Bug Summary

File:lib/CodeGen/CodeGenPrepare.cpp
Warning:line 5915, column 3
Undefined or garbage value returned to caller

Annotated Source Code

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clang -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name CodeGenPrepare.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mthread-model posix -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debugger-tuning=gdb -momit-leaf-frame-pointer -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-9/lib/clang/9.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-9~svn359999/build-llvm/lib/CodeGen -I /build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen -I /build/llvm-toolchain-snapshot-9~svn359999/build-llvm/include -I /build/llvm-toolchain-snapshot-9~svn359999/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0/backward -internal-isystem /usr/include/clang/9.0.0/include/ -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-9/lib/clang/9.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-comment -std=c++11 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-9~svn359999/build-llvm/lib/CodeGen -fdebug-prefix-map=/build/llvm-toolchain-snapshot-9~svn359999=. -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -stack-protector 2 -fobjc-runtime=gcc -fdiagnostics-show-option -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -o /tmp/scan-build-2019-05-06-051613-19774-1 -x c++ /build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp -faddrsig
1//===- CodeGenPrepare.cpp - Prepare a function for code generation --------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This pass munges the code in the input function to better prepare it for
10// SelectionDAG-based code generation. This works around limitations in it's
11// basic-block-at-a-time approach. It should eventually be removed.
12//
13//===----------------------------------------------------------------------===//
14
15#include "llvm/ADT/APInt.h"
16#include "llvm/ADT/ArrayRef.h"
17#include "llvm/ADT/DenseMap.h"
18#include "llvm/ADT/MapVector.h"
19#include "llvm/ADT/PointerIntPair.h"
20#include "llvm/ADT/STLExtras.h"
21#include "llvm/ADT/SmallPtrSet.h"
22#include "llvm/ADT/SmallVector.h"
23#include "llvm/ADT/Statistic.h"
24#include "llvm/Analysis/BlockFrequencyInfo.h"
25#include "llvm/Analysis/BranchProbabilityInfo.h"
26#include "llvm/Analysis/ConstantFolding.h"
27#include "llvm/Analysis/InstructionSimplify.h"
28#include "llvm/Analysis/LoopInfo.h"
29#include "llvm/Analysis/MemoryBuiltins.h"
30#include "llvm/Analysis/ProfileSummaryInfo.h"
31#include "llvm/Analysis/TargetLibraryInfo.h"
32#include "llvm/Analysis/TargetTransformInfo.h"
33#include "llvm/Transforms/Utils/Local.h"
34#include "llvm/Analysis/ValueTracking.h"
35#include "llvm/CodeGen/Analysis.h"
36#include "llvm/CodeGen/ISDOpcodes.h"
37#include "llvm/CodeGen/SelectionDAGNodes.h"
38#include "llvm/CodeGen/TargetLowering.h"
39#include "llvm/CodeGen/TargetPassConfig.h"
40#include "llvm/CodeGen/TargetSubtargetInfo.h"
41#include "llvm/CodeGen/ValueTypes.h"
42#include "llvm/Config/llvm-config.h"
43#include "llvm/IR/Argument.h"
44#include "llvm/IR/Attributes.h"
45#include "llvm/IR/BasicBlock.h"
46#include "llvm/IR/CallSite.h"
47#include "llvm/IR/Constant.h"
48#include "llvm/IR/Constants.h"
49#include "llvm/IR/DataLayout.h"
50#include "llvm/IR/DerivedTypes.h"
51#include "llvm/IR/Dominators.h"
52#include "llvm/IR/Function.h"
53#include "llvm/IR/GetElementPtrTypeIterator.h"
54#include "llvm/IR/GlobalValue.h"
55#include "llvm/IR/GlobalVariable.h"
56#include "llvm/IR/IRBuilder.h"
57#include "llvm/IR/InlineAsm.h"
58#include "llvm/IR/InstrTypes.h"
59#include "llvm/IR/Instruction.h"
60#include "llvm/IR/Instructions.h"
61#include "llvm/IR/IntrinsicInst.h"
62#include "llvm/IR/Intrinsics.h"
63#include "llvm/IR/LLVMContext.h"
64#include "llvm/IR/MDBuilder.h"
65#include "llvm/IR/Module.h"
66#include "llvm/IR/Operator.h"
67#include "llvm/IR/PatternMatch.h"
68#include "llvm/IR/Statepoint.h"
69#include "llvm/IR/Type.h"
70#include "llvm/IR/Use.h"
71#include "llvm/IR/User.h"
72#include "llvm/IR/Value.h"
73#include "llvm/IR/ValueHandle.h"
74#include "llvm/IR/ValueMap.h"
75#include "llvm/Pass.h"
76#include "llvm/Support/BlockFrequency.h"
77#include "llvm/Support/BranchProbability.h"
78#include "llvm/Support/Casting.h"
79#include "llvm/Support/CommandLine.h"
80#include "llvm/Support/Compiler.h"
81#include "llvm/Support/Debug.h"
82#include "llvm/Support/ErrorHandling.h"
83#include "llvm/Support/MachineValueType.h"
84#include "llvm/Support/MathExtras.h"
85#include "llvm/Support/raw_ostream.h"
86#include "llvm/Target/TargetMachine.h"
87#include "llvm/Target/TargetOptions.h"
88#include "llvm/Transforms/Utils/BasicBlockUtils.h"
89#include "llvm/Transforms/Utils/BypassSlowDivision.h"
90#include "llvm/Transforms/Utils/SimplifyLibCalls.h"
91#include <algorithm>
92#include <cassert>
93#include <cstdint>
94#include <iterator>
95#include <limits>
96#include <memory>
97#include <utility>
98#include <vector>
99
100using namespace llvm;
101using namespace llvm::PatternMatch;
102
103#define DEBUG_TYPE"codegenprepare" "codegenprepare"
104
105STATISTIC(NumBlocksElim, "Number of blocks eliminated")static llvm::Statistic NumBlocksElim = {"codegenprepare", "NumBlocksElim"
, "Number of blocks eliminated", {0}, {false}}
;
106STATISTIC(NumPHIsElim, "Number of trivial PHIs eliminated")static llvm::Statistic NumPHIsElim = {"codegenprepare", "NumPHIsElim"
, "Number of trivial PHIs eliminated", {0}, {false}}
;
107STATISTIC(NumGEPsElim, "Number of GEPs converted to casts")static llvm::Statistic NumGEPsElim = {"codegenprepare", "NumGEPsElim"
, "Number of GEPs converted to casts", {0}, {false}}
;
108STATISTIC(NumCmpUses, "Number of uses of Cmp expressions replaced with uses of "static llvm::Statistic NumCmpUses = {"codegenprepare", "NumCmpUses"
, "Number of uses of Cmp expressions replaced with uses of " "sunken Cmps"
, {0}, {false}}
109 "sunken Cmps")static llvm::Statistic NumCmpUses = {"codegenprepare", "NumCmpUses"
, "Number of uses of Cmp expressions replaced with uses of " "sunken Cmps"
, {0}, {false}}
;
110STATISTIC(NumCastUses, "Number of uses of Cast expressions replaced with uses "static llvm::Statistic NumCastUses = {"codegenprepare", "NumCastUses"
, "Number of uses of Cast expressions replaced with uses " "of sunken Casts"
, {0}, {false}}
111 "of sunken Casts")static llvm::Statistic NumCastUses = {"codegenprepare", "NumCastUses"
, "Number of uses of Cast expressions replaced with uses " "of sunken Casts"
, {0}, {false}}
;
112STATISTIC(NumMemoryInsts, "Number of memory instructions whose address "static llvm::Statistic NumMemoryInsts = {"codegenprepare", "NumMemoryInsts"
, "Number of memory instructions whose address " "computations were sunk"
, {0}, {false}}
113 "computations were sunk")static llvm::Statistic NumMemoryInsts = {"codegenprepare", "NumMemoryInsts"
, "Number of memory instructions whose address " "computations were sunk"
, {0}, {false}}
;
114STATISTIC(NumMemoryInstsPhiCreated,static llvm::Statistic NumMemoryInstsPhiCreated = {"codegenprepare"
, "NumMemoryInstsPhiCreated", "Number of phis created when address "
"computations were sunk to memory instructions", {0}, {false
}}
115 "Number of phis created when address "static llvm::Statistic NumMemoryInstsPhiCreated = {"codegenprepare"
, "NumMemoryInstsPhiCreated", "Number of phis created when address "
"computations were sunk to memory instructions", {0}, {false
}}
116 "computations were sunk to memory instructions")static llvm::Statistic NumMemoryInstsPhiCreated = {"codegenprepare"
, "NumMemoryInstsPhiCreated", "Number of phis created when address "
"computations were sunk to memory instructions", {0}, {false
}}
;
117STATISTIC(NumMemoryInstsSelectCreated,static llvm::Statistic NumMemoryInstsSelectCreated = {"codegenprepare"
, "NumMemoryInstsSelectCreated", "Number of select created when address "
"computations were sunk to memory instructions", {0}, {false
}}
118 "Number of select created when address "static llvm::Statistic NumMemoryInstsSelectCreated = {"codegenprepare"
, "NumMemoryInstsSelectCreated", "Number of select created when address "
"computations were sunk to memory instructions", {0}, {false
}}
119 "computations were sunk to memory instructions")static llvm::Statistic NumMemoryInstsSelectCreated = {"codegenprepare"
, "NumMemoryInstsSelectCreated", "Number of select created when address "
"computations were sunk to memory instructions", {0}, {false
}}
;
120STATISTIC(NumExtsMoved, "Number of [s|z]ext instructions combined with loads")static llvm::Statistic NumExtsMoved = {"codegenprepare", "NumExtsMoved"
, "Number of [s|z]ext instructions combined with loads", {0},
{false}}
;
121STATISTIC(NumExtUses, "Number of uses of [s|z]ext instructions optimized")static llvm::Statistic NumExtUses = {"codegenprepare", "NumExtUses"
, "Number of uses of [s|z]ext instructions optimized", {0}, {
false}}
;
122STATISTIC(NumAndsAdded,static llvm::Statistic NumAndsAdded = {"codegenprepare", "NumAndsAdded"
, "Number of and mask instructions added to form ext loads", {
0}, {false}}
123 "Number of and mask instructions added to form ext loads")static llvm::Statistic NumAndsAdded = {"codegenprepare", "NumAndsAdded"
, "Number of and mask instructions added to form ext loads", {
0}, {false}}
;
124STATISTIC(NumAndUses, "Number of uses of and mask instructions optimized")static llvm::Statistic NumAndUses = {"codegenprepare", "NumAndUses"
, "Number of uses of and mask instructions optimized", {0}, {
false}}
;
125STATISTIC(NumRetsDup, "Number of return instructions duplicated")static llvm::Statistic NumRetsDup = {"codegenprepare", "NumRetsDup"
, "Number of return instructions duplicated", {0}, {false}}
;
126STATISTIC(NumDbgValueMoved, "Number of debug value instructions moved")static llvm::Statistic NumDbgValueMoved = {"codegenprepare", "NumDbgValueMoved"
, "Number of debug value instructions moved", {0}, {false}}
;
127STATISTIC(NumSelectsExpanded, "Number of selects turned into branches")static llvm::Statistic NumSelectsExpanded = {"codegenprepare"
, "NumSelectsExpanded", "Number of selects turned into branches"
, {0}, {false}}
;
128STATISTIC(NumStoreExtractExposed, "Number of store(extractelement) exposed")static llvm::Statistic NumStoreExtractExposed = {"codegenprepare"
, "NumStoreExtractExposed", "Number of store(extractelement) exposed"
, {0}, {false}}
;
129
130static cl::opt<bool> DisableBranchOpts(
131 "disable-cgp-branch-opts", cl::Hidden, cl::init(false),
132 cl::desc("Disable branch optimizations in CodeGenPrepare"));
133
134static cl::opt<bool>
135 DisableGCOpts("disable-cgp-gc-opts", cl::Hidden, cl::init(false),
136 cl::desc("Disable GC optimizations in CodeGenPrepare"));
137
138static cl::opt<bool> DisableSelectToBranch(
139 "disable-cgp-select2branch", cl::Hidden, cl::init(false),
140 cl::desc("Disable select to branch conversion."));
141
142static cl::opt<bool> AddrSinkUsingGEPs(
143 "addr-sink-using-gep", cl::Hidden, cl::init(true),
144 cl::desc("Address sinking in CGP using GEPs."));
145
146static cl::opt<bool> EnableAndCmpSinking(
147 "enable-andcmp-sinking", cl::Hidden, cl::init(true),
148 cl::desc("Enable sinkinig and/cmp into branches."));
149
150static cl::opt<bool> DisableStoreExtract(
151 "disable-cgp-store-extract", cl::Hidden, cl::init(false),
152 cl::desc("Disable store(extract) optimizations in CodeGenPrepare"));
153
154static cl::opt<bool> StressStoreExtract(
155 "stress-cgp-store-extract", cl::Hidden, cl::init(false),
156 cl::desc("Stress test store(extract) optimizations in CodeGenPrepare"));
157
158static cl::opt<bool> DisableExtLdPromotion(
159 "disable-cgp-ext-ld-promotion", cl::Hidden, cl::init(false),
160 cl::desc("Disable ext(promotable(ld)) -> promoted(ext(ld)) optimization in "
161 "CodeGenPrepare"));
162
163static cl::opt<bool> StressExtLdPromotion(
164 "stress-cgp-ext-ld-promotion", cl::Hidden, cl::init(false),
165 cl::desc("Stress test ext(promotable(ld)) -> promoted(ext(ld)) "
166 "optimization in CodeGenPrepare"));
167
168static cl::opt<bool> DisablePreheaderProtect(
169 "disable-preheader-prot", cl::Hidden, cl::init(false),
170 cl::desc("Disable protection against removing loop preheaders"));
171
172static cl::opt<bool> ProfileGuidedSectionPrefix(
173 "profile-guided-section-prefix", cl::Hidden, cl::init(true), cl::ZeroOrMore,
174 cl::desc("Use profile info to add section prefix for hot/cold functions"));
175
176static cl::opt<unsigned> FreqRatioToSkipMerge(
177 "cgp-freq-ratio-to-skip-merge", cl::Hidden, cl::init(2),
178 cl::desc("Skip merging empty blocks if (frequency of empty block) / "
179 "(frequency of destination block) is greater than this ratio"));
180
181static cl::opt<bool> ForceSplitStore(
182 "force-split-store", cl::Hidden, cl::init(false),
183 cl::desc("Force store splitting no matter what the target query says."));
184
185static cl::opt<bool>
186EnableTypePromotionMerge("cgp-type-promotion-merge", cl::Hidden,
187 cl::desc("Enable merging of redundant sexts when one is dominating"
188 " the other."), cl::init(true));
189
190static cl::opt<bool> DisableComplexAddrModes(
191 "disable-complex-addr-modes", cl::Hidden, cl::init(false),
192 cl::desc("Disables combining addressing modes with different parts "
193 "in optimizeMemoryInst."));
194
195static cl::opt<bool>
196AddrSinkNewPhis("addr-sink-new-phis", cl::Hidden, cl::init(false),
197 cl::desc("Allow creation of Phis in Address sinking."));
198
199static cl::opt<bool>
200AddrSinkNewSelects("addr-sink-new-select", cl::Hidden, cl::init(true),
201 cl::desc("Allow creation of selects in Address sinking."));
202
203static cl::opt<bool> AddrSinkCombineBaseReg(
204 "addr-sink-combine-base-reg", cl::Hidden, cl::init(true),
205 cl::desc("Allow combining of BaseReg field in Address sinking."));
206
207static cl::opt<bool> AddrSinkCombineBaseGV(
208 "addr-sink-combine-base-gv", cl::Hidden, cl::init(true),
209 cl::desc("Allow combining of BaseGV field in Address sinking."));
210
211static cl::opt<bool> AddrSinkCombineBaseOffs(
212 "addr-sink-combine-base-offs", cl::Hidden, cl::init(true),
213 cl::desc("Allow combining of BaseOffs field in Address sinking."));
214
215static cl::opt<bool> AddrSinkCombineScaledReg(
216 "addr-sink-combine-scaled-reg", cl::Hidden, cl::init(true),
217 cl::desc("Allow combining of ScaledReg field in Address sinking."));
218
219static cl::opt<bool>
220 EnableGEPOffsetSplit("cgp-split-large-offset-gep", cl::Hidden,
221 cl::init(true),
222 cl::desc("Enable splitting large offset of GEP."));
223
224namespace {
225
226enum ExtType {
227 ZeroExtension, // Zero extension has been seen.
228 SignExtension, // Sign extension has been seen.
229 BothExtension // This extension type is used if we saw sext after
230 // ZeroExtension had been set, or if we saw zext after
231 // SignExtension had been set. It makes the type
232 // information of a promoted instruction invalid.
233};
234
235using SetOfInstrs = SmallPtrSet<Instruction *, 16>;
236using TypeIsSExt = PointerIntPair<Type *, 2, ExtType>;
237using InstrToOrigTy = DenseMap<Instruction *, TypeIsSExt>;
238using SExts = SmallVector<Instruction *, 16>;
239using ValueToSExts = DenseMap<Value *, SExts>;
240
241class TypePromotionTransaction;
242
243 class CodeGenPrepare : public FunctionPass {
244 const TargetMachine *TM = nullptr;
245 const TargetSubtargetInfo *SubtargetInfo;
246 const TargetLowering *TLI = nullptr;
247 const TargetRegisterInfo *TRI;
248 const TargetTransformInfo *TTI = nullptr;
249 const TargetLibraryInfo *TLInfo;
250 const LoopInfo *LI;
251 std::unique_ptr<BlockFrequencyInfo> BFI;
252 std::unique_ptr<BranchProbabilityInfo> BPI;
253
254 /// As we scan instructions optimizing them, this is the next instruction
255 /// to optimize. Transforms that can invalidate this should update it.
256 BasicBlock::iterator CurInstIterator;
257
258 /// Keeps track of non-local addresses that have been sunk into a block.
259 /// This allows us to avoid inserting duplicate code for blocks with
260 /// multiple load/stores of the same address. The usage of WeakTrackingVH
261 /// enables SunkAddrs to be treated as a cache whose entries can be
262 /// invalidated if a sunken address computation has been erased.
263 ValueMap<Value*, WeakTrackingVH> SunkAddrs;
264
265 /// Keeps track of all instructions inserted for the current function.
266 SetOfInstrs InsertedInsts;
267
268 /// Keeps track of the type of the related instruction before their
269 /// promotion for the current function.
270 InstrToOrigTy PromotedInsts;
271
272 /// Keep track of instructions removed during promotion.
273 SetOfInstrs RemovedInsts;
274
275 /// Keep track of sext chains based on their initial value.
276 DenseMap<Value *, Instruction *> SeenChainsForSExt;
277
278 /// Keep track of GEPs accessing the same data structures such as structs or
279 /// arrays that are candidates to be split later because of their large
280 /// size.
281 MapVector<
282 AssertingVH<Value>,
283 SmallVector<std::pair<AssertingVH<GetElementPtrInst>, int64_t>, 32>>
284 LargeOffsetGEPMap;
285
286 /// Keep track of new GEP base after splitting the GEPs having large offset.
287 SmallSet<AssertingVH<Value>, 2> NewGEPBases;
288
289 /// Map serial numbers to Large offset GEPs.
290 DenseMap<AssertingVH<GetElementPtrInst>, int> LargeOffsetGEPID;
291
292 /// Keep track of SExt promoted.
293 ValueToSExts ValToSExtendedUses;
294
295 /// True if optimizing for size.
296 bool OptSize;
297
298 /// DataLayout for the Function being processed.
299 const DataLayout *DL = nullptr;
300
301 /// Building the dominator tree can be expensive, so we only build it
302 /// lazily and update it when required.
303 std::unique_ptr<DominatorTree> DT;
304
305 public:
306 static char ID; // Pass identification, replacement for typeid
307
308 CodeGenPrepare() : FunctionPass(ID) {
309 initializeCodeGenPreparePass(*PassRegistry::getPassRegistry());
310 }
311
312 bool runOnFunction(Function &F) override;
313
314 StringRef getPassName() const override { return "CodeGen Prepare"; }
315
316 void getAnalysisUsage(AnalysisUsage &AU) const override {
317 // FIXME: When we can selectively preserve passes, preserve the domtree.
318 AU.addRequired<ProfileSummaryInfoWrapperPass>();
319 AU.addRequired<TargetLibraryInfoWrapperPass>();
320 AU.addRequired<TargetTransformInfoWrapperPass>();
321 AU.addRequired<LoopInfoWrapperPass>();
322 }
323
324 private:
325 template <typename F>
326 void resetIteratorIfInvalidatedWhileCalling(BasicBlock *BB, F f) {
327 // Substituting can cause recursive simplifications, which can invalidate
328 // our iterator. Use a WeakTrackingVH to hold onto it in case this
329 // happens.
330 Value *CurValue = &*CurInstIterator;
331 WeakTrackingVH IterHandle(CurValue);
332
333 f();
334
335 // If the iterator instruction was recursively deleted, start over at the
336 // start of the block.
337 if (IterHandle != CurValue) {
338 CurInstIterator = BB->begin();
339 SunkAddrs.clear();
340 }
341 }
342
343 // Get the DominatorTree, building if necessary.
344 DominatorTree &getDT(Function &F) {
345 if (!DT)
346 DT = llvm::make_unique<DominatorTree>(F);
347 return *DT;
348 }
349
350 bool eliminateFallThrough(Function &F);
351 bool eliminateMostlyEmptyBlocks(Function &F);
352 BasicBlock *findDestBlockOfMergeableEmptyBlock(BasicBlock *BB);
353 bool canMergeBlocks(const BasicBlock *BB, const BasicBlock *DestBB) const;
354 void eliminateMostlyEmptyBlock(BasicBlock *BB);
355 bool isMergingEmptyBlockProfitable(BasicBlock *BB, BasicBlock *DestBB,
356 bool isPreheader);
357 bool optimizeBlock(BasicBlock &BB, bool &ModifiedDT);
358 bool optimizeInst(Instruction *I, bool &ModifiedDT);
359 bool optimizeMemoryInst(Instruction *MemoryInst, Value *Addr,
360 Type *AccessTy, unsigned AddrSpace);
361 bool optimizeInlineAsmInst(CallInst *CS);
362 bool optimizeCallInst(CallInst *CI, bool &ModifiedDT);
363 bool optimizeExt(Instruction *&I);
364 bool optimizeExtUses(Instruction *I);
365 bool optimizeLoadExt(LoadInst *Load);
366 bool optimizeSelectInst(SelectInst *SI);
367 bool optimizeShuffleVectorInst(ShuffleVectorInst *SVI);
368 bool optimizeSwitchInst(SwitchInst *SI);
369 bool optimizeExtractElementInst(Instruction *Inst);
370 bool dupRetToEnableTailCallOpts(BasicBlock *BB, bool &ModifiedDT);
371 bool placeDbgValues(Function &F);
372 bool canFormExtLd(const SmallVectorImpl<Instruction *> &MovedExts,
373 LoadInst *&LI, Instruction *&Inst, bool HasPromoted);
374 bool tryToPromoteExts(TypePromotionTransaction &TPT,
375 const SmallVectorImpl<Instruction *> &Exts,
376 SmallVectorImpl<Instruction *> &ProfitablyMovedExts,
377 unsigned CreatedInstsCost = 0);
378 bool mergeSExts(Function &F);
379 bool splitLargeGEPOffsets();
380 bool performAddressTypePromotion(
381 Instruction *&Inst,
382 bool AllowPromotionWithoutCommonHeader,
383 bool HasPromoted, TypePromotionTransaction &TPT,
384 SmallVectorImpl<Instruction *> &SpeculativelyMovedExts);
385 bool splitBranchCondition(Function &F, bool &ModifiedDT);
386 bool simplifyOffsetableRelocate(Instruction &I);
387
388 bool tryToSinkFreeOperands(Instruction *I);
389 bool replaceMathCmpWithIntrinsic(BinaryOperator *BO, CmpInst *Cmp,
390 Intrinsic::ID IID);
391 bool optimizeCmp(CmpInst *Cmp, bool &ModifiedDT);
392 bool combineToUSubWithOverflow(CmpInst *Cmp, bool &ModifiedDT);
393 bool combineToUAddWithOverflow(CmpInst *Cmp, bool &ModifiedDT);
394 };
395
396} // end anonymous namespace
397
398char CodeGenPrepare::ID = 0;
399
400INITIALIZE_PASS_BEGIN(CodeGenPrepare, DEBUG_TYPE,static void *initializeCodeGenPreparePassOnce(PassRegistry &
Registry) {
401 "Optimize for code generation", false, false)static void *initializeCodeGenPreparePassOnce(PassRegistry &
Registry) {
402INITIALIZE_PASS_DEPENDENCY(ProfileSummaryInfoWrapperPass)initializeProfileSummaryInfoWrapperPassPass(Registry);
403INITIALIZE_PASS_END(CodeGenPrepare, DEBUG_TYPE,PassInfo *PI = new PassInfo( "Optimize for code generation", "codegenprepare"
, &CodeGenPrepare::ID, PassInfo::NormalCtor_t(callDefaultCtor
<CodeGenPrepare>), false, false); Registry.registerPass
(*PI, true); return PI; } static llvm::once_flag InitializeCodeGenPreparePassFlag
; void llvm::initializeCodeGenPreparePass(PassRegistry &Registry
) { llvm::call_once(InitializeCodeGenPreparePassFlag, initializeCodeGenPreparePassOnce
, std::ref(Registry)); }
404 "Optimize for code generation", false, false)PassInfo *PI = new PassInfo( "Optimize for code generation", "codegenprepare"
, &CodeGenPrepare::ID, PassInfo::NormalCtor_t(callDefaultCtor
<CodeGenPrepare>), false, false); Registry.registerPass
(*PI, true); return PI; } static llvm::once_flag InitializeCodeGenPreparePassFlag
; void llvm::initializeCodeGenPreparePass(PassRegistry &Registry
) { llvm::call_once(InitializeCodeGenPreparePassFlag, initializeCodeGenPreparePassOnce
, std::ref(Registry)); }
405
406FunctionPass *llvm::createCodeGenPreparePass() { return new CodeGenPrepare(); }
407
408bool CodeGenPrepare::runOnFunction(Function &F) {
409 if (skipFunction(F))
1
Assuming the condition is false
2
Taking false branch
410 return false;
411
412 DL = &F.getParent()->getDataLayout();
413
414 bool EverMadeChange = false;
415 // Clear per function information.
416 InsertedInsts.clear();
417 PromotedInsts.clear();
418
419 if (auto *TPC = getAnalysisIfAvailable<TargetPassConfig>()) {
3
Assuming 'TPC' is null
4
Taking false branch
420 TM = &TPC->getTM<TargetMachine>();
421 SubtargetInfo = TM->getSubtargetImpl(F);
422 TLI = SubtargetInfo->getTargetLowering();
423 TRI = SubtargetInfo->getRegisterInfo();
424 }
425 TLInfo = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
426 TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
427 LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
428 BPI.reset(new BranchProbabilityInfo(F, *LI));
429 BFI.reset(new BlockFrequencyInfo(F, *BPI, *LI));
430 OptSize = F.hasOptSize();
431
432 ProfileSummaryInfo *PSI =
433 &getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();
434 if (ProfileGuidedSectionPrefix) {
5
Assuming the condition is false
6
Taking false branch
435 if (PSI->isFunctionHotInCallGraph(&F, *BFI))
436 F.setSectionPrefix(".hot");
437 else if (PSI->isFunctionColdInCallGraph(&F, *BFI))
438 F.setSectionPrefix(".unlikely");
439 }
440
441 /// This optimization identifies DIV instructions that can be
442 /// profitably bypassed and carried out with a shorter, faster divide.
443 if (!OptSize && !PSI->hasHugeWorkingSetSize() && TLI &&
7
Assuming the condition is false
444 TLI->isSlowDivBypassed()) {
445 const DenseMap<unsigned int, unsigned int> &BypassWidths =
446 TLI->getBypassSlowDivWidths();
447 BasicBlock* BB = &*F.begin();
448 while (BB != nullptr) {
449 // bypassSlowDivision may create new BBs, but we don't want to reapply the
450 // optimization to those blocks.
451 BasicBlock* Next = BB->getNextNode();
452 EverMadeChange |= bypassSlowDivision(BB, BypassWidths);
453 BB = Next;
454 }
455 }
456
457 // Eliminate blocks that contain only PHI nodes and an
458 // unconditional branch.
459 EverMadeChange |= eliminateMostlyEmptyBlocks(F);
460
461 bool ModifiedDT = false;
462 if (!DisableBranchOpts)
8
Assuming the condition is false
9
Taking false branch
463 EverMadeChange |= splitBranchCondition(F, ModifiedDT);
464
465 // Split some critical edges where one of the sources is an indirect branch,
466 // to help generate sane code for PHIs involving such edges.
467 EverMadeChange |= SplitIndirectBrCriticalEdges(F);
468
469 bool MadeChange = true;
470 while (MadeChange) {
10
Loop condition is true. Entering loop body
471 MadeChange = false;
472 DT.reset();
473 for (Function::iterator I = F.begin(); I != F.end(); ) {
11
Loop condition is true. Entering loop body
474 BasicBlock *BB = &*I++;
475 bool ModifiedDTOnIteration = false;
476 MadeChange |= optimizeBlock(*BB, ModifiedDTOnIteration);
12
Calling 'CodeGenPrepare::optimizeBlock'
477
478 // Restart BB iteration if the dominator tree of the Function was changed
479 if (ModifiedDTOnIteration)
480 break;
481 }
482 if (EnableTypePromotionMerge && !ValToSExtendedUses.empty())
483 MadeChange |= mergeSExts(F);
484 if (!LargeOffsetGEPMap.empty())
485 MadeChange |= splitLargeGEPOffsets();
486
487 // Really free removed instructions during promotion.
488 for (Instruction *I : RemovedInsts)
489 I->deleteValue();
490
491 EverMadeChange |= MadeChange;
492 SeenChainsForSExt.clear();
493 ValToSExtendedUses.clear();
494 RemovedInsts.clear();
495 LargeOffsetGEPMap.clear();
496 LargeOffsetGEPID.clear();
497 }
498
499 SunkAddrs.clear();
500
501 if (!DisableBranchOpts) {
502 MadeChange = false;
503 // Use a set vector to get deterministic iteration order. The order the
504 // blocks are removed may affect whether or not PHI nodes in successors
505 // are removed.
506 SmallSetVector<BasicBlock*, 8> WorkList;
507 for (BasicBlock &BB : F) {
508 SmallVector<BasicBlock *, 2> Successors(succ_begin(&BB), succ_end(&BB));
509 MadeChange |= ConstantFoldTerminator(&BB, true);
510 if (!MadeChange) continue;
511
512 for (SmallVectorImpl<BasicBlock*>::iterator
513 II = Successors.begin(), IE = Successors.end(); II != IE; ++II)
514 if (pred_begin(*II) == pred_end(*II))
515 WorkList.insert(*II);
516 }
517
518 // Delete the dead blocks and any of their dead successors.
519 MadeChange |= !WorkList.empty();
520 while (!WorkList.empty()) {
521 BasicBlock *BB = WorkList.pop_back_val();
522 SmallVector<BasicBlock*, 2> Successors(succ_begin(BB), succ_end(BB));
523
524 DeleteDeadBlock(BB);
525
526 for (SmallVectorImpl<BasicBlock*>::iterator
527 II = Successors.begin(), IE = Successors.end(); II != IE; ++II)
528 if (pred_begin(*II) == pred_end(*II))
529 WorkList.insert(*II);
530 }
531
532 // Merge pairs of basic blocks with unconditional branches, connected by
533 // a single edge.
534 if (EverMadeChange || MadeChange)
535 MadeChange |= eliminateFallThrough(F);
536
537 EverMadeChange |= MadeChange;
538 }
539
540 if (!DisableGCOpts) {
541 SmallVector<Instruction *, 2> Statepoints;
542 for (BasicBlock &BB : F)
543 for (Instruction &I : BB)
544 if (isStatepoint(I))
545 Statepoints.push_back(&I);
546 for (auto &I : Statepoints)
547 EverMadeChange |= simplifyOffsetableRelocate(*I);
548 }
549
550 // Do this last to clean up use-before-def scenarios introduced by other
551 // preparatory transforms.
552 EverMadeChange |= placeDbgValues(F);
553
554 return EverMadeChange;
555}
556
557/// Merge basic blocks which are connected by a single edge, where one of the
558/// basic blocks has a single successor pointing to the other basic block,
559/// which has a single predecessor.
560bool CodeGenPrepare::eliminateFallThrough(Function &F) {
561 bool Changed = false;
562 // Scan all of the blocks in the function, except for the entry block.
563 // Use a temporary array to avoid iterator being invalidated when
564 // deleting blocks.
565 SmallVector<WeakTrackingVH, 16> Blocks;
566 for (auto &Block : llvm::make_range(std::next(F.begin()), F.end()))
567 Blocks.push_back(&Block);
568
569 for (auto &Block : Blocks) {
570 auto *BB = cast_or_null<BasicBlock>(Block);
571 if (!BB)
572 continue;
573 // If the destination block has a single pred, then this is a trivial
574 // edge, just collapse it.
575 BasicBlock *SinglePred = BB->getSinglePredecessor();
576
577 // Don't merge if BB's address is taken.
578 if (!SinglePred || SinglePred == BB || BB->hasAddressTaken()) continue;
579
580 BranchInst *Term = dyn_cast<BranchInst>(SinglePred->getTerminator());
581 if (Term && !Term->isConditional()) {
582 Changed = true;
583 LLVM_DEBUG(dbgs() << "To merge:\n" << *BB << "\n\n\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "To merge:\n" << *
BB << "\n\n\n"; } } while (false)
;
584
585 // Merge BB into SinglePred and delete it.
586 MergeBlockIntoPredecessor(BB);
587 }
588 }
589 return Changed;
590}
591
592/// Find a destination block from BB if BB is mergeable empty block.
593BasicBlock *CodeGenPrepare::findDestBlockOfMergeableEmptyBlock(BasicBlock *BB) {
594 // If this block doesn't end with an uncond branch, ignore it.
595 BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator());
596 if (!BI || !BI->isUnconditional())
597 return nullptr;
598
599 // If the instruction before the branch (skipping debug info) isn't a phi
600 // node, then other stuff is happening here.
601 BasicBlock::iterator BBI = BI->getIterator();
602 if (BBI != BB->begin()) {
603 --BBI;
604 while (isa<DbgInfoIntrinsic>(BBI)) {
605 if (BBI == BB->begin())
606 break;
607 --BBI;
608 }
609 if (!isa<DbgInfoIntrinsic>(BBI) && !isa<PHINode>(BBI))
610 return nullptr;
611 }
612
613 // Do not break infinite loops.
614 BasicBlock *DestBB = BI->getSuccessor(0);
615 if (DestBB == BB)
616 return nullptr;
617
618 if (!canMergeBlocks(BB, DestBB))
619 DestBB = nullptr;
620
621 return DestBB;
622}
623
624/// Eliminate blocks that contain only PHI nodes, debug info directives, and an
625/// unconditional branch. Passes before isel (e.g. LSR/loopsimplify) often split
626/// edges in ways that are non-optimal for isel. Start by eliminating these
627/// blocks so we can split them the way we want them.
628bool CodeGenPrepare::eliminateMostlyEmptyBlocks(Function &F) {
629 SmallPtrSet<BasicBlock *, 16> Preheaders;
630 SmallVector<Loop *, 16> LoopList(LI->begin(), LI->end());
631 while (!LoopList.empty()) {
632 Loop *L = LoopList.pop_back_val();
633 LoopList.insert(LoopList.end(), L->begin(), L->end());
634 if (BasicBlock *Preheader = L->getLoopPreheader())
635 Preheaders.insert(Preheader);
636 }
637
638 bool MadeChange = false;
639 // Copy blocks into a temporary array to avoid iterator invalidation issues
640 // as we remove them.
641 // Note that this intentionally skips the entry block.
642 SmallVector<WeakTrackingVH, 16> Blocks;
643 for (auto &Block : llvm::make_range(std::next(F.begin()), F.end()))
644 Blocks.push_back(&Block);
645
646 for (auto &Block : Blocks) {
647 BasicBlock *BB = cast_or_null<BasicBlock>(Block);
648 if (!BB)
649 continue;
650 BasicBlock *DestBB = findDestBlockOfMergeableEmptyBlock(BB);
651 if (!DestBB ||
652 !isMergingEmptyBlockProfitable(BB, DestBB, Preheaders.count(BB)))
653 continue;
654
655 eliminateMostlyEmptyBlock(BB);
656 MadeChange = true;
657 }
658 return MadeChange;
659}
660
661bool CodeGenPrepare::isMergingEmptyBlockProfitable(BasicBlock *BB,
662 BasicBlock *DestBB,
663 bool isPreheader) {
664 // Do not delete loop preheaders if doing so would create a critical edge.
665 // Loop preheaders can be good locations to spill registers. If the
666 // preheader is deleted and we create a critical edge, registers may be
667 // spilled in the loop body instead.
668 if (!DisablePreheaderProtect && isPreheader &&
669 !(BB->getSinglePredecessor() &&
670 BB->getSinglePredecessor()->getSingleSuccessor()))
671 return false;
672
673 // Skip merging if the block's successor is also a successor to any callbr
674 // that leads to this block.
675 // FIXME: Is this really needed? Is this a correctness issue?
676 for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
677 if (auto *CBI = dyn_cast<CallBrInst>((*PI)->getTerminator()))
678 for (unsigned i = 0, e = CBI->getNumSuccessors(); i != e; ++i)
679 if (DestBB == CBI->getSuccessor(i))
680 return false;
681 }
682
683 // Try to skip merging if the unique predecessor of BB is terminated by a
684 // switch or indirect branch instruction, and BB is used as an incoming block
685 // of PHIs in DestBB. In such case, merging BB and DestBB would cause ISel to
686 // add COPY instructions in the predecessor of BB instead of BB (if it is not
687 // merged). Note that the critical edge created by merging such blocks wont be
688 // split in MachineSink because the jump table is not analyzable. By keeping
689 // such empty block (BB), ISel will place COPY instructions in BB, not in the
690 // predecessor of BB.
691 BasicBlock *Pred = BB->getUniquePredecessor();
692 if (!Pred ||
693 !(isa<SwitchInst>(Pred->getTerminator()) ||
694 isa<IndirectBrInst>(Pred->getTerminator())))
695 return true;
696
697 if (BB->getTerminator() != BB->getFirstNonPHIOrDbg())
698 return true;
699
700 // We use a simple cost heuristic which determine skipping merging is
701 // profitable if the cost of skipping merging is less than the cost of
702 // merging : Cost(skipping merging) < Cost(merging BB), where the
703 // Cost(skipping merging) is Freq(BB) * (Cost(Copy) + Cost(Branch)), and
704 // the Cost(merging BB) is Freq(Pred) * Cost(Copy).
705 // Assuming Cost(Copy) == Cost(Branch), we could simplify it to :
706 // Freq(Pred) / Freq(BB) > 2.
707 // Note that if there are multiple empty blocks sharing the same incoming
708 // value for the PHIs in the DestBB, we consider them together. In such
709 // case, Cost(merging BB) will be the sum of their frequencies.
710
711 if (!isa<PHINode>(DestBB->begin()))
712 return true;
713
714 SmallPtrSet<BasicBlock *, 16> SameIncomingValueBBs;
715
716 // Find all other incoming blocks from which incoming values of all PHIs in
717 // DestBB are the same as the ones from BB.
718 for (pred_iterator PI = pred_begin(DestBB), E = pred_end(DestBB); PI != E;
719 ++PI) {
720 BasicBlock *DestBBPred = *PI;
721 if (DestBBPred == BB)
722 continue;
723
724 if (llvm::all_of(DestBB->phis(), [&](const PHINode &DestPN) {
725 return DestPN.getIncomingValueForBlock(BB) ==
726 DestPN.getIncomingValueForBlock(DestBBPred);
727 }))
728 SameIncomingValueBBs.insert(DestBBPred);
729 }
730
731 // See if all BB's incoming values are same as the value from Pred. In this
732 // case, no reason to skip merging because COPYs are expected to be place in
733 // Pred already.
734 if (SameIncomingValueBBs.count(Pred))
735 return true;
736
737 BlockFrequency PredFreq = BFI->getBlockFreq(Pred);
738 BlockFrequency BBFreq = BFI->getBlockFreq(BB);
739
740 for (auto SameValueBB : SameIncomingValueBBs)
741 if (SameValueBB->getUniquePredecessor() == Pred &&
742 DestBB == findDestBlockOfMergeableEmptyBlock(SameValueBB))
743 BBFreq += BFI->getBlockFreq(SameValueBB);
744
745 return PredFreq.getFrequency() <=
746 BBFreq.getFrequency() * FreqRatioToSkipMerge;
747}
748
749/// Return true if we can merge BB into DestBB if there is a single
750/// unconditional branch between them, and BB contains no other non-phi
751/// instructions.
752bool CodeGenPrepare::canMergeBlocks(const BasicBlock *BB,
753 const BasicBlock *DestBB) const {
754 // We only want to eliminate blocks whose phi nodes are used by phi nodes in
755 // the successor. If there are more complex condition (e.g. preheaders),
756 // don't mess around with them.
757 for (const PHINode &PN : BB->phis()) {
758 for (const User *U : PN.users()) {
759 const Instruction *UI = cast<Instruction>(U);
760 if (UI->getParent() != DestBB || !isa<PHINode>(UI))
761 return false;
762 // If User is inside DestBB block and it is a PHINode then check
763 // incoming value. If incoming value is not from BB then this is
764 // a complex condition (e.g. preheaders) we want to avoid here.
765 if (UI->getParent() == DestBB) {
766 if (const PHINode *UPN = dyn_cast<PHINode>(UI))
767 for (unsigned I = 0, E = UPN->getNumIncomingValues(); I != E; ++I) {
768 Instruction *Insn = dyn_cast<Instruction>(UPN->getIncomingValue(I));
769 if (Insn && Insn->getParent() == BB &&
770 Insn->getParent() != UPN->getIncomingBlock(I))
771 return false;
772 }
773 }
774 }
775 }
776
777 // If BB and DestBB contain any common predecessors, then the phi nodes in BB
778 // and DestBB may have conflicting incoming values for the block. If so, we
779 // can't merge the block.
780 const PHINode *DestBBPN = dyn_cast<PHINode>(DestBB->begin());
781 if (!DestBBPN) return true; // no conflict.
782
783 // Collect the preds of BB.
784 SmallPtrSet<const BasicBlock*, 16> BBPreds;
785 if (const PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
786 // It is faster to get preds from a PHI than with pred_iterator.
787 for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
788 BBPreds.insert(BBPN->getIncomingBlock(i));
789 } else {
790 BBPreds.insert(pred_begin(BB), pred_end(BB));
791 }
792
793 // Walk the preds of DestBB.
794 for (unsigned i = 0, e = DestBBPN->getNumIncomingValues(); i != e; ++i) {
795 BasicBlock *Pred = DestBBPN->getIncomingBlock(i);
796 if (BBPreds.count(Pred)) { // Common predecessor?
797 for (const PHINode &PN : DestBB->phis()) {
798 const Value *V1 = PN.getIncomingValueForBlock(Pred);
799 const Value *V2 = PN.getIncomingValueForBlock(BB);
800
801 // If V2 is a phi node in BB, look up what the mapped value will be.
802 if (const PHINode *V2PN = dyn_cast<PHINode>(V2))
803 if (V2PN->getParent() == BB)
804 V2 = V2PN->getIncomingValueForBlock(Pred);
805
806 // If there is a conflict, bail out.
807 if (V1 != V2) return false;
808 }
809 }
810 }
811
812 return true;
813}
814
815/// Eliminate a basic block that has only phi's and an unconditional branch in
816/// it.
817void CodeGenPrepare::eliminateMostlyEmptyBlock(BasicBlock *BB) {
818 BranchInst *BI = cast<BranchInst>(BB->getTerminator());
819 BasicBlock *DestBB = BI->getSuccessor(0);
820
821 LLVM_DEBUG(dbgs() << "MERGING MOSTLY EMPTY BLOCKS - BEFORE:\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "MERGING MOSTLY EMPTY BLOCKS - BEFORE:\n"
<< *BB << *DestBB; } } while (false)
822 << *BB << *DestBB)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "MERGING MOSTLY EMPTY BLOCKS - BEFORE:\n"
<< *BB << *DestBB; } } while (false)
;
823
824 // If the destination block has a single pred, then this is a trivial edge,
825 // just collapse it.
