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Diffstat (limited to 'llvm/lib/Transforms/Utils/CloneFunction.cpp')
| -rw-r--r-- | llvm/lib/Transforms/Utils/CloneFunction.cpp | 878 |
1 files changed, 878 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/Utils/CloneFunction.cpp b/llvm/lib/Transforms/Utils/CloneFunction.cpp new file mode 100644 index 0000000000000..75e8963303c24 --- /dev/null +++ b/llvm/lib/Transforms/Utils/CloneFunction.cpp @@ -0,0 +1,878 @@ +//===- CloneFunction.cpp - Clone a function into another function ---------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// +// +// 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/ADT/SetVector.h" +#include "llvm/ADT/SmallVector.h" +#include "llvm/Analysis/ConstantFolding.h" +#include "llvm/Analysis/DomTreeUpdater.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/Cloning.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, + DebugInfoFinder *DIFinder) { + DenseMap<const MDNode *, MDNode *> Cache; + BasicBlock *NewBB = BasicBlock::Create(BB->getContext(), "", F); + if (BB->hasName()) + NewBB->setName(BB->getName() + NameSuffix); + + bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false; + Module *TheModule = F ? F->getParent() : nullptr; + + // Loop over all instructions, and copy them over. + for (const Instruction &I : *BB) { + if (DIFinder && TheModule) + DIFinder->processInstruction(*TheModule, I); + + Instruction *NewInst = I.clone(); + if (I.hasName()) + NewInst->setName(I.getName() + NameSuffix); + NewBB->getInstList().push_back(NewInst); + VMap[&I] = NewInst; // Add instruction map to value. + + hasCalls |= (isa<CallInst>(I) && !isa<DbgInfoIntrinsic>(I)); + if (const AllocaInst *AI = dyn_cast<AllocaInst>(&I)) { + 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 (const Argument &I : OldFunc->args()) + assert(VMap.count(&I) && "No mapping from source argument specified!"); +#endif + + // Copy all attributes other than those stored in the AttributeList. We need + // to remap the parameter indices of the AttributeList. + AttributeList NewAttrs = NewFunc->getAttributes(); + NewFunc->copyAttributesFrom(OldFunc); + NewFunc->setAttributes(NewAttrs); + + // Fix up the personality function that got copied over. + if (OldFunc->hasPersonalityFn()) + NewFunc->setPersonalityFn( + MapValue(OldFunc->getPersonalityFn(), VMap, + ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges, + TypeMapper, Materializer)); + + SmallVector<AttributeSet, 4> NewArgAttrs(NewFunc->arg_size()); + AttributeList 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])) { + NewArgAttrs[NewArg->getArgNo()] = + OldAttrs.getParamAttributes(OldArg.getArgNo()); + } + } + + NewFunc->setAttributes( + AttributeList::get(NewFunc->getContext(), OldAttrs.getFnAttributes(), + OldAttrs.getRetAttributes(), NewArgAttrs)); + + bool MustCloneSP = + OldFunc->getParent() && OldFunc->getParent() == NewFunc->getParent(); + DISubprogram *SP = OldFunc->getSubprogram(); + if (SP) { + assert(!MustCloneSP || ModuleLevelChanges); + // Add mappings for some DebugInfo nodes that we don't want duplicated + // even if they're distinct. + auto &MD = VMap.MD(); + MD[SP->getUnit()].reset(SP->getUnit()); + MD[SP->getType()].reset(SP->getType()); + MD[SP->getFile()].reset(SP->getFile()); + // If we're not cloning into the same module, no need to clone the + // subprogram + if (!MustCloneSP) + MD[SP].reset(SP); + } + + SmallVector<std::pair<unsigned, MDNode *>, 1> MDs; + OldFunc->getAllMetadata(MDs); + for (auto MD : MDs) { + NewFunc->addMetadata( + MD.first, + *MapMetadata(MD.second, VMap, + ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges, + TypeMapper, Materializer)); + } + + // When we remap instructions, we want to avoid duplicating inlined + // DISubprograms, so record all subprograms we find as we duplicate + // instructions and then freeze them in the MD map. + // We also record information about dbg.value and dbg.declare to avoid + // duplicating the types. + DebugInfoFinder