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

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Date:   Wed, 24 May 2023 20:41:45 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Namhyung Kim <namhyung@...nel.org>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>, 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 1/2] perf annotate: Handle x86 instruction suffix
 generally

On 24/05/23 19:10, Namhyung Kim wrote:
> Hi Adrian,
> 
> On Tue, May 23, 2023 at 11:11 PM Adrian Hunter <adrian.hunter@...el.com> wrote:
>>
>> On 24/05/23 08:28, Namhyung Kim wrote:
>>> Most of x86 instructions can have size suffix like b, w, l or q.
>>
>> (AT&T mnemonics)
> 
> Right, will update.
> 
>>
>>> 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, it'd try again without the suffix if it's one of
>>> the allowed suffixes.
>>
>> I guess it might be possible that xyz is in the table but xyz<suffix>
>> is a completely different instruction?
> 
> Then xyz<suffix> should be in the table too.  The match without
> suffix is a fallback so it should find the correct instruction first.

Right, so when adding xyz to the table, xyz<suffix> does not need
to be added as well if it is the same instruction but with different
operand sizes, but xyz<suffix> must be added as well if it is a
different instruction with different ops.

> 
> Thanks,
> Namhyung
> 
> 
>>
>>>
>>> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
>>> ---
>>>  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;
>>>  }
>>>
>>