| //===- 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 implementations. |
| // |
| // * use SCC to cut down on pair-wise comparisons and solve larger cycles. |
| // |
| // The current implementation loops over a pair-wise comparison of all |
| // functions in the program where the two functions in the pair are treated as |
| // assumed to be equal until proven otherwise. We could both use fewer |
| // comparisons and optimize more complex cases if we used strongly connected |
| // components of the call graph. |
| // |
| // * be smarter about bitcast. |
| // |
| // 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 peer through bitcasts without imposing bad |
| // performance properties. |
| // |
| // * don't emit aliases for Mach-O. |
| // |
| // Mach-O doesn't support aliases which means that we must avoid introducing |
| // them in the bitcode on architectures which don't support them, such as |
| // Mac OSX. There's a few approaches to this problem; |
| // a) teach codegen to lower global aliases to thunks on platforms which don't |
| // support them. |
| // b) always emit thunks, and create a separate thunk-to-alias pass which |
| // runs on ELF systems. This has the added benefit of transforming other |
| // thunks such as those produced by a C++ frontend into aliases when legal |
| // to do so. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #define DEBUG_TYPE "mergefunc" |
| #include "llvm/Transforms/IPO.h" |
| #include "llvm/ADT/DenseMap.h" |
| #include "llvm/ADT/FoldingSet.h" |
| #include "llvm/ADT/SmallSet.h" |
| #include "llvm/ADT/Statistic.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/raw_ostream.h" |
| #include "llvm/Target/TargetData.h" |
| #include <map> |
| #include <vector> |
| using namespace llvm; |
| |
| STATISTIC(NumFunctionsMerged, "Number of functions merged"); |
| |
| namespace { |
| class MergeFunctions : public ModulePass { |
| public: |
| static char ID; // Pass identification, replacement for typeid |
| MergeFunctions() : ModulePass(&ID) {} |
| |
| bool runOnModule(Module &M); |
| |
| private: |
| bool isEquivalentGEP(const GetElementPtrInst *GEP1, |
| const GetElementPtrInst *GEP2); |
| |
| bool equals(const BasicBlock *BB1, const BasicBlock *BB2); |
| bool equals(const Function *F, const Function *G); |
| |
| bool compare(const Value *V1, const Value *V2); |
| |
| const Function *LHS, *RHS; |
| typedef DenseMap<const Value *, unsigned long> IDMap; |
| IDMap Map; |
| DenseMap<const Function *, IDMap> Domains; |
| DenseMap<const Function *, unsigned long> DomainCount; |
| TargetData *TD; |
| }; |
| } |
| |
| char MergeFunctions::ID = 0; |
| static RegisterPass<MergeFunctions> X("mergefunc", "Merge Functions"); |
| |
| ModulePass *llvm::createMergeFunctionsPass() { |
| return new MergeFunctions(); |
| } |
| |
| // ===----------------------------------------------------------------------=== |
| // Comparison of functions |
| // ===----------------------------------------------------------------------=== |
| |
| static unsigned long hash(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(); |
| } |
| |
| /// isEquivalentType - any two pointers are equivalent. Otherwise, standard |
| /// type equivalence rules apply. |
| static bool isEquivalentType(const Type *Ty1, const Type *Ty2) { |
| if (Ty1 == Ty2) |
| return true; |
| if (Ty1->getTypeID() != Ty2->getTypeID()) |
| return false; |
| |
| switch(Ty1->getTypeID()) { |
| default: |
| llvm_unreachable("Unknown type!"); |
