gdb/compile/compile-c-symbols.c

   1 /* Convert symbols from GDB to GCC
   2
   3    Copyright (C) 2014-2017 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20
  21 #include "defs.h"
  22 #include "compile-internal.h"
  23 #include "symtab.h"
  24 #include "parser-defs.h"
  25 #include "block.h"
  26 #include "objfiles.h"
  27 #include "compile.h"
  28 #include "value.h"
  29 #include "exceptions.h"
  30 #include "gdbtypes.h"
  31 #include "dwarf2loc.h"
  32
  33 \f
  34
  35 /* Object of this type are stored in the compiler's symbol_err_map.  */
  36
  37 struct symbol_error
  38 {
  39   /* The symbol.  */
  40
  41   const struct symbol *sym;
  42
  43   /* The error message to emit.  This is malloc'd and owned by the
  44      hash table.  */
  45
  46   char *message;
  47 };
  48
  49 /* Hash function for struct symbol_error.  */
  50
  51 static hashval_t
  52 hash_symbol_error (const void *a)
  53 {
  54   const struct symbol_error *se = (const struct symbol_error *) a;
  55
  56   return htab_hash_pointer (se->sym);
  57 }
  58
  59 /* Equality function for struct symbol_error.  */
  60
  61 static int
  62 eq_symbol_error (const void *a, const void *b)
  63 {
  64   const struct symbol_error *sea = (const struct symbol_error *) a;
  65   const struct symbol_error *seb = (const struct symbol_error *) b;
  66
  67   return sea->sym == seb->sym;
  68 }
  69
  70 /* Deletion function for struct symbol_error.  */
  71
  72 static void
  73 del_symbol_error (void *a)
  74 {
  75   struct symbol_error *se = (struct symbol_error *) a;
  76
  77   xfree (se->message);
  78   xfree (se);
  79 }
  80
  81 /* Associate SYMBOL with some error text.  */
  82
  83 static void
  84 insert_symbol_error (htab_t hash, const struct symbol *sym, const char *text)
  85 {
  86   struct symbol_error e;
  87   void **slot;
  88
  89   e.sym = sym;
  90   slot = htab_find_slot (hash, &e, INSERT);
  91   if (*slot == NULL)
  92     {
  93       struct symbol_error *e = XNEW (struct symbol_error);
  94
  95       e->sym = sym;
  96       e->message = xstrdup (text);
  97       *slot = e;
  98     }
  99 }
 100
 101 /* Emit the error message corresponding to SYM, if one exists, and
 102    arrange for it not to be emitted again.  */
 103
 104 static void
 105 error_symbol_once (struct compile_c_instance *context,
 106                    const struct symbol *sym)
 107 {
 108   struct symbol_error search;
 109   struct symbol_error *err;
 110
 111   if (context->symbol_err_map == NULL)
 112     return;
 113
 114   search.sym = sym;
 115   err = (struct symbol_error *) htab_find (context->symbol_err_map, &search);
 116   if (err == NULL || err->message == NULL)
 117     return;
 118
 119   gdb::unique_xmalloc_ptr<char> message (err->message);
 120   err->message = NULL;
 121   error (_("%s"), message.get ());
 122 }
 123
 124 \f
 125
 126 /* Compute the name of the pointer representing a local symbol's
 127    address.  */
 128
 129 static gdb::unique_xmalloc_ptr<char>
 130 symbol_substitution_name (struct symbol *sym)
 131 {
 132   return gdb::unique_xmalloc_ptr<char>
 133     (concat ("__", SYMBOL_NATURAL_NAME (sym), "_ptr", (char *) NULL));
 134 }
 135
 136 /* Convert a given symbol, SYM, to the compiler's representation.
