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Diffstat (limited to 'contrib/llvm/lib/Transforms/Utils/InlineFunction.cpp')
| -rw-r--r-- | contrib/llvm/lib/Transforms/Utils/InlineFunction.cpp | 1419 |
1 files changed, 1419 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Transforms/Utils/InlineFunction.cpp b/contrib/llvm/lib/Transforms/Utils/InlineFunction.cpp new file mode 100644 index 0000000..2a86eb5 --- /dev/null +++ b/contrib/llvm/lib/Transforms/Utils/InlineFunction.cpp @@ -0,0 +1,1419 @@ +//===- InlineFunction.cpp - Code to perform function inlining -------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file implements inlining of a function into a call site, resolving +// parameters and the return value as appropriate. +// +//===----------------------------------------------------------------------===// + +#include "llvm/Transforms/Utils/Cloning.h" +#include "llvm/ADT/SmallSet.h" +#include "llvm/ADT/SmallVector.h" +#include "llvm/ADT/SetVector.h" +#include "llvm/ADT/StringExtras.h" +#include "llvm/Analysis/AliasAnalysis.h" +#include "llvm/Analysis/AssumptionCache.h" +#include "llvm/Analysis/CallGraph.h" +#include "llvm/Analysis/CaptureTracking.h" +#include "llvm/Analysis/InstructionSimplify.h" +#include "llvm/Analysis/ValueTracking.h" +#include "llvm/IR/Attributes.h" +#include "llvm/IR/CallSite.h" +#include "llvm/IR/CFG.h" +#include "llvm/IR/Constants.h" +#include "llvm/IR/DataLayout.h" +#include "llvm/IR/DebugInfo.h" +#include "llvm/IR/DerivedTypes.h" +#include "llvm/IR/Dominators.h" +#include "llvm/IR/IRBuilder.h" +#include "llvm/IR/Instructions.h" +#include "llvm/IR/IntrinsicInst.h" +#include "llvm/IR/Intrinsics.h" +#include "llvm/IR/MDBuilder.h" +#include "llvm/IR/Module.h" +#include "llvm/Transforms/Utils/Local.h" +#include "llvm/Support/CommandLine.h" +#include <algorithm> +using namespace llvm; + +static cl::opt<bool> +EnableNoAliasConversion("enable-noalias-to-md-conversion", cl::init(true), + cl::Hidden, + cl::desc("Convert noalias attributes to metadata during inlining.")); + +static cl::opt<bool> +PreserveAlignmentAssumptions("preserve-alignment-assumptions-during-inlining", + cl::init(true), cl::Hidden, + cl::desc("Convert align attributes to assumptions during inlining.")); + +bool llvm::InlineFunction(CallInst *CI, InlineFunctionInfo &IFI, + bool InsertLifetime) { + return InlineFunction(CallSite(CI), IFI, InsertLifetime); +} +bool llvm::InlineFunction(InvokeInst *II, InlineFunctionInfo &IFI, + bool InsertLifetime) { + return InlineFunction(CallSite(II), IFI, InsertLifetime); +} + +namespace { + /// A class for recording information about inlining through an invoke. + class InvokeInliningInfo { + BasicBlock *OuterResumeDest; ///< Destination of the invoke's unwind. + BasicBlock *InnerResumeDest; ///< Destination for the callee's resume. + LandingPadInst *CallerLPad; ///< LandingPadInst associated with the invoke. + PHINode *InnerEHValuesPHI; ///< PHI for EH values from landingpad insts. + SmallVector<Value*, 8> UnwindDestPHIValues; + + public: + InvokeInliningInfo(InvokeInst *II) + : OuterResumeDest(II->getUnwindDest()), InnerResumeDest(nullptr), + CallerLPad(nullptr), InnerEHValuesPHI(nullptr) { + // If there are PHI nodes in the unwind destination block, we need to keep + // track of which values came into them from the invoke before removing + // the edge from this block. + llvm::BasicBlock *InvokeBB = II->getParent(); + BasicBlock::iterator I = OuterResumeDest->begin(); + for (; isa<PHINode>(I); ++I) { + // Save the value to use for this edge. + PHINode *PHI = cast<PHINode>(I); + UnwindDestPHIValues.push_back(PHI->getIncomingValueForBlock(InvokeBB)); + } + + CallerLPad = cast<LandingPadInst>(I); + } + + /// getOuterResumeDest - The outer unwind destination is the target of + /// unwind edges introduced for calls within the inlined function. + BasicBlock *getOuterResumeDest() const { + return OuterResumeDest; + } + + BasicBlock *getInnerResumeDest(); + + LandingPadInst *getLandingPadInst() const { return CallerLPad; } + + /// forwardResume - Forward the 'resume' instruction to the caller's landing + /// pad block. When the landing pad block has only one predecessor, this is + /// a simple branch. When there is more than one predecessor, we need to + /// split the landing pad block after the landingpad instruction and jump + /// to there. + void forwardResume(ResumeInst *RI, + SmallPtrSetImpl<LandingPadInst*> &InlinedLPads); + + /// addIncomingPHIValuesFor - Add incoming-PHI values to the unwind + /// destination block for the given basic block, using the values for the + /// original invoke's source block. + void addIncomingPHIValuesFor(BasicBlock *BB) const { + addIncomingPHIValuesForInto(BB, OuterResumeDest); + } + + void addIncomingPHIValuesForInto(BasicBlock *src, BasicBlock *dest) const { + BasicBlock::iterator I = dest->begin(); + for (unsigned i = 0, e = UnwindDestPHIValues.size(); i != e; ++i, ++I) { + PHINode *phi = cast<PHINode>(I); + phi->addIncoming(UnwindDestPHIValues[i], src); + } + } + }; +} + +/// getInnerResumeDest - Get or create a target for the branch from ResumeInsts. +BasicBlock *InvokeInliningInfo::getInnerResumeDest() { + if (InnerResumeDest) return InnerResumeDest; + + // Split the landing pad. + BasicBlock::iterator SplitPoint = CallerLPad; ++SplitPoint; + InnerResumeDest = + OuterResumeDest->splitBasicBlock(SplitPoint, + OuterResumeDest->getName() + ".body"); + + // The number of incoming edges we expect to the inner landing pad. + const unsigned PHICapacity = 2; + + // Create corresponding new PHIs for all the PHIs in the outer landing pad. + BasicBlock::iterator InsertPoint = InnerResumeDest->begin(); + BasicBlock::iterator I = OuterResumeDest->begin(); + for (unsigned i = 0, e = UnwindDestPHIValues.size(); i != e; ++i, ++I) { + PHINode *OuterPHI = cast<PHINode>(I); + PHINode *InnerPHI = PHINode::Create(OuterPHI->getType(), PHICapacity, + OuterPHI->getName() + ".lpad-body", + InsertPoint); + OuterPHI->replaceAllUsesWith(InnerPHI); + InnerPHI->addIncoming(OuterPHI, OuterResumeDest); + } + + // Create a PHI for the exception values. + InnerEHValuesPHI = PHINode::Create(CallerLPad->getType(), PHICapacity, + "eh.lpad-body", InsertPoint); + CallerLPad->replaceAllUsesWith(InnerEHValuesPHI); + InnerEHValuesPHI->addIncoming(CallerLPad, OuterResumeDest); + + // All done. + return InnerResumeDest; +} + +/// forwardResume - Forward the 'resume' instruction to the caller's landing pad +/// block. When the landing pad block has only one predecessor, this is a simple +/// branch. When there is more than one predecessor, we need to split the +/// landing pad block after the landingpad instruction and jump to there. +void InvokeInliningInfo::forwardResume(ResumeInst *RI, + SmallPtrSetImpl<LandingPadInst*> &InlinedLPads) { + BasicBlock *Dest = getInnerResumeDest(); + BasicBlock *Src = RI->getParent(); + + BranchInst::Create(Dest, Src); + + // Update the PHIs in the destination. They were inserted in an order which + // makes this work. + addIncomingPHIValuesForInto(Src, Dest); + + InnerEHValuesPHI->addIncoming(RI->getOperand(0), Src); + RI->eraseFromParent(); +} + +/// HandleCallsInBlockInlinedThroughInvoke - When we inline a basic block into +/// an invoke, we have to turn all of the calls that can throw into +/// invokes. This function analyze BB to see if there are any calls, and if so, +/// it rewrites them to be invokes that jump to InvokeDest and fills in the PHI +/// nodes in that block with the values specified in InvokeDestPHIValues. +static void HandleCallsInBlockInlinedThroughInvoke(BasicBlock *BB, + InvokeInliningInfo &Invoke) { + for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) { + Instruction *I = BBI++; + + // We only need to check for function calls: inlined invoke + // instructions require no special handling. + CallInst *CI = dyn_cast<CallInst>(I); + + // If this call cannot unwind, don't convert it to an invoke. + // Inline asm calls cannot throw. + if (!CI || CI->doesNotThrow() || isa<InlineAsm>(CI->getCalledValue())) + continue; + + // Convert this function call into an invoke instruction. First, split the + // basic block. + BasicBlock *Split = BB->splitBasicBlock(CI, CI->getName()+".noexc"); + + // Delete the unconditional branch inserted by splitBasicBlock + BB->getInstList().pop_back(); + + // Create the new invoke instruction. + ImmutableCallSite CS(CI); + SmallVector<Value*, 8> InvokeArgs(CS.arg_begin(), CS.arg_end()); + InvokeInst *II = InvokeInst::Create(CI->getCalledValue(), Split, + Invoke.getOuterResumeDest(), + InvokeArgs, CI->getName(), BB); + II->setDebugLoc(CI->getDebugLoc()); + II->setCallingConv(CI->getCallingConv()); + II->setAttributes(CI->getAttributes()); + + // Make sure that anything using the call now uses the invoke! This also + // updates the CallGraph if present, because it uses a WeakVH. + CI->replaceAllUsesWith(II); + + // Delete the original call + Split->getInstList().pop_front(); + + // Update any PHI nodes in the exceptional block to indicate that there is + // now a new entry in them. + Invoke.addIncomingPHIValuesFor(BB); + return; + } +} + +/// HandleInlinedInvoke - If we inlined an invoke site, we need to convert calls +/// in the body of the inlined function into invokes. +/// +/// II is the invoke instruction being inlined. FirstNewBlock is the first +/// block of the inlined code (the last block is the end of the function), +/// and InlineCodeInfo is information about the code that got inlined. +static void HandleInlinedInvoke(InvokeInst *II, BasicBlock *FirstNewBlock, + ClonedCodeInfo &InlinedCodeInfo) { + BasicBlock *InvokeDest = II->getUnwindDest(); + + Function *Caller = FirstNewBlock->getParent(); + + // The inlined code is currently at the end of the function, scan from the + // start of the inlined code to its end, checking for stuff we need to + // rewrite. + InvokeInliningInfo Invoke(II); + + // Get all of the inlined landing pad instructions. + SmallPtrSet<LandingPadInst*, 16> InlinedLPads; + for (Function::iterator I = FirstNewBlock, E = Caller->end(); I != E; ++I) + if (InvokeInst *II = dyn_cast<InvokeInst>(I->getTerminator())) + InlinedLPads.insert(II->getLandingPadInst()); + + // Append the clauses from the outer landing pad instruction into the inlined + // landing pad instructions. + LandingPadInst *OuterLPad = Invoke.getLandingPadInst(); + for (LandingPadInst *InlinedLPad : InlinedLPads) { + unsigned OuterNum = OuterLPad->getNumClauses(); + InlinedLPad->reserveClauses(OuterNum); + for (unsigned OuterIdx = 0; OuterIdx != OuterNum; ++OuterIdx) + InlinedLPad->addClause(OuterLPad->getClause(OuterIdx)); + if (OuterLPad->isCleanup()) + InlinedLPad->setCleanup(true); + } + + for (Function::iterator BB = FirstNewBlock, E = Caller->end(); BB != E; ++BB){ + if (InlinedCodeInfo.ContainsCalls) + HandleCallsInBlockInlinedThroughInvoke(BB, Invoke); + + // Forward any resumes that are remaining here. + if (ResumeInst *RI = dyn_cast<ResumeInst>(BB->getTerminator())) + Invoke.forwardResume(RI, InlinedLPads); + } + + // Now that everything is happy, we have one final detail. The PHI nodes in + // the exception destination block still have entries due to the original + // invoke instruction. Eliminate these entries (which might even delete the + // PHI node) now. + InvokeDest->removePredecessor(II->getParent()); +} + +/// CloneAliasScopeMetadata - When inlining a function that contains noalias +/// scope metadata, this metadata needs to be cloned so that the inlined blocks +/// have different "unqiue scopes" at every call site. Were this not done, then +/// aliasing scopes from a function inlined into a caller multiple times could +/// not be differentiated (and this would lead to miscompiles because the +/// non-aliasing property communicated by the metadata could have +/// call-site-specific control dependencies). +static void CloneAliasScopeMetadata(CallSite CS, ValueToValueMapTy &VMap) { + const Function *CalledFunc = CS.getCalledFunction(); + SetVector<const MDNode *> MD; + + // Note: We could only clone the metadata if it is already used in the + // caller. I'm omitting that check here because it might confuse + // inter-procedural alias analysis passes. We can revisit this if it becomes + // an efficiency or overhead problem. + + for (Function::const_iterator I = CalledFunc->begin(), IE = CalledFunc->end(); + I != IE; ++I) + for (BasicBlock::const_iterator J = I->begin(), JE = I->end(); J != JE; ++J) { + if (const MDNode *M = J->getMetadata(LLVMContext::MD_alias_scope)) + MD.insert(M); + if (const MDNode *M = J->getMetadata(LLVMContext::MD_noalias)) + MD.insert(M); + } + + if (MD.empty()) + return; + + // Walk the existing metadata, adding the complete (perhaps cyclic) chain to + // the set. + SmallVector<const Metadata *, 16> Queue(MD.begin(), MD.end()); + while (!Queue.empty()) { + const MDNode *M = cast<MDNode>(Queue.pop_back_val()); + for (unsigned i = 0, ie = M->getNumOperands(); i != ie; ++i) + if (const MDNode *M1 = dyn_cast<MDNode>(M->getOperand(i))) + if (MD.insert(M1)) + Queue.push_back(M1); + } + + // Now we have a complete set of all metadata in the chains used to specify + // the noalias scopes and the lists of those scopes. + SmallVector<MDNode *, 16> DummyNodes; + DenseMap<const MDNode *, TrackingMDNodeRef> MDMap; + for (SetVector<const MDNode *>::iterator I = MD.begin(), IE = MD.end(); + I != IE; ++I) { + MDNode *Dummy = MDNode::getTemporary(CalledFunc->getContext(), None); + DummyNodes.push_back(Dummy); + MDMap[*I].reset(Dummy); + } + + // Create new metadata nodes to replace the dummy nodes, replacing old + // metadata references with either a dummy node or an already-created new + // node. + for (SetVector<const MDNode *>::iterator I = MD.begin(), IE = MD.end(); + I != IE; ++I) { + SmallVector<Metadata *, 4> NewOps; + for (unsigned i = 0, ie = (*I)->getNumOperands(); i != ie; ++i) { + const Metadata *V = (*I)->getOperand(i); + if (const MDNode *M = dyn_cast<MDNode>(V)) + NewOps.push_back(MDMap[M]); + else + NewOps.push_back(const_cast<Metadata *>(V)); + } + + MDNode *NewM = MDNode::get(CalledFunc->getContext(), NewOps); + MDNodeFwdDecl *TempM = cast<MDNodeFwdDecl>(MDMap[*I]); + + TempM->replaceAllUsesWith(NewM); + } + + // Now replace the metadata in the new inlined instructions with the + // repacements from the map. + for (ValueToValueMapTy::iterator VMI = VMap.begin(), VMIE = VMap.end(); + VMI != VMIE; ++VMI) { + if (!VMI->second) + continue; + + Instruction *NI = dyn_cast<Instruction>(VMI->second); + if (!NI) + continue; + + if (MDNode *M = NI->getMetadata(LLVMContext::MD_alias_scope)) { + MDNode *NewMD = MDMap[M]; + // If the call site also had alias scope metadata (a list of scopes to + // which instructions inside it might belong), propagate those scopes to + // the inlined instructions. + if (MDNode *CSM = + CS.getInstruction()->getMetadata(LLVMContext::MD_alias_scope)) + NewMD = MDNode::concatenate(NewMD, CSM); + NI->setMetadata(LLVMContext::MD_alias_scope, NewMD); + } else if (NI->mayReadOrWriteMemory()) { + if (MDNode *M = + CS.getInstruction()->getMetadata(LLVMContext::MD_alias_scope)) + NI->setMetadata(LLVMContext::MD_alias_scope, M); + } + + if (MDNode *M = NI->getMetadata(LLVMContext::MD_noalias)) { + MDNode *NewMD = MDMap[M]; + // If the call site also had noalias metadata (a list of scopes with + // which instructions inside it don't alias), propagate those scopes to + // the inlined instructions. + if (MDNode *CSM = + CS.getInstruction()->getMetadata(LLVMContext::MD_noalias)) + NewMD = MDNode::concatenate(NewMD, CSM); + NI->setMetadata(LLVMContext::MD_noalias, NewMD); + } else if (NI->mayReadOrWriteMemory()) { + if (MDNode *M = CS.getInstruction()->getMetadata(LLVMContext::MD_noalias)) + NI->setMetadata(LLVMContext::MD_noalias, M); + } + } + + // Now that everything has been replaced, delete the dummy nodes. + for (unsigned i = 0, ie = DummyNodes.size(); i != ie; ++i) + MDNode::deleteTemporary(DummyNodes[i]); +} + +/// AddAliasScopeMetadata - If the inlined function has noalias arguments, then +/// add new alias scopes for each noalias argument, tag the mapped noalias +/// parameters with noalias metadata specifying the new scope, and tag all +/// non-derived loads, stores and memory intrinsics with the new alias scopes. +static void AddAliasScopeMetadata(CallSite CS, ValueToValueMapTy &VMap, + const DataLayout *DL, AliasAnalysis *AA) { + if (!EnableNoAliasConversion) + return; + + const Function *CalledFunc = CS.getCalledFunction(); + SmallVector<const Argument *, 4> NoAliasArgs; + + for (Function::const_arg_iterator I = CalledFunc->arg_begin(), + E = CalledFunc->arg_end(); I != E; ++I) { + if (I->hasNoAliasAttr() && !I->hasNUses(0)) + NoAliasArgs.push_back(I); + } + + if (NoAliasArgs.empty()) + return; + + // To do a good job, if a noalias variable is captured, we need to know if + // the capture point dominates the particular use we're considering. + DominatorTree DT; + DT.recalculate(const_cast<Function&>(*CalledFunc)); + + // noalias indicates that pointer values based on the argument do not alias + // pointer values which are not based on it. So we add a new "scope" for each + // noalias function argument. Accesses using pointers based on that argument + // become part of that alias scope, accesses using pointers not based on that + // argument are tagged as noalias with that scope. + + DenseMap<const Argument *, MDNode *> NewScopes; + MDBuilder MDB(CalledFunc->getContext()); + + // Create a new scope domain for this function. + MDNode *NewDomain = + MDB.createAnonymousAliasScopeDomain(CalledFunc->getName()); + for (unsigned i = 0, e = NoAliasArgs.size(); i != e; ++i) { + const Argument *A = NoAliasArgs[i]; + + std::string Name = CalledFunc->getName(); + if (A->hasName()) { + Name += ": %"; + Name += A->getName(); + } else { + Name += ": argument "; + Name += utostr(i); + } + + // Note: We always create a new anonymous root here. This is true regardless + // of the linkage of the callee because the aliasing "scope" is not just a + // property of the callee, but also all control dependencies in the caller. + MDNode *NewScope = MDB.createAnonymousAliasScope(NewDomain, Name); + NewScopes.insert(std::make_pair(A, NewScope)); + } + + // Iterate over all new instructions in the map; for all memory-access + // instructions, add the alias scope metadata. + for (ValueToValueMapTy::iterator VMI = VMap.begin(), VMIE = VMap.end(); + VMI != VMIE; ++VMI) { + if (const Instruction *I = dyn_cast<Instruction>(VMI->first)) { + if (!VMI->second) + continue; + + Instruction *NI = dyn_cast<Instruction>(VMI->second); + if (!NI) + continue; + + bool IsArgMemOnlyCall = false, IsFuncCall = false; + SmallVector<const Value *, 2> PtrArgs; + + if (const LoadInst *LI = dyn_cast<LoadInst>(I)) + PtrArgs.push_back(LI->getPointerOperand()); + else if (const StoreInst *SI = dyn_cast<StoreInst>(I)) + PtrArgs.push_back(SI->getPointerOperand()); + else if (const VAArgInst *VAAI = dyn_cast<VAArgInst>(I)) + PtrArgs.push_back(VAAI->getPointerOperand()); + else if (const AtomicCmpXchgInst *CXI = dyn_cast<AtomicCmpXchgInst>(I)) + PtrArgs.push_back(CXI->getPointerOperand()); + else if (const AtomicRMWInst *RMWI = dyn_cast<AtomicRMWInst>(I)) + PtrArgs.push_back(RMWI->getPointerOperand()); + else if (ImmutableCallSite ICS = ImmutableCallSite(I)) { + // If we know that the call does not access memory, then we'll still + // know that about the inlined clone of this call site, and we don't + // need to add metadata. + if (ICS.doesNotAccessMemory()) + continue; + + IsFuncCall = true; + if (AA) { + AliasAnalysis::ModRefBehavior MRB = AA->getModRefBehavior(ICS); + if (MRB == AliasAnalysis::OnlyAccessesArgumentPointees || + MRB == AliasAnalysis::OnlyReadsArgumentPointees) + IsArgMemOnlyCall = true; + } + + for (ImmutableCallSite::arg_iterator AI = ICS.arg_begin(), + AE = ICS.arg_end(); AI != AE; ++AI) { + // We need to check the underlying objects of all arguments, not just + // the pointer arguments, because we might be passing pointers as + // integers, etc. + // However, if we know that the call only accesses pointer arguments, + // then we only need to check the pointer arguments. + if (IsArgMemOnlyCall && !