1 //===- InlineFunction.cpp - Code to perform function inlining -------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements inlining of a function into a call site, resolving
11 // parameters and the return value as appropriate.
13 //===----------------------------------------------------------------------===//
15 #include "llvm/Transforms/Utils/Cloning.h"
16 #include "llvm/ADT/SmallSet.h"
17 #include "llvm/ADT/SmallVector.h"
18 #include "llvm/ADT/SetVector.h"
19 #include "llvm/ADT/StringExtras.h"
20 #include "llvm/Analysis/AliasAnalysis.h"
21 #include "llvm/Analysis/AssumptionTracker.h"
22 #include "llvm/Analysis/CallGraph.h"
23 #include "llvm/Analysis/CaptureTracking.h"
24 #include "llvm/Analysis/InstructionSimplify.h"
25 #include "llvm/Analysis/ValueTracking.h"
26 #include "llvm/IR/Attributes.h"
27 #include "llvm/IR/CallSite.h"
28 #include "llvm/IR/CFG.h"
29 #include "llvm/IR/Constants.h"
30 #include "llvm/IR/DataLayout.h"
31 #include "llvm/IR/DebugInfo.h"
32 #include "llvm/IR/DerivedTypes.h"
33 #include "llvm/IR/Dominators.h"
34 #include "llvm/IR/IRBuilder.h"
35 #include "llvm/IR/Instructions.h"
36 #include "llvm/IR/IntrinsicInst.h"
37 #include "llvm/IR/Intrinsics.h"
38 #include "llvm/IR/MDBuilder.h"
39 #include "llvm/IR/Module.h"
40 #include "llvm/Transforms/Utils/Local.h"
41 #include "llvm/Support/CommandLine.h"
46 EnableNoAliasConversion("enable-noalias-to-md-conversion", cl::init(true),
48 cl::desc("Convert noalias attributes to metadata during inlining."));
51 PreserveAlignmentAssumptions("preserve-alignment-assumptions-during-inlining",
52 cl::init(true), cl::Hidden,
53 cl::desc("Convert align attributes to assumptions during inlining."));
55 bool llvm::InlineFunction(CallInst *CI, InlineFunctionInfo &IFI,
56 bool InsertLifetime) {
57 return InlineFunction(CallSite(CI), IFI, InsertLifetime);
59 bool llvm::InlineFunction(InvokeInst *II, InlineFunctionInfo &IFI,
60 bool InsertLifetime) {
61 return InlineFunction(CallSite(II), IFI, InsertLifetime);
65 /// A class for recording information about inlining through an invoke.
66 class InvokeInliningInfo {
67 BasicBlock *OuterResumeDest; ///< Destination of the invoke's unwind.
68 BasicBlock *InnerResumeDest; ///< Destination for the callee's resume.
69 LandingPadInst *CallerLPad; ///< LandingPadInst associated with the invoke.
70 PHINode *InnerEHValuesPHI; ///< PHI for EH values from landingpad insts.
71 SmallVector<Value*, 8> UnwindDestPHIValues;
74 InvokeInliningInfo(InvokeInst *II)
75 : OuterResumeDest(II->getUnwindDest()), InnerResumeDest(nullptr),
76 CallerLPad(nullptr), InnerEHValuesPHI(nullptr) {
77 // If there are PHI nodes in the unwind destination block, we need to keep
78 // track of which values came into them from the invoke before removing
79 // the edge from this block.
80 llvm::BasicBlock *InvokeBB = II->getParent();
81 BasicBlock::iterator I = OuterResumeDest->begin();
82 for (; isa<PHINode>(I); ++I) {
83 // Save the value to use for this edge.
84 PHINode *PHI = cast<PHINode>(I);
85 UnwindDestPHIValues.push_back(PHI->getIncomingValueForBlock(InvokeBB));
88 CallerLPad = cast<LandingPadInst>(I);
91 /// getOuterResumeDest - The outer unwind destination is the target of
92 /// unwind edges introduced for calls within the inlined function.
93 BasicBlock *getOuterResumeDest() const {
94 return OuterResumeDest;
97 BasicBlock *getInnerResumeDest();
99 LandingPadInst *getLandingPadInst() const { return CallerLPad; }
101 /// forwardResume - Forward the 'resume' instruction to the caller's landing
102 /// pad block. When the landing pad block has only one predecessor, this is
103 /// a simple branch. When there is more than one predecessor, we need to
104 /// split the landing pad block after the landingpad instruction and jump
106 void forwardResume(ResumeInst *RI,
107 SmallPtrSetImpl<LandingPadInst*> &InlinedLPads);
109 /// addIncomingPHIValuesFor - Add incoming-PHI values to the unwind
110 /// destination block for the given basic block, using the values for the
111 /// original invoke's source block.
112 void addIncomingPHIValuesFor(BasicBlock *BB) const {
113 addIncomingPHIValuesForInto(BB, OuterResumeDest);
116 void addIncomingPHIValuesForInto(BasicBlock *src, BasicBlock *dest) const {
117 BasicBlock::iterator I = dest->begin();
118 for (unsigned i = 0, e = UnwindDestPHIValues.size(); i != e; ++i, ++I) {
119 PHINode *phi = cast<PHINode>(I);
120 phi->addIncoming(UnwindDestPHIValues[i], src);
126 /// getInnerResumeDest - Get or create a target for the branch from ResumeInsts.
127 BasicBlock *InvokeInliningInfo::getInnerResumeDest() {
128 if (InnerResumeDest) return InnerResumeDest;
130 // Split the landing pad.
131 BasicBlock::iterator SplitPoint = CallerLPad; ++SplitPoint;
133 OuterResumeDest->splitBasicBlock(SplitPoint,
134 OuterResumeDest->getName() + ".body");
136 // The number of incoming edges we expect to the inner landing pad.
137 const unsigned PHICapacity = 2;
139 // Create corresponding new PHIs for all the PHIs in the outer landing pad.
140 BasicBlock::iterator InsertPoint = InnerResumeDest->begin();
141 BasicBlock::iterator I = OuterResumeDest->begin();
142 for (unsigned i = 0, e = UnwindDestPHIValues.size(); i != e; ++i, ++I) {
143 PHINode *OuterPHI = cast<PHINode>(I);
144 PHINode *InnerPHI = PHINode::Create(OuterPHI->getType(), PHICapacity,
145 OuterPHI->getName() + ".lpad-body",
147 OuterPHI->replaceAllUsesWith(InnerPHI);
148 InnerPHI->addIncoming(OuterPHI, OuterResumeDest);
151 // Create a PHI for the exception values.
152 InnerEHValuesPHI = PHINode::Create(CallerLPad->getType(), PHICapacity,
153 "eh.lpad-body", InsertPoint);
154 CallerLPad->replaceAllUsesWith(InnerEHValuesPHI);
155 InnerEHValuesPHI->addIncoming(CallerLPad, OuterResumeDest);
158 return InnerResumeDest;
161 /// forwardResume - Forward the 'resume' instruction to the caller's landing pad
162 /// block. When the landing pad block has only one predecessor, this is a simple
163 /// branch. When there is more than one predecessor, we need to split the
164 /// landing pad block after the landingpad instruction and jump to there.
