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 // The code in this file for handling inlines through invoke
14 // instructions preserves semantics only under some assumptions about
15 // the behavior of unwinders which correspond to gcc-style libUnwind
16 // exception personality functions. Eventually the IR will be
17 // improved to make this unnecessary, but until then, this code is
18 // marked [LIBUNWIND].
20 //===----------------------------------------------------------------------===//
22 #include "llvm/Transforms/Utils/Cloning.h"
23 #include "llvm/Constants.h"
24 #include "llvm/DerivedTypes.h"
25 #include "llvm/Module.h"
26 #include "llvm/Instructions.h"
27 #include "llvm/IntrinsicInst.h"
28 #include "llvm/Intrinsics.h"
29 #include "llvm/Attributes.h"
30 #include "llvm/Analysis/CallGraph.h"
31 #include "llvm/Analysis/DebugInfo.h"
32 #include "llvm/Analysis/InstructionSimplify.h"
33 #include "llvm/Target/TargetData.h"
34 #include "llvm/Transforms/Utils/Local.h"
35 #include "llvm/ADT/SmallVector.h"
36 #include "llvm/ADT/StringExtras.h"
37 #include "llvm/Support/CallSite.h"
38 #include "llvm/Support/IRBuilder.h"
41 bool llvm::InlineFunction(CallInst *CI, InlineFunctionInfo &IFI) {
42 return InlineFunction(CallSite(CI), IFI);
44 bool llvm::InlineFunction(InvokeInst *II, InlineFunctionInfo &IFI) {
45 return InlineFunction(CallSite(II), IFI);
48 /// [LIBUNWIND] Find the (possibly absent) call to @llvm.eh.selector in
49 /// the given landing pad.
50 static EHSelectorInst *findSelectorForLandingPad(BasicBlock *lpad) {
51 // The llvm.eh.exception call is required to be in the landing pad.
52 for (BasicBlock::iterator i = lpad->begin(), e = lpad->end(); i != e; i++) {
53 EHExceptionInst *exn = dyn_cast<EHExceptionInst>(i);
56 EHSelectorInst *selector = 0;
57 for (Instruction::use_iterator
58 ui = exn->use_begin(), ue = exn->use_end(); ui != ue; ++ui) {
59 EHSelectorInst *sel = dyn_cast<EHSelectorInst>(*ui);
62 // Immediately accept an eh.selector in the landing pad.
63 if (sel->getParent() == lpad) return sel;
65 // Otherwise, use the first selector we see.
66 if (!selector) selector = sel;
76 /// A class for recording information about inlining through an invoke.
77 class InvokeInliningInfo {
78 BasicBlock *OuterUnwindDest;
79 EHSelectorInst *OuterSelector;
80 BasicBlock *InnerUnwindDest;
81 PHINode *InnerExceptionPHI;
82 PHINode *InnerSelectorPHI;
83 SmallVector<Value*, 8> UnwindDestPHIValues;
86 InvokeInliningInfo(InvokeInst *II) :
87 OuterUnwindDest(II->getUnwindDest()), OuterSelector(0),
88 InnerUnwindDest(0), InnerExceptionPHI(0), InnerSelectorPHI(0) {
90 // If there are PHI nodes in the unwind destination block, we
91 // need to keep track of which values came into them from the
92 // invoke before removing the edge from this block.
93 llvm::BasicBlock *invokeBB = II->getParent();
94 for (BasicBlock::iterator I = OuterUnwindDest->begin();
95 isa<PHINode>(I); ++I) {
96 // Save the value to use for this edge.
97 PHINode *phi = cast<PHINode>(I);
98 UnwindDestPHIValues.push_back(phi->getIncomingValueForBlock(invokeBB));
102 /// The outer unwind destination is the target of unwind edges
103 /// introduced for calls within the inlined function.
104 BasicBlock *getOuterUnwindDest() const {
105 return OuterUnwindDest;
108 EHSelectorInst *getOuterSelector() {
110 OuterSelector = findSelectorForLandingPad(OuterUnwindDest);
111 return OuterSelector;
114 BasicBlock *getInnerUnwindDest();
116 bool forwardEHResume(CallInst *call, BasicBlock *src);
118 /// Add incoming-PHI values to the unwind destination block for
119 /// the given basic block, using the values for the original
120 /// invoke's source block.
121 void addIncomingPHIValuesFor(BasicBlock *BB) const {
122 addIncomingPHIValuesForInto(BB, OuterUnwindDest);
125 void addIncomingPHIValuesForInto(BasicBlock *src, BasicBlock *dest) const {
126 BasicBlock::iterator I = dest->begin();
127 for (unsigned i = 0, e = UnwindDestPHIValues.size(); i != e; ++i, ++I) {
128 PHINode *phi = cast<PHINode>(I);
129 phi->addIncoming(UnwindDestPHIValues[i], src);
135 /// Get or create a target for the branch out of rewritten calls to
137 BasicBlock *InvokeInliningInfo::getInnerUnwindDest() {
138 if (InnerUnwindDest) return InnerUnwindDest;
140 // Find and hoist the llvm.eh.exception and llvm.eh.selector calls
141 // in the outer landing pad to immediately following the phis.
