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[PATCH] [1/2] value_fetch_lazy - ensure parent is not lazy before accessing.


Hi,

Within value_fetch_lazy, for bit field values we
make use of the parent value without first checking
that the parent is not lazy.

Ideally we'd only fetch that portion of the parent value
that was required to get the contents of the sub-field
value, but I don't believe this is currently supported,
so I offer the patch below.

You might think that the expected test results are a 
little strange, in some cases we report <optimized out>,
and in other cases we throw an error, patch [2/2] to
follow shortly.

OK to apply?


Thanks,
Andrew

gdb/ChangeLog

2013-07-11  Andrew Burgess  <aburgess@broadcom.com>

	* value.c (value_fetch_lazy): Ensure parent value is not lazy
	before checking which bits of the parent are valid.

gdb/testsuite/ChangeLog

2013-07-11  Andrew Burgess  <aburgess@broadcom.com>

	* gdb.dwarf2/pieces-optimized-out.exp: New file.
	* gdb.dwarf2/pieces-optimized-out.c: New file.
	* gdb.dwarf2/pieces-optimized-out.S: New file.

diff --git a/gdb/value.c b/gdb/value.c
index 04f325f..8e0f8c4 100644
--- a/gdb/value.c
+++ b/gdb/value.c
@@ -3433,7 +3433,10 @@ value_fetch_lazy (struct value *val)
       LONGEST offset = value_offset (val);
       LONGEST num;
 
