[llvm] [VPlan] Replace UnrollPart for VPScalarIVSteps with start index op (NFC) (PR #170906)

[via llvm-commits]

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@@ -322,6 +322,17 @@ class VPBuilder {
     return createScalarCast(CastOp, Op, ResultTy, DL);
   }
 
+  VPValue *createScalarSExtOrTrunc(VPValue *Op, Type *ResultTy, Type *SrcTy,
+                                   DebugLoc DL) {
+    if (ResultTy == SrcTy)
+      return Op;
+    Instruction::CastOps CastOp =
+        ResultTy->getScalarSizeInBits() < SrcTy->getScalarSizeInBits()
+            ? Instruction::Trunc
+            : Instruction::SExt;
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ayalz wrote:

Ahh, right, of course.

https://github.com/llvm/llvm-project/pull/170906