[llvm] [VPlan] Emit VPVectorEndPointerRecipe for reverse interleave pointer adjustment (PR #144864)

[Mel Chen via llvm-commits]

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@@ -1706,17 +1706,22 @@ class VPWidenGEPRecipe : public VPRecipeWithIRFlags {
 
 /// A recipe to compute a pointer to the last element of each part of a widened
 /// memory access for widened memory accesses of IndexedTy. Used for
-/// VPWidenMemoryRecipes that are reversed.
+/// VPWidenMemoryRecipes or VPInterleaveRecipes that are reversed.
 class VPVectorEndPointerRecipe : public VPRecipeWithIRFlags,
                                  public VPUnrollPartAccessor<2> {
   Type *IndexedTy;
 
+  /// The constant stride of the pointer computed by this recipe.
+  int64_t Stride;
+
 public:
   VPVectorEndPointerRecipe(VPValue *Ptr, VPValue *VF, Type *IndexedTy,
-                           GEPNoWrapFlags GEPFlags, DebugLoc DL)
+                           int64_t Stride, GEPNoWrapFlags GEPFlags, DebugLoc DL)
       : VPRecipeWithIRFlags(VPDef::VPVectorEndPointerSC,
                             ArrayRef<VPValue *>({Ptr, VF}), GEPFlags, DL),
-        IndexedTy(IndexedTy) {}
+        IndexedTy(IndexedTy), Stride(Stride) {
+    assert(Stride != 0 && "Stride cannot be zero");
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Mel-Chen wrote:

Yes, so far it must be negative.
ef6b46a55b9517f9de79b42424f6257cff83638f

https://github.com/llvm/llvm-project/pull/144864