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+//===- MergeFunctions.cpp - Merge identical functions ---------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass looks for equivalent functions that are mergable and folds them.
+//
+// A hash is computed from the function, based on its type and number of
+// basic blocks.
+//
+// Once all hashes are computed, we perform an expensive equality comparison
+// on each function pair. This takes n^2/2 comparisons per bucket, so it's
+// important that the hash function be high quality. The equality comparison
+// iterates through each instruction in each basic block.
+//
+// When a match is found the functions are folded. If both functions are
+// overridable, we move the functionality into a new internal function and
+// leave two overridable thunks to it.
+//
+//===----------------------------------------------------------------------===//
+//
+// Future work:
+//
+// * virtual functions.
+//
+// Many functions have their address taken by the virtual function table for
+// the object they belong to. However, as long as it's only used for a lookup
+// and call, this is irrelevant, and we'd like to fold such functions.
+//
+// * switch from n^2 pair-wise comparisons to an n-way comparison for each
+// bucket.
+//
+// * be smarter about bitcasts.
+//
+// In order to fold functions, we will sometimes add either bitcast instructions
+// or bitcast constant expressions. Unfortunately, this can confound further
+// analysis since the two functions differ where one has a bitcast and the
+// other doesn't. We should learn to look through bitcasts.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "mergefunc"
+#include "llvm/Transforms/IPO.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/FoldingSet.h"
+#include "llvm/ADT/SmallSet.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/Constants.h"
+#include "llvm/InlineAsm.h"
+#include "llvm/Instructions.h"
+#include "llvm/LLVMContext.h"
+#include "llvm/Module.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/CallSite.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/IRBuilder.h"
+#include "llvm/Support/ValueHandle.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetData.h"
+#include <vector>
+using namespace llvm;
+
+STATISTIC(NumFunctionsMerged, "Number of functions merged");
+
+namespace {
+ /// MergeFunctions finds functions which will generate identical machine code,
+ /// by considering all pointer types to be equivalent. Once identified,
+ /// MergeFunctions will fold them by replacing a call to one to a call to a
+ /// bitcast of the other.
+ ///
+ class MergeFunctions : public ModulePass {
+ public:
+ static char ID;
+ MergeFunctions() : ModulePass(ID) {}
+
+ bool runOnModule(Module &M);
+
+ private:
+ /// MergeTwoFunctions - Merge two equivalent functions. Upon completion, G
+ /// may be deleted, or may be converted into a thunk. In either case, it
+ /// should never be visited again.
+ void MergeTwoFunctions(Function *F, Function *G) const;
+
+ /// WriteThunk - Replace G with a simple tail call to bitcast(F). Also
+ /// replace direct uses of G with bitcast(F).
+ void WriteThunk(Function *F, Function *G) const;
+
+ TargetData *TD;
+ };
+}
+
+char MergeFunctions::ID = 0;
+INITIALIZE_PASS(MergeFunctions, "mergefunc", "Merge Functions", false, false);
+
+ModulePass *llvm::createMergeFunctionsPass() {
+ return new MergeFunctions();
+}
+
+namespace {
+/// FunctionComparator - Compares two functions to determine whether or not
+/// they will generate machine code with the same behaviour. TargetData is
+/// used if available. The comparator always fails conservatively (erring on the
+/// side of claiming that two functions are different).
+class FunctionComparator {
+public:
+ FunctionComparator(const TargetData *TD, const Function *F1,
+ const Function *F2)
+ : F1(F1), F2(F2), TD(TD), IDMap1Count(0), IDMap2Count(0) {}
+
+ /// Compare - test whether the two functions have equivalent behaviour.
+ bool Compare();
+
+private:
+ /// Compare - test whether two basic blocks have equivalent behaviour.
+ bool Compare(const BasicBlock *BB1, const BasicBlock *BB2);
+
+ /// Enumerate - Assign or look up previously assigned numbers for the two
+ /// values, and return whether the numbers are equal. Numbers are assigned in
+ /// the order visited.
+ bool Enumerate(const Value *V1, const Value *V2);
+
+ /// isEquivalentOperation - Compare two Instructions for equivalence, similar
+ /// to Instruction::isSameOperationAs but with modifications to the type
+ /// comparison.
+ bool isEquivalentOperation(const Instruction *I1,
+ const Instruction *I2) const;
+
+ /// isEquivalentGEP - Compare two GEPs for equivalent pointer arithmetic.
