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Diffstat (limited to 'contrib/llvm/lib/Transforms/Utils/CloneFunction.cpp')
| -rw-r--r-- | contrib/llvm/lib/Transforms/Utils/CloneFunction.cpp | 722 |
1 files changed, 722 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Transforms/Utils/CloneFunction.cpp b/contrib/llvm/lib/Transforms/Utils/CloneFunction.cpp new file mode 100644 index 0000000..4f8d1df --- /dev/null +++ b/contrib/llvm/lib/Transforms/Utils/CloneFunction.cpp @@ -0,0 +1,722 @@ +//===- CloneFunction.cpp - Clone a function into another function ---------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file implements the CloneFunctionInto interface, which is used as the +// low-level function cloner. This is used by the CloneFunction and function +// inliner to do the dirty work of copying the body of a function around. +// +//===----------------------------------------------------------------------===// + +#include "llvm/Transforms/Utils/Cloning.h" +#include "llvm/ADT/SmallVector.h" +#include "llvm/Analysis/ConstantFolding.h" +#include "llvm/Analysis/InstructionSimplify.h" +#include "llvm/IR/CFG.h" +#include "llvm/IR/Constants.h" +#include "llvm/IR/DebugInfo.h" +#include "llvm/IR/DerivedTypes.h" +#include "llvm/IR/Function.h" +#include "llvm/IR/GlobalVariable.h" +#include "llvm/IR/Instructions.h" +#include "llvm/IR/IntrinsicInst.h" +#include "llvm/IR/LLVMContext.h" +#include "llvm/IR/Metadata.h" +#include "llvm/IR/Module.h" +#include "llvm/Transforms/Utils/BasicBlockUtils.h" +#include "llvm/Transforms/Utils/Local.h" +#include "llvm/Transforms/Utils/ValueMapper.h" +#include <map> +using namespace llvm; + +/// See comments in Cloning.h. +BasicBlock *llvm::CloneBasicBlock(const BasicBlock *BB, + ValueToValueMapTy &VMap, + const Twine &NameSuffix, Function *F, + ClonedCodeInfo *CodeInfo) { + BasicBlock *NewBB = BasicBlock::Create(BB->getContext(), "", F); + if (BB->hasName()) NewBB->setName(BB->getName()+NameSuffix); + + bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false; + + // Loop over all instructions, and copy them over. + for (BasicBlock::const_iterator II = BB->begin(), IE = BB->end(); + II != IE; ++II) { + Instruction *NewInst = II->clone(); + if (II->hasName()) + NewInst->setName(II->getName()+NameSuffix); + NewBB->getInstList().push_back(NewInst); + VMap[II] = NewInst; // Add instruction map to value. + + hasCalls |= (isa<CallInst>(II) && !isa<DbgInfoIntrinsic>(II)); + if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) { + if (isa<ConstantInt>(AI->getArraySize())) + hasStaticAllocas = true; + else + hasDynamicAllocas = true; + } + } + + if (CodeInfo) { + CodeInfo->ContainsCalls |= hasCalls; + CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas; + CodeInfo->ContainsDynamicAllocas |= hasStaticAllocas && + BB != &BB->getParent()->getEntryBlock(); + } + return NewBB; +} + +// Clone OldFunc into NewFunc, transforming the old arguments into references to +// VMap values. +// +void llvm::CloneFunctionInto(Function *NewFunc, const Function *OldFunc, + ValueToValueMapTy &VMap, + bool ModuleLevelChanges, + SmallVectorImpl<ReturnInst*> &Returns, + const char *NameSuffix, ClonedCodeInfo *CodeInfo, + ValueMapTypeRemapper *TypeMapper, + ValueMaterializer *Materializer) { + assert(NameSuffix && "NameSuffix cannot be null!"); + +#ifndef NDEBUG + for (Function::const_arg_iterator I = OldFunc->arg_begin(), + E = OldFunc->arg_end(); I != E; ++I) + assert(VMap.count(I) && "No mapping from source argument specified!"); +#endif + + // Copy all attributes other than those stored in the AttributeSet. We need + // to remap the parameter indices of the AttributeSet. + AttributeSet NewAttrs = NewFunc->getAttributes(); + NewFunc->copyAttributesFrom(OldFunc); + NewFunc->setAttributes(NewAttrs); + + AttributeSet OldAttrs = OldFunc->getAttributes(); + // Clone any argument attributes that are present in the VMap. + for (const Argument &OldArg : OldFunc->args()) + if (Argument *NewArg = dyn_cast<Argument>(VMap[&OldArg])) { + AttributeSet attrs = + OldAttrs.getParamAttributes(OldArg.getArgNo() + 1); + if (attrs.getNumSlots() > 0) + NewArg->addAttr(attrs); + } + + NewFunc->setAttributes( + NewFunc->getAttributes() + .addAttributes(NewFunc->getContext(), AttributeSet::ReturnIndex, + OldAttrs.getRetAttributes()) + .addAttributes(NewFunc->getContext(), AttributeSet::FunctionIndex, + OldAttrs.getFnAttributes())); + + // Loop over all of the basic blocks in the function, cloning them as + // appropriate. Note that we save BE this way in order to handle cloning of + // recursive functions into themselves. + // + for (Function::const_iterator BI = OldFunc->begin(), BE = OldFunc->end(); + BI != BE; ++BI) { + const BasicBlock &BB = *BI; + + // Create a new basic block and copy instructions into it! + BasicBlock *CBB = CloneBasicBlock(&BB, VMap, NameSuffix, NewFunc, CodeInfo); + + // Add basic block mapping. + VMap[&BB] = CBB; + + // It is only legal to clone a function if a block address within that + // function is never referenced outside of the function. Given that, we + // want to map block addresses from the old function to block addresses in + // the clone. (This is different from the generic ValueMapper + // implementation, which generates an invalid blockaddress when + // cloning a function.) + if (BB.hasAddressTaken()) { + Constant *OldBBAddr = BlockAddress::get(const_cast<Function*>(OldFunc), + const_cast<BasicBlock*>(&BB)); + VMap[OldBBAddr] = BlockAddress::get(NewFunc, CBB); + } + + // Note return instructions for the caller. + if (ReturnInst *RI = dyn_cast<ReturnInst>(CBB->getTerminator())) + Returns.push_back(RI); + } + + // Loop over all of the instructions in the function, fixing up operand + // references as we go. This uses VMap to do all the hard work. + for (Function::iterator BB = cast<BasicBlock>(VMap[OldFunc->begin()]), + BE = NewFunc->end(); BB != BE; ++BB) + // Loop over all instructions, fixing each one as we find it... + for (BasicBlock::iterator II = BB->begin(); II != BB->end(); ++II) + RemapInstruction(II, VMap, + ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges, + TypeMapper, Materializer); +} + +// Find the MDNode which corresponds to the subprogram data that described F. +static DISubprogram *FindSubprogram(const Function *F, + DebugInfoFinder &Finder) { + for (DISubprogram *Subprogram : Finder.subprograms()) { + if (Subprogram->describes(F)) + return Subprogram; + } + return nullptr; +} + +// Add an operand to an existing MDNode. The new operand will be added at the +// back of the operand list. +static void AddOperand(DICompileUnit *CU, DISubprogramArray SPs, + Metadata *NewSP) { + SmallVector<Metadata *, 16> NewSPs; + NewSPs.reserve(SPs.size() + 1); + for (auto *SP : SPs) + NewSPs.push_back(SP); + NewSPs.push_back(NewSP); + CU->replaceSubprograms(MDTuple::get(CU->getContext(), NewSPs)); +} + +// Clone the module-level debug info associated with OldFunc. The cloned data +// will point to NewFunc instead. +static void CloneDebugInfoMetadata(Function *NewFunc, const Function *OldFunc, + ValueToValueMapTy &VMap) { + DebugInfoFinder Finder; + Finder.processModule(*OldFunc->getParent()); + + const DISubprogram *OldSubprogramMDNode = FindSubprogram(OldFunc, Finder); + if (!OldSubprogramMDNode) return; + + // Ensure that OldFunc appears in the map. + // (if it's already there it must point to NewFunc anyway) + VMap[OldFunc] = NewFunc; + auto *NewSubprogram = + cast<DISubprogram>(MapMetadata(OldSubprogramMDNode, VMap)); + + for (auto *CU : Finder.compile_units()) { + auto Subprograms = CU->getSubprograms(); + // If the compile unit's function list contains the old function, it should + // also contain the new one. + for (auto *SP : Subprograms) { + if (SP == OldSubprogramMDNode) { + AddOperand(CU, Subprograms, NewSubprogram); + break; + } + } + } +} + +/// Return a copy of the specified function, but without +/// embedding