Toolchain/binutils-gdb
1
0
Fork 0
forked from Imagelibrary/binutils-gdb
Code Pull Requests Activity

2003-08-21 Michael Chastain <mec@shout.net>

Browse Source 
* symtab.h: Add doco on the space critical structures and
	some measurements of space usage.
This commit is contained in:
Michael Chastain
2003-08-21 19:55:32 +00:00
parent da08ea5b1e
commit a7f19c79e3
2 changed files with 54 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

52
gdb/symtab.h
View File

@@ -35,13 +35,55 @@ struct blockvector;
struct axs_value;
struct agent_expr;
/* Some of the structures in this file are space critical.
The space-critical structures are:
struct general_symbol_info
struct symbol
struct partial_symbol
These structures are layed out to encourage good packing.
They use ENUM_BITFIELD and short int fields, and they order the
structure members so that fields less than a word are next
to each other so they can be packed together. */
/* Rearranged: used ENUM_BITFIELD and rearranged field order in
all the space critical structures (plus struct minimal_symbol).
Memory usage dropped from 99360768 bytes to 90001408 bytes.
I measured this with before-and-after tests of
"HEAD-old-gdb -readnow HEAD-old-gdb" and
"HEAD-new-gdb -readnow HEAD-old-gdb" on native i686-pc-linux-gnu,
red hat linux 8, with LD_LIBRARY_PATH=/usr/lib/debug,
typing "maint space 1" at the first command prompt.
Here is another measurement (from andrew c):
# no /usr/lib/debug, just plain glibc, like a normal user
gdb HEAD-old-gdb
(gdb) break internal_error
(gdb) run
(gdb) maint internal-error
(gdb) backtrace
(gdb) maint space 1
gdb gdb_6_0_branch 2003-08-19 space used: 8896512
gdb HEAD 2003-08-19 space used: 8904704
gdb HEAD 2003-08-21 space used: 8396800 (+symtab.h)
gdb HEAD 2003-08-21 space used: 8265728 (+gdbtypes.h)
The third line shows the savings from the optimizations in symtab.h.
The fourth line shows the savings from the optimizations in
gdbtypes.h. Both optimizations are in gdb HEAD now.
--chastain 2003-08-21 */
/* Define a structure for the information that is common to all symbol types,
including minimal symbols, partial symbols, and full symbols. In a
multilanguage environment, some language specific information may need to
be recorded along with each symbol.
be recorded along with each symbol. */
These fields are ordered to encourage good packing, since we frequently
have tens or hundreds of thousands of these. */
/* This structure is space critical. See space comments at the top. */
struct general_symbol_info
{
@@ -557,6 +599,8 @@ struct alias_list
struct alias_list *next;
};
/* This structure is space critical. See space comments at the top. */
struct symbol
{
@@ -638,6 +682,8 @@ struct symbol
on a partial symtab list and which points to the corresponding
normal symtab once the partial_symtab has been referenced. */
/* This structure is space critical. See space comments at the top. */
struct partial_symbol
{