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");
73 static unsigned ProfileFunction(const Function *F) {
74 const FunctionType *FTy = F->getFunctionType();
77 ID.AddInteger(F->size());
78 ID.AddInteger(F->getCallingConv());
79 ID.AddBoolean(F->hasGC());
80 ID.AddBoolean(FTy->isVarArg());
81 ID.AddInteger(FTy->getReturnType()->getTypeID());
82 for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
83 ID.AddInteger(FTy->getParamType(i)->getTypeID());
84 return ID.ComputeHash();
87 class ComparableFunction {
89 static const ComparableFunction EmptyKey;
90 static const ComparableFunction TombstoneKey;
92 ComparableFunction(Function *Func, TargetData *TD)
93 : Func(Func), Hash(ProfileFunction(Func)), TD(TD) {}
95 Function *getFunc() const { return Func; }
96 unsigned getHash() const { return Hash; }
97 TargetData *getTD() const { return TD; }
99 // Drops AssertingVH reference to the function. Outside of debug mode, this
103 "Attempted to release function twice, or release empty/tombstone!");
108 explicit ComparableFunction(unsigned Hash)
109 : Func(NULL), Hash(Hash), TD(NULL) {}
111 AssertingVH<Function> Func;
116 const ComparableFunction ComparableFunction::EmptyKey = ComparableFunction(0);
117 const ComparableFunction ComparableFunction::TombstoneKey =
118 ComparableFunction(1);
120 } // anonymous namespace
124 struct DenseMapInfo<ComparableFunction> {
125 static ComparableFunction getEmptyKey() {
126 return ComparableFunction::EmptyKey;
128 static ComparableFunction getTombstoneKey() {
129 return ComparableFunction::TombstoneKey;
131 static unsigned getHashValue(const ComparableFunction &CF) {
134 static bool isEqual(const ComparableFunction &LHS,
135 const ComparableFunction &RHS);
141 /// MergeFunctions finds functions which will generate identical machine code,
142 /// by considering all pointer types to be equivalent. Once identified,
143 /// MergeFunctions will fold them by replacing a call to one to a call to a
144 /// bitcast of the other.
146 class MergeFunctions : public ModulePass {
149 MergeFunctions() : ModulePass(ID) {}
151 bool runOnModule(Module &M);
154 typedef DenseSet<ComparableFunction> FnSetType;
157 /// Insert a ComparableFunction into the FnSet, or merge it away if it's
158 /// equal to one that's already present.
159 bool Insert(FnSetType &FnSet, ComparableFunction &NewF);
161 /// MergeTwoFunctions - Merge two equivalent functions. Upon completion, G
162 /// may be deleted, or may be converted into a thunk. In either case, it
163 /// should never be visited again.
164 void MergeTwoFunctions(Function *F, Function *G) const;
166 /// WriteThunk - Replace G with a simple tail call to bitcast(F). Also
167 /// replace direct uses of G with bitcast(F). Deletes G.
168 void WriteThunk(Function *F, Function *G) const;
173 } // end anonymous namespace
175 char MergeFunctions::ID = 0;
176 INITIALIZE_PASS(MergeFunctions, "mergefunc", "Merge Functions", false, false);
178 ModulePass *llvm::createMergeFunctionsPass() {
179 return new MergeFunctions();
183 /// FunctionComparator - Compares two functions to determine whether or not
184 /// they will generate machine code with the same behaviour. TargetData is
185 /// used if available. The comparator always fails conservatively (erring on the
186 /// side of claiming that two functions are different).
187 class FunctionComparator {
189 FunctionComparator(const TargetData *TD, const Function *F1,
191 : F1(F1), F2(F2), TD(TD), IDMap1Count(0), IDMap2Count(0) {}
193 /// Compare - test whether the two functions have equivalent behaviour.
197 /// Compare - test whether two basic blocks have equivalent behaviour.
198 bool Compare(const BasicBlock *BB1, const BasicBlock *BB2);
200 /// Enumerate - Assign or look up previously assigned numbers for the two
201 /// values, and return whether the numbers are equal. Numbers are assigned in
202 /// the order visited.
