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

[Eli Friedman via cfe-commits]

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@@ -32,9 +32,9 @@ struct X f(void);
 // C11-O2-NEXT:    [[A:%.*]] = getelementptr inbounds nuw [[STRUCT_X]], ptr [[REF_TMP]], i32 0, i32 0
 // C11-O2-NEXT:    [[ARRAYDECAY:%.*]] = getelementptr inbounds [5 x i32], ptr [[A]], i64 0, i64 0
 // C11-O2-NEXT:    call void @llvm.lifetime.end.p0(i64 20, ptr [[REF_TMP]]) #[[ATTR5]]
-// C11-O2-NEXT:    store ptr [[ARRAYDECAY]], ptr [[P]], align 8, !tbaa [[TBAA2:![0-9]+]]
-// C11-O2-NEXT:    [[TMP0:%.*]] = load ptr, ptr [[P]], align 8, !tbaa [[TBAA2]]
-// C11-O2-NEXT:    [[TMP1:%.*]] = load i32, ptr [[TMP0]], align 4, !tbaa [[TBAA7:![0-9]+]]
+// C11-O2-NEXT:    store ptr [[ARRAYDECAY]], ptr [[P]], align 8, !tbaa [[TBAA6:![0-9]+]]
+// C11-O2-NEXT:    [[TMP0:%.*]] = load ptr, ptr [[P]], align 8, !tbaa [[TBAA6]]
+// C11-O2-NEXT:    [[TMP1:%.*]] = load i32, ptr [[TMP0]], align 4, !tbaa [[TBAA2:![0-9]+]]
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efriedma-quic wrote:

The check lines here are autogenerated; if we edit anything by hand, we'll need to mark it as a test that can't be automatically regenerated.  Which annoying not only right now, but in the future if the test ever needs to be updated.

It might be possible to make update_cc_test_checks.py choose better names for TBAA checks; in theory, it could take the type name from the metadata, and use it to choose the name of the tbaa variable.

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