165 void InvokeInliningInfo::forwardResume(ResumeInst *RI,
166 SmallPtrSetImpl<LandingPadInst*> &InlinedLPads) {
167 BasicBlock *Dest = getInnerResumeDest();
168 BasicBlock *Src = RI->getParent();
170 BranchInst::Create(Dest, Src);
172 // Update the PHIs in the destination. They were inserted in an order which
174 addIncomingPHIValuesForInto(Src, Dest);
176 InnerEHValuesPHI->addIncoming(RI->getOperand(0), Src);
177 RI->eraseFromParent();
180 /// HandleCallsInBlockInlinedThroughInvoke - When we inline a basic block into
181 /// an invoke, we have to turn all of the calls that can throw into
182 /// invokes. This function analyze BB to see if there are any calls, and if so,
183 /// it rewrites them to be invokes that jump to InvokeDest and fills in the PHI
184 /// nodes in that block with the values specified in InvokeDestPHIValues.
185 static void HandleCallsInBlockInlinedThroughInvoke(BasicBlock *BB,
186 InvokeInliningInfo &Invoke) {
187 for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) {
188 Instruction *I = BBI++;
190 // We only need to check for function calls: inlined invoke
191 // instructions require no special handling.
192 CallInst *CI = dyn_cast<CallInst>(I);
194 // If this call cannot unwind, don't convert it to an invoke.
195 // Inline asm calls cannot throw.
196 if (!CI || CI->doesNotThrow() || isa<InlineAsm>(CI->getCalledValue()))
199 // Convert this function call into an invoke instruction. First, split the
201 BasicBlock *Split = BB->splitBasicBlock(CI, CI->getName()+".noexc");
203 // Delete the unconditional branch inserted by splitBasicBlock
204 BB->getInstList().pop_back();
206 // Create the new invoke instruction.
207 ImmutableCallSite CS(CI);
208 SmallVector<Value*, 8> InvokeArgs(CS.arg_begin(), CS.arg_end());
209 InvokeInst *II = InvokeInst::Create(CI->getCalledValue(), Split,
210 Invoke.getOuterResumeDest(),
211 InvokeArgs, CI->getName(), BB);
212 II->setDebugLoc(CI->getDebugLoc());
213 II->setCallingConv(CI->getCallingConv());
214 II->setAttributes(CI->getAttributes());
216 // Make sure that anything using the call now uses the invoke! This also
217 // updates the CallGraph if present, because it uses a WeakVH.
218 CI->replaceAllUsesWith(II);
220 // Delete the original call
221 Split->getInstList().pop_front();
223 // Update any PHI nodes in the exceptional block to indicate that there is
224 // now a new entry in them.
225 Invoke.addIncomingPHIValuesFor(BB);
230 /// HandleInlinedInvoke - If we inlined an invoke site, we need to convert calls
231 /// in the body of the inlined function into invokes.
233 /// II is the invoke instruction being inlined. FirstNewBlock is the first
234 /// block of the inlined code (the last block is the end of the function),
235 /// and InlineCodeInfo is information about the code that got inlined.
236 static void HandleInlinedInvoke(InvokeInst *II, BasicBlock *FirstNewBlock,
237 ClonedCodeInfo &InlinedCodeInfo) {
238 BasicBlock *InvokeDest = II->getUnwindDest();
240 Function *Caller = FirstNewBlock->getParent();
242 // The inlined code is currently at the end of the function, scan from the
243 // start of the inlined code to its end, checking for stuff we need to
245 InvokeInliningInfo Invoke(II);
247 // Get all of the inlined landing pad instructions.
248 SmallPtrSet<LandingPadInst*, 16> InlinedLPads;
249 for (Function::iterator I = FirstNewBlock, E = Caller->end(); I != E; ++I)
250 if (InvokeInst *II = dyn_cast<InvokeInst>(I->getTerminator()))
251 InlinedLPads.insert(II->getLandingPadInst());
253 // Append the clauses from the outer landing pad instruction into the inlined
254 // landing pad instructions.
255 LandingPadInst *OuterLPad = Invoke.getLandingPadInst();
256 for (LandingPadInst *InlinedLPad : InlinedLPads) {
257 unsigned OuterNum = OuterLPad->getNumClauses();
258 InlinedLPad->reserveClauses(OuterNum);
259 for (unsigned OuterIdx = 0; OuterIdx != OuterNum; ++OuterIdx)
260 InlinedLPad->addClause(OuterLPad->getClause(OuterIdx));
261 if (OuterLPad->isCleanup())
262 InlinedLPad->setCleanup(true);
265 for (Function::iterator BB = FirstNewBlock, E = Caller->end(); BB != E; ++BB){
266 if (InlinedCodeInfo.ContainsCalls)
267 HandleCallsInBlockInlinedThroughInvoke(BB, Invoke);
269 // Forward any resumes that are remaining here.
270 if (ResumeInst *RI = dyn_cast<ResumeInst>(BB->getTerminator()))
271 Invoke.forwardResume(RI, InlinedLPads);
274 // Now that everything is happy, we have one final detail. The PHI nodes in
275 // the exception destination block still have entries due to the original
276 // invoke instruction. Eliminate these entries (which might even delete the
278 InvokeDest->removePredecessor(II->getParent());
281 /// CloneAliasScopeMetadata - When inlining a function that contains noalias
282 /// scope metadata, this metadata needs to be cloned so that the inlined blocks
283 /// have different "unqiue scopes" at every call site. Were this not done, then
284 /// aliasing scopes from a function inlined into a caller multiple times could
285 /// not be differentiated (and this would lead to miscompiles because the
286 /// non-aliasing property communicated by the metadata could have
287 /// call-site-specific control dependencies).
288 static void CloneAliasScopeMetadata(CallSite CS, ValueToValueMapTy &VMap) {
289 const Function *CalledFunc = CS.getCalledFunction();
290 SetVector<const MDNode *> MD;
292 // Note: We could only clone the metadata if it is already used in the
293 // caller. I'm omitting that check here because it might confuse
294 // inter-procedural alias analysis passes. We can revisit this if it becomes
295 // an efficiency or overhead problem.
297 for (Function::const_iterator I = CalledFunc->begin(), IE = CalledFunc->end();
299 for (BasicBlock::const_iterator J = I->begin(), JE = I->end(); J != JE; ++J) {
300 if (const MDNode *M = J->getMDNode(LLVMContext::MD_alias_scope))
302 if (const MDNode *M = J->getMDNode(LLVMContext::MD_noalias))
309 // Walk the existing metadata, adding the complete (perhaps cyclic) chain to
311 SmallVector<const Value *, 16> Queue(MD.begin(), MD.end());
312 while (!Queue.empty()) {
313 const MDNode *M = cast<MDNode>(Queue.pop_back_val());
314 for (unsigned i = 0, ie = M->getNumOperands(); i != ie; ++i)
315 if (const MDNode *M1 = dyn_cast<MDNode>(M->getOperand(i)))
320 // Now we have a complete set of all metadata in the chains used to specify
321 // the noalias scopes and the lists of those scopes.
322 SmallVector<MDNode *, 16> DummyNodes;
323 DenseMap<const MDNode *, TrackingVH<MDNode> > MDMap;
324 for (SetVector<const MDNode *>::iterator I = MD.begin(), IE = MD.end();
326 MDNode *Dummy = MDNode::getTemporary(CalledFunc->getContext(), None);
327 DummyNodes.push_back(Dummy);
331 // Create new metadata nodes to replace the dummy nodes, replacing old
332 // metadata references with either a dummy node or an already-created new
334 for (SetVector<const MDNode *>::iterator I = MD.begin(), IE = MD.end();
336 SmallVector<Value *, 4> NewOps;
337 for (unsigned i = 0, ie = (*I)->getNumOperands(); i != ie; ++i) {
338 const Value *V = (*I)->getOperand(i);
339 if (const MDNode *M = dyn_cast<MDNode>(V))
340 NewOps.push_back(MDMap[M]);
342 NewOps.push_back(const_cast<Value *>(V));
345 MDNode *NewM = MDNode::get(CalledFunc->getContext(), NewOps),
348 TempM->replaceAllUsesWith(NewM);
351 // Now replace the metadata in the new inlined instructions with the
352 // repacements from the map.
