http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54705
Eric Botcazou <ebotcazou at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution| |WONTFIX
--- Comment #5 from Eric Botcazou <ebotcazou at gcc dot gnu.org> 2012-09-28
09:54:15 UTC ---
#2 0x00000000005628db in output_die (die=0x7fffebb91460)
at /home/eric/svn/gcc-4_7-branch/gcc/dwarf2out.c:8469
8469 gcc_assert (AT_ref (a)->die_offset);
(gdb) p debug_dwarf_die(die)
DIE 360467: DW_TAG_GNU_call_site (0x7fffebb91460)
abbrev id: 93 offset: 360467 mark: 1
DW_AT_low_pc: label: *.LVL14079
DW_AT_abstract_origin: die -> 0 (0x7fffeb8a6f00)
We have a cycle in the debug info:
(gdb) p a->dw_attr_val.v.val_die_ref.die
$25 = (dw_die_ref) 0x7fffeb8a6f00
(gdb) p a->dw_attr_val.v.val_die_ref.die->die_parent
$26 = (dw_die_ref) 0x7fffeb8c4820
(gdb) p a->dw_attr_val.v.val_die_ref.die->die_parent->die_parent
$27 = (dw_die_ref) 0x7fffeb8c4780
(gdb) p a->dw_attr_val.v.val_die_ref.die->die_parent->die_parent->die_parent
$28 = (dw_die_ref) 0x7fffeb8a6f00
(gdb) p *a->dw_attr_val.v.val_die_ref.die
$21 = {die_id = {die_symbol = 0x0, die_type_node = 0x0},
die_attr = 0x7fffeb86dc60, die_parent = 0x7fffeb8c4820,
die_child = 0x7fffeb8c4d20, die_sib = 0x7fffeb8c48c0, die_definition = 0x0,
die_offset = 0, die_abbrev = 0, die_mark = 2, die_perennial_p = 0,
decl_id = 4952, die_tag = DW_TAG_subprogram}
(gdb) p *a->dw_attr_val.v.val_die_ref.die->die_parent
$22 = {die_id = {die_symbol = 0x0, die_type_node = 0x0},
die_attr = 0x7fffeb8c1528, die_parent = 0x7fffeb8c4780,
die_child = 0x7fffeb8c4be0, die_sib = 0x7fffeb8c47d0, die_definition = 0x0,
die_offset = 0, die_abbrev = 0, die_mark = 2, die_perennial_p = 0,
decl_id = 0, die_tag = DW_TAG_lexical_block}
(gdb) p *a->dw_attr_val.v.val_die_ref.die->die_parent->die_parent
$23 = {die_id = {die_symbol = 0x0, die_type_node = 0x0},
die_attr = 0x7fffeb8c6360, die_parent = 0x7fffeb8a6f00,
die_child = 0x7fffeb8c4820, die_sib = 0x7fffeb8c4d20, die_definition = 0x0,
die_offset = 0, die_abbrev = 0, die_mark = 2, die_perennial_p = 0,
decl_id = 0, die_tag = DW_TAG_inlined_subroutine}
(gdb) p *a->dw_attr_val.v.val_die_ref.die->die_parent->die_parent->die_parent
$24 = {die_id = {die_symbol = 0x0, die_type_node = 0x0},
die_attr = 0x7fffeb86dc60, die_parent = 0x7fffeb8c4820,
die_child = 0x7fffeb8c4d20, die_sib = 0x7fffeb8c48c0, die_definition = 0x0,
die_offset = 0, die_abbrev = 0, die_mark = 2, die_perennial_p = 0,
decl_id = 4952, die_tag = DW_TAG_subprogram}
That's the usual mess with inlined nested subprograms, see
http://gcc.gnu.org/ml/gcc-patches/2012-03/msg00161.html
for a discussion and LTO further screws things up.
Sorting this out properly is probably impossible, so here are 2 workarounds:
1. This patchlet:
Index: dwarf2out.c
===================================================================
--- dwarf2out.c (revision 191561)
+++ dwarf2out.c (working copy)
@@ -17193,7 +17193,7 @@ gen_call_site_die (tree decl, dw_die_ref
dw_die_ref tdie = lookup_decl_die (SYMBOL_REF_DECL
(ca_loc->symbol_ref));
if (tdie)
add_AT_die_ref (die, DW_AT_abstract_origin, tdie);
- else
+ else if (!in_lto_p)
add_AT_addr (die, DW_AT_abstract_origin, ca_loc->symbol_ref);
}
return die;
works around 3 different crashes with -flto -g for Ada programs I know of.
For some reason, the new DW_TAG_GNU_call_site stuff has made things worse.
2. Do a canonical LTO bootstrap, i.e. add --with-build-config=bootstrap-lto to
the configure line and remove -flto from BOOT_CFLAGS.
