[llvm] [RISCV][ISel] Combine scalable vector fadd/fsub/fmul with fp extend. (PR #88615)

[Craig Topper via llvm-commits]

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@@ -13597,6 +13599,13 @@ struct NodeExtensionHelper {
     case RISCVISD::VZEXT_VL:
     case RISCVISD::FP_EXTEND_VL:
       return OrigOperand.getOperand(0);
+    case ISD::SPLAT_VECTOR: {
+      SDValue Op = OrigOperand.getOperand(0);
+      if (Op.getOpcode() == ISD::FP_EXTEND)
+        return Op;
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topperc wrote:

> How does this work for fixed length float splats currently if we didn't already handle RISCVISD::VFMV_V_F_VL? Since in https://github.com/llvm/llvm-project/pull/81248 it looks like we emit vfwadd.vf

The extend on those tests are happening in the vector domain not the scalar domain I think.

https://github.com/llvm/llvm-project/pull/88615