[llvm] [VPlan] Use VPSCEVExpander in convertToStridedAccesses (PR #208939)

[Ramkumar Ramachandra via llvm-commits]

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@@ -2136,3 +2136,117 @@ loop:
 exit:
   ret void
 }
+
+; The routine for creating strided accesses depends on SCEV expansion.
+define void @scev_expander(ptr %p, ptr noalias %q) {
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artagnon wrote:

A comment specifically mentioning that this is when tryToExpand fails would unfortunately get outdated when we support AddRecs in VPSCEVExpander: it's going to be hard to hunt down for this comment and update it. Left that part out of the comment for this reason.

https://github.com/llvm/llvm-project/pull/208939