[lld] [llvm] [lld][AArch64][Build Attributes] Add support for AArch64 Build Attributes (PR #144082)

[Peter Smith via llvm-commits]

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@@ -0,0 +1,10 @@
+// Declare file properties exclusively with aarch64 build attributes.
+
+.aeabi_subsection aeabi_feature_and_bits, optional, uleb128
+.aeabi_attribute Tag_Feature_PAC, 1
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smithp35 wrote:

I've left a comment further down that recommends using split-file so that this can be inlined into the test that uses it.

I recommend using Tag_Feature_BTI, 1 so that you can simply add BTI support to the function.
```
func3:
  bti c
  ret
```
Although it doesn't really matter what the contents of the function are from the perspective of build attributes, an observer can see the matching property in the function. 

https://github.com/llvm/llvm-project/pull/144082