| // Fall through in Release-Asserts 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::UnionTyID: { |
| const UnionType *UTy1 = cast<UnionType>(Ty1); |
| const UnionType *UTy2 = cast<UnionType>(Ty2); |
| |
| // TODO: we could be fancy with union(A, union(A, B)) === union(A, B), etc. |
| if (UTy1->getNumElements() != UTy2->getNumElements()) |
| return false; |
| |
| for (unsigned i = 0, e = UTy1->getNumElements(); i != e; ++i) { |
| if (!isEquivalentType(UTy1->getElementType(i), UTy2->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: |
| case Type::VectorTyID: { |
| const SequentialType *STy1 = cast<SequentialType>(Ty1); |
| const SequentialType *STy2 = cast<SequentialType>(Ty2); |
| return isEquivalentType(STy1->getElementType(), STy2->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. |
| static bool |
| isEquivalentOperation(const Instruction *I1, const Instruction *I2) { |
| 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; |
| } |
| |
| bool MergeFunctions::isEquivalentGEP(const GetElementPtrInst *GEP1, |
| const GetElementPtrInst *GEP2) { |
| if (TD && GEP1->hasAllConstantIndices() && GEP2->hasAllConstantIndices()) { |
| SmallVector<Value *, 8> Indices1, Indices2; |
| for (GetElementPtrInst::const_op_iterator I = GEP1->idx_begin(), |
| E = GEP1->idx_end(); I != E; ++I) { |
| Indices1.push_back(*I); |
| } |
| for (GetElementPtrInst::const_op_iterator I = GEP2->idx_begin(), |
| E = GEP2->idx_end(); I != E; ++I) { |
| Indices2.push_back(*I); |
| } |
| 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; |
| } |
| |
| // Equivalent types aren't enough. |
| 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 (!compare(GEP1->getOperand(i), GEP2->getOperand(i))) |
| return false; |
| } |
| |
| return true; |
| } |
| |
| bool MergeFunctions::compare(const Value *V1, const Value *V2) { |
| if (V1 == LHS || V1 == RHS) |
| if (V2 == LHS || V2 == RHS) |
| return true; |
| |
| // TODO: constant expressions in terms of LHS and RHS |
| 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(); |
| } |
| |
| // We enumerate constants globally and arguments, basic blocks or |
| // instructions within the function they belong to. |
| const Function *Domain1 = NULL; |
| if (const Argument *A = dyn_cast<Argument>(V1)) { |
| Domain1 = A->getParent(); |
| } else if (const BasicBlock *BB = dyn_cast<BasicBlock>(V1)) { |
| Domain1 = BB->getParent(); |
| } else if (const Instruction *I = dyn_cast<Instruction>(V1)) { |
| Domain1 = I->getParent()->getParent(); |
| } |
| |
| const Function *Domain2 = NULL; |
| if (const Argument *A = dyn_cast<Argument>(V2)) { |
| Domain2 = A->getParent(); |
| } else if (const BasicBlock *BB = dyn_cast<BasicBlock>(V2)) { |
| Domain2 = BB->getParent(); |
| } else if (const Instruction *I = dyn_cast<Instruction>(V2)) { |
| Domain2 = I->getParent()->getParent(); |
| } |
| |
| if (Domain1 != Domain2) |
| if (Domain1 != LHS && Domain1 != RHS) |
| if (Domain2 != LHS && Domain2 != RHS) |
| return false; |
| |
| IDMap &Map1 = Domains[Domain1]; |
| unsigned long &ID1 = Map1[V1]; |
| if (!ID1) |
| ID1 = ++DomainCount[Domain1]; |
| |
| IDMap &Map2 = Domains[Domain2]; |
| unsigned long &ID2 = Map2[V2]; |
| if (!ID2) |
| ID2 = ++DomainCount[Domain2]; |
| |
| return ID1 == ID2; |
| } |
| |
| bool MergeFunctions::equals(const BasicBlock *BB1, const BasicBlock *BB2) { |
| BasicBlock::const_iterator FI = BB1->begin(), FE = BB1->end(); |
| BasicBlock::const_iterator GI = BB2->begin(), GE = BB2->end(); |