DIFinder; + + // 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, + ModuleLevelChanges ? &DIFinder : nullptr); + + // 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); + } + + for (DISubprogram *ISP : DIFinder.subprograms()) + if (ISP != SP) + VMap.MD()[ISP].reset(ISP); + + for (DICompileUnit *CU : DIFinder.compile_units()) + VMap.MD()[CU].reset(CU); + + for (DIType *Type : DIFinder.types()) + VMap.MD()[Type].reset(Type); + + // 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->front()])->getIterator(), + BE = NewFunc->end(); + BB != BE; ++BB) + // Loop over all instructions, fixing each one as we find it... + for (Instruction &II : *BB) + RemapInstruction(&II, VMap, + ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges, + TypeMapper, Materializer); + + // Register all DICompileUnits of the old parent module in the new parent module + auto* OldModule = OldFunc->getParent(); + auto* NewModule = NewFunc->getParent(); + if (OldModule && NewModule && OldModule != NewModule && DIFinder.compile_unit_count()) { + auto* NMD = NewModule->getOrInsertNamedMetadata("llvm.dbg.cu"); + // Avoid multiple insertions of the same DICompileUnit to NMD. + SmallPtrSet<const void*, 8> Visited; + for (auto* Operand : NMD->operands()) + Visited.insert(Operand); + for (auto* Unit : DIFinder.compile_units()) + // VMap.MD()[Unit] == Unit + if (Visited.insert(Unit).second) + NMD->addOperand(Unit); + } +} + +/// Return a copy of the specified function and add it to that function's +/// 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(Function *F, ValueToValueMapTy &VMap, + 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 (const Argument &I : F->args()) + 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->getAddressSpace(), + F->getName(), F->getParent()); + + // Loop over the arguments, copying the names of the mapped arguments over... + Function::arg_iterator DestI = NewF->arg_begin(); + for (const Argument & I : F->args()) + if (VMap.count(&I) == 0) { // Is this argument preserved? + DestI->setName(I.getName()); // Copy the name over... + VMap[&I] = &*DestI++; // Add mapping to VMap + } + + SmallVector<ReturnInst*, 8> Returns; // Ignore returns cloned. + CloneFunctionInto(NewF, F, VMap, F->getSubprogram() != nullptr, 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; + + public: + PruningFunctionCloner(Function *newFunc, const Function *oldFunc, + ValueToValueMapTy &valueMap, bool moduleLevelChanges, + const char *nameSuffix, ClonedCodeInfo *codeInfo) + : NewFunc(newFunc), OldFunc(oldFunc), VMap(valueMap), + ModuleLevelChanges(moduleLevelChanges), NameSuffix(nameSuffix), + CodeInfo(codeInfo) {} + + /// 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){ + WeakTrackingVH &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) { + + 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); + + // 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 (NewFunc != OldFunc) + if (Value *MappedV = VMap.lookup(V)) + V = MappedV; + + if (!NewInst->mayHaveSideEffects()) { + VMap[&*II] = V; + NewInst->deleteValue(); + 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 (CodeInfo) + if (auto CS = ImmutableCallSite(&*II)) + if (CS.hasOperandBundles()) + CodeInfo->OperandBundleCallSites.push_back(NewInst); + + if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) { + if (isa<ConstantInt>(AI->getArraySize())) + hasStaticAllocas = true; + else + hasDynamicAllocas = true; + } + } + + // Finally, clone over the terminator. + const Instruction *OldTI = BB->getTerminator(); + bool TerminatorDone = false; + 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.lookup(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.lookup(SI->getCondition()); + Cond = dyn_cast_or_null<ConstantInt>(V); + } + if (Cond) { // Constant fold to uncond branch! + SwitchInst::ConstCaseHandle 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. + + if (CodeInfo) + if (auto CS = ImmutableCallSite(OldTI)) + if (CS.hasOperandBundles()) + CodeInfo->OperandBundleCallSites.push_back(NewInst); + + // Recursively clone any reachable successor blocks. + const Instruction *TI = BB->getTerminator(); + for (const BasicBlock *Succ : successors(TI)) + ToClone.push_back(Succ); + } + + 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) { + assert(NameSuffix && "NameSuffix cannot be null!"); + + ValueMapTypeRemapper *TypeMapper = nullptr; + ValueMaterializer *Materializer = nullptr; + +#ifndef NDEBUG + // If the cloning starts at the beginning of the function, verify that + // the function arguments are mapped. + if (!StartingInst) + for (const Argument &II : OldFunc->args()) + assert(VMap.count(&II) && "No mapping from source argument specified!"); +#endif + + PruningFunctionCloner PFC(NewFunc, OldFunc, VMap, ModuleLevelChanges, + NameSuffix, CodeInfo); + const BasicBlock *StartingBB; + if (StartingInst) + StartingBB = StartingInst->getParent(); + else { + StartingBB = &OldFunc->getEntryBlock(); + StartingInst = &StartingBB->front(); + } + + // Clone the entry block, and anything recursively reachable from it. + std::vector<const BasicBlock*> CloneWorklist; + PFC.CloneBlock(StartingBB, StartingInst->getIterator(), 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 (const BasicBlock &BI : *OldFunc) { + Value *V = VMap.lookup(&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 (const PHINode &PN : BI.phis()) { + // PHI nodes may have been remapped to non-PHI nodes by the caller or + // during the cloning process. + if (isa<PHINode>(VMap[&PN])) + PHIToResolve.push_back(&PN); + 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.lookup(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; // Revisit the next entry. + --e; + } + } + } + + // 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 = pred_size(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 (const auto &PCI : PredCount) { + 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 + // WeakTrackingVH 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). + const DataLayout &DL = NewFunc->getParent()->getDataLayout(); + SmallSetVector<const Value *, 8> Worklist; + for (unsigned Idx = 0, Size = PHIToResolve.size(); Idx != Size; ++Idx) + if (isa<PHINode>(VMap[PHIToResolve[Idx]])) + Worklist.insert(PHIToResolve[Idx]); + + // Note that we must test the size on each iteration, the worklist can grow. + for (unsigned Idx = 0; Idx != Worklist.size(); ++Idx) { + const Value *OrigV = Worklist[Idx]; + auto *I = dyn_cast_or_null<Instruction>(VMap.lookup(OrigV)); + if (!I) + continue; + + // Skip over non-intrinsic callsites, we don't want to remove any nodes from + // the CGSCC. + CallSite CS = CallSite(I); + if (CS && CS.getCalledFunction() && !CS.getCalledFunction()->isIntrinsic()) + continue; + + // See if this instruction simplifies. + Value *SimpleV = SimplifyInstruction(I, DL); + if (!SimpleV) + continue; + + // Stash away all the uses of the old instruction so we can check them for + // recursive simplifications after a RAUW. This is cheaper than checking all + // uses of To on the recursive step in most cases. + for (const User *U : OrigV->users()) + Worklist.insert(cast<Instruction>(U)); + + // Replace the instruction with its simplified value. + I->replaceAllUsesWith(SimpleV); + + // If the original instruction had no side effects, remove it. + if (isInstructionTriviallyDead(I)) + I->eraseFromParent(); + else + VMap[OrigV] = I; + } + + // 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])->getIterator(); + Function::iterator I = Begin; + while (I != NewFunc->end()) { + // 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. + // + // Do the folding before we check if the block is dead since we want code + // like + // bb: + // br i1 undef, label %bb, label %bb + // to be simplified to + // bb: + // br label %bb + // before we call I->getSinglePredecessor(). + ConstantFoldTerminator(&*I); + + // 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; + } + + 