-      if (!value_bits_valid (val,
+      if (value_lazy (parent))
+	value_fetch_lazy (parent);
+
+      if (!value_bits_valid (parent,
 			     TARGET_CHAR_BIT * offset + value_bitpos (val),
 			     value_bitsize (val)))
 	error (_("value has been optimized out"));
diff --git a/gdb/testsuite/gdb.dwarf2/pieces-optimized-out.S b/gdb/testsuite/gdb.dwarf2/pieces-optimized-out.S
new file mode 100644
index 0000000..06aa707
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/pieces-optimized-out.S
@@ -0,0 +1,548 @@
+/*
+   Copyright 2010-2013 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/>.  */
+
+/* This was compiled with gcc version 4.7.2 using:
+        gcc -O3 -m32 -g -o pieces-optimized-out.S -S pieces-optimized-out.c
+   The contents of this file are otherwise unmodified.  */
+
+        .file	"pieces-optimized-out.c"
+	.text
+.Ltext0:
+	.p2align 4,,15
+	.globl	foo
+	.type	foo, @function
+foo:
+.LFB0:
+	.file 1 "pieces-optimized-out.c"
+	.loc 1 33 0
+.LVL0:
+	.loc 1 35 0
+	movl	4(%esp), %eax
+	ret
+.LFE0:
+	.size	foo, .-foo
+	.section	.text.startup,"ax",@progbits
+	.p2align 4,,15
+	.globl	main
+	.type	main, @function
+main:
+.LFB1:
+	.loc 1 39 0
+.LVL1:
+	subl	$4, %esp
+.LCFI0:
+	.loc 1 44 0
+	movl	$10, (%esp)
+	call	foo
+.LVL2:
+	.loc 1 46 0
+	addl	$4, %esp
+.LCFI1:
+	.loc 1 45 0
+	addl	$20, %eax
+.LVL3:
+	.loc 1 46 0
+	ret
+.LFE1:
+	.size	main, .-main
+	.section	.debug_frame,"",@progbits
+.Lframe0:
+	.long	.LECIE0-.LSCIE0
+.LSCIE0:
+	.long	0xffffffff
+	.byte	0x1
+	.string	""
+	.uleb128 0x1
+	.sleb128 -4
+	.byte	0x8
+	.byte	0xc
+	.uleb128 0x4
+	.uleb128 0x4
+	.byte	0x88
+	.uleb128 0x1
+	.align 4
+.LECIE0:
+.LSFDE0:
+	.long	.LEFDE0-.LASFDE0
+.LASFDE0:
+	.long	.Lframe0
+	.long	.LFB0
+	.long	.LFE0-.LFB0
+	.align 4
+.LEFDE0:
+.LSFDE2:
+	.long	.LEFDE2-.LASFDE2
+.LASFDE2:
+	.long	.Lframe0
+	.long	.LFB1
+	.long	.LFE1-.LFB1
+	.byte	0x4
+	.long	.LCFI0-.LFB1
+	.byte	0xe
+	.uleb128 0x8
+	.byte	0x4
+	.long	.LCFI1-.LCFI0
+	.byte	0xe
+	.uleb128 0x4
+	.align 4
+.LEFDE2:
+	.section	.eh_frame,"a",@progbits
+.Lframe1:
+	.long	.LECIE1-.LSCIE1
+.LSCIE1:
+	.long	0
+	.byte	0x1
+	.string	""
+	.uleb128 0x1
+	.sleb128 -4
+	.byte	0x8
+	.byte	0xc
+	.uleb128 0x4
+	.uleb128 0x4
+	.byte	0x88
+	.uleb128 0x1
+	.align 4
+.LECIE1:
+.LSFDE5:
+	.long	.LEFDE5-.LASFDE5
+.LASFDE5:
+	.long	.LASFDE5-.Lframe1
+	.long	.LFB0
+	.long	.LFE0-.LFB0
+	.align 4
+.LEFDE5:
+.LSFDE7:
+	.long	.LEFDE7-.LASFDE7
+.LASFDE7:
+	.long	.LASFDE7-.Lframe1
+	.long	.LFB1
+	.long	.LFE1-.LFB1
+	.byte	0x4
+	.long	.LCFI0-.LFB1
+	.byte	0xe
+	.uleb128 0x8
+	.byte	0x4
+	.long	.LCFI1-.LCFI0
+	.byte	0xe
+	.uleb128 0x4
+	.align 4
+.LEFDE7:
+	.text
+.Letext0:
+	.section	.debug_info,"",@progbits