 137    CONTEXT is the compiler instance.  IS_GLOBAL is true if the
 138    symbol came from the global scope.  IS_LOCAL is true if the symbol
 139    came from a local scope.  (Note that the two are not strictly
 140    inverses because the symbol might have come from the static
 141    scope.)  */
 142
 143 static void
 144 convert_one_symbol (struct compile_c_instance *context,
 145                     struct block_symbol sym,
 146                     int is_global,
 147                     int is_local)
 148 {
 149   gcc_type sym_type;
 150   const char *filename = symbol_symtab (sym.symbol)->filename;
 151   unsigned short line = SYMBOL_LINE (sym.symbol);
 152
 153   error_symbol_once (context, sym.symbol);
 154
 155   if (SYMBOL_CLASS (sym.symbol) == LOC_LABEL)
 156     sym_type = 0;
 157   else
 158     sym_type = convert_type (context, SYMBOL_TYPE (sym.symbol));
 159
 160   if (SYMBOL_DOMAIN (sym.symbol) == STRUCT_DOMAIN)
 161     {
 162       /* Binding a tag, so we don't need to build a decl.  */
 163       C_CTX (context)->c_ops->tagbind (C_CTX (context),
 164                                        SYMBOL_NATURAL_NAME (sym.symbol),
 165                                        sym_type, filename, line);
 166     }
 167   else
 168     {
 169       gcc_decl decl;
 170       enum gcc_c_symbol_kind kind;
 171       CORE_ADDR addr = 0;
 172       gdb::unique_xmalloc_ptr<char> symbol_name;
 173
 174       switch (SYMBOL_CLASS (sym.symbol))
 175         {
 176         case LOC_TYPEDEF:
 177           kind = GCC_C_SYMBOL_TYPEDEF;
 178           break;
 179
 180         case LOC_LABEL:
 181           kind = GCC_C_SYMBOL_LABEL;
 182           addr = SYMBOL_VALUE_ADDRESS (sym.symbol);
 183           break;
 184
 185         case LOC_BLOCK:
 186           kind = GCC_C_SYMBOL_FUNCTION;
 187           addr = BLOCK_START (SYMBOL_BLOCK_VALUE (sym.symbol));
 188           if (is_global && TYPE_GNU_IFUNC (SYMBOL_TYPE (sym.symbol)))
 189             addr = gnu_ifunc_resolve_addr (target_gdbarch (), addr);
 190           break;
 191
 192         case LOC_CONST:
 193           if (TYPE_CODE (SYMBOL_TYPE (sym.symbol)) == TYPE_CODE_ENUM)
 194             {
 195               /* Already handled by convert_enum.  */
 196               return;
 197             }
 198           C_CTX (context)->c_ops->build_constant
 199             (C_CTX (context),
 200              sym_type, SYMBOL_NATURAL_NAME (sym.symbol),
 201              SYMBOL_VALUE (sym.symbol),
 202              filename, line);
 203           return;
 204
 205         case LOC_CONST_BYTES:
 206           error (_("Unsupported LOC_CONST_BYTES for symbol \"%s\"."),
 207                  SYMBOL_PRINT_NAME (sym.symbol));
 208
 209         case LOC_UNDEF:
 210           internal_error (__FILE__, __LINE__, _("LOC_UNDEF found for \"%s\"."),
 211                           SYMBOL_PRINT_NAME (sym.symbol));
 212
 213         case LOC_COMMON_BLOCK:
 214           error (_("Fortran common block is unsupported for compilation "
 215                    "evaluaton of symbol \"%s\"."),
 216                  SYMBOL_PRINT_NAME (sym.symbol));
 217
 218         case LOC_OPTIMIZED_OUT:
 219           error (_("Symbol \"%s\" cannot be used for compilation evaluation "
 220                    "as it is optimized out."),
 221                  SYMBOL_PRINT_NAME (sym.symbol));
 222
 223         case LOC_COMPUTED:
 224           if (is_local)
 225             goto substitution;
 226           /* Probably TLS here.  */
 227           warning (_("Symbol \"%s\" is thread-local and currently can only "
 228                      "be referenced from the current thread in "
 229                      "compiled code."),
 230                    SYMBOL_PRINT_NAME (sym.symbol));
 231           /* FALLTHROUGH */
 232         case LOC_UNRESOLVED:
 233           /* 'symbol_name' cannot be used here as that one is used only for
 234              local variables from compile_dwarf_expr_to_c.
