Inliner.cpp revision 36b56886974eae4f9c5ebc96befd3e7bfe5de338
158537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)//===- Inliner.cpp - Code common to all inliners --------------------------===// 258537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)// 358537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)// The LLVM Compiler Infrastructure 458537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)// 558537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)// This file is distributed under the University of Illinois Open Source 658537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)// License. See LICENSE.TXT for details. 758537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)// 858537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)//===----------------------------------------------------------------------===// 958537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)// 1058537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)// This file implements the mechanics required to implement inlining without 1158537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)// missing any calls and updating the call graph. The decisions of which calls 1258537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)// are profitable to inline are implemented elsewhere. 1358537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)// 1458537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)//===----------------------------------------------------------------------===// 1558537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) 1658537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)#define DEBUG_TYPE "inline" 1758537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)#include "llvm/Transforms/IPO/InlinerPass.h" 1858537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)#include "llvm/ADT/SmallPtrSet.h" 1958537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)#include "llvm/ADT/Statistic.h" 2058537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)#include "llvm/Analysis/CallGraph.h" 2158537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)#include "llvm/Analysis/InlineCost.h" 2258537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)#include "llvm/IR/CallSite.h" 2358537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)#include "llvm/IR/DataLayout.h" 24cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)#include "llvm/IR/Instructions.h" 25cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)#include "llvm/IR/IntrinsicInst.h" 26cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)#include "llvm/IR/Module.h" 27cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)#include "llvm/Support/CommandLine.h" 28cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)#include "llvm/Support/Debug.h" 29cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)#include "llvm/Support/raw_ostream.h" 30cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)#include "llvm/Target/TargetLibraryInfo.h" 31cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)#include "llvm/Transforms/Utils/Cloning.h" 32cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)#include "llvm/Transforms/Utils/Local.h" 33cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)using namespace llvm; 34cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) 35cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)STATISTIC(NumInlined, "Number of functions inlined"); 36cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)STATISTIC(NumCallsDeleted, "Number of call sites deleted, not inlined"); 37cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)STATISTIC(NumDeleted, "Number of functions deleted because all callers found"); 38cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)STATISTIC(NumMergedAllocas, "Number of allocas merged together"); 39cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) 40cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)// This weirdly named statistic tracks the number of times that, when attempting 4158537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)// to inline a function A into B, we analyze the callers of B in order to see 4258537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)// if those would be more profitable and blocked inline steps. 4358537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)STATISTIC(NumCallerCallersAnalyzed, "Number of caller-callers analyzed"); 4458537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) 4558537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)static cl::opt<int> 4658537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)InlineLimit("inline-threshold", cl::Hidden, cl::init(225), cl::ZeroOrMore, 4758537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) cl::desc("Control the amount of inlining to perform (default = 225)")); 4858537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) 4958537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)static cl::opt<int> 5058537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)HintThreshold("inlinehint-threshold", cl::Hidden, cl::init(325), 5158537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) cl::desc("Threshold for inlining functions with inline hint")); 