[llvm] [VPlan] Don't reset canonical IV start value. (PR #161589)

[Florian Hahn via llvm-commits]

================
@@ -1234,6 +1234,17 @@ static void simplifyRecipe(VPRecipeBase &R, VPTypeAnalysis &TypeInfo) {
   if (!Plan->isUnrolled())
     return;
 
----------------
fhahn wrote:

Added with minor edit, as this applies to any (scalar) phi

https://github.com/llvm/llvm-project/pull/161589