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Don't create a MIN/MAX node if the underlying compare has more than one use.
If the compare in a select pattern has another use then it can't be removed, so we'd just be creating repeated code if we created a min/max node. Spotted by Matt Arsenault! git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239037 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -2282,7 +2282,11 @@ void SelectionDAGBuilder::visitSelect(const User &I) {
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while (TLI.getTypeAction(Ctx, VT) == TargetLoweringBase::TypeSplitVector)
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VT = TLI.getTypeToTransformTo(Ctx, VT);
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if (Opc != ISD::DELETED_NODE && TLI.isOperationLegalOrCustom(Opc, VT)) {
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if (Opc != ISD::DELETED_NODE && TLI.isOperationLegalOrCustom(Opc, VT) &&
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// If the underlying comparison instruction is used by any other instruction,
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// the consumed instructions won't be destroyed, so it is not profitable
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// to convert to a min/max.
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cast<SelectInst>(&I)->getCondition()->hasOneUse()) {
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OpCode = Opc;
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LHSVal = getValue(LHS);
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RHSVal = getValue(RHS);
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@ -94,3 +94,14 @@ define <16 x i32> @t11(<16 x i32> %a, <16 x i32> %b) {
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%t2 = select <16 x i1> %t1, <16 x i32> %a, <16 x i32> %b
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ret <16 x i32> %t2
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}
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; CHECK-LABEL: t12
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; CHECK-NOT: umin
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; The icmp is used by two instructions, so don't produce a umin node.
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define <16 x i8> @t12(<16 x i8> %a, <16 x i8> %b) {
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%t1 = icmp ugt <16 x i8> %b, %a
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%t2 = select <16 x i1> %t1, <16 x i8> %a, <16 x i8> %b
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%t3 = zext <16 x i1> %t1 to <16 x i8>
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%t4 = add <16 x i8> %t3, %t2
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ret <16 x i8> %t4
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}
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