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https://github.com/c64scene-ar/llvm-6502.git
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66c75aaa02
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@59758 91177308-0d34-0410-b5e6-96231b3b80d8
268 lines
9.6 KiB
C++
268 lines
9.6 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/Module.h"
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#include "llvm/Instructions.h"
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#include "llvm/Analysis/CallGraph.h"
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#include "llvm/Support/CallSite.h"
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#include "llvm/Target/TargetData.h"
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#include "llvm/Transforms/IPO/InlinerPass.h"
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#include "llvm/Transforms/Utils/Cloning.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/ADT/Statistic.h"
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#include <set>
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using namespace llvm;
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STATISTIC(NumInlined, "Number of functions inlined");
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STATISTIC(NumDeleted, "Number of functions deleted because all callers found");
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static cl::opt<int>
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InlineLimit("inline-threshold", cl::Hidden, cl::init(200),
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cl::desc("Control the amount of inlining to perform (default = 200)"));
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Inliner::Inliner(void *ID)
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: CallGraphSCCPass(ID), InlineThreshold(InlineLimit) {}
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Inliner::Inliner(void *ID, int Threshold)
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: CallGraphSCCPass(ID), InlineThreshold(Threshold) {}
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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 &Info) const {
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Info.addRequired<TargetData>();
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CallGraphSCCPass::getAnalysisUsage(Info);
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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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static bool InlineCallIfPossible(CallSite CS, CallGraph &CG,
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const std::set<Function*> &SCCFunctions,
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const TargetData &TD) {
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Function *Callee = CS.getCalledFunction();
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Function *Caller = CS.getCaller();
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if (!InlineFunction(CS, &CG, &TD)) return false;
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// 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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if (Callee->hasFnAttr(Attribute::StackProtectReq))
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Caller->addFnAttr(Attribute::StackProtectReq);
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else if (Callee->hasFnAttr(Attribute::StackProtect) &&
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!Caller->hasFnAttr(Attribute::StackProtectReq))
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Caller->addFnAttr(Attribute::StackProtect);
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// If we inlined the last possible call site to the function, delete the
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// function body now.
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if (Callee->use_empty() && Callee->hasInternalLinkage() &&
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!SCCFunctions.count(Callee)) {
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DOUT << " -> Deleting dead function: " << Callee->getName() << "\n";
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CallGraphNode *CalleeNode = CG[Callee];
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// Remove any call graph edges from the callee to its callees.
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CalleeNode->removeAllCalledFunctions();
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// Removing the node for callee from the call graph and delete it.
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delete CG.removeFunctionFromModule(CalleeNode);
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++NumDeleted;
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}
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return true;
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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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float FudgeFactor = getInlineFudgeFactor(CS);
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if (IC.isAlways()) {
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DOUT << " Inlining: cost=always"
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<< ", Call: " << *CS.getInstruction();
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return true;
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}
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if (IC.isNever()) {
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DOUT << " NOT Inlining: cost=never"
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<< ", Call: " << *CS.getInstruction();
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return false;
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}
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int Cost = IC.getValue();
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int CurrentThreshold = InlineThreshold;
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Function *Fn = CS.getCaller();
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if (Fn && !Fn->isDeclaration()
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&& Fn->hasFnAttr(Attribute::OptimizeForSize)
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&& InlineThreshold != 50) {
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CurrentThreshold = 50;
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}
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if (Cost >= (int)(CurrentThreshold * FudgeFactor)) {
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DOUT << " NOT Inlining: cost=" << Cost
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<< ", Call: " << *CS.getInstruction();
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return false;
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} else {
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DOUT << " Inlining: cost=" << Cost
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<< ", Call: " << *CS.getInstruction();
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return true;
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}
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}
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bool Inliner::runOnSCC(const std::vector<CallGraphNode*> &SCC) {
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CallGraph &CG = getAnalysis<CallGraph>();
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std::set<Function*> SCCFunctions;
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DOUT << "Inliner visiting SCC:";
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for (unsigned i = 0, e = SCC.size(); i != e; ++i) {
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Function *F = SCC[i]->getFunction();
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if (F) SCCFunctions.insert(F);
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DOUT << " " << (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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std::vector<CallSite> CallSites;
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for (unsigned i = 0, e = SCC.size(); i != e; ++i)
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if (Function *F = SCC[i]->getFunction())
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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(); I != BB->end(); ++I) {
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CallSite CS = CallSite::get(I);
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if (CS.getInstruction() && (!CS.getCalledFunction() ||
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!CS.getCalledFunction()->isDeclaration()))
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CallSites.push_back(CS);
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}
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DOUT << ": " << CallSites.size() << " call sites.\n";
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// Now that we have all of the call sites, move the ones to functions in the
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// current SCC to the end of the list.
