gdb/dwarf2expr.c

   1 /* DWARF 2 Expression Evaluator.
   2
   3    Copyright (C) 2001-2017 Free Software Foundation, Inc.
   4
   5    Contributed by Daniel Berlin (dan@dberlin.org)
   6
   7    This file is part of GDB.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  21
  22 #include "defs.h"
  23 #include "symtab.h"
  24 #include "gdbtypes.h"
  25 #include "value.h"
  26 #include "gdbcore.h"
  27 #include "dwarf2.h"
  28 #include "dwarf2expr.h"
  29 #include "dwarf2loc.h"
  30 #include "common/underlying.h"
  31
  32 /* Cookie for gdbarch data.  */
  33
  34 static struct gdbarch_data *dwarf_arch_cookie;
  35
  36 /* This holds gdbarch-specific types used by the DWARF expression
  37    evaluator.  See comments in execute_stack_op.  */
  38
  39 struct dwarf_gdbarch_types
  40 {
  41   struct type *dw_types[3];
  42 };
  43
  44 /* Allocate and fill in dwarf_gdbarch_types for an arch.  */
  45
  46 static void *
  47 dwarf_gdbarch_types_init (struct gdbarch *gdbarch)
  48 {
  49   struct dwarf_gdbarch_types *types
  50     = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct dwarf_gdbarch_types);
  51
  52   /* The types themselves are lazily initialized.  */
  53
  54   return types;
  55 }
  56
  57 /* Return the type used for DWARF operations where the type is
  58    unspecified in the DWARF spec.  Only certain sizes are
  59    supported.  */
  60
  61 struct type *
  62 dwarf_expr_context::address_type () const
  63 {
  64   struct dwarf_gdbarch_types *types
  65     = (struct dwarf_gdbarch_types *) gdbarch_data (this->gdbarch,
  66                                                    dwarf_arch_cookie);
  67   int ndx;
  68
  69   if (this->addr_size == 2)
  70     ndx = 0;
  71   else if (this->addr_size == 4)
  72     ndx = 1;
  73   else if (this->addr_size == 8)
  74     ndx = 2;
  75   else
  76     error (_("Unsupported address size in DWARF expressions: %d bits"),
  77            8 * this->addr_size);
  78
  79   if (types->dw_types[ndx] == NULL)
  80     types->dw_types[ndx]
  81       = arch_integer_type (this->gdbarch,
  82                            8 * this->addr_size,
  83                            0, "<signed DWARF address type>");
  84
  85   return types->dw_types[ndx];
  86 }
  87
  88 /* Create a new context for the expression evaluator.  */
  89
  90 dwarf_expr_context::dwarf_expr_context ()
  91 : gdbarch (NULL),
  92   addr_size (0),
  93   ref_addr_size (0),
  94   offset (0),
  95   recursion_depth (0),
  96   max_recursion_depth (0x100),
  97   location (DWARF_VALUE_MEMORY),
  98   len (0),
  99   data (NULL),
 100   initialized (0)
 101 {
 102 }
 103
 104 /* Push VALUE onto the stack.  */
 105
 106 void
 107 dwarf_expr_context::push (struct value *value, bool in_stack_memory)
 108 {
 109   stack.emplace_back (value, in_stack_memory);
 110 }
 111
 112 /* Push VALUE onto the stack.  */
 113
 114 void
 115 dwarf_expr_context::push_address (CORE_ADDR value, bool in_stack_memory)
 116 {
 117   push (value_from_ulongest (address_type (), value), in_stack_memory);
 118 }
 119
 120 /* Pop the top item off of the stack.  */
 121
 122 void
 123 dwarf_expr_context::pop ()
 124 {
 125   if (stack.empty ())
 126     error (_("dwarf expression stack underflow"));
 127
 128   stack.pop_back ();
 129 }
 130
 131 /* Retrieve the N'th item on the stack.  */
 132
 133 struct value *
 134 dwarf_expr_context::fetch (int n)
 135 {
 136   if (stack.size () <= n)
 137      error (_("Asked for position %d of stack, "
 138               "stack only has %zu elements on it."),
 139             n, stack.size ());
 140   return stack[stack.size () - (1 + n)].value;
 141 }
 142
 143 /* Require that TYPE be an integral type; throw an exception if not.  */
 144
 145 static void
 146 dwarf_require_integral (struct type *type)
 147 {
 148   if (TYPE_CODE (type) != TYPE_CODE_INT
 149       && TYPE_CODE (type) != TYPE_CODE_CHAR
 150       && TYPE_CODE (type) != TYPE_CODE_BOOL)
 151     error (_("integral type expected in DWARF expression"));
 152 }
 153
 154 /* Return the unsigned form of TYPE.  TYPE is necessarily an integral
 155    type.  */
 156
 157 static struct type *
 158 get_unsigned_type (struct gdbarch *gdbarch, struct type *type)
 159 {
 160   switch (TYPE_LENGTH (type))
 161     {
 162     case 1:
 163       return builtin_type (gdbarch)->builtin_uint8;
 164     case 2:
 165       return builtin_type (gdbarch)->builtin_uint16;
 166     case 4:
 167       return builtin_type (gdbarch)->builtin_uint32;
 168     case 8:
 169       return builtin_type (gdbarch)->builtin_uint64;
 170     default:
 171       error (_("no unsigned variant found for type, while evaluating "
 172                "DWARF expression"));
 173     }
 174 }
 175
 176 /* Return the signed form of TYPE.  TYPE is necessarily an integral
 177    type.  */
 178
 179 static struct type *
 180 get_signed_type (struct gdbarch *gdbarch, struct type *type)
 181 {
 182   switch (TYPE_LENGTH (type))
 183     {
 184     case 1:
 185       return builtin_type (gdbarch)->builtin_int8;
 186     case 2:
 187       return builtin_type (gdbarch)->builtin_int16;
 188     case 4:
 189       return builtin_type (gdbarch)->builtin_int32;
 190     case 8:
 191       return builtin_type (gdbarch)->builtin_int64;
 192     default:
 193       error (_("no signed variant found for type, while evaluating "
 194                "DWARF expression"));
 195     }
 196 }
 197
 198 /* Retrieve the N'th item on the stack, converted to an address.  */
 199
 200 CORE_ADDR
 201 dwarf_expr_context::fetch_address (int n)
 202 {
 203   struct value *result_val = fetch (n);
 204   enum bfd_endian byte_order = gdbarch_byte_order (this->gdbarch);
 205   ULONGEST result;
 206
 207   dwarf_require_integral (value_type (result_val));
 208   result = extract_unsigned_integer (value_contents (result_val),
 209                                      TYPE_LENGTH (value_type (result_val)),
 210                                      byte_order);
 211
 212   /* For most architectures, calling extract_unsigned_integer() alone
 213      is sufficient for extracting an address.  However, some
 214      architectures (e.g. MIPS) use signed addresses and using
 215      extract_unsigned_integer() will not produce a correct
 216      result.  Make sure we invoke gdbarch_integer_to_address()
 217      for those architectures which require it.  */
