[Mesa-dev] [PATCH] util/disk_cache: fix zlib linking with LTO build

[Mike Lothian]

For what its worth I compile Mesa using LTO with the gold linker so I don't
need to specify -fuse-linker-plugin - everything works fine here

CFLAGS="-O3 -march=skylake -pipe -flto=8"
CXXFLAGS="${CFLAGS}"
LDFLAGS="-Wl,-O1 -Wl,--hash-style=gnu -Wl,--as-needed -Wl,-flto=8"

AR="gcc-ar"
NM="gcc-nm"
RANLIB="gcc-ranlib"


On Sat, 11 Mar 2017 at 16:46 Matt Turner <mattst88 at gmail.com> wrote:

> On Sat, Mar 11, 2017 at 7:31 AM, Emil Velikov <emil.l.velikov at gmail.com>
> wrote:
> > On 10 March 2017 at 13:36, Steven Newbury <steve at snewbury.org.uk> wrote:
> >> On Fri, 2017-03-10 at 12:11 +0000, Emil Velikov wrote:
> >>> On 9 March 2017 at 14:39, Steven Newbury <steve at snewbury.org.uk>
> >>> wrote:
> >>> > Introduction of zlib compression for the shader cache means
> >>> > zlib needs to be explicitly linked to libOSMesa and libstandalone
> >>> > otherwise build fails when LTO is used.
> >>> > ---
> >>>
> >>> How exactly are you doing the LTO build ?
> >> I build everything LTO, except for a short blacklist where
> >> unsupportable.  Specifically, on this system my global *FLAGS contain
> >> "-flto=8 -fuse-linker-plugin".  I have the lto linker plugin symlinked
> >> into "/usr/$CHOST/binutils-bin/lib/bfd-plugins/".
> >>
> >> I also have have the following env vars set to ensure they are called
> >> with the LTO plugin:
> >> AR="gcc-ar"
> >> NM="gcc-nm"
> >> RANLIB="gcc-ranlib"
> >>
> > One should not need these. Have you checked that the issue is
> > reproducible w/o them ?
>
> I think they are necessary
>
> https://gcc.gnu.org/ml/gcc-help/2012-03/msg00100.html
>
> (though I don't know under which circumstances precisely)
>
> FWIW, I agree that this patch looks like a hack.
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