gdb/dwarf2loc.c

   1 /* DWARF 2 location expression support for GDB.
   2
   3    Copyright 2003, 2005 Free Software Foundation, Inc.
   4
   5    Contributed by Daniel Jacobowitz, MontaVista Software, Inc.
   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 (at
  12    your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful, but
  15    WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17    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., 59 Temple Place - Suite 330,
  22    Boston, MA 02111-1307, USA.  */
  23
  24 #include "defs.h"
  25 #include "ui-out.h"
  26 #include "value.h"
  27 #include "frame.h"
  28 #include "gdbcore.h"
  29 #include "target.h"
  30 #include "inferior.h"
  31 #include "ax.h"
  32 #include "ax-gdb.h"
  33 #include "regcache.h"
  34 #include "objfiles.h"
  35 #include "exceptions.h"
  36
  37 #include "elf/dwarf2.h"
  38 #include "dwarf2expr.h"
  39 #include "dwarf2loc.h"
  40
  41 #include "gdb_string.h"
  42
  43 #ifndef DWARF2_REG_TO_REGNUM
  44 #define DWARF2_REG_TO_REGNUM(REG) (REG)
  45 #endif
  46
  47 /* A helper function for dealing with location lists.  Given a
  48    symbol baton (BATON) and a pc value (PC), find the appropriate
  49    location expression, set *LOCEXPR_LENGTH, and return a pointer
  50    to the beginning of the expression.  Returns NULL on failure.
  51
  52    For now, only return the first matching location expression; there
  53    can be more than one in the list.  */
  54
  55 static gdb_byte *
  56 find_location_expression (struct dwarf2_loclist_baton *baton,
  57                           size_t *locexpr_length, CORE_ADDR pc)
  58 {
  59   CORE_ADDR low, high;
  60   gdb_byte *loc_ptr, *buf_end;
  61   int length;
  62   unsigned int addr_size = TARGET_ADDR_BIT / TARGET_CHAR_BIT;
  63   CORE_ADDR base_mask = ~(~(CORE_ADDR)1 << (addr_size * 8 - 1));
  64   /* Adjust base_address for relocatable objects.  */
  65   CORE_ADDR base_offset = ANOFFSET (baton->objfile->section_offsets,
  66                                     SECT_OFF_TEXT (baton->objfile));
  67   CORE_ADDR base_address = baton->base_address + base_offset;
  68
  69   loc_ptr = baton->data;
  70   buf_end = baton->data + baton->size;
  71
  72   while (1)
  73     {
  74       low = dwarf2_read_address (loc_ptr, buf_end, &length);
  75       loc_ptr += length;
  76       high = dwarf2_read_address (loc_ptr, buf_end, &length);
  77       loc_ptr += length;
  78
  79       /* An end-of-list entry.  */
  80       if (low == 0 && high == 0)
  81         return NULL;
  82
  83       /* A base-address-selection entry.  */
  84       if ((low & base_mask) == base_mask)
  85         {
  86           base_address = high;
  87           continue;
  88         }
  89
  90       /* Otherwise, a location expression entry.  */
  91       low += base_address;
  92       high += base_address;
  93
  94       length = extract_unsigned_integer (loc_ptr, 2);
  95       loc_ptr += 2;
  96
  97       if (pc >= low && pc < high)
  98         {
  99           *locexpr_length = length;
 100           return loc_ptr;
 101         }
 102
 103       loc_ptr += length;
 104     }
 105 }
 106
 107 /* This is the baton used when performing dwarf2 expression
 108    evaluation.  */
 109 struct dwarf_expr_baton
 110 {
 111   struct frame_info *frame;
 112   struct objfile *objfile;
 113 };
 114
 115 /* Helper functions for dwarf2_evaluate_loc_desc.  */
 116
 117 /* Using the frame specified in BATON, read register REGNUM.  The lval
 118    type will be returned in LVALP, and for lval_memory the register
 119    save address will be returned in ADDRP.  */
 120 static CORE_ADDR
 121 dwarf_expr_read_reg (void *baton, int dwarf_regnum)
 122 {
 123   struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton;
 124   CORE_ADDR result, save_addr;
 125   enum lval_type lval_type;
