gdb/compile/compile-cplus-symbols.c

   1 /* Convert symbols from GDB to GCC
   2
   3    Copyright (C) 2014-2020 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 "compile-cplus.h"
  24 #include "gdbsupport/gdb_assert.h"
  25 #include "symtab.h"
  26 #include "parser-defs.h"
  27 #include "block.h"
  28 #include "objfiles.h"
  29 #include "compile.h"
  30 #include "value.h"
  31 #include "exceptions.h"
  32 #include "gdbtypes.h"
  33 #include "dwarf2/loc.h"
  34 #include "cp-support.h"
  35 #include "gdbcmd.h"
  36 #include "compile-c.h"
  37
  38 /* Convert a given symbol, SYM, to the compiler's representation.
  39    INSTANCE is the compiler instance.  IS_GLOBAL is true if the
  40    symbol came from the global scope.  IS_LOCAL is true if the symbol
  41    came from a local scope.  (Note that the two are not strictly
  42    inverses because the symbol might have come from the static
  43    scope.)  */
  44
  45 static void
  46 convert_one_symbol (compile_cplus_instance *instance,
  47                     struct block_symbol sym, bool is_global, bool is_local)
  48 {
  49   /* Squash compiler warning.  */
  50   gcc_type sym_type = 0;
  51   const char *filename = symbol_symtab (sym.symbol)->filename;
  52   unsigned short line = SYMBOL_LINE (sym.symbol);
  53
  54   instance->error_symbol_once (sym.symbol);
  55
  56   if (SYMBOL_CLASS (sym.symbol) == LOC_LABEL)
  57     sym_type = 0;
  58   else
  59     sym_type = instance->convert_type (SYMBOL_TYPE (sym.symbol));
  60
  61   if (SYMBOL_DOMAIN (sym.symbol) == STRUCT_DOMAIN)
  62     {
  63       /* Nothing to do.  */
  64     }
  65   else
  66     {
  67       /* Squash compiler warning.  */
  68       gcc_cp_symbol_kind_flags kind = GCC_CP_FLAG_BASE;
  69       CORE_ADDR addr = 0;
  70       std::string name;
  71       gdb::unique_xmalloc_ptr<char> symbol_name;
  72
  73       switch (SYMBOL_CLASS (sym.symbol))
  74         {
  75         case LOC_TYPEDEF:
  76           if (SYMBOL_TYPE (sym.symbol)->code () == TYPE_CODE_TYPEDEF)
  77             kind = GCC_CP_SYMBOL_TYPEDEF;
  78           else  if (SYMBOL_TYPE (sym.symbol)->code () == TYPE_CODE_NAMESPACE)
  79             return;
  80           break;
  81
  82         case LOC_LABEL:
  83           kind = GCC_CP_SYMBOL_LABEL;
  84           addr = SYMBOL_VALUE_ADDRESS (sym.symbol);
  85           break;
  86
  87         case LOC_BLOCK:
  88           {
  89             kind = GCC_CP_SYMBOL_FUNCTION;
  90             addr = BLOCK_START (SYMBOL_BLOCK_VALUE (sym.symbol));
  91             if (is_global && TYPE_GNU_IFUNC (SYMBOL_TYPE (sym.symbol)))
  92               addr = gnu_ifunc_resolve_addr (target_gdbarch (), addr);
  93           }
  94           break;
  95
  96         case LOC_CONST:
  97           if (SYMBOL_TYPE (sym.symbol)->code () == TYPE_CODE_ENUM)
  98             {
  99               /* Already handled by convert_enum.  */
 100               return;
 101             }
 102           instance->plugin ().build_constant
 103             (sym_type, sym.symbol->natural_name (),
 104              SYMBOL_VALUE (sym.symbol), filename, line);
 105           return;
 106
 107         case LOC_CONST_BYTES:
 108           error (_("Unsupported LOC_CONST_BYTES for symbol \"%s\"."),
 109                  sym.symbol->print_name ());
 110
 111         case LOC_UNDEF:
 112           internal_error (__FILE__, __LINE__, _("LOC_UNDEF found for \"%s\"."),
 113                           sym.symbol->print_name ());
 114
 115         case LOC_COMMON_BLOCK:
 116           error (_("Fortran common block is unsupported for compilation "
 117                    "evaluaton of symbol \"%s\"."),
 118                  sym.symbol->print_name ());
 119
 120         case LOC_OPTIMIZED_OUT:
 121           error (_("Symbol \"%s\" cannot be used for compilation evaluation "
 122                    "as it is optimized out."),
 123                  sym.symbol->print_name ());
 124
 125         case LOC_COMPUTED:
 126           if (is_local)
 127             goto substitution;
 128           /* Probably TLS here.  */
 129           warning (_("Symbol \"%s\" is thread-local and currently can only "
 130                      "be referenced from the current thread in "
 131                      "compiled code."),
 132                    sym.symbol->print_name ());
 133           /* FALLTHROUGH */
 134         case LOC_UNRESOLVED:
 135           /* 'symbol_name' cannot be used here as that one is used only for
 136              local variables from compile_dwarf_expr_to_c.