 235              Global variables can be accessed by GCC only by their address, not
 236              by their name.  */
 237           {
 238             struct value *val;
 239             struct frame_info *frame = NULL;
 240
 241             if (symbol_read_needs_frame (sym.symbol))
 242               {
 243                 frame = get_selected_frame (NULL);
 244                 if (frame == NULL)
 245                   error (_("Symbol \"%s\" cannot be used because "
 246                            "there is no selected frame"),
 247                          SYMBOL_PRINT_NAME (sym.symbol));
 248               }
 249
 250             val = read_var_value (sym.symbol, sym.block, frame);
 251             if (VALUE_LVAL (val) != lval_memory)
 252               error (_("Symbol \"%s\" cannot be used for compilation "
 253                        "evaluation as its address has not been found."),
 254                      SYMBOL_PRINT_NAME (sym.symbol));
 255
 256             kind = GCC_C_SYMBOL_VARIABLE;
 257             addr = value_address (val);
 258           }
 259           break;
 260
 261
 262         case LOC_REGISTER:
 263         case LOC_ARG:
 264         case LOC_REF_ARG:
 265         case LOC_REGPARM_ADDR:
 266         case LOC_LOCAL:
 267         substitution:
 268           kind = GCC_C_SYMBOL_VARIABLE;
 269           symbol_name = symbol_substitution_name (sym.symbol);
 270           break;
 271
 272         case LOC_STATIC:
 273           kind = GCC_C_SYMBOL_VARIABLE;
 274           addr = SYMBOL_VALUE_ADDRESS (sym.symbol);
 275           break;
 276
 277         case LOC_FINAL_VALUE:
 278         default:
 279           gdb_assert_not_reached ("Unreachable case in convert_one_symbol.");
 280
 281         }
 282
 283       /* Don't emit local variable decls for a raw expression.  */
 284       if (context->base.scope != COMPILE_I_RAW_SCOPE
 285           || symbol_name == NULL)
 286         {
 287           decl = C_CTX (context)->c_ops->build_decl
 288             (C_CTX (context),
 289              SYMBOL_NATURAL_NAME (sym.symbol),
 290              kind,
 291              sym_type,
 292              symbol_name.get (), addr,
 293              filename, line);
 294
 295           C_CTX (context)->c_ops->bind (C_CTX (context), decl, is_global);
 296         }
 297     }
 298 }
 299
 300 /* Convert a full symbol to its gcc form.  CONTEXT is the compiler to
 301    use, IDENTIFIER is the name of the symbol, SYM is the symbol
 302    itself, and DOMAIN is the domain which was searched.  */
 303
 304 static void
 305 convert_symbol_sym (struct compile_c_instance *context, const char *identifier,
 306                     struct block_symbol sym, domain_enum domain)
 307 {
 308   const struct block *static_block;
 309   int is_local_symbol;
 310
 311   /* If we found a symbol and it is not in the  static or global
 312      scope, then we should first convert any static or global scope
 313      symbol of the same name.  This lets this unusual case work:
 314
 315      int x; // Global.
