[RFA] massively speed up "info var foo" on large programs
Doug Evans
dje@google.com
Mon May 28 04:49:00 GMT 2012
On Fri, May 25, 2012 at 1:50 AM, Pedro Alves <palves@redhat.com> wrote:
> On 05/25/2012 09:21 AM, Doug Evans wrote:
>
>>
>> The output is different from the previous code, I didn't take into
>> account the symbols that gdb creates for @plt entries. I think if we
>> want to continue to provide the current output, we should add an
>> option to "info var|fun|type" to produce it: the normal case shouldn't
>> be that slow.
>
>
> Different how? The patch has no testsuite updates, so the email reader is
> left wondering. ;-)
In the "Non-debugging symbols" section of the output, when a symbol
would have been found in another objfile, the code would have not
printed the non-@plt form of the function name.
With this patch we have a decision to make. Searching all the other
objfiles is not reasonable (IMO) so what to do? I can think of two
possibilities: always print it or never print it. Since the symbol in
question is an artificial symbol created by gdb I have opted for never
printing it.
Thus instead of seeing this in the "Non-debugging symbols" section of
the output:
0x1234 foo@plt
0x1234 foo
the output will contain:
0x1234 foo@plt
Here is v3 of the patch. I added a testcase.
Regression tested on amd64-linux.
Ok to check in?
2012-05-27 Doug Evans <dje@google.com>
* symtab.c (minimal_symbol): New member created_by_gdb.
* elfread.c (elf_symtab_read): Set created_by_gdb for @plt
minsym
created by gdb.
* symtab.c (lookup_msymbol_in_objfile): New function.
(search_symbols): Call it. Only scan minsyms if nfiles == 0.
testsuite:
* gdb.base/info-fun.exp: New file.
* gdb.base/info-fun.c: New file.
* gdb.base/info-fun-solib.c: New file.
-------------- next part --------------
2012-05-27 Doug Evans <dje@google.com>
* symtab.c (minimal_symbol): New member created_by_gdb.
* elfread.c (elf_symtab_read): Set created_by_gdb for @plt minsym
created by gdb.
* symtab.c (lookup_msymbol_in_objfile): New function.
(search_symbols): Call it. Only scan minsyms if nfiles == 0.
testsuite:
* gdb.base/info-fun.exp: New file.
* gdb.base/info-fun.c: New file.
* gdb.base/info-fun-solib.c: New file.
Index: elfread.c
===================================================================
RCS file: /cvs/src/src/gdb/elfread.c,v
retrieving revision 1.131
diff -u -p -r1.131 elfread.c
--- elfread.c 18 May 2012 21:02:47 -0000 1.131
+++ elfread.c 28 May 2012 04:13:19 -0000
@@ -594,6 +594,7 @@ elf_symtab_read (struct objfile *objfile
if (mtramp)
{
MSYMBOL_SIZE (mtramp) = MSYMBOL_SIZE (msym);
+ mtramp->created_by_gdb = 1;
mtramp->filename = filesymname;
gdbarch_elf_make_msymbol_special (gdbarch, sym, mtramp);
}
Index: symtab.c
===================================================================
RCS file: /cvs/src/src/gdb/symtab.c,v
retrieving revision 1.306
diff -u -p -r1.306 symtab.c
--- symtab.c 24 May 2012 02:51:48 -0000 1.306
+++ symtab.c 28 May 2012 04:13:19 -0000
@@ -1559,6 +1559,48 @@ lookup_symbol_aux_symtabs (int block_ind
return NULL;
}
+/* Wrapper around lookup_symbol_aux_objfile for search_symbols.
