expression.c

   1 /*
   2  * sparse/expression.c
   3  *
   4  * Copyright (C) 2003 Transmeta Corp.
   5  *               2003-2004 Linus Torvalds
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a copy
   8  * of this software and associated documentation files (the "Software"), to deal
   9  * in the Software without restriction, including without limitation the rights
  10  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  11  * copies of the Software, and to permit persons to whom the Software is
  12  * furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be included in
  15  * all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  20  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  23  * THE SOFTWARE.
  24  *
  25  * This is the expression parsing part of parsing C.
  26  */
  27 #include <stdarg.h>
  28 #include <stdlib.h>
  29 #include <stdio.h>
  30 #include <string.h>
  31 #include <ctype.h>
  32 #include <unistd.h>
  33 #include <fcntl.h>
  34 #include <errno.h>
  35 #include <limits.h>
  36
  37 #include "lib.h"
  38 #include "allocate.h"
  39 #include "token.h"
  40 #include "parse.h"
  41 #include "symbol.h"
  42 #include "scope.h"
  43 #include "expression.h"
  44 #include "target.h"
  45 #include "char.h"
  46
  47 static int match_oplist(int op, ...)
  48 {
  49         va_list args;
  50         int nextop;
  51
  52         va_start(args, op);
  53         do {
  54                 nextop = va_arg(args, int);
  55         } while (nextop != 0 && nextop != op);
  56         va_end(args);
  57
  58         return nextop != 0;
  59 }
  60
  61 static struct token *comma_expression(struct token *, struct expression **);
  62
  63 struct token *parens_expression(struct token *token, struct expression **expr, const char *where)
  64 {
  65         token = expect(token, '(', where);
  66         if (match_op(token, '{')) {
  67                 struct expression *e = alloc_expression(token->pos, EXPR_STATEMENT);
  68                 struct statement *stmt = alloc_statement(token->pos, STMT_COMPOUND);
  69                 *expr = e;
  70                 e->statement = stmt;
  71                 start_symbol_scope(e->pos);
  72                 token = compound_statement(token->next, stmt);
  73                 end_symbol_scope();
  74                 token = expect(token, '}', "at end of statement expression");
  75         } else
  76                 token = parse_expression(token, expr);
  77         return expect(token, ')', where);
  78 }
  79
  80 /*
  81  * Handle __func__, __FUNCTION__ and __PRETTY_FUNCTION__ token
  82  * conversion
  83  */
  84 static struct symbol *handle_func(struct token *token)
  85 {
  86         struct ident *ident = token->ident;
  87         struct symbol *decl, *array;
  88         struct string *string;
  89         int len;
  90
  91         if (ident != &__func___ident &&
  92             ident != &__FUNCTION___ident &&
  93             ident != &__PRETTY_FUNCTION___ident)
  94                 return NULL;
  95
  96         if (!current_fn || !current_fn->ident)
  97                 return NULL;
  98
  99         /* OK, it's one of ours */
 100         array = alloc_symbol(token->pos, SYM_ARRAY);
 101         array->ctype.base_type = &char_ctype;
 102         array->ctype.alignment = 1;
 103         array->endpos = token->pos;
 104         decl = alloc_symbol(token->pos, SYM_NODE);
 105         decl->ctype.base_type = array;
 106         decl->ctype.alignment = 1;
 107         decl->ctype.modifiers = MOD_STATIC;
 108         decl->endpos = token->pos;
 109
 110         /* function-scope, but in NS_SYMBOL */
 111         bind_symbol(decl, ident, NS_LABEL);
 112         decl->namespace = NS_SYMBOL;
 113
 114         len = current_fn->ident->len;
 115         string = __alloc_string(len + 1);
 116         memcpy(string->data, current_fn->ident->name, len);
 117         string->data[len] = 0;
 118         string->length = len + 1;
 119
 120         decl->initializer = alloc_expression(token->pos, EXPR_STRING);
 121         decl->initializer->string = string;
 122         decl->initializer->ctype = decl;
 123         decl->array_size = alloc_const_expression(token->pos, len + 1);
 124         array->array_size = decl->array_size;
 125         decl->bit_size = array->bit_size = bytes_to_bits(len + 1);
 126
 127         return decl;
 128 }
 129
 130 static struct token *parse_type(struct token *token, struct expression **tree)
 131 {
 132         struct symbol *sym;
 133         *tree = alloc_expression(token->pos, EXPR_TYPE);
 134         token = typename(token, &sym, NULL);
 135         if (sym->ident)
 136                 sparse_error(token->pos,
