linux-kernel - Re: [PATCH 08/48] perf dwarf-aux: Factor out __die_get

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Message-Id: <20231105180732.f3483276b09360267e6d6fbb@kernel.org>
Date:   Sun, 5 Nov 2023 18:07:32 +0900
From:   Masami Hiramatsu (Google) <mhiramat@...nel.org>
To:     Namhyung Kim <namhyung@...nel.org>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Ingo Molnar <mingo@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-perf-users@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Stephane Eranian <eranian@...gle.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        linux-toolchains@...r.kernel.org, linux-trace-devel@...r.kernel.org
Subject: Re: [PATCH 08/48] perf dwarf-aux: Factor out __die_get_typename()

On Wed, 11 Oct 2023 20:50:31 -0700
Namhyung Kim <namhyung@...nel.org> wrote:

> The __die_get_typename() is to get the name of the given DIE in C-style
> type name.  The difference from the die_get_typename() is that it does
> not retrieve the DW_AT_type and use the given DIE directly.  This will
> be used when users know the type DIE already.

Hmm, I would rather like to have another name for this function.
What about 'die_get_typename_from_type()' ?

> 
> Cc: Masami Hiramatsu <mhiramat@...nel.org>
> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> ---
>  tools/perf/util/dwarf-aux.c | 38 ++++++++++++++++++++++++++-----------
>  tools/perf/util/dwarf-aux.h |  3 +++
>  2 files changed, 30 insertions(+), 11 deletions(-)
> 
> diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
> index 652e6e7368a2..5bb05c84d249 100644
> --- a/tools/perf/util/dwarf-aux.c
> +++ b/tools/perf/util/dwarf-aux.c
> @@ -1051,32 +1051,28 @@ Dwarf_Die *die_find_member(Dwarf_Die *st_die, const char *name,
>  }
>  
>  /**
> - * die_get_typename - Get the name of given variable DIE
> - * @vr_die: a variable DIE
> + * __die_get_typename - Get the name of given type DIE
> + * @type: a type DIE
>   * @buf: a strbuf for result type name
>   *
> - * Get the name of @vr_die and stores it to @buf. Return 0 if succeeded.
> + * Get the name of @type_die and stores it to @buf. Return 0 if succeeded.
>   * and Return -ENOENT if failed to find type name.
>   * Note that the result will stores typedef name if possible, and stores
>   * "*(function_type)" if the type is a function pointer.
>   */
> -int die_get_typename(Dwarf_Die *vr_die, struct strbuf *buf)
> +int __die_get_typename(Dwarf_Die *type, struct strbuf *buf)

Could you use 'type_die' instead of 'type' if it is exposed?

Thank you,

>  {
> -	Dwarf_Die type;
>  	int tag, ret;
>  	const char *tmp = "";
>  
> -	if (__die_get_real_type(vr_die, &type) == NULL)
> -		return -ENOENT;
> -
> -	tag = dwarf_tag(&type);
> +	tag = dwarf_tag(type);
>  	if (tag == DW_TAG_array_type || tag == DW_TAG_pointer_type)
>  		tmp = "*";
>  	else if (tag == DW_TAG_subroutine_type) {
>  		/* Function pointer */
>  		return strbuf_add(buf, "(function_type)", 15);
>  	} else {
> -		const char *name = dwarf_diename(&type);
> +		const char *name = dwarf_diename(type);
>  
>  		if (tag == DW_TAG_union_type)
>  			tmp = "union ";
> @@ -1089,7 +1085,7 @@ int die_get_typename(Dwarf_Die *vr_die, struct strbuf *buf)
>  		/* Write a base name */
>  		return strbuf_addf(buf, "%s%s", tmp, name ?: "");
>  	}
> -	ret = die_get_typename(&type, buf);
> +	ret = die_get_typename(type, buf);
>  	if (ret < 0) {
>  		/* void pointer has no type attribute */
>  		if (tag == DW_TAG_pointer_type && ret == -ENOENT)
> @@ -1100,6 +1096,26 @@ int die_get_typename(Dwarf_Die *vr_die, struct strbuf *buf)
>  	return strbuf_addstr(buf, tmp);
>  }
>  
> +/**
> + * die_get_typename - Get the name of given variable DIE
> + * @vr_die: a variable DIE
> + * @buf: a strbuf for result type name
> + *
> + * Get the name of @vr_die and stores it to @buf. Return 0 if succeeded.
> + * and Return -ENOENT if failed to find type name.
> + * Note that the result will stores typedef name if possible, and stores
> + * "*(function_type)" if the type is a function pointer.
> + */
> +int die_get_typename(Dwarf_Die *vr_die, struct strbuf *buf)
> +{
> +	Dwarf_Die type;
> +
> +	if (__die_get_real_type(vr_die, &type) == NULL)
> +		return -ENOENT;
> +
> +	return __die_get_typename(&type, buf);
> +}
> +
>  /**
>   * die_get_varname - Get the name and type of given variable DIE
>   * @vr_die: a variable DIE
> diff --git a/tools/perf/util/dwarf-aux.h b/tools/perf/util/dwarf-aux.h
> index b6f430730bd1..574405c57d3b 100644
> --- a/tools/perf/util/dwarf-aux.h
> +++ b/tools/perf/util/dwarf-aux.h
> @@ -116,6 +116,9 @@ Dwarf_Die *die_find_variable_at(Dwarf_Die *sp_die, const char *name,
>  Dwarf_Die *die_find_member(Dwarf_Die *st_die, const char *name,
>  			   Dwarf_Die *die_mem);
>  
> +/* Get the name of given type DIE */
> +int __die_get_typename(Dwarf_Die *type, struct strbuf *buf);
> +
>  /* Get the name of given variable DIE */
>  int die_get_typename(Dwarf_Die *vr_die, struct strbuf *buf);
>  
> -- 
> 2.42.0.655.g421f12c284-goog
> 


-- 
Masami Hiramatsu (Google) <mhiramat@...nel.org>