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Add predicates for checking whether targets have free FNEG and FABS operations, and prevent the DAGCombiner from turning them into bitwise operations if they do.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153901 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -1600,6 +1600,18 @@ public:
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return false;
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}
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/// isFNegFree - Return true if an fneg operation is free to the point where
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/// it is never worthwhile to replace it with a bitwise operation.
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virtual bool isFNegFree(EVT) const {
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return false;
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}
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/// isFAbsFree - Return true if an fneg operation is free to the point where
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/// it is never worthwhile to replace it with a bitwise operation.
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virtual bool isFAbsFree(EVT) const {
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return false;
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}
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/// isNarrowingProfitable - Return true if it's profitable to narrow
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/// operations of type VT1 to VT2. e.g. on x86, it's profitable to narrow
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/// from i32 to i8 but not from i32 to i16.
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@ -5342,7 +5342,8 @@ SDValue DAGCombiner::visitBITCAST(SDNode *N) {
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// fold (bitconvert (fneg x)) -> (xor (bitconvert x), signbit)
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// fold (bitconvert (fabs x)) -> (and (bitconvert x), (not signbit))
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// This often reduces constant pool loads.
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if ((N0.getOpcode() == ISD::FNEG || N0.getOpcode() == ISD::FABS) &&
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if (((N0.getOpcode() == ISD::FNEG && !TLI.isFNegFree(VT)) ||
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(N0.getOpcode() == ISD::FABS && !TLI.isFAbsFree(VT))) &&
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N0.getNode()->hasOneUse() && VT.isInteger() && !VT.isVector()) {
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SDValue NewConv = DAG.getNode(ISD::BITCAST, N0.getDebugLoc(), VT,
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N0.getOperand(0));
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@ -5993,7 +5994,7 @@ SDValue DAGCombiner::visitFNEG(SDNode *N) {
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// Transform fneg(bitconvert(x)) -> bitconvert(x^sign) to avoid loading
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// constant pool values.
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if (N0.getOpcode() == ISD::BITCAST &&
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if (!TLI.isFNegFree(VT) && N0.getOpcode() == ISD::BITCAST &&
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!VT.isVector() &&
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N0.getNode()->hasOneUse() &&
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N0.getOperand(0).getValueType().isInteger()) {
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@ -6029,7 +6030,8 @@ SDValue DAGCombiner::visitFABS(SDNode *N) {
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// Transform fabs(bitconvert(x)) -> bitconvert(x&~sign) to avoid loading
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// constant pool values.
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if (N0.getOpcode() == ISD::BITCAST && N0.getNode()->hasOneUse() &&
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if (!TLI.isFAbsFree(VT) &&
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N0.getOpcode() == ISD::BITCAST && N0.getNode()->hasOneUse() &&
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N0.getOperand(0).getValueType().isInteger() &&
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!N0.getOperand(0).getValueType().isVector()) {
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SDValue Int = N0.getOperand(0);
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