diff options
Diffstat (limited to 'lib/Transforms')
| -rw-r--r-- | lib/Transforms/Scalar/InstructionCombining.cpp | 20 |
1 files changed, 12 insertions, 8 deletions
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index 5ba48572a5..e56b559971 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -5820,18 +5820,22 @@ Instruction *InstCombiner::visitICmpInstWithCastAndCast(ICmpInst &ICI) { if (RHSCIOp->getType() != LHSCIOp->getType()) return 0; - // If the signedness of the two compares doesn't agree (i.e. one is a sext + // If the signedness of the two casts doesn't agree (i.e. one is a sext // and the other is a zext), then we can't handle this. if (CI->getOpcode() != LHSCI->getOpcode()) return 0; - // Likewise, if the signedness of the [sz]exts and the compare don't match, - // then we can't handle this. - if (isSignedExt != isSignedCmp && !ICI.isEquality()) - return 0; - - // Okay, just insert a compare of the reduced operands now! - return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp); + // Deal with equality cases early. + if (ICI.isEquality()) + return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp); + + // A signed comparison of sign extended values simplifies into a + // signed comparison. + if (isSignedCmp && isSignedExt) + return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp); + + // The other three cases all fold into an unsigned comparison. + return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, RHSCIOp); } // If we aren't dealing with a constant on the RHS, exit early |