[patch] Improve symbol lookup performance noted in PR 15519

Doug Evans
2013-05-30T23:27:38Z

Hi.
Here's the patch I intend to check in to "fix"
http://sourceware.org/bugzilla/show_bug.cgi?id=15519
[It's not a complete "fix", there's still some performance gains
to be had, but I'm leaving that for a separate pass. This gets
us >95% of the way there, at least in the benchmarks I've been using,
including the one in the PR. Thanks Paul!]

No regressions on amd64-linux, with/without Fission.

I'll let it sit for a few days in case there are any more comments.
I'd also like to commit this to the 7.6 branch. Ok Joel?
[I need to rerun the testsuite in that tree before committing there.]

2013-05-30 Doug Evans <dje@google.com>
Keith Seitz <keiths@redhat.com>

PR 15519
* cp-namespace.c (find_symbol_in_baseclass): Call
cp_lookup_symbol_in_namespace instead of cp_lookup_symbol_namespace.
Remove call to lookup_symbol_static. Call lookup_static_symbol_aux
unconditionally. Call check_typedef on base types before accessing
them.
(cp_lookup_nested_symbol): Fix comment.

testsuite/
* gdb.cp/derivation2.cc: New file.
* gdb.cp/derivation.cc (main): Call foo2.
* gdb.cp/derivation.exp: Add tests for typedefs in another
file, and when there's an active block.

Index: cp-namespace.c
===================================================================
RCS file: /cvs/src/src/gdb/cp-namespace.c,v
retrieving revision 1.66
diff -u -p -r1.66 cp-namespace.c
--- ./cp-namespace.c 14 Mar 2013 11:13:34 -0000 1.66
+++ ./cp-namespace.c 30 May 2013 22:47:02 -0000
@@ -717,36 +717,34 @@ find_symbol_in_baseclass (struct type *p
for (i = 0; i < TYPE_N_BASECLASSES (parent_type); ++i)
{
size_t len;
+ struct type *base_type = TYPE_BASECLASS (parent_type, i);
const char *base_name = TYPE_BASECLASS_NAME (parent_type, i);

if (base_name == NULL)
continue;

/* Search this particular base class. */
- sym = cp_lookup_symbol_namespace (base_name, name, block, VAR_DOMAIN);
+ sym = cp_lookup_symbol_in_namespace (base_name, name, block,
+ VAR_DOMAIN, 0);
if (sym != NULL)
break;

+ /* Now search all static file-level symbols. We have to do this
+ for things like typedefs in the class. And we have to search
+ all static blocks, even if block != NULL, because there's no
+ guarantees as to which block it's in. */
len = strlen (base_name) + 2 + strlen (name) + 1;
concatenated_name = xrealloc (concatenated_name, len);
xsnprintf (concatenated_name, len, "%s::%s", base_name, name);
- sym = lookup_symbol_static (concatenated_name, block, VAR_DOMAIN);
-
- /* If there is currently no BLOCK, e.g., the inferior hasn't yet
- been started, then try searching all STATIC_BLOCK symbols in
- all objfiles. */
- if (block == NULL)
- {
- sym = lookup_static_symbol_aux (concatenated_name, VAR_DOMAIN);
- if (sym != NULL)
- break;
- }
+ sym = lookup_static_symbol_aux (concatenated_name, VAR_DOMAIN);
+ if (sym != NULL)
+ break;

/* If this class has base classes, search them next. */
- if (TYPE_N_BASECLASSES (TYPE_BASECLASS (parent_type, i)) > 0)
+ CHECK_TYPEDEF (base_type);
+ if (TYPE_N_BASECLASSES (base_type) > 0)
{
- sym = find_symbol_in_baseclass (TYPE_BASECLASS (parent_type, i),
- name, block);
+ sym = find_symbol_in_baseclass (base_type, name, block);
if (sym != NULL)
break;
}
@@ -794,8 +792,8 @@ cp_lookup_nested_symbol (struct type *pa
if (sym != NULL)
return sym;

- /* Now search all static file-level symbols. Not strictly
- correct, but more useful than an error. We do not try to
+ /* Now search all static file-level symbols. We have to do this
+ for things like typedefs in the class. We do not try to
guess any imported namespace as even the fully specified
namespace search is already not C++ compliant and more
assumptions could make it too magic. */
Index: testsuite/gdb.cp/derivation.cc
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/gdb.cp/derivation.cc,v
retrieving revision 1.5
diff -u -p -r1.5 derivation.cc
--- ./testsuite/gdb.cp/derivation.cc 1 Jan 2013 06:33:27 -0000 1.5
+++ ./testsuite/gdb.cp/derivation.cc 30 May 2013 22:47:02 -0000
@@ -16,6 +16,8 @@
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/

+extern void foo2 (); /* from derivation2.cc */
+
namespace N {
typedef double value_type;
struct Base { typedef int value_type; };
@@ -306,9 +308,7 @@ int main(void)
N::Derived::value_type d = 1;
N::value_type n = 3.0;
dobj.doit ();
+ foo2 ();
return 0;

}
-
-
-
Index: testsuite/gdb.cp/derivation.exp
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/gdb.cp/derivation.exp,v
retrieving revision 1.24
diff -u -p -r1.24 derivation.exp
--- ./testsuite/gdb.cp/derivation.exp 1 Jan 2013 06:33:27 -0000 1.24
+++ ./testsuite/gdb.cp/derivation.exp 30 May 2013 22:47:02 -0000
@@ -32,14 +32,15 @@ if { [skip_cplus_tests] } { continue }

load_lib "cp-support.exp"

-standard_testfile .cc
+standard_testfile derivation.cc derivation2.cc

-if {[prepare_for_testing $testfile.exp $testfile $srcfile {debug c++}]} {
+if {[prepare_for_testing $testfile.exp $testfile \
+ [list $srcfile $srcfile2] {debug c++}]} {
return -1
}

# Check inheritance of typedefs.
-foreach klass {"A" "D" "E" "F"} {
+foreach klass {"A" "D" "E" "F" "A2" "D2"} {
gdb_test "ptype ${klass}::value_type" "type = int"
gdb_test "whatis ${klass}::value_type" "type = int"
gdb_test "p (${klass}::value_type) 0" " = 0"
@@ -57,6 +58,13 @@ if ![runto 'marker1'] then {
continue
}

+# Check inheritance of typedefs again, but this time with an active block.
+foreach klass {"A" "D" "A2" "D2"} {
+ gdb_test "ptype ${klass}::value_type" "type = int"
+ gdb_test "whatis ${klass}::value_type" "type = int"
+ gdb_test "p (${klass}::value_type) 0" " = 0"
+}
+
gdb_test "up" ".*main.*" "up from marker1"

# Print class types and values.
Index: testsuite/gdb.cp/derivation2.cc
===================================================================
RCS file: testsuite/gdb.cp/derivation2.cc
diff -N testsuite/gdb.cp/derivation2.cc
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ ./testsuite/gdb.cp/derivation2.cc 30 May 2013 22:47:02 -0000
@@ -0,0 +1,49 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2013 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/>.
+ */
+
+/* A copy of some classes in derivation.cc so that we can test symbol lookup
+ in other CUs. */
+
+class A2 {
+public:
+ typedef int value_type;
+ value_type a;
+
+ A2()
+ {
+ a=1;
+ }
+};
+
+class D2 : public A2 {
+public:
+ value_type d;
+
+ D2()
+ {
+ d=7;
+ }
+};
+
+void
+foo2 ()
+{
+ D2 d2_instance;
+ d2_instance.a = 42;
+ d2_instance.d = 43;
+}