Hello,

For a powerpc compiler configured with --with-abi=elfv2, an explicit
-mabi option other than elfv1 fails to override the default.

For example, after

  [...]/configure --enable-languages=c --target=powerpc-elf --with-abi=elfv2
  make all-gcc

This command:

  ./gcc/xgcc -B./gcc/ t.c -mabi=ieeelongdouble -v

issues:

  ./gcc/cc1 [...] t.c -mabi=ieeelongdouble -mabi=elfv2

elfv2 overrides the user request here, which I think
is not as intended.

This is controlled by OPTION_DEFAULT_SPECS, where we have

  {"abi", "%{!mabi=elfv*:-mabi=%(VALUE)}" },

From https://gcc.gnu.org/pipermail/gcc-patches/2013-November/375042.html
I don't see an explicit reason to trigger only on elfv* . It just looks
like an oversight with a focus on elfv1 vs elfv2 at the time.

The attached patch is a proposal to correct this, simply removing the
"elfv" prefix from the spec and adding the corresponding description
to the block comment just above.

We have been using this for about a year now in gcc-11 based toolchains.
This helps our dejagnu testsuite runs for VxWorks on powerpc and 
hasn't produced any ill side effect to date.

The patch also bootstraps and regtests fine on powerpc64-linux.

Is this OK to commit?

Thanks in advance!

With Kind Regards,

Olivier

2022-09-14  Olivier Hainque  <hainque@adacore.com>

        * config/rs6000/option-defaults.h (OPTION_DEFAULT_SPECS):
        Have any -mabi, not only -mabi=elfv*, override the --with-abi
        configuration default.