Re: [PATCH] aarch64: Optimized memcmp for medium to large sizes

[Szabolcs Nagy <szabolcs dot nagy at arm dot com>]

On 06/03/18 13:54, Siddhesh Poyarekar wrote:
> On Tuesday 06 March 2018 06:45 PM, Adhemerval Zanella wrote:
> > On 02/02/2018 02:50, Siddhesh Poyarekar wrote:
> > > This improved memcmp provides a fast path for compares up to 16 bytes
> > > and then compares 16 bytes at a time, thus optimizing loads from both
> > > sources.  The glibc memcmp microbenchmark retains performance (with an
> > > error of ~1ns) for smaller compare sizes and reduces up to 31% of
> > > execution time for compares up to 4K on the APM Mustang.  On Qualcomm
> > > Falkor this improves to almost 48%, i.e. it is almost 2x improvement
> > > for sizes of 2K and above.
> > >
> > > 	* sysdeps/aarch64/memcmp.S: Widen comparison to 16 bytes at a
> > > 	time.
> >
> > LGTM with some comments clarifications below.
>
> Thanks, fixed up and pushed.

this broke the build for me:

/B/elf/librtld.os: In function `memcmp':
/S/string/../sysdeps/aarch64/memcmp.S:78: undefined reference to `.Lloop8'
collect2: error: ld returned 1 exit status
make[2]: *** [/B/elf/ld.so] Error 1
make[2]: Leaving directory `/S/elf'