1 //===- Inliner.cpp - Code common to all inliners --------------------------===//
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 the mechanics required to implement inlining without
11 // missing any calls and updating the call graph. The decisions of which calls
12 // are profitable to inline are implemented elsewhere.
14 //===----------------------------------------------------------------------===//
16 #define DEBUG_TYPE "inline"
17 #include "llvm/Transforms/IPO/InlinerPass.h"
18 #include "llvm/ADT/SmallPtrSet.h"
19 #include "llvm/ADT/Statistic.h"
20 #include "llvm/Analysis/CallGraph.h"
21 #include "llvm/Analysis/InlineCost.h"
22 #include "llvm/IR/CallSite.h"
23 #include "llvm/IR/DataLayout.h"
24 #include "llvm/IR/DiagnosticInfo.h"
25 #include "llvm/IR/Instructions.h"
26 #include "llvm/IR/IntrinsicInst.h"
27 #include "llvm/IR/Module.h"
28 #include "llvm/Support/CommandLine.h"
29 #include "llvm/Support/Debug.h"
30 #include "llvm/Support/raw_ostream.h"
31 #include "llvm/Target/TargetLibraryInfo.h"
32 #include "llvm/Transforms/Utils/Cloning.h"
33 #include "llvm/Transforms/Utils/Local.h"
36 STATISTIC(NumInlined, "Number of functions inlined");
37 STATISTIC(NumCallsDeleted, "Number of call sites deleted, not inlined");
38 STATISTIC(NumDeleted, "Number of functions deleted because all callers found");
39 STATISTIC(NumMergedAllocas, "Number of allocas merged together");
41 // This weirdly named statistic tracks the number of times that, when attempting
42 // to inline a function A into B, we analyze the callers of B in order to see
43 // if those would be more profitable and blocked inline steps.
44 STATISTIC(NumCallerCallersAnalyzed, "Number of caller-callers analyzed");
47 InlineLimit("inline-threshold", cl::Hidden, cl::init(225), cl::ZeroOrMore,
48 cl::desc("Control the amount of inlining to perform (default = 225)"));
51 HintThreshold("inlinehint-threshold", cl::Hidden, cl::init(325),
52 cl::desc("Threshold for inlining functions with inline hint"));
54 // We instroduce this threshold to help performance of instrumentation based
55 // PGO before we actually hook up inliner with analysis passes such as BPI and
58 ColdThreshold("inlinecold-threshold", cl::Hidden, cl::init(225),
59 cl::desc("Threshold for inlining functions with cold attribute"));
61 // Threshold to use when optsize is specified (and there is no -inline-limit).
62 const int OptSizeThreshold = 75;
64 Inliner::Inliner(char &ID)
65 : CallGraphSCCPass(ID), InlineThreshold(InlineLimit), InsertLifetime(true) {}
67 Inliner::Inliner(char &ID, int Threshold, bool InsertLifetime)
68 : CallGraphSCCPass(ID), InlineThreshold(InlineLimit.getNumOccurrences() > 0 ?
69 InlineLimit : Threshold),
70 InsertLifetime(InsertLifetime) {}
72 /// getAnalysisUsage - For this class, we declare that we require and preserve
73 /// the call graph. If the derived class implements this method, it should
74 /// always explicitly call the implementation here.
75 void Inliner::getAnalysisUsage(AnalysisUsage &AU) const {
76 CallGraphSCCPass::getAnalysisUsage(AU);
80 typedef DenseMap<ArrayType*, std::vector<AllocaInst*> >
81 InlinedArrayAllocasTy;
83 /// \brief If the inlined function had a higher stack protection level than the
84 /// calling function, then bump up the caller's stack protection level.
85 static void AdjustCallerSSPLevel(Function *Caller, Function *Callee) {
86 // If upgrading the SSP attribute, clear out the old SSP Attributes first.