203 bool Enumerate(const Value *V1, const Value *V2);
205 /// isEquivalentOperation - Compare two Instructions for equivalence, similar
206 /// to Instruction::isSameOperationAs but with modifications to the type
208 bool isEquivalentOperation(const Instruction *I1,
209 const Instruction *I2) const;
211 /// isEquivalentGEP - Compare two GEPs for equivalent pointer arithmetic.
212 bool isEquivalentGEP(const GEPOperator *GEP1, const GEPOperator *GEP2);
213 bool isEquivalentGEP(const GetElementPtrInst *GEP1,
214 const GetElementPtrInst *GEP2) {
215 return isEquivalentGEP(cast<GEPOperator>(GEP1), cast<GEPOperator>(GEP2));
218 /// isEquivalentType - Compare two Types, treating all pointer types as equal.
219 bool isEquivalentType(const Type *Ty1, const Type *Ty2) const;
221 // The two functions undergoing comparison.
222 const Function *F1, *F2;
224 const TargetData *TD;
226 typedef DenseMap<const Value *, unsigned long> IDMap;
228 unsigned long IDMap1Count, IDMap2Count;
232 /// isEquivalentType - any two pointers in the same address space are
233 /// equivalent. Otherwise, standard type equivalence rules apply.
234 bool FunctionComparator::isEquivalentType(const Type *Ty1,
235 const Type *Ty2) const {
238 if (Ty1->getTypeID() != Ty2->getTypeID())
241 switch(Ty1->getTypeID()) {
243 llvm_unreachable("Unknown type!");
244 // Fall through in Release mode.
245 case Type::IntegerTyID:
246 case Type::OpaqueTyID:
247 // Ty1 == Ty2 would have returned true earlier.
251 case Type::FloatTyID:
252 case Type::DoubleTyID:
253 case Type::X86_FP80TyID:
254 case Type::FP128TyID:
255 case Type::PPC_FP128TyID:
256 case Type::LabelTyID:
257 case Type::MetadataTyID:
260 case Type::PointerTyID: {
261 const PointerType *PTy1 = cast<PointerType>(Ty1);
262 const PointerType *PTy2 = cast<PointerType>(Ty2);
263 return PTy1->getAddressSpace() == PTy2->getAddressSpace();
266 case Type::StructTyID: {
267 const StructType *STy1 = cast<StructType>(Ty1);
268 const StructType *STy2 = cast<StructType>(Ty2);
269 if (STy1->getNumElements() != STy2->getNumElements())
272 if (STy1->isPacked() != STy2->isPacked())
275 for (unsigned i = 0, e = STy1->getNumElements(); i != e; ++i) {
276 if (!isEquivalentType(STy1->getElementType(i), STy2->getElementType(i)))
282 case Type::FunctionTyID: {
283 const FunctionType *FTy1 = cast<FunctionType>(Ty1);
284 const FunctionType *FTy2 = cast<FunctionType>(Ty2);
285 if (FTy1->getNumParams() != FTy2->getNumParams() ||
286 FTy1->isVarArg() != FTy2->isVarArg())
289 if (!isEquivalentType(FTy1->getReturnType(), FTy2->getReturnType()))
292 for (unsigned i = 0, e = FTy1->getNumParams(); i != e; ++i) {
293 if (!isEquivalentType(FTy1->getParamType(i), FTy2->getParamType(i)))
299 case Type::ArrayTyID: {
300 const ArrayType *ATy1 = cast<ArrayType>(Ty1);
301 const ArrayType *ATy2 = cast<ArrayType>(Ty2);
302 return ATy1->getNumElements() == ATy2->getNumElements() &&
303 isEquivalentType(ATy1->getElementType(), ATy2->getElementType());
306 case Type::VectorTyID: {
307 const VectorType *VTy1 = cast<VectorType>(Ty1);
308 const VectorType *VTy2 = cast<VectorType>(Ty2);
309 return VTy1->getNumElements() == VTy2->getNumElements() &&
310 isEquivalentType(VTy1->getElementType(), VTy2->getElementType());
315 /// isEquivalentOperation - determine whether the two operations are the same
316 /// except that pointer-to-A and pointer-to-B are equivalent. This should be
317 /// kept in sync with Instruction::isSameOperationAs.
