1 //===- MergeFunctions.cpp - Merge identical functions ---------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This pass looks for equivalent functions that are mergable and folds them.
12 // A hash is computed from the function, based on its type and number of
15 // Once all hashes are computed, we perform an expensive equality comparison
16 // on each function pair. This takes n^2/2 comparisons per bucket, so it's
17 // important that the hash function be high quality. The equality comparison
18 // iterates through each instruction in each basic block.
20 // When a match is found the functions are folded. If both functions are
21 // overridable, we move the functionality into a new internal function and
22 // leave two overridable thunks to it.
24 //===----------------------------------------------------------------------===//
28 // * virtual functions.
30 // Many functions have their address taken by the virtual function table for
31 // the object they belong to. However, as long as it's only used for a lookup
32 // and call, this is irrelevant, and we'd like to fold such functions.
34 // * switch from n^2 pair-wise comparisons to an n-way comparison for each
37 // * be smarter about bitcasts.
39 // In order to fold functions, we will sometimes add either bitcast instructions
40 // or bitcast constant expressions. Unfortunately, this can confound further
41 // analysis since the two functions differ where one has a bitcast and the
42 // other doesn't. We should learn to look through bitcasts.
44 //===----------------------------------------------------------------------===//
46 #define DEBUG_TYPE "mergefunc"
47 #include "llvm/Transforms/IPO.h"
48 #include "llvm/ADT/DenseSet.h"
49 #include "llvm/ADT/FoldingSet.h"
50 #include "llvm/ADT/SmallSet.h"
51 #include "llvm/ADT/Statistic.h"
52 #include "llvm/ADT/STLExtras.h"
53 #include "llvm/Constants.h"
54 #include "llvm/InlineAsm.h"
55 #include "llvm/Instructions.h"
56 #include "llvm/LLVMContext.h"
57 #include "llvm/Module.h"
58 #include "llvm/Pass.h"
59 #include "llvm/Support/CallSite.h"
60 #include "llvm/Support/Debug.h"
61 #include "llvm/Support/ErrorHandling.h"
62 #include "llvm/Support/IRBuilder.h"
63 #include "llvm/Support/ValueHandle.h"
64 #include "llvm/Support/raw_ostream.h"
65 #include "llvm/Target/TargetData.h"
69 STATISTIC(NumFunctionsMerged, "Number of functions merged");
70 STATISTIC(NumThunksWritten, "Number of thunks generated");
71 STATISTIC(NumDoubleWeak, "Number of new functions created");
73 /// ProfileFunction - Creates a hash-code for the function which is the same
74 /// for any two functions that will compare equal, without looking at the
75 /// instructions inside the function.
76 static unsigned ProfileFunction(const Function *F) {
77 const FunctionType *FTy = F->getFunctionType();
80 ID.AddInteger(F->size());
81 ID.AddInteger(F->getCallingConv());
82 ID.AddBoolean(F->hasGC());
83 ID.AddBoolean(FTy->isVarArg());
84 ID.AddInteger(FTy->getReturnType()->getTypeID());
85 for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
86 ID.AddInteger(FTy->getParamType(i)->getTypeID());
87 return ID.ComputeHash();
92 class ComparableFunction {
94 static const ComparableFunction EmptyKey;
95 static const ComparableFunction TombstoneKey;
97 ComparableFunction(Function *Func, TargetData *TD)
98 : Func(Func), Hash(ProfileFunction(Func)), TD(TD) {}
100 Function *getFunc() const { return Func; }
101 unsigned getHash() const { return Hash; }
102 TargetData *getTD() const { return TD; }
104 // Drops AssertingVH reference to the function. Outside of debug mode, this
108 "Attempted to release function twice, or release empty/tombstone!");
112 bool &getOrInsertCachedComparison(const ComparableFunction &Other,
113 bool &inserted) const {
114 typedef DenseMap<Function *, bool>::iterator iterator;
115 std::pair<iterator, bool> p =
116 CompareResultCache.insert(std::make_pair(Other.getFunc(), false));
118 return p.first->second;
122 explicit ComparableFunction(unsigned Hash)
123 : Func(NULL), Hash(Hash), TD(NULL) {}
125 // DenseMap::grow() triggers a recomparison of all keys in the map, which is
126 // wildly expensive. This cache tries to preserve known results.