 316      int func(void)
 317      {
 318      int x;
 319      // At this spot, evaluate "extern int x; x"
 320      }
 321   */
 322
 323   static_block = block_static_block (sym.block);
 324   /* STATIC_BLOCK is NULL if FOUND_BLOCK is the global block.  */
 325   is_local_symbol = (sym.block != static_block && static_block != NULL);
 326   if (is_local_symbol)
 327     {
 328       struct block_symbol global_sym;
 329
 330       global_sym = lookup_symbol (identifier, NULL, domain, NULL);
 331       /* If the outer symbol is in the static block, we ignore it, as
 332          it cannot be referenced.  */
 333       if (global_sym.symbol != NULL
 334           && global_sym.block != block_static_block (global_sym.block))
 335         {
 336           if (compile_debug)
 337             fprintf_unfiltered (gdb_stdlog,
 338                                 "gcc_convert_symbol \"%s\": global symbol\n",
 339                                 identifier);
 340           convert_one_symbol (context, global_sym, 1, 0);
 341         }
 342     }
 343
 344   if (compile_debug)
 345     fprintf_unfiltered (gdb_stdlog,
 346                         "gcc_convert_symbol \"%s\": local symbol\n",
 347                         identifier);
 348   convert_one_symbol (context, sym, 0, is_local_symbol);
 349 }
 350
 351 /* Convert a minimal symbol to its gcc form.  CONTEXT is the compiler
 352    to use and BMSYM is the minimal symbol to convert.  */
 353
 354 static void
 355 convert_symbol_bmsym (struct compile_c_instance *context,
 356                       struct bound_minimal_symbol bmsym)
 357 {
 358   struct minimal_symbol *msym = bmsym.minsym;
 359   struct objfile *objfile = bmsym.objfile;
 360   struct type *type;
 361   enum gcc_c_symbol_kind kind;
 362   gcc_type sym_type;
 363   gcc_decl decl;
 364   CORE_ADDR addr;
 365
 366   addr = MSYMBOL_VALUE_ADDRESS (objfile, msym);
 367
 368   /* Conversion copied from write_exp_msymbol.  */
 369   switch (MSYMBOL_TYPE (msym))
 370     {
 371     case mst_text:
 372     case mst_file_text:
 373     case mst_solib_trampoline:
 374       type = objfile_type (objfile)->nodebug_text_symbol;
 375       kind = GCC_C_SYMBOL_FUNCTION;
 376       break;
 377
 378     case mst_text_gnu_ifunc:
 379       type = objfile_type (objfile)->nodebug_text_gnu_ifunc_symbol;
 380       kind = GCC_C_SYMBOL_FUNCTION;
 381       addr = gnu_ifunc_resolve_addr (target_gdbarch (), addr);
 382       break;
 383
 384     case mst_data:
 385     case mst_file_data:
 386     case mst_bss:
 387     case mst_file_bss:
 388       type = objfile_type (objfile)->nodebug_data_symbol;
 389       kind = GCC_C_SYMBOL_VARIABLE;
 390       break;
 391
 392     case mst_slot_got_plt:
 393       type = objfile_type (objfile)->nodebug_got_plt_symbol;
 394       kind = GCC_C_SYMBOL_FUNCTION;
 395       break;
 396
 397     default:
 398       type = objfile_type (objfile)->nodebug_unknown_symbol;
 399       kind = GCC_C_SYMBOL_VARIABLE;
 400       break;
 401     }
 402
 403   sym_type = convert_type (context, type);
 404   decl = C_CTX (context)->c_ops->build_decl (C_CTX (context),
 405                                              MSYMBOL_NATURAL_NAME (msym),
 406                                              kind, sym_type, NULL, addr,
 407                                              NULL, 0);
 408   C_CTX (context)->c_ops->bind (C_CTX (context), decl, 1 /* is_global */);
 409 }
 410
 411 /* See compile-internal.h.  */
 412
 413 void
 414 gcc_convert_symbol (void *datum,
 415                     struct gcc_c_context *gcc_context,
 416                     enum gcc_c_oracle_request request,
 417                     const char *identifier)
 418 {
 419   struct compile_c_instance *context = (struct compile_c_instance *) datum;
 420   domain_enum domain;
 421   int found = 0;
 422
 423   switch (request)
 424     {
 425     case GCC_C_ORACLE_SYMBOL:
 426       domain = VAR_DOMAIN;
 427       break;
 428     case GCC_C_ORACLE_TAG:
 429       domain = STRUCT_DOMAIN;
 430       break;
 431     case GCC_C_ORACLE_LABEL:
 432       domain = LABEL_DOMAIN;
 433       break;
 434     default:
 435       gdb_assert_not_reached ("Unrecognized oracle request.");
 436     }
 437
 438   /* We can't allow exceptions to escape out of this callback.  Safest
 439      is to simply emit a gcc error.  */
 440   TRY
 441     {
 442       struct block_symbol sym;
 443
 444       sym = lookup_symbol (identifier, context->base.block, domain, NULL);
 445       if (sym.symbol != NULL)
 446         {
 447           convert_symbol_sym (context, identifier, sym, domain);
 448           found = 1;
 449         }
 450       else if (domain == VAR_DOMAIN)
 451         {
 452           struct bound_minimal_symbol bmsym;
 453
 454           bmsym = lookup_minimal_symbol (identifier, NULL, NULL);
 455           if (bmsym.minsym != NULL)
 456             {
 457               convert_symbol_bmsym (context, bmsym);
 458               found = 1;
 459             }
 460         }
 461     }
 462
 463   CATCH (e, RETURN_MASK_ALL)
 464     {
 465       C_CTX (context)->c_ops->error (C_CTX (context), e.message);
 466     }
 467   END_CATCH
 468
 469   if (compile_debug && !found)
 470     fprintf_unfiltered (gdb_stdlog,
 471                         "gcc_convert_symbol \"%s\": lookup_symbol failed\n",
 472                         identifier);
 473   return;
 474 }
 475
 476 /* See compile-internal.h.  */
 477
 478 gcc_address
 479 gcc_symbol_address (void *datum, struct gcc_c_context *gcc_context,
 480                     const char *identifier)
 481 {
 482   struct compile_c_instance *context = (struct compile_c_instance *) datum;
 483   gcc_address result = 0;
 484   int found = 0;
 485
 486   /* We can't allow exceptions to escape out of this callback.  Safest
 487      is to simply emit a gcc error.  */
 488   TRY
 489     {
 490       struct symbol *sym;
 491
 492       /* We only need global functions here.  */
 493       sym = lookup_symbol (identifier, NULL, VAR_DOMAIN, NULL).symbol;
 494       if (sym != NULL && SYMBOL_CLASS (sym) == LOC_BLOCK)
 495         {
 496           if (compile_debug)
 497             fprintf_unfiltered (gdb_stdlog,
 498                                 "gcc_symbol_address \"%s\": full symbol\n",
 499                                 identifier);
 500           result = BLOCK_START (SYMBOL_BLOCK_VALUE (sym));
 501           if (TYPE_GNU_IFUNC (SYMBOL_TYPE (sym)))
 502             result = gnu_ifunc_resolve_addr (target_gdbarch (), result);
 503           found = 1;
 504         }
 505       else
 506         {
 507           struct bound_minimal_symbol msym;
 508
 509           msym = lookup_bound_minimal_symbol (identifier);
 510           if (msym.minsym != NULL)
 511             {
 512               if (compile_debug)
 513                 fprintf_unfiltered (gdb_stdlog,
 514                                     "gcc_symbol_address \"%s\": minimal "
 515                                     "symbol\n",
 516                                     identifier);
 517               result = BMSYMBOL_VALUE_ADDRESS (msym);
 518               if (MSYMBOL_TYPE (msym.minsym) == mst_text_gnu_ifunc)
 519                 result = gnu_ifunc_resolve_addr (target_gdbarch (), result);
 520               found = 1;
 521             }
 522         }
 523     }
 524
 525   CATCH (e, RETURN_MASK_ERROR)
 526     {
 527       C_CTX (context)->c_ops->error (C_CTX (context), e.message);
 528     }
 529   END_CATCH
 530
 531   if (compile_debug && !found)
 532     fprintf_unfiltered (gdb_stdlog,
 533                         "gcc_symbol_address \"%s\": failed\n",
 534                         identifier);
 535   return result;
 536 }
 537
 538 \f
 539
 540 /* A hash function for symbol names.  */
 541
 542 static hashval_t
 543 hash_symname (const void *a)
 544 {
 545   const struct symbol *sym = (const struct symbol *) a;
 546
 547   return htab_hash_string (SYMBOL_NATURAL_NAME (sym));
