Changes in directory llvm/lib/Target:
TargetLowering.cpp updated: 1.39 -> 1.40 --- Log message: Check RHS simplification before LHS simplification to avoid infinitely looping on PowerPC/small-arguments.ll --- Diffs of the changes: (+17 -18) TargetLowering.cpp | 35 +++++++++++++++++------------------ 1 files changed, 17 insertions(+), 18 deletions(-) Index: llvm/lib/Target/TargetLowering.cpp diff -u llvm/lib/Target/TargetLowering.cpp:1.39 llvm/lib/Target/TargetLowering.cpp:1.40 --- llvm/lib/Target/TargetLowering.cpp:1.39 Sun Feb 26 18:22:28 2006 +++ llvm/lib/Target/TargetLowering.cpp Sun Feb 26 18:36:27 2006 @@ -201,7 +201,23 @@ KnownZero = ~KnownOne & DemandedMask; return false; // Don't fall through, will infinitely loop. case ISD::AND: - // If either the LHS or the RHS are Zero, the result is zero. + // If the RHS is a constant, check to see if the LHS would be zero without + // using the bits from the RHS. Below, we use knowledge about the RHS to + // simplify the LHS, here we're using information from the LHS to simplify + // the RHS. + if (ConstantSDNode *RHSC = dyn_cast<ConstantSDNode>(Op.getOperand(1))) { + uint64_t LHSZero, LHSOne; + ComputeMaskedBits(Op.getOperand(0), DemandedMask, + LHSZero, LHSOne, Depth+1); + // If the LHS already has zeros where RHSC does, this and is dead. + if ((LHSZero & DemandedMask) == (~RHSC->getValue() & DemandedMask)) + return TLO.CombineTo(Op, Op.getOperand(0)); + // If any of the set bits in the RHS are known zero on the LHS, shrink + // the constant. + if (TLO.ShrinkDemandedConstant(Op, ~LHSZero & DemandedMask)) + return true; + } + if (SimplifyDemandedBits(Op.getOperand(1), DemandedMask, KnownZero, KnownOne, TLO, Depth+1)) return true; @@ -224,23 +240,6 @@ if (TLO.ShrinkDemandedConstant(Op, DemandedMask & ~KnownZero2)) return true; - // If the RHS is a constant, check to see if the LHS would be zero without - // using the bits from the RHS. Above, we used knowledge about the RHS to - // simplify the LHS, here we're using information from the LHS to simplify - // the RHS. - if (ConstantSDNode *RHSC = dyn_cast<ConstantSDNode>(Op.getOperand(1))) { - uint64_t LHSZero, LHSOne; - ComputeMaskedBits(Op.getOperand(0), DemandedMask, - LHSZero, LHSOne, Depth+1); - // If the LHS already has zeros where RHSC does, this and is dead. - if ((LHSZero & DemandedMask) == (~RHSC->getValue() & DemandedMask)) - return TLO.CombineTo(Op, Op.getOperand(0)); - // If any of the set bits in the RHS are known zero on the LHS, shrink - // the constant. - if (TLO.ShrinkDemandedConstant(Op, ~LHSZero & DemandedMask)) - return true; - } - // Output known-1 bits are only known if set in both the LHS & RHS. KnownOne &= KnownOne2; // Output known-0 are known to be clear if zero in either the LHS | RHS. _______________________________________________ llvm-commits mailing list llvm-commits@cs.uiuc.edu http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits