LLVM  14.0.0git
NewGVN.cpp
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1 //===- NewGVN.cpp - Global Value Numbering Pass ---------------------------===//
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 /// \file
10 /// This file implements the new LLVM's Global Value Numbering pass.
11 /// GVN partitions values computed by a function into congruence classes.
12 /// Values ending up in the same congruence class are guaranteed to be the same
13 /// for every execution of the program. In that respect, congruency is a
14 /// compile-time approximation of equivalence of values at runtime.
15 /// The algorithm implemented here uses a sparse formulation and it's based
16 /// on the ideas described in the paper:
17 /// "A Sparse Algorithm for Predicated Global Value Numbering" from
18 /// Karthik Gargi.
19 ///
20 /// A brief overview of the algorithm: The algorithm is essentially the same as
21 /// the standard RPO value numbering algorithm (a good reference is the paper
22 /// "SCC based value numbering" by L. Taylor Simpson) with one major difference:
23 /// The RPO algorithm proceeds, on every iteration, to process every reachable
24 /// block and every instruction in that block. This is because the standard RPO
25 /// algorithm does not track what things have the same value number, it only
26 /// tracks what the value number of a given operation is (the mapping is
27 /// operation -> value number). Thus, when a value number of an operation
28 /// changes, it must reprocess everything to ensure all uses of a value number
29 /// get updated properly. In constrast, the sparse algorithm we use *also*
30 /// tracks what operations have a given value number (IE it also tracks the
31 /// reverse mapping from value number -> operations with that value number), so
32 /// that it only needs to reprocess the instructions that are affected when
33 /// something's value number changes. The vast majority of complexity and code
34 /// in this file is devoted to tracking what value numbers could change for what
35 /// instructions when various things happen. The rest of the algorithm is
36 /// devoted to performing symbolic evaluation, forward propagation, and
37 /// simplification of operations based on the value numbers deduced so far
38 ///
39 /// In order to make the GVN mostly-complete, we use a technique derived from
40 /// "Detection of Redundant Expressions: A Complete and Polynomial-time
41 /// Algorithm in SSA" by R.R. Pai. The source of incompleteness in most SSA
42 /// based GVN algorithms is related to their inability to detect equivalence
43 /// between phi of ops (IE phi(a+b, c+d)) and op of phis (phi(a,c) + phi(b, d)).
44 /// We resolve this issue by generating the equivalent "phi of ops" form for
45 /// each op of phis we see, in a way that only takes polynomial time to resolve.
46 ///
47 /// We also do not perform elimination by using any published algorithm. All
48 /// published algorithms are O(Instructions). Instead, we use a technique that
49 /// is O(number of operations with the same value number), enabling us to skip
50 /// trying to eliminate things that have unique value numbers.
51 //
52 //===----------------------------------------------------------------------===//
53 
55 #include "llvm/ADT/ArrayRef.h"
56 #include "llvm/ADT/BitVector.h"
57 #include "llvm/ADT/DenseMap.h"
58 #include "llvm/ADT/DenseMapInfo.h"
59 #include "llvm/ADT/DenseSet.h"
61 #include "llvm/ADT/GraphTraits.h"
62 #include "llvm/ADT/Hashing.h"
65 #include "llvm/ADT/SetOperations.h"
66 #include "llvm/ADT/SmallPtrSet.h"
67 #include "llvm/ADT/SmallVector.h"
69 #include "llvm/ADT/Statistic.h"
80 #include "llvm/IR/Argument.h"
81 #include "llvm/IR/BasicBlock.h"
82 #include "llvm/IR/Constant.h"
83 #include "llvm/IR/Constants.h"
84 #include "llvm/IR/Dominators.h"
85 #include "llvm/IR/Function.h"
86 #include "llvm/IR/InstrTypes.h"
87 #include "llvm/IR/Instruction.h"
88 #include "llvm/IR/Instructions.h"
89 #include "llvm/IR/IntrinsicInst.h"
90 #include "llvm/IR/Intrinsics.h"
91 #include "llvm/IR/LLVMContext.h"
92 #include "llvm/IR/PatternMatch.h"
93 #include "llvm/IR/Type.h"
94 #include "llvm/IR/Use.h"
95 #include "llvm/IR/User.h"
96 #include "llvm/IR/Value.h"
97 #include "llvm/InitializePasses.h"
98 #include "llvm/Pass.h"
99 #include "llvm/Support/Allocator.h"
101 #include "llvm/Support/Casting.h"
103 #include "llvm/Support/Debug.h"
108 #include "llvm/Transforms/Scalar.h"
114 #include <algorithm>
115 #include <cassert>
116 #include <cstdint>
117 #include <iterator>
118 #include <map>
119 #include <memory>
120 #include <set>
121 #include <string>
122 #include <tuple>
123 #include <utility>
124 #include <vector>
125 
126 using namespace llvm;
127 using namespace llvm::GVNExpression;
128 using namespace llvm::VNCoercion;
129 using namespace llvm::PatternMatch;
130 
131 #define DEBUG_TYPE "newgvn"
132 
133 STATISTIC(NumGVNInstrDeleted, "Number of instructions deleted");
134 STATISTIC(NumGVNBlocksDeleted, "Number of blocks deleted");
135 STATISTIC(NumGVNOpsSimplified, "Number of Expressions simplified");
136 STATISTIC(NumGVNPhisAllSame, "Number of PHIs whos arguments are all the same");
137 STATISTIC(NumGVNMaxIterations,
138  "Maximum Number of iterations it took to converge GVN");
139 STATISTIC(NumGVNLeaderChanges, "Number of leader changes");
140 STATISTIC(NumGVNSortedLeaderChanges, "Number of sorted leader changes");
141 STATISTIC(NumGVNAvoidedSortedLeaderChanges,
142  "Number of avoided sorted leader changes");
143 STATISTIC(NumGVNDeadStores, "Number of redundant/dead stores eliminated");
144 STATISTIC(NumGVNPHIOfOpsCreated, "Number of PHI of ops created");
145 STATISTIC(NumGVNPHIOfOpsEliminations,
146  "Number of things eliminated using PHI of ops");
147 DEBUG_COUNTER(VNCounter, "newgvn-vn",
148  "Controls which instructions are value numbered");
149 DEBUG_COUNTER(PHIOfOpsCounter, "newgvn-phi",
150  "Controls which instructions we create phi of ops for");
151 // Currently store defining access refinement is too slow due to basicaa being
152 // egregiously slow. This flag lets us keep it working while we work on this
153 // issue.
154 static cl::opt<bool> EnableStoreRefinement("enable-store-refinement",
155  cl::init(false), cl::Hidden);
156 
157 /// Currently, the generation "phi of ops" can result in correctness issues.
158 static cl::opt<bool> EnablePhiOfOps("enable-phi-of-ops", cl::init(true),
159  cl::Hidden);
160 
161 //===----------------------------------------------------------------------===//
162 // GVN Pass
163 //===----------------------------------------------------------------------===//
164 
165 // Anchor methods.
166 namespace llvm {
167 namespace GVNExpression {
168 
169 Expression::~Expression() = default;
176 
177 } // end namespace GVNExpression
178 } // end namespace llvm
179 
180 namespace {
181 
182 // Tarjan's SCC finding algorithm with Nuutila's improvements
183 // SCCIterator is actually fairly complex for the simple thing we want.
184 // It also wants to hand us SCC's that are unrelated to the phi node we ask
185 // about, and have us process them there or risk redoing work.
186 // Graph traits over a filter iterator also doesn't work that well here.
187 // This SCC finder is specialized to walk use-def chains, and only follows
188 // instructions,
189 // not generic values (arguments, etc).
190 struct TarjanSCC {
191  TarjanSCC() : Components(1) {}
192 
193  void Start(const Instruction *Start) {
194  if (Root.lookup(Start) == 0)
195  FindSCC(Start);
196  }
197 
198  const SmallPtrSetImpl<const Value *> &getComponentFor(const Value *V) const {
199  unsigned ComponentID = ValueToComponent.lookup(V);
200 
201  assert(ComponentID > 0 &&
202  "Asking for a component for a value we never processed");
203  return Components[ComponentID];
204  }
205 
206 private:
207  void FindSCC(const Instruction *I) {
208  Root[I] = ++DFSNum;
209  // Store the DFS Number we had before it possibly gets incremented.
210  unsigned int OurDFS = DFSNum;
211  for (auto &Op : I->operands()) {
212  if (auto *InstOp = dyn_cast<Instruction>(Op)) {
213  if (Root.lookup(Op) == 0)
214  FindSCC(InstOp);
215  if (!InComponent.count(Op))
216  Root[I] = std::min(Root.lookup(I), Root.lookup(Op));
217  }
218  }
219  // See if we really were the root of a component, by seeing if we still have
220  // our DFSNumber. If we do, we are the root of the component, and we have
221  // completed a component. If we do not, we are not the root of a component,
222  // and belong on the component stack.
223  if (Root.lookup(I) == OurDFS) {
224  unsigned ComponentID = Components.size();
225  Components.resize(Components.size() + 1);
226  auto &Component = Components.back();
227  Component.insert(I);
228  LLVM_DEBUG(dbgs() << "Component root is " << *I << "\n");
229  InComponent.insert(I);
230  ValueToComponent[I] = ComponentID;
231  // Pop a component off the stack and label it.
232  while (!Stack.empty() && Root.lookup(Stack.back()) >= OurDFS) {
233  auto *Member = Stack.back();
234  LLVM_DEBUG(dbgs() << "Component member is " << *Member << "\n");
235  Component.insert(Member);
236  InComponent.insert(Member);
237  ValueToComponent[Member] = ComponentID;
238  Stack.pop_back();
239  }
240  } else {
241  // Part of a component, push to stack
242  Stack.push_back(I);
243  }
244  }
245 
246  unsigned int DFSNum = 1;
247  SmallPtrSet<const Value *, 8> InComponent;
250 
251  // Store the components as vector of ptr sets, because we need the topo order
252  // of SCC's, but not individual member order
254 
255  DenseMap<const Value *, unsigned> ValueToComponent;
256 };
257 
258 // Congruence classes represent the set of expressions/instructions
259 // that are all the same *during some scope in the function*.
260 // That is, because of the way we perform equality propagation, and
261 // because of memory value numbering, it is not correct to assume
262 // you can willy-nilly replace any member with any other at any
263 // point in the function.
264 //
265 // For any Value in the Member set, it is valid to replace any dominated member
266 // with that Value.
267 //
268 // Every congruence class has a leader, and the leader is used to symbolize
269 // instructions in a canonical way (IE every operand of an instruction that is a
270 // member of the same congruence class will always be replaced with leader
271 // during symbolization). To simplify symbolization, we keep the leader as a
272 // constant if class can be proved to be a constant value. Otherwise, the
273 // leader is the member of the value set with the smallest DFS number. Each
274 // congruence class also has a defining expression, though the expression may be
275 // null. If it exists, it can be used for forward propagation and reassociation
276 // of values.
277 
278 // For memory, we also track a representative MemoryAccess, and a set of memory
279 // members for MemoryPhis (which have no real instructions). Note that for
280 // memory, it seems tempting to try to split the memory members into a
281 // MemoryCongruenceClass or something. Unfortunately, this does not work
282 // easily. The value numbering of a given memory expression depends on the
283 // leader of the memory congruence class, and the leader of memory congruence
284 // class depends on the value numbering of a given memory expression. This
285 // leads to wasted propagation, and in some cases, missed optimization. For
286 // example: If we had value numbered two stores together before, but now do not,
287 // we move them to a new value congruence class. This in turn will move at one
288 // of the memorydefs to a new memory congruence class. Which in turn, affects
289 // the value numbering of the stores we just value numbered (because the memory
290 // congruence class is part of the value number). So while theoretically
291 // possible to split them up, it turns out to be *incredibly* complicated to get
292 // it to work right, because of the interdependency. While structurally
293 // slightly messier, it is algorithmically much simpler and faster to do what we
294 // do here, and track them both at once in the same class.
295 // Note: The default iterators for this class iterate over values
296 class CongruenceClass {
297 public:
298  using MemberType = Value;
299  using MemberSet = SmallPtrSet<MemberType *, 4>;
300  using MemoryMemberType = MemoryPhi;
301  using MemoryMemberSet = SmallPtrSet<const MemoryMemberType *, 2>;
302 
303  explicit CongruenceClass(unsigned ID) : ID(ID) {}
304  CongruenceClass(unsigned ID, Value *Leader, const Expression *E)
305  : ID(ID), RepLeader(Leader), DefiningExpr(E) {}
306 
307  unsigned getID() const { return ID; }
308 
309  // True if this class has no members left. This is mainly used for assertion
310  // purposes, and for skipping empty classes.
311  bool isDead() const {
312  // If it's both dead from a value perspective, and dead from a memory
313  // perspective, it's really dead.
314  return empty() && memory_empty();
315  }
316 
317  // Leader functions
318  Value *getLeader() const { return RepLeader; }
319  void setLeader(Value *Leader) { RepLeader = Leader; }
320  const std::pair<Value *, unsigned int> &getNextLeader() const {
321  return NextLeader;
322  }
323  void resetNextLeader() { NextLeader = {nullptr, ~0}; }
324  void addPossibleNextLeader(std::pair<Value *, unsigned int> LeaderPair) {
325  if (LeaderPair.second < NextLeader.second)
326  NextLeader = LeaderPair;
327  }
328 
329  Value *getStoredValue() const { return RepStoredValue; }
330  void setStoredValue(Value *Leader) { RepStoredValue = Leader; }
331  const MemoryAccess *getMemoryLeader() const { return RepMemoryAccess; }
332  void setMemoryLeader(const MemoryAccess *Leader) { RepMemoryAccess = Leader; }
333 
334  // Forward propagation info
335  const Expression *getDefiningExpr() const { return DefiningExpr; }
336 
337  // Value member set
338  bool empty() const { return Members.empty(); }
339  unsigned size() const { return Members.size(); }
340  MemberSet::const_iterator begin() const { return Members.begin(); }
341  MemberSet::const_iterator end() const { return Members.end(); }
342  void insert(MemberType *M) { Members.insert(M); }
343  void erase(MemberType *M) { Members.erase(M); }
344  void swap(MemberSet &Other) { Members.swap(Other); }
345 
346  // Memory member set
347  bool memory_empty() const { return MemoryMembers.empty(); }
348  unsigned memory_size() const { return MemoryMembers.size(); }
349  MemoryMemberSet::const_iterator memory_begin() const {
350  return MemoryMembers.begin();
351  }
352  MemoryMemberSet::const_iterator memory_end() const {
353  return MemoryMembers.end();
354  }
356  return make_range(memory_begin(), memory_end());
357  }
358 
359  void memory_insert(const MemoryMemberType *M) { MemoryMembers.insert(M); }
360  void memory_erase(const MemoryMemberType *M) { MemoryMembers.erase(M); }
361 
362  // Store count
363  unsigned getStoreCount() const { return StoreCount; }
364  void incStoreCount() { ++StoreCount; }
365  void decStoreCount() {
366  assert(StoreCount != 0 && "Store count went negative");
367  --StoreCount;
368  }
369 
370  // True if this class has no memory members.
371  bool definesNoMemory() const { return StoreCount == 0 && memory_empty(); }
372 
373  // Return true if two congruence classes are equivalent to each other. This
374  // means that every field but the ID number and the dead field are equivalent.
375  bool isEquivalentTo(const CongruenceClass *Other) const {
376  if (!Other)
377  return false;
378  if (this == Other)
379  return true;
380 
381  if (std::tie(StoreCount, RepLeader, RepStoredValue, RepMemoryAccess) !=
382  std::tie(Other->StoreCount, Other->RepLeader, Other->RepStoredValue,
383  Other->RepMemoryAccess))
384  return false;
385  if (DefiningExpr != Other->DefiningExpr)
386  if (!DefiningExpr || !Other->DefiningExpr ||
387  *DefiningExpr != *Other->DefiningExpr)
388  return false;
389 
390  if (Members.size() != Other->Members.size())
391  return false;
392 
393  return llvm::set_is_subset(Members, Other->Members);
394  }
395 
396 private:
397  unsigned ID;
398 
399  // Representative leader.
400  Value *RepLeader = nullptr;
401 
402  // The most dominating leader after our current leader, because the member set
403  // is not sorted and is expensive to keep sorted all the time.
404  std::pair<Value *, unsigned int> NextLeader = {nullptr, ~0U};
405 
406  // If this is represented by a store, the value of the store.
407  Value *RepStoredValue = nullptr;
408 
409  // If this class contains MemoryDefs or MemoryPhis, this is the leading memory
410  // access.
411  const MemoryAccess *RepMemoryAccess = nullptr;
412 
413  // Defining Expression.
414  const Expression *DefiningExpr = nullptr;
415 
416  // Actual members of this class.
417  MemberSet Members;
418 
419  // This is the set of MemoryPhis that exist in the class. MemoryDefs and
420  // MemoryUses have real instructions representing them, so we only need to
421  // track MemoryPhis here.
422  MemoryMemberSet MemoryMembers;
423 
424  // Number of stores in this congruence class.
425  // This is used so we can detect store equivalence changes properly.
426  int StoreCount = 0;
427 };
428 
429 } // end anonymous namespace
430 
431 namespace llvm {
432 
434  const Expression &E;
435 
436  explicit ExactEqualsExpression(const Expression &E) : E(E) {}
437 
438  hash_code getComputedHash() const { return E.getComputedHash(); }
439 
440  bool operator==(const Expression &Other) const {
441  return E.exactlyEquals(Other);
442  }
443 };
444 
445 template <> struct DenseMapInfo<const Expression *> {
446  static const Expression *getEmptyKey() {
447  auto Val = static_cast<uintptr_t>(-1);
448  Val <<= PointerLikeTypeTraits<const Expression *>::NumLowBitsAvailable;
449  return reinterpret_cast<const Expression *>(Val);
450  }
451 
452  static const Expression *getTombstoneKey() {
453  auto Val = static_cast<uintptr_t>(~1U);
454  Val <<= PointerLikeTypeTraits<const Expression *>::NumLowBitsAvailable;
455  return reinterpret_cast<const Expression *>(Val);
456  }
457 
458  static unsigned getHashValue(const Expression *E) {
459  return E->getComputedHash();
460  }
461 
462  static unsigned getHashValue(const ExactEqualsExpression &E) {
463  return E.getComputedHash();
464  }
465 
466  static bool isEqual(const ExactEqualsExpression &LHS, const Expression *RHS) {
467  if (RHS == getTombstoneKey() || RHS == getEmptyKey())
468  return false;
469  return LHS == *RHS;
470  }
471 
472  static bool isEqual(const Expression *LHS, const Expression *RHS) {
473  if (LHS == RHS)
474  return true;
475  if (LHS == getTombstoneKey() || RHS == getTombstoneKey() ||
476  LHS == getEmptyKey() || RHS == getEmptyKey())
477  return false;
478  // Compare hashes before equality. This is *not* what the hashtable does,
479  // since it is computing it modulo the number of buckets, whereas we are
480  // using the full hash keyspace. Since the hashes are precomputed, this
481  // check is *much* faster than equality.
482  if (LHS->getComputedHash() != RHS->getComputedHash())
483  return false;
484  return *LHS == *RHS;
485  }
486 };
487 
488 } // end namespace llvm
489 
490 namespace {
491 
492 class NewGVN {
493  Function &F;
494  DominatorTree *DT = nullptr;
495  const TargetLibraryInfo *TLI = nullptr;
496  AliasAnalysis *AA = nullptr;
497  MemorySSA *MSSA = nullptr;
498  MemorySSAWalker *MSSAWalker = nullptr;
499  AssumptionCache *AC = nullptr;
500  const DataLayout &DL;
501  std::unique_ptr<PredicateInfo> PredInfo;
502 
503  // These are the only two things the create* functions should have
504  // side-effects on due to allocating memory.
505  mutable BumpPtrAllocator ExpressionAllocator;
506  mutable ArrayRecycler<Value *> ArgRecycler;
507  mutable TarjanSCC SCCFinder;
508  const SimplifyQuery SQ;
509 
510  // Number of function arguments, used by ranking
511  unsigned int NumFuncArgs = 0;
512 
513  // RPOOrdering of basic blocks
515 
516  // Congruence class info.
517 
518  // This class is called INITIAL in the paper. It is the class everything
519  // startsout in, and represents any value. Being an optimistic analysis,
520  // anything in the TOP class has the value TOP, which is indeterminate and
521  // equivalent to everything.
522  CongruenceClass *TOPClass = nullptr;
523  std::vector<CongruenceClass *> CongruenceClasses;
524  unsigned NextCongruenceNum = 0;
525 
526  // Value Mappings.
528  DenseMap<Value *, const Expression *> ValueToExpression;
529 
530  // Value PHI handling, used to make equivalence between phi(op, op) and
531  // op(phi, phi).
532  // These mappings just store various data that would normally be part of the
533  // IR.
535 
536  DenseMap<const Value *, bool> OpSafeForPHIOfOps;
537 
538  // Map a temporary instruction we created to a parent block.
540 
541  // Map between the already in-program instructions and the temporary phis we
542  // created that they are known equivalent to.
544 
545  // In order to know when we should re-process instructions that have
546  // phi-of-ops, we track the set of expressions that they needed as
547  // leaders. When we discover new leaders for those expressions, we process the
548  // associated phi-of-op instructions again in case they have changed. The
549  // other way they may change is if they had leaders, and those leaders
550  // disappear. However, at the point they have leaders, there are uses of the
551  // relevant operands in the created phi node, and so they will get reprocessed
552  // through the normal user marking we perform.
553  mutable DenseMap<const Value *, SmallPtrSet<Value *, 2>> AdditionalUsers;
555  ExpressionToPhiOfOps;
556 
557  // Map from temporary operation to MemoryAccess.
559 
560  // Set of all temporary instructions we created.
561  // Note: This will include instructions that were just created during value
562  // numbering. The way to test if something is using them is to check
563  // RealToTemp.
564  DenseSet<Instruction *> AllTempInstructions;
565 
566  // This is the set of instructions to revisit on a reachability change. At
567  // the end of the main iteration loop it will contain at least all the phi of
568  // ops instructions that will be changed to phis, as well as regular phis.
569  // During the iteration loop, it may contain other things, such as phi of ops
570  // instructions that used edge reachability to reach a result, and so need to
571  // be revisited when the edge changes, independent of whether the phi they
572  // depended on changes.
573  DenseMap<BasicBlock *, SparseBitVector<>> RevisitOnReachabilityChange;
574 
575  // Mapping from predicate info we used to the instructions we used it with.
576  // In order to correctly ensure propagation, we must keep track of what
577  // comparisons we used, so that when the values of the comparisons change, we
578  // propagate the information to the places we used the comparison.
580  PredicateToUsers;
581 
582  // the same reasoning as PredicateToUsers. When we skip MemoryAccesses for
583  // stores, we no longer can rely solely on the def-use chains of MemorySSA.
585  MemoryToUsers;
586 
587  // A table storing which memorydefs/phis represent a memory state provably
588  // equivalent to another memory state.
589  // We could use the congruence class machinery, but the MemoryAccess's are
590  // abstract memory states, so they can only ever be equivalent to each other,
591  // and not to constants, etc.
593 
594  // We could, if we wanted, build MemoryPhiExpressions and
595  // MemoryVariableExpressions, etc, and value number them the same way we value
596  // number phi expressions. For the moment, this seems like overkill. They
597  // can only exist in one of three states: they can be TOP (equal to
598  // everything), Equivalent to something else, or unique. Because we do not
599  // create expressions for them, we need to simulate leader change not just
600  // when they change class, but when they change state. Note: We can do the
601  // same thing for phis, and avoid having phi expressions if we wanted, We
602  // should eventually unify in one direction or the other, so this is a little
603  // bit of an experiment in which turns out easier to maintain.
604  enum MemoryPhiState { MPS_Invalid, MPS_TOP, MPS_Equivalent, MPS_Unique };
606 
607  enum InstCycleState { ICS_Unknown, ICS_CycleFree, ICS_Cycle };
608  mutable DenseMap<const Instruction *, InstCycleState> InstCycleState;
609 
610  // Expression to class mapping.
611  using ExpressionClassMap = DenseMap<const Expression *, CongruenceClass *>;
612  ExpressionClassMap ExpressionToClass;
613 
614  // We have a single expression that represents currently DeadExpressions.
615  // For dead expressions we can prove will stay dead, we mark them with
616  // DFS number zero. However, it's possible in the case of phi nodes
617  // for us to assume/prove all arguments are dead during fixpointing.
618  // We use DeadExpression for that case.
619  DeadExpression *SingletonDeadExpression = nullptr;
620 
621  // Which values have changed as a result of leader changes.
622  SmallPtrSet<Value *, 8> LeaderChanges;
623 
624  // Reachability info.
625  using BlockEdge = BasicBlockEdge;
626  DenseSet<BlockEdge> ReachableEdges;
627  SmallPtrSet<const BasicBlock *, 8> ReachableBlocks;
628 
629  // This is a bitvector because, on larger functions, we may have
630  // thousands of touched instructions at once (entire blocks,
631  // instructions with hundreds of uses, etc). Even with optimization
632  // for when we mark whole blocks as touched, when this was a
633  // SmallPtrSet or DenseSet, for some functions, we spent >20% of all
634  // the time in GVN just managing this list. The bitvector, on the
635  // other hand, efficiently supports test/set/clear of both
636  // individual and ranges, as well as "find next element" This
637  // enables us to use it as a worklist with essentially 0 cost.
638  BitVector TouchedInstructions;
639 
641 
642 #ifndef NDEBUG
643  // Debugging for how many times each block and instruction got processed.
644  DenseMap<const Value *, unsigned> ProcessedCount;
645 #endif
646 
647  // DFS info.
648  // This contains a mapping from Instructions to DFS numbers.
649  // The numbering starts at 1. An instruction with DFS number zero
650  // means that the instruction is dead.
652 
653  // This contains the mapping DFS numbers to instructions.
654  SmallVector<Value *, 32> DFSToInstr;
655 
656  // Deletion info.
657  SmallPtrSet<Instruction *, 8> InstructionsToErase;
658 
659 public:
660  NewGVN(Function &F, DominatorTree *DT, AssumptionCache *AC,
661  TargetLibraryInfo *TLI, AliasAnalysis *AA, MemorySSA *MSSA,
662  const DataLayout &DL)
663  : F(F), DT(DT), TLI(TLI), AA(AA), MSSA(MSSA), AC(AC), DL(DL),
664  PredInfo(std::make_unique<PredicateInfo>(F, *DT, *AC)),
665  SQ(DL, TLI, DT, AC, /*CtxI=*/nullptr, /*UseInstrInfo=*/false,
666  /*CanUseUndef=*/false) {}
667 
668  bool runGVN();
669 
670 private:
671  /// Helper struct return a Expression with an optional extra dependency.
672  struct ExprResult {
673  const Expression *Expr;
674  Value *ExtraDep;
675  const PredicateBase *PredDep;
676 
677  ExprResult(const Expression *Expr, Value *ExtraDep = nullptr,
678  const PredicateBase *PredDep = nullptr)
679  : Expr(Expr), ExtraDep(ExtraDep), PredDep(PredDep) {}
680  ExprResult(const ExprResult &) = delete;
681  ExprResult(ExprResult &&Other)
682  : Expr(Other.Expr), ExtraDep(Other.ExtraDep), PredDep(Other.PredDep) {
683  Other.Expr = nullptr;
684  Other.ExtraDep = nullptr;
685  Other.PredDep = nullptr;
686  }
687  ExprResult &operator=(const ExprResult &Other) = delete;
688  ExprResult &operator=(ExprResult &&Other) = delete;
689 
690  ~ExprResult() { assert(!ExtraDep && "unhandled ExtraDep"); }
691 
692  operator bool() const { return Expr; }
693 
694  static ExprResult none() { return {nullptr, nullptr, nullptr}; }
695  static ExprResult some(const Expression *Expr, Value *ExtraDep = nullptr) {
696  return {Expr, ExtraDep, nullptr};
697  }
698  static ExprResult some(const Expression *Expr,
699  const PredicateBase *PredDep) {
700  return {Expr, nullptr, PredDep};
701  }
702  static ExprResult some(const Expression *Expr, Value *ExtraDep,
703  const PredicateBase *PredDep) {
704  return {Expr, ExtraDep, PredDep};
705  }
706  };
707 
708  // Expression handling.
709  ExprResult createExpression(Instruction *) const;
710  const Expression *createBinaryExpression(unsigned, Type *, Value *, Value *,
711  Instruction *) const;
712 
713  // Our canonical form for phi arguments is a pair of incoming value, incoming
714  // basic block.