826 if (BasicBlock *SinglePred = DestBB->getSinglePredecessor()) {
827 if (SinglePred != DestBB) {
828 assert(SinglePred == BB &&((SinglePred == BB && "Single predecessor not the same as predecessor"
) ? static_cast<void> (0) : __assert_fail ("SinglePred == BB && \"Single predecessor not the same as predecessor\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 829, __PRETTY_FUNCTION__))
829 "Single predecessor not the same as predecessor")((SinglePred == BB && "Single predecessor not the same as predecessor"
) ? static_cast<void> (0) : __assert_fail ("SinglePred == BB && \"Single predecessor not the same as predecessor\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 829, __PRETTY_FUNCTION__))
;
830 // Merge DestBB into SinglePred/BB and delete it.
831 MergeBlockIntoPredecessor(DestBB);
832 // Note: BB(=SinglePred) will not be deleted on this path.
833 // DestBB(=its single successor) is the one that was deleted.
834 LLVM_DEBUG(dbgs() << "AFTER:\n" << *SinglePred << "\n\n\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "AFTER:\n" << *SinglePred
<< "\n\n\n"; } } while (false)
;
835 return;
836 }
837 }
838
839 // Otherwise, we have multiple predecessors of BB. Update the PHIs in DestBB
840 // to handle the new incoming edges it is about to have.
841 for (PHINode &PN : DestBB->phis()) {
842 // Remove the incoming value for BB, and remember it.
843 Value *InVal = PN.removeIncomingValue(BB, false);
844
845 // Two options: either the InVal is a phi node defined in BB or it is some
846 // value that dominates BB.
847 PHINode *InValPhi = dyn_cast<PHINode>(InVal);
848 if (InValPhi && InValPhi->getParent() == BB) {
849 // Add all of the input values of the input PHI as inputs of this phi.
850 for (unsigned i = 0, e = InValPhi->getNumIncomingValues(); i != e; ++i)
851 PN.addIncoming(InValPhi->getIncomingValue(i),
852 InValPhi->getIncomingBlock(i));
853 } else {
854 // Otherwise, add one instance of the dominating value for each edge that
855 // we will be adding.
856 if (PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
857 for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
858 PN.addIncoming(InVal, BBPN->getIncomingBlock(i));
859 } else {
860 for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
861 PN.addIncoming(InVal, *PI);
862 }
863 }
864 }
865
866 // The PHIs are now updated, change everything that refers to BB to use
867 // DestBB and remove BB.
868 BB->replaceAllUsesWith(DestBB);
869 BB->eraseFromParent();
870 ++NumBlocksElim;
871
872 LLVM_DEBUG(dbgs() << "AFTER:\n" << *DestBB << "\n\n\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "AFTER:\n" << *DestBB
<< "\n\n\n"; } } while (false)
;
873}
874
875// Computes a map of base pointer relocation instructions to corresponding
876// derived pointer relocation instructions given a vector of all relocate calls
877static void computeBaseDerivedRelocateMap(
878 const SmallVectorImpl<GCRelocateInst *> &AllRelocateCalls,
879 DenseMap<GCRelocateInst *, SmallVector<GCRelocateInst *, 2>>
880 &RelocateInstMap) {
881 // Collect information in two maps: one primarily for locating the base object
882 // while filling the second map; the second map is the final structure holding
883 // a mapping between Base and corresponding Derived relocate calls
884 DenseMap<std::pair<unsigned, unsigned>, GCRelocateInst *> RelocateIdxMap;
885 for (auto *ThisRelocate : AllRelocateCalls) {
886 auto K = std::make_pair(ThisRelocate->getBasePtrIndex(),
887 ThisRelocate->getDerivedPtrIndex());
888 RelocateIdxMap.insert(std::make_pair(K, ThisRelocate));
889 }
890 for (auto &Item : RelocateIdxMap) {
891 std::pair<unsigned, unsigned> Key = Item.first;
892 if (Key.first == Key.second)
893 // Base relocation: nothing to insert
894 continue;
895
896 GCRelocateInst *I = Item.second;
897 auto BaseKey = std::make_pair(Key.first, Key.first);
898
899 // We're iterating over RelocateIdxMap so we cannot modify it.
900 auto MaybeBase = RelocateIdxMap.find(BaseKey);
901 if (MaybeBase == RelocateIdxMap.end())
902 // TODO: We might want to insert a new base object relocate and gep off
903 // that, if there are enough derived object relocates.
904 continue;
905
906 RelocateInstMap[MaybeBase->second].push_back(I);
907 }
908}
909
910// Accepts a GEP and extracts the operands into a vector provided they're all
911// small integer constants
912static bool getGEPSmallConstantIntOffsetV(GetElementPtrInst *GEP,
913 SmallVectorImpl<Value *> &OffsetV) {
914 for (unsigned i = 1; i < GEP->getNumOperands(); i++) {
915 // Only accept small constant integer operands
916 auto Op = dyn_cast<ConstantInt>(GEP->getOperand(i));
917 if (!Op || Op->getZExtValue() > 20)
918 return false;
919 }
920
921 for (unsigned i = 1; i < GEP->getNumOperands(); i++)
922 OffsetV.push_back(GEP->getOperand(i));
923 return true;
924}
925
926// Takes a RelocatedBase (base pointer relocation instruction) and Targets to
927// replace, computes a replacement, and affects it.
928static bool
929simplifyRelocatesOffABase(GCRelocateInst *RelocatedBase,
930 const SmallVectorImpl<GCRelocateInst *> &Targets) {
931 bool MadeChange = false;
932 // We must ensure the relocation of derived pointer is defined after
933 // relocation of base pointer. If we find a relocation corresponding to base
934 // defined earlier than relocation of base then we move relocation of base
935 // right before found relocation. We consider only relocation in the same
936 // basic block as relocation of base. Relocations from other basic block will
937 // be skipped by optimization and we do not care about them.
938 for (auto R = RelocatedBase->getParent()->getFirstInsertionPt();
939 &*R != RelocatedBase; ++R)
940 if (auto RI = dyn_cast<GCRelocateInst>(R))
941 if (RI->getStatepoint() == RelocatedBase->getStatepoint())
942 if (RI->getBasePtrIndex() == RelocatedBase->getBasePtrIndex()) {
943 RelocatedBase->moveBefore(RI);
944 break;
945 }
946
947 for (GCRelocateInst *ToReplace : Targets) {
948 assert(ToReplace->getBasePtrIndex() == RelocatedBase->getBasePtrIndex() &&((ToReplace->getBasePtrIndex() == RelocatedBase->getBasePtrIndex
() && "Not relocating a derived object of the original base object"
) ? static_cast<void> (0) : __assert_fail ("ToReplace->getBasePtrIndex() == RelocatedBase->getBasePtrIndex() && \"Not relocating a derived object of the original base object\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 949, __PRETTY_FUNCTION__))
949 "Not relocating a derived object of the original base object")((ToReplace->getBasePtrIndex() == RelocatedBase->getBasePtrIndex
() && "Not relocating a derived object of the original base object"
) ? static_cast<void> (0) : __assert_fail ("ToReplace->getBasePtrIndex() == RelocatedBase->getBasePtrIndex() && \"Not relocating a derived object of the original base object\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 949, __PRETTY_FUNCTION__))
;
950 if (ToReplace->getBasePtrIndex() == ToReplace->getDerivedPtrIndex()) {
951 // A duplicate relocate call. TODO: coalesce duplicates.
952 continue;
953 }
954
955 if (RelocatedBase->getParent() != ToReplace->getParent()) {
956 // Base and derived relocates are in different basic blocks.
957 // In this case transform is only valid when base dominates derived
958 // relocate. However it would be too expensive to check dominance
959 // for each such relocate, so we skip the whole transformation.
960 continue;
961 }
962
963 Value *Base = ToReplace->getBasePtr();
964 auto Derived = dyn_cast<GetElementPtrInst>(ToReplace->getDerivedPtr());
965 if (!Derived || Derived->getPointerOperand() != Base)
966 continue;
967
968 SmallVector<Value *, 2> OffsetV;
969 if (!getGEPSmallConstantIntOffsetV(Derived, OffsetV))
970 continue;
971
972 // Create a Builder and replace the target callsite with a gep
973 assert(RelocatedBase->getNextNode() &&((RelocatedBase->getNextNode() && "Should always have one since it's not a terminator"
) ? static_cast<void> (0) : __assert_fail ("RelocatedBase->getNextNode() && \"Should always have one since it's not a terminator\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 974, __PRETTY_FUNCTION__))
974 "Should always have one since it's not a terminator")((RelocatedBase->getNextNode() && "Should always have one since it's not a terminator"
) ? static_cast<void> (0) : __assert_fail ("RelocatedBase->getNextNode() && \"Should always have one since it's not a terminator\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 974, __PRETTY_FUNCTION__))
;
975
976 // Insert after RelocatedBase
977 IRBuilder<> Builder(RelocatedBase->getNextNode());
978 Builder.SetCurrentDebugLocation(ToReplace->getDebugLoc());
979
980 // If gc_relocate does not match the actual type, cast it to the right type.
981 // In theory, there must be a bitcast after gc_relocate if the type does not
982 // match, and we should reuse it to get the derived pointer. But it could be
983 // cases like this:
984 // bb1:
985 // ...
986 // %g1 = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(...)
987 // br label %merge
988 //
989 // bb2:
990 // ...
991 // %g2 = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(...)
992 // br label %merge
993 //
994 // merge:
995 // %p1 = phi i8 addrspace(1)* [ %g1, %bb1 ], [ %g2, %bb2 ]
996 // %cast = bitcast i8 addrspace(1)* %p1 in to i32 addrspace(1)*
997 //
998 // In this case, we can not find the bitcast any more. So we insert a new bitcast
999 // no matter there is already one or not. In this way, we can handle all cases, and
1000 // the extra bitcast should be optimized away in later passes.
1001 Value *ActualRelocatedBase = RelocatedBase;
1002 if (RelocatedBase->getType() != Base->getType()) {
1003 ActualRelocatedBase =
1004 Builder.CreateBitCast(RelocatedBase, Base->getType());
1005 }
1006 Value *Replacement = Builder.CreateGEP(
1007 Derived->getSourceElementType(), ActualRelocatedBase, makeArrayRef(OffsetV));
1008 Replacement->takeName(ToReplace);
1009 // If the newly generated derived pointer's type does not match the original derived
1010 // pointer's type, cast the new derived pointer to match it. Same reasoning as above.
1011 Value *ActualReplacement = Replacement;
1012 if (Replacement->getType() != ToReplace->getType()) {
1013 ActualReplacement =
1014 Builder.CreateBitCast(Replacement, ToReplace->getType());
1015 }
1016 ToReplace->replaceAllUsesWith(ActualReplacement);
1017 ToReplace->eraseFromParent();
1018
1019 MadeChange = true;
1020 }
1021 return MadeChange;
1022}
1023
1024// Turns this:
1025//
1026// %base = ...
1027// %ptr = gep %base + 15
1028// %tok = statepoint (%fun, i32 0, i32 0, i32 0, %base, %ptr)
1029// %base' = relocate(%tok, i32 4, i32 4)
1030// %ptr' = relocate(%tok, i32 4, i32 5)
1031// %val = load %ptr'
1032//
1033// into this:
1034//
1035// %base = ...
1036// %ptr = gep %base + 15
1037// %tok = statepoint (%fun, i32 0, i32 0, i32 0, %base, %ptr)
1038// %base' = gc.relocate(%tok, i32 4, i32 4)
1039// %ptr' = gep %base' + 15
1040// %val = load %ptr'
1041bool CodeGenPrepare::simplifyOffsetableRelocate(Instruction &I) {
1042 bool MadeChange = false;
1043 SmallVector<GCRelocateInst *, 2> AllRelocateCalls;
1044
1045 for (auto *U : I.users())
1046 if (GCRelocateInst *Relocate = dyn_cast<GCRelocateInst>(U))
1047 // Collect all the relocate calls associated with a statepoint
1048 AllRelocateCalls.push_back(Relocate);
1049
1050 // We need atleast one base pointer relocation + one derived pointer
1051 // relocation to mangle
1052 if (AllRelocateCalls.size() < 2)
1053 return false;
1054
1055 // RelocateInstMap is a mapping from the base relocate instruction to the
1056 // corresponding derived relocate instructions
1057 DenseMap<GCRelocateInst *, SmallVector<GCRelocateInst *, 2>> RelocateInstMap;
1058 computeBaseDerivedRelocateMap(AllRelocateCalls, RelocateInstMap);
1059 if (RelocateInstMap.empty())
1060 return false;
1061
1062 for (auto &Item : RelocateInstMap)
1063 // Item.first is the RelocatedBase to offset against
1064 // Item.second is the vector of Targets to replace
1065 MadeChange = simplifyRelocatesOffABase(Item.first, Item.second);
1066 return MadeChange;
1067}
1068
1069/// Sink the specified cast instruction into its user blocks.
1070static bool SinkCast(CastInst *CI) {
1071 BasicBlock *DefBB = CI->getParent();
1072
1073 /// InsertedCasts - Only insert a cast in each block once.
1074 DenseMap<BasicBlock*, CastInst*> InsertedCasts;
1075
1076 bool MadeChange = false;
1077 for (Value::user_iterator UI = CI->user_begin(), E = CI->user_end();
1078 UI != E; ) {
1079 Use &TheUse = UI.getUse();
1080 Instruction *User = cast<Instruction>(*UI);
1081
1082 // Figure out which BB this cast is used in. For PHI's this is the
1083 // appropriate predecessor block.
1084 BasicBlock *UserBB = User->getParent();
1085 if (PHINode *PN = dyn_cast<PHINode>(User)) {
1086 UserBB = PN->getIncomingBlock(TheUse);
1087 }
1088
1089 // Preincrement use iterator so we don't invalidate it.
1090 ++UI;
1091
1092 // The first insertion point of a block containing an EH pad is after the
1093 // pad. If the pad is the user, we cannot sink the cast past the pad.
1094 if (User->isEHPad())
1095 continue;
1096
1097 // If the block selected to receive the cast is an EH pad that does not
1098 // allow non-PHI instructions before the terminator, we can't sink the
1099 // cast.
1100 if (UserBB->getTerminator()->isEHPad())
1101 continue;
1102
1103 // If this user is in the same block as the cast, don't change the cast.
1104 if (UserBB == DefBB) continue;
1105
1106 // If we have already inserted a cast into this block, use it.
1107 CastInst *&InsertedCast = InsertedCasts[UserBB];
1108
1109 if (!InsertedCast) {
1110 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
1111 assert(InsertPt != UserBB->end())((InsertPt != UserBB->end()) ? static_cast<void> (0)
: __assert_fail ("InsertPt != UserBB->end()", "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 1111, __PRETTY_FUNCTION__))
;
1112 InsertedCast = CastInst::Create(CI->getOpcode(), CI->getOperand(0),
1113 CI->getType(), "", &*InsertPt);
1114 InsertedCast->setDebugLoc(CI->getDebugLoc());
1115 }
1116
1117 // Replace a use of the cast with a use of the new cast.
1118 TheUse = InsertedCast;
1119 MadeChange = true;
1120 ++NumCastUses;
1121 }
1122
1123 // If we removed all uses, nuke the cast.
1124 if (CI->use_empty()) {
1125 salvageDebugInfo(*CI);
1126 CI->eraseFromParent();
1127 MadeChange = true;
1128 }
1129
1130 return MadeChange;
1131}
1132
1133/// If the specified cast instruction is a noop copy (e.g. it's casting from
1134/// one pointer type to another, i32->i8 on PPC), sink it into user blocks to
1135/// reduce the number of virtual registers that must be created and coalesced.
1136///
1137/// Return true if any changes are made.
1138static bool OptimizeNoopCopyExpression(CastInst *CI, const TargetLowering &TLI,
1139 const DataLayout &DL) {
1140 // Sink only "cheap" (or nop) address-space casts. This is a weaker condition
1141 // than sinking only nop casts, but is helpful on some platforms.
1142 if (auto *ASC = dyn_cast<AddrSpaceCastInst>(CI)) {
1143 if (!TLI.isCheapAddrSpaceCast(ASC->getSrcAddressSpace(),
1144 ASC->getDestAddressSpace()))
1145 return false;
1146 }
1147
1148 // If this is a noop copy,
1149 EVT SrcVT = TLI.getValueType(DL, CI->getOperand(0)->getType());
1150 EVT DstVT = TLI.getValueType(DL, CI->getType());
1151
1152 // This is an fp<->int conversion?
1153 if (SrcVT.isInteger() != DstVT.isInteger())
1154 return false;
1155
1156 // If this is an extension, it will be a zero or sign extension, which
1157 // isn't a noop.
1158 if (SrcVT.bitsLT(DstVT)) return false;
1159
1160 // If these values will be promoted, find out what they will be promoted
1161 // to. This helps us consider truncates on PPC as noop copies when they
1162 // are.
1163 if (TLI.getTypeAction(CI->getContext(), SrcVT) ==
1164 TargetLowering::TypePromoteInteger)
1165 SrcVT = TLI.getTypeToTransformTo(CI->getContext(), SrcVT);
1166 if (TLI.getTypeAction(CI->getContext(), DstVT) ==
1167 TargetLowering::TypePromoteInteger)
1168 DstVT = TLI.getTypeToTransformTo(CI->getContext(), DstVT);
1169
1170 // If, after promotion, these are the same types, this is a noop copy.
1171 if (SrcVT != DstVT)
1172 return false;
1173
1174 return SinkCast(CI);
1175}
1176
1177bool CodeGenPrepare::replaceMathCmpWithIntrinsic(BinaryOperator *BO,
1178 CmpInst *Cmp,
1179 Intrinsic::ID IID) {
1180 if (BO->getParent() != Cmp->getParent()) {
1181 // We used to use a dominator tree here to allow multi-block optimization.
1182 // But that was problematic because:
1183 // 1. It could cause a perf regression by hoisting the math op into the
1184 // critical path.
1185 // 2. It could cause a perf regression by creating a value that was live
1186 // across multiple blocks and increasing register pressure.
1187 // 3. Use of a dominator tree could cause large compile-time regression.
1188 // This is because we recompute the DT on every change in the main CGP
1189 // run-loop. The recomputing is probably unnecessary in many cases, so if
1190 // that was fixed, using a DT here would be ok.
1191 return false;
1192 }
1193
1194 // We allow matching the canonical IR (add X, C) back to (usubo X, -C).
1195 Value *Arg0 = BO->getOperand(0);
1196 Value *Arg1 = BO->getOperand(1);
1197 if (BO->getOpcode() == Instruction::Add &&
1198 IID == Intrinsic::usub_with_overflow) {
1199 assert(isa<Constant>(Arg1) && "Unexpected input for usubo")((isa<Constant>(Arg1) && "Unexpected input for usubo"
) ? static_cast<void> (0) : __assert_fail ("isa<Constant>(Arg1) && \"Unexpected input for usubo\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 1199, __PRETTY_FUNCTION__))
;
1200 Arg1 = ConstantExpr::getNeg(cast<Constant>(Arg1));
1201 }
1202
1203 // Insert at the first instruction of the pair.
1204 Instruction *InsertPt = nullptr;
1205 for (Instruction &Iter : *Cmp->getParent()) {
1206 if (&Iter == BO || &Iter == Cmp) {
1207 InsertPt = &Iter;
1208 break;
1209 }
1210 }
1211 assert(InsertPt != nullptr && "Parent block did not contain cmp or binop")((InsertPt != nullptr && "Parent block did not contain cmp or binop"
) ? static_cast<void> (0) : __assert_fail ("InsertPt != nullptr && \"Parent block did not contain cmp or binop\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 1211, __PRETTY_FUNCTION__))
;
1212
1213 IRBuilder<> Builder(InsertPt);
1214 Value *MathOV = Builder.CreateBinaryIntrinsic(IID, Arg0, Arg1);
1215 Value *Math = Builder.CreateExtractValue(MathOV, 0, "math");
1216 Value *OV = Builder.CreateExtractValue(MathOV, 1, "ov");
1217 BO->replaceAllUsesWith(Math);
1218 Cmp->replaceAllUsesWith(OV);
1219 BO->eraseFromParent();
1220 Cmp->eraseFromParent();
1221 return true;
1222}
1223
1224/// Match special-case patterns that check for unsigned add overflow.
1225static bool matchUAddWithOverflowConstantEdgeCases(CmpInst *Cmp,
1226 BinaryOperator *&Add) {
1227 // Add = add A, 1; Cmp = icmp eq A,-1 (overflow if A is max val)
1228 // Add = add A,-1; Cmp = icmp ne A, 0 (overflow if A is non-zero)
1229 Value *A = Cmp->getOperand(0), *B = Cmp->getOperand(1);
1230
1231 // We are not expecting non-canonical/degenerate code. Just bail out.
1232 if (isa<Constant>(A))
1233 return false;
1234
1235 ICmpInst::Predicate Pred = Cmp->getPredicate();
1236 if (Pred == ICmpInst::ICMP_EQ && match(B, m_AllOnes()))
1237 B = ConstantInt::get(B->getType(), 1);
1238 else if (Pred == ICmpInst::ICMP_NE && match(B, m_ZeroInt()))
1239 B = ConstantInt::get(B->getType(), -1);
1240 else
1241 return false;
1242
1243 // Check the users of the variable operand of the compare looking for an add
1244 // with the adjusted constant.
1245 for (User *U : A->users()) {
1246 if (match(U, m_Add(m_Specific(A), m_Specific(B)))) {
1247 Add = cast<BinaryOperator>(U);
1248 return true;
1249 }
1250 }
1251 return false;
1252}
1253
1254/// Try to combine the compare into a call to the llvm.uadd.with.overflow
1255/// intrinsic. Return true if any changes were made.
1256bool CodeGenPrepare::combineToUAddWithOverflow(CmpInst *Cmp,
1257 bool &ModifiedDT) {
1258 Value *A, *B;
1259 BinaryOperator *Add;
1260 if (!match(Cmp, m_UAddWithOverflow(m_Value(A), m_Value(B), m_BinOp(Add))))
1261 if (!matchUAddWithOverflowConstantEdgeCases(Cmp, Add))
1262 return false;
1263
1264 if (!TLI->shouldFormOverflowOp(ISD::UADDO,
1265 TLI->getValueType(*DL, Add->getType())))
1266 return false;
1267
1268 // We don't want to move around uses of condition values this late, so we
1269 // check if it is legal to create the call to the intrinsic in the basic
1270 // block containing the icmp.
1271 if (Add->getParent() != Cmp->getParent() && !Add->hasOneUse())
1272 return false;
1273
1274 if (!replaceMathCmpWithIntrinsic(Add, Cmp, Intrinsic::uadd_with_overflow))
1275 return false;
1276
1277 // Reset callers - do not crash by iterating over a dead instruction.
1278 ModifiedDT = true;
1279 return true;
1280}
1281
1282bool CodeGenPrepare::combineToUSubWithOverflow(CmpInst *Cmp,
1283 bool &ModifiedDT) {
1284 // We are not expecting non-canonical/degenerate code. Just bail out.
1285 Value *A = Cmp->getOperand(0), *B = Cmp->getOperand(1);
1286 if (isa<Constant>(A) && isa<Constant>(B))
1287 return false;
1288
1289 // Convert (A u> B) to (A u< B) to simplify pattern matching.
1290 ICmpInst::Predicate Pred = Cmp->getPredicate();
1291 if (Pred == ICmpInst::ICMP_UGT) {
1292 std::swap(A, B);
1293 Pred = ICmpInst::ICMP_ULT;
1294 }
1295 // Convert special-case: (A == 0) is the same as (A u< 1).
1296 if (Pred == ICmpInst::ICMP_EQ && match(B, m_ZeroInt())) {
1297 B = ConstantInt::get(B->getType(), 1);
1298 Pred = ICmpInst::ICMP_ULT;
1299 }
1300 // Convert special-case: (A != 0) is the same as (0 u< A).
1301 if (Pred == ICmpInst::ICMP_NE && match(B, m_ZeroInt())) {
1302 std::swap(A, B);
1303 Pred = ICmpInst::ICMP_ULT;
1304 }
1305 if (Pred != ICmpInst::ICMP_ULT)
1306 return false;
1307
1308 // Walk the users of a variable operand of a compare looking for a subtract or
1309 // add with that same operand. Also match the 2nd operand of the compare to
1310 // the add/sub, but that may be a negated constant operand of an add.
1311 Value *CmpVariableOperand = isa<Constant>(A) ? B : A;
1312 BinaryOperator *Sub = nullptr;
1313 for (User *U : CmpVariableOperand->users()) {
1314 // A - B, A u< B --> usubo(A, B)
1315 if (match(U, m_Sub(m_Specific(A), m_Specific(B)))) {
1316 Sub = cast<BinaryOperator>(U);
1317 break;
1318 }
1319
1320 // A + (-C), A u< C (canonicalized form of (sub A, C))
1321 const APInt *CmpC, *AddC;
1322 if (match(U, m_Add(m_Specific(A), m_APInt(AddC))) &&
1323 match(B, m_APInt(CmpC)) && *AddC == -(*CmpC)) {
1324 Sub = cast<BinaryOperator>(U);
1325 break;
1326 }
1327 }
1328 if (!Sub)
1329 return false;
1330
1331 if (!TLI->shouldFormOverflowOp(ISD::USUBO,
1332 TLI->getValueType(*DL, Sub->getType())))
1333 return false;
1334
1335 if (!replaceMathCmpWithIntrinsic(Sub, Cmp, Intrinsic::usub_with_overflow))
1336 return false;
1337
1338 // Reset callers - do not crash by iterating over a dead instruction.
1339 ModifiedDT = true;
1340 return true;
1341}
1342
1343/// Sink the given CmpInst into user blocks to reduce the number of virtual
1344/// registers that must be created and coalesced. This is a clear win except on
1345/// targets with multiple condition code registers (PowerPC), where it might
1346/// lose; some adjustment may be wanted there.
1347///
1348/// Return true if any changes are made.
1349static bool sinkCmpExpression(CmpInst *Cmp, const TargetLowering &TLI) {
1350 if (TLI.hasMultipleConditionRegisters())
1351 return false;
1352
1353 // Avoid sinking soft-FP comparisons, since this can move them into a loop.
1354 if (TLI.useSoftFloat() && isa<FCmpInst>(Cmp))
1355 return false;
1356
1357 // Only insert a cmp in each block once.
1358 DenseMap<BasicBlock*, CmpInst*> InsertedCmps;
1359
1360 bool MadeChange = false;
1361 for (Value::user_iterator UI = Cmp->user_begin(), E = Cmp->user_end();
1362 UI != E; ) {
1363 Use &TheUse = UI.getUse();
1364 Instruction *User = cast<Instruction>(*UI);
1365
1366 // Preincrement use iterator so we don't invalidate it.
1367 ++UI;
1368
1369 // Don't bother for PHI nodes.
1370 if (isa<PHINode>(User))
1371 continue;
1372
1373 // Figure out which BB this cmp is used in.
1374 BasicBlock *UserBB = User->getParent();
1375 BasicBlock *DefBB = Cmp->getParent();
1376
1377 // If this user is in the same block as the cmp, don't change the cmp.
1378 if (UserBB == DefBB) continue;
1379
1380 // If we have already inserted a cmp into this block, use it.
1381 CmpInst *&InsertedCmp = InsertedCmps[UserBB];
1382
1383 if (!InsertedCmp) {
1384 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
1385 assert(InsertPt != UserBB->end())((InsertPt != UserBB->end()) ? static_cast<void> (0)
: __assert_fail ("InsertPt != UserBB->end()", "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 1385, __PRETTY_FUNCTION__))
;
1386 InsertedCmp =
1387 CmpInst::Create(Cmp->getOpcode(), Cmp->getPredicate(),
1388 Cmp->getOperand(0), Cmp->getOperand(1), "",
1389 &*InsertPt);
1390 // Propagate the debug info.
1391 InsertedCmp->setDebugLoc(Cmp->getDebugLoc());
1392 }
1393
1394 // Replace a use of the cmp with a use of the new cmp.
1395 TheUse = InsertedCmp;
1396 MadeChange = true;
1397 ++NumCmpUses;
1398 }
1399
1400 // If we removed all uses, nuke the cmp.
1401 if (Cmp->use_empty()) {
1402 Cmp->eraseFromParent();
1403 MadeChange = true;
1404 }
1405
1406 return MadeChange;
1407}
1408
1409bool CodeGenPrepare::optimizeCmp(CmpInst *Cmp, bool &ModifiedDT) {
1410 if (sinkCmpExpression(Cmp, *TLI))
1411 return true;
1412
1413 if (combineToUAddWithOverflow(Cmp, ModifiedDT))
1414 return true;
1415
1416 if (combineToUSubWithOverflow(Cmp, ModifiedDT))
1417 return true;
1418
1419 return false;
1420}
1421
1422/// Duplicate and sink the given 'and' instruction into user blocks where it is
1423/// used in a compare to allow isel to generate better code for targets where
1424/// this operation can be combined.
1425///
1426/// Return true if any changes are made.
1427static bool sinkAndCmp0Expression(Instruction *AndI,
1428 const TargetLowering &TLI,
1429 SetOfInstrs &InsertedInsts) {
1430 // Double-check that we're not trying to optimize an instruction that was
1431 // already optimized by some other part of this pass.
1432 assert(!InsertedInsts.count(AndI) &&((!InsertedInsts.count(AndI) && "Attempting to optimize already optimized and instruction"
) ? static_cast<void> (0) : __assert_fail ("!InsertedInsts.count(AndI) && \"Attempting to optimize already optimized and instruction\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 1433, __PRETTY_FUNCTION__))
1433 "Attempting to optimize already optimized and instruction")((!InsertedInsts.count(AndI) && "Attempting to optimize already optimized and instruction"
) ? static_cast<void> (0) : __assert_fail ("!InsertedInsts.count(AndI) && \"Attempting to optimize already optimized and instruction\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 1433, __PRETTY_FUNCTION__))
;
1434 (void) InsertedInsts;
1435
1436 // Nothing to do for single use in same basic block.
1437 if (AndI->hasOneUse() &&
1438 AndI->getParent() == cast<Instruction>(*AndI->user_begin())->getParent())
1439 return false;
1440
1441 // Try to avoid cases where sinking/duplicating is likely to increase register
1442 // pressure.
1443 if (!isa<ConstantInt>(AndI->getOperand(0)) &&
1444 !isa<ConstantInt>(AndI->getOperand(1)) &&
1445 AndI->getOperand(0)->hasOneUse() && AndI->getOperand(1)->hasOneUse())
1446 return false;
1447
1448 for (auto *U : AndI->users()) {
1449 Instruction *User = cast<Instruction>(U);
1450
1451 // Only sink 'and' feeding icmp with 0.
1452 if (!isa<ICmpInst>(User))
1453 return false;
1454
1455 auto *CmpC = dyn_cast<ConstantInt>(User->getOperand(1));
1456 if (!CmpC || !CmpC->isZero())
1457 return false;
1458 }
1459
1460 if (!TLI.isMaskAndCmp0FoldingBeneficial(*AndI))
1461 return false;
1462
1463 LLVM_DEBUG(dbgs() << "found 'and' feeding only icmp 0;\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "found 'and' feeding only icmp 0;\n"
; } } while (false)
;
1464 LLVM_DEBUG(AndI->getParent()->dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { AndI->getParent()->dump(); } } while
(false)
;
1465
1466 // Push the 'and' into the same block as the icmp 0. There should only be
1467 // one (icmp (and, 0)) in each block, since CSE/GVN should have removed any
1468 // others, so we don't need to keep track of which BBs we insert into.
1469 for (Value::user_iterator UI = AndI->user_begin(), E = AndI->user_end();
1470 UI != E; ) {
1471 Use &TheUse = UI.getUse();
1472 Instruction *User = cast<Instruction>(*UI);
1473
1474 // Preincrement use iterator so we don't invalidate it.
1475 ++UI;
1476
1477 LLVM_DEBUG(dbgs() << "sinking 'and' use: " << *User << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "sinking 'and' use: " <<
*User << "\n"; } } while (false)
;
1478
1479 // Keep the 'and' in the same place if the use is already in the same block.
1480 Instruction *InsertPt =
1481 User->getParent() == AndI->getParent() ? AndI : User;
1482 Instruction *InsertedAnd =
1483 BinaryOperator::Create(Instruction::And, AndI->getOperand(0),
1484 AndI->getOperand(1), "", InsertPt);
1485 // Propagate the debug info.
1486 InsertedAnd->setDebugLoc(AndI->getDebugLoc());
1487
1488 // Replace a use of the 'and' with a use of the new 'and'.
1489 TheUse = InsertedAnd;
1490 ++NumAndUses;
1491 LLVM_DEBUG(User->getParent()->dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { User->getParent()->dump(); } } while
(false)
;
1492 }
1493
1494 // We removed all uses, nuke the and.
1495 AndI->eraseFromParent();
1496 return true;
1497}
1498
1499/// Check if the candidates could be combined with a shift instruction, which
1500/// includes:
1501/// 1. Truncate instruction
1502/// 2. And instruction and the imm is a mask of the low bits:
1503/// imm & (imm+1) == 0
1504static bool isExtractBitsCandidateUse(Instruction *User) {
1505 if (!isa<TruncInst>(User)) {
1506 if (User->getOpcode() != Instruction::And ||
1507 !isa<ConstantInt>(User->getOperand(1)))
1508 return false;
1509
1510 const APInt &Cimm = cast<ConstantInt>(User->getOperand(1))->getValue();
1511
1512 if ((Cimm & (Cimm + 1)).getBoolValue())
1513 return false;
1514 }
1515 return true;
1516}
1517
1518/// Sink both shift and truncate instruction to the use of truncate's BB.
1519static bool
1520SinkShiftAndTruncate(BinaryOperator *ShiftI, Instruction *User, ConstantInt *CI,
1521 DenseMap<BasicBlock *, BinaryOperator *> &InsertedShifts,
1522 const TargetLowering &TLI, const DataLayout &DL) {
1523 BasicBlock *UserBB = User->getParent();
1524 DenseMap<BasicBlock *, CastInst *> InsertedTruncs;
1525 TruncInst *TruncI = dyn_cast<TruncInst>(User);
1526 bool MadeChange = false;
1527
1528 for (Value::user_iterator TruncUI = TruncI->user_begin(),
1529 TruncE = TruncI->user_end();
1530 TruncUI != TruncE;) {
1531
1532 Use &TruncTheUse = TruncUI.getUse();
1533 Instruction *TruncUser = cast<Instruction>(*TruncUI);
1534 // Preincrement use iterator so we don't invalidate it.
1535
1536 ++TruncUI;
1537
1538 int ISDOpcode = TLI.InstructionOpcodeToISD(TruncUser->getOpcode());
1539 if (!ISDOpcode)
1540 continue;
1541
1542 // If the use is actually a legal node, there will not be an
1543 // implicit truncate.
1544 // FIXME: always querying the result type is just an
1545 // approximation; some nodes' legality is determined by the
1546 // operand or other means. There's no good way to find out though.
1547 if (TLI.isOperationLegalOrCustom(
1548 ISDOpcode, TLI.getValueType(DL, TruncUser->getType(), true)))
1549 continue;
1550
1551 // Don't bother for PHI nodes.
1552 if (isa<PHINode>(TruncUser))
1553 continue;
1554
1555 BasicBlock *TruncUserBB = TruncUser->getParent();
1556
1557 if (UserBB == TruncUserBB)
1558 continue;
1559
1560 BinaryOperator *&InsertedShift = InsertedShifts[TruncUserBB];
1561 CastInst *&InsertedTrunc = InsertedTruncs[TruncUserBB];
1562
1563 if (!InsertedShift && !InsertedTrunc) {
1564 BasicBlock::iterator InsertPt = TruncUserBB->getFirstInsertionPt();
1565 assert(InsertPt != TruncUserBB->end())((InsertPt != TruncUserBB->end()) ? static_cast<void>
(0) : __assert_fail ("InsertPt != TruncUserBB->end()", "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 1565, __PRETTY_FUNCTION__))
;
1566 // Sink the shift
1567 if (ShiftI->getOpcode() == Instruction::AShr)
1568 InsertedShift = BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI,
1569 "", &*InsertPt);
1570 else
1571 InsertedShift = BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI,
1572 "", &*InsertPt);
1573 InsertedShift->setDebugLoc(ShiftI->getDebugLoc());
1574
1575 // Sink the trunc
1576 BasicBlock::iterator TruncInsertPt = TruncUserBB->getFirstInsertionPt();
1577 TruncInsertPt++;
1578 assert(TruncInsertPt != TruncUserBB->end())((TruncInsertPt != TruncUserBB->end()) ? static_cast<void
> (0) : __assert_fail ("TruncInsertPt != TruncUserBB->end()"
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 1578, __PRETTY_FUNCTION__))
;
1579
1580 InsertedTrunc = CastInst::Create(TruncI->getOpcode(), InsertedShift,
1581 TruncI->getType(), "", &*TruncInsertPt);
1582 InsertedTrunc->setDebugLoc(TruncI->getDebugLoc());
1583
1584 MadeChange = true;
1585
1586 TruncTheUse = InsertedTrunc;
1587 }
1588 }
1589 return MadeChange;
1590}
1591
1592/// Sink the shift *right* instruction into user blocks if the uses could
1593/// potentially be combined with this shift instruction and generate BitExtract
1594/// instruction. It will only be applied if the architecture supports BitExtract
1595/// instruction. Here is an example:
1596/// BB1:
1597/// %x.extract.shift = lshr i64 %arg1, 32
1598/// BB2:
1599/// %x.extract.trunc = trunc i64 %x.extract.shift to i16
1600/// ==>
1601///
1602/// BB2:
1603/// %x.extract.shift.1 = lshr i64 %arg1, 32
1604/// %x.extract.trunc = trunc i64 %x.extract.shift.1 to i16
1605///
1606/// CodeGen will recognize the pattern in BB2 and generate BitExtract
1607/// instruction.
1608/// Return true if any changes are made.
1609static bool OptimizeExtractBits(BinaryOperator *ShiftI, ConstantInt *CI,
1610 const TargetLowering &TLI,
1611 const DataLayout &DL) {
1612 BasicBlock *DefBB = ShiftI->getParent();
1613
1614 /// Only insert instructions in each block once.
1615 DenseMap<BasicBlock *, BinaryOperator *> InsertedShifts;
1616
1617 bool shiftIsLegal = TLI.isTypeLegal(TLI.getValueType(DL, ShiftI->getType()));
1618
1619 bool MadeChange = false;
1620 for (Value::user_iterator UI = ShiftI->user_begin(), E = ShiftI->user_end();
1621 UI != E;) {
1622 Use &TheUse = UI.getUse();
1623 Instruction *User = cast<Instruction>(*UI);
1624 // Preincrement use iterator so we don't invalidate it.
1625 ++UI;
1626
1627 // Don't bother for PHI nodes.
1628 if (isa<PHINode>(User))
1629 continue;
1630
1631 if (!isExtractBitsCandidateUse(User))
1632 continue;
1633
1634 BasicBlock *UserBB = User->getParent();
1635
1636 if (UserBB == DefBB) {
1637 // If the shift and truncate instruction are in the same BB. The use of
1638 // the truncate(TruncUse) may still introduce another truncate if not
1639 // legal. In this case, we would like to sink both shift and truncate
1640 // instruction to the BB of TruncUse.
1641 // for example:
1642 // BB1:
1643 // i64 shift.result = lshr i64 opnd, imm
1644 // trunc.result = trunc shift.result to i16
1645 //
1646 // BB2:
1647 // ----> We will have an implicit truncate here if the architecture does
1648 // not have i16 compare.
1649 // cmp i16 trunc.result, opnd2
1650 //
1651 if (isa<TruncInst>(User) && shiftIsLegal
1652 // If the type of the truncate is legal, no truncate will be
1653 // introduced in other basic blocks.
1654 &&
1655 (!TLI.isTypeLegal(TLI.getValueType(DL, User->getType()))))
1656 MadeChange =
1657 SinkShiftAndTruncate(ShiftI, User, CI, InsertedShifts, TLI, DL);
1658
1659 continue;
1660 }
1661 // If we have already inserted a shift into this block, use it.
1662 BinaryOperator *&InsertedShift = InsertedShifts[UserBB];
1663
1664 if (!InsertedShift) {
1665 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
1666 assert(InsertPt != UserBB->end())((InsertPt != UserBB->end()) ? static_cast<void> (0)
: __assert_fail ("InsertPt != UserBB->end()", "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 1666, __PRETTY_FUNCTION__))
;
1667
1668 if (ShiftI->getOpcode() == Instruction::AShr)
1669 InsertedShift = BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI,
1670 "", &*InsertPt);
1671 else
1672 InsertedShift = BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI,
1673 "", &*InsertPt);
1674 InsertedShift->setDebugLoc(ShiftI->getDebugLoc());
1675
1676 MadeChange = true;
1677 }
1678
1679 // Replace a use of the shift with a use of the new shift.
1680 TheUse = InsertedShift;
1681 }
1682
1683 // If we removed all uses, nuke the shift.
1684 if (ShiftI->use_empty()) {
1685 salvageDebugInfo(*ShiftI);
1686 ShiftI->eraseFromParent();
1687 }
1688
1689 return MadeChange;
1690}
1691
1692/// If counting leading or trailing zeros is an expensive operation and a zero
1693/// input is defined, add a check for zero to avoid calling the intrinsic.
1694///
1695/// We want to transform:
1696/// %z = call i64 @llvm.cttz.i64(i64 %A, i1 false)
1697///
1698/// into:
1699/// entry:
1700/// %cmpz = icmp eq i64 %A, 0
1701/// br i1 %cmpz, label %cond.end, label %cond.false
1702/// cond.false:
1703/// %z = call i64 @llvm.cttz.i64(i64 %A, i1 true)
1704/// br label %cond.end
1705/// cond.end:
1706/// %ctz = phi i64 [ 64, %entry ], [ %z, %cond.false ]
1707///
1708/// If the transform is performed, return true and set ModifiedDT to true.
1709static bool despeculateCountZeros(IntrinsicInst *CountZeros,
1710 const TargetLowering *TLI,
1711 const DataLayout *DL,
1712 bool &ModifiedDT) {
1713 if (!TLI || !DL)
1714 return false;
1715
1716 // If a zero input is undefined, it doesn't make sense to despeculate that.
1717 if (match(CountZeros->getOperand(1), m_One()))
1718 return false;
1719
1720 // If it's cheap to speculate, there's nothing to do.
1721 auto IntrinsicID = CountZeros->getIntrinsicID();
1722 if ((IntrinsicID == Intrinsic::cttz && TLI->isCheapToSpeculateCttz()) ||
1723 (IntrinsicID == Intrinsic::ctlz && TLI->isCheapToSpeculateCtlz()))
1724 return false;
1725
1726 // Only handle legal scalar cases. Anything else requires too much work.
1727 Type *Ty = CountZeros->getType();
1728 unsigned SizeInBits = Ty->getPrimitiveSizeInBits();
1729 if (Ty->isVectorTy() || SizeInBits > DL->getLargestLegalIntTypeSizeInBits())
1730 return false;
1731
1732 // The intrinsic will be sunk behind a compare against zero and branch.
1733 BasicBlock *StartBlock = CountZeros->getParent();
1734 BasicBlock *CallBlock = StartBlock->splitBasicBlock(CountZeros, "cond.false");
1735
1736 // Create another block after the count zero intrinsic. A PHI will be added
1737 // in this block to select the result of the intrinsic or the bit-width
1738 // constant if the input to the intrinsic is zero.
1739 BasicBlock::iterator SplitPt = ++(BasicBlock::iterator(CountZeros));
1740 BasicBlock *EndBlock = CallBlock->splitBasicBlock(SplitPt, "cond.end");
1741
1742 // Set up a builder to create a compare, conditional branch, and PHI.
1743 IRBuilder<> Builder(CountZeros->getContext());
1744 Builder.SetInsertPoint(StartBlock->getTerminator());
1745 Builder.SetCurrentDebugLocation(CountZeros->getDebugLoc());
1746
1747 // Replace the unconditional branch that was created by the first split with
1748 // a compare against zero and a conditional branch.
