gdb/dwarf2expr.c

   1 /* DWARF 2 Expression Evaluator.
   2
   3    Copyright (C) 2001-2019 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 "gdbsupport/underlying.h"
  31 #include "gdbarch.h"
  32
  33 /* Cookie for gdbarch data.  */
  34
  35 static struct gdbarch_data *dwarf_arch_cookie;
  36
  37 /* This holds gdbarch-specific types used by the DWARF expression
  38    evaluator.  See comments in execute_stack_op.  */
  39
  40 struct dwarf_gdbarch_types
  41 {
  42   struct type *dw_types[3];
  43 };
  44
  45 /* Allocate and fill in dwarf_gdbarch_types for an arch.  */
  46
  47 static void *
  48 dwarf_gdbarch_types_init (struct gdbarch *gdbarch)
  49 {
  50   struct dwarf_gdbarch_types *types
  51     = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct dwarf_gdbarch_types);
  52
  53   /* The types themselves are lazily initialized.  */
  54
  55   return types;
  56 }
  57
  58 /* Return the type used for DWARF operations where the type is
  59    unspecified in the DWARF spec.  Only certain sizes are
  60    supported.  */
  61
  62 struct type *
  63 dwarf_expr_context::address_type () const
  64 {
  65   struct dwarf_gdbarch_types *types
  66     = (struct dwarf_gdbarch_types *) gdbarch_data (this->gdbarch,
  67                                                    dwarf_arch_cookie);
  68   int ndx;
  69
  70   if (this->addr_size == 2)
  71     ndx = 0;
  72   else if (this->addr_size == 4)
  73     ndx = 1;
  74   else if (this->addr_size == 8)
  75     ndx = 2;
  76   else
  77     error (_("Unsupported address size in DWARF expressions: %d bits"),
  78            8 * this->addr_size);
  79
  80   if (types->dw_types[ndx] == NULL)
  81     types->dw_types[ndx]
  82       = arch_integer_type (this->gdbarch,
  83                            8 * this->addr_size,
  84                            0, "<signed DWARF address type>");
  85
  86   return types->dw_types[ndx];
  87 }
  88
  89 /* Create a new context for the expression evaluator.  */
  90
  91 dwarf_expr_context::dwarf_expr_context ()
  92 : gdbarch (NULL),
  93   addr_size (0),
  94   ref_addr_size (0),
  95   offset (0),
  96   recursion_depth (0),
  97   max_recursion_depth (0x100),
  98   location (DWARF_VALUE_MEMORY),
  99   len (0),
 100   data (NULL),
 101   initialized (0)
 102 {
 103 }
 104
 105 /* Push VALUE onto the stack.  */
 106
 107 void
 108 dwarf_expr_context::push (struct value *value, bool in_stack_memory)
 109 {
 110   stack.emplace_back (value, in_stack_memory);
 111 }
 112
 113 /* Push VALUE onto the stack.  */
 114
 115 void
 116 dwarf_expr_context::push_address (CORE_ADDR value, bool in_stack_memory)
 117 {
 118   push (value_from_ulongest (address_type (), value), in_stack_memory);
 119 }
 120
 121 /* Pop the top item off of the stack.  */
 122
 123 void
 124 dwarf_expr_context::pop ()
 125 {
 126   if (stack.empty ())
 127     error (_("dwarf expression stack underflow"));
 128
 129   stack.pop_back ();
 130 }
 131
 132 /* Retrieve the N'th item on the stack.  */
 133
 134 struct value *
 135 dwarf_expr_context::fetch (int n)
 136 {
 137   if (stack.size () <= n)
 138      error (_("Asked for position %d of stack, "
 139               "stack only has %zu elements on it."),
 140             n, stack.size ());
 141   return stack[stack.size () - (1 + n)].value;
 142 }
 143
 144 /* Require that TYPE be an integral type; throw an exception if not.  */
 145
 146 static void
 147 dwarf_require_integral (struct type *type)
 148 {
 149   if (TYPE_CODE (type) != TYPE_CODE_INT
 150       && TYPE_CODE (type) != TYPE_CODE_CHAR
 151       && TYPE_CODE (type) != TYPE_CODE_BOOL)
 152     error (_("integral type expected in DWARF expression"));
 153 }
 154
 155 /* Return the unsigned form of TYPE.  TYPE is necessarily an integral
 156    type.  */
 157
 158 static struct type *
 159 get_unsigned_type (struct gdbarch *gdbarch, struct type *type)
 160 {
 161   switch (TYPE_LENGTH (type))
 162     {
 163     case 1:
 164       return builtin_type (gdbarch)->builtin_uint8;
 165     case 2:
 166       return builtin_type (gdbarch)->builtin_uint16;
 167     case 4:
 168       return builtin_type (gdbarch)->builtin_uint32;
 169     case 8:
 170       return builtin_type (gdbarch)->builtin_uint64;
 171     default:
 172       error (_("no unsigned variant found for type, while evaluating "
 173                "DWARF expression"));
 174     }
 175 }
 176
 177 /* Return the signed form of TYPE.  TYPE is necessarily an integral
 178    type.  */
 179
 180 static struct type *
 181 get_signed_type (struct gdbarch *gdbarch, struct type *type)
 182 {
 183   switch (TYPE_LENGTH (type))
 184     {
 185     case 1:
 186       return builtin_type (gdbarch)->builtin_int8;
 187     case 2:
 188       return builtin_type (gdbarch)->builtin_int16;
 189     case 4:
 190       return builtin_type (gdbarch)->builtin_int32;
 191     case 8:
 192       return builtin_type (gdbarch)->builtin_int64;
 193     default:
 194       error (_("no signed variant found for type, while evaluating "
 195                "DWARF expression"));
 196     }
 197 }
 198
 199 /* Retrieve the N'th item on the stack, converted to an address.  */
 200
 201 CORE_ADDR
 202 dwarf_expr_context::fetch_address (int n)
 203 {
 204   struct value *result_val = fetch (n);
 205   enum bfd_endian byte_order = gdbarch_byte_order (this->gdbarch);
 206   ULONGEST result;
 207
 208   dwarf_require_integral (value_type (result_val));
 209   result = extract_unsigned_integer (value_contents (result_val),
 210                                      TYPE_LENGTH (value_type (result_val)),
 211                                      byte_order);
 212
 213   /* For most architectures, calling extract_unsigned_integer() alone
 214      is sufficient for extracting an address.  However, some
 215      architectures (e.g. MIPS) use signed addresses and using
 216      extract_unsigned_integer() will not produce a correct
 217      result.  Make sure we invoke gdbarch_integer_to_address()
 218      for those architectures which require it.  */
 219   if (gdbarch_integer_to_address_p (this->gdbarch))
 220     {
 221       gdb_byte *buf = (gdb_byte *) alloca (this->addr_size);
