gdb/compile/compile-c-support.c

   1 /* C/C++ language support for compilation.
   2
   3    Copyright (C) 2014-2019 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 #include "defs.h"
  21 #include "compile-internal.h"
  22 #include "compile-c.h"
  23 #include "compile-cplus.h"
  24 #include "compile.h"
  25 #include "gdb-dlfcn.h"
  26 #include "c-lang.h"
  27 #include "macrotab.h"
  28 #include "macroscope.h"
  29 #include "regcache.h"
  30 #include "gdbsupport/function-view.h"
  31 #include "gdbsupport/preprocessor.h"
  32 #include "gdbarch.h"
  33
  34 /* See compile-internal.h.  */
  35
  36 const char *
  37 c_get_mode_for_size (int size)
  38 {
  39   const char *mode = NULL;
  40
  41   switch (size)
  42     {
  43     case 1:
  44       mode = "QI";
  45       break;
  46     case 2:
  47       mode = "HI";
  48       break;
  49     case 4:
  50       mode = "SI";
  51       break;
  52     case 8:
  53       mode = "DI";
  54       break;
  55     default:
  56       internal_error (__FILE__, __LINE__, _("Invalid GCC mode size %d."), size);
  57     }
  58
  59   return mode;
  60 }
  61
  62 /* See compile-internal.h.  */
  63
  64 std::string
  65 c_get_range_decl_name (const struct dynamic_prop *prop)
  66 {
  67   return string_printf ("__gdb_prop_%s", host_address_to_string (prop));
  68 }
  69
  70 \f
  71
  72 /* Load the plug-in library FE_LIBCC and return the initialization function
  73    FE_CONTEXT.  */
  74
  75 template <typename FUNCTYPE>
  76 FUNCTYPE *
  77 load_libcompile (const char *fe_libcc, const char *fe_context)
  78 {
  79   FUNCTYPE *func;
  80
  81   /* gdb_dlopen will call error () on an error, so no need to check
  82      value.  */
  83   gdb_dlhandle_up handle = gdb_dlopen (fe_libcc);
  84   func = (FUNCTYPE *) gdb_dlsym (handle, fe_context);
  85
  86   if (func == NULL)
  87     error (_("could not find symbol %s in library %s"), fe_context, fe_libcc);
  88
  89   /* Leave the library open.  */
  90   handle.release ();
  91   return func;
  92 }
  93
  94 /* Return the compile instance associated with the current context.
  95    This function calls the symbol returned from the load_libcompile
  96    function.  FE_LIBCC is the library to load.  BASE_VERSION is the
  97    base compile plug-in version we support.  API_VERSION is the
  98    API version supported.  */
  99
 100 template <typename INSTTYPE, typename FUNCTYPE, typename CTXTYPE,
 101           typename BASE_VERSION_TYPE, typename API_VERSION_TYPE>
 102 compile_instance *
 103 get_compile_context (const char *fe_libcc, const char *fe_context,
 104                      BASE_VERSION_TYPE base_version,
 105                      API_VERSION_TYPE api_version)
 106 {
 107   static FUNCTYPE *func;
 108   static CTXTYPE *context;
 109
 110   if (func == NULL)
 111     {
 112       func = load_libcompile<FUNCTYPE> (fe_libcc, fe_context);
 113       gdb_assert (func != NULL);
 114     }
 115
 116   context = (*func) (base_version, api_version);
 117   if (context == NULL)
 118     error (_("The loaded version of GCC does not support the required version "
 119              "of the API."));
 120
 121   return new INSTTYPE (context);
 122 }
 123
 124 /* A C-language implementation of get_compile_context.  */
 125
 126 compile_instance *
 127 c_get_compile_context ()
 128 {
 129   return get_compile_context
 130     <compile_c_instance, gcc_c_fe_context_function, gcc_c_context,
 131     gcc_base_api_version, gcc_c_api_version>
 132     (STRINGIFY (GCC_C_FE_LIBCC), STRINGIFY (GCC_C_FE_CONTEXT),
 133      GCC_FE_VERSION_0, GCC_C_FE_VERSION_0);
 134 }
 135
 136 /* A C++-language implementation of get_compile_context.  */
 137
 138 compile_instance *
 139 cplus_get_compile_context ()
 140 {
 141   return get_compile_context
 142     <compile_cplus_instance, gcc_cp_fe_context_function, gcc_cp_context,
 143      gcc_base_api_version, gcc_cp_api_version>