1749 Value *Zero = Constant::getNullValue(Ty);
1750 Value *Cmp = Builder.CreateICmpEQ(CountZeros->getOperand(0), Zero, "cmpz");
1751 Builder.CreateCondBr(Cmp, EndBlock, CallBlock);
1752 StartBlock->getTerminator()->eraseFromParent();
1753
1754 // Create a PHI in the end block to select either the output of the intrinsic
1755 // or the bit width of the operand.
1756 Builder.SetInsertPoint(&EndBlock->front());
1757 PHINode *PN = Builder.CreatePHI(Ty, 2, "ctz");
1758 CountZeros->replaceAllUsesWith(PN);
1759 Value *BitWidth = Builder.getInt(APInt(SizeInBits, SizeInBits));
1760 PN->addIncoming(BitWidth, StartBlock);
1761 PN->addIncoming(CountZeros, CallBlock);
1762
1763 // We are explicitly handling the zero case, so we can set the intrinsic's
1764 // undefined zero argument to 'true'. This will also prevent reprocessing the
1765 // intrinsic; we only despeculate when a zero input is defined.
1766 CountZeros->setArgOperand(1, Builder.getTrue());
1767 ModifiedDT = true;
1768 return true;
1769}
1770
1771bool CodeGenPrepare::optimizeCallInst(CallInst *CI, bool &ModifiedDT) {
1772 BasicBlock *BB = CI->getParent();
1773
1774 // Lower inline assembly if we can.
1775 // If we found an inline asm expession, and if the target knows how to
1776 // lower it to normal LLVM code, do so now.
1777 if (TLI && isa<InlineAsm>(CI->getCalledValue())) {
1778 if (TLI->ExpandInlineAsm(CI)) {
1779 // Avoid invalidating the iterator.
1780 CurInstIterator = BB->begin();
1781 // Avoid processing instructions out of order, which could cause
1782 // reuse before a value is defined.
1783 SunkAddrs.clear();
1784 return true;
1785 }
1786 // Sink address computing for memory operands into the block.
1787 if (optimizeInlineAsmInst(CI))
1788 return true;
1789 }
1790
1791 // Align the pointer arguments to this call if the target thinks it's a good
1792 // idea
1793 unsigned MinSize, PrefAlign;
1794 if (TLI && TLI->shouldAlignPointerArgs(CI, MinSize, PrefAlign)) {
1795 for (auto &Arg : CI->arg_operands()) {
1796 // We want to align both objects whose address is used directly and
1797 // objects whose address is used in casts and GEPs, though it only makes
1798 // sense for GEPs if the offset is a multiple of the desired alignment and
1799 // if size - offset meets the size threshold.
1800 if (!Arg->getType()->isPointerTy())
1801 continue;
1802 APInt Offset(DL->getIndexSizeInBits(
1803 cast<PointerType>(Arg->getType())->getAddressSpace()),
1804 0);
1805 Value *Val = Arg->stripAndAccumulateInBoundsConstantOffsets(*DL, Offset);
1806 uint64_t Offset2 = Offset.getLimitedValue();
1807 if ((Offset2 & (PrefAlign-1)) != 0)
1808 continue;
1809 AllocaInst *AI;
1810 if ((AI = dyn_cast<AllocaInst>(Val)) && AI->getAlignment() < PrefAlign &&
1811 DL->getTypeAllocSize(AI->getAllocatedType()) >= MinSize + Offset2)
1812 AI->setAlignment(PrefAlign);
1813 // Global variables can only be aligned if they are defined in this
1814 // object (i.e. they are uniquely initialized in this object), and
1815 // over-aligning global variables that have an explicit section is
1816 // forbidden.
1817 GlobalVariable *GV;
1818 if ((GV = dyn_cast<GlobalVariable>(Val)) && GV->canIncreaseAlignment() &&
1819 GV->getPointerAlignment(*DL) < PrefAlign &&
1820 DL->getTypeAllocSize(GV->getValueType()) >=
1821 MinSize + Offset2)
1822 GV->setAlignment(PrefAlign);
1823 }
1824 // If this is a memcpy (or similar) then we may be able to improve the
1825 // alignment
1826 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(CI)) {
1827 unsigned DestAlign = getKnownAlignment(MI->getDest(), *DL);
1828 if (DestAlign > MI->getDestAlignment())
1829 MI->setDestAlignment(DestAlign);
1830 if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI)) {
1831 unsigned SrcAlign = getKnownAlignment(MTI->getSource(), *DL);
1832 if (SrcAlign > MTI->getSourceAlignment())
1833 MTI->setSourceAlignment(SrcAlign);
1834 }
1835 }
1836 }
1837
1838 // If we have a cold call site, try to sink addressing computation into the
1839 // cold block. This interacts with our handling for loads and stores to
1840 // ensure that we can fold all uses of a potential addressing computation
1841 // into their uses. TODO: generalize this to work over profiling data
1842 if (!OptSize && CI->hasFnAttr(Attribute::Cold))
1843 for (auto &Arg : CI->arg_operands()) {
1844 if (!Arg->getType()->isPointerTy())
1845 continue;
1846 unsigned AS = Arg->getType()->getPointerAddressSpace();
1847 return optimizeMemoryInst(CI, Arg, Arg->getType(), AS);
1848 }
1849
1850 IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI);
1851 if (II) {
1852 switch (II->getIntrinsicID()) {
1853 default: break;
1854 case Intrinsic::experimental_widenable_condition: {
1855 // Give up on future widening oppurtunties so that we can fold away dead
1856 // paths and merge blocks before going into block-local instruction
1857 // selection.
1858 if (II->use_empty()) {
1859 II->eraseFromParent();
1860 return true;
1861 }
1862 Constant *RetVal = ConstantInt::getTrue(II->getContext());
1863 resetIteratorIfInvalidatedWhileCalling(BB, [&]() {
1864 replaceAndRecursivelySimplify(CI, RetVal, TLInfo, nullptr);
1865 });
1866 return true;
1867 }
1868 case Intrinsic::objectsize: {
1869 // Lower all uses of llvm.objectsize.*
1870 Value *RetVal =
1871 lowerObjectSizeCall(II, *DL, TLInfo, /*MustSucceed=*/true);
1872
1873 resetIteratorIfInvalidatedWhileCalling(BB, [&]() {
1874 replaceAndRecursivelySimplify(CI, RetVal, TLInfo, nullptr);
1875 });
1876 return true;
1877 }
1878 case Intrinsic::is_constant: {
1879 // If is_constant hasn't folded away yet, lower it to false now.
1880 Constant *RetVal = ConstantInt::get(II->getType(), 0);
1881 resetIteratorIfInvalidatedWhileCalling(BB, [&]() {
1882 replaceAndRecursivelySimplify(CI, RetVal, TLInfo, nullptr);
1883 });
1884 return true;
1885 }
1886 case Intrinsic::aarch64_stlxr:
1887 case Intrinsic::aarch64_stxr: {
1888 ZExtInst *ExtVal = dyn_cast<ZExtInst>(CI->getArgOperand(0));
1889 if (!ExtVal || !ExtVal->hasOneUse() ||
1890 ExtVal->getParent() == CI->getParent())
1891 return false;
1892 // Sink a zext feeding stlxr/stxr before it, so it can be folded into it.
1893 ExtVal->moveBefore(CI);
1894 // Mark this instruction as "inserted by CGP", so that other
1895 // optimizations don't touch it.
1896 InsertedInsts.insert(ExtVal);
1897 return true;
1898 }
1899
1900 case Intrinsic::launder_invariant_group:
1901 case Intrinsic::strip_invariant_group: {
1902 Value *ArgVal = II->getArgOperand(0);
1903 auto it = LargeOffsetGEPMap.find(II);
1904 if (it != LargeOffsetGEPMap.end()) {
1905 // Merge entries in LargeOffsetGEPMap to reflect the RAUW.
1906 // Make sure not to have to deal with iterator invalidation
1907 // after possibly adding ArgVal to LargeOffsetGEPMap.
1908 auto GEPs = std::move(it->second);
1909 LargeOffsetGEPMap[ArgVal].append(GEPs.begin(), GEPs.end());
1910 LargeOffsetGEPMap.erase(II);
1911 }
1912
1913 II->replaceAllUsesWith(ArgVal);
1914 II->eraseFromParent();
1915 return true;
1916 }
1917 case Intrinsic::cttz:
1918 case Intrinsic::ctlz:
1919 // If counting zeros is expensive, try to avoid it.
1920 return despeculateCountZeros(II, TLI, DL, ModifiedDT);
1921 }
1922
1923 if (TLI) {
1924 SmallVector<Value*, 2> PtrOps;
1925 Type *AccessTy;
1926 if (TLI->getAddrModeArguments(II, PtrOps, AccessTy))
1927 while (!PtrOps.empty()) {
1928 Value *PtrVal = PtrOps.pop_back_val();
1929 unsigned AS = PtrVal->getType()->getPointerAddressSpace();
1930 if (optimizeMemoryInst(II, PtrVal, AccessTy, AS))
1931 return true;
1932 }
1933 }
1934 }
1935
1936 // From here on out we're working with named functions.
1937 if (!CI->getCalledFunction()) return false;
1938
1939 // Lower all default uses of _chk calls. This is very similar
1940 // to what InstCombineCalls does, but here we are only lowering calls
1941 // to fortified library functions (e.g. __memcpy_chk) that have the default
1942 // "don't know" as the objectsize. Anything else should be left alone.
1943 FortifiedLibCallSimplifier Simplifier(TLInfo, true);
1944 if (Value *V = Simplifier.optimizeCall(CI)) {
1945 CI->replaceAllUsesWith(V);
1946 CI->eraseFromParent();
1947 return true;
1948 }
1949
1950 return false;
1951}
1952
1953/// Look for opportunities to duplicate return instructions to the predecessor
1954/// to enable tail call optimizations. The case it is currently looking for is:
1955/// @code
1956/// bb0:
1957/// %tmp0 = tail call i32 @f0()
1958/// br label %return
1959/// bb1:
1960/// %tmp1 = tail call i32 @f1()
1961/// br label %return
1962/// bb2:
1963/// %tmp2 = tail call i32 @f2()
1964/// br label %return
1965/// return:
1966/// %retval = phi i32 [ %tmp0, %bb0 ], [ %tmp1, %bb1 ], [ %tmp2, %bb2 ]
1967/// ret i32 %retval
1968/// @endcode
1969///
1970/// =>
1971///
1972/// @code
1973/// bb0:
1974/// %tmp0 = tail call i32 @f0()
1975/// ret i32 %tmp0
1976/// bb1:
1977/// %tmp1 = tail call i32 @f1()
1978/// ret i32 %tmp1
1979/// bb2:
1980/// %tmp2 = tail call i32 @f2()
1981/// ret i32 %tmp2
1982/// @endcode
1983bool CodeGenPrepare::dupRetToEnableTailCallOpts(BasicBlock *BB, bool &ModifiedDT) {
1984 if (!TLI)
1985 return false;
1986
1987 ReturnInst *RetI = dyn_cast<ReturnInst>(BB->getTerminator());
1988 if (!RetI)
1989 return false;
1990
1991 PHINode *PN = nullptr;
1992 BitCastInst *BCI = nullptr;
1993 Value *V = RetI->getReturnValue();
1994 if (V) {
1995 BCI = dyn_cast<BitCastInst>(V);
1996 if (BCI)
1997 V = BCI->getOperand(0);
1998
1999 PN = dyn_cast<PHINode>(V);
2000 if (!PN)
2001 return false;
2002 }
2003
2004 if (PN && PN->getParent() != BB)
2005 return false;
2006
2007 // Make sure there are no instructions between the PHI and return, or that the
2008 // return is the first instruction in the block.
2009 if (PN) {
2010 BasicBlock::iterator BI = BB->begin();
2011 // Skip over debug and the bitcast.
2012 do { ++BI; } while (isa<DbgInfoIntrinsic>(BI) || &*BI == BCI);
2013 if (&*BI != RetI)
2014 return false;
2015 } else {
2016 BasicBlock::iterator BI = BB->begin();
2017 while (isa<DbgInfoIntrinsic>(BI)) ++BI;
2018 if (&*BI != RetI)
2019 return false;
2020 }
2021
2022 /// Only dup the ReturnInst if the CallInst is likely to be emitted as a tail
2023 /// call.
2024 const Function *F = BB->getParent();
2025 SmallVector<CallInst*, 4> TailCalls;
2026 if (PN) {
2027 for (unsigned I = 0, E = PN->getNumIncomingValues(); I != E; ++I) {
2028 // Look through bitcasts.
2029 Value *IncomingVal = PN->getIncomingValue(I)->stripPointerCasts();
2030 CallInst *CI = dyn_cast<CallInst>(IncomingVal);
2031 // Make sure the phi value is indeed produced by the tail call.
2032 if (CI && CI->hasOneUse() && CI->getParent() == PN->getIncomingBlock(I) &&
2033 TLI->mayBeEmittedAsTailCall(CI) &&
2034 attributesPermitTailCall(F, CI, RetI, *TLI))
2035 TailCalls.push_back(CI);
2036 }
2037 } else {
2038 SmallPtrSet<BasicBlock*, 4> VisitedBBs;
2039 for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE; ++PI) {
2040 if (!VisitedBBs.insert(*PI).second)
2041 continue;
2042
2043 BasicBlock::InstListType &InstList = (*PI)->getInstList();
2044 BasicBlock::InstListType::reverse_iterator RI = InstList.rbegin();
2045 BasicBlock::InstListType::reverse_iterator RE = InstList.rend();
2046 do { ++RI; } while (RI != RE && isa<DbgInfoIntrinsic>(&*RI));
2047 if (RI == RE)
2048 continue;
2049
2050 CallInst *CI = dyn_cast<CallInst>(&*RI);
2051 if (CI && CI->use_empty() && TLI->mayBeEmittedAsTailCall(CI) &&
2052 attributesPermitTailCall(F, CI, RetI, *TLI))
2053 TailCalls.push_back(CI);
2054 }
2055 }
2056
2057 bool Changed = false;
2058 for (unsigned i = 0, e = TailCalls.size(); i != e; ++i) {
2059 CallInst *CI = TailCalls[i];
2060 CallSite CS(CI);
2061
2062 // Make sure the call instruction is followed by an unconditional branch to
2063 // the return block.
2064 BasicBlock *CallBB = CI->getParent();
2065 BranchInst *BI = dyn_cast<BranchInst>(CallBB->getTerminator());
2066 if (!BI || !BI->isUnconditional() || BI->getSuccessor(0) != BB)
2067 continue;
2068
2069 // Duplicate the return into CallBB.
2070 (void)FoldReturnIntoUncondBranch(RetI, BB, CallBB);
2071 ModifiedDT = Changed = true;
2072 ++NumRetsDup;
2073 }
2074
2075 // If we eliminated all predecessors of the block, delete the block now.
2076 if (Changed && !BB->hasAddressTaken() && pred_begin(BB) == pred_end(BB))
2077 BB->eraseFromParent();
2078
2079 return Changed;
2080}
2081
2082//===----------------------------------------------------------------------===//
2083// Memory Optimization
2084//===----------------------------------------------------------------------===//
2085
2086namespace {
2087
2088/// This is an extended version of TargetLowering::AddrMode
2089/// which holds actual Value*'s for register values.
2090struct ExtAddrMode : public TargetLowering::AddrMode {
2091 Value *BaseReg = nullptr;
2092 Value *ScaledReg = nullptr;
2093 Value *OriginalValue = nullptr;
2094 bool InBounds = true;
2095
2096 enum FieldName {
2097 NoField = 0x00,
2098 BaseRegField = 0x01,
2099 BaseGVField = 0x02,
2100 BaseOffsField = 0x04,
2101 ScaledRegField = 0x08,
2102 ScaleField = 0x10,
2103 MultipleFields = 0xff
2104 };
2105
2106
2107 ExtAddrMode() = default;
2108
2109 void print(raw_ostream &OS) const;
2110 void dump() const;
2111
2112 FieldName compare(const ExtAddrMode &other) {
2113 // First check that the types are the same on each field, as differing types
2114 // is something we can't cope with later on.
2115 if (BaseReg && other.BaseReg &&
2116 BaseReg->getType() != other.BaseReg->getType())
2117 return MultipleFields;
2118 if (BaseGV && other.BaseGV &&
2119 BaseGV->getType() != other.BaseGV->getType())
2120 return MultipleFields;
2121 if (ScaledReg && other.ScaledReg &&
2122 ScaledReg->getType() != other.ScaledReg->getType())
2123 return MultipleFields;
2124
2125 // Conservatively reject 'inbounds' mismatches.
2126 if (InBounds != other.InBounds)
2127 return MultipleFields;
2128
2129 // Check each field to see if it differs.
2130 unsigned Result = NoField;
2131 if (BaseReg != other.BaseReg)
2132 Result |= BaseRegField;
2133 if (BaseGV != other.BaseGV)
2134 Result |= BaseGVField;
2135 if (BaseOffs != other.BaseOffs)
2136 Result |= BaseOffsField;
2137 if (ScaledReg != other.ScaledReg)
2138 Result |= ScaledRegField;
2139 // Don't count 0 as being a different scale, because that actually means
2140 // unscaled (which will already be counted by having no ScaledReg).
2141 if (Scale && other.Scale && Scale != other.Scale)
2142 Result |= ScaleField;
2143
2144 if (countPopulation(Result) > 1)
2145 return MultipleFields;
2146 else
2147 return static_cast<FieldName>(Result);
2148 }
2149
2150 // An AddrMode is trivial if it involves no calculation i.e. it is just a base
2151 // with no offset.
2152 bool isTrivial() {
2153 // An AddrMode is (BaseGV + BaseReg + BaseOffs + ScaleReg * Scale) so it is
2154 // trivial if at most one of these terms is nonzero, except that BaseGV and
2155 // BaseReg both being zero actually means a null pointer value, which we
2156 // consider to be 'non-zero' here.
2157 return !BaseOffs && !Scale && !(BaseGV && BaseReg);
2158 }
2159
2160 Value *GetFieldAsValue(FieldName Field, Type *IntPtrTy) {
2161 switch (Field) {
2162 default:
2163 return nullptr;
2164 case BaseRegField:
2165 return BaseReg;
2166 case BaseGVField:
2167 return BaseGV;
2168 case ScaledRegField:
2169 return ScaledReg;
2170 case BaseOffsField:
2171 return ConstantInt::get(IntPtrTy, BaseOffs);
2172 }
2173 }
2174
2175 void SetCombinedField(FieldName Field, Value *V,
2176 const SmallVectorImpl<ExtAddrMode> &AddrModes) {
2177 switch (Field) {
2178 default:
2179 llvm_unreachable("Unhandled fields are expected to be rejected earlier")::llvm::llvm_unreachable_internal("Unhandled fields are expected to be rejected earlier"
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 2179)
;
2180 break;
2181 case ExtAddrMode::BaseRegField:
2182 BaseReg = V;
2183 break;
2184 case ExtAddrMode::BaseGVField:
2185 // A combined BaseGV is an Instruction, not a GlobalValue, so it goes
2186 // in the BaseReg field.
2187 assert(BaseReg == nullptr)((BaseReg == nullptr) ? static_cast<void> (0) : __assert_fail
("BaseReg == nullptr", "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 2187, __PRETTY_FUNCTION__))
;
2188 BaseReg = V;
2189 BaseGV = nullptr;
2190 break;
2191 case ExtAddrMode::ScaledRegField:
2192 ScaledReg = V;
2193 // If we have a mix of scaled and unscaled addrmodes then we want scale
2194 // to be the scale and not zero.
2195 if (!Scale)
2196 for (const ExtAddrMode &AM : AddrModes)
2197 if (AM.Scale) {
2198 Scale = AM.Scale;
2199 break;
2200 }
2201 break;
2202 case ExtAddrMode::BaseOffsField:
2203 // The offset is no longer a constant, so it goes in ScaledReg with a
2204 // scale of 1.
2205 assert(ScaledReg == nullptr)((ScaledReg == nullptr) ? static_cast<void> (0) : __assert_fail
("ScaledReg == nullptr", "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 2205, __PRETTY_FUNCTION__))
;
2206 ScaledReg = V;
2207 Scale = 1;
2208 BaseOffs = 0;
2209 break;
2210 }
2211 }
2212};
2213
2214} // end anonymous namespace
2215
2216#ifndef NDEBUG
2217static inline raw_ostream &operator<<(raw_ostream &OS, const ExtAddrMode &AM) {
2218 AM.print(OS);
2219 return OS;
2220}
2221#endif
2222
2223#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
2224void ExtAddrMode::print(raw_ostream &OS) const {
2225 bool NeedPlus = false;
2226 OS << "[";
2227 if (InBounds)
2228 OS << "inbounds ";
2229 if (BaseGV) {
2230 OS << (NeedPlus ? " + " : "")
2231 << "GV:";
2232 BaseGV->printAsOperand(OS, /*PrintType=*/false);
2233 NeedPlus = true;
2234 }
2235
2236 if (BaseOffs) {
2237 OS << (NeedPlus ? " + " : "")
2238 << BaseOffs;
2239 NeedPlus = true;
2240 }
2241
2242 if (BaseReg) {
2243 OS << (NeedPlus ? " + " : "")
2244 << "Base:";
2245 BaseReg->printAsOperand(OS, /*PrintType=*/false);
2246 NeedPlus = true;
2247 }
2248 if (Scale) {
2249 OS << (NeedPlus ? " + " : "")
2250 << Scale << "*";
2251 ScaledReg->printAsOperand(OS, /*PrintType=*/false);
2252 }
2253
2254 OS << ']';
2255}
2256
2257LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void ExtAddrMode::dump() const {
2258 print(dbgs());
2259 dbgs() << '\n';
2260}
2261#endif
2262
2263namespace {
2264
2265/// This class provides transaction based operation on the IR.
2266/// Every change made through this class is recorded in the internal state and
2267/// can be undone (rollback) until commit is called.
2268class TypePromotionTransaction {
2269 /// This represents the common interface of the individual transaction.
2270 /// Each class implements the logic for doing one specific modification on
2271 /// the IR via the TypePromotionTransaction.
2272 class TypePromotionAction {
2273 protected:
2274 /// The Instruction modified.
2275 Instruction *Inst;
2276
2277 public:
2278 /// Constructor of the action.
2279 /// The constructor performs the related action on the IR.
2280 TypePromotionAction(Instruction *Inst) : Inst(Inst) {}
2281
2282 virtual ~TypePromotionAction() = default;
2283
2284 /// Undo the modification done by this action.
2285 /// When this method is called, the IR must be in the same state as it was
2286 /// before this action was applied.
2287 /// \pre Undoing the action works if and only if the IR is in the exact same
2288 /// state as it was directly after this action was applied.
2289 virtual void undo() = 0;
2290
2291 /// Advocate every change made by this action.
2292 /// When the results on the IR of the action are to be kept, it is important
2293 /// to call this function, otherwise hidden information may be kept forever.
2294 virtual void commit() {
2295 // Nothing to be done, this action is not doing anything.
2296 }
2297 };
2298
2299 /// Utility to remember the position of an instruction.
2300 class InsertionHandler {
2301 /// Position of an instruction.
2302 /// Either an instruction:
2303 /// - Is the first in a basic block: BB is used.
2304 /// - Has a previous instruction: PrevInst is used.
2305 union {
2306 Instruction *PrevInst;
2307 BasicBlock *BB;
2308 } Point;
2309
2310 /// Remember whether or not the instruction had a previous instruction.
2311 bool HasPrevInstruction;
2312
2313 public:
2314 /// Record the position of \p Inst.
2315 InsertionHandler(Instruction *Inst) {
2316 BasicBlock::iterator It = Inst->getIterator();
2317 HasPrevInstruction = (It != (Inst->getParent()->begin()));
2318 if (HasPrevInstruction)
2319 Point.PrevInst = &*--It;
2320 else
2321 Point.BB = Inst->getParent();
2322 }
2323
2324 /// Insert \p Inst at the recorded position.
2325 void insert(Instruction *Inst) {
2326 if (HasPrevInstruction) {
2327 if (Inst->getParent())
2328 Inst->removeFromParent();
2329 Inst->insertAfter(Point.PrevInst);
2330 } else {
2331 Instruction *Position = &*Point.BB->getFirstInsertionPt();
2332 if (Inst->getParent())
2333 Inst->moveBefore(Position);
2334 else
2335 Inst->insertBefore(Position);
2336 }
2337 }
2338 };
2339
2340 /// Move an instruction before another.
2341 class InstructionMoveBefore : public TypePromotionAction {
2342 /// Original position of the instruction.
2343 InsertionHandler Position;
2344
2345 public:
2346 /// Move \p Inst before \p Before.
2347 InstructionMoveBefore(Instruction *Inst, Instruction *Before)
2348 : TypePromotionAction(Inst), Position(Inst) {
2349 LLVM_DEBUG(dbgs() << "Do: move: " << *Inst << "\nbefore: " << *Beforedo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: move: " << *
Inst << "\nbefore: " << *Before << "\n"; } }
while (false)
2350 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: move: " << *
Inst << "\nbefore: " << *Before << "\n"; } }
while (false)
;
2351 Inst->moveBefore(Before);
2352 }
2353
2354 /// Move the instruction back to its original position.
2355 void undo() override {
2356 LLVM_DEBUG(dbgs() << "Undo: moveBefore: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: moveBefore: " <<
*Inst << "\n"; } } while (false)
;
2357 Position.insert(Inst);
2358 }
2359 };
2360
2361 /// Set the operand of an instruction with a new value.
2362 class OperandSetter : public TypePromotionAction {
2363 /// Original operand of the instruction.
2364 Value *Origin;
2365
2366 /// Index of the modified instruction.
2367 unsigned Idx;
2368
2369 public:
2370 /// Set \p Idx operand of \p Inst with \p NewVal.
2371 OperandSetter(Instruction *Inst, unsigned Idx, Value *NewVal)
2372 : TypePromotionAction(Inst), Idx(Idx) {
2373 LLVM_DEBUG(dbgs() << "Do: setOperand: " << Idx << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: setOperand: " <<
Idx << "\n" << "for:" << *Inst << "\n"
<< "with:" << *NewVal << "\n"; } } while (
false)
2374 << "for:" << *Inst << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: setOperand: " <<
Idx << "\n" << "for:" << *Inst << "\n"
<< "with:" << *NewVal << "\n"; } } while (
false)
2375 << "with:" << *NewVal << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: setOperand: " <<
Idx << "\n" << "for:" << *Inst << "\n"
<< "with:" << *NewVal << "\n"; } } while (
false)
;
2376 Origin = Inst->getOperand(Idx);
2377 Inst->setOperand(Idx, NewVal);
2378 }
2379
2380 /// Restore the original value of the instruction.
2381 void undo() override {
2382 LLVM_DEBUG(dbgs() << "Undo: setOperand:" << Idx << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: setOperand:" <<
Idx << "\n" << "for: " << *Inst << "\n"
<< "with: " << *Origin << "\n"; } } while (
false)
2383 << "for: " << *Inst << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: setOperand:" <<
Idx << "\n" << "for: " << *Inst << "\n"
<< "with: " << *Origin << "\n"; } } while (
false)
2384 << "with: " << *Origin << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: setOperand:" <<
Idx << "\n" << "for: " << *Inst << "\n"
<< "with: " << *Origin << "\n"; } } while (
false)
;
2385 Inst->setOperand(Idx, Origin);
2386 }
2387 };
2388
2389 /// Hide the operands of an instruction.
2390 /// Do as if this instruction was not using any of its operands.
2391 class OperandsHider : public TypePromotionAction {
2392 /// The list of original operands.
2393 SmallVector<Value *, 4> OriginalValues;
2394
2395 public:
2396 /// Remove \p Inst from the uses of the operands of \p Inst.
2397 OperandsHider(Instruction *Inst) : TypePromotionAction(Inst) {
2398 LLVM_DEBUG(dbgs() << "Do: OperandsHider: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: OperandsHider: " <<
*Inst << "\n"; } } while (false)
;
2399 unsigned NumOpnds = Inst->getNumOperands();
2400 OriginalValues.reserve(NumOpnds);
2401 for (unsigned It = 0; It < NumOpnds; ++It) {
2402 // Save the current operand.
2403 Value *Val = Inst->getOperand(It);
2404 OriginalValues.push_back(Val);
2405 // Set a dummy one.
2406 // We could use OperandSetter here, but that would imply an overhead
2407 // that we are not willing to pay.
2408 Inst->setOperand(It, UndefValue::get(Val->getType()));
2409 }
2410 }
2411
2412 /// Restore the original list of uses.
2413 void undo() override {
2414 LLVM_DEBUG(dbgs() << "Undo: OperandsHider: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: OperandsHider: "
<< *Inst << "\n"; } } while (false)
;
2415 for (unsigned It = 0, EndIt = OriginalValues.size(); It != EndIt; ++It)
2416 Inst->setOperand(It, OriginalValues[It]);
2417 }
2418 };
2419
2420 /// Build a truncate instruction.
2421 class TruncBuilder : public TypePromotionAction {
2422 Value *Val;
2423
2424 public:
2425 /// Build a truncate instruction of \p Opnd producing a \p Ty
2426 /// result.
2427 /// trunc Opnd to Ty.
2428 TruncBuilder(Instruction *Opnd, Type *Ty) : TypePromotionAction(Opnd) {
2429 IRBuilder<> Builder(Opnd);
2430 Val = Builder.CreateTrunc(Opnd, Ty, "promoted");
2431 LLVM_DEBUG(dbgs() << "Do: TruncBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: TruncBuilder: " <<
*Val << "\n"; } } while (false)
;
2432 }
2433
2434 /// Get the built value.
2435 Value *getBuiltValue() { return Val; }
2436
2437 /// Remove the built instruction.
2438 void undo() override {
2439 LLVM_DEBUG(dbgs() << "Undo: TruncBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: TruncBuilder: " <<
*Val << "\n"; } } while (false)
;
2440 if (Instruction *IVal = dyn_cast<Instruction>(Val))
2441 IVal->eraseFromParent();
2442 }
2443 };
2444
2445 /// Build a sign extension instruction.
2446 class SExtBuilder : public TypePromotionAction {
2447 Value *Val;
2448
2449 public:
2450 /// Build a sign extension instruction of \p Opnd producing a \p Ty
2451 /// result.
2452 /// sext Opnd to Ty.
2453 SExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty)
2454 : TypePromotionAction(InsertPt) {
2455 IRBuilder<> Builder(InsertPt);
2456 Val = Builder.CreateSExt(Opnd, Ty, "promoted");
2457 LLVM_DEBUG(dbgs() << "Do: SExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: SExtBuilder: " <<
*Val << "\n"; } } while (false)
;
2458 }
2459
2460 /// Get the built value.
2461 Value *getBuiltValue() { return Val; }
2462
2463 /// Remove the built instruction.
2464 void undo() override {
2465 LLVM_DEBUG(dbgs() << "Undo: SExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: SExtBuilder: " <<
*Val << "\n"; } } while (false)
;
2466 if (Instruction *IVal = dyn_cast<Instruction>(Val))
2467 IVal->eraseFromParent();
2468 }
2469 };
2470
2471 /// Build a zero extension instruction.
2472 class ZExtBuilder : public TypePromotionAction {
2473 Value *Val;
2474
2475 public:
2476 /// Build a zero extension instruction of \p Opnd producing a \p Ty
2477 /// result.
2478 /// zext Opnd to Ty.
2479 ZExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty)
2480 : TypePromotionAction(InsertPt) {
2481 IRBuilder<> Builder(InsertPt);
2482 Val = Builder.CreateZExt(Opnd, Ty, "promoted");
2483 LLVM_DEBUG(dbgs() << "Do: ZExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: ZExtBuilder: " <<
*Val << "\n"; } } while (false)
;
2484 }
2485
2486 /// Get the built value.
2487 Value *getBuiltValue() { return Val; }
2488
2489 /// Remove the built instruction.
2490 void undo() override {
2491 LLVM_DEBUG(dbgs() << "Undo: ZExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: ZExtBuilder: " <<
*Val << "\n"; } } while (false)
;
2492 if (Instruction *IVal = dyn_cast<Instruction>(Val))
2493 IVal->eraseFromParent();
2494 }
2495 };
2496
2497 /// Mutate an instruction to another type.
2498 class TypeMutator : public TypePromotionAction {
2499 /// Record the original type.
2500 Type *OrigTy;
2501
2502 public:
2503 /// Mutate the type of \p Inst into \p NewTy.
2504 TypeMutator(Instruction *Inst, Type *NewTy)
2505 : TypePromotionAction(Inst), OrigTy(Inst->getType()) {
2506 LLVM_DEBUG(dbgs() << "Do: MutateType: " << *Inst << " with " << *NewTydo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: MutateType: " <<
*Inst << " with " << *NewTy << "\n"; } } while
(false)
2507 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: MutateType: " <<
*Inst << " with " << *NewTy << "\n"; } } while
(false)
;
2508 Inst->mutateType(NewTy);
2509 }
2510
2511 /// Mutate the instruction back to its original type.
2512 void undo() override {
2513 LLVM_DEBUG(dbgs() << "Undo: MutateType: " << *Inst << " with " << *OrigTydo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: MutateType: " <<
*Inst << " with " << *OrigTy << "\n"; } } while
(false)
2514 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: MutateType: " <<
*Inst << " with " << *OrigTy << "\n"; } } while
(false)
;
2515 Inst->mutateType(OrigTy);
2516 }
2517 };
2518
2519 /// Replace the uses of an instruction by another instruction.
2520 class UsesReplacer : public TypePromotionAction {
2521 /// Helper structure to keep track of the replaced uses.
2522 struct InstructionAndIdx {
2523 /// The instruction using the instruction.
2524 Instruction *Inst;
2525
2526 /// The index where this instruction is used for Inst.
2527 unsigned Idx;
2528
2529 InstructionAndIdx(Instruction *Inst, unsigned Idx)
2530 : Inst(Inst), Idx(Idx) {}
2531 };
2532
2533 /// Keep track of the original uses (pair Instruction, Index).
2534 SmallVector<InstructionAndIdx, 4> OriginalUses;
2535 /// Keep track of the debug users.
2536 SmallVector<DbgValueInst *, 1> DbgValues;
2537
2538 using use_iterator = SmallVectorImpl<InstructionAndIdx>::iterator;
2539
2540 public:
2541 /// Replace all the use of \p Inst by \p New.
2542 UsesReplacer(Instruction *Inst, Value *New) : TypePromotionAction(Inst) {
2543 LLVM_DEBUG(dbgs() << "Do: UsersReplacer: " << *Inst << " with " << *Newdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: UsersReplacer: " <<
*Inst << " with " << *New << "\n"; } } while
(false)
2544 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: UsersReplacer: " <<
*Inst << " with " << *New << "\n"; } } while
(false)
;
2545 // Record the original uses.
2546 for (Use &U : Inst->uses()) {
2547 Instruction *UserI = cast<Instruction>(U.getUser());
2548 OriginalUses.push_back(InstructionAndIdx(UserI, U.getOperandNo()));
2549 }
2550 // Record the debug uses separately. They are not in the instruction's
2551 // use list, but they are replaced by RAUW.
2552 findDbgValues(DbgValues, Inst);
2553
2554 // Now, we can replace the uses.
2555 Inst->replaceAllUsesWith(New);
2556 }
2557
2558 /// Reassign the original uses of Inst to Inst.
2559 void undo() override {
2560 LLVM_DEBUG(dbgs() << "Undo: UsersReplacer: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: UsersReplacer: "
<< *Inst << "\n"; } } while (false)
;
2561 for (use_iterator UseIt = OriginalUses.begin(),
2562 EndIt = OriginalUses.end();
2563 UseIt != EndIt; ++UseIt) {
2564 UseIt->Inst->setOperand(UseIt->Idx, Inst);
2565 }
2566 // RAUW has replaced all original uses with references to the new value,
2567 // including the debug uses. Since we are undoing the replacements,
2568 // the original debug uses must also be reinstated to maintain the
2569 // correctness and utility of debug value instructions.
2570 for (auto *DVI: DbgValues) {
2571 LLVMContext &Ctx = Inst->getType()->getContext();
2572 auto *MV = MetadataAsValue::get(Ctx, ValueAsMetadata::get(Inst));
2573 DVI->setOperand(0, MV);
2574 }
2575 }
2576 };
2577
2578 /// Remove an instruction from the IR.
2579 class InstructionRemover : public TypePromotionAction {
2580 /// Original position of the instruction.
2581 InsertionHandler Inserter;
2582
2583 /// Helper structure to hide all the link to the instruction. In other
2584 /// words, this helps to do as if the instruction was removed.
2585 OperandsHider Hider;
2586
2587 /// Keep track of the uses replaced, if any.
2588 UsesReplacer *Replacer = nullptr;
2589
2590 /// Keep track of instructions removed.
2591 SetOfInstrs &RemovedInsts;
2592
2593 public:
2594 /// Remove all reference of \p Inst and optionally replace all its
2595 /// uses with New.
2596 /// \p RemovedInsts Keep track of the instructions removed by this Action.
2597 /// \pre If !Inst->use_empty(), then New != nullptr
2598 InstructionRemover(Instruction *Inst, SetOfInstrs &RemovedInsts,
2599 Value *New = nullptr)
2600 : TypePromotionAction(Inst), Inserter(Inst), Hider(Inst),
2601 RemovedInsts(RemovedInsts) {
2602 if (New)
2603 Replacer = new UsesReplacer(Inst, New);
2604 LLVM_DEBUG(dbgs() << "Do: InstructionRemover: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: InstructionRemover: "
<< *Inst << "\n"; } } while (false)
;
2605 RemovedInsts.insert(Inst);
2606 /// The instructions removed here will be freed after completing
2607 /// optimizeBlock() for all blocks as we need to keep track of the
2608 /// removed instructions during promotion.
2609 Inst->removeFromParent();
2610 }
2611
2612 ~InstructionRemover() override { delete Replacer; }
2613
2614 /// Resurrect the instruction and reassign it to the proper uses if
2615 /// new value was provided when build this action.
2616 void undo() override {
2617 LLVM_DEBUG(dbgs() << "Undo: InstructionRemover: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: InstructionRemover: "
<< *Inst << "\n"; } } while (false)
;
2618 Inserter.insert(Inst);
2619 if (Replacer)
2620 Replacer->undo();
2621 Hider.undo();
2622 RemovedInsts.erase(Inst);
2623 }
2624 };
2625
2626public:
2627 /// Restoration point.
2628 /// The restoration point is a pointer to an action instead of an iterator
2629 /// because the iterator may be invalidated but not the pointer.
2630 using ConstRestorationPt = const TypePromotionAction *;
2631
2632 TypePromotionTransaction(SetOfInstrs &RemovedInsts)
2633 : RemovedInsts(RemovedInsts) {}
2634
2635 /// Advocate every changes made in that transaction.
2636 void commit();
2637
2638 /// Undo all the changes made after the given point.
2639 void rollback(ConstRestorationPt Point);
2640
2641 /// Get the current restoration point.
2642 ConstRestorationPt getRestorationPoint() const;
2643
2644 /// \name API for IR modification with state keeping to support rollback.
2645 /// @{
2646 /// Same as Instruction::setOperand.
2647 void setOperand(Instruction *Inst, unsigned Idx, Value *NewVal);
2648
2649 /// Same as Instruction::eraseFromParent.
2650 void eraseInstruction(Instruction *Inst, Value *NewVal = nullptr);
2651
2652 /// Same as Value::replaceAllUsesWith.
2653 void replaceAllUsesWith(Instruction *Inst, Value *New);
2654
2655 /// Same as Value::mutateType.
2656 void mutateType(Instruction *Inst, Type *NewTy);
2657
2658 /// Same as IRBuilder::createTrunc.
2659 Value *createTrunc(Instruction *Opnd, Type *Ty);
2660
2661 /// Same as IRBuilder::createSExt.
2662 Value *createSExt(Instruction *Inst, Value *Opnd, Type *Ty);
2663
2664 /// Same as IRBuilder::createZExt.
2665 Value *createZExt(Instruction *Inst, Value *Opnd, Type *Ty);
2666
2667 /// Same as Instruction::moveBefore.
2668 void moveBefore(Instruction *Inst, Instruction *Before);
2669 /// @}
2670
2671private:
2672 /// The ordered list of actions made so far.
2673 SmallVector<std::unique_ptr<TypePromotionAction>, 16> Actions;
2674
2675 using CommitPt = SmallVectorImpl<std::unique_ptr<TypePromotionAction>>::iterator;
2676
2677 SetOfInstrs &RemovedInsts;
2678};
2679
2680} // end anonymous namespace
2681
2682void TypePromotionTransaction::setOperand(Instruction *Inst, unsigned Idx,
2683 Value *NewVal) {
2684 Actions.push_back(llvm::make_unique<TypePromotionTransaction::OperandSetter>(
2685 Inst, Idx, NewVal));
2686}
2687
2688void TypePromotionTransaction::eraseInstruction(Instruction *Inst,
2689 Value *NewVal) {
2690 Actions.push_back(
2691 llvm::make_unique<TypePromotionTransaction::InstructionRemover>(
2692 Inst, RemovedInsts, NewVal));
2693}
2694
2695void TypePromotionTransaction::replaceAllUsesWith(Instruction *Inst,
2696 Value *New) {
2697 Actions.push_back(
2698 llvm::make_unique<TypePromotionTransaction::UsesReplacer>(Inst, New));
2699}
2700
2701void TypePromotionTransaction::mutateType(Instruction *Inst, Type *NewTy) {
2702 Actions.push_back(
2703 llvm::make_unique<TypePromotionTransaction::TypeMutator>(Inst, NewTy));
2704}
2705
2706Value *TypePromotionTransaction::createTrunc(Instruction *Opnd,
2707 Type *Ty) {
2708 std::unique_ptr<TruncBuilder> Ptr(new TruncBuilder(Opnd, Ty));
2709 Value *Val = Ptr->getBuiltValue();
2710 Actions.push_back(std::move(Ptr));
2711 return Val;
2712}
2713
2714Value *TypePromotionTransaction::createSExt(Instruction *Inst,
2715 Value *Opnd, Type *Ty) {
2716 std::unique_ptr<SExtBuilder> Ptr(new SExtBuilder(Inst, Opnd, Ty));
2717 Value *Val = Ptr->getBuiltValue();
2718 Actions.push_back(std::move(Ptr));
2719 return Val;
2720}
2721
2722Value *TypePromotionTransaction::createZExt(Instruction *Inst,
2723 Value *Opnd, Type *Ty) {
2724 std::unique_ptr<ZExtBuilder> Ptr(new ZExtBuilder(Inst, Opnd, Ty));
2725 Value *Val = Ptr->getBuiltValue();
2726 Actions.push_back(std::move(Ptr));
2727 return Val;
2728}
2729
2730void TypePromotionTransaction::moveBefore(Instruction *Inst,
2731 Instruction *Before) {
2732 Actions.push_back(
2733 llvm::make_unique<TypePromotionTransaction::InstructionMoveBefore>(
2734 Inst, Before));
2735}
2736
2737TypePromotionTransaction::ConstRestorationPt
2738TypePromotionTransaction::getRestorationPoint() const {
2739 return !Actions.empty() ? Actions.back().get() : nullptr;
2740}
2741
2742void TypePromotionTransaction::commit() {
2743 for (CommitPt It = Actions.begin(), EndIt = Actions.end(); It != EndIt;
2744 ++It)
2745 (*It)->commit();
2746 Actions.clear();
2747}
2748
2749void TypePromotionTransaction::rollback(
2750 TypePromotionTransaction::ConstRestorationPt Point) {
2751 while (!Actions.empty() && Point != Actions.back().get()) {
2752 std::unique_ptr<TypePromotionAction> Curr = Actions.pop_back_val();
2753 Curr->undo();
2754 }
2755}
2756
2757namespace {
2758
2759/// A helper class for matching addressing modes.
2760///
2761/// This encapsulates the logic for matching the target-legal addressing modes.
2762class AddressingModeMatcher {
2763 SmallVectorImpl<Instruction*> &AddrModeInsts;
2764 const TargetLowering &TLI;
2765 const TargetRegisterInfo &TRI;
2766 const DataLayout &DL;
2767
2768 /// AccessTy/MemoryInst - This is the type for the access (e.g. double) and
2769 /// the memory instruction that we're computing this address for.
