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

[John McCall via cfe-commits]

================
@@ -1467,6 +1468,17 @@ void CodeGenModule::Release() {
       }
     }
   }
+
+  // Emit `!llvm.errno.tbaa`, a module-level metadata that specifies the TBAA
+  // for an integer access.
----------------
rjmccall wrote:

```suggestion
  // for an int access. This allows LLVM to reason about what memory can
  // be accessed by certain library calls that only touch errno.
```

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