 218   if (gdbarch_integer_to_address_p (this->gdbarch))
 219     {
 220       gdb_byte *buf = (gdb_byte *) alloca (this->addr_size);
 221       struct type *int_type = get_unsigned_type (this->gdbarch,
 222                                                  value_type (result_val));
 223
 224       store_unsigned_integer (buf, this->addr_size, byte_order, result);
 225       return gdbarch_integer_to_address (this->gdbarch, int_type, buf);
 226     }
 227
 228   return (CORE_ADDR) result;
 229 }
 230
 231 /* Retrieve the in_stack_memory flag of the N'th item on the stack.  */
 232
 233 bool
 234 dwarf_expr_context::fetch_in_stack_memory (int n)
 235 {
 236   if (stack.size () <= n)
 237      error (_("Asked for position %d of stack, "
 238               "stack only has %zu elements on it."),
 239             n, stack.size ());
 240   return stack[stack.size () - (1 + n)].in_stack_memory;
 241 }
 242
 243 /* Return true if the expression stack is empty.  */
 244
 245 bool
 246 dwarf_expr_context::stack_empty_p () const
 247 {
 248   return stack.empty ();
 249 }
 250
 251 /* Add a new piece to the dwarf_expr_context's piece list.  */
 252 void
 253 dwarf_expr_context::add_piece (ULONGEST size, ULONGEST offset)
 254 {
 255   this->pieces.emplace_back ();
 256   dwarf_expr_piece &p = this->pieces.back ();
 257
 258   p.location = this->location;
 259   p.size = size;
 260   p.offset = offset;
 261
 262   if (p.location == DWARF_VALUE_LITERAL)
 263     {
 264       p.v.literal.data = this->data;
 265       p.v.literal.length = this->len;
 266     }
 267   else if (stack_empty_p ())
 268     {
 269       p.location = DWARF_VALUE_OPTIMIZED_OUT;
 270       /* Also reset the context's location, for our callers.  This is
 271          a somewhat strange approach, but this lets us avoid setting
 272          the location to DWARF_VALUE_MEMORY in all the individual
 273          cases in the evaluator.  */
 274       this->location = DWARF_VALUE_OPTIMIZED_OUT;
 275     }
 276   else if (p.location == DWARF_VALUE_MEMORY)
 277     {
 278       p.v.mem.addr = fetch_address (0);
 279       p.v.mem.in_stack_memory = fetch_in_stack_memory (0);
 280     }
 281   else if (p.location == DWARF_VALUE_IMPLICIT_POINTER)
 282     {
 283       p.v.ptr.die_sect_off = (sect_offset) this->len;
 284       p.v.ptr.offset = value_as_long (fetch (0));
 285     }
 286   else if (p.location == DWARF_VALUE_REGISTER)
 287     p.v.regno = value_as_long (fetch (0));
 288   else
 289     {
 290       p.v.value = fetch (0);
 291     }
 292 }
 293
 294 /* Evaluate the expression at ADDR (LEN bytes long).  */
 295
 296 void
 297 dwarf_expr_context::eval (const gdb_byte *addr, size_t len)
 298 {
 299   int old_recursion_depth = this->recursion_depth;
 300
 301   execute_stack_op (addr, addr + len);
 302
 303   /* RECURSION_DEPTH becomes invalid if an exception was thrown here.  */
 304
 305   gdb_assert (this->recursion_depth == old_recursion_depth);
 306 }
 307
 308 /* Helper to read a uleb128 value or throw an error.  */
 309
 310 const gdb_byte *
 311 safe_read_uleb128 (const gdb_byte *buf, const gdb_byte *buf_end,
 312                    uint64_t *r)
 313 {
 314   buf = gdb_read_uleb128 (buf, buf_end, r);
 315   if (buf == NULL)
 316     error (_("DWARF expression error: ran off end of buffer reading uleb128 value"));
 317   return buf;
 318 }
 319
 320 /* Helper to read a sleb128 value or throw an error.  */
 321
 322 const gdb_byte *
 323 safe_read_sleb128 (const gdb_byte *buf, const gdb_byte *buf_end,
 324                    int64_t *r)
 325 {
 326   buf = gdb_read_sleb128 (buf, buf_end, r);
 327   if (buf == NULL)
 328     error (_("DWARF expression error: ran off end of buffer reading sleb128 value"));
 329   return buf;
 330 }
 331
 332 const gdb_byte *
 333 safe_skip_leb128 (const gdb_byte *buf, const gdb_byte *buf_end)
 334 {
 335   buf = gdb_skip_leb128 (buf, buf_end);
 336   if (buf == NULL)
 337     error (_("DWARF expression error: ran off end of buffer reading leb128 value"));
 338   return buf;
 339 }
 340 \f
 341
 342 /* Check that the current operator is either at the end of an
 343    expression, or that it is followed by a composition operator or by
 344    DW_OP_GNU_uninit (which should terminate the expression).  */
 345
 346 void
 347 dwarf_expr_require_composition (const gdb_byte *op_ptr, const gdb_byte *op_end,
 348                                 const char *op_name)
 349 {
 350   if (op_ptr != op_end && *op_ptr != DW_OP_piece && *op_ptr != DW_OP_bit_piece
 351       && *op_ptr != DW_OP_GNU_uninit)
 352     error (_("DWARF-2 expression error: `%s' operations must be "
 353              "used either alone or in conjunction with DW_OP_piece "
 354              "or DW_OP_bit_piece."),
 355            op_name);
 356 }
 357
 358 /* Return true iff the types T1 and T2 are "the same".  This only does
 359    checks that might reasonably be needed to compare DWARF base
 360    types.  */
 361
 362 static int
 363 base_types_equal_p (struct type *t1, struct type *t2)
 364 {
 365   if (TYPE_CODE (t1) != TYPE_CODE (t2))
 366     return 0;
 367   if (TYPE_UNSIGNED (t1) != TYPE_UNSIGNED (t2))
 368     return 0;
 369   return TYPE_LENGTH (t1) == TYPE_LENGTH (t2);
 370 }
 371
 372 /* If <BUF..BUF_END] contains DW_FORM_block* with single DW_OP_reg* return the
 373    DWARF register number.  Otherwise return -1.  */
 374
 375 int
 376 dwarf_block_to_dwarf_reg (const gdb_byte *buf, const gdb_byte *buf_end)
 377 {
 378   uint64_t dwarf_reg;
 379
 380   if (buf_end <= buf)
 381     return -1;
 382   if (*buf >= DW_OP_reg0 && *buf <= DW_OP_reg31)
 383     {
 384       if (buf_end - buf != 1)
 385         return -1;
 386       return *buf - DW_OP_reg0;
 387     }
 388
 389   if (*buf == DW_OP_regval_type || *buf == DW_OP_GNU_regval_type)
 390     {
 391       buf++;
 392       buf = gdb_read_uleb128 (buf, buf_end, &dwarf_reg);
 393       if (buf == NULL)
 394         return -1;
 395       buf = gdb_skip_leb128 (buf, buf_end);
 396       if (buf == NULL)
 397         return -1;
 398     }
 399   else if (*buf == DW_OP_regx)
 400     {
 401       buf++;
 402       buf = gdb_read_uleb128 (buf, buf_end, &dwarf_reg);
 403       if (buf == NULL)
 404         return -1;
 405     }
 406   else
 407     return -1;
 408   if (buf != buf_end || (int) dwarf_reg != dwarf_reg)
 409     return -1;
 410   return dwarf_reg;