 144     (STRINGIFY (GCC_CP_FE_LIBCC), STRINGIFY (GCC_CP_FE_CONTEXT),
 145      GCC_FE_VERSION_0, GCC_CP_FE_VERSION_0);
 146 }
 147
 148 \f
 149
 150 /* Write one macro definition.  */
 151
 152 static void
 153 print_one_macro (const char *name, const struct macro_definition *macro,
 154                  struct macro_source_file *source, int line,
 155                  ui_file *file)
 156 {
 157   /* Don't print command-line defines.  They will be supplied another
 158      way.  */
 159   if (line == 0)
 160     return;
 161
 162   /* None of -Wno-builtin-macro-redefined, #undef first
 163      or plain #define of the same value would avoid a warning.  */
 164   fprintf_filtered (file, "#ifndef %s\n# define %s", name, name);
 165
 166   if (macro->kind == macro_function_like)
 167     {
 168       int i;
 169
 170       fputs_filtered ("(", file);
 171       for (i = 0; i < macro->argc; i++)
 172         {
 173           fputs_filtered (macro->argv[i], file);
 174           if (i + 1 < macro->argc)
 175             fputs_filtered (", ", file);
 176         }
 177       fputs_filtered (")", file);
 178     }
 179
 180   fprintf_filtered (file, " %s\n#endif\n", macro->replacement);
 181 }
 182
 183 /* Write macro definitions at PC to FILE.  */
 184
 185 static void
 186 write_macro_definitions (const struct block *block, CORE_ADDR pc,
 187                          struct ui_file *file)
 188 {
 189   gdb::unique_xmalloc_ptr<struct macro_scope> scope;
 190
 191   if (block != NULL)
 192     scope = sal_macro_scope (find_pc_line (pc, 0));
 193   else
 194     scope = default_macro_scope ();
 195   if (scope == NULL)
 196     scope = user_macro_scope ();
 197
 198   if (scope != NULL && scope->file != NULL && scope->file->table != NULL)
 199     {
 200       macro_for_each_in_scope (scope->file, scope->line,
 201                                [&] (const char *name,
 202                                     const macro_definition *macro,
 203                                     macro_source_file *source,
 204                                     int line)
 205         {
 206           print_one_macro (name, macro, source, line, file);
 207         });
 208     }
 209 }
 210
 211 /* Generate a structure holding all the registers used by the function
 212    we're generating.  */
 213
 214 static void
 215 generate_register_struct (struct ui_file *stream, struct gdbarch *gdbarch,
 216                           const unsigned char *registers_used)
 217 {
 218   int i;
 219   int seen = 0;
 220
 221   fputs_unfiltered ("struct " COMPILE_I_SIMPLE_REGISTER_STRUCT_TAG " {\n",
 222                     stream);
 223
 224   if (registers_used != NULL)
 225     for (i = 0; i < gdbarch_num_regs (gdbarch); ++i)
 226       {
 227         if (registers_used[i])
 228           {
 229             struct type *regtype = check_typedef (register_type (gdbarch, i));
 230             std::string regname = compile_register_name_mangled (gdbarch, i);
 231
 232             seen = 1;
 233
 234             /* You might think we could use type_print here.  However,
 235                target descriptions often use types with names like
 236                "int64_t", which may not be defined in the inferior
 237                (and in any case would not be looked up due to the
 238                #pragma business).  So, we take a much simpler
 239                approach: for pointer- or integer-typed registers, emit
 240                the field in the most direct way; and for other
 241                register types (typically flags or vectors), emit a
 242                maximally-aligned array of the correct size.  */
 243
 244             fputs_unfiltered ("  ", stream);
 245             switch (TYPE_CODE (regtype))
 246               {
 247               case TYPE_CODE_PTR:
 248                 fprintf_filtered (stream, "__gdb_uintptr %s",
 249                                   regname.c_str ());
 250                 break;
 251