127 mutable DenseMap<Function *, bool> CompareResultCache;
129 AssertingVH<Function> Func;
134 const ComparableFunction ComparableFunction::EmptyKey = ComparableFunction(0);
135 const ComparableFunction ComparableFunction::TombstoneKey =
136 ComparableFunction(1);
142 struct DenseMapInfo<ComparableFunction> {
143 static ComparableFunction getEmptyKey() {
144 return ComparableFunction::EmptyKey;
146 static ComparableFunction getTombstoneKey() {
147 return ComparableFunction::TombstoneKey;
149 static unsigned getHashValue(const ComparableFunction &CF) {
152 static bool isEqual(const ComparableFunction &LHS,
153 const ComparableFunction &RHS);
159 /// MergeFunctions finds functions which will generate identical machine code,
160 /// by considering all pointer types to be equivalent. Once identified,
161 /// MergeFunctions will fold them by replacing a call to one to a call to a
162 /// bitcast of the other.
164 class MergeFunctions : public ModulePass {
167 MergeFunctions() : ModulePass(ID) {
168 initializeMergeFunctionsPass(*PassRegistry::getPassRegistry());
171 bool runOnModule(Module &M);
174 typedef DenseSet<ComparableFunction> FnSetType;
176 /// A work queue of functions that may have been modified and should be
178 std::vector<WeakVH> Deferred;
180 /// Insert a ComparableFunction into the FnSet, or merge it away if it's
181 /// equal to one that's already present.
182 bool Insert(ComparableFunction &NewF);
184 /// Remove a Function from the FnSet and queue it up for a second sweep of
186 void Remove(Function *F);
188 /// Find the functions that use this Value and remove them from FnSet and
189 /// queue the functions.
190 void RemoveUsers(Value *V);
192 /// MergeTwoFunctions - Merge two equivalent functions. Upon completion, G
193 /// may be deleted, or may be converted into a thunk. In either case, it
194 /// should never be visited again.
195 void MergeTwoFunctions(Function *F, Function *G);
197 /// WriteThunk - Replace G with a simple tail call to bitcast(F). Also
198 /// replace direct uses of G with bitcast(F). Deletes G.
199 void WriteThunk(Function *F, Function *G);
201 /// The set of all distinct functions. Use the Insert and Remove methods to
205 /// TargetData for more accurate GEP comparisons. May be NULL.
209 } // end anonymous namespace
211 char MergeFunctions::ID = 0;
212 INITIALIZE_PASS(MergeFunctions, "mergefunc", "Merge Functions", false, false)
214 ModulePass *llvm::createMergeFunctionsPass() {
215 return new MergeFunctions();
219 /// FunctionComparator - Compares two functions to determine whether or not
220 /// they will generate machine code with the same behaviour. TargetData is
221 /// used if available. The comparator always fails conservatively (erring on the
222 /// side of claiming that two functions are different).
223 class FunctionComparator {
225 FunctionComparator(const TargetData *TD, const Function *F1,
227 : F1(F1), F2(F2), TD(TD), IDMap1Count(0), IDMap2Count(0) {}
229 /// Compare - test whether the two functions have equivalent behaviour.
233 /// Compare - test whether two basic blocks have equivalent behaviour.
234 bool Compare(const BasicBlock *BB1, const BasicBlock *BB2);
236 /// Enumerate - Assign or look up previously assigned numbers for the two
237 /// values, and return whether the numbers are equal. Numbers are assigned in
238 /// the order visited.
239 bool Enumerate(const Value *V1, const Value *V2);
241 /// isEquivalentOperation - Compare two Instructions for equivalence, similar
242 /// to Instruction::isSameOperationAs but with modifications to the type
244 bool isEquivalentOperation(const Instruction *I1,
245 const Instruction *I2) const;
247 /// isEquivalentGEP - Compare two GEPs for equivalent pointer arithmetic.
