> -----Original Message-----
> From: Gcc-patches <gcc-patches-
> bounces+kyrylo.tkachov=arm....@gcc.gnu.org> On Behalf Of Christophe
> LYON via Gcc-patches
> Sent: Thursday, September 30, 2021 2:51 PM
> To: gcc-patches@gcc.gnu.org
> Subject: Re: [PATCH] aarch64: Improve size heuristic for cpymem expansion
>
>
> On 29/09/2021 12:20, Kyrylo Tkachov via Gcc-patches wrote:
> > Hi all,
> >
> > Similar to my previous patch for setmem this one does the same for the
> cpymem expansion.
> > We count the number of ops emitted and compare it against the
> alternative of just calling
> > the library function when optimising for size.
> > For the code:
> > void
> > cpy_127 (char *out, char *in)
> > {
> > __builtin_memcpy (out, in, 127);
> > }
> >
> > void
> > cpy_128 (char *out, char *in)
> > {
> > __builtin_memcpy (out, in, 128);
> > }
> >
> > we now emit a call to memcpy (with an extra MOV-immediate instruction
> for the size) instead of:
> > cpy_127(char*, char*):
> > ldp q0, q1, [x1]
> > stp q0, q1, [x0]
> > ldp q0, q1, [x1, 32]
> > stp q0, q1, [x0, 32]
> > ldp q0, q1, [x1, 64]
> > stp q0, q1, [x0, 64]
> > ldr q0, [x1, 96]
> > str q0, [x0, 96]
> > ldr q0, [x1, 111]
> > str q0, [x0, 111]
> > ret
> > cpy_128(char*, char*):
> > ldp q0, q1, [x1]
> > stp q0, q1, [x0]
> > ldp q0, q1, [x1, 32]
> > stp q0, q1, [x0, 32]
> > ldp q0, q1, [x1, 64]
> > stp q0, q1, [x0, 64]
> > ldp q0, q1, [x1, 96]
> > stp q0, q1, [x0, 96]
> > ret
> >
> > which is a clear code size win. Speed optimisation heuristics remain
> unchanged.
> > Bootstrapped and tested on aarch64-none-linux-gnu.
> > Pushing to trunk.
> >
> > Thanks,
> > Kyrill
> >
> > 2021-09-29 Kyrylo Tkachov <kyrylo.tkac...@arm.com>
> >
> > * config/aarch64/aarch64.c (aarch64_expand_cpymem): Count
> number of
> > emitted operations and adjust heuristic for code size.
> >
> > 2021-09-29 Kyrylo Tkachov <kyrylo.tkac...@arm.com>
> >
> > * gcc.target/aarch64/cpymem-size.c: New test.
>
>
> Hi Kyrill,
>
> Just to mention that the new test fails with -mabi=ilp32...
Drat, thanks for letting me know.
Pushing fix to trunk.
Kyrill
gcc/testsuite/
* gcc.target/aarch64/cpymem-size.c: Adjust scan for ilp32.
>
>
> Thanks,
>
>
> Christophe
>
>
test.patch
Description: test.patch
