Re: c/4053 Re: problems debugging gcc

[Daniel Jacobowitz <drow@mvista.com>]

On Tue, Dec 04, 2001 at 05:02:14PM -0800, mike stump wrote:
> > Date: Tue, 4 Dec 2001 16:08:45 -0500
> > From: Daniel Jacobowitz <drow@mvista.com>
> > To: Neil Booth <neil@daikokuya.demon.co.uk>
> 
> > For the curious, this is the exact same problem as c/4053.
> 
> > > This happens to me very frequently; I have no idea what causes it.  I
> > > have a sneaking suspicion that this GCC bug is what the original post
> > > was about, though I'm not sure.
> 
> > Well, it isn't in the debug format code; the file information in the
> > RTL is wrong.  And there's nothing obviously incorrect about the code
> > in cb_file_change...
> 
> > Aha, I think I see it.  cb_file_change updates input_filename as it
> > reads.  Compile the testcase from the PR with a breakpoint on
> > cb_file_change and a breakpoint on emit_line_note.  If I had to guess,
> > I'd say that the problem was input_filename describing the state of the
> > lexer where it used to describe the state of the parser.  In
> > c_expand_body is the line:
> >   init_function_start (fndecl, input_filename, DECL_SOURCE_LINE (fndecl));
> 
> > DECL_SOURCE_LINE is fine.  input_filename isn't.
> 
> Ok, since you did all the hard work, test out the below, and let us
> know if it works.  Could someone else run a dejagnu run on it, then we
> can submit it for inclusion.
> 
> 2001-12-04  Mike Stump  <mrs@wrs.com>
> 
> 	* c-decl.c (c_expand_body): Use the name of the file associated
> 	with the fndecl, not the current input filename.
> 
> *** c-decl.c.~1~	Tue Dec  4 16:52:33 2001
> --- c-decl.c	Tue Dec  4 16:54:14 2001
> *************** c_expand_body (fndecl, nested_p, can_def
> *** 6889,6895 ****
>   
>     /* Initialize the RTL code for the function.  */
>     current_function_decl = fndecl;
> !   init_function_start (fndecl, input_filename, DECL_SOURCE_LINE (fndecl));
>   
>     /* This function is being processed in whole-function mode.  */
>     cfun->x_whole_function_mode_p = 1;
> --- 6889,6897 ----
>   
>     /* Initialize the RTL code for the function.  */
>     current_function_decl = fndecl;
> !   init_function_start (fndecl,
> ! 		       DECL_SOURCE_FILE (fndecl),
> ! 		       DECL_SOURCE_LINE (fndecl));
>   
>     /* This function is being processed in whole-function mode.  */
>     cfun->x_whole_function_mode_p = 1;
> --------------

I don't expect this to have any effect, and Neil seemed to confirm
that.  Every reference to the input_filename global in the front-end is
going to be similarly wrong.  See all of c-semantics, for instance.

-- 
Daniel Jacobowitz                           Carnegie Mellon University
MontaVista Software                         Debian GNU/Linux Developer