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| author | Bill Wendling <isanbard@gmail.com> | 2012-04-30 17:09:46 +0000 |
|---|---|---|
| committer | Bill Wendling <isanbard@gmail.com> | 2012-04-30 17:09:46 +0000 |
| commit | 55f951325943a719478d625eb4271adb817fde7d (patch) | |
| tree | a8733273ac414c3efbd91d12f63d02d92a34c134 | |
| parent | 8d1440d0217ab3b09a407c42f7559ad641c7077f (diff) | |
Merging r155818:
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r155818 | baldrick | 2012-04-30 04:56:58 -0700 (Mon, 30 Apr 2012) | 3 lines
Just mark the sign bit as known zero, rather than any other irrelevant bits
known zero in the LHS. Fixes PR12541.
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_31@155827 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/Analysis/ValueTracking.cpp | 2 | ||||
| -rw-r--r-- | test/Transforms/InstCombine/2012-04-30-SRem.ll | 12 |
2 files changed, 13 insertions, 1 deletions
diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp index a430f6281e..1418e01d7c 100644 --- a/lib/Analysis/ValueTracking.cpp +++ b/lib/Analysis/ValueTracking.cpp @@ -564,7 +564,7 @@ void llvm::ComputeMaskedBits(Value *V, APInt &KnownZero, APInt &KnownOne, Depth+1); // If it's known zero, our sign bit is also zero. if (LHSKnownZero.isNegative()) - KnownZero |= LHSKnownZero; + KnownZero.setBit(BitWidth - 1); } break; diff --git a/test/Transforms/InstCombine/2012-04-30-SRem.ll b/test/Transforms/InstCombine/2012-04-30-SRem.ll new file mode 100644 index 0000000000..a285d5aea5 --- /dev/null +++ b/test/Transforms/InstCombine/2012-04-30-SRem.ll @@ -0,0 +1,12 @@ +; RUN: opt -instcombine -S < %s | FileCheck %s +; PR12541 + +define i32 @foo(i32 %x) { + %y = xor i32 %x, 3 + %z = srem i32 1656690544, %y + %sext = shl i32 %z, 24 + %s = ashr exact i32 %sext, 24 + ret i32 %s +; CHECK-NOT: and +; The shifts were wrongly being turned into an and with 112 +} |