715  using ValPair = std::pair<Value *, BasicBlock *>;
716 
717  PHIExpression *createPHIExpression(ArrayRef<ValPair>, const Instruction *,
718  BasicBlock *, bool &HasBackEdge,
719  bool &OriginalOpsConstant) const;
720  const DeadExpression *createDeadExpression() const;
721  const VariableExpression *createVariableExpression(Value *) const;
722  const ConstantExpression *createConstantExpression(Constant *) const;
723  const Expression *createVariableOrConstant(Value *V) const;
724  const UnknownExpression *createUnknownExpression(Instruction *) const;
725  const StoreExpression *createStoreExpression(StoreInst *,
726  const MemoryAccess *) const;
727  LoadExpression *createLoadExpression(Type *, Value *, LoadInst *,
728  const MemoryAccess *) const;
729  const CallExpression *createCallExpression(CallInst *,
730  const MemoryAccess *) const;
732  createAggregateValueExpression(Instruction *) const;
733  bool setBasicExpressionInfo(Instruction *, BasicExpression *) const;
734 
735  // Congruence class handling.
736  CongruenceClass *createCongruenceClass(Value *Leader, const Expression *E) {
737  auto *result = new CongruenceClass(NextCongruenceNum++, Leader, E);
738  CongruenceClasses.emplace_back(result);
739  return result;
740  }
741 
742  CongruenceClass *createMemoryClass(MemoryAccess *MA) {
743  auto *CC = createCongruenceClass(nullptr, nullptr);
744  CC->setMemoryLeader(MA);
745  return CC;
746  }
747 
748  CongruenceClass *ensureLeaderOfMemoryClass(MemoryAccess *MA) {
749  auto *CC = getMemoryClass(MA);
750  if (CC->getMemoryLeader() != MA)
751  CC = createMemoryClass(MA);
752  return CC;
753  }
754 
755  CongruenceClass *createSingletonCongruenceClass(Value *Member) {
756  CongruenceClass *CClass = createCongruenceClass(Member, nullptr);
757  CClass->insert(Member);
758  ValueToClass[Member] = CClass;
759  return CClass;
760  }
761 
762  void initializeCongruenceClasses(Function &F);
763  const Expression *makePossiblePHIOfOps(Instruction *,
765  Value *findLeaderForInst(Instruction *ValueOp,
766  SmallPtrSetImpl<Value *> &Visited,
767  MemoryAccess *MemAccess, Instruction *OrigInst,
768  BasicBlock *PredBB);
769  bool OpIsSafeForPHIOfOpsHelper(Value *V, const BasicBlock *PHIBlock,
772  bool OpIsSafeForPHIOfOps(Value *Op, const BasicBlock *PHIBlock,
774  void addPhiOfOps(PHINode *Op, BasicBlock *BB, Instruction *ExistingValue);
775  void removePhiOfOps(Instruction *I, PHINode *PHITemp);
776 
777  // Value number an Instruction or MemoryPhi.
778  void valueNumberMemoryPhi(MemoryPhi *);
779  void valueNumberInstruction(Instruction *);
780 
781  // Symbolic evaluation.
782  ExprResult checkExprResults(Expression *, Instruction *, Value *) const;
783  ExprResult performSymbolicEvaluation(Value *,
784  SmallPtrSetImpl<Value *> &) const;
785  const Expression *performSymbolicLoadCoercion(Type *, Value *, LoadInst *,
786  Instruction *,
787  MemoryAccess *) const;
788  const Expression *performSymbolicLoadEvaluation(Instruction *) const;
789  const Expression *performSymbolicStoreEvaluation(Instruction *) const;
790  ExprResult performSymbolicCallEvaluation(Instruction *) const;
791  void sortPHIOps(MutableArrayRef<ValPair> Ops) const;
792  const Expression *performSymbolicPHIEvaluation(ArrayRef<ValPair>,
793  Instruction *I,
794  BasicBlock *PHIBlock) const;
795  const Expression *performSymbolicAggrValueEvaluation(Instruction *) const;
796  ExprResult performSymbolicCmpEvaluation(Instruction *) const;
797  ExprResult performSymbolicPredicateInfoEvaluation(Instruction *) const;
798 
799  // Congruence finding.
800  bool someEquivalentDominates(const Instruction *, const Instruction *) const;
801  Value *lookupOperandLeader(Value *) const;
802  CongruenceClass *getClassForExpression(const Expression *E) const;
803  void performCongruenceFinding(Instruction *, const Expression *);
804  void moveValueToNewCongruenceClass(Instruction *, const Expression *,
805  CongruenceClass *, CongruenceClass *);
806  void moveMemoryToNewCongruenceClass(Instruction *, MemoryAccess *,
807  CongruenceClass *, CongruenceClass *);
808  Value *getNextValueLeader(CongruenceClass *) const;
809  const MemoryAccess *getNextMemoryLeader(CongruenceClass *) const;
810  bool setMemoryClass(const MemoryAccess *From, CongruenceClass *To);
811  CongruenceClass *getMemoryClass(const MemoryAccess *MA) const;
812  const MemoryAccess *lookupMemoryLeader(const MemoryAccess *) const;
813  bool isMemoryAccessTOP(const MemoryAccess *) const;
814 
815  // Ranking
816  unsigned int getRank(const Value *) const;
817  bool shouldSwapOperands(const Value *, const Value *) const;
818 
819  // Reachability handling.
820  void updateReachableEdge(BasicBlock *, BasicBlock *);
821  void processOutgoingEdges(Instruction *, BasicBlock *);
822  Value *findConditionEquivalence(Value *) const;
823 
824  // Elimination.
825  struct ValueDFS;
826  void convertClassToDFSOrdered(const CongruenceClass &,
830  void convertClassToLoadsAndStores(const CongruenceClass &,
831  SmallVectorImpl<ValueDFS> &) const;
832 
833  bool eliminateInstructions(Function &);
834  void replaceInstruction(Instruction *, Value *);
835  void markInstructionForDeletion(Instruction *);
836  void deleteInstructionsInBlock(BasicBlock *);
837  Value *findPHIOfOpsLeader(const Expression *, const Instruction *,
838  const BasicBlock *) const;
839 
840  // Various instruction touch utilities
841  template <typename Map, typename KeyType>
842  void touchAndErase(Map &, const KeyType &);
843  void markUsersTouched(Value *);
844  void markMemoryUsersTouched(const MemoryAccess *);
845  void markMemoryDefTouched(const MemoryAccess *);
846  void markPredicateUsersTouched(Instruction *);
847  void markValueLeaderChangeTouched(CongruenceClass *CC);
848  void markMemoryLeaderChangeTouched(CongruenceClass *CC);
849  void markPhiOfOpsChanged(const Expression *E);
850  void addMemoryUsers(const MemoryAccess *To, MemoryAccess *U) const;
851  void addAdditionalUsers(Value *To, Value *User) const;
852  void addAdditionalUsers(ExprResult &Res, Instruction *User) const;
853 
854  // Main loop of value numbering
855  void iterateTouchedInstructions();
856 
857  // Utilities.
858  void cleanupTables();
859  std::pair<unsigned, unsigned> assignDFSNumbers(BasicBlock *, unsigned);
860  void updateProcessedCount(const Value *V);
861  void verifyMemoryCongruency() const;
862  void verifyIterationSettled(Function &F);
863  void verifyStoreExpressions() const;
864  bool singleReachablePHIPath(SmallPtrSet<const MemoryAccess *, 8> &,
865  const MemoryAccess *, const MemoryAccess *) const;
866  BasicBlock *getBlockForValue(Value *V) const;
867  void deleteExpression(const Expression *E) const;
868  MemoryUseOrDef *getMemoryAccess(const Instruction *) const;
869  MemoryPhi *getMemoryAccess(const BasicBlock *) const;
870  template <class T, class Range> T *getMinDFSOfRange(const Range &) const;
871 
872  unsigned InstrToDFSNum(const Value *V) const {
873  assert(isa<Instruction>(V) && "This should not be used for MemoryAccesses");
874  return InstrDFS.lookup(V);
875  }
876 
877  unsigned InstrToDFSNum(const MemoryAccess *MA) const {
878  return MemoryToDFSNum(MA);
879  }
880 
881  Value *InstrFromDFSNum(unsigned DFSNum) { return DFSToInstr[DFSNum]; }
882 
883  // Given a MemoryAccess, return the relevant instruction DFS number. Note:
884  // This deliberately takes a value so it can be used with Use's, which will
885  // auto-convert to Value's but not to MemoryAccess's.
886  unsigned MemoryToDFSNum(const Value *MA) const {
887  assert(isa<MemoryAccess>(MA) &&
888  "This should not be used with instructions");
889  return isa<MemoryUseOrDef>(MA)
890  ? InstrToDFSNum(cast<MemoryUseOrDef>(MA)->getMemoryInst())
891  : InstrDFS.lookup(MA);
892  }
893 
894  bool isCycleFree(const Instruction *) const;
895  bool isBackedge(BasicBlock *From, BasicBlock *To) const;
896 
897  // Debug counter info. When verifying, we have to reset the value numbering
898  // debug counter to the same state it started in to get the same results.
899  int64_t StartingVNCounter = 0;
900 };
901 
902 } // end anonymous namespace
903 
904 template <typename T>
905 static bool equalsLoadStoreHelper(const T &LHS, const Expression &RHS) {
906  if (!isa<LoadExpression>(RHS) && !isa<StoreExpression>(RHS))
907  return false;
908  return LHS.MemoryExpression::equals(RHS);
909 }
910 
912  return equalsLoadStoreHelper(*this, Other);
913 }
914 
916  if (!equalsLoadStoreHelper(*this, Other))
917  return false;
918  // Make sure that store vs store includes the value operand.
919  if (const auto *S = dyn_cast<StoreExpression>(&Other))
920  if (getStoredValue() != S->getStoredValue())
921  return false;
922  return true;
923 }
924 
925 // Determine if the edge From->To is a backedge
926 bool NewGVN::isBackedge(BasicBlock *From, BasicBlock *To) const {
927  return From == To ||
928  RPOOrdering.lookup(DT->getNode(From)) >=
929  RPOOrdering.lookup(DT->getNode(To));
930 }
931 
932 #ifndef NDEBUG
933 static std::string getBlockName(const BasicBlock *B) {
935 }
936 #endif
937 
938 // Get a MemoryAccess for an instruction, fake or real.
939 MemoryUseOrDef *NewGVN::getMemoryAccess(const Instruction *I) const {
940  auto *Result = MSSA->getMemoryAccess(I);
941  return Result ? Result : TempToMemory.lookup(I);
942 }
943 
944 // Get a MemoryPhi for a basic block. These are all real.
945 MemoryPhi *NewGVN::getMemoryAccess(const BasicBlock *BB) const {
946  return MSSA->getMemoryAccess(BB);
947 }
948 
949 // Get the basic block from an instruction/memory value.
950 BasicBlock *NewGVN::getBlockForValue(Value *V) const {
951  if (auto *I = dyn_cast<Instruction>(V)) {
952  auto *Parent = I->getParent();
953  if (Parent)
954  return Parent;
955  Parent = TempToBlock.lookup(V);
956  assert(Parent && "Every fake instruction should have a block");
957  return Parent;
958  }
959 
960  auto *MP = dyn_cast<MemoryPhi>(V);
961  assert(MP && "Should have been an instruction or a MemoryPhi");
962  return MP->getBlock();
963 }
964 
965 // Delete a definitely dead expression, so it can be reused by the expression
966 // allocator. Some of these are not in creation functions, so we have to accept
967 // const versions.
968 void NewGVN::deleteExpression(const Expression *E) const {
969  assert(isa<BasicExpression>(E));
970  auto *BE = cast<BasicExpression>(E);
971  const_cast<BasicExpression *>(BE)->deallocateOperands(ArgRecycler);
972  ExpressionAllocator.Deallocate(E);
973 }
974 
975 // If V is a predicateinfo copy, get the thing it is a copy of.
976 static Value *getCopyOf(const Value *V) {
977  if (auto *II = dyn_cast<IntrinsicInst>(V))
978  if (II->getIntrinsicID() == Intrinsic::ssa_copy)
979  return II->getOperand(0);
980  return nullptr;
981 }
982 
983 // Return true if V is really PN, even accounting for predicateinfo copies.
984 static bool isCopyOfPHI(const Value *V, const PHINode *PN) {
985  return V == PN || getCopyOf(V) == PN;
986 }
987 
988 static bool isCopyOfAPHI(const Value *V) {
989  auto *CO = getCopyOf(V);
990  return CO && isa<PHINode>(CO);
991 }
992 
993 // Sort PHI Operands into a canonical order. What we use here is an RPO
994 // order. The BlockInstRange numbers are generated in an RPO walk of the basic
995 // blocks.
996 void NewGVN::sortPHIOps(MutableArrayRef<ValPair> Ops) const {
997  llvm::sort(Ops, [&](const ValPair &P1, const ValPair &P2) {
998  return BlockInstRange.lookup(P1.second).first <
999  BlockInstRange.lookup(P2.second).first;
1000  });
1001 }
1002 
1003 // Return true if V is a value that will always be available (IE can
1004 // be placed anywhere) in the function. We don't do globals here
1005 // because they are often worse to put in place.
1006 static bool alwaysAvailable(Value *V) {
1007  return isa<Constant>(V) || isa<Argument>(V);
1008 }
1009 
1010 // Create a PHIExpression from an array of {incoming edge, value} pairs. I is
1011 // the original instruction we are creating a PHIExpression for (but may not be
1012 // a phi node). We require, as an invariant, that all the PHIOperands in the
1013 // same block are sorted the same way. sortPHIOps will sort them into a
1014 // canonical order.
1015 PHIExpression *NewGVN::createPHIExpression(ArrayRef<ValPair> PHIOperands,
1016  const Instruction *I,
1017  BasicBlock *PHIBlock,
1018  bool &HasBackedge,
1019  bool &OriginalOpsConstant) const {
1020  unsigned NumOps = PHIOperands.size();
1021  auto *E = new (ExpressionAllocator) PHIExpression(NumOps, PHIBlock);
1022 
1023  E->allocateOperands(ArgRecycler, ExpressionAllocator);
1024  E->setType(PHIOperands.begin()->first->getType());
1025  E->setOpcode(Instruction::PHI);
1026 
1027  // Filter out unreachable phi operands.
1028  auto Filtered = make_filter_range(PHIOperands, [&](const ValPair &P) {
1029  auto *BB = P.second;
1030  if (auto *PHIOp = dyn_cast<PHINode>(I))
1031  if (isCopyOfPHI(P.first, PHIOp))
1032  return false;
1033  if (!ReachableEdges.count({BB, PHIBlock}))
1034  return false;
1035  // Things in TOPClass are equivalent to everything.
1036  if (ValueToClass.lookup(P.first) == TOPClass)
1037  return false;
1038  OriginalOpsConstant = OriginalOpsConstant && isa<Constant>(P.first);
1039  HasBackedge = HasBackedge || isBackedge(BB, PHIBlock);
1040  return lookupOperandLeader(P.first) != I;
1041  });
1042  std::transform(Filtered.begin(), Filtered.end(), op_inserter(E),
1043  [&](const ValPair &P) -> Value * {
1044  return lookupOperandLeader(P.first);
1045  });
1046  return E;
1047 }
1048 
1049 // Set basic expression info (Arguments, type, opcode) for Expression
1050 // E from Instruction I in block B.
1051 bool NewGVN::setBasicExpressionInfo(Instruction *I, BasicExpression *E) const {
1052  bool AllConstant = true;
1053  if (auto *GEP = dyn_cast<GetElementPtrInst>(I))
1054  E->setType(GEP->getSourceElementType());
1055  else
1056  E->setType(I->getType());
1057  E->setOpcode(I->getOpcode());
1058  E->allocateOperands(ArgRecycler, ExpressionAllocator);
1059 
1060  // Transform the operand array into an operand leader array, and keep track of
1061  // whether all members are constant.
1062  std::transform(I->op_begin(), I->op_end(), op_inserter(E), [&](Value *O) {
1063  auto Operand = lookupOperandLeader(O);
1064  AllConstant = AllConstant && isa<Constant>(Operand);
1065  return Operand;
1066  });
1067 
1068  return AllConstant;
1069 }
1070 
1071 const Expression *NewGVN::createBinaryExpression(unsigned Opcode, Type *T,
1072  Value *Arg1, Value *Arg2,
1073  Instruction *I) const {
1074  auto *E = new (ExpressionAllocator) BasicExpression(2);
1075 
1076  E->setType(T);
1077  E->setOpcode(Opcode);
1078  E->allocateOperands(ArgRecycler, ExpressionAllocator);
1079  if (Instruction::isCommutative(Opcode)) {
1080  // Ensure that commutative instructions that only differ by a permutation
1081  // of their operands get the same value number by sorting the operand value
1082  // numbers. Since all commutative instructions have two operands it is more
1083  // efficient to sort by hand rather than using, say, std::sort.
1084  if (shouldSwapOperands(Arg1, Arg2))
1085  std::swap(Arg1, Arg2);
1086  }
1087  E->op_push_back(lookupOperandLeader(Arg1));
1088  E->op_push_back(lookupOperandLeader(Arg2));
1089 
1090  Value *V = SimplifyBinOp(Opcode, E->getOperand(0), E->getOperand(1), SQ);
1091  if (auto Simplified = checkExprResults(E, I, V)) {
1092  addAdditionalUsers(Simplified, I);
1093  return Simplified.Expr;
1094  }
1095  return E;
1096 }
1097 
1098 // Take a Value returned by simplification of Expression E/Instruction
1099 // I, and see if it resulted in a simpler expression. If so, return
1100 // that expression.
1101 NewGVN::ExprResult NewGVN::checkExprResults(Expression *E, Instruction *I,
1102  Value *V) const {
1103  if (!V)
1104  return ExprResult::none();
1105 
1106  if (auto *C = dyn_cast<Constant>(V)) {
1107  if (I)
1108  LLVM_DEBUG(dbgs() << "Simplified " << *I << " to "
1109  << " constant " << *C << "\n");
1110  NumGVNOpsSimplified++;
1111  assert(isa<BasicExpression>(E) &&
1112  "We should always have had a basic expression here");
1113  deleteExpression(E);
1114  return ExprResult::some(createConstantExpression(C));
1115  } else if (isa<Argument>(V) || isa<GlobalVariable>(V)) {
1116  if (I)
1117  LLVM_DEBUG(dbgs() << "Simplified " << *I << " to "
1118  << " variable " << *V << "\n");
1119  deleteExpression(E);
1120  return ExprResult::some(createVariableExpression(V));
1121  }
1122 
1123  CongruenceClass *CC = ValueToClass.lookup(V);
1124  if (CC) {
1125  if (CC->getLeader() && CC->getLeader() != I) {
1126  return ExprResult::some(createVariableOrConstant(CC->getLeader()), V);
1127  }
1128  if (CC->getDefiningExpr()) {
1129  if (I)
1130  LLVM_DEBUG(dbgs() << "Simplified " << *I << " to "
1131  << " expression " << *CC->getDefiningExpr() << "\n");
1132  NumGVNOpsSimplified++;
1133  deleteExpression(E);
1134  return ExprResult::some(CC->getDefiningExpr(), V);
1135  }
1136  }
1137 
1138  return ExprResult::none();
1139 }
1140 
1141 // Create a value expression from the instruction I, replacing operands with
1142 // their leaders.
1143 
1144 NewGVN::ExprResult NewGVN::createExpression(Instruction *I) const {
1145  auto *E = new (ExpressionAllocator) BasicExpression(I->getNumOperands());
1146 
1147  bool AllConstant = setBasicExpressionInfo(I, E);
1148 
1149  if (I->isCommutative()) {
1150  // Ensure that commutative instructions that only differ by a permutation
1151  // of their operands get the same value number by sorting the operand value
1152  // numbers. Since all commutative instructions have two operands it is more
1153  // efficient to sort by hand rather than using, say, std::sort.
1154  assert(I->getNumOperands() == 2 && "Unsupported commutative instruction!");
1155  if (shouldSwapOperands(E->getOperand(0), E->getOperand(1)))
1156  E->swapOperands(0, 1);
1157  }
1158  // Perform simplification.
1159  if (auto *CI = dyn_cast<CmpInst>(I)) {
1160  // Sort the operand value numbers so x<y and y>x get the same value
1161  // number.
1162  CmpInst::Predicate Predicate = CI->getPredicate();
1163  if (shouldSwapOperands(E->getOperand(0), E->getOperand(1))) {
1164  E->swapOperands(0, 1);
1166  }
1167  E->setOpcode((CI->getOpcode() << 8) | Predicate);
1168  // TODO: 25% of our time is spent in SimplifyCmpInst with pointer operands
1169  assert(I->getOperand(0)->getType() == I->getOperand(1)->getType() &&
1170  "Wrong types on cmp instruction");
1171  assert((E->getOperand(0)->getType() == I->getOperand(0)->getType() &&
1172  E->getOperand(1)->getType() == I->getOperand(1)->getType()));
1173  Value *V =
1174  SimplifyCmpInst(Predicate, E->getOperand(0), E->getOperand(1), SQ);
1175  if (auto Simplified = checkExprResults(E, I, V))
1176  return Simplified;
1177  } else if (isa<SelectInst>(I)) {
1178  if (isa<Constant>(E->getOperand(0)) ||
1179  E->getOperand(1) == E->getOperand(2)) {
1180  assert(E->getOperand(1)->getType() == I->getOperand(1)->getType() &&
1181  E->getOperand(2)->getType() == I->getOperand(2)->getType());
1182  Value *V = SimplifySelectInst(E->getOperand(0), E->getOperand(1),
1183  E->getOperand(2), SQ);
1184  if (auto Simplified = checkExprResults(E, I, V))
1185  return Simplified;
1186  }
1187  } else if (I->isBinaryOp()) {
1188  Value *V =
1189  SimplifyBinOp(E->getOpcode(), E->getOperand(0), E->getOperand(1), SQ);
1190  if (auto Simplified = checkExprResults(E, I, V))
1191  return Simplified;
1192  } else if (auto *CI = dyn_cast<CastInst>(I)) {
1193  Value *V =
1194  SimplifyCastInst(CI->getOpcode(), E->getOperand(0), CI->getType(), SQ);
1195  if (auto Simplified = checkExprResults(E, I, V))
1196  return Simplified;
1197  } else if (isa<GetElementPtrInst>(I)) {
1198  Value *V = SimplifyGEPInst(
1199  E->getType(), ArrayRef<Value *>(E->op_begin(), E->op_end()), SQ);
1200  if (auto Simplified = checkExprResults(E, I, V))
1201  return Simplified;
1202  } else if (AllConstant) {
1203  // We don't bother trying to simplify unless all of the operands
1204  // were constant.
1205  // TODO: There are a lot of Simplify*'s we could call here, if we
1206  // wanted to. The original motivating case for this code was a
1207  // zext i1 false to i8, which we don't have an interface to
1208  // simplify (IE there is no SimplifyZExt).
1209 
1211  for (Value *Arg : E->operands())
1212  C.emplace_back(cast<Constant>(Arg));
1213 
1214  if (Value *V = ConstantFoldInstOperands(I, C, DL, TLI))
1215  if (auto Simplified = checkExprResults(E, I, V))
1216  return Simplified;
1217  }
1218  return ExprResult::some(E);
1219 }
1220 
1222 NewGVN::createAggregateValueExpression(Instruction *I) const {
1223  if (auto *II = dyn_cast<InsertValueInst>(I)) {
1224  auto *E = new (ExpressionAllocator)
1225  AggregateValueExpression(I->getNumOperands(), II->getNumIndices());
1226  setBasicExpressionInfo(I, E);
1227  E->allocateIntOperands(ExpressionAllocator);
1228  std::copy(II->idx_begin(), II->idx_end(), int_op_inserter(E));
1229  return E;
1230  } else if (auto *EI = dyn_cast<ExtractValueInst>(I)) {
1231  auto *E = new (ExpressionAllocator)
1232  AggregateValueExpression(I->getNumOperands(), EI->getNumIndices());
1233  setBasicExpressionInfo(EI, E);
1234  E->allocateIntOperands(ExpressionAllocator);
1235  std::copy(EI->idx_begin(), EI->idx_end(), int_op_inserter(E));
1236  return E;
1237  }
1238  llvm_unreachable("Unhandled type of aggregate value operation");
1239 }
1240 
1241 const DeadExpression *NewGVN::createDeadExpression() const {
1242  // DeadExpression has no arguments and all DeadExpression's are the same,
1243  // so we only need one of them.
1244  return SingletonDeadExpression;
1245 }
1246 
1247 const VariableExpression *NewGVN::createVariableExpression(Value *V) const {
1248  auto *E = new (ExpressionAllocator) VariableExpression(V);
1249  E->setOpcode(V->getValueID());
1250  return E;
1251 }
1252 
1253 const Expression *NewGVN::createVariableOrConstant(Value *V) const {
1254  if (auto *C = dyn_cast<Constant>(V))
1255  return createConstantExpression(C);
1256  return createVariableExpression(V);
1257 }
1258 
1259 const ConstantExpression *NewGVN::createConstantExpression(Constant *C) const {
1260  auto *E = new (ExpressionAllocator) ConstantExpression(C);
1261  E->setOpcode(C->getValueID());
1262  return E;
1263 }
1264 
1265 const UnknownExpression *NewGVN::createUnknownExpression(Instruction *I) const {
1266  auto *E = new (ExpressionAllocator) UnknownExpression(I);
1267  E->setOpcode(I->getOpcode());
1268  return E;
1269 }
1270 
1271 const CallExpression *
1272 NewGVN::createCallExpression(CallInst *CI, const MemoryAccess *MA) const {
1273  // FIXME: Add operand bundles for calls.
1274  // FIXME: Allow commutative matching for intrinsics.
1275  auto *E =
1276  new (ExpressionAllocator) CallExpression(CI->getNumOperands(), CI, MA);
1277  setBasicExpressionInfo(CI, E);
1278  return E;
1279 }
1280 
1281 // Return true if some equivalent of instruction Inst dominates instruction U.
1282 bool NewGVN::someEquivalentDominates(const Instruction *Inst,
1283  const Instruction *U) const {
1284  auto *CC = ValueToClass.lookup(Inst);
1285  // This must be an instruction because we are only called from phi nodes
1286  // in the case that the value it needs to check against is an instruction.
1287 
1288  // The most likely candidates for dominance are the leader and the next leader.
1289  // The leader or nextleader will dominate in all cases where there is an
1290  // equivalent that is higher up in the dom tree.
1291  // We can't *only* check them, however, because the
1292  // dominator tree could have an infinite number of non-dominating siblings
1293  // with instructions that are in the right congruence class.
1294  // A
1295  // B C D E F G
1296  // |
1297  // H
1298  // Instruction U could be in H, with equivalents in every other sibling.
1299  // Depending on the rpo order picked, the leader could be the equivalent in
1300  // any of these siblings.
1301  if (!CC)
1302  return false;
1303  if (alwaysAvailable(CC->getLeader()))
1304  return true;
1305  if (DT->dominates(cast<Instruction>(CC->getLeader()), U))
1306  return true;
1307  if (CC->getNextLeader().first &&
1308  DT->dominates(cast<Instruction>(CC->getNextLeader().first), U))
1309  return true;
1310  return llvm::any_of(*CC, [&](const Value *Member) {
1311  return Member != CC->getLeader() &&
1312  DT->dominates(cast<Instruction>(Member), U);
1313  });
1314 }
1315 
1316 // See if we have a congruence class and leader for this operand, and if so,
1317 // return it. Otherwise, return the operand itself.
1318 Value *NewGVN::lookupOperandLeader(Value *V) const {
1319  CongruenceClass *CC = ValueToClass.lookup(V);
1320  if (CC) {
1321  // Everything in TOP is represented by undef, as it can be any value.
1322  // We do have to make sure we get the type right though, so we can't set the
1323  // RepLeader to undef.
1324  if (CC == TOPClass)
1325  return UndefValue::get(V->getType());
1326  return CC->getStoredValue() ? CC->getStoredValue() : CC->getLeader();
1327  }
1328 
1329  return V;
1330 }
1331 
1332 const MemoryAccess *NewGVN::lookupMemoryLeader(const MemoryAccess *MA) const {
1333  auto *CC = getMemoryClass(MA);
1334  assert(CC->getMemoryLeader() &&
1335  "Every MemoryAccess should be mapped to a congruence class with a "
1336  "representative memory access");
1337  return CC->getMemoryLeader();
1338 }
1339 
1340 // Return true if the MemoryAccess is really equivalent to everything. This is
1341 // equivalent to the lattice value "TOP" in most lattices. This is the initial
1342 // state of all MemoryAccesses.