+ bool isEquivalentGEP(const GEPOperator *GEP1, const GEPOperator *GEP2);
+ bool isEquivalentGEP(const GetElementPtrInst *GEP1,
+ const GetElementPtrInst *GEP2) {
+ return isEquivalentGEP(cast<GEPOperator>(GEP1), cast<GEPOperator>(GEP2));
+ }
+
+ /// isEquivalentType - Compare two Types, treating all pointer types as equal.
+ bool isEquivalentType(const Type *Ty1, const Type *Ty2) const;
+
+ // The two functions undergoing comparison.
+ const Function *F1, *F2;
+
+ const TargetData *TD;
+
+ typedef DenseMap<const Value *, unsigned long> IDMap;
+ IDMap Map1, Map2;
+ unsigned long IDMap1Count, IDMap2Count;
+};
+}
+
+/// isEquivalentType - any two pointers in the same address space are
+/// equivalent. Otherwise, standard type equivalence rules apply.
+bool FunctionComparator::isEquivalentType(const Type *Ty1,
+ const Type *Ty2) const {
+ if (Ty1 == Ty2)
+ return true;
+ if (Ty1->getTypeID() != Ty2->getTypeID())
+ return false;
+
+ switch(Ty1->getTypeID()) {
+ default:
+ llvm_unreachable("Unknown type!");
+ // Fall through in Release mode.
+ case Type::IntegerTyID:
+ case Type::OpaqueTyID:
+ // Ty1 == Ty2 would have returned true earlier.
+ return false;
+
+ case Type::VoidTyID:
+ case Type::FloatTyID:
+ case Type::DoubleTyID:
+ case Type::X86_FP80TyID:
+ case Type::FP128TyID:
+ case Type::PPC_FP128TyID:
+ case Type::LabelTyID:
+ case Type::MetadataTyID:
+ return true;
+
+ case Type::PointerTyID: {
+ const PointerType *PTy1 = cast<PointerType>(Ty1);
+ const PointerType *PTy2 = cast<PointerType>(Ty2);
+ return PTy1->getAddressSpace() == PTy2->getAddressSpace();
+ }
+
+ case Type::StructTyID: {
+ const StructType *STy1 = cast<StructType>(Ty1);
+ const StructType *STy2 = cast<StructType>(Ty2);
+ if (STy1->getNumElements() != STy2->getNumElements())
+ return false;
+
+ if (STy1->isPacked() != STy2->isPacked())
+ return false;
+
+ for (unsigned i = 0, e = STy1->getNumElements(); i != e; ++i) {
+ if (!isEquivalentType(STy1->getElementType(i), STy2->getElementType(i)))
+ return false;
+ }
+ return true;
+ }
+
+ case Type::FunctionTyID: {
+ const FunctionType *FTy1 = cast<FunctionType>(Ty1);
+ const FunctionType *FTy2 = cast<FunctionType>(Ty2);
+ if (FTy1->getNumParams() != FTy2->getNumParams() ||
+ FTy1->isVarArg() != FTy2->isVarArg())
+ return false;
+
+ if (!isEquivalentType(FTy1->getReturnType(), FTy2->getReturnType()))
+ return false;
+
+ for (unsigned i = 0, e = FTy1->getNumParams(); i != e; ++i) {
+ if (!isEquivalentType(FTy1->getParamType(i), FTy2->getParamType(i)))
+ return false;
+ }
+ return true;
+ }
+
+ case Type::ArrayTyID: {
+ const ArrayType *ATy1 = cast<ArrayType>(Ty1);
+ const ArrayType *ATy2 = cast<ArrayType>(Ty2);
+ return ATy1->getNumElements() == ATy2->getNumElements() &&
+ isEquivalentType(ATy1->getElementType(), ATy2->getElementType());
+ }
+
+ case Type::VectorTyID: {
+ const VectorType *VTy1 = cast<VectorType>(Ty1);
+ const VectorType *VTy2 = cast<VectorType>(Ty2);
+ return VTy1->getNumElements() == VTy2->getNumElements() &&
+ isEquivalentType(VTy1->getElementType(), VTy2->getElementType());
+ }
+ }
+}
+
+/// isEquivalentOperation - determine whether the two operations are the same
+/// except that pointer-to-A and pointer-to-B are equivalent. This should be
+/// kept in sync with Instruction::isSameOperationAs.