| |
| do { |
| if (!compare(FI, GI)) |
| return false; |
| |
| if (isa<GetElementPtrInst>(FI) && isa<GetElementPtrInst>(GI)) { |
| const GetElementPtrInst *GEP1 = cast<GetElementPtrInst>(FI); |
| const GetElementPtrInst *GEP2 = cast<GetElementPtrInst>(GI); |
| |
| if (!compare(GEP1->getPointerOperand(), GEP2->getPointerOperand())) |
| return false; |
| |
| if (!isEquivalentGEP(GEP1, GEP2)) |
| return false; |
| } else { |
| if (!isEquivalentOperation(FI, GI)) |
| return false; |
| |
| for (unsigned i = 0, e = FI->getNumOperands(); i != e; ++i) { |
| Value *OpF = FI->getOperand(i); |
| Value *OpG = GI->getOperand(i); |
| |
| if (!compare(OpF, OpG)) |
| return false; |
| |
| if (OpF->getValueID() != OpG->getValueID() || |
| !isEquivalentType(OpF->getType(), OpG->getType())) |
| return false; |
| } |
| } |
| |
| ++FI, ++GI; |
| } while (FI != FE && GI != GE); |
| |
| return FI == FE && GI == GE; |
| } |
| |
| bool MergeFunctions::equals(const Function *F, const Function *G) { |
| // We need to recheck everything, but check the things that weren't included |
| // in the hash first. |
| |
| if (F->getAttributes() != G->getAttributes()) |
| return false; |
| |
| if (F->hasGC() != G->hasGC()) |
| return false; |
| |
| if (F->hasGC() && F->getGC() != G->getGC()) |
| return false; |
| |
| if (F->hasSection() != G->hasSection()) |
| return false; |
| |
| if (F->hasSection() && F->getSection() != G->getSection()) |
| return false; |
| |
| if (F->isVarArg() != G->isVarArg()) |
| return false; |
| |
| // TODO: if it's internal and only used in direct calls, we could handle this |
| // case too. |
| if (F->getCallingConv() != G->getCallingConv()) |
| return false; |
| |
| if (!isEquivalentType(F->getFunctionType(), G->getFunctionType())) |
| return false; |
| |
| assert(F->arg_size() == G->arg_size() && |
| "Identical functions have a different number of args."); |
| |
| LHS = F; |
| RHS = G; |
| |
| // Visit the arguments so that they get enumerated in the order they're |
| // passed in. |
| for (Function::const_arg_iterator fi = F->arg_begin(), gi = G->arg_begin(), |
| fe = F->arg_end(); fi != fe; ++fi, ++gi) { |
| if (!compare(fi, gi)) |
| llvm_unreachable("Arguments repeat"); |
| } |
| |
| SmallVector<const BasicBlock *, 8> FBBs, GBBs; |
| SmallSet<const BasicBlock *, 128> VisitedBBs; // in terms of F. |
| FBBs.push_back(&F->getEntryBlock()); |
| GBBs.push_back(&G->getEntryBlock()); |
| VisitedBBs.insert(FBBs[0]); |
| while (!FBBs.empty()) { |
| const BasicBlock *FBB = FBBs.pop_back_val(); |
| const BasicBlock *GBB = GBBs.pop_back_val(); |
| if (!compare(FBB, GBB) || !equals(FBB, GBB)) { |
| Domains.clear(); |
| DomainCount.clear(); |
| return false; |
| } |
| const TerminatorInst *FTI = FBB->getTerminator(); |
| const TerminatorInst *GTI = GBB->getTerminator(); |
| assert(FTI->getNumSuccessors() == GTI->getNumSuccessors()); |
| for (unsigned i = 0, e = FTI->getNumSuccessors(); i != e; ++i) { |
| if (!VisitedBBs.insert(FTI->getSuccessor(i))) |
| continue; |
| FBBs.push_back(FTI->getSuccessor(i)); |
| GBBs.push_back(GTI->getSuccessor(i)); |
| } |
| } |
| |
| Domains.clear(); |
| DomainCount.clear(); |
| return true; |
| } |
| |
| // ===----------------------------------------------------------------------=== |
| // Folding of functions |
| // ===----------------------------------------------------------------------=== |
| |
| // Cases: |
| // * F is external strong, G is external strong: |
| // turn G into a thunk to F (1) |