 548 }
 549
 550 /* A comparison function for hash tables that just looks at symbol
 551    names.  */
 552
 553 static int
 554 eq_symname (const void *a, const void *b)
 555 {
 556   const struct symbol *syma = (const struct symbol *) a;
 557   const struct symbol *symb = (const struct symbol *) b;
 558
 559   return strcmp (SYMBOL_NATURAL_NAME (syma), SYMBOL_NATURAL_NAME (symb)) == 0;
 560 }
 561
 562 /* If a symbol with the same name as SYM is already in HASHTAB, return
 563    1.  Otherwise, add SYM to HASHTAB and return 0.  */
 564
 565 static int
 566 symbol_seen (htab_t hashtab, struct symbol *sym)
 567 {
 568   void **slot;
 569
 570   slot = htab_find_slot (hashtab, sym, INSERT);
 571   if (*slot != NULL)
 572     return 1;
 573
 574   *slot = sym;
 575   return 0;
 576 }
 577
 578 /* Generate C code to compute the length of a VLA.  */
 579
 580 static void
 581 generate_vla_size (struct compile_c_instance *compiler,
 582                    string_file &stream,
 583                    struct gdbarch *gdbarch,
 584                    unsigned char *registers_used,
 585                    CORE_ADDR pc,
 586                    struct type *type,
 587                    struct symbol *sym)
 588 {
 589   type = check_typedef (type);
 590
 591   if (TYPE_IS_REFERENCE (type))
 592     type = check_typedef (TYPE_TARGET_TYPE (type));
 593
 594   switch (TYPE_CODE (type))
 595     {
 596     case TYPE_CODE_RANGE:
 597       {
 598         if (TYPE_HIGH_BOUND_KIND (type) == PROP_LOCEXPR
 599             || TYPE_HIGH_BOUND_KIND (type) == PROP_LOCLIST)
 600           {
 601             const struct dynamic_prop *prop = &TYPE_RANGE_DATA (type)->high;
 602             std::string name = c_get_range_decl_name (prop);
 603
 604             dwarf2_compile_property_to_c (stream, name.c_str (),
 605                                           gdbarch, registers_used,
 606                                           prop, pc, sym);
 607           }
 608       }
 609       break;
 610
 611     case TYPE_CODE_ARRAY:
 612       generate_vla_size (compiler, stream, gdbarch, registers_used, pc,
 613                          TYPE_INDEX_TYPE (type), sym);
 614       generate_vla_size (compiler, stream, gdbarch, registers_used, pc,
 615                          TYPE_TARGET_TYPE (type), sym);
 616       break;
 617
 618     case TYPE_CODE_UNION:
 619     case TYPE_CODE_STRUCT:
 620       {
 621         int i;
 622
 623         for (i = 0; i < TYPE_NFIELDS (type); ++i)
 624           if (!field_is_static (&TYPE_FIELD (type, i)))
 625             generate_vla_size (compiler, stream, gdbarch, registers_used, pc,
 626                                TYPE_FIELD_TYPE (type, i), sym);
 627       }
 628       break;
 629     }
 630 }
 631
 632 /* Generate C code to compute the address of SYM.  */
 633
 634 static void
 635 generate_c_for_for_one_variable (struct compile_c_instance *compiler,
 636                                  string_file &stream,
 637                                  struct gdbarch *gdbarch,
 638                                  unsigned char *registers_used,
 639                                  CORE_ADDR pc,
 640                                  struct symbol *sym)
 641 {
 642
 643   TRY
 644     {
 645       if (is_dynamic_type (SYMBOL_TYPE (sym)))
 646         {
 647           /* We need to emit to a temporary buffer in case an error
 648              occurs in the middle.  */
 649           string_file local_file;
 650
 651           generate_vla_size (compiler, local_file, gdbarch, registers_used, pc,
 652                              SYMBOL_TYPE (sym), sym);
 653
 654           stream.write (local_file.c_str (), local_file.size ());
 655         }
 656
 657       if (SYMBOL_COMPUTED_OPS (sym) != NULL)
 658         {
 659           gdb::unique_xmalloc_ptr<char> generated_name
 660             = symbol_substitution_name (sym);
 661           /* We need to emit to a temporary buffer in case an error
