[PATCH] perf dwarf-aux: Print array type name with "[]"

[PATCH] perf dwarf-aux: Print array type name with "[]"

[Namhyung Kim]

It's confusing both pointers and arrays are printed as *.  Let's print
array types with [] so that we can identify them easily.  Although it's
interchangable, sometimes it can cause confusion with size like in the
below example.

Note that it is not the same with C syntax where it goes to the variable
names, but we want to have it in the type names (like in Go language).

Before:
  mov [20] 0x68(reg5) -> reg0 type='struct page**' size=0x80 (die:0x4e61d32)

After:
  mov [20] 0x68(reg5) -> reg0 type='struct page*[]' size=0x80 (die:0x4e61d32)

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/util/dwarf-aux.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
index c0a492e65388..ec988f294497 100644
--- a/tools/perf/util/dwarf-aux.c
+++ b/tools/perf/util/dwarf-aux.c
@@ -1110,8 +1110,10 @@ int die_get_typename_from_type(Dwarf_Die *type_die, struct strbuf *buf)
 	const char *tmp = "";
 
 	tag = dwarf_tag(type_die);
-	if (tag == DW_TAG_array_type || tag == DW_TAG_pointer_type)
+	if (tag == DW_TAG_pointer_type)
 		tmp = "*";
+	else if (tag == DW_TAG_array_type)
+		tmp = "[]";
 	else if (tag == DW_TAG_subroutine_type) {
 		/* Function pointer */
 		return strbuf_add(buf, "(function_type)", 15);
-- 
2.45.0.rc1.225.g2a3ae87e7f-goog

Re: [PATCH] perf dwarf-aux: Print array type name with "[]"

[Masami Hiramatsu]

On Mon,  6 May 2024 21:13:38 -0700
Namhyung Kim <namhyung@kernel.org> wrote:

> It's confusing both pointers and arrays are printed as *.  Let's print
> array types with [] so that we can identify them easily.  Although it's
> interchangable, sometimes it can cause confusion with size like in the
> below example.
> 
> Note that it is not the same with C syntax where it goes to the variable
> names, but we want to have it in the type names (like in Go language).
> 
> Before:
>   mov [20] 0x68(reg5) -> reg0 type='struct page**' size=0x80 (die:0x4e61d32)
> 
> After:
>   mov [20] 0x68(reg5) -> reg0 type='struct page*[]' size=0x80 (die:0x4e61d32)
> 

Good improvement!

Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Thank you!

> Cc: Masami Hiramatsu <mhiramat@kernel.org>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
>  tools/perf/util/dwarf-aux.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
> index c0a492e65388..ec988f294497 100644
> --- a/tools/perf/util/dwarf-aux.c
> +++ b/tools/perf/util/dwarf-aux.c
> @@ -1110,8 +1110,10 @@ int die_get_typename_from_type(Dwarf_Die *type_die, struct strbuf *buf)
>  	const char *tmp = "";
>  
>  	tag = dwarf_tag(type_die);
> -	if (tag == DW_TAG_array_type || tag == DW_TAG_pointer_type)
> +	if (tag == DW_TAG_pointer_type)
>  		tmp = "*";
> +	else if (tag == DW_TAG_array_type)
> +		tmp = "[]";
>  	else if (tag == DW_TAG_subroutine_type) {
>  		/* Function pointer */
>  		return strbuf_add(buf, "(function_type)", 15);
> -- 
> 2.45.0.rc1.225.g2a3ae87e7f-goog
> 


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

Re: [PATCH] perf dwarf-aux: Print array type name with "[]"

[Arnaldo Carvalho de Melo]

On Wed, May 08, 2024 at 08:57:51AM +0900, Masami Hiramatsu wrote:
> On Mon,  6 May 2024 21:13:38 -0700
> Namhyung Kim <namhyung@kernel.org> wrote:
> 
> > It's confusing both pointers and arrays are printed as *.  Let's print
> > array types with [] so that we can identify them easily.  Although it's
> > interchangable, sometimes it can cause confusion with size like in the
> > below example.
> > 
> > Note that it is not the same with C syntax where it goes to the variable
> > names, but we want to have it in the type names (like in Go language).
> > 
> > Before:
> >   mov [20] 0x68(reg5) -> reg0 type='struct page**' size=0x80 (die:0x4e61d32)
> > 
> > After:
> >   mov [20] 0x68(reg5) -> reg0 type='struct page*[]' size=0x80 (die:0x4e61d32)
> > 
> 
> Good improvement!
> 
> Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Indeed,

Thanks, applied to perf-tools-next,

- Arnaldo