+.Ldebug_info0:
+	.long	0xe4
+	.value	0x2
+	.long	.Ldebug_abbrev0
+	.byte	0x4
+	.uleb128 0x1
+	.long	.LASF0
+	.byte	0x1
+	.long	.LASF1
+	.long	.LASF2
+	.long	.Ldebug_ranges0+0
+	.long	0
+	.long	0
+	.long	.Ldebug_line0
+	.uleb128 0x2
+	.string	"str"
+	.byte	0xc
+	.byte	0x1
+	.byte	0x17
+	.long	0x6c
+	.uleb128 0x3
+	.string	"a"
+	.byte	0x1
+	.byte	0x19
+	.long	0x6c
+	.byte	0x2
+	.byte	0x23
+	.uleb128 0
+	.uleb128 0x3
+	.string	"b"
+	.byte	0x1
+	.byte	0x1a
+	.long	0x6c
+	.byte	0x2
+	.byte	0x23
+	.uleb128 0x4
+	.uleb128 0x4
+	.string	"c"
+	.byte	0x1
+	.byte	0x1b
+	.long	0x6c
+	.byte	0x4
+	.byte	0x3
+	.byte	0x1d
+	.byte	0x2
+	.byte	0x23
+	.uleb128 0x8
+	.uleb128 0x4
+	.string	"d"
+	.byte	0x1
+	.byte	0x1c
+	.long	0x6c
+	.byte	0x4
+	.byte	0x3
+	.byte	0x1a
+	.byte	0x2
+	.byte	0x23
+	.uleb128 0x8
+	.byte	0
+	.uleb128 0x5
+	.byte	0x4
+	.byte	0x5
+	.string	"int"
+	.uleb128 0x6
+	.byte	0x1
+	.string	"foo"
+	.byte	0x1
+	.byte	0x20
+	.byte	0x1
+	.long	0x6c
+	.long	.LFB0
+	.long	.LFE0
+	.byte	0x2
+	.byte	0x74
+	.sleb128 4
+	.byte	0x1
+	.long	0x9f
+	.uleb128 0x7
+	.string	"arg"
+	.byte	0x1
+	.byte	0x20
+	.long	0x6c
+	.byte	0x2
+	.byte	0x91
+	.sleb128 0
+	.byte	0
+	.uleb128 0x8
+	.byte	0x1
+	.long	.LASF3
+	.byte	0x1
+	.byte	0x26
+	.byte	0x1
+	.long	0x6c
+	.long	.LFB1
+	.long	.LFE1
+	.long	.LLST0
+	.byte	0x1
+	.uleb128 0x9
+	.string	"s"
+	.byte	0x1
+	.byte	0x28
+	.long	0x29
+	.byte	0x6
+	.byte	0x35
+	.byte	0x9f
+	.byte	0x93
+	.uleb128 0x4
+	.byte	0x93
+	.uleb128 0x8
+	.uleb128 0xa
+	.string	"v"
+	.byte	0x1
+	.byte	0x29
+	.long	0x6c
+	.long	.LLST1
+	.uleb128 0xb
+	.long	.LVL2
+	.long	0x73
+	.uleb128 0xc
+	.byte	0x2
+	.byte	0x74
+	.sleb128 0
+	.byte	0x1
+	.byte	0x3a
+	.byte	0
+	.byte	0
+	.byte	0
+	.section	.debug_abbrev,"",@progbits
+.Ldebug_abbrev0:
+	.uleb128 0x1
+	.uleb128 0x11
+	.byte	0x1
+	.uleb128 0x25
+	.uleb128 0xe
+	.uleb128 0x13
+	.uleb128 0xb
+	.uleb128 0x3
+	.uleb128 0xe
+	.uleb128 0x1b
+	.uleb128 0xe
+	.uleb128 0x55
+	.uleb128 0x6
+	.uleb128 0x11
+	.uleb128 0x1
+	.uleb128 0x52
+	.uleb128 0x1
+	.uleb128 0x10
+	.uleb128 0x6
+	.byte	0
+	.byte	0
+	.uleb128 0x2
+	.uleb128 0x13
+	.byte	0x1
+	.uleb128 0x3
+	.uleb128 0x8
+	.uleb128 0xb
+	.uleb128 0xb
+	.uleb128 0x3a
+	.uleb128 0xb
+	.uleb128 0x3b
+	.uleb128 0xb
+	.uleb128 0x1
+	.uleb128 0x13
+	.byte	0
+	.byte	0
+	.uleb128 0x3
+	.uleb128 0xd
+	.byte	0
+	.uleb128 0x3
+	.uleb128 0x8
+	.uleb128 0x3a
+	.uleb128 0xb
+	.uleb128 0x3b
+	.uleb128 0xb
+	.uleb128 0x49
+	.uleb128 0x13
+	.uleb128 0x38
+	.uleb128 0xa
+	.byte	0
+	.byte	0
+	.uleb128 0x4
+	.uleb128 0xd
+	.byte	0
+	.uleb128 0x3
+	.uleb128 0x8
+	.uleb128 0x3a
+	.uleb128 0xb
+	.uleb128 0x3b
+	.uleb128 0xb
+	.uleb128 0x49