+bool FunctionComparator::isEquivalentOperation(const Instruction *I1,
+ const Instruction *I2) const {
+ if (I1->getOpcode() != I2->getOpcode() ||
+ I1->getNumOperands() != I2->getNumOperands() ||
+ !isEquivalentType(I1->getType(), I2->getType()) ||
+ !I1->hasSameSubclassOptionalData(I2))
+ return false;
+
+ // We have two instructions of identical opcode and #operands. Check to see
+ // if all operands are the same type
+ for (unsigned i = 0, e = I1->getNumOperands(); i != e; ++i)
+ if (!isEquivalentType(I1->getOperand(i)->getType(),
+ I2->getOperand(i)->getType()))
+ return false;
+
+ // Check special state that is a part of some instructions.
+ if (const LoadInst *LI = dyn_cast<LoadInst>(I1))
+ return LI->isVolatile() == cast<LoadInst>(I2)->isVolatile() &&
+ LI->getAlignment() == cast<LoadInst>(I2)->getAlignment();
+ if (const StoreInst *SI = dyn_cast<StoreInst>(I1))
+ return SI->isVolatile() == cast<StoreInst>(I2)->isVolatile() &&
+ SI->getAlignment() == cast<StoreInst>(I2)->getAlignment();
+ if (const CmpInst *CI = dyn_cast<CmpInst>(I1))
+ return CI->getPredicate() == cast<CmpInst>(I2)->getPredicate();
+ if (const CallInst *CI = dyn_cast<CallInst>(I1))
+ return CI->isTailCall() == cast<CallInst>(I2)->isTailCall() &&
+ CI->getCallingConv() == cast<CallInst>(I2)->getCallingConv() &&
+ CI->getAttributes().getRawPointer() ==
+ cast<CallInst>(I2)->getAttributes().getRawPointer();
+ if (const InvokeInst *CI = dyn_cast<InvokeInst>(I1))
+ return CI->getCallingConv() == cast<InvokeInst>(I2)->getCallingConv() &&
+ CI->getAttributes().getRawPointer() ==
+ cast<InvokeInst>(I2)->getAttributes().getRawPointer();
+ if (const InsertValueInst *IVI = dyn_cast<InsertValueInst>(I1)) {
+ if (IVI->getNumIndices() != cast<InsertValueInst>(I2)->getNumIndices())
+ return false;
+ for (unsigned i = 0, e = IVI->getNumIndices(); i != e; ++i)
+ if (IVI->idx_begin()[i] != cast<InsertValueInst>(I2)->idx_begin()[i])
+ return false;
+ return true;
+ }
+ if (const ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(I1)) {
+ if (EVI->getNumIndices() != cast<ExtractValueInst>(I2)->getNumIndices())
+ return false;
+ for (unsigned i = 0, e = EVI->getNumIndices(); i != e; ++i)
+ if (EVI->idx_begin()[i] != cast<ExtractValueInst>(I2)->idx_begin()[i])
+ return false;
+ return true;
+ }
+
+ return true;
+}
+
+/// isEquivalentGEP - determine whether two GEP operations perform the same
+/// underlying arithmetic.
+bool FunctionComparator::isEquivalentGEP(const GEPOperator *GEP1,
+ const GEPOperator *GEP2) {
+ // When we have target data, we can reduce the GEP down to the value in bytes
+ // added to the address.
+ if (TD && GEP1->hasAllConstantIndices() && GEP2->hasAllConstantIndices()) {
+ SmallVector<Value *, 8> Indices1(GEP1->idx_begin(), GEP1->idx_end());
+ SmallVector<Value *, 8> Indices2(GEP2->idx_begin(), GEP2->idx_end());
+ uint64_t Offset1 = TD->getIndexedOffset(GEP1->getPointerOperandType(),
+ Indices1.data(), Indices1.size());
+ uint64_t Offset2 = TD->getIndexedOffset(GEP2->getPointerOperandType(),
+ Indices2.data(), Indices2.size());
+ return Offset1 == Offset2;
+ }
+
+ if (GEP1->getPointerOperand()->getType() !=
+ GEP2->getPointerOperand()->getType())
+ return false;
+
+ if (GEP1->getNumOperands() != GEP2->getNumOperands())
+ return false;
+
+ for (unsigned i = 0, e = GEP1->getNumOperands(); i != e; ++i) {
+ if (!Enumerate(GEP1->getOperand(i), GEP2->getOperand(i)))
+ return false;
+ }
+
+ return true;
+}
+
+/// Enumerate - Compare two values used by the two functions under pair-wise
+/// comparison. If this is the first time the values are seen, they're added to
+/// the mapping so that we will detect mismatches on next use.