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])->getIterator(), + 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().front(), VMap, + ModuleLevelChanges, Returns, NameSuffix, CodeInfo); +} + +/// 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_IgnoreMissingLocals); +} + +/// 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(); + DenseMap<Loop *, Loop *> LMap; + + Loop *NewLoop = LI->AllocateLoop(); + LMap[OrigLoop] = NewLoop; + 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 (Loop *CurLoop : OrigLoop->getLoopsInPreorder()) { + Loop *&NewLoop = LMap[CurLoop]; + if (!NewLoop) { + NewLoop = LI->AllocateLoop(); + + // Establish the parent/child relationship. + Loop *OrigParent = CurLoop->getParentLoop(); + assert(OrigParent && "Could not find the original parent loop"); + Loop *NewParentLoop = LMap[OrigParent]; + assert(NewParentLoop && "Could not find the new parent loop"); + + NewParentLoop->addChildLoop(NewLoop); + } + } + + for (BasicBlock *BB : OrigLoop->getBlocks()) { + Loop *CurLoop = LI->getLoopFor(BB); + Loop *&NewLoop = LMap[CurLoop]; + assert(NewLoop && "Expecting new loop to be allocated"); + + BasicBlock *NewBB = CloneBasicBlock(BB, VMap, NameSuffix, F); + VMap[BB] = NewBB; + + // Update LoopInfo. + NewLoop->addBasicBlockToLoop(NewBB, *LI); + if (BB == CurLoop->getHeader()) + NewLoop->moveToHeader(NewBB); + + // Add DominatorTree node. After seeing all blocks, update to correct + // IDom. + DT->addNewBlock(NewBB, NewPH); + + Blocks.push_back(NewBB); + } + + for (BasicBlock *BB : OrigLoop->getBlocks()) { + // Update DominatorTree. + BasicBlock *IDomBB = DT->getNode(BB)->getIDom()->getBlock(); + DT->changeImmediateDominator(cast<BasicBlock>(VMap[BB]), + cast<BasicBlock>(VMap[IDomBB])); + } + + // Move them physically from the end of the block list. + F->getBasicBlockList().splice(Before->getIterator(), F->getBasicBlockList(), + NewPH); + F->getBasicBlockList().splice(Before->getIterator(), F->getBasicBlockList(), + NewLoop->getHeader()->getIterator(), F->end()); + + return NewLoop; +} + +/// Duplicate non-Phi instructions from the beginning of block up to +/// StopAt instruction into a split block between BB and its predecessor. +BasicBlock *llvm::DuplicateInstructionsInSplitBetween( + BasicBlock *BB, BasicBlock *PredBB, Instruction *StopAt, + ValueToValueMapTy &ValueMapping, DomTreeUpdater &DTU) { + + assert(count(successors(PredBB), BB) == 1 && + "There must be a single edge between PredBB and BB!"); + // We are going to have to map operands from the original BB block to the new + // copy of the block 'NewBB'. If there are PHI nodes in BB, evaluate them to + // account for entry from PredBB. + BasicBlock::iterator BI = BB->begin(); + for (; PHINode *PN = dyn_cast<PHINode>(BI); ++BI) + ValueMapping[PN] = PN->getIncomingValueForBlock(PredBB); + + BasicBlock *NewBB = SplitEdge(PredBB, BB); + NewBB->setName(PredBB->getName() + ".split"); + Instruction *NewTerm = NewBB->getTerminator(); + + // FIXME: SplitEdge does not yet take a DTU, so we include the split edge + // in the update set here. + DTU.applyUpdates({{DominatorTree::Delete, PredBB, BB}, + {DominatorTree::Insert, PredBB, NewBB}, + {DominatorTree::Insert, NewBB, BB}}); + + // Clone the non-phi instructions of BB into NewBB, keeping track of the + // mapping and using it to remap operands in the cloned instructions. + // Stop once we see the terminator too. This covers the case where BB's + // terminator gets replaced and StopAt == BB's terminator. + for (; StopAt != &*BI && BB->getTerminator() != &*BI; ++BI) { + Instruction *New = BI->clone(); + New->setName(BI->getName()); + New->insertBefore(NewTerm); + ValueMapping[&*BI] = New; + + // Remap operands to patch up intra-block references. + for (unsigned i = 0, e = New->getNumOperands(); i != e; ++i) + if (Instruction *Inst = dyn_cast<Instruction>(New->getOperand(i))) { + auto I = ValueMapping.find(Inst); + if (I != ValueMapping.end()) + New->setOperand(i, I->second); + } + } + + return NewBB; +} |