353 for (ValueToValueMapTy::iterator VMI = VMap.begin(), VMIE = VMap.end();
354 VMI != VMIE; ++VMI) {
358 Instruction *NI = dyn_cast<Instruction>(VMI->second);
362 if (MDNode *M = NI->getMDNode(LLVMContext::MD_alias_scope)) {
363 MDNode *NewMD = MDMap[M];
364 // If the call site also had alias scope metadata (a list of scopes to
365 // which instructions inside it might belong), propagate those scopes to
366 // the inlined instructions.
368 CS.getInstruction()->getMDNode(LLVMContext::MD_alias_scope))
369 NewMD = MDNode::concatenate(NewMD, CSM);
370 NI->setMetadata(LLVMContext::MD_alias_scope, NewMD);
371 } else if (NI->mayReadOrWriteMemory()) {
373 CS.getInstruction()->getMDNode(LLVMContext::MD_alias_scope))
374 NI->setMetadata(LLVMContext::MD_alias_scope, M);
377 if (MDNode *M = NI->getMDNode(LLVMContext::MD_noalias)) {
378 MDNode *NewMD = MDMap[M];
379 // If the call site also had noalias metadata (a list of scopes with
380 // which instructions inside it don't alias), propagate those scopes to
381 // the inlined instructions.
382 if (MDNode *CSM = CS.getInstruction()->getMDNode(LLVMContext::MD_noalias))
383 NewMD = MDNode::concatenate(NewMD, CSM);
384 NI->setMetadata(LLVMContext::MD_noalias, NewMD);
385 } else if (NI->mayReadOrWriteMemory()) {
386 if (MDNode *M = CS.getInstruction()->getMDNode(LLVMContext::MD_noalias))
387 NI->setMetadata(LLVMContext::MD_noalias, M);
391 // Now that everything has been replaced, delete the dummy nodes.
392 for (unsigned i = 0, ie = DummyNodes.size(); i != ie; ++i)
393 MDNode::deleteTemporary(DummyNodes[i]);
396 /// AddAliasScopeMetadata - If the inlined function has noalias arguments, then
397 /// add new alias scopes for each noalias argument, tag the mapped noalias
398 /// parameters with noalias metadata specifying the new scope, and tag all
399 /// non-derived loads, stores and memory intrinsics with the new alias scopes.
400 static void AddAliasScopeMetadata(CallSite CS, ValueToValueMapTy &VMap,
401 const DataLayout *DL, AliasAnalysis *AA) {
402 if (!EnableNoAliasConversion)
405 const Function *CalledFunc = CS.getCalledFunction();
406 SmallVector<const Argument *, 4> NoAliasArgs;
408 for (Function::const_arg_iterator I = CalledFunc->arg_begin(),
409 E = CalledFunc->arg_end(); I != E; ++I) {
410 if (I->hasNoAliasAttr() && !I->hasNUses(0))
411 NoAliasArgs.push_back(I);
414 if (NoAliasArgs.empty())
417 // To do a good job, if a noalias variable is captured, we need to know if
418 // the capture point dominates the particular use we're considering.
420 DT.recalculate(const_cast<Function&>(*CalledFunc));
422 // noalias indicates that pointer values based on the argument do not alias
423 // pointer values which are not based on it. So we add a new "scope" for each
424 // noalias function argument. Accesses using pointers based on that argument
425 // become part of that alias scope, accesses using pointers not based on that
426 // argument are tagged as noalias with that scope.
428 DenseMap<const Argument *, MDNode *> NewScopes;
429 MDBuilder MDB(CalledFunc->getContext());
431 // Create a new scope domain for this function.
433 MDB.createAnonymousAliasScopeDomain(CalledFunc->getName());
434 for (unsigned i = 0, e = NoAliasArgs.size(); i != e; ++i) {
435 const Argument *A = NoAliasArgs[i];
437 std::string Name = CalledFunc->getName();
440 Name += A->getName();
442 Name += ": argument ";
446 // Note: We always create a new anonymous root here. This is true regardless
447 // of the linkage of the callee because the aliasing "scope" is not just a
448 // property of the callee, but also all control dependencies in the caller.
449 MDNode *NewScope = MDB.createAnonymousAliasScope(NewDomain, Name);
450 NewScopes.insert(std::make_pair(A, NewScope));
453 // Iterate over all new instructions in the map; for all memory-access
454 // instructions, add the alias scope metadata.
455 for (ValueToValueMapTy::iterator VMI = VMap.begin(), VMIE = VMap.end();
456 VMI != VMIE; ++VMI) {
457 if (const Instruction *I = dyn_cast<Instruction>(VMI->first)) {
461 Instruction *NI = dyn_cast<Instruction>(VMI->second);
465 bool IsArgMemOnlyCall = false, IsFuncCall = false;
466 SmallVector<const Value *, 2> PtrArgs;
468 if (const LoadInst *LI = dyn_cast<LoadInst>(I))
469 PtrArgs.push_back(LI->getPointerOperand());
470 else if (const StoreInst *SI = dyn_cast<StoreInst>(I))
471 PtrArgs.push_back(SI->getPointerOperand());
472 else if (const VAArgInst *VAAI = dyn_cast<VAArgInst>(I))
473 PtrArgs.push_back(VAAI->getPointerOperand());
474 else if (const AtomicCmpXchgInst *CXI = dyn_cast<AtomicCmpXchgInst>(I))
475 PtrArgs.push_back(CXI->getPointerOperand());
476 else if (const AtomicRMWInst *RMWI = dyn_cast<AtomicRMWInst>(I))
477 PtrArgs.push_back(RMWI->getPointerOperand());
478 else if (ImmutableCallSite ICS = ImmutableCallSite(I)) {
479 // If we know that the call does not access memory, then we'll still
480 // know that about the inlined clone of this call site, and we don't
481 // need to add metadata.
482 if (ICS.doesNotAccessMemory())
487 AliasAnalysis::ModRefBehavior MRB = AA->getModRefBehavior(ICS);
488 if (MRB == AliasAnalysis::OnlyAccessesArgumentPointees ||
489 MRB == AliasAnalysis::OnlyReadsArgumentPointees)
490 IsArgMemOnlyCall = true;
493 for (ImmutableCallSite::arg_iterator AI = ICS.arg_begin(),
494 AE = ICS.arg_end(); AI != AE; ++AI) {
495 // We need to check the underlying objects of all arguments, not just
496 // the pointer arguments, because we might be passing pointers as
498 // However, if we know that the call only accesses pointer arguments,
499 // then we only need to check the pointer arguments.
500 if (IsArgMemOnlyCall && !(*AI)->getType()->isPointerTy())
503 PtrArgs.push_back(*AI);
507 // If we found no pointers, then this instruction is not suitable for
508 // pairing with an instruction to receive aliasing metadata.
509 // However, if this is a call, this we might just alias with none of the
510 // noalias arguments.
