Re: [patch] Fix internal error on optimized-out values (regression by me)

[Jan Kratochvil <jan.kratochvil@redhat.com>]

On Mon, 03 Oct 2011 21:34:16 +0200, Tom Tromey wrote:
> >>>>> "Jan" == Jan Kratochvil <jan.kratochvil@redhat.com> writes:
> 
> Jan> ((struct) <optimized out>).field should be IMO still <optimized
> Jan> out>; just it became internal-error now.
> 
> Maybe I am misunderstanding what you are saying -- I think this should
> also throw.  I think the rule should be that any attempt to access any
> "invalid" contents of a value, for purposes of computation, should throw
> an exception.

Here is problematic the term "for purposes of computation".

I agree that any computation with content of <optimized out> must throw.

But here the content is not interpreted in any way.  Only a smaller subset of
it is used.


But I do not have any argument why the former <optimized out> value is better
than this "value has been optimized out", unaware if there is a precedent for
either way in current codebase.  Changed it as you suggest.

No regressions on {x86_64,x86_64-m32,i686}-fedora16pre-linux-gnu.


Thanks,
Jan


gdb/
2011-10-10  Jan Kratochvil  <jan.kratochvil@redhat.com>

	Fix internal error regression.
	* value.c (value_primitive_field): Add require_not_optimized_out.

gdb/testsuite/
2011-10-10  Jan Kratochvil  <jan.kratochvil@redhat.com>

	Fix internal error regression.
	* gdb.dwarf2/implptr-optimized-out.S: New file.
	* gdb.dwarf2/implptr-optimized-out.exp: New file.

--- a/gdb/value.c
+++ b/gdb/value.c
@@ -2477,6 +2477,8 @@ value_primitive_field (struct value *arg1, int offset,
   struct value *v;
   struct type *type;
 
+  require_not_optimized_out (arg1);
+
   CHECK_TYPEDEF (arg_type);
   type = TYPE_FIELD_TYPE (arg_type, fieldno);
 
