From: Pincheng Wang <pincheng.plct@isrc.iscas.ac.cn>
To: musl@lists.openwall.com
Cc: pincheng.plct@isrc.iscas.ac.cn
Subject: [musl] [PATCH v2 0/1] riscv64: add optimized string functions
Date: Wed, 19 Nov 2025 13:40:58 +0800 [thread overview]
Message-ID: <20251119054059.514848-1-pincheng.plct@isrc.iscas.ac.cn> (raw)
Hi all,
This patch series supersedes my previous RVV-optimized memset patch
series, now extending support to memmove and memcpy as well. It provides
optimized versions of these string functions for RISC-V with vector
extension, dispatching at runtime based on CPU capability (RVV support).
Changes from v1:
- Change function pointers' attribute from hidden to static.
- Change conditional compilation condition from __riscv to __riscv &&
__riscv_xlen==64.
Implementation details:
- mem{set,cpy,move}.c are renamed internally to
__mem{set,cpy,move}_scalar via macro, preserving the generic C
implementation scalar fallback.
- mem{set,cpy,move}_vector.S provide the optimized
__mem{set,cpy,move}_vector symbols.
- string_dispatch.c exports the public mem{set,cpy,move}() symbols,
which dispatches via function pointer.
- __init_riscv_string_optimizations is called in __libc_start_main to
initialize function pointers based on AT_HWCAP.
- The vector implementation uses m8 register grouping for bulk fills.
Performance:
Function Size Improvement
memset 16B 0.06%
memset 64B 49.22%
memset 256B 127.81%
memset 1KB 58.12%
memset 4KB 47.95%
memset 64KB 2.56%
memcpy 16B 0.02%
memcpy 64B 35.94%
memcpy 256B 205.10%
memcpy 1KB 126.01%
memcpy 4KB 107.71%
memcpy 64KB 36.15%
memmove_bwd 16B -0.67%
memmove_bwd 64B 47.03%
memmove_bwd 256B 207.32%
memmove_bwd 1KB 125.33%
memmove_bwd 4KB 106.72%
memmove_bwd 64KB 41.46%
Benchmarks are conducted on a Spacemit X60 CPU.
Functional behavior matches generic functions.
Thanks,
Pincheng Wang
Pincheng Wang (1):
riscv64: add optimized memset, memcpy and memmove
src/env/__libc_start_main.c | 3 ++
src/internal/libc.h | 3 ++
src/string/riscv64/memcpy.c | 4 +++
src/string/riscv64/memcpy_vector.S | 28 +++++++++++++++
src/string/riscv64/memmove.c | 4 +++
src/string/riscv64/memmove_vector.S | 52 ++++++++++++++++++++++++++++
src/string/riscv64/memset.c | 4 +++
src/string/riscv64/memset_vector.S | 29 ++++++++++++++++
src/string/riscv64/string_dispatch.c | 52 ++++++++++++++++++++++++++++
9 files changed, 179 insertions(+)
create mode 100644 src/string/riscv64/memcpy.c
create mode 100644 src/string/riscv64/memcpy_vector.S
create mode 100644 src/string/riscv64/memmove.c
create mode 100644 src/string/riscv64/memmove_vector.S
create mode 100644 src/string/riscv64/memset.c
create mode 100644 src/string/riscv64/memset_vector.S
create mode 100644 src/string/riscv64/string_dispatch.c
--
2.39.5
next reply other threads:[~2025-11-19 5:41 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-19 5:40 Pincheng Wang [this message]
2025-11-19 5:40 ` [musl] [PATCH v2 1/1] riscv64: add optimized memset, memcpy and memmove Pincheng Wang
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