 222       struct type *int_type = get_unsigned_type (this->gdbarch,
 223                                                  value_type (result_val));
 224
 225       store_unsigned_integer (buf, this->addr_size, byte_order, result);
 226       return gdbarch_integer_to_address (this->gdbarch, int_type, buf);
 227     }
 228
 229   return (CORE_ADDR) result;
 230 }
 231
 232 /* Retrieve the in_stack_memory flag of the N'th item on the stack.  */
 233
 234 bool
 235 dwarf_expr_context::fetch_in_stack_memory (int n)
 236 {
 237   if (stack.size () <= n)
 238      error (_("Asked for position %d of stack, "
 239               "stack only has %zu elements on it."),
 240             n, stack.size ());
 241   return stack[stack.size () - (1 + n)].in_stack_memory;
 242 }
 243
 244 /* Return true if the expression stack is empty.  */
 245
 246 bool
 247 dwarf_expr_context::stack_empty_p () const
 248 {
 249   return stack.empty ();
 250 }
 251
 252 /* Add a new piece to the dwarf_expr_context's piece list.  */
 253 void
 254 dwarf_expr_context::add_piece (ULONGEST size, ULONGEST offset)
 255 {
 256   this->pieces.emplace_back ();
 257   dwarf_expr_piece &p = this->pieces.back ();
 258
 259   p.location = this->location;
 260   p.size = size;
 261   p.offset = offset;
 262
 263   if (p.location == DWARF_VALUE_LITERAL)
 264     {
 265       p.v.literal.data = this->data;
 266       p.v.literal.length = this->len;
 267     }
 268   else if (stack_empty_p ())
 269     {
 270       p.location = DWARF_VALUE_OPTIMIZED_OUT;
 271       /* Also reset the context's location, for our callers.  This is
 272          a somewhat strange approach, but this lets us avoid setting
 273          the location to DWARF_VALUE_MEMORY in all the individual
 274          cases in the evaluator.  */
 275       this->location = DWARF_VALUE_OPTIMIZED_OUT;
 276     }
 277   else if (p.location == DWARF_VALUE_MEMORY)
 278     {
 279       p.v.mem.addr = fetch_address (0);
 280       p.v.mem.in_stack_memory = fetch_in_stack_memory (0);
 281     }
 282   else if (p.location == DWARF_VALUE_IMPLICIT_POINTER)
 283     {
 284       p.v.ptr.die_sect_off = (sect_offset) this->len;
 285       p.v.ptr.offset = value_as_long (fetch (0));
 286     }
 287   else if (p.location == DWARF_VALUE_REGISTER)
 288     p.v.regno = value_as_long (fetch (0));
 289   else
 290     {
 291       p.v.value = fetch (0);
 292     }
 293 }
 294
 295 /* Evaluate the expression at ADDR (LEN bytes long).  */
 296
 297 void
 298 dwarf_expr_context::eval (const gdb_byte *addr, size_t len)
 299 {
 300   int old_recursion_depth = this->recursion_depth;
 301
 302   execute_stack_op (addr, addr + len);
 303
 304   /* RECURSION_DEPTH becomes invalid if an exception was thrown here.  */
 305
 306   gdb_assert (this->recursion_depth == old_recursion_depth);
 307 }
 308
 309 /* Helper to read a uleb128 value or throw an error.  */
 310
 311 const gdb_byte *
 312 safe_read_uleb128 (const gdb_byte *buf, const gdb_byte *buf_end,
 313                    uint64_t *r)
 314 {
 315   buf = gdb_read_uleb128 (buf, buf_end, r);
 316   if (buf == NULL)
 317     error (_("DWARF expression error: ran off end of buffer reading uleb128 value"));
 318   return buf;
 319 }
 320
 321 /* Helper to read a sleb128 value or throw an error.  */
 322
 323 const gdb_byte *
 324 safe_read_sleb128 (const gdb_byte *buf, const gdb_byte *buf_end,
 325                    int64_t *r)
 326 {
 327   buf = gdb_read_sleb128 (buf, buf_end, r);
 328   if (buf == NULL)
 329     error (_("DWARF expression error: ran off end of buffer reading sleb128 value"));
 330   return buf;
 331 }
 332
 333 const gdb_byte *
 334 safe_skip_leb128 (const gdb_byte *buf, const gdb_byte *buf_end)
 335 {
 336   buf = gdb_skip_leb128 (buf, buf_end);
 337   if (buf == NULL)
 338     error (_("DWARF expression error: ran off end of buffer reading leb128 value"));
 339   return buf;
 340 }
 341 \f
 342
 343 /* Check that the current operator is either at the end of an
 344    expression, or that it is followed by a composition operator or by
 345    DW_OP_GNU_uninit (which should terminate the expression).  */
 346
 347 void
 348 dwarf_expr_require_composition (const gdb_byte *op_ptr, const gdb_byte *op_end,
 349                                 const char *op_name)
 350 {
 351   if (op_ptr != op_end && *op_ptr != DW_OP_piece && *op_ptr != DW_OP_bit_piece
 352       && *op_ptr != DW_OP_GNU_uninit)
 353     error (_("DWARF-2 expression error: `%s' operations must be "
 354              "used either alone or in conjunction with DW_OP_piece "
 355              "or DW_OP_bit_piece."),
 356            op_name);
 357 }
 358
 359 /* Return true iff the types T1 and T2 are "the same".  This only does
 360    checks that might reasonably be needed to compare DWARF base
 361    types.  */
 362
 363 static int
 364 base_types_equal_p (struct type *t1, struct type *t2)
 365 {
 366   if (TYPE_CODE (t1) != TYPE_CODE (t2))
 367     return 0;
 368   if (TYPE_UNSIGNED (t1) != TYPE_UNSIGNED (t2))
 369     return 0;
 370   return TYPE_LENGTH (t1) == TYPE_LENGTH (t2);
 371 }
 372
 373 /* If <BUF..BUF_END] contains DW_FORM_block* with single DW_OP_reg* return the
 374    DWARF register number.  Otherwise return -1.  */
 375
 376 int
 377 dwarf_block_to_dwarf_reg (const gdb_byte *buf, const gdb_byte *buf_end)
 378 {
 379   uint64_t dwarf_reg;
 380
 381   if (buf_end <= buf)
 382     return -1;
 383   if (*buf >= DW_OP_reg0 && *buf <= DW_OP_reg31)
 384     {
 385       if (buf_end - buf != 1)
 386         return -1;
 387       return *buf - DW_OP_reg0;
 388     }
 389
 390   if (*buf == DW_OP_regval_type || *buf == DW_OP_GNU_regval_type)
 391     {
 392       buf++;
 393       buf = gdb_read_uleb128 (buf, buf_end, &dwarf_reg);
 394       if (buf == NULL)
 395         return -1;
 396       buf = gdb_skip_leb128 (buf, buf_end);
 397       if (buf == NULL)
 398         return -1;
 399     }
 400   else if (*buf == DW_OP_regx)
 401     {
 402       buf++;
 403       buf = gdb_read_uleb128 (buf, buf_end, &dwarf_reg);
 404       if (buf == NULL)
 405         return -1;
 406     }
 407   else
 408     return -1;
 409   if (buf != buf_end || (int) dwarf_reg != dwarf_reg)
 410     return -1;
 411   return dwarf_reg;