(*AI)->getType()->isPointerTy()) + continue; + + PtrArgs.push_back(*AI); + } + } + + // If we found no pointers, then this instruction is not suitable for + // pairing with an instruction to receive aliasing metadata. + // However, if this is a call, this we might just alias with none of the + // noalias arguments. + if (PtrArgs.empty() && !IsFuncCall) + continue; + + // It is possible that there is only one underlying object, but you + // need to go through several PHIs to see it, and thus could be + // repeated in the Objects list. + SmallPtrSet<const Value *, 4> ObjSet; + SmallVector<Metadata *, 4> Scopes, NoAliases; + + SmallSetVector<const Argument *, 4> NAPtrArgs; + for (unsigned i = 0, ie = PtrArgs.size(); i != ie; ++i) { + SmallVector<Value *, 4> Objects; + GetUnderlyingObjects(const_cast<Value*>(PtrArgs[i]), + Objects, DL, /* MaxLookup = */ 0); + + for (Value *O : Objects) + ObjSet.insert(O); + } + + // Figure out if we're derived from anything that is not a noalias + // argument. + bool CanDeriveViaCapture = false, UsesAliasingPtr = false; + for (const Value *V : ObjSet) { + // Is this value a constant that cannot be derived from any pointer + // value (we need to exclude constant expressions, for example, that + // are formed from arithmetic on global symbols). + bool IsNonPtrConst = isa<ConstantInt>(V) || isa<ConstantFP>(V) || + isa<ConstantPointerNull>(V) || + isa<ConstantDataVector>(V) || isa<UndefValue>(V); + if (IsNonPtrConst) + continue; + + // If this is anything other than a noalias argument, then we cannot + // completely describe the aliasing properties using alias.scope + // metadata (and, thus, won't add any). + if (const Argument *A = dyn_cast<Argument>(V)) { + if (!A->hasNoAliasAttr()) + UsesAliasingPtr = true; + } else { + UsesAliasingPtr = true; + } + + // If this is not some identified function-local object (which cannot + // directly alias a noalias argument), or some other argument (which, + // by definition, also cannot alias a noalias argument), then we could + // alias a noalias argument that has been captured). + if (!isa<Argument>(V) && + !isIdentifiedFunctionLocal(const_cast<Value*>(V))) + CanDeriveViaCapture = true; + } + + // A function call can always get captured noalias pointers (via other + // parameters, globals, etc.). + if (IsFuncCall && !IsArgMemOnlyCall) + CanDeriveViaCapture = true; + + // First, we want to figure out all of the sets with which we definitely + // don't alias. Iterate over all noalias set, and add those for which: + // 1. The noalias argument is not in the set of objects from which we + // definitely derive. + // 2. The noalias argument has not yet been captured. + // An arbitrary function that might load pointers could see captured + // noalias arguments via other noalias arguments or globals, and so we + // must always check for prior capture. + for (const Argument *A : NoAliasArgs) { + if (!ObjSet.count(A) && (!CanDeriveViaCapture || + // It might be tempting to skip the + // PointerMayBeCapturedBefore check if + // A->hasNoCaptureAttr() is true, but this is + // incorrect because nocapture only guarantees + // that no copies outlive the function, not + // that the value cannot be locally captured. + !PointerMayBeCapturedBefore(A, + /* ReturnCaptures */ false, + /* StoreCaptures */ false, I, &DT))) + NoAliases.push_back(NewScopes[A]); + } + + if (!NoAliases.empty()) + NI->setMetadata(LLVMContext::MD_noalias, + MDNode::concatenate( + NI->getMetadata(LLVMContext::MD_noalias), + MDNode::get(CalledFunc->getContext(), NoAliases))); + + // Next, we want to figure out all of the sets to which we might belong. + // We might belong to a set if the noalias argument is in the set of + // underlying objects. If there is some non-noalias argument in our list + // of underlying objects, then we cannot add a scope because the fact + // that some access does not alias with any set of our noalias arguments + // cannot itself guarantee that it does not alias with this access + // (because there is some pointer of unknown origin involved and the + // other access might also depend on this pointer). We also cannot add + // scopes to arbitrary functions unless we know they don't access any + // non-parameter pointer-values. + bool CanAddScopes = !UsesAliasingPtr; + if (CanAddScopes && IsFuncCall) + CanAddScopes = IsArgMemOnlyCall; + + if (CanAddScopes) + for (const Argument *A : NoAliasArgs) { + if (ObjSet.count(A)) + Scopes.push_back(NewScopes[A]); + } + + if (!Scopes.empty()) + NI->setMetadata( + LLVMContext::MD_alias_scope, + MDNode::concatenate(NI->getMetadata(LLVMContext::MD_alias_scope), + MDNode::get(CalledFunc->getContext(), Scopes))); + } + } +} + +/// If the inlined function has non-byval align arguments, then +/// add @llvm.assume-based alignment assumptions to preserve this information. +static void AddAlignmentAssumptions(CallSite CS, InlineFunctionInfo &IFI) { + if (!PreserveAlignmentAssumptions || !IFI.DL) + return; + + // To avoid inserting redundant assumptions, we should check for assumptions + // already in the caller. To do this, we might need a DT of the caller. + DominatorTree DT; + bool DTCalculated = false; + + Function *CalledFunc = CS.getCalledFunction(); + for (Function::arg_iterator I = CalledFunc->arg_begin(), + E = CalledFunc->arg_end(); + I != E; ++I) { + unsigned Align = I->getType()->isPointerTy() ? I->getParamAlignment() : 0; + if (Align && !I->hasByValOrInAllocaAttr() && !I->hasNUses(0)) { + if (!DTCalculated) { + DT.recalculate(const_cast<Function&>(*CS.getInstruction()->getParent() + ->getParent())); + DTCalculated = true; + } + + // If we can already prove the asserted alignment in the context of the + // caller, then don't bother inserting the assumption. + Value *Arg = CS.getArgument(I->getArgNo()); + if (getKnownAlignment(Arg, IFI.DL, + &IFI.ACT->getAssumptionCache(*CalledFunc), + CS.getInstruction(), &DT) >= Align) + continue; + + IRBuilder<>(CS.getInstruction()).CreateAlignmentAssumption(*IFI.DL, Arg, + Align); + } + } +} + +/// UpdateCallGraphAfterInlining - Once we have cloned code over from a callee +/// into the caller, update the specified callgraph to reflect the changes we +/// made. Note that it's possible that not all code was copied over, so only +/// some edges of the callgraph may remain. +static void UpdateCallGraphAfterInlining(CallSite CS, + Function::iterator FirstNewBlock, + ValueToValueMapTy &VMap, + InlineFunctionInfo &IFI) { + CallGraph &CG = *IFI.CG; + const Function *Caller = CS.getInstruction()->getParent()->getParent(); + const Function *Callee = CS.getCalledFunction(); + CallGraphNode *CalleeNode = CG[Callee]; + CallGraphNode *CallerNode = CG[Caller]; + + // Since we inlined some uninlined call sites in the callee into the caller, + // add edges from the caller to all of the callees of the callee. + CallGraphNode::iterator I = CalleeNode->begin(), E = CalleeNode->end(); + + // Consider the case where CalleeNode == CallerNode. + CallGraphNode::CalledFunctionsVector CallCache; + if (CalleeNode == CallerNode) { + CallCache.assign(I, E); + I = CallCache.begin(); + E = CallCache.end(); + } + + for (; I != E; ++I) { + const Value *OrigCall = I->first; + + ValueToValueMapTy::iterator VMI = VMap.find(OrigCall); + // Only copy the edge if the call was inlined! + if (VMI == VMap.end() || VMI->second == nullptr) + continue; + + // If the call was inlined, but then constant folded, there is no edge to + // add. Check for this case. + Instruction *NewCall = dyn_cast<Instruction>(VMI->second); + if (!NewCall) continue; + + // Remember that this call site got inlined for the client of + // InlineFunction. + IFI.InlinedCalls.push_back(NewCall); + + // It's possible that inlining the callsite will cause it to go from an + // indirect to a direct call by resolving a function pointer. If this + // happens, set the callee of the new call site to a more precise + // destination. This can also happen if the call graph node of the caller + // was just unnecessarily imprecise. + if (!I->second->getFunction()) + if (Function *F = CallSite(NewCall).getCalledFunction()) { + // Indirect call site resolved to direct call. + CallerNode->addCalledFunction(CallSite(NewCall), CG[F]); + + continue; + } + + CallerNode->addCalledFunction(CallSite(NewCall), I->second); + } + + // Update the call graph by deleting the edge from Callee to Caller. We must + // do this after the loop above in case Caller and Callee are the same. + CallerNode->removeCallEdgeFor(CS); +} + +static void HandleByValArgumentInit(Value *Dst, Value *Src, Module *M, + BasicBlock *InsertBlock, + InlineFunctionInfo &IFI) { + Type *AggTy = cast<PointerType>(Src->getType())->getElementType(); + IRBuilder<> Builder(InsertBlock->begin()); + + Value *Size; + if (IFI.DL == nullptr) + Size = ConstantExpr::getSizeOf(AggTy); + else + Size = Builder.getInt64(IFI.DL->getTypeStoreSize(AggTy)); + + // Always generate a memcpy of alignment 1 here because we don't know + // the alignment of the src pointer. Other optimizations can infer + // better alignment. + Builder.CreateMemCpy(Dst, Src, Size, /*Align=*/1); +} + +/// HandleByValArgument - When inlining a call site that has a byval argument, +/// we have to make the implicit memcpy explicit by adding it. +static Value *HandleByValArgument(Value *Arg, Instruction *TheCall, + const Function *CalledFunc, + InlineFunctionInfo &IFI, + unsigned ByValAlignment) { + PointerType *ArgTy = cast<PointerType>(Arg->getType()); + Type *AggTy = ArgTy->getElementType(); + + Function *Caller = TheCall->getParent()->getParent(); + + // If the called function is readonly, then it could not mutate the caller's + // copy of the byval'd memory. In this case, it is safe to elide the copy and + // temporary. + if (CalledFunc->onlyReadsMemory()) { + // If the byval argument has a specified alignment that is greater than the + // passed in pointer, then we either have to round up the input pointer or + // give up on this transformation. + if (ByValAlignment <= 1) // 0 = unspecified, 1 = no particular alignment. + return Arg; + + // If the pointer is already known to be sufficiently aligned, or if we can + // round it up to a larger alignment, then we don't need a temporary. + if (getOrEnforceKnownAlignment(Arg, ByValAlignment, IFI.DL, + &IFI.ACT->getAssumptionCache(*Caller), + TheCall) >= ByValAlignment) + return Arg; + + // Otherwise, we have to make a memcpy to get a safe alignment. This is bad + // for code quality, but rarely happens and is required for correctness. + } + + // Create the alloca. If we have DataLayout, use nice alignment. + unsigned Align = 1; + if (IFI.DL) + Align = IFI.DL->getPrefTypeAlignment(AggTy); + + // If the byval had an alignment specified, we *must* use at least that + // alignment, as it is required by the byval argument (and uses of the + // pointer inside the callee). + Align = std::max(Align, ByValAlignment); + + Value *NewAlloca = new AllocaInst(AggTy, nullptr, Align, Arg->getName(), + &*Caller->begin()->begin()); + IFI.StaticAllocas.push_back(cast<AllocaInst>(NewAlloca)); + + // Uses of the argument in the function should use our new alloca + // instead. + return NewAlloca; +} + +// isUsedByLifetimeMarker - Check whether this Value is used by a lifetime +// intrinsic. +static bool isUsedByLifetimeMarker(Value *V) { + for (User *U : V->users()) { + if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(U)) { + switch (II->getIntrinsicID()) { + default: break; + case Intrinsic::lifetime_start: + case Intrinsic::lifetime_end: + return true; + } + } + } + return false; +} + +// hasLifetimeMarkers - Check whether the given alloca already has +// lifetime.start or lifetime.end intrinsics. +static bool hasLifetimeMarkers(AllocaInst *AI) { + Type *Ty = AI->getType(); + Type *Int8PtrTy = Type::getInt8PtrTy(Ty->getContext(), + Ty->getPointerAddressSpace()); + if (Ty == Int8PtrTy) + return isUsedByLifetimeMarker(AI); + + // Do a scan to find all the casts to i8*. + for (User *U : AI->users()) { + if (U->getType() != Int8PtrTy) continue; + if (U->stripPointerCasts() != AI) continue; + if (isUsedByLifetimeMarker(U)) + return true; + } + return false; +} + +/// updateInlinedAtInfo - Helper function used by fixupLineNumbers to +/// recursively update InlinedAtEntry of a DebugLoc. +static DebugLoc updateInlinedAtInfo(const DebugLoc &DL, + const DebugLoc &InlinedAtDL, + LLVMContext &Ctx) { + if (MDNode *IA = DL.getInlinedAt(Ctx)) { + DebugLoc NewInlinedAtDL + = updateInlinedAtInfo(DebugLoc::getFromDILocation(IA), InlinedAtDL, Ctx); + return DebugLoc::get(DL.getLine(), DL.getCol(), DL.getScope(Ctx), + NewInlinedAtDL.getAsMDNode(Ctx)); + } + + return DebugLoc::get(DL.getLine(), DL.getCol(), DL.getScope(Ctx), + InlinedAtDL.getAsMDNode(Ctx)); +} + +/// fixupLineNumbers - Update inlined instructions' line numbers to +/// to encode location where these instructions are inlined. +static void fixupLineNumbers(Function *Fn, Function::iterator FI, + Instruction *TheCall) { + DebugLoc TheCallDL = TheCall->getDebugLoc(); + if (TheCallDL.isUnknown()) + return; + + for (; FI != Fn->end(); ++FI) { + for (BasicBlock::iterator BI = FI->begin(), BE = FI->end(); + BI != BE; ++BI) { + DebugLoc DL = BI->getDebugLoc(); + if (DL.isUnknown()) { + // If the inlined instruction has no line number, make it look as if it + // originates from the call location. This is important for + // ((__always_inline__, __nodebug__)) functions which must use caller + // location for all instructions in their function body. + + // Don't update static allocas, as they may get moved later. + if (auto *AI = dyn_cast<AllocaInst>(BI)) + if (isa<Constant>(AI->getArraySize())) + continue; + + BI->setDebugLoc(TheCallDL); + } else { + BI->setDebugLoc(updateInlinedAtInfo(DL, TheCallDL, BI->getContext())); + if (DbgValueInst *DVI = dyn_cast<DbgValueInst>(BI)) { + LLVMContext &Ctx = BI->getContext(); + MDNode *InlinedAt = BI->getDebugLoc().getInlinedAt(Ctx); + DVI->setOperand(2, MetadataAsValue::get( + Ctx, createInlinedVariable(DVI->getVariable(), + InlinedAt, Ctx))); + } else if (DbgDeclareInst *DDI = dyn_cast<DbgDeclareInst>(BI)) { + LLVMContext &Ctx = BI->getContext(); + MDNode *InlinedAt = BI->getDebugLoc().getInlinedAt(Ctx); + DDI->setOperand(1, MetadataAsValue::get( + Ctx, createInlinedVariable(DDI->getVariable(), + InlinedAt, Ctx))); + } + } + } + } +} + +/// InlineFunction - This function inlines the called function into the basic +/// block of the caller. This returns false if it is not possible to inline +/// this call. The program is still in a well defined state if this occurs +/// though. +/// +/// Note that this only does one level of inlining. For example, if the +/// instruction 'call B' is inlined, and 'B' calls 'C', then the call to 'C' now +/// exists in the instruction stream. Similarly this will inline a recursive +/// function by one level. +bool llvm::InlineFunction(CallSite CS, InlineFunctionInfo &IFI, + bool InsertLifetime) { + Instruction *TheCall = CS.getInstruction(); + assert(TheCall->getParent() && TheCall->getParent()->getParent() && + "Instruction not in function!"); + + // If IFI has any state in it, zap it before we fill it in. + IFI.reset(); + + const Function *CalledFunc = CS.getCalledFunction(); + if (!CalledFunc || // Can't inline external function or indirect + CalledFunc->isDeclaration() || // call, or call to a vararg function! + CalledFunc->getFunctionType()->isVarArg()) return false; + + // If the call to the callee cannot throw, set the 'nounwind' flag on any + // calls that we inline. + bool MarkNoUnwind = CS.doesNotThrow(); + + BasicBlock *OrigBB = TheCall->getParent(); + Function *Caller = OrigBB->getParent(); + + // GC poses two hazards to inlining, which only occur when the callee has GC: + // 1. If the caller has no GC, then the callee's GC must be propagated to the + // caller. + // 2. If the caller has a differing GC, it is invalid to inline. + if (CalledFunc->hasGC()) { + if (!Caller->hasGC()) + Caller->setGC(CalledFunc->getGC()); + else if (CalledFunc->getGC() != Caller->getGC()) + return false; + } + + // Get the personality function from the callee if it contains a landing pad. + Value *CalleePersonality = nullptr; + for (Function::const_iterator I = CalledFunc->begin(), E = CalledFunc->end(); + I != E; ++I) + if (const InvokeInst *II = dyn_cast<InvokeInst>(I->getTerminator())) { + const BasicBlock *BB = II->getUnwindDest(); + const LandingPadInst *LP = BB->getLandingPadInst(); + CalleePersonality = LP->getPersonalityFn(); + break; + } + + // Find the personality function used by the landing pads of the caller. If it + // exists, then check to see that it matches the personality function used in + // the callee. + if (CalleePersonality) { + for (Function::const_iterator I = Caller->begin(), E = Caller->end(); + I != E; ++I) + if (const InvokeInst *II = dyn_cast<InvokeInst>(I->getTerminator())) { + const BasicBlock *BB = II->getUnwindDest(); + const LandingPadInst *LP = BB->getLandingPadInst(); + + // If the personality functions match, then we can perform the + // inlining. Otherwise, we can't inline. + // TODO: This isn't 100% true. Some personality functions are proper + // supersets of others and can be used in place of the other. + if (LP->getPersonalityFn() != CalleePersonality) + return false; + + break; + } + } + + // Get an iterator to the last basic block in the function, which will have + // the new function inlined after it. + Function::iterator LastBlock = &Caller->back(); + + // Make sure to capture all of the return instructions from the cloned + // function. + SmallVector<ReturnInst*, 8> Returns; + ClonedCodeInfo InlinedFunctionInfo; + Function::iterator FirstNewBlock; + + { // Scope to destroy VMap after cloning. + ValueToValueMapTy VMap; + // Keep a list of pair (dst, src) to emit byval initializations. + SmallVector<std::pair<Value*, Value*>, 4> ByValInit; + + assert(CalledFunc->arg_size() == CS.arg_size() && + "No varargs calls can be inlined!"); + + // Calculate the vector of arguments to pass into the function cloner, which + // matches up the formal to the actual argument values. + CallSite::arg_iterator AI = CS.arg_begin(); + unsigned ArgNo = 0; + for (Function::const_arg_iterator I = CalledFunc->arg_begin(), + E = CalledFunc->arg_end(); I != E; ++I, ++AI, ++ArgNo) { + Value *ActualArg = *AI; + + // When byval arguments actually inlined, we need to make the copy implied + // by them explicit. However, we don't do this if the callee is readonly + // or readnone, because the copy would be unneeded: the callee doesn't + // modify the struct. + if (CS.isByValArgument(ArgNo)) { + ActualArg = HandleByValArgument(ActualArg, TheCall, CalledFunc, IFI, + CalledFunc->getParamAlignment(ArgNo+1)); + if (ActualArg != *AI) + ByValInit.push_back(std::make_pair(ActualArg, (Value*) *AI)); + } + + VMap[I] = ActualArg; + } + + // Add alignment assumptions if necessary. We do this before the inlined + // instructions are actually cloned into the caller so that we can easily + // check what will be known at the start of the inlined code. + AddAlignmentAssumptions(CS, IFI); + + // We want the inliner to prune the code as it copies. We would LOVE to + // have no dead or constant instructions leftover after inlining occurs + // (which can happen, e.g., because an argument was constant), but we'll be + // happy with whatever the cloner can do. + CloneAndPruneFunctionInto(Caller, CalledFunc, VMap, + /*ModuleLevelChanges=*/false, Returns, ".i", + &InlinedFunctionInfo, IFI.DL, TheCall); + + // Remember the first block that is newly cloned over. + FirstNewBlock = LastBlock; ++FirstNewBlock; + + // Inject byval arguments initialization. + for (std::pair<Value*, Value*> &Init : ByValInit) + HandleByValArgumentInit(Init.first, Init.second, Caller->getParent(), + FirstNewBlock, IFI); + + // Update the callgraph if requested. + if (IFI.CG) + UpdateCallGraphAfterInlining(CS, FirstNewBlock, VMap, IFI); + + // Update inlined instructions' line number information. + fixupLineNumbers(Caller, FirstNewBlock, TheCall); + + // Clone existing noalias metadata if necessary. + CloneAliasScopeMetadata(CS, VMap); + + // Add noalias metadata if necessary. + AddAliasScopeMetadata(CS, VMap, IFI.DL, IFI.AA); + + // FIXME: We could register any cloned assumptions instead of clearing the + // whole function's cache. + if (IFI.ACT) + IFI.ACT->getAssumptionCache(*Caller).clear(); + } + + // If there are any alloca instructions in the block that used to be the entry + // block for the callee, move them to the entry block of the caller. First + // calculate which instruction they should be inserted before. We insert the + // instructions at the end of the current alloca list. + { + BasicBlock::iterator InsertPoint = Caller->begin()->begin(); + for (BasicBlock::iterator I = FirstNewBlock->begin(), + E = FirstNewBlock->end(); I != E; ) { + AllocaInst *AI = dyn_cast<AllocaInst>(I++); + if (!AI) continue; + + // If the alloca is now dead, remove it. This often occurs due to code + // specialization. + if (AI->use_empty()) { + AI->eraseFromParent(); + continue; + } + + if (!isa<Constant>(AI->getArraySize())) + continue; + + // Keep track of the static allocas that we inline into the caller. + IFI.StaticAllocas.push_back(AI); + + // Scan for the block of allocas that we can move over, and move them + // all at once. + while (isa<AllocaInst>(I) && + isa<Constant>(cast<AllocaInst>(I)->getArraySize())) { + IFI.StaticAllocas.push_back(cast<AllocaInst>(I)); + ++I; + } + + // Transfer all of the allocas over in a block. Using splice means + // that the instructions aren't removed from the symbol table, then + // reinserted. + Caller->getEntryBlock().getInstList().splice(InsertPoint, + FirstNewBlock->getInstList(), + AI, I); + } + } + + bool InlinedMustTailCalls = false; + if (InlinedFunctionInfo.ContainsCalls) { + CallInst::TailCallKind CallSiteTailKind = CallInst::TCK_None; + if (CallInst *CI = dyn_cast<CallInst>(TheCall)) + CallSiteTailKind = CI->getTailCallKind(); + + for (Function::iterator BB = FirstNewBlock, E = Caller->end(); BB != E; + ++BB) { + for (Instruction &I : *BB) { + CallInst *CI = dyn_cast<CallInst>(&I); + if (!CI) + continue; + + // We need to reduce the strength of any inlined tail calls. For + // musttail, we have to avoid introducing potential unbounded stack + // growth. For example, if functions 'f' and 'g' are mutually recursive + // with musttail, we can inline 'g' into 'f' so long as we preserve + // musttail on the cloned call to 'f'. If either the inlined call site + // or the cloned call site is *not* musttail, the program already has + // one frame of stack growth, so it's safe to remove musttail. Here is + // a table of example transformations: + // + // f -> musttail g -> musttail f ==> f -> musttail f + // f -> musttail g -> tail f ==> f -> tail f + // f -> g -> musttail f ==> f -> f + // f -> g -> tail f ==> f -> f + CallInst::TailCallKind ChildTCK = CI->getTailCallKind(); + ChildTCK = std::min(CallSiteTailKind, ChildTCK); + CI->setTailCallKind(ChildTCK); + InlinedMustTailCalls |= CI->isMustTailCall(); + + // Calls inlined through a 'nounwind' call site should be marked + // 'nounwind'. + if (MarkNoUnwind) + CI->setDoesNotThrow(); + } + } + } + + // Leave lifetime markers for the static alloca's, scoping them to the + // function we just inlined. + if (InsertLifetime && !IFI.StaticAllocas.empty()) { + IRBuilder<> builder(FirstNewBlock->begin()); + for (unsigned ai = 0, ae = IFI.StaticAllocas.size(); ai != ae; ++ai) { + AllocaInst *AI = IFI.StaticAllocas[ai]; + + // If the alloca is already scoped to something smaller than the whole + // function then there's no need to add redundant, less accurate markers. + if (hasLifetimeMarkers(AI)) + continue; + + // Try to determine the size of the allocation. + ConstantInt *AllocaSize = nullptr; + if (ConstantInt *AIArraySize = + dyn_cast<ConstantInt>(AI->getArraySize())) { + if (IFI.DL) { + Type *AllocaType = AI->getAllocatedType(); + uint64_t AllocaTypeSize = IFI.DL->getTypeAllocSize(AllocaType); + uint64_t AllocaArraySize = AIArraySize->getLimitedValue(); + assert(AllocaArraySize > 0 && "array size of AllocaInst is zero"); + // Check that array size doesn't saturate uint64_t and doesn't + // overflow when it's multiplied by type size. + if (AllocaArraySize != ~0ULL && + UINT64_MAX / AllocaArraySize >= AllocaTypeSize) { + AllocaSize = ConstantInt::get(Type::getInt64Ty(AI->getContext()), + AllocaArraySize * AllocaTypeSize); + } + } + } + + builder.CreateLifetimeStart(AI, AllocaSize); + for (ReturnInst *RI : Returns) { + // Don't insert llvm.lifetime.end calls between a musttail call and a + // return. The return kills all local allocas. + if (InlinedMustTailCalls && + RI->getParent()->getTerminatingMustTailCall()) + continue; + IRBuilder<>(RI).CreateLifetimeEnd(AI, AllocaSize); + } + } + } + + // If the inlined code contained dynamic alloca instructions, wrap the inlined + // code with llvm.stacksave/llvm.stackrestore intrinsics. + if (InlinedFunctionInfo.ContainsDynamicAllocas) { + Module *M = Caller->getParent(); + // Get the two intrinsics we care about. + Function *StackSave = Intrinsic::getDeclaration(M, Intrinsic::stacksave); + Function *StackRestore=Intrinsic::getDeclaration(M,Intrinsic::stackrestore); + + // Insert the llvm.stacksave. + CallInst *SavedPtr = IRBuilder<>(FirstNewBlock, FirstNewBlock->begin()) + .CreateCall(StackSave, "savedstack"); + + // Insert a call to llvm.stackrestore before any return instructions in the + // inlined function. + for (ReturnInst *RI : Returns) { + // Don't insert llvm.stackrestore calls between a musttail call and a + // return. The return will restore the stack pointer. + if (InlinedMustTailCalls && RI->getParent()->getTerminatingMustTailCall()) + continue; + IRBuilder<>(RI).CreateCall(StackRestore, SavedPtr); + } + } + + // If we are inlining for an invoke instruction, we must make sure to rewrite + // any call instructions into invoke instructions. + if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall)) + HandleInlinedInvoke(II, FirstNewBlock, InlinedFunctionInfo); + + // Handle any inlined musttail call sites. In order for a new call site to be + // musttail, the source of the clone and the inlined call site must have been + // musttail. Therefore it's safe to return without merging control into the + // phi below. + if (InlinedMustTailCalls) { + // Check if we need to bitcast the result of any musttail calls. + Type *NewRetTy = Caller->getReturnType(); + bool NeedBitCast = !TheCall->use_empty() && TheCall->getType() != NewRetTy; + + // Handle the returns preceded by musttail calls separately. + SmallVector<ReturnInst *, 8> NormalReturns; + for (ReturnInst *RI : Returns) { + CallInst *ReturnedMustTail = + RI->getParent()->getTerminatingMustTailCall(); + if (!ReturnedMustTail) { + NormalReturns.push_back(RI); + continue; + } + if (!NeedBitCast) + continue; + + // Delete the old return and any preceding bitcast. + BasicBlock *CurBB = RI->getParent(); + auto *OldCast = dyn_cast_or_null<BitCastInst>(RI->getReturnValue()); + RI->eraseFromParent(); + if (OldCast) + OldCast->eraseFromParent(); + + // Insert a new bitcast and return with the right type. + IRBuilder<> Builder(CurBB); + Builder.CreateRet(Builder.CreateBitCast(ReturnedMustTail, NewRetTy)); + } + + // Leave behind the normal returns so we can merge control flow. + std::swap(Returns, NormalReturns); + } + + // If we cloned in _exactly one_ basic block, and if that block ends in a + // return instruction, we splice the body of the inlined callee directly into + // the calling basic block. + if (Returns.size() == 1 && std::distance(FirstNewBlock, Caller->end()) == 1) { + // Move all of the instructions right before the call. + OrigBB->getInstList().splice(TheCall, FirstNewBlock->getInstList(), + FirstNewBlock->begin(), FirstNewBlock->end()); + // Remove the cloned basic block. + Caller->getBasicBlockList().pop_back(); + + // If