5258537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) 5358537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)// We instroduce this threshold to help performance of instrumentation based 5458537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)// PGO before we actually hook up inliner with analysis passes such as BPI and 5558537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)// BFI. 5658537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)static cl::opt<int> 5758537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)ColdThreshold("inlinecold-threshold", cl::Hidden, cl::init(225), 5858537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) cl::desc("Threshold for inlining functions with cold attribute")); 5958537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) 6058537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)// Threshold to use when optsize is specified (and there is no -inline-limit). 6158537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)const int OptSizeThreshold = 75; 6258537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) 6358537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)Inliner::Inliner(char &ID) 6458537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) : CallGraphSCCPass(ID), InlineThreshold(InlineLimit), InsertLifetime(true) {} 6558537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) 6658537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)Inliner::Inliner(char &ID, int Threshold, bool InsertLifetime) 6758537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) : CallGraphSCCPass(ID), InlineThreshold(InlineLimit.getNumOccurrences() > 0 ? 6858537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) InlineLimit : Threshold), 6958537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) InsertLifetime(InsertLifetime) {} 70a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) 71a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles)/// getAnalysisUsage - For this class, we declare that we require and preserve 7258537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)/// the call graph. If the derived class implements this method, it should 7358537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)/// always explicitly call the implementation here. 7458537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)void Inliner::getAnalysisUsage(AnalysisUsage &AU) const { 7558537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) CallGraphSCCPass::getAnalysisUsage(AU); 7658537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)} 7758537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) 7858537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) 7958537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)typedef DenseMap<ArrayType*, std::vector<AllocaInst*> > 8058537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)InlinedArrayAllocasTy; 8158537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) 8258537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)/// \brief If the inlined function had a higher stack protection level than the 8358537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)/// calling function, then bump up the caller's stack protection level. 8458537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)static void AdjustCallerSSPLevel(Function *Caller, Function *Callee) { 8558537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) // If upgrading the SSP attribute, clear out the old SSP Attributes first. 8658537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) // Having multiple SSP attributes doesn't actually hurt, but it adds useless 8758537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) // clutter to the IR. 8858537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) AttrBuilder B; 8958537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) B.addAttribute(Attribute::StackProtect) 9058537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) .addAttribute(Attribute::StackProtectStrong); 9158537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) AttributeSet OldSSPAttr = AttributeSet::get(Caller->getContext(), 9258537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) AttributeSet::FunctionIndex, 9358537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) B); 9458537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) AttributeSet CallerAttr = Caller->getAttributes(), 9558537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) CalleeAttr = Callee->getAttributes(); 9658537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) 9758537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) if (CalleeAttr.hasAttribute(AttributeSet::FunctionIndex, 9858537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) Attribute::StackProtectReq)) { 9958537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) Caller->removeAttributes(AttributeSet::FunctionIndex, OldSSPAttr); 10058537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) Caller->addFnAttr(Attribute::StackProtectReq); 10158537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) } else if (CalleeAttr.hasAttribute(AttributeSet::FunctionIndex, 10258537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) Attribute::StackProtectStrong) && 10358537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) !CallerAttr.hasAttribute(AttributeSet::FunctionIndex, 10458537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) Attribute::StackProtectReq)) { 10558537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) Caller->removeAttributes(AttributeSet::FunctionIndex, OldSSPAttr); 10658537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) Caller->addFnAttr(Attribute::StackProtectStrong); 10758537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) } else if (CalleeAttr.hasAttribute(AttributeSet::FunctionIndex, 10858537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) Attribute::StackProtect) && 10958537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) !CallerAttr.hasAttribute(AttributeSet::FunctionIndex, 11058537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) Attribute::StackProtectReq) && 11158537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) !CallerAttr.hasAttribute(AttributeSet::FunctionIndex, 11258537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) Attribute::StackProtectStrong)) 11358537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) Caller->addFnAttr(Attribute::StackProtect); 11458537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)} 11558537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) 11658537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)/// InlineCallIfPossible - If it is possible to inline the specified call site, 11758537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)/// do so and update the CallGraph for this operation. 11858537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)/// 11958537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)/// This function also does some basic book-keeping to update the IR. The 12058537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles)/// InlinedArrayAllocas map keeps track of any allocas that are already 1214e180b6a0b4720a9b8e9e959a882386f690f08ffTorne (Richard Coles)/// available from other functions inlined into the caller. If we are able to 122a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles)/// inline this call site we attempt to reuse already available allocas or add 1234e180b6a0b4720a9b8e9e959a882386f690f08ffTorne (Richard Coles)/// any new allocas to the set if not possible. 1244e180b6a0b4720a9b8e9e959a882386f690f08ffTorne (Richard Coles)static bool InlineCallIfPossible(CallSite CS, InlineFunctionInfo &IFI, 1254e180b6a0b4720a9b8e9e959a882386f690f08ffTorne (Richard Coles) InlinedArrayAllocasTy &InlinedArrayAllocas, 1264e180b6a0b4720a9b8e9e959a882386f690f08ffTorne (Richard Coles) int InlineHistory, bool InsertLifetime, 1274e180b6a0b4720a9b8e9e959a882386f690f08ffTorne (Richard Coles) const DataLayout *DL) { 1284e180b6a0b4720a9b8e9e959a882386f690f08ffTorne (Richard Coles) Function *Callee = CS.getCalledFunction(); 1294e180b6a0b4720a9b8e9e959a882386f690f08ffTorne (Richard Coles) Function *Caller = CS.getCaller(); 1304e180b6a0b4720a9b8e9e959a882386f690f08ffTorne (Richard Coles) 1314e180b6a0b4720a9b8e9e959a882386f690f08ffTorne (Richard Coles) // Try to inline the function. Get the list of static allocas that were 1324e180b6a0b4720a9b8e9e959a882386f690f08ffTorne (Richard Coles) // inlined. 1334e180b6a0b4720a9b8e9e959a882386f690f08ffTorne (Richard Coles) if (!InlineFunction(CS, IFI, InsertLifetime)) 1344e180b6a0b4720a9b8e9e959a882386f690f08ffTorne (Richard Coles) return false; 1354e180b6a0b4720a9b8e9e959a882386f690f08ffTorne (Richard Coles) 1364e180b6a0b4720a9b8e9e959a882386f690f08ffTorne (Richard Coles) AdjustCallerSSPLevel(Caller, Callee); 1374e180b6a0b4720a9b8e9e959a882386f690f08ffTorne (Richard Coles) 1384e180b6a0b4720a9b8e9e959a882386f690f08ffTorne (Richard Coles) // Look at all of the allocas that we inlined through this call site. If we 1394e180b6a0b4720a9b8e9e959a882386f690f08ffTorne (Richard Coles) // have already inlined other allocas through other calls into this function, 1404e180b6a0b4720a9b8e9e959a882386f690f08ffTorne (Richard Coles) // then we know that they have disjoint lifetimes and that we can merge them. 1414e180b6a0b4720a9b8e9e959a882386f690f08ffTorne (Richard Coles) // 142a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // There are many heuristics possible for merging these allocas, and the 14358537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) // different options have different tradeoffs. One thing that we *really* 144a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // don't want to hurt is SRoA: once inlining happens, often allocas are no 145a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // longer address taken and so they can be promoted. 146a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // 147a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // Our "solution" for that is to only merge allocas whose outermost type is an 148a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // array type. These are usually not promoted because someone is using a 149a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // variable index into them. These are also often the most important ones to 150a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // merge. 151a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // 152a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // A better solution would be to have real memory lifetime markers in the IR 153a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // and not have the inliner do any merging of allocas at all. This would 154a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // allow the backend to do proper stack slot coloring of all allocas that 15558537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) // *actually make it to the backend*, which is really what we want. 156a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // 157a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // Because we don't have this information, we do this simple and useful hack. 158a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // 159a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) SmallPtrSet<AllocaInst*, 16> UsedAllocas; 160a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) 161a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // When processing our SCC, check to see if CS was inlined from some other 16258537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) // call site. For example, if we're processing "A" in this code: 163a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // A() { B() } 164a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // B() { x = alloca ... C() } 16558537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) // C() { y = alloca ... } 166a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // Assume that C was not inlined into B initially, and so we're processing A 167a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // and decide to inline B into A. Doing this makes an alloca available for 168a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // reuse and makes a callsite (C) available for inlining. When we process 169a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // the C call site we don't want to do any alloca merging between X and Y 17058537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) // because their scopes are not disjoint. We could make this smarter by 171a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // keeping track of the inline history for each alloca in the 172a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // InlinedArrayAllocas but this isn't likely to be a significant win. 173a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) if (InlineHistory != -1) // Only do merging for top-level call sites in SCC. 174a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) return true; 1754e180b6a0b4720a9b8e9e959a882386f690f08ffTorne (Richard Coles) 176a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // Loop over all the allocas we have so far and see if they can be merged with 177a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // a previously inlined alloca. If not, remember that we had it. 178a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) for (unsigned AllocaNo = 0, e = IFI.StaticAllocas.size(); 179a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) AllocaNo != e; ++AllocaNo) { 180a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) AllocaInst *AI = IFI.StaticAllocas[AllocaNo]; 181a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) 182a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // Don't bother trying to merge array allocations (they will usually be 18358537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) // canonicalized to be an allocation *of* an array), or allocations whose 184a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // type is not itself an array (because we're afraid of pessimizing SRoA). 185a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) ArrayType *ATy = dyn_cast<ArrayType>(AI->getAllocatedType()); 186a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) if (ATy == 0 || AI->isArrayAllocation()) 187a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) continue; 188a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) 189a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // Get the list of all available allocas for this array type. 190a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) std::vector<AllocaInst*> &AllocasForType = InlinedArrayAllocas[ATy]; 19158537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) 192a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // Loop over the allocas in AllocasForType to see if we can reuse one. Note 193a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // that we have to be careful not to reuse the same "available" alloca for 194a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // multiple different allocas that we just inlined, we use the 'UsedAllocas' 195a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // set to keep track of which "available" allocas are being used by this 196a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // function. Also, AllocasForType can be empty of course! 197a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) bool MergedAwayAlloca = false; 198a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) for (unsigned i = 0, e = AllocasForType.size(); i != e; ++i) { 19958537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) AllocaInst *AvailableAlloca = AllocasForType[i]; 200a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) 201a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) unsigned Align1 = AI->getAlignment(), 202a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) Align2 = AvailableAlloca->getAlignment(); 203a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // If we don't have data layout information, and only one alloca is using 204a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // the target default, then we can't safely merge them because we can't 205a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // pick the greater alignment. 206a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) if (!DL && (!Align1 || !Align2) && Align1 != Align2) 207a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) continue; 208a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) 209a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // The available alloca has to be in the right function, not in some other 210a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // function in this SCC. 211a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) if (AvailableAlloca->getParent() != AI->getParent()) 212a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) continue; 213a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) 214a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // If the inlined function already uses this alloca then we can't reuse 215a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // it. 216a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) if (!UsedAllocas.insert(AvailableAlloca)) 217a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) continue; 218a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) 219a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // Otherwise, we *can* reuse it, RAUW AI into AvailableAlloca and declare 220a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // success! 221a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) DEBUG(dbgs() << " ***MERGED ALLOCA: " << *AI << "\n\t\tINTO: " 222a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) << *AvailableAlloca << '\n'); 223a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) 224a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) AI->replaceAllUsesWith(AvailableAlloca); 225a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) 226a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) if (Align1 != Align2) { 227a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) if (!Align1 || !Align2) { 228a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) assert(DL && "DataLayout required to compare default alignments"); 229cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) unsigned TypeAlign = DL->getABITypeAlignment(AI->getAllocatedType()); 230cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) 231a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) Align1 = Align1 ? Align1 : TypeAlign; 232a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) Align2 = Align2 ? Align2 : TypeAlign; 233010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) } 234010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) 235a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) if (Align1 > Align2) 236a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) AvailableAlloca->setAlignment(AI->getAlignment()); 237a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) } 238a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) 239a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) AI->eraseFromParent(); 240a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) MergedAwayAlloca = true; 241a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) ++NumMergedAllocas; 242a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) IFI.StaticAllocas[AllocaNo] = 0; 243a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) break; 244a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) } 245a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) 246a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // If we already nuked the alloca, we're done with it. 247a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) if (MergedAwayAlloca) 248a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) continue; 249c5cede9ae108bb15f6b7a8aea21c7e1fefa2834cBen Murdoch 250c5cede9ae108bb15f6b7a8aea21c7e1fefa2834cBen Murdoch // If we were unable to merge away the alloca either because there are no 251a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // allocas of the right type available or because we reused them all 252a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // already, remember that this alloca came from an inlined function and mark 253a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles) // it used so we don't reuse it for other allocas from this inline 254a02191e04bc25c4935f804f2c080ae28663d096dBen Murdoch // operation. 