 252               case TYPE_CODE_INT:
 253                 {
 254                   const char *mode
 255                     = c_get_mode_for_size (TYPE_LENGTH (regtype));
 256
 257                   if (mode != NULL)
 258                     {
 259                       if (TYPE_UNSIGNED (regtype))
 260                         fputs_unfiltered ("unsigned ", stream);
 261                       fprintf_unfiltered (stream,
 262                                           "int %s"
 263                                           " __attribute__ ((__mode__(__%s__)))",
 264                                           regname.c_str (),
 265                                           mode);
 266                       break;
 267                     }
 268                 }
 269
 270                 /* Fall through.  */
 271
 272               default:
 273                 fprintf_unfiltered (stream,
 274                                     "  unsigned char %s[%s]"
 275                                     " __attribute__((__aligned__("
 276                                     "__BIGGEST_ALIGNMENT__)))",
 277                                     regname.c_str (),
 278                                     pulongest (TYPE_LENGTH (regtype)));
 279               }
 280             fputs_unfiltered (";\n", stream);
 281           }
 282       }
 283
 284   if (!seen)
 285     fputs_unfiltered ("  char " COMPILE_I_SIMPLE_REGISTER_DUMMY ";\n",
 286                       stream);
 287
 288   fputs_unfiltered ("};\n\n", stream);
 289 }
 290
 291 /* C-language policy to emit a push user expression pragma into BUF.  */
 292
 293 struct c_push_user_expression
 294 {
 295   void push_user_expression (struct ui_file *buf)
 296   {
 297     fputs_unfiltered ("#pragma GCC user_expression\n", buf);
 298   }
 299 };
 300
 301 /* C-language policy to emit a pop user expression pragma into BUF.
 302    For C, this is a nop.  */
 303
 304 struct pop_user_expression_nop
 305 {
 306   void pop_user_expression (struct ui_file *buf)
 307   {
 308     /* Nothing to do.  */
 309   }
 310 };
 311
 312 /* C-language policy to construct a code header for a block of code.
 313    Takes a scope TYPE argument which selects the correct header to
 314    insert into BUF.  */
 315
 316 struct c_add_code_header
 317 {
 318   void add_code_header (enum compile_i_scope_types type, struct ui_file *buf)
 319   {
 320     switch (type)
 321       {
 322       case COMPILE_I_SIMPLE_SCOPE:
 323         fputs_unfiltered ("void "
 324                           GCC_FE_WRAPPER_FUNCTION
 325                           " (struct "
 326                           COMPILE_I_SIMPLE_REGISTER_STRUCT_TAG
 327                           " *"
 328                           COMPILE_I_SIMPLE_REGISTER_ARG_NAME
 329                           ") {\n",
 330                           buf);
 331         break;
 332
 333       case COMPILE_I_PRINT_ADDRESS_SCOPE:
 334       case COMPILE_I_PRINT_VALUE_SCOPE:
 335         /* <string.h> is needed for a memcpy call below.  */
 336         fputs_unfiltered ("#include <string.h>\n"
 337                           "void "
 338                           GCC_FE_WRAPPER_FUNCTION
 339                           " (struct "
 340                           COMPILE_I_SIMPLE_REGISTER_STRUCT_TAG
 341                           " *"
 342                           COMPILE_I_SIMPLE_REGISTER_ARG_NAME
 343                           ", "
 344                           COMPILE_I_PRINT_OUT_ARG_TYPE
 345                           " "
 346                           COMPILE_I_PRINT_OUT_ARG
 347                           ") {\n",
 348                           buf);
 349         break;
 350
 351       case COMPILE_I_RAW_SCOPE:
 352         break;
 353
 354       default:
 355         gdb_assert_not_reached (_("Unknown compiler scope reached."));
 356       }
 357   }
 358 };
 359
 360 /* C-language policy to construct a code footer for a block of code.
