gdb/dwarf2expr.c

   1 /* DWARF 2 Expression Evaluator.
   2
   3    Copyright (C) 2001, 2002, 2003, 2005, 2007 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 2 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, write to the Free Software
  21    Foundation, Inc., 51 Franklin Street, Fifth Floor,
  22    Boston, MA 02110-1301, USA.  */
  23
  24 #include "defs.h"
  25 #include "symtab.h"
  26 #include "gdbtypes.h"
  27 #include "value.h"
  28 #include "gdbcore.h"
  29 #include "elf/dwarf2.h"
  30 #include "dwarf2expr.h"
  31
  32 /* Local prototypes.  */
  33
  34 static void execute_stack_op (struct dwarf_expr_context *,
  35                               gdb_byte *, gdb_byte *);
  36
  37 /* Create a new context for the expression evaluator.  */
  38
  39 struct dwarf_expr_context *
  40 new_dwarf_expr_context (void)
  41 {
  42   struct dwarf_expr_context *retval;
  43   retval = xcalloc (1, sizeof (struct dwarf_expr_context));
  44   retval->stack_len = 0;
  45   retval->stack_allocated = 10;
  46   retval->stack = xmalloc (retval->stack_allocated * sizeof (CORE_ADDR));
  47   retval->num_pieces = 0;
  48   retval->pieces = 0;
  49   return retval;
  50 }
  51
  52 /* Release the memory allocated to CTX.  */
  53
  54 void
  55 free_dwarf_expr_context (struct dwarf_expr_context *ctx)
  56 {
  57   xfree (ctx->stack);
  58   xfree (ctx->pieces);
  59   xfree (ctx);
  60 }
  61
  62 /* Expand the memory allocated to CTX's stack to contain at least
  63    NEED more elements than are currently used.  */
  64
  65 static void
  66 dwarf_expr_grow_stack (struct dwarf_expr_context *ctx, size_t need)
  67 {
  68   if (ctx->stack_len + need > ctx->stack_allocated)
  69     {
  70       size_t newlen = ctx->stack_len + need + 10;
  71       ctx->stack = xrealloc (ctx->stack,
  72                              newlen * sizeof (CORE_ADDR));
  73       ctx->stack_allocated = newlen;
  74     }
  75 }
  76
  77 /* Push VALUE onto CTX's stack.  */
  78
  79 void
  80 dwarf_expr_push (struct dwarf_expr_context *ctx, CORE_ADDR value)
  81 {
  82   dwarf_expr_grow_stack (ctx, 1);
  83   ctx->stack[ctx->stack_len++] = value;
  84 }
  85
  86 /* Pop the top item off of CTX's stack.  */
  87
  88 void
  89 dwarf_expr_pop (struct dwarf_expr_context *ctx)
  90 {
  91   if (ctx->stack_len <= 0)
  92     error (_("dwarf expression stack underflow"));
  93   ctx->stack_len--;
  94 }
  95
  96 /* Retrieve the N'th item on CTX's stack.  */
  97
  98 CORE_ADDR
  99 dwarf_expr_fetch (struct dwarf_expr_context *ctx, int n)
 100 {
 101   if (ctx->stack_len <= n)
 102      error (_("Asked for position %d of stack, stack only has %d elements on it."),
 103             n, ctx->stack_len);
 104   return ctx->stack[ctx->stack_len - (1 + n)];
 105
 106 }
 107
 108 /* Add a new piece to CTX's piece list.  */
 109 static void
 110 add_piece (struct dwarf_expr_context *ctx,
 111            int in_reg, CORE_ADDR value, ULONGEST size)
 112 {
 113   struct dwarf_expr_piece *p;
 114
 115   ctx->num_pieces++;
 116
 117   if (ctx->pieces)
 118     ctx->pieces = xrealloc (ctx->pieces,
 119                             (ctx->num_pieces
 120                              * sizeof (struct dwarf_expr_piece)));
 121   else
 122     ctx->pieces = xmalloc (ctx->num_pieces
 123                            * sizeof (struct dwarf_expr_piece));
 124
 125   p = &ctx->pieces[ctx->num_pieces - 1];
 126   p->in_reg = in_reg;
 127   p->value = value;
 128   p->size = size;
 129 }
 130
 131 /* Evaluate the expression at ADDR (LEN bytes long) using the context
 132    CTX.  */
 133
 134 void
 135 dwarf_expr_eval (struct dwarf_expr_context *ctx, gdb_byte *addr, size_t len)
 136 {
 137   execute_stack_op (ctx, addr, addr + len);
 138 }
 139
 140 /* Decode the unsigned LEB128 constant at BUF into the variable pointed to
 141    by R, and return the new value of BUF.  Verify that it doesn't extend
 142    past BUF_END.  */
