diff options
Diffstat (limited to 'llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp')
| -rw-r--r-- | llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp | 26 |
1 files changed, 15 insertions, 11 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp index 24ab65171a1..368e2100031 100644 --- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp @@ -5490,9 +5490,20 @@ char TargetLowering::isNegatibleForFree(SDValue Op, SelectionDAG &DAG, EVT VT = Op.getValueType(); const SDNodeFlags Flags = Op->getFlags(); const TargetOptions &Options = DAG.getTarget().Options; - if (!Op.hasOneUse() && !(Op.getOpcode() == ISD::FP_EXTEND && - isFPExtFree(VT, Op.getOperand(0).getValueType()))) - return 0; + if (!Op.hasOneUse()) { + bool IsFreeExtend = Op.getOpcode() == ISD::FP_EXTEND && + isFPExtFree(VT, Op.getOperand(0).getValueType()); + + // If we already have the use of the negated floating constant, it is free + // to negate it even it has multiple uses. + bool IsFreeConstant = + Op.getOpcode() == ISD::ConstantFP && + !getNegatedExpression(Op, DAG, LegalOperations, ForCodeSize) + .use_empty(); + + if (!IsFreeExtend && !IsFreeConstant) + return 0; + } // Don't recurse exponentially. if (Depth > SelectionDAG::MaxRecursionDepth) @@ -5687,14 +5698,7 @@ SDValue TargetLowering::getNegatedExpression(SDValue Op, SelectionDAG &DAG, ForCodeSize, Depth + 1); char V1 = isNegatibleForFree(Op.getOperand(1), DAG, LegalOperations, ForCodeSize, Depth + 1); - // TODO: This is a hack. It is possible that costs have changed between now - // and the initial calls to isNegatibleForFree(). That is because we - // are rewriting the expression, and that may change the number of - // uses (and therefore the cost) of values. If the negation costs are - // equal, only negate this value if it is a constant. Otherwise, try - // operand 1. A better fix would eliminate uses as a cost factor or - // track the change in uses as we rewrite the expression. - if (V0 > V1 || (V0 == V1 && isa<ConstantFPSDNode>(Op.getOperand(0)))) { + if (V0 > V1) { // fold (fneg (fma X, Y, Z)) -> (fma (fneg X), Y, (fneg Z)) SDValue Neg0 = getNegatedExpression( Op.getOperand(0), DAG, LegalOperations, ForCodeSize, Depth + 1); |