255a02191e04bc25c4935f804f2c080ae28663d096dBen Murdoch AllocasForType.push_back(AI); 256116680a4aac90f2aa7413d9095a592090648e557Ben Murdoch UsedAllocas.insert(AI); 257116680a4aac90f2aa7413d9095a592090648e557Ben Murdoch } 258116680a4aac90f2aa7413d9095a592090648e557Ben Murdoch 259116680a4aac90f2aa7413d9095a592090648e557Ben Murdoch return true; 2605f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles)} 2615f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) 262a1401311d1ab56c4ed0a474bd38c108f75cb0cd9Torne (Richard Coles)unsigned Inliner::getInlineThreshold(CallSite CS) const { 26358537e28ecd584eab876aee8be7156509866d23aTorne (Richard Coles) int thres = InlineThreshold; // -inline-threshold or else selected by 264 // overall opt level 265 266 // If -inline-threshold is not given, listen to the optsize attribute when it 267 // would decrease the threshold. 268 Function *Caller = CS.getCaller(); 269 bool OptSize = Caller && !Caller->isDeclaration() && 270 Caller->getAttributes().hasAttribute(AttributeSet::FunctionIndex, 271 Attribute::OptimizeForSize); 272 if (!(InlineLimit.getNumOccurrences() > 0) && OptSize && 273 OptSizeThreshold < thres) 274 thres = OptSizeThreshold; 275 276 // Listen to the inlinehint attribute when it would increase the threshold 277 // and the caller does not need to minimize its size. 278 Function *Callee = CS.getCalledFunction(); 279 bool InlineHint = Callee && !Callee->isDeclaration() && 280 Callee->getAttributes().hasAttribute(AttributeSet::FunctionIndex, 281 Attribute::InlineHint); 282 if (InlineHint && HintThreshold > thres 283 && !Caller->getAttributes().hasAttribute(AttributeSet::FunctionIndex, 284 Attribute::MinSize)) 285 thres = HintThreshold; 286 287 // Listen to the cold attribute when it would decrease the threshold. 288 bool ColdCallee = Callee && !Callee->isDeclaration() && 289 Callee->getAttributes().hasAttribute(AttributeSet::FunctionIndex, 290 Attribute::Cold); 291 if (ColdCallee && ColdThreshold < thres) 292 thres = ColdThreshold; 293 294 return thres; 295} 296 297/// shouldInline - Return true if the inliner should attempt to inline 298/// at the given CallSite. 299bool Inliner::shouldInline(CallSite CS) { 300 InlineCost IC = getInlineCost(CS); 301 302 if (IC.isAlways()) { 303 DEBUG(dbgs() << " Inlining: cost=always" 304 << ", Call: " << *CS.getInstruction() << "\n"); 305 return true; 306 } 307 308 if (IC.isNever()) { 309 DEBUG(dbgs() << " NOT Inlining: cost=never" 310 << ", Call: " << *CS.getInstruction() << "\n"); 311 return false; 312 } 313 314 Function *Caller = CS.getCaller(); 315 if (!IC) { 316 DEBUG(dbgs() << " NOT Inlining: cost=" << IC.getCost() 317 << ", thres=" << (IC.getCostDelta() + IC.getCost()) 318 << ", Call: " << *CS.getInstruction() << "\n"); 319 return false; 320 } 321 322 // Try to detect the case where the current inlining candidate caller (call 323 // it B) is a static or linkonce-ODR function and is an inlining candidate 324 // elsewhere, and the current candidate callee (call it C) is large enough 325 // that inlining it into B would make B too big to inline later. In these 326 // circumstances it may be best not to inline C into B, but to inline B into 327 // its callers. 328 // 329 // This only applies to static and linkonce-ODR functions because those are 330 // expected to be available for inlining in the translation units where they 331 // are used. Thus we will always have the opportunity to make local inlining 332 // decisions. Importantly the linkonce-ODR linkage covers inline functions 333 // and templates in C++. 334 // 335 // FIXME: All of this logic should be sunk into getInlineCost. It relies on 336 // the internal implementation of the inline cost metrics rather than 337 // treating them as truly abstract units etc. 338 if (Caller->hasLocalLinkage() || 339 Caller->getLinkage() == GlobalValue::LinkOnceODRLinkage) { 340 int TotalSecondaryCost = 0; 341 // The candidate cost to be imposed upon the current function. 342 int CandidateCost = IC.getCost() - (InlineConstants::CallPenalty + 1); 343 // This bool tracks what happens if we do NOT inline C into B. 344 bool callerWillBeRemoved = Caller->hasLocalLinkage(); 345 // This bool tracks what happens if we DO inline C into B. 346 bool inliningPreventsSomeOuterInline = false; 347 for (User *U : Caller->users()) { 348 CallSite CS2(U); 349 350 // If this isn't a call to Caller (it could be some other sort 351 // of reference) skip it. Such references will prevent the caller 352 // from being removed. 353 if (!CS2 || CS2.getCalledFunction() != Caller) { 354 callerWillBeRemoved = false; 355 continue; 356 } 357 358 InlineCost IC2 = getInlineCost(CS2); 359 ++NumCallerCallersAnalyzed; 360 if (!IC2) { 361 callerWillBeRemoved = false; 362 continue; 363 } 364 if (IC2.isAlways()) 365 continue; 366 367 // See if inlining or original callsite would erase the cost delta of 368 // this callsite. We subtract off the penalty for the call instruction, 369 // which we would be deleting. 370 if (IC2.getCostDelta() <= CandidateCost) { 371 inliningPreventsSomeOuterInline = true; 372 TotalSecondaryCost += IC2.getCost(); 373 } 374 } 375 // If all outer calls to Caller would get inlined, the cost for the last 376 // one is set very low by getInlineCost, in anticipation that Caller will 377 // be removed entirely. We did not account for this above unless there 378 // is only one caller of Caller. 