511 if (PtrArgs.empty() && !IsFuncCall)
514 // It is possible that there is only one underlying object, but you
515 // need to go through several PHIs to see it, and thus could be
516 // repeated in the Objects list.
517 SmallPtrSet<const Value *, 4> ObjSet;
518 SmallVector<Value *, 4> Scopes, NoAliases;
520 SmallSetVector<const Argument *, 4> NAPtrArgs;
521 for (unsigned i = 0, ie = PtrArgs.size(); i != ie; ++i) {
522 SmallVector<Value *, 4> Objects;
523 GetUnderlyingObjects(const_cast<Value*>(PtrArgs[i]),
524 Objects, DL, /* MaxLookup = */ 0);
526 for (Value *O : Objects)
530 // Figure out if we're derived from anything that is not a noalias
532 bool CanDeriveViaCapture = false, UsesAliasingPtr = false;
533 for (const Value *V : ObjSet) {
534 // Is this value a constant that cannot be derived from any pointer
535 // value (we need to exclude constant expressions, for example, that
536 // are formed from arithmetic on global symbols).
537 bool IsNonPtrConst = isa<ConstantInt>(V) || isa<ConstantFP>(V) ||
538 isa<ConstantPointerNull>(V) ||
539 isa<ConstantDataVector>(V) || isa<UndefValue>(V);
543 // If this is anything other than a noalias argument, then we cannot
544 // completely describe the aliasing properties using alias.scope
545 // metadata (and, thus, won't add any).
546 if (const Argument *A = dyn_cast<Argument>(V)) {
547 if (!A->hasNoAliasAttr())
548 UsesAliasingPtr = true;
550 UsesAliasingPtr = true;
553 // If this is not some identified function-local object (which cannot
554 // directly alias a noalias argument), or some other argument (which,
555 // by definition, also cannot alias a noalias argument), then we could
556 // alias a noalias argument that has been captured).
557 if (!isa<Argument>(V) &&
558 !isIdentifiedFunctionLocal(const_cast<Value*>(V)))
559 CanDeriveViaCapture = true;
562 // A function call can always get captured noalias pointers (via other
563 // parameters, globals, etc.).
564 if (IsFuncCall && !IsArgMemOnlyCall)
565 CanDeriveViaCapture = true;
567 // First, we want to figure out all of the sets with which we definitely
568 // don't alias. Iterate over all noalias set, and add those for which:
569 // 1. The noalias argument is not in the set of objects from which we
570 // definitely derive.
571 // 2. The noalias argument has not yet been captured.
572 // An arbitrary function that might load pointers could see captured
573 // noalias arguments via other noalias arguments or globals, and so we
574 // must always check for prior capture.
575 for (const Argument *A : NoAliasArgs) {
576 if (!ObjSet.count(A) && (!CanDeriveViaCapture ||
577 // It might be tempting to skip the
578 // PointerMayBeCapturedBefore check if
579 // A->hasNoCaptureAttr() is true, but this is
580 // incorrect because nocapture only guarantees
581 // that no copies outlive the function, not
582 // that the value cannot be locally captured.
583 !PointerMayBeCapturedBefore(A,
584 /* ReturnCaptures */ false,
585 /* StoreCaptures */ false, I, &DT)))
586 NoAliases.push_back(NewScopes[A]);
589 if (!NoAliases.empty())
590 NI->setMetadata(LLVMContext::MD_noalias,
592 NI->getMDNode(LLVMContext::MD_noalias),
593 MDNode::get(CalledFunc->getContext(), NoAliases)));
595 // Next, we want to figure out all of the sets to which we might belong.
596 // We might belong to a set if the noalias argument is in the set of
597 // underlying objects. If there is some non-noalias argument in our list
598 // of underlying objects, then we cannot add a scope because the fact
599 // that some access does not alias with any set of our noalias arguments
600 // cannot itself guarantee that it does not alias with this access
601 // (because there is some pointer of unknown origin involved and the
602 // other access might also depend on this pointer). We also cannot add
603 // scopes to arbitrary functions unless we know they don't access any
604 // non-parameter pointer-values.
605 bool CanAddScopes = !UsesAliasingPtr;
606 if (CanAddScopes && IsFuncCall)
607 CanAddScopes = IsArgMemOnlyCall;
610 for (const Argument *A : NoAliasArgs) {
612 Scopes.push_back(NewScopes[A]);
617 LLVMContext::MD_alias_scope,
618 MDNode::concatenate(NI->getMDNode(LLVMContext::MD_alias_scope),
619 MDNode::get(CalledFunc->getContext(), Scopes)));
624 /// If the inlined function has non-byval align arguments, then
625 /// add @llvm.assume-based alignment assumptions to preserve this information.
626 static void AddAlignmentAssumptions(CallSite CS, InlineFunctionInfo &IFI) {
627 if (!PreserveAlignmentAssumptions || !IFI.DL)
630 // To avoid inserting redundant assumptions, we should check for assumptions
631 // already in the caller. To do this, we might need a DT of the caller.
633 bool DTCalculated = false;
635 const Function *CalledFunc = CS.getCalledFunction();
636 for (Function::const_arg_iterator I = CalledFunc->arg_begin(),
637 E = CalledFunc->arg_end(); I != E; ++I) {
638 unsigned Align = I->getType()->isPointerTy() ? I->getParamAlignment() : 0;
639 if (Align && !I->hasByValOrInAllocaAttr() && !I->hasNUses(0)) {
641 DT.recalculate(const_cast<Function&>(*CS.getInstruction()->getParent()
646 // If we can already prove the asserted alignment in the context of the
647 // caller, then don't bother inserting the assumption.
648 Value *Arg = CS.getArgument(I->getArgNo());
649 if (getKnownAlignment(Arg, IFI.DL, IFI.AT, CS.getInstruction(),
653 IRBuilder<>(CS.getInstruction()).CreateAlignmentAssumption(*IFI.DL, Arg,
659 /// UpdateCallGraphAfterInlining - Once we have cloned code over from a callee
660 /// into the caller, update the specified callgraph to reflect the changes we
661 /// made. Note that it's possible that not all code was copied over, so only
662 /// some edges of the callgraph may remain.
663 static void UpdateCallGraphAfterInlining(CallSite CS,
664 Function::iterator FirstNewBlock,
665 ValueToValueMapTy &VMap,
666 InlineFunctionInfo &IFI) {
667 CallGraph &CG = *IFI.CG;
668 const Function *Caller = CS.getInstruction()->getParent()->getParent();
669 const Function *Callee = CS.getCalledFunction();
670 CallGraphNode *CalleeNode = CG[Callee];
671 CallGraphNode *CallerNode = CG[Caller];
673 // Since we inlined some uninlined call sites in the callee into the caller,
674 // add edges from the caller to all of the callees of the callee.
675 CallGraphNode::iterator I = CalleeNode->begin(), E = CalleeNode->end();
677 // Consider the case where CalleeNode == CallerNode.
678 CallGraphNode::CalledFunctionsVector CallCache;
679 if (CalleeNode == CallerNode) {
680 CallCache.assign(I, E);
681 I = CallCache.begin();
685 for (; I != E; ++I) {
686 const Value *OrigCall = I->first;
688 ValueToValueMapTy::iterator VMI = VMap.find(OrigCall);
689 // Only copy the edge if the call was inlined!
690 if (VMI == VMap.end() || VMI->second == nullptr)
693 // If the call was inlined, but then constant folded, there is no edge to
694 // add. Check for this case.
