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author | Benjamin Kramer <benny.kra@googlemail.com> | 2011-10-24 13:50:56 +0000 |
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committer | Benjamin Kramer <benny.kra@googlemail.com> | 2011-10-24 13:50:56 +0000 |
commit | 13b10731abfc006fce790c5c8205cd24c7d67de8 (patch) | |
tree | eb1a73b00a86c6246051239c5e58c7cb28c6b5ac | |
parent | de1c9bb45017e25b5fc2b77e15d3c377f6572075 (diff) | |
download | external_llvm-13b10731abfc006fce790c5c8205cd24c7d67de8.zip external_llvm-13b10731abfc006fce790c5c8205cd24c7d67de8.tar.gz external_llvm-13b10731abfc006fce790c5c8205cd24c7d67de8.tar.bz2 |
Implement comparison operators for BranchProbability in a way that can't overflow INT64_MAX.
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
-rw-r--r-- | include/llvm/Support/BranchProbability.h | 28 | ||||
-rw-r--r-- | unittests/Support/BlockFrequencyTest.cpp | 9 |
2 files changed, 27 insertions, 10 deletions
diff --git a/include/llvm/Support/BranchProbability.h b/include/llvm/Support/BranchProbability.h index 6b83159..4b5d904 100644 --- a/include/llvm/Support/BranchProbability.h +++ b/include/llvm/Support/BranchProbability.h @@ -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); diff --git a/unittests/Support/BlockFrequencyTest.cpp b/unittests/Support/BlockFrequencyTest.cpp index ac3cedf..df25642 100644 --- a/unittests/Support/BlockFrequencyTest.cpp +++ b/unittests/Support/BlockFrequencyTest.cpp @@ -71,6 +71,15 @@ TEST(BlockFrequencyTest, ProbabilityCompare) { EXPECT_TRUE(B > C); EXPECT_FALSE(B <= C); EXPECT_TRUE(B >= C); + + BranchProbability BigZero(0, UINT32_MAX); + BranchProbability BigOne(UINT32_MAX, UINT32_MAX); + EXPECT_FALSE(BigZero == BigOne); + EXPECT_TRUE(BigZero != BigOne); + EXPECT_TRUE(BigZero < BigOne); + EXPECT_FALSE(BigZero > BigOne); + EXPECT_TRUE(BigZero <= BigOne); + EXPECT_FALSE(BigZero >= BigOne); } } |