the function into another module. Also, any references specified +/// in the VMap are changed to refer to their mapped value instead of the +/// original one. If any of the arguments to the function are in the VMap, +/// the arguments are deleted from the resultant function. The VMap is +/// updated to include mappings from all of the instructions and basicblocks in +/// the function from their old to new values. +/// +Function *llvm::CloneFunction(const Function *F, ValueToValueMapTy &VMap, + bool ModuleLevelChanges, + ClonedCodeInfo *CodeInfo) { + std::vector<Type*> ArgTypes; + + // The user might be deleting arguments to the function by specifying them in + // the VMap. If so, we need to not add the arguments to the arg ty vector + // + for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end(); + I != E; ++I) + if (VMap.count(I) == 0) // Haven't mapped the argument to anything yet? + ArgTypes.push_back(I->getType()); + + // Create a new function type... + FunctionType *FTy = FunctionType::get(F->getFunctionType()->getReturnType(), + ArgTypes, F->getFunctionType()->isVarArg()); + + // Create the new function... + Function *NewF = Function::Create(FTy, F->getLinkage(), F->getName()); + + // Loop over the arguments, copying the names of the mapped arguments over... + Function::arg_iterator DestI = NewF->arg_begin(); + for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end(); + I != E; ++I) + if (VMap.count(I) == 0) { // Is this argument preserved? + DestI->setName(I->getName()); // Copy the name over... + VMap[I] = DestI++; // Add mapping to VMap + } + + if (ModuleLevelChanges) + CloneDebugInfoMetadata(NewF, F, VMap); + + SmallVector<ReturnInst*, 8> Returns; // Ignore returns cloned. + CloneFunctionInto(NewF, F, VMap, ModuleLevelChanges, Returns, "", CodeInfo); + return NewF; +} + + + +namespace { + /// This is a private class used to implement CloneAndPruneFunctionInto. + struct PruningFunctionCloner { + Function *NewFunc; + const Function *OldFunc; + ValueToValueMapTy &VMap; + bool ModuleLevelChanges; + const char *NameSuffix; + ClonedCodeInfo *CodeInfo; + CloningDirector *Director; + ValueMapTypeRemapper *TypeMapper; + ValueMaterializer *Materializer; + + public: + PruningFunctionCloner(Function *newFunc, const Function *oldFunc, + ValueToValueMapTy &valueMap, bool moduleLevelChanges, + const char *nameSuffix, ClonedCodeInfo *codeInfo, + CloningDirector *Director) + : NewFunc(newFunc), OldFunc(oldFunc), VMap(valueMap), + ModuleLevelChanges(moduleLevelChanges), NameSuffix(nameSuffix), + CodeInfo(codeInfo), Director(Director) { + // These are optional components. The Director may return null. + if (Director) { + TypeMapper = Director->getTypeRemapper(); + Materializer = Director->getValueMaterializer(); + } else { + TypeMapper = nullptr; + Materializer = nullptr; + } + } + + /// The specified block is found to be reachable, clone it and + /// anything that it can reach. + void CloneBlock(const BasicBlock *BB, + BasicBlock::const_iterator StartingInst, + std::vector<const BasicBlock*> &ToClone); + }; +} + +/// The specified block is found to be reachable, clone it and +/// anything that it can reach. +void PruningFunctionCloner::CloneBlock(const BasicBlock *BB, + BasicBlock::const_iterator StartingInst, + std::vector<const BasicBlock*> &ToClone){ + WeakVH &BBEntry = VMap[BB]; + + // Have we already cloned this block? + if (BBEntry) return; + + // Nope, clone it now. + BasicBlock *NewBB; + BBEntry = NewBB = BasicBlock::Create(BB->getContext()); + if (BB->hasName()) NewBB->setName(BB->getName()+NameSuffix); + + // It is only legal to clone a function if a block address within that + // function is never referenced outside of the function. Given that, we + // want to map block addresses from the old function to block addresses in + // the clone. (This is different from the generic ValueMapper + // implementation, which generates an invalid blockaddress when + // cloning