diff options
| -rw-r--r-- | lib/Support/BlockFrequency.cpp | 6 | ||||
| -rw-r--r-- | unittests/Support/BlockFrequencyTest.cpp | 5 |
2 files changed, 7 insertions, 4 deletions
diff --git a/lib/Support/BlockFrequency.cpp b/lib/Support/BlockFrequency.cpp index 8de517fad6..5e45e46cf9 100644 --- a/lib/Support/BlockFrequency.cpp +++ b/lib/Support/BlockFrequency.cpp @@ -47,9 +47,7 @@ static uint64_t div96bit(uint64_t W[2], uint32_t D) { uint64_t x = W[1]; unsigned i; - // This is really a 64-bit division. - if (!x) - return y / D; + assert(x != 0 && "This is really a 64-bit division"); // This long division algorithm automatically saturates on overflow. for (i = 0; i < 64 && x; ++i) { @@ -75,7 +73,7 @@ void BlockFrequency::scale(uint32_t N, uint32_t D) { uint64_t MulRes = (MulHi << 32) + MulLo; // If the product fits in 64 bits, just use built-in division. - if (MulHi <= UINT32_MAX && MulRes <= MulLo) { + if (MulHi <= UINT32_MAX && MulRes >= MulLo) { Frequency = MulRes / D; return; } diff --git a/unittests/Support/BlockFrequencyTest.cpp b/unittests/Support/BlockFrequencyTest.cpp index 4bcddfebd9..ca420fccaa 100644 --- a/unittests/Support/BlockFrequencyTest.cpp +++ b/unittests/Support/BlockFrequencyTest.cpp @@ -68,6 +68,11 @@ TEST(BlockFrequencyTest, Saturate) { Freq = 0x1000000000000000ULL; Freq /= BranchProbability(10000, 160000); EXPECT_EQ(Freq.getFrequency(), UINT64_MAX); + + // Try to cheat the multiplication overflow check. + Freq = 0x00000001f0000001ull; + Freq /= BranchProbability(1000, 0xf000000f); + EXPECT_EQ(33506781356485509ULL, Freq.getFrequency()); } TEST(BlockFrequencyTest, ProbabilityCompare) { |