87 // Having multiple SSP attributes doesn't actually hurt, but it adds useless
90 B.addAttribute(Attribute::StackProtect)
91 .addAttribute(Attribute::StackProtectStrong);
92 AttributeSet OldSSPAttr = AttributeSet::get(Caller->getContext(),
93 AttributeSet::FunctionIndex,
95 AttributeSet CallerAttr = Caller->getAttributes(),
96 CalleeAttr = Callee->getAttributes();
98 if (CalleeAttr.hasAttribute(AttributeSet::FunctionIndex,
99 Attribute::StackProtectReq)) {
100 Caller->removeAttributes(AttributeSet::FunctionIndex, OldSSPAttr);
101 Caller->addFnAttr(Attribute::StackProtectReq);
102 } else if (CalleeAttr.hasAttribute(AttributeSet::FunctionIndex,
103 Attribute::StackProtectStrong) &&
104 !CallerAttr.hasAttribute(AttributeSet::FunctionIndex,
105 Attribute::StackProtectReq)) {
106 Caller->removeAttributes(AttributeSet::FunctionIndex, OldSSPAttr);
107 Caller->addFnAttr(Attribute::StackProtectStrong);
108 } else if (CalleeAttr.hasAttribute(AttributeSet::FunctionIndex,
109 Attribute::StackProtect) &&
110 !CallerAttr.hasAttribute(AttributeSet::FunctionIndex,
111 Attribute::StackProtectReq) &&
112 !CallerAttr.hasAttribute(AttributeSet::FunctionIndex,
113 Attribute::StackProtectStrong))
114 Caller->addFnAttr(Attribute::StackProtect);
117 /// InlineCallIfPossible - If it is possible to inline the specified call site,
118 /// do so and update the CallGraph for this operation.
120 /// This function also does some basic book-keeping to update the IR. The
121 /// InlinedArrayAllocas map keeps track of any allocas that are already
122 /// available from other functions inlined into the caller. If we are able to
123 /// inline this call site we attempt to reuse already available allocas or add
124 /// any new allocas to the set if not possible.
125 static bool InlineCallIfPossible(CallSite CS, InlineFunctionInfo &IFI,
126 InlinedArrayAllocasTy &InlinedArrayAllocas,
127 int InlineHistory, bool InsertLifetime,
128 const DataLayout *DL) {
129 Function *Callee = CS.getCalledFunction();
130 Function *Caller = CS.getCaller();
132 // Try to inline the function. Get the list of static allocas that were
134 if (!InlineFunction(CS, IFI, InsertLifetime))
137 AdjustCallerSSPLevel(Caller, Callee);
139 // Look at all of the allocas that we inlined through this call site. If we
140 // have already inlined other allocas through other calls into this function,
141 // then we know that they have disjoint lifetimes and that we can merge them.
143 // There are many heuristics possible for merging these allocas, and the
144 // different options have different tradeoffs. One thing that we *really*
145 // don't want to hurt is SRoA: once inlining happens, often allocas are no
146 // longer address taken and so they can be promoted.
148 // Our "solution" for that is to only merge allocas whose outermost type is an
149 // array type. These are usually not promoted because someone is using a
150 // variable index into them. These are also often the most important ones to
153 // A better solution would be to have real memory lifetime markers in the IR
154 // and not have the inliner do any merging of allocas at all. This would
155 // allow the backend to do proper stack slot coloring of all allocas that
156 // *actually make it to the backend*, which is really what we want.
158 // Because we don't have this information, we do this simple and useful hack.
160 SmallPtrSet<AllocaInst*, 16> UsedAllocas;
162 // When processing our SCC, check to see if CS was inlined from some other
163 // call site. For example, if we're processing "A" in this code:
165 // B() { x = alloca ... C() }
166 // C() { y = alloca ... }
167 // Assume that C was not inlined into B initially, and so we're processing A
168 // and decide to inline B into A. Doing this makes an alloca available for
169 // reuse and makes a callsite (C) available for inlining. When we process
170 // the C call site we don't want to do any alloca merging between X and Y
171 // because their scopes are not disjoint. We could make this smarter by
172 // keeping track of the inline history for each alloca in the
173 // InlinedArrayAllocas but this isn't likely to be a significant win.
174 if (InlineHistory != -1) // Only do merging for top-level call sites in SCC.
177 // Loop over all the allocas we have so far and see if they can be merged with
178 // a previously inlined alloca. If not, remember that we had it.
179 for (unsigned AllocaNo = 0, e = IFI.StaticAllocas.size();
180 AllocaNo != e; ++AllocaNo) {
181 AllocaInst *AI = IFI.StaticAllocas[AllocaNo];
183 // Don't bother trying to merge array allocations (they will usually be
184 // canonicalized to be an allocation *of* an array), or allocations whose
185 // type is not itself an array (because we're afraid of pessimizing SRoA).