a function.) + // + // Note that we don't need to fix the mapping for unreachable blocks; + // the default mapping there is safe. + if (BB->hasAddressTaken()) { + Constant *OldBBAddr = BlockAddress::get(const_cast<Function*>(OldFunc), + const_cast<BasicBlock*>(BB)); + VMap[OldBBAddr] = BlockAddress::get(NewFunc, NewBB); + } + + bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false; + + // Loop over all instructions, and copy them over, DCE'ing as we go. This + // loop doesn't include the terminator. + for (BasicBlock::const_iterator II = StartingInst, IE = --BB->end(); + II != IE; ++II) { + // If the "Director" remaps the instruction, don't clone it. + if (Director) { + CloningDirector::CloningAction Action + = Director->handleInstruction(VMap, II, NewBB); + // If the cloning director says stop, we want to stop everything, not + // just break out of the loop (which would cause the terminator to be + // cloned). The cloning director is responsible for inserting a proper + // terminator into the new basic block in this case. + if (Action == CloningDirector::StopCloningBB) + return; + // If the cloning director says skip, continue to the next instruction. + // In this case, the cloning director is responsible for mapping the + // skipped instruction to some value that is defined in the new + // basic block. + if (Action == CloningDirector::SkipInstruction) + continue; + } + + Instruction *NewInst = II->clone(); + + // Eagerly remap operands to the newly cloned instruction, except for PHI + // nodes for which we defer processing until we update the CFG. + if (!isa<PHINode>(NewInst)) { + RemapInstruction(NewInst, VMap, + ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges, + TypeMapper, Materializer); + + // If we can simplify this instruction to some other value, simply add + // a mapping to that value rather than inserting a new instruction into + // the basic block. + if (Value *V = + SimplifyInstruction(NewInst, BB->getModule()->getDataLayout())) { + // On the off-chance that this simplifies to an instruction in the old + // function, map it back into the new function. + if (Value *MappedV = VMap.lookup(V)) + V = MappedV; + + VMap[II] = V; + delete NewInst; + continue; + } + } + + if (II->hasName()) + NewInst->setName(II->getName()+NameSuffix); + VMap[II] = NewInst; // Add instruction map to value. + NewBB->getInstList().push_back(NewInst); + hasCalls |= (isa<CallInst>(II) && !isa<DbgInfoIntrinsic>(II)); + if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) { + if (isa<ConstantInt>(AI->getArraySize())) + hasStaticAllocas = true; + else + hasDynamicAllocas = true; + } + } + + // Finally, clone over the terminator. + const TerminatorInst *OldTI = BB->getTerminator(); + bool TerminatorDone = false; + if (Director) { + CloningDirector::CloningAction Action + = Director->handleInstruction(VMap, OldTI, NewBB); + // If the cloning director says stop, we want to stop everything, not + // just break out of the loop (which would cause the terminator to be + // cloned). The cloning director is responsible for inserting a proper + // terminator into the new basic block in this case. + if (Action == CloningDirector::StopCloningBB) + return; + if (Action == CloningDirector::CloneSuccessors) { + // If the director says to skip with a terminate instruction, we still + // need to clone this block's successors. + const TerminatorInst *TI = NewBB->getTerminator(); + for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i) + ToClone.push_back(TI->getSuccessor(i)); + return; + } + assert(Action != CloningDirector::SkipInstruction && + "SkipInstruction is not valid for terminators."); + } + if (const BranchInst *BI = dyn_cast<BranchInst>(OldTI)) { + if (BI->isConditional()) { + // If the condition was a known constant in the callee... + ConstantInt *Cond = dyn_cast<ConstantInt>(BI->getCondition()); + // Or is a known constant in the caller... + if (!Cond) { + Value *V = VMap[BI->getCondition()]; + Cond = dyn_cast_or_null<ConstantInt>(V); + } + + // Constant fold to uncond branch! + if (Cond) { + BasicBlock *Dest = BI->getSuccessor(!Cond->getZExtValue()); + VMap[OldTI] = BranchInst::Create(Dest, NewBB); + ToClone.push_back(Dest); + TerminatorDone = true; + } + } + } else if (const SwitchInst *SI = dyn_cast<SwitchInst>(OldTI)) { + // If switching on a value known constant in the caller. + ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition()); + if (!Cond) { // Or known constant after constant prop in the callee... + Value *V = VMap[SI->getCondition()]; + Cond = dyn_cast_or_null<ConstantInt>(V); + } + if (Cond) { // Constant fold to uncond branch! + SwitchInst::ConstCaseIt Case = SI->findCaseValue(Cond); + BasicBlock *Dest = const_cast<BasicBlock*>(Case.getCaseSuccessor()); + VMap[OldTI] = BranchInst::Create(Dest, NewBB); + ToClone.push_back(Dest); + TerminatorDone = true; + } + } + + if (!TerminatorDone) { + Instruction *NewInst = OldTI->clone(); + if (OldTI->hasName()) + NewInst->setName(OldTI->getName()+NameSuffix); + NewBB->getInstList().push_back(NewInst); + VMap[OldTI] = NewInst; // Add instruction map to value. + + // Recursively clone any reachable successor blocks. + const TerminatorInst *TI = BB->getTerminator(); + for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i) + ToClone.push_back(TI->getSuccessor(i)); + } + + if (CodeInfo) { + CodeInfo->ContainsCalls |= hasCalls; + CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas; + CodeInfo->ContainsDynamicAllocas |= hasStaticAllocas && + BB != &BB->getParent()->front(); + } +} + +/// This works like CloneAndPruneFunctionInto, except that it does not clone the +/// entire function. Instead it starts at an instruction provided by the caller +/// and copies (and prunes) only the code reachable from that instruction. +void llvm::CloneAndPruneIntoFromInst(Function *NewFunc, const Function *OldFunc, + const Instruction *StartingInst, + ValueToValueMapTy &VMap, + bool ModuleLevelChanges, + SmallVectorImpl<ReturnInst *> &Returns, + const char *NameSuffix, + ClonedCodeInfo *CodeInfo, + CloningDirector *Director) { + assert(NameSuffix && "NameSuffix cannot be null!"); + + ValueMapTypeRemapper *TypeMapper = nullptr; + ValueMaterializer *Materializer = nullptr; + + if (Director) { + TypeMapper = Director->getTypeRemapper(); + Materializer = Director->getValueMaterializer(); + } + +#ifndef NDEBUG + // If the cloning starts at the begining of the function, verify that + // the function arguments are mapped. + if (!StartingInst) + for (Function::const_arg_iterator II = OldFunc->arg_begin(), + E = OldFunc->arg_end(); II != E; ++II) + assert(VMap.count(II) && "No mapping from source argument specified!"); +#endif + + PruningFunctionCloner PFC(NewFunc, OldFunc, VMap, ModuleLevelChanges, + NameSuffix, CodeInfo, Director); + const BasicBlock *StartingBB; + if (StartingInst) + StartingBB = StartingInst->getParent(); + else { + StartingBB = &OldFunc->getEntryBlock(); + StartingInst = StartingBB->begin(); + } + + // Clone the entry block, and anything recursively reachable from it. + std::vector<const BasicBlock*> CloneWorklist; + PFC.CloneBlock(StartingBB, StartingInst, CloneWorklist); + while (!CloneWorklist.empty()) { + const BasicBlock *BB = CloneWorklist.back(); + CloneWorklist.pop_back(); + PFC.CloneBlock(BB, BB->begin(), CloneWorklist); + } + + // Loop over all of the basic blocks in the old function. If the block was + // reachable, we have cloned it and the old block is now in the value map: + // insert it into the new function in the right order. If not, ignore it. + // + // Defer PHI resolution until rest of function is resolved. + SmallVector<const PHINode*, 16> PHIToResolve; + for (Function::const_iterator BI = OldFunc->begin(), BE = OldFunc->end(); + BI != BE; ++BI) { + Value *V = VMap[BI]; + BasicBlock *NewBB = cast_or_null<BasicBlock>(V); + if (!NewBB) continue; // Dead block. + + // Add the new