[llvm] [llvm-symbolizer] Recognize AIX big archive (PR #150401)

[James Henderson via llvm-commits]

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@@ -535,16 +535,20 @@ MACH-O SPECIFIC OPTIONS
 .. option:: --default-arch <arch>
 
   If a binary contains object files for multiple architectures (e.g. it is a
-  Mach-O universal binary), symbolize the object file for a given architecture.
-  You can also specify the architecture by writing ``binary_name:arch_name`` in
-  the input (see example below). If the architecture is not specified in either
-  way, the address will not be symbolized. Defaults to empty string.
+  Mach-O universal binary or an AIX archive with architecture variants),
+  symbolize the object file for a given architecture. You can also specify
+  the architecture by writing ``binary_name:arch_name`` in the input (see
+  example below). For AIX archives, the format ``archive.a(member.o):arch``
+  is also supported. If the architecture is not specified,
+  the address will not be symbolized. Defaults to empty string.
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jh7370 wrote:

> If the architecture is not specified, the address will not be symbolized

This bit of the behaviour needs testing in both tests.

https://github.com/llvm/llvm-project/pull/150401