248 bool isEquivalentGEP(const GEPOperator *GEP1, const GEPOperator *GEP2);
249 bool isEquivalentGEP(const GetElementPtrInst *GEP1,
250 const GetElementPtrInst *GEP2) {
251 return isEquivalentGEP(cast<GEPOperator>(GEP1), cast<GEPOperator>(GEP2));
254 /// isEquivalentType - Compare two Types, treating all pointer types as equal.
255 bool isEquivalentType(const Type *Ty1, const Type *Ty2) const;
257 // The two functions undergoing comparison.
258 const Function *F1, *F2;
260 const TargetData *TD;
262 typedef DenseMap<const Value *, unsigned long> IDMap;
264 unsigned long IDMap1Count, IDMap2Count;
268 /// isEquivalentType - any two pointers in the same address space are
269 /// equivalent. Otherwise, standard type equivalence rules apply.
270 bool FunctionComparator::isEquivalentType(const Type *Ty1,
271 const Type *Ty2) const {
274 if (Ty1->getTypeID() != Ty2->getTypeID())
277 switch(Ty1->getTypeID()) {
279 llvm_unreachable("Unknown type!");
280 // Fall through in Release mode.
281 case Type::IntegerTyID:
282 case Type::OpaqueTyID:
283 // Ty1 == Ty2 would have returned true earlier.
287 case Type::FloatTyID:
288 case Type::DoubleTyID:
289 case Type::X86_FP80TyID:
290 case Type::FP128TyID:
291 case Type::PPC_FP128TyID:
292 case Type::LabelTyID:
293 case Type::MetadataTyID:
296 case Type::PointerTyID: {
297 const PointerType *PTy1 = cast<PointerType>(Ty1);
298 const PointerType *PTy2 = cast<PointerType>(Ty2);
299 return PTy1->getAddressSpace() == PTy2->getAddressSpace();
302 case Type::StructTyID: {
303 const StructType *STy1 = cast<StructType>(Ty1);
304 const StructType *STy2 = cast<StructType>(Ty2);
305 if (STy1->getNumElements() != STy2->getNumElements())
308 if (STy1->isPacked() != STy2->isPacked())
311 for (unsigned i = 0, e = STy1->getNumElements(); i != e; ++i) {
312 if (!isEquivalentType(STy1->getElementType(i), STy2->getElementType(i)))
318 case Type::FunctionTyID: {
319 const FunctionType *FTy1 = cast<FunctionType>(Ty1);
320 const FunctionType *FTy2 = cast<FunctionType>(Ty2);
321 if (FTy1->getNumParams() != FTy2->getNumParams() ||
322 FTy1->isVarArg() != FTy2->isVarArg())
325 if (!isEquivalentType(FTy1->getReturnType(), FTy2->getReturnType()))
328 for (unsigned i = 0, e = FTy1->getNumParams(); i != e; ++i) {
329 if (!isEquivalentType(FTy1->getParamType(i), FTy2->getParamType(i)))
335 case Type::ArrayTyID: {
336 const ArrayType *ATy1 = cast<ArrayType>(Ty1);
337 const ArrayType *ATy2 = cast<ArrayType>(Ty2);
338 return ATy1->getNumElements() == ATy2->getNumElements() &&
339 isEquivalentType(ATy1->getElementType(), ATy2->getElementType());
342 case Type::VectorTyID: {
343 const VectorType *VTy1 = cast<VectorType>(Ty1);
344 const VectorType *VTy2 = cast<VectorType>(Ty2);
345 return VTy1->getNumElements() == VTy2->getNumElements() &&
346 isEquivalentType(VTy1->getElementType(), VTy2->getElementType());
351 /// isEquivalentOperation - determine whether the two operations are the same
352 /// except that pointer-to-A and pointer-to-B are equivalent. This should be
353 /// kept in sync with Instruction::isSameOperationAs.
354 bool FunctionComparator::isEquivalentOperation(const Instruction *I1,
355 const Instruction *I2) const {
356 if (I1->getOpcode() != I2->getOpcode() ||
357 I1->getNumOperands() != I2->getNumOperands() ||
358 !isEquivalentType(I1->getType(), I2->getType()) ||
359 !I1->hasSameSubclassOptionalData(I2))
362 // We have two instructions of identical opcode and #operands. Check to see
363 // if all operands are the same type
364 for (unsigned i = 0, e = I1->getNumOperands(); i != e; ++i)
365 if (!isEquivalentType(I1->getOperand(i)->getType(),
366 I2->getOperand(i)->getType()))
369 // Check special state that is a part of some instructions.