 412 }
 413
 414 /* If <BUF..BUF_END] contains DW_FORM_block* with just DW_OP_breg*(0) and
 415    DW_OP_deref* return the DWARF register number.  Otherwise return -1.
 416    DEREF_SIZE_RETURN contains -1 for DW_OP_deref; otherwise it contains the
 417    size from DW_OP_deref_size.  */
 418
 419 int
 420 dwarf_block_to_dwarf_reg_deref (const gdb_byte *buf, const gdb_byte *buf_end,
 421                                 CORE_ADDR *deref_size_return)
 422 {
 423   uint64_t dwarf_reg;
 424   int64_t offset;
 425
 426   if (buf_end <= buf)
 427     return -1;
 428
 429   if (*buf >= DW_OP_breg0 && *buf <= DW_OP_breg31)
 430     {
 431       dwarf_reg = *buf - DW_OP_breg0;
 432       buf++;
 433       if (buf >= buf_end)
 434         return -1;
 435     }
 436   else if (*buf == DW_OP_bregx)
 437     {
 438       buf++;
 439       buf = gdb_read_uleb128 (buf, buf_end, &dwarf_reg);
 440       if (buf == NULL)
 441         return -1;
 442       if ((int) dwarf_reg != dwarf_reg)
 443        return -1;
 444     }
 445   else
 446     return -1;
 447
 448   buf = gdb_read_sleb128 (buf, buf_end, &offset);
 449   if (buf == NULL)
 450     return -1;
 451   if (offset != 0)
 452     return -1;
 453
 454   if (*buf == DW_OP_deref)
 455     {
 456       buf++;
 457       *deref_size_return = -1;
 458     }
 459   else if (*buf == DW_OP_deref_size)
 460     {
 461       buf++;
 462       if (buf >= buf_end)
 463        return -1;
 464       *deref_size_return = *buf++;
 465     }
 466   else
 467     return -1;
 468
 469   if (buf != buf_end)
 470     return -1;
 471
 472   return dwarf_reg;
 473 }
 474
 475 /* If <BUF..BUF_END] contains DW_FORM_block* with single DW_OP_fbreg(X) fill
 476    in FB_OFFSET_RETURN with the X offset and return 1.  Otherwise return 0.  */
 477
 478 int
 479 dwarf_block_to_fb_offset (const gdb_byte *buf, const gdb_byte *buf_end,
 480                           CORE_ADDR *fb_offset_return)
 481 {
 482   int64_t fb_offset;
 483
 484   if (buf_end <= buf)
 485     return 0;
 486
 487   if (*buf != DW_OP_fbreg)
 488     return 0;
 489   buf++;
 490
 491   buf = gdb_read_sleb128 (buf, buf_end, &fb_offset);
 492   if (buf == NULL)
 493     return 0;
 494   *fb_offset_return = fb_offset;
 495   if (buf != buf_end || fb_offset != (LONGEST) *fb_offset_return)
 496     return 0;
 497
 498   return 1;
 499 }
 500
 501 /* If <BUF..BUF_END] contains DW_FORM_block* with single DW_OP_bregSP(X) fill
 502    in SP_OFFSET_RETURN with the X offset and return 1.  Otherwise return 0.
 503    The matched SP register number depends on GDBARCH.  */
 504
 505 int
 506 dwarf_block_to_sp_offset (struct gdbarch *gdbarch, const gdb_byte *buf,
 507                           const gdb_byte *buf_end, CORE_ADDR *sp_offset_return)
 508 {
 509   uint64_t dwarf_reg;
 510   int64_t sp_offset;
 511
 512   if (buf_end <= buf)
 513     return 0;
 514   if (*buf >= DW_OP_breg0 && *buf <= DW_OP_breg31)
 515     {
 516       dwarf_reg = *buf - DW_OP_breg0;
 517       buf++;
 518     }
 519   else
 520     {
 521       if (*buf != DW_OP_bregx)
 522        return 0;
 523       buf++;
 524       buf = gdb_read_uleb128 (buf, buf_end, &dwarf_reg);
 525       if (buf == NULL)
 526         return 0;
 527     }
 528
 529   if (dwarf_reg_to_regnum (gdbarch, dwarf_reg)
 530       != gdbarch_sp_regnum (gdbarch))
 531     return 0;
 532
 533   buf = gdb_read_sleb128 (buf, buf_end, &sp_offset);
 534   if (buf == NULL)
 535     return 0;
 536   *sp_offset_return = sp_offset;
 537   if (buf != buf_end || sp_offset != (LONGEST) *sp_offset_return)
 538     return 0;
 539
 540   return 1;
 541 }
 542
 543 /* The engine for the expression evaluator.  Using the context in this
 544    object, evaluate the expression between OP_PTR and OP_END.  */
 545
 546 void
 547 dwarf_expr_context::execute_stack_op (const gdb_byte *op_ptr,
 548                                       const gdb_byte *op_end)
 549 {
 550   enum bfd_endian byte_order = gdbarch_byte_order (this->gdbarch);
 551   /* Old-style "untyped" DWARF values need special treatment in a
 552      couple of places, specifically DW_OP_mod and DW_OP_shr.  We need
 553      a special type for these values so we can distinguish them from
 554      values that have an explicit type, because explicitly-typed
 555      values do not need special treatment.  This special type must be
 556      different (in the `==' sense) from any base type coming from the
 557      CU.  */
 558   struct type *address_type = this->address_type ();
 559
 560   this->location = DWARF_VALUE_MEMORY;
 561   this->initialized = 1;  /* Default is initialized.  */
 562
 563   if (this->recursion_depth > this->max_recursion_depth)
 564     error (_("DWARF-2 expression error: Loop detected (%d)."),
 565            this->recursion_depth);
 566   this->recursion_depth++;
 567
 568   while (op_ptr < op_end)
 569     {
 570       enum dwarf_location_atom op = (enum dwarf_location_atom) *op_ptr++;
 571       ULONGEST result;
 572       /* Assume the value is not in stack memory.