| // * F is external strong, G is external weak: |
| // turn G into a thunk to F (1) |
| // * F is external weak, G is external weak: |
| // unfoldable |
| // * F is external strong, G is internal: |
| // address of G taken: |
| // turn G into a thunk to F (1) |
| // address of G not taken: |
| // make G an alias to F (2) |
| // * F is internal, G is external weak |
| // address of F is taken: |
| // turn G into a thunk to F (1) |
| // address of F is not taken: |
| // make G an alias of F (2) |
| // * F is internal, G is internal: |
| // address of F and G are taken: |
| // turn G into a thunk to F (1) |
| // address of G is not taken: |
| // make G an alias to F (2) |
| // |
| // alias requires linkage == (external,local,weak) fallback to creating a thunk |
| // external means 'externally visible' linkage != (internal,private) |
| // internal means linkage == (internal,private) |
| // weak means linkage mayBeOverridable |
| // being external implies that the address is taken |
| // |
| // 1. turn G into a thunk to F |
| // 2. make G an alias to F |
| |
| enum LinkageCategory { |
| ExternalStrong, |
| ExternalWeak, |
| Internal |
| }; |
| |
| static LinkageCategory categorize(const Function *F) { |
| switch (F->getLinkage()) { |
| case GlobalValue::InternalLinkage: |
| case GlobalValue::PrivateLinkage: |
| case GlobalValue::LinkerPrivateLinkage: |
| return Internal; |
| |
| case GlobalValue::WeakAnyLinkage: |
| case GlobalValue::WeakODRLinkage: |
| case GlobalValue::ExternalWeakLinkage: |
| case GlobalValue::LinkerWeakLinkage: |
| return ExternalWeak; |
| |
| case GlobalValue::ExternalLinkage: |
| case GlobalValue::AvailableExternallyLinkage: |
| case GlobalValue::LinkOnceAnyLinkage: |
| case GlobalValue::LinkOnceODRLinkage: |
| case GlobalValue::AppendingLinkage: |
| case GlobalValue::DLLImportLinkage: |
| case GlobalValue::DLLExportLinkage: |
| case GlobalValue::CommonLinkage: |
| return ExternalStrong; |
| } |
| |
| llvm_unreachable("Unknown LinkageType."); |
| return ExternalWeak; |
| } |
| |
| static void ThunkGToF(Function *F, Function *G) { |
| 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); |
| } |
| } |
| |
| Function *NewG = Function::Create(G->getFunctionType(), G->getLinkage(), "", |
| G->getParent()); |
| BasicBlock *BB = BasicBlock::Create(F->getContext(), "", NewG); |
| |
| 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) { |
| if (FFTy->getParamType(i) == AI->getType()) { |
| Args.push_back(AI); |
| } else { |
| Args.push_back(new BitCastInst(AI, FFTy->getParamType(i), "", BB)); |
| } |
| ++i; |
| } |
| |
| CallInst *CI = CallInst::Create(F, Args.begin(), Args.end(), "", BB); |
| CI->setTailCall(); |
| CI->setCallingConv(F->getCallingConv()); |
| if (NewG->getReturnType()->isVoidTy()) { |
| ReturnInst::Create(F->getContext(), BB); |
| } else if (CI->getType() != NewG->getReturnType()) { |
| Value *BCI = new BitCastInst(CI, NewG->getReturnType(), "", BB); |
| ReturnInst::Create(F->getContext(), BCI, BB); |
| } else { |
| ReturnInst::Create(F->getContext(), CI, BB); |
| } |
| |
| NewG->copyAttributesFrom(G); |
| NewG->takeName(G); |
| G->replaceAllUsesWith(NewG); |
| G->eraseFromParent(); |
| } |
| |
| static void AliasGToF(Function *F, Function *G) { |
| if (!G->hasExternalLinkage() && !G->hasLocalLinkage() && !G->hasWeakLinkage()) |
| return ThunkGToF(F, G); |
| |
| GlobalAlias *GA = new GlobalAlias( |
| G->getType(), G->getLinkage(), "", |
| ConstantExpr::getBitCast(F, G->getType()), G->getParent()); |