+	.uleb128 0x13
+	.uleb128 0xb
+	.uleb128 0xb
+	.uleb128 0xd
+	.uleb128 0xb
+	.uleb128 0xc
+	.uleb128 0xb
+	.uleb128 0x38
+	.uleb128 0xa
+	.byte	0
+	.byte	0
+	.uleb128 0x5
+	.uleb128 0x24
+	.byte	0
+	.uleb128 0xb
+	.uleb128 0xb
+	.uleb128 0x3e
+	.uleb128 0xb
+	.uleb128 0x3
+	.uleb128 0x8
+	.byte	0
+	.byte	0
+	.uleb128 0x6
+	.uleb128 0x2e
+	.byte	0x1
+	.uleb128 0x3f
+	.uleb128 0xc
+	.uleb128 0x3
+	.uleb128 0x8
+	.uleb128 0x3a
+	.uleb128 0xb
+	.uleb128 0x3b
+	.uleb128 0xb
+	.uleb128 0x27
+	.uleb128 0xc
+	.uleb128 0x49
+	.uleb128 0x13
+	.uleb128 0x11
+	.uleb128 0x1
+	.uleb128 0x12
+	.uleb128 0x1
+	.uleb128 0x40
+	.uleb128 0xa
+	.uleb128 0x2117
+	.uleb128 0xc
+	.uleb128 0x1
+	.uleb128 0x13
+	.byte	0
+	.byte	0
+	.uleb128 0x7
+	.uleb128 0x5
+	.byte	0
+	.uleb128 0x3
+	.uleb128 0x8
+	.uleb128 0x3a
+	.uleb128 0xb
+	.uleb128 0x3b
+	.uleb128 0xb
+	.uleb128 0x49
+	.uleb128 0x13
+	.uleb128 0x2
+	.uleb128 0xa
+	.byte	0
+	.byte	0
+	.uleb128 0x8
+	.uleb128 0x2e
+	.byte	0x1
+	.uleb128 0x3f
+	.uleb128 0xc
+	.uleb128 0x3
+	.uleb128 0xe
+	.uleb128 0x3a
+	.uleb128 0xb
+	.uleb128 0x3b
+	.uleb128 0xb
+	.uleb128 0x27
+	.uleb128 0xc
+	.uleb128 0x49
+	.uleb128 0x13
+	.uleb128 0x11
+	.uleb128 0x1
+	.uleb128 0x12
+	.uleb128 0x1
+	.uleb128 0x40
+	.uleb128 0x6
+	.uleb128 0x2117
+	.uleb128 0xc
+	.byte	0
+	.byte	0
+	.uleb128 0x9
+	.uleb128 0x34
+	.byte	0
+	.uleb128 0x3
+	.uleb128 0x8
+	.uleb128 0x3a
+	.uleb128 0xb
+	.uleb128 0x3b
+	.uleb128 0xb
+	.uleb128 0x49
+	.uleb128 0x13
+	.uleb128 0x2
+	.uleb128 0xa
+	.byte	0
+	.byte	0
+	.uleb128 0xa
+	.uleb128 0x34
+	.byte	0
+	.uleb128 0x3
+	.uleb128 0x8
+	.uleb128 0x3a
+	.uleb128 0xb
+	.uleb128 0x3b
+	.uleb128 0xb
+	.uleb128 0x49
+	.uleb128 0x13
+	.uleb128 0x2
+	.uleb128 0x6
+	.byte	0
+	.byte	0
+	.uleb128 0xb
+	.uleb128 0x4109
+	.byte	0x1
+	.uleb128 0x11
+	.uleb128 0x1
+	.uleb128 0x31
+	.uleb128 0x13
+	.byte	0
+	.byte	0
+	.uleb128 0xc
+	.uleb128 0x410a
+	.byte	0
+	.uleb128 0x2
+	.uleb128 0xa
+	.uleb128 0x2111
+	.uleb128 0xa
+	.byte	0
+	.byte	0
+	.byte	0
+	.section	.debug_loc,"",@progbits
+.Ldebug_loc0:
+.LLST0:
+	.long	.LFB1
+	.long	.LCFI0
+	.value	0x2
+	.byte	0x74
+	.sleb128 4
+	.long	.LCFI0
+	.long	.LCFI1
+	.value	0x2
+	.byte	0x74
+	.sleb128 8
+	.long	.LCFI1
+	.long	.LFE1
+	.value	0x2
+	.byte	0x74
+	.sleb128 4
+	.long	0
+	.long	0
+.LLST1:
+	.long	.LVL1
+	.long	.LVL2
+	.value	0x2
+	.byte	0x3a
+	.byte	0x9f
+	.long	.LVL2
+	.long	.LVL3
+	.value	0x3
+	.byte	0x70
+	.sleb128 10
+	.byte	0x9f
+	.long	.LVL3
+	.long	.LFE1
+	.value	0x3
+	.byte	0x70
+	.sleb128 -10
+	.byte	0x9f
+	.long	0
+	.long	0
+	.section	.debug_aranges,"",@progbits
+	.long	0x24
+	.value	0x2
+	.long	.Ldebug_info0
+	.byte	0x4
+	.byte	0
+	.value	0
+	.value	0