186 ArrayType *ATy = dyn_cast<ArrayType>(AI->getAllocatedType());
187 if (ATy == 0 || AI->isArrayAllocation())
190 // Get the list of all available allocas for this array type.
191 std::vector<AllocaInst*> &AllocasForType = InlinedArrayAllocas[ATy];
193 // Loop over the allocas in AllocasForType to see if we can reuse one. Note
194 // that we have to be careful not to reuse the same "available" alloca for
195 // multiple different allocas that we just inlined, we use the 'UsedAllocas'
196 // set to keep track of which "available" allocas are being used by this
197 // function. Also, AllocasForType can be empty of course!
198 bool MergedAwayAlloca = false;
199 for (unsigned i = 0, e = AllocasForType.size(); i != e; ++i) {
200 AllocaInst *AvailableAlloca = AllocasForType[i];
202 unsigned Align1 = AI->getAlignment(),
203 Align2 = AvailableAlloca->getAlignment();
204 // If we don't have data layout information, and only one alloca is using
205 // the target default, then we can't safely merge them because we can't
206 // pick the greater alignment.
207 if (!DL && (!Align1 || !Align2) && Align1 != Align2)
210 // The available alloca has to be in the right function, not in some other
211 // function in this SCC.
212 if (AvailableAlloca->getParent() != AI->getParent())
215 // If the inlined function already uses this alloca then we can't reuse
217 if (!UsedAllocas.insert(AvailableAlloca))
220 // Otherwise, we *can* reuse it, RAUW AI into AvailableAlloca and declare
222 DEBUG(dbgs() << " ***MERGED ALLOCA: " << *AI << "\n\t\tINTO: "
223 << *AvailableAlloca << '\n');
225 AI->replaceAllUsesWith(AvailableAlloca);
227 if (Align1 != Align2) {
228 if (!Align1 || !Align2) {
229 assert(DL && "DataLayout required to compare default alignments");
230 unsigned TypeAlign = DL->getABITypeAlignment(AI->getAllocatedType());
232 Align1 = Align1 ? Align1 : TypeAlign;
233 Align2 = Align2 ? Align2 : TypeAlign;
237 AvailableAlloca->setAlignment(AI->getAlignment());
240 AI->eraseFromParent();
241 MergedAwayAlloca = true;
243 IFI.StaticAllocas[AllocaNo] = 0;
247 // If we already nuked the alloca, we're done with it.
248 if (MergedAwayAlloca)
251 // If we were unable to merge away the alloca either because there are no
252 // allocas of the right type available or because we reused them all
253 // already, remember that this alloca came from an inlined function and mark
254 // it used so we don't reuse it for other allocas from this inline
256 AllocasForType.push_back(AI);
257 UsedAllocas.insert(AI);
263 unsigned Inliner::getInlineThreshold(CallSite CS) const {
264 int thres = InlineThreshold; // -inline-threshold or else selected by
267 // If -inline-threshold is not given, listen to the optsize attribute when it
268 // would decrease the threshold.
269 Function *Caller = CS.getCaller();
270 bool OptSize = Caller && !Caller->isDeclaration() &&
271 Caller->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
272 Attribute::OptimizeForSize);
273 if (!(InlineLimit.getNumOccurrences() > 0) && OptSize &&
274 OptSizeThreshold < thres)
275 thres = OptSizeThreshold;
277 // Listen to the inlinehint attribute when it would increase the threshold
278 // and the caller does not need to minimize its size.
279 Function *Callee = CS.getCalledFunction();
280 bool InlineHint = Callee && !Callee->isDeclaration() &&
281 Callee->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
282 Attribute::InlineHint);
283 if (InlineHint && HintThreshold > thres
284 && !Caller->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
286 thres = HintThreshold;
288 // Listen to the cold attribute when it would decrease the threshold.
289 bool ColdCallee = Callee && !Callee->isDeclaration() &&
290 Callee->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
292 if (ColdCallee && ColdThreshold < thres)
293 thres = ColdThreshold;
298 /// shouldInline - Return true if the inliner should attempt to inline
299 /// at the given CallSite.
