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DebugLoc in Callsite would not live after Inliner. It should be copied before Inliner. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206459 91177308-0d34-0410-b5e6-96231b3b80d8
660 lines
28 KiB
C++
660 lines
28 KiB
C++
//===- Inliner.cpp - Code common to all inliners --------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the mechanics required to implement inlining without
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// missing any calls and updating the call graph. The decisions of which calls
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// are profitable to inline are implemented elsewhere.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "inline"
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#include "llvm/Transforms/IPO/InlinerPass.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Analysis/CallGraph.h"
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#include "llvm/Analysis/InlineCost.h"
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#include "llvm/IR/CallSite.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/IR/DiagnosticInfo.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/IntrinsicInst.h"
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#include "llvm/IR/Module.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/Target/TargetLibraryInfo.h"
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#include "llvm/Transforms/Utils/Cloning.h"
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#include "llvm/Transforms/Utils/Local.h"
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using namespace llvm;
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STATISTIC(NumInlined, "Number of functions inlined");
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STATISTIC(NumCallsDeleted, "Number of call sites deleted, not inlined");
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STATISTIC(NumDeleted, "Number of functions deleted because all callers found");
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STATISTIC(NumMergedAllocas, "Number of allocas merged together");
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// This weirdly named statistic tracks the number of times that, when attempting
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// to inline a function A into B, we analyze the callers of B in order to see
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// if those would be more profitable and blocked inline steps.
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STATISTIC(NumCallerCallersAnalyzed, "Number of caller-callers analyzed");
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static cl::opt<int>
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InlineLimit("inline-threshold", cl::Hidden, cl::init(225), cl::ZeroOrMore,
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cl::desc("Control the amount of inlining to perform (default = 225)"));
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static cl::opt<int>
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HintThreshold("inlinehint-threshold", cl::Hidden, cl::init(325),
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cl::desc("Threshold for inlining functions with inline hint"));
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// We instroduce this threshold to help performance of instrumentation based
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// PGO before we actually hook up inliner with analysis passes such as BPI and
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// BFI.
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static cl::opt<int>
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ColdThreshold("inlinecold-threshold", cl::Hidden, cl::init(225),
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cl::desc("Threshold for inlining functions with cold attribute"));
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// Threshold to use when optsize is specified (and there is no -inline-limit).
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const int OptSizeThreshold = 75;
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Inliner::Inliner(char &ID)
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: CallGraphSCCPass(ID), InlineThreshold(InlineLimit), InsertLifetime(true) {}
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Inliner::Inliner(char &ID, int Threshold, bool InsertLifetime)
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: CallGraphSCCPass(ID), InlineThreshold(InlineLimit.getNumOccurrences() > 0 ?
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InlineLimit : Threshold),
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InsertLifetime(InsertLifetime) {}
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/// getAnalysisUsage - For this class, we declare that we require and preserve
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/// the call graph. If the derived class implements this method, it should
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/// always explicitly call the implementation here.
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void Inliner::getAnalysisUsage(AnalysisUsage &AU) const {
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CallGraphSCCPass::getAnalysisUsage(AU);
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}
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typedef DenseMap<ArrayType*, std::vector<AllocaInst*> >
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InlinedArrayAllocasTy;
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/// \brief If the inlined function had a higher stack protection level than the
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/// calling function, then bump up the caller's stack protection level.
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static void AdjustCallerSSPLevel(Function *Caller, Function *Callee) {
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// If upgrading the SSP attribute, clear out the old SSP Attributes first.
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// Having multiple SSP attributes doesn't actually hurt, but it adds useless
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// clutter to the IR.
