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Re: [PATCH] Steam out non-explicit -fno-tree-loop-distribute-patterns for LTO options


On Thu, 28 Aug 2014, Kito Cheng wrote:

> Hi Richard:
> 
> I think preserve -fno-builtin is better than
> -fno-tree-loop-distribute-patterns too,
> 
> However if we preserve -fno-builtin, the coming problem is should we
> preserve all -fbuiltin-* and do the check logic[1] in common code in
> gcc?

No, just -fno-builtin.
 
> btw, in our internal gcc 4.9.x tree is move -fno-builtin to common
> group (CL_COMMON) (preserve in lto since it's in CL_COMMON)  and check
> it in tree-loop-distribution.c for temporary workaround .
> 
> [1] gcc/c-family/c-common.c:disable_builtin_function
> 
> On Thu, Aug 28, 2014 at 4:45 PM, Richard Biener
> <richard.guenther@gmail.com> wrote:
> > On Wed, Aug 27, 2014 at 4:42 PM, Kito Cheng <kito.cheng@gmail.com> wrote:
> >> Hi all:
> >>
> >> This patch basically is extension for r210100[1], stream out
> >> non-explicit -fno-tree-loop-distribute-patterns since compile with
> >> `-flto -O3 -fno-builtin` still may gen builtin function call during
> >> LTO phase.
> >>
> >> LTO bootstrapped and tested on x86_64-unknown-linux-gnu.
> >
> > Hmm, but that will for two units, one compiled with -O2 and one
> > compiled with -O3, produce -O3 -fno-tree-loop-distribute-patterns.
> > The previous patch restricted this to -ffreestanding / -fno-builtin.
> >
> > I think it makes more sense to preserve -fno-builtin, that is,
> > add 'LTO' to the list of FEs supporting 'fbuiltin' (the non-joined version)
> > and stream '-fno-builtin' if set, doing similar option post-processing
> > in the LTO frontend as I added to the C family frontends.
> >
> > Richard.
> >
> >> 2014-09-27  Kito Cheng  <kito@0xlab.org>
> >>
> >>     * lto-opts.c (lto_write_options): Output non-explicit
> >>     -fno-tree-loop-distribute-patterns.
> >>     * lto-wrapper.c (merge_and_complain): Merge
> >>     -fno-tree-loop-distribute-patterns conservatively.
> >>     (run_gcc): Pass through -fno-tree-loop-distribute-patterns.
> >>
> >>
> >> [1] https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=210100
> 
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE / SUSE Labs
SUSE LINUX Products GmbH - Nuernberg - AG Nuernberg - HRB 16746
GF: Jeff Hawn, Jennifer Guild, Felix Imend"orffer


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