* Jan Hubicka:
> Internally the patch tries to mimic what happens in ELF. In particular
>
> __attribute__ ((__symver__ ("foo@VERS_1"))) int
> foo_v1 (void)
> {
> }
>
> creates a special form of alias with symver flag. Its assembler name is
> foo@VERS_1 since it is what happens in ELF too (normally @ is not
> allowed in symbol name). Rest of GCC and LTO path handles is as normal
> alias (since it seems what binutils does as well) and instead of
> outputting it via .set we use .symver directive at the end.
Do you support foo@@VERS_1 for setting the default version as well?
It's sometimes useful to define multiple versions for a single symbol.
For maximum binutils compatibility, you would have to use intermediate
aliases. __attribute__ ((__symver__ ("foo@VERS_1", "foo@@VERS_2")))
could turn into this:
.set foo_v1.symver.1, foo_v1
.symver foo_v1.symver.1, foo_v1@VERS_1
.set foo_v1.symver.2, foo_v1
.symver foo_v1.symver.2, foo_v1@@VERS_2
Sometimes it's also necessary to reference a symbol version. I
suspect we'd need a separate attribute for that, or enhance the
__asm__ alias code to recognize @ and @@ symbols (also creating
internal aliases).
We would use both extensions (multiple symbol versions and symbol
references) internally for glibc eventually, once compiler versions
before GCC 10 are no longer supported.