142 EHSelectorInst *selector = getOuterSelector();
143 if (!selector) return 0;
145 // The call to llvm.eh.exception *must* be in the landing pad.
146 Instruction *exn = cast<Instruction>(selector->getArgOperand(0));
147 assert(exn->getParent() == OuterUnwindDest);
149 // TODO: recognize when we've already done this, so that we don't
150 // get a linear number of these when inlining calls into lots of
151 // invokes with the same landing pad.
154 Instruction *splitPoint = exn->getParent()->getFirstNonPHI();
155 assert(splitPoint != selector && "selector-on-exception dominance broken!");
156 if (splitPoint == exn) {
157 selector->removeFromParent();
158 selector->insertAfter(exn);
159 splitPoint = selector->getNextNode();
161 exn->moveBefore(splitPoint);
162 selector->moveBefore(splitPoint);
165 // Split the landing pad.
166 InnerUnwindDest = OuterUnwindDest->splitBasicBlock(splitPoint,
167 OuterUnwindDest->getName() + ".body");
169 // The number of incoming edges we expect to the inner landing pad.
170 const unsigned phiCapacity = 2;
172 // Create corresponding new phis for all the phis in the outer landing pad.
173 BasicBlock::iterator insertPoint = InnerUnwindDest->begin();
174 BasicBlock::iterator I = OuterUnwindDest->begin();
175 for (unsigned i = 0, e = UnwindDestPHIValues.size(); i != e; ++i, ++I) {
176 PHINode *outerPhi = cast<PHINode>(I);
177 PHINode *innerPhi = PHINode::Create(outerPhi->getType(), phiCapacity,
178 outerPhi->getName() + ".lpad-body",
180 outerPhi->replaceAllUsesWith(innerPhi);
181 innerPhi->addIncoming(outerPhi, OuterUnwindDest);
184 // Create a phi for the exception value...
185 InnerExceptionPHI = PHINode::Create(exn->getType(), phiCapacity,
186 "exn.lpad-body", insertPoint);
187 exn->replaceAllUsesWith(InnerExceptionPHI);
188 selector->setArgOperand(0, exn); // restore this use
189 InnerExceptionPHI->addIncoming(exn, OuterUnwindDest);
191 // ...and the selector.
192 InnerSelectorPHI = PHINode::Create(selector->getType(), phiCapacity,
193 "selector.lpad-body", insertPoint);
194 selector->replaceAllUsesWith(InnerSelectorPHI);
195 InnerSelectorPHI->addIncoming(selector, OuterUnwindDest);
198 return InnerUnwindDest;
201 /// [LIBUNWIND] Try to forward the given call, which logically occurs
202 /// at the end of the given block, as a branch to the inner unwind
203 /// block. Returns true if the call was forwarded.
204 bool InvokeInliningInfo::forwardEHResume(CallInst *call, BasicBlock *src) {
205 // First, check whether this is a call to the intrinsic.
206 Function *fn = dyn_cast<Function>(call->getCalledValue());
207 if (!fn || fn->getName() != "llvm.eh.resume")
210 // At this point, we need to return true on all paths, because
211 // otherwise we'll construct an invoke of the intrinsic, which is
214 // Try to find or make an inner unwind dest, which will fail if we
215 // can't find a selector call for the outer unwind dest.
216 BasicBlock *dest = getInnerUnwindDest();
217 bool hasSelector = (dest != 0);
219 // If we failed, just use the outer unwind dest, dropping the
220 // exception and selector on the floor.
222 dest = OuterUnwindDest;
225 BranchInst::Create(dest, src);
227 // Update the phis in the destination. They were inserted in an
228 // order which makes this work.
229 addIncomingPHIValuesForInto(src, dest);
232 InnerExceptionPHI->addIncoming(call->getArgOperand(0), src);
233 InnerSelectorPHI->addIncoming(call->getArgOperand(1), src);
239 /// [LIBUNWIND] Check whether this selector is "only cleanups":
240 /// call i32 @llvm.eh.selector(blah, blah, i32 0)
241 static bool isCleanupOnlySelector(EHSelectorInst *selector) {
242 if (selector->getNumArgOperands() != 3) return false;
243 ConstantInt *val = dyn_cast<ConstantInt>(selector->getArgOperand(2));
244 return (val && val->isZero());
247 /// HandleCallsInBlockInlinedThroughInvoke - When we inline a basic block into
248 /// an invoke, we have to turn all of the calls that can throw into
249 /// invokes. This function analyze BB to see if there are any calls, and if so,
250 /// it rewrites them to be invokes that jump to InvokeDest and fills in the PHI
251 /// nodes in that block with the values specified in InvokeDestPHIValues.
