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/DataLayout.h"
23 #include "llvm/IR/Instructions.h"
24 #include "llvm/IR/IntrinsicInst.h"
25 #include "llvm/IR/Module.h"
26 #include "llvm/Support/CallSite.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 STATISTIC(NumInlined, "Number of functions inlined");
36 STATISTIC(NumCallsDeleted, "Number of call sites deleted, not inlined");
37 STATISTIC(NumDeleted, "Number of functions deleted because all callers found");
38 STATISTIC(NumMergedAllocas, "Number of allocas merged together");
40 // This weirdly named statistic tracks the number of times that, when attempting
41 // to inline a function A into B, we analyze the callers of B in order to see
42 // if those would be more profitable and blocked inline steps.
43 STATISTIC(NumCallerCallersAnalyzed, "Number of caller-callers analyzed");
46 InlineLimit("inline-threshold", cl::Hidden, cl::init(225), cl::ZeroOrMore,
47 cl::desc("Control the amount of inlining to perform (default = 225)"));
50 HintThreshold("inlinehint-threshold", cl::Hidden, cl::init(325),
51 cl::desc("Threshold for inlining functions with inline hint"));
54 ColdThreshold("inlinecold-threshold", cl::Hidden, cl::init(75),
55 cl::desc("Threshold for inlining functions with cold attribute"));
57 // Threshold to use when optsize is specified (and there is no -inline-limit).
58 const int OptSizeThreshold = 75;
60 Inliner::Inliner(char &ID)
61 : CallGraphSCCPass(ID), InlineThreshold(InlineLimit), InsertLifetime(true) {}
63 Inliner::Inliner(char &ID, int Threshold, bool InsertLifetime)
64 : CallGraphSCCPass(ID), InlineThreshold(InlineLimit.getNumOccurrences() > 0 ?
65 InlineLimit : Threshold),
66 InsertLifetime(InsertLifetime) {}
68 /// getAnalysisUsage - For this class, we declare that we require and preserve
69 /// the call graph. If the derived class implements this method, it should
70 /// always explicitly call the implementation here.
71 void Inliner::getAnalysisUsage(AnalysisUsage &AU) const {
72 CallGraphSCCPass::getAnalysisUsage(AU);
76 typedef DenseMap<ArrayType*, std::vector<AllocaInst*> >
77 InlinedArrayAllocasTy;
79 /// \brief If the inlined function had a higher stack protection level than the
80 /// calling function, then bump up the caller's stack protection level.
81 static void AdjustCallerSSPLevel(Function *Caller, Function *Callee) {
82 // If upgrading the SSP attribute, clear out the old SSP Attributes first.
83 // Having multiple SSP attributes doesn't actually hurt, but it adds useless
86 B.addAttribute(Attribute::StackProtect)
87 .addAttribute(Attribute::StackProtectStrong);
88 AttributeSet OldSSPAttr = AttributeSet::get(Caller->getContext(),
89 AttributeSet::FunctionIndex,
91 AttributeSet CallerAttr = Caller->getAttributes(),
92 CalleeAttr = Callee->getAttributes();
94 if (CalleeAttr.hasAttribute(AttributeSet::FunctionIndex,
95 Attribute::StackProtectReq)) {
96 Caller->removeAttributes(AttributeSet::FunctionIndex, OldSSPAttr);
97 Caller->addFnAttr(Attribute::StackProtectReq);
98 } else if (CalleeAttr.hasAttribute(AttributeSet::FunctionIndex,
99 Attribute::StackProtectStrong) &&
100 !CallerAttr.hasAttribute(AttributeSet::FunctionIndex,
101 Attribute::StackProtectReq)) {
102 Caller->removeAttributes(AttributeSet::FunctionIndex, OldSSPAttr);
103 Caller->addFnAttr(Attribute::StackProtectStrong);
104 } else if (CalleeAttr.hasAttribute(AttributeSet::FunctionIndex,
105 Attribute::StackProtect) &&
106 !CallerAttr.hasAttribute(AttributeSet::FunctionIndex,
107 Attribute::StackProtectReq) &&
108 !CallerAttr.hasAttribute(AttributeSet::FunctionIndex,
109 Attribute::StackProtectStrong))
110 Caller->addFnAttr(Attribute::StackProtect);
113 /// InlineCallIfPossible - If it is possible to inline the specified call site,
114 /// do so and update the CallGraph for this operation.