 143
 144 gdb_byte *
 145 read_uleb128 (gdb_byte *buf, gdb_byte *buf_end, ULONGEST * r)
 146 {
 147   unsigned shift = 0;
 148   ULONGEST result = 0;
 149   gdb_byte byte;
 150
 151   while (1)
 152     {
 153       if (buf >= buf_end)
 154         error (_("read_uleb128: Corrupted DWARF expression."));
 155
 156       byte = *buf++;
 157       result |= (byte & 0x7f) << shift;
 158       if ((byte & 0x80) == 0)
 159         break;
 160       shift += 7;
 161     }
 162   *r = result;
 163   return buf;
 164 }
 165
 166 /* Decode the signed LEB128 constant at BUF into the variable pointed to
 167    by R, and return the new value of BUF.  Verify that it doesn't extend
 168    past BUF_END.  */
 169
 170 gdb_byte *
 171 read_sleb128 (gdb_byte *buf, gdb_byte *buf_end, LONGEST * r)
 172 {
 173   unsigned shift = 0;
 174   LONGEST result = 0;
 175   gdb_byte byte;
 176
 177   while (1)
 178     {
 179       if (buf >= buf_end)
 180         error (_("read_sleb128: Corrupted DWARF expression."));
 181
 182       byte = *buf++;
 183       result |= (byte & 0x7f) << shift;
 184       shift += 7;
 185       if ((byte & 0x80) == 0)
 186         break;
 187     }
 188   if (shift < (sizeof (*r) * 8) && (byte & 0x40) != 0)
 189     result |= -(1 << shift);
 190
 191   *r = result;
 192   return buf;
 193 }
 194
 195 /* Read an address from BUF, and verify that it doesn't extend past
 196    BUF_END.  The address is returned, and *BYTES_READ is set to the
 197    number of bytes read from BUF.  */
 198
 199 CORE_ADDR
 200 dwarf2_read_address (gdb_byte *buf, gdb_byte *buf_end, int *bytes_read)
 201 {
 202   CORE_ADDR result;
 203
 204   if (buf_end - buf < TARGET_ADDR_BIT / TARGET_CHAR_BIT)
 205     error (_("dwarf2_read_address: Corrupted DWARF expression."));
 206
 207   *bytes_read = TARGET_ADDR_BIT / TARGET_CHAR_BIT;
 208   /* NOTE: cagney/2003-05-22: This extract is assuming that a DWARF 2
 209      address is always unsigned.  That may or may not be true.  */
 210   result = extract_unsigned_integer (buf, TARGET_ADDR_BIT / TARGET_CHAR_BIT);
 211   return result;
 212 }
 213
 214 /* Return the type of an address, for unsigned arithmetic.  */
 215
 216 static struct type *
 217 unsigned_address_type (void)
 218 {
 219   switch (TARGET_ADDR_BIT / TARGET_CHAR_BIT)
 220     {
 221     case 2:
 222       return builtin_type_uint16;
 223     case 4:
 224       return builtin_type_uint32;
 225     case 8:
 226       return builtin_type_uint64;
 227     default:
 228       internal_error (__FILE__, __LINE__,
 229                       _("Unsupported address size.\n"));
 230     }
 231 }
 232
 233 /* Return the type of an address, for signed arithmetic.  */
 234
 235 static struct type *
 236 signed_address_type (void)
 237 {
 238   switch (TARGET_ADDR_BIT / TARGET_CHAR_BIT)
 239     {
 240     case 2:
 241       return builtin_type_int16;
 242     case 4:
 243       return builtin_type_int32;
 244     case 8:
 245       return builtin_type_int64;
 246     default:
 247       internal_error (__FILE__, __LINE__,
 248                       _("Unsupported address size.\n"));
 249     }
 250 }
 251 \f
 252 /* The engine for the expression evaluator.  Using the context in CTX,
 253    evaluate the expression between OP_PTR and OP_END.  */
 254
 255 static void
 256 execute_stack_op (struct dwarf_expr_context *ctx,
 257                   gdb_byte *op_ptr, gdb_byte *op_end)
 258 {
 259   ctx->in_reg = 0;
 260
 261   while (op_ptr < op_end)
 262     {
 263       enum dwarf_location_atom op = *op_ptr++;
 264       CORE_ADDR result;
 265       ULONGEST uoffset, reg;
 266       LONGEST offset;
 267       int bytes_read;
 268
 269       switch (op)
 270         {
 271         case DW_OP_lit0:
 272         case DW_OP_lit1:
 273         case DW_OP_lit2:
 274         case DW_OP_lit3:
 275         case DW_OP_lit4:
 276         case DW_OP_lit5:
 277         case DW_OP_lit6:
 278         case DW_OP_lit7:
 279         case DW_OP_lit8:
 280         case DW_OP_lit9:
 281         case DW_OP_lit10:
 282         case DW_OP_lit11:
 283         case DW_OP_lit12:
 284         case DW_OP_lit13:
 285         case DW_OP_lit14:
 286         case DW_OP_lit15:
 287         case DW_OP_lit16:
 288         case DW_OP_lit17:
 289         case DW_OP_lit18:
 290         case DW_OP_lit19:
 291         case DW_OP_lit20:
 292         case DW_OP_lit21:
 293         case DW_OP_lit22:
 294         case DW_OP_lit23:
 295         case DW_OP_lit24:
 296         case DW_OP_lit25:
 297         case DW_OP_lit26:
 298         case DW_OP_lit27:
 299         case DW_OP_lit28:
 300         case DW_OP_lit29:
 301         case DW_OP_lit30:
 302         case DW_OP_lit31:
 303           result = op - DW_OP_lit0;
 304           break;
 305
 306         case DW_OP_addr:
 307           result = dwarf2_read_address (op_ptr, op_end, &bytes_read);
 308           op_ptr += bytes_read;
 309           break;
 310
 311         case DW_OP_const1u:
 312           result = extract_unsigned_integer (op_ptr, 1);
 313           op_ptr += 1;
 314           break;
 315         case DW_OP_const1s:
 316           result = extract_signed_integer (op_ptr, 1);
 317           op_ptr += 1;
 318           break;
 319         case DW_OP_const2u:
 320           result = extract_unsigned_integer (op_ptr, 2);
 321           op_ptr += 2;
 322           break;
 323         case DW_OP_const2s:
 324           result = extract_signed_integer (op_ptr, 2);
 325           op_ptr += 2;
 326           break;
 327         case DW_OP_const4u:
 328           result = extract_unsigned_integer (op_ptr, 4);
 329           op_ptr += 4;
 330           break;
 331         case DW_OP_const4s:
 332           result = extract_signed_integer (op_ptr, 4);
 333           op_ptr += 4;
 334           break;
 335         case DW_OP_const8u:
 336           result = extract_unsigned_integer (op_ptr, 8);
 337           op_ptr += 8;
 338           break;
 339         case DW_OP_const8s:
 340           result = extract_signed_integer (op_ptr, 8);
 341           op_ptr += 8;
 342           break;
 343         case DW_OP_constu:
 344           op_ptr = read_uleb128 (op_ptr, op_end, &uoffset);
 345           result = uoffset;
 346           break;
 347         case DW_OP_consts:
 348           op_ptr = read_sleb128 (op_ptr, op_end, &offset);
 349           result = offset;
 350           break;
 351
 352         /* The DW_OP_reg operations are required to occur alone in
 353            location expressions.  */
 354         case DW_OP_reg0:
 355         case DW_OP_reg1:
 356         case DW_OP_reg2:
 357         case DW_OP_reg3:
 358         case DW_OP_reg4:
 359         case DW_OP_reg5:
 360         case DW_OP_reg6:
 361         case DW_OP_reg7:
 362         case DW_OP_reg8:
 363         case DW_OP_reg9:
 364         case DW_OP_reg10:
 365         case DW_OP_reg11:
 366         case DW_OP_reg12:
 367         case DW_OP_reg13:
 368         case DW_OP_reg14:
 369         case DW_OP_reg15:
 370         case DW_OP_reg16:
 371         case DW_OP_reg17:
 372         case DW_OP_reg18:
 373         case DW_OP_reg19:
 374         case DW_OP_reg20:
 375         case DW_OP_reg21:
 376         case DW_OP_reg22:
 377         case DW_OP_reg23:
 378         case DW_OP_reg24:
 379         case DW_OP_reg25:
 380         case DW_OP_reg26:
 381         case DW_OP_reg27:
 382         case DW_OP_reg28:
 383         case DW_OP_reg29:
 384         case DW_OP_reg30:
 385         case DW_OP_reg31:
 386           if (op_ptr != op_end && *op_ptr != DW_OP_piece)
 387             error (_("DWARF-2 expression error: DW_OP_reg operations must be "
 388                    "used either alone or in conjuction with DW_OP_piece."));
 389
 390           result = op - DW_OP_reg0;
 391           ctx->in_reg = 1;
 392
 393           break;
 394
 395         case DW_OP_regx:
 396           op_ptr = read_uleb128 (op_ptr, op_end, &reg);
 397           if (op_ptr != op_end && *op_ptr != DW_OP_piece)
 398             error (_("DWARF-2 expression error: DW_OP_reg operations must be "
 399                    "used either alone or in conjuction with DW_OP_piece."));
 400
 401           result = reg;
 402           ctx->in_reg = 1;
 403           break;
 404
 405         case DW_OP_breg0:
 406         case DW_OP_breg1:
 407         case DW_OP_breg2:
 408         case DW_OP_breg3:
 409         case DW_OP_breg4:
 410         case DW_OP_breg5:
 411         case DW_OP_breg6:
 412         case DW_OP_breg7:
 413         case DW_OP_breg8:
 414         case DW_OP_breg9:
 415         case DW_OP_breg10:
 416         case DW_OP_breg11:
 417         case DW_OP_breg12:
 418         case DW_OP_breg13:
 419         case DW_OP_breg14:
 420         case DW_OP_breg15:
 421         case DW_OP_breg16:
 422         case DW_OP_breg17:
 423         case DW_OP_breg18:
 424         case DW_OP_breg19:
 425         case DW_OP_breg20:
 426         case DW_OP_breg21:
 427         case DW_OP_breg22:
 428         case DW_OP_breg23:
 429         case DW_OP_breg24:
 430         case DW_OP_breg25:
 431         case DW_OP_breg26:
 432         case DW_OP_breg27:
 433         case DW_OP_breg28:
 434         case DW_OP_breg29:
 435         case DW_OP_breg30:
 436         case DW_OP_breg31:
 437           {
 438             op_ptr = read_sleb128 (op_ptr, op_end, &offset);
 439             result = (ctx->read_reg) (ctx->baton, op - DW_OP_breg0);
 440             result += offset;
 441           }
 442           break;
 443         case DW_OP_bregx:
 444           {
 445             op_ptr = read_uleb128 (op_ptr, op_end, &reg);
 446             op_ptr = read_sleb128 (op_ptr, op_end, &offset);
 447             result = (ctx->read_reg) (ctx->baton, reg);
 448             result += offset;
 449           }
 450           break;
 451         case DW_OP_fbreg:
 452           {
 453             gdb_byte *datastart;
 454             size_t datalen;
 455             unsigned int before_stack_len;
 456
 457             op_ptr = read_sleb128 (op_ptr, op_end, &offset);
 458             /* Rather than create a whole new context, we simply
 459                record the stack length before execution, then reset it
 460                afterwards, effectively erasing whatever the recursive
 461                call put there.  */
 462             before_stack_len = ctx->stack_len;
 463             /* FIXME: cagney/2003-03-26: This code should be using
 464                get_frame_base_address(), and then implement a dwarf2
 465                specific this_base method.  */
 466             (ctx->get_frame_base) (ctx->baton, &datastart, &datalen);
 467             dwarf_expr_eval (ctx, datastart, datalen);
 468             result = dwarf_expr_fetch (ctx, 0);
 469             if (ctx->in_reg)
 470               result = (ctx->read_reg) (ctx->baton, result);
 471             result = result + offset;
 472             ctx->stack_len = before_stack_len;
 473             ctx->in_reg = 0;
 474           }
 475           break;
 476         case DW_OP_dup:
 477           result = dwarf_expr_fetch (ctx, 0);
 478           break;
 479
 480         case DW_OP_drop:
 481           dwarf_expr_pop (ctx);
 482           goto no_push;
 483
 484         case DW_OP_pick:
 485           offset = *op_ptr++;
 486           result = dwarf_expr_fetch (ctx, offset);
 487           break;
 488
 489         case DW_OP_over:
 490           result = dwarf_expr_fetch (ctx, 1);
 491           break;
 492
 493         case DW_OP_rot:
 494           {
 495             CORE_ADDR t1, t2, t3;
 496
 497             if (ctx->stack_len < 3)
 498                error (_("Not enough elements for DW_OP_rot. Need 3, have %d."),
 499                       ctx->stack_len);
 500             t1 = ctx->stack[ctx->stack_len - 1];
