linux-kernel - Re: [PATCH] lib/string.c: Disable tree-loop-distribute-patterns

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Date:   Wed, 19 Aug 2020 09:16:27 -0400
From:   Arvind Sankar <nivedita@...m.mit.edu>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Arvind Sankar <nivedita@...m.mit.edu>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        clang-built-linux <clang-built-linux@...glegroups.com>
Subject: Re: [PATCH] lib/string.c: Disable tree-loop-distribute-patterns

On Tue, Aug 18, 2020 at 08:32:58PM -0700, Linus Torvalds wrote:
> On Tue, Aug 18, 2020 at 8:04 PM Arvind Sankar <nivedita@...m.mit.edu> wrote:
> 
> > Might be worth optimizing strnlen etc with the word-at-a-time thing though.
> 
> Yeah, possibly. Except the kernel almost never uses strnlen for
> anything bigger. At least I haven't seen it very much in the profiles.

strscpy could be implemented as strnlen+memcpy. I'd think that wouldn't
be much slower, especially if strnlen is optimized and the arch has a
good implementation of memcpy?