+bool FunctionComparator::Enumerate(const Value *V1, const Value *V2) {
+ // Check for function @f1 referring to itself and function @f2 referring to
+ // itself, or referring to each other, or both referring to either of them.
+ // They're all equivalent if the two functions are otherwise equivalent.
+ if (V1 == F1 && V2 == F2)
+ return true;
+ if (V1 == F2 && V2 == F1)
+ return true;
+
+ // TODO: constant expressions with GEP or references to F1 or F2.
+ if (isa<Constant>(V1))
+ return V1 == V2;
+
+ if (isa<InlineAsm>(V1) && isa<InlineAsm>(V2)) {
+ const InlineAsm *IA1 = cast<InlineAsm>(V1);
+ const InlineAsm *IA2 = cast<InlineAsm>(V2);
+ return IA1->getAsmString() == IA2->getAsmString() &&
+ IA1->getConstraintString() == IA2->getConstraintString();
+ }
+
+ unsigned long &ID1 = Map1[V1];
+ if (!ID1)
+ ID1 = ++IDMap1Count;
+
+ unsigned long &ID2 = Map2[V2];
+ if (!ID2)
+ ID2 = ++IDMap2Count;
+
+ return ID1 == ID2;
+}
+
+/// Compare - test whether two basic blocks have equivalent behaviour.
+bool FunctionComparator::Compare(const BasicBlock *BB1, const BasicBlock *BB2) {
+ BasicBlock::const_iterator F1I = BB1->begin(), F1E = BB1->end();
+ BasicBlock::const_iterator F2I = BB2->begin(), F2E = BB2->end();
+
+ do {
+ if (!Enumerate(F1I, F2I))
+ return false;
+
+ if (const GetElementPtrInst *GEP1 = dyn_cast<GetElementPtrInst>(F1I)) {
+ const GetElementPtrInst *GEP2 = dyn_cast<GetElementPtrInst>(F2I);
+ if (!GEP2)
+ return false;
+
+ if (!Enumerate(GEP1->getPointerOperand(), GEP2->getPointerOperand()))
+ return false;
+
+ if (!isEquivalentGEP(GEP1, GEP2))
+ return false;
+ } else {
+ if (!isEquivalentOperation(F1I, F2I))
+ return false;
+
+ assert(F1I->getNumOperands() == F2I->getNumOperands());
+ for (unsigned i = 0, e = F1I->getNumOperands(); i != e; ++i) {
+ Value *OpF1 = F1I->getOperand(i);
+ Value *OpF2 = F2I->getOperand(i);
+
+ if (!Enumerate(OpF1, OpF2))
+ return false;
+
+ if (OpF1->getValueID() != OpF2->getValueID() ||
+ !isEquivalentType(OpF1->getType(), OpF2->getType()))
+ return false;
+ }
+ }
+
+ ++F1I, ++F2I;
+ } while (F1I != F1E && F2I != F2E);
+
+ return F1I == F1E && F2I == F2E;
+}
+
+/// Compare - test whether the two functions have equivalent behaviour.
+bool FunctionComparator::Compare() {
+ // We need to recheck everything, but check the things that weren't included
+ // in the hash first.
+
+ if (F1->getAttributes() != F2->getAttributes())
+ return false;
+
+ if (F1->hasGC() != F2->hasGC())
+ return false;
+
+ if (F1->hasGC() && F1->getGC() != F2->getGC())
+ return false;
+
+ if (F1->hasSection() != F2->hasSection())
+ return false;
+
+ if (F1->hasSection() && F1->getSection() != F2->getSection())
+ return false;
+
+ if (F1->isVarArg() != F2->isVarArg())
+ return false;
+
+ // TODO: if it's internal and only used in direct calls, we could handle this
+ // case too.
+ if (F1->getCallingConv() != F2->getCallingConv())
+ return false;
+
+ if (!isEquivalentType(F1->getFunctionType(), F2->getFunctionType()))
+ return false;
+
+ assert(F1->arg_size() == F2->arg_size() &&
+ "Identical functions have a different number of args.");
+
+ // Visit the arguments so that they get enumerated in the order they're
+ // passed in.