 361    Takes a scope TYPE which selects the correct footer to insert into BUF.  */
 362
 363 struct c_add_code_footer
 364 {
 365   void add_code_footer (enum compile_i_scope_types type, struct ui_file *buf)
 366   {
 367     switch (type)
 368       {
 369       case COMPILE_I_SIMPLE_SCOPE:
 370       case COMPILE_I_PRINT_ADDRESS_SCOPE:
 371       case COMPILE_I_PRINT_VALUE_SCOPE:
 372         fputs_unfiltered ("}\n", buf);
 373         break;
 374
 375       case COMPILE_I_RAW_SCOPE:
 376         break;
 377
 378       default:
 379         gdb_assert_not_reached (_("Unknown compiler scope reached."));
 380       }
 381   }
 382 };
 383
 384 /* C-language policy to emit the user code snippet INPUT into BUF based on the
 385    scope TYPE.  */
 386
 387 struct c_add_input
 388 {
 389   void add_input (enum compile_i_scope_types type, const char *input,
 390                   struct ui_file *buf)
 391   {
 392     switch (type)
 393       {
 394       case COMPILE_I_PRINT_ADDRESS_SCOPE:
 395       case COMPILE_I_PRINT_VALUE_SCOPE:
 396         fprintf_unfiltered (buf,
 397                             "__auto_type " COMPILE_I_EXPR_VAL " = %s;\n"
 398                             "typeof (%s) *" COMPILE_I_EXPR_PTR_TYPE ";\n"
 399                             "memcpy (" COMPILE_I_PRINT_OUT_ARG ", %s"
 400                             COMPILE_I_EXPR_VAL ",\n"
 401                             "sizeof (*" COMPILE_I_EXPR_PTR_TYPE "));\n"
 402                             , input, input,
 403                             (type == COMPILE_I_PRINT_ADDRESS_SCOPE
 404                              ? "&" : ""));
 405         break;
 406
 407       default:
 408         fputs_unfiltered (input, buf);
 409         break;
 410       }
 411     fputs_unfiltered ("\n", buf);
 412   }
 413 };
 414
 415 /* C++-language policy to emit a push user expression pragma into
 416    BUF.  */
 417
 418 struct cplus_push_user_expression
 419 {
 420   void push_user_expression (struct ui_file *buf)
 421   {
 422     fputs_unfiltered ("#pragma GCC push_user_expression\n", buf);
 423   }
 424 };
 425
 426 /* C++-language policy to emit a pop user expression pragma into BUF.  */
 427
 428 struct cplus_pop_user_expression
 429 {
 430   void pop_user_expression (struct ui_file *buf)
 431   {
 432     fputs_unfiltered ("#pragma GCC pop_user_expression\n", buf);
 433   }
 434 };
 435
 436 /* C++-language policy to construct a code header for a block of code.
 437    Takes a scope TYPE argument which selects the correct header to
 438    insert into BUF.  */
 439
 440 struct cplus_add_code_header
 441 {
 442   void add_code_header (enum compile_i_scope_types type, struct ui_file *buf)
 443   {
 444   switch (type)
 445     {
 446     case COMPILE_I_SIMPLE_SCOPE:
 447       fputs_unfiltered ("void "
 448                         GCC_FE_WRAPPER_FUNCTION
 449                         " (struct "
 450                         COMPILE_I_SIMPLE_REGISTER_STRUCT_TAG
 451                         " *"
 452                         COMPILE_I_SIMPLE_REGISTER_ARG_NAME
 453                         ") {\n",
 454                         buf);
 455       break;
 456
 457     case COMPILE_I_PRINT_ADDRESS_SCOPE:
 458     case COMPILE_I_PRINT_VALUE_SCOPE:
 459       fputs_unfiltered (
 460                         "#include <cstring>\n"
 461                         "#include <bits/move.h>\n"
 462                         "void "
 463                         GCC_FE_WRAPPER_FUNCTION
 464                         " (struct "
 465                         COMPILE_I_SIMPLE_REGISTER_STRUCT_TAG
 466                         " *"
 467                         COMPILE_I_SIMPLE_REGISTER_ARG_NAME
 468                         ", "
 469                         COMPILE_I_PRINT_OUT_ARG_TYPE
 470                         " "
 471                         COMPILE_I_PRINT_OUT_ARG
 472                         ") {\n",
 473                         buf);
 474       break;
 475
 476     case COMPILE_I_RAW_SCOPE:
 477       break;
 478
 479     default:
 480       gdb_assert_not_reached (_("Unknown compiler scope reached."));
 481     }
 482   }
 483 };
 484
 485 /* C++-language policy to emit the user code snippet INPUT into BUF based on