300 bool Inliner::shouldInline(CallSite CS) {
301 InlineCost IC = getInlineCost(CS);
304 DEBUG(dbgs() << " Inlining: cost=always"
305 << ", Call: " << *CS.getInstruction() << "\n");
310 DEBUG(dbgs() << " NOT Inlining: cost=never"
311 << ", Call: " << *CS.getInstruction() << "\n");
315 Function *Caller = CS.getCaller();
317 DEBUG(dbgs() << " NOT Inlining: cost=" << IC.getCost()
318 << ", thres=" << (IC.getCostDelta() + IC.getCost())
319 << ", Call: " << *CS.getInstruction() << "\n");
323 // Try to detect the case where the current inlining candidate caller (call
324 // it B) is a static or linkonce-ODR function and is an inlining candidate
325 // elsewhere, and the current candidate callee (call it C) is large enough
326 // that inlining it into B would make B too big to inline later. In these
327 // circumstances it may be best not to inline C into B, but to inline B into
330 // This only applies to static and linkonce-ODR functions because those are
331 // expected to be available for inlining in the translation units where they
332 // are used. Thus we will always have the opportunity to make local inlining
333 // decisions. Importantly the linkonce-ODR linkage covers inline functions
334 // and templates in C++.
336 // FIXME: All of this logic should be sunk into getInlineCost. It relies on
337 // the internal implementation of the inline cost metrics rather than
338 // treating them as truly abstract units etc.
339 if (Caller->hasLocalLinkage() ||
340 Caller->getLinkage() == GlobalValue::LinkOnceODRLinkage) {
341 int TotalSecondaryCost = 0;
342 // The candidate cost to be imposed upon the current function.
343 int CandidateCost = IC.getCost() - (InlineConstants::CallPenalty + 1);
344 // This bool tracks what happens if we do NOT inline C into B.
345 bool callerWillBeRemoved = Caller->hasLocalLinkage();
346 // This bool tracks what happens if we DO inline C into B.
347 bool inliningPreventsSomeOuterInline = false;
348 for (User *U : Caller->users()) {
351 // If this isn't a call to Caller (it could be some other sort
352 // of reference) skip it. Such references will prevent the caller
353 // from being removed.
354 if (!CS2 || CS2.getCalledFunction() != Caller) {
355 callerWillBeRemoved = false;
359 InlineCost IC2 = getInlineCost(CS2);
360 ++NumCallerCallersAnalyzed;
362 callerWillBeRemoved = false;
368 // See if inlining or original callsite would erase the cost delta of
369 // this callsite. We subtract off the penalty for the call instruction,
370 // which we would be deleting.
371 if (IC2.getCostDelta() <= CandidateCost) {
372 inliningPreventsSomeOuterInline = true;
373 TotalSecondaryCost += IC2.getCost();
376 // If all outer calls to Caller would get inlined, the cost for the last
377 // one is set very low by getInlineCost, in anticipation that Caller will
378 // be removed entirely. We did not account for this above unless there
379 // is only one caller of Caller.
380 if (callerWillBeRemoved && !Caller->use_empty())
381 TotalSecondaryCost += InlineConstants::LastCallToStaticBonus;
383 if (inliningPreventsSomeOuterInline && TotalSecondaryCost < IC.getCost()) {
384 DEBUG(dbgs() << " NOT Inlining: " << *CS.getInstruction() <<
385 " Cost = " << IC.getCost() <<
386 ", outer Cost = " << TotalSecondaryCost << '\n');
391 DEBUG(dbgs() << " Inlining: cost=" << IC.getCost()
392 << ", thres=" << (IC.getCostDelta() + IC.getCost())
393 << ", Call: " << *CS.getInstruction() << '\n');
397 /// InlineHistoryIncludes - Return true if the specified inline history ID
398 /// indicates an inline history that includes the specified function.
399 static bool InlineHistoryIncludes(Function *F, int InlineHistoryID,
400 const SmallVectorImpl<std::pair<Function*, int> > &InlineHistory) {
401 while (InlineHistoryID != -1) {
402 assert(unsigned(InlineHistoryID) < InlineHistory.size() &&
403 "Invalid inline history ID");
404 if (InlineHistory[InlineHistoryID].first == F)
406 InlineHistoryID = InlineHistory[InlineHistoryID].second;
411 bool Inliner::runOnSCC(CallGraphSCC &SCC) {
412 CallGraph &CG = getAnalysis<CallGraphWrapperPass>().getCallGraph();
413 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
414 const DataLayout *DL = DLP ? &DLP->getDataLayout() : 0;
415 const TargetLibraryInfo *TLI = getAnalysisIfAvailable<TargetLibraryInfo>();
417 SmallPtrSet<Function*, 8> SCCFunctions;
418 DEBUG(dbgs() << "Inliner visiting SCC:");
419 for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
420 Function *F = (*I)->getFunction();
421 if (F) SCCFunctions.insert(F);
422 DEBUG(dbgs() << " " << (F ? F->getName() : "INDIRECTNODE"));
425 // Scan through and identify all call sites ahead of time so that we only
426 // inline call sites in the original functions, not call sites that result
427 // from inlining other functions.
