| //===- 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/Analysis/LoopInfo.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); |
| } |
| |
| /// \brief Remaps instructions in \p Blocks using the mapping in \p VMap. |
| void llvm::remapInstructionsInBlocks( |
| const SmallVectorImpl<BasicBlock *> &Blocks, ValueToValueMapTy &VMap) { |
| // Rewrite the code to refer to itself. |
| for (auto *BB : Blocks) |
| for (auto &Inst : *BB) |
| RemapInstruction(&Inst, VMap, |
| RF_NoModuleLevelChanges | RF_IgnoreMissingEntries); |
| } |
| |
| /// \brief Clones a loop \p OrigLoop. Returns the loop and the blocks in \p |
| /// Blocks. |
| /// |
| /// Updates LoopInfo and DominatorTree assuming the loop is dominated by block |
| /// \p LoopDomBB. Insert the new blocks before block specified in \p Before. |
| Loop *llvm::cloneLoopWithPreheader(BasicBlock *Before, BasicBlock *LoopDomBB, |
| Loop *OrigLoop, ValueToValueMapTy &VMap, |
| const Twine &NameSuffix, LoopInfo *LI, |
| DominatorTree *DT, |
| SmallVectorImpl<BasicBlock *> &Blocks) { |
| Function *F = OrigLoop->getHeader()->getParent(); |
| Loop *ParentLoop = OrigLoop->getParentLoop(); |
| |
| Loop *NewLoop = new Loop(); |
| if (ParentLoop) |
| ParentLoop->addChildLoop(NewLoop); |
| else |
| LI->addTopLevelLoop(NewLoop); |
| |
| BasicBlock *OrigPH = OrigLoop->getLoopPreheader(); |
| assert(OrigPH && "No preheader"); |
| BasicBlock *NewPH = CloneBasicBlock(OrigPH, VMap, NameSuffix, F); |
| // To rename the loop PHIs. |
| VMap[OrigPH] = NewPH; |
| Blocks.push_back(NewPH); |
| |
| // Update LoopInfo. |
| if (ParentLoop) |
| ParentLoop->addBasicBlockToLoop(NewPH, *LI); |
| |
| // Update DominatorTree. |
| DT->addNewBlock(NewPH, LoopDomBB); |
| |
| for (BasicBlock *BB : OrigLoop->getBlocks()) { |
| BasicBlock *NewBB = CloneBasicBlock(BB, VMap, NameSuffix, F); |
| VMap[BB] = NewBB; |
| |
| // Update LoopInfo. |
| NewLoop->addBasicBlockToLoop(NewBB, *LI); |
| |
| // Update DominatorTree. |
| BasicBlock *IDomBB = DT->getNode(BB)->getIDom()->getBlock(); |
| DT->addNewBlock(NewBB, cast<BasicBlock>(VMap[IDomBB])); |
| |
| Blocks.push_back(NewBB); |
| } |
| |
| // Move them physically from the end of the block list. |
| F->getBasicBlockList().splice(Before, F->getBasicBlockList(), NewPH); |
| F->getBasicBlockList().splice(Before, F->getBasicBlockList(), |
| NewLoop->getHeader(), F->end()); |
| |
| return NewLoop; |
| } |