 411 }
 412
 413 /* If <BUF..BUF_END] contains DW_FORM_block* with just DW_OP_breg*(0) and
 414    DW_OP_deref* return the DWARF register number.  Otherwise return -1.
 415    DEREF_SIZE_RETURN contains -1 for DW_OP_deref; otherwise it contains the
 416    size from DW_OP_deref_size.  */
 417
 418 int
 419 dwarf_block_to_dwarf_reg_deref (const gdb_byte *buf, const gdb_byte *buf_end,
 420                                 CORE_ADDR *deref_size_return)
 421 {
 422   uint64_t dwarf_reg;
 423   int64_t offset;
 424
 425   if (buf_end <= buf)
 426     return -1;
 427
 428   if (*buf >= DW_OP_breg0 && *buf <= DW_OP_breg31)
 429     {
 430       dwarf_reg = *buf - DW_OP_breg0;
 431       buf++;
 432       if (buf >= buf_end)
 433         return -1;
 434     }
 435   else if (*buf == DW_OP_bregx)
 436     {
 437       buf++;
 438       buf = gdb_read_uleb128 (buf, buf_end, &dwarf_reg);
 439       if (buf == NULL)
 440         return -1;
 441       if ((int) dwarf_reg != dwarf_reg)
 442        return -1;
 443     }
 444   else
 445     return -1;
 446
 447   buf = gdb_read_sleb128 (buf, buf_end, &offset);
 448   if (buf == NULL)
 449     return -1;
 450   if (offset != 0)
 451     return -1;
 452
 453   if (*buf == DW_OP_deref)
 454     {
 455       buf++;
 456       *deref_size_return = -1;
 457     }
 458   else if (*buf == DW_OP_deref_size)
 459     {
 460       buf++;
 461       if (buf >= buf_end)
 462        return -1;
 463       *deref_size_return = *buf++;
 464     }
 465   else
 466     return -1;
 467
 468   if (buf != buf_end)
 469     return -1;
 470
 471   return dwarf_reg;
 472 }
 473
 474 /* If <BUF..BUF_END] contains DW_FORM_block* with single DW_OP_fbreg(X) fill
 475    in FB_OFFSET_RETURN with the X offset and return 1.  Otherwise return 0.  */
 476
 477 int
 478 dwarf_block_to_fb_offset (const gdb_byte *buf, const gdb_byte *buf_end,
 479                           CORE_ADDR *fb_offset_return)
 480 {
 481   int64_t fb_offset;
 482
 483   if (buf_end <= buf)
 484     return 0;
 485
 486   if (*buf != DW_OP_fbreg)
 487     return 0;
 488   buf++;
 489
 490   buf = gdb_read_sleb128 (buf, buf_end, &fb_offset);
 491   if (buf == NULL)
 492     return 0;
 493   *fb_offset_return = fb_offset;
 494   if (buf != buf_end || fb_offset != (LONGEST) *fb_offset_return)
 495     return 0;
 496
 497   return 1;
 498 }
 499
 500 /* If <BUF..BUF_END] contains DW_FORM_block* with single DW_OP_bregSP(X) fill
 501    in SP_OFFSET_RETURN with the X offset and return 1.  Otherwise return 0.
 502    The matched SP register number depends on GDBARCH.  */
 503
 504 int
 505 dwarf_block_to_sp_offset (struct gdbarch *gdbarch, const gdb_byte *buf,
 506                           const gdb_byte *buf_end, CORE_ADDR *sp_offset_return)
 507 {
 508   uint64_t dwarf_reg;
 509   int64_t sp_offset;
 510
 511   if (buf_end <= buf)
 512     return 0;
 513   if (*buf >= DW_OP_breg0 && *buf <= DW_OP_breg31)
 514     {
 515       dwarf_reg = *buf - DW_OP_breg0;
 516       buf++;
 517     }
 518   else
 519     {
 520       if (*buf != DW_OP_bregx)
 521        return 0;
 522       buf++;
 523       buf = gdb_read_uleb128 (buf, buf_end, &dwarf_reg);
 524       if (buf == NULL)
 525         return 0;
 526     }
 527
 528   if (dwarf_reg_to_regnum (gdbarch, dwarf_reg)
 529       != gdbarch_sp_regnum (gdbarch))
 530     return 0;
 531
 532   buf = gdb_read_sleb128 (buf, buf_end, &sp_offset);
 533   if (buf == NULL)
 534     return 0;
 535   *sp_offset_return = sp_offset;
 536   if (buf != buf_end || sp_offset != (LONGEST) *sp_offset_return)
 537     return 0;
 538
 539   return 1;
 540 }
 541
 542 /* The engine for the expression evaluator.  Using the context in this
 543    object, evaluate the expression between OP_PTR and OP_END.  */
 544
 545 void
 546 dwarf_expr_context::execute_stack_op (const gdb_byte *op_ptr,
 547                                       const gdb_byte *op_end)
 548 {
 549   enum bfd_endian byte_order = gdbarch_byte_order (this->gdbarch);
 550   /* Old-style "untyped" DWARF values need special treatment in a
 551      couple of places, specifically DW_OP_mod and DW_OP_shr.  We need
 552      a special type for these values so we can distinguish them from
 553      values that have an explicit type, because explicitly-typed
 554      values do not need special treatment.  This special type must be
 555      different (in the `==' sense) from any base type coming from the
 556      CU.  */
 557   struct type *address_type = this->address_type ();
 558
 559   this->location = DWARF_VALUE_MEMORY;
 560   this->initialized = 1;  /* Default is initialized.  */
 561
 562   if (this->recursion_depth > this->max_recursion_depth)
 563     error (_("DWARF-2 expression error: Loop detected (%d)."),
 564            this->recursion_depth);
 565   this->recursion_depth++;
 566
 567   while (op_ptr < op_end)
 568     {
 569       enum dwarf_location_atom op = (enum dwarf_location_atom) *op_ptr++;
 570       ULONGEST result;
 571       /* Assume the value is not in stack memory.
