Re: [PATCH] PR66870 PowerPC64 Enable gold linker with split stack

["Lynn A. Boger" <laboger at linux dot vnet dot ibm dot com>]

Also, I don't think it is sufficient to add the option to enable the
gold linker in gospec.c.  That will only affect links when using gccgo.
You also want to use the gold linker with gcc if -fsplit-stack is used.
That is why I had to add it to a spec in linux64.h, so that -fuse-ld=gold
 is added if fsplit-stack is set for all compilers, not just gccgo.

On 08/19/2015 02:33 PM, Matthias Klose wrote:
> On 08/18/2015 10:36 PM, Lynn A. Boger wrote:
> > As discussed in PR 66870, for ppc64le and ppc64le it is preferred to
> >   use the gold linker with gccgo or gcc if the split stack option is enabled.
> > Use of the gold linker with the split stack option results in less storage
> > allocated for goroutine stacks; if split stack is used without the gold
> > linker then some testcase failures can occur.
> >
> >    Since the use of the gold linker has not been well tested
> > with all gcc compilers on Power, it is only used as the linker if the
> > split stack option is used.
> >
> > This adds the capability to the configure for gcc and libgo to determine
> > if the gold linker is available at build time, either in the path or explicitly
> >   configured, and its version supports split stack.  If that is the case then
> > defines are set that cause the gold linker to be used by the compiler when
> > -fsplit-stack is used.  This applies to ppc64 and ppc64le.  Other platforms
> > with split stack work as before.
> >
> > 2015-08-18    Lynn Boger <laboger@linux.vnet.ibm.com>
> >
> > gcc/
> >          PR target/66870
> >          config/rs6000/linux64.h: When HAVE_LD_GOLD_SUPPORTS_SPLIT_STACK
> >          is defined add -fuse-ld=gold if fsplit-stack and not m32
> >          config/rs6000/sysv4.h:  Define TARGET_CAN_SPLIT_STACK based on
> >          LIBC version.
> >          config.in:  Set up HAVE_LD_GOLD_SUPPORTS_SPLIT_STACK.
> >          configure.ac:  When gold linker is available and its version
> >          supports split stack on ppc64, ppc64le, define
> >          HAVE_LD_GOLD_SUPPORTS_SPLIT_STACK.
> >          configure:  Regenerate.
> >
> > libgo/
> >          PR target/66870
> >          configure.ac:  When gccgo for building libgo uses the gold version
> >          containing split stack support on ppc64, ppc64le, define
> >          LINKER_SUPPORTS_SPLIT_STACK.
> >          configure:  Regenerate.
> >
> > For platforms other than ppc64 and ppc64le, the configure for gcc
> > and libgo behave as before.
> why keep the old behaviour for other archs that have split stack support? Is it
> really necessary to make this dependent on the target? I'm still using an
> unreviewed/unpinged patch to enable gold for gccgo (attached).
>
> Matthias