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Fix for dwz-related crash 

PR symtab/23010 reports a crash that occurs when using -readnow
on a dwz-generated debuginfo file.

The crash occurs because the DWARF has a partial CU with no language
set, and then a full CU that references this partial CU using
DW_AT_abstract_origin.

In this case, the partial CU is read by dw2_expand_all_symtabs using
language_minimal; but then this conflicts with the creation of the
block's symbol table in the C++ CU.

This patch fixes the problem by arranging for partial CUs not to be
read by -readnow.  I tend to think that it doesn't make sense to read
a partial CU in isolation -- they should only be read when imported
into some other CU.

In conjunction with some other patches I am going to post, this also
fixes the Rust -readnow crash that Jan reported.

There are two problems with this patch:

1. It is difficult to reason about.  There are many cases where I've
   patched the code to call init_cutu_and_read_dies with the flag set
   to "please do read partial units" -- but I find it difficult to be
   sure that this is always correct.

2. It is still missing a standalone test case.  This seemed hard.

2018-05-17  Tom Tromey  <tom@tromey.com>

	PR symtab/23010:
	* dwarf2read.c (load_cu, dw2_do_instantiate_symtab)
	(dw2_instantiate_symtab): Add skip_partial parameter.
	(dw2_find_last_source_symtab, dw2_map_expand_apply)
	(dw2_lookup_symbol, dw2_expand_symtabs_for_function)
	(dw2_expand_all_symtabs, dw2_expand_symtabs_with_fullname)
	(dw2_expand_symtabs_matching_one)
	(dw2_find_pc_sect_compunit_symtab)
	(dw2_debug_names_lookup_symbol)
	(dw2_debug_names_expand_symtabs_for_function): Update.
	(init_cutu_and_read_dies): Add skip_partial parameter.
	(process_psymtab_comp_unit, build_type_psymtabs_1)
	(process_skeletonless_type_unit, load_partial_comp_unit)
	(psymtab_to_symtab_1): Update.
	(load_full_comp_unit): Add skip_partial parameter.
	(process_imported_unit_die, dwarf2_read_addr_index)
	(follow_die_offset, dwarf2_fetch_die_loc_sect_off)
	(dwarf2_fetch_constant_bytes, dwarf2_fetch_die_type_sect_off)
	(read_signatured_type): Update.
This commit is contained in:
Tom Tromey 2018-04-12 08:24:41 -06:00
parent 809276d28a
commit 58f0c71853
2 changed files with 67 additions and 34 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
gdb/ChangeLog
View File

@ -1,3 +1,25 @@
2018-05-17 Tom Tromey <tom@tromey.com>
PR symtab/23010:
* dwarf2read.c (load_cu, dw2_do_instantiate_symtab)
(dw2_instantiate_symtab): Add skip_partial parameter.
(dw2_find_last_source_symtab, dw2_map_expand_apply)
(dw2_lookup_symbol, dw2_expand_symtabs_for_function)
(dw2_expand_all_symtabs, dw2_expand_symtabs_with_fullname)
(dw2_expand_symtabs_matching_one)
(dw2_find_pc_sect_compunit_symtab)
(dw2_debug_names_lookup_symbol)
(dw2_debug_names_expand_symtabs_for_function): Update.
(init_cutu_and_read_dies): Add skip_partial parameter.
(process_psymtab_comp_unit, build_type_psymtabs_1)
(process_skeletonless_type_unit, load_partial_comp_unit)
(psymtab_to_symtab_1): Update.
(load_full_comp_unit): Add skip_partial parameter.
(process_imported_unit_die, dwarf2_read_addr_index)
(follow_die_offset, dwarf2_fetch_die_loc_sect_off)
(dwarf2_fetch_constant_bytes, dwarf2_fetch_die_type_sect_off)
(read_signatured_type): Update.
2018-05-17 Simon Marchi <simon.marchi@ericsson.com>
* value.c (release_value): Remove unused variable.

