[PATCH 2/3] aarch64: Optimized memchr specific to AmpereComputing emag

[Siddhesh Poyarekar]

On 18/12/18 3:37 PM, Feng Xue wrote:
> This version uses general register based memory instruction to load
> data, because vector register based is slightly slower in emag.
> 
> Character-matching is performed on 16-byte (both size and alignment)
> memory block in parallel each iteration.
> 
>      * sysdeps/aarch64/memchr.S (__memchr): Rename to MEMCHR.
>      [!MEMCHR](MEMCHR): Set to __memchr.
>      * sysdeps/aarch64/multiarch/Makefile (sysdep_routines):
>      Add memchr_generic and memchr_base.
>      * sysdeps/aarch64/multiarch/ifunc-impl-list.c
>      (__libc_ifunc_impl_list): Add memchr ifuncs.
>      * sysdeps/aarch64/multiarch/memchr.c: New file.
>      * sysdeps/aarch64/multiarch/memchr_generic.S: Likewise.
>      * sysdeps/aarch64/multiarch/memchr_base.S: Likewise.
> ---
>   ChangeLog                                   |  12 ++
>   sysdeps/aarch64/memchr.S                    |  10 +-
>   sysdeps/aarch64/multiarch/Makefile          |   1 +
>   sysdeps/aarch64/multiarch/ifunc-impl-list.c |   3 +
>   sysdeps/aarch64/multiarch/memchr.c          |  41 +++++
>   sysdeps/aarch64/multiarch/memchr_base.S     | 223 ++++++++++++++++++++++++++++
>   sysdeps/aarch64/multiarch/memchr_generic.S  |  33 ++++
>   7 files changed, 320 insertions(+), 3 deletions(-)
>   create mode 100644 sysdeps/aarch64/multiarch/memchr.c
>   create mode 100644 sysdeps/aarch64/multiarch/memchr_base.S
>   create mode 100644 sysdeps/aarch64/multiarch/memchr_generic.S
> 
> diff --git a/ChangeLog b/ChangeLog
> index b4c07e2..6386b1e 100644
> --- a/ChangeLog
> +++ b/ChangeLog
> @@ -1,5 +1,17 @@
>   2018-12-17  Feng Xue  <fxue@os.amperecomputing.com>
>   
> +	* sysdeps/aarch64/memchr.S (__memchr): Rename to MEMCHR.
> +	[!MEMCHR](MEMCHR): Set to __memchr.
> +	* sysdeps/aarch64/multiarch/Makefile (sysdep_routines):
> +	Add memchr_generic and memchr_base.
> +	* sysdeps/aarch64/multiarch/ifunc-impl-list.c
> +	(__libc_ifunc_impl_list): Add memchr ifuncs.
> +	* sysdeps/aarch64/multiarch/memchr.c: New file.
> +	* sysdeps/aarch64/multiarch/memchr_generic.S: Likewise.
> +	* sysdeps/aarch64/multiarch/memchr_base.S: Likewise.

Please call it something else, say, memchr_nosimd.  Looks OK otherwise.

Thanks,
Siddhesh