gdb/patches/gdb-optimized-out-internal-error.patch

   1 http://sourceware.org/ml/gdb-patches/2011-09/msg00449.html
   2 Subject: [patch] Fix internal error on optimized-out values (regression by me)
   3
   4 Hi,
   5
   6 since:
   7         Re: [patch] Code cleanup: Introduce allocate_optimized_out_value
   8         http://sourceware.org/ml/gdb-patches/2011-07/msg00327.html
   9         acfe85f56075910a3ba5e8b76189e0770079b8d1
  10 can occur:
  11         (gdb) p p->f
  12         valops.c:1118: internal-error: Unexpected lazy value type.
  13         A problem internal to GDB has been detected,
  14
  15 in that mail referenced above:
  16 # It is true it would be definitely a bug in a code incompatible with such
  17 # change so one may rather fix that possible regression there.
  18
  19 so this testcase exploits such case.  The problem is formerly the code
  20 allocated (in some cases) optimized out values as non-lazy ones.  Now they are
  21 allocated all as lazy (*) which breaks some code not expecting lazy values.
  22
  23 (*) Such lazy optimized out value still gets silently allocate_value_contents
  24     by value_fetch_lazy, allocate_value_contents should be suppressed in such
  25     case; such more radical change has never been made.
  26
  27 Formerly (incl. gdb-7.3) did:
  28         (gdb) p p->f
  29         $1 = 0
  30 which was also wrong, ((struct *) <optimized out>)->field should be IMO still
  31 <optimized out>; just it became internal-error now.
  32
  33 GDB usually does require_not_optimized_out throwing error() when it meets any
  34 first <optimized out> value.  I have just produced new optimized value
  35 instead; require_not_optimized_out is not exported and I find it better this
  36 way.
  37
  38 Following the rule that it is better if GDB does something wrong rather then
  39 it throws internal-error to make the patch from July above fully safe one
  40 would have to change allocate_optimized_out_value to allocate everything as
  41 non-lazy.  I find that as a too ugly workaround of the codebase.
  42
  43 No regressions on {x86_64,x86_64-m32,i686}-fedora16pre-linux-gnu.
  44
  45
  46 Andre, do you still see the bug even with this patch?
  47
  48
  49 Thanks,
  50 Jan
  51
  52
  53 gdb/
  54 2011-09-26  Jan Kratochvil  <jan.kratochvil@redhat.com>
  55
  56         Fix internal error regression.
  57         * value.c (value_primitive_field): Handle value_optimized_out.  Move
  58         packed bitfields comment.
  59
  60 gdb/testsuite/
  61 2011-09-26  Jan Kratochvil  <jan.kratochvil@redhat.com>
  62
  63         Fix internal error regression.
  64         * gdb.dwarf2/implptr-optimized-out.S: New file.
  65         * gdb.dwarf2/implptr-optimized-out.exp: New file.
  66
  67 --- a/gdb/value.c
  68 +++ b/gdb/value.c
  69 @@ -2482,16 +2482,19 @@ value_primitive_field (struct value *arg1, int offset,
  70       description correctly.  */
  71    check_typedef (type);
  72
  73 -  /* Handle packed fields */
  74 -
  75 -  if (TYPE_FIELD_BITSIZE (arg_type, fieldno))
  76 +  if (value_optimized_out (arg1))
  77 +    v = allocate_optimized_out_value (type);
  78 +  else if (TYPE_FIELD_BITSIZE (arg_type, fieldno))
  79      {
  80 -      /* Create a new value for the bitfield, with bitpos and bitsize
  81 +      /* Handle packed fields.
  82 +
  83 +        Create a new value for the bitfield, with bitpos and bitsize
  84          set.  If possible, arrange offset and bitpos so that we can
  85          do a single aligned read of the size of the containing type.
  86          Otherwise, adjust offset to the byte containing the first
  87          bit.  Assume that the address, offset, and embedded offset
  88          are sufficiently aligned.  */
  89 +
  90        int bitpos = TYPE_FIELD_BITPOS (arg_type, fieldno);
  91        int container_bitsize = TYPE_LENGTH (type) * 8;
  92
  93 --- /dev/null
  94 +++ b/gdb/testsuite/gdb.dwarf2/implptr-optimized-out.S
  95 @@ -0,0 +1,166 @@
  96 +/* Copyright 2010, 2011 Free Software Foundation, Inc.
  97 +
  98 +   This program is free software; you can redistribute it and/or modify
  99 +   it under the terms of the GNU General Public License as published by
 100 +   the Free Software Foundation; either version 3 of the License, or
 101 +   (at your option) any later version.
 102 +
 103 +   This program is distributed in the hope that it will be useful,
 104 +   but WITHOUT ANY WARRANTY; without even the implied warranty of
 105 +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 106 +   GNU General Public License for more details.