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AttrBuilder B;
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B.addAttribute(Attribute::StackProtect)
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.addAttribute(Attribute::StackProtectStrong);
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AttributeSet OldSSPAttr = AttributeSet::get(Caller->getContext(),
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AttributeSet::FunctionIndex,
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B);
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AttributeSet CallerAttr = Caller->getAttributes(),
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CalleeAttr = Callee->getAttributes();
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if (CalleeAttr.hasAttribute(AttributeSet::FunctionIndex,
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Attribute::StackProtectReq)) {
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Caller->removeAttributes(AttributeSet::FunctionIndex, OldSSPAttr);
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Caller->addFnAttr(Attribute::StackProtectReq);
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} else if (CalleeAttr.hasAttribute(AttributeSet::FunctionIndex,
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Attribute::StackProtectStrong) &&
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!CallerAttr.hasAttribute(AttributeSet::FunctionIndex,
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Attribute::StackProtectReq)) {
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Caller->removeAttributes(AttributeSet::FunctionIndex, OldSSPAttr);
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Caller->addFnAttr(Attribute::StackProtectStrong);
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} else if (CalleeAttr.hasAttribute(AttributeSet::FunctionIndex,
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Attribute::StackProtect) &&
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!CallerAttr.hasAttribute(AttributeSet::FunctionIndex,
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Attribute::StackProtectReq) &&
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!CallerAttr.hasAttribute(AttributeSet::FunctionIndex,
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Attribute::StackProtectStrong))
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Caller->addFnAttr(Attribute::StackProtect);
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}
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/// InlineCallIfPossible - If it is possible to inline the specified call site,
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/// do so and update the CallGraph for this operation.
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///
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/// This function also does some basic book-keeping to update the IR. The
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/// InlinedArrayAllocas map keeps track of any allocas that are already
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/// available from other functions inlined into the caller. If we are able to
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/// inline this call site we attempt to reuse already available allocas or add
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/// any new allocas to the set if not possible.
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static bool InlineCallIfPossible(CallSite CS, InlineFunctionInfo &IFI,
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InlinedArrayAllocasTy &InlinedArrayAllocas,
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int InlineHistory, bool InsertLifetime,
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const DataLayout *DL) {
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Function *Callee = CS.getCalledFunction();
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Function *Caller = CS.getCaller();
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// Try to inline the function. Get the list of static allocas that were
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// inlined.
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if (!InlineFunction(CS, IFI, InsertLifetime))
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return false;
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AdjustCallerSSPLevel(Caller, Callee);
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// Look at all of the allocas that we inlined through this call site. If we
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// have already inlined other allocas through other calls into this function,
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// then we know that they have disjoint lifetimes and that we can merge them.
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//
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// There are many heuristics possible for merging these allocas, and the
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// different options have different tradeoffs. One thing that we *really*
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// don't want to hurt is SRoA: once inlining happens, often allocas are no
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// longer address taken and so they can be promoted.
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//
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// Our "solution" for that is to only merge allocas whose outermost type is an
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// array type. These are usually not promoted because someone is using a
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// variable index into them. These are also often the most important ones to
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// merge.
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//
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// A better solution would be to have real memory lifetime markers in the IR
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// and not have the inliner do any merging of allocas at all. This would
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// allow the backend to do proper stack slot coloring of all allocas that
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// *actually make it to the backend*, which is really what we want.
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//
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// Because we don't have this information, we do this simple and useful hack.
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//
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SmallPtrSet<AllocaInst*, 16> UsedAllocas;
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// When processing our SCC, check to see if CS was inlined from some other
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// call site. For example, if we're processing "A" in this code:
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// A() { B() }
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// B() { x = alloca ... C() }
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// C() { y = alloca ... }
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// Assume that C was not inlined into B initially, and so we're processing A
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// and decide to inline B into A. Doing this makes an alloca available for
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// reuse and makes a callsite (C) available for inlining. When we process
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// the C call site we don't want to do any alloca merging between X and Y
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// because their scopes are not disjoint. We could make this smarter by
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// keeping track of the inline history for each alloca in the
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// InlinedArrayAllocas but this isn't likely to be a significant win.
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if (InlineHistory != -1) // Only do merging for top-level call sites in SCC.
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return true;
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// Loop over all the allocas we have so far and see if they can be merged with
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// a previously inlined alloca. If not, remember that we had it.
