Re: [RFA/DOC] record pic

[Hui Zhu <teawater@gmail.com>]

Thanks Eli.

On Wed, Aug 25, 2010 at 01:24, Eli Zaretskii <eliz@gnu.org> wrote:
>> From: Hui Zhu <teawater@gmail.com>
>> Date: Tue, 24 Aug 2010 11:19:06 +0800
>> Cc: gdb-patches@sourceware.org, brobecker@adacore.com
>>
>> >> +set record pic hide-nofunction on|off
>> >> +  The each line or each function will be show in vcg file as a node.
>> >> +  Sometime, we don't want show it.  So hide the nodes.
>> >> +  Set or show whether `record pic' hides the nodes without function
>> >> +  name.
>> >
>> > Rephrase:
>> >
>> >  Normally each line and each function will show up as a node in the
>> >  VCG file.  This command does not save nodes that correspond to
>> >  functions.
>> >
>> > Btw, you didn't answer my question what is a "node without function
>> > name".  Because of this, I'm not sure the above text I suggest is
>> > correct.  Please explain more about this.
>>
>> It like the line, if this address doesn't have the debug message, it
>> will not have the function name.
>
> When would a function lack debug info? in a stripped executable?  If
> so, what would "record pic" produce for functions that cannot be found
> in the symbol table, when hide-nofunction is OFF?

When inferior exec into a libc, it will lack debug info.
If without debug info and "hide-nofunction is OFF", record pic will
show address directly.

>
>> >> +When @var{type} is set to @code{function}, each node of vcg file that
>> >
>> > Again, "a VCG file}
>> >
>> >> +@code{record pic} saved will be a function of the inferior.
>> >                           ^^^^^^^^^^^^^^^^^^
>> > "will represent a function".
>> >
>> > Do you mean that all the lines belonging to a function will be
>> > represented by a single node?
>>
>> No.  Each line will be a special note.
>
> I'm confused.  You say that when "set record pic function" is in
> effect, each node of the VCG file will be a function.  Now you are
> saying that each line "will be a special note".  What note? and how is
> this different from "set record pic line"?

Sorry I make a mistake.  I just think you ask about "set record pic line".
When "set record pic line",each line will be a special note.
When "set record pic function", just show the function as a note, it
will not show the line.

>
> Maybe you could show a fragment of the produced VCG file under each
> option and command, so I could understand what is the effect of each
> one of them, and suggest the appropriate text for the manual.
>
>> >> +@item set record pic hide-nofunction
>> >> +The each line or each function will be show in vcg file as a node.
>> >> +Sometime, we don't want show it.  So hide the nodes.
>> >
>> > I still don't understand what this means.  Will only the function
>> > nodes hidden?  If so, do you mean that the saved nodes will represent
>> > lines, but there will be no nodes that represent functions?  How is
>> > this different from saying "set record pic line"?
>>
>> For line and function.  The node will be hide when:
>>                   /* Get the start addr of function.  */
>>                   addr = get_pc_function_start (addr);
>>                   if (addr == 0)
>>                     {
>>                       if (record_pic_hide_nofunction)
>>                         goto exec;
>> When we try to get the function start address.
>>               function = lookup_minimal_symbol_by_pc (addr);
>>               if (!function && record_pic_hide_nofunction)
>>                 goto exec;
>> And the find the function's name.
>
> This seems to say that hide-nofunction affects the situations where we
> cannot get the function's address, or couldn't find its entry in the
> symtab.  Is that right?  Is this option effective only for such
> functions?  If so, what will be produced in the VCG file when a
> function has no address or is not in the symtab, but hide-nofunction
> is OFF?

Show a address in the note.

>
> Again, a fragment from the file for each possibility would be great to
> explain to me what to write in the manual.
>
>> >> +If OFF, @code{record pic} will show the nodes that have the same
>> >> +address node in vcg file.  And @code{record pic} will show the
>> >> +instruction number in format @code{i:number} that
>> >> +@value{record goto} support.
>> >
>> > Please replace the last sentence with this:
>> >
>> >  Each node will show its instruction count in the form
>> >  @code{i:@var{num}}.
>> >
>> > Is this i:NUM display shown always, or is it shown only when nodes
>> > with identical addresses are shown individually, as opposed to
>> > collapsed into a single node?
>>
>> It always display.
>
> Then please don't tell this as part of describing hide-sameaddr OFF.
> Describe it separately, to avoid the impression that hide-sameaddr
> somehow affects the i:NUM display.

hide-sameaddr OFF, show i:NUM.

hide-sameaddr On, show c:COUNT.

>
>> I make a new one.  please help me review it.
>
> I will wait with the rest of the review until I understand the issues
> better, according to your answers to the above questions.

Best,
Hui