 572          Code that knows otherwise sets this to true.
 573          Some arithmetic on stack addresses can probably be assumed to still
 574          be a stack address, but we skip this complication for now.
 575          This is just an optimization, so it's always ok to punt
 576          and leave this as false.  */
 577       bool in_stack_memory = false;
 578       uint64_t uoffset, reg;
 579       int64_t offset;
 580       struct value *result_val = NULL;
 581
 582       /* The DWARF expression might have a bug causing an infinite
 583          loop.  In that case, quitting is the only way out.  */
 584       QUIT;
 585
 586       switch (op)
 587         {
 588         case DW_OP_lit0:
 589         case DW_OP_lit1:
 590         case DW_OP_lit2:
 591         case DW_OP_lit3:
 592         case DW_OP_lit4:
 593         case DW_OP_lit5:
 594         case DW_OP_lit6:
 595         case DW_OP_lit7:
 596         case DW_OP_lit8:
 597         case DW_OP_lit9:
 598         case DW_OP_lit10:
 599         case DW_OP_lit11:
 600         case DW_OP_lit12:
 601         case DW_OP_lit13:
 602         case DW_OP_lit14:
 603         case DW_OP_lit15:
 604         case DW_OP_lit16:
 605         case DW_OP_lit17:
 606         case DW_OP_lit18:
 607         case DW_OP_lit19:
 608         case DW_OP_lit20:
 609         case DW_OP_lit21:
 610         case DW_OP_lit22:
 611         case DW_OP_lit23:
 612         case DW_OP_lit24:
 613         case DW_OP_lit25:
 614         case DW_OP_lit26:
 615         case DW_OP_lit27:
 616         case DW_OP_lit28:
 617         case DW_OP_lit29:
 618         case DW_OP_lit30:
 619         case DW_OP_lit31:
 620           result = op - DW_OP_lit0;
 621           result_val = value_from_ulongest (address_type, result);
 622           break;
 623
 624         case DW_OP_addr:
 625           result = extract_unsigned_integer (op_ptr,
 626                                              this->addr_size, byte_order);
 627           op_ptr += this->addr_size;
 628           /* Some versions of GCC emit DW_OP_addr before
 629              DW_OP_GNU_push_tls_address.  In this case the value is an
 630              index, not an address.  We don't support things like
 631              branching between the address and the TLS op.  */
 632           if (op_ptr >= op_end || *op_ptr != DW_OP_GNU_push_tls_address)
 633             result += this->offset;
 634           result_val = value_from_ulongest (address_type, result);
 635           break;
 636
 637         case DW_OP_GNU_addr_index:
 638           op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
 639           result = this->get_addr_index (uoffset);
 640           result += this->offset;
 641           result_val = value_from_ulongest (address_type, result);
 642           break;
 643         case DW_OP_GNU_const_index:
 644           op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
 645           result = this->get_addr_index (uoffset);
 646           result_val = value_from_ulongest (address_type, result);
 647           break;
 648
 649         case DW_OP_const1u:
 650           result = extract_unsigned_integer (op_ptr, 1, byte_order);
 651           result_val = value_from_ulongest (address_type, result);
 652           op_ptr += 1;
 653           break;
 654         case DW_OP_const1s:
 655           result = extract_signed_integer (op_ptr, 1, byte_order);
 656           result_val = value_from_ulongest (address_type, result);
 657           op_ptr += 1;
 658           break;
 659         case DW_OP_const2u:
 660           result = extract_unsigned_integer (op_ptr, 2, byte_order);
 661           result_val = value_from_ulongest (address_type, result);
 662           op_ptr += 2;
 663           break;
 664         case DW_OP_const2s:
 665           result = extract_signed_integer (op_ptr, 2, byte_order);
 666           result_val = value_from_ulongest (address_type, result);
 667           op_ptr += 2;
 668           break;
 669         case DW_OP_const4u:
 670           result = extract_unsigned_integer (op_ptr, 4, byte_order);
 671           result_val = value_from_ulongest (address_type, result);
 672           op_ptr += 4;
 673           break;
 674         case DW_OP_const4s:
 675           result = extract_signed_integer (op_ptr, 4, byte_order);
 676           result_val = value_from_ulongest (address_type, result);
 677           op_ptr += 4;
 678           break;
 679         case DW_OP_const8u:
 680           result = extract_unsigned_integer (op_ptr, 8, byte_order);
 681           result_val = value_from_ulongest (address_type, result);
 682           op_ptr += 8;
 683           break;
 684         case DW_OP_const8s:
 685           result = extract_signed_integer (op_ptr, 8, byte_order);
 686           result_val = value_from_ulongest (address_type, result);
 687           op_ptr += 8;
 688           break;
 689         case DW_OP_constu:
 690           op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
 691           result = uoffset;
 692           result_val = value_from_ulongest (address_type, result);
 693           break;
 694         case DW_OP_consts:
 695           op_ptr = safe_read_sleb128 (op_ptr, op_end, &offset);
 696           result = offset;
 697           result_val = value_from_ulongest (address_type, result);
 698           break;
 699
 700         /* The DW_OP_reg operations are required to occur alone in
 701            location expressions.  */
 702         case DW_OP_reg0:
 703         case DW_OP_reg1:
 704         case DW_OP_reg2:
 705         case DW_OP_reg3:
 706         case DW_OP_reg4:
 707         case DW_OP_reg5:
 708         case DW_OP_reg6:
 709         case DW_OP_reg7:
 710         case DW_OP_reg8:
 711         case DW_OP_reg9:
 712         case DW_OP_reg10:
 713         case DW_OP_reg11:
 714         case DW_OP_reg12:
 715         case DW_OP_reg13:
 716         case DW_OP_reg14:
 717         case DW_OP_reg15:
 718         case DW_OP_reg16:
 719         case DW_OP_reg17:
 720         case DW_OP_reg18:
 721         case DW_OP_reg19:
 722         case DW_OP_reg20:
 723         case DW_OP_reg21:
 724         case DW_OP_reg22:
 725         case DW_OP_reg23:
 726         case DW_OP_reg24:
 727         case DW_OP_reg25:
 728         case DW_OP_reg26:
 729         case DW_OP_reg27:
 730         case DW_OP_reg28:
 731         case DW_OP_reg29:
 732         case DW_OP_reg30:
 733         case DW_OP_reg31:
 734           dwarf_expr_require_composition (op_ptr, op_end, "DW_OP_reg");
 735
 736           result = op - DW_OP_reg0;
 737           result_val = value_from_ulongest (address_type, result);
 738           this->location = DWARF_VALUE_REGISTER;
 739           break;
 740
 741         case DW_OP_regx:
 742           op_ptr = safe_read_uleb128 (op_ptr, op_end, &reg);
 743           dwarf_expr_require_composition (op_ptr, op_end, "DW_OP_regx");
 744
 745           result = reg;
 746           result_val = value_from_ulongest (address_type, result);
 747           this->location = DWARF_VALUE_REGISTER;
 748           break;
 749
 750         case DW_OP_implicit_value:
 751           {
 752             uint64_t len;
 753
 754             op_ptr = safe_read_uleb128 (op_ptr, op_end, &len);
 755             if (op_ptr + len > op_end)
 756               error (_("DW_OP_implicit_value: too few bytes available."));
 757             this->len = len;
 758             this->data = op_ptr;
 759             this->location = DWARF_VALUE_LITERAL;
 760             op_ptr += len;
 761             dwarf_expr_require_composition (op_ptr, op_end,
 762                                             "DW_OP_implicit_value");
 763           }
 764           goto no_push;
 765
 766         case DW_OP_stack_value:
 767           this->location = DWARF_VALUE_STACK;
 768           dwarf_expr_require_composition (op_ptr, op_end, "DW_OP_stack_value");
 769           goto no_push;
 770
 771         case DW_OP_implicit_pointer:
 772         case DW_OP_GNU_implicit_pointer:
 773           {
 774             int64_t len;
 775
 776             if (this->ref_addr_size == -1)
 777               error (_("DWARF-2 expression error: DW_OP_implicit_pointer "
 778                        "is not allowed in frame context"));
 779
 780             /* The referred-to DIE of sect_offset kind.  */
 781             this->len = extract_unsigned_integer (op_ptr, this->ref_addr_size,
 782                                                  byte_order);
 783             op_ptr += this->ref_addr_size;
 784
 785             /* The byte offset into the data.  */
 786             op_ptr = safe_read_sleb128 (op_ptr, op_end, &len);
 787             result = (ULONGEST) len;
 788             result_val = value_from_ulongest (address_type, result);
 789
 790             this->location = DWARF_VALUE_IMPLICIT_POINTER;
 791             dwarf_expr_require_composition (op_ptr, op_end,
 792                                             "DW_OP_implicit_pointer");
 793           }
 794           break;
 795
 796         case DW_OP_breg0:
 797         case DW_OP_breg1:
 798         case DW_OP_breg2:
 799         case DW_OP_breg3:
 800         case DW_OP_breg4:
 801         case DW_OP_breg5:
 802         case DW_OP_breg6:
 803         case DW_OP_breg7:
 804         case DW_OP_breg8:
 805         case DW_OP_breg9:
 806         case DW_OP_breg10:
 807         case DW_OP_breg11:
 808         case DW_OP_breg12:
 809         case DW_OP_breg13:
 810         case DW_OP_breg14:
 811         case DW_OP_breg15:
 812         case DW_OP_breg16:
 813         case DW_OP_breg17:
 814         case DW_OP_breg18:
 815         case DW_OP_breg19:
 816         case DW_OP_breg20:
 817         case DW_OP_breg21:
 818         case DW_OP_breg22:
 819         case DW_OP_breg23:
 820         case DW_OP_breg24:
 821         case DW_OP_breg25:
 822         case DW_OP_breg26:
 823         case DW_OP_breg27:
 824         case DW_OP_breg28:
 825         case DW_OP_breg29:
 826         case DW_OP_breg30:
 827         case DW_OP_breg31:
 828           {
 829             op_ptr = safe_read_sleb128 (op_ptr, op_end, &offset);
 830             result = this->read_addr_from_reg (op - DW_OP_breg0);
 831             result += offset;
 832             result_val = value_from_ulongest (address_type, result);
 833           }
 834           break;
 835         case DW_OP_bregx:
 836           {
 837             op_ptr = safe_read_uleb128 (op_ptr, op_end, &reg);
 838             op_ptr = safe_read_sleb128 (op_ptr, op_end, &offset);
 839             result = this->read_addr_from_reg (reg);
 840             result += offset;
 841             result_val = value_from_ulongest (address_type, result);
 842           }
 843           break;
 844         case DW_OP_fbreg:
 845           {
 846             const gdb_byte *datastart;
 847             size_t datalen;
 848
 849             op_ptr = safe_read_sleb128 (op_ptr, op_end, &offset);
 850
 851             /* Rather than create a whole new context, we simply
 852                backup the current stack locally and install a new empty stack,
 853                then reset it afterwards, effectively erasing whatever the
 854                recursive call put there.  */
 855             std::vector<dwarf_stack_value> saved_stack = std::move (stack);
 856             stack.clear ();
 857
 858             /* FIXME: cagney/2003-03-26: This code should be using
 859                get_frame_base_address(), and then implement a dwarf2
 860                specific this_base method.  */
 861             this->get_frame_base (&datastart, &datalen);
 862             eval (datastart, datalen);
 863             if (this->location == DWARF_VALUE_MEMORY)
 864               result = fetch_address (0);
 865             else if (this->location == DWARF_VALUE_REGISTER)
 866               result = this->read_addr_from_reg (value_as_long (fetch (0)));
 867             else
 868               error (_("Not implemented: computing frame "
 869                        "base using explicit value operator"));
 870             result = result + offset;
 871             result_val = value_from_ulongest (address_type, result);
 872             in_stack_memory = true;
 873
 874             /* Restore the content of the original stack.  */
 875             stack = std::move (saved_stack);
 876
 877             this->location = DWARF_VALUE_MEMORY;
 878           }
 879           break;
 880
 881         case DW_OP_dup:
 882           result_val = fetch (0);
 883           in_stack_memory = fetch_in_stack_memory (0);
 884           break;
 885
 886         case DW_OP_drop:
 887           pop ();
 888           goto no_push;
 889
 890         case DW_OP_pick:
 891           offset = *op_ptr++;
 892           result_val = fetch (offset);
 893           in_stack_memory = fetch_in_stack_memory (offset);
 894           break;
 895
 896         case DW_OP_swap:
 897           {
 898             if (stack.size () < 2)
 899                error (_("Not enough elements for "
 900                         "DW_OP_swap.  Need 2, have %zu."),
 901                       stack.size ());
 902
 903             dwarf_stack_value &t1 = stack[stack.size () - 1];
 904             dwarf_stack_value &t2 = stack[stack.size () - 2];
 905             std::swap (t1, t2);
 906             goto no_push;
 907           }
 908
 909         case DW_OP_over:
 910           result_val = fetch (1);
 911           in_stack_memory = fetch_in_stack_memory (1);
 912           break;
 913
