[PATCH 0/3] RISC-V: memcpy(): align dest when misaligned access is

[Kito Cheng]

Pushed, thanks :)

On Mon, May 26, 2025 at 10:43 PM Mahmoud Abumandour
<ma.mandourr@gmail.com> wrote:
>
> Hello,
>
> Those patches were reviewed a while ago but have not been merged yet. I wanted to check if there’s anything else needed to move them forward.
>
> Thanks,
> Mahmoud
>
> On Wed, May 7, 2025 at 6:35 PM Kito Cheng <kito.cheng@gmail.com> wrote:
>>
>> LGTM, thanks for the patch :)
>>
>> On Sun, Apr 27, 2025 at 7:59 PM <ma.mandourr@gmail.com> wrote:
>> >
>> > From: Mahmoud Abumandour <ma.mandourr@gmail.com>
>> >
>> > Add a code path for when source and dest are differently aligned.
>> >
>> > If misaligned access is slow or prohibited (i.e. `__riscv_misaligned_slow` or
>> > `__riscv_misaligned_avoid` is defined), and the alignments of the source and destination are
>> > different, we align the destination to do XLEN stores. This uses only one
>> > aligned store for every four (or eight for XLEN == 64) bytes of data.
>> >
>> > This only affects the case where source and destination are differently aligned.
>> > Previously, this case was handled by copying one byte at a time. The new
>> > approach significantly reduces the number of executed (dynamic) instructions
>> > (30% weighted average for `-mstrict-align`, while not affecting
>> > `-mno-strict-align`, which is expected).
>> >
>> > A comparison between the implementations with raw numbers is posted here:
>> >     https://docs.google.com/spreadsheets/d/1KDnfhYVFQYIXb23LjsgWFyWna4A_9mcRZRLm_u0zELE/edit?usp=sharing
>> >
>> > While at it, the function is generally improved to use `uintxlen_t` and
>> > eliminate gotos and macros.
>> >
>> > Mahmoud Abumandour (3):
>> >   RISC-V: memcpy() Use uintxlen_t for xlen-sized copy
>> >   RISC-V: memcpy() Use inline functions instead of macros and gotos
>> >   RISC-V: memcpy() align dest when misaligned access is prohibited
>> >
>> >  newlib/libc/machine/riscv/memcpy.c | 163 +++++++++++++++++++----------
>> >  1 file changed, 109 insertions(+), 54 deletions(-)
>> >
>> > --
>> > 2.43.0
>> >