2770 Type *AccessTy;
2771 unsigned AddrSpace;
2772 Instruction *MemoryInst;
2773
2774 /// This is the addressing mode that we're building up. This is
2775 /// part of the return value of this addressing mode matching stuff.
2776 ExtAddrMode &AddrMode;
2777
2778 /// The instructions inserted by other CodeGenPrepare optimizations.
2779 const SetOfInstrs &InsertedInsts;
2780
2781 /// A map from the instructions to their type before promotion.
2782 InstrToOrigTy &PromotedInsts;
2783
2784 /// The ongoing transaction where every action should be registered.
2785 TypePromotionTransaction &TPT;
2786
2787 // A GEP which has too large offset to be folded into the addressing mode.
2788 std::pair<AssertingVH<GetElementPtrInst>, int64_t> &LargeOffsetGEP;
2789
2790 /// This is set to true when we should not do profitability checks.
2791 /// When true, IsProfitableToFoldIntoAddressingMode always returns true.
2792 bool IgnoreProfitability;
2793
2794 AddressingModeMatcher(
2795 SmallVectorImpl<Instruction *> &AMI, const TargetLowering &TLI,
2796 const TargetRegisterInfo &TRI, Type *AT, unsigned AS, Instruction *MI,
2797 ExtAddrMode &AM, const SetOfInstrs &InsertedInsts,
2798 InstrToOrigTy &PromotedInsts, TypePromotionTransaction &TPT,
2799 std::pair<AssertingVH<GetElementPtrInst>, int64_t> &LargeOffsetGEP)
2800 : AddrModeInsts(AMI), TLI(TLI), TRI(TRI),
2801 DL(MI->getModule()->getDataLayout()), AccessTy(AT), AddrSpace(AS),
2802 MemoryInst(MI), AddrMode(AM), InsertedInsts(InsertedInsts),
2803 PromotedInsts(PromotedInsts), TPT(TPT), LargeOffsetGEP(LargeOffsetGEP) {
2804 IgnoreProfitability = false;
2805 }
2806
2807public:
2808 /// Find the maximal addressing mode that a load/store of V can fold,
2809 /// give an access type of AccessTy. This returns a list of involved
2810 /// instructions in AddrModeInsts.
2811 /// \p InsertedInsts The instructions inserted by other CodeGenPrepare
2812 /// optimizations.
2813 /// \p PromotedInsts maps the instructions to their type before promotion.
2814 /// \p The ongoing transaction where every action should be registered.
2815 static ExtAddrMode
2816 Match(Value *V, Type *AccessTy, unsigned AS, Instruction *MemoryInst,
2817 SmallVectorImpl<Instruction *> &AddrModeInsts,
2818 const TargetLowering &TLI, const TargetRegisterInfo &TRI,
2819 const SetOfInstrs &InsertedInsts, InstrToOrigTy &PromotedInsts,
2820 TypePromotionTransaction &TPT,
2821 std::pair<AssertingVH<GetElementPtrInst>, int64_t> &LargeOffsetGEP) {
2822 ExtAddrMode Result;
2823
2824 bool Success = AddressingModeMatcher(AddrModeInsts, TLI, TRI, AccessTy, AS,
2825 MemoryInst, Result, InsertedInsts,
2826 PromotedInsts, TPT, LargeOffsetGEP)
2827 .matchAddr(V, 0);
2828 (void)Success; assert(Success && "Couldn't select *anything*?")((Success && "Couldn't select *anything*?") ? static_cast
<void> (0) : __assert_fail ("Success && \"Couldn't select *anything*?\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 2828, __PRETTY_FUNCTION__))
;
2829 return Result;
2830 }
2831
2832private:
2833 bool matchScaledValue(Value *ScaleReg, int64_t Scale, unsigned Depth);
2834 bool matchAddr(Value *Addr, unsigned Depth);
2835 bool matchOperationAddr(User *AddrInst, unsigned Opcode, unsigned Depth,
2836 bool *MovedAway = nullptr);
2837 bool isProfitableToFoldIntoAddressingMode(Instruction *I,
2838 ExtAddrMode &AMBefore,
2839 ExtAddrMode &AMAfter);
2840 bool valueAlreadyLiveAtInst(Value *Val, Value *KnownLive1, Value *KnownLive2);
2841 bool isPromotionProfitable(unsigned NewCost, unsigned OldCost,
2842 Value *PromotedOperand) const;
2843};
2844
2845class PhiNodeSet;
2846
2847/// An iterator for PhiNodeSet.
2848class PhiNodeSetIterator {
2849 PhiNodeSet * const Set;
2850 size_t CurrentIndex = 0;
2851
2852public:
2853 /// The constructor. Start should point to either a valid element, or be equal
2854 /// to the size of the underlying SmallVector of the PhiNodeSet.
2855 PhiNodeSetIterator(PhiNodeSet * const Set, size_t Start);
2856 PHINode * operator*() const;
2857 PhiNodeSetIterator& operator++();
2858 bool operator==(const PhiNodeSetIterator &RHS) const;
2859 bool operator!=(const PhiNodeSetIterator &RHS) const;
2860};
2861
2862/// Keeps a set of PHINodes.
2863///
2864/// This is a minimal set implementation for a specific use case:
2865/// It is very fast when there are very few elements, but also provides good
2866/// performance when there are many. It is similar to SmallPtrSet, but also
2867/// provides iteration by insertion order, which is deterministic and stable
2868/// across runs. It is also similar to SmallSetVector, but provides removing
2869/// elements in O(1) time. This is achieved by not actually removing the element
2870/// from the underlying vector, so comes at the cost of using more memory, but
2871/// that is fine, since PhiNodeSets are used as short lived objects.
2872class PhiNodeSet {
2873 friend class PhiNodeSetIterator;
2874
2875 using MapType = SmallDenseMap<PHINode *, size_t, 32>;
2876 using iterator = PhiNodeSetIterator;
2877
2878 /// Keeps the elements in the order of their insertion in the underlying
2879 /// vector. To achieve constant time removal, it never deletes any element.
2880 SmallVector<PHINode *, 32> NodeList;
2881
2882 /// Keeps the elements in the underlying set implementation. This (and not the
2883 /// NodeList defined above) is the source of truth on whether an element
2884 /// is actually in the collection.
2885 MapType NodeMap;
2886
2887 /// Points to the first valid (not deleted) element when the set is not empty
2888 /// and the value is not zero. Equals to the size of the underlying vector
2889 /// when the set is empty. When the value is 0, as in the beginning, the
2890 /// first element may or may not be valid.
2891 size_t FirstValidElement = 0;
2892
2893public:
2894 /// Inserts a new element to the collection.
2895 /// \returns true if the element is actually added, i.e. was not in the
2896 /// collection before the operation.
2897 bool insert(PHINode *Ptr) {
2898 if (NodeMap.insert(std::make_pair(Ptr, NodeList.size())).second) {
2899 NodeList.push_back(Ptr);
2900 return true;
2901 }
2902 return false;
2903 }
2904
2905 /// Removes the element from the collection.
2906 /// \returns whether the element is actually removed, i.e. was in the
2907 /// collection before the operation.
2908 bool erase(PHINode *Ptr) {
2909 auto it = NodeMap.find(Ptr);
2910 if (it != NodeMap.end()) {
2911 NodeMap.erase(Ptr);
2912 SkipRemovedElements(FirstValidElement);
2913 return true;
2914 }
2915 return false;
2916 }
2917
2918 /// Removes all elements and clears the collection.
2919 void clear() {
2920 NodeMap.clear();
2921 NodeList.clear();
2922 FirstValidElement = 0;
2923 }
2924
2925 /// \returns an iterator that will iterate the elements in the order of
2926 /// insertion.
2927 iterator begin() {
2928 if (FirstValidElement == 0)
2929 SkipRemovedElements(FirstValidElement);
2930 return PhiNodeSetIterator(this, FirstValidElement);
2931 }
2932
2933 /// \returns an iterator that points to the end of the collection.
2934 iterator end() { return PhiNodeSetIterator(this, NodeList.size()); }
2935
2936 /// Returns the number of elements in the collection.
2937 size_t size() const {
2938 return NodeMap.size();
2939 }
2940
2941 /// \returns 1 if the given element is in the collection, and 0 if otherwise.
2942 size_t count(PHINode *Ptr) const {
2943 return NodeMap.count(Ptr);
2944 }
2945
2946private:
2947 /// Updates the CurrentIndex so that it will point to a valid element.
2948 ///
2949 /// If the element of NodeList at CurrentIndex is valid, it does not
2950 /// change it. If there are no more valid elements, it updates CurrentIndex
2951 /// to point to the end of the NodeList.
2952 void SkipRemovedElements(size_t &CurrentIndex) {
2953 while (CurrentIndex < NodeList.size()) {
2954 auto it = NodeMap.find(NodeList[CurrentIndex]);
2955 // If the element has been deleted and added again later, NodeMap will
2956 // point to a different index, so CurrentIndex will still be invalid.
2957 if (it != NodeMap.end() && it->second == CurrentIndex)
2958 break;
2959 ++CurrentIndex;
2960 }
2961 }
2962};
2963
2964PhiNodeSetIterator::PhiNodeSetIterator(PhiNodeSet *const Set, size_t Start)
2965 : Set(Set), CurrentIndex(Start) {}
2966
2967PHINode * PhiNodeSetIterator::operator*() const {
2968 assert(CurrentIndex < Set->NodeList.size() &&((CurrentIndex < Set->NodeList.size() && "PhiNodeSet access out of range"
) ? static_cast<void> (0) : __assert_fail ("CurrentIndex < Set->NodeList.size() && \"PhiNodeSet access out of range\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 2969, __PRETTY_FUNCTION__))
2969 "PhiNodeSet access out of range")((CurrentIndex < Set->NodeList.size() && "PhiNodeSet access out of range"
) ? static_cast<void> (0) : __assert_fail ("CurrentIndex < Set->NodeList.size() && \"PhiNodeSet access out of range\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 2969, __PRETTY_FUNCTION__))
;
2970 return Set->NodeList[CurrentIndex];
2971}
2972
2973PhiNodeSetIterator& PhiNodeSetIterator::operator++() {
2974 assert(CurrentIndex < Set->NodeList.size() &&((CurrentIndex < Set->NodeList.size() && "PhiNodeSet access out of range"
) ? static_cast<void> (0) : __assert_fail ("CurrentIndex < Set->NodeList.size() && \"PhiNodeSet access out of range\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 2975, __PRETTY_FUNCTION__))
2975 "PhiNodeSet access out of range")((CurrentIndex < Set->NodeList.size() && "PhiNodeSet access out of range"
) ? static_cast<void> (0) : __assert_fail ("CurrentIndex < Set->NodeList.size() && \"PhiNodeSet access out of range\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 2975, __PRETTY_FUNCTION__))
;
2976 ++CurrentIndex;
2977 Set->SkipRemovedElements(CurrentIndex);
2978 return *this;
2979}
2980
2981bool PhiNodeSetIterator::operator==(const PhiNodeSetIterator &RHS) const {
2982 return CurrentIndex == RHS.CurrentIndex;
2983}
2984
2985bool PhiNodeSetIterator::operator!=(const PhiNodeSetIterator &RHS) const {
2986 return !((*this) == RHS);
2987}
2988
2989/// Keep track of simplification of Phi nodes.
2990/// Accept the set of all phi nodes and erase phi node from this set
2991/// if it is simplified.
2992class SimplificationTracker {
2993 DenseMap<Value *, Value *> Storage;
2994 const SimplifyQuery &SQ;
2995 // Tracks newly created Phi nodes. The elements are iterated by insertion
2996 // order.
2997 PhiNodeSet AllPhiNodes;
2998 // Tracks newly created Select nodes.
2999 SmallPtrSet<SelectInst *, 32> AllSelectNodes;
3000
3001public:
3002 SimplificationTracker(const SimplifyQuery &sq)
3003 : SQ(sq) {}
3004
3005 Value *Get(Value *V) {
3006 do {
3007 auto SV = Storage.find(V);
3008 if (SV == Storage.end())
3009 return V;
3010 V = SV->second;
3011 } while (true);
3012 }
3013
3014 Value *Simplify(Value *Val) {
3015 SmallVector<Value *, 32> WorkList;
3016 SmallPtrSet<Value *, 32> Visited;
3017 WorkList.push_back(Val);
3018 while (!WorkList.empty()) {
3019 auto P = WorkList.pop_back_val();
3020 if (!Visited.insert(P).second)
3021 continue;
3022 if (auto *PI = dyn_cast<Instruction>(P))
3023 if (Value *V = SimplifyInstruction(cast<Instruction>(PI), SQ)) {
3024 for (auto *U : PI->users())
3025 WorkList.push_back(cast<Value>(U));
3026 Put(PI, V);
3027 PI->replaceAllUsesWith(V);
3028 if (auto *PHI = dyn_cast<PHINode>(PI))
3029 AllPhiNodes.erase(PHI);
3030 if (auto *Select = dyn_cast<SelectInst>(PI))
3031 AllSelectNodes.erase(Select);
3032 PI->eraseFromParent();
3033 }
3034 }
3035 return Get(Val);
3036 }
3037
3038 void Put(Value *From, Value *To) {
3039 Storage.insert({ From, To });
3040 }
3041
3042 void ReplacePhi(PHINode *From, PHINode *To) {
3043 Value* OldReplacement = Get(From);
3044 while (OldReplacement != From) {
3045 From = To;
3046 To = dyn_cast<PHINode>(OldReplacement);
3047 OldReplacement = Get(From);
3048 }
3049 assert(Get(To) == To && "Replacement PHI node is already replaced.")((Get(To) == To && "Replacement PHI node is already replaced."
) ? static_cast<void> (0) : __assert_fail ("Get(To) == To && \"Replacement PHI node is already replaced.\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 3049, __PRETTY_FUNCTION__))
;
3050 Put(From, To);
3051 From->replaceAllUsesWith(To);
3052 AllPhiNodes.erase(From);
3053 From->eraseFromParent();
3054 }
3055
3056 PhiNodeSet& newPhiNodes() { return AllPhiNodes; }
3057
3058 void insertNewPhi(PHINode *PN) { AllPhiNodes.insert(PN); }
3059
3060 void insertNewSelect(SelectInst *SI) { AllSelectNodes.insert(SI); }
3061
3062 unsigned countNewPhiNodes() const { return AllPhiNodes.size(); }
3063
3064 unsigned countNewSelectNodes() const { return AllSelectNodes.size(); }
3065
3066 void destroyNewNodes(Type *CommonType) {
3067 // For safe erasing, replace the uses with dummy value first.
3068 auto Dummy = UndefValue::get(CommonType);
3069 for (auto I : AllPhiNodes) {
3070 I->replaceAllUsesWith(Dummy);
3071 I->eraseFromParent();
3072 }
3073 AllPhiNodes.clear();
3074 for (auto I : AllSelectNodes) {
3075 I->replaceAllUsesWith(Dummy);
3076 I->eraseFromParent();
3077 }
3078 AllSelectNodes.clear();
3079 }
3080};
3081
3082/// A helper class for combining addressing modes.
3083class AddressingModeCombiner {
3084 typedef DenseMap<Value *, Value *> FoldAddrToValueMapping;
3085 typedef std::pair<PHINode *, PHINode *> PHIPair;
3086
3087private:
3088 /// The addressing modes we've collected.
3089 SmallVector<ExtAddrMode, 16> AddrModes;
3090
3091 /// The field in which the AddrModes differ, when we have more than one.
3092 ExtAddrMode::FieldName DifferentField = ExtAddrMode::NoField;
3093
3094 /// Are the AddrModes that we have all just equal to their original values?
3095 bool AllAddrModesTrivial = true;
3096
3097 /// Common Type for all different fields in addressing modes.
3098 Type *CommonType;
3099
3100 /// SimplifyQuery for simplifyInstruction utility.
3101 const SimplifyQuery &SQ;
3102
3103 /// Original Address.
3104 Value *Original;
3105
3106public:
3107 AddressingModeCombiner(const SimplifyQuery &_SQ, Value *OriginalValue)
3108 : CommonType(nullptr), SQ(_SQ), Original(OriginalValue) {}
3109
3110 /// Get the combined AddrMode
3111 const ExtAddrMode &getAddrMode() const {
3112 return AddrModes[0];
3113 }
3114
3115 /// Add a new AddrMode if it's compatible with the AddrModes we already
3116 /// have.
3117 /// \return True iff we succeeded in doing so.
3118 bool addNewAddrMode(ExtAddrMode &NewAddrMode) {
3119 // Take note of if we have any non-trivial AddrModes, as we need to detect
3120 // when all AddrModes are trivial as then we would introduce a phi or select
3121 // which just duplicates what's already there.
3122 AllAddrModesTrivial = AllAddrModesTrivial && NewAddrMode.isTrivial();
3123
3124 // If this is the first addrmode then everything is fine.
3125 if (AddrModes.empty()) {
3126 AddrModes.emplace_back(NewAddrMode);
3127 return true;
3128 }
3129
3130 // Figure out how different this is from the other address modes, which we
3131 // can do just by comparing against the first one given that we only care
3132 // about the cumulative difference.
3133 ExtAddrMode::FieldName ThisDifferentField =
3134 AddrModes[0].compare(NewAddrMode);
3135 if (DifferentField == ExtAddrMode::NoField)
3136 DifferentField = ThisDifferentField;
3137 else if (DifferentField != ThisDifferentField)
3138 DifferentField = ExtAddrMode::MultipleFields;
3139
3140 // If NewAddrMode differs in more than one dimension we cannot handle it.
3141 bool CanHandle = DifferentField != ExtAddrMode::MultipleFields;
3142
3143 // If Scale Field is different then we reject.
3144 CanHandle = CanHandle && DifferentField != ExtAddrMode::ScaleField;
3145
3146 // We also must reject the case when base offset is different and
3147 // scale reg is not null, we cannot handle this case due to merge of
3148 // different offsets will be used as ScaleReg.
3149 CanHandle = CanHandle && (DifferentField != ExtAddrMode::BaseOffsField ||
3150 !NewAddrMode.ScaledReg);
3151
3152 // We also must reject the case when GV is different and BaseReg installed
3153 // due to we want to use base reg as a merge of GV values.
3154 CanHandle = CanHandle && (DifferentField != ExtAddrMode::BaseGVField ||
3155 !NewAddrMode.HasBaseReg);
3156
3157 // Even if NewAddMode is the same we still need to collect it due to
3158 // original value is different. And later we will need all original values
3159 // as anchors during finding the common Phi node.
3160 if (CanHandle)
3161 AddrModes.emplace_back(NewAddrMode);
3162 else
3163 AddrModes.clear();
3164
3165 return CanHandle;
3166 }
3167
3168 /// Combine the addressing modes we've collected into a single
3169 /// addressing mode.
3170 /// \return True iff we successfully combined them or we only had one so
3171 /// didn't need to combine them anyway.
3172 bool combineAddrModes() {
3173 // If we have no AddrModes then they can't be combined.
3174 if (AddrModes.size() == 0)
3175 return false;
3176
3177 // A single AddrMode can trivially be combined.
3178 if (AddrModes.size() == 1 || DifferentField == ExtAddrMode::NoField)
3179 return true;
3180
3181 // If the AddrModes we collected are all just equal to the value they are
3182 // derived from then combining them wouldn't do anything useful.
3183 if (AllAddrModesTrivial)
3184 return false;
3185
3186 if (!addrModeCombiningAllowed())
3187 return false;
3188
3189 // Build a map between <original value, basic block where we saw it> to
3190 // value of base register.
3191 // Bail out if there is no common type.
3192 FoldAddrToValueMapping Map;
3193 if (!initializeMap(Map))
3194 return false;
3195
3196 Value *CommonValue = findCommon(Map);
3197 if (CommonValue)
3198 AddrModes[0].SetCombinedField(DifferentField, CommonValue, AddrModes);
3199 return CommonValue != nullptr;
3200 }
3201
3202private:
3203 /// Initialize Map with anchor values. For address seen
3204 /// we set the value of different field saw in this address.
3205 /// At the same time we find a common type for different field we will
3206 /// use to create new Phi/Select nodes. Keep it in CommonType field.
3207 /// Return false if there is no common type found.
3208 bool initializeMap(FoldAddrToValueMapping &Map) {
3209 // Keep track of keys where the value is null. We will need to replace it
3210 // with constant null when we know the common type.
3211 SmallVector<Value *, 2> NullValue;
3212 Type *IntPtrTy = SQ.DL.getIntPtrType(AddrModes[0].OriginalValue->getType());
3213 for (auto &AM : AddrModes) {
3214 Value *DV = AM.GetFieldAsValue(DifferentField, IntPtrTy);
3215 if (DV) {
3216 auto *Type = DV->getType();
3217 if (CommonType && CommonType != Type)
3218 return false;
3219 CommonType = Type;
3220 Map[AM.OriginalValue] = DV;
3221 } else {
3222 NullValue.push_back(AM.OriginalValue);
3223 }
3224 }
3225 assert(CommonType && "At least one non-null value must be!")((CommonType && "At least one non-null value must be!"
) ? static_cast<void> (0) : __assert_fail ("CommonType && \"At least one non-null value must be!\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 3225, __PRETTY_FUNCTION__))
;
3226 for (auto *V : NullValue)
3227 Map[V] = Constant::getNullValue(CommonType);
3228 return true;
3229 }
3230
3231 /// We have mapping between value A and other value B where B was a field in
3232 /// addressing mode represented by A. Also we have an original value C
3233 /// representing an address we start with. Traversing from C through phi and
3234 /// selects we ended up with A's in a map. This utility function tries to find
3235 /// a value V which is a field in addressing mode C and traversing through phi
3236 /// nodes and selects we will end up in corresponded values B in a map.
3237 /// The utility will create a new Phi/Selects if needed.
3238 // The simple example looks as follows:
3239 // BB1:
3240 // p1 = b1 + 40
3241 // br cond BB2, BB3
3242 // BB2:
3243 // p2 = b2 + 40
3244 // br BB3
3245 // BB3:
3246 // p = phi [p1, BB1], [p2, BB2]
3247 // v = load p
3248 // Map is
3249 // p1 -> b1
3250 // p2 -> b2
3251 // Request is
3252 // p -> ?
3253 // The function tries to find or build phi [b1, BB1], [b2, BB2] in BB3.
3254 Value *findCommon(FoldAddrToValueMapping &Map) {
3255 // Tracks the simplification of newly created phi nodes. The reason we use
3256 // this mapping is because we will add new created Phi nodes in AddrToBase.
3257 // Simplification of Phi nodes is recursive, so some Phi node may
3258 // be simplified after we added it to AddrToBase. In reality this
3259 // simplification is possible only if original phi/selects were not
3260 // simplified yet.
3261 // Using this mapping we can find the current value in AddrToBase.
3262 SimplificationTracker ST(SQ);
3263
3264 // First step, DFS to create PHI nodes for all intermediate blocks.
3265 // Also fill traverse order for the second step.
3266 SmallVector<Value *, 32> TraverseOrder;
3267 InsertPlaceholders(Map, TraverseOrder, ST);
3268
3269 // Second Step, fill new nodes by merged values and simplify if possible.
3270 FillPlaceholders(Map, TraverseOrder, ST);
3271
3272 if (!AddrSinkNewSelects && ST.countNewSelectNodes() > 0) {
3273 ST.destroyNewNodes(CommonType);
3274 return nullptr;
3275 }
3276
3277 // Now we'd like to match New Phi nodes to existed ones.
3278 unsigned PhiNotMatchedCount = 0;
3279 if (!MatchPhiSet(ST, AddrSinkNewPhis, PhiNotMatchedCount)) {
3280 ST.destroyNewNodes(CommonType);
3281 return nullptr;
3282 }
3283
3284 auto *Result = ST.Get(Map.find(Original)->second);
3285 if (Result) {
3286 NumMemoryInstsPhiCreated += ST.countNewPhiNodes() + PhiNotMatchedCount;
3287 NumMemoryInstsSelectCreated += ST.countNewSelectNodes();
3288 }
3289 return Result;
3290 }
3291
3292 /// Try to match PHI node to Candidate.
3293 /// Matcher tracks the matched Phi nodes.
3294 bool MatchPhiNode(PHINode *PHI, PHINode *Candidate,
3295 SmallSetVector<PHIPair, 8> &Matcher,
3296 PhiNodeSet &PhiNodesToMatch) {
3297 SmallVector<PHIPair, 8> WorkList;
3298 Matcher.insert({ PHI, Candidate });
3299 SmallSet<PHINode *, 8> MatchedPHIs;
3300 MatchedPHIs.insert(PHI);
3301 WorkList.push_back({ PHI, Candidate });
3302 SmallSet<PHIPair, 8> Visited;
3303 while (!WorkList.empty()) {
3304 auto Item = WorkList.pop_back_val();
3305 if (!Visited.insert(Item).second)
3306 continue;
3307 // We iterate over all incoming values to Phi to compare them.
3308 // If values are different and both of them Phi and the first one is a
3309 // Phi we added (subject to match) and both of them is in the same basic
3310 // block then we can match our pair if values match. So we state that
3311 // these values match and add it to work list to verify that.
3312 for (auto B : Item.first->blocks()) {
3313 Value *FirstValue = Item.first->getIncomingValueForBlock(B);
3314 Value *SecondValue = Item.second->getIncomingValueForBlock(B);
3315 if (FirstValue == SecondValue)
3316 continue;
3317
3318 PHINode *FirstPhi = dyn_cast<PHINode>(FirstValue);
3319 PHINode *SecondPhi = dyn_cast<PHINode>(SecondValue);
3320
3321 // One of them is not Phi or
3322 // The first one is not Phi node from the set we'd like to match or
3323 // Phi nodes from different basic blocks then
3324 // we will not be able to match.
3325 if (!FirstPhi || !SecondPhi || !PhiNodesToMatch.count(FirstPhi) ||
3326 FirstPhi->getParent() != SecondPhi->getParent())
3327 return false;
3328
3329 // If we already matched them then continue.
3330 if (Matcher.count({ FirstPhi, SecondPhi }))
3331 continue;
3332 // So the values are different and does not match. So we need them to
3333 // match. (But we register no more than one match per PHI node, so that
3334 // we won't later try to replace them twice.)
3335 if (!MatchedPHIs.insert(FirstPhi).second)
3336 Matcher.insert({ FirstPhi, SecondPhi });
3337 // But me must check it.
3338 WorkList.push_back({ FirstPhi, SecondPhi });
3339 }
3340 }
3341 return true;
3342 }
3343
3344 /// For the given set of PHI nodes (in the SimplificationTracker) try
3345 /// to find their equivalents.
3346 /// Returns false if this matching fails and creation of new Phi is disabled.
3347 bool MatchPhiSet(SimplificationTracker &ST, bool AllowNewPhiNodes,
3348 unsigned &PhiNotMatchedCount) {
3349 // Matched and PhiNodesToMatch iterate their elements in a deterministic
3350 // order, so the replacements (ReplacePhi) are also done in a deterministic
3351 // order.
3352 SmallSetVector<PHIPair, 8> Matched;
3353 SmallPtrSet<PHINode *, 8> WillNotMatch;
3354 PhiNodeSet &PhiNodesToMatch = ST.newPhiNodes();
3355 while (PhiNodesToMatch.size()) {
3356 PHINode *PHI = *PhiNodesToMatch.begin();
3357
3358 // Add us, if no Phi nodes in the basic block we do not match.
3359 WillNotMatch.clear();
3360 WillNotMatch.insert(PHI);
3361
3362 // Traverse all Phis until we found equivalent or fail to do that.
3363 bool IsMatched = false;
3364 for (auto &P : PHI->getParent()->phis()) {
3365 if (&P == PHI)
3366 continue;
3367 if ((IsMatched = MatchPhiNode(PHI, &P, Matched, PhiNodesToMatch)))
3368 break;
3369 // If it does not match, collect all Phi nodes from matcher.
3370 // if we end up with no match, them all these Phi nodes will not match
3371 // later.
3372 for (auto M : Matched)
3373 WillNotMatch.insert(M.first);
3374 Matched.clear();
3375 }
3376 if (IsMatched) {
3377 // Replace all matched values and erase them.
3378 for (auto MV : Matched)
3379 ST.ReplacePhi(MV.first, MV.second);
3380 Matched.clear();
3381 continue;
3382 }
3383 // If we are not allowed to create new nodes then bail out.
3384 if (!AllowNewPhiNodes)
3385 return false;
3386 // Just remove all seen values in matcher. They will not match anything.
3387 PhiNotMatchedCount += WillNotMatch.size();
3388 for (auto *P : WillNotMatch)
3389 PhiNodesToMatch.erase(P);
3390 }
3391 return true;
3392 }
3393 /// Fill the placeholders with values from predecessors and simplify them.
3394 void FillPlaceholders(FoldAddrToValueMapping &Map,
3395 SmallVectorImpl<Value *> &TraverseOrder,
3396 SimplificationTracker &ST) {
3397 while (!TraverseOrder.empty()) {
3398 Value *Current = TraverseOrder.pop_back_val();
3399 assert(Map.find(Current) != Map.end() && "No node to fill!!!")((Map.find(Current) != Map.end() && "No node to fill!!!"
) ? static_cast<void> (0) : __assert_fail ("Map.find(Current) != Map.end() && \"No node to fill!!!\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 3399, __PRETTY_FUNCTION__))
;
3400 Value *V = Map[Current];
3401
3402 if (SelectInst *Select = dyn_cast<SelectInst>(V)) {
3403 // CurrentValue also must be Select.
3404 auto *CurrentSelect = cast<SelectInst>(Current);
3405 auto *TrueValue = CurrentSelect->getTrueValue();
3406 assert(Map.find(TrueValue) != Map.end() && "No True Value!")((Map.find(TrueValue) != Map.end() && "No True Value!"
) ? static_cast<void> (0) : __assert_fail ("Map.find(TrueValue) != Map.end() && \"No True Value!\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 3406, __PRETTY_FUNCTION__))
;
3407 Select->setTrueValue(ST.Get(Map[TrueValue]));
3408 auto *FalseValue = CurrentSelect->getFalseValue();
3409 assert(Map.find(FalseValue) != Map.end() && "No False Value!")((Map.find(FalseValue) != Map.end() && "No False Value!"
) ? static_cast<void> (0) : __assert_fail ("Map.find(FalseValue) != Map.end() && \"No False Value!\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 3409, __PRETTY_FUNCTION__))
;
3410 Select->setFalseValue(ST.Get(Map[FalseValue]));
3411 } else {
3412 // Must be a Phi node then.
3413 PHINode *PHI = cast<PHINode>(V);
3414 auto *CurrentPhi = dyn_cast<PHINode>(Current);
3415 // Fill the Phi node with values from predecessors.
3416 for (auto B : predecessors(PHI->getParent())) {
3417 Value *PV = CurrentPhi->getIncomingValueForBlock(B);
3418 assert(Map.find(PV) != Map.end() && "No predecessor Value!")((Map.find(PV) != Map.end() && "No predecessor Value!"
) ? static_cast<void> (0) : __assert_fail ("Map.find(PV) != Map.end() && \"No predecessor Value!\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 3418, __PRETTY_FUNCTION__))
;
3419 PHI->addIncoming(ST.Get(Map[PV]), B);
3420 }
3421 }
3422 Map[Current] = ST.Simplify(V);
3423 }
3424 }
3425
3426 /// Starting from original value recursively iterates over def-use chain up to
3427 /// known ending values represented in a map. For each traversed phi/select
3428 /// inserts a placeholder Phi or Select.
3429 /// Reports all new created Phi/Select nodes by adding them to set.
3430 /// Also reports and order in what values have been traversed.
3431 void InsertPlaceholders(FoldAddrToValueMapping &Map,
3432 SmallVectorImpl<Value *> &TraverseOrder,
3433 SimplificationTracker &ST) {
3434 SmallVector<Value *, 32> Worklist;
3435 assert((isa<PHINode>(Original) || isa<SelectInst>(Original)) &&(((isa<PHINode>(Original) || isa<SelectInst>(Original
)) && "Address must be a Phi or Select node") ? static_cast
<void> (0) : __assert_fail ("(isa<PHINode>(Original) || isa<SelectInst>(Original)) && \"Address must be a Phi or Select node\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 3436, __PRETTY_FUNCTION__))
3436 "Address must be a Phi or Select node")(((isa<PHINode>(Original) || isa<SelectInst>(Original
)) && "Address must be a Phi or Select node") ? static_cast
<void> (0) : __assert_fail ("(isa<PHINode>(Original) || isa<SelectInst>(Original)) && \"Address must be a Phi or Select node\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 3436, __PRETTY_FUNCTION__))
;
3437 auto *Dummy = UndefValue::get(CommonType);
3438 Worklist.push_back(Original);
3439 while (!Worklist.empty()) {
3440 Value *Current = Worklist.pop_back_val();
3441 // if it is already visited or it is an ending value then skip it.
3442 if (Map.find(Current) != Map.end())
3443 continue;
3444 TraverseOrder.push_back(Current);
3445
3446 // CurrentValue must be a Phi node or select. All others must be covered
3447 // by anchors.
3448 if (SelectInst *CurrentSelect = dyn_cast<SelectInst>(Current)) {
3449 // Is it OK to get metadata from OrigSelect?!
3450 // Create a Select placeholder with dummy value.
3451 SelectInst *Select = SelectInst::Create(
3452 CurrentSelect->getCondition(), Dummy, Dummy,
3453 CurrentSelect->getName(), CurrentSelect, CurrentSelect);
3454 Map[Current] = Select;
3455 ST.insertNewSelect(Select);
3456 // We are interested in True and False values.
3457 Worklist.push_back(CurrentSelect->getTrueValue());
3458 Worklist.push_back(CurrentSelect->getFalseValue());
3459 } else {
3460 // It must be a Phi node then.
3461 PHINode *CurrentPhi = cast<PHINode>(Current);
3462 unsigned PredCount = CurrentPhi->getNumIncomingValues();
3463 PHINode *PHI =
3464 PHINode::Create(CommonType, PredCount, "sunk_phi", CurrentPhi);
3465 Map[Current] = PHI;
3466 ST.insertNewPhi(PHI);
3467 for (Value *P : CurrentPhi->incoming_values())
3468 Worklist.push_back(P);
3469 }
3470 }
3471 }
3472
3473 bool addrModeCombiningAllowed() {
3474 if (DisableComplexAddrModes)
3475 return false;
3476 switch (DifferentField) {
3477 default:
3478 return false;
3479 case ExtAddrMode::BaseRegField:
3480 return AddrSinkCombineBaseReg;
3481 case ExtAddrMode::BaseGVField:
3482 return AddrSinkCombineBaseGV;
3483 case ExtAddrMode::BaseOffsField:
3484 return AddrSinkCombineBaseOffs;
3485 case ExtAddrMode::ScaledRegField:
3486 return AddrSinkCombineScaledReg;
3487 }
3488 }
3489};
3490} // end anonymous namespace
3491
3492/// Try adding ScaleReg*Scale to the current addressing mode.
3493/// Return true and update AddrMode if this addr mode is legal for the target,
3494/// false if not.
3495bool AddressingModeMatcher::matchScaledValue(Value *ScaleReg, int64_t Scale,
3496 unsigned Depth) {
3497 // If Scale is 1, then this is the same as adding ScaleReg to the addressing
3498 // mode. Just process that directly.
3499 if (Scale == 1)
3500 return matchAddr(ScaleReg, Depth);
3501
3502 // If the scale is 0, it takes nothing to add this.
3503 if (Scale == 0)
3504 return true;
3505
3506 // If we already have a scale of this value, we can add to it, otherwise, we
3507 // need an available scale field.
3508 if (AddrMode.Scale != 0 && AddrMode.ScaledReg != ScaleReg)
3509 return false;
3510
3511 ExtAddrMode TestAddrMode = AddrMode;
3512
3513 // Add scale to turn X*4+X*3 -> X*7. This could also do things like
3514 // [A+B + A*7] -> [B+A*8].
3515 TestAddrMode.Scale += Scale;
3516 TestAddrMode.ScaledReg = ScaleReg;
3517
3518 // If the new address isn't legal, bail out.
3519 if (!TLI.isLegalAddressingMode(DL, TestAddrMode, AccessTy, AddrSpace))
3520 return false;
3521
3522 // It was legal, so commit it.
3523 AddrMode = TestAddrMode;
3524
3525 // Okay, we decided that we can add ScaleReg+Scale to AddrMode. Check now
3526 // to see if ScaleReg is actually X+C. If so, we can turn this into adding
3527 // X*Scale + C*Scale to addr mode.
3528 ConstantInt *CI = nullptr; Value *AddLHS = nullptr;
3529 if (isa<Instruction>(ScaleReg) && // not a constant expr.
3530 match(ScaleReg, m_Add(m_Value(AddLHS), m_ConstantInt(CI)))) {
3531 TestAddrMode.InBounds = false;
3532 TestAddrMode.ScaledReg = AddLHS;
3533 TestAddrMode.BaseOffs += CI->getSExtValue()*TestAddrMode.Scale;
3534
3535 // If this addressing mode is legal, commit it and remember that we folded
3536 // this instruction.
3537 if (TLI.isLegalAddressingMode(DL, TestAddrMode, AccessTy, AddrSpace)) {
3538 AddrModeInsts.push_back(cast<Instruction>(ScaleReg));
3539 AddrMode = TestAddrMode;
3540 return true;
3541 }
3542 }
3543
3544 // Otherwise, not (x+c)*scale, just return what we have.
3545 return true;
3546}
3547
3548/// This is a little filter, which returns true if an addressing computation
3549/// involving I might be folded into a load/store accessing it.
3550/// This doesn't need to be perfect, but needs to accept at least
3551/// the set of instructions that MatchOperationAddr can.
3552static bool MightBeFoldableInst(Instruction *I) {
3553 switch (I->getOpcode()) {
3554 case Instruction::BitCast:
3555 case Instruction::AddrSpaceCast:
3556 // Don't touch identity bitcasts.
3557 if (I->getType() == I->getOperand(0)->getType())
3558 return false;
3559 return I->getType()->isIntOrPtrTy();
3560 case Instruction::PtrToInt:
3561 // PtrToInt is always a noop, as we know that the int type is pointer sized.
3562 return true;
3563 case Instruction::IntToPtr:
3564 // We know the input is intptr_t, so this is foldable.
3565 return true;
3566 case Instruction::Add:
3567 return true;
3568 case Instruction::Mul:
3569 case Instruction::Shl:
3570 // Can only handle X*C and X << C.
3571 return isa<ConstantInt>(I->getOperand(1));
3572 case Instruction::GetElementPtr:
3573 return true;
3574 default:
3575 return false;
3576 }
3577}
3578
3579/// Check whether or not \p Val is a legal instruction for \p TLI.
3580/// \note \p Val is assumed to be the product of some type promotion.
3581/// Therefore if \p Val has an undefined state in \p TLI, this is assumed
3582/// to be legal, as the non-promoted value would have had the same state.
3583static bool isPromotedInstructionLegal(const TargetLowering &TLI,
3584 const DataLayout &DL, Value *Val) {
3585 Instruction *PromotedInst = dyn_cast<Instruction>(Val);
3586 if (!PromotedInst)
3587 return false;
3588 int ISDOpcode = TLI.InstructionOpcodeToISD(PromotedInst->getOpcode());
3589 // If the ISDOpcode is undefined, it was undefined before the promotion.
3590 if (!ISDOpcode)
3591 return true;
3592 // Otherwise, check if the promoted instruction is legal or not.
3593 return TLI.isOperationLegalOrCustom(
3594 ISDOpcode, TLI.getValueType(DL, PromotedInst->getType()));
3595}
3596
3597namespace {
3598
3599/// Hepler class to perform type promotion.
3600class TypePromotionHelper {
3601 /// Utility function to add a promoted instruction \p ExtOpnd to
3602 /// \p PromotedInsts and record the type of extension we have seen.
3603 static void addPromotedInst(InstrToOrigTy &PromotedInsts,
3604 Instruction *ExtOpnd,
3605 bool IsSExt) {
3606 ExtType ExtTy = IsSExt ? SignExtension : ZeroExtension;
3607 InstrToOrigTy::iterator It = PromotedInsts.find(ExtOpnd);
3608 if (It != PromotedInsts.end()) {
3609 // If the new extension is same as original, the information in
3610 // PromotedInsts[ExtOpnd] is still correct.
3611 if (It->second.getInt() == ExtTy)
3612 return;
3613
3614 // Now the new extension is different from old extension, we make
3615 // the type information invalid by setting extension type to
3616 // BothExtension.
3617 ExtTy = BothExtension;
3618 }
3619 PromotedInsts[ExtOpnd] = TypeIsSExt(ExtOpnd->getType(), ExtTy);
3620 }
3621
3622 /// Utility function to query the original type of instruction \p Opnd
3623 /// with a matched extension type. If the extension doesn't match, we
3624 /// cannot use the information we had on the original type.
3625 /// BothExtension doesn't match any extension type.
3626 static const Type *getOrigType(const InstrToOrigTy &PromotedInsts,
3627 Instruction *Opnd,
3628 bool IsSExt) {
3629 ExtType ExtTy = IsSExt ? SignExtension : ZeroExtension;
3630 InstrToOrigTy::const_iterator It = PromotedInsts.find(Opnd);
3631 if (It != PromotedInsts.end() && It->second.getInt() == ExtTy)
3632 return It->second.getPointer();
3633 return nullptr;
3634 }
3635
3636 /// Utility function to check whether or not a sign or zero extension
3637 /// of \p Inst with \p ConsideredExtType can be moved through \p Inst by
3638 /// either using the operands of \p Inst or promoting \p Inst.
3639 /// The type of the extension is defined by \p IsSExt.
3640 /// In other words, check if:
3641 /// ext (Ty Inst opnd1 opnd2 ... opndN) to ConsideredExtType.
3642 /// #1 Promotion applies:
3643 /// ConsideredExtType Inst (ext opnd1 to ConsideredExtType, ...).
3644 /// #2 Operand reuses:
3645 /// ext opnd1 to ConsideredExtType.
3646 /// \p PromotedInsts maps the instructions to their type before promotion.
3647 static bool canGetThrough(const Instruction *Inst, Type *ConsideredExtType,
3648 const InstrToOrigTy &PromotedInsts, bool IsSExt);
3649
3650 /// Utility function to determine if \p OpIdx should be promoted when
3651 /// promoting \p Inst.
3652 static bool shouldExtOperand(const Instruction *Inst, int OpIdx) {
3653 return !(isa<SelectInst>(Inst) && OpIdx == 0);
3654 }
3655
3656 /// Utility function to promote the operand of \p Ext when this
3657 /// operand is a promotable trunc or sext or zext.
3658 /// \p PromotedInsts maps the instructions to their type before promotion.
3659 /// \p CreatedInstsCost[out] contains the cost of all instructions
3660 /// created to promote the operand of Ext.
3661 /// Newly added extensions are inserted in \p Exts.
3662 /// Newly added truncates are inserted in \p Truncs.
3663 /// Should never be called directly.
3664 /// \return The promoted value which is used instead of Ext.
3665 static Value *promoteOperandForTruncAndAnyExt(
3666 Instruction *Ext, TypePromotionTransaction &TPT,
3667 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3668 SmallVectorImpl<Instruction *> *Exts,
3669 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI);
3670
3671 /// Utility function to promote the operand of \p Ext when this
3672 /// operand is promotable and is not a supported trunc or sext.
3673 /// \p PromotedInsts maps the instructions to their type before promotion.
3674 /// \p CreatedInstsCost[out] contains the cost of all the instructions
3675 /// created to promote the operand of Ext.
3676 /// Newly added extensions are inserted in \p Exts.
3677 /// Newly added truncates are inserted in \p Truncs.
3678 /// Should never be called directly.
3679 /// \return The promoted value which is used instead of Ext.
3680 static Value *promoteOperandForOther(Instruction *Ext,
3681 TypePromotionTransaction &TPT,
3682 InstrToOrigTy &PromotedInsts,
3683 unsigned &CreatedInstsCost,
3684 SmallVectorImpl<Instruction *> *Exts,
3685 SmallVectorImpl<Instruction *> *Truncs,
3686 const TargetLowering &TLI, bool IsSExt);
3687
3688 /// \see promoteOperandForOther.
