[llvm] [LV] Teach LoopVectorizationLegality about struct vector calls (PR #119221)

[Florian Hahn via llvm-commits]

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@@ -943,11 +955,24 @@ bool LoopVectorizationLegality::canVectorizeInstrs() {
       if (CI && !VFDatabase::getMappings(*CI).empty())
         VecCallVariantsFound = true;
 
+      auto canWidenInstruction = [this](Instruction const &Inst) {
+        Type *InstTy = Inst.getType();
+        if (isa<CallInst>(Inst) && isa<StructType>(InstTy) &&
+            canWidenCallReturnType(InstTy)) {
+          StructVecCallFound = true;
+          // For now, we can only widen struct values returned from calls where
+          // all users are extractvalue instructions.
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fhahn wrote:

Hm I see, would probably be good to clarify the comment, as the current wording seems to imply we can already widen it (which to me reads as we can create wide vector recipes for them)

https://github.com/llvm/llvm-project/pull/119221