Fix a bogus srem rule - a negative value srem'd by a power-of-2

can have a non-negative result; for example, -16%16 is 0. Also,
clarify the related comments. This fixes PR2670.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@54767 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 0 insertions, 3 deletions

diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index bdea6e40d2..74b88b9afc 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -1266,11 +1266,8 @@ bool InstCombiner::SimplifyDemandedBits(Value *V, APInt DemandedMask,
 
         if (LHSKnownZero[BitWidth-1] || ((LHSKnownZero & LowBits) == LowBits))
           LHSKnownZero |= ~LowBits;
-        else if (LHSKnownOne[BitWidth-1])
-          LHSKnownOne |= ~LowBits;
 
         KnownZero |= LHSKnownZero & DemandedMask;
-        KnownOne |= LHSKnownOne & DemandedMask;
 
         assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?"); 
       }