http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48508
Richard Guenther <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jason at gcc dot gnu.org
--- Comment #7 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-12-09
13:17:47 UTC ---
(gdb) call debug_dwarf_die (die)
DIE 459: DW_TAG_formal_parameter (0x7ffff5befdc0)
abbrev id: 22 offset: 459 mark: 1
DW_AT_abstract_origin: die -> 0 (0x7ffff5bef730)
DW_AT_location: location descriptor
(gdb) call debug_dwarf_die (0x7ffff5bef730)
DIE 0: DW_TAG_formal_parameter (0x7ffff5bef730)
abbrev id: 0 offset: 0 mark: 2
DW_AT_name: "cx"
DW_AT_decl_file: "jsatom.3.ii" (1)
DW_AT_decl_line: 58
DW_AT_type: die -> 287 (0x7ffff5bebc30)
So the question is why was that DIE not output. The answer is possibly
because dwarf2out.c would do so only when a proper debug hook is called
from the frontend.
The DIE get's generated via
#0 gen_formal_parameter_die (node=0x7ffff5b6f5d8, origin=0x0,
emit_name_p=1 '\001', context_die=0x7ffff5bf0690)
at /space/rguenther/src/svn/trunk/gcc/dwarf2out.c:16703
#1 0x000000000062e8b6 in gen_decl_die (decl=0x7ffff5b6f5d8, origin=0x0,
context_die=0x7ffff5bf0690)
at /space/rguenther/src/svn/trunk/gcc/dwarf2out.c:19576
#2 0x0000000000624ac7 in gen_subprogram_die (decl=0x7ffff5b70d00,
context_die=0x7ffff5bec410)
at /space/rguenther/src/svn/trunk/gcc/dwarf2out.c:17496
#3 0x000000000062dfac in gen_decl_die (decl=0x7ffff5b70d00, origin=0x0,
context_die=0x7ffff5bec410)
at /space/rguenther/src/svn/trunk/gcc/dwarf2out.c:19489
#4 0x000000000062f48e in dwarf2out_decl (decl=0x7ffff5b70d00)
at /space/rguenther/src/svn/trunk/gcc/dwarf2out.c:19863
#5 0x000000000062321a in dwarf2out_abstract_function (decl=0x7ffff5b70d00)
at /space/rguenther/src/svn/trunk/gcc/dwarf2out.c:16969
#6 0x000000000057316b in gimple_expand_cfg ()
at /space/rguenther/src/svn/trunk/gcc/cfgexpand.c:4654
so it was created up-front to be used by inline instances. But for some
reason we do not mark it for output even though it ends up being used.
We are creating a DIE for the same parameter again, via
#0 gen_formal_parameter_die (node=0x7ffff5b6f5d8, origin=0x0,
emit_name_p=1 '\001', context_die=0x7ffff5bf0cd0)
at /space/rguenther/src/svn/trunk/gcc/dwarf2out.c:16703
#1 0x000000000062e8b6 in gen_decl_die (decl=0x7ffff5b6f5d8, origin=0x0,
context_die=0x7ffff5bf0cd0)
at /space/rguenther/src/svn/trunk/gcc/dwarf2out.c:19576
#2 0x0000000000624ac7 in gen_subprogram_die (decl=0x7ffff5b70d00,
context_die=0x7ffff5bec410)
at /space/rguenther/src/svn/trunk/gcc/dwarf2out.c:17496
#3 0x000000000062dfac in gen_decl_die (decl=0x7ffff5b70d00, origin=0x0,
context_die=0x7ffff5bec410)
at /space/rguenther/src/svn/trunk/gcc/dwarf2out.c:19489
#4 0x000000000062f48e in dwarf2out_decl (decl=0x7ffff5b70d00)
at /space/rguenther/src/svn/trunk/gcc/dwarf2out.c:19863
#5 0x000000000062f4c9 in dwarf2out_function_decl (decl=0x7ffff5b70d00)
at /space/rguenther/src/svn/trunk/gcc/dwarf2out.c:19871
#6 0x00000000006a6b89 in rest_of_handle_final ()
at /space/rguenther/src/svn/trunk/gcc/final.c:4349
interestingly the 2nd one (not found by lookup_decl_die) is the one
that refers to the DIE in question.
Guarding it like
Index: dwarf2out.c
===================================================================
--- dwarf2out.c (revision 182154)
+++ dwarf2out.c (working copy)
@@ -19868,7 +19868,8 @@ dwarf2out_decl (tree decl)
static void
dwarf2out_function_decl (tree decl)
{
- dwarf2out_decl (decl);
+ if (!lookup_decl_die (decl))
+ dwarf2out_decl (decl);
call_arg_locations = NULL;
call_arg_loc_last = NULL;
call_site_count = -1;
fixes the ICE.
Now the question is what guarantees that this does not happen? Should we
be able to assert like
Index: dwarf2out.c
===================================================================
--- dwarf2out.c (revision 182154)
+++ dwarf2out.c (working copy)
@@ -5171,6 +5171,7 @@ equate_decl_number_to_die (tree decl, dw
void **slot;
slot = htab_find_slot_with_hash (decl_die_table, decl, decl_id, INSERT);
+ gcc_assert (!*slot || *slot == decl_die);
*slot = decl_die;
decl_die->decl_id = decl_id;
}
? That trivially asserts already at compile-time, without -flto.
Or is this an odering issue somehow and the two DIEs should have been
created in the opposite order? Or should the DIE reference have been
created inbetween the two calls?
I realize this has more questions than answers ... :/
