From: Heiko Stuebner <heiko@sntech.de> To: palmer@rivosinc.com Cc: conor@kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, christoph.muellner@vrull.eu, ajones@ventanamicro.com, Heiko Stuebner <heiko.stuebner@vrull.eu> Subject: [PATCH 2/2] RISC-V: improve string-function assembly Date: Wed, 8 Feb 2023 23:53:28 +0100 [thread overview] Message-ID: <20230208225328.1636017-3-heiko@sntech.de> (raw) In-Reply-To: <20230208225328.1636017-1-heiko@sntech.de> From: Heiko Stuebner <heiko.stuebner@vrull.eu> Adapt the suggestions for the assembly string functions that Andrew suggested but that I didn't manage to include into the series that got applied. This includes improvements to two comments, removal of unneeded labels and moving one instruction slightly higher to contradict an explanatory comment. Suggested-by: Andrew Jones <ajones@ventanamicro.com> Signed-off-by: Heiko Stuebner <heiko.stuebner@vrull.eu> --- arch/riscv/lib/strcmp.S | 6 ++++-- arch/riscv/lib/strlen.S | 10 +++++----- arch/riscv/lib/strncmp.S | 16 +++++++--------- 3 files changed, 16 insertions(+), 16 deletions(-) diff --git a/arch/riscv/lib/strcmp.S b/arch/riscv/lib/strcmp.S index 8148b6418f61..fb186bf28f07 100644 --- a/arch/riscv/lib/strcmp.S +++ b/arch/riscv/lib/strcmp.S @@ -40,7 +40,9 @@ SYM_FUNC_START(strcmp) ret /* - * Variant of strcmp using the ZBB extension if available + * Variant of strcmp using the ZBB extension if available. + * The code was published as part of the bitmanip manual + * in Appendix A. */ #ifdef CONFIG_RISCV_ISA_ZBB strcmp_zbb: @@ -57,7 +59,7 @@ strcmp_zbb: * a1 - string2 * * Clobbers - * t0, t1, t2, t3, t4, t5 + * t0, t1, t2, t3, t4 */ or t2, a0, a1 diff --git a/arch/riscv/lib/strlen.S b/arch/riscv/lib/strlen.S index 0f9dbf93301a..898466f67000 100644 --- a/arch/riscv/lib/strlen.S +++ b/arch/riscv/lib/strlen.S @@ -96,7 +96,7 @@ strlen_zbb: * of valid bytes in this chunk. */ srli a0, t1, 3 - bgtu t3, a0, 3f + bgtu t3, a0, 2f /* Prepare for the word comparison loop. */ addi t2, t0, SZREG @@ -112,20 +112,20 @@ strlen_zbb: addi t0, t0, SZREG orc.b t1, t1 beq t1, t3, 1b -2: + not t1, t1 CZ t1, t1 + srli t1, t1, 3 - /* Get number of processed words. */ + /* Get number of processed bytes. */ sub t2, t0, t2 /* Add number of characters in the first word. */ add a0, a0, t2 - srli t1, t1, 3 /* Add number of characters in the last word. */ add a0, a0, t1 -3: +2: ret .option pop diff --git a/arch/riscv/lib/strncmp.S b/arch/riscv/lib/strncmp.S index 7940ddab2d48..e36f5a6e1b16 100644 --- a/arch/riscv/lib/strncmp.S +++ b/arch/riscv/lib/strncmp.S @@ -70,7 +70,7 @@ strncmp_zbb: li t5, -1 and t2, t2, SZREG-1 add t4, a0, a2 - bnez t2, 4f + bnez t2, 3f /* Adjust limit for fast-path. */ andi t6, t4, -SZREG @@ -114,23 +114,21 @@ strncmp_zbb: ret /* Simple loop for misaligned strings. */ -3: - /* Restore limit for slow-path. */ .p2align 3 -4: - bge a0, t4, 6f +3: + bge a0, t4, 5f lbu t0, 0(a0) lbu t1, 0(a1) addi a0, a0, 1 addi a1, a1, 1 - bne t0, t1, 5f - bnez t0, 4b + bne t0, t1, 4f + bnez t0, 3b -5: +4: sub a0, t0, t1 ret -6: +5: li a0, 0 ret -- 2.39.0
WARNING: multiple messages have this Message-ID (diff)
From: Heiko Stuebner <heiko@sntech.de> To: palmer@rivosinc.com Cc: conor@kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, christoph.muellner@vrull.eu, ajones@ventanamicro.com, Heiko Stuebner <heiko.stuebner@vrull.eu> Subject: [PATCH 2/2] RISC-V: improve string-function assembly Date: Wed, 8 Feb 2023 23:53:28 +0100 [thread overview] Message-ID: <20230208225328.1636017-3-heiko@sntech.de> (raw) In-Reply-To: <20230208225328.1636017-1-heiko@sntech.de> From: Heiko Stuebner <heiko.stuebner@vrull.eu> Adapt the suggestions for the assembly string functions that Andrew suggested but that I didn't manage to include into the series that got applied. This includes improvements to two comments, removal of unneeded labels and moving one instruction slightly higher to contradict an explanatory comment. Suggested-by: Andrew Jones <ajones@ventanamicro.com> Signed-off-by: Heiko Stuebner <heiko.stuebner@vrull.eu> --- arch/riscv/lib/strcmp.S | 6 ++++-- arch/riscv/lib/strlen.S | 10 +++++----- arch/riscv/lib/strncmp.S | 16 +++++++--------- 3 files changed, 16 insertions(+), 16 deletions(-) diff --git a/arch/riscv/lib/strcmp.S b/arch/riscv/lib/strcmp.S index 8148b6418f61..fb186bf28f07 100644 --- a/arch/riscv/lib/strcmp.S +++ b/arch/riscv/lib/strcmp.S @@ -40,7 +40,9 @@ SYM_FUNC_START(strcmp) ret /* - * Variant of strcmp using the ZBB extension if available + * Variant of strcmp using the ZBB extension if available. + * The code was published as part of the bitmanip manual + * in Appendix A. */ #ifdef CONFIG_RISCV_ISA_ZBB strcmp_zbb: @@ -57,7 +59,7 @@ strcmp_zbb: * a1 - string2 * * Clobbers - * t0, t1, t2, t3, t4, t5 + * t0, t1, t2, t3, t4 */ or t2, a0, a1 diff --git a/arch/riscv/lib/strlen.S b/arch/riscv/lib/strlen.S index 0f9dbf93301a..898466f67000 100644 --- a/arch/riscv/lib/strlen.S +++ b/arch/riscv/lib/strlen.S @@ -96,7 +96,7 @@ strlen_zbb: * of valid bytes in this chunk. */ srli a0, t1, 3 - bgtu t3, a0, 3f + bgtu t3, a0, 2f /* Prepare for the word comparison loop. */ addi t2, t0, SZREG @@ -112,20 +112,20 @@ strlen_zbb: addi t0, t0, SZREG orc.b t1, t1 beq t1, t3, 1b -2: + not t1, t1 CZ t1, t1 + srli t1, t1, 3 - /* Get number of processed words. */ + /* Get number of processed bytes. */ sub t2, t0, t2 /* Add number of characters in the first word. */ add a0, a0, t2 - srli t1, t1, 3 /* Add number of characters in the last word. */ add a0, a0, t1 -3: +2: ret .option pop diff --git a/arch/riscv/lib/strncmp.S b/arch/riscv/lib/strncmp.S index 7940ddab2d48..e36f5a6e1b16 100644 --- a/arch/riscv/lib/strncmp.S +++ b/arch/riscv/lib/strncmp.S @@ -70,7 +70,7 @@ strncmp_zbb: li t5, -1 and t2, t2, SZREG-1 add t4, a0, a2 - bnez t2, 4f + bnez t2, 3f /* Adjust limit for fast-path. */ andi t6, t4, -SZREG @@ -114,23 +114,21 @@ strncmp_zbb: ret /* Simple loop for misaligned strings. */ -3: - /* Restore limit for slow-path. */ .p2align 3 -4: - bge a0, t4, 6f +3: + bge a0, t4, 5f lbu t0, 0(a0) lbu t1, 0(a1) addi a0, a0, 1 addi a1, a1, 1 - bne t0, t1, 5f - bnez t0, 4b + bne t0, t1, 4f + bnez t0, 3b -5: +4: sub a0, t0, t1 ret -6: +5: li a0, 0 ret -- 2.39.0 _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv
next prev parent reply other threads:[~2023-02-08 22:53 UTC|newest] Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-02-08 22:53 [PATCH 0/2] Small fixups for the Zbb string functions Heiko Stuebner 2023-02-08 22:53 ` Heiko Stuebner 2023-02-08 22:53 ` [PATCH 1/2] RISC-V: fix ordering of Zbb extension Heiko Stuebner 2023-02-08 22:53 ` Heiko Stuebner 2023-02-08 23:20 ` Conor Dooley 2023-02-08 23:20 ` Conor Dooley 2023-02-08 23:26 ` Heiko Stübner 2023-02-08 23:26 ` Heiko Stübner 2023-02-09 8:25 ` Andrew Jones 2023-02-09 8:25 ` Andrew Jones 2023-02-09 9:03 ` Conor Dooley 2023-02-09 9:03 ` Conor Dooley 2023-02-09 9:28 ` Andrew Jones 2023-02-09 9:28 ` Andrew Jones 2023-02-09 8:23 ` Andrew Jones 2023-02-09 8:23 ` Andrew Jones 2023-02-08 22:53 ` Heiko Stuebner [this message] 2023-02-08 22:53 ` [PATCH 2/2] RISC-V: improve string-function assembly Heiko Stuebner 2023-02-09 8:25 ` Andrew Jones 2023-02-09 8:25 ` Andrew Jones 2023-02-10 20:49 ` [PATCH 0/2] Small fixups for the Zbb string functions Conor Dooley 2023-02-10 20:49 ` Conor Dooley 2023-02-22 15:00 ` patchwork-bot+linux-riscv 2023-02-22 15:00 ` patchwork-bot+linux-riscv 2023-02-28 20:51 ` (subset) " Palmer Dabbelt 2023-02-28 20:51 ` Palmer Dabbelt 2023-02-28 21:11 ` patchwork-bot+linux-riscv 2023-02-28 21:11 ` patchwork-bot+linux-riscv
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20230208225328.1636017-3-heiko@sntech.de \ --to=heiko@sntech.de \ --cc=ajones@ventanamicro.com \ --cc=christoph.muellner@vrull.eu \ --cc=conor@kernel.org \ --cc=heiko.stuebner@vrull.eu \ --cc=linux-kernel@vger.kernel.org \ --cc=linux-riscv@lists.infradead.org \ --cc=palmer@rivosinc.com \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.