 914         case DW_OP_rot:
 915           {
 916             if (stack.size () < 3)
 917                error (_("Not enough elements for "
 918                         "DW_OP_rot.  Need 3, have %zu."),
 919                       stack.size ());
 920
 921             dwarf_stack_value temp = stack[stack.size () - 1];
 922             stack[stack.size () - 1] = stack[stack.size () - 2];
 923             stack[stack.size () - 2] = stack[stack.size () - 3];
 924             stack[stack.size () - 3] = temp;
 925             goto no_push;
 926           }
 927
 928         case DW_OP_deref:
 929         case DW_OP_deref_size:
 930         case DW_OP_deref_type:
 931         case DW_OP_GNU_deref_type:
 932           {
 933             int addr_size = (op == DW_OP_deref ? this->addr_size : *op_ptr++);
 934             gdb_byte *buf = (gdb_byte *) alloca (addr_size);
 935             CORE_ADDR addr = fetch_address (0);
 936             struct type *type;
 937
 938             pop ();
 939
 940             if (op == DW_OP_deref_type || op == DW_OP_GNU_deref_type)
 941               {
 942                 op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
 943                 cu_offset type_die_cu_off = (cu_offset) uoffset;
 944                 type = get_base_type (type_die_cu_off, 0);
 945               }
 946             else
 947               type = address_type;
 948
 949             this->read_mem (buf, addr, addr_size);
 950
 951             /* If the size of the object read from memory is different
 952                from the type length, we need to zero-extend it.  */
 953             if (TYPE_LENGTH (type) != addr_size)
 954               {
 955                 ULONGEST result =
 956                   extract_unsigned_integer (buf, addr_size, byte_order);
 957
 958                 buf = (gdb_byte *) alloca (TYPE_LENGTH (type));
 959                 store_unsigned_integer (buf, TYPE_LENGTH (type),
 960                                         byte_order, result);
 961               }
 962
 963             result_val = value_from_contents_and_address (type, buf, addr);
 964             break;
 965           }
 966
 967         case DW_OP_abs:
 968         case DW_OP_neg:
 969         case DW_OP_not:
 970         case DW_OP_plus_uconst:
 971           {
 972             /* Unary operations.  */
 973             result_val = fetch (0);
 974             pop ();
 975
 976             switch (op)
 977               {
 978               case DW_OP_abs:
 979                 if (value_less (result_val,
 980                                 value_zero (value_type (result_val), not_lval)))
 981                   result_val = value_neg (result_val);
 982                 break;
 983               case DW_OP_neg:
 984                 result_val = value_neg (result_val);
 985                 break;
 986               case DW_OP_not:
 987                 dwarf_require_integral (value_type (result_val));
 988                 result_val = value_complement (result_val);
 989                 break;
 990               case DW_OP_plus_uconst:
 991                 dwarf_require_integral (value_type (result_val));
 992                 result = value_as_long (result_val);
 993                 op_ptr = safe_read_uleb128 (op_ptr, op_end, &reg);
 994                 result += reg;
 995                 result_val = value_from_ulongest (address_type, result);
 996                 break;
 997               }
 998           }
 999           break;
1000
1001         case DW_OP_and:
1002         case DW_OP_div:
1003         case DW_OP_minus:
1004         case DW_OP_mod:
1005         case DW_OP_mul:
1006         case DW_OP_or:
1007         case DW_OP_plus:
1008         case DW_OP_shl:
1009         case DW_OP_shr:
1010         case DW_OP_shra:
1011         case DW_OP_xor:
1012         case DW_OP_le:
1013         case DW_OP_ge:
1014         case DW_OP_eq:
1015         case DW_OP_lt:
1016         case DW_OP_gt:
1017         case DW_OP_ne:
1018           {
1019             /* Binary operations.  */
1020             struct value *first, *second;
1021
1022             second = fetch (0);
1023             pop ();
1024
1025             first = fetch (0);
1026             pop ();
1027
1028             if (! base_types_equal_p (value_type (first), value_type (second)))
1029               error (_("Incompatible types on DWARF stack"));
1030
1031             switch (op)
1032               {
1033               case DW_OP_and:
1034                 dwarf_require_integral (value_type (first));
1035                 dwarf_require_integral (value_type (second));
1036                 result_val = value_binop (first, second, BINOP_BITWISE_AND);
1037                 break;
1038               case DW_OP_div:
1039                 result_val = value_binop (first, second, BINOP_DIV);
1040                 break;
1041               case DW_OP_minus:
1042                 result_val = value_binop (first, second, BINOP_SUB);
1043                 break;
1044               case DW_OP_mod:
1045                 {
1046                   int cast_back = 0;
1047                   struct type *orig_type = value_type (first);
1048
1049                   /* We have to special-case "old-style" untyped values
1050                      -- these must have mod computed using unsigned
1051                      math.  */
1052                   if (orig_type == address_type)
1053                     {
1054                       struct type *utype
1055                         = get_unsigned_type (this->gdbarch, orig_type);
1056
1057                       cast_back = 1;
1058                       first = value_cast (utype, first);
1059                       second = value_cast (utype, second);
1060                     }
1061                   /* Note that value_binop doesn't handle float or
1062                      decimal float here.  This seems unimportant.  */
1063                   result_val = value_binop (first, second, BINOP_MOD);
1064                   if (cast_back)
1065                     result_val = value_cast (orig_type, result_val);
1066                 }
1067                 break;
1068               case DW_OP_mul:
1069                 result_val = value_binop (first, second, BINOP_MUL);
1070                 break;
1071               case DW_OP_or:
1072                 dwarf_require_integral (value_type (first));
1073                 dwarf_require_integral (value_type (second));
1074                 result_val = value_binop (first, second, BINOP_BITWISE_IOR);
1075                 break;
1076               case DW_OP_plus:
1077                 result_val = value_binop (first, second, BINOP_ADD);
1078                 break;
1079               case DW_OP_shl:
1080                 dwarf_require_integral (value_type (first));