1343 bool NewGVN::isMemoryAccessTOP(const MemoryAccess *MA) const {
1344  return getMemoryClass(MA) == TOPClass;
1345 }
1346 
1347 LoadExpression *NewGVN::createLoadExpression(Type *LoadType, Value *PointerOp,
1348  LoadInst *LI,
1349  const MemoryAccess *MA) const {
1350  auto *E =
1351  new (ExpressionAllocator) LoadExpression(1, LI, lookupMemoryLeader(MA));
1352  E->allocateOperands(ArgRecycler, ExpressionAllocator);
1353  E->setType(LoadType);
1354 
1355  // Give store and loads same opcode so they value number together.
1356  E->setOpcode(0);
1357  E->op_push_back(PointerOp);
1358 
1359  // TODO: Value number heap versions. We may be able to discover
1360  // things alias analysis can't on it's own (IE that a store and a
1361  // load have the same value, and thus, it isn't clobbering the load).
1362  return E;
1363 }
1364 
1365 const StoreExpression *
1366 NewGVN::createStoreExpression(StoreInst *SI, const MemoryAccess *MA) const {
1367  auto *StoredValueLeader = lookupOperandLeader(SI->getValueOperand());
1368  auto *E = new (ExpressionAllocator)
1369  StoreExpression(SI->getNumOperands(), SI, StoredValueLeader, MA);
1370  E->allocateOperands(ArgRecycler, ExpressionAllocator);
1371  E->setType(SI->getValueOperand()->getType());
1372 
1373  // Give store and loads same opcode so they value number together.
1374  E->setOpcode(0);
1375  E->op_push_back(lookupOperandLeader(SI->getPointerOperand()));
1376 
1377  // TODO: Value number heap versions. We may be able to discover
1378  // things alias analysis can't on it's own (IE that a store and a
1379  // load have the same value, and thus, it isn't clobbering the load).
1380  return E;
1381 }
1382 
1383 const Expression *NewGVN::performSymbolicStoreEvaluation(Instruction *I) const {
1384  // Unlike loads, we never try to eliminate stores, so we do not check if they
1385  // are simple and avoid value numbering them.
1386  auto *SI = cast<StoreInst>(I);
1387  auto *StoreAccess = getMemoryAccess(SI);
1388  // Get the expression, if any, for the RHS of the MemoryDef.
1389  const MemoryAccess *StoreRHS = StoreAccess->getDefiningAccess();
1391  StoreRHS = MSSAWalker->getClobberingMemoryAccess(StoreAccess);
1392  // If we bypassed the use-def chains, make sure we add a use.
1393  StoreRHS = lookupMemoryLeader(StoreRHS);
1394  if (StoreRHS != StoreAccess->getDefiningAccess())
1395  addMemoryUsers(StoreRHS, StoreAccess);
1396  // If we are defined by ourselves, use the live on entry def.
1397  if (StoreRHS == StoreAccess)
1398  StoreRHS = MSSA->getLiveOnEntryDef();
1399 
1400  if (SI->isSimple()) {
1401  // See if we are defined by a previous store expression, it already has a
1402  // value, and it's the same value as our current store. FIXME: Right now, we
1403  // only do this for simple stores, we should expand to cover memcpys, etc.
1404  const auto *LastStore = createStoreExpression(SI, StoreRHS);
1405  const auto *LastCC = ExpressionToClass.lookup(LastStore);
1406  // We really want to check whether the expression we matched was a store. No
1407  // easy way to do that. However, we can check that the class we found has a
1408  // store, which, assuming the value numbering state is not corrupt, is
1409  // sufficient, because we must also be equivalent to that store's expression
1410  // for it to be in the same class as the load.
1411  if (LastCC && LastCC->getStoredValue() == LastStore->getStoredValue())
1412  return LastStore;
1413  // Also check if our value operand is defined by a load of the same memory
1414  // location, and the memory state is the same as it was then (otherwise, it
1415  // could have been overwritten later. See test32 in
1416  // transforms/DeadStoreElimination/simple.ll).
1417  if (auto *LI = dyn_cast<LoadInst>(LastStore->getStoredValue()))
1418  if ((lookupOperandLeader(LI->getPointerOperand()) ==
1419  LastStore->getOperand(0)) &&
1420  (lookupMemoryLeader(getMemoryAccess(LI)->getDefiningAccess()) ==
1421  StoreRHS))
1422  return LastStore;
1423  deleteExpression(LastStore);
1424  }
1425 
1426  // If the store is not equivalent to anything, value number it as a store that
1427  // produces a unique memory state (instead of using it's MemoryUse, we use
1428  // it's MemoryDef).
1429  return createStoreExpression(SI, StoreAccess);
1430 }
1431 
1432 // See if we can extract the value of a loaded pointer from a load, a store, or
1433 // a memory instruction.
1434 const Expression *
1435 NewGVN::performSymbolicLoadCoercion(Type *LoadType, Value *LoadPtr,
1436  LoadInst *LI, Instruction *DepInst,
1437  MemoryAccess *DefiningAccess) const {
1438  assert((!LI || LI->isSimple()) && "Not a simple load");
1439  if (auto *DepSI = dyn_cast<StoreInst>(DepInst)) {
1440  // Can't forward from non-atomic to atomic without violating memory model.
1441  // Also don't need to coerce if they are the same type, we will just
1442  // propagate.
1443  if (LI->isAtomic() > DepSI->isAtomic() ||
1444  LoadType == DepSI->getValueOperand()->getType())
1445  return nullptr;
1446  int Offset = analyzeLoadFromClobberingStore(LoadType, LoadPtr, DepSI, DL);
1447  if (Offset >= 0) {
1448  if (auto *C = dyn_cast<Constant>(
1449  lookupOperandLeader(DepSI->getValueOperand()))) {
1450  LLVM_DEBUG(dbgs() << "Coercing load from store " << *DepSI
1451  << " to constant " << *C << "\n");
1452  return createConstantExpression(
1453  getConstantStoreValueForLoad(C, Offset, LoadType, DL));
1454  }
1455  }
1456  } else if (auto *DepLI = dyn_cast<LoadInst>(DepInst)) {
1457  // Can't forward from non-atomic to atomic without violating memory model.
1458  if (LI->isAtomic() > DepLI->isAtomic())
1459  return nullptr;
1460  int Offset = analyzeLoadFromClobberingLoad(LoadType, LoadPtr, DepLI, DL);
1461  if (Offset >= 0) {
1462  // We can coerce a constant load into a load.
1463  if (auto *C = dyn_cast<Constant>(lookupOperandLeader(DepLI)))
1464  if (auto *PossibleConstant =
1465  getConstantLoadValueForLoad(C, Offset, LoadType, DL)) {
1466  LLVM_DEBUG(dbgs() << "Coercing load from load " << *LI
1467  << " to constant " << *PossibleConstant << "\n");
1468  return createConstantExpression(PossibleConstant);
1469  }
1470  }
1471  } else if (auto *DepMI = dyn_cast<MemIntrinsic>(DepInst)) {
1472  int Offset = analyzeLoadFromClobberingMemInst(LoadType, LoadPtr, DepMI, DL);
1473  if (Offset >= 0) {
1474  if (auto *PossibleConstant =
1475  getConstantMemInstValueForLoad(DepMI, Offset, LoadType, DL)) {
1476  LLVM_DEBUG(dbgs() << "Coercing load from meminst " << *DepMI
1477  << " to constant " << *PossibleConstant << "\n");
1478  return createConstantExpression(PossibleConstant);
1479  }
1480  }
1481  }
1482 
1483  // All of the below are only true if the loaded pointer is produced
1484  // by the dependent instruction.
1485  if (LoadPtr != lookupOperandLeader(DepInst) &&
1486  !AA->isMustAlias(LoadPtr, DepInst))
1487  return nullptr;
1488  // If this load really doesn't depend on anything, then we must be loading an
1489  // undef value. This can happen when loading for a fresh allocation with no
1490  // intervening stores, for example. Note that this is only true in the case
1491  // that the result of the allocation is pointer equal to the load ptr.
1492  if (isa<AllocaInst>(DepInst) || isMallocLikeFn(DepInst, TLI) ||
1493  isAlignedAllocLikeFn(DepInst, TLI)) {
1494  return createConstantExpression(UndefValue::get(LoadType));
1495  }
1496  // If this load occurs either right after a lifetime begin,
1497  // then the loaded value is undefined.
1498  else if (auto *II = dyn_cast<IntrinsicInst>(DepInst)) {
1499  if (II->getIntrinsicID() == Intrinsic::lifetime_start)
1500  return createConstantExpression(UndefValue::get(LoadType));
1501  }
1502  // If this load follows a calloc (which zero initializes memory),
1503  // then the loaded value is zero
1504  else if (isCallocLikeFn(DepInst, TLI)) {
1505  return createConstantExpression(Constant::getNullValue(LoadType));
1506  }
1507 
1508  return nullptr;
1509 }
1510 
1511 const Expression *NewGVN::performSymbolicLoadEvaluation(Instruction *I) const {
1512  auto *LI = cast<LoadInst>(I);
1513 
1514  // We can eliminate in favor of non-simple loads, but we won't be able to
1515  // eliminate the loads themselves.
1516  if (!LI->isSimple())
1517  return nullptr;
1518 
1519  Value *LoadAddressLeader = lookupOperandLeader(LI->getPointerOperand());
1520  // Load of undef is undef.
1521  if (isa<UndefValue>(LoadAddressLeader))
1522  return createConstantExpression(UndefValue::get(LI->getType()));
1523  MemoryAccess *OriginalAccess = getMemoryAccess(I);
1524  MemoryAccess *DefiningAccess =
1525  MSSAWalker->getClobberingMemoryAccess(OriginalAccess);
1526 
1527  if (!MSSA->isLiveOnEntryDef(DefiningAccess)) {
1528  if (auto *MD = dyn_cast<MemoryDef>(DefiningAccess)) {
1529  Instruction *DefiningInst = MD->getMemoryInst();
1530  // If the defining instruction is not reachable, replace with undef.
1531  if (!ReachableBlocks.count(DefiningInst->getParent()))
1532  return createConstantExpression(UndefValue::get(LI->getType()));
1533  // This will handle stores and memory insts. We only do if it the
1534  // defining access has a different type, or it is a pointer produced by
1535  // certain memory operations that cause the memory to have a fixed value
1536  // (IE things like calloc).
1537  if (const auto *CoercionResult =
1538  performSymbolicLoadCoercion(LI->getType(), LoadAddressLeader, LI,
1539  DefiningInst, DefiningAccess))
1540  return CoercionResult;
1541  }
1542  }
1543 
1544  const auto *LE = createLoadExpression(LI->getType(), LoadAddressLeader, LI,
1545  DefiningAccess);
1546  // If our MemoryLeader is not our defining access, add a use to the
1547  // MemoryLeader, so that we get reprocessed when it changes.
1548  if (LE->getMemoryLeader() != DefiningAccess)
1549  addMemoryUsers(LE->getMemoryLeader(), OriginalAccess);
1550  return LE;
1551 }
1552 
1553 NewGVN::ExprResult
1554 NewGVN::performSymbolicPredicateInfoEvaluation(Instruction *I) const {
1555  auto *PI = PredInfo->getPredicateInfoFor(I);
1556  if (!PI)
1557  return ExprResult::none();
1558 
1559  LLVM_DEBUG(dbgs() << "Found predicate info from instruction !\n");
1560 
1561  const Optional<PredicateConstraint> &Constraint = PI->getConstraint();
1562  if (!Constraint)
1563  return ExprResult::none();
1564 
1565  CmpInst::Predicate Predicate = Constraint->Predicate;
1566  Value *CmpOp0 = I->getOperand(0);
1567  Value *CmpOp1 = Constraint->OtherOp;
1568 
1569  Value *FirstOp = lookupOperandLeader(CmpOp0);
1570  Value *SecondOp = lookupOperandLeader(CmpOp1);
1571  Value *AdditionallyUsedValue = CmpOp0;
1572 
1573  // Sort the ops.
1574  if (shouldSwapOperands(FirstOp, SecondOp)) {
1575  std::swap(FirstOp, SecondOp);
1577  AdditionallyUsedValue = CmpOp1;
1578  }
1579 
1580  if (Predicate == CmpInst::ICMP_EQ)
1581  return ExprResult::some(createVariableOrConstant(FirstOp),
1582  AdditionallyUsedValue, PI);
1583 
1584  // Handle the special case of floating point.
1585  if (Predicate == CmpInst::FCMP_OEQ && isa<ConstantFP>(FirstOp) &&
1586  !cast<ConstantFP>(FirstOp)->isZero())
1587  return ExprResult::some(createConstantExpression(cast<Constant>(FirstOp)),
1588  AdditionallyUsedValue, PI);
1589 
1590  return ExprResult::none();
1591 }
1592 
1593 // Evaluate read only and pure calls, and create an expression result.
1594 NewGVN::ExprResult NewGVN::performSymbolicCallEvaluation(Instruction *I) const {
1595  auto *CI = cast<CallInst>(I);
1596  if (auto *II = dyn_cast<IntrinsicInst>(I)) {
1597  // Intrinsics with the returned attribute are copies of arguments.
1598  if (auto *ReturnedValue = II->getReturnedArgOperand()) {
1599  if (II->getIntrinsicID() == Intrinsic::ssa_copy)
1600  if (auto Res = performSymbolicPredicateInfoEvaluation(I))
1601  return Res;
1602  return ExprResult::some(createVariableOrConstant(ReturnedValue));
1603  }
1604  }
1605  if (AA->doesNotAccessMemory(CI)) {
1606  return ExprResult::some(
1607  createCallExpression(CI, TOPClass->getMemoryLeader()));
1608  } else if (AA->onlyReadsMemory(CI)) {
1609  if (auto *MA = MSSA->getMemoryAccess(CI)) {
1610  auto *DefiningAccess = MSSAWalker->getClobberingMemoryAccess(MA);
1611  return ExprResult::some(createCallExpression(CI, DefiningAccess));
1612  } else // MSSA determined that CI does not access memory.
1613  return ExprResult::some(
1614  createCallExpression(CI, TOPClass->getMemoryLeader()));
1615  }
1616  return ExprResult::none();
1617 }
1618 
1619 // Retrieve the memory class for a given MemoryAccess.
1620 CongruenceClass *NewGVN::getMemoryClass(const MemoryAccess *MA) const {
1621  auto *Result = MemoryAccessToClass.lookup(MA);
1622  assert(Result && "Should have found memory class");
1623  return Result;
1624 }
1625 
1626 // Update the MemoryAccess equivalence table to say that From is equal to To,
1627 // and return true if this is different from what already existed in the table.
1628 bool NewGVN::setMemoryClass(const MemoryAccess *From,
1629  CongruenceClass *NewClass) {
1630  assert(NewClass &&
1631  "Every MemoryAccess should be getting mapped to a non-null class");
1632  LLVM_DEBUG(dbgs() << "Setting " << *From);
1633  LLVM_DEBUG(dbgs() << " equivalent to congruence class ");
1634  LLVM_DEBUG(dbgs() << NewClass->getID()
1635  << " with current MemoryAccess leader ");
1636  LLVM_DEBUG(dbgs() << *NewClass->getMemoryLeader() << "\n");
1637 
1638  auto LookupResult = MemoryAccessToClass.find(From);
1639  bool Changed = false;
1640  // If it's already in the table, see if the value changed.
1641  if (LookupResult != MemoryAccessToClass.end()) {
1642  auto *OldClass = LookupResult->second;
1643  if (OldClass != NewClass) {
1644  // If this is a phi, we have to handle memory member updates.
1645  if (auto *MP = dyn_cast<MemoryPhi>(From)) {
1646  OldClass->memory_erase(MP);
1647  NewClass->memory_insert(MP);
1648  // This may have killed the class if it had no non-memory members
1649  if (OldClass->getMemoryLeader() == From) {
1650  if (OldClass->definesNoMemory()) {
1651  OldClass->setMemoryLeader(nullptr);
1652  } else {
1653  OldClass->setMemoryLeader(getNextMemoryLeader(OldClass));
1654  LLVM_DEBUG(dbgs() << "Memory class leader change for class "
1655  << OldClass->getID() << " to "
1656  << *OldClass->getMemoryLeader()
1657  << " due to removal of a memory member " << *From
1658  << "\n");
1659  markMemoryLeaderChangeTouched(OldClass);
1660  }
1661  }
1662  }
1663  // It wasn't equivalent before, and now it is.
1664  LookupResult->second = NewClass;
1665  Changed = true;
1666  }
1667  }
1668 
1669  return Changed;
1670 }
1671 
1672 // Determine if a instruction is cycle-free. That means the values in the
1673 // instruction don't depend on any expressions that can change value as a result
1674 // of the instruction. For example, a non-cycle free instruction would be v =
1675 // phi(0, v+1).
1676 bool NewGVN::isCycleFree(const Instruction *I) const {
1677  // In order to compute cycle-freeness, we do SCC finding on the instruction,
1678  // and see what kind of SCC it ends up in. If it is a singleton, it is
1679  // cycle-free. If it is not in a singleton, it is only cycle free if the
1680  // other members are all phi nodes (as they do not compute anything, they are
1681  // copies).
1682  auto ICS = InstCycleState.lookup(I);
1683  if (ICS == ICS_Unknown) {
1684  SCCFinder.Start(I);
1685  auto &SCC = SCCFinder.getComponentFor(I);
1686  // It's cycle free if it's size 1 or the SCC is *only* phi nodes.
1687  if (SCC.size() == 1)
1688  InstCycleState.insert({I, ICS_CycleFree});
1689  else {
1690  bool AllPhis = llvm::all_of(SCC, [](const Value *V) {
1691  return isa<PHINode>(V) || isCopyOfAPHI(V);
1692  });
1693  ICS = AllPhis ? ICS_CycleFree : ICS_Cycle;
1694  for (auto *Member : SCC)
1695  if (auto *MemberPhi = dyn_cast<PHINode>(Member))
1696  InstCycleState.insert({MemberPhi, ICS});
1697  }
1698  }
1699  if (ICS == ICS_Cycle)
1700  return false;
1701  return true;
1702 }
1703 
1704 // Evaluate PHI nodes symbolically and create an expression result.
1705 const Expression *
1706 NewGVN::performSymbolicPHIEvaluation(ArrayRef<ValPair> PHIOps,
1707  Instruction *I,
1708  BasicBlock *PHIBlock) const {
1709  // True if one of the incoming phi edges is a backedge.
1710  bool HasBackedge = false;
1711  // All constant tracks the state of whether all the *original* phi operands
1712  // This is really shorthand for "this phi cannot cycle due to forward
1713  // change in value of the phi is guaranteed not to later change the value of
1714  // the phi. IE it can't be v = phi(undef, v+1)
1715  bool OriginalOpsConstant = true;
1716  auto *E = cast<PHIExpression>(createPHIExpression(
1717  PHIOps, I, PHIBlock, HasBackedge, OriginalOpsConstant));
1718  // We match the semantics of SimplifyPhiNode from InstructionSimplify here.
1719  // See if all arguments are the same.
1720  // We track if any were undef because they need special handling.
1721  bool HasUndef = false;
1722  auto Filtered = make_filter_range(E->operands(), [&](Value *Arg) {
1723  if (isa<UndefValue>(Arg)) {
1724  HasUndef = true;
1725  return false;
1726  }
1727  return true;
1728  });
1729  // If we are left with no operands, it's dead.
1730  if (Filtered.empty()) {
1731  // If it has undef at this point, it means there are no-non-undef arguments,
1732  // and thus, the value of the phi node must be undef.
1733  if (HasUndef) {
1734  LLVM_DEBUG(
1735  dbgs() << "PHI Node " << *I
1736  << " has no non-undef arguments, valuing it as undef\n");
1737  return createConstantExpression(UndefValue::get(I->getType()));
1738  }
1739 
1740  LLVM_DEBUG(dbgs() << "No arguments of PHI node " << *I << " are live\n");
1741  deleteExpression(E);
1742  return createDeadExpression();
1743  }
1744  Value *AllSameValue = *(Filtered.begin());
1745  ++Filtered.begin();
1746  // Can't use std::equal here, sadly, because filter.begin moves.
1747  if (llvm::all_of(Filtered, [&](Value *Arg) { return Arg == AllSameValue; })) {
1748  // In LLVM's non-standard representation of phi nodes, it's possible to have
1749  // phi nodes with cycles (IE dependent on other phis that are .... dependent
1750  // on the original phi node), especially in weird CFG's where some arguments
1751  // are unreachable, or uninitialized along certain paths. This can cause
1752  // infinite loops during evaluation. We work around this by not trying to
1753  // really evaluate them independently, but instead using a variable
1754  // expression to say if one is equivalent to the other.
1755  // We also special case undef, so that if we have an undef, we can't use the
1756  // common value unless it dominates the phi block.
1757  if (HasUndef) {
1758  // If we have undef and at least one other value, this is really a
1759  // multivalued phi, and we need to know if it's cycle free in order to
1760  // evaluate whether we can ignore the undef. The other parts of this are
1761  // just shortcuts. If there is no backedge, or all operands are
1762  // constants, it also must be cycle free.
1763  if (HasBackedge && !OriginalOpsConstant &&
1764  !isa<UndefValue>(AllSameValue) && !isCycleFree(I))
1765  return E;
1766 
1767  // Only have to check for instructions
1768  if (auto *AllSameInst = dyn_cast<Instruction>(AllSameValue))
1769  if (!someEquivalentDominates(AllSameInst, I))
1770  return E;
1771  }
1772  // Can't simplify to something that comes later in the iteration.
1773  // Otherwise, when and if it changes congruence class, we will never catch
1774  // up. We will always be a class behind it.
1775  if (isa<Instruction>(AllSameValue) &&
1776  InstrToDFSNum(AllSameValue) > InstrToDFSNum(I))
1777  return E;
1778  NumGVNPhisAllSame++;
1779  LLVM_DEBUG(dbgs() << "Simplified PHI node " << *I << " to " << *AllSameValue
1780  << "\n");
1781  deleteExpression(E);
1782  return createVariableOrConstant(AllSameValue);
1783  }
1784  return E;
1785 }
1786 
1787 const Expression *
1788 NewGVN::performSymbolicAggrValueEvaluation(Instruction *I) const {
1789  if (auto *EI = dyn_cast<ExtractValueInst>(I)) {
1790  auto *WO = dyn_cast<WithOverflowInst>(EI->getAggregateOperand());
1791  if (WO && EI->getNumIndices() == 1 && *EI->idx_begin() == 0)
1792  // EI is an extract from one of our with.overflow intrinsics. Synthesize
1793  // a semantically equivalent expression instead of an extract value
1794  // expression.
1795  return createBinaryExpression(WO->getBinaryOp(), EI->getType(),
1796  WO->getLHS(), WO->getRHS(), I);
1797  }
1798 
1799  return createAggregateValueExpression(I);
1800 }
1801 
1802 NewGVN::ExprResult NewGVN::performSymbolicCmpEvaluation(Instruction *I) const {
1803  assert(isa<CmpInst>(I) && "Expected a cmp instruction.");
1804 
1805  auto *CI = cast<CmpInst>(I);
1806  // See if our operands are equal to those of a previous predicate, and if so,
1807  // if it implies true or false.
1808  auto Op0 = lookupOperandLeader(CI->getOperand(0));
1809  auto Op1 = lookupOperandLeader(CI->getOperand(1));
1810  auto OurPredicate = CI->getPredicate();
1811  if (shouldSwapOperands(Op0, Op1)) {
1812  std::swap(Op0, Op1);
1813  OurPredicate = CI->getSwappedPredicate();
1814  }
1815 
1816  // Avoid processing the same info twice.
1817  const PredicateBase *LastPredInfo = nullptr;
1818  // See if we know something about the comparison itself, like it is the target
1819  // of an assume.
1820  auto *CmpPI = PredInfo->getPredicateInfoFor(I);
1821  if (dyn_cast_or_null<PredicateAssume>(CmpPI))
1822  return ExprResult::some(
1823  createConstantExpression(ConstantInt::getTrue(CI->getType())));
1824 
1825  if (Op0 == Op1) {
1826  // This condition does not depend on predicates, no need to add users
1827  if (CI->isTrueWhenEqual())
1828  return ExprResult::some(
1829  createConstantExpression(ConstantInt::getTrue(CI->getType())));
1830  else if (CI->isFalseWhenEqual())
1831  return ExprResult::some(
1832  createConstantExpression(ConstantInt::getFalse(CI->getType())));
1833  }
1834 
1835  // NOTE: Because we are comparing both operands here and below, and using
1836  // previous comparisons, we rely on fact that predicateinfo knows to mark
1837  // comparisons that use renamed operands as users of the earlier comparisons.
1838  // It is *not* enough to just mark predicateinfo renamed operands as users of
1839  // the earlier comparisons, because the *other* operand may have changed in a
1840  // previous iteration.
1841  // Example:
1842  // icmp slt %a, %b
1843  // %b.0 = ssa.copy(%b)
1844  // false branch:
1845  // icmp slt %c, %b.0
1846 
1847  // %c and %a may start out equal, and thus, the code below will say the second
1848  // %icmp is false. c may become equal to something else, and in that case the
1849  // %second icmp *must* be reexamined, but would not if only the renamed
1850  // %operands are considered users of the icmp.
1851 
1852  // *Currently* we only check one level of comparisons back, and only mark one
1853  // level back as touched when changes happen. If you modify this code to look
1854  // back farther through comparisons, you *must* mark the appropriate
1855  // comparisons as users in PredicateInfo.cpp, or you will cause bugs. See if
1856  // we know something just from the operands themselves
1857 
1858  // See if our operands have predicate info, so that we may be able to derive
1859  // something from a previous comparison.
1860  for (const auto &Op : CI->operands()) {
1861  auto *PI = PredInfo->getPredicateInfoFor(Op);
1862  if (const auto *PBranch = dyn_cast_or_null<PredicateBranch>(PI)) {
1863  if (PI == LastPredInfo)
1864  continue;
1865  LastPredInfo = PI;
1866  // In phi of ops cases, we may have predicate info that we are evaluating
1867  // in a different context.
1868  if (!DT->dominates(PBranch->To, getBlockForValue(I)))
1869  continue;
1870  // TODO: Along the false edge, we may know more things too, like
1871  // icmp of
1872  // same operands is false.
1873  // TODO: We only handle actual comparison conditions below, not
1874  // and/or.
1875  auto *BranchCond = dyn_cast<CmpInst>(PBranch->Condition);
1876  if (!BranchCond)
1877  continue;
1878  auto *BranchOp0 = lookupOperandLeader(BranchCond->getOperand(0));
1879  auto *BranchOp1 = lookupOperandLeader(BranchCond->getOperand(1));
1880  auto BranchPredicate = BranchCond->getPredicate();
1881  if (shouldSwapOperands(BranchOp0, BranchOp1)) {
1882  std::swap(BranchOp0, BranchOp1);
1883  BranchPredicate = BranchCond->getSwappedPredicate();
1884  }
1885  if (BranchOp0 == Op0 && BranchOp1 == Op1) {
1886  if (PBranch->TrueEdge) {
1887  // If we know the previous predicate is true and we are in the true
1888  // edge then we may be implied true or false.
1889  if (CmpInst::isImpliedTrueByMatchingCmp(BranchPredicate,
1890  OurPredicate)) {
1891  return ExprResult::some(
1892  createConstantExpression(ConstantInt::getTrue(CI->getType())),
1893  PI);
1894  }
1895 
1896  if (CmpInst::isImpliedFalseByMatchingCmp(BranchPredicate,
1897  OurPredicate)) {
1898  return ExprResult::some(
1899  createConstantExpression(ConstantInt::getFalse(CI->getType())),
1900  PI);
1901  }
1902  } else {
1903  // Just handle the ne and eq cases, where if we have the same
1904  // operands, we may know something.
1905  if (BranchPredicate == OurPredicate) {
1906  // Same predicate, same ops,we know it was false, so this is false.
1907  return ExprResult::some(
1908  createConstantExpression(ConstantInt::getFalse(CI->getType())),
1909  PI);
1910  } else if (BranchPredicate ==
1911  CmpInst::getInversePredicate(OurPredicate)) {
1912  // Inverse predicate, we know the other was false, so this is true.
1913  return ExprResult::some(
1914  createConstantExpression(ConstantInt::getTrue(CI->getType())),
1915  PI);
1916  }
1917  }
1918  }
1919  }
1920  }
1921  // Create expression will take care of simplifyCmpInst
1922  return createExpression(I);
1923 }
1924 
1925 // Substitute and symbolize the value before value numbering.
1926 NewGVN::ExprResult
1927 NewGVN::performSymbolicEvaluation(Value *V,
1928  SmallPtrSetImpl<Value *> &Visited) const {
1929 
1930  const Expression *E = nullptr;
1931  if (auto *C = dyn_cast<Constant>(V))
1932  E = createConstantExpression(C);
1933  else if (isa<Argument>(V) || isa<GlobalVariable>(V)) {
1934  E = createVariableExpression(V);
1935  } else {
1936  // TODO: memory intrinsics.
1937  // TODO: Some day, we should do the forward propagation and reassociation
1938  // parts of the algorithm.
