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/SmallVector.h"
17 #include "llvm/ADT/StringExtras.h"
18 #include "llvm/Analysis/CallGraph.h"
19 #include "llvm/Analysis/InstructionSimplify.h"
20 #include "llvm/IR/Attributes.h"
21 #include "llvm/IR/CallSite.h"
22 #include "llvm/IR/CFG.h"
23 #include "llvm/IR/Constants.h"
24 #include "llvm/IR/DataLayout.h"
25 #include "llvm/IR/DebugInfo.h"
26 #include "llvm/IR/DerivedTypes.h"
27 #include "llvm/IR/IRBuilder.h"
28 #include "llvm/IR/Instructions.h"
29 #include "llvm/IR/IntrinsicInst.h"
30 #include "llvm/IR/Intrinsics.h"
31 #include "llvm/IR/Module.h"
32 #include "llvm/Transforms/Utils/Local.h"
35 bool llvm::InlineFunction(CallInst *CI, InlineFunctionInfo &IFI,
36 bool InsertLifetime) {
37 return InlineFunction(CallSite(CI), IFI, InsertLifetime);
39 bool llvm::InlineFunction(InvokeInst *II, InlineFunctionInfo &IFI,
40 bool InsertLifetime) {
41 return InlineFunction(CallSite(II), IFI, InsertLifetime);
45 /// A class for recording information about inlining through an invoke.
46 class InvokeInliningInfo {
47 BasicBlock *OuterResumeDest; ///< Destination of the invoke's unwind.
48 BasicBlock *InnerResumeDest; ///< Destination for the callee's resume.
49 LandingPadInst *CallerLPad; ///< LandingPadInst associated with the invoke.
50 PHINode *InnerEHValuesPHI; ///< PHI for EH values from landingpad insts.
51 SmallVector<Value*, 8> UnwindDestPHIValues;
54 InvokeInliningInfo(InvokeInst *II)
55 : OuterResumeDest(II->getUnwindDest()), InnerResumeDest(nullptr),
56 CallerLPad(nullptr), InnerEHValuesPHI(nullptr) {
57 // If there are PHI nodes in the unwind destination block, we need to keep
58 // track of which values came into them from the invoke before removing
59 // the edge from this block.
60 llvm::BasicBlock *InvokeBB = II->getParent();
61 BasicBlock::iterator I = OuterResumeDest->begin();
62 for (; isa<PHINode>(I); ++I) {
63 // Save the value to use for this edge.
64 PHINode *PHI = cast<PHINode>(I);
65 UnwindDestPHIValues.push_back(PHI->getIncomingValueForBlock(InvokeBB));
68 CallerLPad = cast<LandingPadInst>(I);
71 /// getOuterResumeDest - The outer unwind destination is the target of
72 /// unwind edges introduced for calls within the inlined function.
73 BasicBlock *getOuterResumeDest() const {
74 return OuterResumeDest;
77 BasicBlock *getInnerResumeDest();
79 LandingPadInst *getLandingPadInst() const { return CallerLPad; }
81 /// forwardResume - Forward the 'resume' instruction to the caller's landing
82 /// pad block. When the landing pad block has only one predecessor, this is
83 /// a simple branch. When there is more than one predecessor, we need to
84 /// split the landing pad block after the landingpad instruction and jump
86 void forwardResume(ResumeInst *RI,
87 SmallPtrSet<LandingPadInst*, 16> &InlinedLPads);
89 /// addIncomingPHIValuesFor - Add incoming-PHI values to the unwind
90 /// destination block for the given basic block, using the values for the
91 /// original invoke's source block.
92 void addIncomingPHIValuesFor(BasicBlock *BB) const {
93 addIncomingPHIValuesForInto(BB, OuterResumeDest);
96 void addIncomingPHIValuesForInto(BasicBlock *src, BasicBlock *dest) const {
97 BasicBlock::iterator I = dest->begin();
98 for (unsigned i = 0, e = UnwindDestPHIValues.size(); i != e; ++i, ++I) {
99 PHINode *phi = cast<PHINode>(I);
100 phi->addIncoming(UnwindDestPHIValues[i], src);
106 /// getInnerResumeDest - Get or create a target for the branch from ResumeInsts.
107 BasicBlock *InvokeInliningInfo::getInnerResumeDest() {
108 if (InnerResumeDest) return InnerResumeDest;
110 // Split the landing pad.
111 BasicBlock::iterator SplitPoint = CallerLPad; ++SplitPoint;
113 OuterResumeDest->splitBasicBlock(SplitPoint,
114 OuterResumeDest->getName() + ".body");
116 // The number of incoming edges we expect to the inner landing pad.
117 const unsigned PHICapacity = 2;
119 // Create corresponding new PHIs for all the PHIs in the outer landing pad.
120 BasicBlock::iterator InsertPoint = InnerResumeDest->begin();
121 BasicBlock::iterator I = OuterResumeDest->begin();
122 for (unsigned i = 0, e = UnwindDestPHIValues.size(); i != e; ++i, ++I) {
123 PHINode *OuterPHI = cast<PHINode>(I);
124 PHINode *InnerPHI = PHINode::Create(OuterPHI->getType(), PHICapacity,
125 OuterPHI->getName() + ".lpad-body",
127 OuterPHI->replaceAllUsesWith(InnerPHI);
128 InnerPHI->addIncoming(OuterPHI, OuterResumeDest);
131 // Create a PHI for the exception values.