1081                 dwarf_require_integral (value_type (second));
1082                 result_val = value_binop (first, second, BINOP_LSH);
1083                 break;
1084               case DW_OP_shr:
1085                 dwarf_require_integral (value_type (first));
1086                 dwarf_require_integral (value_type (second));
1087                 if (!TYPE_UNSIGNED (value_type (first)))
1088                   {
1089                     struct type *utype
1090                       = get_unsigned_type (this->gdbarch, value_type (first));
1091
1092                     first = value_cast (utype, first);
1093                   }
1094
1095                 result_val = value_binop (first, second, BINOP_RSH);
1096                 /* Make sure we wind up with the same type we started
1097                    with.  */
1098                 if (value_type (result_val) != value_type (second))
1099                   result_val = value_cast (value_type (second), result_val);
1100                 break;
1101               case DW_OP_shra:
1102                 dwarf_require_integral (value_type (first));
1103                 dwarf_require_integral (value_type (second));
1104                 if (TYPE_UNSIGNED (value_type (first)))
1105                   {
1106                     struct type *stype
1107                       = get_signed_type (this->gdbarch, value_type (first));
1108
1109                     first = value_cast (stype, first);
1110                   }
1111
1112                 result_val = value_binop (first, second, BINOP_RSH);
1113                 /* Make sure we wind up with the same type we started
1114                    with.  */
1115                 if (value_type (result_val) != value_type (second))
1116                   result_val = value_cast (value_type (second), result_val);
1117                 break;
1118               case DW_OP_xor:
1119                 dwarf_require_integral (value_type (first));
1120                 dwarf_require_integral (value_type (second));
1121                 result_val = value_binop (first, second, BINOP_BITWISE_XOR);
1122                 break;
1123               case DW_OP_le:
1124                 /* A <= B is !(B < A).  */
1125                 result = ! value_less (second, first);
1126                 result_val = value_from_ulongest (address_type, result);
1127                 break;
1128               case DW_OP_ge:
1129                 /* A >= B is !(A < B).  */
1130                 result = ! value_less (first, second);
1131                 result_val = value_from_ulongest (address_type, result);
1132                 break;
1133               case DW_OP_eq:
1134                 result = value_equal (first, second);
1135                 result_val = value_from_ulongest (address_type, result);
1136                 break;
1137               case DW_OP_lt:
1138                 result = value_less (first, second);
1139                 result_val = value_from_ulongest (address_type, result);
1140                 break;
1141               case DW_OP_gt:
1142                 /* A > B is B < A.  */
1143                 result = value_less (second, first);
1144                 result_val = value_from_ulongest (address_type, result);
1145                 break;
1146               case DW_OP_ne:
1147                 result = ! value_equal (first, second);
1148                 result_val = value_from_ulongest (address_type, result);
1149                 break;
1150               default:
1151                 internal_error (__FILE__, __LINE__,
1152                                 _("Can't be reached."));
1153               }
1154           }
1155           break;
1156
1157         case DW_OP_call_frame_cfa:
1158           result = this->get_frame_cfa ();
1159           result_val = value_from_ulongest (address_type, result);
1160           in_stack_memory = true;
1161           break;
1162
1163         case DW_OP_GNU_push_tls_address:
1164         case DW_OP_form_tls_address:
1165           /* Variable is at a constant offset in the thread-local
1166           storage block into the objfile for the current thread and
1167           the dynamic linker module containing this expression.  Here
1168           we return returns the offset from that base.  The top of the
1169           stack has the offset from the beginning of the thread
1170           control block at which the variable is located.  Nothing
1171           should follow this operator, so the top of stack would be
1172           returned.  */
1173           result = value_as_long (fetch (0));
1174           pop ();
1175           result = this->get_tls_address (result);
1176           result_val = value_from_ulongest (address_type, result);
1177           break;
1178
1179         case DW_OP_skip:
1180           offset = extract_signed_integer (op_ptr, 2, byte_order);
1181           op_ptr += 2;
1182           op_ptr += offset;
1183           goto no_push;
1184
1185         case DW_OP_bra:
1186           {
1187             struct value *val;
1188
1189             offset = extract_signed_integer (op_ptr, 2, byte_order);
1190             op_ptr += 2;
1191             val = fetch (0);
1192             dwarf_require_integral (value_type (val));
1193             if (value_as_long (val) != 0)
1194               op_ptr += offset;
1195             pop ();
1196           }
1197           goto no_push;
1198
1199         case DW_OP_nop:
1200           goto no_push;
1201
1202         case DW_OP_piece:
1203           {
1204             uint64_t size;
1205
1206             /* Record the piece.  */
1207             op_ptr = safe_read_uleb128 (op_ptr, op_end, &size);
1208             add_piece (8 * size, 0);
1209
1210             /* Pop off the address/regnum, and reset the location
1211                type.  */
1212             if (this->location != DWARF_VALUE_LITERAL
1213                 && this->location != DWARF_VALUE_OPTIMIZED_OUT)
1214               pop ();
1215             this->location = DWARF_VALUE_MEMORY;
1216           }
1217           goto no_push;
1218
1219         case DW_OP_bit_piece:
1220           {
1221             uint64_t size, offset;
1222
1223             /* Record the piece.  */
1224             op_ptr = safe_read_uleb128 (op_ptr, op_end, &size);
1225             op_ptr = safe_read_uleb128 (op_ptr, op_end, &offset);
1226             add_piece (size, offset);
1227
1228             /* Pop off the address/regnum, and reset the location
1229                type.  */
1230             if (this->location != DWARF_VALUE_LITERAL
1231                 && this->location != DWARF_VALUE_OPTIMIZED_OUT)
1232               pop ();
1233             this->location = DWARF_VALUE_MEMORY;
1234           }
