[llvm] [AArch64][Build Attributes] Improve Parsing and Formatting (PR #126530)

[via llvm-commits]

================
@@ -222,13 +222,9 @@ void AArch64TargetStreamer::emitAttribute(StringRef VendorName, unsigned Tag,
                      "Can not add AArch64 build attribute: An attribute with "
                      "the same tag and a different value already exists");
               return;
-            } else {
-              // Case Item.IntValue == Value, no need to emit twice
-              assert(0 &&
-                     "AArch64 build attribute: An attribute with the same tag "
-                     "and a same value already exists");
-              return;
             }
+            // Case Item.IntValue == Value is permited.
----------------
sivan-shani wrote:

- Same tag, same value: ignore
Test- _aarch64-build-attributes-asm-aeabi-aeabi-known.s_
```
.aeabi_attribute Tag_PAuth_Schema, 777
.aeabi_attribute Tag_PAuth_Schema, 777
```
- Same tag, different value: override
Test- _aarch64-build-attributes-asm-aeabi-mixed.s_ (just been added)

https://github.com/llvm/llvm-project/pull/126530