 486    the scope TYPE.  */
 487
 488 struct cplus_add_input
 489 {
 490   void add_input (enum compile_i_scope_types type, const char *input,
 491                   struct ui_file *buf)
 492   {
 493     switch (type)
 494       {
 495       case COMPILE_I_PRINT_VALUE_SCOPE:
 496       case COMPILE_I_PRINT_ADDRESS_SCOPE:
 497         fprintf_unfiltered
 498           (buf,
 499            /* "auto" strips ref- and cv- qualifiers, so we need to also strip
 500               those from COMPILE_I_EXPR_PTR_TYPE.  */
 501            "auto " COMPILE_I_EXPR_VAL " = %s;\n"
 502            "typedef "
 503              "std::add_pointer<std::remove_cv<decltype (%s)>::type>::type "
 504              " __gdb_expr_ptr;\n"
 505            "__gdb_expr_ptr " COMPILE_I_EXPR_PTR_TYPE ";\n"
 506            "std::memcpy (" COMPILE_I_PRINT_OUT_ARG ", %s ("
 507            COMPILE_I_EXPR_VAL "),\n"
 508            "\tsizeof (*" COMPILE_I_EXPR_PTR_TYPE "));\n"
 509            ,input, input,
 510            (type == COMPILE_I_PRINT_ADDRESS_SCOPE
 511             ? "__builtin_addressof" : ""));
 512         break;
 513
 514       default:
 515         fputs_unfiltered (input, buf);
 516         break;
 517       }
 518     fputs_unfiltered ("\n", buf);
 519   }
 520 };
 521
 522 /* A host class representing a compile program.
 523
 524    CompileInstanceType is the type of the compile_instance for the
 525    language.
 526
 527    PushUserExpressionPolicy and PopUserExpressionPolicy are used to
 528    push and pop user expression pragmas to the compile plug-in.
 529
 530    AddCodeHeaderPolicy and AddCodeFooterPolicy are used to add the appropriate
 531    code header and footer, respectively.
 532
 533    AddInputPolicy adds the actual user code.  */
 534
 535 template <class CompileInstanceType, class PushUserExpressionPolicy,
 536           class PopUserExpressionPolicy, class AddCodeHeaderPolicy,
 537           class AddCodeFooterPolicy, class AddInputPolicy>
 538 class compile_program
 539   : private PushUserExpressionPolicy, private PopUserExpressionPolicy,
 540     private AddCodeHeaderPolicy, private AddCodeFooterPolicy,
 541     private AddInputPolicy
 542 {
 543 public:
 544
 545   /* Construct a compile_program using the compiler instance INST
 546      using the architecture given by GDBARCH.  */
 547   compile_program (CompileInstanceType *inst, struct gdbarch *gdbarch)
 548     : m_instance (inst), m_arch (gdbarch)
 549   {
 550   }
 551
 552   /* Take the source code provided by the user with the 'compile'
 553      command and compute the additional wrapping, macro, variable and
 554      register operations needed.  INPUT is the source code derived from
 555      the 'compile' command, EXPR_BLOCK denotes the block relevant contextually
 556      to the inferior when the expression was created, and EXPR_PC
 557      indicates the value of $PC.
 558
 559      Returns the text of the program to compile.  */
 560   std::string compute (const char *input, const struct block *expr_block,
 561                        CORE_ADDR expr_pc)
 562   {
 563     string_file var_stream;
 564     string_file buf;
 565
 566     /* Do not generate local variable information for "raw"
 567        compilations.  In this case we aren't emitting our own function
 568        and the user's code may only refer to globals.  */
 569     if (m_instance->scope () != COMPILE_I_RAW_SCOPE)
 570       {
 571         /* Generate the code to compute variable locations, but do it
 572            before generating the function header, so we can define the
 573            register struct before the function body.  This requires a
 574            temporary stream.  */
 575         gdb::unique_xmalloc_ptr<unsigned char> registers_used
 576           = generate_c_for_variable_locations (m_instance, &var_stream, m_arch,
 577                                                expr_block, expr_pc);
 578
 579         buf.puts ("typedef unsigned int"
 580                   " __attribute__ ((__mode__(__pointer__)))"
 581                   " __gdb_uintptr;\n");
 582         buf.puts ("typedef int"
 583                   " __attribute__ ((__mode__(__pointer__)))"