132 InnerEHValuesPHI = PHINode::Create(CallerLPad->getType(), PHICapacity,
133 "eh.lpad-body", InsertPoint);
134 CallerLPad->replaceAllUsesWith(InnerEHValuesPHI);
135 InnerEHValuesPHI->addIncoming(CallerLPad, OuterResumeDest);
138 return InnerResumeDest;
141 /// forwardResume - Forward the 'resume' instruction to the caller's landing pad
142 /// block. When the landing pad block has only one predecessor, this is a simple
143 /// branch. When there is more than one predecessor, we need to split the
144 /// landing pad block after the landingpad instruction and jump to there.
145 void InvokeInliningInfo::forwardResume(ResumeInst *RI,
146 SmallPtrSet<LandingPadInst*, 16> &InlinedLPads) {
147 BasicBlock *Dest = getInnerResumeDest();
148 BasicBlock *Src = RI->getParent();
150 BranchInst::Create(Dest, Src);
152 // Update the PHIs in the destination. They were inserted in an order which
154 addIncomingPHIValuesForInto(Src, Dest);
156 InnerEHValuesPHI->addIncoming(RI->getOperand(0), Src);
157 RI->eraseFromParent();
160 /// HandleCallsInBlockInlinedThroughInvoke - When we inline a basic block into
161 /// an invoke, we have to turn all of the calls that can throw into
162 /// invokes. This function analyze BB to see if there are any calls, and if so,
163 /// it rewrites them to be invokes that jump to InvokeDest and fills in the PHI
164 /// nodes in that block with the values specified in InvokeDestPHIValues.
165 static void HandleCallsInBlockInlinedThroughInvoke(BasicBlock *BB,
166 InvokeInliningInfo &Invoke) {
167 for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) {
168 Instruction *I = BBI++;
170 // We only need to check for function calls: inlined invoke
171 // instructions require no special handling.
172 CallInst *CI = dyn_cast<CallInst>(I);
174 // If this call cannot unwind, don't convert it to an invoke.
175 // Inline asm calls cannot throw.
176 if (!CI || CI->doesNotThrow() || isa<InlineAsm>(CI->getCalledValue()))
179 // Convert this function call into an invoke instruction. First, split the
181 BasicBlock *Split = BB->splitBasicBlock(CI, CI->getName()+".noexc");
183 // Delete the unconditional branch inserted by splitBasicBlock
184 BB->getInstList().pop_back();
186 // Create the new invoke instruction.
187 ImmutableCallSite CS(CI);
188 SmallVector<Value*, 8> InvokeArgs(CS.arg_begin(), CS.arg_end());
189 InvokeInst *II = InvokeInst::Create(CI->getCalledValue(), Split,
190 Invoke.getOuterResumeDest(),
191 InvokeArgs, CI->getName(), BB);
192 II->setCallingConv(CI->getCallingConv());
193 II->setAttributes(CI->getAttributes());
195 // Make sure that anything using the call now uses the invoke! This also
196 // updates the CallGraph if present, because it uses a WeakVH.
197 CI->replaceAllUsesWith(II);
199 // Delete the original call
200 Split->getInstList().pop_front();
202 // Update any PHI nodes in the exceptional block to indicate that there is
203 // now a new entry in them.
204 Invoke.addIncomingPHIValuesFor(BB);
209 /// HandleInlinedInvoke - If we inlined an invoke site, we need to convert calls
210 /// in the body of the inlined function into invokes.
212 /// II is the invoke instruction being inlined. FirstNewBlock is the first
213 /// block of the inlined code (the last block is the end of the function),
214 /// and InlineCodeInfo is information about the code that got inlined.
215 static void HandleInlinedInvoke(InvokeInst *II, BasicBlock *FirstNewBlock,
216 ClonedCodeInfo &InlinedCodeInfo) {
217 BasicBlock *InvokeDest = II->getUnwindDest();
219 Function *Caller = FirstNewBlock->getParent();
221 // The inlined code is currently at the end of the function, scan from the
222 // start of the inlined code to its end, checking for stuff we need to
224 InvokeInliningInfo Invoke(II);
226 // Get all of the inlined landing pad instructions.
227 SmallPtrSet<LandingPadInst*, 16> InlinedLPads;
228 for (Function::iterator I = FirstNewBlock, E = Caller->end(); I != E; ++I)
229 if (InvokeInst *II = dyn_cast<InvokeInst>(I->getTerminator()))
230 InlinedLPads.insert(II->getLandingPadInst());
232 // Append the clauses from the outer landing pad instruction into the inlined
233 // landing pad instructions.