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unsigned FirstCallInSCC = CallSites.size();
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for (unsigned i = 0; i < FirstCallInSCC; ++i)
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if (Function *F = CallSites[i].getCalledFunction())
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if (SCCFunctions.count(F))
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std::swap(CallSites[i--], CallSites[--FirstCallInSCC]);
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// Now that we have all of the call sites, loop over them and inline them if
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// it looks profitable to do so.
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bool Changed = false;
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bool LocalChange;
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do {
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LocalChange = false;
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// Iterate over the outer loop because inlining functions can cause indirect
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// calls to become direct calls.
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for (unsigned CSi = 0; CSi != CallSites.size(); ++CSi)
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if (Function *Callee = CallSites[CSi].getCalledFunction()) {
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// Calls to external functions are never inlinable.
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if (Callee->isDeclaration() ||
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CallSites[CSi].getInstruction()->getParent()->getParent() ==Callee){
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if (SCC.size() == 1) {
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std::swap(CallSites[CSi], CallSites.back());
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CallSites.pop_back();
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} else {
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// Keep the 'in SCC / not in SCC' boundary correct.
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CallSites.erase(CallSites.begin()+CSi);
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}
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--CSi;
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continue;
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}
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// If the policy determines that we should inline this function,
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// try to do so.
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CallSite CS = CallSites[CSi];
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if (shouldInline(CS)) {
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// Attempt to inline the function...
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if (InlineCallIfPossible(CS, CG, SCCFunctions,
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getAnalysis<TargetData>())) {
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// Remove this call site from the list. If possible, use
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// swap/pop_back for efficiency, but do not use it if doing so would
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// move a call site to a function in this SCC before the
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// 'FirstCallInSCC' barrier.
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if (SCC.size() == 1) {
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std::swap(CallSites[CSi], CallSites.back());
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CallSites.pop_back();
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} else {
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CallSites.erase(CallSites.begin()+CSi);
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}
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--CSi;
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++NumInlined;
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Changed = true;
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LocalChange = true;
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}
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}
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}
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} while (LocalChange);
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return Changed;
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}
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// doFinalization - Remove now-dead linkonce functions at the end of
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// processing to avoid breaking the SCC traversal.
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bool Inliner::doFinalization(CallGraph &CG) {
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return removeDeadFunctions(CG);
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}
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/// removeDeadFunctions - Remove dead functions that are not included in
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/// DNR (Do Not Remove) list.
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bool Inliner::removeDeadFunctions(CallGraph &CG,
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SmallPtrSet<const Function *, 16> *DNR) {
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std::set<CallGraphNode*> FunctionsToRemove;
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// Scan for all of the functions, looking for ones that should now be removed
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// from the program. Insert the dead ones in the FunctionsToRemove set.
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for (CallGraph::iterator I = CG.begin(), E = CG.end(); I != E; ++I) {
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CallGraphNode *CGN = I->second;
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if (Function *F = CGN ? CGN->getFunction() : 0) {
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// If the only remaining users of the function are dead constants, remove
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// them.
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F->removeDeadConstantUsers();
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if (DNR && DNR->count(F))
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continue;
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if ((F->hasLinkOnceLinkage() || F->hasInternalLinkage()) &&
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F->use_empty()) {
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// Remove any call graph edges from the function to its callees.
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CGN->removeAllCalledFunctions();
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// Remove any edges from the external node to the function's call graph
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// node. These edges might have been made irrelegant due to
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// optimization of the program.
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CG.getExternalCallingNode()->removeAnyCallEdgeTo(CGN);
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// Removing the node for callee from the call graph and delete it.
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FunctionsToRemove.insert(CGN);
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}
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}
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}
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// Now that we know which functions to delete, do so. We didn't want to do
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// this inline, because that would invalidate our CallGraph::iterator
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// objects. :(
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bool Changed = false;
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for (std::set<CallGraphNode*>::iterator I = FunctionsToRemove.begin(),
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E = FunctionsToRemove.end(); I != E; ++I) {
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delete CG.removeFunctionFromModule(*I);
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++NumDeleted;
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Changed = true;
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}
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return Changed;
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}
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