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author | NAKAMURA Takumi <geek4civic@gmail.com> | 2012-12-13 14:28:16 +0000 |
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committer | NAKAMURA Takumi <geek4civic@gmail.com> | 2012-12-13 14:28:16 +0000 |
commit | bb9004e0dcef07ef7538784e46bbdd3cb3789d24 (patch) | |
tree | 61ea6a8a09409e74a6b1d24ad7efc61664d97356 /lib/Transforms/InstCombine/InstCombineCompares.cpp | |
parent | dbabd5acad7f2b483f12469648cab2d3445b90e2 (diff) | |
download | external_llvm-bb9004e0dcef07ef7538784e46bbdd3cb3789d24.zip external_llvm-bb9004e0dcef07ef7538784e46bbdd3cb3789d24.tar.gz external_llvm-bb9004e0dcef07ef7538784e46bbdd3cb3789d24.tar.bz2 |
Revert r170020, "Simplify negated bit test", for now.
This assumes (1 << n) is always not zero. Consider n is greater than word size.
Although I know it is undefined, this transforms undefined behavior hidden.
This led clang unexpected behavior with some failures. I will investigate to fix undefined shl in clang.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@170128 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Transforms/InstCombine/InstCombineCompares.cpp')
-rw-r--r-- | lib/Transforms/InstCombine/InstCombineCompares.cpp | 18 |
1 files changed, 0 insertions, 18 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp index 00807a3..1b96c3c 100644 --- a/lib/Transforms/InstCombine/InstCombineCompares.cpp +++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp @@ -2034,15 +2034,6 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) { CI->countTrailingZeros())); } - // Turn x&~y == 0 into x&y != 0 if x is a power of 2. - Value *X = 0, *Y = 0; - if (match(Op0, m_And(m_Value(X), m_Not(m_Value(Y)))) && - match(Op1, m_Zero()) && isKnownToBeAPowerOfTwo(X, TD)) { - return new ICmpInst(ICmpInst::ICMP_NE, - Builder->CreateAnd(X, Y), - Op1); - } - break; } case ICmpInst::ICMP_NE: { @@ -2080,15 +2071,6 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) { CI->countTrailingZeros())); } - // Turn x&~y != 0 into x&y == 0 if x is a power of 2. - Value *X = 0, *Y = 0; - if (match(Op0, m_And(m_Value(X), m_Not(m_Value(Y)))) && - match(Op1, m_Zero()) && isKnownToBeAPowerOfTwo(X, TD)) { - return new ICmpInst(ICmpInst::ICMP_EQ, - Builder->CreateAnd(X, Y), - Op1); - } - break; } case ICmpInst::ICMP_ULT: |