 126   gdb_byte *buf;
 127   int optimized, regnum, realnum, regsize;
 128
 129   regnum = DWARF2_REG_TO_REGNUM (dwarf_regnum);
 130   regsize = register_size (current_gdbarch, regnum);
 131   buf = alloca (regsize);
 132
 133   frame_register (debaton->frame, regnum, &optimized, &lval_type, &save_addr,
 134                   &realnum, buf);
 135   /* NOTE: cagney/2003-05-22: This extract is assuming that a DWARF 2
 136      address is always unsigned.  That may or may not be true.  */
 137   result = extract_unsigned_integer (buf, regsize);
 138
 139   return result;
 140 }
 141
 142 /* Read memory at ADDR (length LEN) into BUF.  */
 143
 144 static void
 145 dwarf_expr_read_mem (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t len)
 146 {
 147   read_memory (addr, buf, len);
 148 }
 149
 150 /* Using the frame specified in BATON, find the location expression
 151    describing the frame base.  Return a pointer to it in START and
 152    its length in LENGTH.  */
 153 static void
 154 dwarf_expr_frame_base (void *baton, gdb_byte **start, size_t * length)
 155 {
 156   /* FIXME: cagney/2003-03-26: This code should be using
 157      get_frame_base_address(), and then implement a dwarf2 specific
 158      this_base method.  */
 159   struct symbol *framefunc;
 160   struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton;
 161
 162   framefunc = get_frame_function (debaton->frame);
 163
 164   if (SYMBOL_OPS (framefunc) == &dwarf2_loclist_funcs)
 165     {
 166       struct dwarf2_loclist_baton *symbaton;
 167       symbaton = SYMBOL_LOCATION_BATON (framefunc);
 168       *start = find_location_expression (symbaton, length,
 169                                          get_frame_pc (debaton->frame));
 170     }
 171   else
 172     {
 173       struct dwarf2_locexpr_baton *symbaton;
 174       symbaton = SYMBOL_LOCATION_BATON (framefunc);
 175       *length = symbaton->size;
 176       *start = symbaton->data;
 177     }
 178
 179   if (*start == NULL)
 180     error (_("Could not find the frame base for \"%s\"."),
 181            SYMBOL_NATURAL_NAME (framefunc));
 182 }
 183
 184 /* Using the objfile specified in BATON, find the address for the
 185    current thread's thread-local storage with offset OFFSET.  */
 186 static CORE_ADDR
 187 dwarf_expr_tls_address (void *baton, CORE_ADDR offset)
 188 {
 189   struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton;
 190   volatile CORE_ADDR addr = 0;
 191
 192   if (target_get_thread_local_address_p ()
 193       && gdbarch_fetch_tls_load_module_address_p (current_gdbarch))
 194     {
 195       ptid_t ptid = inferior_ptid;
 196       struct objfile *objfile = debaton->objfile;
 197       volatile struct gdb_exception ex;
 198
 199       TRY_CATCH (ex, RETURN_MASK_ALL)
 200         {
 201           CORE_ADDR lm_addr;
 202
 203           /* Fetch the load module address for this objfile.  */
 204           lm_addr = gdbarch_fetch_tls_load_module_address (current_gdbarch,
 205                                                            objfile);
 206           /* If it's 0, throw the appropriate exception.  */
 207           if (lm_addr == 0)
 208             throw_error (TLS_LOAD_MODULE_NOT_FOUND_ERROR,
 209                          _("TLS load module not found"));
 210
 211           addr = target_get_thread_local_address (ptid, lm_addr, offset);
 212         }
 213       /* If an error occurred, print TLS related messages here.  Otherwise,
 214          throw the error to some higher catcher.  */
 215       if (ex.reason < 0)
 216         {
 217           int objfile_is_library = (objfile->flags & OBJF_SHARED);
 218
 219           switch (ex.error)
 220             {
 221             case TLS_NO_LIBRARY_SUPPORT_ERROR:
 222               error (_("Cannot find thread-local variables in this thread library."));
 223               break;
