[llvm] [VPlan] Introduce VPInstructionWithType, use instead of VPScalarCast(NFC) (PR #129706)

[Luke Lau via llvm-commits]

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@@ -113,7 +113,12 @@ bool vputils::isUniformAcrossVFsAndUFs(VPValue *V) {
                all_of(R->operands(),
                       [](VPValue *Op) { return isUniformAcrossVFsAndUFs(Op); });
       })
-      .Case<VPScalarCastRecipe, VPWidenCastRecipe>([](const auto *R) {
+      .Case<VPInstruction>([](const auto *VPI) {
+        return Instruction::isCast(VPI->getOpcode())
+                   ? all_of(VPI->operands(), isUniformAcrossVFsAndUFs)
+                   : false;
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lukel97 wrote:

Nit, I think this is the same as

```suggestion
        return Instruction::isCast(VPI->getOpcode()) && all_of(VPI->operands(), isUniformAcrossVFsAndUFs);
```

https://github.com/llvm/llvm-project/pull/129706