Simply memcpy and memset inline strategies to avoid branches for
Skylake family CPUs:
1. With MOVE_RATIO and CLEAR_RATIO == 17, GCC will use integer/vector
load and store for up to 16 * 16 (256) bytes when the data size is
fixed and known.
2. Inline only if data size is known to be <= 256.
On Mon, Mar 22, 2021 at 6:16 AM H.J. Lu wrote:
>
> Simply memcpy and memset inline strategies to avoid branches for
> Skylake family CPUs:
>
> 1. With MOVE_RATIO and CLEAR_RATIO == 17, GCC will use integer/vector
>load and store for up to 16 * 16 (256) bytes when the data size is
>fixed an
> > /* skylake_cost should produce code tuned for Skylake familly of CPUs. */
> > static stringop_algs skylake_memcpy[2] = {
> > - {libcall, {{1024, rep_prefix_4_byte, true}, {-1, libcall, false}}},
> > - {libcall, {{16, loop, false}, {512, unrolled_loop, false},
> > - {-1, libca
On Mon, Apr 5, 2021 at 2:14 PM Jan Hubicka wrote:
>
> > > /* skylake_cost should produce code tuned for Skylake familly of CPUs.
> > > */
> > > static stringop_algs skylake_memcpy[2] = {
> > > - {libcall, {{1024, rep_prefix_4_byte, true}, {-1, libcall, false}}},
> > > - {libcall, {{16, loo
> Do you know what of the three changes (preferring reps/stosb,
> CLEAR_RATIO and algorithm choice changes) cause the two speedups
> on eebmc?
A extracted testcase from nnet_test in https://godbolt.org/z/c8KdsohTP
This loop is transformed to builtin_memcpy and builtin_memset with size 280.
Curre
> > Do you know what of the three changes (preferring reps/stosb,
> > CLEAR_RATIO and algorithm choice changes) cause the two speedups
> > on eebmc?
>
> A extracted testcase from nnet_test in https://godbolt.org/z/c8KdsohTP
>
> This loop is transformed to builtin_memcpy and builtin_memset with si
On Tue, Apr 6, 2021 at 2:51 AM Jan Hubicka wrote:
>
> > > Do you know what of the three changes (preferring reps/stosb,
> > > CLEAR_RATIO and algorithm choice changes) cause the two speedups
> > > on eebmc?
> >
> > A extracted testcase from nnet_test in https://godbolt.org/z/c8KdsohTP
> >
> > This
