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Re: [patch] Support constant DW_AT_data_member_location by GCC PR debug/40659
On Fri, 14 Aug 2009 22:58:52 +0200, Tom Tromey wrote:
> >>>>> "Jan" == Jan Kratochvil <jan.kratochvil@redhat.com> writes:
> Jan> - if (attr_form_is_section_offset (attr))
> Jan> - {
> Jan> - dwarf2_complex_location_expr_complaint ();
> Jan> - byte_offset = 0;
>
> IIUC the patch still will issue a complaint for this construct, but now
> it just issues a more generic one from dwarf2_get_attr_constant_value.
>
> What about putting the more specific checks into that function instead?
> Would it cause some problem?
Thanks for the review, I found out now DWARF3 is very particular which classes
(constant, block, loclistptr, reference etc.) are permitted for which
attribute names (DW_AT_*) - Figure 20, page 138 (150/267).
My patch was extending a bit the classes permitted for some attributes which
is probably wrong.
Moreover DWARF4 draft makes some changes for it:
http://www.dwarfstd.org/doc/DWARF4-draft4-090815.pdf
# In DWARF V3 the forms DW_FORM_data4 and DW_FORM_data8 were members of either
# class constant or one of the classes lineptr, loclistptr, macptr or
# rangelistptr, depending on context. In DWARF V4 DW_FORM_data4 and
# DW_FORM_data8 are members of class constant in all cases. The new
# DW_FORM_sec_offset replaces their usage for the other classes.
Therefore rewritten the patch in a very conservative way fully following the
current GDB style.
The patch only follows DWARF3, it does not try to implement anything from
DWARF4.
Regression tested on {x86_64,i686}-fedora11-linux-gnu.
Thanks,
Jan
gdb/
2009-08-26 Jan Kratochvil <jan.kratochvil@redhat.com>
Support constant DW_AT_data_member_location by GCC PR debug/40659.
* dwarf2read.c
(dwarf2_add_field <DW_TAG_member> <DW_AT_data_member_location>):
Initialize BYTE_OFFSET to 0 by default. Explicitly check if
attr_form_is_block.
(dwarf2_add_field <DW_TAG_inheritance> <DW_AT_data_member_location>)
(read_common_block <DW_AT_data_member_location>): New variable
byte_offset. Fix crash on non-DW_BLOCK ATTR values.
gdb/testsuite/
2009-08-26 Jan Kratochvil <jan.kratochvil@redhat.com>
Support constant DW_AT_data_member_location by GCC PR debug/40659.
* gdb.dwarf2/dw2-inheritance.exp, gdb.dwarf2/dw2-inheritance.S: New.
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -4385,17 +4385,16 @@ dwarf2_add_field (struct field_info *fip, struct die_info *die,
attr = dwarf2_attr (die, DW_AT_data_member_location, cu);
if (attr)
{
- int byte_offset;
+ int byte_offset = 0;
if (attr_form_is_section_offset (attr))
- {
- dwarf2_complex_location_expr_complaint ();
- byte_offset = 0;
- }
+ dwarf2_complex_location_expr_complaint ();
else if (attr_form_is_constant (attr))
byte_offset = dwarf2_get_attr_constant_value (attr, 0);
- else
+ else if (attr_form_is_block (attr))
byte_offset = decode_locdesc (DW_BLOCK (attr), cu);
+ else
+ dwarf2_complex_location_expr_complaint ();
SET_FIELD_BITPOS (*fp, byte_offset * bits_per_byte);
}
@@ -4490,8 +4489,20 @@ dwarf2_add_field (struct field_info *fip, struct die_info *die,
/* C++ base class field. */
attr = dwarf2_attr (die, DW_AT_data_member_location, cu);
if (attr)
- SET_FIELD_BITPOS (*fp, decode_locdesc (DW_BLOCK (attr), cu)
- * bits_per_byte);
+ {
+ int byte_offset = 0;
+
+ if (attr_form_is_section_offset (attr))
+ dwarf2_complex_location_expr_complaint ();
+ else if (attr_form_is_constant (attr))
+ byte_offset = dwarf2_get_attr_constant_value (attr, 0);
+ else if (attr_form_is_block (attr))
+ byte_offset = decode_locdesc (DW_BLOCK (attr), cu);
+ else
+ dwarf2_complex_location_expr_complaint ();
+
+ SET_FIELD_BITPOS (*fp, byte_offset * bits_per_byte);
+ }
FIELD_BITSIZE (*fp) = 0;
FIELD_TYPE (*fp) = die_type (die, cu);
FIELD_NAME (*fp) = type_name_no_tag (fp->type);
@@ -5438,8 +5449,18 @@ read_common_block (struct die_info *die, struct dwarf2_cu *cu)
attr = dwarf2_attr (child_die, DW_AT_data_member_location, cu);
if (attr)