 573          Code that knows otherwise sets this to true.
 574          Some arithmetic on stack addresses can probably be assumed to still
 575          be a stack address, but we skip this complication for now.
 576          This is just an optimization, so it's always ok to punt
 577          and leave this as false.  */
 578       bool in_stack_memory = false;
 579       uint64_t uoffset, reg;
 580       int64_t offset;
 581       struct value *result_val = NULL;
 582
 583       /* The DWARF expression might have a bug causing an infinite
 584          loop.  In that case, quitting is the only way out.  */
 585       QUIT;
 586
 587       switch (op)
 588         {
 589         case DW_OP_lit0:
 590         case DW_OP_lit1:
 591         case DW_OP_lit2:
 592         case DW_OP_lit3:
 593         case DW_OP_lit4:
 594         case DW_OP_lit5:
 595         case DW_OP_lit6:
 596         case DW_OP_lit7:
 597         case DW_OP_lit8:
 598         case DW_OP_lit9:
 599         case DW_OP_lit10:
 600         case DW_OP_lit11:
 601         case DW_OP_lit12:
 602         case DW_OP_lit13:
 603         case DW_OP_lit14:
 604         case DW_OP_lit15:
 605         case DW_OP_lit16:
 606         case DW_OP_lit17:
 607         case DW_OP_lit18:
 608         case DW_OP_lit19:
 609         case DW_OP_lit20:
 610         case DW_OP_lit21:
 611         case DW_OP_lit22:
 612         case DW_OP_lit23:
 613         case DW_OP_lit24:
 614         case DW_OP_lit25:
 615         case DW_OP_lit26:
 616         case DW_OP_lit27:
 617         case DW_OP_lit28:
 618         case DW_OP_lit29:
 619         case DW_OP_lit30:
 620         case DW_OP_lit31:
 621           result = op - DW_OP_lit0;
 622           result_val = value_from_ulongest (address_type, result);
 623           break;
 624
 625         case DW_OP_addr:
 626           result = extract_unsigned_integer (op_ptr,
 627                                              this->addr_size, byte_order);
 628           op_ptr += this->addr_size;
 629           /* Some versions of GCC emit DW_OP_addr before
 630              DW_OP_GNU_push_tls_address.  In this case the value is an
 631              index, not an address.  We don't support things like
 632              branching between the address and the TLS op.  */
 633           if (op_ptr >= op_end || *op_ptr != DW_OP_GNU_push_tls_address)
 634             result += this->offset;
 635           result_val = value_from_ulongest (address_type, result);
 636           break;
 637
 638         case DW_OP_addrx:
 639         case DW_OP_GNU_addr_index:
 640           op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
 641           result = this->get_addr_index (uoffset);
 642           result += this->offset;
 643           result_val = value_from_ulongest (address_type, result);
 644           break;
 645         case DW_OP_GNU_const_index:
 646           op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
 647           result = this->get_addr_index (uoffset);
 648           result_val = value_from_ulongest (address_type, result);
 649           break;
 650
 651         case DW_OP_const1u:
 652           result = extract_unsigned_integer (op_ptr, 1, byte_order);
 653           result_val = value_from_ulongest (address_type, result);
 654           op_ptr += 1;
 655           break;
 656         case DW_OP_const1s:
 657           result = extract_signed_integer (op_ptr, 1, byte_order);
 658           result_val = value_from_ulongest (address_type, result);
 659           op_ptr += 1;
 660           break;
 661         case DW_OP_const2u:
 662           result = extract_unsigned_integer (op_ptr, 2, byte_order);
 663           result_val = value_from_ulongest (address_type, result);
 664           op_ptr += 2;
 665           break;
 666         case DW_OP_const2s:
 667           result = extract_signed_integer (op_ptr, 2, byte_order);
 668           result_val = value_from_ulongest (address_type, result);
 669           op_ptr += 2;
 670           break;
 671         case DW_OP_const4u:
 672           result = extract_unsigned_integer (op_ptr, 4, byte_order);
 673           result_val = value_from_ulongest (address_type, result);
 674           op_ptr += 4;
 675           break;
 676         case DW_OP_const4s:
 677           result = extract_signed_integer (op_ptr, 4, byte_order);
 678           result_val = value_from_ulongest (address_type, result);
 679           op_ptr += 4;
 680           break;
 681         case DW_OP_const8u:
 682           result = extract_unsigned_integer (op_ptr, 8, byte_order);
 683           result_val = value_from_ulongest (address_type, result);
 684           op_ptr += 8;
 685           break;
 686         case DW_OP_const8s:
 687           result = extract_signed_integer (op_ptr, 8, byte_order);
 688           result_val = value_from_ulongest (address_type, result);
 689           op_ptr += 8;
 690           break;
 691         case DW_OP_constu:
 692           op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
 693           result = uoffset;
 694           result_val = value_from_ulongest (address_type, result);
 695           break;
 696         case DW_OP_consts:
 697           op_ptr = safe_read_sleb128 (op_ptr, op_end, &offset);
 698           result = offset;
 699           result_val = value_from_ulongest (address_type, result);
 700           break;
 701
 702         /* The DW_OP_reg operations are required to occur alone in
 703            location expressions.  */
 704         case DW_OP_reg0:
 705         case DW_OP_reg1:
 706         case DW_OP_reg2:
 707         case DW_OP_reg3:
 708         case DW_OP_reg4:
 709         case DW_OP_reg5:
 710         case DW_OP_reg6:
 711         case DW_OP_reg7:
 712         case DW_OP_reg8:
 713         case DW_OP_reg9:
 714         case DW_OP_reg10:
 715         case DW_OP_reg11:
 716         case DW_OP_reg12:
 717         case DW_OP_reg13:
 718         case DW_OP_reg14:
 719         case DW_OP_reg15:
 720         case DW_OP_reg16:
 721         case DW_OP_reg17:
 722         case DW_OP_reg18:
 723         case DW_OP_reg19:
 724         case DW_OP_reg20:
 725         case DW_OP_reg21:
 726         case DW_OP_reg22:
 727         case DW_OP_reg23:
 728         case DW_OP_reg24:
 729         case DW_OP_reg25:
 730         case DW_OP_reg26:
 731         case DW_OP_reg27:
 732         case DW_OP_reg28:
 733         case DW_OP_reg29:
 734         case DW_OP_reg30:
 735         case DW_OP_reg31:
 736           dwarf_expr_require_composition (op_ptr, op_end, "DW_OP_reg");
 737
 738           result = op - DW_OP_reg0;
 739           result_val = value_from_ulongest (address_type, result);
 740           this->location = DWARF_VALUE_REGISTER;
 741           break;
 742
 743         case DW_OP_regx:
 744           op_ptr = safe_read_uleb128 (op_ptr, op_end, &reg);
