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