 662              occurs in the middle.  */
 663           string_file local_file;
 664
 665           SYMBOL_COMPUTED_OPS (sym)->generate_c_location (sym, local_file,
 666                                                           gdbarch,
 667                                                           registers_used,
 668                                                           pc,
 669                                                           generated_name.get ());
 670           stream.write (local_file.c_str (), local_file.size ());
 671         }
 672       else
 673         {
 674           switch (SYMBOL_CLASS (sym))
 675             {
 676             case LOC_REGISTER:
 677             case LOC_ARG:
 678             case LOC_REF_ARG:
 679             case LOC_REGPARM_ADDR:
 680             case LOC_LOCAL:
 681               error (_("Local symbol unhandled when generating C code."));
 682
 683             case LOC_COMPUTED:
 684               gdb_assert_not_reached (_("LOC_COMPUTED variable "
 685                                         "missing a method."));
 686
 687             default:
 688               /* Nothing to do for all other cases, as they don't represent
 689                  local variables.  */
 690               break;
 691             }
 692         }
 693     }
 694
 695   CATCH (e, RETURN_MASK_ERROR)
 696     {
 697       if (compiler->symbol_err_map == NULL)
 698         compiler->symbol_err_map = htab_create_alloc (10,
 699                                                       hash_symbol_error,
 700                                                       eq_symbol_error,
 701                                                       del_symbol_error,
 702                                                       xcalloc,
 703                                                       xfree);
 704       insert_symbol_error (compiler->symbol_err_map, sym, e.message);
 705     }
 706   END_CATCH
 707 }
 708
 709 /* See compile-internal.h.  */
 710
 711 unsigned char *
 712 generate_c_for_variable_locations (struct compile_c_instance *compiler,
 713                                    string_file &stream,
 714                                    struct gdbarch *gdbarch,
 715                                    const struct block *block,
 716                                    CORE_ADDR pc)
 717 {
 718   struct cleanup *outer;
 719   const struct block *static_block = block_static_block (block);
 720   unsigned char *registers_used;
 721
 722   /* If we're already in the static or global block, there is nothing
 723      to write.  */
 724   if (static_block == NULL || block == static_block)
 725     return NULL;
 726
 727   registers_used = XCNEWVEC (unsigned char, gdbarch_num_regs (gdbarch));
 728   outer = make_cleanup (xfree, registers_used);
 729
 730   /* Ensure that a given name is only entered once.  This reflects the
 731      reality of shadowing.  */
 732   htab_up symhash (htab_create_alloc (1, hash_symname, eq_symname, NULL,
 733                                       xcalloc, xfree));
 734
 735   while (1)
 736     {
 737       struct symbol *sym;
 738       struct block_iterator iter;
 739
 740       /* Iterate over symbols in this block, generating code to
 741          compute the location of each local variable.  */
 742       for (sym = block_iterator_first (block, &iter);
 743            sym != NULL;
 744            sym = block_iterator_next (&iter))
 745         {
 746           if (!symbol_seen (symhash.get (), sym))
 747             generate_c_for_for_one_variable (compiler, stream, gdbarch,
 748                                              registers_used, pc, sym);
 749         }
 750
 751       /* If we just finished the outermost block of a function, we're
 752          done.  */
 753       if (BLOCK_FUNCTION (block) != NULL)
 754         break;
 755       block = BLOCK_SUPERBLOCK (block);
 756     }
 757
 758   discard_cleanups (outer);
 759   return registers_used;
 760 }