[llvm] [X86] LowerRotate - expand vXi8 non-uniform variable rotates using uniform constant rotates (PR #189986)

[Phoebe Wang via llvm-commits]

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@@ -32177,14 +32177,16 @@ static SDValue LowerRotate(SDValue Op, const X86Subtarget &Subtarget,
       return DAG.getSelect(DL, SelVT, C, V0, V1);
     };
 
-    // ISD::ROTR is currently only profitable on AVX512 targets with VPTERNLOG.
-    if (!IsROTL && !useVPTERNLOG(Subtarget, VT)) {
+    // ISD::ROTR is currently only profitable on GFNI/AVX512+VPTERNLOG targets.
+    if (!IsROTL && !useVPTERNLOG(Subtarget, VT) && !Subtarget.hasGFNI()) {
       Amt = DAG.getNode(ISD::SUB, DL, VT, Z, Amt);
       IsROTL = true;
     }
 
-    unsigned ShiftLHS = IsROTL ? ISD::SHL : ISD::SRL;
-    unsigned ShiftRHS = IsROTL ? ISD::SRL : ISD::SHL;
+    auto BuildRotate = [&](SDValue R, unsigned RotAmt) {
+      return DAG.getNode(IsROTL ? ISD::ROTL : ISD::ROTR, DL, VT, R,
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phoebewang wrote:

Can we use `Opcode` directly?

https://github.com/llvm/llvm-project/pull/189986