3689 static Value *signExtendOperandForOther(
3690 Instruction *Ext, TypePromotionTransaction &TPT,
3691 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3692 SmallVectorImpl<Instruction *> *Exts,
3693 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
3694 return promoteOperandForOther(Ext, TPT, PromotedInsts, CreatedInstsCost,
3695 Exts, Truncs, TLI, true);
3696 }
3697
3698 /// \see promoteOperandForOther.
3699 static Value *zeroExtendOperandForOther(
3700 Instruction *Ext, TypePromotionTransaction &TPT,
3701 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3702 SmallVectorImpl<Instruction *> *Exts,
3703 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
3704 return promoteOperandForOther(Ext, TPT, PromotedInsts, CreatedInstsCost,
3705 Exts, Truncs, TLI, false);
3706 }
3707
3708public:
3709 /// Type for the utility function that promotes the operand of Ext.
3710 using Action = Value *(*)(Instruction *Ext, TypePromotionTransaction &TPT,
3711 InstrToOrigTy &PromotedInsts,
3712 unsigned &CreatedInstsCost,
3713 SmallVectorImpl<Instruction *> *Exts,
3714 SmallVectorImpl<Instruction *> *Truncs,
3715 const TargetLowering &TLI);
3716
3717 /// Given a sign/zero extend instruction \p Ext, return the appropriate
3718 /// action to promote the operand of \p Ext instead of using Ext.
3719 /// \return NULL if no promotable action is possible with the current
3720 /// sign extension.
3721 /// \p InsertedInsts keeps track of all the instructions inserted by the
3722 /// other CodeGenPrepare optimizations. This information is important
3723 /// because we do not want to promote these instructions as CodeGenPrepare
3724 /// will reinsert them later. Thus creating an infinite loop: create/remove.
3725 /// \p PromotedInsts maps the instructions to their type before promotion.
3726 static Action getAction(Instruction *Ext, const SetOfInstrs &InsertedInsts,
3727 const TargetLowering &TLI,
3728 const InstrToOrigTy &PromotedInsts);
3729};
3730
3731} // end anonymous namespace
3732
3733bool TypePromotionHelper::canGetThrough(const Instruction *Inst,
3734 Type *ConsideredExtType,
3735 const InstrToOrigTy &PromotedInsts,
3736 bool IsSExt) {
3737 // The promotion helper does not know how to deal with vector types yet.
3738 // To be able to fix that, we would need to fix the places where we
3739 // statically extend, e.g., constants and such.
3740 if (Inst->getType()->isVectorTy())
3741 return false;
3742
3743 // We can always get through zext.
3744 if (isa<ZExtInst>(Inst))
3745 return true;
3746
3747 // sext(sext) is ok too.
3748 if (IsSExt && isa<SExtInst>(Inst))
3749 return true;
3750
3751 // We can get through binary operator, if it is legal. In other words, the
3752 // binary operator must have a nuw or nsw flag.
3753 const BinaryOperator *BinOp = dyn_cast<BinaryOperator>(Inst);
3754 if (BinOp && isa<OverflowingBinaryOperator>(BinOp) &&
3755 ((!IsSExt && BinOp->hasNoUnsignedWrap()) ||
3756 (IsSExt && BinOp->hasNoSignedWrap())))
3757 return true;
3758
3759 // ext(and(opnd, cst)) --> and(ext(opnd), ext(cst))
3760 if ((Inst->getOpcode() == Instruction::And ||
3761 Inst->getOpcode() == Instruction::Or))
3762 return true;
3763
3764 // ext(xor(opnd, cst)) --> xor(ext(opnd), ext(cst))
3765 if (Inst->getOpcode() == Instruction::Xor) {
3766 const ConstantInt *Cst = dyn_cast<ConstantInt>(Inst->getOperand(1));
3767 // Make sure it is not a NOT.
3768 if (Cst && !Cst->getValue().isAllOnesValue())
3769 return true;
3770 }
3771
3772 // zext(shrl(opnd, cst)) --> shrl(zext(opnd), zext(cst))
3773 // It may change a poisoned value into a regular value, like
3774 // zext i32 (shrl i8 %val, 12) --> shrl i32 (zext i8 %val), 12
3775 // poisoned value regular value
3776 // It should be OK since undef covers valid value.
3777 if (Inst->getOpcode() == Instruction::LShr && !IsSExt)
3778 return true;
3779
3780 // and(ext(shl(opnd, cst)), cst) --> and(shl(ext(opnd), ext(cst)), cst)
3781 // It may change a poisoned value into a regular value, like
3782 // zext i32 (shl i8 %val, 12) --> shl i32 (zext i8 %val), 12
3783 // poisoned value regular value
3784 // It should be OK since undef covers valid value.
3785 if (Inst->getOpcode() == Instruction::Shl && Inst->hasOneUse()) {
3786 const Instruction *ExtInst =
3787 dyn_cast<const Instruction>(*Inst->user_begin());
3788 if (ExtInst->hasOneUse()) {
3789 const Instruction *AndInst =
3790 dyn_cast<const Instruction>(*ExtInst->user_begin());
3791 if (AndInst && AndInst->getOpcode() == Instruction::And) {
3792 const ConstantInt *Cst = dyn_cast<ConstantInt>(AndInst->getOperand(1));
3793 if (Cst &&
3794 Cst->getValue().isIntN(Inst->getType()->getIntegerBitWidth()))
3795 return true;
3796 }
3797 }
3798 }
3799
3800 // Check if we can do the following simplification.
3801 // ext(trunc(opnd)) --> ext(opnd)
3802 if (!isa<TruncInst>(Inst))
3803 return false;
3804
3805 Value *OpndVal = Inst->getOperand(0);
3806 // Check if we can use this operand in the extension.
3807 // If the type is larger than the result type of the extension, we cannot.
3808 if (!OpndVal->getType()->isIntegerTy() ||
3809 OpndVal->getType()->getIntegerBitWidth() >
3810 ConsideredExtType->getIntegerBitWidth())
3811 return false;
3812
3813 // If the operand of the truncate is not an instruction, we will not have
3814 // any information on the dropped bits.
3815 // (Actually we could for constant but it is not worth the extra logic).
3816 Instruction *Opnd = dyn_cast<Instruction>(OpndVal);
3817 if (!Opnd)
3818 return false;
3819
3820 // Check if the source of the type is narrow enough.
3821 // I.e., check that trunc just drops extended bits of the same kind of
3822 // the extension.
3823 // #1 get the type of the operand and check the kind of the extended bits.
3824 const Type *OpndType = getOrigType(PromotedInsts, Opnd, IsSExt);
3825 if (OpndType)
3826 ;
3827 else if ((IsSExt && isa<SExtInst>(Opnd)) || (!IsSExt && isa<ZExtInst>(Opnd)))
3828 OpndType = Opnd->getOperand(0)->getType();
3829 else
3830 return false;
3831
3832 // #2 check that the truncate just drops extended bits.
3833 return Inst->getType()->getIntegerBitWidth() >=
3834 OpndType->getIntegerBitWidth();
3835}
3836
3837TypePromotionHelper::Action TypePromotionHelper::getAction(
3838 Instruction *Ext, const SetOfInstrs &InsertedInsts,
3839 const TargetLowering &TLI, const InstrToOrigTy &PromotedInsts) {
3840 assert((isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) &&(((isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) &&
"Unexpected instruction type") ? static_cast<void> (0)
: __assert_fail ("(isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) && \"Unexpected instruction type\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 3841, __PRETTY_FUNCTION__))
3841 "Unexpected instruction type")(((isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) &&
"Unexpected instruction type") ? static_cast<void> (0)
: __assert_fail ("(isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) && \"Unexpected instruction type\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 3841, __PRETTY_FUNCTION__))
;
3842 Instruction *ExtOpnd = dyn_cast<Instruction>(Ext->getOperand(0));
3843 Type *ExtTy = Ext->getType();
3844 bool IsSExt = isa<SExtInst>(Ext);
3845 // If the operand of the extension is not an instruction, we cannot
3846 // get through.
3847 // If it, check we can get through.
3848 if (!ExtOpnd || !canGetThrough(ExtOpnd, ExtTy, PromotedInsts, IsSExt))
3849 return nullptr;
3850
3851 // Do not promote if the operand has been added by codegenprepare.
3852 // Otherwise, it means we are undoing an optimization that is likely to be
3853 // redone, thus causing potential infinite loop.
3854 if (isa<TruncInst>(ExtOpnd) && InsertedInsts.count(ExtOpnd))
3855 return nullptr;
3856
3857 // SExt or Trunc instructions.
3858 // Return the related handler.
3859 if (isa<SExtInst>(ExtOpnd) || isa<TruncInst>(ExtOpnd) ||
3860 isa<ZExtInst>(ExtOpnd))
3861 return promoteOperandForTruncAndAnyExt;
3862
3863 // Regular instruction.
3864 // Abort early if we will have to insert non-free instructions.
3865 if (!ExtOpnd->hasOneUse() && !TLI.isTruncateFree(ExtTy, ExtOpnd->getType()))
3866 return nullptr;
3867 return IsSExt ? signExtendOperandForOther : zeroExtendOperandForOther;
3868}
3869
3870Value *TypePromotionHelper::promoteOperandForTruncAndAnyExt(
3871 Instruction *SExt, TypePromotionTransaction &TPT,
3872 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3873 SmallVectorImpl<Instruction *> *Exts,
3874 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
3875 // By construction, the operand of SExt is an instruction. Otherwise we cannot
3876 // get through it and this method should not be called.
3877 Instruction *SExtOpnd = cast<Instruction>(SExt->getOperand(0));
3878 Value *ExtVal = SExt;
3879 bool HasMergedNonFreeExt = false;
3880 if (isa<ZExtInst>(SExtOpnd)) {
3881 // Replace s|zext(zext(opnd))
3882 // => zext(opnd).
3883 HasMergedNonFreeExt = !TLI.isExtFree(SExtOpnd);
3884 Value *ZExt =
3885 TPT.createZExt(SExt, SExtOpnd->getOperand(0), SExt->getType());
3886 TPT.replaceAllUsesWith(SExt, ZExt);
3887 TPT.eraseInstruction(SExt);
3888 ExtVal = ZExt;
3889 } else {
3890 // Replace z|sext(trunc(opnd)) or sext(sext(opnd))
3891 // => z|sext(opnd).
3892 TPT.setOperand(SExt, 0, SExtOpnd->getOperand(0));
3893 }
3894 CreatedInstsCost = 0;
3895
3896 // Remove dead code.
3897 if (SExtOpnd->use_empty())
3898 TPT.eraseInstruction(SExtOpnd);
3899
3900 // Check if the extension is still needed.
3901 Instruction *ExtInst = dyn_cast<Instruction>(ExtVal);
3902 if (!ExtInst || ExtInst->getType() != ExtInst->getOperand(0)->getType()) {
3903 if (ExtInst) {
3904 if (Exts)
3905 Exts->push_back(ExtInst);
3906 CreatedInstsCost = !TLI.isExtFree(ExtInst) && !HasMergedNonFreeExt;
3907 }
3908 return ExtVal;
3909 }
3910
3911 // At this point we have: ext ty opnd to ty.
3912 // Reassign the uses of ExtInst to the opnd and remove ExtInst.
3913 Value *NextVal = ExtInst->getOperand(0);
3914 TPT.eraseInstruction(ExtInst, NextVal);
3915 return NextVal;
3916}
3917
3918Value *TypePromotionHelper::promoteOperandForOther(
3919 Instruction *Ext, TypePromotionTransaction &TPT,
3920 InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
3921 SmallVectorImpl<Instruction *> *Exts,
3922 SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI,
3923 bool IsSExt) {
3924 // By construction, the operand of Ext is an instruction. Otherwise we cannot
3925 // get through it and this method should not be called.
3926 Instruction *ExtOpnd = cast<Instruction>(Ext->getOperand(0));
3927 CreatedInstsCost = 0;
3928 if (!ExtOpnd->hasOneUse()) {
3929 // ExtOpnd will be promoted.
3930 // All its uses, but Ext, will need to use a truncated value of the
3931 // promoted version.
3932 // Create the truncate now.
3933 Value *Trunc = TPT.createTrunc(Ext, ExtOpnd->getType());
3934 if (Instruction *ITrunc = dyn_cast<Instruction>(Trunc)) {
3935 // Insert it just after the definition.
3936 ITrunc->moveAfter(ExtOpnd);
3937 if (Truncs)
3938 Truncs->push_back(ITrunc);
3939 }
3940
3941 TPT.replaceAllUsesWith(ExtOpnd, Trunc);
3942 // Restore the operand of Ext (which has been replaced by the previous call
3943 // to replaceAllUsesWith) to avoid creating a cycle trunc <-> sext.
3944 TPT.setOperand(Ext, 0, ExtOpnd);
3945 }
3946
3947 // Get through the Instruction:
3948 // 1. Update its type.
3949 // 2. Replace the uses of Ext by Inst.
3950 // 3. Extend each operand that needs to be extended.
3951
3952 // Remember the original type of the instruction before promotion.
3953 // This is useful to know that the high bits are sign extended bits.
3954 addPromotedInst(PromotedInsts, ExtOpnd, IsSExt);
3955 // Step #1.
3956 TPT.mutateType(ExtOpnd, Ext->getType());
3957 // Step #2.
3958 TPT.replaceAllUsesWith(Ext, ExtOpnd);
3959 // Step #3.
3960 Instruction *ExtForOpnd = Ext;
3961
3962 LLVM_DEBUG(dbgs() << "Propagate Ext to operands\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Propagate Ext to operands\n"
; } } while (false)
;
3963 for (int OpIdx = 0, EndOpIdx = ExtOpnd->getNumOperands(); OpIdx != EndOpIdx;
3964 ++OpIdx) {
3965 LLVM_DEBUG(dbgs() << "Operand:\n" << *(ExtOpnd->getOperand(OpIdx)) << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Operand:\n" << *
(ExtOpnd->getOperand(OpIdx)) << '\n'; } } while (false
)
;
3966 if (ExtOpnd->getOperand(OpIdx)->getType() == Ext->getType() ||
3967 !shouldExtOperand(ExtOpnd, OpIdx)) {
3968 LLVM_DEBUG(dbgs() << "No need to propagate\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "No need to propagate\n"
; } } while (false)
;
3969 continue;
3970 }
3971 // Check if we can statically extend the operand.
3972 Value *Opnd = ExtOpnd->getOperand(OpIdx);
3973 if (const ConstantInt *Cst = dyn_cast<ConstantInt>(Opnd)) {
3974 LLVM_DEBUG(dbgs() << "Statically extend\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Statically extend\n"; }
} while (false)
;
3975 unsigned BitWidth = Ext->getType()->getIntegerBitWidth();
3976 APInt CstVal = IsSExt ? Cst->getValue().sext(BitWidth)
3977 : Cst->getValue().zext(BitWidth);
3978 TPT.setOperand(ExtOpnd, OpIdx, ConstantInt::get(Ext->getType(), CstVal));
3979 continue;
3980 }
3981 // UndefValue are typed, so we have to statically sign extend them.
3982 if (isa<UndefValue>(Opnd)) {
3983 LLVM_DEBUG(dbgs() << "Statically extend\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Statically extend\n"; }
} while (false)
;
3984 TPT.setOperand(ExtOpnd, OpIdx, UndefValue::get(Ext->getType()));
3985 continue;
3986 }
3987
3988 // Otherwise we have to explicitly sign extend the operand.
3989 // Check if Ext was reused to extend an operand.
3990 if (!ExtForOpnd) {
3991 // If yes, create a new one.
3992 LLVM_DEBUG(dbgs() << "More operands to ext\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "More operands to ext\n"
; } } while (false)
;
3993 Value *ValForExtOpnd = IsSExt ? TPT.createSExt(Ext, Opnd, Ext->getType())
3994 : TPT.createZExt(Ext, Opnd, Ext->getType());
3995 if (!isa<Instruction>(ValForExtOpnd)) {
3996 TPT.setOperand(ExtOpnd, OpIdx, ValForExtOpnd);
3997 continue;
3998 }
3999 ExtForOpnd = cast<Instruction>(ValForExtOpnd);
4000 }
4001 if (Exts)
4002 Exts->push_back(ExtForOpnd);
4003 TPT.setOperand(ExtForOpnd, 0, Opnd);
4004
4005 // Move the sign extension before the insertion point.
4006 TPT.moveBefore(ExtForOpnd, ExtOpnd);
4007 TPT.setOperand(ExtOpnd, OpIdx, ExtForOpnd);
4008 CreatedInstsCost += !TLI.isExtFree(ExtForOpnd);
4009 // If more sext are required, new instructions will have to be created.
4010 ExtForOpnd = nullptr;
4011 }
4012 if (ExtForOpnd == Ext) {
4013 LLVM_DEBUG(dbgs() << "Extension is useless now\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Extension is useless now\n"
; } } while (false)
;
4014 TPT.eraseInstruction(Ext);
4015 }
4016 return ExtOpnd;
4017}
4018
4019/// Check whether or not promoting an instruction to a wider type is profitable.
4020/// \p NewCost gives the cost of extension instructions created by the
4021/// promotion.
4022/// \p OldCost gives the cost of extension instructions before the promotion
4023/// plus the number of instructions that have been
4024/// matched in the addressing mode the promotion.
4025/// \p PromotedOperand is the value that has been promoted.
4026/// \return True if the promotion is profitable, false otherwise.
4027bool AddressingModeMatcher::isPromotionProfitable(
4028 unsigned NewCost, unsigned OldCost, Value *PromotedOperand) const {
4029 LLVM_DEBUG(dbgs() << "OldCost: " << OldCost << "\tNewCost: " << NewCostdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "OldCost: " << OldCost
<< "\tNewCost: " << NewCost << '\n'; } } while
(false)
4030 << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "OldCost: " << OldCost
<< "\tNewCost: " << NewCost << '\n'; } } while
(false)
;
4031 // The cost of the new extensions is greater than the cost of the
4032 // old extension plus what we folded.
4033 // This is not profitable.
4034 if (NewCost > OldCost)
4035 return false;
4036 if (NewCost < OldCost)
4037 return true;
4038 // The promotion is neutral but it may help folding the sign extension in
4039 // loads for instance.
4040 // Check that we did not create an illegal instruction.
4041 return isPromotedInstructionLegal(TLI, DL, PromotedOperand);
4042}
4043
4044/// Given an instruction or constant expr, see if we can fold the operation
4045/// into the addressing mode. If so, update the addressing mode and return
4046/// true, otherwise return false without modifying AddrMode.
4047/// If \p MovedAway is not NULL, it contains the information of whether or
4048/// not AddrInst has to be folded into the addressing mode on success.
4049/// If \p MovedAway == true, \p AddrInst will not be part of the addressing
4050/// because it has been moved away.
4051/// Thus AddrInst must not be added in the matched instructions.
4052/// This state can happen when AddrInst is a sext, since it may be moved away.
4053/// Therefore, AddrInst may not be valid when MovedAway is true and it must
4054/// not be referenced anymore.
4055bool AddressingModeMatcher::matchOperationAddr(User *AddrInst, unsigned Opcode,
4056 unsigned Depth,
4057 bool *MovedAway) {
4058 // Avoid exponential behavior on extremely deep expression trees.
4059 if (Depth >= 5) return false;
4060
4061 // By default, all matched instructions stay in place.
4062 if (MovedAway)
4063 *MovedAway = false;
4064
4065 switch (Opcode) {
4066 case Instruction::PtrToInt:
4067 // PtrToInt is always a noop, as we know that the int type is pointer sized.
4068 return matchAddr(AddrInst->getOperand(0), Depth);
4069 case Instruction::IntToPtr: {
4070 auto AS = AddrInst->getType()->getPointerAddressSpace();
4071 auto PtrTy = MVT::getIntegerVT(DL.getPointerSizeInBits(AS));
4072 // This inttoptr is a no-op if the integer type is pointer sized.
4073 if (TLI.getValueType(DL, AddrInst->getOperand(0)->getType()) == PtrTy)
4074 return matchAddr(AddrInst->getOperand(0), Depth);
4075 return false;
4076 }
4077 case Instruction::BitCast:
4078 // BitCast is always a noop, and we can handle it as long as it is
4079 // int->int or pointer->pointer (we don't want int<->fp or something).
4080 if (AddrInst->getOperand(0)->getType()->isIntOrPtrTy() &&
4081 // Don't touch identity bitcasts. These were probably put here by LSR,
4082 // and we don't want to mess around with them. Assume it knows what it
4083 // is doing.
4084 AddrInst->getOperand(0)->getType() != AddrInst->getType())
4085 return matchAddr(AddrInst->getOperand(0), Depth);
4086 return false;
4087 case Instruction::AddrSpaceCast: {
4088 unsigned SrcAS
4089 = AddrInst->getOperand(0)->getType()->getPointerAddressSpace();
4090 unsigned DestAS = AddrInst->getType()->getPointerAddressSpace();
4091 if (TLI.isNoopAddrSpaceCast(SrcAS, DestAS))
4092 return matchAddr(AddrInst->getOperand(0), Depth);
4093 return false;
4094 }
4095 case Instruction::Add: {
4096 // Check to see if we can merge in the RHS then the LHS. If so, we win.
4097 ExtAddrMode BackupAddrMode = AddrMode;
4098 unsigned OldSize = AddrModeInsts.size();
4099 // Start a transaction at this point.
4100 // The LHS may match but not the RHS.
4101 // Therefore, we need a higher level restoration point to undo partially
4102 // matched operation.
4103 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4104 TPT.getRestorationPoint();
4105
4106 AddrMode.InBounds = false;
4107 if (matchAddr(AddrInst->getOperand(1), Depth+1) &&
4108 matchAddr(AddrInst->getOperand(0), Depth+1))
4109 return true;
4110
4111 // Restore the old addr mode info.
4112 AddrMode = BackupAddrMode;
4113 AddrModeInsts.resize(OldSize);
4114 TPT.rollback(LastKnownGood);
4115
4116 // Otherwise this was over-aggressive. Try merging in the LHS then the RHS.
4117 if (matchAddr(AddrInst->getOperand(0), Depth+1) &&
4118 matchAddr(AddrInst->getOperand(1), Depth+1))
4119 return true;
4120
4121 // Otherwise we definitely can't merge the ADD in.
4122 AddrMode = BackupAddrMode;
4123 AddrModeInsts.resize(OldSize);
4124 TPT.rollback(LastKnownGood);
4125 break;
4126 }
4127 //case Instruction::Or:
4128 // TODO: We can handle "Or Val, Imm" iff this OR is equivalent to an ADD.
4129 //break;
4130 case Instruction::Mul:
4131 case Instruction::Shl: {
4132 // Can only handle X*C and X << C.
4133 AddrMode.InBounds = false;
4134 ConstantInt *RHS = dyn_cast<ConstantInt>(AddrInst->getOperand(1));
4135 if (!RHS || RHS->getBitWidth() > 64)
4136 return false;
4137 int64_t Scale = RHS->getSExtValue();
4138 if (Opcode == Instruction::Shl)
4139 Scale = 1LL << Scale;
4140
4141 return matchScaledValue(AddrInst->getOperand(0), Scale, Depth);
4142 }
4143 case Instruction::GetElementPtr: {
4144 // Scan the GEP. We check it if it contains constant offsets and at most
4145 // one variable offset.
4146 int VariableOperand = -1;
4147 unsigned VariableScale = 0;
4148
4149 int64_t ConstantOffset = 0;
4150 gep_type_iterator GTI = gep_type_begin(AddrInst);
4151 for (unsigned i = 1, e = AddrInst->getNumOperands(); i != e; ++i, ++GTI) {
4152 if (StructType *STy = GTI.getStructTypeOrNull()) {
4153 const StructLayout *SL = DL.getStructLayout(STy);
4154 unsigned Idx =
4155 cast<ConstantInt>(AddrInst->getOperand(i))->getZExtValue();
4156 ConstantOffset += SL->getElementOffset(Idx);
4157 } else {
4158 uint64_t TypeSize = DL.getTypeAllocSize(GTI.getIndexedType());
4159 if (ConstantInt *CI = dyn_cast<ConstantInt>(AddrInst->getOperand(i))) {
4160 const APInt &CVal = CI->getValue();
4161 if (CVal.getMinSignedBits() <= 64) {
4162 ConstantOffset += CVal.getSExtValue() * TypeSize;
4163 continue;
4164 }
4165 }
4166 if (TypeSize) { // Scales of zero don't do anything.
4167 // We only allow one variable index at the moment.
4168 if (VariableOperand != -1)
4169 return false;
4170
4171 // Remember the variable index.
4172 VariableOperand = i;
4173 VariableScale = TypeSize;
4174 }
4175 }
4176 }
4177
4178 // A common case is for the GEP to only do a constant offset. In this case,
4179 // just add it to the disp field and check validity.
4180 if (VariableOperand == -1) {
4181 AddrMode.BaseOffs += ConstantOffset;
4182 if (ConstantOffset == 0 ||
4183 TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace)) {
4184 // Check to see if we can fold the base pointer in too.
4185 if (matchAddr(AddrInst->getOperand(0), Depth+1)) {
4186 if (!cast<GEPOperator>(AddrInst)->isInBounds())
4187 AddrMode.InBounds = false;
4188 return true;
4189 }
4190 } else if (EnableGEPOffsetSplit && isa<GetElementPtrInst>(AddrInst) &&
4191 TLI.shouldConsiderGEPOffsetSplit() && Depth == 0 &&
4192 ConstantOffset > 0) {
4193 // Record GEPs with non-zero offsets as candidates for splitting in the
4194 // event that the offset cannot fit into the r+i addressing mode.
4195 // Simple and common case that only one GEP is used in calculating the
4196 // address for the memory access.
4197 Value *Base = AddrInst->getOperand(0);
4198 auto *BaseI = dyn_cast<Instruction>(Base);
4199 auto *GEP = cast<GetElementPtrInst>(AddrInst);
4200 if (isa<Argument>(Base) || isa<GlobalValue>(Base) ||
4201 (BaseI && !isa<CastInst>(BaseI) &&
4202 !isa<GetElementPtrInst>(BaseI))) {
4203 // If the base is an instruction, make sure the GEP is not in the same
4204 // basic block as the base. If the base is an argument or global
4205 // value, make sure the GEP is not in the entry block. Otherwise,
4206 // instruction selection can undo the split. Also make sure the
4207 // parent block allows inserting non-PHI instructions before the
4208 // terminator.
4209 BasicBlock *Parent =
4210 BaseI ? BaseI->getParent() : &GEP->getFunction()->getEntryBlock();
4211 if (GEP->getParent() != Parent && !Parent->getTerminator()->isEHPad())
4212 LargeOffsetGEP = std::make_pair(GEP, ConstantOffset);
4213 }
4214 }
4215 AddrMode.BaseOffs -= ConstantOffset;
4216 return false;
4217 }
4218
4219 // Save the valid addressing mode in case we can't match.
4220 ExtAddrMode BackupAddrMode = AddrMode;
4221 unsigned OldSize = AddrModeInsts.size();
4222
4223 // See if the scale and offset amount is valid for this target.
4224 AddrMode.BaseOffs += ConstantOffset;
4225 if (!cast<GEPOperator>(AddrInst)->isInBounds())
4226 AddrMode.InBounds = false;
4227
4228 // Match the base operand of the GEP.
4229 if (!matchAddr(AddrInst->getOperand(0), Depth+1)) {
4230 // If it couldn't be matched, just stuff the value in a register.
4231 if (AddrMode.HasBaseReg) {
4232 AddrMode = BackupAddrMode;
4233 AddrModeInsts.resize(OldSize);
4234 return false;
4235 }
4236 AddrMode.HasBaseReg = true;
4237 AddrMode.BaseReg = AddrInst->getOperand(0);
4238 }
4239
4240 // Match the remaining variable portion of the GEP.
4241 if (!matchScaledValue(AddrInst->getOperand(VariableOperand), VariableScale,
4242 Depth)) {
4243 // If it couldn't be matched, try stuffing the base into a register
4244 // instead of matching it, and retrying the match of the scale.
4245 AddrMode = BackupAddrMode;
4246 AddrModeInsts.resize(OldSize);
4247 if (AddrMode.HasBaseReg)
4248 return false;
4249 AddrMode.HasBaseReg = true;
4250 AddrMode.BaseReg = AddrInst->getOperand(0);
4251 AddrMode.BaseOffs += ConstantOffset;
4252 if (!matchScaledValue(AddrInst->getOperand(VariableOperand),
4253 VariableScale, Depth)) {
4254 // If even that didn't work, bail.
4255 AddrMode = BackupAddrMode;
4256 AddrModeInsts.resize(OldSize);
4257 return false;
4258 }
4259 }
4260
4261 return true;
4262 }
4263 case Instruction::SExt:
4264 case Instruction::ZExt: {
4265 Instruction *Ext = dyn_cast<Instruction>(AddrInst);
4266 if (!Ext)
4267 return false;
4268
4269 // Try to move this ext out of the way of the addressing mode.
4270 // Ask for a method for doing so.
4271 TypePromotionHelper::Action TPH =
4272 TypePromotionHelper::getAction(Ext, InsertedInsts, TLI, PromotedInsts);
4273 if (!TPH)
4274 return false;
4275
4276 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4277 TPT.getRestorationPoint();
4278 unsigned CreatedInstsCost = 0;
4279 unsigned ExtCost = !TLI.isExtFree(Ext);
4280 Value *PromotedOperand =
4281 TPH(Ext, TPT, PromotedInsts, CreatedInstsCost, nullptr, nullptr, TLI);
4282 // SExt has been moved away.
4283 // Thus either it will be rematched later in the recursive calls or it is
4284 // gone. Anyway, we must not fold it into the addressing mode at this point.
4285 // E.g.,
4286 // op = add opnd, 1
4287 // idx = ext op
4288 // addr = gep base, idx
4289 // is now:
4290 // promotedOpnd = ext opnd <- no match here
4291 // op = promoted_add promotedOpnd, 1 <- match (later in recursive calls)
4292 // addr = gep base, op <- match
4293 if (MovedAway)
4294 *MovedAway = true;
4295
4296 assert(PromotedOperand &&((PromotedOperand && "TypePromotionHelper should have filtered out those cases"
) ? static_cast<void> (0) : __assert_fail ("PromotedOperand && \"TypePromotionHelper should have filtered out those cases\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 4297, __PRETTY_FUNCTION__))
4297 "TypePromotionHelper should have filtered out those cases")((PromotedOperand && "TypePromotionHelper should have filtered out those cases"
) ? static_cast<void> (0) : __assert_fail ("PromotedOperand && \"TypePromotionHelper should have filtered out those cases\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 4297, __PRETTY_FUNCTION__))
;
4298
4299 ExtAddrMode BackupAddrMode = AddrMode;
4300 unsigned OldSize = AddrModeInsts.size();
4301
4302 if (!matchAddr(PromotedOperand, Depth) ||
4303 // The total of the new cost is equal to the cost of the created
4304 // instructions.
4305 // The total of the old cost is equal to the cost of the extension plus
4306 // what we have saved in the addressing mode.
4307 !isPromotionProfitable(CreatedInstsCost,
4308 ExtCost + (AddrModeInsts.size() - OldSize),
4309 PromotedOperand)) {
4310 AddrMode = BackupAddrMode;
4311 AddrModeInsts.resize(OldSize);
4312 LLVM_DEBUG(dbgs() << "Sign extension does not pay off: rollback\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Sign extension does not pay off: rollback\n"
; } } while (false)
;
4313 TPT.rollback(LastKnownGood);
4314 return false;
4315 }
4316 return true;
4317 }
4318 }
4319 return false;
4320}
4321
4322/// If we can, try to add the value of 'Addr' into the current addressing mode.
4323/// If Addr can't be added to AddrMode this returns false and leaves AddrMode
4324/// unmodified. This assumes that Addr is either a pointer type or intptr_t
4325/// for the target.
4326///
4327bool AddressingModeMatcher::matchAddr(Value *Addr, unsigned Depth) {
4328 // Start a transaction at this point that we will rollback if the matching
4329 // fails.
4330 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4331 TPT.getRestorationPoint();
4332 if (ConstantInt *CI = dyn_cast<ConstantInt>(Addr)) {
4333 // Fold in immediates if legal for the target.
4334 AddrMode.BaseOffs += CI->getSExtValue();
4335 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
4336 return true;
4337 AddrMode.BaseOffs -= CI->getSExtValue();
4338 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(Addr)) {
4339 // If this is a global variable, try to fold it into the addressing mode.
4340 if (!AddrMode.BaseGV) {
4341 AddrMode.BaseGV = GV;
4342 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
4343 return true;
4344 AddrMode.BaseGV = nullptr;
4345 }
4346 } else if (Instruction *I = dyn_cast<Instruction>(Addr)) {
4347 ExtAddrMode BackupAddrMode = AddrMode;
4348 unsigned OldSize = AddrModeInsts.size();
4349
4350 // Check to see if it is possible to fold this operation.
4351 bool MovedAway = false;
4352 if (matchOperationAddr(I, I->getOpcode(), Depth, &MovedAway)) {
4353 // This instruction may have been moved away. If so, there is nothing
4354 // to check here.
4355 if (MovedAway)
4356 return true;
4357 // Okay, it's possible to fold this. Check to see if it is actually
4358 // *profitable* to do so. We use a simple cost model to avoid increasing
4359 // register pressure too much.
4360 if (I->hasOneUse() ||
4361 isProfitableToFoldIntoAddressingMode(I, BackupAddrMode, AddrMode)) {
4362 AddrModeInsts.push_back(I);
4363 return true;
4364 }
4365
4366 // It isn't profitable to do this, roll back.
4367 //cerr << "NOT FOLDING: " << *I;
4368 AddrMode = BackupAddrMode;
4369 AddrModeInsts.resize(OldSize);
4370 TPT.rollback(LastKnownGood);
4371 }
4372 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr)) {
4373 if (matchOperationAddr(CE, CE->getOpcode(), Depth))
4374 return true;
4375 TPT.rollback(LastKnownGood);
4376 } else if (isa<ConstantPointerNull>(Addr)) {
4377 // Null pointer gets folded without affecting the addressing mode.
4378 return true;
4379 }
4380
4381 // Worse case, the target should support [reg] addressing modes. :)
4382 if (!AddrMode.HasBaseReg) {
4383 AddrMode.HasBaseReg = true;
4384 AddrMode.BaseReg = Addr;
4385 // Still check for legality in case the target supports [imm] but not [i+r].
4386 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
4387 return true;
4388 AddrMode.HasBaseReg = false;
4389 AddrMode.BaseReg = nullptr;
4390 }
4391
4392 // If the base register is already taken, see if we can do [r+r].
4393 if (AddrMode.Scale == 0) {
4394 AddrMode.Scale = 1;
4395 AddrMode.ScaledReg = Addr;
4396 if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
4397 return true;
4398 AddrMode.Scale = 0;
4399 AddrMode.ScaledReg = nullptr;
4400 }
4401 // Couldn't match.
4402 TPT.rollback(LastKnownGood);
4403 return false;
4404}
4405
4406/// Check to see if all uses of OpVal by the specified inline asm call are due
4407/// to memory operands. If so, return true, otherwise return false.
4408static bool IsOperandAMemoryOperand(CallInst *CI, InlineAsm *IA, Value *OpVal,
4409 const TargetLowering &TLI,
4410 const TargetRegisterInfo &TRI) {
4411 const Function *F = CI->getFunction();
4412 TargetLowering::AsmOperandInfoVector TargetConstraints =
4413 TLI.ParseConstraints(F->getParent()->getDataLayout(), &TRI,
4414 ImmutableCallSite(CI));
4415
4416 for (unsigned i = 0, e = TargetConstraints.size(); i != e; ++i) {
4417 TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i];
4418
4419 // Compute the constraint code and ConstraintType to use.
4420 TLI.ComputeConstraintToUse(OpInfo, SDValue());
4421
4422 // If this asm operand is our Value*, and if it isn't an indirect memory
4423 // operand, we can't fold it!
4424 if (OpInfo.CallOperandVal == OpVal &&
4425 (OpInfo.ConstraintType != TargetLowering::C_Memory ||
4426 !OpInfo.isIndirect))
4427 return false;
4428 }
4429
4430 return true;
4431}
4432
4433// Max number of memory uses to look at before aborting the search to conserve
4434// compile time.
4435static constexpr int MaxMemoryUsesToScan = 20;
4436
4437/// Recursively walk all the uses of I until we find a memory use.
4438/// If we find an obviously non-foldable instruction, return true.
4439/// Add the ultimately found memory instructions to MemoryUses.
4440static bool FindAllMemoryUses(
4441 Instruction *I,
4442 SmallVectorImpl<std::pair<Instruction *, unsigned>> &MemoryUses,
4443 SmallPtrSetImpl<Instruction *> &ConsideredInsts, const TargetLowering &TLI,
4444 const TargetRegisterInfo &TRI, int SeenInsts = 0) {
4445 // If we already considered this instruction, we're done.
4446 if (!ConsideredInsts.insert(I).second)
4447 return false;
4448
4449 // If this is an obviously unfoldable instruction, bail out.
4450 if (!MightBeFoldableInst(I))
4451 return true;
4452
4453 const bool OptSize = I->getFunction()->hasOptSize();
4454
4455 // Loop over all the uses, recursively processing them.
4456 for (Use &U : I->uses()) {
4457 // Conservatively return true if we're seeing a large number or a deep chain
4458 // of users. This avoids excessive compilation times in pathological cases.
4459 if (SeenInsts++ >= MaxMemoryUsesToScan)
4460 return true;
4461
4462 Instruction *UserI = cast<Instruction>(U.getUser());
4463 if (LoadInst *LI = dyn_cast<LoadInst>(UserI)) {
4464 MemoryUses.push_back(std::make_pair(LI, U.getOperandNo()));
4465 continue;
4466 }
4467
4468 if (StoreInst *SI = dyn_cast<StoreInst>(UserI)) {
4469 unsigned opNo = U.getOperandNo();
4470 if (opNo != StoreInst::getPointerOperandIndex())
4471 return true; // Storing addr, not into addr.
4472 MemoryUses.push_back(std::make_pair(SI, opNo));
4473 continue;
4474 }
4475
4476 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(UserI)) {
4477 unsigned opNo = U.getOperandNo();
4478 if (opNo != AtomicRMWInst::getPointerOperandIndex())
4479 return true; // Storing addr, not into addr.
4480 MemoryUses.push_back(std::make_pair(RMW, opNo));
4481 continue;
4482 }
4483
4484 if (AtomicCmpXchgInst *CmpX = dyn_cast<AtomicCmpXchgInst>(UserI)) {
4485 unsigned opNo = U.getOperandNo();
4486 if (opNo != AtomicCmpXchgInst::getPointerOperandIndex())
4487 return true; // Storing addr, not into addr.
4488 MemoryUses.push_back(std::make_pair(CmpX, opNo));
4489 continue;
4490 }
4491
4492 if (CallInst *CI = dyn_cast<CallInst>(UserI)) {
4493 // If this is a cold call, we can sink the addressing calculation into
4494 // the cold path. See optimizeCallInst
4495 if (!OptSize && CI->hasFnAttr(Attribute::Cold))
4496 continue;
4497
4498 InlineAsm *IA = dyn_cast<InlineAsm>(CI->getCalledValue());
4499 if (!IA) return true;
4500
4501 // If this is a memory operand, we're cool, otherwise bail out.
4502 if (!IsOperandAMemoryOperand(CI, IA, I, TLI, TRI))
4503 return true;
4504 continue;
4505 }
4506
4507 if (FindAllMemoryUses(UserI, MemoryUses, ConsideredInsts, TLI, TRI,
4508 SeenInsts))
4509 return true;
4510 }
4511
4512 return false;
4513}
4514
4515/// Return true if Val is already known to be live at the use site that we're
4516/// folding it into. If so, there is no cost to include it in the addressing
4517/// mode. KnownLive1 and KnownLive2 are two values that we know are live at the
4518/// instruction already.
4519bool AddressingModeMatcher::valueAlreadyLiveAtInst(Value *Val,Value *KnownLive1,
4520 Value *KnownLive2) {
4521 // If Val is either of the known-live values, we know it is live!
4522 if (Val == nullptr || Val == KnownLive1 || Val == KnownLive2)
4523 return true;
4524
4525 // All values other than instructions and arguments (e.g. constants) are live.
4526 if (!isa<Instruction>(Val) && !isa<Argument>(Val)) return true;
4527
4528 // If Val is a constant sized alloca in the entry block, it is live, this is
4529 // true because it is just a reference to the stack/frame pointer, which is
4530 // live for the whole function.
4531 if (AllocaInst *AI = dyn_cast<AllocaInst>(Val))
4532 if (AI->isStaticAlloca())
4533 return true;
4534
4535 // Check to see if this value is already used in the memory instruction's
4536 // block. If so, it's already live into the block at the very least, so we
4537 // can reasonably fold it.
4538 return Val->isUsedInBasicBlock(MemoryInst->getParent());
4539}
4540
4541/// It is possible for the addressing mode of the machine to fold the specified
4542/// instruction into a load or store that ultimately uses it.
4543/// However, the specified instruction has multiple uses.
4544/// Given this, it may actually increase register pressure to fold it
4545/// into the load. For example, consider this code:
4546///
4547/// X = ...
4548/// Y = X+1
4549/// use(Y) -> nonload/store
4550/// Z = Y+1
4551/// load Z
4552///
4553/// In this case, Y has multiple uses, and can be folded into the load of Z
4554/// (yielding load [X+2]). However, doing this will cause both "X" and "X+1" to
4555/// be live at the use(Y) line. If we don't fold Y into load Z, we use one
4556/// fewer register. Since Y can't be folded into "use(Y)" we don't increase the
4557/// number of computations either.
4558///
4559/// Note that this (like most of CodeGenPrepare) is just a rough heuristic. If
4560/// X was live across 'load Z' for other reasons, we actually *would* want to
4561/// fold the addressing mode in the Z case. This would make Y die earlier.
4562bool AddressingModeMatcher::
4563isProfitableToFoldIntoAddressingMode(Instruction *I, ExtAddrMode &AMBefore,
4564 ExtAddrMode &AMAfter) {
4565 if (IgnoreProfitability) return true;
4566
4567 // AMBefore is the addressing mode before this instruction was folded into it,
4568 // and AMAfter is the addressing mode after the instruction was folded. Get
4569 // the set of registers referenced by AMAfter and subtract out those
4570 // referenced by AMBefore: this is the set of values which folding in this
4571 // address extends the lifetime of.
4572 //
4573 // Note that there are only two potential values being referenced here,
4574 // BaseReg and ScaleReg (global addresses are always available, as are any
4575 // folded immediates).
4576 Value *BaseReg = AMAfter.BaseReg, *ScaledReg = AMAfter.ScaledReg;
4577
4578 // If the BaseReg or ScaledReg was referenced by the previous addrmode, their
4579 // lifetime wasn't extended by adding this instruction.
4580 if (valueAlreadyLiveAtInst(BaseReg, AMBefore.BaseReg, AMBefore.ScaledReg))
4581 BaseReg = nullptr;
4582 if (valueAlreadyLiveAtInst(ScaledReg, AMBefore.BaseReg, AMBefore.ScaledReg))
4583 ScaledReg = nullptr;
4584
4585 // If folding this instruction (and it's subexprs) didn't extend any live
4586 // ranges, we're ok with it.
4587 if (!BaseReg && !ScaledReg)
4588 return true;
4589
4590 // If all uses of this instruction can have the address mode sunk into them,
4591 // we can remove the addressing mode and effectively trade one live register
4592 // for another (at worst.) In this context, folding an addressing mode into
4593 // the use is just a particularly nice way of sinking it.
4594 SmallVector<std::pair<Instruction*,unsigned>, 16> MemoryUses;
4595 SmallPtrSet<Instruction*, 16> ConsideredInsts;
4596 if (FindAllMemoryUses(I, MemoryUses, ConsideredInsts, TLI, TRI))
4597 return false; // Has a non-memory, non-foldable use!
4598
4599 // Now that we know that all uses of this instruction are part of a chain of
4600 // computation involving only operations that could theoretically be folded
4601 // into a memory use, loop over each of these memory operation uses and see
4602 // if they could *actually* fold the instruction. The assumption is that
4603 // addressing modes are cheap and that duplicating the computation involved
4604 // many times is worthwhile, even on a fastpath. For sinking candidates
4605 // (i.e. cold call sites), this serves as a way to prevent excessive code
4606 // growth since most architectures have some reasonable small and fast way to
4607 // compute an effective address. (i.e LEA on x86)
4608 SmallVector<Instruction*, 32> MatchedAddrModeInsts;
4609 for (unsigned i = 0, e = MemoryUses.size(); i != e; ++i) {
4610 Instruction *User = MemoryUses[i].first;
4611 unsigned OpNo = MemoryUses[i].second;
4612
4613 // Get the access type of this use. If the use isn't a pointer, we don't
4614 // know what it accesses.