the call site was an invoke instruction, add a branch to the normal + // destination. + if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall)) { + BranchInst *NewBr = BranchInst::Create(II->getNormalDest(), TheCall); + NewBr->setDebugLoc(Returns[0]->getDebugLoc()); + } + + // If the return instruction returned a value, replace uses of the call with + // uses of the returned value. + if (!TheCall->use_empty()) { + ReturnInst *R = Returns[0]; + if (TheCall == R->getReturnValue()) + TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType())); + else + TheCall->replaceAllUsesWith(R->getReturnValue()); + } + // Since we are now done with the Call/Invoke, we can delete it. + TheCall->eraseFromParent(); + + // Since we are now done with the return instruction, delete it also. + Returns[0]->eraseFromParent(); + + // We are now done with the inlining. + return true; + } + + // Otherwise, we have the normal case, of more than one block to inline or + // multiple return sites. + + // We want to clone the entire callee function into the hole between the + // "starter" and "ender" blocks. How we accomplish this depends on whether + // this is an invoke instruction or a call instruction. + BasicBlock *AfterCallBB; + BranchInst *CreatedBranchToNormalDest = nullptr; + if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall)) { + + // Add an unconditional branch to make this look like the CallInst case... + CreatedBranchToNormalDest = BranchInst::Create(II->getNormalDest(), TheCall); + + // Split the basic block. This guarantees that no PHI nodes will have to be + // updated due to new incoming edges, and make the invoke case more + // symmetric to the call case. + AfterCallBB = OrigBB->splitBasicBlock(CreatedBranchToNormalDest, + CalledFunc->getName()+".exit"); + + } else { // It's a call + // If this is a call instruction, we need to split the basic block that + // the call lives in. + // + AfterCallBB = OrigBB->splitBasicBlock(TheCall, + CalledFunc->getName()+".exit"); + } + + // Change the branch that used to go to AfterCallBB to branch to the first + // basic block of the inlined function. + // + TerminatorInst *Br = OrigBB->getTerminator(); + assert(Br && Br->getOpcode() == Instruction::Br && + "splitBasicBlock broken!"); + Br->setOperand(0, FirstNewBlock); + + + // Now that the function is correct, make it a little bit nicer. In + // particular, move the basic blocks inserted from the end of the function + // into the space made by splitting the source basic block. + Caller->getBasicBlockList().splice(AfterCallBB, Caller->getBasicBlockList(), + FirstNewBlock, Caller->end()); + + // Handle all of the return instructions that we just cloned in, and eliminate + // any users of the original call/invoke instruction. + Type *RTy = CalledFunc->getReturnType(); + + PHINode *PHI = nullptr; + if (Returns.size() > 1) { + // The PHI node should go at the front of the new basic block to merge all + // possible incoming values. + if (!TheCall->use_empty()) { + PHI = PHINode::Create(RTy, Returns.size(), TheCall->getName(), + AfterCallBB->begin()); + // Anything that used the result of the function call should now use the + // PHI node as their operand. + TheCall->replaceAllUsesWith(PHI); + } + + // Loop over all of the return instructions adding entries to the PHI node + // as appropriate. + if (PHI) { + for (unsigned i = 0, e = Returns.size(); i != e; ++i) { + ReturnInst *RI = Returns[i]; + assert(RI->getReturnValue()->getType() == PHI->getType() && + "Ret value not consistent in function!"); + PHI->addIncoming(RI->getReturnValue(), RI->getParent()); + } + } + + + // Add a branch to the merge points and remove return instructions. + DebugLoc Loc; + for (unsigned i = 0, e = Returns.size(); i != e; ++i) { + ReturnInst *RI = Returns[i]; + BranchInst* BI = BranchInst::Create(AfterCallBB, RI); + Loc = RI->getDebugLoc(); + BI->setDebugLoc(Loc); + RI->eraseFromParent(); + } + // We need to set the debug location to *somewhere* inside the + // inlined function. The line number may be nonsensical, but the + // instruction will at least be associated with the right + // function. + if (CreatedBranchToNormalDest) + CreatedBranchToNormalDest->setDebugLoc(Loc); + } else if (!Returns.empty()) { + // Otherwise, if there is exactly one return value, just replace anything + // using the return value of the call with the computed value. + if (!TheCall->use_empty()) { + if (TheCall == Returns[0]->getReturnValue()) + TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType())); + else + TheCall->replaceAllUsesWith(Returns[0]->getReturnValue()); + } + + // Update PHI nodes that use the ReturnBB to use the AfterCallBB. + BasicBlock *ReturnBB = Returns[0]->getParent(); + ReturnBB->replaceAllUsesWith(AfterCallBB); + + // Splice the code from the return block into the block that it will return + // to, which contains the code that was after the call. + AfterCallBB->getInstList().splice(AfterCallBB->begin(), + ReturnBB->getInstList()); + + if (CreatedBranchToNormalDest) + CreatedBranchToNormalDest->setDebugLoc(Returns[0]->getDebugLoc()); + + // Delete the return instruction now and empty ReturnBB now. + Returns[0]->eraseFromParent(); + ReturnBB->eraseFromParent(); + } else if (!TheCall->use_empty()) { + // No returns, but something is using the return value of the call. Just + // nuke the result. + TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType())); + } + + // Since we are now done with the Call/Invoke, we can delete it. + TheCall->eraseFromParent(); + + // If we inlined any musttail calls and the original return is now + // unreachable, delete it. It can only contain a bitcast and ret. + if (InlinedMustTailCalls && pred_begin(AfterCallBB) == pred_end(AfterCallBB)) + AfterCallBB->eraseFromParent(); + + // We should always be able to fold the entry block of the function into the + // single predecessor of the block... + assert(cast<BranchInst>(Br)->isUnconditional() && "splitBasicBlock broken!"); + BasicBlock *CalleeEntry = cast<BranchInst>(Br)->getSuccessor(0); + + // Splice the code entry block into calling block, right before the + // unconditional branch. + CalleeEntry->replaceAllUsesWith(OrigBB); // Update PHI nodes + OrigBB->getInstList().splice(Br, CalleeEntry->getInstList()); + + // Remove the unconditional branch. + OrigBB->getInstList().erase(Br); + + // Now we can remove the CalleeEntry block, which is now empty. + Caller->getBasicBlockList().erase(CalleeEntry); + + // If we inserted a phi node, check to see if it has a single value (e.g. all + // the entries are the same or undef). If so, remove the PHI so it doesn't + // block other optimizations. + if (PHI) { + if (Value *V = SimplifyInstruction(PHI, IFI.DL, nullptr, nullptr, + &IFI.ACT->getAssumptionCache(*Caller))) { + PHI->replaceAllUsesWith(V); + PHI->eraseFromParent(); + } + } + + return true; +} |