234 LandingPadInst *OuterLPad = Invoke.getLandingPadInst();
235 for (SmallPtrSet<LandingPadInst*, 16>::iterator I = InlinedLPads.begin(),
236 E = InlinedLPads.end(); I != E; ++I) {
237 LandingPadInst *InlinedLPad = *I;
238 unsigned OuterNum = OuterLPad->getNumClauses();
239 InlinedLPad->reserveClauses(OuterNum);
240 for (unsigned OuterIdx = 0; OuterIdx != OuterNum; ++OuterIdx)
241 InlinedLPad->addClause(OuterLPad->getClause(OuterIdx));
242 if (OuterLPad->isCleanup())
243 InlinedLPad->setCleanup(true);
246 for (Function::iterator BB = FirstNewBlock, E = Caller->end(); BB != E; ++BB){
247 if (InlinedCodeInfo.ContainsCalls)
248 HandleCallsInBlockInlinedThroughInvoke(BB, Invoke);
250 // Forward any resumes that are remaining here.
251 if (ResumeInst *RI = dyn_cast<ResumeInst>(BB->getTerminator()))
252 Invoke.forwardResume(RI, InlinedLPads);
255 // Now that everything is happy, we have one final detail. The PHI nodes in
256 // the exception destination block still have entries due to the original
257 // invoke instruction. Eliminate these entries (which might even delete the
259 InvokeDest->removePredecessor(II->getParent());
262 /// UpdateCallGraphAfterInlining - Once we have cloned code over from a callee
263 /// into the caller, update the specified callgraph to reflect the changes we
264 /// made. Note that it's possible that not all code was copied over, so only
265 /// some edges of the callgraph may remain.
266 static void UpdateCallGraphAfterInlining(CallSite CS,
267 Function::iterator FirstNewBlock,
268 ValueToValueMapTy &VMap,
269 InlineFunctionInfo &IFI) {
270 CallGraph &CG = *IFI.CG;
271 const Function *Caller = CS.getInstruction()->getParent()->getParent();
272 const Function *Callee = CS.getCalledFunction();
273 CallGraphNode *CalleeNode = CG[Callee];
274 CallGraphNode *CallerNode = CG[Caller];
276 // Since we inlined some uninlined call sites in the callee into the caller,
277 // add edges from the caller to all of the callees of the callee.
278 CallGraphNode::iterator I = CalleeNode->begin(), E = CalleeNode->end();
280 // Consider the case where CalleeNode == CallerNode.
281 CallGraphNode::CalledFunctionsVector CallCache;
282 if (CalleeNode == CallerNode) {
283 CallCache.assign(I, E);
284 I = CallCache.begin();
288 for (; I != E; ++I) {
289 const Value *OrigCall = I->first;
291 ValueToValueMapTy::iterator VMI = VMap.find(OrigCall);
292 // Only copy the edge if the call was inlined!
293 if (VMI == VMap.end() || VMI->second == nullptr)
296 // If the call was inlined, but then constant folded, there is no edge to
297 // add. Check for this case.
298 Instruction *NewCall = dyn_cast<Instruction>(VMI->second);
299 if (!NewCall) continue;
301 // Remember that this call site got inlined for the client of
303 IFI.InlinedCalls.push_back(NewCall);
305 // It's possible that inlining the callsite will cause it to go from an
306 // indirect to a direct call by resolving a function pointer. If this
307 // happens, set the callee of the new call site to a more precise
308 // destination. This can also happen if the call graph node of the caller
309 // was just unnecessarily imprecise.
310 if (!I->second->getFunction())
311 if (Function *F = CallSite(NewCall).getCalledFunction()) {
312 // Indirect call site resolved to direct call.
313 CallerNode->addCalledFunction(CallSite(NewCall), CG[F]);
318 CallerNode->addCalledFunction(CallSite(NewCall), I->second);
321 // Update the call graph by deleting the edge from Callee to Caller. We must
322 // do this after the loop above in case Caller and Callee are the same.
323 CallerNode->removeCallEdgeFor(CS);
326 static void HandleByValArgumentInit(Value *Dst, Value *Src, Module *M,
327 BasicBlock *InsertBlock,
328 InlineFunctionInfo &IFI) {
329 LLVMContext &Context = Src->getContext();
330 Type *VoidPtrTy = Type::getInt8PtrTy(Context);
331 Type *AggTy = cast<PointerType>(Src->getType())->getElementType();
332 Type *Tys[3] = { VoidPtrTy, VoidPtrTy, Type::getInt64Ty(Context) };
333 Function *MemCpyFn = Intrinsic::getDeclaration(M, Intrinsic::memcpy, Tys);
334 IRBuilder<> builder(InsertBlock->begin());
335 Value *DstCast = builder.CreateBitCast(Dst, VoidPtrTy, "tmp");
336 Value *SrcCast = builder.CreateBitCast(Src, VoidPtrTy, "tmp");
339 if (IFI.DL == nullptr)
340 Size = ConstantExpr::getSizeOf(AggTy);
342 Size = ConstantInt::get(Type::getInt64Ty(Context),
343 IFI.DL->getTypeStoreSize(AggTy));
345 // Always generate a memcpy of alignment 1 here because we don't know
346 // the alignment of the src pointer. Other optimizations can infer
348 Value *CallArgs[] = {
349 DstCast, SrcCast, Size,
350 ConstantInt::get(Type::getInt32Ty(Context), 1),
351 ConstantInt::getFalse(Context) // isVolatile
353 builder.CreateCall(MemCpyFn, CallArgs);
356 /// HandleByValArgument - When inlining a call site that has a byval argument,
357 /// we have to make the implicit memcpy explicit by adding it.