318 bool FunctionComparator::isEquivalentOperation(const Instruction *I1,
319 const Instruction *I2) const {
320 if (I1->getOpcode() != I2->getOpcode() ||
321 I1->getNumOperands() != I2->getNumOperands() ||
322 !isEquivalentType(I1->getType(), I2->getType()) ||
323 !I1->hasSameSubclassOptionalData(I2))
326 // We have two instructions of identical opcode and #operands. Check to see
327 // if all operands are the same type
328 for (unsigned i = 0, e = I1->getNumOperands(); i != e; ++i)
329 if (!isEquivalentType(I1->getOperand(i)->getType(),
330 I2->getOperand(i)->getType()))
333 // Check special state that is a part of some instructions.
334 if (const LoadInst *LI = dyn_cast<LoadInst>(I1))
335 return LI->isVolatile() == cast<LoadInst>(I2)->isVolatile() &&
336 LI->getAlignment() == cast<LoadInst>(I2)->getAlignment();
337 if (const StoreInst *SI = dyn_cast<StoreInst>(I1))
338 return SI->isVolatile() == cast<StoreInst>(I2)->isVolatile() &&
339 SI->getAlignment() == cast<StoreInst>(I2)->getAlignment();
340 if (const CmpInst *CI = dyn_cast<CmpInst>(I1))
341 return CI->getPredicate() == cast<CmpInst>(I2)->getPredicate();
342 if (const CallInst *CI = dyn_cast<CallInst>(I1))
343 return CI->isTailCall() == cast<CallInst>(I2)->isTailCall() &&
344 CI->getCallingConv() == cast<CallInst>(I2)->getCallingConv() &&
345 CI->getAttributes().getRawPointer() ==
346 cast<CallInst>(I2)->getAttributes().getRawPointer();
347 if (const InvokeInst *CI = dyn_cast<InvokeInst>(I1))
348 return CI->getCallingConv() == cast<InvokeInst>(I2)->getCallingConv() &&
349 CI->getAttributes().getRawPointer() ==
350 cast<InvokeInst>(I2)->getAttributes().getRawPointer();
351 if (const InsertValueInst *IVI = dyn_cast<InsertValueInst>(I1)) {
352 if (IVI->getNumIndices() != cast<InsertValueInst>(I2)->getNumIndices())
354 for (unsigned i = 0, e = IVI->getNumIndices(); i != e; ++i)
355 if (IVI->idx_begin()[i] != cast<InsertValueInst>(I2)->idx_begin()[i])
359 if (const ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(I1)) {
360 if (EVI->getNumIndices() != cast<ExtractValueInst>(I2)->getNumIndices())
362 for (unsigned i = 0, e = EVI->getNumIndices(); i != e; ++i)
363 if (EVI->idx_begin()[i] != cast<ExtractValueInst>(I2)->idx_begin()[i])
371 /// isEquivalentGEP - determine whether two GEP operations perform the same
372 /// underlying arithmetic.
373 bool FunctionComparator::isEquivalentGEP(const GEPOperator *GEP1,
374 const GEPOperator *GEP2) {
375 // When we have target data, we can reduce the GEP down to the value in bytes
376 // added to the address.
377 if (TD && GEP1->hasAllConstantIndices() && GEP2->hasAllConstantIndices()) {
378 SmallVector<Value *, 8> Indices1(GEP1->idx_begin(), GEP1->idx_end());
379 SmallVector<Value *, 8> Indices2(GEP2->idx_begin(), GEP2->idx_end());
380 uint64_t Offset1 = TD->getIndexedOffset(GEP1->getPointerOperandType(),
381 Indices1.data(), Indices1.size());
382 uint64_t Offset2 = TD->getIndexedOffset(GEP2->getPointerOperandType(),
383 Indices2.data(), Indices2.size());
384 return Offset1 == Offset2;
387 if (GEP1->getPointerOperand()->getType() !=
388 GEP2->getPointerOperand()->getType())
391 if (GEP1->getNumOperands() != GEP2->getNumOperands())
394 for (unsigned i = 0, e = GEP1->getNumOperands(); i != e; ++i) {
395 if (!Enumerate(GEP1->getOperand(i), GEP2->getOperand(i)))
402 /// Enumerate - Compare two values used by the two functions under pair-wise
403 /// comparison. If this is the first time the values are seen, they're added to
404 /// the mapping so that we will detect mismatches on next use.
405 bool FunctionComparator::Enumerate(const Value *V1, const Value *V2) {
406 // Check for function @f1 referring to itself and function @f2 referring to
407 // itself, or referring to each other, or both referring to either of them.
408 // They're all equivalent if the two functions are otherwise equivalent.
409 if (V1 == F1 && V2 == F2)
411 if (V1 == F2 && V2 == F1)
414 // TODO: constant expressions with GEP or references to F1 or F2.
415 if (isa<Constant>(V1))
418 if (isa<InlineAsm>(V1) && isa<InlineAsm>(V2)) {
419 const InlineAsm *IA1 = cast<InlineAsm>(V1);
420 const InlineAsm *IA2 = cast<InlineAsm>(V2);
421 return IA1->getAsmString() == IA2->getAsmString() &&
422 IA1->getConstraintString() == IA2->getConstraintString();
425 unsigned long &ID1 = Map1[V1];
429 unsigned long &ID2 = Map2[V2];
436 /// Compare - test whether two basic blocks have equivalent behaviour.
437 bool FunctionComparator::Compare(const BasicBlock *BB1, const BasicBlock *BB2) {
438 BasicBlock::const_iterator F1I = BB1->begin(), F1E = BB1->end();
439 BasicBlock::const_iterator F2I = BB2->begin(), F2E = BB2->end();
442 if (!Enumerate(F1I, F2I))
445 if (const GetElementPtrInst *GEP1 = dyn_cast<GetElementPtrInst>(F1I)) {
446 const GetElementPtrInst *GEP2 = dyn_cast<GetElementPtrInst>(F2I);
450 if (!Enumerate(GEP1->getPointerOperand(), GEP2->getPointerOperand()))
453 if (!isEquivalentGEP(GEP1, GEP2))
456 if (!isEquivalentOperation(F1I, F2I))
459 assert(F1I->getNumOperands() == F2I->getNumOperands());
460 for (unsigned i = 0, e = F1I->getNumOperands(); i != e; ++i) {
461 Value *OpF1 = F1I->getOperand(i);
462 Value *OpF2 = F2I->getOperand(i);
464 if (!Enumerate(OpF1, OpF2))
467 if (OpF1->getValueID() != OpF2->getValueID() ||
468 !isEquivalentType(OpF1->getType(), OpF2->getType()))
474 } while (F1I != F1E && F2I != F2E);
476 return F1I == F1E && F2I == F2E;
479 /// Compare - test whether the two functions have equivalent behaviour.
480 bool FunctionComparator::Compare() {
481 // We need to recheck everything, but check the things that weren't included
482 // in the hash first.
484 if (F1->getAttributes() != F2->getAttributes())
487 if (F1->hasGC() != F2->hasGC())
490 if (F1->hasGC() && F1->getGC() != F2->getGC())
493 if (F1->hasSection() != F2->hasSection())
496 if (F1->hasSection() && F1->getSection() != F2->getSection())
499 if (F1->isVarArg() != F2->isVarArg())
502 // TODO: if it's internal and only used in direct calls, we could handle this
504 if (F1->getCallingConv() != F2->getCallingConv())
507 if (!isEquivalentType(F1->getFunctionType(), F2->getFunctionType()))
510 assert(F1->arg_size() == F2->arg_size() &&
511 "Identical functions have a different number of args.");
513 // Visit the arguments so that they get enumerated in the order they're
515 for (Function::const_arg_iterator f1i = F1->arg_begin(),
516 f2i = F2->arg_begin(), f1e = F1->arg_end(); f1i != f1e; ++f1i, ++f2i) {
517 if (!Enumerate(f1i, f2i))
518 llvm_unreachable("Arguments repeat");
521 // We do a CFG-ordered walk since the actual ordering of the blocks in the
522 // linked list is immaterial. Our walk starts at the entry block for both
523 // functions, then takes each block from each terminator in order. As an
524 // artifact, this also means that unreachable blocks are ignored.
