[RFC/Windows] Ignore __fu<digits>__ symbols from COFF symbol tables
Joel Brobecker
brobecker@adacore.com
Fri Mar 22 06:17:00 GMT 2013
Hello,
The debugger sometimes prints strange function names for given
addresses. For instance, with the following source code...
4 procedure Foo is
5 A : Integer;
6 begin
7 Do_Nothing (A'Address);
8 end Foo;
... we can see...
(gdb) info line 5
Line 5 of "foo.adb" starts at address 0x4017ca <_ada_foo+6>
and ends at 0x4017d2 <_fu29__system__scalar_values__is_is4+7>.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
_fu29__system__scalar_values__is_is4 is an artificial symbol
generated by the linker, and interferes with the pc-to-symbol
resolution. There isn't much in the general minimal_symbol
data that could help us identify them, so this patch changes
the COFF reader to simply ignore them.
A little hacky, but contained, limited to targets using COFF,
and hopefully harmless, as long as one does not expect to be
able to print the value of those symbols.
gdb/ChangeLog:
* coffread.c (is_import_fixup_symbol): New function.
(record_minimal_symbol): Use is_import_fixup_symbol to
detect import fixup symbols, and discard them.
gdb/testsuite/ChangeLog:
* gdb.ada/win_fu_syms: New testcase.
Tested on x86-windows. Any thoughts on this?
Thanks a lot,
--
Joel
---
gdb/coffread.c | 43 +++++++++++++++++++++++++++++
gdb/testsuite/gdb.ada/win_fu_syms.exp | 35 +++++++++++++++++++++++
gdb/testsuite/gdb.ada/win_fu_syms/foo.adb | 23 +++++++++++++++
gdb/testsuite/gdb.ada/win_fu_syms/pck.adb | 21 ++++++++++++++
gdb/testsuite/gdb.ada/win_fu_syms/pck.ads | 19 +++++++++++++
5 files changed, 141 insertions(+)
create mode 100644 gdb/testsuite/gdb.ada/win_fu_syms.exp
create mode 100644 gdb/testsuite/gdb.ada/win_fu_syms/foo.adb
create mode 100644 gdb/testsuite/gdb.ada/win_fu_syms/pck.adb
create mode 100644 gdb/testsuite/gdb.ada/win_fu_syms/pck.ads
diff --git a/gdb/coffread.c b/gdb/coffread.c
index 3cc14ce..79e1a71 100644
--- a/gdb/coffread.c
+++ b/gdb/coffread.c
@@ -418,6 +418,39 @@ coff_end_symtab (struct objfile *objfile)
set_last_source_file (NULL);
}
+/* The linker sometimes generates some non-function symbols inside
+ functions referencing variables imported from another DLL.
+ Return nonzero if the given symbol corresponds to one of them. */
+
+static int
+is_import_fixup_symbol (struct coff_symbol *cs,
+ enum minimal_symbol_type type)
+{
+ /* The following is a bit of a heuristic using the characterictics
+ of these fixup symbols, but should work well in practice... */
+ int i;
+
+ /* Must be a non-static text symbol. */
+ if (type != mst_text)
+ return 0;
+
+ /* Must be a non-function symbol. */
+ if (ISFCN (cs->c_type))
+ return 0;
+
+ /* The name must start with "__fu<digits>__". */
+ if (strncmp (cs->c_name, "__fu", 4) != 0)
+ return 0;
+ if (! isdigit (cs->c_name[4]))
+ return 0;
+ for (i = 5; cs->c_name[i] != '\0' && isdigit (cs->c_name[i]); i++)
+ /* Nothing, just incrementing index past all digits. */;
+ if (cs->c_name[i] != '_' || cs->c_name[i + 1] != '_')
+ return 0;
+
+ return 1;
+}
+
static struct minimal_symbol *
record_minimal_symbol (struct coff_symbol *cs, CORE_ADDR address,
enum minimal_symbol_type type, int section,
@@ -429,6 +462,16 @@ record_minimal_symbol (struct coff_symbol *cs, CORE_ADDR address,
if (cs->c_name[0] == '@')
return NULL;
+ if (is_import_fixup_symbol (cs, type))
+ {
+ /* Because the value of these symbols is within a function code
+ range, these symbols interfere with the symbol-from-address
+ reverse lookup; this manifests itselfs in backtraces, or any
+ other commands that prints symbolic addresses. Just pretend
+ these symbols do not exist. */
+ return NULL;
+ }
+
bfd_section = cs_to_bfd_section (cs, objfile);
return prim_record_minimal_symbol_and_info (cs->c_name, address,
type, section,
diff --git a/gdb/testsuite/gdb.ada/win_fu_syms.exp b/gdb/testsuite/gdb.ada/win_fu_syms.exp
new file mode 100644
index 0000000..c3cbf16
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/win_fu_syms.exp
@@ -0,0 +1,35 @@
+# 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/>.
+
+load_lib "ada.exp"
+
+standard_ada_testfile foo
+
+if {[gdb_compile_ada "${srcfile}" "${binfile}" executable [list debug additional_flags=-bargs additional_flags=-shared additional_flags=-margs]] != "" } {
+ return -1
+}
+
+clean_restart ${testfile}
+
+set loc [gdb_get_line_number "Integer" ${testdir}/foo.adb]
+gdb_test "info line foo.adb:$loc" \
+ "Line $decimal of \".*foo\\.adb\" starts at address $hex <_ada_foo\\+$decimal> and ends at $hex <_ada_foo\\+$decimal>\\." \
+ "info line on variable declaration"
+
+set loc [gdb_get_line_number "Do_Nothing" ${testdir}/foo.adb]
+gdb_test "info line foo.adb:$loc" \
+ "Line $decimal of \".*foo\\.adb\" starts at address $hex <_ada_foo\\+$decimal> and ends at $hex <_ada_foo\\+$decimal>\\." \
+ "info line on Do_Nothing call"
+
diff --git a/gdb/testsuite/gdb.ada/win_fu_syms/foo.adb b/gdb/testsuite/gdb.ada/win_fu_syms/foo.adb
new file mode 100644
index 0000000..a09a346
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/win_fu_syms/foo.adb
@@ -0,0 +1,23 @@
+-- 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/>.
+
+pragma Initialize_Scalars;
+with Pck; use Pck;
+
+procedure Foo is
+ A : Integer;
+begin
+ Do_Nothing (A'Address);
+end Foo;
diff --git a/gdb/testsuite/gdb.ada/win_fu_syms/pck.adb b/gdb/testsuite/gdb.ada/win_fu_syms/pck.adb
new file mode 100644
index 0000000..808da4d
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/win_fu_syms/pck.adb
@@ -0,0 +1,21 @@
+-- Copyright 2007-2013 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/>.
+
+package body Pck is
+ procedure Do_Nothing (A : System.Address) is
+ begin
+ null;
+ end Do_Nothing;
+end Pck;
diff --git a/gdb/testsuite/gdb.ada/win_fu_syms/pck.ads b/gdb/testsuite/gdb.ada/win_fu_syms/pck.ads
new file mode 100644
index 0000000..d5791b2
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/win_fu_syms/pck.ads
@@ -0,0 +1,19 @@
+-- Copyright 2007-2013 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/>.
+
+with System;
+package Pck is
+ procedure Do_Nothing (A : System.Address);
+end Pck;
--
1.7.10.4
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