253 /// Returns true to indicate that the next block should be skipped.
254 static bool HandleCallsInBlockInlinedThroughInvoke(BasicBlock *BB,
255 InvokeInliningInfo &Invoke) {
256 for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) {
257 Instruction *I = BBI++;
259 // We only need to check for function calls: inlined invoke
260 // instructions require no special handling.
261 CallInst *CI = dyn_cast<CallInst>(I);
262 if (CI == 0) continue;
264 // LIBUNWIND: merge selector instructions.
265 if (EHSelectorInst *Inner = dyn_cast<EHSelectorInst>(CI)) {
266 EHSelectorInst *Outer = Invoke.getOuterSelector();
267 if (!Outer) continue;
269 bool innerIsOnlyCleanup = isCleanupOnlySelector(Inner);
270 bool outerIsOnlyCleanup = isCleanupOnlySelector(Outer);
272 // If both selectors contain only cleanups, we don't need to do
273 // anything. TODO: this is really just a very specific instance
274 // of a much more general optimization.
275 if (innerIsOnlyCleanup && outerIsOnlyCleanup) continue;
277 // Otherwise, we just append the outer selector to the inner selector.
278 SmallVector<Value*, 16> NewSelector;
279 for (unsigned i = 0, e = Inner->getNumArgOperands(); i != e; ++i)
280 NewSelector.push_back(Inner->getArgOperand(i));
281 for (unsigned i = 2, e = Outer->getNumArgOperands(); i != e; ++i)
282 NewSelector.push_back(Outer->getArgOperand(i));
284 CallInst *NewInner = CallInst::Create(Inner->getCalledValue(),
289 // No need to copy attributes, calling convention, etc.
290 NewInner->takeName(Inner);
291 Inner->replaceAllUsesWith(NewInner);
292 Inner->eraseFromParent();
296 // If this call cannot unwind, don't convert it to an invoke.
297 if (CI->doesNotThrow())
300 // Convert this function call into an invoke instruction.
301 // First, split the basic block.
302 BasicBlock *Split = BB->splitBasicBlock(CI, CI->getName()+".noexc");
304 // Delete the unconditional branch inserted by splitBasicBlock
305 BB->getInstList().pop_back();
307 // LIBUNWIND: If this is a call to @llvm.eh.resume, just branch
308 // directly to the new landing pad.
309 if (Invoke.forwardEHResume(CI, BB)) {
310 // TODO: 'Split' is now unreachable; clean it up.
312 // We want to leave the original call intact so that the call
313 // graph and other structures won't get misled. We also have to
314 // avoid processing the next block, or we'll iterate here forever.
318 // Otherwise, create the new invoke instruction.
319 ImmutableCallSite CS(CI);
320 SmallVector<Value*, 8> InvokeArgs(CS.arg_begin(), CS.arg_end());
322 InvokeInst::Create(CI->getCalledValue(), Split,
323 Invoke.getOuterUnwindDest(),
324 InvokeArgs.begin(), InvokeArgs.end(),
326 II->setCallingConv(CI->getCallingConv());
327 II->setAttributes(CI->getAttributes());
329 // Make sure that anything using the call now uses the invoke! This also
330 // updates the CallGraph if present, because it uses a WeakVH.
331 CI->replaceAllUsesWith(II);
333 Split->getInstList().pop_front(); // Delete the original call
335 // Update any PHI nodes in the exceptional block to indicate that
336 // there is now a new entry in them.
337 Invoke.addIncomingPHIValuesFor(BB);
345 /// HandleInlinedInvoke - If we inlined an invoke site, we need to convert calls
346 /// in the body of the inlined function into invokes and turn unwind
347 /// instructions into branches to the invoke unwind dest.
349 /// II is the invoke instruction being inlined. FirstNewBlock is the first
350 /// block of the inlined code (the last block is the end of the function),
351 /// and InlineCodeInfo is information about the code that got inlined.
352 static void HandleInlinedInvoke(InvokeInst *II, BasicBlock *FirstNewBlock,
353 ClonedCodeInfo &InlinedCodeInfo) {
354 BasicBlock *InvokeDest = II->getUnwindDest();
356 Function *Caller = FirstNewBlock->getParent();
358 // The inlined code is currently at the end of the function, scan from the
359 // start of the inlined code to its end, checking for stuff we need to
360 // rewrite. If the code doesn't have calls or unwinds, we know there is
361 // nothing to rewrite.