370 if (const LoadInst *LI = dyn_cast<LoadInst>(I1))
371 return LI->isVolatile() == cast<LoadInst>(I2)->isVolatile() &&
372 LI->getAlignment() == cast<LoadInst>(I2)->getAlignment();
373 if (const StoreInst *SI = dyn_cast<StoreInst>(I1))
374 return SI->isVolatile() == cast<StoreInst>(I2)->isVolatile() &&
375 SI->getAlignment() == cast<StoreInst>(I2)->getAlignment();
376 if (const CmpInst *CI = dyn_cast<CmpInst>(I1))
377 return CI->getPredicate() == cast<CmpInst>(I2)->getPredicate();
378 if (const CallInst *CI = dyn_cast<CallInst>(I1))
379 return CI->isTailCall() == cast<CallInst>(I2)->isTailCall() &&
380 CI->getCallingConv() == cast<CallInst>(I2)->getCallingConv() &&
381 CI->getAttributes().getRawPointer() ==
382 cast<CallInst>(I2)->getAttributes().getRawPointer();
383 if (const InvokeInst *CI = dyn_cast<InvokeInst>(I1))
384 return CI->getCallingConv() == cast<InvokeInst>(I2)->getCallingConv() &&
385 CI->getAttributes().getRawPointer() ==
386 cast<InvokeInst>(I2)->getAttributes().getRawPointer();
387 if (const InsertValueInst *IVI = dyn_cast<InsertValueInst>(I1)) {
388 if (IVI->getNumIndices() != cast<InsertValueInst>(I2)->getNumIndices())
390 for (unsigned i = 0, e = IVI->getNumIndices(); i != e; ++i)
391 if (IVI->idx_begin()[i] != cast<InsertValueInst>(I2)->idx_begin()[i])
395 if (const ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(I1)) {
396 if (EVI->getNumIndices() != cast<ExtractValueInst>(I2)->getNumIndices())
398 for (unsigned i = 0, e = EVI->getNumIndices(); i != e; ++i)
399 if (EVI->idx_begin()[i] != cast<ExtractValueInst>(I2)->idx_begin()[i])
407 /// isEquivalentGEP - determine whether two GEP operations perform the same
408 /// underlying arithmetic.
409 bool FunctionComparator::isEquivalentGEP(const GEPOperator *GEP1,
410 const GEPOperator *GEP2) {
411 // When we have target data, we can reduce the GEP down to the value in bytes
412 // added to the address.
413 if (TD && GEP1->hasAllConstantIndices() && GEP2->hasAllConstantIndices()) {
414 SmallVector<Value *, 8> Indices1(GEP1->idx_begin(), GEP1->idx_end());
415 SmallVector<Value *, 8> Indices2(GEP2->idx_begin(), GEP2->idx_end());
416 uint64_t Offset1 = TD->getIndexedOffset(GEP1->getPointerOperandType(),
417 Indices1.data(), Indices1.size());
418 uint64_t Offset2 = TD->getIndexedOffset(GEP2->getPointerOperandType(),
419 Indices2.data(), Indices2.size());
420 return Offset1 == Offset2;
423 if (GEP1->getPointerOperand()->getType() !=
424 GEP2->getPointerOperand()->getType())
427 if (GEP1->getNumOperands() != GEP2->getNumOperands())
430 for (unsigned i = 0, e = GEP1->getNumOperands(); i != e; ++i) {
431 if (!Enumerate(GEP1->getOperand(i), GEP2->getOperand(i)))
438 /// Enumerate - Compare two values used by the two functions under pair-wise
439 /// comparison. If this is the first time the values are seen, they're added to
440 /// the mapping so that we will detect mismatches on next use.