 745           dwarf_expr_require_composition (op_ptr, op_end, "DW_OP_regx");
 746
 747           result = reg;
 748           result_val = value_from_ulongest (address_type, result);
 749           this->location = DWARF_VALUE_REGISTER;
 750           break;
 751
 752         case DW_OP_implicit_value:
 753           {
 754             uint64_t len;
 755
 756             op_ptr = safe_read_uleb128 (op_ptr, op_end, &len);
 757             if (op_ptr + len > op_end)
 758               error (_("DW_OP_implicit_value: too few bytes available."));
 759             this->len = len;
 760             this->data = op_ptr;
 761             this->location = DWARF_VALUE_LITERAL;
 762             op_ptr += len;
 763             dwarf_expr_require_composition (op_ptr, op_end,
 764                                             "DW_OP_implicit_value");
 765           }
 766           goto no_push;
 767
 768         case DW_OP_stack_value:
 769           this->location = DWARF_VALUE_STACK;
 770           dwarf_expr_require_composition (op_ptr, op_end, "DW_OP_stack_value");
 771           goto no_push;
 772
 773         case DW_OP_implicit_pointer:
 774         case DW_OP_GNU_implicit_pointer:
 775           {
 776             int64_t len;
 777
 778             if (this->ref_addr_size == -1)
 779               error (_("DWARF-2 expression error: DW_OP_implicit_pointer "
 780                        "is not allowed in frame context"));
 781
 782             /* The referred-to DIE of sect_offset kind.  */
 783             this->len = extract_unsigned_integer (op_ptr, this->ref_addr_size,
 784                                                  byte_order);
 785             op_ptr += this->ref_addr_size;
 786
 787             /* The byte offset into the data.  */
 788             op_ptr = safe_read_sleb128 (op_ptr, op_end, &len);
 789             result = (ULONGEST) len;
 790             result_val = value_from_ulongest (address_type, result);
 791
 792             this->location = DWARF_VALUE_IMPLICIT_POINTER;
 793             dwarf_expr_require_composition (op_ptr, op_end,
 794                                             "DW_OP_implicit_pointer");
 795           }
 796           break;
 797
 798         case DW_OP_breg0:
 799         case DW_OP_breg1:
 800         case DW_OP_breg2:
 801         case DW_OP_breg3:
 802         case DW_OP_breg4:
 803         case DW_OP_breg5:
 804         case DW_OP_breg6:
 805         case DW_OP_breg7:
 806         case DW_OP_breg8:
 807         case DW_OP_breg9:
 808         case DW_OP_breg10:
 809         case DW_OP_breg11:
 810         case DW_OP_breg12:
 811         case DW_OP_breg13:
 812         case DW_OP_breg14:
 813         case DW_OP_breg15:
 814         case DW_OP_breg16:
 815         case DW_OP_breg17:
 816         case DW_OP_breg18:
 817         case DW_OP_breg19:
 818         case DW_OP_breg20:
 819         case DW_OP_breg21:
 820         case DW_OP_breg22:
 821         case DW_OP_breg23:
 822         case DW_OP_breg24:
 823         case DW_OP_breg25:
 824         case DW_OP_breg26:
 825         case DW_OP_breg27:
 826         case DW_OP_breg28:
 827         case DW_OP_breg29:
 828         case DW_OP_breg30:
 829         case DW_OP_breg31:
 830           {
 831             op_ptr = safe_read_sleb128 (op_ptr, op_end, &offset);
 832             result = this->read_addr_from_reg (op - DW_OP_breg0);
 833             result += offset;
 834             result_val = value_from_ulongest (address_type, result);
 835           }
 836           break;
 837         case DW_OP_bregx:
 838           {
 839             op_ptr = safe_read_uleb128 (op_ptr, op_end, &reg);
 840             op_ptr = safe_read_sleb128 (op_ptr, op_end, &offset);
 841             result = this->read_addr_from_reg (reg);
 842             result += offset;
 843             result_val = value_from_ulongest (address_type, result);
 844           }
 845           break;
 846         case DW_OP_fbreg:
 847           {
 848             const gdb_byte *datastart;
 849             size_t datalen;
 850
 851             op_ptr = safe_read_sleb128 (op_ptr, op_end, &offset);
 852
 853             /* Rather than create a whole new context, we simply
 854                backup the current stack locally and install a new empty stack,
 855                then reset it afterwards, effectively erasing whatever the
 856                recursive call put there.  */
 857             std::vector<dwarf_stack_value> saved_stack = std::move (stack);
 858             stack.clear ();
 859
 860             /* FIXME: cagney/2003-03-26: This code should be using
 861                get_frame_base_address(), and then implement a dwarf2
 862                specific this_base method.  */
 863             this->get_frame_base (&datastart, &datalen);
 864             eval (datastart, datalen);
 865             if (this->location == DWARF_VALUE_MEMORY)
 866               result = fetch_address (0);
 867             else if (this->location == DWARF_VALUE_REGISTER)
 868               result = this->read_addr_from_reg (value_as_long (fetch (0)));
 869             else
 870               error (_("Not implemented: computing frame "
 871                        "base using explicit value operator"));
 872             result = result + offset;
 873             result_val = value_from_ulongest (address_type, result);
 874             in_stack_memory = true;
 875
 876             /* Restore the content of the original stack.  */
 877             stack = std::move (saved_stack);
 878
 879             this->location = DWARF_VALUE_MEMORY;
 880           }
 881           break;
 882
 883         case DW_OP_dup:
 884           result_val = fetch (0);
 885           in_stack_memory = fetch_in_stack_memory (0);
 886           break;
 887
 888         case DW_OP_drop:
 889           pop ();
 890           goto no_push;
 891
 892         case DW_OP_pick:
 893           offset = *op_ptr++;
 894           result_val = fetch (offset);
 895           in_stack_memory = fetch_in_stack_memory (offset);
 896           break;
 897
 898         case DW_OP_swap:
 899           {
 900             if (stack.size () < 2)
 901                error (_("Not enough elements for "
 902                         "DW_OP_swap.  Need 2, have %zu."),
 903                       stack.size ());
 904
 905             dwarf_stack_value &t1 = stack[stack.size () - 1];
 906             dwarf_stack_value &t2 = stack[stack.size () - 2];
 907             std::swap (t1, t2);
 908             goto no_push;
 909           }
 910
 911         case DW_OP_over:
 912           result_val = fetch (1);
 913           in_stack_memory = fetch_in_stack_memory (1);
 914           break;
 915
 916         case DW_OP_rot:
 917           {
 918             if (stack.size () < 3)
 919                error (_("Not enough elements for "
 920                         "DW_OP_rot.  Need 3, have %zu."),
