On Fri, Oct 28, 2022 at 10:08 AM Hongyu Wang wrote:
>
> > Ugh, that's all quite ugly and unmaintainable, no?
> Agreed, I have the same feeling.
>
> > I'm quite sure that if this works it's not by intention. Doesn't this
> > also disable
> > register renaming and web when the user explicitely spec
> Ugh, that's all quite ugly and unmaintainable, no?
Agreed, I have the same feeling.
> I'm quite sure that if this works it's not by intention. Doesn't this
> also disable
> register renaming and web when the user explicitely specifies -funroll-loops?
>
> Doesn't this change -funroll-loops behav
On Wed, Oct 26, 2022 at 7:53 AM Hongyu Wang wrote:
>
> Hi,
>
> Inspired by rs6000 and s390 port changes, this patch
> enables loop unrolling for small size loop at O2 by default.
> The default behavior is to unroll loop with unknown trip-count and
> less than 4 insns by 1 time.
>
> This improves 5
> Does this setting benefit all targets? IIRC, in the past all
> benchmarks also enabled -funroll-loops, so it looks to me that
> unrolling small loops by default is a good compromise.
The idea to unroll small loops can be explained from the x86
micro-architecture. Modern x86 processors has multi
On Wed, Oct 26, 2022 at 7:53 AM Hongyu Wang wrote:
>
> Hi,
>
> Inspired by rs6000 and s390 port changes, this patch
> enables loop unrolling for small size loop at O2 by default.
> The default behavior is to unroll loop with unknown trip-count and
> less than 4 insns by 1 time.
>
> This improves 5