441 bool FunctionComparator::Enumerate(const Value *V1, const Value *V2) {
442 // Check for function @f1 referring to itself and function @f2 referring to
443 // itself, or referring to each other, or both referring to either of them.
444 // They're all equivalent if the two functions are otherwise equivalent.
445 if (V1 == F1 && V2 == F2)
447 if (V1 == F2 && V2 == F1)
450 // TODO: constant expressions with GEP or references to F1 or F2.
451 if (isa<Constant>(V1))
454 if (isa<InlineAsm>(V1) && isa<InlineAsm>(V2)) {
455 const InlineAsm *IA1 = cast<InlineAsm>(V1);
456 const InlineAsm *IA2 = cast<InlineAsm>(V2);
457 return IA1->getAsmString() == IA2->getAsmString() &&
458 IA1->getConstraintString() == IA2->getConstraintString();
461 unsigned long &ID1 = Map1[V1];
465 unsigned long &ID2 = Map2[V2];
472 /// Compare - test whether two basic blocks have equivalent behaviour.
473 bool FunctionComparator::Compare(const BasicBlock *BB1, const BasicBlock *BB2) {
474 BasicBlock::const_iterator F1I = BB1->begin(), F1E = BB1->end();
475 BasicBlock::const_iterator F2I = BB2->begin(), F2E = BB2->end();
478 if (!Enumerate(F1I, F2I))
481 if (const GetElementPtrInst *GEP1 = dyn_cast<GetElementPtrInst>(F1I)) {
482 const GetElementPtrInst *GEP2 = dyn_cast<GetElementPtrInst>(F2I);
486 if (!Enumerate(GEP1->getPointerOperand(), GEP2->getPointerOperand()))
489 if (!isEquivalentGEP(GEP1, GEP2))
492 if (!isEquivalentOperation(F1I, F2I))
495 assert(F1I->getNumOperands() == F2I->getNumOperands());
496 for (unsigned i = 0, e = F1I->getNumOperands(); i != e; ++i) {
497 Value *OpF1 = F1I->getOperand(i);
498 Value *OpF2 = F2I->getOperand(i);
500 if (!Enumerate(OpF1, OpF2))
503 if (OpF1->getValueID() != OpF2->getValueID() ||
504 !isEquivalentType(OpF1->getType(), OpF2->getType()))
510 } while (F1I != F1E && F2I != F2E);
512 return F1I == F1E && F2I == F2E;
515 /// Compare - test whether the two functions have equivalent behaviour.
516 bool FunctionComparator::Compare() {
517 // We need to recheck everything, but check the things that weren't included
518 // in the hash first.
520 if (F1->getAttributes() != F2->getAttributes())
523 if (F1->hasGC() != F2->hasGC())
526 if (F1->hasGC() && F1->getGC() != F2->getGC())
529 if (F1->hasSection() != F2->hasSection())
532 if (F1->hasSection() && F1->getSection() != F2->getSection())
535 if (F1->isVarArg() != F2->isVarArg())
538 // TODO: if it's internal and only used in direct calls, we could handle this
540 if (F1->getCallingConv() != F2->getCallingConv())
543 if (!isEquivalentType(F1->getFunctionType(), F2->getFunctionType()))
546 assert(F1->arg_size() == F2->arg_size() &&
547 "Identically typed functions have different numbers of args!");
549 // Visit the arguments so that they get enumerated in the order they're
551 for (Function::const_arg_iterator f1i = F1->arg_begin(),
552 f2i = F2->arg_begin(), f1e = F1->arg_end(); f1i != f1e; ++f1i, ++f2i) {
553 if (!Enumerate(f1i, f2i))
554 llvm_unreachable("Arguments repeat!");
557 // We do a CFG-ordered walk since the actual ordering of the blocks in the
558 // linked list is immaterial. Our walk starts at the entry block for both
559 // functions, then takes each block from each terminator in order. As an
560 // artifact, this also means that unreachable blocks are ignored.