116 /// This function also does some basic book-keeping to update the IR. The
117 /// InlinedArrayAllocas map keeps track of any allocas that are already
118 /// available from other functions inlined into the caller. If we are able to
119 /// inline this call site we attempt to reuse already available allocas or add
120 /// any new allocas to the set if not possible.
121 static bool InlineCallIfPossible(CallSite CS, InlineFunctionInfo &IFI,
122 InlinedArrayAllocasTy &InlinedArrayAllocas,
123 int InlineHistory, bool InsertLifetime,
124 const DataLayout *TD) {
125 Function *Callee = CS.getCalledFunction();
126 Function *Caller = CS.getCaller();
128 // Try to inline the function. Get the list of static allocas that were
130 if (!InlineFunction(CS, IFI, InsertLifetime))
133 AdjustCallerSSPLevel(Caller, Callee);
135 // Look at all of the allocas that we inlined through this call site. If we
136 // have already inlined other allocas through other calls into this function,
137 // then we know that they have disjoint lifetimes and that we can merge them.
139 // There are many heuristics possible for merging these allocas, and the
140 // different options have different tradeoffs. One thing that we *really*
141 // don't want to hurt is SRoA: once inlining happens, often allocas are no
142 // longer address taken and so they can be promoted.
144 // Our "solution" for that is to only merge allocas whose outermost type is an
145 // array type. These are usually not promoted because someone is using a
146 // variable index into them. These are also often the most important ones to
149 // A better solution would be to have real memory lifetime markers in the IR
150 // and not have the inliner do any merging of allocas at all. This would
151 // allow the backend to do proper stack slot coloring of all allocas that
152 // *actually make it to the backend*, which is really what we want.
154 // Because we don't have this information, we do this simple and useful hack.
156 SmallPtrSet<AllocaInst*, 16> UsedAllocas;
158 // When processing our SCC, check to see if CS was inlined from some other
159 // call site. For example, if we're processing "A" in this code:
161 // B() { x = alloca ... C() }
162 // C() { y = alloca ... }
163 // Assume that C was not inlined into B initially, and so we're processing A
164 // and decide to inline B into A. Doing this makes an alloca available for
165 // reuse and makes a callsite (C) available for inlining. When we process
166 // the C call site we don't want to do any alloca merging between X and Y
167 // because their scopes are not disjoint. We could make this smarter by
168 // keeping track of the inline history for each alloca in the
169 // InlinedArrayAllocas but this isn't likely to be a significant win.
170 if (InlineHistory != -1) // Only do merging for top-level call sites in SCC.
173 // Loop over all the allocas we have so far and see if they can be merged with
174 // a previously inlined alloca. If not, remember that we had it.
175 for (unsigned AllocaNo = 0, e = IFI.StaticAllocas.size();
176 AllocaNo != e; ++AllocaNo) {
177 AllocaInst *AI = IFI.StaticAllocas[AllocaNo];
179 // Don't bother trying to merge array allocations (they will usually be
180 // canonicalized to be an allocation *of* an array), or allocations whose
181 // type is not itself an array (because we're afraid of pessimizing SRoA).
182 ArrayType *ATy = dyn_cast<ArrayType>(AI->getAllocatedType());
183 if (ATy == 0 || AI->isArrayAllocation())
186 // Get the list of all available allocas for this array type.
187 std::vector<AllocaInst*> &AllocasForType = InlinedArrayAllocas[ATy];
189 // Loop over the allocas in AllocasForType to see if we can reuse one. Note
190 // that we have to be careful not to reuse the same "available" alloca for
191 // multiple different allocas that we just inlined, we use the 'UsedAllocas'
192 // set to keep track of which "available" allocas are being used by this
193 // function. Also, AllocasForType can be empty of course!