+ for (Function::const_arg_iterator f1i = F1->arg_begin(),
+ f2i = F2->arg_begin(), f1e = F1->arg_end(); f1i != f1e; ++f1i, ++f2i) {
+ if (!Enumerate(f1i, f2i))
+ llvm_unreachable("Arguments repeat");
+ }
+
+ // We do a CFG-ordered walk since the actual ordering of the blocks in the
+ // linked list is immaterial. Our walk starts at the entry block for both
+ // functions, then takes each block from each terminator in order. As an
+ // artifact, this also means that unreachable blocks are ignored.
+ SmallVector<const BasicBlock *, 8> F1BBs, F2BBs;
+ SmallSet<const BasicBlock *, 128> VisitedBBs; // in terms of F1.
+
+ F1BBs.push_back(&F1->getEntryBlock());
+ F2BBs.push_back(&F2->getEntryBlock());
+
+ VisitedBBs.insert(F1BBs[0]);
+ while (!F1BBs.empty()) {
+ const BasicBlock *F1BB = F1BBs.pop_back_val();
+ const BasicBlock *F2BB = F2BBs.pop_back_val();
+
+ if (!Enumerate(F1BB, F2BB) || !Compare(F1BB, F2BB))
+ return false;
+
+ const TerminatorInst *F1TI = F1BB->getTerminator();
+ const TerminatorInst *F2TI = F2BB->getTerminator();
+
+ assert(F1TI->getNumSuccessors() == F2TI->getNumSuccessors());
+ for (unsigned i = 0, e = F1TI->getNumSuccessors(); i != e; ++i) {
+ if (!VisitedBBs.insert(F1TI->getSuccessor(i)))
+ continue;
+
+ F1BBs.push_back(F1TI->getSuccessor(i));
+ F2BBs.push_back(F2TI->getSuccessor(i));
+ }
+ }
+ return true;
+}
+
+/// WriteThunk - Replace G with a simple tail call to bitcast(F). Also replace
+/// direct uses of G with bitcast(F).
+void MergeFunctions::WriteThunk(Function *F, Function *G) const {
+ if (!G->mayBeOverridden()) {
+ // Redirect direct callers of G to F.
+ Constant *BitcastF = ConstantExpr::getBitCast(F, G->getType());
+ for (Value::use_iterator UI = G->use_begin(), UE = G->use_end();
+ UI != UE;) {
+ Value::use_iterator TheIter = UI;
+ ++UI;
+ CallSite CS(*TheIter);
+ if (CS && CS.isCallee(TheIter))
+ TheIter.getUse().set(BitcastF);
+ }
+ }
+
+ // If G was internal then we may have replaced all uses if G with F. If so,
+ // stop here and delete G. There's no need for a thunk.
+ if (G->hasLocalLinkage() && G->use_empty()) {
+ G->eraseFromParent();
+ return;
+ }
+
+ Function *NewG = Function::Create(G->getFunctionType(), G->getLinkage(), "",
+ G->getParent());
+ BasicBlock *BB = BasicBlock::Create(F->getContext(), "", NewG);
+ IRBuilder<false> Builder(BB);
+
+ SmallVector<Value *, 16> Args;
+ unsigned i = 0;
+ const FunctionType *FFTy = F->getFunctionType();
+ for (Function::arg_iterator AI = NewG->arg_begin(), AE = NewG->arg_end();
+ AI != AE; ++AI) {
+ Args.push_back(Builder.CreateBitCast(AI, FFTy->getParamType(i)));
+ ++i;
+ }
+
+ CallInst *CI = Builder.CreateCall(F, Args.begin(), Args.end());
+ CI->setTailCall();
+ CI->setCallingConv(F->getCallingConv());
+ if (NewG->getReturnType()->isVoidTy()) {
+ Builder.CreateRetVoid();
+ } else {
+ Builder.CreateRet(Builder.CreateBitCast(CI, NewG->getReturnType()));
+ }
+
+ NewG->copyAttributesFrom(G);
+ NewG->takeName(G);
+ G->replaceAllUsesWith(NewG);
+ G->eraseFromParent();
+}
+
+/// MergeTwoFunctions - Merge two equivalent functions. Upon completion,
+/// Function G is deleted.
+void MergeFunctions::MergeTwoFunctions(Function *F, Function *G) const {
+ if (F->isWeakForLinker()) {
+ assert(G->isWeakForLinker());
+
+ // Make them both thunks to the same internal function.