1939  auto *I = cast<Instruction>(V);
1940  switch (I->getOpcode()) {
1941  case Instruction::ExtractValue:
1942  case Instruction::InsertValue:
1943  E = performSymbolicAggrValueEvaluation(I);
1944  break;
1945  case Instruction::PHI: {
1947  auto *PN = cast<PHINode>(I);
1948  for (unsigned i = 0; i < PN->getNumOperands(); ++i)
1949  Ops.push_back({PN->getIncomingValue(i), PN->getIncomingBlock(i)});
1950  // Sort to ensure the invariant createPHIExpression requires is met.
1951  sortPHIOps(Ops);
1952  E = performSymbolicPHIEvaluation(Ops, I, getBlockForValue(I));
1953  } break;
1954  case Instruction::Call:
1955  return performSymbolicCallEvaluation(I);
1956  break;
1957  case Instruction::Store:
1958  E = performSymbolicStoreEvaluation(I);
1959  break;
1960  case Instruction::Load:
1961  E = performSymbolicLoadEvaluation(I);
1962  break;
1963  case Instruction::BitCast:
1964  case Instruction::AddrSpaceCast:
1965  return createExpression(I);
1966  break;
1967  case Instruction::ICmp:
1968  case Instruction::FCmp:
1969  return performSymbolicCmpEvaluation(I);
1970  break;
1971  case Instruction::FNeg:
1972  case Instruction::Add:
1973  case Instruction::FAdd:
1974  case Instruction::Sub:
1975  case Instruction::FSub:
1976  case Instruction::Mul:
1977  case Instruction::FMul:
1978  case Instruction::UDiv:
1979  case Instruction::SDiv:
1980  case Instruction::FDiv:
1981  case Instruction::URem:
1982  case Instruction::SRem:
1983  case Instruction::FRem:
1984  case Instruction::Shl:
1985  case Instruction::LShr:
1986  case Instruction::AShr:
1987  case Instruction::And:
1988  case Instruction::Or:
1989  case Instruction::Xor:
1990  case Instruction::Trunc:
1991  case Instruction::ZExt:
1992  case Instruction::SExt:
1993  case Instruction::FPToUI:
1994  case Instruction::FPToSI:
1995  case Instruction::UIToFP:
1996  case Instruction::SIToFP:
1997  case Instruction::FPTrunc:
1998  case Instruction::FPExt:
1999  case Instruction::PtrToInt:
2000  case Instruction::IntToPtr:
2001  case Instruction::Select:
2002  case Instruction::ExtractElement:
2003  case Instruction::InsertElement:
2004  case Instruction::GetElementPtr:
2005  return createExpression(I);
2006  break;
2007  case Instruction::ShuffleVector:
2008  // FIXME: Add support for shufflevector to createExpression.
2009  return ExprResult::none();
2010  default:
2011  return ExprResult::none();
2012  }
2013  }
2014  return ExprResult::some(E);
2015 }
2016 
2017 // Look up a container of values/instructions in a map, and touch all the
2018 // instructions in the container. Then erase value from the map.
2019 template <typename Map, typename KeyType>
2020 void NewGVN::touchAndErase(Map &M, const KeyType &Key) {
2021  const auto Result = M.find_as(Key);
2022  if (Result != M.end()) {
2023  for (const typename Map::mapped_type::value_type Mapped : Result->second)
2024  TouchedInstructions.set(InstrToDFSNum(Mapped));
2025  M.erase(Result);
2026  }
2027 }
2028 
2029 void NewGVN::addAdditionalUsers(Value *To, Value *User) const {
2030  assert(User && To != User);
2031  if (isa<Instruction>(To))
2032  AdditionalUsers[To].insert(User);
2033 }
2034 
2035 void NewGVN::addAdditionalUsers(ExprResult &Res, Instruction *User) const {
2036  if (Res.ExtraDep && Res.ExtraDep != User)
2037  addAdditionalUsers(Res.ExtraDep, User);
2038  Res.ExtraDep = nullptr;
2039 
2040  if (Res.PredDep) {
2041  if (const auto *PBranch = dyn_cast<PredicateBranch>(Res.PredDep))
2042  PredicateToUsers[PBranch->Condition].insert(User);
2043  else if (const auto *PAssume = dyn_cast<PredicateAssume>(Res.PredDep))
2044  PredicateToUsers[PAssume->Condition].insert(User);
2045  }
2046  Res.PredDep = nullptr;
2047 }
2048 
2049 void NewGVN::markUsersTouched(Value *V) {
2050  // Now mark the users as touched.
2051  for (auto *User : V->users()) {
2052  assert(isa<Instruction>(User) && "Use of value not within an instruction?");
2053  TouchedInstructions.set(InstrToDFSNum(User));
2054  }
2055  touchAndErase(AdditionalUsers, V);
2056 }
2057 
2058 void NewGVN::addMemoryUsers(const MemoryAccess *To, MemoryAccess *U) const {
2059  LLVM_DEBUG(dbgs() << "Adding memory user " << *U << " to " << *To << "\n");
2060  MemoryToUsers[To].insert(U);
2061 }
2062 
2063 void NewGVN::markMemoryDefTouched(const MemoryAccess *MA) {
2064  TouchedInstructions.set(MemoryToDFSNum(MA));
2065 }
2066 
2067 void NewGVN::markMemoryUsersTouched(const MemoryAccess *MA) {
2068  if (isa<MemoryUse>(MA))
2069  return;
2070  for (auto U : MA->users())
2071  TouchedInstructions.set(MemoryToDFSNum(U));
2072  touchAndErase(MemoryToUsers, MA);
2073 }
2074 
2075 // Touch all the predicates that depend on this instruction.
2076 void NewGVN::markPredicateUsersTouched(Instruction *I) {
2077  touchAndErase(PredicateToUsers, I);
2078 }
2079 
2080 // Mark users affected by a memory leader change.
2081 void NewGVN::markMemoryLeaderChangeTouched(CongruenceClass *CC) {
2082  for (auto M : CC->memory())
2083  markMemoryDefTouched(M);
2084 }
2085 
2086 // Touch the instructions that need to be updated after a congruence class has a
2087 // leader change, and mark changed values.
2088 void NewGVN::markValueLeaderChangeTouched(CongruenceClass *CC) {
2089  for (auto M : *CC) {
2090  if (auto *I = dyn_cast<Instruction>(M))
2091  TouchedInstructions.set(InstrToDFSNum(I));
2092  LeaderChanges.insert(M);
2093  }
2094 }
2095 
2096 // Give a range of things that have instruction DFS numbers, this will return
2097 // the member of the range with the smallest dfs number.
2098 template <class T, class Range>
2099 T *NewGVN::getMinDFSOfRange(const Range &R) const {
2100  std::pair<T *, unsigned> MinDFS = {nullptr, ~0U};
2101  for (const auto X : R) {
2102  auto DFSNum = InstrToDFSNum(X);
2103  if (DFSNum < MinDFS.second)
2104  MinDFS = {X, DFSNum};
2105  }
2106  return MinDFS.first;
2107 }
2108 
2109 // This function returns the MemoryAccess that should be the next leader of
2110 // congruence class CC, under the assumption that the current leader is going to
2111 // disappear.
2112 const MemoryAccess *NewGVN::getNextMemoryLeader(CongruenceClass *CC) const {
2113  // TODO: If this ends up to slow, we can maintain a next memory leader like we
2114  // do for regular leaders.
2115  // Make sure there will be a leader to find.
2116  assert(!CC->definesNoMemory() && "Can't get next leader if there is none");
2117  if (CC->getStoreCount() > 0) {
2118  if (auto *NL = dyn_cast_or_null<StoreInst>(CC->getNextLeader().first))
2119  return getMemoryAccess(NL);
2120  // Find the store with the minimum DFS number.
2121  auto *V = getMinDFSOfRange<Value>(make_filter_range(
2122  *CC, [&](const Value *V) { return isa<StoreInst>(V); }));
2123  return getMemoryAccess(cast<StoreInst>(V));
2124  }
2125  assert(CC->getStoreCount() == 0);
2126 
2127  // Given our assertion, hitting this part must mean
2128  // !OldClass->memory_empty()
2129  if (CC->memory_size() == 1)
2130  return *CC->memory_begin();
2131  return getMinDFSOfRange<const MemoryPhi>(CC->memory());
2132 }
2133 
2134 // This function returns the next value leader of a congruence class, under the
2135 // assumption that the current leader is going away. This should end up being
2136 // the next most dominating member.
2137 Value *NewGVN::getNextValueLeader(CongruenceClass *CC) const {
2138  // We don't need to sort members if there is only 1, and we don't care about
2139  // sorting the TOP class because everything either gets out of it or is
2140  // unreachable.
2141 
2142  if (CC->size() == 1 || CC == TOPClass) {
2143  return *(CC->begin());
2144  } else if (CC->getNextLeader().first) {
2145  ++NumGVNAvoidedSortedLeaderChanges;
2146  return CC->getNextLeader().first;
2147  } else {
2148  ++NumGVNSortedLeaderChanges;
2149  // NOTE: If this ends up to slow, we can maintain a dual structure for
2150  // member testing/insertion, or keep things mostly sorted, and sort only
2151  // here, or use SparseBitVector or ....
2152  return getMinDFSOfRange<Value>(*CC);
2153  }
2154 }
2155 
2156 // Move a MemoryAccess, currently in OldClass, to NewClass, including updates to
2157 // the memory members, etc for the move.
2158 //
2159 // The invariants of this function are:
2160 //
2161 // - I must be moving to NewClass from OldClass
2162 // - The StoreCount of OldClass and NewClass is expected to have been updated
2163 // for I already if it is a store.
2164 // - The OldClass memory leader has not been updated yet if I was the leader.
2165 void NewGVN::moveMemoryToNewCongruenceClass(Instruction *I,
2166  MemoryAccess *InstMA,
2167  CongruenceClass *OldClass,
2168  CongruenceClass *NewClass) {
2169  // If the leader is I, and we had a representative MemoryAccess, it should
2170  // be the MemoryAccess of OldClass.
2171  assert((!InstMA || !OldClass->getMemoryLeader() ||
2172  OldClass->getLeader() != I ||
2173  MemoryAccessToClass.lookup(OldClass->getMemoryLeader()) ==
2174  MemoryAccessToClass.lookup(InstMA)) &&
2175  "Representative MemoryAccess mismatch");
2176  // First, see what happens to the new class
2177  if (!NewClass->getMemoryLeader()) {
2178  // Should be a new class, or a store becoming a leader of a new class.
2179  assert(NewClass->size() == 1 ||
2180  (isa<StoreInst>(I) && NewClass->getStoreCount() == 1));
2181  NewClass->setMemoryLeader(InstMA);
2182  // Mark it touched if we didn't just create a singleton
2183  LLVM_DEBUG(dbgs() << "Memory class leader change for class "
2184  << NewClass->getID()
2185  << " due to new memory instruction becoming leader\n");
2186  markMemoryLeaderChangeTouched(NewClass);
2187  }
2188  setMemoryClass(InstMA, NewClass);
2189  // Now, fixup the old class if necessary
2190  if (OldClass->getMemoryLeader() == InstMA) {
2191  if (!OldClass->definesNoMemory()) {
2192  OldClass->setMemoryLeader(getNextMemoryLeader(OldClass));
2193  LLVM_DEBUG(dbgs() << "Memory class leader change for class "
2194  << OldClass->getID() << " to "
2195  << *OldClass->getMemoryLeader()
2196  << " due to removal of old leader " << *InstMA << "\n");
2197  markMemoryLeaderChangeTouched(OldClass);
2198  } else
2199  OldClass->setMemoryLeader(nullptr);
2200  }
2201 }
2202 
2203 // Move a value, currently in OldClass, to be part of NewClass
2204 // Update OldClass and NewClass for the move (including changing leaders, etc).
2205 void NewGVN::moveValueToNewCongruenceClass(Instruction *I, const Expression *E,
2206  CongruenceClass *OldClass,
2207  CongruenceClass *NewClass) {
2208  if (I == OldClass->getNextLeader().first)
2209  OldClass->resetNextLeader();
2210 
2211  OldClass->erase(I);
2212  NewClass->insert(I);
2213 
2214  if (NewClass->getLeader() != I)
2215  NewClass->addPossibleNextLeader({I, InstrToDFSNum(I)});
2216  // Handle our special casing of stores.
2217  if (auto *SI = dyn_cast<StoreInst>(I)) {
2218  OldClass->decStoreCount();
2219  // Okay, so when do we want to make a store a leader of a class?
2220  // If we have a store defined by an earlier load, we want the earlier load
2221  // to lead the class.
2222  // If we have a store defined by something else, we want the store to lead
2223  // the class so everything else gets the "something else" as a value.
2224  // If we have a store as the single member of the class, we want the store
2225  // as the leader
2226  if (NewClass->getStoreCount() == 0 && !NewClass->getStoredValue()) {
2227  // If it's a store expression we are using, it means we are not equivalent
2228  // to something earlier.
2229  if (auto *SE = dyn_cast<StoreExpression>(E)) {
2230  NewClass->setStoredValue(SE->getStoredValue());
2231  markValueLeaderChangeTouched(NewClass);
2232  // Shift the new class leader to be the store
2233  LLVM_DEBUG(dbgs() << "Changing leader of congruence class "
2234  << NewClass->getID() << " from "
2235  << *NewClass->getLeader() << " to " << *SI
2236  << " because store joined class\n");
2237  // If we changed the leader, we have to mark it changed because we don't
2238  // know what it will do to symbolic evaluation.
2239  NewClass->setLeader(SI);
2240  }
2241  // We rely on the code below handling the MemoryAccess change.
2242  }
2243  NewClass->incStoreCount();
2244  }
2245  // True if there is no memory instructions left in a class that had memory
2246  // instructions before.
2247 
2248  // If it's not a memory use, set the MemoryAccess equivalence
2249  auto *InstMA = dyn_cast_or_null<MemoryDef>(getMemoryAccess(I));
2250  if (InstMA)
2251  moveMemoryToNewCongruenceClass(I, InstMA, OldClass, NewClass);
2252  ValueToClass[I] = NewClass;
2253  // See if we destroyed the class or need to swap leaders.
2254  if (OldClass->empty() && OldClass != TOPClass) {
2255  if (OldClass->getDefiningExpr()) {
2256  LLVM_DEBUG(dbgs() << "Erasing expression " << *OldClass->getDefiningExpr()
2257  << " from table\n");
2258  // We erase it as an exact expression to make sure we don't just erase an
2259  // equivalent one.
2260  auto Iter = ExpressionToClass.find_as(
2261  ExactEqualsExpression(*OldClass->getDefiningExpr()));
2262  if (Iter != ExpressionToClass.end())
2263  ExpressionToClass.erase(Iter);
2264 #ifdef EXPENSIVE_CHECKS
2265  assert(
2266  (*OldClass->getDefiningExpr() != *E || ExpressionToClass.lookup(E)) &&
2267  "We erased the expression we just inserted, which should not happen");
2268 #endif
2269  }
2270  } else if (OldClass->getLeader() == I) {
2271  // When the leader changes, the value numbering of
2272  // everything may change due to symbolization changes, so we need to
2273  // reprocess.
2274  LLVM_DEBUG(dbgs() << "Value class leader change for class "
2275  << OldClass->getID() << "\n");
2276  ++NumGVNLeaderChanges;
2277  // Destroy the stored value if there are no more stores to represent it.
2278  // Note that this is basically clean up for the expression removal that
2279  // happens below. If we remove stores from a class, we may leave it as a
2280  // class of equivalent memory phis.
2281  if (OldClass->getStoreCount() == 0) {
2282  if (OldClass->getStoredValue())
2283  OldClass->setStoredValue(nullptr);
2284  }
2285  OldClass->setLeader(getNextValueLeader(OldClass));
2286  OldClass->resetNextLeader();
2287  markValueLeaderChangeTouched(OldClass);
2288  }
2289 }
2290 
2291 // For a given expression, mark the phi of ops instructions that could have
2292 // changed as a result.
2293 void NewGVN::markPhiOfOpsChanged(const Expression *E) {
2294  touchAndErase(ExpressionToPhiOfOps, E);
2295 }
2296 
2297 // Perform congruence finding on a given value numbering expression.
2298 void NewGVN::performCongruenceFinding(Instruction *I, const Expression *E) {
2299  // This is guaranteed to return something, since it will at least find
2300  // TOP.
2301 
2302  CongruenceClass *IClass = ValueToClass.lookup(I);
2303  assert(IClass && "Should have found a IClass");
2304  // Dead classes should have been eliminated from the mapping.
2305  assert(!IClass->isDead() && "Found a dead class");
2306 
2307  CongruenceClass *EClass = nullptr;
2308  if (const auto *VE = dyn_cast<VariableExpression>(E)) {
2309  EClass = ValueToClass.lookup(VE->getVariableValue());
2310  } else if (isa<DeadExpression>(E)) {
2311  EClass = TOPClass;
2312  }
2313  if (!EClass) {
2314  auto lookupResult = ExpressionToClass.insert({E, nullptr});
2315 
2316  // If it's not in the value table, create a new congruence class.
2317  if (lookupResult.second) {
2318  CongruenceClass *NewClass = createCongruenceClass(nullptr, E);
2319  auto place = lookupResult.first;
2320  place->second = NewClass;
2321 
2322  // Constants and variables should always be made the leader.
2323  if (const auto *CE = dyn_cast<ConstantExpression>(E)) {
2324  NewClass->setLeader(CE->getConstantValue());
2325  } else if (const auto *SE = dyn_cast<StoreExpression>(E)) {
2326  StoreInst *SI = SE->getStoreInst();
2327  NewClass->setLeader(SI);
2328  NewClass->setStoredValue(SE->getStoredValue());
2329  // The RepMemoryAccess field will be filled in properly by the
2330  // moveValueToNewCongruenceClass call.
2331  } else {
2332  NewClass->setLeader(I);
2333  }
2334  assert(!isa<VariableExpression>(E) &&
2335  "VariableExpression should have been handled already");
2336 
2337  EClass = NewClass;
2338  LLVM_DEBUG(dbgs() << "Created new congruence class for " << *I
2339  << " using expression " << *E << " at "
2340  << NewClass->getID() << " and leader "
2341  << *(NewClass->getLeader()));
2342  if (NewClass->getStoredValue())
2343  LLVM_DEBUG(dbgs() << " and stored value "
2344  << *(NewClass->getStoredValue()));
2345  LLVM_DEBUG(dbgs() << "\n");
2346  } else {
2347  EClass = lookupResult.first->second;
2348  if (isa<ConstantExpression>(E))
2349  assert((isa<Constant>(EClass->getLeader()) ||
2350  (EClass->getStoredValue() &&
2351  isa<Constant>(EClass->getStoredValue()))) &&
2352  "Any class with a constant expression should have a "
2353  "constant leader");
2354 
2355  assert(EClass && "Somehow don't have an eclass");
2356 
2357  assert(!EClass->isDead() && "We accidentally looked up a dead class");
2358  }
2359  }
2360  bool ClassChanged = IClass != EClass;
2361  bool LeaderChanged = LeaderChanges.erase(I);
2362  if (ClassChanged || LeaderChanged) {
2363  LLVM_DEBUG(dbgs() << "New class " << EClass->getID() << " for expression "
2364  << *E << "\n");
2365  if (ClassChanged) {
2366  moveValueToNewCongruenceClass(I, E, IClass, EClass);
2367  markPhiOfOpsChanged(E);
2368  }
2369 
2370  markUsersTouched(I);
2371  if (MemoryAccess *MA = getMemoryAccess(I))
2372  markMemoryUsersTouched(MA);
2373  if (auto *CI = dyn_cast<CmpInst>(I))
2374  markPredicateUsersTouched(CI);
2375  }
2376  // If we changed the class of the store, we want to ensure nothing finds the
2377  // old store expression. In particular, loads do not compare against stored
2378  // value, so they will find old store expressions (and associated class
2379  // mappings) if we leave them in the table.
2380  if (ClassChanged && isa<StoreInst>(I)) {
2381  auto *OldE = ValueToExpression.lookup(I);
2382  // It could just be that the old class died. We don't want to erase it if we
2383  // just moved classes.
2384  if (OldE && isa<StoreExpression>(OldE) && *E != *OldE) {
2385  // Erase this as an exact expression to ensure we don't erase expressions
2386  // equivalent to it.
2387  auto Iter = ExpressionToClass.find_as(ExactEqualsExpression(*OldE));
2388  if (Iter != ExpressionToClass.end())
2389  ExpressionToClass.erase(Iter);
2390  }
2391  }
2392  ValueToExpression[I] = E;
2393 }
2394 
2395 // Process the fact that Edge (from, to) is reachable, including marking
2396 // any newly reachable blocks and instructions for processing.
2397 void NewGVN::updateReachableEdge(BasicBlock *From, BasicBlock *To) {
2398  // Check if the Edge was reachable before.
2399  if (ReachableEdges.insert({From, To}).second) {
2400  // If this block wasn't reachable before, all instructions are touched.
2401  if (ReachableBlocks.insert(To).second) {
2402  LLVM_DEBUG(dbgs() << "Block " << getBlockName(To)
2403  << " marked reachable\n");
2404  const auto &InstRange = BlockInstRange.lookup(To);
2405  TouchedInstructions.set(InstRange.first, InstRange.second);
2406  } else {
2407  LLVM_DEBUG(dbgs() << "Block " << getBlockName(To)
2408  << " was reachable, but new edge {"
2409  << getBlockName(From) << "," << getBlockName(To)
2410  << "} to it found\n");
2411 
2412  // We've made an edge reachable to an existing block, which may
2413  // impact predicates. Otherwise, only mark the phi nodes as touched, as
2414  // they are the only thing that depend on new edges. Anything using their
2415  // values will get propagated to if necessary.
2416  if (MemoryAccess *MemPhi = getMemoryAccess(To))
2417  TouchedInstructions.set(InstrToDFSNum(MemPhi));
2418 
2419  // FIXME: We should just add a union op on a Bitvector and
2420  // SparseBitVector. We can do it word by word faster than we are doing it
2421  // here.
2422  for (auto InstNum : RevisitOnReachabilityChange[To])
2423  TouchedInstructions.set(InstNum);
2424  }
2425  }
2426 }
2427 
2428 // Given a predicate condition (from a switch, cmp, or whatever) and a block,
2429 // see if we know some constant value for it already.
2430 Value *NewGVN::findConditionEquivalence(Value *Cond) const {
2431  auto Result = lookupOperandLeader(Cond);
2432  return isa<Constant>(Result) ? Result : nullptr;
2433 }
2434 
2435 // Process the outgoing edges of a block for reachability.
2436 void NewGVN::processOutgoingEdges(Instruction *TI, BasicBlock *B) {
2437  // Evaluate reachability of terminator instruction.
2438  Value *Cond;
2439  BasicBlock *TrueSucc, *FalseSucc;
2440  if (match(TI, m_Br(m_Value(Cond), TrueSucc, FalseSucc))) {
2441  Value *CondEvaluated = findConditionEquivalence(Cond);
2442  if (!CondEvaluated) {
2443  if (auto *I = dyn_cast<Instruction>(Cond)) {
2444  SmallPtrSet<Value *, 4> Visited;
2445  auto Res = performSymbolicEvaluation(I, Visited);
2446  if (const auto *CE = dyn_cast_or_null<ConstantExpression>(Res.Expr)) {
2447  CondEvaluated = CE->getConstantValue();
2448  addAdditionalUsers(Res, I);
2449  } else {
2450  // Did not use simplification result, no need to add the extra
2451  // dependency.
2452  Res.ExtraDep = nullptr;
2453  }
2454  } else if (isa<ConstantInt>(Cond)) {
2455  CondEvaluated = Cond;
2456  }
2457  }
2458  ConstantInt *CI;
2459  if (CondEvaluated && (CI = dyn_cast<ConstantInt>(CondEvaluated))) {
2460  if (CI->isOne()) {
2461  LLVM_DEBUG(dbgs() << "Condition for Terminator " << *TI
2462  << " evaluated to true\n");
2463  updateReachableEdge(B, TrueSucc);
2464  } else if (CI->isZero()) {
2465  LLVM_DEBUG(dbgs() << "Condition for Terminator " << *TI
2466  << " evaluated to false\n");
2467  updateReachableEdge(B, FalseSucc);
2468  }
2469  } else {
2470  updateReachableEdge(B, TrueSucc);
2471  updateReachableEdge(B, FalseSucc);
2472  }
2473  } else if (auto *SI = dyn_cast<SwitchInst>(TI)) {
2474  // For switches, propagate the case values into the case
2475  // destinations.
2476 
2477  Value *SwitchCond = SI->getCondition();
2478  Value *CondEvaluated = findConditionEquivalence(SwitchCond);
2479  // See if we were able to turn this switch statement into a constant.
2480  if (CondEvaluated && isa<ConstantInt>(CondEvaluated)) {
2481  auto *CondVal = cast<ConstantInt>(CondEvaluated);
2482  // We should be able to get case value for this.
2483  auto Case = *SI->findCaseValue(CondVal);
2484  if (Case.getCaseSuccessor() == SI->getDefaultDest()) {
2485  // We proved the value is outside of the range of the case.
2486  // We can't do anything other than mark the default dest as reachable,
2487  // and go home.
2488  updateReachableEdge(B, SI->getDefaultDest());
2489  return;
2490  }
2491  // Now get where it goes and mark it reachable.
2492  BasicBlock *TargetBlock = Case.getCaseSuccessor();
2493  updateReachableEdge(B, TargetBlock);
2494  } else {
2495  for (unsigned i = 0, e = SI->getNumSuccessors(); i != e; ++i) {
2496  BasicBlock *TargetBlock = SI->getSuccessor(i);
2497  updateReachableEdge(B, TargetBlock);
2498  }
2499  }
2500  } else {
2501  // Otherwise this is either unconditional, or a type we have no
2502  // idea about. Just mark successors as reachable.
2503  for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i) {
2504  BasicBlock *TargetBlock = TI->getSuccessor(i);
2505  updateReachableEdge(B, TargetBlock);
2506  }
2507 
2508  // This also may be a memory defining terminator, in which case, set it
2509  // equivalent only to itself.
2510  //
2511  auto *MA = getMemoryAccess(TI);
2512  if (MA && !isa<MemoryUse>(MA)) {
2513  auto *CC = ensureLeaderOfMemoryClass(MA);
2514  if (setMemoryClass(MA, CC))
2515  markMemoryUsersTouched(MA);
2516  }
2517  }
2518 }
2519 
2520 // Remove the PHI of Ops PHI for I
2521 void NewGVN::removePhiOfOps(Instruction *I, PHINode *PHITemp) {
2522  InstrDFS.erase(PHITemp);
2523  // It's still a temp instruction. We keep it in the array so it gets erased.
2524  // However, it's no longer used by I, or in the block
2525  TempToBlock.erase(PHITemp);
2526  RealToTemp.erase(I);
2527  // We don't remove the users from the phi node uses. This wastes a little
2528  // time, but such is life. We could use two sets to track which were there
2529  // are the start of NewGVN, and which were added, but right nowt he cost of
2530  // tracking is more than the cost of checking for more phi of ops.
2531 }
2532 
2533 // Add PHI Op in BB as a PHI of operations version of ExistingValue.
2534 void NewGVN::addPhiOfOps(PHINode *Op, BasicBlock *BB,
2535  Instruction *ExistingValue) {
2536  InstrDFS[Op] = InstrToDFSNum(ExistingValue);
2537  AllTempInstructions.insert(Op);
2538  TempToBlock[Op] = BB;
2539  RealToTemp[ExistingValue] = Op;
2540  // Add all users to phi node use, as they are now uses of the phi of ops phis
2541  // and may themselves be phi of ops.
2542  for (auto *U : ExistingValue->users())
2543  if (auto *UI = dyn_cast<Instruction>(U))
2544  PHINodeUses.insert(UI);
2545 }
2546 
2547 static bool okayForPHIOfOps(const Instruction *I) {
2548  if (!EnablePhiOfOps)
2549  return false;
2550  return isa<BinaryOperator>(I) || isa<SelectInst>(I) || isa<CmpInst>(I) ||
2551  isa<LoadInst>(I);
2552 }
2553 
2554 bool NewGVN::OpIsSafeForPHIOfOpsHelper(
2555  Value *V, const BasicBlock *PHIBlock,
2557  SmallVectorImpl<Instruction *> &Worklist) {
2558 
2559  if (!isa<Instruction>(V))
2560  return true;
2561  auto OISIt = OpSafeForPHIOfOps.find(V);
2562  if (OISIt != OpSafeForPHIOfOps.end())
2563  return OISIt->second;
2564 
2565  // Keep walking until we either dominate the phi block, or hit a phi, or run
2566  // out of things to check.