561 SmallVector<const BasicBlock *, 8> F1BBs, F2BBs;
562 SmallSet<const BasicBlock *, 128> VisitedBBs; // in terms of F1.
564 F1BBs.push_back(&F1->getEntryBlock());
565 F2BBs.push_back(&F2->getEntryBlock());
567 VisitedBBs.insert(F1BBs[0]);
568 while (!F1BBs.empty()) {
569 const BasicBlock *F1BB = F1BBs.pop_back_val();
570 const BasicBlock *F2BB = F2BBs.pop_back_val();
572 if (!Enumerate(F1BB, F2BB) || !Compare(F1BB, F2BB))
575 const TerminatorInst *F1TI = F1BB->getTerminator();
576 const TerminatorInst *F2TI = F2BB->getTerminator();
578 assert(F1TI->getNumSuccessors() == F2TI->getNumSuccessors());
579 for (unsigned i = 0, e = F1TI->getNumSuccessors(); i != e; ++i) {
580 if (!VisitedBBs.insert(F1TI->getSuccessor(i)))
583 F1BBs.push_back(F1TI->getSuccessor(i));
584 F2BBs.push_back(F2TI->getSuccessor(i));
590 /// WriteThunk - Replace G with a simple tail call to bitcast(F). Also replace
591 /// direct uses of G with bitcast(F). Deletes G.
592 void MergeFunctions::WriteThunk(Function *F, Function *G) {
593 if (!G->mayBeOverridden()) {
594 // Redirect direct callers of G to F.
595 Constant *BitcastF = ConstantExpr::getBitCast(F, G->getType());
596 for (Value::use_iterator UI = G->use_begin(), UE = G->use_end();
598 Value::use_iterator TheIter = UI;
600 CallSite CS(*TheIter);
601 if (CS && CS.isCallee(TheIter)) {
602 Remove(CS.getInstruction()->getParent()->getParent());
603 TheIter.getUse().set(BitcastF);
608 // If G was internal then we may have replaced all uses of G with F. If so,
609 // stop here and delete G. There's no need for a thunk.
610 if (G->hasLocalLinkage() && G->use_empty()) {
611 G->eraseFromParent();
615 Function *NewG = Function::Create(G->getFunctionType(), G->getLinkage(), "",
617 BasicBlock *BB = BasicBlock::Create(F->getContext(), "", NewG);
618 IRBuilder<false> Builder(BB);
620 SmallVector<Value *, 16> Args;
622 const FunctionType *FFTy = F->getFunctionType();
623 for (Function::arg_iterator AI = NewG->arg_begin(), AE = NewG->arg_end();
625 Args.push_back(Builder.CreateBitCast(AI, FFTy->getParamType(i)));
629 CallInst *CI = Builder.CreateCall(F, Args.begin(), Args.end());
631 CI->setCallingConv(F->getCallingConv());
632 if (NewG->getReturnType()->isVoidTy()) {
633 Builder.CreateRetVoid();
635 Builder.CreateRet(Builder.CreateBitCast(CI, NewG->getReturnType()));
638 NewG->copyAttributesFrom(G);
641 G->replaceAllUsesWith(NewG);
642 G->eraseFromParent();
644 DEBUG(dbgs() << "WriteThunk: " << NewG->getName() << '\n');
648 /// MergeTwoFunctions - Merge two equivalent functions. Upon completion,
649 /// Function G is deleted.
650 void MergeFunctions::MergeTwoFunctions(Function *F, Function *G) {
651 if (F->mayBeOverridden()) {
652 assert(G->mayBeOverridden());
654 // Make them both thunks to the same internal function.
655 Function *H = Function::Create(F->getFunctionType(), F->getLinkage(), "",
657 H->copyAttributesFrom(F);
660 F->replaceAllUsesWith(H);
662 unsigned MaxAlignment = std::max(G->getAlignment(), H->getAlignment());
667 F->setAlignment(MaxAlignment);
668 F->setLinkage(GlobalValue::PrivateLinkage);
675 ++NumFunctionsMerged;
678 // Insert - Insert a ComparableFunction into the FnSet, or merge it away if
679 // equal to one that's already inserted.
680 bool MergeFunctions::Insert(ComparableFunction &NewF) {
681 std::pair<FnSetType::iterator, bool> Result = FnSet.insert(NewF);
685 const ComparableFunction &OldF = *Result.first;
687 // Never thunk a strong function to a weak function.
