Changes in directory llvm/lib/Transforms/Scalar:
InstructionCombining.cpp updated: 1.660 -> 1.661 --- Log message: ShiftAmt might equal to zero. Handle this situation. --- Diffs of the changes: (+9 -7) InstructionCombining.cpp | 16 +++++++++------- 1 files changed, 9 insertions(+), 7 deletions(-) Index: llvm/lib/Transforms/Scalar/InstructionCombining.cpp diff -u llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.660 llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.661 --- llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.660 Tue Mar 13 22:21:24 2007 +++ llvm/lib/Transforms/Scalar/InstructionCombining.cpp Wed Mar 14 04:07:33 2007 @@ -1997,7 +1997,8 @@ RHSKnownZero <<= ShiftAmt; RHSKnownOne <<= ShiftAmt; // low bits known zero. - RHSKnownZero |= APInt::getAllOnesValue(ShiftAmt).zextOrCopy(BitWidth); + if (ShiftAmt) + RHSKnownZero |= APInt::getAllOnesValue(ShiftAmt).zextOrCopy(BitWidth); } break; case Instruction::LShr: @@ -2013,14 +2014,16 @@ return true; assert((RHSKnownZero & RHSKnownOne) == 0 && "Bits known to be one AND zero?"); - // Compute the new bits that are at the top now. - APInt HighBits(APInt::getAllOnesValue(ShiftAmt).zextOrCopy(BitWidth).shl( - BitWidth - ShiftAmt)); RHSKnownZero &= TypeMask; RHSKnownOne &= TypeMask; RHSKnownZero = APIntOps::lshr(RHSKnownZero, ShiftAmt); RHSKnownOne = APIntOps::lshr(RHSKnownOne, ShiftAmt); - RHSKnownZero |= HighBits; // high bits known zero. + if (ShiftAmt) { + // Compute the new bits that are at the top now. + APInt HighBits(APInt::getAllOnesValue(BitWidth).shl( + BitWidth - ShiftAmt)); + RHSKnownZero |= HighBits; // high bits known zero. + } } break; case Instruction::AShr: @@ -2048,8 +2051,7 @@ assert((RHSKnownZero & RHSKnownOne) == 0 && "Bits known to be one AND zero?"); // Compute the new bits that are at the top now. - APInt HighBits(APInt::getAllOnesValue(ShiftAmt).zextOrCopy(BitWidth).shl( - BitWidth - ShiftAmt)); + APInt HighBits(APInt::getAllOnesValue(BitWidth).shl(BitWidth - ShiftAmt)); RHSKnownZero &= TypeMask; RHSKnownOne &= TypeMask; RHSKnownZero = APIntOps::lshr(RHSKnownZero, ShiftAmt); _______________________________________________ llvm-commits mailing list llvm-commits@cs.uiuc.edu http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits