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Implement comparison operators for BranchProbability in a way that can't overflow INT64_MAX.

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Add a test case for the edge case that triggers this. Thanks to Chandler for bringing this to my attention.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142794 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Benjamin Kramer
2011-10-24 13:50:56 +00:00
parent de1c9bb450
commit 13b10731ab
2 changed files with 27 additions and 10 deletions
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28
include/llvm/Support/BranchProbability.h
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@@ -29,10 +29,6 @@ class BranchProbability {
// Denominator
uint32_t D;
int64_t compare(BranchProbability RHS) const {
return (uint64_t)N * RHS.D - (uint64_t)D * RHS.N;
}
public:
BranchProbability(uint32_t n, uint32_t d) : N(n), D(d) {
assert(d > 0 && "Denomiator cannot be 0!");
@@ -54,12 +50,24 @@ public:
void dump() const;
bool operator==(BranchProbability RHS) const { return compare(RHS) == 0; }
bool operator!=(BranchProbability RHS) const { return compare(RHS) != 0; }
bool operator< (BranchProbability RHS) const { return compare(RHS) < 0; }
bool operator> (BranchProbability RHS) const { return compare(RHS) > 0; }
bool operator<=(BranchProbability RHS) const { return compare(RHS) <= 0; }
bool operator>=(BranchProbability RHS) const { return compare(RHS) >= 0; }
bool operator==(BranchProbability RHS) const {
return (uint64_t)N * RHS.D == (uint64_t)D * RHS.N;
}
bool operator!=(BranchProbability RHS) const {
return !(*this == RHS);
}
bool operator<(BranchProbability RHS) const {
return (uint64_t)N * RHS.D < (uint64_t)D * RHS.N;
}
bool operator>(BranchProbability RHS) const {
return RHS < *this;
}
bool operator<=(BranchProbability RHS) const {
return (uint64_t)N * RHS.D <= (uint64_t)D * RHS.N;
}
bool operator>=(BranchProbability RHS) const {
return RHS <= *this;
}
};
raw_ostream &operator<<(raw_ostream &OS, const BranchProbability &Prob);