695 Instruction *NewCall = dyn_cast<Instruction>(VMI->second);
696 if (!NewCall) continue;
698 // Remember that this call site got inlined for the client of
700 IFI.InlinedCalls.push_back(NewCall);
702 // It's possible that inlining the callsite will cause it to go from an
703 // indirect to a direct call by resolving a function pointer. If this
704 // happens, set the callee of the new call site to a more precise
705 // destination. This can also happen if the call graph node of the caller
706 // was just unnecessarily imprecise.
707 if (!I->second->getFunction())
708 if (Function *F = CallSite(NewCall).getCalledFunction()) {
709 // Indirect call site resolved to direct call.
710 CallerNode->addCalledFunction(CallSite(NewCall), CG[F]);
715 CallerNode->addCalledFunction(CallSite(NewCall), I->second);
718 // Update the call graph by deleting the edge from Callee to Caller. We must
719 // do this after the loop above in case Caller and Callee are the same.
720 CallerNode->removeCallEdgeFor(CS);
723 static void HandleByValArgumentInit(Value *Dst, Value *Src, Module *M,
724 BasicBlock *InsertBlock,
725 InlineFunctionInfo &IFI) {
726 Type *AggTy = cast<PointerType>(Src->getType())->getElementType();
727 IRBuilder<> Builder(InsertBlock->begin());
730 if (IFI.DL == nullptr)
731 Size = ConstantExpr::getSizeOf(AggTy);
733 Size = Builder.getInt64(IFI.DL->getTypeStoreSize(AggTy));
735 // Always generate a memcpy of alignment 1 here because we don't know
736 // the alignment of the src pointer. Other optimizations can infer
738 Builder.CreateMemCpy(Dst, Src, Size, /*Align=*/1);
741 /// HandleByValArgument - When inlining a call site that has a byval argument,
742 /// we have to make the implicit memcpy explicit by adding it.
743 static Value *HandleByValArgument(Value *Arg, Instruction *TheCall,
744 const Function *CalledFunc,
745 InlineFunctionInfo &IFI,
746 unsigned ByValAlignment,
747 bool &AddedNewAllocas) {
748 PointerType *ArgTy = cast<PointerType>(Arg->getType());
749 Type *AggTy = ArgTy->getElementType();
751 // If the called function is readonly, then it could not mutate the caller's
752 // copy of the byval'd memory. In this case, it is safe to elide the copy and
754 if (CalledFunc->onlyReadsMemory()) {
755 // If the byval argument has a specified alignment that is greater than the
756 // passed in pointer, then we either have to round up the input pointer or
757 // give up on this transformation.
758 if (ByValAlignment <= 1) // 0 = unspecified, 1 = no particular alignment.
761 // If the pointer is already known to be sufficiently aligned, or if we can
762 // round it up to a larger alignment, then we don't need a temporary.
763 if (getOrEnforceKnownAlignment(Arg, ByValAlignment,
764 IFI.DL, IFI.AT, TheCall) >= ByValAlignment)
767 // Otherwise, we have to make a memcpy to get a safe alignment. This is bad
768 // for code quality, but rarely happens and is required for correctness.
771 // Create the alloca. If we have DataLayout, use nice alignment.
774 Align = IFI.DL->getPrefTypeAlignment(AggTy);
776 // If the byval had an alignment specified, we *must* use at least that
777 // alignment, as it is required by the byval argument (and uses of the
778 // pointer inside the callee).
779 Align = std::max(Align, ByValAlignment);
781 Function *Caller = TheCall->getParent()->getParent();
783 Value *NewAlloca = new AllocaInst(AggTy, nullptr, Align, Arg->getName(),
784 &*Caller->begin()->begin());
785 IFI.StaticAllocas.push_back(cast<AllocaInst>(NewAlloca));
787 // Uses of the argument in the function should use our new alloca
789 AddedNewAllocas = true;
793 // isUsedByLifetimeMarker - Check whether this Value is used by a lifetime
795 static bool isUsedByLifetimeMarker(Value *V) {
796 for (User *U : V->users()) {
797 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(U)) {
798 switch (II->getIntrinsicID()) {
800 case Intrinsic::lifetime_start:
801 case Intrinsic::lifetime_end:
809 // hasLifetimeMarkers - Check whether the given alloca already has
810 // lifetime.start or lifetime.end intrinsics.
811 static bool hasLifetimeMarkers(AllocaInst *AI) {
812 Type *Ty = AI->getType();
813 Type *Int8PtrTy = Type::getInt8PtrTy(Ty->getContext(),
814 Ty->getPointerAddressSpace());
816 return isUsedByLifetimeMarker(AI);
818 // Do a scan to find all the casts to i8*.
819 for (User *U : AI->users()) {
820 if (U->getType() != Int8PtrTy) continue;
821 if (U->stripPointerCasts() != AI) continue;
822 if (isUsedByLifetimeMarker(U))
828 /// updateInlinedAtInfo - Helper function used by fixupLineNumbers to
829 /// recursively update InlinedAtEntry of a DebugLoc.
830 static DebugLoc updateInlinedAtInfo(const DebugLoc &DL,
831 const DebugLoc &InlinedAtDL,
833 if (MDNode *IA = DL.getInlinedAt(Ctx)) {
834 DebugLoc NewInlinedAtDL
835 = updateInlinedAtInfo(DebugLoc::getFromDILocation(IA), InlinedAtDL, Ctx);
836 return DebugLoc::get(DL.getLine(), DL.getCol(), DL.getScope(Ctx),
837 NewInlinedAtDL.getAsMDNode(Ctx));
840 return DebugLoc::get(DL.getLine(), DL.getCol(), DL.getScope(Ctx),
841 InlinedAtDL.getAsMDNode(Ctx));
844 /// fixupLineNumbers - Update inlined instructions' line numbers to
845 /// to encode location where these instructions are inlined.
846 static void fixupLineNumbers(Function *Fn, Function::iterator FI,
847 Instruction *TheCall) {
848 DebugLoc TheCallDL = TheCall->getDebugLoc();
849 if (TheCallDL.isUnknown())
852 for (; FI != Fn->end(); ++FI) {
853 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
855 DebugLoc DL = BI->getDebugLoc();
856 if (DL.isUnknown()) {
857 // If the inlined instruction has no line number, make it look as if it
858 // originates from the call location. This is important for
859 // ((__always_inline__, __nodebug__)) functions which must use caller
860 // location for all instructions in their function body.
862 // Don't update static allocas, as they may get moved later.
863 if (auto *AI = dyn_cast<AllocaInst>(BI))
864 if (isa<Constant>(AI->getArraySize()))
867 BI->setDebugLoc(TheCallDL);
869 BI->setDebugLoc(updateInlinedAtInfo(DL, TheCallDL, BI->getContext()));
870 if (DbgValueInst *DVI = dyn_cast<DbgValueInst>(BI)) {
871 LLVMContext &Ctx = BI->getContext();
872 MDNode *InlinedAt = BI->getDebugLoc().getInlinedAt(Ctx);
873 DVI->setOperand(2, createInlinedVariable(DVI->getVariable(),
881 /// InlineFunction - This function inlines the called function into the basic
882 /// block of the caller. This returns false if it is not possible to inline
883 /// this call. The program is still in a well defined state if this occurs
886 /// Note that this only does one level of inlining. For example, if the
887 /// instruction 'call B' is inlined, and 'B' calls 'C', then the call to 'C' now
888 /// exists in the instruction stream. Similarly this will inline a recursive
889 /// function by one level.
