On 02/07/2021 13:31, Matteo Croce wrote:

From: Matteo Croce <redacted>

Rewrite the generic memcpy() to copy a word at time, without generating
unaligned accesses.

The procedure is made of three steps:
First copy data one byte at time until the destination buffer is aligned
to a long boundary.
Then copy the data one long at time shifting the current and the next long
to compose a long at every cycle.
Finally, copy the remainder one byte at time.

This is the improvement on RISC-V:

original aligned:	 75 Mb/s
original unaligned:	 75 Mb/s
new aligned:		114 Mb/s
new unaligned:		107 Mb/s

and this the binary size increase according to bloat-o-meter:

Function     old     new   delta
memcpy        36     324    +288


Signed-off-by: Matteo Croce <redacted>
---
  lib/string.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++--
  1 file changed, 77 insertions(+), 3 deletions(-)

Doesn't arch/riscv/lib/memcpy.S also exist for an architecture
optimised version? I would have thought the lib/string.c version
was not being used?


-- 
Ben Dooks				http://www.codethink.co.uk/
Senior Engineer				Codethink - Providing Genius

https://www.codethink.co.uk/privacy.html