This inlines a couple of methods on struct attribute, improving the
performance of DWARF partial symbol reading. These methods were
discovered as hot spots using callgrind.
For this patch, and for all the patches in this series, I tested gdb's
performance on three programs:
1. gdb itself -- I built gdb and copied it to /tmp, ensuring that the
same version was used in all tests.
2. The system libxul.so, the main library of Firefox. I installed the
separate debuginfo and ensured that gdb read it.
3. A large-ish Ada program that I happen to have.
I ran gdb 10 times like:
/bin/time -f %e \
./gdb/gdb --data-directory ./gdb/data-directory -nx \
-iex 'set debug-file-directory /usr/lib/debug' \
-batch $X
... where $X was the test executable. Then I computed the mean time.
This was all done with a standard (-g -O2) build of gdb.
The baseline times were
gdb 1.90
libxul 2.12
Ada 2.61
This patch brings the numbers down to
gdb 1.88
libxul 2.11
Ada 2.60
Not a huge change, but still visible in the results.
gdb/ChangeLog
2020-05-27 Tom Tromey <tromey@adacore.com>
* dwarf2/attribute.h (struct attribute) <form_is_ref>: Inline.
<get_ref_die_offset>: Inline.
<get_ref_die_offset_complaint>: New method.
* dwarf2/attribute.c (attribute::form_is_ref): Move to header.
(attribute::get_ref_die_offset_complaint): Rename from
get_ref_die_offset. Just issue complaint.
The full DIE reader checks that an attribute has a "string" form in
some spots, but the partial DIE reader does not. This patch brings
the two readers in sync for one specific case, namely when examining
the linkage name. This avoids regressions in an existing DWARF test
case.
A full fix for this problem would be preferable. An accessor like
DW_STRING should always check the form. However, I haven't attempted
that in this series.
Also the fact that the partial and full readers can disagree like this
is a design flaw.
gdb/ChangeLog
2020-04-24 Tom Tromey <tom@tromey.com>
* dwarf2/read.c (partial_die_info::read) <case
DW_AT_linkage_name>: Use value_as_string.
(dwarf2_string_attr): Use value_as_string.
* dwarf2/attribute.h (struct attribute) <value_as_string>: Declare
method.
* dwarf2/attribute.c (attribute::value_as_string): New method.
This changes dwarf2_get_ref_die_offset and
dwarf2_get_attr_constant_value to be methods on struct attribute.
gdb/ChangeLog
2020-03-26 Tom Tromey <tom@tromey.com>
* dwarf2/read.c (handle_data_member_location, dwarf2_add_field)
(mark_common_block_symbol_computed, read_tag_string_type)
(attr_to_dynamic_prop, read_subrange_type): Update.
(dwarf2_get_ref_die_offset, dwarf2_get_attr_constant_value): Move
to be methods on struct attribute.
(skip_one_die, process_imported_unit_die, read_namespace_alias)
(read_call_site_scope, partial_die_info::read)
(partial_die_info::read, lookup_die_type, follow_die_ref):
Update.
* dwarf2/attribute.c (attribute::get_ref_die_offset): New method,
from dwarf2_get_ref_die_offset.
(attribute::constant_value): New method, from
dwarf2_get_attr_constant_value.
* dwarf2/attribute.h (struct attribute) <get_ref_die_offset>:
Declare method.
<constant_value>: New method.
This changes attr_form_is_block to be a method. This is done
separately because, unlike the other attribute functions,
attr_form_is_block had special handling for the case where the
argument was NULL. This required auditing each call site; in most
cases, NULL was already ruled out, but in a few spots, an additional
check was needed.
gdb/ChangeLog
2020-02-08 Tom Tromey <tom@tromey.com>
* dwarf2read.c (read_call_site_scope)
(handle_data_member_location, dwarf2_add_member_fn)
(mark_common_block_symbol_computed, read_common_block)
(attr_to_dynamic_prop, partial_die_info::read)
(var_decode_location, dwarf2_fetch_die_loc_sect_off)
(dwarf2_symbol_mark_computed, set_die_type): Update.
* dwarf2/attribute.h (struct attribute) <form_is_block>: Declare
method.
(attr_form_is_block): Don't declare.
* dwarf2/attribute.c (attribute::form_is_block): Now a method.
Change-Id: Idfb290c61d738301ab991666f43e0b9cf577b2ae
This moves the attribute-related code out of dwarf2read.c and into the
new files dwarf2/attribute.[ch].
gdb/ChangeLog
2020-02-08 Tom Tromey <tom@tromey.com>
* dwarf2read.c (struct attribute, DW_STRING)
(DW_STRING_IS_CANONICAL, DW_UNSND, DW_BLOCK, DW_SND, DW_ADDR)
(DW_SIGNATURE, struct dwarf_block, attr_value_as_address)
(attr_form_is_block, attr_form_is_section_offset)
(attr_form_is_constant, attr_form_is_ref): Move.
* dwarf2/attribute.h: New file.
* dwarf2/attribute.c: New file, from dwarf2read.c.
* Makefile.in (COMMON_SFILES): Add dwarf2/attribute.c.
Change-Id: I1ea4c146256a1b9e38b66f1c605d782a14eeded7
Tom Tromey
Tom Tromey
nitachra