358 static Value *HandleByValArgument(Value *Arg, Instruction *TheCall,
359 const Function *CalledFunc,
360 InlineFunctionInfo &IFI,
361 unsigned ByValAlignment) {
362 PointerType *ArgTy = cast<PointerType>(Arg->getType());
363 Type *AggTy = ArgTy->getElementType();
365 // If the called function is readonly, then it could not mutate the caller's
366 // copy of the byval'd memory. In this case, it is safe to elide the copy and
368 if (CalledFunc->onlyReadsMemory()) {
369 // If the byval argument has a specified alignment that is greater than the
370 // passed in pointer, then we either have to round up the input pointer or
371 // give up on this transformation.
372 if (ByValAlignment <= 1) // 0 = unspecified, 1 = no particular alignment.
375 // If the pointer is already known to be sufficiently aligned, or if we can
376 // round it up to a larger alignment, then we don't need a temporary.
377 if (getOrEnforceKnownAlignment(Arg, ByValAlignment,
378 IFI.DL) >= ByValAlignment)
381 // Otherwise, we have to make a memcpy to get a safe alignment. This is bad
382 // for code quality, but rarely happens and is required for correctness.
385 // Create the alloca. If we have DataLayout, use nice alignment.
388 Align = IFI.DL->getPrefTypeAlignment(AggTy);
390 // If the byval had an alignment specified, we *must* use at least that
391 // alignment, as it is required by the byval argument (and uses of the
392 // pointer inside the callee).
393 Align = std::max(Align, ByValAlignment);
395 Function *Caller = TheCall->getParent()->getParent();
397 Value *NewAlloca = new AllocaInst(AggTy, nullptr, Align, Arg->getName(),
398 &*Caller->begin()->begin());
399 IFI.StaticAllocas.push_back(cast<AllocaInst>(NewAlloca));
401 // Uses of the argument in the function should use our new alloca
406 // isUsedByLifetimeMarker - Check whether this Value is used by a lifetime
408 static bool isUsedByLifetimeMarker(Value *V) {
409 for (User *U : V->users()) {
410 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(U)) {
411 switch (II->getIntrinsicID()) {
413 case Intrinsic::lifetime_start:
414 case Intrinsic::lifetime_end:
422 // hasLifetimeMarkers - Check whether the given alloca already has
423 // lifetime.start or lifetime.end intrinsics.
424 static bool hasLifetimeMarkers(AllocaInst *AI) {
425 Type *Ty = AI->getType();
426 Type *Int8PtrTy = Type::getInt8PtrTy(Ty->getContext(),
427 Ty->getPointerAddressSpace());
429 return isUsedByLifetimeMarker(AI);
431 // Do a scan to find all the casts to i8*.
432 for (User *U : AI->users()) {
433 if (U->getType() != Int8PtrTy) continue;
434 if (U->stripPointerCasts() != AI) continue;
435 if (isUsedByLifetimeMarker(U))
441 /// updateInlinedAtInfo - Helper function used by fixupLineNumbers to
442 /// recursively update InlinedAtEntry of a DebugLoc.
443 static DebugLoc updateInlinedAtInfo(const DebugLoc &DL,
444 const DebugLoc &InlinedAtDL,
446 if (MDNode *IA = DL.getInlinedAt(Ctx)) {
447 DebugLoc NewInlinedAtDL
448 = updateInlinedAtInfo(DebugLoc::getFromDILocation(IA), InlinedAtDL, Ctx);
449 return DebugLoc::get(DL.getLine(), DL.getCol(), DL.getScope(Ctx),
450 NewInlinedAtDL.getAsMDNode(Ctx));
453 return DebugLoc::get(DL.getLine(), DL.getCol(), DL.getScope(Ctx),
454 InlinedAtDL.getAsMDNode(Ctx));
457 /// fixupLineNumbers - Update inlined instructions' line numbers to
458 /// to encode location where these instructions are inlined.
459 static void fixupLineNumbers(Function *Fn, Function::iterator FI,
460 Instruction *TheCall) {
461 DebugLoc TheCallDL = TheCall->getDebugLoc();
462 if (TheCallDL.isUnknown())
465 for (; FI != Fn->end(); ++FI) {
466 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
468 DebugLoc DL = BI->getDebugLoc();
469 if (!DL.isUnknown()) {
470 BI->setDebugLoc(updateInlinedAtInfo(DL, TheCallDL, BI->getContext()));
471 if (DbgValueInst *DVI = dyn_cast<DbgValueInst>(BI)) {
472 LLVMContext &Ctx = BI->getContext();
473 MDNode *InlinedAt = BI->getDebugLoc().getInlinedAt(Ctx);
474 DVI->setOperand(2, createInlinedVariable(DVI->getVariable(),
482 /// Returns a musttail call instruction if one immediately precedes the given
483 /// return instruction with an optional bitcast instruction between them.
484 static CallInst *getPrecedingMustTailCall(ReturnInst *RI) {
485 Instruction *Prev = RI->getPrevNode();
489 if (Value *RV = RI->getReturnValue()) {
493 // Look through the optional bitcast.