2567  if (DT->properlyDominates(getBlockForValue(V), PHIBlock)) {
2568  OpSafeForPHIOfOps.insert({V, true});
2569  return true;
2570  }
2571  // PHI in the same block.
2572  if (isa<PHINode>(V) && getBlockForValue(V) == PHIBlock) {
2573  OpSafeForPHIOfOps.insert({V, false});
2574  return false;
2575  }
2576 
2577  auto *OrigI = cast<Instruction>(V);
2578  for (auto *Op : OrigI->operand_values()) {
2579  if (!isa<Instruction>(Op))
2580  continue;
2581  // Stop now if we find an unsafe operand.
2582  auto OISIt = OpSafeForPHIOfOps.find(OrigI);
2583  if (OISIt != OpSafeForPHIOfOps.end()) {
2584  if (!OISIt->second) {
2585  OpSafeForPHIOfOps.insert({V, false});
2586  return false;
2587  }
2588  continue;
2589  }
2590  if (!Visited.insert(Op).second)
2591  continue;
2592  Worklist.push_back(cast<Instruction>(Op));
2593  }
2594  return true;
2595 }
2596 
2597 // Return true if this operand will be safe to use for phi of ops.
2598 //
2599 // The reason some operands are unsafe is that we are not trying to recursively
2600 // translate everything back through phi nodes. We actually expect some lookups
2601 // of expressions to fail. In particular, a lookup where the expression cannot
2602 // exist in the predecessor. This is true even if the expression, as shown, can
2603 // be determined to be constant.
2604 bool NewGVN::OpIsSafeForPHIOfOps(Value *V, const BasicBlock *PHIBlock,
2605  SmallPtrSetImpl<const Value *> &Visited) {
2607  if (!OpIsSafeForPHIOfOpsHelper(V, PHIBlock, Visited, Worklist))
2608  return false;
2609  while (!Worklist.empty()) {
2610  auto *I = Worklist.pop_back_val();
2611  if (!OpIsSafeForPHIOfOpsHelper(I, PHIBlock, Visited, Worklist))
2612  return false;
2613  }
2614  OpSafeForPHIOfOps.insert({V, true});
2615  return true;
2616 }
2617 
2618 // Try to find a leader for instruction TransInst, which is a phi translated
2619 // version of something in our original program. Visited is used to ensure we
2620 // don't infinite loop during translations of cycles. OrigInst is the
2621 // instruction in the original program, and PredBB is the predecessor we
2622 // translated it through.
2623 Value *NewGVN::findLeaderForInst(Instruction *TransInst,
2624  SmallPtrSetImpl<Value *> &Visited,
2625  MemoryAccess *MemAccess, Instruction *OrigInst,
2626  BasicBlock *PredBB) {
2627  unsigned IDFSNum = InstrToDFSNum(OrigInst);
2628  // Make sure it's marked as a temporary instruction.
2629  AllTempInstructions.insert(TransInst);
2630  // and make sure anything that tries to add it's DFS number is
2631  // redirected to the instruction we are making a phi of ops
2632  // for.
2633  TempToBlock.insert({TransInst, PredBB});
2634  InstrDFS.insert({TransInst, IDFSNum});
2635 
2636  auto Res = performSymbolicEvaluation(TransInst, Visited);
2637  const Expression *E = Res.Expr;
2638  addAdditionalUsers(Res, OrigInst);
2639  InstrDFS.erase(TransInst);
2640  AllTempInstructions.erase(TransInst);
2641  TempToBlock.erase(TransInst);
2642  if (MemAccess)
2643  TempToMemory.erase(TransInst);
2644  if (!E)
2645  return nullptr;
2646  auto *FoundVal = findPHIOfOpsLeader(E, OrigInst, PredBB);
2647  if (!FoundVal) {
2648  ExpressionToPhiOfOps[E].insert(OrigInst);
2649  LLVM_DEBUG(dbgs() << "Cannot find phi of ops operand for " << *TransInst
2650  << " in block " << getBlockName(PredBB) << "\n");
2651  return nullptr;
2652  }
2653  if (auto *SI = dyn_cast<StoreInst>(FoundVal))
2654  FoundVal = SI->getValueOperand();
2655  return FoundVal;
2656 }
2657 
2658 // When we see an instruction that is an op of phis, generate the equivalent phi
2659 // of ops form.
2660 const Expression *
2661 NewGVN::makePossiblePHIOfOps(Instruction *I,
2662  SmallPtrSetImpl<Value *> &Visited) {
2663  if (!okayForPHIOfOps(I))
2664  return nullptr;
2665 
2666  if (!Visited.insert(I).second)
2667  return nullptr;
2668  // For now, we require the instruction be cycle free because we don't
2669  // *always* create a phi of ops for instructions that could be done as phi
2670  // of ops, we only do it if we think it is useful. If we did do it all the
2671  // time, we could remove the cycle free check.
2672  if (!isCycleFree(I))
2673  return nullptr;
2674 
2675  SmallPtrSet<const Value *, 8> ProcessedPHIs;
2676  // TODO: We don't do phi translation on memory accesses because it's
2677  // complicated. For a load, we'd need to be able to simulate a new memoryuse,
2678  // which we don't have a good way of doing ATM.
2679  auto *MemAccess = getMemoryAccess(I);
2680  // If the memory operation is defined by a memory operation this block that
2681  // isn't a MemoryPhi, transforming the pointer backwards through a scalar phi
2682  // can't help, as it would still be killed by that memory operation.
2683  if (MemAccess && !isa<MemoryPhi>(MemAccess->getDefiningAccess()) &&
2684  MemAccess->getDefiningAccess()->getBlock() == I->getParent())
2685  return nullptr;
2686 
2687  // Convert op of phis to phi of ops
2688  SmallPtrSet<const Value *, 10> VisitedOps;
2689  SmallVector<Value *, 4> Ops(I->operand_values());
2690  BasicBlock *SamePHIBlock = nullptr;
2691  PHINode *OpPHI = nullptr;
2692  if (!DebugCounter::shouldExecute(PHIOfOpsCounter))
2693  return nullptr;
2694  for (auto *Op : Ops) {
2695  if (!isa<PHINode>(Op)) {
2696  auto *ValuePHI = RealToTemp.lookup(Op);
2697  if (!ValuePHI)
2698  continue;
2699  LLVM_DEBUG(dbgs() << "Found possible dependent phi of ops\n");
2700  Op = ValuePHI;
2701  }
2702  OpPHI = cast<PHINode>(Op);
2703  if (!SamePHIBlock) {
2704  SamePHIBlock = getBlockForValue(OpPHI);
2705  } else if (SamePHIBlock != getBlockForValue(OpPHI)) {
2706  LLVM_DEBUG(
2707  dbgs()
2708  << "PHIs for operands are not all in the same block, aborting\n");
2709  return nullptr;
2710  }
2711  // No point in doing this for one-operand phis.
2712  if (OpPHI->getNumOperands() == 1) {
2713  OpPHI = nullptr;
2714  continue;
2715  }
2716  }
2717 
2718  if (!OpPHI)
2719  return nullptr;
2720 
2721  SmallVector<ValPair, 4> PHIOps;
2723  auto *PHIBlock = getBlockForValue(OpPHI);
2724  RevisitOnReachabilityChange[PHIBlock].reset(InstrToDFSNum(I));
2725  for (unsigned PredNum = 0; PredNum < OpPHI->getNumOperands(); ++PredNum) {
2726  auto *PredBB = OpPHI->getIncomingBlock(PredNum);
2727  Value *FoundVal = nullptr;
2728  SmallPtrSet<Value *, 4> CurrentDeps;
2729  // We could just skip unreachable edges entirely but it's tricky to do
2730  // with rewriting existing phi nodes.
2731  if (ReachableEdges.count({PredBB, PHIBlock})) {
2732  // Clone the instruction, create an expression from it that is
2733  // translated back into the predecessor, and see if we have a leader.
2734  Instruction *ValueOp = I->clone();
2735  if (MemAccess)
2736  TempToMemory.insert({ValueOp, MemAccess});
2737  bool SafeForPHIOfOps = true;
2738  VisitedOps.clear();
2739  for (auto &Op : ValueOp->operands()) {
2740  auto *OrigOp = &*Op;
2741  // When these operand changes, it could change whether there is a
2742  // leader for us or not, so we have to add additional users.
2743  if (isa<PHINode>(Op)) {
2744  Op = Op->DoPHITranslation(PHIBlock, PredBB);
2745  if (Op != OrigOp && Op != I)
2746  CurrentDeps.insert(Op);
2747  } else if (auto *ValuePHI = RealToTemp.lookup(Op)) {
2748  if (getBlockForValue(ValuePHI) == PHIBlock)
2749  Op = ValuePHI->getIncomingValueForBlock(PredBB);
2750  }
2751  // If we phi-translated the op, it must be safe.
2752  SafeForPHIOfOps =
2753  SafeForPHIOfOps &&
2754  (Op != OrigOp || OpIsSafeForPHIOfOps(Op, PHIBlock, VisitedOps));
2755  }
2756  // FIXME: For those things that are not safe we could generate
2757  // expressions all the way down, and see if this comes out to a
2758  // constant. For anything where that is true, and unsafe, we should
2759  // have made a phi-of-ops (or value numbered it equivalent to something)
2760  // for the pieces already.
2761  FoundVal = !SafeForPHIOfOps ? nullptr
2762  : findLeaderForInst(ValueOp, Visited,
2763  MemAccess, I, PredBB);
2764  ValueOp->deleteValue();
2765  if (!FoundVal) {
2766  // We failed to find a leader for the current ValueOp, but this might
2767  // change in case of the translated operands change.
2768  if (SafeForPHIOfOps)
2769  for (auto Dep : CurrentDeps)
2770  addAdditionalUsers(Dep, I);
2771 
2772  return nullptr;
2773  }
2774  Deps.insert(CurrentDeps.begin(), CurrentDeps.end());
2775  } else {
2776  LLVM_DEBUG(dbgs() << "Skipping phi of ops operand for incoming block "
2777  << getBlockName(PredBB)
2778  << " because the block is unreachable\n");
2779  FoundVal = UndefValue::get(I->getType());
2780  RevisitOnReachabilityChange[PHIBlock].set(InstrToDFSNum(I));
2781  }
2782 
2783  PHIOps.push_back({FoundVal, PredBB});
2784  LLVM_DEBUG(dbgs() << "Found phi of ops operand " << *FoundVal << " in "
2785  << getBlockName(PredBB) << "\n");
2786  }
2787  for (auto Dep : Deps)
2788  addAdditionalUsers(Dep, I);
2789  sortPHIOps(PHIOps);
2790  auto *E = performSymbolicPHIEvaluation(PHIOps, I, PHIBlock);
2791  if (isa<ConstantExpression>(E) || isa<VariableExpression>(E)) {
2792  LLVM_DEBUG(
2793  dbgs()
2794  << "Not creating real PHI of ops because it simplified to existing "
2795  "value or constant\n");
2796  // We have leaders for all operands, but do not create a real PHI node with
2797  // those leaders as operands, so the link between the operands and the
2798  // PHI-of-ops is not materialized in the IR. If any of those leaders
2799  // changes, the PHI-of-op may change also, so we need to add the operands as
2800  // additional users.
2801  for (auto &O : PHIOps)
2802  addAdditionalUsers(O.first, I);
2803 
2804  return E;
2805  }
2806  auto *ValuePHI = RealToTemp.lookup(I);
2807  bool NewPHI = false;
2808  if (!ValuePHI) {
2809  ValuePHI =
2810  PHINode::Create(I->getType(), OpPHI->getNumOperands(), "phiofops");
2811  addPhiOfOps(ValuePHI, PHIBlock, I);
2812  NewPHI = true;
2813  NumGVNPHIOfOpsCreated++;
2814  }
2815  if (NewPHI) {
2816  for (auto PHIOp : PHIOps)
2817  ValuePHI->addIncoming(PHIOp.first, PHIOp.second);
2818  } else {
2819  TempToBlock[ValuePHI] = PHIBlock;
2820  unsigned int i = 0;
2821  for (auto PHIOp : PHIOps) {
2822  ValuePHI->setIncomingValue(i, PHIOp.first);
2823  ValuePHI->setIncomingBlock(i, PHIOp.second);
2824  ++i;
2825  }
2826  }
2827  RevisitOnReachabilityChange[PHIBlock].set(InstrToDFSNum(I));
2828  LLVM_DEBUG(dbgs() << "Created phi of ops " << *ValuePHI << " for " << *I
2829  << "\n");
2830 
2831  return E;
2832 }
2833 
2834 // The algorithm initially places the values of the routine in the TOP
2835 // congruence class. The leader of TOP is the undetermined value `undef`.
2836 // When the algorithm has finished, values still in TOP are unreachable.
2837 void NewGVN::initializeCongruenceClasses(Function &F) {
2838  NextCongruenceNum = 0;
2839 
2840  // Note that even though we use the live on entry def as a representative
2841  // MemoryAccess, it is *not* the same as the actual live on entry def. We
2842  // have no real equivalemnt to undef for MemoryAccesses, and so we really
2843  // should be checking whether the MemoryAccess is top if we want to know if it
2844  // is equivalent to everything. Otherwise, what this really signifies is that
2845  // the access "it reaches all the way back to the beginning of the function"
2846 
2847  // Initialize all other instructions to be in TOP class.
2848  TOPClass = createCongruenceClass(nullptr, nullptr);
2849  TOPClass->setMemoryLeader(MSSA->getLiveOnEntryDef());
2850  // The live on entry def gets put into it's own class
2851  MemoryAccessToClass[MSSA->getLiveOnEntryDef()] =
2852  createMemoryClass(MSSA->getLiveOnEntryDef());
2853 
2854  for (auto DTN : nodes(DT)) {
2855  BasicBlock *BB = DTN->getBlock();
2856  // All MemoryAccesses are equivalent to live on entry to start. They must
2857  // be initialized to something so that initial changes are noticed. For
2858  // the maximal answer, we initialize them all to be the same as
2859  // liveOnEntry.
2860  auto *MemoryBlockDefs = MSSA->getBlockDefs(BB);
2861  if (MemoryBlockDefs)
2862  for (const auto &Def : *MemoryBlockDefs) {
2863  MemoryAccessToClass[&Def] = TOPClass;
2864  auto *MD = dyn_cast<MemoryDef>(&Def);
2865  // Insert the memory phis into the member list.
2866  if (!MD) {
2867  const MemoryPhi *MP = cast<MemoryPhi>(&Def);
2868  TOPClass->memory_insert(MP);
2869  MemoryPhiState.insert({MP, MPS_TOP});
2870  }
2871 
2872  if (MD && isa<StoreInst>(MD->getMemoryInst()))
2873  TOPClass->incStoreCount();
2874  }
2875 
2876  // FIXME: This is trying to discover which instructions are uses of phi
2877  // nodes. We should move this into one of the myriad of places that walk
2878  // all the operands already.
2879  for (auto &I : *BB) {
2880  if (isa<PHINode>(&I))
2881  for (auto *U : I.users())
2882  if (auto *UInst = dyn_cast<Instruction>(U))
2883  if (InstrToDFSNum(UInst) != 0 && okayForPHIOfOps(UInst))
2884  PHINodeUses.insert(UInst);
2885  // Don't insert void terminators into the class. We don't value number
2886  // them, and they just end up sitting in TOP.
2887  if (I.isTerminator() && I.getType()->isVoidTy())
2888  continue;
2889  TOPClass->insert(&I);
2890  ValueToClass[&I] = TOPClass;
2891  }
2892  }
2893 
2894  // Initialize arguments to be in their own unique congruence classes
2895  for (auto &FA : F.args())
2896  createSingletonCongruenceClass(&FA);
2897 }
2898 
2899 void NewGVN::cleanupTables() {
2900  for (unsigned i = 0, e = CongruenceClasses.size(); i != e; ++i) {
2901  LLVM_DEBUG(dbgs() << "Congruence class " << CongruenceClasses[i]->getID()
2902  << " has " << CongruenceClasses[i]->size()
2903  << " members\n");
2904  // Make sure we delete the congruence class (probably worth switching to
2905  // a unique_ptr at some point.
2906  delete CongruenceClasses[i];
2907  CongruenceClasses[i] = nullptr;
2908  }
2909 
2910  // Destroy the value expressions
2911  SmallVector<Instruction *, 8> TempInst(AllTempInstructions.begin(),
2912  AllTempInstructions.end());
2913  AllTempInstructions.clear();
2914 
2915  // We have to drop all references for everything first, so there are no uses
2916  // left as we delete them.
2917  for (auto *I : TempInst) {
2918  I->dropAllReferences();
2919  }
2920 
2921  while (!TempInst.empty()) {
2922  auto *I = TempInst.pop_back_val();
2923  I->deleteValue();
2924  }
2925 
2926  ValueToClass.clear();
2927  ArgRecycler.clear(ExpressionAllocator);
2928  ExpressionAllocator.Reset();
2929  CongruenceClasses.clear();
2930  ExpressionToClass.clear();
2931  ValueToExpression.clear();
2932  RealToTemp.clear();
2933  AdditionalUsers.clear();
2934  ExpressionToPhiOfOps.clear();
2935  TempToBlock.clear();
2936  TempToMemory.clear();
2937  PHINodeUses.clear();
2938  OpSafeForPHIOfOps.clear();
2939  ReachableBlocks.clear();
2940  ReachableEdges.clear();
2941 #ifndef NDEBUG
2942  ProcessedCount.clear();
2943 #endif
2944  InstrDFS.clear();
2945  InstructionsToErase.clear();
2946  DFSToInstr.clear();
2947  BlockInstRange.clear();
2948  TouchedInstructions.clear();
2949  MemoryAccessToClass.clear();
2950  PredicateToUsers.clear();
2951  MemoryToUsers.clear();
2952  RevisitOnReachabilityChange.clear();
2953 }
2954 
2955 // Assign local DFS number mapping to instructions, and leave space for Value
2956 // PHI's.
2957 std::pair<unsigned, unsigned> NewGVN::assignDFSNumbers(BasicBlock *B,
2958  unsigned Start) {
2959  unsigned End = Start;
2960  if (MemoryAccess *MemPhi = getMemoryAccess(B)) {
2961  InstrDFS[MemPhi] = End++;
2962  DFSToInstr.emplace_back(MemPhi);
2963  }
2964 
2965  // Then the real block goes next.
2966  for (auto &I : *B) {
2967  // There's no need to call isInstructionTriviallyDead more than once on
2968  // an instruction. Therefore, once we know that an instruction is dead
2969  // we change its DFS number so that it doesn't get value numbered.
2970  if (isInstructionTriviallyDead(&I, TLI)) {
2971  InstrDFS[&I] = 0;
2972  LLVM_DEBUG(dbgs() << "Skipping trivially dead instruction " << I << "\n");
2973  markInstructionForDeletion(&I);
2974  continue;
2975  }
2976  if (isa<PHINode>(&I))
2977  RevisitOnReachabilityChange[B].set(End);
2978  InstrDFS[&I] = End++;
2979  DFSToInstr.emplace_back(&I);
2980  }
2981 
2982  // All of the range functions taken half-open ranges (open on the end side).
2983  // So we do not subtract one from count, because at this point it is one
2984  // greater than the last instruction.
2985  return std::make_pair(Start, End);
2986 }
2987 
2988 void NewGVN::updateProcessedCount(const Value *V) {
2989 #ifndef NDEBUG
2990  if (ProcessedCount.count(V) == 0) {
2991  ProcessedCount.insert({V, 1});
2992  } else {
2993  ++ProcessedCount[V];
2994  assert(ProcessedCount[V] < 100 &&
2995  "Seem to have processed the same Value a lot");
2996  }
2997 #endif
2998 }
2999 
3000 // Evaluate MemoryPhi nodes symbolically, just like PHI nodes
3001 void NewGVN::valueNumberMemoryPhi(MemoryPhi *MP) {
3002  // If all the arguments are the same, the MemoryPhi has the same value as the
3003  // argument. Filter out unreachable blocks and self phis from our operands.
3004  // TODO: We could do cycle-checking on the memory phis to allow valueizing for
3005  // self-phi checking.
3006  const BasicBlock *PHIBlock = MP->getBlock();
3007  auto Filtered = make_filter_range(MP->operands(), [&](const Use &U) {
3008  return cast<MemoryAccess>(U) != MP &&
3009  !isMemoryAccessTOP(cast<MemoryAccess>(U)) &&
3010  ReachableEdges.count({MP->getIncomingBlock(U), PHIBlock});
3011  });
3012  // If all that is left is nothing, our memoryphi is undef. We keep it as
3013  // InitialClass. Note: The only case this should happen is if we have at
3014  // least one self-argument.
3015  if (Filtered.begin() == Filtered.end()) {
3016  if (setMemoryClass(MP, TOPClass))
3017  markMemoryUsersTouched(MP);
3018  return;
3019  }
3020 
3021  // Transform the remaining operands into operand leaders.
3022  // FIXME: mapped_iterator should have a range version.
3023  auto LookupFunc = [&](const Use &U) {
3024  return lookupMemoryLeader(cast<MemoryAccess>(U));
3025  };
3026  auto MappedBegin = map_iterator(Filtered.begin(), LookupFunc);
3027  auto MappedEnd = map_iterator(Filtered.end(), LookupFunc);
3028 
3029  // and now check if all the elements are equal.
3030  // Sadly, we can't use std::equals since these are random access iterators.
3031  const auto *AllSameValue = *MappedBegin;
3032  ++MappedBegin;
3033  bool AllEqual = std::all_of(
3034  MappedBegin, MappedEnd,
3035  [&AllSameValue](const MemoryAccess *V) { return V == AllSameValue; });
3036 
3037  if (AllEqual)
3038  LLVM_DEBUG(dbgs() << "Memory Phi value numbered to " << *AllSameValue
3039  << "\n");
3040  else
3041  LLVM_DEBUG(dbgs() << "Memory Phi value numbered to itself\n");
3042  // If it's equal to something, it's in that class. Otherwise, it has to be in
3043  // a class where it is the leader (other things may be equivalent to it, but
3044  // it needs to start off in its own class, which means it must have been the
3045  // leader, and it can't have stopped being the leader because it was never
3046  // removed).
3047  CongruenceClass *CC =
3048  AllEqual ? getMemoryClass(AllSameValue) : ensureLeaderOfMemoryClass(MP);
3049  auto OldState = MemoryPhiState.lookup(MP);
3050  assert(OldState != MPS_Invalid && "Invalid memory phi state");
3051  auto NewState = AllEqual ? MPS_Equivalent : MPS_Unique;
3052  MemoryPhiState[MP] = NewState;
3053  if (setMemoryClass(MP, CC) || OldState != NewState)
3054  markMemoryUsersTouched(MP);
3055 }
3056 
3057 // Value number a single instruction, symbolically evaluating, performing
3058 // congruence finding, and updating mappings.
3059 void NewGVN::valueNumberInstruction(Instruction *I) {
3060  LLVM_DEBUG(dbgs() << "Processing instruction " << *I << "\n");
3061  if (!I->isTerminator()) {
3062  const Expression *Symbolized = nullptr;
3063  SmallPtrSet<Value *, 2> Visited;
3064  if (DebugCounter::shouldExecute(VNCounter)) {
3065  auto Res = performSymbolicEvaluation(I, Visited);
3066  Symbolized = Res.Expr;
3067  addAdditionalUsers(Res, I);
3068 
3069  // Make a phi of ops if necessary
3070  if (Symbolized && !isa<ConstantExpression>(Symbolized) &&
3071  !isa<VariableExpression>(Symbolized) && PHINodeUses.count(I)) {
3072  auto *PHIE = makePossiblePHIOfOps(I, Visited);
3073  // If we created a phi of ops, use it.
3074  // If we couldn't create one, make sure we don't leave one lying around
3075  if (PHIE) {
3076  Symbolized = PHIE;
3077  } else if (auto *Op = RealToTemp.lookup(I)) {
3078  removePhiOfOps(I, Op);
3079  }
3080  }
3081  } else {
3082  // Mark the instruction as unused so we don't value number it again.
3083  InstrDFS[I] = 0;
3084  }
3085  // If we couldn't come up with a symbolic expression, use the unknown
3086  // expression
3087  if (Symbolized == nullptr)
3088  Symbolized = createUnknownExpression(I);
3089  performCongruenceFinding(I, Symbolized);
3090  } else {
3091  // Handle terminators that return values. All of them produce values we
3092  // don't currently understand. We don't place non-value producing
3093  // terminators in a class.
3094  if (!I->getType()->isVoidTy()) {
3095  auto *Symbolized = createUnknownExpression(I);
3096  performCongruenceFinding(I, Symbolized);
3097  }
3098  processOutgoingEdges(I, I->getParent());
3099  }
3100 }
3101 
3102 // Check if there is a path, using single or equal argument phi nodes, from
3103 // First to Second.
3104 bool NewGVN::singleReachablePHIPath(
3106  const MemoryAccess *Second) const {
3107  if (First == Second)
3108  return true;
3109  if (MSSA->isLiveOnEntryDef(First))
3110  return false;
3111 
3112  // This is not perfect, but as we're just verifying here, we can live with
3113  // the loss of precision. The real solution would be that of doing strongly
3114  // connected component finding in this routine, and it's probably not worth
3115  // the complexity for the time being. So, we just keep a set of visited
3116  // MemoryAccess and return true when we hit a cycle.
3117  if (Visited.count(First))
3118  return true;
3119  Visited.insert(First);
3120 
3121  const auto *EndDef = First;
3122  for (auto *ChainDef : optimized_def_chain(First)) {
3123  if (ChainDef == Second)
3124  return true;
3125  if (MSSA->isLiveOnEntryDef(ChainDef))
3126  return false;
3127  EndDef = ChainDef;
3128  }
3129  auto *MP = cast<MemoryPhi>(EndDef);
3130  auto ReachableOperandPred = [&](const Use &U) {
3131  return ReachableEdges.count({MP->getIncomingBlock(U), MP->getBlock()});
3132  };
3133  auto FilteredPhiArgs =
3134  make_filter_range(MP->operands(), ReachableOperandPred);
3135  SmallVector<const Value *, 32> OperandList;
3136  llvm::copy(FilteredPhiArgs, std::back_inserter(OperandList));
3137  bool Okay = is_splat(OperandList);
3138  if (Okay)
3139  return singleReachablePHIPath(Visited, cast<MemoryAccess>(OperandList[0]),
3140  Second);
3141  return false;
3142 }
3143 
3144 // Verify the that the memory equivalence table makes sense relative to the
3145 // congruence classes. Note that this checking is not perfect, and is currently
3146 // subject to very rare false negatives. It is only useful for
3147 // testing/debugging.
3148 void NewGVN::verifyMemoryCongruency() const {
3149 #ifndef NDEBUG
3150  // Verify that the memory table equivalence and memory member set match
3151  for (const auto *CC : CongruenceClasses) {
3152  if (CC == TOPClass || CC->isDead())
3153  continue;
3154  if (CC->getStoreCount() != 0) {
3155  assert((CC->getStoredValue() || !isa<StoreInst>(CC->getLeader())) &&
3156  "Any class with a store as a leader should have a "
3157  "representative stored value");
3158  assert(CC->getMemoryLeader() &&
3159  "Any congruence class with a store should have a "
3160  "representative access");
3161  }
3162 
3163  if (CC->getMemoryLeader())
3164  assert(MemoryAccessToClass.lookup(CC->getMemoryLeader()) == CC &&
3165  "Representative MemoryAccess does not appear to be reverse "
3166  "mapped properly");
3167  for (auto M : CC->memory())
3168  assert(MemoryAccessToClass.lookup(M) == CC &&
3169  "Memory member does not appear to be reverse mapped properly");
3170  }
3171 
3172  // Anything equivalent in the MemoryAccess table should be in the same
3173  // congruence class.
3174 
3175  // Filter out the unreachable and trivially dead entries, because they may
3176  // never have been updated if the instructions were not processed.
3177  auto ReachableAccessPred =
3178  [&](const std::pair<const MemoryAccess *, CongruenceClass *> Pair) {
3179  bool Result = ReachableBlocks.count(Pair.first->getBlock());
3180  if (!Result || MSSA->isLiveOnEntryDef(Pair.first) ||
3181  MemoryToDFSNum(Pair.first) == 0)
3182  return false;
3183  if (auto *MemDef = dyn_cast<MemoryDef>(Pair.first))
3184  return !isInstructionTriviallyDead(MemDef->getMemoryInst());
3185 
3186  // We could have phi nodes which operands are all trivially dead,
3187  // so we don't process them.