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for (unsigned AllocaNo = 0, e = IFI.StaticAllocas.size();
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AllocaNo != e; ++AllocaNo) {
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AllocaInst *AI = IFI.StaticAllocas[AllocaNo];
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// Don't bother trying to merge array allocations (they will usually be
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// canonicalized to be an allocation *of* an array), or allocations whose
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// type is not itself an array (because we're afraid of pessimizing SRoA).
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ArrayType *ATy = dyn_cast<ArrayType>(AI->getAllocatedType());
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if (ATy == 0 || AI->isArrayAllocation())
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continue;
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// Get the list of all available allocas for this array type.
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std::vector<AllocaInst*> &AllocasForType = InlinedArrayAllocas[ATy];
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// Loop over the allocas in AllocasForType to see if we can reuse one. Note
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// that we have to be careful not to reuse the same "available" alloca for
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// multiple different allocas that we just inlined, we use the 'UsedAllocas'
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// set to keep track of which "available" allocas are being used by this
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// function. Also, AllocasForType can be empty of course!
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bool MergedAwayAlloca = false;
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for (unsigned i = 0, e = AllocasForType.size(); i != e; ++i) {
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AllocaInst *AvailableAlloca = AllocasForType[i];
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unsigned Align1 = AI->getAlignment(),
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Align2 = AvailableAlloca->getAlignment();
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// If we don't have data layout information, and only one alloca is using
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// the target default, then we can't safely merge them because we can't
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// pick the greater alignment.
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if (!DL && (!Align1 || !Align2) && Align1 != Align2)
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continue;
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// The available alloca has to be in the right function, not in some other
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// function in this SCC.
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if (AvailableAlloca->getParent() != AI->getParent())
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continue;
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// If the inlined function already uses this alloca then we can't reuse
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// it.
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if (!UsedAllocas.insert(AvailableAlloca))
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continue;
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// Otherwise, we *can* reuse it, RAUW AI into AvailableAlloca and declare
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// success!
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DEBUG(dbgs() << " ***MERGED ALLOCA: " << *AI << "\n\t\tINTO: "
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<< *AvailableAlloca << '\n');
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AI->replaceAllUsesWith(AvailableAlloca);
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if (Align1 != Align2) {
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if (!Align1 || !Align2) {
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assert(DL && "DataLayout required to compare default alignments");
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unsigned TypeAlign = DL->getABITypeAlignment(AI->getAllocatedType());
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Align1 = Align1 ? Align1 : TypeAlign;
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Align2 = Align2 ? Align2 : TypeAlign;
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}
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if (Align1 > Align2)
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AvailableAlloca->setAlignment(AI->getAlignment());
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}
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AI->eraseFromParent();
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MergedAwayAlloca = true;
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++NumMergedAllocas;
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IFI.StaticAllocas[AllocaNo] = 0;
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break;
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}
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// If we already nuked the alloca, we're done with it.
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if (MergedAwayAlloca)
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continue;
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// If we were unable to merge away the alloca either because there are no
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// allocas of the right type available or because we reused them all
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// already, remember that this alloca came from an inlined function and mark
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// it used so we don't reuse it for other allocas from this inline
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// operation.
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AllocasForType.push_back(AI);
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UsedAllocas.insert(AI);
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}
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return true;
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}
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unsigned Inliner::getInlineThreshold(CallSite CS) const {
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int thres = InlineThreshold; // -inline-threshold or else selected by
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// overall opt level
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// If -inline-threshold is not given, listen to the optsize attribute when it
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// would decrease the threshold.
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Function *Caller = CS.getCaller();
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bool OptSize = Caller && !Caller->isDeclaration() &&
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Caller->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
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Attribute::OptimizeForSize);
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if (!(InlineLimit.getNumOccurrences() > 0) && OptSize &&
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OptSizeThreshold < thres)
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thres = OptSizeThreshold;
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// Listen to the inlinehint attribute when it would increase the threshold
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// and the caller does not need to minimize its size.
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Function *Callee = CS.getCalledFunction();
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bool InlineHint = Callee && !Callee->isDeclaration() &&
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Callee->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
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Attribute::InlineHint);
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if (InlineHint && HintThreshold > thres
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&& !Caller->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
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Attribute::MinSize))
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thres = HintThreshold;
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// Listen to the cold attribute when it would decrease the threshold.
