diff options
| author | Dan Gohman <gohman@apple.com> | 2010-12-09 02:52:17 +0000 |
|---|---|---|
| committer | Dan Gohman <gohman@apple.com> | 2010-12-09 02:52:17 +0000 |
| commit | d8e0c0438ab1ec86b2bd42da7a439caa7f0a61eb (patch) | |
| tree | e40cb8e64fcdfcf9e8d257ff9cea52b233d2af89 /lib/Transforms/InstCombine/InstCombineShifts.cpp | |
| parent | 1a48c032bd7c240fc4c52aee6dad57f8043a77d9 (diff) | |
| download | llvm-d8e0c0438ab1ec86b2bd42da7a439caa7f0a61eb.tar.gz llvm-d8e0c0438ab1ec86b2bd42da7a439caa7f0a61eb.tar.bz2 llvm-d8e0c0438ab1ec86b2bd42da7a439caa7f0a61eb.tar.xz | |
Really check that the bits that will become zero are actually already zero
before eliminating the operation that zeros them. This fixes rdar://8739316.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121353 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Transforms/InstCombine/InstCombineShifts.cpp')
| -rw-r--r-- | lib/Transforms/InstCombine/InstCombineShifts.cpp | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineShifts.cpp b/lib/Transforms/InstCombine/InstCombineShifts.cpp index e52f2013fe..e3232a491b 100644 --- a/lib/Transforms/InstCombine/InstCombineShifts.cpp +++ b/lib/Transforms/InstCombine/InstCombineShifts.cpp @@ -168,9 +168,8 @@ static bool CanEvaluateShifted(Value *V, unsigned NumBits, bool isLeftShift, // We can always turn lshr(c1)+shl(c2) -> lshr(c3)+and(c4), but it isn't // profitable unless we know the and'd out bits are already zero. if (CI->getZExtValue() > NumBits) { - unsigned LowBits = CI->getZExtValue() - NumBits; if (MaskedValueIsZero(I->getOperand(0), - APInt::getLowBitsSet(TypeWidth, LowBits) << NumBits)) + APInt::getLowBitsSet(TypeWidth, NumBits))) return true; } |