block to the new function. + NewFunc->getBasicBlockList().push_back(NewBB); + + // Handle PHI nodes specially, as we have to remove references to dead + // blocks. + for (BasicBlock::const_iterator I = BI->begin(), E = BI->end(); I != E; ++I) { + // PHI nodes may have been remapped to non-PHI nodes by the caller or + // during the cloning process. + if (const PHINode *PN = dyn_cast<PHINode>(I)) { + if (isa<PHINode>(VMap[PN])) + PHIToResolve.push_back(PN); + else + break; + } else { + break; + } + } + + // Finally, remap the terminator instructions, as those can't be remapped + // until all BBs are mapped. + RemapInstruction(NewBB->getTerminator(), VMap, + ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges, + TypeMapper, Materializer); + } + + // Defer PHI resolution until rest of function is resolved, PHI resolution + // requires the CFG to be up-to-date. + for (unsigned phino = 0, e = PHIToResolve.size(); phino != e; ) { + const PHINode *OPN = PHIToResolve[phino]; + unsigned NumPreds = OPN->getNumIncomingValues(); + const BasicBlock *OldBB = OPN->getParent(); + BasicBlock *NewBB = cast<BasicBlock>(VMap[OldBB]); + + // Map operands for blocks that are live and remove operands for blocks + // that are dead. + for (; phino != PHIToResolve.size() && + PHIToResolve[phino]->getParent() == OldBB; ++phino) { + OPN = PHIToResolve[phino]; + PHINode *PN = cast<PHINode>(VMap[OPN]); + for (unsigned pred = 0, e = NumPreds; pred != e; ++pred) { + Value *V = VMap[PN->getIncomingBlock(pred)]; + if (BasicBlock *MappedBlock = cast_or_null<BasicBlock>(V)) { + Value *InVal = MapValue(PN->getIncomingValue(pred), + VMap, + ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges); + assert(InVal && "Unknown input value?"); + PN->setIncomingValue(pred, InVal); + PN->setIncomingBlock(pred, MappedBlock); + } else { + PN->removeIncomingValue(pred, false); + --pred, --e; // Revisit the next entry. + } + } + } + + // The loop above has removed PHI entries for those blocks that are dead + // and has updated others. However, if a block is live (i.e. copied over) + // but its terminator has been changed to not go to this block, then our + // phi nodes will have invalid entries. Update the PHI nodes in this + // case. + PHINode *PN = cast<PHINode>(NewBB->begin()); + NumPreds = std::distance(pred_begin(NewBB), pred_end(NewBB)); + if (NumPreds != PN->getNumIncomingValues()) { + assert(NumPreds < PN->getNumIncomingValues()); + // Count how many times each predecessor comes to this block. + std::map<BasicBlock*, unsigned> PredCount; + for (pred_iterator PI = pred_begin(NewBB), E = pred_end(NewBB); + PI != E; ++PI) + --PredCount[*PI]; + + // Figure out how many entries to remove from each PHI. + for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) + ++PredCount[PN->getIncomingBlock(i)]; + + // At this point, the excess predecessor entries are positive in the + // map. Loop over all of the PHIs and remove excess predecessor + // entries. + BasicBlock::iterator I = NewBB->begin(); + for (; (PN = dyn_cast<PHINode>(I)); ++I) { + for (std::map<BasicBlock*, unsigned>::iterator PCI =PredCount.begin(), + E = PredCount.end(); PCI != E; ++PCI) { + BasicBlock *Pred = PCI->first; + for (unsigned NumToRemove = PCI->second; NumToRemove; --NumToRemove) + PN->removeIncomingValue(Pred, false); + } + } + } + + // If the loops above have made these phi nodes have 0 or 1 operand, + // replace them with undef or the input value. We must do this for + // correctness, because 0-operand phis are not valid. + PN = cast<PHINode>(NewBB->begin()); + if (PN->getNumIncomingValues() == 0) { + BasicBlock::iterator I = NewBB->begin(); + BasicBlock::const_iterator OldI = OldBB->begin(); + while ((PN = dyn_cast<PHINode>(I++))) { + Value *NV = UndefValue::get(PN->getType()); + PN->replaceAllUsesWith(NV); + assert(VMap[OldI] == PN && "VMap mismatch"); + VMap[OldI] = NV; + PN->eraseFromParent(); + ++OldI; + } + } + } + + // Make a second pass