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/implptr-optimized-out.S
@@ -0,0 +1,166 @@
+/* Copyright 2010, 2011 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/>.  */
+
+	.section	.debug_info
+d:
+	.long	debug_end - 1f	/* Length of Compilation Unit Info */
+1:
+	.2byte	0x3	/* DWARF version number */
+	.long	.Ldebug_abbrev0	/* Offset Into Abbrev. Section */
+	.byte	0x4	/* Pointer Size (in bytes) */
+	.uleb128 0x1	/* (DIE (0xb) DW_TAG_compile_unit) */
+	.ascii "GNU C 4.4.3\0"	/* DW_AT_producer */
+	.byte	0x1	/* DW_AT_language */
+	.ascii "1.c\0"	/* DW_AT_name */
+
+.Ltype_int:
+	.uleb128 0x7	/* DW_TAG_base_type */
+	.byte	0x4	/* DW_AT_byte_size */
+	.byte	0x5	/* DW_AT_encoding */
+	.ascii "int\0"	/* DW_AT_name */
+
+.Ltype_struct:
+	.uleb128 0x2	/* DW_TAG_structure_type */
+	.ascii "s\0"	/* DW_AT_name */
+	.byte	4	/* DW_AT_byte_size */
+
+	.uleb128 0x3	/* DW_TAG_member */
+	.ascii "f\0"	/* DW_AT_name */
+	.4byte	.Ltype_int - d	/* DW_AT_type */
+	.byte	0	/* DW_AT_data_member_location */
+
+	.byte	0x0	/* end of children of DW_TAG_structure_type */
+
+	.uleb128	6			/* Abbrev: DW_TAG_subprogram */
+	.ascii		"main\0"		/* DW_AT_name */
+	.4byte		main			/* DW_AT_low_pc */
+	.4byte		main + 0x100		/* DW_AT_high_pc */
+	.4byte		.Ltype_int - d		/* DW_AT_type */
+	.byte		1			/* DW_AT_external */
+
+.Ltype_structptr:
+	.uleb128 0x5	/* DW_TAG_pointer_type */
+	.byte	0x4	/* DW_AT_byte_size */
+	.long	.Ltype_struct - d	/* DW_AT_type */
+
+.Lvar_out:
+	.uleb128 0x4	/* (DW_TAG_variable) */
+	.ascii "v\0"	/* DW_AT_name */
+	.byte	0	/* DW_AT_location: DW_FORM_block1 */
+	.4byte	.Ltype_struct - d	/* DW_AT_type */
+
+	.uleb128 0x4	/* (DW_TAG_variable) */
+	.ascii "p\0"	/* DW_AT_name */
+	.byte	2f - 1f	/* DW_AT_location: DW_FORM_block1 */
+1:
+	.byte	0xf2	/* DW_OP_GNU_implicit_pointer */
+	.4byte	.Lvar_out - d	/* referenced DIE */
+	.sleb128	0	/* offset */
+2:
+	.4byte	.Ltype_structptr - d	/* DW_AT_type */
+
+	.byte	0x0	/* end of children of main */
+
+	.byte	0x0	/* end of children of CU */
+debug_end:
+
+	.section	.debug_abbrev
+.Ldebug_abbrev0:
+
+	.uleb128 0x1	/* (abbrev code) */
+	.uleb128 0x11	/* (TAG: DW_TAG_compile_unit) */
+	.byte	0x1	/* DW_children_yes */
+	.uleb128 0x25	/* (DW_AT_producer) */
+	.uleb128 0x8	/* (DW_FORM_string) */
+	.uleb128 0x13	/* (DW_AT_language) */
+	.uleb128 0xb	/* (DW_FORM_data1) */
+	.uleb128 0x3	/* (DW_AT_name) */
+	.uleb128 0x8	/* (DW_FORM_string) */
+	.byte	0x0
+	.byte	0x0
+
+	.uleb128 0x2	/* (abbrev code) */
+	.uleb128 0x13	/* (TAG: DW_TAG_structure_type) */
+	.byte	0x1	/* DW_children_yes */
+	.uleb128 0x3	/* (DW_AT_name) */
+	.uleb128 0x8	/* (DW_FORM_string) */
+	.uleb128 0xb	/* (DW_AT_byte_size) */
+	.uleb128 0xb	/* (DW_FORM_data1) */
+	.byte	0
+	.byte	0
+
+	.uleb128 0x3	/* (abbrev code) */
+	.uleb128 0xd	/* (TAG: DW_TAG_member) */
+	.byte	0	/* DW_children_no */
+	.uleb128 0x3	/* (DW_AT_name) */
+	.uleb128 0x8	/* (DW_FORM_string) */
+	.uleb128 0x49	/* (DW_AT_type) */
+	.uleb128 0x13	/* (DW_FORM_ref4) */
+	.uleb128 0x38	/* (DW_AT_data_member_location) */
+	.uleb128 0xb	/* (DW_FORM_data1) */
+	.byte	0
+	.byte	0
+
+	.uleb128 0x4	/* (abbrev code) */
+	.uleb128 0x34	/* (TAG: DW_TAG_variable) */
+	.byte	0x0	/* DW_children_yes */
+	.uleb128 0x3	/* (DW_AT_name) */
+	.uleb128 0x8	/* (DW_FORM_string) */
+	.uleb128 0x02	/* (DW_AT_location) */
+	.uleb128 0xa	/* (DW_FORM_block1) */
+	.uleb128 0x49	/* (DW_AT_type) */
+	.uleb128 0x13	/* (DW_FORM_ref4) */
+	.byte	0x0
+	.byte	0x0
+
+	.uleb128 0x5	/* (abbrev code) */
+	.uleb128 0xf	/* (TAG: DW_TAG_pointer_type) */
+	.byte	0x0	/* DW_children_no */
+	.uleb128 0xb	/* (DW_AT_byte_size) */
+	.uleb128 0xb	/* (DW_FORM_data1) */
+	.uleb128 0x49	/* (DW_AT_type) */
+	.uleb128 0x13	/* (DW_FORM_ref4) */
+	.byte	0x0
+	.byte	0x0
+
+	.uleb128	6			/* Abbrev code */
+	.uleb128	0x2e			/* DW_TAG_subprogram */
+	.byte		1			/* has_children */
+	.uleb128	0x3			/* DW_AT_name */
+	.uleb128	0x8			/* DW_FORM_string */
+	.uleb128	0x11			/* DW_AT_low_pc */
+	.uleb128	0x1			/* DW_FORM_addr */
+	.uleb128	0x12			/* DW_AT_high_pc */
+	.uleb128	0x1			/* DW_FORM_addr */
+	.uleb128	0x49			/* DW_AT_type */
+	.uleb128	0x13			/* DW_FORM_ref4 */
+	.uleb128	0x3f			/* DW_AT_external */
+	.uleb128	0xc			/* DW_FORM_flag */
+	.byte		0x0			/* Terminator */
+	.byte		0x0			/* Terminator */
+
+	.uleb128 0x7	/* (abbrev code) */
+	.uleb128 0x24	/* (TAG: DW_TAG_base_type) */
+	.byte	0	/* DW_children_no */
+	.uleb128 0xb	/* (DW_AT_byte_size) */
+	.uleb128 0xb	/* (DW_FORM_data1) */
+	.uleb128 0x3e	/* (DW_AT_encoding) */
+	.uleb128 0xb	/* (DW_FORM_data1) */
+	.uleb128 0x3	/* (DW_AT_name) */
+	.uleb128 0x8	/* (DW_FORM_string) */
+	.byte	0
+	.byte	0
+
+	.byte	0x0
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/implptr-optimized-out.exp
@@ -0,0 +1,37 @@
+# Copyright 2011 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 dwarf.exp
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+if {![dwarf2_support]} {
+    return 0  
+}
+
+set testfile "implptr-optimized-out"
+set srcfile ${testfile}.S
+set mainfile main.c
+set executable ${testfile}
+set binfile ${objdir}/${subdir}/${executable}
+
+if [prepare_for_testing ${testfile}.exp $executable "${srcfile} ${mainfile}" {}] {
+    return -1
+}
+
+# DW_OP_GNU_implicit_pointer implementation requires a valid frame.
+if ![runto_main] {
+    return -1
+}
+
+gdb_test "p p->f" "value has been optimized out"