[llvm] [VPlan] Implement VPlan-based unit-strideness speculation (PR #182595)

[Andrei Elovikov via llvm-commits]

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@@ -5641,33 +5647,34 @@ void VPlanTransforms::multiversionForUnitStridedMemOps(
 
     StridePredicates = StridePredicates.getUnionWith(NewPred, *SE);
 
-    auto ReplaceUsesInVectorLoop = [&](Value *V, const SCEV *ToSCEV) {
+    // Replace the stride and all integral casts derived from it. Some casts
+    // might be defined outside VPlan and modeled as live-ins only, so we need
+    // to process users at the LLVM IR level in order to discover them.
+    auto ReplaceUsesInVectorLoopThroughCastsRecursively =
+        [&](auto &Self, Value *V, const SCEV *ToSCEV) -> void {
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eas wrote:

Either works for me, so extracted in the latest upload.

https://github.com/llvm/llvm-project/pull/182595