362 if (!InlinedCodeInfo.ContainsCalls && !InlinedCodeInfo.ContainsUnwinds) {
363 // Now that everything is happy, we have one final detail. The PHI nodes in
364 // the exception destination block still have entries due to the original
365 // invoke instruction. Eliminate these entries (which might even delete the
367 InvokeDest->removePredecessor(II->getParent());
371 InvokeInliningInfo Invoke(II);
373 for (Function::iterator BB = FirstNewBlock, E = Caller->end(); BB != E; ++BB){
374 if (InlinedCodeInfo.ContainsCalls)
375 if (HandleCallsInBlockInlinedThroughInvoke(BB, Invoke)) {
376 // Honor a request to skip the next block. We don't need to
377 // consider UnwindInsts in this case either.
382 if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) {
383 // An UnwindInst requires special handling when it gets inlined into an
384 // invoke site. Once this happens, we know that the unwind would cause
385 // a control transfer to the invoke exception destination, so we can
386 // transform it into a direct branch to the exception destination.
387 BranchInst::Create(InvokeDest, UI);
389 // Delete the unwind instruction!
390 UI->eraseFromParent();
392 // Update any PHI nodes in the exceptional block to indicate that
393 // there is now a new entry in them.
394 Invoke.addIncomingPHIValuesFor(BB);
398 // Now that everything is happy, we have one final detail. The PHI nodes in
399 // the exception destination block still have entries due to the original
400 // invoke instruction. Eliminate these entries (which might even delete the
402 InvokeDest->removePredecessor(II->getParent());
405 /// UpdateCallGraphAfterInlining - Once we have cloned code over from a callee
406 /// into the caller, update the specified callgraph to reflect the changes we
407 /// made. Note that it's possible that not all code was copied over, so only
408 /// some edges of the callgraph may remain.
409 static void UpdateCallGraphAfterInlining(CallSite CS,
410 Function::iterator FirstNewBlock,
411 ValueToValueMapTy &VMap,
412 InlineFunctionInfo &IFI) {
413 CallGraph &CG = *IFI.CG;
414 const Function *Caller = CS.getInstruction()->getParent()->getParent();
415 const Function *Callee = CS.getCalledFunction();
416 CallGraphNode *CalleeNode = CG[Callee];
417 CallGraphNode *CallerNode = CG[Caller];
419 // Since we inlined some uninlined call sites in the callee into the caller,
420 // add edges from the caller to all of the callees of the callee.
421 CallGraphNode::iterator I = CalleeNode->begin(), E = CalleeNode->end();
423 // Consider the case where CalleeNode == CallerNode.
424 CallGraphNode::CalledFunctionsVector CallCache;
425 if (CalleeNode == CallerNode) {
426 CallCache.assign(I, E);
427 I = CallCache.begin();
431 for (; I != E; ++I) {
432 const Value *OrigCall = I->first;
434 ValueToValueMapTy::iterator VMI = VMap.find(OrigCall);
435 // Only copy the edge if the call was inlined!
436 if (VMI == VMap.end() || VMI->second == 0)
439 // If the call was inlined, but then constant folded, there is no edge to
440 // add. Check for this case.
441 Instruction *NewCall = dyn_cast<Instruction>(VMI->second);
442 if (NewCall == 0) continue;
444 // Remember that this call site got inlined for the client of
446 IFI.InlinedCalls.push_back(NewCall);
448 // It's possible that inlining the callsite will cause it to go from an
449 // indirect to a direct call by resolving a function pointer. If this
450 // happens, set the callee of the new call site to a more precise
451 // destination. This can also happen if the call graph node of the caller
452 // was just unnecessarily imprecise.
453 if (I->second->getFunction() == 0)
454 if (Function *F = CallSite(NewCall).getCalledFunction()) {
455 // Indirect call site resolved to direct call.
456 CallerNode->addCalledFunction(CallSite(NewCall), CG[F]);
461 CallerNode->addCalledFunction(CallSite(NewCall), I->second);
464 // Update the call graph by deleting the edge from Callee to Caller. We must
465 // do this after the loop above in case Caller and Callee are the same.
466 CallerNode->removeCallEdgeFor(CS);
469 /// HandleByValArgument - When inlining a call site that has a byval argument,
470 /// we have to make the implicit memcpy explicit by adding it.
471 static Value *HandleByValArgument(Value *Arg, Instruction *TheCall,
472 const Function *CalledFunc,
473 InlineFunctionInfo &IFI,
474 unsigned ByValAlignment) {
475 const Type *AggTy = cast<PointerType>(Arg->getType())->getElementType();
477 // If the called function is readonly, then it could not mutate the caller's
478 // copy of the byval'd memory. In this case, it is safe to elide the copy and
480 if (CalledFunc->onlyReadsMemory()) {
481 // If the byval argument has a specified alignment that is greater than the
482 // passed in pointer, then we either have to round up the input pointer or
483 // give up on this transformation.
484 if (ByValAlignment <= 1) // 0 = unspecified, 1 = no particular alignment.
487 // If the pointer is already known to be sufficiently aligned, or if we can
488 // round it up to a larger alignment, then we don't need a temporary.