3188  if (auto *MemPHI = dyn_cast<MemoryPhi>(Pair.first)) {
3189  for (auto &U : MemPHI->incoming_values()) {
3190  if (auto *I = dyn_cast<Instruction>(&*U)) {
3192  return true;
3193  }
3194  }
3195  return false;
3196  }
3197 
3198  return true;
3199  };
3200 
3201  auto Filtered = make_filter_range(MemoryAccessToClass, ReachableAccessPred);
3202  for (auto KV : Filtered) {
3203  if (auto *FirstMUD = dyn_cast<MemoryUseOrDef>(KV.first)) {
3204  auto *SecondMUD = dyn_cast<MemoryUseOrDef>(KV.second->getMemoryLeader());
3205  if (FirstMUD && SecondMUD) {
3207  assert((singleReachablePHIPath(VisitedMAS, FirstMUD, SecondMUD) ||
3208  ValueToClass.lookup(FirstMUD->getMemoryInst()) ==
3209  ValueToClass.lookup(SecondMUD->getMemoryInst())) &&
3210  "The instructions for these memory operations should have "
3211  "been in the same congruence class or reachable through"
3212  "a single argument phi");
3213  }
3214  } else if (auto *FirstMP = dyn_cast<MemoryPhi>(KV.first)) {
3215  // We can only sanely verify that MemoryDefs in the operand list all have
3216  // the same class.
3217  auto ReachableOperandPred = [&](const Use &U) {
3218  return ReachableEdges.count(
3219  {FirstMP->getIncomingBlock(U), FirstMP->getBlock()}) &&
3220  isa<MemoryDef>(U);
3221 
3222  };
3223  // All arguments should in the same class, ignoring unreachable arguments
3224  auto FilteredPhiArgs =
3225  make_filter_range(FirstMP->operands(), ReachableOperandPred);
3227  std::transform(FilteredPhiArgs.begin(), FilteredPhiArgs.end(),
3228  std::back_inserter(PhiOpClasses), [&](const Use &U) {
3229  const MemoryDef *MD = cast<MemoryDef>(U);
3230  return ValueToClass.lookup(MD->getMemoryInst());
3231  });
3232  assert(is_splat(PhiOpClasses) &&
3233  "All MemoryPhi arguments should be in the same class");
3234  }
3235  }
3236 #endif
3237 }
3238 
3239 // Verify that the sparse propagation we did actually found the maximal fixpoint
3240 // We do this by storing the value to class mapping, touching all instructions,
3241 // and redoing the iteration to see if anything changed.
3242 void NewGVN::verifyIterationSettled(Function &F) {
3243 #ifndef NDEBUG
3244  LLVM_DEBUG(dbgs() << "Beginning iteration verification\n");
3245  if (DebugCounter::isCounterSet(VNCounter))
3246  DebugCounter::setCounterValue(VNCounter, StartingVNCounter);
3247 
3248  // Note that we have to store the actual classes, as we may change existing
3249  // classes during iteration. This is because our memory iteration propagation
3250  // is not perfect, and so may waste a little work. But it should generate
3251  // exactly the same congruence classes we have now, with different IDs.
3252  std::map<const Value *, CongruenceClass> BeforeIteration;
3253 
3254  for (auto &KV : ValueToClass) {
3255  if (auto *I = dyn_cast<Instruction>(KV.first))
3256  // Skip unused/dead instructions.
3257  if (InstrToDFSNum(I) == 0)
3258  continue;
3259  BeforeIteration.insert({KV.first, *KV.second});
3260  }
3261 
3262  TouchedInstructions.set();
3263  TouchedInstructions.reset(0);
3264  iterateTouchedInstructions();
3266  EqualClasses;
3267  for (const auto &KV : ValueToClass) {
3268  if (auto *I = dyn_cast<Instruction>(KV.first))
3269  // Skip unused/dead instructions.
3270  if (InstrToDFSNum(I) == 0)
3271  continue;
3272  // We could sink these uses, but i think this adds a bit of clarity here as
3273  // to what we are comparing.
3274  auto *BeforeCC = &BeforeIteration.find(KV.first)->second;
3275  auto *AfterCC = KV.second;
3276  // Note that the classes can't change at this point, so we memoize the set
3277  // that are equal.
3278  if (!EqualClasses.count({BeforeCC, AfterCC})) {
3279  assert(BeforeCC->isEquivalentTo(AfterCC) &&
3280  "Value number changed after main loop completed!");
3281  EqualClasses.insert({BeforeCC, AfterCC});
3282  }
3283  }
3284 #endif
3285 }
3286 
3287 // Verify that for each store expression in the expression to class mapping,
3288 // only the latest appears, and multiple ones do not appear.
3289 // Because loads do not use the stored value when doing equality with stores,
3290 // if we don't erase the old store expressions from the table, a load can find
3291 // a no-longer valid StoreExpression.
3292 void NewGVN::verifyStoreExpressions() const {
3293 #ifndef NDEBUG
3294  // This is the only use of this, and it's not worth defining a complicated
3295  // densemapinfo hash/equality function for it.
3296  std::set<
3297  std::pair<const Value *,
3298  std::tuple<const Value *, const CongruenceClass *, Value *>>>
3299  StoreExpressionSet;
3300  for (const auto &KV : ExpressionToClass) {
3301  if (auto *SE = dyn_cast<StoreExpression>(KV.first)) {
3302  // Make sure a version that will conflict with loads is not already there
3303  auto Res = StoreExpressionSet.insert(
3304  {SE->getOperand(0), std::make_tuple(SE->getMemoryLeader(), KV.second,
3305  SE->getStoredValue())});
3306  bool Okay = Res.second;
3307  // It's okay to have the same expression already in there if it is
3308  // identical in nature.
3309  // This can happen when the leader of the stored value changes over time.
3310  if (!Okay)
3311  Okay = (std::get<1>(Res.first->second) == KV.second) &&
3312  (lookupOperandLeader(std::get<2>(Res.first->second)) ==
3313  lookupOperandLeader(SE->getStoredValue()));
3314  assert(Okay && "Stored expression conflict exists in expression table");
3315  auto *ValueExpr = ValueToExpression.lookup(SE->getStoreInst());
3316  assert(ValueExpr && ValueExpr->equals(*SE) &&
3317  "StoreExpression in ExpressionToClass is not latest "
3318  "StoreExpression for value");
3319  }
3320  }
3321 #endif
3322 }
3323 
3324 // This is the main value numbering loop, it iterates over the initial touched
3325 // instruction set, propagating value numbers, marking things touched, etc,
3326 // until the set of touched instructions is completely empty.
3327 void NewGVN::iterateTouchedInstructions() {
3328  unsigned int Iterations = 0;
3329  // Figure out where touchedinstructions starts
3330  int FirstInstr = TouchedInstructions.find_first();
3331  // Nothing set, nothing to iterate, just return.
3332  if (FirstInstr == -1)
3333  return;
3334  const BasicBlock *LastBlock = getBlockForValue(InstrFromDFSNum(FirstInstr));
3335  while (TouchedInstructions.any()) {
3336  ++Iterations;
3337  // Walk through all the instructions in all the blocks in RPO.
3338  // TODO: As we hit a new block, we should push and pop equalities into a
3339  // table lookupOperandLeader can use, to catch things PredicateInfo
3340  // might miss, like edge-only equivalences.
3341  for (unsigned InstrNum : TouchedInstructions.set_bits()) {
3342 
3343  // This instruction was found to be dead. We don't bother looking
3344  // at it again.
3345  if (InstrNum == 0) {
3346  TouchedInstructions.reset(InstrNum);
3347  continue;
3348  }
3349 
3350  Value *V = InstrFromDFSNum(InstrNum);
3351  const BasicBlock *CurrBlock = getBlockForValue(V);
3352 
3353  // If we hit a new block, do reachability processing.
3354  if (CurrBlock != LastBlock) {
3355  LastBlock = CurrBlock;
3356  bool BlockReachable = ReachableBlocks.count(CurrBlock);
3357  const auto &CurrInstRange = BlockInstRange.lookup(CurrBlock);
3358 
3359  // If it's not reachable, erase any touched instructions and move on.
3360  if (!BlockReachable) {
3361  TouchedInstructions.reset(CurrInstRange.first, CurrInstRange.second);
3362  LLVM_DEBUG(dbgs() << "Skipping instructions in block "
3363  << getBlockName(CurrBlock)
3364  << " because it is unreachable\n");
3365  continue;
3366  }
3367  updateProcessedCount(CurrBlock);
3368  }
3369  // Reset after processing (because we may mark ourselves as touched when
3370  // we propagate equalities).
3371  TouchedInstructions.reset(InstrNum);
3372 
3373  if (auto *MP = dyn_cast<MemoryPhi>(V)) {
3374  LLVM_DEBUG(dbgs() << "Processing MemoryPhi " << *MP << "\n");
3375  valueNumberMemoryPhi(MP);
3376  } else if (auto *I = dyn_cast<Instruction>(V)) {
3377  valueNumberInstruction(I);
3378  } else {
3379  llvm_unreachable("Should have been a MemoryPhi or Instruction");
3380  }
3381  updateProcessedCount(V);
3382  }
3383  }
3384  NumGVNMaxIterations = std::max(NumGVNMaxIterations.getValue(), Iterations);
3385 }
3386 
3387 // This is the main transformation entry point.
3388 bool NewGVN::runGVN() {
3389  if (DebugCounter::isCounterSet(VNCounter))
3390  StartingVNCounter = DebugCounter::getCounterValue(VNCounter);
3391  bool Changed = false;
3392  NumFuncArgs = F.arg_size();
3393  MSSAWalker = MSSA->getWalker();
3394  SingletonDeadExpression = new (ExpressionAllocator) DeadExpression();
3395 
3396  // Count number of instructions for sizing of hash tables, and come
3397  // up with a global dfs numbering for instructions.
3398  unsigned ICount = 1;
3399  // Add an empty instruction to account for the fact that we start at 1
3400  DFSToInstr.emplace_back(nullptr);
3401  // Note: We want ideal RPO traversal of the blocks, which is not quite the
3402  // same as dominator tree order, particularly with regard whether backedges
3403  // get visited first or second, given a block with multiple successors.
3404  // If we visit in the wrong order, we will end up performing N times as many
3405  // iterations.
3406  // The dominator tree does guarantee that, for a given dom tree node, it's
3407  // parent must occur before it in the RPO ordering. Thus, we only need to sort
3408  // the siblings.
3410  unsigned Counter = 0;
3411  for (auto &B : RPOT) {
3412  auto *Node = DT->getNode(B);
3413  assert(Node && "RPO and Dominator tree should have same reachability");
3414  RPOOrdering[Node] = ++Counter;
3415  }
3416  // Sort dominator tree children arrays into RPO.
3417  for (auto &B : RPOT) {
3418  auto *Node = DT->getNode(B);
3419  if (Node->getNumChildren() > 1)
3420  llvm::sort(*Node, [&](const DomTreeNode *A, const DomTreeNode *B) {
3421  return RPOOrdering[A] < RPOOrdering[B];
3422  });
3423  }
3424 
3425  // Now a standard depth first ordering of the domtree is equivalent to RPO.
3426  for (auto DTN : depth_first(DT->getRootNode())) {
3427  BasicBlock *B = DTN->getBlock();
3428  const auto &BlockRange = assignDFSNumbers(B, ICount);
3429  BlockInstRange.insert({B, BlockRange});
3430  ICount += BlockRange.second - BlockRange.first;
3431  }
3432  initializeCongruenceClasses(F);
3433 
3434  TouchedInstructions.resize(ICount);
3435  // Ensure we don't end up resizing the expressionToClass map, as
3436  // that can be quite expensive. At most, we have one expression per
3437  // instruction.
3438  ExpressionToClass.reserve(ICount);
3439 
3440  // Initialize the touched instructions to include the entry block.
3441  const auto &InstRange = BlockInstRange.lookup(&F.getEntryBlock());
3442  TouchedInstructions.set(InstRange.first, InstRange.second);
3443  LLVM_DEBUG(dbgs() << "Block " << getBlockName(&F.getEntryBlock())
3444  << " marked reachable\n");
3445  ReachableBlocks.insert(&F.getEntryBlock());
3446 
3447  iterateTouchedInstructions();
3448  verifyMemoryCongruency();
3449  verifyIterationSettled(F);
3450  verifyStoreExpressions();
3451 
3452  Changed |= eliminateInstructions(F);
3453 
3454  // Delete all instructions marked for deletion.
3455  for (Instruction *ToErase : InstructionsToErase) {
3456  if (!ToErase->use_empty())
3457  ToErase->replaceAllUsesWith(UndefValue::get(ToErase->getType()));
3458 
3459  assert(ToErase->getParent() &&
3460  "BB containing ToErase deleted unexpectedly!");
3461  ToErase->eraseFromParent();
3462  }
3463  Changed |= !InstructionsToErase.empty();
3464 
3465  // Delete all unreachable blocks.
3466  auto UnreachableBlockPred = [&](const BasicBlock &BB) {
3467  return !ReachableBlocks.count(&BB);
3468  };
3469 
3470  for (auto &BB : make_filter_range(F, UnreachableBlockPred)) {
3471  LLVM_DEBUG(dbgs() << "We believe block " << getBlockName(&BB)
3472  << " is unreachable\n");
3473  deleteInstructionsInBlock(&BB);
3474  Changed = true;
3475  }
3476 
3477  cleanupTables();
3478  return Changed;
3479 }
3480 
3482  int DFSIn = 0;
3483  int DFSOut = 0;
3484  int LocalNum = 0;
3485 
3486  // Only one of Def and U will be set.
3487  // The bool in the Def tells us whether the Def is the stored value of a
3488  // store.
3490  Use *U = nullptr;
3491 
3492  bool operator<(const ValueDFS &Other) const {
3493  // It's not enough that any given field be less than - we have sets
3494  // of fields that need to be evaluated together to give a proper ordering.
3495  // For example, if you have;
3496  // DFS (1, 3)
3497  // Val 0
3498  // DFS (1, 2)
3499  // Val 50
3500  // We want the second to be less than the first, but if we just go field
3501  // by field, we will get to Val 0 < Val 50 and say the first is less than
3502  // the second. We only want it to be less than if the DFS orders are equal.
3503  //
3504  // Each LLVM instruction only produces one value, and thus the lowest-level
3505  // differentiator that really matters for the stack (and what we use as as a
3506  // replacement) is the local dfs number.
3507  // Everything else in the structure is instruction level, and only affects
3508  // the order in which we will replace operands of a given instruction.
3509  //
3510  // For a given instruction (IE things with equal dfsin, dfsout, localnum),
3511  // the order of replacement of uses does not matter.
3512  // IE given,
3513  // a = 5
3514  // b = a + a
3515  // When you hit b, you will have two valuedfs with the same dfsin, out, and
3516  // localnum.
3517  // The .val will be the same as well.
3518  // The .u's will be different.
3519  // You will replace both, and it does not matter what order you replace them
3520  // in (IE whether you replace operand 2, then operand 1, or operand 1, then
3521  // operand 2).
3522  // Similarly for the case of same dfsin, dfsout, localnum, but different
3523  // .val's
3524  // a = 5
3525  // b = 6
3526  // c = a + b
3527  // in c, we will a valuedfs for a, and one for b,with everything the same
3528  // but .val and .u.
3529  // It does not matter what order we replace these operands in.
3530  // You will always end up with the same IR, and this is guaranteed.
3531  return std::tie(DFSIn, DFSOut, LocalNum, Def, U) <
3532  std::tie(Other.DFSIn, Other.DFSOut, Other.LocalNum, Other.Def,
3533  Other.U);
3534  }
3535 };
3536 
3537 // This function converts the set of members for a congruence class from values,
3538 // to sets of defs and uses with associated DFS info. The total number of
3539 // reachable uses for each value is stored in UseCount, and instructions that
3540 // seem
3541 // dead (have no non-dead uses) are stored in ProbablyDead.
3542 void NewGVN::convertClassToDFSOrdered(
3543  const CongruenceClass &Dense, SmallVectorImpl<ValueDFS> &DFSOrderedSet,
3545  SmallPtrSetImpl<Instruction *> &ProbablyDead) const {
3546  for (auto D : Dense) {
3547  // First add the value.
3548  BasicBlock *BB = getBlockForValue(D);
3549  // Constants are handled prior to ever calling this function, so
3550  // we should only be left with instructions as members.
3551  assert(BB && "Should have figured out a basic block for value");
3552  ValueDFS VDDef;
3553  DomTreeNode *DomNode = DT->getNode(BB);
3554  VDDef.DFSIn = DomNode->getDFSNumIn();
3555  VDDef.DFSOut = DomNode->getDFSNumOut();
3556  // If it's a store, use the leader of the value operand, if it's always
3557  // available, or the value operand. TODO: We could do dominance checks to
3558  // find a dominating leader, but not worth it ATM.
3559  if (auto *SI = dyn_cast<StoreInst>(D)) {
3560  auto Leader = lookupOperandLeader(SI->getValueOperand());
3561  if (alwaysAvailable(Leader)) {
3562  VDDef.Def.setPointer(Leader);
3563  } else {
3564  VDDef.Def.setPointer(SI->getValueOperand());
3565  VDDef.Def.setInt(true);
3566  }
3567  } else {
3568  VDDef.Def.setPointer(D);
3569  }
3570  assert(isa<Instruction>(D) &&
3571  "The dense set member should always be an instruction");
3572  Instruction *Def = cast<Instruction>(D);
3573  VDDef.LocalNum = InstrToDFSNum(D);
3574  DFSOrderedSet.push_back(VDDef);
3575  // If there is a phi node equivalent, add it
3576  if (auto *PN = RealToTemp.lookup(Def)) {
3577  auto *PHIE =
3578  dyn_cast_or_null<PHIExpression>(ValueToExpression.lookup(Def));
3579  if (PHIE) {
3580  VDDef.Def.setInt(false);
3581  VDDef.Def.setPointer(PN);
3582  VDDef.LocalNum = 0;
3583  DFSOrderedSet.push_back(VDDef);
3584  }
3585  }
3586 
3587  unsigned int UseCount = 0;
3588  // Now add the uses.
3589  for (auto &U : Def->uses()) {
3590  if (auto *I = dyn_cast<Instruction>(U.getUser())) {
3591  // Don't try to replace into dead uses
3592  if (InstructionsToErase.count(I))
3593  continue;
3594  ValueDFS VDUse;
3595  // Put the phi node uses in the incoming block.
3596  BasicBlock *IBlock;
3597  if (auto *P = dyn_cast<PHINode>(I)) {
3598  IBlock = P->getIncomingBlock(U);
3599  // Make phi node users appear last in the incoming block
3600  // they are from.
3601  VDUse.LocalNum = InstrDFS.size() + 1;
3602  } else {
3603  IBlock = getBlockForValue(I);
3604  VDUse.LocalNum = InstrToDFSNum(I);
3605  }
3606 
3607  // Skip uses in unreachable blocks, as we're going
3608  // to delete them.
3609  if (ReachableBlocks.count(IBlock) == 0)
3610  continue;
3611 
3612  DomTreeNode *DomNode = DT->getNode(IBlock);
3613  VDUse.DFSIn = DomNode->getDFSNumIn();
3614  VDUse.DFSOut = DomNode->getDFSNumOut();
3615  VDUse.U = &U;
3616  ++UseCount;
3617  DFSOrderedSet.emplace_back(VDUse);
3618  }
3619  }
3620 
3621  // If there are no uses, it's probably dead (but it may have side-effects,
3622  // so not definitely dead. Otherwise, store the number of uses so we can
3623  // track if it becomes dead later).
3624  if (UseCount == 0)
3625  ProbablyDead.insert(Def);
3626  else
3627  UseCounts[Def] = UseCount;
3628  }
3629 }
3630 
3631 // This function converts the set of members for a congruence class from values,
3632 // to the set of defs for loads and stores, with associated DFS info.
3633 void NewGVN::convertClassToLoadsAndStores(
3634  const CongruenceClass &Dense,
3635  SmallVectorImpl<ValueDFS> &LoadsAndStores) const {
3636  for (auto D : Dense) {
3637  if (!isa<LoadInst>(D) && !isa<StoreInst>(D))
3638  continue;
3639 
3640  BasicBlock *BB = getBlockForValue(D);
3641  ValueDFS VD;
3642  DomTreeNode *DomNode = DT->getNode(BB);
3643  VD.DFSIn = DomNode->getDFSNumIn();
3644  VD.DFSOut = DomNode->getDFSNumOut();
3645  VD.Def.setPointer(D);
3646 
3647  // If it's an instruction, use the real local dfs number.
3648  if (auto *I = dyn_cast<Instruction>(D))
3649  VD.LocalNum = InstrToDFSNum(I);
3650  else
3651  llvm_unreachable("Should have been an instruction");
3652 
3653  LoadsAndStores.emplace_back(VD);
3654  }
3655 }
3656 
3659  I->replaceAllUsesWith(Repl);
3660 }
3661 
3662 void NewGVN::deleteInstructionsInBlock(BasicBlock *BB) {
3663  LLVM_DEBUG(dbgs() << " BasicBlock Dead:" << *BB);
3664  ++NumGVNBlocksDeleted;
3665 
3666  // Delete the instructions backwards, as it has a reduced likelihood of having
3667  // to update as many def-use and use-def chains. Start after the terminator.
3668  auto StartPoint = BB->rbegin();
3669  ++StartPoint;
3670  // Note that we explicitly recalculate BB->rend() on each iteration,
3671  // as it may change when we remove the first instruction.
3672  for (BasicBlock::reverse_iterator I(StartPoint); I != BB->rend();) {
3673  Instruction &Inst = *I++;
3674  if (!Inst.use_empty())
3676  if (isa<LandingPadInst>(Inst))
3677  continue;
3678  salvageKnowledge(&Inst, AC);
3679 
3680  Inst.eraseFromParent();
3681  ++NumGVNInstrDeleted;
3682  }
3683  // Now insert something that simplifycfg will turn into an unreachable.
3684  Type *Int8Ty = Type::getInt8Ty(BB->getContext());
3685  new StoreInst(UndefValue::get(Int8Ty),
3687  BB->getTerminator());
3688 }
3689 
3690 void NewGVN::markInstructionForDeletion(Instruction *I) {
3691  LLVM_DEBUG(dbgs() << "Marking " << *I << " for deletion\n");
3692  InstructionsToErase.insert(I);
3693 }
3694 
3695 void NewGVN::replaceInstruction(Instruction *I, Value *V) {
3696  LLVM_DEBUG(dbgs() << "Replacing " << *I << " with " << *V << "\n");
3698  // We save the actual erasing to avoid invalidating memory
3699  // dependencies until we are done with everything.
3700  markInstructionForDeletion(I);
3701 }
3702 
3703 namespace {
3704 
3705 // This is a stack that contains both the value and dfs info of where
3706 // that value is valid.
3707 class ValueDFSStack {
3708 public:
3709  Value *back() const { return ValueStack.back(); }
3710  std::pair<int, int> dfs_back() const { return DFSStack.back(); }
3711 
3712  void push_back(Value *V, int DFSIn, int DFSOut) {
3713  ValueStack.emplace_back(V);
3714  DFSStack.emplace_back(DFSIn, DFSOut);
3715  }
3716 
3717  bool empty() const { return DFSStack.empty(); }
3718 
3719  bool isInScope(int DFSIn, int DFSOut) const {
3720  if (empty())
3721  return false;
3722  return DFSIn >= DFSStack.back().first && DFSOut <= DFSStack.back().second;
3723  }
3724 
3725  void popUntilDFSScope(int DFSIn, int DFSOut) {
3726 
3727  // These two should always be in sync at this point.
3728  assert(ValueStack.size() == DFSStack.size() &&
3729  "Mismatch between ValueStack and DFSStack");
3730  while (
3731  !DFSStack.empty() &&
3732  !(DFSIn >= DFSStack.back().first && DFSOut <= DFSStack.back().second)) {
3733  DFSStack.pop_back();
3734  ValueStack.pop_back();
3735  }
3736  }
3737 
3738 private:
3739  SmallVector<Value *, 8> ValueStack;
3740  SmallVector<std::pair<int, int>, 8> DFSStack;
3741 };
3742 
3743 } // end anonymous namespace
3744 
3745 // Given an expression, get the congruence class for it.
3746 CongruenceClass *NewGVN::getClassForExpression(const Expression *E) const {
3747  if (auto *VE = dyn_cast<VariableExpression>(E))
3748  return ValueToClass.lookup(VE->getVariableValue());
3749  else if (isa<DeadExpression>(E))
3750  return TOPClass;
3751  return ExpressionToClass.lookup(E);
3752 }
3753 
3754 // Given a value and a basic block we are trying to see if it is available in,
3755 // see if the value has a leader available in that block.
3756 Value *NewGVN::findPHIOfOpsLeader(const Expression *E,
3757  const Instruction *OrigInst,
3758  const BasicBlock *BB) const {
3759  // It would already be constant if we could make it constant
3760  if (auto *CE = dyn_cast<ConstantExpression>(E))
3761  return CE->getConstantValue();
3762  if (auto *VE = dyn_cast<VariableExpression>(E)) {
3763  auto *V = VE->getVariableValue();
3764  if (alwaysAvailable(V) || DT->dominates(getBlockForValue(V), BB))
3765  return VE->getVariableValue();
3766  }
3767 
3768  auto *CC = getClassForExpression(E);
3769  if (!CC)
3770  return nullptr;
3771  if (alwaysAvailable(CC->getLeader()))
3772  return CC->getLeader();
3773 
3774  for (auto Member : *CC) {
3775  auto *MemberInst = dyn_cast<Instruction>(Member);
3776  if (MemberInst == OrigInst)
3777  continue;
3778  // Anything that isn't an instruction is always available.
3779  if (!MemberInst)
3780  return Member;
3781  if (DT->dominates(getBlockForValue(MemberInst), BB))
3782  return Member;
3783  }
3784  return nullptr;
3785 }
3786 
3787 bool NewGVN::eliminateInstructions(Function &F) {
3788  // This is a non-standard eliminator. The normal way to eliminate is
3789  // to walk the dominator tree in order, keeping track of available
3790  // values, and eliminating them. However, this is mildly
3791  // pointless. It requires doing lookups on every instruction,
3792  // regardless of whether we will ever eliminate it. For
3793  // instructions part of most singleton congruence classes, we know we
3794  // will never eliminate them.
3795 
3796  // Instead, this eliminator looks at the congruence classes directly, sorts
3797  // them into a DFS ordering of the dominator tree, and then we just
3798  // perform elimination straight on the sets by walking the congruence
3799  // class member uses in order, and eliminate the ones dominated by the
3800  // last member. This is worst case O(E log E) where E = number of
3801  // instructions in a single congruence class. In theory, this is all
3802  // instructions. In practice, it is much faster, as most instructions are
3803  // either in singleton congruence classes or can't possibly be eliminated
3804  // anyway (if there are no overlapping DFS ranges in class).
3805  // When we find something not dominated, it becomes the new leader
3806  // for elimination purposes.
3807  // TODO: If we wanted to be faster, We could remove any members with no
3808  // overlapping ranges while sorting, as we will never eliminate anything
3809  // with those members, as they don't dominate anything else in our set.
3810 
3811  bool AnythingReplaced = false;
3812 
3813  // Since we are going to walk the domtree anyway, and we can't guarantee the
3814  // DFS numbers are updated, we compute some ourselves.
3815  DT->updateDFSNumbers();
3816 
3817  // Go through all of our phi nodes, and kill the arguments associated with
3818  // unreachable edges.
3819  auto ReplaceUnreachablePHIArgs = [&](PHINode *PHI, BasicBlock *BB) {
3820  for (auto &Operand : PHI->incoming_values())
3821  if (!ReachableEdges.count({PHI->getIncomingBlock(Operand), BB})) {
3822  LLVM_DEBUG(dbgs() << "Replacing incoming value of " << PHI
3823  << " for block "
3824  << getBlockName(PHI->getIncomingBlock(Operand))
3825  << " with undef due to it being unreachable\n");
3826  Operand.set(UndefValue::get(PHI->getType()));
3827  }
3828  };
3829  // Replace unreachable phi arguments.
3830  // At this point, RevisitOnReachabilityChange only contains:
3831  //
3832  // 1. PHIs
3833  // 2. Temporaries that will convert to PHIs
3834  // 3. Operations that are affected by an unreachable edge but do not fit into
3835  // 1 or 2 (rare).
3836  // So it is a slight overshoot of what we want. We could make it exact by
3837  // using two SparseBitVectors per block.
3838  DenseMap<const BasicBlock *, unsigned> ReachablePredCount;
3839  for (auto &KV : ReachableEdges)
3840  ReachablePredCount[KV.getEnd()]++;
3841  for (auto &BBPair : RevisitOnReachabilityChange) {
3842  for (auto InstNum : BBPair.second) {
3843  auto *Inst = InstrFromDFSNum(InstNum);
3844  auto *PHI = dyn_cast<PHINode>(Inst);
3845  PHI = PHI ? PHI : dyn_cast_or_null<PHINode>(RealToTemp.lookup(Inst));
3846  if (!PHI)
3847  continue;
3848  auto *BB = BBPair.first;
3849  if (ReachablePredCount.lookup(BB) != PHI->getNumIncomingValues())
3850  ReplaceUnreachablePHIArgs(PHI, BB);
3851  }
3852  }
3853 
3854  // Map to store the use counts
3856  for (auto *CC : reverse(CongruenceClasses)) {
3857  LLVM_DEBUG(dbgs() << "Eliminating in congruence class " << CC->getID()
3858  << "\n");
3859  // Track the equivalent store info so we can decide whether to try
3860  // dead store elimination.
