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//===- 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;
}
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