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This patch implements ProfileDataLoader which loads profile data generated by -insert-edge-profiling and updates branch weight metadata accordingly. Patch by Alastair Murray. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162799 91177308-0d34-0410-b5e6-96231b3b80d8
189 lines
7.1 KiB
C++
189 lines
7.1 KiB
C++
//===- ProfileDataLoaderPass.cpp - Set branch weight metadata from prof ---===//
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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 pass loads profiling data from a dump file and sets branch weight
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// metadata.
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//
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// TODO: Replace all "profile-metadata-loader" strings with "profile-loader"
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// once ProfileInfo etc. has been removed.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "profile-metadata-loader"
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#include "llvm/BasicBlock.h"
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#include "llvm/InstrTypes.h"
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#include "llvm/Module.h"
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#include "llvm/LLVMContext.h"
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#include "llvm/MDBuilder.h"
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#include "llvm/Metadata.h"
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#include "llvm/Pass.h"
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#include "llvm/Analysis/Passes.h"
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#include "llvm/Analysis/ProfileDataLoader.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/CFG.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/Support/Format.h"
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#include "llvm/ADT/Statistic.h"
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#include <vector>
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using namespace llvm;
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STATISTIC(NumEdgesRead, "The # of edges read.");
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STATISTIC(NumTermsAnnotated, "The # of terminator instructions annotated.");
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static cl::opt<std::string>
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ProfileMetadataFilename("profile-file", cl::init("llvmprof.out"),
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cl::value_desc("filename"),
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cl::desc("Profile file loaded by -profile-metadata-loader"));
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namespace {
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/// This pass loads profiling data from a dump file and sets branch weight
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/// metadata.
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class ProfileMetadataLoaderPass : public ModulePass {
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std::string Filename;
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public:
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static char ID; // Class identification, replacement for typeinfo
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explicit ProfileMetadataLoaderPass(const std::string &filename = "")
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: ModulePass(ID), Filename(filename) {
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initializeProfileMetadataLoaderPassPass(*PassRegistry::getPassRegistry());
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if (filename.empty()) Filename = ProfileMetadataFilename;
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}
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.setPreservesAll();
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}
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virtual const char *getPassName() const {
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return "Profile loader";
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}
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virtual void readEdge(unsigned, ProfileData&, ProfileData::Edge,
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std::vector<unsigned>&);
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virtual unsigned matchEdges(Module&, ProfileData&, std::vector<unsigned>&);
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virtual void setBranchWeightMetadata(Module&, ProfileData&);
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virtual bool runOnModule(Module &M);
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};
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} // End of anonymous namespace
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char ProfileMetadataLoaderPass::ID = 0;
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INITIALIZE_PASS_BEGIN(ProfileMetadataLoaderPass, "profile-metadata-loader",
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"Load profile information from llvmprof.out", false, true)
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INITIALIZE_PASS_END(ProfileMetadataLoaderPass, "profile-metadata-loader",
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"Load profile information from llvmprof.out", false, true)
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char &llvm::ProfileMetadataLoaderPassID = ProfileMetadataLoaderPass::ID;
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/// createProfileMetadataLoaderPass - This function returns a Pass that loads
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/// the profiling information for the module from the specified filename,
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/// making it available to the optimizers.
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ModulePass *llvm::createProfileMetadataLoaderPass() {
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return new ProfileMetadataLoaderPass();
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}
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ModulePass *llvm::createProfileMetadataLoaderPass(const std::string &Filename) {
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return new ProfileMetadataLoaderPass(Filename);
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}
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/// readEdge - Take the value from a profile counter and assign it to an edge.
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void ProfileMetadataLoaderPass::readEdge(unsigned ReadCount,
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ProfileData &PB, ProfileData::Edge e,
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std::vector<unsigned> &Counters) {
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if (ReadCount < Counters.size()) {
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unsigned weight = Counters[ReadCount];
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assert(weight != ProfileDataLoader::Uncounted);
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PB.addEdgeWeight(e, weight);
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DEBUG(dbgs() << "-- Read Edge Counter for " << e
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<< " (# "<< (ReadCount) << "): "
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<< PB.getEdgeWeight(e) << "\n");
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}
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}
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/// matchEdges - Link every profile counter with an edge.
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unsigned ProfileMetadataLoaderPass::matchEdges(Module &M, ProfileData &PB,
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std::vector<unsigned> &Counters) {
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if (Counters.size() == 0) return 0;
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unsigned ReadCount = 0;
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for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
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if (F->isDeclaration()) continue;
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DEBUG(dbgs() << "Loading edges in '" << F->getName() << "'\n");
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readEdge(ReadCount++, PB, PB.getEdge(0, &F->getEntryBlock()), Counters);
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for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
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TerminatorInst *TI = BB->getTerminator();
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for (unsigned s = 0, e = TI->getNumSuccessors(); s != e; ++s) {
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readEdge(ReadCount++, PB, PB.getEdge(BB,TI->getSuccessor(s)),
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Counters);
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}
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}
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}
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return ReadCount;
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}
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/// setBranchWeightMetadata - Translate the counter values associated with each
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/// edge into branch weights for each conditional branch (a branch with 2 or
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/// more desinations).
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void ProfileMetadataLoaderPass::setBranchWeightMetadata(Module &M,
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ProfileData &PB) {
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for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
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if (F->isDeclaration()) continue;
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DEBUG(dbgs() << "Setting branch metadata in '" << F->getName() << "'\n");
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for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
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TerminatorInst *TI = BB->getTerminator();
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unsigned NumSuccessors = TI->getNumSuccessors();
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// If there is only one successor then we can not set a branch
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// probability as the target is certain.
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if (NumSuccessors < 2) continue;
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// Load the weights of all edges leading from this terminator.
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DEBUG(dbgs() << "-- Terminator with " << NumSuccessors
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<< " successors:\n");
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std::vector<uint32_t> Weights(NumSuccessors);
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for (unsigned s = 0 ; s < NumSuccessors ; ++s) {
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ProfileData::Edge edge = PB.getEdge(BB, TI->getSuccessor(s));
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Weights[s] = (uint32_t)PB.getEdgeWeight(edge);
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DEBUG(dbgs() << "---- Edge '" << edge << "' has weight "
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<< Weights[s] << "\n");
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}
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// Set branch weight metadata. This will set branch probabilities of
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// 100%/0% if that is true of the dynamic execution.
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// BranchProbabilityInfo can account for this when it loads this metadata
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// (it gives the unexectuted branch a weight of 1 for the purposes of
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// probability calculations).
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MDBuilder MDB(TI->getContext());
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MDNode *Node = MDB.createBranchWeights(Weights);
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TI->setMetadata(LLVMContext::MD_prof, Node);
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NumTermsAnnotated++;
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}
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}
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}
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bool ProfileMetadataLoaderPass::runOnModule(Module &M) {
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ProfileDataLoader PDL("profile-data-loader", Filename);
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ProfileData PB;
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std::vector<unsigned> Counters = PDL.getRawEdgeCounts();
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unsigned ReadCount = matchEdges(M, PB, Counters);
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if (ReadCount != Counters.size()) {
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errs() << "WARNING: profile information is inconsistent with "
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<< "the current program!\n";
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}
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NumEdgesRead = ReadCount;
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setBranchWeightMetadata(M, PB);
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return ReadCount > 0;
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}
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