489 if (getOrEnforceKnownAlignment(Arg, ByValAlignment,
490 IFI.TD) >= ByValAlignment)
493 // Otherwise, we have to make a memcpy to get a safe alignment. This is bad
494 // for code quality, but rarely happens and is required for correctness.
497 LLVMContext &Context = Arg->getContext();
499 const Type *VoidPtrTy = Type::getInt8PtrTy(Context);
501 // Create the alloca. If we have TargetData, use nice alignment.
504 Align = IFI.TD->getPrefTypeAlignment(AggTy);
506 // If the byval had an alignment specified, we *must* use at least that
507 // alignment, as it is required by the byval argument (and uses of the
508 // pointer inside the callee).
509 Align = std::max(Align, ByValAlignment);
511 Function *Caller = TheCall->getParent()->getParent();
513 Value *NewAlloca = new AllocaInst(AggTy, 0, Align, Arg->getName(),
514 &*Caller->begin()->begin());
516 const Type *Tys[3] = {VoidPtrTy, VoidPtrTy, Type::getInt64Ty(Context)};
517 Function *MemCpyFn = Intrinsic::getDeclaration(Caller->getParent(),
520 Value *DestCast = new BitCastInst(NewAlloca, VoidPtrTy, "tmp", TheCall);
521 Value *SrcCast = new BitCastInst(Arg, VoidPtrTy, "tmp", TheCall);
525 Size = ConstantExpr::getSizeOf(AggTy);
527 Size = ConstantInt::get(Type::getInt64Ty(Context),
528 IFI.TD->getTypeStoreSize(AggTy));
530 // Always generate a memcpy of alignment 1 here because we don't know
531 // the alignment of the src pointer. Other optimizations can infer
533 Value *CallArgs[] = {
534 DestCast, SrcCast, Size,
535 ConstantInt::get(Type::getInt32Ty(Context), 1),
536 ConstantInt::getFalse(Context) // isVolatile
538 CallInst::Create(MemCpyFn, CallArgs, CallArgs+5, "", TheCall);
540 // Uses of the argument in the function should use our new alloca
545 // isUsedByLifetimeMarker - Check whether this Value is used by a lifetime
547 static bool isUsedByLifetimeMarker(Value *V) {
548 for (Value::use_iterator UI = V->use_begin(), UE = V->use_end(); UI != UE;
550 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(*UI)) {
551 switch (II->getIntrinsicID()) {
553 case Intrinsic::lifetime_start:
554 case Intrinsic::lifetime_end:
562 // hasLifetimeMarkers - Check whether the given alloca already has
563 // lifetime.start or lifetime.end intrinsics.
564 static bool hasLifetimeMarkers(AllocaInst *AI) {
565 const Type *Int8PtrTy = Type::getInt8PtrTy(AI->getType()->getContext());
566 if (AI->getType() == Int8PtrTy)
567 return isUsedByLifetimeMarker(AI);
569 // Do a scan to find all the bitcasts to i8*.
570 for (Value::use_iterator I = AI->use_begin(), E = AI->use_end(); I != E;
572 if (I->getType() != Int8PtrTy) continue;
573 if (!isa<BitCastInst>(*I)) continue;
574 if (isUsedByLifetimeMarker(*I))
580 // InlineFunction - This function inlines the called function into the basic
581 // block of the caller. This returns false if it is not possible to inline this
582 // call. The program is still in a well defined state if this occurs though.
584 // Note that this only does one level of inlining. For example, if the
585 // instruction 'call B' is inlined, and 'B' calls 'C', then the call to 'C' now
586 // exists in the instruction stream. Similarly this will inline a recursive
587 // function by one level.
589 bool llvm::InlineFunction(CallSite CS, InlineFunctionInfo &IFI) {
590 Instruction *TheCall = CS.getInstruction();
591 LLVMContext &Context = TheCall->getContext();
592 assert(TheCall->getParent() && TheCall->getParent()->getParent() &&
593 "Instruction not in function!");
595 // If IFI has any state in it, zap it before we fill it in.
598 const Function *CalledFunc = CS.getCalledFunction();
599 if (CalledFunc == 0 || // Can't inline external function or indirect
600 CalledFunc->isDeclaration() || // call, or call to a vararg function!
601 CalledFunc->getFunctionType()->isVarArg()) return false;
603 // If the call to the callee is not a tail call, we must clear the 'tail'
604 // flags on any calls that we inline.
605 bool MustClearTailCallFlags =
606 !(isa<CallInst>(TheCall) && cast<CallInst>(TheCall)->isTailCall());
608 // If the call to the callee cannot throw, set the 'nounwind' flag on any
609 // calls that we inline.
610 bool MarkNoUnwind = CS.doesNotThrow();
612 BasicBlock *OrigBB = TheCall->getParent();
613 Function *Caller = OrigBB->getParent();
615 // GC poses two hazards to inlining, which only occur when the callee has GC:
616 // 1. If the caller has no GC, then the callee's GC must be propagated to the
618 // 2. If the caller has a differing GC, it is invalid to inline.
