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| author | Benjamin Kramer <benny.kra@googlemail.com> | 2013-06-21 19:30:05 +0000 |
|---|---|---|
| committer | Benjamin Kramer <benny.kra@googlemail.com> | 2013-06-21 19:30:05 +0000 |
| commit | 93702a3b0754052d926c75082abf7ca156b80c45 (patch) | |
| tree | 10b032704125296644321d26cc84d3053da88dc7 /unittests | |
| parent | 65af4b5333f539b9e572ebb9c4d4e97a897e5130 (diff) | |
| download | llvm-93702a3b0754052d926c75082abf7ca156b80c45.tar.gz llvm-93702a3b0754052d926c75082abf7ca156b80c45.tar.bz2 llvm-93702a3b0754052d926c75082abf7ca156b80c45.tar.xz | |
BlockFrequency: Saturate at 1 instead of 0 when multiplying a frequency with a branch probability.
Zero is used by BlockFrequencyInfo as a special "don't know" value. It also
causes a sink for frequencies as you can't ever get off a zero frequency with
more multiplies.
This recovers a 10% regression on MultiSource/Benchmarks/7zip. A zero frequency
was propagated into an inner loop causing excessive spilling.
PR16402.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184584 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'unittests')
| -rw-r--r-- | unittests/Support/BlockFrequencyTest.cpp | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/unittests/Support/BlockFrequencyTest.cpp b/unittests/Support/BlockFrequencyTest.cpp index ff66bc4e45..bcb88c8895 100644 --- a/unittests/Support/BlockFrequencyTest.cpp +++ b/unittests/Support/BlockFrequencyTest.cpp @@ -8,11 +8,22 @@ using namespace llvm; namespace { +TEST(BlockFrequencyTest, ZeroToZero) { + BlockFrequency Freq(0); + BranchProbability Prob(UINT32_MAX - 1, UINT32_MAX); + Freq *= Prob; + EXPECT_EQ(Freq.getFrequency(), 0u); + + Freq = 1; + Freq *= BranchProbability::getZero(); + EXPECT_EQ(Freq.getFrequency(), 0u); +} + TEST(BlockFrequencyTest, OneToZero) { BlockFrequency Freq(1); BranchProbability Prob(UINT32_MAX - 1, UINT32_MAX); Freq *= Prob; - EXPECT_EQ(Freq.getFrequency(), 0u); + EXPECT_EQ(Freq.getFrequency(), 1u); } TEST(BlockFrequencyTest, OneToOne) { |