{
- SYMBOL_VALUE_ADDRESS (sym) =
- base + decode_locdesc (DW_BLOCK (attr), cu);
+ CORE_ADDR byte_offset = 0;
+
+ if (attr_form_is_section_offset (attr))
+ dwarf2_complex_location_expr_complaint ();
+ else if (attr_form_is_constant (attr))
+ byte_offset = dwarf2_get_attr_constant_value (attr, 0);
+ else if (attr_form_is_block (attr))
+ byte_offset = decode_locdesc (DW_BLOCK (attr), cu);
+ else
+ dwarf2_complex_location_expr_complaint ();
+
+ SYMBOL_VALUE_ADDRESS (sym) = base + byte_offset;
add_symbol_to_list (sym, &global_symbols);
}
child_die = sibling_die (child_die);
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-inheritance.S
@@ -0,0 +1,98 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2009 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/>. */
+
+/* Test DW_TAG_inheritance using constant DW_AT_data_member_location
+ introduced by GCC PR debug/40659. */
+
+/* Debug information */
+
+ .section .debug_info
+.Lcu1_begin:
+ /* CU header */
+ .4byte .Lcu1_end - .Lcu1_start /* Length of Compilation Unit */
+.Lcu1_start:
+ .2byte 2 /* DWARF Version */
+ .4byte .Labbrev1_begin /* Offset into abbrev section */
+ .byte 4 /* Pointer size */
+
+ /* CU die */
+ .uleb128 1 /* Abbrev: DW_TAG_compile_unit */
+ .4byte .Lline1_begin /* DW_AT_stmt_list */
+ .ascii "file1.txt\0" /* DW_AT_name */
+ .ascii "GNU C 3.3.3\0" /* DW_AT_producer */
+ .byte 4 /* DW_LANG_C_plus_plus (C++) */
+
+.Lbase:
+ .uleb128 3 /* Abbrev: DW_TAG_class_type */
+ .ascii "base\0" /* DW_AT_name */
+ .byte 4 /* DW_AT_byte_size */
+
+ .byte 0 /* End of children of "base" */
+
+ .uleb128 3 /* Abbrev: DW_TAG_class_type */
+ .ascii "inherited\0" /* DW_AT_name */
+ .byte 8 /* DW_AT_byte_size */
+
+ .uleb128 2 /* Abbrev: DW_TAG_inheritance */
+ .4byte .Lbase-.Lcu1_begin /* DW_AT_type */
+ .byte 0 /* DW_AT_data_member_location */
+
+ .byte 0 /* End of children of "inherited" */
+
+ .byte 0 /* End of children of CU */
+
+.Lcu1_end:
+
+/* Abbrev table */
+ .section .debug_abbrev
+.Labbrev1_begin:
+ .uleb128 1 /* Abbrev code */
+ .uleb128 0x11 /* DW_TAG_compile_unit */
+ .byte 1 /* has_children */
+ .uleb128 0x10 /* DW_AT_stmt_list */
+ .uleb128 0x6 /* DW_FORM_data4 */
+ .uleb128 0x3 /* DW_AT_name */
+ .uleb128 0x8 /* DW_FORM_string */
+ .uleb128 0x25 /* DW_AT_producer */
+ .uleb128 0x8 /* DW_FORM_string */
+ .uleb128 0x13 /* DW_AT_language */
+ .uleb128 0xb /* DW_FORM_data1 */
+ .byte 0x0 /* Terminator */
+ .byte 0x0 /* Terminator */
+
+ .uleb128 2 /* Abbrev code */
+ .uleb128 0x1c /* DW_TAG_inheritance */
+ .byte 0 /* has_children */
+ .uleb128 0x49 /* DW_AT_type */
+ .uleb128 0x13 /* DW_FORM_ref4 */
+ .uleb128 0x38 /* DW_AT_data_member_location */
+ .uleb128 0xb /* DW_FORM_data1 */
+ .byte 0x0 /* Terminator */
+ .byte 0x0 /* Terminator */
+
+ .uleb128 3 /* Abbrev code */
+ .uleb128 0x02 /* DW_TAG_class_type */
+ .byte 1 /* has_children */
+ .uleb128 0x3 /* DW_AT_name */
+ .uleb128 0x8 /* DW_FORM_string */
+ .uleb128 0xb /* DW_AT_byte_size */
+ .uleb128 0xb /* DW_FORM_data1 */
+ .byte 0x0 /* Terminator */
+ .byte 0x0 /* Terminator */
+
+ .byte 0x0 /* Terminator */
+ .byte 0x0 /* Terminator */
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-inheritance.exp
@@ -0,0 +1,40 @@
+# Copyright 2009 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/>.
+
+# Test DW_TAG_inheritance using constant DW_AT_data_member_location
+# introduced by GCC PR debug/40659.
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+# For now pick a sampling of likely targets.
+if {![istarget *-*-linux*]
+ && ![istarget *-*-gnu*]
+ && ![istarget *-*-elf*]
+ && ![istarget *-*-openbsd*]
+ && ![istarget arm-*-eabi*]
+ && ![istarget powerpc-*-eabi*]} {
+ return 0
+}
+
+set testfile "dw2-inheritance"
+set srcfile ${testfile}.S
+set executable ${testfile}.x
+
+if { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${objdir}/${subdir}/${executable}" object {nodebug}] != "" } {
+ return -1
+}
+
+clean_restart $executable
+
+gdb_test "ptype inherited" "type = class inherited .*"