LLVM  13.0.0git
LowerConstantIntrinsics.cpp
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1 //===- LowerConstantIntrinsics.cpp - Lower constant intrinsic calls -------===//
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 lowers all remaining 'objectsize' 'is.constant' intrinsic calls
10 // and provides constant propagation and basic CFG cleanup on the result.
11 //
12 //===----------------------------------------------------------------------===//
13 
16 #include "llvm/ADT/SetVector.h"
17 #include "llvm/ADT/Statistic.h"
23 #include "llvm/IR/BasicBlock.h"
24 #include "llvm/IR/Constants.h"
25 #include "llvm/IR/Dominators.h"
26 #include "llvm/IR/Function.h"
27 #include "llvm/IR/Instructions.h"
28 #include "llvm/IR/IntrinsicInst.h"
29 #include "llvm/IR/Intrinsics.h"
30 #include "llvm/IR/PatternMatch.h"
31 #include "llvm/InitializePasses.h"
32 #include "llvm/Pass.h"
33 #include "llvm/Support/Debug.h"
34 #include "llvm/Transforms/Scalar.h"
36 
37 using namespace llvm;
38 using namespace llvm::PatternMatch;
39 
40 #define DEBUG_TYPE "lower-is-constant-intrinsic"
41 
42 STATISTIC(IsConstantIntrinsicsHandled,
43  "Number of 'is.constant' intrinsic calls handled");
44 STATISTIC(ObjectSizeIntrinsicsHandled,
45  "Number of 'objectsize' intrinsic calls handled");
46 
48  Value *Op = II->getOperand(0);
49 
50  return isa<Constant>(Op) ? ConstantInt::getTrue(II->getType())
52 }
53 
55  Value *NewValue,
56  DomTreeUpdater *DTU) {
57  bool HasDeadBlocks = false;
59  replaceAndRecursivelySimplify(II, NewValue, nullptr, nullptr, nullptr,
60  &Worklist);
61  for (auto I : Worklist) {
62  BranchInst *BI = dyn_cast<BranchInst>(I);
63  if (!BI)
64  continue;
65  if (BI->isUnconditional())
66  continue;
67 
69  if (match(BI->getOperand(0), m_Zero())) {
70  Target = BI->getSuccessor(1);
71  Other = BI->getSuccessor(0);
72  } else if (match(BI->getOperand(0), m_One())) {
73  Target = BI->getSuccessor(0);
74  Other = BI->getSuccessor(1);
75  } else {
76  Target = nullptr;
77  Other = nullptr;
78  }
79  if (Target && Target != Other) {
80  BasicBlock *Source = BI->getParent();
81  Other->removePredecessor(Source);
82  BI->eraseFromParent();
84  if (DTU)
86  if (pred_empty(Other))
87  HasDeadBlocks = true;
88  }
89  }
90  return HasDeadBlocks;
91 }
92 
94  DominatorTree *DT) {
96  if (DT)
98 
99  bool HasDeadBlocks = false;
100  const auto &DL = F.getParent()->getDataLayout();
102 
104  for (BasicBlock *BB : RPOT) {
105  for (Instruction &I: *BB) {
106  IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I);
107  if (!II)
108  continue;
109  switch (II->getIntrinsicID()) {
110  default:
111  break;
112  case Intrinsic::is_constant:
113  case Intrinsic::objectsize:
114  Worklist.push_back(WeakTrackingVH(&I));
115  break;
116  }
117  }
118  }
119  for (WeakTrackingVH &VH: Worklist) {
120  // Items on the worklist can be mutated by earlier recursive replaces.
121  // This can remove the intrinsic as dead (VH == null), but also replace
122  // the intrinsic in place.
123  if (!VH)
124  continue;
125  IntrinsicInst *II = dyn_cast<IntrinsicInst>(&*VH);
126  if (!II)
127  continue;
128  Value *NewValue;
129  switch (II->getIntrinsicID()) {
130  default:
131  continue;
132  case Intrinsic::is_constant:
133  NewValue = lowerIsConstantIntrinsic(II);
134  IsConstantIntrinsicsHandled++;
135  break;
136  case Intrinsic::objectsize:
137  NewValue = lowerObjectSizeCall(II, DL, TLI, true);
138  ObjectSizeIntrinsicsHandled++;
139  break;
140  }
141  HasDeadBlocks |= replaceConditionalBranchesOnConstant(
142  II, NewValue, DTU.hasValue() ? DTU.getPointer() : nullptr);
143  }
144  if (HasDeadBlocks)
145  removeUnreachableBlocks(F, DTU.hasValue() ? DTU.getPointer() : nullptr);
146  return !Worklist.empty();
147 }
148 
154  PA.preserve<GlobalsAA>();
156  return PA;
157  }
158 
159  return PreservedAnalyses::all();
160 }
161 
162 namespace {
163 /// Legacy pass for lowering is.constant intrinsics out of the IR.