428 SmallVector<std::pair<CallSite, int>, 16> CallSites;
430 // When inlining a callee produces new call sites, we want to keep track of
431 // the fact that they were inlined from the callee. This allows us to avoid
432 // infinite inlining in some obscure cases. To represent this, we use an
433 // index into the InlineHistory vector.
434 SmallVector<std::pair<Function*, int>, 8> InlineHistory;
436 for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
437 Function *F = (*I)->getFunction();
440 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
441 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
442 CallSite CS(cast<Value>(I));
443 // If this isn't a call, or it is a call to an intrinsic, it can
445 if (!CS || isa<IntrinsicInst>(I))
448 // If this is a direct call to an external function, we can never inline
449 // it. If it is an indirect call, inlining may resolve it to be a
450 // direct call, so we keep it.
451 if (CS.getCalledFunction() && CS.getCalledFunction()->isDeclaration())
454 CallSites.push_back(std::make_pair(CS, -1));
458 DEBUG(dbgs() << ": " << CallSites.size() << " call sites.\n");
460 // If there are no calls in this function, exit early.
461 if (CallSites.empty())
464 // Now that we have all of the call sites, move the ones to functions in the
465 // current SCC to the end of the list.
466 unsigned FirstCallInSCC = CallSites.size();
467 for (unsigned i = 0; i < FirstCallInSCC; ++i)
468 if (Function *F = CallSites[i].first.getCalledFunction())
469 if (SCCFunctions.count(F))
470 std::swap(CallSites[i--], CallSites[--FirstCallInSCC]);
473 InlinedArrayAllocasTy InlinedArrayAllocas;
474 InlineFunctionInfo InlineInfo(&CG, DL);
476 // Now that we have all of the call sites, loop over them and inline them if
477 // it looks profitable to do so.
478 bool Changed = false;
482 // Iterate over the outer loop because inlining functions can cause indirect
483 // calls to become direct calls.
484 for (unsigned CSi = 0; CSi != CallSites.size(); ++CSi) {
485 CallSite CS = CallSites[CSi].first;
487 Function *Caller = CS.getCaller();
488 Function *Callee = CS.getCalledFunction();
490 // If this call site is dead and it is to a readonly function, we should
491 // just delete the call instead of trying to inline it, regardless of
492 // size. This happens because IPSCCP propagates the result out of the
493 // call and then we're left with the dead call.
494 if (isInstructionTriviallyDead(CS.getInstruction(), TLI)) {
495 DEBUG(dbgs() << " -> Deleting dead call: "
496 << *CS.getInstruction() << "\n");
497 // Update the call graph by deleting the edge from Callee to Caller.
498 CG[Caller]->removeCallEdgeFor(CS);
499 CS.getInstruction()->eraseFromParent();
502 // We can only inline direct calls to non-declarations.
503 if (Callee == 0 || Callee->isDeclaration()) continue;
505 // If this call site was obtained by inlining another function, verify
506 // that the include path for the function did not include the callee
507 // itself. If so, we'd be recursively inlining the same function,
508 // which would provide the same callsites, which would cause us to
509 // infinitely inline.
510 int InlineHistoryID = CallSites[CSi].second;
511 if (InlineHistoryID != -1 &&
512 InlineHistoryIncludes(Callee, InlineHistoryID, InlineHistory))
516 // If the policy determines that we should inline this function,
518 if (!shouldInline(CS))
521 // Attempt to inline the function.
522 if (!InlineCallIfPossible(CS, InlineInfo, InlinedArrayAllocas,
523 InlineHistoryID, InsertLifetime, DL))
527 // Report the inline decision.
528 Caller->getContext().emitOptimizationRemark(
529 DEBUG_TYPE, *Caller, CS.getInstruction()->getDebugLoc(),
530 Twine(Callee->getName() + " inlined into " + Caller->getName()));
532 // If inlining this function gave us any new call sites, throw them
533 // onto our worklist to process. They are useful inline candidates.