+	.long	.Ltext0
+	.long	.Letext0-.Ltext0
+	.long	.LFB1
+	.long	.LFE1-.LFB1
+	.long	0
+	.long	0
+	.section	.debug_ranges,"",@progbits
+.Ldebug_ranges0:
+	.long	.Ltext0
+	.long	.Letext0
+	.long	.LFB1
+	.long	.LFE1
+	.long	0
+	.long	0
+	.section	.debug_line,"",@progbits
+.Ldebug_line0:
+	.section	.debug_str,"MS",@progbits,1
+.LASF2:
+	.string	"/home/username/"
+.LASF1:
+	.string	"pieces-optimized-out.c"
+.LASF0:
+	.string	"GNU C 4.7.2"
+.LASF3:
+	.string	"main"
+	.ident	"GCC: (GNU) 4.7.2"
+	.section	.note.GNU-stack,"",@progbits
diff --git a/gdb/testsuite/gdb.dwarf2/pieces-optimized-out.c b/gdb/testsuite/gdb.dwarf2/pieces-optimized-out.c
new file mode 100644
index 0000000..2bf9cf8
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/pieces-optimized-out.c
@@ -0,0 +1,47 @@
+/* Copyright (C) 2013 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   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/>.  */
+
+/* This file is not actually compiled, the .S file is committed alongside
+   this file.  The reason is that changes to the compiler might result
+   in different debug information being created, this could break the
+   test.  */
+
+struct str
+{
+  int a;
+  int b;
+  int c : 3;
+  int d : 3;
+};
+
+int __attribute__ ((noinline))
+foo (int arg)
+{  
+  return arg;
+}
+
+int
+main ( void )
+{
+  struct str s = {5, 7, 1, 2};
+  int v;
+
+  v = (s.a << 1);
+  v += foo (v);
+  return v + 5 + s.a;
+}
+
diff --git a/gdb/testsuite/gdb.dwarf2/pieces-optimized-out.exp b/gdb/testsuite/gdb.dwarf2/pieces-optimized-out.exp
new file mode 100644
index 0000000..2e4d028
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/pieces-optimized-out.exp
@@ -0,0 +1,49 @@
+# 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 dwarf.exp
+# Test some DWARF piece operators.
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+if {![dwarf2_support]} {
+    return 0  
+}
+# This test can only be run on x86 targets.
+if {![is_x86_like_target]} {
+    return 0  
+}
+
+standard_testfile .S
+set csrcfile ${testfile}.c
+
+if {[prepare_for_testing ${testfile}.exp ${testfile} $srcfile]} {
+    return -1
+}
+
+if ![runto foo] {
+    return -1
+}
+
+# Move back up to main.
+gdb_test "up" "#1  $hex in main.*" "move up a frame"
+
+# Now take a look at the 's' structure.
+gdb_test "p s" \
+    " = {a = 5, b = <optimized out>, c = <optimized out>, d = <optimized out>}" \
+    "print s"
+gdb_test "p s.a" " = 5" "print s.a"
+gdb_test "p s.b" " = <optimized out>" "print s.b"
+gdb_test "p s.c" "value has been optimized out" "print s.c"
+gdb_test "p s.d" "value has been optimized out" "print s.d"
+


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