From mboxrd@z Thu Jan  1 00:00:00 1970
From: "=?ISO-8859-15?Q?Ilpo_J=E4rvinen?=" <ilpo.jarvinen-pxSi+dnQzZMxHbG02/KK1g@public.gmane.org>
Subject: Re: Formatting "drivers" was Re: Can't persuade pahole to see through
 forward declarations
Date: Wed, 24 Jun 2009 09:29:26 +0300 (EEST)
Message-ID: <Pine.LNX.4.64.0906240918170.26611@melkinkari.cs.Helsinki.FI>
References: <20090615172409.6f0f322b@mozilla.com> <20090617170217.GB21530@ghostprotocols.net>
 <20090617102506.34aaf8e2@mozilla.com> <20090618183634.GE21530@ghostprotocols.net>
 <20090618132820.2eb7371a@mozilla.com> <20090618205053.GA4258@ghostprotocols.net>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Return-path: <dwarves-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
In-Reply-To: <20090618205053.GA4258-f8uhVLnGfZaxAyOMLChx1axOck334EZe@public.gmane.org>
Sender: dwarves-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
To: Arnaldo Carvalho de Melo <acme-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Cc: Zack Weinberg <zweinberg-4eJtQOnFJqFBDgjK7y7TUQ@public.gmane.org>, dwarves-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
List-Id: dwarves@vger.kernel.org

On Thu, 18 Jun 2009, Arnaldo Carvalho de Melo wrote:

> Em Thu, Jun 18, 2009 at 01:28:20PM -0700, Zack Weinberg escreveu:
> > Arnaldo Carvalho de Melo <acme-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
> > 
> > > > Also, I wonder if you could see your way clear to adding an
> > > > alternative output format that is easily machine-parseable?
> > > > Approximation-to-C-source format is nice for humans but I've spent
> > > > the past day and a bit writing a sed script to turn it into
> > > > something that I can do programmed analysis on and it was no fun.
> > > 
> > > How would it look like?
> > 
> > For the analysis I'm doing, the ideal format would be very flat and
> > line-oriented.  Consider this structure definition:
> > 
> > struct Foo {
> >   union {
> >     struct { int x; int y; } a;
> >     struct { float z; short y; } b;
> >     double c;
> >     void* d;
> >   } u;
> >   char n[4];
> >   void (*ptr)(int);
> >   void (*ptrs[2])(int);
> >   int bf:12;
> >   short bg:3;
> > };
> > 
> > I would like to get something like this (assuming LP64):
> > 
> > name|type|bytes|bits|byteoff|bitoff|cacheline
> > Foo|struct Foo|48|0|0|0|0
> > Foo.u|union|8|0|0|0|0
> > Foo.u.a|struct|8|0|0|0|0
> > Foo.u.a.x|int|4|0|0|0|0
> > Foo.u.a.y|int|4|0|4|0|0
> > Foo.u.b|struct|8|0|0|0|0
> > Foo.u.b.z|float|4|0|0|0|0
> > Foo.u.b.y|short int|2|0|4|0|0
> > Foo.u.b.<pad>|pad|2|0|6|0|0
> > Foo.u.c|double|8|0|0|0|0
> > Foo.u.d|void *|8|0|0|0|0
> > Foo.n|char[4]|4|0|8|0|0
> > Foo.<hole1>|pad|4|0|12|0|0
> > Foo.ptr|void(*)(int)|8|0|16|0|0
> > Foo.ptrs|void(*[2])(int)|16|0|24|0|0
> > Foo.bf|int|1|4|40|0|0
> > Foo.bg|short int|0|3|41|4|0
> > Foo.<pad>|pad|6|1|41|7|0
> > 
> > I suggest "|" for the field separator because I'm pretty sure it can't
> > appear in a C/C++ "abstract declaration" (i.e. the "type" field).  Tabs
> > are visually confusable with the spaces that you do occasionally need
> > in an abstract declaration.
> > 
> > The key properties of this are:
> > 
> >  - There is only one kind of record to process.
> >  - Each line can be examined in isolation, if you don't care about the
> >    nesting structure.
> >  - You do not have to process C declaration syntax to find the name of
> >    each field.

Good point, this is one of the most complex tasks in scripts to get 
general case right. Besides typedefs, especially those function pointers 
which appear in return value and arguments make it a task too hairy 
for any sane people, not that I'd say it is impossible... :-)

> >  - There is never missing data; in many cases pahole currently will
> >    omit the offset in its annotation of a full nested structure,
> >    for instance, which is fine for humans but really bad for machine
> >    processing.
> 
> Annoying "simplification", I'll put the offset there explicitely, just
> worried that Ilpo may be using it in his sed scripts... Ilpo?

No, I'm not. I usually try to avoid trusting such things anyway, unless I 
really have to. You just don't parse anything c-like with newlines / 
spaces as significant :-).


-- 
 i.
--
To unsubscribe from this list: send the line "unsubscribe dwarves" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html