164 ///
165 /// When this pass is run over a function it converts is.constant intrinsics
166 /// into 'true' or 'false'. This complements the normal constant folding
167 /// to 'true' as part of Instruction Simplify passes.
168 class LowerConstantIntrinsics : public FunctionPass {
169 public:
170  static char ID;
171  LowerConstantIntrinsics() : FunctionPass(ID) {
173  }
174 
175  bool runOnFunction(Function &F) override {
176  auto *TLIP = getAnalysisIfAvailable<TargetLibraryInfoWrapperPass>();
177  const TargetLibraryInfo *TLI = TLIP ? &TLIP->getTLI(F) : nullptr;
178  DominatorTree *DT = nullptr;
179  if (auto *DTWP = getAnalysisIfAvailable<DominatorTreeWrapperPass>())
180  DT = &DTWP->getDomTree();
181  return lowerConstantIntrinsics(F, TLI, DT);
182  }
183 
184  void getAnalysisUsage(AnalysisUsage &AU) const override {
187  }
188 };
189 } // namespace
190 
192 INITIALIZE_PASS_BEGIN(LowerConstantIntrinsics, "lower-constant-intrinsics",
193  "Lower constant intrinsics", false, false)
195 INITIALIZE_PASS_END(LowerConstantIntrinsics, "lower-constant-intrinsics",
197 
199  return new LowerConstantIntrinsics();
200 }
llvm::GlobalsAA
Analysis pass providing a never-invalidated alias analysis result.
Definition: GlobalsModRef.h:132
llvm::PreservedAnalyses
A set of analyses that are preserved following a run of a transformation pass.
Definition: PassManager.h:155
constant
we should consider alternate ways to model stack dependencies Lots of things could be done in WebAssemblyTargetTransformInfo cpp there are numerous optimization related hooks that can be overridden in WebAssemblyTargetLowering Instead of the OptimizeReturned which should consider preserving the returned attribute through to MachineInstrs and extending the MemIntrinsicResults pass to do this optimization on calls too That would also let the WebAssemblyPeephole pass clean up dead defs for such as it does for stores Consider implementing and or getMachineCombinerPatterns Find a clean way to fix the problem which leads to the Shrink Wrapping pass being run after the WebAssembly PEI pass When setting multiple variables to the same constant
Definition: README.txt:114
llvm
Definition: AllocatorList.h:23
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Value handle that is nullable, but tries to track the Value.
Definition: ValueHandle.h:204
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Scalar.h
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void applyUpdates(ArrayRef< DominatorTree::UpdateType > Updates)
Submit updates to all available trees.
Definition: DomTreeUpdater.cpp:230
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Definition: Function.h:61
Pass.h
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Intrinsic::ID getIntrinsicID() const
Return the intrinsic ID of this intrinsic.
Definition: IntrinsicInst.h:52
llvm::Target
Target - Wrapper for Target specific information.
Definition: TargetRegistry.h:124
llvm::SmallVector
This is a 'vector' (really, a variable-sized array), optimized for the case when the array is small.
Definition: SmallVector.h:1168
Statistic.h
DomTreeUpdater.h
Local.h
llvm::DominatorTree
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree.
Definition: Dominators.h:151
GlobalsModRef.h
llvm::removeUnreachableBlocks
bool removeUnreachableBlocks(Function &F, DomTreeUpdater *DTU=nullptr, MemorySSAUpdater *MSSAU=nullptr)
Remove all blocks that can not be reached from the function's entry.
Definition: Local.cpp:2478
MemoryBuiltins.h
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Definition: RegBankSelect.cpp:69
F
#define F(x, y, z)
Definition: MD5.cpp:56
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LLVM Basic Block Representation.
Definition: BasicBlock.h:58
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constexpr const T * getPointer() const
Definition: Optional.h:278
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constexpr bool hasValue() const
Definition: Optional.h:286
llvm::PassRegistry::getPassRegistry
static PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
Definition: PassRegistry.cpp:31
Constants.h
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bool match(Val *V, const Pattern &P)
Definition: PatternMatch.h:49
Intrinsics.h
lowerIsConstantIntrinsic
static Value * lowerIsConstantIntrinsic(IntrinsicInst *II)
Definition: LowerConstantIntrinsics.cpp:47
llvm::AnalysisUsage
Represent the analysis usage information of a pass.
