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Diffstat (limited to 'contrib/llvm/lib/Analysis/ProfileDataLoaderPass.cpp')
-rw-r--r-- | contrib/llvm/lib/Analysis/ProfileDataLoaderPass.cpp | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Analysis/ProfileDataLoaderPass.cpp b/contrib/llvm/lib/Analysis/ProfileDataLoaderPass.cpp new file mode 100644 index 0000000..2ee0093 --- /dev/null +++ b/contrib/llvm/lib/Analysis/ProfileDataLoaderPass.cpp @@ -0,0 +1,188 @@ +//===- ProfileDataLoaderPass.cpp - Set branch weight metadata from prof ---===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This pass loads profiling data from a dump file and sets branch weight +// metadata. +// +// TODO: Replace all "profile-metadata-loader" strings with "profile-loader" +// once ProfileInfo etc. has been removed. +// +//===----------------------------------------------------------------------===// +#define DEBUG_TYPE "profile-metadata-loader" +#include "llvm/Analysis/Passes.h" +#include "llvm/ADT/ArrayRef.h" +#include "llvm/ADT/Statistic.h" +#include "llvm/Analysis/ProfileDataLoader.h" +#include "llvm/IR/BasicBlock.h" +#include "llvm/IR/InstrTypes.h" +#include "llvm/IR/LLVMContext.h" +#include "llvm/IR/MDBuilder.h" +#include "llvm/IR/Metadata.h" +#include "llvm/IR/Module.h" +#include "llvm/Pass.h" +#include "llvm/Support/CFG.h" +#include "llvm/Support/CommandLine.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/Format.h" +#include "llvm/Support/raw_ostream.h" +using namespace llvm; + +STATISTIC(NumEdgesRead, "The # of edges read."); +STATISTIC(NumTermsAnnotated, "The # of terminator instructions annotated."); + +static cl::opt<std::string> +ProfileMetadataFilename("profile-file", cl::init("llvmprof.out"), + cl::value_desc("filename"), + cl::desc("Profile file loaded by -profile-metadata-loader")); + +namespace { + /// This pass loads profiling data from a dump file and sets branch weight + /// metadata. + class ProfileMetadataLoaderPass : public ModulePass { + std::string Filename; + public: + static char ID; // Class identification, replacement for typeinfo + explicit ProfileMetadataLoaderPass(const std::string &filename = "") + : ModulePass(ID), Filename(filename) { + initializeProfileMetadataLoaderPassPass(*PassRegistry::getPassRegistry()); + if (filename.empty()) Filename = ProfileMetadataFilename; + } + + virtual void getAnalysisUsage(AnalysisUsage &AU) const { + AU.setPreservesAll(); + } + + virtual const char *getPassName() const { + return "Profile loader"; + } + + virtual void readEdge(unsigned, ProfileData&, ProfileData::Edge, + ArrayRef<unsigned>); + virtual unsigned matchEdges(Module&, ProfileData&, ArrayRef<unsigned>); + virtual void setBranchWeightMetadata(Module&, ProfileData&); + + virtual bool runOnModule(Module &M); + }; +} // End of anonymous namespace + +char ProfileMetadataLoaderPass::ID = 0; +INITIALIZE_PASS_BEGIN(ProfileMetadataLoaderPass, "profile-metadata-loader", + "Load profile information from llvmprof.out", false, true) +INITIALIZE_PASS_END(ProfileMetadataLoaderPass, "profile-metadata-loader", + "Load profile information from llvmprof.out", false, true) + +char &llvm::ProfileMetadataLoaderPassID = ProfileMetadataLoaderPass::ID; + +/// createProfileMetadataLoaderPass - This function returns a Pass that loads +/// the profiling information for the module from the specified filename, +/// making it available to the optimizers. +ModulePass *llvm::createProfileMetadataLoaderPass() { + return new ProfileMetadataLoaderPass(); +} +ModulePass *llvm::createProfileMetadataLoaderPass(const std::string &Filename) { + return new ProfileMetadataLoaderPass(Filename); +} + +/// readEdge - Take the value from a profile counter and assign it to an edge. +void ProfileMetadataLoaderPass::readEdge(unsigned ReadCount, + ProfileData &PB, ProfileData::Edge e, + ArrayRef<unsigned> Counters) { + if (ReadCount >= Counters.size()) return; + + unsigned weight = Counters[ReadCount]; + assert(weight != ProfileDataLoader::Uncounted); + PB.addEdgeWeight(e, weight); + + DEBUG(dbgs() << "-- Read Edge Counter for " << e + << " (# "<< (ReadCount) << "): " + << PB.getEdgeWeight(e) << "\n"); +} + +/// matchEdges - Link every profile counter with an edge. +unsigned ProfileMetadataLoaderPass::matchEdges(Module &M, ProfileData &PB, + ArrayRef<unsigned> Counters) { + if (Counters.size() == 0) return 0; + + unsigned ReadCount = 0; + + for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) { + if (F->isDeclaration()) continue; + DEBUG(dbgs() << "Loading edges in '" << F->getName() << "'\n"); + readEdge(ReadCount++, PB, PB.getEdge(0, &F->getEntryBlock()), Counters); + for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) { + TerminatorInst *TI = BB->getTerminator(); + for (unsigned s = 0, e = TI->getNumSuccessors(); s != e; ++s) { + readEdge(ReadCount++, PB, PB.getEdge(BB,TI->getSuccessor(s)), + Counters); + } + } + } + + return ReadCount; +} + +/// setBranchWeightMetadata - Translate the counter values associated with each +/// edge into branch weights for each conditional branch (a branch with 2 or +/// more desinations). +void ProfileMetadataLoaderPass::setBranchWeightMetadata(Module &M, + ProfileData &PB) { + for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) { + if (F->isDeclaration()) continue; + DEBUG(dbgs() << "Setting branch metadata in '" << F->getName() << "'\n"); + + for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) { + TerminatorInst *TI = BB->getTerminator(); + unsigned NumSuccessors = TI->getNumSuccessors(); + + // If there is only one successor then we can not set a branch + // probability as the target is certain. + if (NumSuccessors < 2) continue; + + // Load the weights of all edges leading from this terminator. + DEBUG(dbgs() << "-- Terminator with " << NumSuccessors + << " successors:\n"); + SmallVector<uint32_t, 4> Weights(NumSuccessors); + for (unsigned s = 0 ; s < NumSuccessors ; ++s) { + ProfileData::Edge edge = PB.getEdge(BB, TI->getSuccessor(s)); + Weights[s] = (uint32_t)PB.getEdgeWeight(edge); + DEBUG(dbgs() << "---- Edge '" << edge << "' has weight " + << Weights[s] << "\n"); + } + + // Set branch weight metadata. This will set branch probabilities of + // 100%/0% if that is true of the dynamic execution. + // BranchProbabilityInfo can account for this when it loads this metadata + // (it gives the unexectuted branch a weight of 1 for the purposes of + // probability calculations). + MDBuilder MDB(TI->getContext()); + MDNode *Node = MDB.createBranchWeights(Weights); + TI->setMetadata(LLVMContext::MD_prof, Node); + NumTermsAnnotated++; + } + } +} + +bool ProfileMetadataLoaderPass::runOnModule(Module &M) { + ProfileDataLoader PDL("profile-data-loader", Filename); + ProfileData PB; + + ArrayRef<unsigned> Counters = PDL.getRawEdgeCounts(); + + unsigned ReadCount = matchEdges(M, PB, Counters); + + if (ReadCount != Counters.size()) { + errs() << "WARNING: profile information is inconsistent with " + << "the current program!\n"; + } + NumEdgesRead = ReadCount; + + setBranchWeightMetadata(M, PB); + + return ReadCount > 0; +} |