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Check the case that the numerator and denominator are both zeros when getting edge probabilities in BPI and return 100% in this case.

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This issue is triggered in PGO mode when bootstrapping LLVM. It seems that it is not guaranteed that edge weights are always greater than zero which are read from profile data.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@251317 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Cong Hou 2015-10-26 18:00:17 +00:00
parent 0cd635f750
commit 2d382f246b
1 changed files with 10 additions and 0 deletions
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10
lib/Analysis/BranchProbabilityInfo.cpp
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@ -623,6 +623,11 @@ getEdgeProbability(const BasicBlock *Src, unsigned IndexInSuccessors) const {
uint32_t N = getEdgeWeight(Src, IndexInSuccessors);
uint32_t D = getSumForBlock(Src);
// It is possible that the edge weight on the only successor edge of Src is
// zero, in which case we return 100%.
if (N == 0 && D == 0)
return BranchProbability::getOne();
return BranchProbability(N, D);
}
@ -634,6 +639,11 @@ getEdgeProbability(const BasicBlock *Src, const BasicBlock *Dst) const {
uint32_t N = getEdgeWeight(Src, Dst);
uint32_t D = getSumForBlock(Src);
// It is possible that the edge weight on the only successor edge of Src is
// zero, in which case we return 100%.
if (N == 0 && D == 0)
return BranchProbability::getOne();
return BranchProbability(N, D);
}