4615 Value *Address = User->getOperand(OpNo);
4616 PointerType *AddrTy = dyn_cast<PointerType>(Address->getType());
4617 if (!AddrTy)
4618 return false;
4619 Type *AddressAccessTy = AddrTy->getElementType();
4620 unsigned AS = AddrTy->getAddressSpace();
4621
4622 // Do a match against the root of this address, ignoring profitability. This
4623 // will tell us if the addressing mode for the memory operation will
4624 // *actually* cover the shared instruction.
4625 ExtAddrMode Result;
4626 std::pair<AssertingVH<GetElementPtrInst>, int64_t> LargeOffsetGEP(nullptr,
4627 0);
4628 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4629 TPT.getRestorationPoint();
4630 AddressingModeMatcher Matcher(
4631 MatchedAddrModeInsts, TLI, TRI, AddressAccessTy, AS, MemoryInst, Result,
4632 InsertedInsts, PromotedInsts, TPT, LargeOffsetGEP);
4633 Matcher.IgnoreProfitability = true;
4634 bool Success = Matcher.matchAddr(Address, 0);
4635 (void)Success; assert(Success && "Couldn't select *anything*?")((Success && "Couldn't select *anything*?") ? static_cast
<void> (0) : __assert_fail ("Success && \"Couldn't select *anything*?\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 4635, __PRETTY_FUNCTION__))
;
4636
4637 // The match was to check the profitability, the changes made are not
4638 // part of the original matcher. Therefore, they should be dropped
4639 // otherwise the original matcher will not present the right state.
4640 TPT.rollback(LastKnownGood);
4641
4642 // If the match didn't cover I, then it won't be shared by it.
4643 if (!is_contained(MatchedAddrModeInsts, I))
4644 return false;
4645
4646 MatchedAddrModeInsts.clear();
4647 }
4648
4649 return true;
4650}
4651
4652/// Return true if the specified values are defined in a
4653/// different basic block than BB.
4654static bool IsNonLocalValue(Value *V, BasicBlock *BB) {
4655 if (Instruction *I = dyn_cast<Instruction>(V))
4656 return I->getParent() != BB;
4657 return false;
4658}
4659
4660/// Sink addressing mode computation immediate before MemoryInst if doing so
4661/// can be done without increasing register pressure. The need for the
4662/// register pressure constraint means this can end up being an all or nothing
4663/// decision for all uses of the same addressing computation.
4664///
4665/// Load and Store Instructions often have addressing modes that can do
4666/// significant amounts of computation. As such, instruction selection will try
4667/// to get the load or store to do as much computation as possible for the
4668/// program. The problem is that isel can only see within a single block. As
4669/// such, we sink as much legal addressing mode work into the block as possible.
4670///
4671/// This method is used to optimize both load/store and inline asms with memory
4672/// operands. It's also used to sink addressing computations feeding into cold
4673/// call sites into their (cold) basic block.
4674///
4675/// The motivation for handling sinking into cold blocks is that doing so can
4676/// both enable other address mode sinking (by satisfying the register pressure
4677/// constraint above), and reduce register pressure globally (by removing the
4678/// addressing mode computation from the fast path entirely.).
4679bool CodeGenPrepare::optimizeMemoryInst(Instruction *MemoryInst, Value *Addr,
4680 Type *AccessTy, unsigned AddrSpace) {
4681 Value *Repl = Addr;
4682
4683 // Try to collapse single-value PHI nodes. This is necessary to undo
4684 // unprofitable PRE transformations.
4685 SmallVector<Value*, 8> worklist;
4686 SmallPtrSet<Value*, 16> Visited;
4687 worklist.push_back(Addr);
4688
4689 // Use a worklist to iteratively look through PHI and select nodes, and
4690 // ensure that the addressing mode obtained from the non-PHI/select roots of
4691 // the graph are compatible.
4692 bool PhiOrSelectSeen = false;
4693 SmallVector<Instruction*, 16> AddrModeInsts;
4694 const SimplifyQuery SQ(*DL, TLInfo);
4695 AddressingModeCombiner AddrModes(SQ, Addr);
4696 TypePromotionTransaction TPT(RemovedInsts);
4697 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
4698 TPT.getRestorationPoint();
4699 while (!worklist.empty()) {
4700 Value *V = worklist.back();
4701 worklist.pop_back();
4702
4703 // We allow traversing cyclic Phi nodes.
4704 // In case of success after this loop we ensure that traversing through
4705 // Phi nodes ends up with all cases to compute address of the form
4706 // BaseGV + Base + Scale * Index + Offset
4707 // where Scale and Offset are constans and BaseGV, Base and Index
4708 // are exactly the same Values in all cases.
4709 // It means that BaseGV, Scale and Offset dominate our memory instruction
4710 // and have the same value as they had in address computation represented
4711 // as Phi. So we can safely sink address computation to memory instruction.
4712 if (!Visited.insert(V).second)
4713 continue;
4714
4715 // For a PHI node, push all of its incoming values.
4716 if (PHINode *P = dyn_cast<PHINode>(V)) {
4717 for (Value *IncValue : P->incoming_values())
4718 worklist.push_back(IncValue);
4719 PhiOrSelectSeen = true;
4720 continue;
4721 }
4722 // Similar for select.
4723 if (SelectInst *SI = dyn_cast<SelectInst>(V)) {
4724 worklist.push_back(SI->getFalseValue());
4725 worklist.push_back(SI->getTrueValue());
4726 PhiOrSelectSeen = true;
4727 continue;
4728 }
4729
4730 // For non-PHIs, determine the addressing mode being computed. Note that
4731 // the result may differ depending on what other uses our candidate
4732 // addressing instructions might have.
4733 AddrModeInsts.clear();
4734 std::pair<AssertingVH<GetElementPtrInst>, int64_t> LargeOffsetGEP(nullptr,
4735 0);
4736 ExtAddrMode NewAddrMode = AddressingModeMatcher::Match(
4737 V, AccessTy, AddrSpace, MemoryInst, AddrModeInsts, *TLI, *TRI,
4738 InsertedInsts, PromotedInsts, TPT, LargeOffsetGEP);
4739
4740 GetElementPtrInst *GEP = LargeOffsetGEP.first;
4741 if (GEP && GEP->getParent() != MemoryInst->getParent() &&
4742 !NewGEPBases.count(GEP)) {
4743 // If splitting the underlying data structure can reduce the offset of a
4744 // GEP, collect the GEP. Skip the GEPs that are the new bases of
4745 // previously split data structures.
4746 LargeOffsetGEPMap[GEP->getPointerOperand()].push_back(LargeOffsetGEP);
4747 if (LargeOffsetGEPID.find(GEP) == LargeOffsetGEPID.end())
4748 LargeOffsetGEPID[GEP] = LargeOffsetGEPID.size();
4749 }
4750
4751 NewAddrMode.OriginalValue = V;
4752 if (!AddrModes.addNewAddrMode(NewAddrMode))
4753 break;
4754 }
4755
4756 // Try to combine the AddrModes we've collected. If we couldn't collect any,
4757 // or we have multiple but either couldn't combine them or combining them
4758 // wouldn't do anything useful, bail out now.
4759 if (!AddrModes.combineAddrModes()) {
4760 TPT.rollback(LastKnownGood);
4761 return false;
4762 }
4763 TPT.commit();
4764
4765 // Get the combined AddrMode (or the only AddrMode, if we only had one).
4766 ExtAddrMode AddrMode = AddrModes.getAddrMode();
4767
4768 // If all the instructions matched are already in this BB, don't do anything.
4769 // If we saw a Phi node then it is not local definitely, and if we saw a select
4770 // then we want to push the address calculation past it even if it's already
4771 // in this BB.
4772 if (!PhiOrSelectSeen && none_of(AddrModeInsts, [&](Value *V) {
4773 return IsNonLocalValue(V, MemoryInst->getParent());
4774 })) {
4775 LLVM_DEBUG(dbgs() << "CGP: Found local addrmode: " << AddrModedo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: Found local addrmode: "
<< AddrMode << "\n"; } } while (false)
4776 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: Found local addrmode: "
<< AddrMode << "\n"; } } while (false)
;
4777 return false;
4778 }
4779
4780 // Insert this computation right after this user. Since our caller is
4781 // scanning from the top of the BB to the bottom, reuse of the expr are
4782 // guaranteed to happen later.
4783 IRBuilder<> Builder(MemoryInst);
4784
4785 // Now that we determined the addressing expression we want to use and know
4786 // that we have to sink it into this block. Check to see if we have already
4787 // done this for some other load/store instr in this block. If so, reuse
4788 // the computation. Before attempting reuse, check if the address is valid
4789 // as it may have been erased.
4790
4791 WeakTrackingVH SunkAddrVH = SunkAddrs[Addr];
4792
4793 Value * SunkAddr = SunkAddrVH.pointsToAliveValue() ? SunkAddrVH : nullptr;
4794 if (SunkAddr) {
4795 LLVM_DEBUG(dbgs() << "CGP: Reusing nonlocal addrmode: " << AddrModedo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: Reusing nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
4796 << " for " << *MemoryInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: Reusing nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
;
4797 if (SunkAddr->getType() != Addr->getType())
4798 SunkAddr = Builder.CreatePointerCast(SunkAddr, Addr->getType());
4799 } else if (AddrSinkUsingGEPs ||
4800 (!AddrSinkUsingGEPs.getNumOccurrences() && TM && TTI->useAA())) {
4801 // By default, we use the GEP-based method when AA is used later. This
4802 // prevents new inttoptr/ptrtoint pairs from degrading AA capabilities.
4803 LLVM_DEBUG(dbgs() << "CGP: SINKING nonlocal addrmode: " << AddrModedo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
4804 << " for " << *MemoryInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
;
4805 Type *IntPtrTy = DL->getIntPtrType(Addr->getType());
4806 Value *ResultPtr = nullptr, *ResultIndex = nullptr;
4807
4808 // First, find the pointer.
4809 if (AddrMode.BaseReg && AddrMode.BaseReg->getType()->isPointerTy()) {
4810 ResultPtr = AddrMode.BaseReg;
4811 AddrMode.BaseReg = nullptr;
4812 }
4813
4814 if (AddrMode.Scale && AddrMode.ScaledReg->getType()->isPointerTy()) {
4815 // We can't add more than one pointer together, nor can we scale a
4816 // pointer (both of which seem meaningless).
4817 if (ResultPtr || AddrMode.Scale != 1)
4818 return false;
4819
4820 ResultPtr = AddrMode.ScaledReg;
4821 AddrMode.Scale = 0;
4822 }
4823
4824 // It is only safe to sign extend the BaseReg if we know that the math
4825 // required to create it did not overflow before we extend it. Since
4826 // the original IR value was tossed in favor of a constant back when
4827 // the AddrMode was created we need to bail out gracefully if widths
4828 // do not match instead of extending it.
4829 //
4830 // (See below for code to add the scale.)
4831 if (AddrMode.Scale) {
4832 Type *ScaledRegTy = AddrMode.ScaledReg->getType();
4833 if (cast<IntegerType>(IntPtrTy)->getBitWidth() >
4834 cast<IntegerType>(ScaledRegTy)->getBitWidth())
4835 return false;
4836 }
4837
4838 if (AddrMode.BaseGV) {
4839 if (ResultPtr)
4840 return false;
4841
4842 ResultPtr = AddrMode.BaseGV;
4843 }
4844
4845 // If the real base value actually came from an inttoptr, then the matcher
4846 // will look through it and provide only the integer value. In that case,
4847 // use it here.
4848 if (!DL->isNonIntegralPointerType(Addr->getType())) {
4849 if (!ResultPtr && AddrMode.BaseReg) {
4850 ResultPtr = Builder.CreateIntToPtr(AddrMode.BaseReg, Addr->getType(),
4851 "sunkaddr");
4852 AddrMode.BaseReg = nullptr;
4853 } else if (!ResultPtr && AddrMode.Scale == 1) {
4854 ResultPtr = Builder.CreateIntToPtr(AddrMode.ScaledReg, Addr->getType(),
4855 "sunkaddr");
4856 AddrMode.Scale = 0;
4857 }
4858 }
4859
4860 if (!ResultPtr &&
4861 !AddrMode.BaseReg && !AddrMode.Scale && !AddrMode.BaseOffs) {
4862 SunkAddr = Constant::getNullValue(Addr->getType());
4863 } else if (!ResultPtr) {
4864 return false;
4865 } else {
4866 Type *I8PtrTy =
4867 Builder.getInt8PtrTy(Addr->getType()->getPointerAddressSpace());
4868 Type *I8Ty = Builder.getInt8Ty();
4869
4870 // Start with the base register. Do this first so that subsequent address
4871 // matching finds it last, which will prevent it from trying to match it
4872 // as the scaled value in case it happens to be a mul. That would be
4873 // problematic if we've sunk a different mul for the scale, because then
4874 // we'd end up sinking both muls.
4875 if (AddrMode.BaseReg) {
4876 Value *V = AddrMode.BaseReg;
4877 if (V->getType() != IntPtrTy)
4878 V = Builder.CreateIntCast(V, IntPtrTy, /*isSigned=*/true, "sunkaddr");
4879
4880 ResultIndex = V;
4881 }
4882
4883 // Add the scale value.
4884 if (AddrMode.Scale) {
4885 Value *V = AddrMode.ScaledReg;
4886 if (V->getType() == IntPtrTy) {
4887 // done.
4888 } else {
4889 assert(cast<IntegerType>(IntPtrTy)->getBitWidth() <((cast<IntegerType>(IntPtrTy)->getBitWidth() < cast
<IntegerType>(V->getType())->getBitWidth() &&
"We can't transform if ScaledReg is too narrow") ? static_cast
<void> (0) : __assert_fail ("cast<IntegerType>(IntPtrTy)->getBitWidth() < cast<IntegerType>(V->getType())->getBitWidth() && \"We can't transform if ScaledReg is too narrow\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 4891, __PRETTY_FUNCTION__))
4890 cast<IntegerType>(V->getType())->getBitWidth() &&((cast<IntegerType>(IntPtrTy)->getBitWidth() < cast
<IntegerType>(V->getType())->getBitWidth() &&
"We can't transform if ScaledReg is too narrow") ? static_cast
<void> (0) : __assert_fail ("cast<IntegerType>(IntPtrTy)->getBitWidth() < cast<IntegerType>(V->getType())->getBitWidth() && \"We can't transform if ScaledReg is too narrow\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 4891, __PRETTY_FUNCTION__))
4891 "We can't transform if ScaledReg is too narrow")((cast<IntegerType>(IntPtrTy)->getBitWidth() < cast
<IntegerType>(V->getType())->getBitWidth() &&
"We can't transform if ScaledReg is too narrow") ? static_cast
<void> (0) : __assert_fail ("cast<IntegerType>(IntPtrTy)->getBitWidth() < cast<IntegerType>(V->getType())->getBitWidth() && \"We can't transform if ScaledReg is too narrow\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 4891, __PRETTY_FUNCTION__))
;
4892 V = Builder.CreateTrunc(V, IntPtrTy, "sunkaddr");
4893 }
4894
4895 if (AddrMode.Scale != 1)
4896 V = Builder.CreateMul(V, ConstantInt::get(IntPtrTy, AddrMode.Scale),
4897 "sunkaddr");
4898 if (ResultIndex)
4899 ResultIndex = Builder.CreateAdd(ResultIndex, V, "sunkaddr");
4900 else
4901 ResultIndex = V;
4902 }
4903
4904 // Add in the Base Offset if present.
4905 if (AddrMode.BaseOffs) {
4906 Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);
4907 if (ResultIndex) {
4908 // We need to add this separately from the scale above to help with
4909 // SDAG consecutive load/store merging.
4910 if (ResultPtr->getType() != I8PtrTy)
4911 ResultPtr = Builder.CreatePointerCast(ResultPtr, I8PtrTy);
4912 ResultPtr =
4913 AddrMode.InBounds
4914 ? Builder.CreateInBoundsGEP(I8Ty, ResultPtr, ResultIndex,
4915 "sunkaddr")
4916 : Builder.CreateGEP(I8Ty, ResultPtr, ResultIndex, "sunkaddr");
4917 }
4918
4919 ResultIndex = V;
4920 }
4921
4922 if (!ResultIndex) {
4923 SunkAddr = ResultPtr;
4924 } else {
4925 if (ResultPtr->getType() != I8PtrTy)
4926 ResultPtr = Builder.CreatePointerCast(ResultPtr, I8PtrTy);
4927 SunkAddr =
4928 AddrMode.InBounds
4929 ? Builder.CreateInBoundsGEP(I8Ty, ResultPtr, ResultIndex,
4930 "sunkaddr")
4931 : Builder.CreateGEP(I8Ty, ResultPtr, ResultIndex, "sunkaddr");
4932 }
4933
4934 if (SunkAddr->getType() != Addr->getType())
4935 SunkAddr = Builder.CreatePointerCast(SunkAddr, Addr->getType());
4936 }
4937 } else {
4938 // We'd require a ptrtoint/inttoptr down the line, which we can't do for
4939 // non-integral pointers, so in that case bail out now.
4940 Type *BaseTy = AddrMode.BaseReg ? AddrMode.BaseReg->getType() : nullptr;
4941 Type *ScaleTy = AddrMode.Scale ? AddrMode.ScaledReg->getType() : nullptr;
4942 PointerType *BasePtrTy = dyn_cast_or_null<PointerType>(BaseTy);
4943 PointerType *ScalePtrTy = dyn_cast_or_null<PointerType>(ScaleTy);
4944 if (DL->isNonIntegralPointerType(Addr->getType()) ||
4945 (BasePtrTy && DL->isNonIntegralPointerType(BasePtrTy)) ||
4946 (ScalePtrTy && DL->isNonIntegralPointerType(ScalePtrTy)) ||
4947 (AddrMode.BaseGV &&
4948 DL->isNonIntegralPointerType(AddrMode.BaseGV->getType())))
4949 return false;
4950
4951 LLVM_DEBUG(dbgs() << "CGP: SINKING nonlocal addrmode: " << AddrModedo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
4952 << " for " << *MemoryInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)
;
4953 Type *IntPtrTy = DL->getIntPtrType(Addr->getType());
4954 Value *Result = nullptr;
4955
4956 // Start with the base register. Do this first so that subsequent address
4957 // matching finds it last, which will prevent it from trying to match it
4958 // as the scaled value in case it happens to be a mul. That would be
4959 // problematic if we've sunk a different mul for the scale, because then
4960 // we'd end up sinking both muls.
4961 if (AddrMode.BaseReg) {
4962 Value *V = AddrMode.BaseReg;
4963 if (V->getType()->isPointerTy())
4964 V = Builder.CreatePtrToInt(V, IntPtrTy, "sunkaddr");
4965 if (V->getType() != IntPtrTy)
4966 V = Builder.CreateIntCast(V, IntPtrTy, /*isSigned=*/true, "sunkaddr");
4967 Result = V;
4968 }
4969
4970 // Add the scale value.
4971 if (AddrMode.Scale) {
4972 Value *V = AddrMode.ScaledReg;
4973 if (V->getType() == IntPtrTy) {
4974 // done.
4975 } else if (V->getType()->isPointerTy()) {
4976 V = Builder.CreatePtrToInt(V, IntPtrTy, "sunkaddr");
4977 } else if (cast<IntegerType>(IntPtrTy)->getBitWidth() <
4978 cast<IntegerType>(V->getType())->getBitWidth()) {
4979 V = Builder.CreateTrunc(V, IntPtrTy, "sunkaddr");
4980 } else {
4981 // It is only safe to sign extend the BaseReg if we know that the math
4982 // required to create it did not overflow before we extend it. Since
4983 // the original IR value was tossed in favor of a constant back when
4984 // the AddrMode was created we need to bail out gracefully if widths
4985 // do not match instead of extending it.
4986 Instruction *I = dyn_cast_or_null<Instruction>(Result);
4987 if (I && (Result != AddrMode.BaseReg))
4988 I->eraseFromParent();
4989 return false;
4990 }
4991 if (AddrMode.Scale != 1)
4992 V = Builder.CreateMul(V, ConstantInt::get(IntPtrTy, AddrMode.Scale),
4993 "sunkaddr");
4994 if (Result)
4995 Result = Builder.CreateAdd(Result, V, "sunkaddr");
4996 else
4997 Result = V;
4998 }
4999
5000 // Add in the BaseGV if present.
5001 if (AddrMode.BaseGV) {
5002 Value *V = Builder.CreatePtrToInt(AddrMode.BaseGV, IntPtrTy, "sunkaddr");
5003 if (Result)
5004 Result = Builder.CreateAdd(Result, V, "sunkaddr");
5005 else
5006 Result = V;
5007 }
5008
5009 // Add in the Base Offset if present.
5010 if (AddrMode.BaseOffs) {
5011 Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);
5012 if (Result)
5013 Result = Builder.CreateAdd(Result, V, "sunkaddr");
5014 else
5015 Result = V;
5016 }
5017
5018 if (!Result)
5019 SunkAddr = Constant::getNullValue(Addr->getType());
5020 else
5021 SunkAddr = Builder.CreateIntToPtr(Result, Addr->getType(), "sunkaddr");
5022 }
5023
5024 MemoryInst->replaceUsesOfWith(Repl, SunkAddr);
5025 // Store the newly computed address into the cache. In the case we reused a
5026 // value, this should be idempotent.
5027 SunkAddrs[Addr] = WeakTrackingVH(SunkAddr);
5028
5029 // If we have no uses, recursively delete the value and all dead instructions
5030 // using it.
5031 if (Repl->use_empty()) {
5032 // This can cause recursive deletion, which can invalidate our iterator.
5033 // Use a WeakTrackingVH to hold onto it in case this happens.
5034 Value *CurValue = &*CurInstIterator;
5035 WeakTrackingVH IterHandle(CurValue);
5036 BasicBlock *BB = CurInstIterator->getParent();
5037
5038 RecursivelyDeleteTriviallyDeadInstructions(Repl, TLInfo);
5039
5040 if (IterHandle != CurValue) {
5041 // If the iterator instruction was recursively deleted, start over at the
5042 // start of the block.
5043 CurInstIterator = BB->begin();
5044 SunkAddrs.clear();
5045 }
5046 }
5047 ++NumMemoryInsts;
5048 return true;
5049}
5050
5051/// If there are any memory operands, use OptimizeMemoryInst to sink their
5052/// address computing into the block when possible / profitable.
5053bool CodeGenPrepare::optimizeInlineAsmInst(CallInst *CS) {
5054 bool MadeChange = false;
5055
5056 const TargetRegisterInfo *TRI =
5057 TM->getSubtargetImpl(*CS->getFunction())->getRegisterInfo();
5058 TargetLowering::AsmOperandInfoVector TargetConstraints =
5059 TLI->ParseConstraints(*DL, TRI, CS);
5060 unsigned ArgNo = 0;
5061 for (unsigned i = 0, e = TargetConstraints.size(); i != e; ++i) {
5062 TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i];
5063
5064 // Compute the constraint code and ConstraintType to use.
5065 TLI->ComputeConstraintToUse(OpInfo, SDValue());
5066
5067 if (OpInfo.ConstraintType == TargetLowering::C_Memory &&
5068 OpInfo.isIndirect) {
5069 Value *OpVal = CS->getArgOperand(ArgNo++);
5070 MadeChange |= optimizeMemoryInst(CS, OpVal, OpVal->getType(), ~0u);
5071 } else if (OpInfo.Type == InlineAsm::isInput)
5072 ArgNo++;
5073 }
5074
5075 return MadeChange;
5076}
5077
5078/// Check if all the uses of \p Val are equivalent (or free) zero or
5079/// sign extensions.
5080static bool hasSameExtUse(Value *Val, const TargetLowering &TLI) {
5081 assert(!Val->use_empty() && "Input must have at least one use")((!Val->use_empty() && "Input must have at least one use"
) ? static_cast<void> (0) : __assert_fail ("!Val->use_empty() && \"Input must have at least one use\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 5081, __PRETTY_FUNCTION__))
;
5082 const Instruction *FirstUser = cast<Instruction>(*Val->user_begin());
5083 bool IsSExt = isa<SExtInst>(FirstUser);
5084 Type *ExtTy = FirstUser->getType();
5085 for (const User *U : Val->users()) {
5086 const Instruction *UI = cast<Instruction>(U);
5087 if ((IsSExt && !isa<SExtInst>(UI)) || (!IsSExt && !isa<ZExtInst>(UI)))
5088 return false;
5089 Type *CurTy = UI->getType();
5090 // Same input and output types: Same instruction after CSE.
5091 if (CurTy == ExtTy)
5092 continue;
5093
5094 // If IsSExt is true, we are in this situation:
5095 // a = Val
5096 // b = sext ty1 a to ty2
5097 // c = sext ty1 a to ty3
5098 // Assuming ty2 is shorter than ty3, this could be turned into:
5099 // a = Val
5100 // b = sext ty1 a to ty2
5101 // c = sext ty2 b to ty3
5102 // However, the last sext is not free.
5103 if (IsSExt)
5104 return false;
5105
5106 // This is a ZExt, maybe this is free to extend from one type to another.
5107 // In that case, we would not account for a different use.
5108 Type *NarrowTy;
5109 Type *LargeTy;
5110 if (ExtTy->getScalarType()->getIntegerBitWidth() >
5111 CurTy->getScalarType()->getIntegerBitWidth()) {
5112 NarrowTy = CurTy;
5113 LargeTy = ExtTy;
5114 } else {
5115 NarrowTy = ExtTy;
5116 LargeTy = CurTy;
5117 }
5118
5119 if (!TLI.isZExtFree(NarrowTy, LargeTy))
5120 return false;
5121 }
5122 // All uses are the same or can be derived from one another for free.
5123 return true;
5124}
5125
5126/// Try to speculatively promote extensions in \p Exts and continue
5127/// promoting through newly promoted operands recursively as far as doing so is
5128/// profitable. Save extensions profitably moved up, in \p ProfitablyMovedExts.
5129/// When some promotion happened, \p TPT contains the proper state to revert
5130/// them.
5131///
5132/// \return true if some promotion happened, false otherwise.
5133bool CodeGenPrepare::tryToPromoteExts(
5134 TypePromotionTransaction &TPT, const SmallVectorImpl<Instruction *> &Exts,
5135 SmallVectorImpl<Instruction *> &ProfitablyMovedExts,
5136 unsigned CreatedInstsCost) {
5137 bool Promoted = false;
5138
5139 // Iterate over all the extensions to try to promote them.
5140 for (auto I : Exts) {
5141 // Early check if we directly have ext(load).
5142 if (isa<LoadInst>(I->getOperand(0))) {
5143 ProfitablyMovedExts.push_back(I);
5144 continue;
5145 }
5146
5147 // Check whether or not we want to do any promotion. The reason we have
5148 // this check inside the for loop is to catch the case where an extension
5149 // is directly fed by a load because in such case the extension can be moved
5150 // up without any promotion on its operands.
5151 if (!TLI || !TLI->enableExtLdPromotion() || DisableExtLdPromotion)
5152 return false;
5153
5154 // Get the action to perform the promotion.
5155 TypePromotionHelper::Action TPH =
5156 TypePromotionHelper::getAction(I, InsertedInsts, *TLI, PromotedInsts);
5157 // Check if we can promote.
5158 if (!TPH) {
5159 // Save the current extension as we cannot move up through its operand.
5160 ProfitablyMovedExts.push_back(I);
5161 continue;
5162 }
5163
5164 // Save the current state.
5165 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
5166 TPT.getRestorationPoint();
5167 SmallVector<Instruction *, 4> NewExts;
5168 unsigned NewCreatedInstsCost = 0;
5169 unsigned ExtCost = !TLI->isExtFree(I);
5170 // Promote.
5171 Value *PromotedVal = TPH(I, TPT, PromotedInsts, NewCreatedInstsCost,
5172 &NewExts, nullptr, *TLI);
5173 assert(PromotedVal &&((PromotedVal && "TypePromotionHelper should have filtered out those cases"
) ? static_cast<void> (0) : __assert_fail ("PromotedVal && \"TypePromotionHelper should have filtered out those cases\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 5174, __PRETTY_FUNCTION__))
5174 "TypePromotionHelper should have filtered out those cases")((PromotedVal && "TypePromotionHelper should have filtered out those cases"
) ? static_cast<void> (0) : __assert_fail ("PromotedVal && \"TypePromotionHelper should have filtered out those cases\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 5174, __PRETTY_FUNCTION__))
;
5175
5176 // We would be able to merge only one extension in a load.
5177 // Therefore, if we have more than 1 new extension we heuristically
5178 // cut this search path, because it means we degrade the code quality.
5179 // With exactly 2, the transformation is neutral, because we will merge
5180 // one extension but leave one. However, we optimistically keep going,
5181 // because the new extension may be removed too.
5182 long long TotalCreatedInstsCost = CreatedInstsCost + NewCreatedInstsCost;
5183 // FIXME: It would be possible to propagate a negative value instead of
5184 // conservatively ceiling it to 0.
5185 TotalCreatedInstsCost =
5186 std::max((long long)0, (TotalCreatedInstsCost - ExtCost));
5187 if (!StressExtLdPromotion &&
5188 (TotalCreatedInstsCost > 1 ||
5189 !isPromotedInstructionLegal(*TLI, *DL, PromotedVal))) {
5190 // This promotion is not profitable, rollback to the previous state, and
5191 // save the current extension in ProfitablyMovedExts as the latest
5192 // speculative promotion turned out to be unprofitable.
5193 TPT.rollback(LastKnownGood);
5194 ProfitablyMovedExts.push_back(I);
5195 continue;
5196 }
5197 // Continue promoting NewExts as far as doing so is profitable.
5198 SmallVector<Instruction *, 2> NewlyMovedExts;
5199 (void)tryToPromoteExts(TPT, NewExts, NewlyMovedExts, TotalCreatedInstsCost);
5200 bool NewPromoted = false;
5201 for (auto ExtInst : NewlyMovedExts) {
5202 Instruction *MovedExt = cast<Instruction>(ExtInst);
5203 Value *ExtOperand = MovedExt->getOperand(0);
5204 // If we have reached to a load, we need this extra profitability check
5205 // as it could potentially be merged into an ext(load).
5206 if (isa<LoadInst>(ExtOperand) &&
5207 !(StressExtLdPromotion || NewCreatedInstsCost <= ExtCost ||
5208 (ExtOperand->hasOneUse() || hasSameExtUse(ExtOperand, *TLI))))
5209 continue;
5210
5211 ProfitablyMovedExts.push_back(MovedExt);
5212 NewPromoted = true;
5213 }
5214
5215 // If none of speculative promotions for NewExts is profitable, rollback
5216 // and save the current extension (I) as the last profitable extension.
5217 if (!NewPromoted) {
5218 TPT.rollback(LastKnownGood);
5219 ProfitablyMovedExts.push_back(I);
5220 continue;
5221 }
5222 // The promotion is profitable.
5223 Promoted = true;
5224 }
5225 return Promoted;
5226}
5227
5228/// Merging redundant sexts when one is dominating the other.
5229bool CodeGenPrepare::mergeSExts(Function &F) {
5230 bool Changed = false;
5231 for (auto &Entry : ValToSExtendedUses) {
5232 SExts &Insts = Entry.second;
5233 SExts CurPts;
5234 for (Instruction *Inst : Insts) {
5235 if (RemovedInsts.count(Inst) || !isa<SExtInst>(Inst) ||
5236 Inst->getOperand(0) != Entry.first)
5237 continue;
5238 bool inserted = false;
5239 for (auto &Pt : CurPts) {
5240 if (getDT(F).dominates(Inst, Pt)) {
5241 Pt->replaceAllUsesWith(Inst);
5242 RemovedInsts.insert(Pt);
5243 Pt->removeFromParent();
5244 Pt = Inst;
5245 inserted = true;
5246 Changed = true;
5247 break;
5248 }
5249 if (!getDT(F).dominates(Pt, Inst))
5250 // Give up if we need to merge in a common dominator as the
5251 // experiments show it is not profitable.
5252 continue;
5253 Inst->replaceAllUsesWith(Pt);
5254 RemovedInsts.insert(Inst);
5255 Inst->removeFromParent();
5256 inserted = true;
5257 Changed = true;
5258 break;
5259 }
5260 if (!inserted)
5261 CurPts.push_back(Inst);
5262 }
5263 }
5264 return Changed;
5265}
5266
5267// Spliting large data structures so that the GEPs accessing them can have
5268// smaller offsets so that they can be sunk to the same blocks as their users.
5269// For example, a large struct starting from %base is splitted into two parts
5270// where the second part starts from %new_base.
5271//
5272// Before:
5273// BB0:
5274// %base =
5275//
5276// BB1:
5277// %gep0 = gep %base, off0
5278// %gep1 = gep %base, off1
5279// %gep2 = gep %base, off2
5280//
5281// BB2:
5282// %load1 = load %gep0
5283// %load2 = load %gep1
5284// %load3 = load %gep2
5285//
5286// After:
5287// BB0:
5288// %base =
5289// %new_base = gep %base, off0
5290//
5291// BB1:
5292// %new_gep0 = %new_base
5293// %new_gep1 = gep %new_base, off1 - off0
5294// %new_gep2 = gep %new_base, off2 - off0
5295//
5296// BB2:
5297// %load1 = load i32, i32* %new_gep0
5298// %load2 = load i32, i32* %new_gep1
5299// %load3 = load i32, i32* %new_gep2
5300//
5301// %new_gep1 and %new_gep2 can be sunk to BB2 now after the splitting because
5302// their offsets are smaller enough to fit into the addressing mode.
5303bool CodeGenPrepare::splitLargeGEPOffsets() {
5304 bool Changed = false;
5305 for (auto &Entry : LargeOffsetGEPMap) {
5306 Value *OldBase = Entry.first;
5307 SmallVectorImpl<std::pair<AssertingVH<GetElementPtrInst>, int64_t>>
5308 &LargeOffsetGEPs = Entry.second;
5309 auto compareGEPOffset =
5310 [&](const std::pair<GetElementPtrInst *, int64_t> &LHS,
5311 const std::pair<GetElementPtrInst *, int64_t> &RHS) {
5312 if (LHS.first == RHS.first)
5313 return false;
5314 if (LHS.second != RHS.second)
5315 return LHS.second < RHS.second;
5316 return LargeOffsetGEPID[LHS.first] < LargeOffsetGEPID[RHS.first];
5317 };
5318 // Sorting all the GEPs of the same data structures based on the offsets.
5319 llvm::sort(LargeOffsetGEPs, compareGEPOffset);
5320 LargeOffsetGEPs.erase(
5321 std::unique(LargeOffsetGEPs.begin(), LargeOffsetGEPs.end()),
5322 LargeOffsetGEPs.end());
5323 // Skip if all the GEPs have the same offsets.
5324 if (LargeOffsetGEPs.front().second == LargeOffsetGEPs.back().second)
5325 continue;
5326 GetElementPtrInst *BaseGEP = LargeOffsetGEPs.begin()->first;
5327 int64_t BaseOffset = LargeOffsetGEPs.begin()->second;
5328 Value *NewBaseGEP = nullptr;
5329
5330 auto LargeOffsetGEP = LargeOffsetGEPs.begin();
5331 while (LargeOffsetGEP != LargeOffsetGEPs.end()) {
5332 GetElementPtrInst *GEP = LargeOffsetGEP->first;
5333 int64_t Offset = LargeOffsetGEP->second;
5334 if (Offset != BaseOffset) {
5335 TargetLowering::AddrMode AddrMode;
5336 AddrMode.BaseOffs = Offset - BaseOffset;
5337 // The result type of the GEP might not be the type of the memory
5338 // access.
5339 if (!TLI->isLegalAddressingMode(*DL, AddrMode,
5340 GEP->getResultElementType(),
5341 GEP->getAddressSpace())) {
5342 // We need to create a new base if the offset to the current base is
5343 // too large to fit into the addressing mode. So, a very large struct
5344 // may be splitted into several parts.
5345 BaseGEP = GEP;
5346 BaseOffset = Offset;
5347 NewBaseGEP = nullptr;
5348 }
5349 }
5350
5351 // Generate a new GEP to replace the current one.
5352 LLVMContext &Ctx = GEP->getContext();
5353 Type *IntPtrTy = DL->getIntPtrType(GEP->getType());
5354 Type *I8PtrTy =
5355 Type::getInt8PtrTy(Ctx, GEP->getType()->getPointerAddressSpace());
5356 Type *I8Ty = Type::getInt8Ty(Ctx);
5357
5358 if (!NewBaseGEP) {
5359 // Create a new base if we don't have one yet. Find the insertion
5360 // pointer for the new base first.
5361 BasicBlock::iterator NewBaseInsertPt;
5362 BasicBlock *NewBaseInsertBB;
5363 if (auto *BaseI = dyn_cast<Instruction>(OldBase)) {
5364 // If the base of the struct is an instruction, the new base will be
5365 // inserted close to it.
5366 NewBaseInsertBB = BaseI->getParent();
5367 if (isa<PHINode>(BaseI))
5368 NewBaseInsertPt = NewBaseInsertBB->getFirstInsertionPt();
5369 else if (InvokeInst *Invoke = dyn_cast<InvokeInst>(BaseI)) {
5370 NewBaseInsertBB =
5371 SplitEdge(NewBaseInsertBB, Invoke->getNormalDest());
5372 NewBaseInsertPt = NewBaseInsertBB->getFirstInsertionPt();
5373 } else
5374 NewBaseInsertPt = std::next(BaseI->getIterator());
5375 } else {
5376 // If the current base is an argument or global value, the new base
5377 // will be inserted to the entry block.
5378 NewBaseInsertBB = &BaseGEP->getFunction()->getEntryBlock();
5379 NewBaseInsertPt = NewBaseInsertBB->getFirstInsertionPt();
5380 }
5381 IRBuilder<> NewBaseBuilder(NewBaseInsertBB, NewBaseInsertPt);
5382 // Create a new base.
5383 Value *BaseIndex = ConstantInt::get(IntPtrTy, BaseOffset);
5384 NewBaseGEP = OldBase;
5385 if (NewBaseGEP->getType() != I8PtrTy)
5386 NewBaseGEP = NewBaseBuilder.CreatePointerCast(NewBaseGEP, I8PtrTy);
5387 NewBaseGEP =
5388 NewBaseBuilder.CreateGEP(I8Ty, NewBaseGEP, BaseIndex, "splitgep");
5389 NewGEPBases.insert(NewBaseGEP);
5390 }
5391
5392 IRBuilder<> Builder(GEP);
5393 Value *NewGEP = NewBaseGEP;
5394 if (Offset == BaseOffset) {
5395 if (GEP->getType() != I8PtrTy)
5396 NewGEP = Builder.CreatePointerCast(NewGEP, GEP->getType());
5397 } else {
5398 // Calculate the new offset for the new GEP.
5399 Value *Index = ConstantInt::get(IntPtrTy, Offset - BaseOffset);
5400 NewGEP = Builder.CreateGEP(I8Ty, NewBaseGEP, Index);
5401
5402 if (GEP->getType() != I8PtrTy)
5403 NewGEP = Builder.CreatePointerCast(NewGEP, GEP->getType());
5404 }
5405 GEP->replaceAllUsesWith(NewGEP);
5406 LargeOffsetGEPID.erase(GEP);
5407 LargeOffsetGEP = LargeOffsetGEPs.erase(LargeOffsetGEP);
5408 GEP->eraseFromParent();
5409 Changed = true;
5410 }
5411 }
5412 return Changed;
5413}
5414
5415/// Return true, if an ext(load) can be formed from an extension in
5416/// \p MovedExts.
5417bool CodeGenPrepare::canFormExtLd(
5418 const SmallVectorImpl<Instruction *> &MovedExts, LoadInst *&LI,
5419 Instruction *&Inst, bool HasPromoted) {
5420 for (auto *MovedExtInst : MovedExts) {
5421 if (isa<LoadInst>(MovedExtInst->getOperand(0))) {
5422 LI = cast<LoadInst>(MovedExtInst->getOperand(0));
5423 Inst = MovedExtInst;
5424 break;
5425 }
5426 }
5427 if (!LI)
5428 return false;
5429
5430 // If they're already in the same block, there's nothing to do.
5431 // Make the cheap checks first if we did not promote.
5432 // If we promoted, we need to check if it is indeed profitable.
5433 if (!HasPromoted && LI->getParent() == Inst->getParent())
5434 return false;
5435
5436 return TLI->isExtLoad(LI, Inst, *DL);
5437}
5438
5439/// Move a zext or sext fed by a load into the same basic block as the load,
5440/// unless conditions are unfavorable. This allows SelectionDAG to fold the
5441/// extend into the load.
5442///
5443/// E.g.,
5444/// \code
5445/// %ld = load i32* %addr
5446/// %add = add nuw i32 %ld, 4
5447/// %zext = zext i32 %add to i64
5448// \endcode
5449/// =>
5450/// \code
5451/// %ld = load i32* %addr
5452/// %zext = zext i32 %ld to i64
5453/// %add = add nuw i64 %zext, 4
5454/// \encode
5455/// Note that the promotion in %add to i64 is done in tryToPromoteExts(), which
5456/// allow us to match zext(load i32*) to i64.
5457///
5458/// Also, try to promote the computations used to obtain a sign extended
5459/// value used into memory accesses.
5460/// E.g.,
5461/// \code
5462/// a = add nsw i32 b, 3
5463/// d = sext i32 a to i64
5464/// e = getelementptr ..., i64 d
5465/// \endcode
5466/// =>
5467/// \code
5468/// f = sext i32 b to i64
5469/// a = add nsw i64 f, 3
5470/// e = getelementptr ..., i64 a
5471/// \endcode
5472///
5473/// \p Inst[in/out] the extension may be modified during the process if some
5474/// promotions apply.
5475bool CodeGenPrepare::optimizeExt(Instruction *&Inst) {
5476 // ExtLoad formation and address type promotion infrastructure requires TLI to
5477 // be effective.
5478 if (!TLI)
5479 return false;
5480
5481 bool AllowPromotionWithoutCommonHeader = false;
5482 /// See if it is an interesting sext operations for the address type
5483 /// promotion before trying to promote it, e.g., the ones with the right
5484 /// type and used in memory accesses.
5485 bool ATPConsiderable = TTI->shouldConsiderAddressTypePromotion(
5486 *Inst, AllowPromotionWithoutCommonHeader);
5487 TypePromotionTransaction TPT(RemovedInsts);
5488 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
5489 TPT.getRestorationPoint();
5490 SmallVector<Instruction *, 1> Exts;
5491 SmallVector<Instruction *, 2> SpeculativelyMovedExts;
5492 Exts.push_back(Inst);
5493
5494 bool HasPromoted = tryToPromoteExts(TPT, Exts, SpeculativelyMovedExts);
5495
5496 // Look for a load being extended.
5497 LoadInst *LI = nullptr;
5498 Instruction *ExtFedByLoad;
5499
5500 // Try to promote a chain of computation if it allows to form an extended
5501 // load.
5502 if (canFormExtLd(SpeculativelyMovedExts, LI, ExtFedByLoad, HasPromoted)) {
5503 assert(LI && ExtFedByLoad && "Expect a valid load and extension")((LI && ExtFedByLoad && "Expect a valid load and extension"
) ? static_cast<void> (0) : __assert_fail ("LI && ExtFedByLoad && \"Expect a valid load and extension\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 5503, __PRETTY_FUNCTION__))
;
5504 TPT.commit();
5505 // Move the extend into the same block as the load
5506 ExtFedByLoad->moveAfter(LI);
5507 // CGP does not check if the zext would be speculatively executed when moved
5508 // to the same basic block as the load. Preserving its original location
5509 // would pessimize the debugging experience, as well as negatively impact
5510 // the quality of sample pgo. We don't want to use "line 0" as that has a
5511 // size cost in the line-table section and logically the zext can be seen as
5512 // part of the load. Therefore we conservatively reuse the same debug
5513 // location for the load and the zext.
