[clang] [llvm] [clang-tools-extra] [VPlan] Add new VPUniformPerUFRecipe, use for step truncation. (PR #78113)

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@@ -2297,6 +2297,7 @@ emitTransformedIndex(IRBuilderBase &B, Value *Index, Value *StartValue,
                            ? B.CreateSExtOrTrunc(Index, StepTy)
                            : B.CreateCast(Instruction::SIToFP, Index, StepTy);
   if (CastedIndex != Index) {
+    assert(!isa<SExtInst>(CastedIndex));
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ayalz wrote:

nit: error message missing.

https://github.com/llvm/llvm-project/pull/78113