| F->setAlignment(std::max(F->getAlignment(), G->getAlignment())); |
| GA->takeName(G); |
| GA->setVisibility(G->getVisibility()); |
| G->replaceAllUsesWith(GA); |
| G->eraseFromParent(); |
| } |
| |
| static bool fold(std::vector<Function *> &FnVec, unsigned i, unsigned j) { |
| Function *F = FnVec[i]; |
| Function *G = FnVec[j]; |
| |
| LinkageCategory catF = categorize(F); |
| LinkageCategory catG = categorize(G); |
| |
| if (catF == ExternalWeak || (catF == Internal && catG == ExternalStrong)) { |
| std::swap(FnVec[i], FnVec[j]); |
| std::swap(F, G); |
| std::swap(catF, catG); |
| } |
| |
| switch (catF) { |
| case ExternalStrong: |
| switch (catG) { |
| case ExternalStrong: |
| case ExternalWeak: |
| ThunkGToF(F, G); |
| break; |
| case Internal: |
| if (G->hasAddressTaken()) |
| ThunkGToF(F, G); |
| else |
| AliasGToF(F, G); |
| break; |
| } |
| break; |
| |
| case ExternalWeak: { |
| assert(catG == ExternalWeak); |
| |
| // Make them both thunks to the same internal function. |
| F->setAlignment(std::max(F->getAlignment(), G->getAlignment())); |
| Function *H = Function::Create(F->getFunctionType(), F->getLinkage(), "", |
| F->getParent()); |
| H->copyAttributesFrom(F); |
| H->takeName(F); |
| F->replaceAllUsesWith(H); |
| |
| ThunkGToF(F, G); |
| ThunkGToF(F, H); |
| |
| F->setLinkage(GlobalValue::InternalLinkage); |
| } break; |
| |
| case Internal: |
| switch (catG) { |
| case ExternalStrong: |
| llvm_unreachable(0); |
| // fall-through |
| case ExternalWeak: |
| if (F->hasAddressTaken()) |
| ThunkGToF(F, G); |
| else |
| AliasGToF(F, G); |
| break; |
| case Internal: { |
| bool addrTakenF = F->hasAddressTaken(); |
| bool addrTakenG = G->hasAddressTaken(); |
| if (!addrTakenF && addrTakenG) { |
| std::swap(FnVec[i], FnVec[j]); |
| std::swap(F, G); |
| std::swap(addrTakenF, addrTakenG); |
| } |
| |
| if (addrTakenF && addrTakenG) { |
| ThunkGToF(F, G); |
| } else { |
| assert(!addrTakenG); |
| AliasGToF(F, G); |
| } |
| } break; |
| } break; |
| } |
| |
| ++NumFunctionsMerged; |
| return true; |
| } |
| |
| // ===----------------------------------------------------------------------=== |
| // Pass definition |
| // ===----------------------------------------------------------------------=== |
| |
| bool MergeFunctions::runOnModule(Module &M) { |
| bool Changed = false; |
| |
| std::map<unsigned long, std::vector<Function *> > FnMap; |
| |
| for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) { |
| if (F->isDeclaration()) |
| continue; |
| |
| FnMap[hash(F)].push_back(F); |
| } |
| |
| TD = getAnalysisIfAvailable<TargetData>(); |
| |
| bool LocalChanged; |
| do { |
| LocalChanged = false; |
| DEBUG(dbgs() << "size: " << FnMap.size() << "\n"); |
| for (std::map<unsigned long, std::vector<Function *> >::iterator |
| I = FnMap.begin(), E = FnMap.end(); I != E; ++I) { |
| std::vector<Function *> &FnVec = I->second; |
| DEBUG(dbgs() << "hash (" << I->first << "): " << FnVec.size() << "\n"); |
| |
| for (int i = 0, e = FnVec.size(); i != e; ++i) { |
| for (int j = i + 1; j != e; ++j) { |
| bool isEqual = equals(FnVec[i], FnVec[j]); |
| |
| DEBUG(dbgs() << " " << FnVec[i]->getName() |
| << (isEqual ? " == " : " != ") |
| << FnVec[j]->getName() << "\n"); |
| |
| if (isEqual) { |
| if (fold(FnVec, i, j)) { |
| LocalChanged = true; |
| FnVec.erase(FnVec.begin() + j); |
| --j, --e; |
| } |
| } |
| } |
| } |
| |
| } |
| Changed |= LocalChanged; |
| } while (LocalChanged); |
| |
| return Changed; |
| } |