[llvm] [VPlan] Use VPInstructionWithType for uniform casts. (PR #140623)

[via llvm-commits]

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@@ -1031,8 +1031,15 @@ static void simplifyRecipe(VPRecipeBase &R, VPTypeAnalysis &TypeInfo) {
         unsigned ExtOpcode = match(R.getOperand(0), m_SExt(m_VPValue()))
                                  ? Instruction::SExt
                                  : Instruction::ZExt;
-        auto *VPC =
-            new VPWidenCastRecipe(Instruction::CastOps(ExtOpcode), A, TruncTy);
+        VPSingleDefRecipe *VPC;
+        if (vputils::isSingleScalar(Def))
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ayalz wrote:

Note that this asks if a VPSingleDefRecipe Def is single scalar, where Def (not being a VPInstruction) does not record its own IsSingleScalar, defaulting to vputils function to figure it out.
Can VPWidenCastRecipe be folded into VPInstructionWithType, making the latter single-scalar agnostic?

https://github.com/llvm/llvm-project/pull/140623