 224             case TLS_LOAD_MODULE_NOT_FOUND_ERROR:
 225               if (objfile_is_library)
 226                 error (_("Cannot find shared library `%s' in dynamic"
 227                          " linker's load module list"), objfile->name);
 228               else
 229                 error (_("Cannot find executable file `%s' in dynamic"
 230                          " linker's load module list"), objfile->name);
 231               break;
 232             case TLS_NOT_ALLOCATED_YET_ERROR:
 233               if (objfile_is_library)
 234                 error (_("The inferior has not yet allocated storage for"
 235                          " thread-local variables in\n"
 236                          "the shared library `%s'\n"
 237                          "for %s"),
 238                        objfile->name, target_pid_to_str (ptid));
 239               else
 240                 error (_("The inferior has not yet allocated storage for"
 241                          " thread-local variables in\n"
 242                          "the executable `%s'\n"
 243                          "for %s"),
 244                        objfile->name, target_pid_to_str (ptid));
 245               break;
 246             case TLS_GENERIC_ERROR:
 247               if (objfile_is_library)
 248                 error (_("Cannot find thread-local storage for %s, "
 249                          "shared library %s:\n%s"),
 250                        target_pid_to_str (ptid),
 251                        objfile->name, ex.message);
 252               else
 253                 error (_("Cannot find thread-local storage for %s, "
 254                          "executable file %s:\n%s"),
 255                        target_pid_to_str (ptid),
 256                        objfile->name, ex.message);
 257               break;
 258             default:
 259               throw_exception (ex);
 260               break;
 261             }
 262         }
 263     }
 264   /* It wouldn't be wrong here to try a gdbarch method, too; finding
 265      TLS is an ABI-specific thing.  But we don't do that yet.  */
 266   else
 267     error (_("Cannot find thread-local variables on this target"));
 268
 269   return addr;
 270 }
 271
 272 /* Evaluate a location description, starting at DATA and with length
 273    SIZE, to find the current location of variable VAR in the context
 274    of FRAME.  */
 275 static struct value *
 276 dwarf2_evaluate_loc_desc (struct symbol *var, struct frame_info *frame,
 277                           gdb_byte *data, unsigned short size,
 278                           struct objfile *objfile)
 279 {
 280   struct gdbarch *arch = get_frame_arch (frame);
 281   struct value *retval;
 282   struct dwarf_expr_baton baton;
 283   struct dwarf_expr_context *ctx;
 284
 285   if (size == 0)
 286     {
 287       retval = allocate_value (SYMBOL_TYPE (var));
 288       VALUE_LVAL (retval) = not_lval;
 289       set_value_optimized_out (retval, 1);
 290     }
 291
 292   baton.frame = frame;
 293   baton.objfile = objfile;
 294
 295   ctx = new_dwarf_expr_context ();
 296   ctx->baton = &baton;
 297   ctx->read_reg = dwarf_expr_read_reg;
 298   ctx->read_mem = dwarf_expr_read_mem;
 299   ctx->get_frame_base = dwarf_expr_frame_base;
 300   ctx->get_tls_address = dwarf_expr_tls_address;
 301
 302   dwarf_expr_eval (ctx, data, size);
 303   if (ctx->num_pieces > 0)
 304     {
 305       /* We haven't implemented splicing together pieces from
 306          arbitrary sources yet.  */
 307       error (_("The value of variable '%s' is distributed across several\n"
 308              "locations, and GDB cannot access its value.\n"),
 309              SYMBOL_NATURAL_NAME (var));
 310     }
 311   else if (ctx->in_reg)
 312     {
 313       CORE_ADDR dwarf_regnum = dwarf_expr_fetch (ctx, 0);
