/// 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"); }
/// 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++; } } }