 921                       stack.size ());
 922
 923             dwarf_stack_value temp = stack[stack.size () - 1];
 924             stack[stack.size () - 1] = stack[stack.size () - 2];
 925             stack[stack.size () - 2] = stack[stack.size () - 3];
 926             stack[stack.size () - 3] = temp;
 927             goto no_push;
 928           }
 929
 930         case DW_OP_deref:
 931         case DW_OP_deref_size:
 932         case DW_OP_deref_type:
 933         case DW_OP_GNU_deref_type:
 934           {
 935             int addr_size = (op == DW_OP_deref ? this->addr_size : *op_ptr++);
 936             gdb_byte *buf = (gdb_byte *) alloca (addr_size);
 937             CORE_ADDR addr = fetch_address (0);
 938             struct type *type;
 939
 940             pop ();
 941
 942             if (op == DW_OP_deref_type || op == DW_OP_GNU_deref_type)
 943               {
 944                 op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
 945                 cu_offset type_die_cu_off = (cu_offset) uoffset;
 946                 type = get_base_type (type_die_cu_off, 0);
 947               }
 948             else
 949               type = address_type;
 950
 951             this->read_mem (buf, addr, addr_size);
 952
 953             /* If the size of the object read from memory is different
 954                from the type length, we need to zero-extend it.  */
 955             if (TYPE_LENGTH (type) != addr_size)
 956               {
 957                 ULONGEST datum =
 958                   extract_unsigned_integer (buf, addr_size, byte_order);
 959
 960                 buf = (gdb_byte *) alloca (TYPE_LENGTH (type));
 961                 store_unsigned_integer (buf, TYPE_LENGTH (type),
 962                                         byte_order, datum);
 963               }
 964
 965             result_val = value_from_contents_and_address (type, buf, addr);
 966             break;
 967           }
 968
 969         case DW_OP_abs:
 970         case DW_OP_neg:
 971         case DW_OP_not:
 972         case DW_OP_plus_uconst:
 973           {
 974             /* Unary operations.  */
 975             result_val = fetch (0);
 976             pop ();
 977
 978             switch (op)
 979               {
 980               case DW_OP_abs:
 981                 if (value_less (result_val,
 982                                 value_zero (value_type (result_val), not_lval)))
 983                   result_val = value_neg (result_val);
 984                 break;
 985               case DW_OP_neg:
 986                 result_val = value_neg (result_val);
 987                 break;
 988               case DW_OP_not:
 989                 dwarf_require_integral (value_type (result_val));
 990                 result_val = value_complement (result_val);
 991                 break;
 992               case DW_OP_plus_uconst:
 993                 dwarf_require_integral (value_type (result_val));
 994                 result = value_as_long (result_val);
 995                 op_ptr = safe_read_uleb128 (op_ptr, op_end, &reg);
 996                 result += reg;
 997                 result_val = value_from_ulongest (address_type, result);
 998                 break;
 999               }
1000           }
1001           break;
1002
1003         case DW_OP_and:
1004         case DW_OP_div:
1005         case DW_OP_minus:
1006         case DW_OP_mod:
1007         case DW_OP_mul:
1008         case DW_OP_or:
1009         case DW_OP_plus:
1010         case DW_OP_shl:
1011         case DW_OP_shr:
1012         case DW_OP_shra:
1013         case DW_OP_xor:
1014         case DW_OP_le:
1015         case DW_OP_ge:
1016         case DW_OP_eq:
1017         case DW_OP_lt:
1018         case DW_OP_gt:
1019         case DW_OP_ne:
1020           {
1021             /* Binary operations.  */
1022             struct value *first, *second;
1023
1024             second = fetch (0);
1025             pop ();
1026
1027             first = fetch (0);
1028             pop ();
1029
1030             if (! base_types_equal_p (value_type (first), value_type (second)))
1031               error (_("Incompatible types on DWARF stack"));
1032
1033             switch (op)
1034               {
1035               case DW_OP_and:
1036                 dwarf_require_integral (value_type (first));
1037                 dwarf_require_integral (value_type (second));
1038                 result_val = value_binop (first, second, BINOP_BITWISE_AND);
1039                 break;
1040               case DW_OP_div:
1041                 result_val = value_binop (first, second, BINOP_DIV);
1042                 break;
1043               case DW_OP_minus:
1044                 result_val = value_binop (first, second, BINOP_SUB);
1045                 break;
1046               case DW_OP_mod:
1047                 {
1048                   int cast_back = 0;
1049                   struct type *orig_type = value_type (first);
1050
1051                   /* We have to special-case "old-style" untyped values
1052                      -- these must have mod computed using unsigned
1053                      math.  */
1054                   if (orig_type == address_type)
1055                     {
1056                       struct type *utype
1057                         = get_unsigned_type (this->gdbarch, orig_type);
1058
1059                       cast_back = 1;
1060                       first = value_cast (utype, first);
1061                       second = value_cast (utype, second);
1062                     }
1063                   /* Note that value_binop doesn't handle float or
1064                      decimal float here.  This seems unimportant.  */
1065                   result_val = value_binop (first, second, BINOP_MOD);
1066                   if (cast_back)
1067                     result_val = value_cast (orig_type, result_val);
1068                 }
1069                 break;
1070               case DW_OP_mul:
1071                 result_val = value_binop (first, second, BINOP_MUL);
1072                 break;
1073               case DW_OP_or:
1074                 dwarf_require_integral (value_type (first));
1075                 dwarf_require_integral (value_type (second));
1076                 result_val = value_binop (first, second, BINOP_BITWISE_IOR);
1077                 break;
1078               case DW_OP_plus:
1079                 result_val = value_binop (first, second, BINOP_ADD);
1080                 break;
1081               case DW_OP_shl:
1082                 dwarf_require_integral (value_type (first));
1083                 dwarf_require_integral (value_type (second));
1084                 result_val = value_binop (first, second, BINOP_LSH);
1085                 break;
1086               case DW_OP_shr:
1087                 dwarf_require_integral (value_type (first));