5514 ExtFedByLoad->setDebugLoc(LI->getDebugLoc());
5515 ++NumExtsMoved;
5516 Inst = ExtFedByLoad;
5517 return true;
5518 }
5519
5520 // Continue promoting SExts if known as considerable depending on targets.
5521 if (ATPConsiderable &&
5522 performAddressTypePromotion(Inst, AllowPromotionWithoutCommonHeader,
5523 HasPromoted, TPT, SpeculativelyMovedExts))
5524 return true;
5525
5526 TPT.rollback(LastKnownGood);
5527 return false;
5528}
5529
5530// Perform address type promotion if doing so is profitable.
5531// If AllowPromotionWithoutCommonHeader == false, we should find other sext
5532// instructions that sign extended the same initial value. However, if
5533// AllowPromotionWithoutCommonHeader == true, we expect promoting the
5534// extension is just profitable.
5535bool CodeGenPrepare::performAddressTypePromotion(
5536 Instruction *&Inst, bool AllowPromotionWithoutCommonHeader,
5537 bool HasPromoted, TypePromotionTransaction &TPT,
5538 SmallVectorImpl<Instruction *> &SpeculativelyMovedExts) {
5539 bool Promoted = false;
5540 SmallPtrSet<Instruction *, 1> UnhandledExts;
5541 bool AllSeenFirst = true;
5542 for (auto I : SpeculativelyMovedExts) {
5543 Value *HeadOfChain = I->getOperand(0);
5544 DenseMap<Value *, Instruction *>::iterator AlreadySeen =
5545 SeenChainsForSExt.find(HeadOfChain);
5546 // If there is an unhandled SExt which has the same header, try to promote
5547 // it as well.
5548 if (AlreadySeen != SeenChainsForSExt.end()) {
5549 if (AlreadySeen->second != nullptr)
5550 UnhandledExts.insert(AlreadySeen->second);
5551 AllSeenFirst = false;
5552 }
5553 }
5554
5555 if (!AllSeenFirst || (AllowPromotionWithoutCommonHeader &&
5556 SpeculativelyMovedExts.size() == 1)) {
5557 TPT.commit();
5558 if (HasPromoted)
5559 Promoted = true;
5560 for (auto I : SpeculativelyMovedExts) {
5561 Value *HeadOfChain = I->getOperand(0);
5562 SeenChainsForSExt[HeadOfChain] = nullptr;
5563 ValToSExtendedUses[HeadOfChain].push_back(I);
5564 }
5565 // Update Inst as promotion happen.
5566 Inst = SpeculativelyMovedExts.pop_back_val();
5567 } else {
5568 // This is the first chain visited from the header, keep the current chain
5569 // as unhandled. Defer to promote this until we encounter another SExt
5570 // chain derived from the same header.
5571 for (auto I : SpeculativelyMovedExts) {
5572 Value *HeadOfChain = I->getOperand(0);
5573 SeenChainsForSExt[HeadOfChain] = Inst;
5574 }
5575 return false;
5576 }
5577
5578 if (!AllSeenFirst && !UnhandledExts.empty())
5579 for (auto VisitedSExt : UnhandledExts) {
5580 if (RemovedInsts.count(VisitedSExt))
5581 continue;
5582 TypePromotionTransaction TPT(RemovedInsts);
5583 SmallVector<Instruction *, 1> Exts;
5584 SmallVector<Instruction *, 2> Chains;
5585 Exts.push_back(VisitedSExt);
5586 bool HasPromoted = tryToPromoteExts(TPT, Exts, Chains);
5587 TPT.commit();
5588 if (HasPromoted)
5589 Promoted = true;
5590 for (auto I : Chains) {
5591 Value *HeadOfChain = I->getOperand(0);
5592 // Mark this as handled.
5593 SeenChainsForSExt[HeadOfChain] = nullptr;
5594 ValToSExtendedUses[HeadOfChain].push_back(I);
5595 }
5596 }
5597 return Promoted;
5598}
5599
5600bool CodeGenPrepare::optimizeExtUses(Instruction *I) {
5601 BasicBlock *DefBB = I->getParent();
5602
5603 // If the result of a {s|z}ext and its source are both live out, rewrite all
5604 // other uses of the source with result of extension.
5605 Value *Src = I->getOperand(0);
5606 if (Src->hasOneUse())
5607 return false;
5608
5609 // Only do this xform if truncating is free.
5610 if (TLI && !TLI->isTruncateFree(I->getType(), Src->getType()))
5611 return false;
5612
5613 // Only safe to perform the optimization if the source is also defined in
5614 // this block.
5615 if (!isa<Instruction>(Src) || DefBB != cast<Instruction>(Src)->getParent())
5616 return false;
5617
5618 bool DefIsLiveOut = false;
5619 for (User *U : I->users()) {
5620 Instruction *UI = cast<Instruction>(U);
5621
5622 // Figure out which BB this ext is used in.
5623 BasicBlock *UserBB = UI->getParent();
5624 if (UserBB == DefBB) continue;
5625 DefIsLiveOut = true;
5626 break;
5627 }
5628 if (!DefIsLiveOut)
5629 return false;
5630
5631 // Make sure none of the uses are PHI nodes.
5632 for (User *U : Src->users()) {
5633 Instruction *UI = cast<Instruction>(U);
5634 BasicBlock *UserBB = UI->getParent();
5635 if (UserBB == DefBB) continue;
5636 // Be conservative. We don't want this xform to end up introducing
5637 // reloads just before load / store instructions.
5638 if (isa<PHINode>(UI) || isa<LoadInst>(UI) || isa<StoreInst>(UI))
5639 return false;
5640 }
5641
5642 // InsertedTruncs - Only insert one trunc in each block once.
5643 DenseMap<BasicBlock*, Instruction*> InsertedTruncs;
5644
5645 bool MadeChange = false;
5646 for (Use &U : Src->uses()) {
5647 Instruction *User = cast<Instruction>(U.getUser());
5648
5649 // Figure out which BB this ext is used in.
5650 BasicBlock *UserBB = User->getParent();
5651 if (UserBB == DefBB) continue;
5652
5653 // Both src and def are live in this block. Rewrite the use.
5654 Instruction *&InsertedTrunc = InsertedTruncs[UserBB];
5655
5656 if (!InsertedTrunc) {
5657 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
5658 assert(InsertPt != UserBB->end())((InsertPt != UserBB->end()) ? static_cast<void> (0)
: __assert_fail ("InsertPt != UserBB->end()", "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 5658, __PRETTY_FUNCTION__))
;
5659 InsertedTrunc = new TruncInst(I, Src->getType(), "", &*InsertPt);
5660 InsertedInsts.insert(InsertedTrunc);
5661 }
5662
5663 // Replace a use of the {s|z}ext source with a use of the result.
5664 U = InsertedTrunc;
5665 ++NumExtUses;
5666 MadeChange = true;
5667 }
5668
5669 return MadeChange;
5670}
5671
5672// Find loads whose uses only use some of the loaded value's bits. Add an "and"
5673// just after the load if the target can fold this into one extload instruction,
5674// with the hope of eliminating some of the other later "and" instructions using
5675// the loaded value. "and"s that are made trivially redundant by the insertion
5676// of the new "and" are removed by this function, while others (e.g. those whose
5677// path from the load goes through a phi) are left for isel to potentially
5678// remove.
5679//
5680// For example:
5681//
5682// b0:
5683// x = load i32
5684// ...
5685// b1:
5686// y = and x, 0xff
5687// z = use y
5688//
5689// becomes:
5690//
5691// b0:
5692// x = load i32
5693// x' = and x, 0xff
5694// ...
5695// b1:
5696// z = use x'
5697//
5698// whereas:
5699//
5700// b0:
5701// x1 = load i32
5702// ...
5703// b1:
5704// x2 = load i32
5705// ...
5706// b2:
5707// x = phi x1, x2
5708// y = and x, 0xff
5709//
5710// becomes (after a call to optimizeLoadExt for each load):
5711//
5712// b0:
5713// x1 = load i32
5714// x1' = and x1, 0xff
5715// ...
5716// b1:
5717// x2 = load i32
5718// x2' = and x2, 0xff
5719// ...
5720// b2:
5721// x = phi x1', x2'
5722// y = and x, 0xff
5723bool CodeGenPrepare::optimizeLoadExt(LoadInst *Load) {
5724 if (!Load->isSimple() || !Load->getType()->isIntOrPtrTy())
5725 return false;
5726
5727 // Skip loads we've already transformed.
5728 if (Load->hasOneUse() &&
5729 InsertedInsts.count(cast<Instruction>(*Load->user_begin())))
5730 return false;
5731
5732 // Look at all uses of Load, looking through phis, to determine how many bits
5733 // of the loaded value are needed.
5734 SmallVector<Instruction *, 8> WorkList;
5735 SmallPtrSet<Instruction *, 16> Visited;
5736 SmallVector<Instruction *, 8> AndsToMaybeRemove;
5737 for (auto *U : Load->users())
5738 WorkList.push_back(cast<Instruction>(U));
5739
5740 EVT LoadResultVT = TLI->getValueType(*DL, Load->getType());
5741 unsigned BitWidth = LoadResultVT.getSizeInBits();
5742 APInt DemandBits(BitWidth, 0);
5743 APInt WidestAndBits(BitWidth, 0);
5744
5745 while (!WorkList.empty()) {
5746 Instruction *I = WorkList.back();
5747 WorkList.pop_back();
5748
5749 // Break use-def graph loops.
5750 if (!Visited.insert(I).second)
5751 continue;
5752
5753 // For a PHI node, push all of its users.
5754 if (auto *Phi = dyn_cast<PHINode>(I)) {
5755 for (auto *U : Phi->users())
5756 WorkList.push_back(cast<Instruction>(U));
5757 continue;
5758 }
5759
5760 switch (I->getOpcode()) {
5761 case Instruction::And: {
5762 auto *AndC = dyn_cast<ConstantInt>(I->getOperand(1));
5763 if (!AndC)
5764 return false;
5765 APInt AndBits = AndC->getValue();
5766 DemandBits |= AndBits;
5767 // Keep track of the widest and mask we see.
5768 if (AndBits.ugt(WidestAndBits))
5769 WidestAndBits = AndBits;
5770 if (AndBits == WidestAndBits && I->getOperand(0) == Load)
5771 AndsToMaybeRemove.push_back(I);
5772 break;
5773 }
5774
5775 case Instruction::Shl: {
5776 auto *ShlC = dyn_cast<ConstantInt>(I->getOperand(1));
5777 if (!ShlC)
5778 return false;
5779 uint64_t ShiftAmt = ShlC->getLimitedValue(BitWidth - 1);
5780 DemandBits.setLowBits(BitWidth - ShiftAmt);
5781 break;
5782 }
5783
5784 case Instruction::Trunc: {
5785 EVT TruncVT = TLI->getValueType(*DL, I->getType());
5786 unsigned TruncBitWidth = TruncVT.getSizeInBits();
5787 DemandBits.setLowBits(TruncBitWidth);
5788 break;
5789 }
5790
5791 default:
5792 return false;
5793 }
5794 }
5795
5796 uint32_t ActiveBits = DemandBits.getActiveBits();
5797 // Avoid hoisting (and (load x) 1) since it is unlikely to be folded by the
5798 // target even if isLoadExtLegal says an i1 EXTLOAD is valid. For example,
5799 // for the AArch64 target isLoadExtLegal(ZEXTLOAD, i32, i1) returns true, but
5800 // (and (load x) 1) is not matched as a single instruction, rather as a LDR
5801 // followed by an AND.
5802 // TODO: Look into removing this restriction by fixing backends to either
5803 // return false for isLoadExtLegal for i1 or have them select this pattern to
5804 // a single instruction.
5805 //
5806 // Also avoid hoisting if we didn't see any ands with the exact DemandBits
5807 // mask, since these are the only ands that will be removed by isel.
5808 if (ActiveBits <= 1 || !DemandBits.isMask(ActiveBits) ||
5809 WidestAndBits != DemandBits)
5810 return false;
5811
5812 LLVMContext &Ctx = Load->getType()->getContext();
5813 Type *TruncTy = Type::getIntNTy(Ctx, ActiveBits);
5814 EVT TruncVT = TLI->getValueType(*DL, TruncTy);
5815
5816 // Reject cases that won't be matched as extloads.
5817 if (!LoadResultVT.bitsGT(TruncVT) || !TruncVT.isRound() ||
5818 !TLI->isLoadExtLegal(ISD::ZEXTLOAD, LoadResultVT, TruncVT))
5819 return false;
5820
5821 IRBuilder<> Builder(Load->getNextNode());
5822 auto *NewAnd = dyn_cast<Instruction>(
5823 Builder.CreateAnd(Load, ConstantInt::get(Ctx, DemandBits)));
5824 // Mark this instruction as "inserted by CGP", so that other
5825 // optimizations don't touch it.
5826 InsertedInsts.insert(NewAnd);
5827
5828 // Replace all uses of load with new and (except for the use of load in the
5829 // new and itself).
5830 Load->replaceAllUsesWith(NewAnd);
5831 NewAnd->setOperand(0, Load);
5832
5833 // Remove any and instructions that are now redundant.
5834 for (auto *And : AndsToMaybeRemove)
5835 // Check that the and mask is the same as the one we decided to put on the
5836 // new and.
5837 if (cast<ConstantInt>(And->getOperand(1))->getValue() == DemandBits) {
5838 And->replaceAllUsesWith(NewAnd);
5839 if (&*CurInstIterator == And)
5840 CurInstIterator = std::next(And->getIterator());
5841 And->eraseFromParent();
5842 ++NumAndUses;
5843 }
5844
5845 ++NumAndsAdded;
5846 return true;
5847}
5848
5849/// Check if V (an operand of a select instruction) is an expensive instruction
5850/// that is only used once.
5851static bool sinkSelectOperand(const TargetTransformInfo *TTI, Value *V) {
5852 auto *I = dyn_cast<Instruction>(V);
5853 // If it's safe to speculatively execute, then it should not have side
5854 // effects; therefore, it's safe to sink and possibly *not* execute.
5855 return I && I->hasOneUse() && isSafeToSpeculativelyExecute(I) &&
5856 TTI->getUserCost(I) >= TargetTransformInfo::TCC_Expensive;
5857}
5858
5859/// Returns true if a SelectInst should be turned into an explicit branch.
5860static bool isFormingBranchFromSelectProfitable(const TargetTransformInfo *TTI,
5861 const TargetLowering *TLI,
5862 SelectInst *SI) {
5863 // If even a predictable select is cheap, then a branch can't be cheaper.
5864 if (!TLI->isPredictableSelectExpensive())
5865 return false;
5866
5867 // FIXME: This should use the same heuristics as IfConversion to determine
5868 // whether a select is better represented as a branch.
5869
5870 // If metadata tells us that the select condition is obviously predictable,
5871 // then we want to replace the select with a branch.
5872 uint64_t TrueWeight, FalseWeight;
5873 if (SI->extractProfMetadata(TrueWeight, FalseWeight)) {
5874 uint64_t Max = std::max(TrueWeight, FalseWeight);
5875 uint64_t Sum = TrueWeight + FalseWeight;
5876 if (Sum != 0) {
5877 auto Probability = BranchProbability::getBranchProbability(Max, Sum);
5878 if (Probability > TLI->getPredictableBranchThreshold())
5879 return true;
5880 }
5881 }
5882
5883 CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition());
5884
5885 // If a branch is predictable, an out-of-order CPU can avoid blocking on its
5886 // comparison condition. If the compare has more than one use, there's
5887 // probably another cmov or setcc around, so it's not worth emitting a branch.
5888 if (!Cmp || !Cmp->hasOneUse())
5889 return false;
5890
5891 // If either operand of the select is expensive and only needed on one side
5892 // of the select, we should form a branch.
5893 if (sinkSelectOperand(TTI, SI->getTrueValue()) ||
5894 sinkSelectOperand(TTI, SI->getFalseValue()))
5895 return true;
5896
5897 return false;
5898}
5899
5900/// If \p isTrue is true, return the true value of \p SI, otherwise return
5901/// false value of \p SI. If the true/false value of \p SI is defined by any
5902/// select instructions in \p Selects, look through the defining select
5903/// instruction until the true/false value is not defined in \p Selects.
5904static Value *getTrueOrFalseValue(
5905 SelectInst *SI, bool isTrue,
5906 const SmallPtrSet<const Instruction *, 2> &Selects) {
5907 Value *V;
44
'V' declared without an initial value
5908
5909 for (SelectInst *DefSI = SI; DefSI != nullptr && Selects.count(DefSI);
45
Loop condition is false. Execution continues on line 5915
5910 DefSI = dyn_cast<SelectInst>(V)) {
5911 assert(DefSI->getCondition() == SI->getCondition() &&((DefSI->getCondition() == SI->getCondition() &&
"The condition of DefSI does not match with SI") ? static_cast
<void> (0) : __assert_fail ("DefSI->getCondition() == SI->getCondition() && \"The condition of DefSI does not match with SI\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 5912, __PRETTY_FUNCTION__))
5912 "The condition of DefSI does not match with SI")((DefSI->getCondition() == SI->getCondition() &&
"The condition of DefSI does not match with SI") ? static_cast
<void> (0) : __assert_fail ("DefSI->getCondition() == SI->getCondition() && \"The condition of DefSI does not match with SI\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 5912, __PRETTY_FUNCTION__))
;
5913 V = (isTrue ? DefSI->getTrueValue() : DefSI->getFalseValue());
5914 }
5915 return V;
46
Undefined or garbage value returned to caller
5916}
5917
5918/// If we have a SelectInst that will likely profit from branch prediction,
5919/// turn it into a branch.
5920bool CodeGenPrepare::optimizeSelectInst(SelectInst *SI) {
5921 // If branch conversion isn't desirable, exit early.
5922 if (DisableSelectToBranch || OptSize || !TLI)
28
Assuming the condition is false
29
Assuming the condition is false
30
Taking false branch
5923 return false;
5924
5925 // Find all consecutive select instructions that share the same condition.
5926 SmallVector<SelectInst *, 2> ASI;
5927 ASI.push_back(SI);
5928 for (BasicBlock::iterator It = ++BasicBlock::iterator(SI);
31
Loop condition is false. Execution continues on line 5938
5929 It != SI->getParent()->end(); ++It) {
5930 SelectInst *I = dyn_cast<SelectInst>(&*It);
5931 if (I && SI->getCondition() == I->getCondition()) {
5932 ASI.push_back(I);
5933 } else {
5934 break;
5935 }
5936 }
5937
5938 SelectInst *LastSI = ASI.back();
5939 // Increment the current iterator to skip all the rest of select instructions
5940 // because they will be either "not lowered" or "all lowered" to branch.
5941 CurInstIterator = std::next(LastSI->getIterator());
5942
5943 bool VectorCond = !SI->getCondition()->getType()->isIntegerTy(1);
32
Assuming the condition is false
5944
5945 // Can we convert the 'select' to CF ?
5946 if (VectorCond || SI->getMetadata(LLVMContext::MD_unpredictable))
33
Assuming the condition is false
34
Taking false branch
5947 return false;
5948
5949 TargetLowering::SelectSupportKind SelectKind;
5950 if (VectorCond)
35
Taking false branch
5951 SelectKind = TargetLowering::VectorMaskSelect;
5952 else if (SI->getType()->isVectorTy())
36
Taking false branch
5953 SelectKind = TargetLowering::ScalarCondVectorVal;
5954 else
5955 SelectKind = TargetLowering::ScalarValSelect;
5956
5957 if (TLI->isSelectSupported(SelectKind) &&
37
Assuming the condition is false
5958 !isFormingBranchFromSelectProfitable(TTI, TLI, SI))
5959 return false;
5960
5961 // The DominatorTree needs to be rebuilt by any consumers after this
5962 // transformation. We simply reset here rather than setting the ModifiedDT
5963 // flag to avoid restarting the function walk in runOnFunction for each
5964 // select optimized.
5965 DT.reset();
5966
5967 // Transform a sequence like this:
5968 // start:
5969 // %cmp = cmp uge i32 %a, %b
5970 // %sel = select i1 %cmp, i32 %c, i32 %d
5971 //
5972 // Into:
5973 // start:
5974 // %cmp = cmp uge i32 %a, %b
5975 // br i1 %cmp, label %select.true, label %select.false
5976 // select.true:
5977 // br label %select.end
5978 // select.false:
5979 // br label %select.end
5980 // select.end:
5981 // %sel = phi i32 [ %c, %select.true ], [ %d, %select.false ]
5982 //
5983 // In addition, we may sink instructions that produce %c or %d from
5984 // the entry block into the destination(s) of the new branch.
5985 // If the true or false blocks do not contain a sunken instruction, that
5986 // block and its branch may be optimized away. In that case, one side of the
5987 // first branch will point directly to select.end, and the corresponding PHI
5988 // predecessor block will be the start block.
5989
5990 // First, we split the block containing the select into 2 blocks.
5991 BasicBlock *StartBlock = SI->getParent();
5992 BasicBlock::iterator SplitPt = ++(BasicBlock::iterator(LastSI));
5993 BasicBlock *EndBlock = StartBlock->splitBasicBlock(SplitPt, "select.end");
5994
5995 // Delete the unconditional branch that was just created by the split.
5996 StartBlock->getTerminator()->eraseFromParent();
5997
5998 // These are the new basic blocks for the conditional branch.
5999 // At least one will become an actual new basic block.
6000 BasicBlock *TrueBlock = nullptr;
6001 BasicBlock *FalseBlock = nullptr;
6002 BranchInst *TrueBranch = nullptr;
6003 BranchInst *FalseBranch = nullptr;
6004
6005 // Sink expensive instructions into the conditional blocks to avoid executing
6006 // them speculatively.
6007 for (SelectInst *SI : ASI) {
38
Assuming '__begin1' is equal to '__end1'
6008 if (sinkSelectOperand(TTI, SI->getTrueValue())) {
6009 if (TrueBlock == nullptr) {
6010 TrueBlock = BasicBlock::Create(SI->getContext(), "select.true.sink",
6011 EndBlock->getParent(), EndBlock);
6012 TrueBranch = BranchInst::Create(EndBlock, TrueBlock);
6013 TrueBranch->setDebugLoc(SI->getDebugLoc());
6014 }
6015 auto *TrueInst = cast<Instruction>(SI->getTrueValue());
6016 TrueInst->moveBefore(TrueBranch);
6017 }
6018 if (sinkSelectOperand(TTI, SI->getFalseValue())) {
6019 if (FalseBlock == nullptr) {
6020 FalseBlock = BasicBlock::Create(SI->getContext(), "select.false.sink",
6021 EndBlock->getParent(), EndBlock);
6022 FalseBranch = BranchInst::Create(EndBlock, FalseBlock);
6023 FalseBranch->setDebugLoc(SI->getDebugLoc());
6024 }
6025 auto *FalseInst = cast<Instruction>(SI->getFalseValue());
6026 FalseInst->moveBefore(FalseBranch);
6027 }
6028 }
6029
6030 // If there was nothing to sink, then arbitrarily choose the 'false' side
6031 // for a new input value to the PHI.
6032 if (TrueBlock == FalseBlock) {
39
Taking true branch
6033 assert(TrueBlock == nullptr &&((TrueBlock == nullptr && "Unexpected basic block transform while optimizing select"
) ? static_cast<void> (0) : __assert_fail ("TrueBlock == nullptr && \"Unexpected basic block transform while optimizing select\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 6034, __PRETTY_FUNCTION__))
40
'?' condition is true
6034 "Unexpected basic block transform while optimizing select")((TrueBlock == nullptr && "Unexpected basic block transform while optimizing select"
) ? static_cast<void> (0) : __assert_fail ("TrueBlock == nullptr && \"Unexpected basic block transform while optimizing select\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 6034, __PRETTY_FUNCTION__))
;
6035
6036 FalseBlock = BasicBlock::Create(SI->getContext(), "select.false",
6037 EndBlock->getParent(), EndBlock);
6038 auto *FalseBranch = BranchInst::Create(EndBlock, FalseBlock);
6039 FalseBranch->setDebugLoc(SI->getDebugLoc());
6040 }
6041
6042 // Insert the real conditional branch based on the original condition.
6043 // If we did not create a new block for one of the 'true' or 'false' paths
6044 // of the condition, it means that side of the branch goes to the end block
6045 // directly and the path originates from the start block from the point of
6046 // view of the new PHI.
6047 BasicBlock *TT, *FT;
6048 if (TrueBlock == nullptr) {
41
Taking true branch
6049 TT = EndBlock;
6050 FT = FalseBlock;
6051 TrueBlock = StartBlock;
6052 } else if (FalseBlock == nullptr) {
6053 TT = TrueBlock;
6054 FT = EndBlock;
6055 FalseBlock = StartBlock;
6056 } else {
6057 TT = TrueBlock;
6058 FT = FalseBlock;
6059 }
6060 IRBuilder<>(SI).CreateCondBr(SI->getCondition(), TT, FT, SI);
6061
6062 SmallPtrSet<const Instruction *, 2> INS;
6063 INS.insert(ASI.begin(), ASI.end());
6064 // Use reverse iterator because later select may use the value of the
6065 // earlier select, and we need to propagate value through earlier select
6066 // to get the PHI operand.
6067 for (auto It = ASI.rbegin(); It != ASI.rend(); ++It) {
42
Loop condition is true. Entering loop body
6068 SelectInst *SI = *It;
6069 // The select itself is replaced with a PHI Node.
6070 PHINode *PN = PHINode::Create(SI->getType(), 2, "", &EndBlock->front());
6071 PN->takeName(SI);
6072 PN->addIncoming(getTrueOrFalseValue(SI, true, INS), TrueBlock);
43
Calling 'getTrueOrFalseValue'
6073 PN->addIncoming(getTrueOrFalseValue(SI, false, INS), FalseBlock);
6074 PN->setDebugLoc(SI->getDebugLoc());
6075
6076 SI->replaceAllUsesWith(PN);
6077 SI->eraseFromParent();
6078 INS.erase(SI);
6079 ++NumSelectsExpanded;
6080 }
6081
6082 // Instruct OptimizeBlock to skip to the next block.
6083 CurInstIterator = StartBlock->end();
6084 return true;
6085}
6086
6087static bool isBroadcastShuffle(ShuffleVectorInst *SVI) {
6088 SmallVector<int, 16> Mask(SVI->getShuffleMask());
6089 int SplatElem = -1;
6090 for (unsigned i = 0; i < Mask.size(); ++i) {
6091 if (SplatElem != -1 && Mask[i] != -1 && Mask[i] != SplatElem)
6092 return false;
6093 SplatElem = Mask[i];
6094 }
6095
6096 return true;
6097}
6098
6099/// Some targets have expensive vector shifts if the lanes aren't all the same
6100/// (e.g. x86 only introduced "vpsllvd" and friends with AVX2). In these cases
6101/// it's often worth sinking a shufflevector splat down to its use so that
6102/// codegen can spot all lanes are identical.
6103bool CodeGenPrepare::optimizeShuffleVectorInst(ShuffleVectorInst *SVI) {
6104 BasicBlock *DefBB = SVI->getParent();
6105
6106 // Only do this xform if variable vector shifts are particularly expensive.
6107 if (!TLI || !TLI->isVectorShiftByScalarCheap(SVI->getType()))
6108 return false;
6109
6110 // We only expect better codegen by sinking a shuffle if we can recognise a
6111 // constant splat.
6112 if (!isBroadcastShuffle(SVI))
6113 return false;
6114
6115 // InsertedShuffles - Only insert a shuffle in each block once.
6116 DenseMap<BasicBlock*, Instruction*> InsertedShuffles;
6117
6118 bool MadeChange = false;
6119 for (User *U : SVI->users()) {
6120 Instruction *UI = cast<Instruction>(U);
6121
6122 // Figure out which BB this ext is used in.
6123 BasicBlock *UserBB = UI->getParent();
6124 if (UserBB == DefBB) continue;
6125
6126 // For now only apply this when the splat is used by a shift instruction.
6127 if (!UI->isShift()) continue;
6128
6129 // Everything checks out, sink the shuffle if the user's block doesn't
6130 // already have a copy.
6131 Instruction *&InsertedShuffle = InsertedShuffles[UserBB];
6132
6133 if (!InsertedShuffle) {
6134 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
6135 assert(InsertPt != UserBB->end())((InsertPt != UserBB->end()) ? static_cast<void> (0)
: __assert_fail ("InsertPt != UserBB->end()", "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 6135, __PRETTY_FUNCTION__))
;
6136 InsertedShuffle =
6137 new ShuffleVectorInst(SVI->getOperand(0), SVI->getOperand(1),
6138 SVI->getOperand(2), "", &*InsertPt);
6139 }
6140
6141 UI->replaceUsesOfWith(SVI, InsertedShuffle);
6142 MadeChange = true;
6143 }
6144
6145 // If we removed all uses, nuke the shuffle.
6146 if (SVI->use_empty()) {
6147 SVI->eraseFromParent();
6148 MadeChange = true;
6149 }
6150
6151 return MadeChange;
6152}
6153
6154bool CodeGenPrepare::tryToSinkFreeOperands(Instruction *I) {
6155 // If the operands of I can be folded into a target instruction together with
6156 // I, duplicate and sink them.
6157 SmallVector<Use *, 4> OpsToSink;
6158 if (!TLI || !TLI->shouldSinkOperands(I, OpsToSink))
6159 return false;
6160
6161 // OpsToSink can contain multiple uses in a use chain (e.g.
6162 // (%u1 with %u1 = shufflevector), (%u2 with %u2 = zext %u1)). The dominating
6163 // uses must come first, which means they are sunk first, temporarily creating
6164 // invalid IR. This will be fixed once their dominated users are sunk and
6165 // updated.
6166 BasicBlock *TargetBB = I->getParent();
6167 bool Changed = false;
6168 SmallVector<Use *, 4> ToReplace;
6169 for (Use *U : OpsToSink) {
6170 auto *UI = cast<Instruction>(U->get());
6171 if (UI->getParent() == TargetBB || isa<PHINode>(UI))
6172 continue;
6173 ToReplace.push_back(U);
6174 }
6175
6176 SmallPtrSet<Instruction *, 4> MaybeDead;
6177 for (Use *U : ToReplace) {
6178 auto *UI = cast<Instruction>(U->get());
6179 Instruction *NI = UI->clone();
6180 MaybeDead.insert(UI);
6181 LLVM_DEBUG(dbgs() << "Sinking " << *UI << " to user " << *I << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Sinking " << *UI
<< " to user " << *I << "\n"; } } while (false
)
;
6182 NI->insertBefore(I);
6183 InsertedInsts.insert(NI);
6184 U->set(NI);
6185 Changed = true;
6186 }
6187
6188 // Remove instructions that are dead after sinking.
6189 for (auto *I : MaybeDead)
6190 if (!I->hasNUsesOrMore(1))
6191 I->eraseFromParent();
6192
6193 return Changed;
6194}
6195
6196bool CodeGenPrepare::optimizeSwitchInst(SwitchInst *SI) {
6197 if (!TLI || !DL)
6198 return false;
6199
6200 Value *Cond = SI->getCondition();
6201 Type *OldType = Cond->getType();
6202 LLVMContext &Context = Cond->getContext();
6203 MVT RegType = TLI->getRegisterType(Context, TLI->getValueType(*DL, OldType));
6204 unsigned RegWidth = RegType.getSizeInBits();
6205
6206 if (RegWidth <= cast<IntegerType>(OldType)->getBitWidth())
6207 return false;
6208
6209 // If the register width is greater than the type width, expand the condition
6210 // of the switch instruction and each case constant to the width of the
6211 // register. By widening the type of the switch condition, subsequent
6212 // comparisons (for case comparisons) will not need to be extended to the
6213 // preferred register width, so we will potentially eliminate N-1 extends,
6214 // where N is the number of cases in the switch.
6215 auto *NewType = Type::getIntNTy(Context, RegWidth);
6216
6217 // Zero-extend the switch condition and case constants unless the switch
6218 // condition is a function argument that is already being sign-extended.
6219 // In that case, we can avoid an unnecessary mask/extension by sign-extending
6220 // everything instead.
6221 Instruction::CastOps ExtType = Instruction::ZExt;
6222 if (auto *Arg = dyn_cast<Argument>(Cond))
6223 if (Arg->hasSExtAttr())
6224 ExtType = Instruction::SExt;
6225
6226 auto *ExtInst = CastInst::Create(ExtType, Cond, NewType);
6227 ExtInst->insertBefore(SI);
6228 ExtInst->setDebugLoc(SI->getDebugLoc());
6229 SI->setCondition(ExtInst);
6230 for (auto Case : SI->cases()) {
6231 APInt NarrowConst = Case.getCaseValue()->getValue();
6232 APInt WideConst = (ExtType == Instruction::ZExt) ?
6233 NarrowConst.zext(RegWidth) : NarrowConst.sext(RegWidth);
6234 Case.setValue(ConstantInt::get(Context, WideConst));
6235 }
6236
6237 return true;
6238}
6239
6240
6241namespace {
6242
6243/// Helper class to promote a scalar operation to a vector one.
6244/// This class is used to move downward extractelement transition.
6245/// E.g.,
6246/// a = vector_op <2 x i32>
6247/// b = extractelement <2 x i32> a, i32 0
6248/// c = scalar_op b
6249/// store c
6250///
6251/// =>
6252/// a = vector_op <2 x i32>
6253/// c = vector_op a (equivalent to scalar_op on the related lane)
6254/// * d = extractelement <2 x i32> c, i32 0
6255/// * store d
6256/// Assuming both extractelement and store can be combine, we get rid of the
6257/// transition.
6258class VectorPromoteHelper {
6259 /// DataLayout associated with the current module.
6260 const DataLayout &DL;
6261
6262 /// Used to perform some checks on the legality of vector operations.
6263 const TargetLowering &TLI;
6264
6265 /// Used to estimated the cost of the promoted chain.
6266 const TargetTransformInfo &TTI;
6267
6268 /// The transition being moved downwards.
6269 Instruction *Transition;
6270
6271 /// The sequence of instructions to be promoted.
6272 SmallVector<Instruction *, 4> InstsToBePromoted;
6273
6274 /// Cost of combining a store and an extract.
6275 unsigned StoreExtractCombineCost;
6276
6277 /// Instruction that will be combined with the transition.
6278 Instruction *CombineInst = nullptr;
6279
6280 /// The instruction that represents the current end of the transition.
6281 /// Since we are faking the promotion until we reach the end of the chain
6282 /// of computation, we need a way to get the current end of the transition.
6283 Instruction *getEndOfTransition() const {
6284 if (InstsToBePromoted.empty())
6285 return Transition;
6286 return InstsToBePromoted.back();
6287 }
6288
6289 /// Return the index of the original value in the transition.
6290 /// E.g., for "extractelement <2 x i32> c, i32 1" the original value,
6291 /// c, is at index 0.
6292 unsigned getTransitionOriginalValueIdx() const {
6293 assert(isa<ExtractElementInst>(Transition) &&((isa<ExtractElementInst>(Transition) && "Other kind of transitions are not supported yet"
) ? static_cast<void> (0) : __assert_fail ("isa<ExtractElementInst>(Transition) && \"Other kind of transitions are not supported yet\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 6294, __PRETTY_FUNCTION__))
6294 "Other kind of transitions are not supported yet")((isa<ExtractElementInst>(Transition) && "Other kind of transitions are not supported yet"
) ? static_cast<void> (0) : __assert_fail ("isa<ExtractElementInst>(Transition) && \"Other kind of transitions are not supported yet\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 6294, __PRETTY_FUNCTION__))
;
6295 return 0;
6296 }
6297
6298 /// Return the index of the index in the transition.
6299 /// E.g., for "extractelement <2 x i32> c, i32 0" the index
6300 /// is at index 1.
6301 unsigned getTransitionIdx() const {
6302 assert(isa<ExtractElementInst>(Transition) &&((isa<ExtractElementInst>(Transition) && "Other kind of transitions are not supported yet"
) ? static_cast<void> (0) : __assert_fail ("isa<ExtractElementInst>(Transition) && \"Other kind of transitions are not supported yet\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 6303, __PRETTY_FUNCTION__))
6303 "Other kind of transitions are not supported yet")((isa<ExtractElementInst>(Transition) && "Other kind of transitions are not supported yet"
) ? static_cast<void> (0) : __assert_fail ("isa<ExtractElementInst>(Transition) && \"Other kind of transitions are not supported yet\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 6303, __PRETTY_FUNCTION__))
;
6304 return 1;
6305 }
6306
6307 /// Get the type of the transition.
6308 /// This is the type of the original value.
6309 /// E.g., for "extractelement <2 x i32> c, i32 1" the type of the
6310 /// transition is <2 x i32>.
6311 Type *getTransitionType() const {
6312 return Transition->getOperand(getTransitionOriginalValueIdx())->getType();
6313 }
6314
6315 /// Promote \p ToBePromoted by moving \p Def downward through.
6316 /// I.e., we have the following sequence:
6317 /// Def = Transition <ty1> a to <ty2>
6318 /// b = ToBePromoted <ty2> Def, ...
6319 /// =>
6320 /// b = ToBePromoted <ty1> a, ...
6321 /// Def = Transition <ty1> ToBePromoted to <ty2>
6322 void promoteImpl(Instruction *ToBePromoted);
6323
6324 /// Check whether or not it is profitable to promote all the
6325 /// instructions enqueued to be promoted.
6326 bool isProfitableToPromote() {
6327 Value *ValIdx = Transition->getOperand(getTransitionOriginalValueIdx());
6328 unsigned Index = isa<ConstantInt>(ValIdx)
6329 ? cast<ConstantInt>(ValIdx)->getZExtValue()
6330 : -1;
6331 Type *PromotedType = getTransitionType();
6332
6333 StoreInst *ST = cast<StoreInst>(CombineInst);
6334 unsigned AS = ST->getPointerAddressSpace();
6335 unsigned Align = ST->getAlignment();
6336 // Check if this store is supported.
6337 if (!TLI.allowsMisalignedMemoryAccesses(
6338 TLI.getValueType(DL, ST->getValueOperand()->getType()), AS,
6339 Align)) {
6340 // If this is not supported, there is no way we can combine
6341 // the extract with the store.
6342 return false;
6343 }
6344
6345 // The scalar chain of computation has to pay for the transition
6346 // scalar to vector.
6347 // The vector chain has to account for the combining cost.
6348 uint64_t ScalarCost =
6349 TTI.getVectorInstrCost(Transition->getOpcode(), PromotedType, Index);
6350 uint64_t VectorCost = StoreExtractCombineCost;
6351 for (const auto &Inst : InstsToBePromoted) {
6352 // Compute the cost.
6353 // By construction, all instructions being promoted are arithmetic ones.
6354 // Moreover, one argument is a constant that can be viewed as a splat
6355 // constant.
6356 Value *Arg0 = Inst->getOperand(0);
6357 bool IsArg0Constant = isa<UndefValue>(Arg0) || isa<ConstantInt>(Arg0) ||
6358 isa<ConstantFP>(Arg0);
6359 TargetTransformInfo::OperandValueKind Arg0OVK =
6360 IsArg0Constant ? TargetTransformInfo::OK_UniformConstantValue
6361 : TargetTransformInfo::OK_AnyValue;
6362 TargetTransformInfo::OperandValueKind Arg1OVK =
6363 !IsArg0Constant ? TargetTransformInfo::OK_UniformConstantValue
6364 : TargetTransformInfo::OK_AnyValue;
6365 ScalarCost += TTI.getArithmeticInstrCost(
6366 Inst->getOpcode(), Inst->getType(), Arg0OVK, Arg1OVK);
6367 VectorCost += TTI.getArithmeticInstrCost(Inst->getOpcode(), PromotedType,
6368 Arg0OVK, Arg1OVK);
6369 }
6370 LLVM_DEBUG(do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Estimated cost of computation to be promoted:\nScalar: "
<< ScalarCost << "\nVector: " << VectorCost
<< '\n'; } } while (false)
6371 dbgs() << "Estimated cost of computation to be promoted:\nScalar: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Estimated cost of computation to be promoted:\nScalar: "
<< ScalarCost << "\nVector: " << VectorCost
<< '\n'; } } while (false)
6372 << ScalarCost << "\nVector: " << VectorCost << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Estimated cost of computation to be promoted:\nScalar: "
<< ScalarCost << "\nVector: " << VectorCost
<< '\n'; } } while (false)
;
6373 return ScalarCost > VectorCost;
6374 }
6375
6376 /// Generate a constant vector with \p Val with the same
6377 /// number of elements as the transition.
6378 /// \p UseSplat defines whether or not \p Val should be replicated
6379 /// across the whole vector.
6380 /// In other words, if UseSplat == true, we generate <Val, Val, ..., Val>,
6381 /// otherwise we generate a vector with as many undef as possible:
6382 /// <undef, ..., undef, Val, undef, ..., undef> where \p Val is only
6383 /// used at the index of the extract.
6384 Value *getConstantVector(Constant *Val, bool UseSplat) const {
6385 unsigned ExtractIdx = std::numeric_limits<unsigned>::max();
6386 if (!UseSplat) {
6387 // If we cannot determine where the constant must be, we have to
6388 // use a splat constant.
6389 Value *ValExtractIdx = Transition->getOperand(getTransitionIdx());
6390 if (ConstantInt *CstVal = dyn_cast<ConstantInt>(ValExtractIdx))
6391 ExtractIdx = CstVal->getSExtValue();
6392 else
6393 UseSplat = true;
6394 }
6395
6396 unsigned End = getTransitionType()->getVectorNumElements();
6397 if (UseSplat)
6398 return ConstantVector::getSplat(End, Val);
6399
6400 SmallVector<Constant *, 4> ConstVec;
6401 UndefValue *UndefVal = UndefValue::get(Val->getType());
6402 for (unsigned Idx = 0; Idx != End; ++Idx) {
6403 if (Idx == ExtractIdx)
6404 ConstVec.push_back(Val);
6405 else
6406 ConstVec.push_back(UndefVal);
6407 }
6408 return ConstantVector::get(ConstVec);
6409 }
6410
6411 /// Check if promoting to a vector type an operand at \p OperandIdx
6412 /// in \p Use can trigger undefined behavior.
6413 static bool canCauseUndefinedBehavior(const Instruction *Use,
6414 unsigned OperandIdx) {
6415 // This is not safe to introduce undef when the operand is on
6416 // the right hand side of a division-like instruction.
6417 if (OperandIdx != 1)
6418 return false;
6419 switch (Use->getOpcode()) {
6420 default:
6421 return false;
6422 case Instruction::SDiv:
6423 case Instruction::UDiv:
6424 case Instruction::SRem:
6425 case Instruction::URem:
6426 return true;
6427 case Instruction::FDiv:
6428 case Instruction::FRem:
6429 return !Use->hasNoNaNs();
6430 }
6431 llvm_unreachable(nullptr)::llvm::llvm_unreachable_internal(nullptr, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 6431)
;
6432 }
6433
6434public:
6435 VectorPromoteHelper(const DataLayout &DL, const TargetLowering &TLI,
6436 const TargetTransformInfo &TTI, Instruction *Transition,
6437 unsigned CombineCost)
6438 : DL(DL), TLI(TLI), TTI(TTI), Transition(Transition),
6439 StoreExtractCombineCost(CombineCost) {
6440 assert(Transition && "Do not know how to promote null")((Transition && "Do not know how to promote null") ? static_cast
<void> (0) : __assert_fail ("Transition && \"Do not know how to promote null\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 6440, __PRETTY_FUNCTION__))
;
6441 }
6442
6443 /// Check if we can promote \p ToBePromoted to \p Type.
6444 bool canPromote(const Instruction *ToBePromoted) const {
6445 // We could support CastInst too.
6446 return isa<BinaryOperator>(ToBePromoted);
6447 }
6448
6449 /// Check if it is profitable to promote \p ToBePromoted
6450 /// by moving downward the transition through.
6451 bool shouldPromote(const Instruction *ToBePromoted) const {
6452 // Promote only if all the operands can be statically expanded.
6453 // Indeed, we do not want to introduce any new kind of transitions.
6454 for (const Use &U : ToBePromoted->operands()) {
6455 const Value *Val = U.get();
6456 if (Val == getEndOfTransition()) {
6457 // If the use is a division and the transition is on the rhs,
6458 // we cannot promote the operation, otherwise we may create a
6459 // division by zero.
6460 if (canCauseUndefinedBehavior(ToBePromoted, U.getOperandNo()))
6461 return false;
6462 continue;
6463 }
6464 if (!isa<ConstantInt>(Val) && !isa<UndefValue>(Val) &&
6465 !isa<ConstantFP>(Val))
6466 return false;
6467 }
6468 // Check that the resulting operation is legal.
