Re: Macro code crasher on re-run

[Jim Blandy <jimb@redhat.com>]

Daniel Jacobowitz <drow@mvista.com> writes:
> On Mon, Nov 03, 2003 at 03:59:41PM -0500, Jim Blandy wrote:
> > 
> > Daniel Jacobowitz <drow@mvista.com> writes:
> > > > I don't follow.  All default_macro_scope's callers check for null
> > > > return; it's documented to return zero at times.  So you must be
> > > > talking about that code in sal_macro_scope itself.  Line 39 refers to
> > > > sal.symtab, initialized by line 115, so you must be talking about line
> > > > 40.  But sal.symtab must be non-zero, or else we wouldn't reach the
> > > > right operand of the ||.
> > > > 
> > > > Or should I sleep and try again?
> > > > 
> > > 
> > > Right.  sal.symtab is nonzero.  sal.symtab->macro_table, however, is
> > > uninitialized.  The short-circuit if on line 40 does not trigger, but
> > > the remainder of sal_macro_scope assumes that sal.symtab->macro_table
> > > is valid.
> > > 
> > > In my case it happens to be 0xB.
> > 
> > Every symtab's macro_table field should be initialized, at least to
> > zero.  Which symtab is it?  Who creates it?
> 
> If you thought I wasn't making sense, you were right.  I really needed
> some sleep when I wrote that.
> 
> My best guess is that the returned symtab belongs to the old (already
> unloaded) binary.  Which would put the bug somewhere else.

I haven't debugged it (only Daniel J. has seen the problem, as far as
I know), but I kind of suspect this change:

2003-10-22  Andrew Cagney  <cagney@redhat.com>

	* target.c (target_close): New function.
	(debug_to_close): Use "target_close".
	(push_target): Use "target_close".
	(unpush_target): Use "target_close".
	(pop_target): Use "target_close".
	* target.h (struct target_ops): Add "to_xclose".
	(target_open): Delete macro.  Move comment to "to_open".
	(target_close): Replace macro with function that takes a target.
	* top.c (quit_target): Pass "current_target" to "target_close".

The to_close method of the "exec" target calls free_objfile, which
assumes that its callers call clear_symtab_users at some appropriate
time.  This change seems to have introduced several new callers to
target_close, so it may have broken that assumption.

Having free_objfile require its callers to take care of things this
way is not very nice.