[llvm] [VPlan] Use pointer to member 0 as VPInterleaveRecipe's pointer arg. (PR #106431)

[Ramkumar Ramachandra via llvm-commits]

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@@ -1539,9 +1543,39 @@ void VPlanTransforms::createInterleaveGroups(
 
     bool NeedsMaskForGaps =
         IG->requiresScalarEpilogue() && !ScalarEpilogueAllowed;
-    auto *VPIG = new VPInterleaveRecipe(IG, Recipe->getAddr(), StoredValues,
-                                        Recipe->getMask(), NeedsMaskForGaps);
-    VPIG->insertBefore(Recipe);
+
+    Instruction *IRInsertPos = IG->getInsertPos();
+    auto *InsertPos =
+        cast<VPWidenMemoryRecipe>(RecipeBuilder.getRecipe(IRInsertPos));
+    VPRecipeBase *IP = InsertPos;
+
+    // Get or create the start address for the interleave group.
+    auto *Start =
+        cast<VPWidenMemoryRecipe>(RecipeBuilder.getRecipe(IG->getMember(0)));
+    VPValue *Addr = Start->getAddr();
+    if (!VPDT.properlyDominates(Addr->getDefiningRecipe(), InsertPos)) {
+      bool InBounds = false;
+      if (auto *gep = dyn_cast<GetElementPtrInst>(
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artagnon wrote:

Nit: s/gep/GEP/ for style consistency?

https://github.com/llvm/llvm-project/pull/106431