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bool ColdCallee = Callee && !Callee->isDeclaration() &&
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Callee->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
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Attribute::Cold);
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if (ColdCallee && ColdThreshold < thres)
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thres = ColdThreshold;
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return thres;
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}
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/// shouldInline - Return true if the inliner should attempt to inline
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/// at the given CallSite.
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bool Inliner::shouldInline(CallSite CS) {
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InlineCost IC = getInlineCost(CS);
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if (IC.isAlways()) {
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DEBUG(dbgs() << " Inlining: cost=always"
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<< ", Call: " << *CS.getInstruction() << "\n");
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return true;
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}
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if (IC.isNever()) {
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DEBUG(dbgs() << " NOT Inlining: cost=never"
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<< ", Call: " << *CS.getInstruction() << "\n");
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return false;
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}
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Function *Caller = CS.getCaller();
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if (!IC) {
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DEBUG(dbgs() << " NOT Inlining: cost=" << IC.getCost()
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<< ", thres=" << (IC.getCostDelta() + IC.getCost())
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<< ", Call: " << *CS.getInstruction() << "\n");
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return false;
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}
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// Try to detect the case where the current inlining candidate caller (call
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// it B) is a static or linkonce-ODR function and is an inlining candidate
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// elsewhere, and the current candidate callee (call it C) is large enough
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// that inlining it into B would make B too big to inline later. In these
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// circumstances it may be best not to inline C into B, but to inline B into
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// its callers.
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//
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// This only applies to static and linkonce-ODR functions because those are
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// expected to be available for inlining in the translation units where they
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// are used. Thus we will always have the opportunity to make local inlining
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// decisions. Importantly the linkonce-ODR linkage covers inline functions
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// and templates in C++.
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//
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// FIXME: All of this logic should be sunk into getInlineCost. It relies on
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// the internal implementation of the inline cost metrics rather than
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// treating them as truly abstract units etc.
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if (Caller->hasLocalLinkage() ||
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Caller->getLinkage() == GlobalValue::LinkOnceODRLinkage) {
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int TotalSecondaryCost = 0;
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// The candidate cost to be imposed upon the current function.
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int CandidateCost = IC.getCost() - (InlineConstants::CallPenalty + 1);
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// This bool tracks what happens if we do NOT inline C into B.
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bool callerWillBeRemoved = Caller->hasLocalLinkage();
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// This bool tracks what happens if we DO inline C into B.
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bool inliningPreventsSomeOuterInline = false;
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for (User *U : Caller->users()) {
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CallSite CS2(U);
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// If this isn't a call to Caller (it could be some other sort
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// of reference) skip it. Such references will prevent the caller
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// from being removed.
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if (!CS2 || CS2.getCalledFunction() != Caller) {
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callerWillBeRemoved = false;
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continue;
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}
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InlineCost IC2 = getInlineCost(CS2);
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++NumCallerCallersAnalyzed;
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if (!IC2) {
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callerWillBeRemoved = false;
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continue;
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}
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if (IC2.isAlways())
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continue;
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// See if inlining or original callsite would erase the cost delta of
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// this callsite. We subtract off the penalty for the call instruction,
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// which we would be deleting.
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if (IC2.getCostDelta() <= CandidateCost) {
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inliningPreventsSomeOuterInline = true;
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TotalSecondaryCost += IC2.getCost();
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}
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}
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// If all outer calls to Caller would get inlined, the cost for the last
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// one is set very low by getInlineCost, in anticipation that Caller will
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// be removed entirely. We did not account for this above unless there
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// is only one caller of Caller.
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if (callerWillBeRemoved && !Caller->use_empty())
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TotalSecondaryCost += InlineConstants::LastCallToStaticBonus;
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if (inliningPreventsSomeOuterInline && TotalSecondaryCost < IC.getCost()) {
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DEBUG(dbgs() << " NOT Inlining: " << *CS.getInstruction() <<
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" Cost = " << IC.getCost() <<
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", outer Cost = " << TotalSecondaryCost << '\n');
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return false;
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}
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}
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DEBUG(dbgs() << " Inlining: cost=" << IC.getCost()
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<< ", thres=" << (IC.getCostDelta() + IC.getCost())
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<< ", Call: " << *CS.getInstruction() << '\n');
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return true;
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}
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/// InlineHistoryIncludes - Return true if the specified inline history ID
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/// indicates an inline history that includes the specified function.
