From 941aa7b1e8c1b77544d643e8b23ff07f7f83f281 Mon Sep 17 00:00:00 2001 From: Chandler Carruth Date: Wed, 19 Oct 2011 10:32:19 +0000 Subject: Generalize the reading of probability metadata to work for both branches and switches, with arbitrary numbers of successors. Still optimized for the common case of 2 successors for a conditional branch. Add a test case for switch metadata showing up in the BlockFrequencyInfo pass. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142493 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Analysis/BranchProbabilityInfo.cpp | 40 ++++++++++++++++++++-------------- 1 file changed, 24 insertions(+), 16 deletions(-) (limited to 'lib/Analysis') diff --git a/lib/Analysis/BranchProbabilityInfo.cpp b/lib/Analysis/BranchProbabilityInfo.cpp index 70de3d1c49..52090c9fc1 100644 --- a/lib/Analysis/BranchProbabilityInfo.cpp +++ b/lib/Analysis/BranchProbabilityInfo.cpp @@ -140,30 +140,38 @@ public: // Propagate existing explicit probabilities from either profile data or // 'expect' intrinsic processing. -// FIXME: This doesn't correctly extract probabilities for switches. bool BranchProbabilityAnalysis::calcMetadataWeights(BasicBlock *BB) { - BranchInst *BI = dyn_cast(BB->getTerminator()); - if (!BI || !BI->isConditional()) + TerminatorInst *TI = BB->getTerminator(); + if (TI->getNumSuccessors() == 1) + return false; + if (!isa(TI) && !isa(TI)) return false; - MDNode *WeightsNode = BI->getMetadata(LLVMContext::MD_prof); - if (!WeightsNode || WeightsNode->getNumOperands() < 3) + MDNode *WeightsNode = TI->getMetadata(LLVMContext::MD_prof); + if (!WeightsNode) return false; - // Pull the weights out of the metadata. Note that the zero operand is the - // name. - ConstantInt *Weights[] = { - dyn_cast(WeightsNode->getOperand(1)), - dyn_cast(WeightsNode->getOperand(2)) - }; - if (!Weights[0] || !Weights[1]) + // Ensure there are weights for all of the successors. Note that the first + // operand to the metadata node is a name, not a weight. + if (WeightsNode->getNumOperands() != TI->getNumSuccessors() + 1) return false; + // Build up the final weights that will be used in a temporary buffer, but + // don't add them until all weihts are present. Each weight value is clamped + // to [1, getMaxWeightFor(BB)]. uint32_t WeightLimit = getMaxWeightFor(BB); - BP->setEdgeWeight(BB, BI->getSuccessor(0), - Weights[0]->getLimitedValue(WeightLimit)); - BP->setEdgeWeight(BB, BI->getSuccessor(1), - Weights[1]->getLimitedValue(WeightLimit)); + SmallVector Weights; + Weights.reserve(TI->getNumSuccessors()); + for (unsigned i = 1, e = WeightsNode->getNumOperands(); i != e; ++i) { + ConstantInt *Weight = dyn_cast(WeightsNode->getOperand(i)); + if (!Weight) + return false; + Weights.push_back( + std::max(1, Weight->getLimitedValue(WeightLimit))); + } + assert(Weights.size() == TI->getNumSuccessors() && "Checked above"); + for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i) + BP->setEdgeWeight(BB, TI->getSuccessor(i), Weights[i]); return true; } -- cgit v1.2.3