[PATCH v2 20/42] Pass dwarf2_cu objects to dwo-related functions, instead of dwarf2_per_cu_data

Simon Marchi
2020-05-12T21:15:16Z

This allows removing references to the
dwarf2_per_cu_data::dwarf2_per_objfile field.

I am not too sure of the code flow here, but ultimately
open_and_init_dwo_file calls create_cus_hash_table, and passes it
per_cu->cu. create_cus_hash_table requires a dwarf2_cu to pass to
cutu_reader, as the "parent_cu".

The dwarf2_per_cu_data::cu link is only set when in a certain context.
It's not easy to convince myself in which situations it's safe to use
it. Instead, if a function is going to use a dwarf2_cu, I think it's
simpler if it takes that object directly. If it needs access to the
corresponding dwarf2_per_cu_data object, then it can used the
dwarf2_cu::per_cu field, which we know is always set.

This patch adds some references to dwarf2_per_cu_data::cu in the
cutu_reader context. In this context, we know this field will be set,
as it's cutu_reader that is responsible for instantiating the dwarf2_cu
and assigning the field.

gdb/ChangeLog:

* dwarf2/read.c (lookup_dwo_comp_unit): Change
dwarf2_per_cu_data parameter fo dwarf2_cu.
(lookup_dwo_type_unit): Likewise.
(read_cutu_die_from_dwo): Likewise.
(lookup_dwo_unit): Likewise.
(open_and_init_dwo_file): Likewise.
(lookup_dwo_cutu): Likewise.
(lookup_dwo_comp_unit): Likewise.
(lookup_dwo_type_unit): Likewise.
(cutu_reader::init_tu_and_read_dwo_dies): Update.
(cutu_reader::cutu_reader): Update.
---
gdb/dwarf2/read.c | 84 ++++++++++++++++++++++-------------------------
1 file changed, 39 insertions(+), 45 deletions(-)

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 906a0ade2ce..5dc8a350739 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -1672,10 +1672,11 @@ static struct dwp_file *get_dwp_file
(struct dwarf2_per_objfile *dwarf2_per_objfile);

static struct dwo_unit *lookup_dwo_comp_unit
- (struct dwarf2_per_cu_data *, const char *, const char *, ULONGEST);
+ (dwarf2_cu *cu, const char *dwo_name, const char *comp_dir,
+ ULONGEST signature);

static struct dwo_unit *lookup_dwo_type_unit
- (struct signatured_type *, const char *, const char *);
+ (dwarf2_cu *cu, const char *dwo_name, const char *comp_dir);

static void queue_and_load_all_dwo_tus (struct dwarf2_per_cu_data *);

@@ -6650,7 +6651,7 @@ init_cu_die_reader (struct die_reader_specs *reader,
The result is non-zero if a valid (non-dummy) DIE was found. */

static int
-read_cutu_die_from_dwo (struct dwarf2_per_cu_data *this_cu,
+read_cutu_die_from_dwo (dwarf2_cu *cu,
struct dwo_unit *dwo_unit,
struct die_info *stub_comp_unit_die,
const char *stub_comp_dir,
@@ -6659,9 +6660,9 @@ read_cutu_die_from_dwo (struct dwarf2_per_cu_data *this_cu,
struct die_info **result_comp_unit_die,
abbrev_table_up *result_dwo_abbrev_table)
{
- struct dwarf2_per_objfile *dwarf2_per_objfile = this_cu->dwarf2_per_objfile;
+ struct dwarf2_per_objfile *dwarf2_per_objfile = cu->per_objfile;
+ dwarf2_per_cu_data *per_cu = cu->per_cu;
struct objfile *objfile = dwarf2_per_objfile->objfile;
- struct dwarf2_cu *cu = this_cu->cu;
bfd *abfd;
const gdb_byte *begin_info_ptr, *info_ptr;
struct attribute *comp_dir, *stmt_list, *low_pc, *high_pc, *ranges;
@@ -6690,7 +6691,7 @@ read_cutu_die_from_dwo (struct dwarf2_per_cu_data *this_cu,
{
/* For TUs in DWO files, the DW_AT_stmt_list attribute lives in the
DWO file. */
- if (! this_cu->is_debug_types)
+ if (!per_cu->is_debug_types)
stmt_list = dwarf2_attr (stub_comp_unit_die, DW_AT_stmt_list, cu);
low_pc = dwarf2_attr (stub_comp_unit_die, DW_AT_low_pc, cu);
high_pc = dwarf2_attr (stub_comp_unit_die, DW_AT_high_pc, cu);
@@ -6723,9 +6724,9 @@ read_cutu_die_from_dwo (struct dwarf2_per_cu_data *this_cu,
+ to_underlying (dwo_unit->sect_off));
dwo_abbrev_section = &dwo_unit->dwo_file->sections.abbrev;