194 bool MergedAwayAlloca = false;
195 for (unsigned i = 0, e = AllocasForType.size(); i != e; ++i) {
196 AllocaInst *AvailableAlloca = AllocasForType[i];
198 unsigned Align1 = AI->getAlignment(),
199 Align2 = AvailableAlloca->getAlignment();
200 // If we don't have data layout information, and only one alloca is using
201 // the target default, then we can't safely merge them because we can't
202 // pick the greater alignment.
203 if (!TD && (!Align1 || !Align2) && Align1 != Align2)
206 // The available alloca has to be in the right function, not in some other
207 // function in this SCC.
208 if (AvailableAlloca->getParent() != AI->getParent())
211 // If the inlined function already uses this alloca then we can't reuse
213 if (!UsedAllocas.insert(AvailableAlloca))
216 // Otherwise, we *can* reuse it, RAUW AI into AvailableAlloca and declare
218 DEBUG(dbgs() << " ***MERGED ALLOCA: " << *AI << "\n\t\tINTO: "
219 << *AvailableAlloca << '\n');
221 AI->replaceAllUsesWith(AvailableAlloca);
223 if (Align1 != Align2) {
224 if (!Align1 || !Align2) {
225 assert(TD && "DataLayout required to compare default alignments");
226 unsigned TypeAlign = TD->getABITypeAlignment(AI->getAllocatedType());
228 Align1 = Align1 ? Align1 : TypeAlign;
229 Align2 = Align2 ? Align2 : TypeAlign;
233 AvailableAlloca->setAlignment(AI->getAlignment());
236 AI->eraseFromParent();
237 MergedAwayAlloca = true;
239 IFI.StaticAllocas[AllocaNo] = 0;
243 // If we already nuked the alloca, we're done with it.
244 if (MergedAwayAlloca)
247 // If we were unable to merge away the alloca either because there are no
248 // allocas of the right type available or because we reused them all
249 // already, remember that this alloca came from an inlined function and mark
250 // it used so we don't reuse it for other allocas from this inline
252 AllocasForType.push_back(AI);
253 UsedAllocas.insert(AI);
259 unsigned Inliner::getInlineThreshold(CallSite CS) const {
260 int thres = InlineThreshold; // -inline-threshold or else selected by
263 // If -inline-threshold is not given, listen to the optsize attribute when it
264 // would decrease the threshold.
265 Function *Caller = CS.getCaller();
266 bool OptSize = Caller && !Caller->isDeclaration() &&
267 Caller->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
268 Attribute::OptimizeForSize);
269 if (!(InlineLimit.getNumOccurrences() > 0) && OptSize &&
270 OptSizeThreshold < thres)
271 thres = OptSizeThreshold;
273 // Listen to the inlinehint attribute when it would increase the threshold
274 // and the caller does not need to minimize its size.
275 Function *Callee = CS.getCalledFunction();
276 bool InlineHint = Callee && !Callee->isDeclaration() &&
277 Callee->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
278 Attribute::InlineHint);
279 if (InlineHint && HintThreshold > thres
280 && !Caller->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
282 thres = HintThreshold;
284 // Listen to the cold attribute when it would decrease the threshold.
285 bool ColdCallee = Callee && !Callee->isDeclaration() &&
286 Callee->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
288 if (ColdCallee && ColdThreshold < thres)
289 thres = ColdThreshold;
294 /// shouldInline - Return true if the inliner should attempt to inline
295 /// at the given CallSite.
296 bool Inliner::shouldInline(CallSite CS) {
297 InlineCost IC = getInlineCost(CS);
300 DEBUG(dbgs() << " Inlining: cost=always"
301 << ", Call: " << *CS.getInstruction() << "\n");
306 DEBUG(dbgs() << " NOT Inlining: cost=never"
307 << ", Call: " << *CS.getInstruction() << "\n");
311 Function *Caller = CS.getCaller();
313 DEBUG(dbgs() << " NOT Inlining: cost=" << IC.getCost()
314 << ", thres=" << (IC.getCostDelta() + IC.getCost())
315 << ", Call: " << *CS.getInstruction() << "\n");
319 // Try to detect the case where the current inlining candidate caller (call
320 // it B) is a static or linkonce-ODR function and is an inlining candidate
321 // elsewhere, and the current candidate callee (call it C) is large enough
322 // that inlining it into B would make B too big to inline later. In these
323 // circumstances it may be best not to inline C into B, but to inline B into
326 // This only applies to static and linkonce-ODR functions because those are
327 // expected to be available for inlining in the translation units where they
328 // are used. Thus we will always have the opportunity to make local inlining
329 // decisions. Importantly the linkonce-ODR linkage covers inline functions
330 // and templates in C++.
