On Thu, 20 Aug 2015, Richard Biener wrote:
> On Wed, 19 Aug 2015, Richard Biener wrote:
>
> > On Tue, 18 Aug 2015, Aldy Hernandez wrote:
> >
> > > On 08/18/2015 07:20 AM, Richard Biener wrote:
> > > >
> > > > This starts a series of patches (still in development) to refactor
> > > > dwarf2out.c to better cope with early debug (and LTO debug).
> > >
> > > Awesome! Thanks.
> > >
> > > > Aldyh, what other testing did you usually do for changes? Run
> > > > the gdb testsuite against the new compiler? Anything else?
> > >
> > > gdb testsuite, and make sure you test GCC with
> > > --enable-languages=all,go,ada,
> > > though the latter is mostly useful while you iron out bugs initially. I
> > > found
> > > that ultimately, the best test was C++.
> >
> > I see.
> >
> > > Pre merge I also bootstrapped the compiler and compared .debug* section
> > > sizes
> > > in object files to make sure things were within reason.
> > >
> > > > +
> > > > +static void
> > > > +vmsdbgout_early_finish (const char *filename ATTRIBUTE_UNUSED)
> > > > +{
> > > > + if (write_symbols == VMS_AND_DWARF2_DEBUG)
> > > > + (*dwarf2_debug_hooks.early_finish) (filename);
> > > > +}
> > >
> > > You can get rid of ATTRIBUTE_UNUSED now.
> >
> > Done. I've also refrained from moving
> >
> > gen_scheduled_generic_parms_dies ();
> > gen_remaining_tmpl_value_param_die_attribute ();
> >
> > for now as that causes regressions I have to investigate.
>
> So I thought gen_scheduled_generic_parms_dies was fine but it exposes
> a hole in
>
> /* Generate early debug for global variables. Any local variables will
> be handled by either handling reachable functions from
> finalize_compilation_unit (and by consequence, locally scoped
> symbols), or by rest_of_type_compilation below.
> ...
> && !decl_type_context (decl))
> (*debug_hooks->early_global_decl) (decl);
>
> for __timepunct_cache::_S_timezones where through the
> rest_of_type_compilation we quickly finish processing __timepunct_cache
> as it is TYPE_DECL_SUPPRESS_DEBUG (so ->type_decl exits w/o doing
> anything). So we fail to generate a type DIE for the global which
> causes us, at late_global_decl time (we do output this global var)
> ends up doing
>
> #12 0x0000000000b831f1 in gen_decl_die (decl=0x7ffff5650a20, origin=0x0,
> context_die=0x7ffff62ab000)
> at /space/rguenther/src/svn/trunk/gcc/dwarf2out.c:21535
> 21532 /* And its containing type. */
> 21533 class_origin = decl_class_context (decl_or_origin);
> 21534 if (class_origin != NULL_TREE)
> 21535 gen_type_die_for_member (class_origin, decl_or_origin,
> context_die);
>
> and thus create the type DIE for __timepunct_cache late.
>
> This is a hole in current early-debug. IMHO we should force
> early_global_decl even for globals in decl_type_context ()
> or at least for a type DIE to be created for TYPE_DECL_SUPPRESS_DEBUG
> type decls.
>
> Jason, any advice on this? I note
>
> /* In a TYPE_DECL nonzero means the detail info about this type is not
> dumped
> into stabs. Instead it will generate cross reference ('x') of names.
> This uses the same flag as DECL_EXTERNAL. */
> #define TYPE_DECL_SUPPRESS_DEBUG(NODE) \
> (TYPE_DECL_CHECK (NODE)->decl_common.decl_flag_1)
>
> refering to STABS and "This uses the same flag as DECL_EXTERNAL" so
> maybe this is just bad co-incidence? DECL_EXTERNAL doesn't check
> it operates on a non-TYPE_DECL.
>
> So without knowing that the flag is supposed to be doing in DWARF
> (also the desired effect on any of its static members) I can only
> suggest we maybe do not want any debug info for
> __timepunct_cache::_S_timezones at all?
Sorry to followup myself all the time ;) The following seems to
"work" for me here:
Index: gcc/dwarf2out.c
===================================================================
--- gcc/dwarf2out.c (revision 226937)
+++ gcc/dwarf2out.c (working copy)
@@ -21647,7 +21652,8 @@ dwarf2out_late_global_decl (tree decl)
Skip over functions because they were handled by the
debug_hooks->function_decl() call in rest_of_handle_final. */
if ((TREE_CODE (decl) != FUNCTION_DECL || !DECL_INITIAL (decl))
- && !POINTER_BOUNDS_P (decl))
+ && !POINTER_BOUNDS_P (decl)
+ && lookup_decl_die (decl) != NULL)
dwarf2out_decl (decl);
}
which basically means only annotate gloabl decls late if we
created a DIE for it early.
Kind-of makes sense. Going to test that more extensively separately.
Richard.
