[PATCH][AArch64] Optimized memset

Marcus Shawcroft marcus.shawcroft@gmail.com
Fri Sep 25 14:55:00 GMT 2015


On 31 July 2015 at 16:02, Wilco Dijkstra <wdijkstr@arm.com> wrote:
> This is an optimized memset for AArch64. Memset is split into 4 main cases: small sets of up to 16
> bytes, medium of 16..96 bytes which are fully unrolled. Large memsets of more than 96 bytes align
> the destination and use an unrolled loop processing 64 bytes per iteration. Memsets of zero of more
> than 256 use the dc zva instruction, and there are faster versions for the common ZVA sizes 64 or
> 128. STP of Q registers is used to reduce codesize without loss of performance.
>
> Speedup on test-memset is 1% on Cortex-A57 and 8% on Cortex-A53. On a random test with varying sizes
> and alignment the new version is 50% faster.
>
> OK for commit?
>
> ChangeLog:
> 2015-07-31  Wilco Dijkstra  <wdijkstr@arm.com>
>
>         * sysdeps/aarch64/memset.S (__memset):
>         Rewrite of optimized memset.
>

-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

Please drop this unrelated white space change when you commit.  OK /Marcus



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