79
gdb/dwarf2read.c
View File

@ -1832,7 +1832,7 @@ static void create_all_comp_units (struct dwarf2_per_objfile *dwarf2_per_objfile
static int create_all_type_units (struct dwarf2_per_objfile *dwarf2_per_objfile);
static void load_full_comp_unit (struct dwarf2_per_cu_data *,
static void load_full_comp_unit (struct dwarf2_per_cu_data *, bool,
enum language);
static void process_full_comp_unit (struct dwarf2_per_cu_data *,
@ -1932,7 +1932,7 @@ static const gdb_byte *read_and_check_comp_unit_head
static void init_cutu_and_read_dies
(struct dwarf2_per_cu_data *this_cu, struct abbrev_table *abbrev_table,
int use_existing_cu, int keep,
int use_existing_cu, int keep, bool skip_partial,
die_reader_func_ftype *die_reader_func, void *data);
static void init_cutu_and_read_dies_simple
@ -2835,12 +2835,12 @@ create_quick_file_names_table (unsigned int nr_initial_entries)
processing PER_CU->CU. dw2_setup must have been already called. */
static void
load_cu (struct dwarf2_per_cu_data *per_cu)
load_cu (struct dwarf2_per_cu_data *per_cu, bool skip_partial)
{
if (per_cu->is_debug_types)
load_full_type_unit (per_cu);
else
load_full_comp_unit (per_cu, language_minimal);
load_full_comp_unit (per_cu, skip_partial, language_minimal);
if (per_cu->cu == NULL)
return; /* Dummy CU. */
@ -2851,7 +2851,7 @@ load_cu (struct dwarf2_per_cu_data *per_cu)
/* Read in the symbols for PER_CU. */
static void
dw2_do_instantiate_symtab (struct dwarf2_per_cu_data *per_cu)
dw2_do_instantiate_symtab (struct dwarf2_per_cu_data *per_cu, bool skip_partial)
{
struct dwarf2_per_objfile *dwarf2_per_objfile = per_cu->dwarf2_per_objfile;
@ -2870,7 +2870,7 @@ dw2_do_instantiate_symtab (struct dwarf2_per_cu_data *per_cu)
: (per_cu->v.psymtab == NULL || !per_cu->v.psymtab->readin))
{
queue_comp_unit (per_cu, language_minimal);
load_cu (per_cu);
load_cu (per_cu, skip_partial);
/* If we just loaded a CU from a DWO, and we're working with an index
that may badly handle TUs, load all the TUs in that DWO as well.
@ -2897,7 +2897,7 @@ dw2_do_instantiate_symtab (struct dwarf2_per_cu_data *per_cu)
table. */
static struct compunit_symtab *
dw2_instantiate_symtab (struct dwarf2_per_cu_data *per_cu)
dw2_instantiate_symtab (struct dwarf2_per_cu_data *per_cu, bool skip_partial)
{
struct dwarf2_per_objfile *dwarf2_per_objfile = per_cu->dwarf2_per_objfile;
@ -2906,7 +2906,7 @@ dw2_instantiate_symtab (struct dwarf2_per_cu_data *per_cu)
{
free_cached_comp_units freer (dwarf2_per_objfile);
scoped_restore decrementer = increment_reading_symtab ();
dw2_do_instantiate_symtab (per_cu);
dw2_do_instantiate_symtab (per_cu, skip_partial);
process_cu_includes (dwarf2_per_objfile);
}
@ -3741,7 +3741,7 @@ dw2_find_last_source_symtab (struct objfile *objfile)
struct dwarf2_per_objfile *dwarf2_per_objfile
= get_dwarf2_per_objfile (objfile);
dwarf2_per_cu_data *dwarf_cu = dwarf2_per_objfile->all_comp_units.back ();
compunit_symtab *cust = dw2_instantiate_symtab (dwarf_cu);
compunit_symtab *cust = dw2_instantiate_symtab (dwarf_cu, false);
if (cust == NULL)
return NULL;
@ -3797,7 +3797,7 @@ dw2_map_expand_apply (struct objfile *objfile,
/* This may expand more than one symtab, and we want to iterate over
all of them. */
dw2_instantiate_symtab (per_cu);
dw2_instantiate_symtab (per_cu, false);
return iterate_over_some_symtabs (name, real_path, objfile->compunit_symtabs,
last_made, callback);
@ -4037,7 +4037,7 @@ dw2_lookup_symbol (struct objfile *objfile, int block_index,
while ((per_cu = dw2_symtab_iter_next (&iter)) != NULL)
{
struct symbol *sym, *with_opaque = NULL;
struct compunit_symtab *stab = dw2_instantiate_symtab (per_cu);
struct compunit_symtab *stab = dw2_instantiate_symtab (per_cu, false);
const struct blockvector *bv = COMPUNIT_BLOCKVECTOR (stab);