494 if (auto *BI = dyn_cast<BitCastInst>(Prev)) {
495 RV = BI->getOperand(0);
496 Prev = BI->getPrevNode();
497 if (!Prev || RV != Prev)
502 if (auto *CI = dyn_cast<CallInst>(Prev)) {
503 if (CI->isMustTailCall())
509 /// InlineFunction - This function inlines the called function into the basic
510 /// block of the caller. This returns false if it is not possible to inline
511 /// this call. The program is still in a well defined state if this occurs
514 /// Note that this only does one level of inlining. For example, if the
515 /// instruction 'call B' is inlined, and 'B' calls 'C', then the call to 'C' now
516 /// exists in the instruction stream. Similarly this will inline a recursive
517 /// function by one level.
518 bool llvm::InlineFunction(CallSite CS, InlineFunctionInfo &IFI,
519 bool InsertLifetime) {
520 Instruction *TheCall = CS.getInstruction();
521 assert(TheCall->getParent() && TheCall->getParent()->getParent() &&
522 "Instruction not in function!");
524 // If IFI has any state in it, zap it before we fill it in.
527 const Function *CalledFunc = CS.getCalledFunction();
528 if (!CalledFunc || // Can't inline external function or indirect
529 CalledFunc->isDeclaration() || // call, or call to a vararg function!
530 CalledFunc->getFunctionType()->isVarArg()) return false;
532 // If the call to the callee cannot throw, set the 'nounwind' flag on any
533 // calls that we inline.
534 bool MarkNoUnwind = CS.doesNotThrow();
536 BasicBlock *OrigBB = TheCall->getParent();
537 Function *Caller = OrigBB->getParent();
539 // GC poses two hazards to inlining, which only occur when the callee has GC:
540 // 1. If the caller has no GC, then the callee's GC must be propagated to the
542 // 2. If the caller has a differing GC, it is invalid to inline.
543 if (CalledFunc->hasGC()) {
544 if (!Caller->hasGC())
545 Caller->setGC(CalledFunc->getGC());
546 else if (CalledFunc->getGC() != Caller->getGC())
550 // Get the personality function from the callee if it contains a landing pad.
551 Value *CalleePersonality = nullptr;
552 for (Function::const_iterator I = CalledFunc->begin(), E = CalledFunc->end();
554 if (const InvokeInst *II = dyn_cast<InvokeInst>(I->getTerminator())) {
555 const BasicBlock *BB = II->getUnwindDest();
556 const LandingPadInst *LP = BB->getLandingPadInst();
557 CalleePersonality = LP->getPersonalityFn();
561 // Find the personality function used by the landing pads of the caller. If it
562 // exists, then check to see that it matches the personality function used in
564 if (CalleePersonality) {
565 for (Function::const_iterator I = Caller->begin(), E = Caller->end();
567 if (const InvokeInst *II = dyn_cast<InvokeInst>(I->getTerminator())) {
568 const BasicBlock *BB = II->getUnwindDest();
569 const LandingPadInst *LP = BB->getLandingPadInst();
571 // If the personality functions match, then we can perform the
572 // inlining. Otherwise, we can't inline.
573 // TODO: This isn't 100% true. Some personality functions are proper
574 // supersets of others and can be used in place of the other.
575 if (LP->getPersonalityFn() != CalleePersonality)
582 // Get an iterator to the last basic block in the function, which will have
583 // the new function inlined after it.
584 Function::iterator LastBlock = &Caller->back();
586 // Make sure to capture all of the return instructions from the cloned
588 SmallVector<ReturnInst*, 8> Returns;
589 ClonedCodeInfo InlinedFunctionInfo;
590 Function::iterator FirstNewBlock;
592 { // Scope to destroy VMap after cloning.
593 ValueToValueMapTy VMap;
594 // Keep a list of pair (dst, src) to emit byval initializations.
595 SmallVector<std::pair<Value*, Value*>, 4> ByValInit;
597 assert(CalledFunc->arg_size() == CS.arg_size() &&
598 "No varargs calls can be inlined!");
600 // Calculate the vector of arguments to pass into the function cloner, which
601 // matches up the formal to the actual argument values.
602 CallSite::arg_iterator AI = CS.arg_begin();
604 for (Function::const_arg_iterator I = CalledFunc->arg_begin(),
605 E = CalledFunc->arg_end(); I != E; ++I, ++AI, ++ArgNo) {
606 Value *ActualArg = *AI;
608 // When byval arguments actually inlined, we need to make the copy implied
609 // by them explicit. However, we don't do this if the callee is readonly
610 // or readnone, because the copy would be unneeded: the callee doesn't
611 // modify the struct.
612 if (CS.isByValArgument(ArgNo)) {
613 ActualArg = HandleByValArgument(ActualArg, TheCall, CalledFunc, IFI,
614 CalledFunc->getParamAlignment(ArgNo+1));
615 if (ActualArg != *AI)
616 ByValInit.push_back(std::make_pair(ActualArg, (Value*) *AI));
622 // We want the inliner to prune the code as it copies. We would LOVE to
623 // have no dead or constant instructions leftover after inlining occurs
624 // (which can happen, e.g., because an argument was constant), but we'll be
625 // happy with whatever the cloner can do.
