| //===- Inliner.cpp - Code common to all inliners --------------------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file was developed by the LLVM research group and is distributed under |
| // the University of Illinois Open Source License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file implements the mechanics required to implement inlining without |
| // missing any calls and updating the call graph. The decisions of which calls |
| // are profitable to inline are implemented elsewhere. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #define DEBUG_TYPE "inline" |
| #include "llvm/Module.h" |
| #include "llvm/Instructions.h" |
| #include "llvm/Analysis/CallGraph.h" |
| #include "llvm/Support/CallSite.h" |
| #include "llvm/Target/TargetData.h" |
| #include "llvm/Transforms/IPO/InlinerPass.h" |
| #include "llvm/Transforms/Utils/Cloning.h" |
| #include "llvm/Support/CommandLine.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/ADT/Statistic.h" |
| #include <set> |
| using namespace llvm; |
| |
| STATISTIC(NumInlined, "Number of functions inlined"); |
| STATISTIC(NumDeleted, "Number of functions deleted because all callers found"); |
| |
| namespace { |
| cl::opt<unsigned> // FIXME: 200 is VERY conservative |
| InlineLimit("inline-threshold", cl::Hidden, cl::init(200), |
| cl::desc("Control the amount of inlining to perform (default = 200)")); |
| } |
| |
| Inliner::Inliner(const void *ID) |
| : CallGraphSCCPass((intptr_t)ID), InlineThreshold(InlineLimit) {} |
| |
| /// getAnalysisUsage - For this class, we declare that we require and preserve |
| /// the call graph. If the derived class implements this method, it should |
| /// always explicitly call the implementation here. |
| void Inliner::getAnalysisUsage(AnalysisUsage &Info) const { |
| Info.addRequired<TargetData>(); |
| CallGraphSCCPass::getAnalysisUsage(Info); |
| } |
| |
| // InlineCallIfPossible - If it is possible to inline the specified call site, |
| // do so and update the CallGraph for this operation. |
| static bool InlineCallIfPossible(CallSite CS, CallGraph &CG, |
| const std::set<Function*> &SCCFunctions, |
| const TargetData &TD) { |
| Function *Callee = CS.getCalledFunction(); |
| if (!InlineFunction(CS, &CG, &TD)) return false; |
| |
| // If we inlined the last possible call site to the function, delete the |
| // function body now. |
| if (Callee->use_empty() && Callee->hasInternalLinkage() && |
| !SCCFunctions.count(Callee)) { |
| DOUT << " -> Deleting dead function: " << Callee->getName() << "\n"; |
| |
| // Remove any call graph edges from the callee to its callees. |
| CallGraphNode *CalleeNode = CG[Callee]; |
| while (!CalleeNode->empty()) |
| CalleeNode->removeCallEdgeTo((CalleeNode->end()-1)->second); |
| |
| // Removing the node for callee from the call graph and delete it. |
| delete CG.removeFunctionFromModule(CalleeNode); |
| ++NumDeleted; |
| } |
| return true; |
| } |
| |
| bool Inliner::runOnSCC(const std::vector<CallGraphNode*> &SCC) { |
| CallGraph &CG = getAnalysis<CallGraph>(); |
| |
| std::set<Function*> SCCFunctions; |
| DOUT << "Inliner visiting SCC:"; |
| for (unsigned i = 0, e = SCC.size(); i != e; ++i) { |
| Function *F = SCC[i]->getFunction(); |
| if (F) SCCFunctions.insert(F); |
| DOUT << " " << (F ? F->getName() : "INDIRECTNODE"); |
| } |
| |
| // Scan through and identify all call sites ahead of time so that we only |
| // inline call sites in the original functions, not call sites that result |
| // from inlining other functions. |
| std::vector<CallSite> CallSites; |
| |
| for (unsigned i = 0, e = SCC.size(); i != e; ++i) |
| if (Function *F = SCC[i]->getFunction()) |
| for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) |
| for (BasicBlock::iterator I = BB->begin(); I != BB->end(); ++I) { |
| CallSite CS = CallSite::get(I); |
| if (CS.getInstruction() && (!CS.getCalledFunction() || |
| !CS.getCalledFunction()->isDeclaration())) |
| CallSites.push_back(CS); |
| } |
| |
| DOUT << ": " << CallSites.size() << " call sites.\n"; |
| |
| // 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].getCalledFunction()) |
| if (SCCFunctions.count(F)) |
| std::swap(CallSites[i--], CallSites[--FirstCallInSCC]); |
| |
| // 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) |
| if (Function *Callee = CallSites[CSi].getCalledFunction()) { |
| // Calls to external functions are never inlinable. |
| if (Callee->isDeclaration() || |
| CallSites[CSi].getInstruction()->getParent()->getParent() ==Callee){ |
| if (SCC.size() == 1) { |
| std::swap(CallSites[CSi], CallSites.back()); |
| CallSites.pop_back(); |
| } else { |
| // Keep the 'in SCC / not in SCC' boundary correct. |
| CallSites.erase(CallSites.begin()+CSi); |
| } |
| --CSi; |
| continue; |
| } |
| |
| // If the policy determines that we should inline this function, |
| // try to do so. |
| CallSite CS = CallSites[CSi]; |
| int InlineCost = getInlineCost(CS); |
| if (InlineCost >= (int)InlineThreshold) { |
| DOUT << " NOT Inlining: cost=" << InlineCost |
| << ", Call: " << *CS.getInstruction(); |
| } else { |
| DOUT << " Inlining: cost=" << InlineCost |
| << ", Call: " << *CS.getInstruction(); |
| |
| // Attempt to inline the function... |
| if (InlineCallIfPossible(CS, CG, SCCFunctions, |
| getAnalysis<TargetData>())) { |
| // 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.size() == 1) { |
| std::swap(CallSites[CSi], CallSites.back()); |
| CallSites.pop_back(); |
| } else { |
| CallSites.erase(CallSites.begin()+CSi); |
| } |
| --CSi; |
| |
| ++NumInlined; |
| 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) { |
| std::set<CallGraphNode*> 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; |
| if (Function *F = CGN ? CGN->getFunction() : 0) { |
| // If the only remaining users of the function are dead constants, remove |
| // them. |
| F->removeDeadConstantUsers(); |
| |
| if ((F->hasLinkOnceLinkage() || F->hasInternalLinkage()) && |
| F->use_empty()) { |
| |
| // Remove any call graph edges from the function to its callees. |
| while (!CGN->empty()) |
| CGN->removeCallEdgeTo((CGN->end()-1)->second); |
| |
| // 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.insert(CGN); |
| } |
| } |
| } |
| |
| // 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. :( |
| bool Changed = false; |
| for (std::set<CallGraphNode*>::iterator I = FunctionsToRemove.begin(), |
| E = FunctionsToRemove.end(); I != E; ++I) { |
| delete CG.removeFunctionFromModule(*I); |
| ++NumDeleted; |
| Changed = true; |
| } |
| |
| return Changed; |
| } |