[llvm] [RISCV] Rewrite vrgather.vx undef, (vmv.s.x), 0, v0 as vmv.v.x (PR #136010)

[Craig Topper via llvm-commits]

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@@ -19710,20 +19709,47 @@ SDValue RISCVTargetLowering::PerformDAGCombine(SDNode *N,
       return V;
     break;
   case RISCVISD::VRGATHER_VX_VL: {
-    // Drop a redundant vrgather_vx.
+    using namespace llvm::SDPatternMatch;
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topperc wrote:

You don't need this now

https://github.com/llvm/llvm-project/pull/136010