626 CloneAndPruneFunctionInto(Caller, CalledFunc, VMap,
627 /*ModuleLevelChanges=*/false, Returns, ".i",
628 &InlinedFunctionInfo, IFI.DL, TheCall);
630 // Remember the first block that is newly cloned over.
631 FirstNewBlock = LastBlock; ++FirstNewBlock;
633 // Inject byval arguments initialization.
634 for (std::pair<Value*, Value*> &Init : ByValInit)
635 HandleByValArgumentInit(Init.first, Init.second, Caller->getParent(),
638 // Update the callgraph if requested.
640 UpdateCallGraphAfterInlining(CS, FirstNewBlock, VMap, IFI);
642 // Update inlined instructions' line number information.
643 fixupLineNumbers(Caller, FirstNewBlock, TheCall);
646 // If there are any alloca instructions in the block that used to be the entry
647 // block for the callee, move them to the entry block of the caller. First
648 // calculate which instruction they should be inserted before. We insert the
649 // instructions at the end of the current alloca list.
651 BasicBlock::iterator InsertPoint = Caller->begin()->begin();
652 for (BasicBlock::iterator I = FirstNewBlock->begin(),
653 E = FirstNewBlock->end(); I != E; ) {
654 AllocaInst *AI = dyn_cast<AllocaInst>(I++);
657 // If the alloca is now dead, remove it. This often occurs due to code
659 if (AI->use_empty()) {
660 AI->eraseFromParent();
664 if (!isa<Constant>(AI->getArraySize()))
667 // Keep track of the static allocas that we inline into the caller.
668 IFI.StaticAllocas.push_back(AI);
670 // Scan for the block of allocas that we can move over, and move them
672 while (isa<AllocaInst>(I) &&
673 isa<Constant>(cast<AllocaInst>(I)->getArraySize())) {
674 IFI.StaticAllocas.push_back(cast<AllocaInst>(I));
678 // Transfer all of the allocas over in a block. Using splice means
679 // that the instructions aren't removed from the symbol table, then
681 Caller->getEntryBlock().getInstList().splice(InsertPoint,
682 FirstNewBlock->getInstList(),
687 bool InlinedMustTailCalls = false;
688 if (InlinedFunctionInfo.ContainsCalls) {
689 CallInst::TailCallKind CallSiteTailKind = CallInst::TCK_None;
690 if (CallInst *CI = dyn_cast<CallInst>(TheCall))
691 CallSiteTailKind = CI->getTailCallKind();
693 for (Function::iterator BB = FirstNewBlock, E = Caller->end(); BB != E;
695 for (Instruction &I : *BB) {
696 CallInst *CI = dyn_cast<CallInst>(&I);
700 // We need to reduce the strength of any inlined tail calls. For
701 // musttail, we have to avoid introducing potential unbounded stack
702 // growth. For example, if functions 'f' and 'g' are mutually recursive
703 // with musttail, we can inline 'g' into 'f' so long as we preserve
704 // musttail on the cloned call to 'f'. If either the inlined call site
705 // or the cloned call site is *not* musttail, the program already has
706 // one frame of stack growth, so it's safe to remove musttail. Here is
707 // a table of example transformations:
709 // f -> musttail g -> musttail f ==> f -> musttail f
710 // f -> musttail g -> tail f ==> f -> tail f
711 // f -> g -> musttail f ==> f -> f
712 // f -> g -> tail f ==> f -> f
713 CallInst::TailCallKind ChildTCK = CI->getTailCallKind();
714 ChildTCK = std::min(CallSiteTailKind, ChildTCK);
715 CI->setTailCallKind(ChildTCK);
716 InlinedMustTailCalls |= CI->isMustTailCall();
718 // Calls inlined through a 'nounwind' call site should be marked
721 CI->setDoesNotThrow();
726 // Leave lifetime markers for the static alloca's, scoping them to the
727 // function we just inlined.
728 if (InsertLifetime && !IFI.StaticAllocas.empty()) {
729 IRBuilder<> builder(FirstNewBlock->begin());
730 for (unsigned ai = 0, ae = IFI.StaticAllocas.size(); ai != ae; ++ai) {
731 AllocaInst *AI = IFI.StaticAllocas[ai];
733 // If the alloca is already scoped to something smaller than the whole
734 // function then there's no need to add redundant, less accurate markers.
735 if (hasLifetimeMarkers(AI))
738 // Try to determine the size of the allocation.
739 ConstantInt *AllocaSize = nullptr;
740 if (ConstantInt *AIArraySize =
741 dyn_cast<ConstantInt>(AI->getArraySize())) {
743 Type *AllocaType = AI->getAllocatedType();
744 uint64_t AllocaTypeSize = IFI.DL->getTypeAllocSize(AllocaType);
745 uint64_t AllocaArraySize = AIArraySize->getLimitedValue();
746 assert(AllocaArraySize > 0 && "array size of AllocaInst is zero");
747 // Check that array size doesn't saturate uint64_t and doesn't
748 // overflow when it's multiplied by type size.
