[PATCH] D18035: [GCC] PR23529 Mangler part of attrbute abi_tag support

[Dmitry Polukhin via cfe-commits]

DmitryPolukhin added a comment.

In http://reviews.llvm.org/D18035#450258, @rsmith wrote:

> Yes, I definitely want us to implement this for GCC compatibility. And now that we have a specification for this feature, we can evaluate whether this is doing the right thing. On that basis:
>
> I still want this refactored so that the normally-mangled part of a function name is only mangled once, rather than being mangled twice (once to find the implicit tag set and once to actually produce the mangled name). As suggested, you can achieve this by first computing the set of tags from the return type, then mangling the encoding to a separate buffer (collecting tags as you go) if the set is non-empty, and finally writing any remaining tags and the buffer contents.
>
> Please factor out a function to mangle the source name and ABI tags for a `NamedDecl` rather than duplicating that pair of calls throughout the patch.
>
> Current discussion on the ABI list suggests that it is not correct to mangle the return type / variable type to get the implicit tag set. The set of available attributes should be determined by a recursive walk of the original type (prior to any substitution), not by mangling it and seeing what it references. It's not yet clear whether that's the actual design intent or just the emergent behavior of the GCC implementation, however.


I'm monitoring the discussion and will try to rewrite this patch according to the guidance and avoid double mangling.


http://reviews.llvm.org/D18035