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static bool InlineHistoryIncludes(Function *F, int InlineHistoryID,
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const SmallVectorImpl<std::pair<Function*, int> > &InlineHistory) {
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while (InlineHistoryID != -1) {
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assert(unsigned(InlineHistoryID) < InlineHistory.size() &&
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"Invalid inline history ID");
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if (InlineHistory[InlineHistoryID].first == F)
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return true;
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InlineHistoryID = InlineHistory[InlineHistoryID].second;
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}
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return false;
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}
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bool Inliner::runOnSCC(CallGraphSCC &SCC) {
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CallGraph &CG = getAnalysis<CallGraphWrapperPass>().getCallGraph();
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DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
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const DataLayout *DL = DLP ? &DLP->getDataLayout() : 0;
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const TargetLibraryInfo *TLI = getAnalysisIfAvailable<TargetLibraryInfo>();
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SmallPtrSet<Function*, 8> SCCFunctions;
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DEBUG(dbgs() << "Inliner visiting SCC:");
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for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
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Function *F = (*I)->getFunction();
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if (F) SCCFunctions.insert(F);
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DEBUG(dbgs() << " " << (F ? F->getName() : "INDIRECTNODE"));
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}
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// Scan through and identify all call sites ahead of time so that we only
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// inline call sites in the original functions, not call sites that result
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// from inlining other functions.
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SmallVector<std::pair<CallSite, int>, 16> CallSites;
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// When inlining a callee produces new call sites, we want to keep track of
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// the fact that they were inlined from the callee. This allows us to avoid
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// infinite inlining in some obscure cases. To represent this, we use an
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// index into the InlineHistory vector.
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SmallVector<std::pair<Function*, int>, 8> InlineHistory;
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for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
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Function *F = (*I)->getFunction();
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if (!F) continue;
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for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
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for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
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CallSite CS(cast<Value>(I));
|
|
// If this isn't a call, or it is a call to an intrinsic, it can
|
|
// never be inlined.
|
|
if (!CS || isa<IntrinsicInst>(I))
|
|
continue;
|
|
|
|
// If this is a direct call to an external function, we can never inline
|
|
// it. If it is an indirect call, inlining may resolve it to be a
|
|
// direct call, so we keep it.
|
|
if (CS.getCalledFunction() && CS.getCalledFunction()->isDeclaration())
|
|
continue;
|
|
|
|
CallSites.push_back(std::make_pair(CS, -1));
|
|
}
|
|
}
|
|
|
|
DEBUG(dbgs() << ": " << CallSites.size() << " call sites.\n");
|
|
|
|
// If there are no calls in this function, exit early.
|
|
if (CallSites.empty())
|
|
return false;
|
|
|
|
// Now that we have all of the call sites, move the ones to functions in the
|
|
// current SCC to the end of the list.
|
|
unsigned FirstCallInSCC = CallSites.size();
|
|
for (unsigned i = 0; i < FirstCallInSCC; ++i)
|
|
if (Function *F = CallSites[i].first.getCalledFunction())
|
|
if (SCCFunctions.count(F))
|
|
std::swap(CallSites[i--], CallSites[--FirstCallInSCC]);
|
|
|
|
|
|
InlinedArrayAllocasTy InlinedArrayAllocas;
|
|
InlineFunctionInfo InlineInfo(&CG, DL);
|
|
|
|
// Now that we have all of the call sites, loop over them and inline them if
|
|
// it looks profitable to do so.
|
|
bool Changed = false;
|
|
bool LocalChange;
|
|
do {
|
|
LocalChange = false;
|
|
// Iterate over the outer loop because inlining functions can cause indirect
|
|
// calls to become direct calls.