332 // FIXME: All of this logic should be sunk into getInlineCost. It relies on
333 // the internal implementation of the inline cost metrics rather than
334 // treating them as truly abstract units etc.
335 if (Caller->hasLocalLinkage() ||
336 Caller->getLinkage() == GlobalValue::LinkOnceODRLinkage) {
337 int TotalSecondaryCost = 0;
338 // The candidate cost to be imposed upon the current function.
339 int CandidateCost = IC.getCost() - (InlineConstants::CallPenalty + 1);
340 // This bool tracks what happens if we do NOT inline C into B.
341 bool callerWillBeRemoved = Caller->hasLocalLinkage();
342 // This bool tracks what happens if we DO inline C into B.
343 bool inliningPreventsSomeOuterInline = false;
344 for (Value::use_iterator I = Caller->use_begin(), E =Caller->use_end();
348 // If this isn't a call to Caller (it could be some other sort
349 // of reference) skip it. Such references will prevent the caller
350 // from being removed.
351 if (!CS2 || CS2.getCalledFunction() != Caller) {
352 callerWillBeRemoved = false;
356 InlineCost IC2 = getInlineCost(CS2);
357 ++NumCallerCallersAnalyzed;
359 callerWillBeRemoved = false;
365 // See if inlining or original callsite would erase the cost delta of
366 // this callsite. We subtract off the penalty for the call instruction,
367 // which we would be deleting.
368 if (IC2.getCostDelta() <= CandidateCost) {
369 inliningPreventsSomeOuterInline = true;
370 TotalSecondaryCost += IC2.getCost();
373 // If all outer calls to Caller would get inlined, the cost for the last
374 // one is set very low by getInlineCost, in anticipation that Caller will
375 // be removed entirely. We did not account for this above unless there
376 // is only one caller of Caller.
377 if (callerWillBeRemoved && Caller->use_begin() != Caller->use_end())
378 TotalSecondaryCost += InlineConstants::LastCallToStaticBonus;
380 if (inliningPreventsSomeOuterInline && TotalSecondaryCost < IC.getCost()) {
381 DEBUG(dbgs() << " NOT Inlining: " << *CS.getInstruction() <<
382 " Cost = " << IC.getCost() <<
383 ", outer Cost = " << TotalSecondaryCost << '\n');
388 DEBUG(dbgs() << " Inlining: cost=" << IC.getCost()
389 << ", thres=" << (IC.getCostDelta() + IC.getCost())
390 << ", Call: " << *CS.getInstruction() << '\n');
394 /// InlineHistoryIncludes - Return true if the specified inline history ID
395 /// indicates an inline history that includes the specified function.
396 static bool InlineHistoryIncludes(Function *F, int InlineHistoryID,
397 const SmallVectorImpl<std::pair<Function*, int> > &InlineHistory) {
398 while (InlineHistoryID != -1) {
399 assert(unsigned(InlineHistoryID) < InlineHistory.size() &&
400 "Invalid inline history ID");
401 if (InlineHistory[InlineHistoryID].first == F)
403 InlineHistoryID = InlineHistory[InlineHistoryID].second;
408 bool Inliner::runOnSCC(CallGraphSCC &SCC) {
409 CallGraph &CG = getAnalysis<CallGraphWrapperPass>().getCallGraph();
410 const DataLayout *TD = getAnalysisIfAvailable<DataLayout>();
411 const TargetLibraryInfo *TLI = getAnalysisIfAvailable<TargetLibraryInfo>();
413 SmallPtrSet<Function*, 8> SCCFunctions;
414 DEBUG(dbgs() << "Inliner visiting SCC:");
415 for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
416 Function *F = (*I)->getFunction();
417 if (F) SCCFunctions.insert(F);
418 DEBUG(dbgs() << " " << (F ? F->getName() : "INDIRECTNODE"));
421 // Scan through and identify all call sites ahead of time so that we only
422 // inline call sites in the original functions, not call sites that result
423 // from inlining other functions.
