diff options
| author | Duncan Sands <baldrick@free.fr> | 2011-10-26 20:55:21 +0000 |
|---|---|---|
| committer | Duncan Sands <baldrick@free.fr> | 2011-10-26 20:55:21 +0000 |
| commit | dd3149d57977d0632cfaf24290dd93416fb2a0ef (patch) | |
| tree | 474b791ded4b0b4e186663009e133000d2c45814 /lib/Analysis/InstructionSimplify.cpp | |
| parent | 1832f4d94eb292d63824eaa043118ed6cc61389b (diff) | |
The maximum power of 2 dividing a power of 2 is itself. This occurs
in 403.gcc and was spotted by my super-optimizer.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@143054 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Analysis/InstructionSimplify.cpp')
| -rw-r--r-- | lib/Analysis/InstructionSimplify.cpp | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp index 131cc97d23..d9e3400f89 100644 --- a/lib/Analysis/InstructionSimplify.cpp +++ b/lib/Analysis/InstructionSimplify.cpp @@ -1197,6 +1197,15 @@ static Value *SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD, (A == Op0 || B == Op0)) return Op0; + // A & (-A) = A if A is a power of two or zero. + if (match(Op0, m_Neg(m_Specific(Op1))) || + match(Op1, m_Neg(m_Specific(Op0)))) { + if (isPowerOfTwo(Op0, TD, /*OrZero*/true)) + return Op0; + if (isPowerOfTwo(Op1, TD, /*OrZero*/true)) + return Op1; + } + // Try some generic simplifications for associative operations. if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, TD, DT, MaxRecurse)) |