 107 +
 108 +   You should have received a copy of the GNU General Public License
 109 +   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 110 +
 111 +       .section        .debug_info
 112 +d:
 113 +       .long   debug_end - 1f  /* Length of Compilation Unit Info */
 114 +1:
 115 +       .2byte  0x3     /* DWARF version number */
 116 +       .long   .Ldebug_abbrev0 /* Offset Into Abbrev. Section */
 117 +       .byte   0x4     /* Pointer Size (in bytes) */
 118 +       .uleb128 0x1    /* (DIE (0xb) DW_TAG_compile_unit) */
 119 +       .ascii "GNU C 4.4.3\0"  /* DW_AT_producer */
 120 +       .byte   0x1     /* DW_AT_language */
 121 +       .ascii "1.c\0"  /* DW_AT_name */
 122 +
 123 +.Ltype_int:
 124 +       .uleb128 0x7    /* DW_TAG_base_type */
 125 +       .byte   0x4     /* DW_AT_byte_size */
 126 +       .byte   0x5     /* DW_AT_encoding */
 127 +       .ascii "int\0"  /* DW_AT_name */
 128 +
 129 +.Ltype_struct:
 130 +       .uleb128 0x2    /* DW_TAG_structure_type */
 131 +       .ascii "s\0"    /* DW_AT_name */
 132 +       .byte   4       /* DW_AT_byte_size */
 133 +
 134 +       .uleb128 0x3    /* DW_TAG_member */
 135 +       .ascii "f\0"    /* DW_AT_name */
 136 +       .4byte  .Ltype_int - d  /* DW_AT_type */
 137 +       .byte   0       /* DW_AT_data_member_location */
 138 +
 139 +       .byte   0x0     /* end of children of DW_TAG_structure_type */
 140 +
 141 +       .uleb128        6                       /* Abbrev: DW_TAG_subprogram */
 142 +       .ascii          "main\0"                /* DW_AT_name */
 143 +       .4byte          main                    /* DW_AT_low_pc */
 144 +       .4byte          main + 0x100            /* DW_AT_high_pc */
 145 +       .4byte          .Ltype_int - d          /* DW_AT_type */
 146 +       .byte           1                       /* DW_AT_external */
 147 +
 148 +.Ltype_structptr:
 149 +       .uleb128 0x5    /* DW_TAG_pointer_type */
 150 +       .byte   0x4     /* DW_AT_byte_size */
 151 +       .long   .Ltype_struct - d       /* DW_AT_type */
 152 +
 153 +.Lvar_out:
 154 +       .uleb128 0x4    /* (DW_TAG_variable) */
 155 +       .ascii "v\0"    /* DW_AT_name */
 156 +       .byte   0       /* DW_AT_location: DW_FORM_block1 */
 157 +       .4byte  .Ltype_struct - d       /* DW_AT_type */
 158 +
 159 +       .uleb128 0x4    /* (DW_TAG_variable) */
 160 +       .ascii "p\0"    /* DW_AT_name */
 161 +       .byte   2f - 1f /* DW_AT_location: DW_FORM_block1 */
 162 +1:
 163 +       .byte   0xf2    /* DW_OP_GNU_implicit_pointer */
 164 +       .4byte  .Lvar_out - d   /* referenced DIE */
 165 +       .sleb128        0       /* offset */
 166 +2:
 167 +       .4byte  .Ltype_structptr - d    /* DW_AT_type */
 168 +
 169 +       .byte   0x0     /* end of children of main */
 170 +
 171 +       .byte   0x0     /* end of children of CU */
 172 +debug_end:
 173 +
 174 +       .section        .debug_abbrev
 175 +.Ldebug_abbrev0:
 176 +
 177 +       .uleb128 0x1    /* (abbrev code) */
 178 +       .uleb128 0x11   /* (TAG: DW_TAG_compile_unit) */
 179 +       .byte   0x1     /* DW_children_yes */
 180 +       .uleb128 0x25   /* (DW_AT_producer) */
 181 +       .uleb128 0x8    /* (DW_FORM_string) */
 182 +       .uleb128 0x13   /* (DW_AT_language) */
 183 +       .uleb128 0xb    /* (DW_FORM_data1) */
 184 +       .uleb128 0x3    /* (DW_AT_name) */
 185 +       .uleb128 0x8    /* (DW_FORM_string) */
 186 +       .byte   0x0
 187 +       .byte   0x0
 188 +
 189 +       .uleb128 0x2    /* (abbrev code) */
 190 +       .uleb128 0x13   /* (TAG: DW_TAG_structure_type) */
 191 +       .byte   0x1     /* DW_children_yes */
 192 +       .uleb128 0x3    /* (DW_AT_name) */
 193 +       .uleb128 0x8    /* (DW_FORM_string) */
 194 +       .uleb128 0xb    /* (DW_AT_byte_size) */
 195 +       .uleb128 0xb    /* (DW_FORM_data1) */
 196 +       .byte   0
 197 +       .byte   0
 198 +
 199 +       .uleb128 0x3    /* (abbrev code) */
 200 +       .uleb128 0xd    /* (TAG: DW_TAG_member) */
 201 +       .byte   0       /* DW_children_no */
 202 +       .uleb128 0x3    /* (DW_AT_name) */
 203 +       .uleb128 0x8    /* (DW_FORM_string) */
 204 +       .uleb128 0x49   /* (DW_AT_type) */
 205 +       .uleb128 0x13   /* (DW_FORM_ref4) */