890 bool llvm::InlineFunction(CallSite CS, InlineFunctionInfo &IFI,
891 bool InsertLifetime) {
892 Instruction *TheCall = CS.getInstruction();
893 assert(TheCall->getParent() && TheCall->getParent()->getParent() &&
894 "Instruction not in function!");
896 // If IFI has any state in it, zap it before we fill it in.
899 const Function *CalledFunc = CS.getCalledFunction();
900 if (!CalledFunc || // Can't inline external function or indirect
901 CalledFunc->isDeclaration() || // call, or call to a vararg function!
902 CalledFunc->getFunctionType()->isVarArg()) return false;
904 // If the call to the callee cannot throw, set the 'nounwind' flag on any
905 // calls that we inline.
906 bool MarkNoUnwind = CS.doesNotThrow();
908 BasicBlock *OrigBB = TheCall->getParent();
909 Function *Caller = OrigBB->getParent();
911 // GC poses two hazards to inlining, which only occur when the callee has GC:
912 // 1. If the caller has no GC, then the callee's GC must be propagated to the
914 // 2. If the caller has a differing GC, it is invalid to inline.
915 if (CalledFunc->hasGC()) {
916 if (!Caller->hasGC())
917 Caller->setGC(CalledFunc->getGC());
918 else if (CalledFunc->getGC() != Caller->getGC())
922 // Get the personality function from the callee if it contains a landing pad.
923 Value *CalleePersonality = nullptr;
924 for (Function::const_iterator I = CalledFunc->begin(), E = CalledFunc->end();
926 if (const InvokeInst *II = dyn_cast<InvokeInst>(I->getTerminator())) {
927 const BasicBlock *BB = II->getUnwindDest();
928 const LandingPadInst *LP = BB->getLandingPadInst();
929 CalleePersonality = LP->getPersonalityFn();
933 // Find the personality function used by the landing pads of the caller. If it
934 // exists, then check to see that it matches the personality function used in
936 if (CalleePersonality) {
937 for (Function::const_iterator I = Caller->begin(), E = Caller->end();
939 if (const InvokeInst *II = dyn_cast<InvokeInst>(I->getTerminator())) {
940 const BasicBlock *BB = II->getUnwindDest();
941 const LandingPadInst *LP = BB->getLandingPadInst();
943 // If the personality functions match, then we can perform the
944 // inlining. Otherwise, we can't inline.
945 // TODO: This isn't 100% true. Some personality functions are proper
946 // supersets of others and can be used in place of the other.
947 if (LP->getPersonalityFn() != CalleePersonality)
954 // Get an iterator to the last basic block in the function, which will have
955 // the new function inlined after it.
956 Function::iterator LastBlock = &Caller->back();
958 // Make sure to capture all of the return instructions from the cloned
960 SmallVector<ReturnInst*, 8> Returns;
961 ClonedCodeInfo InlinedFunctionInfo;
962 Function::iterator FirstNewBlock;
963 bool AddedNewAllocas = false;
965 { // Scope to destroy VMap after cloning.
966 ValueToValueMapTy VMap;
967 // Keep a list of pair (dst, src) to emit byval initializations.
968 SmallVector<std::pair<Value*, Value*>, 4> ByValInit;
970 assert(CalledFunc->arg_size() == CS.arg_size() &&
971 "No varargs calls can be inlined!");
973 // Calculate the vector of arguments to pass into the function cloner, which
974 // matches up the formal to the actual argument values.
975 CallSite::arg_iterator AI = CS.arg_begin();
977 for (Function::const_arg_iterator I = CalledFunc->arg_begin(),
978 E = CalledFunc->arg_end(); I != E; ++I, ++AI, ++ArgNo) {
979 Value *ActualArg = *AI;
981 // When byval arguments actually inlined, we need to make the copy implied
982 // by them explicit. However, we don't do this if the callee is readonly
983 // or readnone, because the copy would be unneeded: the callee doesn't
984 // modify the struct.
985 if (CS.isByValArgument(ArgNo)) {
986 ActualArg = HandleByValArgument(ActualArg, TheCall, CalledFunc, IFI,
987 CalledFunc->getParamAlignment(ArgNo+1),
989 if (ActualArg != *AI)
990 ByValInit.push_back(std::make_pair(ActualArg, (Value*) *AI));
996 // Add alignment assumptions if necessary. We do this before the inlined
997 // instructions are actually cloned into the caller so that we can easily
998 // check what will be known at the start of the inlined code.
999 AddAlignmentAssumptions(CS, IFI);
1001 // We want the inliner to prune the code as it copies. We would LOVE to
1002 // have no dead or constant instructions leftover after inlining occurs
1003 // (which can happen, e.g., because an argument was constant), but we'll be
1004 // happy with whatever the cloner can do.
1005 CloneAndPruneFunctionInto(Caller, CalledFunc, VMap,
1006 /*ModuleLevelChanges=*/false, Returns, ".i",
1007 &InlinedFunctionInfo, IFI.DL, TheCall);
1009 // Remember the first block that is newly cloned over.
1010 FirstNewBlock = LastBlock; ++FirstNewBlock;
1012 // Inject byval arguments initialization.
1013 for (std::pair<Value*, Value*> &Init : ByValInit)
1014 HandleByValArgumentInit(Init.first, Init.second, Caller->getParent(),
1015 FirstNewBlock, IFI);
1017 // Update the callgraph if requested.
1019 UpdateCallGraphAfterInlining(CS, FirstNewBlock, VMap, IFI);
1021 // Update inlined instructions' line number information.
1022 fixupLineNumbers(Caller, FirstNewBlock, TheCall);
1024 // Clone existing noalias metadata if necessary.
1025 CloneAliasScopeMetadata(CS, VMap);
1027 // Add noalias metadata if necessary.
1028 AddAliasScopeMetadata(CS, VMap, IFI.DL, IFI.AA);
1030 // FIXME: We could register any cloned assumptions instead of clearing the
1031 // whole function's cache.
1033 IFI.AT->forgetCachedAssumptions(Caller);
1036 // If there are any alloca instructions in the block that used to be the entry
1037 // block for the callee, move them to the entry block of the caller. First
1038 // calculate which instruction they should be inserted before. We insert the
1039 // instructions at the end of the current alloca list.
1041 BasicBlock::iterator InsertPoint = Caller->begin()->begin();
1042 for (BasicBlock::iterator I = FirstNewBlock->begin(),
1043 E = FirstNewBlock->end(); I != E; ) {
1044 AllocaInst *AI = dyn_cast<AllocaInst>(I++);
1047 // If the alloca is now dead, remove it. This often occurs due to code
1049 if (AI->use_empty()) {
1050 AI->eraseFromParent();
1054 if (!isa<Constant>(AI->getArraySize()))
1057 // Keep track of the static allocas that we inline into the caller.