749 if (AllocaArraySize != ~0ULL &&
750 UINT64_MAX / AllocaArraySize >= AllocaTypeSize) {
751 AllocaSize = ConstantInt::get(Type::getInt64Ty(AI->getContext()),
752 AllocaArraySize * AllocaTypeSize);
757 builder.CreateLifetimeStart(AI, AllocaSize);
758 for (ReturnInst *RI : Returns)
759 IRBuilder<>(RI).CreateLifetimeEnd(AI, AllocaSize);
763 // If the inlined code contained dynamic alloca instructions, wrap the inlined
764 // code with llvm.stacksave/llvm.stackrestore intrinsics.
765 if (InlinedFunctionInfo.ContainsDynamicAllocas) {
766 Module *M = Caller->getParent();
767 // Get the two intrinsics we care about.
768 Function *StackSave = Intrinsic::getDeclaration(M, Intrinsic::stacksave);
769 Function *StackRestore=Intrinsic::getDeclaration(M,Intrinsic::stackrestore);
771 // Insert the llvm.stacksave.
772 CallInst *SavedPtr = IRBuilder<>(FirstNewBlock, FirstNewBlock->begin())
773 .CreateCall(StackSave, "savedstack");
775 // Insert a call to llvm.stackrestore before any return instructions in the
777 for (ReturnInst *RI : Returns)
778 IRBuilder<>(RI).CreateCall(StackRestore, SavedPtr);
781 // If we are inlining for an invoke instruction, we must make sure to rewrite
782 // any call instructions into invoke instructions.
783 if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall))
784 HandleInlinedInvoke(II, FirstNewBlock, InlinedFunctionInfo);
786 // Handle any inlined musttail call sites. In order for a new call site to be
787 // musttail, the source of the clone and the inlined call site must have been
788 // musttail. Therefore it's safe to return without merging control into the
790 if (InlinedMustTailCalls) {
791 // Check if we need to bitcast the result of any musttail calls.
792 Type *NewRetTy = Caller->getReturnType();
793 bool NeedBitCast = !TheCall->use_empty() && TheCall->getType() != NewRetTy;
795 // Handle the returns preceded by musttail calls separately.
796 SmallVector<ReturnInst *, 8> NormalReturns;
797 for (ReturnInst *RI : Returns) {
798 CallInst *ReturnedMustTail = getPrecedingMustTailCall(RI);
799 if (!ReturnedMustTail) {
800 NormalReturns.push_back(RI);
806 // Delete the old return and any preceding bitcast.
807 BasicBlock *CurBB = RI->getParent();
808 auto *OldCast = dyn_cast_or_null<BitCastInst>(RI->getReturnValue());
809 RI->eraseFromParent();
811 OldCast->eraseFromParent();
813 // Insert a new bitcast and return with the right type.
814 IRBuilder<> Builder(CurBB);
815 Builder.CreateRet(Builder.CreateBitCast(ReturnedMustTail, NewRetTy));
818 // Leave behind the normal returns so we can merge control flow.
819 std::swap(Returns, NormalReturns);
822 // If we cloned in _exactly one_ basic block, and if that block ends in a
823 // return instruction, we splice the body of the inlined callee directly into
824 // the calling basic block.
825 if (Returns.size() == 1 && std::distance(FirstNewBlock, Caller->end()) == 1) {
826 // Move all of the instructions right before the call.
827 OrigBB->getInstList().splice(TheCall, FirstNewBlock->getInstList(),
828 FirstNewBlock->begin(), FirstNewBlock->end());
829 // Remove the cloned basic block.
830 Caller->getBasicBlockList().pop_back();
832 // If the call site was an invoke instruction, add a branch to the normal
834 if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall)) {
835 BranchInst *NewBr = BranchInst::Create(II->getNormalDest(), TheCall);
836 NewBr->setDebugLoc(Returns[0]->getDebugLoc());
839 // If the return instruction returned a value, replace uses of the call with
840 // uses of the returned value.
841 if (!TheCall->use_empty()) {
842 ReturnInst *R = Returns[0];
843 if (TheCall == R->getReturnValue())
844 TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType()));
846 TheCall->replaceAllUsesWith(R->getReturnValue());
848 // Since we are now done with the Call/Invoke, we can delete it.
849 TheCall->eraseFromParent();
851 // Since we are now done with the return instruction, delete it also.
852 Returns[0]->eraseFromParent();
854 // We are now done with the inlining.
858 // Otherwise, we have the normal case, of more than one block to inline or
859 // multiple return sites.
861 // We want to clone the entire callee function into the hole between the
862 // "starter" and "ender" blocks. How we accomplish this depends on whether
863 // this is an invoke instruction or a call instruction.
864 BasicBlock *AfterCallBB;
865 BranchInst *CreatedBranchToNormalDest = nullptr;
866 if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall)) {
868 // Add an unconditional branch to make this look like the CallInst case...
869 CreatedBranchToNormalDest = BranchInst::Create(II->getNormalDest(), TheCall);
871 // Split the basic block. This guarantees that no PHI nodes will have to be
872 // updated due to new incoming edges, and make the invoke case more
873 // symmetric to the call case.
874 AfterCallBB = OrigBB->splitBasicBlock(CreatedBranchToNormalDest,
875 CalledFunc->getName()+".exit");
877 } else { // It's a call
878 // If this is a call instruction, we need to split the basic block that
879 // the call lives in.