struct block *block = BLOCKVECTOR_BLOCK (bv, block_index);
@ -4128,7 +4128,7 @@ dw2_expand_symtabs_for_function (struct objfile *objfile,
func_name);
while ((per_cu = dw2_symtab_iter_next (&iter)) != NULL)
dw2_instantiate_symtab (per_cu);
dw2_instantiate_symtab (per_cu, false);
}
@ -4144,7 +4144,12 @@ dw2_expand_all_symtabs (struct objfile *objfile)
{
dwarf2_per_cu_data *per_cu = dwarf2_per_objfile->get_cutu (i);
dw2_instantiate_symtab (per_cu);
/* We don't want to directly expand a partial CU, because if we
read it with the wrong language, then assertion failures can
be triggered later on. See PR symtab/23010. So, tell
dw2_instantiate_symtab to skip partial CUs -- any important
partial CU will be read via DW_TAG_imported_unit anyway. */
dw2_instantiate_symtab (per_cu, true);
}
}
@ -4176,7 +4181,7 @@ dw2_expand_symtabs_with_fullname (struct objfile *objfile,
if (filename_cmp (this_fullname, fullname) == 0)
{
dw2_instantiate_symtab (per_cu);
dw2_instantiate_symtab (per_cu, false);
break;
}
}
@ -5000,7 +5005,7 @@ dw2_expand_symtabs_matching_one
bool symtab_was_null
= (per_cu->v.quick->compunit_symtab == NULL);
dw2_instantiate_symtab (per_cu);
dw2_instantiate_symtab (per_cu, false);
if (expansion_notify != NULL
&& symtab_was_null
@ -5250,7 +5255,8 @@ dw2_find_pc_sect_compunit_symtab (struct objfile *objfile,
paddress (get_objfile_arch (objfile), pc));
result
= recursively_find_pc_sect_compunit_symtab (dw2_instantiate_symtab (data),
= recursively_find_pc_sect_compunit_symtab (dw2_instantiate_symtab (data,
false),
pc);
gdb_assert (result != NULL);
return result;
@ -6049,7 +6055,7 @@ dw2_debug_names_lookup_symbol (struct objfile *objfile, int block_index_int,
while ((per_cu = iter.next ()) != NULL)
{
struct symbol *sym, *with_opaque = NULL;
struct compunit_symtab *stab = dw2_instantiate_symtab (per_cu);
struct compunit_symtab *stab = dw2_instantiate_symtab (per_cu, false);
const struct blockvector *bv = COMPUNIT_BLOCKVECTOR (stab);
struct block *block = BLOCKVECTOR_BLOCK (bv, block_index);
@ -6111,7 +6117,7 @@ dw2_debug_names_expand_symtabs_for_function (struct objfile *objfile,
struct dwarf2_per_cu_data *per_cu;
while ((per_cu = iter.next ()) != NULL)
dw2_instantiate_symtab (per_cu);
dw2_instantiate_symtab (per_cu, false);
}
}
@ -7410,6 +7416,7 @@ static void
init_cutu_and_read_dies (struct dwarf2_per_cu_data *this_cu,
struct abbrev_table *abbrev_table,
int use_existing_cu, int keep,
bool skip_partial,
die_reader_func_ftype *die_reader_func,
void *data)
{
@ -7548,6 +7555,9 @@ init_cutu_and_read_dies (struct dwarf2_per_cu_data *this_cu,
init_cu_die_reader (&reader, cu, section, NULL, abbrev_table);
info_ptr = read_full_die (&reader, &comp_unit_die, info_ptr, &has_children);
if (skip_partial && comp_unit_die->tag == DW_TAG_partial_unit)
return;
/* If we are in a DWO stub, process it and then read in the "real" CU/TU
from the DWO file. read_cutu_die_from_dwo will allocate the abbreviation
table from the DWO file and pass the ownership over to us. It will be
@ -8042,14 +8052,14 @@ process_psymtab_comp_unit (struct dwarf2_per_cu_data *this_cu,
free_one_cached_comp_unit (this_cu);
if (this_cu->is_debug_types)
init_cutu_and_read_dies (this_cu, NULL, 0, 0, build_type_psymtabs_reader,
NULL);
init_cutu_and_read_dies (this_cu, NULL, 0, 0, false,
build_type_psymtabs_reader, NULL);
else
{
process_psymtab_comp_unit_data info;
info.want_partial_unit = want_partial_unit;
info.pretend_language = pretend_language;
init_cutu_and_read_dies (this_cu, NULL, 0, 0,
init_cutu_and_read_dies (this_cu, NULL, 0, 0, false,
process_psymtab_comp_unit_reader, &info);
}
@ -8209,7 +8219,7 @@ build_type_psymtabs_1 (struct dwarf2_per_objfile *dwarf2_per_objfile)
}
init_cutu_and_read_dies (&tu.sig_type->per_cu, abbrev_table.get (),
