[clang] [llvm] [clang][CodeGen][AA] Introduce `!llvm.errno.tbaa` for errno alias disambiguation (PR #125258)

[Nikita Popov via cfe-commits]

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@@ -385,6 +386,20 @@ AliasResult TypeBasedAAResult::alias(const MemoryLocation &LocA,
   return AliasResult::NoAlias;
 }
 
+AliasResult TypeBasedAAResult::aliasErrno(const MemoryLocation &Loc,
+                                          const Module *M) {
+  if (!shouldUseTBAA())
+    return AliasResult::MayAlias;
+
+  const auto *ErrnoTBAAMD = M->getNamedMetadata("llvm.errno.tbaa");
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nikic wrote:

Avoid lookup if we don't have TBAA in the first place.

https://github.com/llvm/llvm-project/pull/125258