1058 IFI.StaticAllocas.push_back(AI);
1060 // Scan for the block of allocas that we can move over, and move them
1062 while (isa<AllocaInst>(I) &&
1063 isa<Constant>(cast<AllocaInst>(I)->getArraySize())) {
1064 IFI.StaticAllocas.push_back(cast<AllocaInst>(I));
1068 // Transfer all of the allocas over in a block. Using splice means
1069 // that the instructions aren't removed from the symbol table, then
1071 Caller->getEntryBlock().getInstList().splice(InsertPoint,
1072 FirstNewBlock->getInstList(),
1077 bool InlinedMustTailCalls = false;
1078 if (InlinedFunctionInfo.ContainsCalls) {
1079 CallInst::TailCallKind CallSiteTailKind = CallInst::TCK_None;
1080 if (CallInst *CI = dyn_cast<CallInst>(TheCall))
1081 CallSiteTailKind = CI->getTailCallKind();
1083 for (Function::iterator BB = FirstNewBlock, E = Caller->end(); BB != E;
1085 for (Instruction &I : *BB) {
1086 CallInst *CI = dyn_cast<CallInst>(&I);
1090 // We need to reduce the strength of any inlined tail calls. For
1091 // musttail, we have to avoid introducing potential unbounded stack
1092 // growth. For example, if functions 'f' and 'g' are mutually recursive
1093 // with musttail, we can inline 'g' into 'f' so long as we preserve
1094 // musttail on the cloned call to 'f'. If either the inlined call site
1095 // or the cloned call site is *not* musttail, the program already has
1096 // one frame of stack growth, so it's safe to remove musttail. Here is
1097 // a table of example transformations:
1099 // f -> musttail g -> musttail f ==> f -> musttail f
1100 // f -> musttail g -> tail f ==> f -> tail f
1101 // f -> g -> musttail f ==> f -> f
1102 // f -> g -> tail f ==> f -> f
1104 // If an alloca was introduced in the frame due to a byval parameter
1105 // being passed to a subsequent call, tail calls must have the tail
1106 // stripped as they may not access variables in the caller's stack.
1107 // A single alloca ripples through out as the alloca may be aliased by
1108 // bitcasts or may escape and be mutated outside of the function.
1109 CallInst::TailCallKind ChildTCK = CI->getTailCallKind();
1110 ChildTCK = std::min(CallSiteTailKind, ChildTCK);
1111 if (AddedNewAllocas)
1112 CI->setTailCallKind(CallInst::TCK_None);
1114 CI->setTailCallKind(ChildTCK);
1115 InlinedMustTailCalls |= CI->isMustTailCall();
1117 // Calls inlined through a 'nounwind' call site should be marked
1120 CI->setDoesNotThrow();
1125 // Leave lifetime markers for the static alloca's, scoping them to the
1126 // function we just inlined.
1127 if (InsertLifetime && !IFI.StaticAllocas.empty()) {
1128 IRBuilder<> builder(FirstNewBlock->begin());
1129 for (unsigned ai = 0, ae = IFI.StaticAllocas.size(); ai != ae; ++ai) {
1130 AllocaInst *AI = IFI.StaticAllocas[ai];
1132 // If the alloca is already scoped to something smaller than the whole
1133 // function then there's no need to add redundant, less accurate markers.
1134 if (hasLifetimeMarkers(AI))
1137 // Try to determine the size of the allocation.
1138 ConstantInt *AllocaSize = nullptr;
1139 if (ConstantInt *AIArraySize =
1140 dyn_cast<ConstantInt>(AI->getArraySize())) {
1142 Type *AllocaType = AI->getAllocatedType();
1143 uint64_t AllocaTypeSize = IFI.DL->getTypeAllocSize(AllocaType);
1144 uint64_t AllocaArraySize = AIArraySize->getLimitedValue();
1145 assert(AllocaArraySize > 0 && "array size of AllocaInst is zero");
1146 // Check that array size doesn't saturate uint64_t and doesn't
1147 // overflow when it's multiplied by type size.
1148 if (AllocaArraySize != ~0ULL &&
1149 UINT64_MAX / AllocaArraySize >= AllocaTypeSize) {
1150 AllocaSize = ConstantInt::get(Type::getInt64Ty(AI->getContext()),
1151 AllocaArraySize * AllocaTypeSize);
1156 builder.CreateLifetimeStart(AI, AllocaSize);
1157 for (ReturnInst *RI : Returns) {
1158 // Don't insert llvm.lifetime.end calls between a musttail call and a
1159 // return. The return kills all local allocas.
1160 if (InlinedMustTailCalls &&
1161 RI->getParent()->getTerminatingMustTailCall())
1163 IRBuilder<>(RI).CreateLifetimeEnd(AI, AllocaSize);
1168 // If the inlined code contained dynamic alloca instructions, wrap the inlined
1169 // code with llvm.stacksave/llvm.stackrestore intrinsics.
1170 if (InlinedFunctionInfo.ContainsDynamicAllocas) {
1171 Module *M = Caller->getParent();
1172 // Get the two intrinsics we care about.
1173 Function *StackSave = Intrinsic::getDeclaration(M, Intrinsic::stacksave);
1174 Function *StackRestore=Intrinsic::getDeclaration(M,Intrinsic::stackrestore);
1176 // Insert the llvm.stacksave.
1177 CallInst *SavedPtr = IRBuilder<>(FirstNewBlock, FirstNewBlock->begin())
1178 .CreateCall(StackSave, "savedstack");
1180 // Insert a call to llvm.stackrestore before any return instructions in the
1181 // inlined function.
1182 for (ReturnInst *RI : Returns) {
1183 // Don't insert llvm.stackrestore calls between a musttail call and a
1184 // return. The return will restore the stack pointer.
1185 if (InlinedMustTailCalls && RI->getParent()->getTerminatingMustTailCall())
1187 IRBuilder<>(RI).CreateCall(StackRestore, SavedPtr);
1191 // If we are inlining for an invoke instruction, we must make sure to rewrite
1192 // any call instructions into invoke instructions.
1193 if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall))
1194 HandleInlinedInvoke(II, FirstNewBlock, InlinedFunctionInfo);
1196 // Handle any inlined musttail call sites. In order for a new call site to be
1197 // musttail, the source of the clone and the inlined call site must have been
1198 // musttail. Therefore it's safe to return without merging control into the
1200 if (InlinedMustTailCalls) {
1201 // Check if we need to bitcast the result of any musttail calls.
1202 Type *NewRetTy = Caller->getReturnType();
1203 bool NeedBitCast = !TheCall->use_empty() && TheCall->getType() != NewRetTy;
1205 // Handle the returns preceded by musttail calls separately.
1206 SmallVector<ReturnInst *, 8> NormalReturns;
1207 for (ReturnInst *RI : Returns) {
1208 CallInst *ReturnedMustTail =
1209 RI->getParent()->getTerminatingMustTailCall();
1210 if (!ReturnedMustTail) {
1211 NormalReturns.push_back(RI);
1217 // Delete the old return and any preceding bitcast.
1218 BasicBlock *CurBB = RI->getParent();
1219 auto *OldCast = dyn_cast_or_null<BitCastInst>(RI->getReturnValue());
1220 RI->eraseFromParent();
1222 OldCast->eraseFromParent();
1224 // Insert a new bitcast and return with the right type.
1225 IRBuilder<> Builder(CurBB);
1226 Builder.CreateRet(Builder.CreateBitCast(ReturnedMustTail, NewRetTy));
1229 // Leave behind the normal returns so we can merge control flow.
1230 std::swap(Returns, NormalReturns);
1233 // If we cloned in _exactly one_ basic block, and if that block ends in a
1234 // return instruction, we splice the body of the inlined callee directly into
1235 // the calling basic block.
1236 if (Returns.size() == 1 && std::distance(FirstNewBlock, Caller->end()) == 1) {
1237 // Move all of the instructions right before the call.