379 if (callerWillBeRemoved && !Caller->use_empty()) 380 TotalSecondaryCost += InlineConstants::LastCallToStaticBonus; 381 382 if (inliningPreventsSomeOuterInline && TotalSecondaryCost < IC.getCost()) { 383 DEBUG(dbgs() << " NOT Inlining: " << *CS.getInstruction() << 384 " Cost = " << IC.getCost() << 385 ", outer Cost = " << TotalSecondaryCost << '\n'); 386 return false; 387 } 388 } 389 390 DEBUG(dbgs() << " Inlining: cost=" << IC.getCost() 391 << ", thres=" << (IC.getCostDelta() + IC.getCost()) 392 << ", Call: " << *CS.getInstruction() << '\n'); 393 return true; 394} 395 396/// InlineHistoryIncludes - Return true if the specified inline history ID 397/// indicates an inline history that includes the specified function. 398static bool InlineHistoryIncludes(Function *F, int InlineHistoryID, 399 const SmallVectorImpl<std::pair<Function*, int> > &InlineHistory) { 400 while (InlineHistoryID != -1) { 401 assert(unsigned(InlineHistoryID) < InlineHistory.size() && 402 "Invalid inline history ID"); 403 if (InlineHistory[InlineHistoryID].first == F) 404 return true; 405 InlineHistoryID = InlineHistory[InlineHistoryID].second; 406 } 407 return false; 408} 409 410bool Inliner::runOnSCC(CallGraphSCC &SCC) { 411 CallGraph &CG = getAnalysis<CallGraphWrapperPass>().getCallGraph(); 412 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>(); 413 const DataLayout *DL = DLP ? &DLP->getDataLayout() : 0; 414 const TargetLibraryInfo *TLI = getAnalysisIfAvailable<TargetLibraryInfo>(); 415 416 SmallPtrSet<Function*, 8> SCCFunctions; 417 DEBUG(dbgs() << "Inliner visiting SCC:"); 418 for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) { 419 Function *F = (*I)->getFunction(); 420 if (F) SCCFunctions.insert(F); 421 DEBUG(dbgs() << " " << (F ? F->getName() : "INDIRECTNODE")); 422 } 423 424 // Scan through and identify all call sites ahead of time so that we only 425 // inline call sites in the original functions, not call sites that result 426 // from inlining other functions. 427 SmallVector<std::pair<CallSite, int>, 16> CallSites; 428 429 // When inlining a callee produces new call sites, we want to keep track of 430 // the fact that they were inlined from the callee. This allows us to avoid 431 // infinite inlining in some obscure cases. To represent this, we use an 432 // index into the InlineHistory vector. 433 SmallVector<std::pair<Function*, int>, 8> InlineHistory; 434 435 for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) { 436 Function *F = (*I)->getFunction(); 437 if (!F) continue; 438 439 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) 440 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) { 441 CallSite CS(cast<Value>(I)); 442 // If this isn't a call, or it is a call to an intrinsic, it can 443 // never be inlined. 444 if (!CS || isa<IntrinsicInst>(I)) 445 continue; 446 447 // If this is a direct call to an external function, we can never inline 448 // it. If it is an indirect call, inlining may resolve it to be a 449 // direct call, so we keep it. 450 if (CS.getCalledFunction() && CS.getCalledFunction()->isDeclaration()) 451 continue; 452 453 CallSites.push_back(std::make_pair(CS, -1)); 454 } 455 } 456 457 DEBUG(dbgs() << ": " << CallSites.size() << " call sites.\n"); 458 459 // If there are no calls in this function, exit early. 460 if (CallSites.empty()) 461 return false; 462 463 // Now that we have all of the call sites, move the ones to functions in the 464 // current SCC to the end of the list. 465 unsigned FirstCallInSCC = CallSites.size(); 466 for (unsigned i = 0; i < FirstCallInSCC; ++i) 467 if (Function *F = CallSites[i].first.getCalledFunction()) 468 if (SCCFunctions.count(F)) 469 std::swap(CallSites[i--], CallSites[--FirstCallInSCC]); 470 471 472 InlinedArrayAllocasTy InlinedArrayAllocas; 473 InlineFunctionInfo InlineInfo(&CG, DL); 474 475 // Now that we have all of the call sites, loop over them and inline them if 476 // it looks profitable to do so. 477 bool Changed = false; 478 bool LocalChange; 479 do { 480 LocalChange = false; 481 // Iterate over the outer loop because inlining functions can cause indirect 482 // calls to become direct calls. 483 for (unsigned CSi = 0; CSi != CallSites.size(); ++CSi) { 484 CallSite CS = CallSites[CSi].first; 485 486 Function *Caller = CS.getCaller(); 487 Function *Callee = CS.getCalledFunction(); 488 489 // If this call site is dead and it is to a readonly function, we should 490 // just delete the call instead of trying to inline it, regardless of 491 // size. This happens because IPSCCP propagates the result out of the 492 // call and then we're left with the dead call. 493 if (isInstructionTriviallyDead(CS.getInstruction(), TLI)) { 494 DEBUG(dbgs() << " -> Deleting dead call: " 495 << *CS.getInstruction() << "\n"); 496 // Update the call graph by deleting the edge from Callee to Caller. 497 CG[Caller]->removeCallEdgeFor(CS); 498 CS.getInstruction()->eraseFromParent(); 499 ++NumCallsDeleted; 500 } else { 501 // We can only inline direct calls to non-declarations. 502 if (Callee == 0 || Callee->isDeclaration()) continue; 503 504 // If this call site was obtained by inlining another function, verify 505 // that the include path for the function did not include the callee 506 // itself. If so, we'd be recursively inlining the same function, 507 // which would provide the same callsites, which would cause us to 508 // infinitely inline. 