 314       int gdb_regnum = DWARF2_REG_TO_REGNUM (dwarf_regnum);
 315       retval = value_from_register (SYMBOL_TYPE (var), gdb_regnum, frame);
 316     }
 317   else
 318     {
 319       CORE_ADDR address = dwarf_expr_fetch (ctx, 0);
 320
 321       retval = allocate_value (SYMBOL_TYPE (var));
 322       VALUE_LVAL (retval) = lval_memory;
 323       set_value_lazy (retval, 1);
 324       VALUE_ADDRESS (retval) = address;
 325     }
 326
 327   free_dwarf_expr_context (ctx);
 328
 329   return retval;
 330 }
 331
 332
 333
 334
 335 \f
 336 /* Helper functions and baton for dwarf2_loc_desc_needs_frame.  */
 337
 338 struct needs_frame_baton
 339 {
 340   int needs_frame;
 341 };
 342
 343 /* Reads from registers do require a frame.  */
 344 static CORE_ADDR
 345 needs_frame_read_reg (void *baton, int regnum)
 346 {
 347   struct needs_frame_baton *nf_baton = baton;
 348   nf_baton->needs_frame = 1;
 349   return 1;
 350 }
 351
 352 /* Reads from memory do not require a frame.  */
 353 static void
 354 needs_frame_read_mem (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t len)
 355 {
 356   memset (buf, 0, len);
 357 }
 358
 359 /* Frame-relative accesses do require a frame.  */
 360 static void
 361 needs_frame_frame_base (void *baton, gdb_byte **start, size_t * length)
 362 {
 363   static gdb_byte lit0 = DW_OP_lit0;
 364   struct needs_frame_baton *nf_baton = baton;
 365
 366   *start = &lit0;
 367   *length = 1;
 368
 369   nf_baton->needs_frame = 1;
 370 }
 371
 372 /* Thread-local accesses do require a frame.  */
 373 static CORE_ADDR
 374 needs_frame_tls_address (void *baton, CORE_ADDR offset)
 375 {
 376   struct needs_frame_baton *nf_baton = baton;
 377   nf_baton->needs_frame = 1;
 378   return 1;
 379 }
 380
 381 /* Return non-zero iff the location expression at DATA (length SIZE)
 382    requires a frame to evaluate.  */
 383
 384 static int
 385 dwarf2_loc_desc_needs_frame (gdb_byte *data, unsigned short size)
 386 {
 387   struct needs_frame_baton baton;
 388   struct dwarf_expr_context *ctx;
 389   int in_reg;
 390
 391   baton.needs_frame = 0;
 392
 393   ctx = new_dwarf_expr_context ();
 394   ctx->baton = &baton;
 395   ctx->read_reg = needs_frame_read_reg;
 396   ctx->read_mem = needs_frame_read_mem;
 397   ctx->get_frame_base = needs_frame_frame_base;
 398   ctx->get_tls_address = needs_frame_tls_address;
 399
 400   dwarf_expr_eval (ctx, data, size);
 401
 402   in_reg = ctx->in_reg;
 403
 404   if (ctx->num_pieces > 0)
 405     {
 406       int i;
 407
 408       /* If the location has several pieces, and any of them are in
 409          registers, then we will need a frame to fetch them from.  */
 410       for (i = 0; i < ctx->num_pieces; i++)
 411         if (ctx->pieces[i].in_reg)
 412           in_reg = 1;
 413     }
 414
 415   free_dwarf_expr_context (ctx);
 416
 417   return baton.needs_frame || in_reg;
 418 }
 419
 420 static void
 421 dwarf2_tracepoint_var_ref (struct symbol *symbol, struct agent_expr *ax,
 422                            struct axs_value *value, gdb_byte *data,
 423                            int size)
 424 {
 425   if (size == 0)
 426     error (_("Symbol \"%s\" has been optimized out."),
 427            SYMBOL_PRINT_NAME (symbol));
 428
 429   if (size == 1
 430       && data[0] >= DW_OP_reg0
 431       && data[0] <= DW_OP_reg31)
 432     {
 433       value->kind = axs_lvalue_register;
 434       value->u.reg = data[0] - DW_OP_reg0;
 435     }
 436   else if (data[0] == DW_OP_regx)
 437     {
 438       ULONGEST reg;
 439       read_uleb128 (data + 1, data + size, &reg);
 440       value->kind = axs_lvalue_register;
 441       value->u.reg = reg;
 442     }
 443   else if (data[0] == DW_OP_fbreg)
 444     {
 445       /* And this is worse than just minimal; we should honor the frame base
 446          as above.  */
 447       int frame_reg;
 448       LONGEST frame_offset;
