[llvm] [VPlan] Manage noalias/alias_scope metadata in VPlan. (NFC) (PR #136450)

[Florian Hahn via llvm-commits]

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@@ -9011,6 +8995,20 @@ bool VPRecipeBuilder::getScaledReductions(
   return false;
 }
 
+SmallVector<std::pair<unsigned, MDNode *>>
+VPRecipeBuilder::getMetadataToPropagate(Instruction *I) const {
+  SmallVector<std::pair<unsigned, MDNode *>> Metadata;
+  ::getMetadataToPropagate(I, Metadata);
+  if (LVer && isa<LoadInst, StoreInst>(I)) {
+    const auto &[AliasScopeMD, NoAliasMD] = LVer->getNoAliasMetadataFor(I);
+    if (AliasScopeMD)
+      Metadata.emplace_back(LLVMContext::MD_alias_scope, AliasScopeMD);
+    if (NoAliasMD)
+      Metadata.emplace_back(LLVMContext::MD_noalias, NoAliasMD);
+  }
+  return Metadata;
+}
+
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fhahn wrote:

We could provide such a constructor, but then we would need to pass `LVer` to the recipe constructor, which seems like leaking more implementation details of LV into recipes. Passing the metadata that's needed as list seems more general, and more cleanly separates the interfaces. WDYT?

https://github.com/llvm/llvm-project/pull/136450