 501             t2 = ctx->stack[ctx->stack_len - 2];
 502             t3 = ctx->stack[ctx->stack_len - 3];
 503             ctx->stack[ctx->stack_len - 1] = t2;
 504             ctx->stack[ctx->stack_len - 2] = t3;
 505             ctx->stack[ctx->stack_len - 3] = t1;
 506             goto no_push;
 507           }
 508
 509         case DW_OP_deref:
 510         case DW_OP_deref_size:
 511         case DW_OP_abs:
 512         case DW_OP_neg:
 513         case DW_OP_not:
 514         case DW_OP_plus_uconst:
 515           /* Unary operations.  */
 516           result = dwarf_expr_fetch (ctx, 0);
 517           dwarf_expr_pop (ctx);
 518
 519           switch (op)
 520             {
 521             case DW_OP_deref:
 522               {
 523                 gdb_byte *buf = alloca (TARGET_ADDR_BIT / TARGET_CHAR_BIT);
 524                 int bytes_read;
 525
 526                 (ctx->read_mem) (ctx->baton, buf, result,
 527                                  TARGET_ADDR_BIT / TARGET_CHAR_BIT);
 528                 result = dwarf2_read_address (buf,
 529                                               buf + (TARGET_ADDR_BIT
 530                                                      / TARGET_CHAR_BIT),
 531                                               &bytes_read);
 532               }
 533               break;
 534
 535             case DW_OP_deref_size:
 536               {
 537                 gdb_byte *buf = alloca (TARGET_ADDR_BIT / TARGET_CHAR_BIT);
 538                 int bytes_read;
 539
 540                 (ctx->read_mem) (ctx->baton, buf, result, *op_ptr++);
 541                 result = dwarf2_read_address (buf,
 542                                               buf + (TARGET_ADDR_BIT
 543                                                      / TARGET_CHAR_BIT),
 544                                               &bytes_read);
 545               }
 546               break;
 547
 548             case DW_OP_abs:
 549               if ((signed int) result < 0)
 550                 result = -result;
 551               break;
 552             case DW_OP_neg:
 553               result = -result;
 554               break;
 555             case DW_OP_not:
 556               result = ~result;
 557               break;
 558             case DW_OP_plus_uconst:
 559               op_ptr = read_uleb128 (op_ptr, op_end, &reg);
 560               result += reg;
 561               break;
 562             }
 563           break;
 564
 565         case DW_OP_and:
 566         case DW_OP_div:
 567         case DW_OP_minus:
 568         case DW_OP_mod:
 569         case DW_OP_mul:
 570         case DW_OP_or:
 571         case DW_OP_plus:
 572         case DW_OP_shl:
 573         case DW_OP_shr:
 574         case DW_OP_shra:
 575         case DW_OP_xor:
 576         case DW_OP_le:
 577         case DW_OP_ge:
 578         case DW_OP_eq:
 579         case DW_OP_lt:
 580         case DW_OP_gt:
 581         case DW_OP_ne:
 582           {
 583             /* Binary operations.  Use the value engine to do computations in
 584                the right width.  */
 585             CORE_ADDR first, second;
 586             enum exp_opcode binop;
 587             struct value *val1, *val2;
 588
 589             second = dwarf_expr_fetch (ctx, 0);
 590             dwarf_expr_pop (ctx);
 591
 592             first = dwarf_expr_fetch (ctx, 0);
 593             dwarf_expr_pop (ctx);
 594
 595             val1 = value_from_longest (unsigned_address_type (), first);
 596             val2 = value_from_longest (unsigned_address_type (), second);
 597
 598             switch (op)
 599               {
 600               case DW_OP_and:
 601                 binop = BINOP_BITWISE_AND;
 602                 break;
 603               case DW_OP_div:
 604                 binop = BINOP_DIV;
 605                 break;
 606               case DW_OP_minus:
 607                 binop = BINOP_SUB;
 608                 break;