3861  SmallVector<ValueDFS, 8> PossibleDeadStores;
3862  SmallPtrSet<Instruction *, 8> ProbablyDead;
3863  if (CC->isDead() || CC->empty())
3864  continue;
3865  // Everything still in the TOP class is unreachable or dead.
3866  if (CC == TOPClass) {
3867  for (auto M : *CC) {
3868  auto *VTE = ValueToExpression.lookup(M);
3869  if (VTE && isa<DeadExpression>(VTE))
3870  markInstructionForDeletion(cast<Instruction>(M));
3871  assert((!ReachableBlocks.count(cast<Instruction>(M)->getParent()) ||
3872  InstructionsToErase.count(cast<Instruction>(M))) &&
3873  "Everything in TOP should be unreachable or dead at this "
3874  "point");
3875  }
3876  continue;
3877  }
3878 
3879  assert(CC->getLeader() && "We should have had a leader");
3880  // If this is a leader that is always available, and it's a
3881  // constant or has no equivalences, just replace everything with
3882  // it. We then update the congruence class with whatever members
3883  // are left.
3884  Value *Leader =
3885  CC->getStoredValue() ? CC->getStoredValue() : CC->getLeader();
3886  if (alwaysAvailable(Leader)) {
3887  CongruenceClass::MemberSet MembersLeft;
3888  for (auto M : *CC) {
3889  Value *Member = M;
3890  // Void things have no uses we can replace.
3891  if (Member == Leader || !isa<Instruction>(Member) ||
3892  Member->getType()->isVoidTy()) {
3893  MembersLeft.insert(Member);
3894  continue;
3895  }
3896  LLVM_DEBUG(dbgs() << "Found replacement " << *(Leader) << " for "
3897  << *Member << "\n");
3898  auto *I = cast<Instruction>(Member);
3899  assert(Leader != I && "About to accidentally remove our leader");
3900  replaceInstruction(I, Leader);
3901  AnythingReplaced = true;
3902  }
3903  CC->swap(MembersLeft);
3904  } else {
3905  // If this is a singleton, we can skip it.
3906  if (CC->size() != 1 || RealToTemp.count(Leader)) {
3907  // This is a stack because equality replacement/etc may place
3908  // constants in the middle of the member list, and we want to use
3909  // those constant values in preference to the current leader, over
3910  // the scope of those constants.
3911  ValueDFSStack EliminationStack;
3912 
3913  // Convert the members to DFS ordered sets and then merge them.
3914  SmallVector<ValueDFS, 8> DFSOrderedSet;
3915  convertClassToDFSOrdered(*CC, DFSOrderedSet, UseCounts, ProbablyDead);
3916 
3917  // Sort the whole thing.
3918  llvm::sort(DFSOrderedSet);
3919  for (auto &VD : DFSOrderedSet) {
3920  int MemberDFSIn = VD.DFSIn;
3921  int MemberDFSOut = VD.DFSOut;
3922  Value *Def = VD.Def.getPointer();
3923  bool FromStore = VD.Def.getInt();
3924  Use *U = VD.U;
3925  // We ignore void things because we can't get a value from them.
3926  if (Def && Def->getType()->isVoidTy())
3927  continue;
3928  auto *DefInst = dyn_cast_or_null<Instruction>(Def);
3929  if (DefInst && AllTempInstructions.count(DefInst)) {
3930  auto *PN = cast<PHINode>(DefInst);
3931 
3932  // If this is a value phi and that's the expression we used, insert
3933  // it into the program
3934  // remove from temp instruction list.
3935  AllTempInstructions.erase(PN);
3936  auto *DefBlock = getBlockForValue(Def);
3937  LLVM_DEBUG(dbgs() << "Inserting fully real phi of ops" << *Def
3938  << " into block "
3939  << getBlockName(getBlockForValue(Def)) << "\n");
3940  PN->insertBefore(&DefBlock->front());
3941  Def = PN;
3942  NumGVNPHIOfOpsEliminations++;
3943  }
3944 
3945  if (EliminationStack.empty()) {
3946  LLVM_DEBUG(dbgs() << "Elimination Stack is empty\n");
3947  } else {
3948  LLVM_DEBUG(dbgs() << "Elimination Stack Top DFS numbers are ("
3949  << EliminationStack.dfs_back().first << ","
3950  << EliminationStack.dfs_back().second << ")\n");
3951  }
3952 
3953  LLVM_DEBUG(dbgs() << "Current DFS numbers are (" << MemberDFSIn << ","
3954  << MemberDFSOut << ")\n");
3955  // First, we see if we are out of scope or empty. If so,
3956  // and there equivalences, we try to replace the top of
3957  // stack with equivalences (if it's on the stack, it must
3958  // not have been eliminated yet).
3959  // Then we synchronize to our current scope, by
3960  // popping until we are back within a DFS scope that
3961  // dominates the current member.
3962  // Then, what happens depends on a few factors
3963  // If the stack is now empty, we need to push
3964  // If we have a constant or a local equivalence we want to
3965  // start using, we also push.
3966  // Otherwise, we walk along, processing members who are
3967  // dominated by this scope, and eliminate them.
3968  bool ShouldPush = Def && EliminationStack.empty();
3969  bool OutOfScope =
3970  !EliminationStack.isInScope(MemberDFSIn, MemberDFSOut);
3971 
3972  if (OutOfScope || ShouldPush) {
3973  // Sync to our current scope.
3974  EliminationStack.popUntilDFSScope(MemberDFSIn, MemberDFSOut);
3975  bool ShouldPush = Def && EliminationStack.empty();
3976  if (ShouldPush) {
3977  EliminationStack.push_back(Def, MemberDFSIn, MemberDFSOut);
3978  }
3979  }
3980 
3981  // Skip the Def's, we only want to eliminate on their uses. But mark
3982  // dominated defs as dead.
3983  if (Def) {
3984  // For anything in this case, what and how we value number
3985  // guarantees that any side-effets that would have occurred (ie
3986  // throwing, etc) can be proven to either still occur (because it's
3987  // dominated by something that has the same side-effects), or never
3988  // occur. Otherwise, we would not have been able to prove it value
3989  // equivalent to something else. For these things, we can just mark
3990  // it all dead. Note that this is different from the "ProbablyDead"
3991  // set, which may not be dominated by anything, and thus, are only
3992  // easy to prove dead if they are also side-effect free. Note that
3993  // because stores are put in terms of the stored value, we skip
3994  // stored values here. If the stored value is really dead, it will
3995  // still be marked for deletion when we process it in its own class.
3996  if (!EliminationStack.empty() && Def != EliminationStack.back() &&
3997  isa<Instruction>(Def) && !FromStore)
3998  markInstructionForDeletion(cast<Instruction>(Def));
3999  continue;
4000  }
4001  // At this point, we know it is a Use we are trying to possibly
4002  // replace.
4003 
4004  assert(isa<Instruction>(U->get()) &&
4005  "Current def should have been an instruction");
4006  assert(isa<Instruction>(U->getUser()) &&
4007  "Current user should have been an instruction");
4008 
4009  // If the thing we are replacing into is already marked to be dead,
4010  // this use is dead. Note that this is true regardless of whether
4011  // we have anything dominating the use or not. We do this here
4012  // because we are already walking all the uses anyway.
4013  Instruction *InstUse = cast<Instruction>(U->getUser());
4014  if (InstructionsToErase.count(InstUse)) {
4015  auto &UseCount = UseCounts[U->get()];
4016  if (--UseCount == 0) {
4017  ProbablyDead.insert(cast<Instruction>(U->get()));
4018  }
4019  }
4020 
4021  // If we get to this point, and the stack is empty we must have a use
4022  // with nothing we can use to eliminate this use, so just skip it.
4023  if (EliminationStack.empty())
4024  continue;
4025 
4026  Value *DominatingLeader = EliminationStack.back();
4027 
4028  auto *II = dyn_cast<IntrinsicInst>(DominatingLeader);
4029  bool isSSACopy = II && II->getIntrinsicID() == Intrinsic::ssa_copy;
4030  if (isSSACopy)
4031  DominatingLeader = II->getOperand(0);
4032 
4033  // Don't replace our existing users with ourselves.
4034  if (U->get() == DominatingLeader)
4035  continue;
4036  LLVM_DEBUG(dbgs()
4037  << "Found replacement " << *DominatingLeader << " for "
4038  << *U->get() << " in " << *(U->getUser()) << "\n");
4039 
4040  // If we replaced something in an instruction, handle the patching of
4041  // metadata. Skip this if we are replacing predicateinfo with its
4042  // original operand, as we already know we can just drop it.
4043  auto *ReplacedInst = cast<Instruction>(U->get());
4044  auto *PI = PredInfo->getPredicateInfoFor(ReplacedInst);
4045  if (!PI || DominatingLeader != PI->OriginalOp)
4046  patchReplacementInstruction(ReplacedInst, DominatingLeader);
4047  U->set(DominatingLeader);
4048  // This is now a use of the dominating leader, which means if the
4049  // dominating leader was dead, it's now live!
4050  auto &LeaderUseCount = UseCounts[DominatingLeader];
4051  // It's about to be alive again.
4052  if (LeaderUseCount == 0 && isa<Instruction>(DominatingLeader))
4053  ProbablyDead.erase(cast<Instruction>(DominatingLeader));
4054  // For copy instructions, we use their operand as a leader,
4055  // which means we remove a user of the copy and it may become dead.
4056  if (isSSACopy) {
4057  unsigned &IIUseCount = UseCounts[II];
4058  if (--IIUseCount == 0)
4059  ProbablyDead.insert(II);
4060  }
4061  ++LeaderUseCount;
4062  AnythingReplaced = true;
4063  }
4064  }
4065  }
4066 
4067  // At this point, anything still in the ProbablyDead set is actually dead if
4068  // would be trivially dead.
4069  for (auto *I : ProbablyDead)
4071  markInstructionForDeletion(I);
4072 
4073  // Cleanup the congruence class.
4074  CongruenceClass::MemberSet MembersLeft;
4075  for (auto *Member : *CC)
4076  if (!isa<Instruction>(Member) ||
4077  !InstructionsToErase.count(cast<Instruction>(Member)))
4078  MembersLeft.insert(Member);
4079  CC->swap(MembersLeft);
4080 
4081  // If we have possible dead stores to look at, try to eliminate them.
4082  if (CC->getStoreCount() > 0) {
4083  convertClassToLoadsAndStores(*CC, PossibleDeadStores);
4084  llvm::sort(PossibleDeadStores);
4085  ValueDFSStack EliminationStack;
4086  for (auto &VD : PossibleDeadStores) {
4087  int MemberDFSIn = VD.DFSIn;
4088  int MemberDFSOut = VD.DFSOut;
4089  Instruction *Member = cast<Instruction>(VD.Def.getPointer());
4090  if (EliminationStack.empty() ||
4091  !EliminationStack.isInScope(MemberDFSIn, MemberDFSOut)) {
4092  // Sync to our current scope.
4093  EliminationStack.popUntilDFSScope(MemberDFSIn, MemberDFSOut);
4094  if (EliminationStack.empty()) {
4095  EliminationStack.push_back(Member, MemberDFSIn, MemberDFSOut);
4096  continue;
4097  }
4098  }
4099  // We already did load elimination, so nothing to do here.
4100  if (isa<LoadInst>(Member))
4101  continue;
4102  assert(!EliminationStack.empty());
4103  Instruction *Leader = cast<Instruction>(EliminationStack.back());
4104  (void)Leader;
4105  assert(DT->dominates(Leader->getParent(), Member->getParent()));
4106  // Member is dominater by Leader, and thus dead
4107  LLVM_DEBUG(dbgs() << "Marking dead store " << *Member
4108  << " that is dominated by " << *Leader << "\n");
4109  markInstructionForDeletion(Member);
4110  CC->erase(Member);
4111  ++NumGVNDeadStores;
4112  }
4113  }
4114  }
4115  return AnythingReplaced;
4116 }
4117 
4118 // This function provides global ranking of operations so that we can place them
4119 // in a canonical order. Note that rank alone is not necessarily enough for a
4120 // complete ordering, as constants all have the same rank. However, generally,
4121 // we will simplify an operation with all constants so that it doesn't matter
4122 // what order they appear in.
4123 unsigned int NewGVN::getRank(const Value *V) const {
4124  // Prefer constants to undef to anything else
4125  // Undef is a constant, have to check it first.
4126  // Prefer smaller constants to constantexprs
4127  if (isa<ConstantExpr>(V))
4128  return 2;
4129  if (isa<UndefValue>(V))
4130  return 1;
4131  if (isa<Constant>(V))
4132  return 0;
4133  else if (auto *A = dyn_cast<Argument>(V))
4134  return 3 + A->getArgNo();
4135 
4136  // Need to shift the instruction DFS by number of arguments + 3 to account for
4137  // the constant and argument ranking above.
4138  unsigned Result = InstrToDFSNum(V);
4139  if (Result > 0)
4140  return 4 + NumFuncArgs + Result;
4141  // Unreachable or something else, just return a really large number.
4142  return ~0;
4143 }
4144 
4145 // This is a function that says whether two commutative operations should
4146 // have their order swapped when canonicalizing.
4147 bool NewGVN::shouldSwapOperands(const Value *A, const Value *B) const {
4148  // Because we only care about a total ordering, and don't rewrite expressions
4149  // in this order, we order by rank, which will give a strict weak ordering to
4150  // everything but constants, and then we order by pointer address.
4151  return std::make_pair(getRank(A), A) > std::make_pair(getRank(B), B);
4152 }
4153 
4154 namespace {
4155 
4156 class NewGVNLegacyPass : public FunctionPass {
4157 public:
4158  // Pass identification, replacement for typeid.
4159  static char ID;
4160 
4161  NewGVNLegacyPass() : FunctionPass(ID) {
4163  }
4164 
4165  bool runOnFunction(Function &F) override;
4166 
4167 private:
4168  void getAnalysisUsage(AnalysisUsage &AU) const override {
4176  }
4177 };
4178 
4179 } // end anonymous namespace
4180 
4182  if (skipFunction(F))
4183  return false;
4184  return NewGVN(F, &getAnalysis<DominatorTreeWrapperPass>().getDomTree(),
4185  &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F),
4186  &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F),
4187  &getAnalysis<AAResultsWrapperPass>().getAAResults(),
4188  &getAnalysis<MemorySSAWrapperPass>().getMSSA(),
4189  F.getParent()->getDataLayout())
4190  .runGVN();
4191 }
4192 
4193 char NewGVNLegacyPass::ID = 0;
4194 
4195 INITIALIZE_PASS_BEGIN(NewGVNLegacyPass, "newgvn", "Global Value Numbering",
4196  false, false)
4203 INITIALIZE_PASS_END(NewGVNLegacyPass, "newgvn", "Global Value Numbering", false,
4204  false)
4205 
4206 // createGVNPass - The public interface to this file.
4207 FunctionPass *llvm::createNewGVNPass() { return new NewGVNLegacyPass(); }
4208 
4210  // Apparently the order in which we get these results matter for
4211  // the old GVN (see Chandler's comment in GVN.cpp). I'll keep
4212  // the same order here, just in case.
4213  auto &AC = AM.getResult<AssumptionAnalysis>(F);
4214  auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
4215  auto &TLI = AM.getResult<TargetLibraryAnalysis>(F);
4216  auto &AA = AM.getResult<AAManager>(F);
4217  auto &MSSA = AM.getResult<MemorySSAAnalysis>(F).getMSSA();
4218  bool Changed =
4219  NewGVN(F, &DT, &AC, &TLI, &AA, &MSSA, F.getParent()->getDataLayout())
4220  .runGVN();
4221  if (!Changed)
4222  return PreservedAnalyses::all();
4223  PreservedAnalyses PA;
4225  return PA;
4226 }
i
i
Definition: README.txt:29
llvm::PreservedAnalyses
A set of analyses that are preserved following a run of a transformation pass.
Definition: PassManager.h:155
llvm::VNCoercion::analyzeLoadFromClobberingMemInst
int analyzeLoadFromClobberingMemInst(Type *LoadTy, Value *LoadPtr, MemIntrinsic *DepMI, const DataLayout &DL)
This function determines whether a value for the pointer LoadPtr can be extracted from the memory int...
Definition: VNCoercion.cpp:367
set
We currently generate a but we really shouldn eax ecx xorl edx divl ecx eax divl ecx movl eax ret A similar code sequence works for division We currently compile i32 v2 eax eax jo LBB1_2 atomic and others It is also currently not done for read modify write instructions It is also current not done if the OF or CF flags are needed The shift operators have the complication that when the shift count is EFLAGS is not set
Definition: README.txt:1277
AssumptionCache.h
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static void patchAndReplaceAllUsesWith(Instruction *I, Value *Repl)
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llvm::AAManager
A manager for alias analyses.
Definition: AliasAnalysis.h:1233
llvm::ValueDFS::LocalNum
unsigned int LocalNum
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llvm::CmpInst::getSwappedPredicate
Predicate getSwappedPredicate() const
For example, EQ->EQ, SLE->SGE, ULT->UGT, OEQ->OEQ, ULE->UGE, OLT->OGT, etc.
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Definition: AllocatorList.h:23
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Get end iterator over path.
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@ Def
Definition: TGLexer.h:50
llvm::isCallocLikeFn
bool isCallocLikeFn(const Value *V, const TargetLibraryInfo *TLI, bool LookThroughBitCast=false)
Tests if a value is a call or invoke to a library function that allocates zero-filled memory (such as...
Definition: MemoryBuiltins.cpp:291
NewGVN::ValueDFS
Definition: NewGVN.cpp:3481
M
We currently emits eax Perhaps this is what we really should generate is Is imull three or four cycles eax eax The current instruction priority is based on pattern complexity The former is more complex because it folds a load so the latter will not be emitted Perhaps we should use AddedComplexity to give LEA32r a higher priority We should always try to match LEA first since the LEA matching code does some estimate to determine whether the match is profitable if we care more about code then imull is better It s two bytes shorter than movl leal On a Pentium M
Definition: README.txt:252
llvm::CmpInst::ICMP_EQ
@ ICMP_EQ
equal
Definition: InstrTypes.h:741
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iterator_range< T > make_range(T x, T y)
Convenience function for iterating over sub-ranges.
Definition: iterator_range.h:53
llvm::set_is_subset
bool set_is_subset(const S1Ty &S1, const S2Ty &S2)
set_is_subset(A, B) - Return true iff A in B
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bool erase(PtrType Ptr)
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op_range incoming_values()
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A parsed version of the target data layout string in and methods for querying it.
Definition: DataLayout.h:112
llvm::BumpPtrAllocatorImpl::Reset
void Reset()
Deallocate all but the current slab and reset the current pointer to the beginning of it,...
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PredicateInfo.h
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Predicate
This enumeration lists the possible predicates for CmpInst subclasses.
Definition: InstrTypes.h:720
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op_range operands()
Definition: User.h:242
IntrinsicInst.h
llvm::SimplifyQuery
Definition: InstructionSimplify.h:94
llvm::AnalysisManager::getResult
PassT::Result & getResult(IRUnitT &IR, ExtraArgTs... ExtraArgs)
Get the result of an analysis pass for a given IR unit.
Definition: PassManager.h:769
llvm::pdb::PDB_DataKind::Member
@ Member
Scalar.h
SetOperations.h
llvm::Function
Definition: Function.h:61
llvm::optimized_def_chain
iterator_range< def_chain_iterator< T, true > > optimized_def_chain(T MA)
Definition: MemorySSA.h:1338
llvm::DenseMapBase::lookup
ValueT lookup(const_arg_type_t< KeyT > Val) const
lookup - Return the entry for the specified key, or a default constructed value if no such entry exis...
Definition: DenseMap.h:197
P
This currently compiles esp xmm0 movsd esp eax eax esp ret We should use not the dag combiner This is because dagcombine2 needs to be able to see through the X86ISD::Wrapper which DAGCombine can t really do The code for turning x load into a single vector load is target independent and should be moved to the dag combiner The code for turning x load into a vector load can only handle a direct load from a global or a direct load from the stack It should be generalized to handle any load from P
Definition: README-SSE.txt:411
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Definition: BitVector.h:343
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void clear()
clear - Removes all bits from the bitvector.
Definition: BitVector.h:327
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Definition: SmallVector.h:1168
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Definition: Dominators.h:151
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Definition: CommandLine.h:143
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Definition: Type.h:45
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MemoryBuiltins.h
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void resize(unsigned N, bool t=false)
resize - Grow or shrink the bitvector.
Definition: BitVector.h:333
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Definition: STLExtras.h:329
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Get end iterator over path.
Definition: Path.cpp:233
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MemoryAccess * getLiveOnEntryDef() const
Definition: MemorySSA.h:749
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Definition: Path.cpp:224
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Definition: Dominators.h:83
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Definition: STLExtras.h:1598
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Definition: GenericDomTree.h:351
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llvm::DenseMapBase::count
size_type count(const_arg_type_t< KeyT > Val) const
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Definition: DenseMap.h:145
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Given operands for a CmpInst, fold the result or return null.
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Definition: MemorySSA.h:487
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Definition: DenseSet.h:206
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Definition: Debug.h:122
DepthFirstIterator.h
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Definition: DebugCounter.h:102
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@ R
Definition: RISCVBaseInfo.h:180
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Definition: BasicBlock.h:58
AliasAnalysis.h
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It looks like we only need to define PPCfmarto for these because according to these instructions perform RTO on fma s result
Definition: README_P9.txt:256
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Definition: Debug.cpp:163
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Definition: GVNExpression.h:625
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unsigned getDFSNumIn() const
getDFSNumIn/getDFSNumOut - These return the DFS visitation order for nodes in the dominator tree.
Definition: GenericDomTree.h:143
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Given operands for a CastInst, fold the result or return null.
Definition: InstructionSimplify.cpp:4643
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bool dominates(const BasicBlock *BB, const Use &U) const
Return true if the (end of the) basic block BB dominates the use U.
Definition: Dominators.cpp:115
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unsigned getDFSNumOut() const
Definition: GenericDomTree.h:144
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Definition: AMDGPULibCalls.cpp:206
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Definition: DenseSet.h:174
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Definition: PredicateInfo.cpp:107
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CommandLine.h
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Definition: GVNExpression.h:480
llvm::GVNExpression::ConstantExpression
Definition: GVNExpression.h:588
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Definition: Constants.h:79
llvm::Instruction::getNumSuccessors
unsigned getNumSuccessors() const
Return the number of successors that this instruction has.
Definition: Instruction.cpp:765
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Definition: APInt.h:34
llvm::all_of
bool all_of(R &&range, UnaryPredicate P)
Provide wrappers to std::all_of which take ranges instead of having to pass begin/end explicitly.
Definition: STLExtras.h:1547
llvm::orc::tpctypes::LookupResult
std::vector< JITTargetAddress > LookupResult
Definition: TargetProcessControlTypes.h:62
llvm::MemorySSAWrapperPass
Legacy analysis pass which computes MemorySSA.
Definition: MemorySSA.h:965
llvm::SPII::Load
@ Load
Definition: SparcInstrInfo.h:32
llvm::DominatorTreeBase::getRootNode
DomTreeNodeBase< NodeT > * getRootNode()
getRootNode - This returns the entry node for the CFG of the function.
Definition: GenericDomTree.h:370
llvm::PassRegistry::getPassRegistry
static PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
Definition: PassRegistry.cpp:31
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static bool isEqual(const Expression *LHS, const Expression *RHS)
Definition: NewGVN.cpp:472
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bool operator<(const ValueDFS &Other) const
Definition: NewGVN.cpp:3492
llvm::MutableArrayRef
MutableArrayRef - Represent a mutable reference to an array (0 or more elements consecutively in memo...
Definition: ArrayRef.h:307
llvm::AAResults::onlyReadsMemory
bool onlyReadsMemory(const CallBase *Call)
Checks if the specified call is known to only read from non-volatile memory (or not access memory at ...
Definition: AliasAnalysis.h:605
llvm::PredicateConstraint::OtherOp
Value * OtherOp
Definition: PredicateInfo.h:77
llvm::GVNExpression::PHIExpression
Definition: GVNExpression.h:505
Constants.h
llvm::PatternMatch::match
bool match(Val *V, const Pattern &P)
Definition: PatternMatch.h:49
llvm::ExactEqualsExpression::ExactEqualsExpression
ExactEqualsExpression(const Expression &E)
Definition: NewGVN.cpp:436
isZero
static bool isZero(Value *V, const DataLayout &DL, DominatorTree *DT, AssumptionCache *AC)
Definition: Lint.cpp:519
llvm::AAResults
Definition: AliasAnalysis.h:456
llvm::MemorySSA::isLiveOnEntryDef
bool isLiveOnEntryDef(const MemoryAccess *MA) const
Return true if MA represents the live on entry value.
Definition: MemorySSA.h:745
P2
This might compile to this xmm1 xorps xmm0 movss xmm0 ret Now consider if the code caused xmm1 to get spilled This might produce this xmm1 movaps xmm0 movaps xmm1 movss xmm0 ret since the reload is only used by these we could fold it into the producing something like xmm1 movaps xmm0 ret saving two instructions The basic idea is that a reload from a spill if only one byte chunk is bring in zeros the one element instead of elements This can be used to simplify a variety of shuffle where the elements are fixed zeros This code generates ugly probably due to costs being off or< 4 x float > * P2
Definition: README-SSE.txt:278
E
static GCRegistry::Add< CoreCLRGC > E("coreclr", "CoreCLR-compatible GC")
llvm::User
Definition: User.h:44
Intrinsics.h
llvm::initializeNewGVNLegacyPassPass
void initializeNewGVNLegacyPassPass(PassRegistry &)
C
(vector float) vec_cmpeq(*A, *B) C
Definition: README_ALTIVEC.txt:86
llvm::ARM_PROC::A
@ A
Definition: ARMBaseInfo.h:34
InstrTypes.h
EnableStoreRefinement
static cl::opt< bool > EnableStoreRefinement("enable-store-refinement", cl::init(false), cl::Hidden)
llvm::JumpTable::Simplified
@ Simplified
Definition: TargetOptions.h:47
llvm::createNewGVNPass
FunctionPass * createNewGVNPass()
Definition: NewGVN.cpp:4207
llvm::AnalysisUsage
Represent the analysis usage information of a pass.
Definition: PassAnalysisSupport.h:47
llvm::ms_demangle::QualifierMangleMode::Result
@ Result
NewGVN::ValueDFS::Def
PointerIntPair< Value *, 1, bool > Def
Definition: NewGVN.cpp:3489
llvm::AMDGPU::PALMD::Key
Key
PAL metadata keys.
Definition: AMDGPUMetadata.h:481
TargetLibraryInfo.h
llvm::GVNExpression::LoadExpression::equals
bool equals(const Expression &Other) const override
Definition: NewGVN.cpp:911
AssumeBundleBuilder.h
DenseSet.h
false
Definition: StackSlotColoring.cpp:142
B
static GCRegistry::Add< OcamlGC > B("ocaml", "ocaml 3.10-compatible GC")
First
into llvm powi allowing the code generator to produce balanced multiplication trees First
Definition: README.txt:54
llvm::Value::getValueID
unsigned getValueID() const
Return an ID for the concrete type of this object.
Definition: Value.h:529
llvm::VNCoercion
Definition: VNCoercion.h:34
llvm::GVNExpression::Expression
Definition: GVNExpression.h:60
llvm::Instruction
Definition: Instruction.h:45
llvm::DebugCounter::shouldExecute
static bool shouldExecute(unsigned CounterName)
Definition: DebugCounter.h:74
llvm::DominatorTreeWrapperPass
Legacy analysis pass which computes a DominatorTree.
Definition: Dominators.h:281
GVNExpression.h
llvm::STATISTIC
STATISTIC(NumFunctions, "Total number of functions")
isCopyOfPHI
static bool isCopyOfPHI(const Value *V, const PHINode *PN)
Definition: NewGVN.cpp:984
PointerLikeTypeTraits.h
EnablePhiOfOps
static cl::opt< bool > EnablePhiOfOps("enable-phi-of-ops", cl::init(true), cl::Hidden)
Currently, the generation "phi of ops" can result in correctness issues.
llvm::AArch64CC::LE
@ LE
Definition: AArch64BaseInfo.h:268
llvm::UndefValue::get
static UndefValue * get(Type *T)
Static factory methods - Return an 'undef' object of the specified type.