- if (this_cu->is_debug_types)
+ if (per_cu->is_debug_types)
{
- struct signatured_type *sig_type = (struct signatured_type *) this_cu;
+ signatured_type *sig_type = (struct signatured_type *) per_cu;

info_ptr = read_and_check_comp_unit_head (dwarf2_per_objfile,
&cu->header, section,
@@ -6836,11 +6837,9 @@ lookup_dwo_id (struct dwarf2_cu *cu, struct die_info* comp_unit_die)
Returns NULL if the specified DWO unit cannot be found. */

static struct dwo_unit *
-lookup_dwo_unit (struct dwarf2_per_cu_data *this_cu,
- struct die_info *comp_unit_die,
- const char *dwo_name)
+lookup_dwo_unit (dwarf2_cu *cu, die_info *comp_unit_die, const char *dwo_name)
{
- struct dwarf2_cu *cu = this_cu->cu;
+ dwarf2_per_cu_data *per_cu = cu->per_cu;
struct dwo_unit *dwo_unit;
const char *comp_dir;

@@ -6850,24 +6849,18 @@ lookup_dwo_unit (struct dwarf2_per_cu_data *this_cu,
dwo_name = dwarf2_dwo_name (comp_unit_die, cu);
comp_dir = dwarf2_string_attr (comp_unit_die, DW_AT_comp_dir, cu);

- if (this_cu->is_debug_types)
- {
- struct signatured_type *sig_type;
-
- /* Since this_cu is the first member of struct signatured_type,
- we can go from a pointer to one to a pointer to the other. */
- sig_type = (struct signatured_type *) this_cu;
- dwo_unit = lookup_dwo_type_unit (sig_type, dwo_name, comp_dir);
- }
+ if (per_cu->is_debug_types)
+ dwo_unit = lookup_dwo_type_unit (cu, dwo_name, comp_dir);
else
{
gdb::optional<ULONGEST> signature = lookup_dwo_id (cu, comp_unit_die);
+
if (!signature.has_value ())
error (_("Dwarf Error: missing dwo_id for dwo_name %s"
" [in module %s]"),
- dwo_name, bfd_get_filename (this_cu->per_bfd->obfd));
- dwo_unit = lookup_dwo_comp_unit (this_cu, dwo_name, comp_dir,
- *signature);
+ dwo_name, bfd_get_filename (per_cu->per_bfd->obfd));
+
+ dwo_unit = lookup_dwo_comp_unit (cu, dwo_name, comp_dir, *signature);
}

return dwo_unit;
@@ -6907,7 +6900,7 @@ cutu_reader::init_tu_and_read_dwo_dies (dwarf2_per_cu_data *this_cu,
abbrev table. When reading DWOs with skeletonless TUs, all the TUs
could share abbrev tables. */

- if (read_cutu_die_from_dwo (this_cu, sig_type->dwo_unit,
+ if (read_cutu_die_from_dwo (this_cu->cu, sig_type->dwo_unit,
NULL /* stub_comp_unit_die */,
sig_type->dwo_unit->dwo_file->comp_dir,
this, &info_ptr,
@@ -7094,10 +7087,10 @@ cutu_reader::cutu_reader (dwarf2_per_cu_data *this_cu,
sect_offset_str (this_cu->sect_off),
bfd_get_filename (abfd));
}
- dwo_unit = lookup_dwo_unit (this_cu, comp_unit_die, dwo_name);
+ dwo_unit = lookup_dwo_unit (cu, comp_unit_die, dwo_name);
if (dwo_unit != NULL)
{
- if (read_cutu_die_from_dwo (this_cu, dwo_unit,
+ if (read_cutu_die_from_dwo (cu, dwo_unit,
comp_unit_die, NULL,
this, &info_ptr,
&dwo_comp_unit_die,
@@ -12325,10 +12318,10 @@ dwarf2_locate_dwo_sections (bfd *abfd, asection *sectp, void *dwo_sections_ptr)
The result is NULL if DWO_NAME can't be found. */

static struct dwo_file *
-open_and_init_dwo_file (struct dwarf2_per_cu_data *per_cu,
- const char *dwo_name, const char *comp_dir)
+open_and_init_dwo_file (dwarf2_cu *cu, const char *dwo_name,
+ const char *comp_dir)
{
- struct dwarf2_per_objfile *dwarf2_per_objfile = per_cu->dwarf2_per_objfile;
+ struct dwarf2_per_objfile *dwarf2_per_objfile = cu->per_objfile;

gdb_bfd_ref_ptr dbfd = open_dwo_file (dwarf2_per_objfile, dwo_name, comp_dir);
if (dbfd == NULL)
@@ -12346,7 +12339,7 @@ open_and_init_dwo_file (struct dwarf2_per_cu_data *per_cu,
bfd_map_over_sections (dwo_file->dbfd.get (), dwarf2_locate_dwo_sections,
&dwo_file->sections);