|
|
for (unsigned CSi = 0; CSi != CallSites.size(); ++CSi) {
|
|
CallSite CS = CallSites[CSi].first;
|
|
|
|
Function *Caller = CS.getCaller();
|
|
Function *Callee = CS.getCalledFunction();
|
|
|
|
// If this call site is dead and it is to a readonly function, we should
|
|
// just delete the call instead of trying to inline it, regardless of
|
|
// size. This happens because IPSCCP propagates the result out of the
|
|
// call and then we're left with the dead call.
|
|
if (isInstructionTriviallyDead(CS.getInstruction(), TLI)) {
|
|
DEBUG(dbgs() << " -> Deleting dead call: "
|
|
<< *CS.getInstruction() << "\n");
|
|
// Update the call graph by deleting the edge from Callee to Caller.
|
|
CG[Caller]->removeCallEdgeFor(CS);
|
|
CS.getInstruction()->eraseFromParent();
|
|
++NumCallsDeleted;
|
|
} else {
|
|
// We can only inline direct calls to non-declarations.
|
|
if (Callee == 0 || Callee->isDeclaration()) continue;
|
|
|
|
// If this call site was obtained by inlining another function, verify
|
|
// that the include path for the function did not include the callee
|
|
// itself. If so, we'd be recursively inlining the same function,
|
|
// which would provide the same callsites, which would cause us to
|
|
// infinitely inline.
|
|
int InlineHistoryID = CallSites[CSi].second;
|
|
if (InlineHistoryID != -1 &&
|
|
InlineHistoryIncludes(Callee, InlineHistoryID, InlineHistory))
|
|
continue;
|
|
|
|
|
|
// If the policy determines that we should inline this function,
|
|
// try to do so.
|
|
if (!shouldInline(CS))
|
|
continue;
|
|
|
|
// Get DebugLoc to report. CS will be invalid after Inliner.
|
|
DebugLoc DLoc = CS.getInstruction()->getDebugLoc();
|
|
|
|
// Attempt to inline the function.
|
|
if (!InlineCallIfPossible(CS, InlineInfo, InlinedArrayAllocas,
|
|
InlineHistoryID, InsertLifetime, DL))
|
|
continue;
|
|
++NumInlined;
|
|
|
|
// Report the inline decision.
|
|
Caller->getContext().emitOptimizationRemark(
|
|
DEBUG_TYPE, *Caller, DLoc,
|
|
Twine(Callee->getName() + " inlined into " + Caller->getName()));
|
|
|
|
// If inlining this function gave us any new call sites, throw them
|
|
// onto our worklist to process. They are useful inline candidates.
|
|
if (!InlineInfo.InlinedCalls.empty()) {
|
|
// Create a new inline history entry for this, so that we remember
|
|
// that these new callsites came about due to inlining Callee.
|
|
int NewHistoryID = InlineHistory.size();
|
|
InlineHistory.push_back(std::make_pair(Callee, InlineHistoryID));
|
|
|
|
for (unsigned i = 0, e = InlineInfo.InlinedCalls.size();
|
|
i != e; ++i) {
|
|
Value *Ptr = InlineInfo.InlinedCalls[i];
|
|
CallSites.push_back(std::make_pair(CallSite(Ptr), NewHistoryID));
|
|
}
|
|
}
|
|
}
|
|
|
|
// If we inlined or deleted the last possible call site to the function,
|
|
// delete the function body now.
|
|
if (Callee && Callee->use_empty() && Callee->hasLocalLinkage() &&
|
|
// TODO: Can remove if in SCC now.
|
|
!SCCFunctions.count(Callee) &&
|
|
|
|
// The function may be apparently dead, but if there are indirect
|
|
// callgraph references to the node, we cannot delete it yet, this
|
|
// could invalidate the CGSCC iterator.
|
|
CG[Callee]->getNumReferences() == 0) {
|
|
DEBUG(dbgs() << " -> Deleting dead function: "
|
|
<< Callee->getName() << "\n");
|
|
CallGraphNode *CalleeNode = CG[Callee];
|
|
|
|
// Remove any call graph edges from the callee to its callees.