Definition: Constants.cpp:1784
BitVector.h
llvm::GVNExpression::BasicExpression::~BasicExpression
~BasicExpression() override
llvm::CmpInst::FCMP_OEQ
@ FCMP_OEQ
0 0 0 1 True if ordered and equal
Definition: InstrTypes.h:723
SmallPtrSet.h
llvm::Instruction::getSuccessor
BasicBlock * getSuccessor(unsigned Idx) const
Return the specified successor. This instruction must be a terminator.
Definition: Instruction.cpp:777
llvm::BitVector
Definition: BitVector.h:74
llvm::DominatorTreeBase::updateDFSNumbers
void updateDFSNumbers() const
updateDFSNumbers - Assign In and Out numbers to the nodes while walking dominator tree in dfs order.
Definition: GenericDomTree.h:732
PatternMatch.h
llvm::ExactEqualsExpression::getComputedHash
hash_code getComputedHash() const
Definition: NewGVN.cpp:438
llvm::SimplifyGEPInst
Value * SimplifyGEPInst(Type *SrcTy, ArrayRef< Value * > Ops, const SimplifyQuery &Q)
Given operands for a GetElementPtrInst, fold the result or return null.
Definition: InstructionSimplify.cpp:4422
llvm::MCID::Call
@ Call
Definition: MCInstrDesc.h:153
place
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 ID Predecessors according to mbb< bb27, 0x8b0a7c0 > Note ADDri is not a two address instruction its result reg1037 is an operand of the PHI node in bb76 and its operand reg1039 is the result of the PHI node We should treat it as a two address code and make sure the ADDri is scheduled after any node that reads reg1039 Use info(i.e. register scavenger) to assign it a free register to allow reuse the collector could move the objects and invalidate the derived pointer This is bad enough in the first place
Definition: README.txt:50
llvm::PHINode::getNumIncomingValues
unsigned getNumIncomingValues() const
Return the number of incoming edges.
Definition: Instructions.h:2689
llvm::GVNExpression::PHIExpression::~PHIExpression
~PHIExpression() override
llvm::MemoryAccess::getBlock
BasicBlock * getBlock() const
Definition: MemorySSA.h:162
llvm::Value::use_empty
bool use_empty() const
Definition: Value.h:345
Type.h
X
static GCMetadataPrinterRegistry::Add< ErlangGCPrinter > X("erlang", "erlang-compatible garbage collector")
INITIALIZE_PASS_BEGIN
INITIALIZE_PASS_BEGIN(NewGVNLegacyPass, "newgvn", "Global Value Numbering", false, false) INITIALIZE_PASS_END(NewGVNLegacyPass
llvm::PredicateInfo
Encapsulates PredicateInfo, including all data associated with memory accesses.
Definition: PredicateInfo.h:178
INITIALIZE_PASS_END
#define INITIALIZE_PASS_END(passName, arg, name, cfg, analysis)
Definition: PassSupport.h:58
llvm::DenseMapInfo< const Expression * >::isEqual
static bool isEqual(const ExactEqualsExpression &LHS, const Expression *RHS)
Definition: NewGVN.cpp:466
llvm::Instruction::isCommutative
bool isCommutative() const LLVM_READONLY
Return true if the instruction is commutative:
Definition: Instruction.cpp:758
llvm::PredicateConstraint::Predicate
CmpInst::Predicate Predicate
Definition: PredicateInfo.h:76
llvm::DOTGraphTraits
DOTGraphTraits - Template class that can be specialized to customize how graphs are converted to 'dot...
Definition: DOTGraphTraits.h:161
llvm::ExactEqualsExpression::operator==
bool operator==(const Expression &Other) const
Definition: NewGVN.cpp:440
llvm::DenseSet
Implements a dense probed hash-table based set.
Definition: DenseSet.h:268
llvm::MemorySSAWalker::getClobberingMemoryAccess
MemoryAccess * getClobberingMemoryAccess(const Instruction *I)
Given a memory Mod/Ref/ModRef'ing instruction, calling this will give you the nearest dominating Memo...
Definition: MemorySSA.h:1025
llvm::wouldInstructionBeTriviallyDead
bool wouldInstructionBeTriviallyDead(Instruction *I, const TargetLibraryInfo *TLI=nullptr)
Return true if the result produced by the instruction would have no side effects if it was not used.
Definition: Local.cpp:405
llvm::PredicateBase
Definition: PredicateInfo.h:82
DEBUG_COUNTER
DEBUG_COUNTER(VNCounter, "newgvn-vn", "Controls which instructions are value numbered")
BasicBlock.h
llvm::cl::opt< bool >
llvm::ValueDFS
Definition: PredicateInfo.cpp:101
llvm::RISCVFenceField::O
@ O
Definition: RISCVBaseInfo.h:179
llvm::StoreInst
An instruction for storing to memory.
Definition: Instructions.h:304
llvm::DebugCounter::setCounterValue
static void setCounterValue(unsigned ID, int64_t Count)
Definition: DebugCounter.h:115
llvm::Constant
This is an important base class in LLVM.
Definition: Constant.h:41
llvm::isMallocLikeFn
bool isMallocLikeFn(const Value *V, const TargetLibraryInfo *TLI, bool LookThroughBitCast=false)
Tests if a value is a call or invoke to a library function that allocates uninitialized memory (such ...
Definition: MemoryBuiltins.cpp:264
llvm::Instruction::eraseFromParent
SymbolTableList< Instruction >::iterator eraseFromParent()
This method unlinks 'this' from the containing basic block and deletes it.
Definition: Instruction.cpp:78
CFGPrinter.h
llvm::DenseMapBase< DenseMap< KeyT, ValueT, DenseMapInfo< KeyT >, llvm::detail::DenseMapPair< KeyT, ValueT > >, KeyT, ValueT, DenseMapInfo< KeyT >, llvm::detail::DenseMapPair< KeyT, ValueT > >::clear
void clear()
Definition: DenseMap.h:111
llvm::GVNExpression
Definition: GVNExpression.h:40
llvm::TargetLibraryInfoWrapperPass
Definition: TargetLibraryInfo.h:463
llvm::GVNExpression::AggregateValueExpression::~AggregateValueExpression
~AggregateValueExpression() override
D
static GCRegistry::Add< StatepointGC > D("statepoint-example", "an example strategy for statepoint")
llvm::BitVector::any
bool any() const
any - Returns true if any bit is set.
Definition: BitVector.h:162
const
aarch64 promote const
Definition: AArch64PromoteConstant.cpp:232
llvm::SmallPtrSetImpl::end
iterator end() const
Definition: SmallPtrSet.h:407
llvm::AssumptionAnalysis
A function analysis which provides an AssumptionCache.
Definition: AssumptionCache.h:169
llvm::PreservedAnalyses::preserve
void preserve()
Mark an analysis as preserved.
Definition: PassManager.h:176
INITIALIZE_PASS_DEPENDENCY
INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
llvm::SimplifyBinOp
Value * SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, const SimplifyQuery &Q)
Given operands for a BinaryOperator, fold the result or return null.
Definition: InstructionSimplify.cpp:5282
llvm::BumpPtrAllocatorImpl
Allocate memory in an ever growing pool, as if by bump-pointer.
Definition: Allocator.h:67
llvm::numbers::e
constexpr double e
Definition: MathExtras.h:57
llvm::DenseMap
Definition: DenseMap.h:714
llvm::nodes
iterator_range< typename GraphTraits< GraphType >::nodes_iterator > nodes(const GraphType &G)
Definition: GraphTraits.h:108
llvm::MemorySSA
Encapsulates MemorySSA, including all data associated with memory accesses.
Definition: MemorySSA.h:708
I
#define I(x, y, z)
Definition: MD5.cpp:59
llvm::MemorySSA::getMemoryAccess
MemoryUseOrDef * getMemoryAccess(const Instruction *I) const
Given a memory Mod/Ref'ing instruction, get the MemorySSA access associated with it.
Definition: MemorySSA.h:725
VNCoercion.h
llvm::DenseMapInfo< const Expression * >::getHashValue
static unsigned getHashValue(const Expression *E)
Definition: NewGVN.cpp:458
llvm::cl::init
initializer< Ty > init(const Ty &Val)
Definition: CommandLine.h:443
newgvn
newgvn
Definition: NewGVN.cpp:4203
llvm::SmallPtrSetImpl::begin
iterator begin() const
Definition: SmallPtrSet.h:402
ArrayRef.h
llvm::detail::DenseSetImpl< ValueT, DenseMap< ValueT, detail::DenseSetEmpty, DenseMapInfo< ValueT >, detail::DenseSetPair< ValueT > >, DenseMapInfo< ValueT > >::begin
iterator begin()
Definition: DenseSet.h:173
llvm::pdb::PDB_MemoryType::Stack
@ Stack
llvm::DenseMapBase< DenseMap< KeyT, ValueT, DenseMapInfo< KeyT >, llvm::detail::DenseMapPair< KeyT, ValueT > >, KeyT, ValueT, DenseMapInfo< KeyT >, llvm::detail::DenseMapPair< KeyT, ValueT > >::find
iterator find(const_arg_type_t< KeyT > Val)
Definition: DenseMap.h:150
llvm::sys::path::const_iterator::begin
friend const_iterator begin(StringRef path, Style style)
Get begin iterator over path.
Definition: Path.cpp:224
assert
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
std::swap
void swap(llvm::BitVector &LHS, llvm::BitVector &RHS)
Implement std::swap in terms of BitVector swap.
Definition: BitVector.h:840
SI
StandardInstrumentations SI(Debug, VerifyEach)
llvm::GVNExpression::StoreExpression
Definition: GVNExpression.h:370
llvm::isAlignedAllocLikeFn
bool isAlignedAllocLikeFn(const Value *V, const TargetLibraryInfo *TLI, bool LookThroughBitCast=false)
Tests if a value is a call or invoke to a library function that allocates uninitialized memory with a...
Definition: MemoryBuiltins.cpp:277
llvm::GVNExpression::VariableExpression
Definition: GVNExpression.h:552
iterator_range.h
okayForPHIOfOps
static bool okayForPHIOfOps(const Instruction *I)
Definition: NewGVN.cpp:2547
llvm::is_splat
bool is_splat(R &&Range)
Wrapper function around std::equal to detect if all elements in a container are same.
Definition: STLExtras.h:1714
llvm::WinEH::EncodingType::CE
@ CE
Windows NT (Windows on ARM)
llvm::salvageKnowledge
void salvageKnowledge(Instruction *I, AssumptionCache *AC=nullptr, DominatorTree *DT=nullptr)
Calls BuildAssumeFromInst and if the resulting llvm.assume is valid insert if before I.
Definition: AssumeBundleBuilder.cpp:293
llvm::MemorySSAAnalysis
An analysis that produces MemorySSA for a function.
Definition: MemorySSA.h:926
llvm::MemorySSA::getWalker
MemorySSAWalker * getWalker()
Definition: MemorySSA.cpp:1566
llvm::SmallPtrSetImpl::count
size_type count(ConstPtrType Ptr) const
count - Return 1 if the specified pointer is in the set, 0 otherwise.
Definition: SmallPtrSet.h:382
llvm::ArrayRecycler::clear
void clear(AllocatorType &Allocator)
Release all the tracked allocations to the allocator.
Definition: ArrayRecycler.h:104
llvm::PatternMatch::m_Value
class_match< Value > m_Value()
Match an arbitrary value and ignore it.
Definition: PatternMatch.h:76
llvm::detail::DenseSetImpl< ValueT, DenseMap< ValueT, detail::DenseSetEmpty, DenseMapInfo< ValueT >, detail::DenseSetPair< ValueT > >, DenseMapInfo< ValueT > >::clear
void clear()
Definition: DenseSet.h:92
llvm::size
auto size(R &&Range, std::enable_if_t< std::is_base_of< std::random_access_iterator_tag, typename std::iterator_traits< decltype(Range.begin())>::iterator_category >::value, void > *=nullptr)
Get the size of a range.
Definition: STLExtras.h:1528
llvm::GVNExpression::StoreExpression::equals
bool equals(const Expression &Other) const override
Definition: NewGVN.cpp:915
llvm::AMDGPU::CPol::SCC
@ SCC
Definition: SIDefines.h:285
llvm::ConstantFoldInstOperands
Constant * ConstantFoldInstOperands(Instruction *I, ArrayRef< Constant * > Ops, const DataLayout &DL, const TargetLibraryInfo *TLI=nullptr)
ConstantFoldInstOperands - Attempt to constant fold an instruction with the specified operands.
Definition: ConstantFolding.cpp:1259
llvm::Expression
Class representing an expression and its matching format.
Definition: FileCheckImpl.h:237
llvm::SmallPtrSetImplBase::clear
void clear()
Definition: SmallPtrSet.h:94
llvm::AssumptionCacheTracker
An immutable pass that tracks lazily created AssumptionCache objects.
Definition: AssumptionCache.h:200
llvm::ArrayRef
ArrayRef - Represent a constant reference to an array (0 or more elements consecutively in memory),...
Definition: APInt.h:32
llvm::isInstructionTriviallyDead
bool isInstructionTriviallyDead(Instruction *I, const TargetLibraryInfo *TLI=nullptr)
Return true if the result produced by the instruction is not used, and the instruction has no side ef...
Definition: Local.cpp:398
llvm::VNCoercion::getConstantLoadValueForLoad
Constant * getConstantLoadValueForLoad(Constant *SrcVal, unsigned Offset, Type *LoadTy, const DataLayout &DL)
Definition: VNCoercion.cpp:535
llvm::min
Expected< ExpressionValue > min(const ExpressionValue &Lhs, const ExpressionValue &Rhs)
Definition: FileCheck.cpp:357
llvm::any_of
bool any_of(R &&range, UnaryPredicate P)
Provide wrappers to std::any_of which take ranges instead of having to pass begin/end explicitly.
Definition: STLExtras.h:1554
Cond
SmallVector< MachineOperand, 4 > Cond
Definition: BasicBlockSections.cpp:179
llvm::LoadInst::isSimple
bool isSimple() const
Definition: Instructions.h:259
llvm::AssumptionCache
A cache of @llvm.assume calls within a function.
Definition: AssumptionCache.h:41
llvm_unreachable
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
Definition: ErrorHandling.h:136
llvm::Value::getType
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:256
llvm::MemorySSA::getBlockDefs
const DefsList * getBlockDefs(const BasicBlock *BB) const
Return the list of MemoryDef's and MemoryPhi's for a given basic block.
Definition: MemorySSA.h:773
llvm::SPII::Store
@ Store
Definition: SparcInstrInfo.h:33
if
if(llvm_vc STREQUAL "") set(fake_version_inc "$
Definition: CMakeLists.txt:14
llvm::ConstantInt::isZero
bool isZero() const
This is just a convenience method to make client code smaller for a common code.
Definition: Constants.h:194
llvm::AnalysisUsage::addPreserved
AnalysisUsage & addPreserved()
Add the specified Pass class to the set of analyses preserved by this pass.
Definition: PassAnalysisSupport.h:98
llvm::Value::replaceAllUsesWith
void replaceAllUsesWith(Value *V)
Change all uses of this to point to a new Value.
Definition: Value.cpp:520
A
* A
Definition: README_ALTIVEC.txt:89
DL
MachineBasicBlock MachineBasicBlock::iterator DebugLoc DL
Definition: AArch64SLSHardening.cpp:76
llvm::ExactEqualsExpression
Definition: NewGVN.cpp:433
S
add sub stmia L5 ldr r0 bl L_printf $stub Instead of a and a wouldn t it be better to do three moves *Return an aggregate type is even return S
Definition: README.txt:210
NewGVN.h
llvm::GVNExpression::CallExpression
Definition: GVNExpression.h:301
llvm::DominatorTreeBase::properlyDominates
bool properlyDominates(const DomTreeNodeBase< NodeT > *A, const DomTreeNodeBase< NodeT > *B) const
properlyDominates - Returns true iff A dominates B and A != B.
Definition: GenericDomTree.h:392
llvm::MemoryAccess
Definition: MemorySSA.h:140
llvm::DomTreeNodeBase< BasicBlock >
llvm::LoadInst
An instruction for reading from memory.
Definition: Instructions.h:175
llvm::DenseMapBase< DenseMap< KeyT, ValueT, DenseMapInfo< KeyT >, llvm::detail::DenseMapPair< KeyT, ValueT > >, KeyT, ValueT, DenseMapInfo< KeyT >, llvm::detail::DenseMapPair< KeyT, ValueT > >::insert
std::pair< iterator, bool > insert(const std::pair< KeyT, ValueT > &KV)
Definition: DenseMap.h:207
llvm::make_filter_range
iterator_range< filter_iterator< detail::IterOfRange< RangeT >, PredicateT > > make_filter_range(RangeT &&Range, PredicateT Pred)
Convenience function that takes a range of elements and a predicate, and return a new filter_iterator...
Definition: STLExtras.h:486
llvm::DenseMapInfo< const Expression * >::getHashValue
static unsigned getHashValue(const ExactEqualsExpression &E)
Definition: NewGVN.cpp:462
llvm::ValueDFS::Def
Value * Def
Definition: PredicateInfo.cpp:106
llvm::ConstantInt::getFalse
static ConstantInt * getFalse(LLVMContext &Context)
Definition: Constants.cpp:854
Argument.h
llvm::ArrayRecycler
Recycle small arrays allocated from a BumpPtrAllocator.
Definition: ArrayRecycler.h:28
llvm::depth_first
iterator_range< df_iterator< T > > depth_first(const T &G)
Definition: DepthFirstIterator.h:229
llvm::MCID::Select
@ Select
Definition: MCInstrDesc.h:162
runOnFunction
static bool runOnFunction(Function &F, bool PostInlining)
Definition: EntryExitInstrumenter.cpp:69
llvm::GVNExpression::Expression::~Expression
virtual ~Expression()
llvm::VNCoercion::getConstantMemInstValueForLoad
Constant * getConstantMemInstValueForLoad(MemIntrinsic *SrcInst, unsigned Offset, Type *LoadTy, const DataLayout &DL)
Definition: VNCoercion.cpp:612
llvm::CmpInst::isImpliedFalseByMatchingCmp
static bool isImpliedFalseByMatchingCmp(Predicate Pred1, Predicate Pred2)
Determine if Pred1 implies Pred2 is false when two compares have matching operands.
Definition: Instructions.cpp:4019
llvm::Instruction::isAtomic
bool isAtomic() const
Return true if this instruction has an AtomicOrdering of unordered or higher.
Definition: Instruction.cpp:604
Constant.h
llvm::CmpInst::isImpliedTrueByMatchingCmp
static bool isImpliedTrueByMatchingCmp(Predicate Pred1, Predicate Pred2)
Determine if Pred1 implies Pred2 is true when two compares have matching operands.
Definition: Instructions.cpp:3994
llvm::empty
constexpr bool empty(const T &RangeOrContainer)
Test whether RangeOrContainer is empty. Similar to C++17 std::empty.
Definition: STLExtras.h:254
llvm::ConstantInt::getTrue
static ConstantInt * getTrue(LLVMContext &Context)
Definition: Constants.cpp:847
std
Definition: BitVector.h:838
llvm::Constant::getNullValue
static Constant * getNullValue(Type *Ty)
Constructor to create a '0' constant of arbitrary type.
Definition: Constants.cpp:346
llvm::DenseMapBase< DenseMap< KeyT, ValueT, DenseMapInfo< KeyT >, llvm::detail::DenseMapPair< KeyT, ValueT > >, KeyT, ValueT, DenseMapInfo< KeyT >, llvm::detail::DenseMapPair< KeyT, ValueT > >::end
iterator end()
Definition: DenseMap.h:83
llvm::AMDGPU::SendMsg::Op
Op
Definition: SIDefines.h:314
llvm::PreservedAnalyses::all
static PreservedAnalyses all()
Construct a special preserved set that preserves all passes.
Definition: PassManager.h:161
llvm::PHINode::Create
static PHINode * Create(Type *Ty, unsigned NumReservedValues, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
Constructors - NumReservedValues is a hint for the number of incoming edges that this phi node will h...
Definition: Instructions.h:2639
llvm::ArrayRef::begin
iterator begin() const
Definition: ArrayRef.h:153
llvm::VNCoercion::analyzeLoadFromClobberingStore
int analyzeLoadFromClobberingStore(Type *LoadTy, Value *LoadPtr, StoreInst *DepSI, const DataLayout &DL)
This function determines whether a value for the pointer LoadPtr can be extracted from the store at D...
Definition: VNCoercion.cpp:226
Casting.h
Function.h
llvm::GVNExpression::DeadExpression
Definition: GVNExpression.h:541
DebugCounter.h
llvm::DenseMapBase::size
unsigned size() const
Definition: DenseMap.h:100
llvm::sort
void sort(IteratorTy Start, IteratorTy End)
Definition: STLExtras.h:1488
llvm::TargetStackID::Value
Value
Definition: TargetFrameLowering.h:27
llvm::Type::getPointerTo
PointerType * getPointerTo(unsigned AddrSpace=0) const
Return a pointer to the current type.
Definition: Type.cpp:738
llvm::TargetLibraryInfo
Provides information about what library functions are available for the current target.
Definition: TargetLibraryInfo.h:219
Numbering
Global Value Numbering
Definition: NewGVN.cpp:4203
llvm::MemoryUseOrDef
Class that has the common methods + fields of memory uses/defs.
Definition: MemorySSA.h:250
transform
instcombine should handle this transform
Definition: README.txt:262
llvm::SmallVectorImpl::clear
void clear()
Definition: SmallVector.h:585
llvm::ExactEqualsExpression::E
const Expression & E
Definition: NewGVN.cpp:434
llvm::MCID::Add
@ Add
Definition: MCInstrDesc.h:183
llvm::GVNExpression::LoadExpression::~LoadExpression
~LoadExpression() override
llvm::ReversePostOrderTraversal
Definition: PostOrderIterator.h:290
llvm::BitVector::reset
BitVector & reset()
Definition: BitVector.h:384
llvm::VNCoercion::getConstantStoreValueForLoad
Constant * getConstantStoreValueForLoad(Constant *SrcVal, unsigned Offset, Type *LoadTy, const DataLayout &DL)
Definition: VNCoercion.cpp:476
Predicate
llvm::NewGVNPass::run
PreservedAnalyses run(Function &F, AnalysisManager< Function > &AM)
Run the pass over the function.
Definition: NewGVN.cpp:4209
llvm::DominatorTreeAnalysis
Analysis pass which computes a DominatorTree.
Definition: Dominators.h:252
llvm::DenseMapInfo< const Expression * >::getEmptyKey
static const Expression * getEmptyKey()
Definition: NewGVN.cpp:446
llvm::BasicBlock::reverse_iterator
InstListType::reverse_iterator reverse_iterator
Definition: BasicBlock.h:92
MemorySSA.h
Instructions.h
PostOrderIterator.h
llvm::GVNExpression::AggregateValueExpression
Definition: GVNExpression.h:411
llvm::User::getNumOperands
unsigned getNumOperands() const
Definition: User.h:191
llvm::PointerIntPair< Value *, 1, bool >
llvm::AAResults::doesNotAccessMemory
bool doesNotAccessMemory(const CallBase *Call)
Checks if the specified call is known to never read or write memory.
Definition: AliasAnalysis.h:577
llvm::ValueDFS::DFSOut
int DFSOut
Definition: PredicateInfo.cpp:103
SmallVector.h
lookup
static bool lookup(const GsymReader &GR, DataExtractor &Data, uint64_t &Offset, uint64_t BaseAddr, uint64_t Addr, SourceLocations &SrcLocs, llvm::Error &Err)
A Lookup helper functions.
Definition: InlineInfo.cpp:108
User.h
ArrayRecycler.h
Dominators.h
llvm::BitVector::find_first
int find_first() const
find_first - Returns the index of the first set bit, -1 if none of the bits are set.
Definition: BitVector.h:292
llvm::AAResultsWrapperPass
A wrapper pass to provide the legacy pass manager access to a suitably prepared AAResults object.
Definition: AliasAnalysis.h:1281
llvm::Instruction::getParent
const BasicBlock * getParent() const
Definition: Instruction.h:94
InstructionSimplify.h
llvm::Value::deleteValue
void deleteValue()
Delete a pointer to a generic Value.
Definition: Value.cpp:110
llvm::VNCoercion::analyzeLoadFromClobberingLoad
int analyzeLoadFromClobberingLoad(Type *LoadTy, Value *LoadPtr, LoadInst *DepLI, const DataLayout &DL)
This function determines whether a value for the pointer LoadPtr can be extracted from the load at De...
Definition: VNCoercion.cpp:332
llvm::GlobalsAAWrapperPass
Legacy wrapper pass to provide the GlobalsAAResult object.
Definition: GlobalsModRef.h:143
llvm::PHINode::getIncomingBlock
BasicBlock * getIncomingBlock(unsigned i) const
Return incoming basic block number i.
Definition: Instructions.h:2713
llvm::ArrayRef::size
size_t size() const
size - Get the array size.
Definition: ArrayRef.h:165
llvm::max
Align max(MaybeAlign Lhs, Align Rhs)
Definition: Alignment.h:340
llvm::iterator_range
A range adaptor for a pair of iterators.
Definition: iterator_range.h:30
llvm::AAResults::isMustAlias
bool isMustAlias(const MemoryLocation &LocA, const MemoryLocation &LocB)
A trivial helper function to check to see if the specified pointers are must-alias.
Definition: AliasAnalysis.h:528
llvm::PHINode
Definition: Instructions.h:2597
llvm::GVNExpression::BasicExpression
Definition: GVNExpression.h:136
llvm::PatternMatch
Definition: PatternMatch.h:47
llvm::detail::DenseSetImpl< ValueT, DenseMap< ValueT, detail::DenseSetEmpty, DenseMapInfo< ValueT >, detail::DenseSetPair< ValueT > >, DenseMapInfo< ValueT > >::erase
bool erase(const ValueT &V)
Definition: DenseSet.h:101
llvm::SmallVectorImpl< Instruction * >
DenseMapInfo.h
llvm::SmallPtrSetImpl< const Value * >
llvm::AnalysisManager
A container for analyses that lazily runs them and caches their results.
Definition: InstructionSimplify.h:44
llvm::FunctionPass
FunctionPass class - This class is used to implement most global optimizations.
Definition: Pass.h:298
llvm::CallInst
This class represents a function call, abstracting a target machine's calling convention.
Definition: Instructions.h:1475
llvm::ConstantInt::isOne
bool isOne() const
This is just a convenience method to make client code smaller for a common case.
Definition: Constants.h:200
BB
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
GEP
Hexagon Common GEP
Definition: HexagonCommonGEP.cpp:172
llvm::GVNExpression::op_inserter
Definition: GVNExpression.h:243
llvm::patchReplacementInstruction
void patchReplacementInstruction(Instruction *I, Value *Repl)
Patch the replacement so that it is not more restrictive than the value being replaced.
Definition: Local.cpp:2633
llvm::AnalysisUsage::addRequired
AnalysisUsage & addRequired()
Definition: PassAnalysisSupport.h:75
LLVMContext.h
From
BlockVerifier::State From
Definition: BlockVerifier.cpp:55
llvm::MemorySSAWalker
This is the generic walker interface for walkers of MemorySSA.
Definition: MemorySSA.h:996
llvm::User::getOperand
Value * getOperand(unsigned i) const
Definition: User.h:169
raw_ostream.h
copy
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 we currently get code like const It could be done with a smaller encoding like local tee $pop5 local copy
Definition: README.txt:101
Value.h
llvm::GVNExpression::LoadExpression
Definition: GVNExpression.h:328
InitializePasses.h
llvm::Value
LLVM Value Representation.
Definition: Value.h:75
Debug.h
llvm::TargetLibraryAnalysis
Analysis pass providing the TargetLibraryInfo.
Definition: TargetLibraryInfo.h:438
llvm::Value::users
iterator_range< user_iterator > users()
Definition: Value.h:422
llvm::BumpPtrAllocatorImpl::Deallocate
void Deallocate(const void *Ptr, size_t Size, size_t)
Definition: Allocator.h:213
Other
Optional< std::vector< StOtherPiece > > Other
Definition: ELFYAML.cpp:1172
llvm::Use
A Use represents the edge between a Value definition and its users.
Definition: Use.h:44
llvm::SmallVectorImpl::emplace_back
reference emplace_back(ArgTypes &&... Args)
Definition: SmallVector.h:908
llvm::SmallPtrSetImpl::insert
std::pair< iterator, bool > insert(PtrType Ptr)
Inserts Ptr if and only if there is no element in the container equal to Ptr.
Definition: SmallPtrSet.h:364
llvm::Intrinsic::ID
unsigned ID
Definition: TargetTransformInfo.h:38
llvm::hash_code
An opaque object representing a hash code.
Definition: Hashing.h:72