 449       gdb_byte *buf_end;
 450
 451       buf_end = read_sleb128 (data + 1, data + size, &frame_offset);
 452       if (buf_end != data + size)
 453         error (_("Unexpected opcode after DW_OP_fbreg for symbol \"%s\"."),
 454                SYMBOL_PRINT_NAME (symbol));
 455
 456       TARGET_VIRTUAL_FRAME_POINTER (ax->scope, &frame_reg, &frame_offset);
 457       ax_reg (ax, frame_reg);
 458       ax_const_l (ax, frame_offset);
 459       ax_simple (ax, aop_add);
 460
 461       ax_const_l (ax, frame_offset);
 462       ax_simple (ax, aop_add);
 463       value->kind = axs_lvalue_memory;
 464     }
 465   else
 466     error (_("Unsupported DWARF opcode in the location of \"%s\"."),
 467            SYMBOL_PRINT_NAME (symbol));
 468 }
 469 \f
 470 /* Return the value of SYMBOL in FRAME using the DWARF-2 expression
 471    evaluator to calculate the location.  */
 472 static struct value *
 473 locexpr_read_variable (struct symbol *symbol, struct frame_info *frame)
 474 {
 475   struct dwarf2_locexpr_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol);
 476   struct value *val;
 477   val = dwarf2_evaluate_loc_desc (symbol, frame, dlbaton->data, dlbaton->size,
 478                                   dlbaton->objfile);
 479
 480   return val;
 481 }
 482
 483 /* Return non-zero iff we need a frame to evaluate SYMBOL.  */
 484 static int
 485 locexpr_read_needs_frame (struct symbol *symbol)
 486 {
 487   struct dwarf2_locexpr_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol);
 488   return dwarf2_loc_desc_needs_frame (dlbaton->data, dlbaton->size);
 489 }
 490
 491 /* Print a natural-language description of SYMBOL to STREAM.  */
 492 static int
 493 locexpr_describe_location (struct symbol *symbol, struct ui_file *stream)
 494 {
 495   /* FIXME: be more extensive.  */
 496   struct dwarf2_locexpr_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol);
 497
 498   if (dlbaton->size == 1
 499       && dlbaton->data[0] >= DW_OP_reg0
 500       && dlbaton->data[0] <= DW_OP_reg31)
 501     {
 502       int regno = DWARF2_REG_TO_REGNUM (dlbaton->data[0] - DW_OP_reg0);
 503       fprintf_filtered (stream,
 504                         "a variable in register %s", REGISTER_NAME (regno));
 505       return 1;
 506     }
 507
 508   /* The location expression for a TLS variable looks like this (on a
 509      64-bit LE machine):
 510
 511      DW_AT_location    : 10 byte block: 3 4 0 0 0 0 0 0 0 e0
 512                         (DW_OP_addr: 4; DW_OP_GNU_push_tls_address)
 513
 514      0x3 is the encoding for DW_OP_addr, which has an operand as long
 515      as the size of an address on the target machine (here is 8
 516      bytes).  0xe0 is the encoding for DW_OP_GNU_push_tls_address.
 517      The operand represents the offset at which the variable is within
 518      the thread local storage.  */
 519
 520   if (dlbaton->size > 1
 521       && dlbaton->data[dlbaton->size - 1] == DW_OP_GNU_push_tls_address)
 522     if (dlbaton->data[0] == DW_OP_addr)
 523       {
 524         int bytes_read;
 525         CORE_ADDR offset = dwarf2_read_address (&dlbaton->data[1],
 526                                                 &dlbaton->data[dlbaton->size - 1],
 527                                                 &bytes_read);
 528         fprintf_filtered (stream,
 529                           "a thread-local variable at offset %s in the "
 530                           "thread-local storage for `%s'",
 531                           paddr_nz (offset), dlbaton->objfile->name);
 532         return 1;
 533       }
 534
 535
 536   fprintf_filtered (stream,
 537                     "a variable with complex or multiple locations (DWARF2)");
 538   return 1;
 539 }
 540
 541
 542 /* Describe the location of SYMBOL as an agent value in VALUE, generating
 543    any necessary bytecode in AX.