6469 int ISDOpcode = TLI.InstructionOpcodeToISD(ToBePromoted->getOpcode());
6470 if (!ISDOpcode)
6471 return false;
6472 return StressStoreExtract ||
6473 TLI.isOperationLegalOrCustom(
6474 ISDOpcode, TLI.getValueType(DL, getTransitionType(), true));
6475 }
6476
6477 /// Check whether or not \p Use can be combined
6478 /// with the transition.
6479 /// I.e., is it possible to do Use(Transition) => AnotherUse?
6480 bool canCombine(const Instruction *Use) { return isa<StoreInst>(Use); }
6481
6482 /// Record \p ToBePromoted as part of the chain to be promoted.
6483 void enqueueForPromotion(Instruction *ToBePromoted) {
6484 InstsToBePromoted.push_back(ToBePromoted);
6485 }
6486
6487 /// Set the instruction that will be combined with the transition.
6488 void recordCombineInstruction(Instruction *ToBeCombined) {
6489 assert(canCombine(ToBeCombined) && "Unsupported instruction to combine")((canCombine(ToBeCombined) && "Unsupported instruction to combine"
) ? static_cast<void> (0) : __assert_fail ("canCombine(ToBeCombined) && \"Unsupported instruction to combine\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 6489, __PRETTY_FUNCTION__))
;
6490 CombineInst = ToBeCombined;
6491 }
6492
6493 /// Promote all the instructions enqueued for promotion if it is
6494 /// is profitable.
6495 /// \return True if the promotion happened, false otherwise.
6496 bool promote() {
6497 // Check if there is something to promote.
6498 // Right now, if we do not have anything to combine with,
6499 // we assume the promotion is not profitable.
6500 if (InstsToBePromoted.empty() || !CombineInst)
6501 return false;
6502
6503 // Check cost.
6504 if (!StressStoreExtract && !isProfitableToPromote())
6505 return false;
6506
6507 // Promote.
6508 for (auto &ToBePromoted : InstsToBePromoted)
6509 promoteImpl(ToBePromoted);
6510 InstsToBePromoted.clear();
6511 return true;
6512 }
6513};
6514
6515} // end anonymous namespace
6516
6517void VectorPromoteHelper::promoteImpl(Instruction *ToBePromoted) {
6518 // At this point, we know that all the operands of ToBePromoted but Def
6519 // can be statically promoted.
6520 // For Def, we need to use its parameter in ToBePromoted:
6521 // b = ToBePromoted ty1 a
6522 // Def = Transition ty1 b to ty2
6523 // Move the transition down.
6524 // 1. Replace all uses of the promoted operation by the transition.
6525 // = ... b => = ... Def.
6526 assert(ToBePromoted->getType() == Transition->getType() &&((ToBePromoted->getType() == Transition->getType() &&
"The type of the result of the transition does not match " "the final type"
) ? static_cast<void> (0) : __assert_fail ("ToBePromoted->getType() == Transition->getType() && \"The type of the result of the transition does not match \" \"the final type\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 6528, __PRETTY_FUNCTION__))
6527 "The type of the result of the transition does not match "((ToBePromoted->getType() == Transition->getType() &&
"The type of the result of the transition does not match " "the final type"
) ? static_cast<void> (0) : __assert_fail ("ToBePromoted->getType() == Transition->getType() && \"The type of the result of the transition does not match \" \"the final type\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 6528, __PRETTY_FUNCTION__))
6528 "the final type")((ToBePromoted->getType() == Transition->getType() &&
"The type of the result of the transition does not match " "the final type"
) ? static_cast<void> (0) : __assert_fail ("ToBePromoted->getType() == Transition->getType() && \"The type of the result of the transition does not match \" \"the final type\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 6528, __PRETTY_FUNCTION__))
;
6529 ToBePromoted->replaceAllUsesWith(Transition);
6530 // 2. Update the type of the uses.
6531 // b = ToBePromoted ty2 Def => b = ToBePromoted ty1 Def.
6532 Type *TransitionTy = getTransitionType();
6533 ToBePromoted->mutateType(TransitionTy);
6534 // 3. Update all the operands of the promoted operation with promoted
6535 // operands.
6536 // b = ToBePromoted ty1 Def => b = ToBePromoted ty1 a.
6537 for (Use &U : ToBePromoted->operands()) {
6538 Value *Val = U.get();
6539 Value *NewVal = nullptr;
6540 if (Val == Transition)
6541 NewVal = Transition->getOperand(getTransitionOriginalValueIdx());
6542 else if (isa<UndefValue>(Val) || isa<ConstantInt>(Val) ||
6543 isa<ConstantFP>(Val)) {
6544 // Use a splat constant if it is not safe to use undef.
6545 NewVal = getConstantVector(
6546 cast<Constant>(Val),
6547 isa<UndefValue>(Val) ||
6548 canCauseUndefinedBehavior(ToBePromoted, U.getOperandNo()));
6549 } else
6550 llvm_unreachable("Did you modified shouldPromote and forgot to update "::llvm::llvm_unreachable_internal("Did you modified shouldPromote and forgot to update "
"this?", "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 6551)
6551 "this?")::llvm::llvm_unreachable_internal("Did you modified shouldPromote and forgot to update "
"this?", "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 6551)
;
6552 ToBePromoted->setOperand(U.getOperandNo(), NewVal);
6553 }
6554 Transition->moveAfter(ToBePromoted);
6555 Transition->setOperand(getTransitionOriginalValueIdx(), ToBePromoted);
6556}
6557
6558/// Some targets can do store(extractelement) with one instruction.
6559/// Try to push the extractelement towards the stores when the target
6560/// has this feature and this is profitable.
6561bool CodeGenPrepare::optimizeExtractElementInst(Instruction *Inst) {
6562 unsigned CombineCost = std::numeric_limits<unsigned>::max();
6563 if (DisableStoreExtract || !TLI ||
6564 (!StressStoreExtract &&
6565 !TLI->canCombineStoreAndExtract(Inst->getOperand(0)->getType(),
6566 Inst->getOperand(1), CombineCost)))
6567 return false;
6568
6569 // At this point we know that Inst is a vector to scalar transition.
6570 // Try to move it down the def-use chain, until:
6571 // - We can combine the transition with its single use
6572 // => we got rid of the transition.
6573 // - We escape the current basic block
6574 // => we would need to check that we are moving it at a cheaper place and
6575 // we do not do that for now.
6576 BasicBlock *Parent = Inst->getParent();
6577 LLVM_DEBUG(dbgs() << "Found an interesting transition: " << *Inst << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Found an interesting transition: "
<< *Inst << '\n'; } } while (false)
;
6578 VectorPromoteHelper VPH(*DL, *TLI, *TTI, Inst, CombineCost);
6579 // If the transition has more than one use, assume this is not going to be
6580 // beneficial.
6581 while (Inst->hasOneUse()) {
6582 Instruction *ToBePromoted = cast<Instruction>(*Inst->user_begin());
6583 LLVM_DEBUG(dbgs() << "Use: " << *ToBePromoted << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Use: " << *ToBePromoted
<< '\n'; } } while (false)
;
6584
6585 if (ToBePromoted->getParent() != Parent) {
6586 LLVM_DEBUG(dbgs() << "Instruction to promote is in a different block ("do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Instruction to promote is in a different block ("
<< ToBePromoted->getParent()->getName() <<
") than the transition (" << Parent->getName() <<
").\n"; } } while (false)
6587 << ToBePromoted->getParent()->getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Instruction to promote is in a different block ("
<< ToBePromoted->getParent()->getName() <<
") than the transition (" << Parent->getName() <<
").\n"; } } while (false)
6588 << ") than the transition (" << Parent->getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Instruction to promote is in a different block ("
<< ToBePromoted->getParent()->getName() <<
") than the transition (" << Parent->getName() <<
").\n"; } } while (false)
6589 << ").\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Instruction to promote is in a different block ("
<< ToBePromoted->getParent()->getName() <<
") than the transition (" << Parent->getName() <<
").\n"; } } while (false)
;
6590 return false;
6591 }
6592
6593 if (VPH.canCombine(ToBePromoted)) {
6594 LLVM_DEBUG(dbgs() << "Assume " << *Inst << '\n'do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Assume " << *Inst
<< '\n' << "will be combined with: " << *ToBePromoted
<< '\n'; } } while (false)
6595 << "will be combined with: " << *ToBePromoted << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Assume " << *Inst
<< '\n' << "will be combined with: " << *ToBePromoted
<< '\n'; } } while (false)
;
6596 VPH.recordCombineInstruction(ToBePromoted);
6597 bool Changed = VPH.promote();
6598 NumStoreExtractExposed += Changed;
6599 return Changed;
6600 }
6601
6602 LLVM_DEBUG(dbgs() << "Try promoting.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Try promoting.\n"; } }
while (false)
;
6603 if (!VPH.canPromote(ToBePromoted) || !VPH.shouldPromote(ToBePromoted))
6604 return false;
6605
6606 LLVM_DEBUG(dbgs() << "Promoting is possible... Enqueue for promotion!\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Promoting is possible... Enqueue for promotion!\n"
; } } while (false)
;
6607
6608 VPH.enqueueForPromotion(ToBePromoted);
6609 Inst = ToBePromoted;
6610 }
6611 return false;
6612}
6613
6614/// For the instruction sequence of store below, F and I values
6615/// are bundled together as an i64 value before being stored into memory.
6616/// Sometimes it is more efficient to generate separate stores for F and I,
6617/// which can remove the bitwise instructions or sink them to colder places.
6618///
6619/// (store (or (zext (bitcast F to i32) to i64),
6620/// (shl (zext I to i64), 32)), addr) -->
6621/// (store F, addr) and (store I, addr+4)
6622///
6623/// Similarly, splitting for other merged store can also be beneficial, like:
6624/// For pair of {i32, i32}, i64 store --> two i32 stores.
6625/// For pair of {i32, i16}, i64 store --> two i32 stores.
6626/// For pair of {i16, i16}, i32 store --> two i16 stores.
6627/// For pair of {i16, i8}, i32 store --> two i16 stores.
6628/// For pair of {i8, i8}, i16 store --> two i8 stores.
6629///
6630/// We allow each target to determine specifically which kind of splitting is
6631/// supported.
6632///
6633/// The store patterns are commonly seen from the simple code snippet below
6634/// if only std::make_pair(...) is sroa transformed before inlined into hoo.
6635/// void goo(const std::pair<int, float> &);
6636/// hoo() {
6637/// ...
6638/// goo(std::make_pair(tmp, ftmp));
6639/// ...
6640/// }
6641///
6642/// Although we already have similar splitting in DAG Combine, we duplicate
6643/// it in CodeGenPrepare to catch the case in which pattern is across
6644/// multiple BBs. The logic in DAG Combine is kept to catch case generated
6645/// during code expansion.
6646static bool splitMergedValStore(StoreInst &SI, const DataLayout &DL,
6647 const TargetLowering &TLI) {
6648 // Handle simple but common cases only.
6649 Type *StoreType = SI.getValueOperand()->getType();
6650 if (DL.getTypeStoreSizeInBits(StoreType) != DL.getTypeSizeInBits(StoreType) ||
6651 DL.getTypeSizeInBits(StoreType) == 0)
6652 return false;
6653
6654 unsigned HalfValBitSize = DL.getTypeSizeInBits(StoreType) / 2;
6655 Type *SplitStoreType = Type::getIntNTy(SI.getContext(), HalfValBitSize);
6656 if (DL.getTypeStoreSizeInBits(SplitStoreType) !=
6657 DL.getTypeSizeInBits(SplitStoreType))
6658 return false;
6659
6660 // Match the following patterns:
6661 // (store (or (zext LValue to i64),
6662 // (shl (zext HValue to i64), 32)), HalfValBitSize)
6663 // or
6664 // (store (or (shl (zext HValue to i64), 32)), HalfValBitSize)
6665 // (zext LValue to i64),
6666 // Expect both operands of OR and the first operand of SHL have only
6667 // one use.
6668 Value *LValue, *HValue;
6669 if (!match(SI.getValueOperand(),
6670 m_c_Or(m_OneUse(m_ZExt(m_Value(LValue))),
6671 m_OneUse(m_Shl(m_OneUse(m_ZExt(m_Value(HValue))),
6672 m_SpecificInt(HalfValBitSize))))))
6673 return false;
6674
6675 // Check LValue and HValue are int with size less or equal than 32.
6676 if (!LValue->getType()->isIntegerTy() ||
6677 DL.getTypeSizeInBits(LValue->getType()) > HalfValBitSize ||
6678 !HValue->getType()->isIntegerTy() ||
6679 DL.getTypeSizeInBits(HValue->getType()) > HalfValBitSize)
6680 return false;
6681
6682 // If LValue/HValue is a bitcast instruction, use the EVT before bitcast
6683 // as the input of target query.
6684 auto *LBC = dyn_cast<BitCastInst>(LValue);
6685 auto *HBC = dyn_cast<BitCastInst>(HValue);
6686 EVT LowTy = LBC ? EVT::getEVT(LBC->getOperand(0)->getType())
6687 : EVT::getEVT(LValue->getType());
6688 EVT HighTy = HBC ? EVT::getEVT(HBC->getOperand(0)->getType())
6689 : EVT::getEVT(HValue->getType());
6690 if (!ForceSplitStore && !TLI.isMultiStoresCheaperThanBitsMerge(LowTy, HighTy))
6691 return false;
6692
6693 // Start to split store.
6694 IRBuilder<> Builder(SI.getContext());
6695 Builder.SetInsertPoint(&SI);
6696
6697 // If LValue/HValue is a bitcast in another BB, create a new one in current
6698 // BB so it may be merged with the splitted stores by dag combiner.
6699 if (LBC && LBC->getParent() != SI.getParent())
6700 LValue = Builder.CreateBitCast(LBC->getOperand(0), LBC->getType());
6701 if (HBC && HBC->getParent() != SI.getParent())
6702 HValue = Builder.CreateBitCast(HBC->getOperand(0), HBC->getType());
6703
6704 bool IsLE = SI.getModule()->getDataLayout().isLittleEndian();
6705 auto CreateSplitStore = [&](Value *V, bool Upper) {
6706 V = Builder.CreateZExtOrBitCast(V, SplitStoreType);
6707 Value *Addr = Builder.CreateBitCast(
6708 SI.getOperand(1),
6709 SplitStoreType->getPointerTo(SI.getPointerAddressSpace()));
6710 if ((IsLE && Upper) || (!IsLE && !Upper))
6711 Addr = Builder.CreateGEP(
6712 SplitStoreType, Addr,
6713 ConstantInt::get(Type::getInt32Ty(SI.getContext()), 1));
6714 Builder.CreateAlignedStore(
6715 V, Addr, Upper ? SI.getAlignment() / 2 : SI.getAlignment());
6716 };
6717
6718 CreateSplitStore(LValue, false);
6719 CreateSplitStore(HValue, true);
6720
6721 // Delete the old store.
6722 SI.eraseFromParent();
6723 return true;
6724}
6725
6726// Return true if the GEP has two operands, the first operand is of a sequential
6727// type, and the second operand is a constant.
6728static bool GEPSequentialConstIndexed(GetElementPtrInst *GEP) {
6729 gep_type_iterator I = gep_type_begin(*GEP);
6730 return GEP->getNumOperands() == 2 &&
6731 I.isSequential() &&
6732 isa<ConstantInt>(GEP->getOperand(1));
6733}
6734
6735// Try unmerging GEPs to reduce liveness interference (register pressure) across
6736// IndirectBr edges. Since IndirectBr edges tend to touch on many blocks,
6737// reducing liveness interference across those edges benefits global register
6738// allocation. Currently handles only certain cases.
6739//
6740// For example, unmerge %GEPI and %UGEPI as below.
6741//
6742// ---------- BEFORE ----------
6743// SrcBlock:
6744// ...
6745// %GEPIOp = ...
6746// ...
6747// %GEPI = gep %GEPIOp, Idx
6748// ...
6749// indirectbr ... [ label %DstB0, label %DstB1, ... label %DstBi ... ]
6750// (* %GEPI is alive on the indirectbr edges due to other uses ahead)
6751// (* %GEPIOp is alive on the indirectbr edges only because of it's used by
6752// %UGEPI)
6753//
6754// DstB0: ... (there may be a gep similar to %UGEPI to be unmerged)
6755// DstB1: ... (there may be a gep similar to %UGEPI to be unmerged)
6756// ...
6757//
6758// DstBi:
6759// ...
6760// %UGEPI = gep %GEPIOp, UIdx
6761// ...
6762// ---------------------------
6763//
6764// ---------- AFTER ----------
6765// SrcBlock:
6766// ... (same as above)
6767// (* %GEPI is still alive on the indirectbr edges)
6768// (* %GEPIOp is no longer alive on the indirectbr edges as a result of the
6769// unmerging)
6770// ...
6771//
6772// DstBi:
6773// ...
6774// %UGEPI = gep %GEPI, (UIdx-Idx)
6775// ...
6776// ---------------------------
6777//
6778// The register pressure on the IndirectBr edges is reduced because %GEPIOp is
6779// no longer alive on them.
6780//
6781// We try to unmerge GEPs here in CodGenPrepare, as opposed to limiting merging
6782// of GEPs in the first place in InstCombiner::visitGetElementPtrInst() so as
6783// not to disable further simplications and optimizations as a result of GEP
6784// merging.
6785//
6786// Note this unmerging may increase the length of the data flow critical path
6787// (the path from %GEPIOp to %UGEPI would go through %GEPI), which is a tradeoff
6788// between the register pressure and the length of data-flow critical
6789// path. Restricting this to the uncommon IndirectBr case would minimize the
6790// impact of potentially longer critical path, if any, and the impact on compile
6791// time.
6792static bool tryUnmergingGEPsAcrossIndirectBr(GetElementPtrInst *GEPI,
6793 const TargetTransformInfo *TTI) {
6794 BasicBlock *SrcBlock = GEPI->getParent();
6795 // Check that SrcBlock ends with an IndirectBr. If not, give up. The common
6796 // (non-IndirectBr) cases exit early here.
6797 if (!isa<IndirectBrInst>(SrcBlock->getTerminator()))
6798 return false;
6799 // Check that GEPI is a simple gep with a single constant index.
6800 if (!GEPSequentialConstIndexed(GEPI))
6801 return false;
6802 ConstantInt *GEPIIdx = cast<ConstantInt>(GEPI->getOperand(1));
6803 // Check that GEPI is a cheap one.
6804 if (TTI->getIntImmCost(GEPIIdx->getValue(), GEPIIdx->getType())
6805 > TargetTransformInfo::TCC_Basic)
6806 return false;
6807 Value *GEPIOp = GEPI->getOperand(0);
6808 // Check that GEPIOp is an instruction that's also defined in SrcBlock.
6809 if (!isa<Instruction>(GEPIOp))
6810 return false;
6811 auto *GEPIOpI = cast<Instruction>(GEPIOp);
6812 if (GEPIOpI->getParent() != SrcBlock)
6813 return false;
6814 // Check that GEP is used outside the block, meaning it's alive on the
6815 // IndirectBr edge(s).
6816 if (find_if(GEPI->users(), [&](User *Usr) {
6817 if (auto *I = dyn_cast<Instruction>(Usr)) {
6818 if (I->getParent() != SrcBlock) {
6819 return true;
6820 }
6821 }
6822 return false;
6823 }) == GEPI->users().end())
6824 return false;
6825 // The second elements of the GEP chains to be unmerged.
6826 std::vector<GetElementPtrInst *> UGEPIs;
6827 // Check each user of GEPIOp to check if unmerging would make GEPIOp not alive
6828 // on IndirectBr edges.
6829 for (User *Usr : GEPIOp->users()) {
6830 if (Usr == GEPI) continue;
6831 // Check if Usr is an Instruction. If not, give up.
6832 if (!isa<Instruction>(Usr))
6833 return false;
6834 auto *UI = cast<Instruction>(Usr);
6835 // Check if Usr in the same block as GEPIOp, which is fine, skip.
6836 if (UI->getParent() == SrcBlock)
6837 continue;
6838 // Check if Usr is a GEP. If not, give up.
6839 if (!isa<GetElementPtrInst>(Usr))
6840 return false;
6841 auto *UGEPI = cast<GetElementPtrInst>(Usr);
6842 // Check if UGEPI is a simple gep with a single constant index and GEPIOp is
6843 // the pointer operand to it. If so, record it in the vector. If not, give
6844 // up.
6845 if (!GEPSequentialConstIndexed(UGEPI))
6846 return false;
6847 if (UGEPI->getOperand(0) != GEPIOp)
6848 return false;
6849 if (GEPIIdx->getType() !=
6850 cast<ConstantInt>(UGEPI->getOperand(1))->getType())
6851 return false;
6852 ConstantInt *UGEPIIdx = cast<ConstantInt>(UGEPI->getOperand(1));
6853 if (TTI->getIntImmCost(UGEPIIdx->getValue(), UGEPIIdx->getType())
6854 > TargetTransformInfo::TCC_Basic)
6855 return false;
6856 UGEPIs.push_back(UGEPI);
6857 }
6858 if (UGEPIs.size() == 0)
6859 return false;
6860 // Check the materializing cost of (Uidx-Idx).
6861 for (GetElementPtrInst *UGEPI : UGEPIs) {
6862 ConstantInt *UGEPIIdx = cast<ConstantInt>(UGEPI->getOperand(1));
6863 APInt NewIdx = UGEPIIdx->getValue() - GEPIIdx->getValue();
6864 unsigned ImmCost = TTI->getIntImmCost(NewIdx, GEPIIdx->getType());
6865 if (ImmCost > TargetTransformInfo::TCC_Basic)
6866 return false;
6867 }
6868 // Now unmerge between GEPI and UGEPIs.
6869 for (GetElementPtrInst *UGEPI : UGEPIs) {
6870 UGEPI->setOperand(0, GEPI);
6871 ConstantInt *UGEPIIdx = cast<ConstantInt>(UGEPI->getOperand(1));
6872 Constant *NewUGEPIIdx =
6873 ConstantInt::get(GEPIIdx->getType(),
6874 UGEPIIdx->getValue() - GEPIIdx->getValue());
6875 UGEPI->setOperand(1, NewUGEPIIdx);
6876 // If GEPI is not inbounds but UGEPI is inbounds, change UGEPI to not
6877 // inbounds to avoid UB.
6878 if (!GEPI->isInBounds()) {
6879 UGEPI->setIsInBounds(false);
6880 }
6881 }
6882 // After unmerging, verify that GEPIOp is actually only used in SrcBlock (not
6883 // alive on IndirectBr edges).
6884 assert(find_if(GEPIOp->users(), [&](User *Usr) {((find_if(GEPIOp->users(), [&](User *Usr) { return cast
<Instruction>(Usr)->getParent() != SrcBlock; }) == GEPIOp
->users().end() && "GEPIOp is used outside SrcBlock"
) ? static_cast<void> (0) : __assert_fail ("find_if(GEPIOp->users(), [&](User *Usr) { return cast<Instruction>(Usr)->getParent() != SrcBlock; }) == GEPIOp->users().end() && \"GEPIOp is used outside SrcBlock\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 6886, __PRETTY_FUNCTION__))
6885 return cast<Instruction>(Usr)->getParent() != SrcBlock;((find_if(GEPIOp->users(), [&](User *Usr) { return cast
<Instruction>(Usr)->getParent() != SrcBlock; }) == GEPIOp
->users().end() && "GEPIOp is used outside SrcBlock"
) ? static_cast<void> (0) : __assert_fail ("find_if(GEPIOp->users(), [&](User *Usr) { return cast<Instruction>(Usr)->getParent() != SrcBlock; }) == GEPIOp->users().end() && \"GEPIOp is used outside SrcBlock\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 6886, __PRETTY_FUNCTION__))
6886 }) == GEPIOp->users().end() && "GEPIOp is used outside SrcBlock")((find_if(GEPIOp->users(), [&](User *Usr) { return cast
<Instruction>(Usr)->getParent() != SrcBlock; }) == GEPIOp
->users().end() && "GEPIOp is used outside SrcBlock"
) ? static_cast<void> (0) : __assert_fail ("find_if(GEPIOp->users(), [&](User *Usr) { return cast<Instruction>(Usr)->getParent() != SrcBlock; }) == GEPIOp->users().end() && \"GEPIOp is used outside SrcBlock\""
, "/build/llvm-toolchain-snapshot-9~svn359999/lib/CodeGen/CodeGenPrepare.cpp"
, 6886, __PRETTY_FUNCTION__))
;
6887 return true;
6888}
6889
6890bool CodeGenPrepare::optimizeInst(Instruction *I, bool &ModifiedDT) {
6891 // Bail out if we inserted the instruction to prevent optimizations from
6892 // stepping on each other's toes.
6893 if (InsertedInsts.count(I))
15
Assuming the condition is false
16
Taking false branch
6894 return false;
6895
6896 // TODO: Move into the switch on opcode below here.
6897 if (PHINode *P = dyn_cast<PHINode>(I)) {
17
Taking false branch
6898 // It is possible for very late stage optimizations (such as SimplifyCFG)
6899 // to introduce PHI nodes too late to be cleaned up. If we detect such a
6900 // trivial PHI, go ahead and zap it here.
6901 if (Value *V = SimplifyInstruction(P, {*DL, TLInfo})) {
6902 LargeOffsetGEPMap.erase(P);
6903 P->replaceAllUsesWith(V);
6904 P->eraseFromParent();
6905 ++NumPHIsElim;
6906 return true;
6907 }
6908 return false;
6909 }
6910
6911 if (CastInst *CI = dyn_cast<CastInst>(I)) {
18
Taking false branch
6912 // If the source of the cast is a constant, then this should have
6913 // already been constant folded. The only reason NOT to constant fold
6914 // it is if something (e.g. LSR) was careful to place the constant
6915 // evaluation in a block other than then one that uses it (e.g. to hoist
6916 // the address of globals out of a loop). If this is the case, we don't
6917 // want to forward-subst the cast.
6918 if (isa<Constant>(CI->getOperand(0)))
6919 return false;
6920
6921 if (TLI && OptimizeNoopCopyExpression(CI, *TLI, *DL))
6922 return true;
6923
6924 if (isa<ZExtInst>(I) || isa<SExtInst>(I)) {
6925 /// Sink a zext or sext into its user blocks if the target type doesn't
6926 /// fit in one register
6927 if (TLI &&
6928 TLI->getTypeAction(CI->getContext(),
6929 TLI->getValueType(*DL, CI->getType())) ==
6930 TargetLowering::TypeExpandInteger) {
6931 return SinkCast(CI);
6932 } else {
6933 bool MadeChange = optimizeExt(I);
6934 return MadeChange | optimizeExtUses(I);
6935 }
6936 }
6937 return false;
6938 }
6939
6940 if (auto *Cmp = dyn_cast<CmpInst>(I))
19
Taking false branch
6941 if (TLI && optimizeCmp(Cmp, ModifiedDT))
6942 return true;
6943
6944 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
20
Taking false branch
6945 LI->setMetadata(LLVMContext::MD_invariant_group, nullptr);
6946 if (TLI) {
6947 bool Modified = optimizeLoadExt(LI);
6948 unsigned AS = LI->getPointerAddressSpace();
6949 Modified |= optimizeMemoryInst(I, I->getOperand(0), LI->getType(), AS);
6950 return Modified;
6951 }
6952 return false;
6953 }
6954
6955 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
21
Taking false branch
6956 if (TLI && splitMergedValStore(*SI, *DL, *TLI))
6957 return true;
6958 SI->setMetadata(LLVMContext::MD_invariant_group, nullptr);
6959 if (TLI) {
6960 unsigned AS = SI->getPointerAddressSpace();
6961 return optimizeMemoryInst(I, SI->getOperand(1),
6962 SI->getOperand(0)->getType(), AS);
6963 }
6964 return false;
6965 }
6966
6967 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
22
Taking false branch
6968 unsigned AS = RMW->getPointerAddressSpace();
6969 return optimizeMemoryInst(I, RMW->getPointerOperand(),
6970 RMW->getType(), AS);
6971 }
6972
6973 if (AtomicCmpXchgInst *CmpX = dyn_cast<AtomicCmpXchgInst>(I)) {
23
Taking false branch
6974 unsigned AS = CmpX->getPointerAddressSpace();
6975 return optimizeMemoryInst(I, CmpX->getPointerOperand(),
6976 CmpX->getCompareOperand()->getType(), AS);
6977 }
6978
6979 BinaryOperator *BinOp = dyn_cast<BinaryOperator>(I);
6980
6981 if (BinOp && (BinOp->getOpcode() == Instruction::And) &&
6982 EnableAndCmpSinking && TLI)
6983 return sinkAndCmp0Expression(BinOp, *TLI, InsertedInsts);
6984
6985 if (BinOp && (BinOp->getOpcode() == Instruction::AShr ||
6986 BinOp->getOpcode() == Instruction::LShr)) {
6987 ConstantInt *CI = dyn_cast<ConstantInt>(BinOp->getOperand(1));
6988 if (TLI && CI && TLI->hasExtractBitsInsn())
6989 return OptimizeExtractBits(BinOp, CI, *TLI, *DL);
6990
6991 return false;
6992 }
6993
6994 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I)) {
24
Taking false branch
6995 if (GEPI->hasAllZeroIndices()) {
6996 /// The GEP operand must be a pointer, so must its result -> BitCast
6997 Instruction *NC = new BitCastInst(GEPI->getOperand(0), GEPI->getType(),
6998 GEPI->getName(), GEPI);
6999 NC->setDebugLoc(GEPI->getDebugLoc());
7000 GEPI->replaceAllUsesWith(NC);
7001 GEPI->eraseFromParent();
7002 ++NumGEPsElim;
7003 optimizeInst(NC, ModifiedDT);
7004 return true;
7005 }
7006 if (tryUnmergingGEPsAcrossIndirectBr(GEPI, TTI)) {
7007 return true;
7008 }
7009 return false;
7010 }
7011
7012 if (tryToSinkFreeOperands(I))
25
Taking false branch
7013 return true;
7014
7015 switch (I->getOpcode()) {
26
Control jumps to 'case Select:' at line 7018
7016 case Instruction::Call:
7017 return optimizeCallInst(cast<CallInst>(I), ModifiedDT);
7018 case Instruction::Select:
7019 return optimizeSelectInst(cast<SelectInst>(I));
27
Calling 'CodeGenPrepare::optimizeSelectInst'
7020 case Instruction::ShuffleVector:
7021 return optimizeShuffleVectorInst(cast<ShuffleVectorInst>(I));
7022 case Instruction::Switch:
7023 return optimizeSwitchInst(cast<SwitchInst>(I));
7024 case Instruction::ExtractElement:
7025 return optimizeExtractElementInst(cast<ExtractElementInst>(I));
7026 }
7027
7028 return false;
7029}
7030
7031/// Given an OR instruction, check to see if this is a bitreverse
7032/// idiom. If so, insert the new intrinsic and return true.
7033static bool makeBitReverse(Instruction &I, const DataLayout &DL,
7034 const TargetLowering &TLI) {
7035 if (!I.getType()->isIntegerTy() ||
7036 !TLI.isOperationLegalOrCustom(ISD::BITREVERSE,
7037 TLI.getValueType(DL, I.getType(), true)))
7038 return false;
7039
7040 SmallVector<Instruction*, 4> Insts;
7041 if (!recognizeBSwapOrBitReverseIdiom(&I, false, true, Insts))
7042 return false;
7043 Instruction *LastInst = Insts.back();
7044 I.replaceAllUsesWith(LastInst);
7045 RecursivelyDeleteTriviallyDeadInstructions(&I);
7046 return true;
7047}
7048
7049// In this pass we look for GEP and cast instructions that are used
7050// across basic blocks and rewrite them to improve basic-block-at-a-time
7051// selection.
7052bool CodeGenPrepare::optimizeBlock(BasicBlock &BB, bool &ModifiedDT) {
7053 SunkAddrs.clear();
7054 bool MadeChange = false;
7055
7056 CurInstIterator = BB.begin();
7057 while (CurInstIterator != BB.end()) {
13
Loop condition is true. Entering loop body
7058 MadeChange |= optimizeInst(&*CurInstIterator++, ModifiedDT);
14
Calling 'CodeGenPrepare::optimizeInst'
7059 if (ModifiedDT)
7060 return true;
7061 }
7062
7063 bool MadeBitReverse = true;
7064 while (TLI && MadeBitReverse) {
7065 MadeBitReverse = false;
7066 for (auto &I : reverse(BB)) {
7067 if (makeBitReverse(I, *DL, *TLI)) {
7068 MadeBitReverse = MadeChange = true;
7069 ModifiedDT = true;
7070 break;
7071 }
7072 }
7073 }
7074 MadeChange |= dupRetToEnableTailCallOpts(&BB, ModifiedDT);
7075
7076 return MadeChange;
7077}
7078
7079// llvm.dbg.value is far away from the value then iSel may not be able
7080// handle it properly. iSel will drop llvm.dbg.value if it can not
7081// find a node corresponding to the value.
7082bool CodeGenPrepare::placeDbgValues(Function &F) {
7083 bool MadeChange = false;
7084 for (BasicBlock &BB : F) {
7085 Instruction *PrevNonDbgInst = nullptr;
7086 for (BasicBlock::iterator BI = BB.begin(), BE = BB.end(); BI != BE;) {
7087 Instruction *Insn = &*BI++;
7088 DbgValueInst *DVI = dyn_cast<DbgValueInst>(Insn);
7089 // Leave dbg.values that refer to an alloca alone. These
7090 // intrinsics describe the address of a variable (= the alloca)
7091 // being taken. They should not be moved next to the alloca
7092 // (and to the beginning of the scope), but rather stay close to
7093 // where said address is used.
7094 if (!DVI || (DVI->getValue() && isa<AllocaInst>(DVI->getValue()))) {
7095 PrevNonDbgInst = Insn;
7096 continue;
7097 }
7098
7099 Instruction *VI = dyn_cast_or_null<Instruction>(DVI->getValue());
7100 if (VI && VI != PrevNonDbgInst && !VI->isTerminator()) {
7101 // If VI is a phi in a block with an EHPad terminator, we can't insert
7102 // after it.
7103 if (isa<PHINode>(VI) && VI->getParent()->getTerminator()->isEHPad())
7104 continue;
7105 LLVM_DEBUG(dbgs() << "Moving Debug Value before :\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Moving Debug Value before :\n"
<< *DVI << ' ' << *VI; } } while (false)
7106 << *DVI << ' ' << *VI)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Moving Debug Value before :\n"
<< *DVI << ' ' << *VI; } } while (false)
;
7107 DVI->removeFromParent();
7108 if (isa<PHINode>(VI))
7109 DVI->insertBefore(&*VI->getParent()->getFirstInsertionPt());
7110 else
7111 DVI->insertAfter(VI);
7112 MadeChange = true;
7113 ++NumDbgValueMoved;
7114 }
7115 }
7116 }
7117 return MadeChange;
7118}
7119
7120/// Scale down both weights to fit into uint32_t.
7121static void scaleWeights(uint64_t &NewTrue, uint64_t &NewFalse) {
7122 uint64_t NewMax = (NewTrue > NewFalse) ? NewTrue : NewFalse;
7123 uint32_t Scale = (NewMax / std::numeric_limits<uint32_t>::max()) + 1;
7124 NewTrue = NewTrue / Scale;
7125 NewFalse = NewFalse / Scale;
7126}
7127
7128/// Some targets prefer to split a conditional branch like:
7129/// \code
7130/// %0 = icmp ne i32 %a, 0
7131/// %1 = icmp ne i32 %b, 0
7132/// %or.cond = or i1 %0, %1
7133/// br i1 %or.cond, label %TrueBB, label %FalseBB
7134/// \endcode
7135/// into multiple branch instructions like:
7136/// \code
7137/// bb1:
7138/// %0 = icmp ne i32 %a, 0
7139/// br i1 %0, label %TrueBB, label %bb2
7140/// bb2:
7141/// %1 = icmp ne i32 %b, 0
7142/// br i1 %1, label %TrueBB, label %FalseBB
7143/// \endcode
7144/// This usually allows instruction selection to do even further optimizations
7145/// and combine the compare with the branch instruction. Currently this is
7146/// applied for targets which have "cheap" jump instructions.
7147///
7148/// FIXME: Remove the (equivalent?) implementation in SelectionDAG.
7149///
7150bool CodeGenPrepare::splitBranchCondition(Function &F, bool &ModifiedDT) {
7151 if (!TM || !TM->Options.EnableFastISel || !TLI || TLI->isJumpExpensive())
7152 return false;
7153
7154 bool MadeChange = false;
7155 for (auto &BB : F) {
7156 // Does this BB end with the following?
7157 // %cond1 = icmp|fcmp|binary instruction ...
7158 // %cond2 = icmp|fcmp|binary instruction ...
7159 // %cond.or = or|and i1 %cond1, cond2
7160 // br i1 %cond.or label %dest1, label %dest2"
7161 BinaryOperator *LogicOp;
7162 BasicBlock *TBB, *FBB;
7163 if (!match(BB.getTerminator(), m_Br(m_OneUse(m_BinOp(LogicOp)), TBB, FBB)))
7164 continue;
7165
7166 auto *Br1 = cast<BranchInst>(BB.getTerminator());
7167 if (Br1->getMetadata(LLVMContext::MD_unpredictable))
7168 continue;
7169
7170 unsigned Opc;
7171 Value *Cond1, *Cond2;
7172 if (match(LogicOp, m_And(m_OneUse(m_Value(Cond1)),
7173 m_OneUse(m_Value(Cond2)))))
7174 Opc = Instruction::And;
7175 else if (match(LogicOp, m_Or(m_OneUse(m_Value(Cond1)),
7176 m_OneUse(m_Value(Cond2)))))
7177 Opc = Instruction::Or;
7178 else
7179 continue;
7180
7181 if (!match(Cond1, m_CombineOr(m_Cmp(), m_BinOp())) ||
7182 !match(Cond2, m_CombineOr(m_Cmp(), m_BinOp())) )
7183 continue;
7184
7185 LLVM_DEBUG(dbgs() << "Before branch condition splitting\n"; BB.dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Before branch condition splitting\n"
; BB.dump(); } } while (false)
;
7186
7187 // Create a new BB.
7188 auto TmpBB =
7189 BasicBlock::Create(BB.getContext(), BB.getName() + ".cond.split",
7190 BB.getParent(), BB.getNextNode());
7191
7192 // Update original basic block by using the first condition directly by the
7193 // branch instruction and removing the no longer needed and/or instruction.
7194 Br1->setCondition(Cond1);
7195 LogicOp->eraseFromParent();
7196
7197 // Depending on the condition we have to either replace the true or the
7198 // false successor of the original branch instruction.
7199 if (Opc == Instruction::And)
7200 Br1->setSuccessor(0, TmpBB);
7201 else
7202 Br1->setSuccessor(1, TmpBB);
7203
7204 // Fill in the new basic block.
7205 auto *Br2 = IRBuilder<>(TmpBB).CreateCondBr(Cond2, TBB, FBB);
7206 if (auto *I = dyn_cast<Instruction>(Cond2)) {
7207 I->removeFromParent();
7208 I->insertBefore(Br2);
7209 }
7210
7211 // Update PHI nodes in both successors. The original BB needs to be
7212 // replaced in one successor's PHI nodes, because the branch comes now from
7213 // the newly generated BB (NewBB). In the other successor we need to add one
7214 // incoming edge to the PHI nodes, because both branch instructions target
7215 // now the same successor. Depending on the original branch condition
7216 // (and/or) we have to swap the successors (TrueDest, FalseDest), so that
7217 // we perform the correct update for the PHI nodes.
7218 // This doesn't change the successor order of the just created branch
7219 // instruction (or any other instruction).
7220 if (Opc == Instruction::Or)
7221 std::swap(TBB, FBB);
7222
7223 // Replace the old BB with the new BB.
7224 TBB->replacePhiUsesWith(&BB, TmpBB);
7225
7226 // Add another incoming edge form the new BB.
7227 for (PHINode &PN : FBB->phis()) {
7228 auto *Val = PN.getIncomingValueForBlock(&BB);
7229 PN.addIncoming(Val, TmpBB);
7230 }
7231
7232 // Update the branch weights (from SelectionDAGBuilder::
7233 // FindMergedConditions).
7234 if (Opc == Instruction::Or) {
7235 // Codegen X | Y as:
7236 // BB1:
7237 // jmp_if_X TBB
7238 // jmp TmpBB
7239 // TmpBB:
7240 // jmp_if_Y TBB
7241 // jmp FBB
7242 //
7243
7244 // We have flexibility in setting Prob for BB1 and Prob for NewBB.
7245 // The requirement is that
7246 // TrueProb for BB1 + (FalseProb for BB1 * TrueProb for TmpBB)
7247 // = TrueProb for original BB.
7248 // Assuming the original weights are A and B, one choice is to set BB1's
7249 // weights to A and A+2B, and set TmpBB's weights to A and 2B. This choice
7250 // assumes that
7251 // TrueProb for BB1 == FalseProb for BB1 * TrueProb for TmpBB.
7252 // Another choice is to assume TrueProb for BB1 equals to TrueProb for
7253 // TmpBB, but the math is more complicated.
7254 uint64_t TrueWeight, FalseWeight;
7255 if (Br1->extractProfMetadata(TrueWeight, FalseWeight)) {
7256 uint64_t NewTrueWeight = TrueWeight;
7257 uint64_t NewFalseWeight = TrueWeight + 2 * FalseWeight;
7258 scaleWeights(NewTrueWeight, NewFalseWeight);
7259 Br1->setMetadata(LLVMContext::MD_prof, MDBuilder(Br1->getContext())
7260 .createBranchWeights(TrueWeight, FalseWeight));
7261
7262 NewTrueWeight = TrueWeight;
7263 NewFalseWeight = 2 * FalseWeight;
7264 scaleWeights(NewTrueWeight, NewFalseWeight);
7265 Br2->setMetadata(LLVMContext::MD_prof, MDBuilder(Br2->getContext())
7266 .createBranchWeights(TrueWeight, FalseWeight));
7267 }
7268 } else {
7269 // Codegen X & Y as:
7270 // BB1:
7271 // jmp_if_X TmpBB
7272 // jmp FBB
7273 // TmpBB:
7274 // jmp_if_Y TBB
7275 // jmp FBB
7276 //
7277 // This requires creation of TmpBB after CurBB.
7278
7279 // We have flexibility in setting Prob for BB1 and Prob for TmpBB.
7280 // The requirement is that
7281 // FalseProb for BB1 + (TrueProb for BB1 * FalseProb for TmpBB)
7282 // = FalseProb for original BB.
7283 // Assuming the original weights are A and B, one choice is to set BB1's
7284 // weights to 2A+B and B, and set TmpBB's weights to 2A and B. This choice
7285 // assumes that
7286 // FalseProb for BB1 == TrueProb for BB1 * FalseProb for TmpBB.
7287 uint64_t TrueWeight, FalseWeight;
7288 if (Br1->extractProfMetadata(TrueWeight, FalseWeight)) {
7289 uint64_t NewTrueWeight = 2 * TrueWeight + FalseWeight;
7290 uint64_t NewFalseWeight = FalseWeight;
7291 scaleWeights(NewTrueWeight, NewFalseWeight);
7292 Br1->setMetadata(LLVMContext::MD_prof, MDBuilder(Br1->getContext())
7293 .createBranchWeights(TrueWeight, FalseWeight));
7294
7295 NewTrueWeight = 2 * TrueWeight;
7296 NewFalseWeight = FalseWeight;
7297 scaleWeights(NewTrueWeight, NewFalseWeight);
7298 Br2->setMetadata(LLVMContext::MD_prof, MDBuilder(Br2->getContext())
7299 .createBranchWeights(TrueWeight, FalseWeight));
7300 }
7301 }
7302
7303 ModifiedDT = true;
7304 MadeChange = true;
7305
7306 LLVM_DEBUG(dbgs() << "After branch condition splitting\n"; BB.dump();do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "After branch condition splitting\n"
; BB.dump(); TmpBB->dump(); } } while (false)
7307 TmpBB->dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "After branch condition splitting\n"
; BB.dump(); TmpBB->dump(); } } while (false)
;
7308 }
7309 return MadeChange;
7310}