From a4bd1463c8dc04bcd9befd49a667dbfd7fec0f87 Mon Sep 17 00:00:00 2001 From: Vedant Kumar Date: Sat, 17 Dec 2016 01:02:08 +0000 Subject: Retry: [BPI] Use a safer constructor to calculate branch probabilities BPI may trigger signed overflow UB while computing branch probabilities for cold calls or to unreachables. For example, with our current choice of weights, we'll crash if there are >= 2^12 branches to an unreachable. Use a safer BranchProbability constructor which is better at handling fractions with large denominators. Changes since the initial commit: - Use explicit casts to ensure that multiplication operands are 64-bit ints. rdar://problem/29368161 Differential Revision: https://reviews.llvm.org/D27862 llvm-svn: 290022 --- llvm/lib/Analysis/BranchProbabilityInfo.cpp | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-) (limited to 'llvm/lib/Analysis/BranchProbabilityInfo.cpp') diff --git a/llvm/lib/Analysis/BranchProbabilityInfo.cpp b/llvm/lib/Analysis/BranchProbabilityInfo.cpp index a91ac8d06fa..3eabb780398 100644 --- a/llvm/lib/Analysis/BranchProbabilityInfo.cpp +++ b/llvm/lib/Analysis/BranchProbabilityInfo.cpp @@ -162,12 +162,12 @@ bool BranchProbabilityInfo::calcUnreachableHeuristics(const BasicBlock *BB) { return true; } - BranchProbability UnreachableProb(UR_TAKEN_WEIGHT, - (UR_TAKEN_WEIGHT + UR_NONTAKEN_WEIGHT) * - UnreachableEdges.size()); - BranchProbability ReachableProb(UR_NONTAKEN_WEIGHT, - (UR_TAKEN_WEIGHT + UR_NONTAKEN_WEIGHT) * - ReachableEdges.size()); + auto UnreachableProb = BranchProbability::getBranchProbability( + UR_TAKEN_WEIGHT, (UR_TAKEN_WEIGHT + UR_NONTAKEN_WEIGHT) * + uint64_t(UnreachableEdges.size())); + auto ReachableProb = BranchProbability::getBranchProbability( + UR_NONTAKEN_WEIGHT, + (UR_TAKEN_WEIGHT + UR_NONTAKEN_WEIGHT) * uint64_t(ReachableEdges.size())); for (unsigned SuccIdx : UnreachableEdges) setEdgeProbability(BB, SuccIdx, UnreachableProb); @@ -300,12 +300,12 @@ bool BranchProbabilityInfo::calcColdCallHeuristics(const BasicBlock *BB) { return true; } - BranchProbability ColdProb(CC_TAKEN_WEIGHT, - (CC_TAKEN_WEIGHT + CC_NONTAKEN_WEIGHT) * - ColdEdges.size()); - BranchProbability NormalProb(CC_NONTAKEN_WEIGHT, - (CC_TAKEN_WEIGHT + CC_NONTAKEN_WEIGHT) * - NormalEdges.size()); + auto ColdProb = BranchProbability::getBranchProbability( + CC_TAKEN_WEIGHT, + (CC_TAKEN_WEIGHT + CC_NONTAKEN_WEIGHT) * uint64_t(ColdEdges.size())); + auto NormalProb = BranchProbability::getBranchProbability( + CC_NONTAKEN_WEIGHT, + (CC_TAKEN_WEIGHT + CC_NONTAKEN_WEIGHT) * uint64_t(NormalEdges.size())); for (unsigned SuccIdx : ColdEdges) setEdgeProbability(BB, SuccIdx, ColdProb); -- cgit v1.2.3