Re: [External] Re: [PATCH] riscv: Improve sbi_ecall() code generation by reordering arguments

From: yunhui cui <cuiyunhui@bytedance.com>
To: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Qingfang Deng <dqfext@gmail.com>,
	aou@eecs.berkeley.edu, linux-kernel@vger.kernel.org,
	 linux-riscv@lists.infradead.org, palmer@dabbelt.com,
	paul.walmsley@sifive.com,  samuel.holland@sifive.com
Subject: Re: [External] Re: [PATCH] riscv: Improve sbi_ecall() code generation by reordering arguments
Date: Mon, 25 Mar 2024 11:59:43 +0800	[thread overview]
Message-ID: <CAEEQ3w=mXXTwxph+_ttBLQhvNb66bq9b6Wo-Ka35qpp+3iq2JQ@mail.gmail.com> (raw)
In-Reply-To: <CAHVXubisa6HQJDbj_GfjwhP1Y4as0DzrxsU0B7N6DSU6HZNaaw@mail.gmail.com>

Hi Alex,

On Mon, Mar 25, 2024 at 2:20 AM Alexandre Ghiti <alexghiti@rivosinc.com> wrote:
>
> Hi Qingfang,
>
> On Sat, Mar 23, 2024 at 7:26 AM Qingfang Deng <dqfext@gmail.com> wrote:
> >
> > Hi Alexandre,
> >
> > You can simply make sbi_ecall `__always_inline`, so the C function call
> > overhead can be fully avoided.
>
> I understand your point, though I don't think we need to mark
> sbi_ecall() as inline, it's not in any hot path so it's not worth it.
> This patch simply gets rid of a really useless overhead, but it does
> not visibly accelerate anything.
>
> I hope it makes sense,
>
> Thanks,
>
> Alex
>

The compiler will have inline size restrictions, so I agree with the
modification of this patch instead of inline.
Please refer to:
https://github.com/gcc-mirror/gcc/blob/master/gcc/common.opt,
"finline-limit-"

So：
Reviewed-by: Yunhui Cui <cuiyunhui@bytedance.com>

Thanks,
Yunhui

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