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Re: [PATCH] [GCC] Don't use section anchors for declarations that don't fit in a single anchor range
On Wed, Aug 17, 2016 at 09:09:07PM -0600, Jeff Law wrote:
> On 08/17/2016 02:23 AM, Richard Biener wrote:
> >On Tue, Aug 16, 2016 at 6:06 PM, Jeff Law <law@redhat.com> wrote:
> >>On 08/16/2016 08:01 AM, Tamar Christina wrote:
> >>>
> >>>
> >>>Hi All,
> >>>
> >>>This patch turns off the usage of section anchors for
> >>>declarations that do not fit in a single anchor range.
> >>>A large enough object will use the full anchor range
> >>>and also force the use of another anchor pointer.
> >>>
> >>>By not using an anchor for large objects more globals
> >>>can share the same anchor.
> >>>
> >>>The patch has been benchmarked using Spec2000 and
> >>>the impact on performance is negligible, however some files
> >>>using large arrays showed a appreciable reduction in amount of
> >>>instructions in the assembly file.
> >>>
> >>>Regression tests were run on aarch64-none-elf and no regressions.
> >>>
> >>>Ok for trunk?
> >>>
> >>>2016-08-16 Tamar Christina <tamar.christina@arm.com>
> >>> Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>
> >>>
> >>> * gcc/varasm.c
> >>> (default_use_anchors_for_symbol_p): Reject too large decls.
> >>
> >>Do you have to worry about DECL_SIZE being non-constant here or are those
> >>filtered out earlier?
> >
> >Globals can't have variable size.
> Duh. You're obviously correct.
>
> Patch is OK for the trunk.
Tamar's not yet got commit rights, so I've committed this on his behalf as
r239561.
Thanks for the review!
James