 584                   " __gdb_intptr;\n");
 585
 586         /* Iterate all log2 sizes in bytes supported by c_get_mode_for_size.  */
 587         for (int i = 0; i < 4; ++i)
 588           {
 589             const char *mode = c_get_mode_for_size (1 << i);
 590
 591             gdb_assert (mode != NULL);
 592             buf.printf ("typedef int"
 593                         " __attribute__ ((__mode__(__%s__)))"
 594                         " __gdb_int_%s;\n",
 595                         mode, mode);
 596           }
 597
 598         generate_register_struct (&buf, m_arch, registers_used.get ());
 599       }
 600
 601     AddCodeHeaderPolicy::add_code_header (m_instance->scope (), &buf);
 602
 603     if (m_instance->scope () == COMPILE_I_SIMPLE_SCOPE
 604         || m_instance->scope () == COMPILE_I_PRINT_ADDRESS_SCOPE
 605         || m_instance->scope () == COMPILE_I_PRINT_VALUE_SCOPE)
 606       {
 607         buf.write (var_stream.c_str (), var_stream.size ());
 608         PushUserExpressionPolicy::push_user_expression (&buf);
 609       }
 610
 611     write_macro_definitions (expr_block, expr_pc, &buf);
 612
 613     /* The user expression has to be in its own scope, so that "extern"
 614        works properly.  Otherwise gcc thinks that the "extern"
 615        declaration is in the same scope as the declaration provided by
 616        gdb.  */
 617     if (m_instance->scope () != COMPILE_I_RAW_SCOPE)
 618       buf.puts ("{\n");
 619
 620     buf.puts ("#line 1 \"gdb command line\"\n");
 621
 622     AddInputPolicy::add_input (m_instance->scope (), input, &buf);
 623
 624     /* For larger user expressions the automatic semicolons may be
 625        confusing.  */
 626     if (strchr (input, '\n') == NULL)
 627       buf.puts (";\n");
 628
 629     if (m_instance->scope () != COMPILE_I_RAW_SCOPE)
 630       buf.puts ("}\n");
 631
 632     if (m_instance->scope () == COMPILE_I_SIMPLE_SCOPE
 633         || m_instance->scope () == COMPILE_I_PRINT_ADDRESS_SCOPE
 634         || m_instance->scope () == COMPILE_I_PRINT_VALUE_SCOPE)
 635       PopUserExpressionPolicy::pop_user_expression (&buf);
 636
 637     AddCodeFooterPolicy::add_code_footer (m_instance->scope (), &buf);
 638     return buf.string ();
 639   }
 640
 641 private:
 642
 643   /* The compile instance to be used for compilation and
 644      type-conversion.  */
 645   CompileInstanceType *m_instance;
 646
 647   /* The architecture to be used.  */
 648   struct gdbarch *m_arch;
 649 };
 650
 651 /* The types used for C and C++ program computations.  */
 652
 653 typedef compile_program<compile_c_instance,
 654                         c_push_user_expression, pop_user_expression_nop,
 655                         c_add_code_header, c_add_code_footer,
 656                         c_add_input> c_compile_program;
 657
 658 typedef compile_program<compile_cplus_instance,
 659                         cplus_push_user_expression, cplus_pop_user_expression,
 660                         cplus_add_code_header, c_add_code_footer,
 661                         cplus_add_input> cplus_compile_program;
 662
 663 /* The la_compute_program method for C.  */
 664
 665 std::string
 666 c_compute_program (compile_instance *inst,
 667                    const char *input,
 668                    struct gdbarch *gdbarch,
 669                    const struct block *expr_block,
 670                    CORE_ADDR expr_pc)
 671 {
 672   compile_c_instance *c_inst = static_cast<compile_c_instance *> (inst);
 673   c_compile_program program (c_inst, gdbarch);
 674
 675   return program.compute (input, expr_block, expr_pc);
 676 }
 677
 678 /* The la_compute_program method for C++.  */
 679
 680 std::string
 681 cplus_compute_program (compile_instance *inst,
 682                        const char *input,
 683                        struct gdbarch *gdbarch,
 684                        const struct block *expr_block,
 685                        CORE_ADDR expr_pc)
 686 {
 687   compile_cplus_instance *cplus_inst
 688     = static_cast<compile_cplus_instance *> (inst);
 689   cplus_compile_program program (cplus_inst, gdbarch);
 690
 691   return program.compute (input, expr_block, expr_pc);
 692 }