[Mesa-dev] [PATCH] mesa: Enable LTO compilation

Pierre Moreau pierre.morrow at free.fr
Mon May 30 18:13:28 UTC 2016


Ok, I found the answer to my question regarding the `-fno-lto`. IMHO that
should be in the commit message, since the patch only checks for availability
and disables LTO in one case, never enabling it explicitely.
Please ignore my previous mail.

Pierre

On 11:06 AM - May 30 2016, Matt Turner wrote:
> On Mon, May 30, 2016 at 11:02 AM, ⚛ <0xe2.0x9a.0x9b at gmail.com> wrote:
> >
> > On Mon, May 30, 2016 at 7:39 PM, Matt Turner <mattst88 at gmail.com> wrote:
> >>
> >> On Mon, May 30, 2016 at 10:28 AM, <0xe2.0x9a.0x9b at gmail.com> wrote:
> >> > This patch enables compilation with -flto.
> >> >
> >> > The performance benefits of LTO (GCC 4.9 & 6.1) are about 1% for glxgears.
> >> > Performance changes in OpenGL games haven't been measured yet, my feeling is
> >> > that they are negligible.
> >>
> >> Without a compelling reason, I don't think the build system should be
> >> adding compiler flags like this.
> >
> >
> > What does it mean "like this". The patched build system only checks whether -flto works because it needs to be disabled in mesa/src/mapi.
> >
> >>
> >> -flto makes debugging impossible, at least the last time I tried it
> >> with gcc. I don't think that's something we would want enabled
> >> whenever it's supported.
> >
> >
> > "Enable LTO compilation" means the person compiling Mesa can choose whether to use -flto.
> 
> Oh, I see. I misunderstood the patch initially.
> 
> Because src/mapi cannot be compiled with -flto, this patch *disables*
> -flto in that directory if it is enabled. Interesting.
> 
> (Please keep mesa-dev@ in Cc on your replies, and don't sent HTML mail)
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