 206 +       .uleb128 0x38   /* (DW_AT_data_member_location) */
 207 +       .uleb128 0xb    /* (DW_FORM_data1) */
 208 +       .byte   0
 209 +       .byte   0
 210 +
 211 +       .uleb128 0x4    /* (abbrev code) */
 212 +       .uleb128 0x34   /* (TAG: DW_TAG_variable) */
 213 +       .byte   0x0     /* DW_children_yes */
 214 +       .uleb128 0x3    /* (DW_AT_name) */
 215 +       .uleb128 0x8    /* (DW_FORM_string) */
 216 +       .uleb128 0x02   /* (DW_AT_location) */
 217 +       .uleb128 0xa    /* (DW_FORM_block1) */
 218 +       .uleb128 0x49   /* (DW_AT_type) */
 219 +       .uleb128 0x13   /* (DW_FORM_ref4) */
 220 +       .byte   0x0
 221 +       .byte   0x0
 222 +
 223 +       .uleb128 0x5    /* (abbrev code) */
 224 +       .uleb128 0xf    /* (TAG: DW_TAG_pointer_type) */
 225 +       .byte   0x0     /* DW_children_no */
 226 +       .uleb128 0xb    /* (DW_AT_byte_size) */
 227 +       .uleb128 0xb    /* (DW_FORM_data1) */
 228 +       .uleb128 0x49   /* (DW_AT_type) */
 229 +       .uleb128 0x13   /* (DW_FORM_ref4) */
 230 +       .byte   0x0
 231 +       .byte   0x0
 232 +
 233 +       .uleb128        6                       /* Abbrev code */
 234 +       .uleb128        0x2e                    /* DW_TAG_subprogram */
 235 +       .byte           1                       /* has_children */
 236 +       .uleb128        0x3                     /* DW_AT_name */
 237 +       .uleb128        0x8                     /* DW_FORM_string */
 238 +       .uleb128        0x11                    /* DW_AT_low_pc */
 239 +       .uleb128        0x1                     /* DW_FORM_addr */
 240 +       .uleb128        0x12                    /* DW_AT_high_pc */
 241 +       .uleb128        0x1                     /* DW_FORM_addr */
 242 +       .uleb128        0x49                    /* DW_AT_type */
 243 +       .uleb128        0x13                    /* DW_FORM_ref4 */
 244 +       .uleb128        0x3f                    /* DW_AT_external */
 245 +       .uleb128        0xc                     /* DW_FORM_flag */
 246 +       .byte           0x0                     /* Terminator */
 247 +       .byte           0x0                     /* Terminator */
 248 +
 249 +       .uleb128 0x7    /* (abbrev code) */
 250 +       .uleb128 0x24   /* (TAG: DW_TAG_base_type) */
 251 +       .byte   0       /* DW_children_no */
 252 +       .uleb128 0xb    /* (DW_AT_byte_size) */
 253 +       .uleb128 0xb    /* (DW_FORM_data1) */
 254 +       .uleb128 0x3e   /* (DW_AT_encoding) */
 255 +       .uleb128 0xb    /* (DW_FORM_data1) */
 256 +       .uleb128 0x3    /* (DW_AT_name) */
 257 +       .uleb128 0x8    /* (DW_FORM_string) */
 258 +       .byte   0
 259 +       .byte   0
 260 +
 261 +       .byte   0x0
 262 --- /dev/null
 263 +++ b/gdb/testsuite/gdb.dwarf2/implptr-optimized-out.exp
 264 @@ -0,0 +1,37 @@
 265 +# Copyright 2011 Free Software Foundation, Inc.
 266 +
 267 +# This program is free software; you can redistribute it and/or modify
 268 +# it under the terms of the GNU General Public License as published by
 269 +# the Free Software Foundation; either version 3 of the License, or
 270 +# (at your option) any later version.
 271 +#
 272 +# This program is distributed in the hope that it will be useful,
 273 +# but WITHOUT ANY WARRANTY; without even the implied warranty of
 274 +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 275 +# GNU General Public License for more details.
 276 +#
 277 +# You should have received a copy of the GNU General Public License
 278 +# along with this program.  If not, see <http://www.gnu.org/licenses/>.
 279 +load_lib dwarf.exp
 280 +
 281 +# This test can only be run on targets which support DWARF-2 and use gas.
 282 +if {![dwarf2_support]} {
 283 +    return 0
 284 +}
 285 +
 286 +set testfile "implptr-optimized-out"
 287 +set srcfile ${testfile}.S
 288 +set mainfile main.c
 289 +set executable ${testfile}
 290 +set binfile ${objdir}/${subdir}/${executable}
 291 +
 292 +if [prepare_for_testing ${testfile}.exp $executable "${srcfile} ${mainfile}" {}] {
 293 +    return -1
 294 +}
 295 +
 296 +# DW_OP_GNU_implicit_pointer implementation requires a valid frame.
 297 +if ![runto_main] {
 298 +    return -1
 299 +}
 300 +
 301 +gdb_test "p p->f" " = <optimized out>"
 302