1235           goto no_push;
1236
1237         case DW_OP_GNU_uninit:
1238           if (op_ptr != op_end)
1239             error (_("DWARF-2 expression error: DW_OP_GNU_uninit must always "
1240                    "be the very last op."));
1241
1242           this->initialized = 0;
1243           goto no_push;
1244
1245         case DW_OP_call2:
1246           {
1247             cu_offset cu_off
1248               = (cu_offset) extract_unsigned_integer (op_ptr, 2, byte_order);
1249             op_ptr += 2;
1250             this->dwarf_call (cu_off);
1251           }
1252           goto no_push;
1253
1254         case DW_OP_call4:
1255           {
1256             cu_offset cu_off
1257               = (cu_offset) extract_unsigned_integer (op_ptr, 4, byte_order);
1258             op_ptr += 4;
1259             this->dwarf_call (cu_off);
1260           }
1261           goto no_push;
1262
1263         case DW_OP_entry_value:
1264         case DW_OP_GNU_entry_value:
1265           {
1266             uint64_t len;
1267             CORE_ADDR deref_size;
1268             union call_site_parameter_u kind_u;
1269
1270             op_ptr = safe_read_uleb128 (op_ptr, op_end, &len);
1271             if (op_ptr + len > op_end)
1272               error (_("DW_OP_entry_value: too few bytes available."));
1273
1274             kind_u.dwarf_reg = dwarf_block_to_dwarf_reg (op_ptr, op_ptr + len);
1275             if (kind_u.dwarf_reg != -1)
1276               {
1277                 op_ptr += len;
1278                 this->push_dwarf_reg_entry_value (CALL_SITE_PARAMETER_DWARF_REG,
1279                                                   kind_u,
1280                                                   -1 /* deref_size */);
1281                 goto no_push;
1282               }
1283
1284             kind_u.dwarf_reg = dwarf_block_to_dwarf_reg_deref (op_ptr,
1285                                                                op_ptr + len,
1286                                                                &deref_size);
1287             if (kind_u.dwarf_reg != -1)
1288               {
1289                 if (deref_size == -1)
1290                   deref_size = this->addr_size;
1291                 op_ptr += len;
1292                 this->push_dwarf_reg_entry_value (CALL_SITE_PARAMETER_DWARF_REG,
1293                                                   kind_u, deref_size);
1294                 goto no_push;
1295               }
1296
1297             error (_("DWARF-2 expression error: DW_OP_entry_value is "
1298                      "supported only for single DW_OP_reg* "
1299                      "or for DW_OP_breg*(0)+DW_OP_deref*"));
1300           }
1301
1302         case DW_OP_GNU_parameter_ref:
1303           {
1304             union call_site_parameter_u kind_u;
1305
1306             kind_u.param_cu_off
1307               = (cu_offset) extract_unsigned_integer (op_ptr, 4, byte_order);
1308             op_ptr += 4;
1309             this->push_dwarf_reg_entry_value (CALL_SITE_PARAMETER_PARAM_OFFSET,
1310                                               kind_u,
1311                                               -1 /* deref_size */);
1312           }
1313           goto no_push;
1314
1315         case DW_OP_const_type:
1316         case DW_OP_GNU_const_type:
1317           {
1318             int n;
1319             const gdb_byte *data;
1320             struct type *type;
1321
1322             op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
1323             cu_offset type_die_cu_off = (cu_offset) uoffset;
1324
1325             n = *op_ptr++;
1326             data = op_ptr;
1327             op_ptr += n;
1328
1329             type = get_base_type (type_die_cu_off, n);
1330             result_val = value_from_contents (type, data);
1331           }
1332           break;
1333
1334         case DW_OP_regval_type:
1335         case DW_OP_GNU_regval_type:
1336           {
1337             struct type *type;
1338
1339             op_ptr = safe_read_uleb128 (op_ptr, op_end, &reg);
1340             op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
1341             cu_offset type_die_cu_off = (cu_offset) uoffset;
1342
1343             type = get_base_type (type_die_cu_off, 0);
1344             result_val = this->get_reg_value (type, reg);
1345           }
1346           break;
1347
1348         case DW_OP_convert:
1349         case DW_OP_GNU_convert:
1350         case DW_OP_reinterpret:
1351         case DW_OP_GNU_reinterpret:
1352           {
1353             struct type *type;
1354
1355             op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
1356             cu_offset type_die_cu_off = (cu_offset) uoffset;
1357
1358             if (to_underlying (type_die_cu_off) == 0)
1359               type = address_type;
1360             else
1361               type = get_base_type (type_die_cu_off, 0);
1362
1363             result_val = fetch (0);
1364             pop ();
1365
1366             if (op == DW_OP_convert || op == DW_OP_GNU_convert)
1367               result_val = value_cast (type, result_val);
1368             else if (type == value_type (result_val))
1369               {
1370                 /* Nothing.  */
1371               }
1372             else if (TYPE_LENGTH (type)
1373                      != TYPE_LENGTH (value_type (result_val)))
1374               error (_("DW_OP_reinterpret has wrong size"));
1375             else
1376               result_val
1377                 = value_from_contents (type,
1378                                        value_contents_all (result_val));
1379           }
1380           break;
1381
1382         case DW_OP_push_object_address:
1383           /* Return the address of the object we are currently observing.  */
1384           result = this->get_object_address ();
1385           result_val = value_from_ulongest (address_type, result);
1386           break;
1387
1388         default:
1389           error (_("Unhandled dwarf expression opcode 0x%x"), op);
1390         }
1391
1392       /* Most things push a result value.  */
1393       gdb_assert (result_val != NULL);
1394       push (result_val, in_stack_memory);
1395     no_push:
1396       ;
1397     }
1398
1399   /* To simplify our main caller, if the result is an implicit
1400      pointer, then make a pieced value.  This is ok because we can't
1401      have implicit pointers in contexts where pieces are invalid.  */
1402   if (this->location == DWARF_VALUE_IMPLICIT_POINTER)
1403     add_piece (8 * this->addr_size, 0);
1404
1405   this->recursion_depth--;
1406   gdb_assert (this->recursion_depth >= 0);
1407 }
1408
1409 void
1410 _initialize_dwarf2expr (void)
1411 {
1412   dwarf_arch_cookie
1413     = gdbarch_data_register_post_init (dwarf_gdbarch_types_init);
1414 }