+ Look up MSYMBOL in DOMAIN in the global and static blocks of OBJFILE
+ and all related objfiles. */
+
+static struct symbol *
+lookup_msymbol_in_objfile (struct objfile *objfile,
+ struct minimal_symbol *msymbol,
+ domain_enum domain)
+{
+ const char *name = SYMBOL_LINKAGE_NAME (msymbol);
+ enum language lang = current_language->la_language;
+ const char *modified_name;
+ struct cleanup *cleanup = demangle_for_lookup (name, lang, &modified_name);
+ struct objfile *main_objfile, *cur_objfile;
+
+ if (objfile->separate_debug_objfile_backlink)
+ main_objfile = objfile->separate_debug_objfile_backlink;
+ else
+ main_objfile = objfile;
+
+ for (cur_objfile = main_objfile;
+ cur_objfile;
+ cur_objfile = objfile_separate_debug_iterate (main_objfile, cur_objfile))
+ {
+ struct symbol *sym;
+
+ sym = lookup_symbol_aux_objfile (cur_objfile, GLOBAL_BLOCK,
+ modified_name, domain);
+ if (sym == NULL)
+ sym = lookup_symbol_aux_objfile (cur_objfile, STATIC_BLOCK,
+ modified_name, domain);
+ if (sym != NULL)
+ {
+ do_cleanups (cleanup);
+ return sym;
+ }
+ }
+
+ do_cleanups (cleanup);
+ return NULL;
+}
+
/* A helper function for lookup_symbol_aux that interfaces with the
"quick" symbol table functions. */
@@ -3463,21 +3505,13 @@ search_symbols (char *regexp, enum searc
|| regexec (&datum.preg, SYMBOL_NATURAL_NAME (msymbol), 0,
NULL, 0) == 0)
{
- if (0 == find_pc_symtab (SYMBOL_VALUE_ADDRESS (msymbol)))
- {
- /* FIXME: carlton/2003-02-04: Given that the
- semantics of lookup_symbol keeps on changing
- slightly, it would be a nice idea if we had a
- function lookup_symbol_minsym that found the
- symbol associated to a given minimal symbol (if
- any). */
- if (kind == FUNCTIONS_DOMAIN
- || lookup_symbol (SYMBOL_LINKAGE_NAME (msymbol),
- (struct block *) NULL,
- VAR_DOMAIN, 0)
- == NULL)
- found_misc = 1;
- }
+ /* Note: An important side-effect of these lookup functions
+ is to expand the symbol table if msymbol is found. */
+ if (kind == FUNCTIONS_DOMAIN
+ ? find_pc_symtab (SYMBOL_VALUE_ADDRESS (msymbol)) == NULL
+ : lookup_msymbol_in_objfile (objfile, msymbol,
+ VAR_DOMAIN) == NULL)
+ found_misc = 1;
}
}
}
@@ -3554,12 +3588,15 @@ search_symbols (char *regexp, enum searc
/* If there are no eyes, avoid all contact. I mean, if there are
no debug symbols, then print directly from the msymbol_vector. */
- if (found_misc || kind != FUNCTIONS_DOMAIN)
+ if (found_misc || (nfiles == 0 && kind != FUNCTIONS_DOMAIN))
{
ALL_MSYMBOLS (objfile, msymbol)
{
QUIT;
+ if (msymbol->created_by_gdb)
+ continue;
+
if (MSYMBOL_TYPE (msymbol) == ourtype
|| MSYMBOL_TYPE (msymbol) == ourtype2
|| MSYMBOL_TYPE (msymbol) == ourtype3
@@ -3569,14 +3606,13 @@ search_symbols (char *regexp, enum searc
|| regexec (&datum.preg, SYMBOL_NATURAL_NAME (msymbol), 0,
NULL, 0) == 0)
{
- /* Functions: Look up by address. */
- if (kind != FUNCTIONS_DOMAIN ||
- (0 == find_pc_symtab (SYMBOL_VALUE_ADDRESS (msymbol))))
+ /* For functions we can do a quick check of whether the
+ symbol might be found via find_pc_symtab. */
+ if (kind != FUNCTIONS_DOMAIN
+ || find_pc_symtab (SYMBOL_VALUE_ADDRESS (msymbol)) == NULL)
{
- /* Variables/Absolutes: Look up by name. */
- if (lookup_symbol (SYMBOL_LINKAGE_NAME (msymbol),
- (struct block *) NULL, VAR_DOMAIN, 0)
- == NULL)
+ if (lookup_msymbol_in_objfile (objfile, msymbol,
+ VAR_DOMAIN) == NULL)
{
/* match */
psr = (struct symbol_search *)
Index: symtab.h
===================================================================
RCS file: /cvs/src/src/gdb/symtab.h,v
retrieving revision 1.206
diff -u -p -r1.206 symtab.h
--- symtab.h 10 May 2012 20:04:00 -0000 1.206
+++ symtab.h 28 May 2012 04:13:19 -0000
@@ -339,6 +339,10 @@ struct minimal_symbol
ENUM_BITFIELD(minimal_symbol_type) type : 8;
+ /* Non-zero if this symbol was created by gdb.
