[llvm] [X86] getScalarMaskingNode - if the mask is zero just return the preserved source value (PR #153575)

[Simon Pilgrim via llvm-commits]

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@@ -26261,10 +26261,8 @@ static SDValue getScalarMaskingNode(SDValue Op, SDValue Mask,
                                     SDValue PreservedSrc,
                                     const X86Subtarget &Subtarget,
                                     SelectionDAG &DAG) {
-
   if (auto *MaskConst = dyn_cast<ConstantSDNode>(Mask))
-    if (MaskConst->getZExtValue() & 0x1)
-      return Op;
+    return (MaskConst->getZExtValue() & 0x1) ? Op : PreservedSrc;
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RKSimon wrote:

You're right - we need to remove the scalar op and convert to a basic blend instead of just passing through - sorry about that

https://github.com/llvm/llvm-project/pull/153575