ppc64le: gcc 12 vs -mabi=ibmlongdouble

[Paul E Murphy]

On 1/24/22 9:38 AM, Florian Weimer wrote:
> * DJ Delorie via Libc-alpha:
> 
>> I've been working on updating glibc for Fedora Rawhide, and have
>> stumbled upon this issue (after working around the -Wuse-after-free
>> issues with a cflags hack)...  A few of the math tests explicitly add
>> -mlong-double-64 but configure adds -mabi=ibmlongdouble
>>
>> I would guess that we need a "CFLAGS -= -mabi=ibmlongdouble" in all
>> the places we add -mlong-double-64 but I don't see an easy way of
>> doing that, nor am I sure that's a valid solution.  Alternately, gcc
>> could be changed to accept the conflicting flags in a meaningful way,
>> if there is one.  Is there an -mabi= that undoes the
>> -mabi=ibmlongdouble that we can just add to the -mlong-double-64 flag
>> lines?

For the sake of my clarification, does this affect more than the 6 test 
cases/files in ldbl-opt Makefile? If not, could the removal be handled 
case-by-case in sysdeps/powerpc/powerpc64/le/Makefile?

> 
>> cc1: error: '-mabi=ibmlongdouble' requires '-mlong-double-128'
> 
> I was able to reproduce with a GCC 12 build configured using
> --with-long-double-format=ieee.
> 
> I tried the attached patch to remove the unwanted -mabi=ibmlongdouble,
> but it does not work: it removes CFLAGS-*.c processing as a side effect.
> 
> Any suggestions how we can fix this properly?
> 
> Thanks,
> Florian
>