|
|
CalleeNode->removeAllCalledFunctions();
|
|
|
|
// Removing the node for callee from the call graph and delete it.
|
|
delete CG.removeFunctionFromModule(CalleeNode);
|
|
++NumDeleted;
|
|
}
|
|
|
|
// Remove this call site from the list. If possible, use
|
|
// swap/pop_back for efficiency, but do not use it if doing so would
|
|
// move a call site to a function in this SCC before the
|
|
// 'FirstCallInSCC' barrier.
|
|
if (SCC.isSingular()) {
|
|
CallSites[CSi] = CallSites.back();
|
|
CallSites.pop_back();
|
|
} else {
|
|
CallSites.erase(CallSites.begin()+CSi);
|
|
}
|
|
--CSi;
|
|
|
|
Changed = true;
|
|
LocalChange = true;
|
|
}
|
|
} while (LocalChange);
|
|
|
|
return Changed;
|
|
}
|
|
|
|
// doFinalization - Remove now-dead linkonce functions at the end of
|
|
// processing to avoid breaking the SCC traversal.
|
|
bool Inliner::doFinalization(CallGraph &CG) {
|
|
return removeDeadFunctions(CG);
|
|
}
|
|
|
|
/// removeDeadFunctions - Remove dead functions that are not included in
|
|
/// DNR (Do Not Remove) list.
|
|
bool Inliner::removeDeadFunctions(CallGraph &CG, bool AlwaysInlineOnly) {
|
|
SmallVector<CallGraphNode*, 16> FunctionsToRemove;
|
|
|
|
// Scan for all of the functions, looking for ones that should now be removed
|
|
// from the program. Insert the dead ones in the FunctionsToRemove set.
|
|
for (CallGraph::iterator I = CG.begin(), E = CG.end(); I != E; ++I) {
|
|
CallGraphNode *CGN = I->second;
|
|
Function *F = CGN->getFunction();
|
|
if (!F || F->isDeclaration())
|
|
continue;
|
|
|
|
// Handle the case when this function is called and we only want to care
|
|
// about always-inline functions. This is a bit of a hack to share code
|
|
// between here and the InlineAlways pass.
|
|
if (AlwaysInlineOnly &&
|
|
!F->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
|
|
Attribute::AlwaysInline))
|
|
continue;
|
|
|
|
// If the only remaining users of the function are dead constants, remove
|
|
// them.
|
|
F->removeDeadConstantUsers();
|
|
|
|
if (!F->isDefTriviallyDead())
|
|
continue;
|
|
|
|
// Remove any call graph edges from the function to its callees.
|
|
CGN->removeAllCalledFunctions();
|
|
|
|
// Remove any edges from the external node to the function's call graph
|
|
// node. These edges might have been made irrelegant due to
|
|
// optimization of the program.
|
|
CG.getExternalCallingNode()->removeAnyCallEdgeTo(CGN);
|
|
|
|
// Removing the node for callee from the call graph and delete it.
|
|
FunctionsToRemove.push_back(CGN);
|
|
}
|
|
if (FunctionsToRemove.empty())
|
|
return false;
|
|
|
|
// Now that we know which functions to delete, do so. We didn't want to do
|
|
// this inline, because that would invalidate our CallGraph::iterator
|
|
// objects. :(
|
|
//
|
|
// Note that it doesn't matter that we are iterating over a non-stable order
|
|
// here to do this, it doesn't matter which order the functions are deleted
|
|
// in.
|
|
array_pod_sort(FunctionsToRemove.begin(), FunctionsToRemove.end());
|
|
FunctionsToRemove.erase(std::unique(FunctionsToRemove.begin(),
|
|
FunctionsToRemove.end()),
|
|
FunctionsToRemove.end());
|
|
for (SmallVectorImpl<CallGraphNode *>::iterator I = FunctionsToRemove.begin(),
|
|
E = FunctionsToRemove.end();
|
|
I != E; ++I) {
|
|
delete CG.removeFunctionFromModule(*I);
|
|
++NumDeleted;
|
|
}
|
|
return true;
|
|
}
|