 609               case DW_OP_mod:
 610                 binop = BINOP_MOD;
 611                 break;
 612               case DW_OP_mul:
 613                 binop = BINOP_MUL;
 614                 break;
 615               case DW_OP_or:
 616                 binop = BINOP_BITWISE_IOR;
 617                 break;
 618               case DW_OP_plus:
 619                 binop = BINOP_ADD;
 620                 break;
 621               case DW_OP_shl:
 622                 binop = BINOP_LSH;
 623                 break;
 624               case DW_OP_shr:
 625                 binop = BINOP_RSH;
 626                 break;
 627               case DW_OP_shra:
 628                 binop = BINOP_RSH;
 629                 val1 = value_from_longest (signed_address_type (), first);
 630                 break;
 631               case DW_OP_xor:
 632                 binop = BINOP_BITWISE_XOR;
 633                 break;
 634               case DW_OP_le:
 635                 binop = BINOP_LEQ;
 636                 break;
 637               case DW_OP_ge:
 638                 binop = BINOP_GEQ;
 639                 break;
 640               case DW_OP_eq:
 641                 binop = BINOP_EQUAL;
 642                 break;
 643               case DW_OP_lt:
 644                 binop = BINOP_LESS;
 645                 break;
 646               case DW_OP_gt:
 647                 binop = BINOP_GTR;
 648                 break;
 649               case DW_OP_ne:
 650                 binop = BINOP_NOTEQUAL;
 651                 break;
 652               default:
 653                 internal_error (__FILE__, __LINE__,
 654                                 _("Can't be reached."));
 655               }
 656             result = value_as_long (value_binop (val1, val2, binop));
 657           }
 658           break;
 659
 660         case DW_OP_GNU_push_tls_address:
 661           /* Variable is at a constant offset in the thread-local
 662           storage block into the objfile for the current thread and
 663           the dynamic linker module containing this expression. Here
 664           we return returns the offset from that base.  The top of the
 665           stack has the offset from the beginning of the thread
 666           control block at which the variable is located.  Nothing
 667           should follow this operator, so the top of stack would be
 668           returned.  */
 669           result = dwarf_expr_fetch (ctx, 0);
 670           dwarf_expr_pop (ctx);
 671           result = (ctx->get_tls_address) (ctx->baton, result);
 672           break;
 673
 674         case DW_OP_skip:
 675           offset = extract_signed_integer (op_ptr, 2);
 676           op_ptr += 2;
 677           op_ptr += offset;
 678           goto no_push;
 679
 680         case DW_OP_bra:
 681           offset = extract_signed_integer (op_ptr, 2);
 682           op_ptr += 2;
 683           if (dwarf_expr_fetch (ctx, 0) != 0)
 684             op_ptr += offset;
 685           dwarf_expr_pop (ctx);
 686           goto no_push;
 687
 688         case DW_OP_nop:
 689           goto no_push;
 690
 691         case DW_OP_piece:
 692           {
 693             ULONGEST size;
 694             CORE_ADDR addr_or_regnum;
 695
 696             /* Record the piece.  */
 697             op_ptr = read_uleb128 (op_ptr, op_end, &size);
 698             addr_or_regnum = dwarf_expr_fetch (ctx, 0);
 699             add_piece (ctx, ctx->in_reg, addr_or_regnum, size);
 700
 701             /* Pop off the address/regnum, and clear the in_reg flag.  */
 702             dwarf_expr_pop (ctx);
 703             ctx->in_reg = 0;
 704           }
 705           goto no_push;
 706
 707         default:
 708           error (_("Unhandled dwarf expression opcode 0x%x"), op);
 709         }
 710
 711       /* Most things push a result value.  */
 712       dwarf_expr_push (ctx, result);
 713     no_push:;
 714     }
 715 }