424 SmallVector<std::pair<CallSite, int>, 16> CallSites;
426 // When inlining a callee produces new call sites, we want to keep track of
427 // the fact that they were inlined from the callee. This allows us to avoid
428 // infinite inlining in some obscure cases. To represent this, we use an
429 // index into the InlineHistory vector.
430 SmallVector<std::pair<Function*, int>, 8> InlineHistory;
432 for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
433 Function *F = (*I)->getFunction();
436 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
437 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
438 CallSite CS(cast<Value>(I));
439 // If this isn't a call, or it is a call to an intrinsic, it can
441 if (!CS || isa<IntrinsicInst>(I))
444 // If this is a direct call to an external function, we can never inline
445 // it. If it is an indirect call, inlining may resolve it to be a
446 // direct call, so we keep it.
447 if (CS.getCalledFunction() && CS.getCalledFunction()->isDeclaration())
450 CallSites.push_back(std::make_pair(CS, -1));
454 DEBUG(dbgs() << ": " << CallSites.size() << " call sites.\n");
456 // If there are no calls in this function, exit early.
457 if (CallSites.empty())
460 // Now that we have all of the call sites, move the ones to functions in the
461 // current SCC to the end of the list.
462 unsigned FirstCallInSCC = CallSites.size();
463 for (unsigned i = 0; i < FirstCallInSCC; ++i)
464 if (Function *F = CallSites[i].first.getCalledFunction())
465 if (SCCFunctions.count(F))
466 std::swap(CallSites[i--], CallSites[--FirstCallInSCC]);
469 InlinedArrayAllocasTy InlinedArrayAllocas;
470 InlineFunctionInfo InlineInfo(&CG, TD);
472 // Now that we have all of the call sites, loop over them and inline them if
473 // it looks profitable to do so.
474 bool Changed = false;
478 // Iterate over the outer loop because inlining functions can cause indirect
479 // calls to become direct calls.
480 for (unsigned CSi = 0; CSi != CallSites.size(); ++CSi) {
481 CallSite CS = CallSites[CSi].first;
483 Function *Caller = CS.getCaller();
484 Function *Callee = CS.getCalledFunction();
486 // If this call site is dead and it is to a readonly function, we should
487 // just delete the call instead of trying to inline it, regardless of
488 // size. This happens because IPSCCP propagates the result out of the
489 // call and then we're left with the dead call.
490 if (isInstructionTriviallyDead(CS.getInstruction(), TLI)) {
491 DEBUG(dbgs() << " -> Deleting dead call: "
492 << *CS.getInstruction() << "\n");
493 // Update the call graph by deleting the edge from Callee to Caller.
494 CG[Caller]->removeCallEdgeFor(CS);
495 CS.getInstruction()->eraseFromParent();
498 // We can only inline direct calls to non-declarations.
499 if (Callee == 0 || Callee->isDeclaration()) continue;
501 // If this call site was obtained by inlining another function, verify
502 // that the include path for the function did not include the callee
503 // itself. If so, we'd be recursively inlining the same function,
504 // which would provide the same callsites, which would cause us to
505 // infinitely inline.
506 int InlineHistoryID = CallSites[CSi].second;
507 if (InlineHistoryID != -1 &&
508 InlineHistoryIncludes(Callee, InlineHistoryID, InlineHistory))
512 // If the policy determines that we should inline this function,
514 if (!shouldInline(CS))
517 // Attempt to inline the function.
518 if (!InlineCallIfPossible(CS, InlineInfo, InlinedArrayAllocas,
519 InlineHistoryID, InsertLifetime, TD))
523 // If inlining this function gave us any new call sites, throw them
524 // onto our worklist to process. They are useful inline candidates.
525 if (!InlineInfo.InlinedCalls.empty()) {
526 // Create a new inline history entry for this, so that we remember
527 // that these new callsites came about due to inlining Callee.