1238 OrigBB->getInstList().splice(TheCall, FirstNewBlock->getInstList(),
1239 FirstNewBlock->begin(), FirstNewBlock->end());
1240 // Remove the cloned basic block.
1241 Caller->getBasicBlockList().pop_back();
1243 // If the call site was an invoke instruction, add a branch to the normal
1245 if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall)) {
1246 BranchInst *NewBr = BranchInst::Create(II->getNormalDest(), TheCall);
1247 NewBr->setDebugLoc(Returns[0]->getDebugLoc());
1250 // If the return instruction returned a value, replace uses of the call with
1251 // uses of the returned value.
1252 if (!TheCall->use_empty()) {
1253 ReturnInst *R = Returns[0];
1254 if (TheCall == R->getReturnValue())
1255 TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType()));
1257 TheCall->replaceAllUsesWith(R->getReturnValue());
1259 // Since we are now done with the Call/Invoke, we can delete it.
1260 TheCall->eraseFromParent();
1262 // Since we are now done with the return instruction, delete it also.
1263 Returns[0]->eraseFromParent();
1265 // We are now done with the inlining.
1269 // Otherwise, we have the normal case, of more than one block to inline or
1270 // multiple return sites.
1272 // We want to clone the entire callee function into the hole between the
1273 // "starter" and "ender" blocks. How we accomplish this depends on whether
1274 // this is an invoke instruction or a call instruction.
1275 BasicBlock *AfterCallBB;
1276 BranchInst *CreatedBranchToNormalDest = nullptr;
1277 if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall)) {
1279 // Add an unconditional branch to make this look like the CallInst case...
1280 CreatedBranchToNormalDest = BranchInst::Create(II->getNormalDest(), TheCall);
1282 // Split the basic block. This guarantees that no PHI nodes will have to be
1283 // updated due to new incoming edges, and make the invoke case more
1284 // symmetric to the call case.
1285 AfterCallBB = OrigBB->splitBasicBlock(CreatedBranchToNormalDest,
1286 CalledFunc->getName()+".exit");
1288 } else { // It's a call
1289 // If this is a call instruction, we need to split the basic block that
1290 // the call lives in.
1292 AfterCallBB = OrigBB->splitBasicBlock(TheCall,
1293 CalledFunc->getName()+".exit");
1296 // Change the branch that used to go to AfterCallBB to branch to the first
1297 // basic block of the inlined function.
1299 TerminatorInst *Br = OrigBB->getTerminator();
1300 assert(Br && Br->getOpcode() == Instruction::Br &&
1301 "splitBasicBlock broken!");
1302 Br->setOperand(0, FirstNewBlock);
1305 // Now that the function is correct, make it a little bit nicer. In
1306 // particular, move the basic blocks inserted from the end of the function
1307 // into the space made by splitting the source basic block.
1308 Caller->getBasicBlockList().splice(AfterCallBB, Caller->getBasicBlockList(),
1309 FirstNewBlock, Caller->end());
1311 // Handle all of the return instructions that we just cloned in, and eliminate
1312 // any users of the original call/invoke instruction.
1313 Type *RTy = CalledFunc->getReturnType();
1315 PHINode *PHI = nullptr;
1316 if (Returns.size() > 1) {
1317 // The PHI node should go at the front of the new basic block to merge all
1318 // possible incoming values.
1319 if (!TheCall->use_empty()) {
1320 PHI = PHINode::Create(RTy, Returns.size(), TheCall->getName(),
1321 AfterCallBB->begin());
1322 // Anything that used the result of the function call should now use the
1323 // PHI node as their operand.
1324 TheCall->replaceAllUsesWith(PHI);
1327 // Loop over all of the return instructions adding entries to the PHI node
1330 for (unsigned i = 0, e = Returns.size(); i != e; ++i) {
1331 ReturnInst *RI = Returns[i];
1332 assert(RI->getReturnValue()->getType() == PHI->getType() &&
1333 "Ret value not consistent in function!");
1334 PHI->addIncoming(RI->getReturnValue(), RI->getParent());
1339 // Add a branch to the merge points and remove return instructions.
1341 for (unsigned i = 0, e = Returns.size(); i != e; ++i) {
1342 ReturnInst *RI = Returns[i];
1343 BranchInst* BI = BranchInst::Create(AfterCallBB, RI);
1344 Loc = RI->getDebugLoc();
1345 BI->setDebugLoc(Loc);
1346 RI->eraseFromParent();
1348 // We need to set the debug location to *somewhere* inside the
1349 // inlined function. The line number may be nonsensical, but the
1350 // instruction will at least be associated with the right
1352 if (CreatedBranchToNormalDest)
1353 CreatedBranchToNormalDest->setDebugLoc(Loc);
1354 } else if (!Returns.empty()) {
1355 // Otherwise, if there is exactly one return value, just replace anything
1356 // using the return value of the call with the computed value.
1357 if (!TheCall->use_empty()) {
1358 if (TheCall == Returns[0]->getReturnValue())
1359 TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType()));
1361 TheCall->replaceAllUsesWith(Returns[0]->getReturnValue());
1364 // Update PHI nodes that use the ReturnBB to use the AfterCallBB.
1365 BasicBlock *ReturnBB = Returns[0]->getParent();
1366 ReturnBB->replaceAllUsesWith(AfterCallBB);
1368 // Splice the code from the return block into the block that it will return
1369 // to, which contains the code that was after the call.
1370 AfterCallBB->getInstList().splice(AfterCallBB->begin(),
1371 ReturnBB->getInstList());
1373 if (CreatedBranchToNormalDest)
1374 CreatedBranchToNormalDest->setDebugLoc(Returns[0]->getDebugLoc());
1376 // Delete the return instruction now and empty ReturnBB now.
1377 Returns[0]->eraseFromParent();
1378 ReturnBB->eraseFromParent();
1379 } else if (!TheCall->use_empty()) {
1380 // No returns, but something is using the return value of the call. Just
1382 TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType()));
1385 // Since we are now done with the Call/Invoke, we can delete it.
1386 TheCall->eraseFromParent();
1388 // If we inlined any musttail calls and the original return is now
1389 // unreachable, delete it. It can only contain a bitcast and ret.
1390 if (InlinedMustTailCalls && pred_begin(AfterCallBB) == pred_end(AfterCallBB))
1391 AfterCallBB->eraseFromParent();
1393 // We should always be able to fold the entry block of the function into the
1394 // single predecessor of the block...
1395 assert(cast<BranchInst>(Br)->isUnconditional() && "splitBasicBlock broken!");
1396 BasicBlock *CalleeEntry = cast<BranchInst>(Br)->getSuccessor(0);
1398 // Splice the code entry block into calling block, right before the
1399 // unconditional branch.
1400 CalleeEntry->replaceAllUsesWith(OrigBB); // Update PHI nodes
1401 OrigBB->getInstList().splice(Br, CalleeEntry->getInstList());
1403 // Remove the unconditional branch.
1404 OrigBB->getInstList().erase(Br);
1406 // Now we can remove the CalleeEntry block, which is now empty.
1407 Caller->getBasicBlockList().erase(CalleeEntry);
1409 // If we inserted a phi node, check to see if it has a single value (e.g. all
1410 // the entries are the same or undef). If so, remove the PHI so it doesn't
1411 // block other optimizations.
1413 if (Value *V = SimplifyInstruction(PHI, IFI.DL, nullptr, nullptr, IFI.AT)) {
1414 PHI->replaceAllUsesWith(V);
1415 PHI->eraseFromParent();