linux-kernel - Re: [PATCH v2 1/2] perf annotate: Handle x86 instruction suffix generally

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Date:   Thu, 25 May 2023 08:21:31 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Namhyung Kim <namhyung@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>
Cc:     Ian Rogers <irogers@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-perf-users@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Kan Liang <kan.liang@...ux.intel.com>
Subject: Re: [PATCH v2 1/2] perf annotate: Handle x86 instruction suffix
 generally

On 24/05/23 23:50, Namhyung Kim wrote:
> In AT&T asm syntax, most of x86 instructions can have size suffix like
> b, w, l or q.  Instead of adding all these instructions in the table,
> we can handle them in a general way.
> 
> For example, it can try to find an instruction as is.  If not found,
> assuming it has a suffix and it'd try again without the suffix if it's
> one of the allowed suffixes.  This way, we can reduce the instruction
> table size for duplicated entries of the same instructions with a
> different suffix.
> 
> If an instruction xyz and others like xyz<suffix> are completely
> different ones, then they both need to be listed in the table so that
> they can be found before the second attempt (without the suffix).
> 
> Signed-off-by: Namhyung Kim <namhyung@...nel.org>

Reviewed-by: Adrian Hunter <adrian.hunter@...el.com>

> ---
>  tools/perf/util/annotate.c | 22 ++++++++++++++++++++++
>  1 file changed, 22 insertions(+)
> 
> diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
> index b708bbc49c9e..7f05f2a2aa83 100644
> --- a/tools/perf/util/annotate.c
> +++ b/tools/perf/util/annotate.c
> @@ -70,6 +70,7 @@ struct arch {
>  	struct ins_ops  *(*associate_instruction_ops)(struct arch *arch, const char *name);
>  	bool		sorted_instructions;
>  	bool		initialized;
> +	const char	*insn_suffix;
>  	void		*priv;
>  	unsigned int	model;
>  	unsigned int	family;
> @@ -179,6 +180,7 @@ static struct arch architectures[] = {
>  		.init = x86__annotate_init,
>  		.instructions = x86__instructions,
>  		.nr_instructions = ARRAY_SIZE(x86__instructions),
> +		.insn_suffix = "bwlq",
>  		.objdump =  {
>  			.comment_char = '#',
>  		},
> @@ -720,6 +722,26 @@ static struct ins_ops *__ins__find(struct arch *arch, const char *name)
>  	}
>  
>  	ins = bsearch(name, arch->instructions, nmemb, sizeof(struct ins), ins__key_cmp);
> +	if (ins)
> +		return ins->ops;
> +
> +	if (arch->insn_suffix) {
> +		char tmp[32];
> +		char suffix;
> +		size_t len = strlen(name);
> +
> +		if (len == 0 || len >= sizeof(tmp))
> +			return NULL;
> +
> +		suffix = name[len - 1];
> +		if (strchr(arch->insn_suffix, suffix) == NULL)
> +			return NULL;
> +
> +		strcpy(tmp, name);
> +		tmp[len - 1] = '\0'; /* remove the suffix and check again */
> +
> +		ins = bsearch(tmp, arch->instructions, nmemb, sizeof(struct ins), ins__key_cmp);
> +	}
>  	return ins ? ins->ops : NULL;
>  }
>