 544
 545    NOTE drow/2003-02-26: This function is extremely minimal, because
 546    doing it correctly is extremely complicated and there is no
 547    publicly available stub with tracepoint support for me to test
 548    against.  When there is one this function should be revisited.  */
 549
 550 static void
 551 locexpr_tracepoint_var_ref (struct symbol * symbol, struct agent_expr * ax,
 552                             struct axs_value * value)
 553 {
 554   struct dwarf2_locexpr_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol);
 555
 556   dwarf2_tracepoint_var_ref (symbol, ax, value, dlbaton->data, dlbaton->size);
 557 }
 558
 559 /* The set of location functions used with the DWARF-2 expression
 560    evaluator.  */
 561 const struct symbol_ops dwarf2_locexpr_funcs = {
 562   locexpr_read_variable,
 563   locexpr_read_needs_frame,
 564   locexpr_describe_location,
 565   locexpr_tracepoint_var_ref
 566 };
 567
 568
 569 /* Wrapper functions for location lists.  These generally find
 570    the appropriate location expression and call something above.  */
 571
 572 /* Return the value of SYMBOL in FRAME using the DWARF-2 expression
 573    evaluator to calculate the location.  */
 574 static struct value *
 575 loclist_read_variable (struct symbol *symbol, struct frame_info *frame)
 576 {
 577   struct dwarf2_loclist_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol);
 578   struct value *val;
 579   gdb_byte *data;
 580   size_t size;
 581
 582   data = find_location_expression (dlbaton, &size,
 583                                    frame ? get_frame_pc (frame) : 0);
 584   if (data == NULL)
 585     {
 586       val = allocate_value (SYMBOL_TYPE (symbol));
 587       VALUE_LVAL (val) = not_lval;
 588       set_value_optimized_out (val, 1);
 589     }
 590   else
 591     val = dwarf2_evaluate_loc_desc (symbol, frame, data, size,
 592                                     dlbaton->objfile);
 593
 594   return val;
 595 }
 596
 597 /* Return non-zero iff we need a frame to evaluate SYMBOL.  */
 598 static int
 599 loclist_read_needs_frame (struct symbol *symbol)
 600 {
 601   /* If there's a location list, then assume we need to have a frame
 602      to choose the appropriate location expression.  With tracking of
 603      global variables this is not necessarily true, but such tracking
 604      is disabled in GCC at the moment until we figure out how to
 605      represent it.  */
 606
 607   return 1;
 608 }
 609
 610 /* Print a natural-language description of SYMBOL to STREAM.  */
 611 static int
 612 loclist_describe_location (struct symbol *symbol, struct ui_file *stream)
 613 {
 614   /* FIXME: Could print the entire list of locations.  */
 615   fprintf_filtered (stream, "a variable with multiple locations");
 616   return 1;
 617 }
 618
 619 /* Describe the location of SYMBOL as an agent value in VALUE, generating
 620    any necessary bytecode in AX.  */
 621 static void
 622 loclist_tracepoint_var_ref (struct symbol * symbol, struct agent_expr * ax,
 623                             struct axs_value * value)
 624 {
 625   struct dwarf2_loclist_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol);
 626   gdb_byte *data;
 627   size_t size;
 628
 629   data = find_location_expression (dlbaton, &size, ax->scope);
 630   if (data == NULL)
 631     error (_("Variable \"%s\" is not available."), SYMBOL_NATURAL_NAME (symbol));
 632
 633   dwarf2_tracepoint_var_ref (symbol, ax, value, data, size);
 634 }
 635
 636 /* The set of location functions used with the DWARF-2 expression
 637    evaluator and location lists.  */
 638 const struct symbol_ops dwarf2_loclist_funcs = {
 639   loclist_read_variable,
 640   loclist_read_needs_frame,
 641   loclist_describe_location,
 642   loclist_tracepoint_var_ref
 643 };