1088                 dwarf_require_integral (value_type (second));
1089                 if (!TYPE_UNSIGNED (value_type (first)))
1090                   {
1091                     struct type *utype
1092                       = get_unsigned_type (this->gdbarch, value_type (first));
1093
1094                     first = value_cast (utype, first);
1095                   }
1096
1097                 result_val = value_binop (first, second, BINOP_RSH);
1098                 /* Make sure we wind up with the same type we started
1099                    with.  */
1100                 if (value_type (result_val) != value_type (second))
1101                   result_val = value_cast (value_type (second), result_val);
1102                 break;
1103               case DW_OP_shra:
1104                 dwarf_require_integral (value_type (first));
1105                 dwarf_require_integral (value_type (second));
1106                 if (TYPE_UNSIGNED (value_type (first)))
1107                   {
1108                     struct type *stype
1109                       = get_signed_type (this->gdbarch, value_type (first));
1110
1111                     first = value_cast (stype, first);
1112                   }
1113
1114                 result_val = value_binop (first, second, BINOP_RSH);
1115                 /* Make sure we wind up with the same type we started
1116                    with.  */
1117                 if (value_type (result_val) != value_type (second))
1118                   result_val = value_cast (value_type (second), result_val);
1119                 break;
1120               case DW_OP_xor:
1121                 dwarf_require_integral (value_type (first));
1122                 dwarf_require_integral (value_type (second));
1123                 result_val = value_binop (first, second, BINOP_BITWISE_XOR);
1124                 break;
1125               case DW_OP_le:
1126                 /* A <= B is !(B < A).  */
1127                 result = ! value_less (second, first);
1128                 result_val = value_from_ulongest (address_type, result);
1129                 break;
1130               case DW_OP_ge:
1131                 /* A >= B is !(A < B).  */
1132                 result = ! value_less (first, second);
1133                 result_val = value_from_ulongest (address_type, result);
1134                 break;
1135               case DW_OP_eq:
1136                 result = value_equal (first, second);
1137                 result_val = value_from_ulongest (address_type, result);
1138                 break;
1139               case DW_OP_lt:
1140                 result = value_less (first, second);
1141                 result_val = value_from_ulongest (address_type, result);
1142                 break;
1143               case DW_OP_gt:
1144                 /* A > B is B < A.  */
1145                 result = value_less (second, first);
1146                 result_val = value_from_ulongest (address_type, result);
1147                 break;
1148               case DW_OP_ne:
1149                 result = ! value_equal (first, second);
1150                 result_val = value_from_ulongest (address_type, result);
1151                 break;
1152               default:
1153                 internal_error (__FILE__, __LINE__,
1154                                 _("Can't be reached."));
1155               }
1156           }
1157           break;
1158
1159         case DW_OP_call_frame_cfa:
1160           result = this->get_frame_cfa ();
1161           result_val = value_from_ulongest (address_type, result);
1162           in_stack_memory = true;
1163           break;
1164
1165         case DW_OP_GNU_push_tls_address:
1166         case DW_OP_form_tls_address:
1167           /* Variable is at a constant offset in the thread-local
1168           storage block into the objfile for the current thread and
1169           the dynamic linker module containing this expression.  Here
1170           we return returns the offset from that base.  The top of the
1171           stack has the offset from the beginning of the thread
1172           control block at which the variable is located.  Nothing
1173           should follow this operator, so the top of stack would be
1174           returned.  */
1175           result = value_as_long (fetch (0));
1176           pop ();
1177           result = this->get_tls_address (result);
1178           result_val = value_from_ulongest (address_type, result);
1179           break;
1180
1181         case DW_OP_skip:
1182           offset = extract_signed_integer (op_ptr, 2, byte_order);
1183           op_ptr += 2;
1184           op_ptr += offset;
1185           goto no_push;
1186
1187         case DW_OP_bra:
1188           {
1189             struct value *val;
1190
1191             offset = extract_signed_integer (op_ptr, 2, byte_order);
1192             op_ptr += 2;
1193             val = fetch (0);
1194             dwarf_require_integral (value_type (val));
1195             if (value_as_long (val) != 0)
1196               op_ptr += offset;
1197             pop ();
1198           }
1199           goto no_push;
1200
1201         case DW_OP_nop:
1202           goto no_push;
1203
1204         case DW_OP_piece:
1205           {
1206             uint64_t size;
1207
1208             /* Record the piece.  */
1209             op_ptr = safe_read_uleb128 (op_ptr, op_end, &size);
1210             add_piece (8 * size, 0);
1211
1212             /* Pop off the address/regnum, and reset the location
1213                type.  */
1214             if (this->location != DWARF_VALUE_LITERAL
1215                 && this->location != DWARF_VALUE_OPTIMIZED_OUT)
1216               pop ();
1217             this->location = DWARF_VALUE_MEMORY;
1218           }
1219           goto no_push;
1220
1221         case DW_OP_bit_piece:
1222           {
1223             uint64_t size, uleb_offset;
1224
1225             /* Record the piece.  */
1226             op_ptr = safe_read_uleb128 (op_ptr, op_end, &size);
1227             op_ptr = safe_read_uleb128 (op_ptr, op_end, &uleb_offset);
1228             add_piece (size, uleb_offset);
1229
1230             /* Pop off the address/regnum, and reset the location
1231                type.  */
1232             if (this->location != DWARF_VALUE_LITERAL
1233                 && this->location != DWARF_VALUE_OPTIMIZED_OUT)
1234               pop ();
1235             this->location = DWARF_VALUE_MEMORY;
1236           }
1237           goto no_push;
1238
1239         case DW_OP_GNU_uninit:
1240           if (op_ptr != op_end)
1241             error (_("DWARF-2 expression error: DW_OP_GNU_uninit must always "
1242                    "be the very last op."));
1243
1244           this->initialized = 0;
1245           goto no_push;
1246
1247         case DW_OP_call2:
1248           {
1249             cu_offset cu_off