534 if (!InlineInfo.InlinedCalls.empty()) {
535 // Create a new inline history entry for this, so that we remember
536 // that these new callsites came about due to inlining Callee.
537 int NewHistoryID = InlineHistory.size();
538 InlineHistory.push_back(std::make_pair(Callee, InlineHistoryID));
540 for (unsigned i = 0, e = InlineInfo.InlinedCalls.size();
542 Value *Ptr = InlineInfo.InlinedCalls[i];
543 CallSites.push_back(std::make_pair(CallSite(Ptr), NewHistoryID));
548 // If we inlined or deleted the last possible call site to the function,
549 // delete the function body now.
550 if (Callee && Callee->use_empty() && Callee->hasLocalLinkage() &&
551 // TODO: Can remove if in SCC now.
552 !SCCFunctions.count(Callee) &&
554 // The function may be apparently dead, but if there are indirect
555 // callgraph references to the node, we cannot delete it yet, this
556 // could invalidate the CGSCC iterator.
557 CG[Callee]->getNumReferences() == 0) {
558 DEBUG(dbgs() << " -> Deleting dead function: "
559 << Callee->getName() << "\n");
560 CallGraphNode *CalleeNode = CG[Callee];
562 // Remove any call graph edges from the callee to its callees.
563 CalleeNode->removeAllCalledFunctions();
565 // Removing the node for callee from the call graph and delete it.
566 delete CG.removeFunctionFromModule(CalleeNode);
570 // Remove this call site from the list. If possible, use
571 // swap/pop_back for efficiency, but do not use it if doing so would
572 // move a call site to a function in this SCC before the
573 // 'FirstCallInSCC' barrier.
574 if (SCC.isSingular()) {
575 CallSites[CSi] = CallSites.back();
576 CallSites.pop_back();
578 CallSites.erase(CallSites.begin()+CSi);
585 } while (LocalChange);
590 // doFinalization - Remove now-dead linkonce functions at the end of
591 // processing to avoid breaking the SCC traversal.
592 bool Inliner::doFinalization(CallGraph &CG) {
593 return removeDeadFunctions(CG);
596 /// removeDeadFunctions - Remove dead functions that are not included in
597 /// DNR (Do Not Remove) list.
598 bool Inliner::removeDeadFunctions(CallGraph &CG, bool AlwaysInlineOnly) {
599 SmallVector<CallGraphNode*, 16> FunctionsToRemove;
601 // Scan for all of the functions, looking for ones that should now be removed
602 // from the program. Insert the dead ones in the FunctionsToRemove set.
603 for (CallGraph::iterator I = CG.begin(), E = CG.end(); I != E; ++I) {
604 CallGraphNode *CGN = I->second;
605 Function *F = CGN->getFunction();
606 if (!F || F->isDeclaration())
609 // Handle the case when this function is called and we only want to care
610 // about always-inline functions. This is a bit of a hack to share code
611 // between here and the InlineAlways pass.
612 if (AlwaysInlineOnly &&
613 !F->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
614 Attribute::AlwaysInline))
617 // If the only remaining users of the function are dead constants, remove
619 F->removeDeadConstantUsers();
621 if (!F->isDefTriviallyDead())
624 // Remove any call graph edges from the function to its callees.
625 CGN->removeAllCalledFunctions();
627 // Remove any edges from the external node to the function's call graph
628 // node. These edges might have been made irrelegant due to
629 // optimization of the program.
630 CG.getExternalCallingNode()->removeAnyCallEdgeTo(CGN);
632 // Removing the node for callee from the call graph and delete it.
633 FunctionsToRemove.push_back(CGN);
635 if (FunctionsToRemove.empty())
638 // Now that we know which functions to delete, do so. We didn't want to do
639 // this inline, because that would invalidate our CallGraph::iterator
642 // Note that it doesn't matter that we are iterating over a non-stable order
643 // here to do this, it doesn't matter which order the functions are deleted
645 array_pod_sort(FunctionsToRemove.begin(), FunctionsToRemove.end());
646 FunctionsToRemove.erase(std::unique(FunctionsToRemove.begin(),
647 FunctionsToRemove.end()),
648 FunctionsToRemove.end());
649 for (SmallVectorImpl<CallGraphNode *>::iterator I = FunctionsToRemove.begin(),
650 E = FunctionsToRemove.end();
652 delete CG.removeFunctionFromModule(*I);