688 assert(!OldF.getFunc()->mayBeOverridden() ||
689 NewF.getFunc()->mayBeOverridden());
691 DEBUG(dbgs() << " " << OldF.getFunc()->getName() << " == "
692 << NewF.getFunc()->getName() << '\n');
694 Function *DeleteF = NewF.getFunc();
696 MergeTwoFunctions(OldF.getFunc(), DeleteF);
700 // Remove - Remove a function from FnSet. If it was already in FnSet, add it to
701 // Deferred so that we'll look at it in the next round.
702 void MergeFunctions::Remove(Function *F) {
703 ComparableFunction CF = ComparableFunction(F, TD);
704 if (FnSet.erase(CF)) {
705 Deferred.push_back(F);
709 // RemoveUsers - For each instruction used by the value, Remove() the function
710 // that contains the instruction. This should happen right before a call to RAUW.
711 void MergeFunctions::RemoveUsers(Value *V) {
712 std::vector<Value *> Worklist;
713 Worklist.push_back(V);
714 while (!Worklist.empty()) {
715 Value *V = Worklist.back();
718 for (Value::use_iterator UI = V->use_begin(), UE = V->use_end();
720 Use &U = UI.getUse();
721 if (Instruction *I = dyn_cast<Instruction>(U.getUser())) {
722 Remove(I->getParent()->getParent());
723 } else if (isa<GlobalValue>(U.getUser())) {
725 } else if (Constant *C = dyn_cast<Constant>(U.getUser())) {
726 for (Value::use_iterator CUI = C->use_begin(), CUE = C->use_end();
728 Worklist.push_back(*CUI);
734 bool MergeFunctions::runOnModule(Module &M) {
735 bool Changed = false;
736 TD = getAnalysisIfAvailable<TargetData>();
738 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
739 Deferred.push_back(WeakVH(I));
743 std::vector<WeakVH> Worklist;
744 Deferred.swap(Worklist);
746 DEBUG(dbgs() << "size of module: " << M.size() << '\n');
747 DEBUG(dbgs() << "size of worklist: " << Worklist.size() << '\n');
749 // Insert only strong functions and merge them. Strong function merging
750 // always deletes one of them.
751 for (std::vector<WeakVH>::iterator I = Worklist.begin(),
752 E = Worklist.end(); I != E; ++I) {
754 Function *F = cast<Function>(*I);
755 if (!F->isDeclaration() && !F->hasAvailableExternallyLinkage() &&
756 !F->mayBeOverridden()) {
757 ComparableFunction CF = ComparableFunction(F, TD);
758 Changed |= Insert(CF);
762 // Insert only weak functions and merge them. By doing these second we
763 // create thunks to the strong function when possible. When two weak
764 // functions are identical, we create a new strong function with two weak
765 // weak thunks to it which are identical but not mergable.
766 for (std::vector<WeakVH>::iterator I = Worklist.begin(),
767 E = Worklist.end(); I != E; ++I) {
769 Function *F = cast<Function>(*I);
770 if (!F->isDeclaration() && !F->hasAvailableExternallyLinkage() &&
771 F->mayBeOverridden()) {
772 ComparableFunction CF = ComparableFunction(F, TD);
773 Changed |= Insert(CF);
776 DEBUG(dbgs() << "size of FnSet: " << FnSet.size() << '\n');
777 } while (!Deferred.empty());
784 bool DenseMapInfo<ComparableFunction>::isEqual(const ComparableFunction &LHS,
785 const ComparableFunction &RHS) {
786 if (LHS.getFunc() == RHS.getFunc() &&
787 LHS.getHash() == RHS.getHash())
789 if (!LHS.getFunc() || !RHS.getFunc())
791 assert(LHS.getTD() == RHS.getTD() &&
792 "Comparing functions for different targets");
795 bool &result1 = LHS.getOrInsertCachedComparison(RHS, inserted);
798 bool &result2 = RHS.getOrInsertCachedComparison(LHS, inserted);
800 return result1 = result2;
802 return result1 = result2 = FunctionComparator(LHS.getTD(), LHS.getFunc(),
803 RHS.getFunc()).Compare();