525 SmallVector<const BasicBlock *, 8> F1BBs, F2BBs;
526 SmallSet<const BasicBlock *, 128> VisitedBBs; // in terms of F1.
528 F1BBs.push_back(&F1->getEntryBlock());
529 F2BBs.push_back(&F2->getEntryBlock());
531 VisitedBBs.insert(F1BBs[0]);
532 while (!F1BBs.empty()) {
533 const BasicBlock *F1BB = F1BBs.pop_back_val();
534 const BasicBlock *F2BB = F2BBs.pop_back_val();
536 if (!Enumerate(F1BB, F2BB) || !Compare(F1BB, F2BB))
539 const TerminatorInst *F1TI = F1BB->getTerminator();
540 const TerminatorInst *F2TI = F2BB->getTerminator();
542 assert(F1TI->getNumSuccessors() == F2TI->getNumSuccessors());
543 for (unsigned i = 0, e = F1TI->getNumSuccessors(); i != e; ++i) {
544 if (!VisitedBBs.insert(F1TI->getSuccessor(i)))
547 F1BBs.push_back(F1TI->getSuccessor(i));
548 F2BBs.push_back(F2TI->getSuccessor(i));
554 /// WriteThunk - Replace G with a simple tail call to bitcast(F). Also replace
555 /// direct uses of G with bitcast(F). Deletes G.
556 void MergeFunctions::WriteThunk(Function *F, Function *G) const {
557 if (!G->mayBeOverridden()) {
558 // Redirect direct callers of G to F.
559 Constant *BitcastF = ConstantExpr::getBitCast(F, G->getType());
560 for (Value::use_iterator UI = G->use_begin(), UE = G->use_end();
562 Value::use_iterator TheIter = UI;
564 CallSite CS(*TheIter);
565 if (CS && CS.isCallee(TheIter))
566 TheIter.getUse().set(BitcastF);
570 // If G was internal then we may have replaced all uses if G with F. If so,
571 // stop here and delete G. There's no need for a thunk.
572 if (G->hasLocalLinkage() && G->use_empty()) {
573 G->eraseFromParent();
577 Function *NewG = Function::Create(G->getFunctionType(), G->getLinkage(), "",
579 BasicBlock *BB = BasicBlock::Create(F->getContext(), "", NewG);
580 IRBuilder<false> Builder(BB);
582 SmallVector<Value *, 16> Args;
584 const FunctionType *FFTy = F->getFunctionType();
585 for (Function::arg_iterator AI = NewG->arg_begin(), AE = NewG->arg_end();
587 Args.push_back(Builder.CreateBitCast(AI, FFTy->getParamType(i)));
591 CallInst *CI = Builder.CreateCall(F, Args.begin(), Args.end());
593 CI->setCallingConv(F->getCallingConv());
594 if (NewG->getReturnType()->isVoidTy()) {
595 Builder.CreateRetVoid();
597 Builder.CreateRet(Builder.CreateBitCast(CI, NewG->getReturnType()));
600 NewG->copyAttributesFrom(G);
602 G->replaceAllUsesWith(NewG);
603 G->eraseFromParent();
606 /// MergeTwoFunctions - Merge two equivalent functions. Upon completion,
607 /// Function G is deleted.
608 void MergeFunctions::MergeTwoFunctions(Function *F, Function *G) const {
609 if (F->isWeakForLinker()) {
610 assert(G->isWeakForLinker());
612 // Make them both thunks to the same internal function.
613 Function *H = Function::Create(F->getFunctionType(), F->getLinkage(), "",
615 H->copyAttributesFrom(F);
617 F->replaceAllUsesWith(H);
619 unsigned MaxAlignment = std::max(G->getAlignment(), H->getAlignment());
624 F->setAlignment(MaxAlignment);
625 F->setLinkage(GlobalValue::InternalLinkage);
630 ++NumFunctionsMerged;
633 // Insert - Insert a ComparableFunction into the FnSet, or merge it away if
634 // equal to one that's already inserted.
635 bool MergeFunctions::Insert(FnSetType &FnSet, ComparableFunction &NewF) {
636 std::pair<FnSetType::iterator, bool> Result = FnSet.insert(NewF);
640 const ComparableFunction &OldF = *Result.first;
642 // Never thunk a strong function to a weak function.
643 assert(!OldF.getFunc()->isWeakForLinker() ||
644 NewF.getFunc()->isWeakForLinker());
646 DEBUG(dbgs() << " " << OldF.getFunc()->getName() << " == "
647 << NewF.getFunc()->getName() << '\n');
649 Function *DeleteF = NewF.getFunc();
651 MergeTwoFunctions(OldF.getFunc(), DeleteF);
655 // IsThunk - This method determines whether or not a given Function is a thunk\// like the ones emitted by this pass and therefore not subject to further
657 static bool IsThunk(const Function *F) {
658 // The safe direction to fail is to return true. In that case, the function
659 // will be removed from merging analysis. If we failed to including functions
660 // then we may try to merge unmergable thing (ie., identical weak functions)
661 // which will push us into an infinite loop.