 137              Global variables can be accessed by GCC only by their address, not
 138              by their name.  */
 139           {
 140             struct value *val;
 141             struct frame_info *frame = nullptr;
 142
 143             if (symbol_read_needs_frame (sym.symbol))
 144               {
 145                 frame = get_selected_frame (nullptr);
 146                 if (frame == nullptr)
 147                   error (_("Symbol \"%s\" cannot be used because "
 148                            "there is no selected frame"),
 149                          sym.symbol->print_name ());
 150               }
 151
 152             val = read_var_value (sym.symbol, sym.block, frame);
 153             if (VALUE_LVAL (val) != lval_memory)
 154               error (_("Symbol \"%s\" cannot be used for compilation "
 155                        "evaluation as its address has not been found."),
 156                      sym.symbol->print_name ());
 157
 158             kind = GCC_CP_SYMBOL_VARIABLE;
 159             addr = value_address (val);
 160           }
 161           break;
 162
 163
 164         case LOC_REGISTER:
 165         case LOC_ARG:
 166         case LOC_REF_ARG:
 167         case LOC_REGPARM_ADDR:
 168         case LOC_LOCAL:
 169         substitution:
 170           kind = GCC_CP_SYMBOL_VARIABLE;
 171           symbol_name = c_symbol_substitution_name (sym.symbol);
 172           break;
 173
 174         case LOC_STATIC:
 175           kind = GCC_CP_SYMBOL_VARIABLE;
 176           addr = SYMBOL_VALUE_ADDRESS (sym.symbol);
 177           break;
 178
 179         case LOC_FINAL_VALUE:
 180         default:
 181           gdb_assert_not_reached ("Unreachable case in convert_one_symbol.");
 182         }
 183
 184       /* Don't emit local variable decls for a raw expression.  */
 185       if (instance->scope () != COMPILE_I_RAW_SCOPE || symbol_name == nullptr)
 186         {
 187           /* For non-local symbols, create/push a new scope so that the
 188              symbol is properly scoped to the plug-in.  */
 189           if (!is_local)
 190             {
 191               compile_scope scope
 192                 = instance->new_scope (sym.symbol->natural_name (),
 193                                        SYMBOL_TYPE (sym.symbol));
 194               if (scope.nested_type () != GCC_TYPE_NONE)
 195                 {
 196                   /* We found a symbol for this type that was defined inside
 197                      some other symbol, e.g., a class typedef defined.  */
 198                   return;
 199                 }
 200
 201               instance->enter_scope (std::move (scope));
 202             }
 203
 204           /* Get the `raw' name of the symbol.  */
 205           if (name.empty () && sym.symbol->natural_name () != nullptr)
 206             name = compile_cplus_instance::decl_name
 207               (sym.symbol->natural_name ()).get ();
 208
 209           /* Define the decl.  */
 210           instance->plugin ().build_decl
 211             ("variable", name.c_str (), kind, sym_type,
 212              symbol_name.get (), addr, filename, line);
 213
 214           /* Pop scope for non-local symbols.  */
 215           if (!is_local)
 216             instance->leave_scope ();
 217         }
 218     }
 219 }
 220
 221 /* Convert a full symbol to its gcc form.  CONTEXT is the compiler to
 222    use, IDENTIFIER is the name of the symbol, SYM is the symbol
 223    itself, and DOMAIN is the domain which was searched.  */
 224
 225 static void
 226 convert_symbol_sym (compile_cplus_instance *instance,
 227                     const char *identifier, struct block_symbol sym,
 228                     domain_enum domain)
 229 {
 230   /* If we found a symbol and it is not in the  static or global
 231      scope, then we should first convert any static or global scope
 232      symbol of the same name.  This lets this unusual case work:
 233
 234      int x; // Global.