881 AfterCallBB = OrigBB->splitBasicBlock(TheCall,
882 CalledFunc->getName()+".exit");
885 // Change the branch that used to go to AfterCallBB to branch to the first
886 // basic block of the inlined function.
888 TerminatorInst *Br = OrigBB->getTerminator();
889 assert(Br && Br->getOpcode() == Instruction::Br &&
890 "splitBasicBlock broken!");
891 Br->setOperand(0, FirstNewBlock);
894 // Now that the function is correct, make it a little bit nicer. In
895 // particular, move the basic blocks inserted from the end of the function
896 // into the space made by splitting the source basic block.
897 Caller->getBasicBlockList().splice(AfterCallBB, Caller->getBasicBlockList(),
898 FirstNewBlock, Caller->end());
900 // Handle all of the return instructions that we just cloned in, and eliminate
901 // any users of the original call/invoke instruction.
902 Type *RTy = CalledFunc->getReturnType();
904 PHINode *PHI = nullptr;
905 if (Returns.size() > 1) {
906 // The PHI node should go at the front of the new basic block to merge all
907 // possible incoming values.
908 if (!TheCall->use_empty()) {
909 PHI = PHINode::Create(RTy, Returns.size(), TheCall->getName(),
910 AfterCallBB->begin());
911 // Anything that used the result of the function call should now use the
912 // PHI node as their operand.
913 TheCall->replaceAllUsesWith(PHI);
916 // Loop over all of the return instructions adding entries to the PHI node
919 for (unsigned i = 0, e = Returns.size(); i != e; ++i) {
920 ReturnInst *RI = Returns[i];
921 assert(RI->getReturnValue()->getType() == PHI->getType() &&
922 "Ret value not consistent in function!");
923 PHI->addIncoming(RI->getReturnValue(), RI->getParent());
928 // Add a branch to the merge points and remove return instructions.
930 for (unsigned i = 0, e = Returns.size(); i != e; ++i) {
931 ReturnInst *RI = Returns[i];
932 BranchInst* BI = BranchInst::Create(AfterCallBB, RI);
933 Loc = RI->getDebugLoc();
934 BI->setDebugLoc(Loc);
935 RI->eraseFromParent();
937 // We need to set the debug location to *somewhere* inside the
938 // inlined function. The line number may be nonsensical, but the
939 // instruction will at least be associated with the right
941 if (CreatedBranchToNormalDest)
942 CreatedBranchToNormalDest->setDebugLoc(Loc);
943 } else if (!Returns.empty()) {
944 // Otherwise, if there is exactly one return value, just replace anything
945 // using the return value of the call with the computed value.
946 if (!TheCall->use_empty()) {
947 if (TheCall == Returns[0]->getReturnValue())
948 TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType()));
950 TheCall->replaceAllUsesWith(Returns[0]->getReturnValue());
953 // Update PHI nodes that use the ReturnBB to use the AfterCallBB.
954 BasicBlock *ReturnBB = Returns[0]->getParent();
955 ReturnBB->replaceAllUsesWith(AfterCallBB);
957 // Splice the code from the return block into the block that it will return
958 // to, which contains the code that was after the call.
959 AfterCallBB->getInstList().splice(AfterCallBB->begin(),
960 ReturnBB->getInstList());
962 if (CreatedBranchToNormalDest)
963 CreatedBranchToNormalDest->setDebugLoc(Returns[0]->getDebugLoc());
965 // Delete the return instruction now and empty ReturnBB now.
966 Returns[0]->eraseFromParent();
967 ReturnBB->eraseFromParent();
968 } else if (!TheCall->use_empty()) {
969 // No returns, but something is using the return value of the call. Just
971 TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType()));
974 // Since we are now done with the Call/Invoke, we can delete it.
975 TheCall->eraseFromParent();
977 // If we inlined any musttail calls and the original return is now
978 // unreachable, delete it. It can only contain a bitcast and ret.
979 if (InlinedMustTailCalls && pred_begin(AfterCallBB) == pred_end(AfterCallBB))
980 AfterCallBB->eraseFromParent();
982 // We should always be able to fold the entry block of the function into the
983 // single predecessor of the block...
984 assert(cast<BranchInst>(Br)->isUnconditional() && "splitBasicBlock broken!");
985 BasicBlock *CalleeEntry = cast<BranchInst>(Br)->getSuccessor(0);
987 // Splice the code entry block into calling block, right before the
988 // unconditional branch.
989 CalleeEntry->replaceAllUsesWith(OrigBB); // Update PHI nodes
990 OrigBB->getInstList().splice(Br, CalleeEntry->getInstList());
992 // Remove the unconditional branch.
993 OrigBB->getInstList().erase(Br);
995 // Now we can remove the CalleeEntry block, which is now empty.
996 Caller->getBasicBlockList().erase(CalleeEntry);
998 // If we inserted a phi node, check to see if it has a single value (e.g. all
999 // the entries are the same or undef). If so, remove the PHI so it doesn't
1000 // block other optimizations.
1002 if (Value *V = SimplifyInstruction(PHI, IFI.DL)) {
1003 PHI->replaceAllUsesWith(V);
1004 PHI->eraseFromParent();