666 const BasicBlock *BB = &F->front();
669 // optional-reg tail call @thunkee(args...*)
670 // ret void|optional-reg
671 // where the args are in the same order as the arguments.
673 // Verify that the sequence of bitcast-inst's are all casts of arguments and
674 // that there aren't any extras (ie. no repeated casts).
676 BasicBlock::const_iterator I = BB->begin();
677 while (const BitCastInst *BCI = dyn_cast<BitCastInst>(I)) {
678 const Argument *A = dyn_cast<Argument>(BCI->getOperand(0));
679 if (!A) return false;
680 if ((int)A->getArgNo() >= LastArgNo) return false;
681 LastArgNo = A->getArgNo();
685 // Verify that the call instruction has the same arguments as this function
686 // and that they're all either the incoming argument or a cast of the right
688 const CallInst *CI = dyn_cast<CallInst>(I++);
689 if (!CI || !CI->isTailCall() ||
690 CI->getNumArgOperands() != F->arg_size()) return false;
692 for (unsigned i = 0, e = CI->getNumArgOperands(); i != e; ++i) {
693 const Value *V = CI->getArgOperand(i);
694 const Argument *A = dyn_cast<Argument>(V);
696 const BitCastInst *BCI = dyn_cast<BitCastInst>(V);
697 if (!BCI) return false;
698 A = cast<Argument>(BCI->getOperand(0));
700 if (A->getArgNo() != i) return false;
703 // Verify that the terminator is a ret void (if we're void) or a ret of the
704 // call's return, or a ret of a bitcast of the call's return.
705 const Value *RetOp = CI;
706 if (const BitCastInst *BCI = dyn_cast<BitCastInst>(I)) {
708 if (BCI->getOperand(0) != CI) return false;
711 const ReturnInst *RI = dyn_cast<ReturnInst>(I);
712 if (!RI) return false;
713 if (RI->getNumOperands() == 0)
714 return CI->getType()->isVoidTy();
715 return RI->getReturnValue() == CI;
718 bool MergeFunctions::runOnModule(Module &M) {
719 bool Changed = false;
720 TD = getAnalysisIfAvailable<TargetData>();
724 DEBUG(dbgs() << "size: " << M.size() << '\n');
725 LocalChanged = false;
728 // Insert only strong functions and merge them. Strong function merging
729 // always deletes one of them.
730 for (Module::iterator I = M.begin(), E = M.end(); I != E;) {
732 if (!F->isDeclaration() && !F->hasAvailableExternallyLinkage() &&
733 !F->isWeakForLinker() && !IsThunk(F)) {
734 ComparableFunction CF = ComparableFunction(F, TD);
735 LocalChanged |= Insert(FnSet, CF);
739 // Insert only weak functions and merge them. By doing these second we
740 // create thunks to the strong function when possible. When two weak
741 // functions are identical, we create a new strong function with two weak
742 // weak thunks to it which are identical but not mergable.
743 for (Module::iterator I = M.begin(), E = M.end(); I != E;) {
745 if (!F->isDeclaration() && !F->hasAvailableExternallyLinkage() &&
746 F->isWeakForLinker() && !IsThunk(F)) {
747 ComparableFunction CF = ComparableFunction(F, TD);
748 LocalChanged |= Insert(FnSet, CF);
751 Changed |= LocalChanged;
752 } while (LocalChanged);
757 bool DenseMapInfo<ComparableFunction>::isEqual(const ComparableFunction &LHS,
758 const ComparableFunction &RHS) {
759 if (LHS.getFunc() == RHS.getFunc() &&
760 LHS.getHash() == RHS.getHash())
762 if (!LHS.getFunc() || !RHS.getFunc())
764 assert(LHS.getTD() == RHS.getTD() &&
765 "Comparing functions for different targets");
766 return FunctionComparator(LHS.getTD(),
767 LHS.getFunc(), RHS.getFunc()).Compare();