- create_cus_hash_table (dwarf2_per_objfile, per_cu->cu, *dwo_file,
+ create_cus_hash_table (dwarf2_per_objfile, cu, *dwo_file,
dwo_file->sections.info, dwo_file->cus);

create_debug_types_hash_table (dwarf2_per_objfile, dwo_file.get (),
@@ -12657,11 +12650,10 @@ get_dwp_file (struct dwarf2_per_objfile *dwarf2_per_objfile)
(dwo_id mismatch or couldn't find the DWO/DWP file). */

static struct dwo_unit *
-lookup_dwo_cutu (struct dwarf2_per_cu_data *this_unit,
- const char *dwo_name, const char *comp_dir,
+lookup_dwo_cutu (dwarf2_cu *cu, const char *dwo_name, const char *comp_dir,
ULONGEST signature, int is_debug_types)
{
- struct dwarf2_per_objfile *dwarf2_per_objfile = this_unit->dwarf2_per_objfile;
+ struct dwarf2_per_objfile *dwarf2_per_objfile = cu->per_objfile;
struct objfile *objfile = dwarf2_per_objfile->objfile;
const char *kind = is_debug_types ? "TU" : "CU";
void **dwo_file_slot;
@@ -12707,7 +12699,7 @@ lookup_dwo_cutu (struct dwarf2_per_cu_data *this_unit,
if (*dwo_file_slot == NULL)
{
/* Read in the file and build a table of the CUs/TUs it contains. */
- *dwo_file_slot = open_and_init_dwo_file (this_unit, dwo_name, comp_dir);
+ *dwo_file_slot = open_and_init_dwo_file (cu, dwo_name, comp_dir);
}
/* NOTE: This will be NULL if unable to open the file. */
dwo_file = (struct dwo_file *) *dwo_file_slot;
@@ -12772,10 +12764,8 @@ lookup_dwo_cutu (struct dwarf2_per_cu_data *this_unit,

warning (_("Could not find DWO %s %s(%s)%s referenced by %s at offset %s"
" [in module %s]"),
- kind, dwo_name, hex_string (signature),
- dwp_text.c_str (),
- this_unit->is_debug_types ? "TU" : "CU",
- sect_offset_str (this_unit->sect_off), objfile_name (objfile));
+ kind, dwo_name, hex_string (signature), dwp_text.c_str (), kind,
+ sect_offset_str (cu->per_cu->sect_off), objfile_name (objfile));
}
return NULL;
}
@@ -12784,21 +12774,25 @@ lookup_dwo_cutu (struct dwarf2_per_cu_data *this_unit,
See lookup_dwo_cutu_unit for details. */

static struct dwo_unit *
-lookup_dwo_comp_unit (struct dwarf2_per_cu_data *this_cu,
- const char *dwo_name, const char *comp_dir,
+lookup_dwo_comp_unit (dwarf2_cu *cu, const char *dwo_name, const char *comp_dir,
ULONGEST signature)
{
- return lookup_dwo_cutu (this_cu, dwo_name, comp_dir, signature, 0);
+ gdb_assert (!cu->per_cu->is_debug_types);
+
+ return lookup_dwo_cutu (cu, dwo_name, comp_dir, signature, 0);
}

/* Lookup the DWO TU DWO_NAME/SIGNATURE referenced from THIS_TU.
See lookup_dwo_cutu_unit for details. */

static struct dwo_unit *
-lookup_dwo_type_unit (struct signatured_type *this_tu,
- const char *dwo_name, const char *comp_dir)
+lookup_dwo_type_unit (dwarf2_cu *cu, const char *dwo_name, const char *comp_dir)
{
- return lookup_dwo_cutu (&this_tu->per_cu, dwo_name, comp_dir, this_tu->signature, 1);
+ gdb_assert (cu->per_cu->is_debug_types);
+
+ signatured_type *sig_type = (signatured_type *) cu->per_cu;
+
+ return lookup_dwo_cutu (cu, dwo_name, comp_dir, sig_type->signature, 1);
}

/* Traversal function for queue_and_load_all_dwo_tus. */
--
2.26.2