[Bug target/114718] New: GCN's '-march'es vs. default multilib

[Bug target/114718] New: GCN's '-march'es vs. default multilib

[tschwinge at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114718

            Bug ID: 114718
           Summary: GCN's '-march'es vs. default multilib
           Product: gcc
           Version: 14.0
               URL: https://github.com/gcc-mirror/gcc/commit/1bf18629c54ad
                    f4893c8db5227a36e1952ee69a3#commitcomment-140648051
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: tschwinge at gcc dot gnu.org
                CC: ams at gcc dot gnu.org
  Target Milestone: ---
            Target: GCN

When a specific multilib build for GCN's '-march'es is not available (has not
been 'configure'd/packaged), GCC resorts to the default multilib build -- which
in the case of GCN won't even link: 'ld: error: incompatible mach'.  Instead of
attempting the latter (default multilib build), should this case be diagnosed
properly, instead?

(Independent of the vague idea that multilib builds for GCN be made "more
permeable".)

Reported, for example, by Oscar Barenys in
<https://github.com/gcc-mirror/gcc/commit/1bf18629c54adf4893c8db5227a36e1952ee69a3#commitcomment-140648051>.

[Bug target/114718] GCN's '-march'es vs. default multilib

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114718

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                URL|https://github.com/gcc-mirr |
                   |or/gcc/commit/1bf18629c54ad |
                   |f4893c8db5227a36e1952ee69a3 |
                   |#commitcomment-140648051    |

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
https://github.com/gcc-mirror/gcc/commit/1bf18629c54adf4893c8db5227a36e1952ee69a3#commitcomment-140648051

[Bug driver/114718] GCN's '-march'es vs. default multilib

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114718

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|target                      |driver
           Severity|normal                      |enhancement
           Keywords|                            |diagnostic

[Bug driver/114718] GCN's '-march'es vs. default multilib

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114718

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2024-04-15
             Status|UNCONFIRMED                 |WAITING
     Ever confirmed|0                           |1

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This is a standard ABI changing option issue. I doubt there is anything can be
done as you don't know if the library was installed seperately and might just
happen to work with some extra -L options.

Maybe describe what kind of error message you are expecting instead of the
current one which is coming from the linker when doing the final link?