From: Andrew Jones <ajones@ventanamicro.com>
To: Heiko Stuebner <heiko@sntech.de>
Cc: linux-riscv@lists.infradead.org, palmer@dabbelt.com,
christoph.muellner@vrull.eu, conor@kernel.org,
philipp.tomsich@vrull.eu, jszhang@kernel.org,
Heiko Stuebner <heiko.stuebner@vrull.eu>
Subject: Re: [PATCH v5 2/2] RISC-V: add zbb support to string functions
Date: Fri, 20 Jan 2023 16:02:28 +0100 [thread overview]
Message-ID: <20230120150228.nexxggusemcntzoc@orel> (raw)
In-Reply-To: <20230113212301.3534711-3-heiko@sntech.de>
On Fri, Jan 13, 2023 at 10:23:01PM +0100, Heiko Stuebner wrote:
...
> diff --git a/arch/riscv/lib/strcmp.S b/arch/riscv/lib/strcmp.S
> index 8babd712b958..8148b6418f61 100644
> --- a/arch/riscv/lib/strcmp.S
> +++ b/arch/riscv/lib/strcmp.S
> @@ -3,9 +3,14 @@
> #include <linux/linkage.h>
> #include <asm/asm.h>
> #include <asm-generic/export.h>
> +#include <asm/alternative-macros.h>
> +#include <asm/errata_list.h>
>
> /* int strcmp(const char *cs, const char *ct) */
> SYM_FUNC_START(strcmp)
> +
> + ALTERNATIVE("nop", "j strcmp_zbb", 0, CPUFEATURE_ZBB, CONFIG_RISCV_ISA_ZBB)
> +
I have something similar for Zicboz (which I've just reread as I'm
preparing v2). The difference is that I opted to penalize the non-
optimized version with the unconditional jump and give the optimized
version the nop. To do that here, it'd just need the label changed to
strcmp_basic or whatever, push the "basic" code down into it the new
label, and then put the new zbb code here.
Thanks,
drew
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next prev parent reply other threads:[~2023-01-20 15:02 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-13 21:22 [PATCH v5 0/2] Zbb string optimizations Heiko Stuebner
2023-01-13 21:23 ` [PATCH v5 1/2] RISC-V: add infrastructure to allow different str* implementations Heiko Stuebner
2023-01-13 21:59 ` Conor Dooley
2023-01-13 21:23 ` [PATCH v5 2/2] RISC-V: add zbb support to string functions Heiko Stuebner
2023-01-13 22:33 ` Conor Dooley
2023-01-17 12:24 ` Andrew Jones
2023-01-20 15:02 ` Andrew Jones [this message]
2023-02-12 15:47 ` Guenter Roeck
2023-02-02 23:39 ` [PATCH v5 0/2] Zbb string optimizations Palmer Dabbelt
2023-02-03 9:53 ` Andrew Jones
2023-02-02 23:40 ` patchwork-bot+linux-riscv
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