1250               = (cu_offset) extract_unsigned_integer (op_ptr, 2, byte_order);
1251             op_ptr += 2;
1252             this->dwarf_call (cu_off);
1253           }
1254           goto no_push;
1255
1256         case DW_OP_call4:
1257           {
1258             cu_offset cu_off
1259               = (cu_offset) extract_unsigned_integer (op_ptr, 4, byte_order);
1260             op_ptr += 4;
1261             this->dwarf_call (cu_off);
1262           }
1263           goto no_push;
1264
1265         case DW_OP_GNU_variable_value:
1266           {
1267             sect_offset sect_off
1268               = (sect_offset) extract_unsigned_integer (op_ptr,
1269                                                         this->ref_addr_size,
1270                                                         byte_order);
1271             op_ptr += this->ref_addr_size;
1272             result_val = this->dwarf_variable_value (sect_off);
1273           }
1274           break;
1275
1276         case DW_OP_entry_value:
1277         case DW_OP_GNU_entry_value:
1278           {
1279             uint64_t len;
1280             CORE_ADDR deref_size;
1281             union call_site_parameter_u kind_u;
1282
1283             op_ptr = safe_read_uleb128 (op_ptr, op_end, &len);
1284             if (op_ptr + len > op_end)
1285               error (_("DW_OP_entry_value: too few bytes available."));
1286
1287             kind_u.dwarf_reg = dwarf_block_to_dwarf_reg (op_ptr, op_ptr + len);
1288             if (kind_u.dwarf_reg != -1)
1289               {
1290                 op_ptr += len;
1291                 this->push_dwarf_reg_entry_value (CALL_SITE_PARAMETER_DWARF_REG,
1292                                                   kind_u,
1293                                                   -1 /* deref_size */);
1294                 goto no_push;
1295               }
1296
1297             kind_u.dwarf_reg = dwarf_block_to_dwarf_reg_deref (op_ptr,
1298                                                                op_ptr + len,
1299                                                                &deref_size);
1300             if (kind_u.dwarf_reg != -1)
1301               {
1302                 if (deref_size == -1)
1303                   deref_size = this->addr_size;
1304                 op_ptr += len;
1305                 this->push_dwarf_reg_entry_value (CALL_SITE_PARAMETER_DWARF_REG,
1306                                                   kind_u, deref_size);
1307                 goto no_push;
1308               }
1309
1310             error (_("DWARF-2 expression error: DW_OP_entry_value is "
1311                      "supported only for single DW_OP_reg* "
1312                      "or for DW_OP_breg*(0)+DW_OP_deref*"));
1313           }
1314
1315         case DW_OP_GNU_parameter_ref:
1316           {
1317             union call_site_parameter_u kind_u;
1318
1319             kind_u.param_cu_off
1320               = (cu_offset) extract_unsigned_integer (op_ptr, 4, byte_order);
1321             op_ptr += 4;
1322             this->push_dwarf_reg_entry_value (CALL_SITE_PARAMETER_PARAM_OFFSET,
1323                                               kind_u,
1324                                               -1 /* deref_size */);
1325           }
1326           goto no_push;
1327
1328         case DW_OP_const_type:
1329         case DW_OP_GNU_const_type:
1330           {
1331             int n;
1332             const gdb_byte *data;
1333             struct type *type;
1334
1335             op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
1336             cu_offset type_die_cu_off = (cu_offset) uoffset;
1337
1338             n = *op_ptr++;
1339             data = op_ptr;
1340             op_ptr += n;
1341
1342             type = get_base_type (type_die_cu_off, n);
1343             result_val = value_from_contents (type, data);
1344           }
1345           break;
1346
1347         case DW_OP_regval_type:
1348         case DW_OP_GNU_regval_type:
1349           {
1350             struct type *type;
1351
1352             op_ptr = safe_read_uleb128 (op_ptr, op_end, &reg);
1353             op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
1354             cu_offset type_die_cu_off = (cu_offset) uoffset;
1355
1356             type = get_base_type (type_die_cu_off, 0);
1357             result_val = this->get_reg_value (type, reg);
1358           }
1359           break;
1360
1361         case DW_OP_convert:
1362         case DW_OP_GNU_convert:
1363         case DW_OP_reinterpret:
1364         case DW_OP_GNU_reinterpret:
1365           {
1366             struct type *type;
1367
1368             op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
1369             cu_offset type_die_cu_off = (cu_offset) uoffset;
1370
1371             if (to_underlying (type_die_cu_off) == 0)
1372               type = address_type;
1373             else
1374               type = get_base_type (type_die_cu_off, 0);
1375
1376             result_val = fetch (0);
1377             pop ();
1378
1379             if (op == DW_OP_convert || op == DW_OP_GNU_convert)
1380               result_val = value_cast (type, result_val);
1381             else if (type == value_type (result_val))
1382               {
1383                 /* Nothing.  */
1384               }
1385             else if (TYPE_LENGTH (type)
1386                      != TYPE_LENGTH (value_type (result_val)))
1387               error (_("DW_OP_reinterpret has wrong size"));
1388             else
1389               result_val
1390                 = value_from_contents (type,
1391                                        value_contents_all (result_val));
1392           }
1393           break;
1394
1395         case DW_OP_push_object_address:
1396           /* Return the address of the object we are currently observing.  */
1397           result = this->get_object_address ();
1398           result_val = value_from_ulongest (address_type, result);
1399           break;
1400
1401         default:
1402           error (_("Unhandled dwarf expression opcode 0x%x"), op);
1403         }
1404
1405       /* Most things push a result value.  */
1406       gdb_assert (result_val != NULL);
1407       push (result_val, in_stack_memory);
1408     no_push:
1409       ;
1410     }
1411
1412   /* To simplify our main caller, if the result is an implicit
1413      pointer, then make a pieced value.  This is ok because we can't
1414      have implicit pointers in contexts where pieces are invalid.  */
1415   if (this->location == DWARF_VALUE_IMPLICIT_POINTER)
1416     add_piece (8 * this->addr_size, 0);
1417
1418   this->recursion_depth--;
1419   gdb_assert (this->recursion_depth >= 0);
1420 }
1421
1422 void
1423 _initialize_dwarf2expr (void)
1424 {
1425   dwarf_arch_cookie
1426     = gdbarch_data_register_post_init (dwarf_gdbarch_types_init);
1427 }