over the PHINodes now that all of them have been + // remapped into the new function, simplifying the PHINode and performing any + // recursive simplifications exposed. This will transparently update the + // WeakVH in the VMap. Notably, we rely on that so that if we coalesce + // two PHINodes, the iteration over the old PHIs remains valid, and the + // mapping will just map us to the new node (which may not even be a PHI + // node). + for (unsigned Idx = 0, Size = PHIToResolve.size(); Idx != Size; ++Idx) + if (PHINode *PN = dyn_cast<PHINode>(VMap[PHIToResolve[Idx]])) + recursivelySimplifyInstruction(PN); + + // Now that the inlined function body has been fully constructed, go through + // and zap unconditional fall-through branches. This happens all the time when + // specializing code: code specialization turns conditional branches into + // uncond branches, and this code folds them. + Function::iterator Begin = cast<BasicBlock>(VMap[StartingBB]); + Function::iterator I = Begin; + while (I != NewFunc->end()) { + // Check if this block has become dead during inlining or other + // simplifications. Note that the first block will appear dead, as it has + // not yet been wired up properly. + if (I != Begin && (pred_begin(I) == pred_end(I) || + I->getSinglePredecessor() == I)) { + BasicBlock *DeadBB = I++; + DeleteDeadBlock(DeadBB); + continue; + } + + // We need to simplify conditional branches and switches with a constant + // operand. We try to prune these out when cloning, but if the + // simplification required looking through PHI nodes, those are only + // available after forming the full basic block. That may leave some here, + // and we still want to prune the dead code as early as possible. + ConstantFoldTerminator(I); + + BranchInst *BI = dyn_cast<BranchInst>(I->getTerminator()); + if (!BI || BI->isConditional()) { ++I; continue; } + + BasicBlock *Dest = BI->getSuccessor(0); + if (!Dest->getSinglePredecessor()) { + ++I; continue; + } + + // We shouldn't be able to get single-entry PHI nodes here, as instsimplify + // above should have zapped all of them.. + assert(!isa<PHINode>(Dest->begin())); + + // We know all single-entry PHI nodes in the inlined function have been + // removed, so we just need to splice the blocks. + BI->eraseFromParent(); + + // Make all PHI nodes that referred to Dest now refer to I as their source. + Dest->replaceAllUsesWith(I); + + // Move all the instructions in the succ to the pred. + I->getInstList().splice(I->end(), Dest->getInstList()); + + // Remove the dest block. + Dest->eraseFromParent(); + + // Do not increment I, iteratively merge all things this block branches to. + } + + // Make a final pass over the basic blocks from the old function to gather + // any return instructions which survived folding. We have to do this here + // because we can iteratively remove and merge returns above. + for (Function::iterator I = cast<BasicBlock>(VMap[StartingBB]), + E = NewFunc->end(); + I != E; ++I) + if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) + Returns.push_back(RI); +} + + +/// This works exactly like CloneFunctionInto, +/// except that it does some simple constant prop and DCE on the fly. The +/// effect of this is to copy significantly less code in cases where (for +/// example) a function call with constant arguments is inlined, and those +/// constant arguments cause a significant amount of code in the callee to be +/// dead. Since this doesn't produce an exact copy of the input, it can't be +/// used for things like CloneFunction or CloneModule. +void llvm::CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc, + ValueToValueMapTy &VMap, + bool ModuleLevelChanges, + SmallVectorImpl<ReturnInst*> &Returns, + const char *NameSuffix, + ClonedCodeInfo *CodeInfo, + Instruction *TheCall) { + CloneAndPruneIntoFromInst(NewFunc, OldFunc, OldFunc->front().begin(), VMap, + ModuleLevelChanges, Returns, NameSuffix, CodeInfo, + nullptr); +} |