 235      int func(void)
 236      {
 237      int x;
 238      // At this spot, evaluate "extern int x; x"
 239      }
 240   */
 241
 242   const struct block *static_block = block_static_block (sym.block);
 243   /* STATIC_BLOCK is NULL if FOUND_BLOCK is the global block.  */
 244   bool is_local_symbol = (sym.block != static_block && static_block != nullptr);
 245   if (is_local_symbol)
 246     {
 247       struct block_symbol global_sym;
 248
 249       global_sym = lookup_symbol (identifier, nullptr, domain, nullptr);
 250       /* If the outer symbol is in the static block, we ignore it, as
 251          it cannot be referenced.  */
 252       if (global_sym.symbol != nullptr
 253           && global_sym.block != block_static_block (global_sym.block))
 254         {
 255           if (compile_debug)
 256             fprintf_unfiltered (gdb_stdlog,
 257                                 "gcc_convert_symbol \"%s\": global symbol\n",
 258                                 identifier);
 259           convert_one_symbol (instance, global_sym, true, false);
 260         }
 261     }
 262
 263   if (compile_debug)
 264     fprintf_unfiltered (gdb_stdlog,
 265                         "gcc_convert_symbol \"%s\": local symbol\n",
 266                         identifier);
 267   convert_one_symbol (instance, sym, false, is_local_symbol);
 268 }
 269
 270 /* Convert a minimal symbol to its gcc form.  CONTEXT is the compiler
 271    to use and BMSYM is the minimal symbol to convert.  */
 272
 273 static void
 274 convert_symbol_bmsym (compile_cplus_instance *instance,
 275                       struct bound_minimal_symbol bmsym)
 276 {
 277   struct minimal_symbol *msym = bmsym.minsym;
 278   struct objfile *objfile = bmsym.objfile;
 279   struct type *type;
 280   gcc_cp_symbol_kind_flags kind;
 281   gcc_type sym_type;
 282   CORE_ADDR addr;
 283
 284   addr = MSYMBOL_VALUE_ADDRESS (objfile, msym);
 285
 286   /* Conversion copied from write_exp_msymbol.  */
 287   switch (MSYMBOL_TYPE (msym))
 288     {
 289     case mst_text:
 290     case mst_file_text:
 291     case mst_solib_trampoline:
 292       type = objfile_type (objfile)->nodebug_text_symbol;
 293       kind = GCC_CP_SYMBOL_FUNCTION;
 294       break;
 295
 296     case mst_text_gnu_ifunc:
 297       /* nodebug_text_gnu_ifunc_symbol would cause:
 298          function return type cannot be function  */
 299       type = objfile_type (objfile)->nodebug_text_symbol;
 300       kind = GCC_CP_SYMBOL_FUNCTION;
 301       addr = gnu_ifunc_resolve_addr (target_gdbarch (), addr);
 302       break;
 303
 304     case mst_data:
 305     case mst_file_data:
 306     case mst_bss:
 307     case mst_file_bss:
 308       type = objfile_type (objfile)->nodebug_data_symbol;
 309       kind = GCC_CP_SYMBOL_VARIABLE;
 310       break;
 311
 312     case mst_slot_got_plt:
 313       type = objfile_type (objfile)->nodebug_got_plt_symbol;
 314       kind = GCC_CP_SYMBOL_FUNCTION;
 315       break;
 316
 317     default:
 318       type = objfile_type (objfile)->nodebug_unknown_symbol;
 319       kind = GCC_CP_SYMBOL_VARIABLE;
 320       break;
 321     }
 322
 323   sym_type = instance->convert_type (type);
 324   instance->plugin ().push_namespace ("");
 325   instance->plugin ().build_decl
 326     ("minsym", msym->natural_name (), kind, sym_type, nullptr, addr,
 327      nullptr, 0);
 328   instance->plugin ().pop_binding_level ("");
 329 }
 330
 331 /* See compile-cplus.h.  */
 332
 333 void
 334 gcc_cplus_convert_symbol (void *datum,
 335                           struct gcc_cp_context *gcc_context,
 336                           enum gcc_cp_oracle_request request,
 337                           const char *identifier)
 338 {
 339   if (compile_debug)
 340     fprintf_unfiltered (gdb_stdlog,
 341                         "got oracle request for \"%s\"\n", identifier);
 342
 343   bool found = false;
 344   compile_cplus_instance *instance = (compile_cplus_instance *) datum;
 345
 346   try
 347     {
 348       /* Symbol searching is a three part process unfortunately.  */
 349
 350       /* First do a "standard" lookup, converting any found symbols.