+ Function *H = Function::Create(F->getFunctionType(), F->getLinkage(), "",
+ F->getParent());
+ H->copyAttributesFrom(F);
+ H->takeName(F);
+ F->replaceAllUsesWith(H);
+
+ unsigned MaxAlignment = std::max(G->getAlignment(), H->getAlignment());
+
+ WriteThunk(F, G);
+ WriteThunk(F, H);
+
+ F->setAlignment(MaxAlignment);
+ F->setLinkage(GlobalValue::InternalLinkage);
+ } else {
+ WriteThunk(F, G);
+ }
+
+ ++NumFunctionsMerged;
+}
+
+static unsigned ProfileFunction(const Function *F) {
+ const FunctionType *FTy = F->getFunctionType();
+
+ FoldingSetNodeID ID;
+ ID.AddInteger(F->size());
+ ID.AddInteger(F->getCallingConv());
+ ID.AddBoolean(F->hasGC());
+ ID.AddBoolean(FTy->isVarArg());
+ ID.AddInteger(FTy->getReturnType()->getTypeID());
+ for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
+ ID.AddInteger(FTy->getParamType(i)->getTypeID());
+ return ID.ComputeHash();
+}
+
+class ComparableFunction {
+public:
+ ComparableFunction(Function *Func, TargetData *TD)
+ : Func(Func), Hash(ProfileFunction(Func)), TD(TD) {}
+
+ AssertingVH<Function> const Func;
+ const unsigned Hash;
+ TargetData * const TD;
+};
+
+struct MergeFunctionsEqualityInfo {
+ static ComparableFunction *getEmptyKey() {
+ return reinterpret_cast<ComparableFunction*>(0);
+ }
+ static ComparableFunction *getTombstoneKey() {
+ return reinterpret_cast<ComparableFunction*>(-1);
+ }
+ static unsigned getHashValue(const ComparableFunction *CF) {
+ return CF->Hash;
+ }
+ static bool isEqual(const ComparableFunction *LHS,
+ const ComparableFunction *RHS) {
+ if (LHS == RHS)
+ return true;
+ if (LHS == getEmptyKey() || LHS == getTombstoneKey() ||
+ RHS == getEmptyKey() || RHS == getTombstoneKey())
+ return false;
+ assert(LHS->TD == RHS->TD && "Comparing functions for different targets");
+ return FunctionComparator(LHS->TD, LHS->Func, RHS->Func).Compare();
+ }
+};
+
+bool MergeFunctions::runOnModule(Module &M) {
+ typedef DenseSet<ComparableFunction *, MergeFunctionsEqualityInfo> FnSetType;
+
+ bool Changed = false;
+ TD = getAnalysisIfAvailable<TargetData>();
+
+ std::vector<Function *> Funcs;
+ for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
+ if (!F->isDeclaration() && !F->hasAvailableExternallyLinkage())
+ Funcs.push_back(F);
+ }
+
+ bool LocalChanged;
+ do {
+ LocalChanged = false;
+
+ FnSetType FnSet;
+ for (unsigned i = 0, e = Funcs.size(); i != e;) {
+ Function *F = Funcs[i];
+ ComparableFunction *NewF = new ComparableFunction(F, TD);
+ std::pair<FnSetType::iterator, bool> Result = FnSet.insert(NewF);
+ if (!Result.second) {
+ ComparableFunction *&OldF = *Result.first;
+ assert(OldF && "Expected a hash collision");
+
+ // NewF will be deleted in favour of OldF unless NewF is strong and
+ // OldF is weak in which case swap them to keep the strong definition.
+
+ if (OldF->Func->isWeakForLinker() && !NewF->Func->isWeakForLinker())
+ std::swap(OldF, NewF);
+
+ DEBUG(dbgs() << " " << OldF->Func->getName() << " == "
+ << NewF->Func->getName() << '\n');
+
+ Funcs.erase(Funcs.begin() + i);
+ --e;
+
+ Function *DeleteF = NewF->Func;
+ delete NewF;
+ MergeTwoFunctions(OldF->Func, DeleteF);
+ LocalChanged = true;
+ Changed = true;
+ } else {
+ ++i;
+ }
+ }
+ DeleteContainerPointers(FnSet);
+ } while (LocalChanged);
+
+ return Changed;
+}
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