[PATCH v8 0/2] target/riscv: rvv: reduce the overhead for simple RISC-V vector unit-stride loads and stores

[Craig Blackmore]

Changes since v7:
- Fixed typo `bits` -> `bytes`
- Tuned threshold for applying the optimization
- Provided results for larger sizes requested by Max Chou

This patch provides up to 60% speedup on the `memcpy` benchmark from:

  https://github.com/embecosm/rise-rvv-tcg-qemu-tooling/tree/main/strmem-benchmarks

There is some variation in the measurements so results are attached for six runs on a single thread on an Intel(R) Xeon(R) CPU E5-2630 v4 @ 2.20GHz.

The three graphs are:

  memcpy-594c0cb1ab-128-speedup.pdf: VLEN 128

  memcpy-594c0cb1ab-1024-speedup.pdf: VLEN 1024

  memcpy-594c0cb1ab-stdlib-speedup.pdf: Scalar (to further illustrate measurement variation as this version will not touch the function modified by this patch)

Previous versions:
- v1: https://lore.kernel.org/all/20240717153040.11073-1-paolo.savini@embecosm.com/
- v2: https://lore.kernel.org/all/20241002135708.99146-1-paolo.savini@embecosm.com/
- v3: https://lore.kernel.org/all/20241014220153.196183-1-paolo.savini@embecosm.com/
- v4: https://lore.kernel.org/all/20241029194348.59574-1-paolo.savini@embecosm.com/
- v5: https://lore.kernel.org/all/20241111130324.32487-1-paolo.savini@embecosm.com/
- v6: https://lore.kernel.org/all/20241204122952.53375-1-craig.blackmore@embecosm.com/
- v7: 20241211125113.583902-1-craig.blackmore@embecosm.com/">https://lore.kernel.org/all/20241211125113.583902-1-craig.blackmore@embecosm.com/

Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Alistair Francis <alistair.francis@wdc.com>
Cc: Bin Meng <bmeng.cn@gmail.com>
Cc: Weiwei Li <liwei1518@gmail.com>
Cc: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Cc: Liu Zhiwei <zhiwei_liu@linux.alibaba.com>
Cc: Helene Chelin <helene.chelin@embecosm.com>
Cc: Nathan Egge <negge@google.com>
Cc: Max Chou <max.chou@sifive.com>
Cc: Paolo Savini <paolo.savini@embecosm.com>

Craig Blackmore (2):
  target/riscv: rvv: fix typo in vext continuous ldst function names
  target/riscv: rvv: speed up small unit-stride loads and stores

 target/riscv/vector_helper.c | 26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

-- 
2.43.0

memcpy-594c0cb1ab-graphs.tar.gz
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