Definition: PassAnalysisSupport.h:47
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false
Definition: StackSlotColoring.cpp:142
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Definition: Instruction.h:45
llvm::DominatorTreeWrapperPass
Legacy analysis pass which computes a DominatorTree.
Definition: Dominators.h:281
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llvm::LowerConstantIntrinsicsPass::run
PreservedAnalyses run(Function &F, FunctionAnalysisManager &)
Run the pass over the function.
Definition: LowerConstantIntrinsics.cpp:150
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Definition: DomTreeUpdater.h:28
PatternMatch.h
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cst_pred_ty< is_one > m_One()
Match an integer 1 or a vector with all elements equal to 1.
Definition: PatternMatch.h:469
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llvm::PatternMatch::m_Zero
is_zero m_Zero()
Match any null constant or a vector with all elements equal to 0.
Definition: PatternMatch.h:491
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SymbolTableList< Instruction >::iterator eraseFromParent()
This method unlinks 'this' from the containing basic block and deletes it.
Definition: Instruction.cpp:78
INITIALIZE_PASS_BEGIN
INITIALIZE_PASS_BEGIN(LowerConstantIntrinsics, "lower-constant-intrinsics", "Lower constant intrinsics", false, false) INITIALIZE_PASS_END(LowerConstantIntrinsics
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static bool lowerConstantIntrinsics(Function &F, const TargetLibraryInfo *TLI, DominatorTree *DT)
Definition: LowerConstantIntrinsics.cpp:93
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void preserve()
Mark an analysis as preserved.
Definition: PassManager.h:176
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lower constant intrinsics
Definition: LowerConstantIntrinsics.cpp:195
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void emplace(ArgTypes &&... Args)
Create a new object by constructing it in place with the given arguments.
Definition: Optional.h:262
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static BranchInst * Create(BasicBlock *IfTrue, Instruction *InsertBefore=nullptr)
Definition: Instructions.h:3061
I
#define I(x, y, z)
Definition: MD5.cpp:59
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Value * lowerObjectSizeCall(IntrinsicInst *ObjectSize, const DataLayout &DL, const TargetLibraryInfo *TLI, bool MustSucceed)
Try to turn a call to @llvm.objectsize into an integer value of the given Type.
Definition: MemoryBuiltins.cpp:525
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Definition: InstructionSimplify.cpp:6089
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static bool replaceConditionalBranchesOnConstant(Instruction *II, Value *NewValue, DomTreeUpdater *DTU)
Definition: LowerConstantIntrinsics.cpp:54
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bool isUnconditional() const
Definition: Instructions.h:3083
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@ Source
Definition: TargetLowering.h:98
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Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:256
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AnalysisUsage & addPreserved()
Add the specified Pass class to the set of analyses preserved by this pass.
Definition: PassAnalysisSupport.h:98
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Definition: Constants.cpp:840
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Definition: Constants.cpp:833
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Definition: SIDefines.h:314
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static PreservedAnalyses all()
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Definition: PassManager.h:161
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void initializeLowerConstantIntrinsicsPass(PassRegistry &)
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Get the cached result of an analysis pass for a given IR unit.
Definition: PassManager.h:804
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Provides information about what library functions are available for the current target.
Definition: TargetLibraryInfo.h:207
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Definition: PostOrderIterator.h:290
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Definition: IntrinsicInst.h:45
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Definition: Dominators.h:252
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Definition: LowerConstantIntrinsics.cpp:198
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Definition: PatternMatch.h:47
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Definition: SetVector.h:307
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Definition: InstructionSimplify.h:43
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Definition: Pass.h:298
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Common register allocation spilling lr str ldr sxth r3 ldr mla r4 can lr mov lr str ldr sxth r3 mla r4 and then merge mul and lr str ldr sxth r3 mla r4 It also increase the likelihood the store may become dead bb27 Successors according to LLVM BB
Definition: README.txt:39
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Definition: User.h:169
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Definition: Instructions.h:3005
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LLVM Value Representation.
Definition: Value.h:75
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Definition: TargetLibraryInfo.h:421
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static constexpr UpdateKind Delete
Definition: GenericDomTree.h:243
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unsigned ID
Definition: TargetTransformInfo.h:38