 351          This will find variables in the current scope.  */
 352
 353       struct block_symbol sym
 354         = lookup_symbol (identifier, instance->block (), VAR_DOMAIN, nullptr);
 355
 356       if (sym.symbol != nullptr)
 357         {
 358           found = true;
 359           convert_symbol_sym (instance, identifier, sym, VAR_DOMAIN);
 360         }
 361
 362       /* Then use linespec.c's multi-symbol search.  This should find
 363          all non-variable symbols for which we have debug info.  */
 364
 365       symbol_searcher searcher;
 366       searcher.find_all_symbols (identifier, current_language,
 367                                  ALL_DOMAIN, nullptr, nullptr);
 368
 369       /* Convert any found symbols.  */
 370       for (const auto &it : searcher.matching_symbols ())
 371         {
 372           /* Don't convert the symbol found above, if any, twice!  */
 373           if (it.symbol != sym.symbol)
 374             {
 375               found = true;
 376               convert_symbol_sym (instance, identifier, it,
 377                                   SYMBOL_DOMAIN (it.symbol));
 378             }
 379         }
 380
 381       /* Finally, if no symbols have been found, fall back to minsyms.  */
 382       if (!found)
 383         {
 384           for (const auto &it : searcher.matching_msymbols ())
 385             {
 386               found = true;
 387               convert_symbol_bmsym (instance, it);
 388             }
 389         }
 390     }
 391   catch (const gdb_exception &e)
 392     {
 393       /* We can't allow exceptions to escape out of this callback.  Safest
 394          is to simply emit a gcc error.  */
 395       instance->plugin ().error (e.what ());
 396     }
 397
 398   if (compile_debug && !found)
 399     fprintf_unfiltered (gdb_stdlog,
 400                         "gcc_convert_symbol \"%s\": lookup_symbol failed\n",
 401                         identifier);
 402
 403   if (compile_debug)
 404     {
 405       if (found)
 406         fprintf_unfiltered (gdb_stdlog, "found type for %s\n", identifier);
 407       else
 408         {
 409           fprintf_unfiltered (gdb_stdlog, "did not find type for %s\n",
 410                               identifier);
 411         }
 412     }
 413
 414   return;
 415 }
 416
 417 /* See compile-cplus.h.  */
 418
 419 gcc_address
 420 gcc_cplus_symbol_address (void *datum, struct gcc_cp_context *gcc_context,
 421                           const char *identifier)
 422 {
 423   compile_cplus_instance *instance = (compile_cplus_instance *) datum;
 424   gcc_address result = 0;
 425   int found = 0;
 426
 427   if (compile_debug)
 428     fprintf_unfiltered (gdb_stdlog,
 429                         "got oracle request for address of %s\n", identifier);
 430
 431   /* We can't allow exceptions to escape out of this callback.  Safest
 432      is to simply emit a gcc error.  */
 433   try
 434     {
 435       struct symbol *sym
 436         = lookup_symbol (identifier, nullptr, VAR_DOMAIN, nullptr).symbol;
 437
 438       if (sym != nullptr && SYMBOL_CLASS (sym) == LOC_BLOCK)
 439         {
 440           if (compile_debug)
 441             fprintf_unfiltered (gdb_stdlog,
 442                                 "gcc_symbol_address \"%s\": full symbol\n",
 443                                 identifier);
 444           result = BLOCK_START (SYMBOL_BLOCK_VALUE (sym));
 445           if (TYPE_GNU_IFUNC (SYMBOL_TYPE (sym)))
 446             result = gnu_ifunc_resolve_addr (target_gdbarch (), result);
 447           found = 1;
 448         }
 449       else
 450         {
 451           struct bound_minimal_symbol msym;
 452
 453           msym = lookup_bound_minimal_symbol (identifier);
 454           if (msym.minsym != nullptr)
 455             {
 456               if (compile_debug)
 457                 fprintf_unfiltered (gdb_stdlog,
 458                                     "gcc_symbol_address \"%s\": minimal "
 459                                     "symbol\n",
 460                                     identifier);
 461               result = BMSYMBOL_VALUE_ADDRESS (msym);
 462               if (MSYMBOL_TYPE (msym.minsym) == mst_text_gnu_ifunc)
 463                 result = gnu_ifunc_resolve_addr (target_gdbarch (), result);
 464               found = 1;
 465             }
 466         }
 467     }
 468
 469   catch (const gdb_exception_error &e)
 470     {
 471       instance->plugin ().error (e.what ());
 472     }
 473
 474   if (compile_debug && !found)
 475     fprintf_unfiltered (gdb_stdlog,
 476                         "gcc_symbol_address \"%s\": failed\n",
 477                         identifier);
 478
 479   if (compile_debug)
 480     {
 481       if (found)
 482         fprintf_unfiltered (gdb_stdlog, "found address for %s!\n", identifier);
 483       else
 484         fprintf_unfiltered (gdb_stdlog,
 485                             "did not find address for %s\n", identifier);
 486     }
 487
 488   return result;
 489 }