509 int InlineHistoryID = CallSites[CSi].second; 510 if (InlineHistoryID != -1 && 511 InlineHistoryIncludes(Callee, InlineHistoryID, InlineHistory)) 512 continue; 513 514 515 // If the policy determines that we should inline this function, 516 // try to do so. 517 if (!shouldInline(CS)) 518 continue; 519 520 // Attempt to inline the function. 521 if (!InlineCallIfPossible(CS, InlineInfo, InlinedArrayAllocas, 522 InlineHistoryID, InsertLifetime, DL)) 523 continue; 524 ++NumInlined; 525 526 // If inlining this function gave us any new call sites, throw them 527 // onto our worklist to process. They are useful inline candidates. 528 if (!InlineInfo.InlinedCalls.empty()) { 529 // Create a new inline history entry for this, so that we remember 530 // that these new callsites came about due to inlining Callee. 531 int NewHistoryID = InlineHistory.size(); 532 InlineHistory.push_back(std::make_pair(Callee, InlineHistoryID)); 533 534 for (unsigned i = 0, e = InlineInfo.InlinedCalls.size(); 535 i != e; ++i) { 536 Value *Ptr = InlineInfo.InlinedCalls[i]; 537 CallSites.push_back(std::make_pair(CallSite(Ptr), NewHistoryID)); 538 } 539 } 540 } 541 542 // If we inlined or deleted the last possible call site to the function, 543 // delete the function body now. 544 if (Callee && Callee->use_empty() && Callee->hasLocalLinkage() && 545 // TODO: Can remove if in SCC now. 546 !SCCFunctions.count(Callee) && 547 548 // The function may be apparently dead, but if there are indirect 549 // callgraph references to the node, we cannot delete it yet, this 550 // could invalidate the CGSCC iterator. 551 CG[Callee]->getNumReferences() == 0) { 552 DEBUG(dbgs() << " -> Deleting dead function: " 553 << Callee->getName() << "\n"); 554 CallGraphNode *CalleeNode = CG[Callee]; 555 556 // Remove any call graph edges from the callee to its callees. 557 CalleeNode->removeAllCalledFunctions(); 558 559 // Removing the node for callee from the call graph and delete it. 560 delete CG.removeFunctionFromModule(CalleeNode); 561 ++NumDeleted; 562 } 563 564 // Remove this call site from the list. If possible, use 565 // swap/pop_back for efficiency, but do not use it if doing so would 566 // move a call site to a function in this SCC before the 567 // 'FirstCallInSCC' barrier. 568 if (SCC.isSingular()) { 569 CallSites[CSi] = CallSites.back(); 570 CallSites.pop_back(); 571 } else { 572 CallSites.erase(CallSites.begin()+CSi); 573 } 574 --CSi; 575 576 Changed = true; 577 LocalChange = true; 578 } 579 } while (LocalChange); 580 581 return Changed; 582} 583 584// doFinalization - Remove now-dead linkonce functions at the end of 585// processing to avoid breaking the SCC traversal. 586bool Inliner::doFinalization(CallGraph &CG) { 587 return removeDeadFunctions(CG); 588} 589 590/// removeDeadFunctions - Remove dead functions that are not included in 591/// DNR (Do Not Remove) list. 592bool Inliner::removeDeadFunctions(CallGraph &CG, bool AlwaysInlineOnly) { 593 SmallVector<CallGraphNode*, 16> FunctionsToRemove; 594 595 // Scan for all of the functions, looking for ones that should now be removed 596 // from the program. Insert the dead ones in the FunctionsToRemove set. 597 for (CallGraph::iterator I = CG.begin(), E = CG.end(); I != E; ++I) { 598 CallGraphNode *CGN = I->second; 599 Function *F = CGN->getFunction(); 600 if (!F || F->isDeclaration()) 601 continue; 602 603 // Handle the case when this function is called and we only want to care 604 // about always-inline functions. This is a bit of a hack to share code 605 // between here and the InlineAlways pass. 606 if (AlwaysInlineOnly && 607 !F->getAttributes().hasAttribute(AttributeSet::FunctionIndex, 608 Attribute::AlwaysInline)) 609 continue; 610 611 // If the only remaining users of the function are dead constants, remove 612 // them. 613 F->removeDeadConstantUsers(); 614 615 if (!F->isDefTriviallyDead()) 616 continue; 617 618 // Remove any call graph edges from the function to its callees. 619 CGN->removeAllCalledFunctions(); 620 621 // Remove any edges from the external node to the function's call graph 622 // node. These edges might have been made irrelegant due to 623 // optimization of the program. 624 CG.getExternalCallingNode()->removeAnyCallEdgeTo(CGN); 625 626 // Removing the node for callee from the call graph and delete it. 627 FunctionsToRemove.push_back(CGN); 628 } 629 if (FunctionsToRemove.empty()) 630 return false; 631 632 // Now that we know which functions to delete, do so. We didn't want to do 633 // this inline, because that would invalidate our CallGraph::iterator 634 // objects. :( 635 // 636 // Note that it doesn't matter that we are iterating over a non-stable order 637 // here to do this, it doesn't matter which order the functions are deleted 638 // in. 639 array_pod_sort(FunctionsToRemove.begin(), FunctionsToRemove.end()); 640 FunctionsToRemove.erase(std::unique(FunctionsToRemove.begin(), 641 FunctionsToRemove.end()), 642 FunctionsToRemove.end()); 643 for (SmallVectorImpl<CallGraphNode *>::iterator I = FunctionsToRemove.begin(), 644 E = FunctionsToRemove.end(); 645 I != E; ++I) { 646 delete CG.removeFunctionFromModule(*I); 647 ++NumDeleted; 648 } 649 return true; 650} 651