619 if (CalledFunc->hasGC()) {
620 if (!Caller->hasGC())
621 Caller->setGC(CalledFunc->getGC());
622 else if (CalledFunc->getGC() != Caller->getGC())
626 // Get an iterator to the last basic block in the function, which will have
627 // the new function inlined after it.
629 Function::iterator LastBlock = &Caller->back();
631 // Make sure to capture all of the return instructions from the cloned
633 SmallVector<ReturnInst*, 8> Returns;
634 ClonedCodeInfo InlinedFunctionInfo;
635 Function::iterator FirstNewBlock;
637 { // Scope to destroy VMap after cloning.
638 ValueToValueMapTy VMap;
640 assert(CalledFunc->arg_size() == CS.arg_size() &&
641 "No varargs calls can be inlined!");
643 // Calculate the vector of arguments to pass into the function cloner, which
644 // matches up the formal to the actual argument values.
645 CallSite::arg_iterator AI = CS.arg_begin();
647 for (Function::const_arg_iterator I = CalledFunc->arg_begin(),
648 E = CalledFunc->arg_end(); I != E; ++I, ++AI, ++ArgNo) {
649 Value *ActualArg = *AI;
651 // When byval arguments actually inlined, we need to make the copy implied
652 // by them explicit. However, we don't do this if the callee is readonly
653 // or readnone, because the copy would be unneeded: the callee doesn't
654 // modify the struct.
655 if (CalledFunc->paramHasAttr(ArgNo+1, Attribute::ByVal)) {
656 ActualArg = HandleByValArgument(ActualArg, TheCall, CalledFunc, IFI,
657 CalledFunc->getParamAlignment(ArgNo+1));
659 // Calls that we inline may use the new alloca, so we need to clear
660 // their 'tail' flags if HandleByValArgument introduced a new alloca and
661 // the callee has calls.
662 MustClearTailCallFlags |= ActualArg != *AI;
668 // We want the inliner to prune the code as it copies. We would LOVE to
669 // have no dead or constant instructions leftover after inlining occurs
670 // (which can happen, e.g., because an argument was constant), but we'll be
671 // happy with whatever the cloner can do.
672 CloneAndPruneFunctionInto(Caller, CalledFunc, VMap,
673 /*ModuleLevelChanges=*/false, Returns, ".i",
674 &InlinedFunctionInfo, IFI.TD, TheCall);
676 // Remember the first block that is newly cloned over.
677 FirstNewBlock = LastBlock; ++FirstNewBlock;
679 // Update the callgraph if requested.
681 UpdateCallGraphAfterInlining(CS, FirstNewBlock, VMap, IFI);
684 // If there are any alloca instructions in the block that used to be the entry
685 // block for the callee, move them to the entry block of the caller. First
686 // calculate which instruction they should be inserted before. We insert the
687 // instructions at the end of the current alloca list.
690 BasicBlock::iterator InsertPoint = Caller->begin()->begin();
691 for (BasicBlock::iterator I = FirstNewBlock->begin(),
692 E = FirstNewBlock->end(); I != E; ) {
693 AllocaInst *AI = dyn_cast<AllocaInst>(I++);
694 if (AI == 0) continue;
696 // If the alloca is now dead, remove it. This often occurs due to code
698 if (AI->use_empty()) {
699 AI->eraseFromParent();
703 if (!isa<Constant>(AI->getArraySize()))
706 // Keep track of the static allocas that we inline into the caller.
707 IFI.StaticAllocas.push_back(AI);
709 // Scan for the block of allocas that we can move over, and move them
711 while (isa<AllocaInst>(I) &&
712 isa<Constant>(cast<AllocaInst>(I)->getArraySize())) {
713 IFI.StaticAllocas.push_back(cast<AllocaInst>(I));
717 // Transfer all of the allocas over in a block. Using splice means
718 // that the instructions aren't removed from the symbol table, then
720 Caller->getEntryBlock().getInstList().splice(InsertPoint,
721 FirstNewBlock->getInstList(),
726 // Leave lifetime markers for the static alloca's, scoping them to the
727 // function we just inlined.
728 if (!IFI.StaticAllocas.empty()) {
729 // Also preserve the call graph, if applicable.
730 CallGraphNode *StartCGN = 0, *EndCGN = 0, *CallerNode = 0;
731 if (CallGraph *CG = IFI.CG) {
732 Function *Start = Intrinsic::getDeclaration(Caller->getParent(),
733 Intrinsic::lifetime_start);
734 Function *End = Intrinsic::getDeclaration(Caller->getParent(),
735 Intrinsic::lifetime_end);
736 StartCGN = CG->getOrInsertFunction(Start);
737 EndCGN = CG->getOrInsertFunction(End);
738 CallerNode = (*CG)[Caller];
741 IRBuilder<> builder(FirstNewBlock->begin());
742 for (unsigned ai = 0, ae = IFI.StaticAllocas.size(); ai != ae; ++ai) {
743 AllocaInst *AI = IFI.StaticAllocas[ai];
745 // If the alloca is already scoped to something smaller than the whole
746 // function then there's no need to add redundant, less accurate markers.