528 int NewHistoryID = InlineHistory.size();
529 InlineHistory.push_back(std::make_pair(Callee, InlineHistoryID));
531 for (unsigned i = 0, e = InlineInfo.InlinedCalls.size();
533 Value *Ptr = InlineInfo.InlinedCalls[i];
534 CallSites.push_back(std::make_pair(CallSite(Ptr), NewHistoryID));
539 // If we inlined or deleted the last possible call site to the function,
540 // delete the function body now.
541 if (Callee && Callee->use_empty() && Callee->hasLocalLinkage() &&
542 // TODO: Can remove if in SCC now.
543 !SCCFunctions.count(Callee) &&
545 // The function may be apparently dead, but if there are indirect
546 // callgraph references to the node, we cannot delete it yet, this
547 // could invalidate the CGSCC iterator.
548 CG[Callee]->getNumReferences() == 0) {
549 DEBUG(dbgs() << " -> Deleting dead function: "
550 << Callee->getName() << "\n");
551 CallGraphNode *CalleeNode = CG[Callee];
553 // Remove any call graph edges from the callee to its callees.
554 CalleeNode->removeAllCalledFunctions();
556 // Removing the node for callee from the call graph and delete it.
557 delete CG.removeFunctionFromModule(CalleeNode);
561 // Remove this call site from the list. If possible, use
562 // swap/pop_back for efficiency, but do not use it if doing so would
563 // move a call site to a function in this SCC before the
564 // 'FirstCallInSCC' barrier.
565 if (SCC.isSingular()) {
566 CallSites[CSi] = CallSites.back();
567 CallSites.pop_back();
569 CallSites.erase(CallSites.begin()+CSi);
576 } while (LocalChange);
581 // doFinalization - Remove now-dead linkonce functions at the end of
582 // processing to avoid breaking the SCC traversal.
583 bool Inliner::doFinalization(CallGraph &CG) {
584 return removeDeadFunctions(CG);
587 /// removeDeadFunctions - Remove dead functions that are not included in
588 /// DNR (Do Not Remove) list.
589 bool Inliner::removeDeadFunctions(CallGraph &CG, bool AlwaysInlineOnly) {
590 SmallVector<CallGraphNode*, 16> FunctionsToRemove;
592 // Scan for all of the functions, looking for ones that should now be removed
593 // from the program. Insert the dead ones in the FunctionsToRemove set.
594 for (CallGraph::iterator I = CG.begin(), E = CG.end(); I != E; ++I) {
595 CallGraphNode *CGN = I->second;
596 Function *F = CGN->getFunction();
597 if (!F || F->isDeclaration())
600 // Handle the case when this function is called and we only want to care
601 // about always-inline functions. This is a bit of a hack to share code
602 // between here and the InlineAlways pass.
603 if (AlwaysInlineOnly &&
604 !F->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
605 Attribute::AlwaysInline))
608 // If the only remaining users of the function are dead constants, remove
610 F->removeDeadConstantUsers();
612 if (!F->isDefTriviallyDead())
615 // Remove any call graph edges from the function to its callees.
616 CGN->removeAllCalledFunctions();
618 // Remove any edges from the external node to the function's call graph
619 // node. These edges might have been made irrelegant due to
620 // optimization of the program.
621 CG.getExternalCallingNode()->removeAnyCallEdgeTo(CGN);
623 // Removing the node for callee from the call graph and delete it.
624 FunctionsToRemove.push_back(CGN);
626 if (FunctionsToRemove.empty())
629 // Now that we know which functions to delete, do so. We didn't want to do
630 // this inline, because that would invalidate our CallGraph::iterator
633 // Note that it doesn't matter that we are iterating over a non-stable order
634 // here to do this, it doesn't matter which order the functions are deleted
636 array_pod_sort(FunctionsToRemove.begin(), FunctionsToRemove.end());
637 FunctionsToRemove.erase(std::unique(FunctionsToRemove.begin(),
638 FunctionsToRemove.end()),
639 FunctionsToRemove.end());
640 for (SmallVectorImpl<CallGraphNode *>::iterator I = FunctionsToRemove.begin(),
641 E = FunctionsToRemove.end();
643 delete CG.removeFunctionFromModule(*I);