+ Such symbols do not appear in the output of "info var|fun". */
+ unsigned int created_by_gdb : 1;
+
/* Two flag bits provided for the use of the target. */
unsigned int target_flag_1 : 1;
unsigned int target_flag_2 : 1;
Index: testsuite/gdb.base/info-fun-solib.c
===================================================================
RCS file: testsuite/gdb.base/info-fun-solib.c
diff -N testsuite/gdb.base/info-fun-solib.c
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ testsuite/gdb.base/info-fun-solib.c 28 May 2012 04:13:20 -0000
@@ -0,0 +1,20 @@
+/* Copyright 2012 Free Software Foundation, Inc.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
+
+int
+foo (void)
+{
+ return 0;
+}
Index: testsuite/gdb.base/info-fun.c
===================================================================
RCS file: testsuite/gdb.base/info-fun.c
diff -N testsuite/gdb.base/info-fun.c
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ testsuite/gdb.base/info-fun.c 28 May 2012 04:13:20 -0000
@@ -0,0 +1,22 @@
+/* Copyright 2012 Free Software Foundation, Inc.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
+
+extern int foo (void);
+
+int
+main ()
+{
+ return foo ();
+}
Index: testsuite/gdb.base/info-fun.exp
===================================================================
RCS file: testsuite/gdb.base/info-fun.exp
diff -N testsuite/gdb.base/info-fun.exp
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ testsuite/gdb.base/info-fun.exp 28 May 2012 04:13:20 -0000
@@ -0,0 +1,76 @@
+# Copyright 2012 Free Software Foundation, Inc.
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+if { [skip_shlib_tests] || [is_remote target] } {
+ return 0
+}
+
+# Library file.
+set libname "info-fun-solib"
+set srcfile_lib ${srcdir}/${subdir}/${libname}.c
+set binfile_lib ${objdir}/${subdir}/${libname}.so
+set lib_flags {}
+# Binary file.
+set testfile "info-fun"
+set srcfile ${srcdir}/${subdir}/${testfile}.c
+set executable ${testfile}
+set binfile ${objdir}/${subdir}/${executable}
+set bin_flags [list debug shlib=${binfile_lib}]
+
+if [get_compiler_info ${binfile}] {
+ return -1
+}
+
+# SEP must be last for the possible `unsupported' error path.
+foreach libsepdebug {NO IN SEP} { with_test_prefix "$libsepdebug" {
+
+ set sep_lib_flags $lib_flags
+ if {$libsepdebug != "NO"} {
+ lappend sep_lib_flags {debug}
+ }
+ if { [gdb_compile_shlib ${srcfile_lib} ${binfile_lib} $sep_lib_flags] != ""
+ || [gdb_compile ${srcfile} ${binfile} executable $bin_flags] != "" } {
+ untested "Could not compile $binfile_lib or $binfile."
+ return -1
+ }
+
+ if {$libsepdebug == "SEP"} {
+ if {[gdb_gnu_strip_debug $binfile_lib] != 0} {
+ unsupported "Could not split debug of $binfile_lib."
+ return
+ } else {
+ pass "split solib"
+ }
+ }
+
+ clean_restart $executable
+
+ if ![runto_main] then {
+ fail "Can't run to main"
+ return 0
+ }
+
+ set match_str {All functions matching regular expression "foo":[\r\n]*}
+ if { "$libsepdebug" != "NO" } {
+ append match_str {File .*/info-fun-solib[.]c:[\r\n]*}
+ append match_str {int foo\(void\);[\r\n]*}
+ }
+ append match_str {Non-debugging symbols:[\r\n]*}
+ append match_str "$hex *foo(@plt)?\[\r\n\]*"
+ if { "$libsepdebug" == "NO" } {
+ append match_str "$hex *foo\[\r\n\]*"
+ }
+
+ gdb_test "info fun foo" "$match_str"
+}}
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