747 if (hasLifetimeMarkers(AI))
750 builder.CreateLifetimeStart(AI);
751 for (unsigned ri = 0, re = Returns.size(); ri != re; ++ri) {
752 IRBuilder<> builder(Returns[ri]);
753 builder.CreateLifetimeEnd(AI);
758 // If the inlined code contained dynamic alloca instructions, wrap the inlined
759 // code with llvm.stacksave/llvm.stackrestore intrinsics.
760 if (InlinedFunctionInfo.ContainsDynamicAllocas) {
761 Module *M = Caller->getParent();
762 // Get the two intrinsics we care about.
763 Function *StackSave = Intrinsic::getDeclaration(M, Intrinsic::stacksave);
764 Function *StackRestore=Intrinsic::getDeclaration(M,Intrinsic::stackrestore);
766 // Insert the llvm.stacksave.
767 CallInst *SavedPtr = CallInst::Create(StackSave, "savedstack",
768 FirstNewBlock->begin());
770 // Insert a call to llvm.stackrestore before any return instructions in the
772 for (unsigned i = 0, e = Returns.size(); i != e; ++i) {
773 CallInst::Create(StackRestore, SavedPtr, "", Returns[i]);
776 // Count the number of StackRestore calls we insert.
777 unsigned NumStackRestores = Returns.size();
779 // If we are inlining an invoke instruction, insert restores before each
780 // unwind. These unwinds will be rewritten into branches later.
781 if (InlinedFunctionInfo.ContainsUnwinds && isa<InvokeInst>(TheCall)) {
782 for (Function::iterator BB = FirstNewBlock, E = Caller->end();
784 if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) {
785 CallInst::Create(StackRestore, SavedPtr, "", UI);
791 // If we are inlining tail call instruction through a call site that isn't
792 // marked 'tail', we must remove the tail marker for any calls in the inlined
793 // code. Also, calls inlined through a 'nounwind' call site should be marked
795 if (InlinedFunctionInfo.ContainsCalls &&
796 (MustClearTailCallFlags || MarkNoUnwind)) {
797 for (Function::iterator BB = FirstNewBlock, E = Caller->end();
799 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
800 if (CallInst *CI = dyn_cast<CallInst>(I)) {
801 if (MustClearTailCallFlags)
802 CI->setTailCall(false);
804 CI->setDoesNotThrow();
808 // If we are inlining through a 'nounwind' call site then any inlined 'unwind'
809 // instructions are unreachable.
810 if (InlinedFunctionInfo.ContainsUnwinds && MarkNoUnwind)
811 for (Function::iterator BB = FirstNewBlock, E = Caller->end();
813 TerminatorInst *Term = BB->getTerminator();
814 if (isa<UnwindInst>(Term)) {
815 new UnreachableInst(Context, Term);
816 BB->getInstList().erase(Term);
820 // If we are inlining for an invoke instruction, we must make sure to rewrite
821 // any inlined 'unwind' instructions into branches to the invoke exception
822 // destination, and call instructions into invoke instructions.
823 if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall))
824 HandleInlinedInvoke(II, FirstNewBlock, InlinedFunctionInfo);
826 // If we cloned in _exactly one_ basic block, and if that block ends in a
827 // return instruction, we splice the body of the inlined callee directly into
828 // the calling basic block.
829 if (Returns.size() == 1 && std::distance(FirstNewBlock, Caller->end()) == 1) {
830 // Move all of the instructions right before the call.
831 OrigBB->getInstList().splice(TheCall, FirstNewBlock->getInstList(),
832 FirstNewBlock->begin(), FirstNewBlock->end());
833 // Remove the cloned basic block.
834 Caller->getBasicBlockList().pop_back();
836 // If the call site was an invoke instruction, add a branch to the normal
838 if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall))
839 BranchInst::Create(II->getNormalDest(), TheCall);
841 // If the return instruction returned a value, replace uses of the call with
842 // uses of the returned value.
843 if (!TheCall->use_empty()) {
844 ReturnInst *R = Returns[0];
845 if (TheCall == R->getReturnValue())
846 TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType()));
848 TheCall->replaceAllUsesWith(R->getReturnValue());
850 // Since we are now done with the Call/Invoke, we can delete it.
851 TheCall->eraseFromParent();
853 // Since we are now done with the return instruction, delete it also.
854 Returns[0]->eraseFromParent();
856 // We are now done with the inlining.
860 // Otherwise, we have the normal case, of more than one block to inline or
861 // multiple return sites.
