linux-kernel - Re: [PATCH v1 1/1] vsprintf: Move space out of string literals in fourcc

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Date:   Tue, 11 Jan 2022 11:26:21 +0100
From:   Rasmus Villemoes <linux@...musvillemoes.dk>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Petr Mladek <pmladek@...e.com>, linux-kernel@...r.kernel.org
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>
Subject: Re: [PATCH v1 1/1] vsprintf: Move space out of string literals in
 fourcc_string()

On 10/01/2022 21.55, Andy Shevchenko wrote:
> The literals "big-endian" and "little-endian" may be potentially
> occurred in other places. Dropping space allows compiler to
> "compress" them by using only a single copy.

Nit: it's not the compiler which does that, but the linker.

> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index b02f01366acb..5818856d5626 100644
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -1780,7 +1780,8 @@ char *fourcc_string(char *buf, char *end, const u32 *fourcc,
>  		*p++ = isascii(c) && isprint(c) ? c : '.';
>  	}
>  
> -	strcpy(p, orig & BIT(31) ? " big-endian" : " little-endian");
> +	*p++ = ' ';
> +	strcpy(p, orig & BIT(31) ? "big-endian" : "little-endian");
>  	p += strlen(p);

Hm, ok, those two strings do occur a lot with of_property_read_bool()
and friends. But if you're micro-optimizing anyway, why not drop the
strlen() and say p = stpcpy(...) instead?
Rasmus