Re: [PATCH 0/3] Simplify the simple_return handling

[Kyrill Tkachov <kyrylo dot tkachov at foss dot arm dot com>]

Hi Segher,

On 03/05/16 07:59, Segher Boessenkool wrote:
> This series teaches cfgcleanup how to optimize jumps and branches to and
> around return statements, after which the shrink-wrap code doesn't have
> to deal with it anymore.  The simplified code also catches a few more
> cases.
>
> Tested on powerpc64-linux (-m32 and -m64, all languages), and also on
> x86_64-linux (actually, still in progress with the most recent version
> of the patchset).  Is this okay for trunk?

I tried make check on gcc on aarch64 and I didn't see any fallout.
I also had a quick look on SPECINT and there seems to be a consistent
small reduction in code size on them, mostly from redundant returns
being eliminated, for example:

    bgt    .L70
    ret
.L62:
    ret
.L76:

into:

    bgt    .L70
.L62:
    ret

So I think this should be a win overall.

Thanks,
Kyrill

> Segher
>
>
>    cfgcleanup: Bugfix
>    cfgcleanup: Fold jumps and conditional branches with returns
>    shrink-wrap: Remove complicated simple_return manipulations
>
>   gcc/cfgcleanup.c  | 124 +++++++++++++++++++++++++++++++
>   gcc/function.c    | 213 +-----------------------------------------------------
>   gcc/shrink-wrap.c | 171 ++++---------------------------------------
>   gcc/shrink-wrap.h |   6 --
>   4 files changed, 140 insertions(+), 374 deletions(-)