863 // We want to clone the entire callee function into the hole between the
864 // "starter" and "ender" blocks. How we accomplish this depends on whether
865 // this is an invoke instruction or a call instruction.
866 BasicBlock *AfterCallBB;
867 if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall)) {
869 // Add an unconditional branch to make this look like the CallInst case...
870 BranchInst *NewBr = BranchInst::Create(II->getNormalDest(), TheCall);
872 // Split the basic block. This guarantees that no PHI nodes will have to be
873 // updated due to new incoming edges, and make the invoke case more
874 // symmetric to the call case.
875 AfterCallBB = OrigBB->splitBasicBlock(NewBr,
876 CalledFunc->getName()+".exit");
878 } else { // It's a call
879 // If this is a call instruction, we need to split the basic block that
880 // the call lives in.
882 AfterCallBB = OrigBB->splitBasicBlock(TheCall,
883 CalledFunc->getName()+".exit");
886 // Change the branch that used to go to AfterCallBB to branch to the first
887 // basic block of the inlined function.
889 TerminatorInst *Br = OrigBB->getTerminator();
890 assert(Br && Br->getOpcode() == Instruction::Br &&
891 "splitBasicBlock broken!");
892 Br->setOperand(0, FirstNewBlock);
895 // Now that the function is correct, make it a little bit nicer. In
896 // particular, move the basic blocks inserted from the end of the function
897 // into the space made by splitting the source basic block.
898 Caller->getBasicBlockList().splice(AfterCallBB, Caller->getBasicBlockList(),
899 FirstNewBlock, Caller->end());
901 // Handle all of the return instructions that we just cloned in, and eliminate
902 // any users of the original call/invoke instruction.
903 const Type *RTy = CalledFunc->getReturnType();
906 if (Returns.size() > 1) {
907 // The PHI node should go at the front of the new basic block to merge all
908 // possible incoming values.
909 if (!TheCall->use_empty()) {
910 PHI = PHINode::Create(RTy, Returns.size(), TheCall->getName(),
911 AfterCallBB->begin());
912 // Anything that used the result of the function call should now use the
913 // PHI node as their operand.
914 TheCall->replaceAllUsesWith(PHI);
917 // Loop over all of the return instructions adding entries to the PHI node
920 for (unsigned i = 0, e = Returns.size(); i != e; ++i) {
921 ReturnInst *RI = Returns[i];
922 assert(RI->getReturnValue()->getType() == PHI->getType() &&
923 "Ret value not consistent in function!");
924 PHI->addIncoming(RI->getReturnValue(), RI->getParent());
929 // 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::Create(AfterCallBB, RI);
933 RI->eraseFromParent();
935 } else if (!Returns.empty()) {
936 // Otherwise, if there is exactly one return value, just replace anything
937 // using the return value of the call with the computed value.
938 if (!TheCall->use_empty()) {
939 if (TheCall == Returns[0]->getReturnValue())
940 TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType()));
942 TheCall->replaceAllUsesWith(Returns[0]->getReturnValue());
945 // Splice the code from the return block into the block that it will return
946 // to, which contains the code that was after the call.
947 BasicBlock *ReturnBB = Returns[0]->getParent();
948 AfterCallBB->getInstList().splice(AfterCallBB->begin(),
949 ReturnBB->getInstList());
951 // Update PHI nodes that use the ReturnBB to use the AfterCallBB.
952 ReturnBB->replaceAllUsesWith(AfterCallBB);
954 // Delete the return instruction now and empty ReturnBB now.
955 Returns[0]->eraseFromParent();
956 ReturnBB->eraseFromParent();
957 } else if (!TheCall->use_empty()) {
958 // No returns, but something is using the return value of the call. Just
960 TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType()));
963 // Since we are now done with the Call/Invoke, we can delete it.
964 TheCall->eraseFromParent();
966 // We should always be able to fold the entry block of the function into the
967 // single predecessor of the block...
968 assert(cast<BranchInst>(Br)->isUnconditional() && "splitBasicBlock broken!");
969 BasicBlock *CalleeEntry = cast<BranchInst>(Br)->getSuccessor(0);
971 // Splice the code entry block into calling block, right before the
972 // unconditional branch.
973 OrigBB->getInstList().splice(Br, CalleeEntry->getInstList());
974 CalleeEntry->replaceAllUsesWith(OrigBB); // Update PHI nodes
976 // Remove the unconditional branch.
977 OrigBB->getInstList().erase(Br);
979 // Now we can remove the CalleeEntry block, which is now empty.
980 Caller->getBasicBlockList().erase(CalleeEntry);
982 // If we inserted a phi node, check to see if it has a single value (e.g. all
983 // the entries are the same or undef). If so, remove the PHI so it doesn't
984 // block other optimizations.
986 if (Value *V = SimplifyInstruction(PHI, IFI.TD)) {
987 PHI->replaceAllUsesWith(V);
988 PHI->eraseFromParent();