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llvm-project/llvm/lib/Transforms/Utils/InlineFunction.cpp

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//===- 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/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(false),
cl::Hidden,
cl::desc("Convert noalias attributes to metadata 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 Value *, 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 *, TrackingVH<MDNode> > 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] = 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<Value *, 4> NewOps;
for (unsigned i = 0, ie = (*I)->getNumOperands(); i != ie; ++i) {
const Value *V = (*I)->getOperand(i);
if (const MDNode *M = dyn_cast<MDNode>(V))
NewOps.push_back(MDMap[M]);
else
NewOps.push_back(const_cast<Value *>(V));
}
MDNode *NewM = MDNode::get(CalledFunc->getContext(), NewOps),
*TempM = 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) {
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;
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;
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.
// FIXME: If we know that the call only accesses pointer arguments,
// then we only need to check the pointer arguments.
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() && !isa<CallInst>(I) && !isa<InvokeInst>(I))
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<Value *, 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 &&
!isIdentifiedFunctionLocal(const_cast<Value*>(V))) {
UsesAliasingPtr = true;
if (!isa<Argument>(V)) {
CanDeriveViaCapture = true;
break;
}
}
}
// 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.
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 && (isa<CallInst>(I) || isa<InvokeInst>(I))) {
// FIXME: We should have a way to access the
// IntrReadArgMem/IntrReadWriteArgMem properties of intrinsics, and we
// should have a way to determine that for regular functions too. For
// now, just do this for the memory intrinsics we understand.
CanAddScopes = isa<MemIntrinsic>(I);
}
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)));
}
}
}
/// 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) {
LLVMContext &Context = Src->getContext();
Type *VoidPtrTy = Type::getInt8PtrTy(Context);
Type *AggTy = cast<PointerType>(Src->getType())->getElementType();
Type *Tys[3] = { VoidPtrTy, VoidPtrTy, Type::getInt64Ty(Context) };
Function *MemCpyFn = Intrinsic::getDeclaration(M, Intrinsic::memcpy, Tys);
IRBuilder<> builder(InsertBlock->begin());
Value *DstCast = builder.CreateBitCast(Dst, VoidPtrTy, "tmp");
Value *SrcCast = builder.CreateBitCast(Src, VoidPtrTy, "tmp");
Value *Size;
if (IFI.DL == nullptr)
Size = ConstantExpr::getSizeOf(AggTy);
else
Size = ConstantInt::get(Type::getInt64Ty(Context),
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.
Value *CallArgs[] = {
DstCast, SrcCast, Size,
ConstantInt::get(Type::getInt32Ty(Context), 1),
ConstantInt::getFalse(Context) // isVolatile
};
builder.CreateCall(MemCpyFn, CallArgs);
}
/// 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();
// 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) >= 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);
Function *Caller = TheCall->getParent()->getParent();
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.
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, createInlinedVariable(DVI->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;
}
// 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);
}
// 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)) {
PHI->replaceAllUsesWith(V);
PHI->eraseFromParent();
}
}
return true;
}
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