Re: PPC64: gcc currently compiles for power4 by default, causing glibc's sqrtf to fail on e6500

[Mathieu Malaterre <malat@debian.org>]

On Fri, Feb 9, 2018 at 11:34 AM, John Paul Adrian Glaubitz
<glaubitz@physik.fu-berlin.de> wrote:
> On 02/09/2018 11:30 AM, Bas Vermeulen wrote:
>>
>> mator on #debian-ports compiled gcc-7 for me with the attached patch.
>> With the resulting gcc, I compiled glibc and got a library I can use
>> sqrtf without running into an illegal instruction exception.
>>
>> Would it be possible to get this applied by default? The resulting
>> binaries work on e6500, and ought to work on all supported CPUs
>> for the ppc64 port.
>
>
> This is something that needs to be discussed. A single user alone shouldn't
> warrant such major change in a port. You always have to keep in mind that
> changing the default compiler options also has potential impact on the
> performance on more modern ppc64 systems like Apple Macintosh.
>
> So, while I'm generally not against such a change, I would like to hear
> some voices first.

uh, could someone please actually list the diff ? I am guessing something like:

$ echo | gcc -dM -E -

or maybe:

$ gcc  -Q --help=target