Re: [rfa/6.0] Fix a thinko in dwarf2loc

[Elena Zannoni <ezannoni@redhat.com>]

Daniel Jacobowitz writes:
 > On Tue, Sep 09, 2003 at 05:27:10PM -0400, Elena Zannoni wrote:
 > > Daniel Jacobowitz writes:
 > >  > On Sun, Aug 24, 2003 at 12:48:55PM -0400, Daniel Jacobowitz wrote:
 > >  > > On Sun, Aug 17, 2003 at 04:58:22PM -0400, Daniel Jacobowitz wrote:
 > >  > > > On Fri, Aug 01, 2003 at 03:32:45PM -0400, Daniel Jacobowitz wrote:
 > >  > > > > Any variable with DW_OP_reg* requires a frame to read it - what
 > >  > > > > symbol_read_needs_frame () really means is "is this variable meaningful when
 > >  > > > > the program is not running".
 > >  > > > > 
 > >  > > > > This would show up in the testsuite, but GCC doesn't tend to put locals in
 > >  > > > > registers without optimization or register keywords everywhere.  Symptom is
 > >  > > > > that a watchpoint was not deleted when we left its scope, since we thought
 > >  > > > > it was global.
 > >  > > > > 
 > >  > > > > OK?
 > >  > > > 
 > >  > > > Ping...
 > >  > > > 
 > >  > > > [Does dwarf2loc fall under the maintenance umbrella of the dwarf2
 > >  > > > reader?]
 > >  > > 
 > >  > > Ping?  I would like to fix this bug for 6.0.
 > >  > 
 > >  > Jim, Elena?  I hit this bug again in testing the
 > >  > deprecated_safe_get_selected_frame () patch.
 > >  > 
 > >  > > > > 2003-08-01  Daniel Jacobowitz  <drow@mvista.com>
 > >  > > > > 
 > >  > > > > 	* dwarf2loc.c (dwarf2_loc_desc_needs_frame): Variables in a
 > >  > > > > 	register do need a frame.
 > >  > > > > 
 > >  > > > > --- gdb-5.3.20030801/gdb/dwarf2loc.c.orig	2003-08-01 14:58:57.000000000 -0400
 > >  > > > > +++ gdb-5.3.20030801/gdb/dwarf2loc.c	2003-08-01 15:00:05.000000000 -0400
 > >  > > > > @@ -318,7 +318,7 @@ dwarf2_loc_desc_needs_frame (unsigned ch
 > >  > > > >  
 > >  > > > >    free_dwarf_expr_context (ctx);
 > >  > > > >  
 > >  > > > > -  return baton.needs_frame;
 > >  > > > > +  return baton.needs_frame || ctx->in_reg;
 > >  > > > >  }
 > >  > > > >  
 > > 
 > > Hmmm, the ctx just got freed, you cannot dereference it. Need to use a
 > 
 > Eek, I'm embarassed.  You are so right.
 > 
 > > local variable.  What you are really saying here is that the
 > > needs_frame variable is not sufficient to describe what's needed. Can
 > > the case be added, so that needs_frame becomes OK? Proabably you
 > > need another need_frame_* function.
 > 
 > No, I can't.  The needs_frame_* functions are hooks for things which
 > are external to the expression evaluator - concepts like "object" and
 > "thread local storage address" which require information.  But the
 > evaluator won't actually try to read from the register when parsing a
 > DW_OP_reg1; it just sets in_reg.

Oh, ok, I guess save ctx->in_reg in a local variable then.

elena


 > 
 > -- 
 > Daniel Jacobowitz
 > MontaVista Software                         Debian GNU/Linux Developer