Date: Sun, 30 Nov 2025 01:45:50 +0000 From: Robert Clausecker <fuz@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Cc: Strahinja =?utf-8?Q?Stani=C5=A1?==?utf-8?Q?i=C4=87?= <strajabot@FreeBSD.org> Subject: git: 2d205cdb41e3 - stable/15 - libc: scalar memset() in RISC-V assembly Message-ID: <692ba1ce.28660.7af4e31b@gitrepo.freebsd.org>
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The branch stable/15 has been updated by fuz: URL: https://cgit.FreeBSD.org/src/commit/?id=2d205cdb41e375ab5fcdab9233439aec75eeebd6 commit 2d205cdb41e375ab5fcdab9233439aec75eeebd6 Author: Strahinja Stanišić <strajabot@FreeBSD.org> AuthorDate: 2024-06-21 15:43:45 +0000 Commit: Robert Clausecker <fuz@FreeBSD.org> CommitDate: 2025-11-30 00:43:05 +0000 libc: scalar memset() in RISC-V assembly Adds scalar implementation of memset for RISC-V and updates the relevant manpage os: FreeBSD arch: riscv │ ./results/memset/memset_baseline │ ./results/memset/memset_scalar │ │ sec/op │ sec/op vs base │ 40 527.5µ ± 1% 479.4µ ± 1% -9.12% (p=0.000 n=20) 168 254.5µ ± 1% 216.7µ ± 1% -14.86% (p=0.000 n=20) 2k 169.5µ ± 1% 128.4µ ± 0% -24.24% (p=0.000 n=20) 256k 161.2µ ± 1% 118.6µ ± 1% -26.42% (p=0.000 n=20) 16m 56.58m ± 0% 53.91m ± 0% -4.72% (p=0.000 n=20) geomean 730.2µ 611.2µ -16.29% │ ./results/memset/memset_baseline │ ./results/memset/memset_scalar │ │ B/s │ B/s vs base │ 40 452.0Mi ± 1% 497.3Mi ± 1% +10.04% (p=0.000 n=20) 168 936.9Mi ± 1% 1100.4Mi ± 1% +17.45% (p=0.000 n=20) 2k 1.373Gi ± 1% 1.813Gi ± 0% +32.00% (p=0.000 n=20) 256k 1.444Gi ± 1% 1.962Gi ± 1% +35.91% (p=0.000 n=20) 16m 269.7Mi ± 0% 283.1Mi ± 0% +4.96% (p=0.000 n=20) geomean 750.1Mi 896.1Mi +19.47% MFC after: 1 month MFC to: stable/15 Approved by: mhorne, markj (mentor) Reviewed by: fuz Sponsored by: Google LLC (GSoc 2024) Differential Revision: https://reviews.freebsd.org/D45730 (cherry picked from commit 40a958d5850ddda6d863558c8b31572f700d53ca) --- lib/libc/riscv/string/Makefile.inc | 1 + lib/libc/riscv/string/memset.S | 95 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 96 insertions(+) diff --git a/lib/libc/riscv/string/Makefile.inc b/lib/libc/riscv/string/Makefile.inc index cdbc19d286fc..44aeb65bf1f7 100644 --- a/lib/libc/riscv/string/Makefile.inc +++ b/lib/libc/riscv/string/Makefile.inc @@ -1,3 +1,4 @@ MDSRCS+= \ memchr.S \ + memset.S \ strrchr.S diff --git a/lib/libc/riscv/string/memset.S b/lib/libc/riscv/string/memset.S new file mode 100644 index 000000000000..ca435dfdd5c1 --- /dev/null +++ b/lib/libc/riscv/string/memset.S @@ -0,0 +1,95 @@ +/*- + * SPDX-License-Identifier: BSD-2-Clause + * + * Copyright (c) 2024 Strahinja Stanisic <strajabot@FreeBSD.org> + */ + +#include <machine/asm.h> + +/* + * register a0 - void *dest + * register a1 - int c + * register a2 - size_t len + */ +ENTRY(memset) + andi a1, a1, 0xFF + + sltiu t1, a2, 8 + mv t0, a0 + bnez t1, .Lend + + li t1, 0x0101010101010101 + mul a1, a1, t1 + + andi t1, a0, 0b111 + andi t0, a0, ~0b111 + + beqz t1, .Lloop_store_64 + + la t2, .Lduff_start + slli t3, t1, 2 + add t2, t2, t3 + jr -4(t2) +.Lduff_start: + sb a1, 1(t0) + sb a1, 2(t0) + sb a1, 3(t0) + sb a1, 4(t0) + sb a1, 5(t0) + sb a1, 6(t0) + sb a1, 7(t0) + + /* a3 = a3 -(8-a) <=> a3 = a3 + (a-8) */ + addi t1, t1, -8 + add a2, a2, t1 + addi t0, t0, 8 + +.Lloop_store_64: + slti t1, a2, 64 + bnez t1, .Lstore_rest + sd a1, 0(t0) + sd a1, 8(t0) + sd a1, 16(t0) + sd a1, 24(t0) + sd a1, 32(t0) + sd a1, 40(t0) + sd a1, 48(t0) + sd a1, 56(t0) + addi a2, a2, -64 + addi t0, t0, 64 + j .Lloop_store_64 + +.Lstore_rest: + la t2, .Lduff_rest + andi t3, a2, ~0b111 + srli t4, t3, 1 + sub t2, t2, t4 + jr t2 + sd a1, 56(t0) + sd a1, 48(t0) + sd a1, 40(t0) + sd a1, 32(t0) + sd a1, 24(t0) + sd a1, 16(t0) + sd a1, 8(t0) + sd a1, 0(t0) +.Lduff_rest: + add t0, t0, t3 + sub a2, a2, t3 + +.Lend: + slli a2, a2, 2 + la t2, .Lduff_end + sub t2, t2, a2 + jr t2 + sb a1, 6(t0) + sb a1, 5(t0) + sb a1, 4(t0) + sb a1, 3(t0) + sb a1, 2(t0) + sb a1, 1(t0) + sb a1, (t0) +.Lduff_end: + ret +END(memset) +help
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