0, 0, build_type_psymtabs_reader, NULL);
0, 0, false, build_type_psymtabs_reader, NULL);
}
}
@ -8316,7 +8326,7 @@ process_skeletonless_type_unit (void **slot, void *info)
*slot = entry;
/* This does the job that build_type_psymtabs_1 would have done. */
init_cutu_and_read_dies (&entry->per_cu, NULL, 0, 0,
init_cutu_and_read_dies (&entry->per_cu, NULL, 0, 0, false,
build_type_psymtabs_reader, NULL);
return 1;
@ -8464,7 +8474,7 @@ load_partial_comp_unit_reader (const struct die_reader_specs *reader,
static void
load_partial_comp_unit (struct dwarf2_per_cu_data *this_cu)
{
init_cutu_and_read_dies (this_cu, NULL, 1, 1,
init_cutu_and_read_dies (this_cu, NULL, 1, 1, false,
load_partial_comp_unit_reader, NULL);
}
@ -9558,7 +9568,7 @@ psymtab_to_symtab_1 (struct partial_symtab *pst)
return;
}
dw2_do_instantiate_symtab (per_cu);
dw2_do_instantiate_symtab (per_cu, false);
}
/* Trivial hash function for die_info: the hash value of a DIE
@ -9627,11 +9637,12 @@ load_full_comp_unit_reader (const struct die_reader_specs *reader,
static void
load_full_comp_unit (struct dwarf2_per_cu_data *this_cu,
bool skip_partial,
enum language pretend_language)
{
gdb_assert (! this_cu->is_debug_types);
init_cutu_and_read_dies (this_cu, NULL, 1, 1,
init_cutu_and_read_dies (this_cu, NULL, 1, 1, skip_partial,
load_full_comp_unit_reader, &pretend_language);
}
@ -10463,7 +10474,7 @@ process_imported_unit_die (struct die_info *die, struct dwarf2_cu *cu)
/* If necessary, add it to the queue and load its DIEs. */
if (maybe_queue_comp_unit (cu, per_cu, cu->language))
load_full_comp_unit (per_cu, cu->language);
load_full_comp_unit (per_cu, false, cu->language);
VEC_safe_push (dwarf2_per_cu_ptr, cu->per_cu->imported_symtabs,
per_cu);
@ -19679,7 +19690,7 @@ dwarf2_read_addr_index (struct dwarf2_per_cu_data *per_cu,
/* Note: We can't use init_cutu_and_read_dies_simple here,
we need addr_base. */
init_cutu_and_read_dies (per_cu, NULL, 0, 0,
init_cutu_and_read_dies (per_cu, NULL, 0, 0, false,
dwarf2_read_addr_index_reader, &aidata);
addr_base = aidata.addr_base;
addr_size = aidata.addr_size;
@ -22886,7 +22897,7 @@ follow_die_offset (sect_offset sect_off, int offset_in_dwz,
/* If necessary, add it to the queue and load its DIEs. */
if (maybe_queue_comp_unit (cu, per_cu, cu->language))
load_full_comp_unit (per_cu, cu->language);
load_full_comp_unit (per_cu, false, cu->language);
target_cu = per_cu->cu;
}
@ -22894,7 +22905,7 @@ follow_die_offset (sect_offset sect_off, int offset_in_dwz,
{
/* We're loading full DIEs during partial symbol reading. */
gdb_assert (dwarf2_per_objfile->reading_partial_symbols);
load_full_comp_unit (cu->per_cu, language_minimal);
load_full_comp_unit (cu->per_cu, false, language_minimal);
}
*ref_cu = target_cu;
@ -22948,7 +22959,7 @@ dwarf2_fetch_die_loc_sect_off (sect_offset sect_off,
struct objfile *objfile = dwarf2_per_objfile->objfile;
if (per_cu->cu == NULL)
load_cu (per_cu);
load_cu (per_cu, false);
cu = per_cu->cu;
if (cu == NULL)
{
@ -23055,7 +23066,7 @@ dwarf2_fetch_constant_bytes (sect_offset sect_off,
struct objfile *objfile = per_cu->dwarf2_per_objfile->objfile;
if (per_cu->cu == NULL)
load_cu (per_cu);
load_cu (per_cu, false);
cu = per_cu->cu;
if (cu == NULL)
{
@ -23177,7 +23188,7 @@ dwarf2_fetch_die_type_sect_off (sect_offset sect_off,
struct die_info *die;
if (per_cu->cu == NULL)
load_cu (per_cu);
load_cu (per_cu, false);
cu = per_cu->cu;
if (!cu)
return NULL;
@ -23458,7 +23469,7 @@ read_signatured_type (struct signatured_type *sig_type)
gdb_assert (per_cu->is_debug_types);
gdb_assert (per_cu->cu == NULL);
init_cutu_and_read_dies (per_cu, NULL, 0, 1,
init_cutu_and_read_dies (per_cu, NULL, 0, 1, false,
read_signatured_type_reader, NULL);
sig_type->per_cu.tu_read = 1;
}