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Eventually it would be nice if CallGraph maintained an ilist of CallGraphNode's instead of a vector of pointers to them, but today is not that day. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@13100 91177308-0d34-0410-b5e6-96231b3b80d8
189 lines
7.4 KiB
C++
189 lines
7.4 KiB
C++
//===- InlineCommon.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 was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source 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 code shared between the LLVM inliners. This
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// implements all of the boring mechanics of the bottom-up inlining.
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//
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//===----------------------------------------------------------------------===//
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#include "Inliner.h"
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#include "llvm/Constants.h" // ConstantPointerRef should die
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#include "llvm/Module.h"
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#include "llvm/iOther.h"
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#include "llvm/iTerminators.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/Transforms/Utils/Cloning.h"
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#include "Support/CommandLine.h"
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#include "Support/Debug.h"
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#include "Support/Statistic.h"
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using namespace llvm;
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namespace {
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Statistic<> NumInlined("inline", "Number of functions inlined");
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Statistic<> NumDeleted("inline", "Number of functions deleted because all callers found");
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cl::opt<unsigned> // FIXME: 200 is VERY conservative
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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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}
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Inliner::Inliner() : InlineThreshold(InlineLimit) {}
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int Inliner::getRecursiveInlineCost(CallSite CS) {
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return getInlineCost(CS);
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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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DEBUG(std::cerr << "Inliner visiting SCC:");
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for (unsigned i = 0, e = SCC.size(); i != e; ++i) {
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SCCFunctions.insert(SCC[i]->getFunction());
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DEBUG(std::cerr << " " << (SCC[i]->getFunction() ?
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SCC[i]->getFunction()->getName() : "INDIRECTNODE"));
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}
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DEBUG(std::cerr << "\n");
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bool Changed = false;
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for (std::set<Function*>::iterator SCCI = SCCFunctions.begin(),
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E = SCCFunctions.end(); SCCI != E; ++SCCI) {
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Function *F = *SCCI;
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if (F == 0 || F->isExternal()) continue;
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DEBUG(std::cerr << " Inspecting function: " << F->getName() << "\n");
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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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// in inlining other functions.
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std::vector<CallSite> CallSites;
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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()->isExternal())
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CallSites.push_back(CS);
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}
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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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for (unsigned i = 0, e = CallSites.size(); i != e; ++i) {
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CallSite CS = CallSites[i];
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Function *Callee = CS.getCalledFunction();
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// Determine whether this is a function IN the SCC...
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bool inSCC = SCCFunctions.count(Callee);
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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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int InlineCost = inSCC ? getRecursiveInlineCost(CS) : getInlineCost(CS);
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if (InlineCost >= (int)InlineThreshold) {
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DEBUG(std::cerr << " NOT Inlining: cost=" << InlineCost
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<< ", Call: " << *CS.getInstruction());
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} else {
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DEBUG(std::cerr << " Inlining: cost=" << InlineCost
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<< ", Call: " << *CS.getInstruction());
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Function *Caller = CS.getInstruction()->getParent()->getParent();
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// Attempt to inline the function...
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if (InlineFunction(CS)) {
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++NumInlined;
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// Update the call graph by deleting the edge from Callee to Caller
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CallGraphNode *CalleeNode = CG[Callee];
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CallGraphNode *CallerNode = CG[Caller];
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CallerNode->removeCallEdgeTo(CalleeNode);
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// Since we inlined all uninlinable call sites in the callee into the
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// caller, add edges from the caller to all of the callees of the
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// callee.
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for (CallGraphNode::iterator I = CalleeNode->begin(),
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E = CalleeNode->end(); I != E; ++I)
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CallerNode->addCalledFunction(*I);
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// If we inlined the last possible call site to the function,
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// delete the function body now.
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if (Callee->use_empty() && Callee != Caller &&
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Callee->hasInternalLinkage()) {
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DEBUG(std::cerr << " -> Deleting dead function: "
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<< Callee->getName() << "\n");
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SCCFunctions.erase(Callee); // Remove function from this SCC.
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// Remove any call graph edges from the callee to its callees.
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while (CalleeNode->begin() != CalleeNode->end())
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CalleeNode->removeCallEdgeTo(*(CalleeNode->end()-1));
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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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Changed = true;
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}
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}
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}
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}
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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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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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Function *F = CGN ? CGN->getFunction() : 0;
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// If the only remaining use of the function is a dead constant
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// pointer ref, remove it.
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if (F && F->hasOneUse())
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if (ConstantPointerRef *CPR = dyn_cast<ConstantPointerRef>(F->use_back()))
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if (CPR->use_empty()) {
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CPR->destroyConstant();
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if (F->hasInternalLinkage()) {
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// There *MAY* be an edge from the external call node to this
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// function. If so, remove it.
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CallGraphNode *EN = CG.getExternalCallingNode();
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CallGraphNode::iterator I = std::find(EN->begin(), EN->end(), CGN);
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if (I != EN->end()) EN->removeCallEdgeTo(CGN);
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}
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}
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if (F && (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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while (CGN->begin() != CGN->end())
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CGN->removeCallEdgeTo(*(CGN->end()-1));
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// If the function has external linkage (basically if it's a linkonce
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// function) remove the edge from the external node to the callee node.
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if (!F->hasInternalLinkage())
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CG.getExternalCallingNode()->removeCallEdgeTo(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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// 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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