 137                              "type expression should not include identifier "
 138                              "\"%s\"", sym->ident->name);
 139         (*tree)->symbol = sym;
 140         return token;
 141 }
 142
 143 static struct token *builtin_types_compatible_p_expr(struct token *token,
 144                                                      struct expression **tree)
 145 {
 146         struct expression *expr = alloc_expression(
 147                 token->pos, EXPR_COMPARE);
 148         expr->op = SPECIAL_EQUAL;
 149         token = token->next;
 150         if (!match_op(token, '('))
 151                 return expect(token, '(',
 152                               "after __builtin_types_compatible_p");
 153         token = token->next;
 154         token = parse_type(token, &expr->left);
 155         if (!match_op(token, ','))
 156                 return expect(token, ',',
 157                               "in __builtin_types_compatible_p");
 158         token = token->next;
 159         token = parse_type(token, &expr->right);
 160         if (!match_op(token, ')'))
 161                 return expect(token, ')',
 162                               "at end of __builtin_types_compatible_p");
 163         token = token->next;
 164
 165         *tree = expr;
 166         return token;
 167 }
 168
 169 static struct token *builtin_offsetof_expr(struct token *token,
 170                                            struct expression **tree)
 171 {
 172         struct expression *expr = NULL;
 173         struct expression **p = &expr;
 174         struct symbol *sym;
 175         int op = '.';
 176
 177         token = token->next;
 178         if (!match_op(token, '('))
 179                 return expect(token, '(', "after __builtin_offset");
 180
 181         token = token->next;
 182         token = typename(token, &sym, NULL);
 183         if (sym->ident)
 184                 sparse_error(token->pos,
 185                              "type expression should not include identifier "
 186                              "\"%s\"", sym->ident->name);
 187
 188         if (!match_op(token, ','))
 189                 return expect(token, ',', "in __builtin_offset");
 190
 191         while (1) {
 192                 struct expression *e;
 193                 switch (op) {
 194                 case ')':
 195                         expr->in = sym;
 196                         *tree = expr;
 197                 default:
 198                         return expect(token, ')', "at end of __builtin_offset");
 199                 case SPECIAL_DEREFERENCE:
 200                         e = alloc_expression(token->pos, EXPR_OFFSETOF);
 201                         e->op = '[';
 202                         *p = e;
 203                         p = &e->down;
 204                         /* fall through */
 205                 case '.':
 206                         token = token->next;
 207                         e = alloc_expression(token->pos, EXPR_OFFSETOF);
 208                         e->op = '.';
 209                         if (token_type(token) != TOKEN_IDENT) {
 210                                 sparse_error(token->pos, "Expected member name");
 211                                 return token;
 212                         }
 213                         e->ident = token->ident;
 214                         token = token->next;
 215                         break;
 216                 case '[':
 217                         token = token->next;
 218                         e = alloc_expression(token->pos, EXPR_OFFSETOF);
 219                         e->op = '[';
 220                         token = parse_expression(token, &e->index);
 221                         token = expect(token, ']',
 222                                         "at end of array dereference");
 223                         if (!e->index)
 224                                 return token;
 225                 }
 226                 *p = e;
 227                 p = &e->down;
 228                 op = token_type(token) == TOKEN_SPECIAL ? token->special : 0;
 229         }
 230 }
 231
 232 #ifndef ULLONG_MAX
 233 #define ULLONG_MAX (~0ULL)
 234 #endif
 235
 236 static unsigned long long parse_num(const char *nptr, char **end)
 237 {
 238         if (nptr[0] == '0' && tolower((unsigned char)nptr[1]) == 'b')
 239                 return strtoull(&nptr[2], end, 2);
 240         return strtoull(nptr, end, 0);
 241 }
 242
 243 static void get_number_value(struct expression *expr, struct token *token)
 244 {
 245         const char *str = token->number;
 246         unsigned long long value;
 247         char *end;
 248         int size = 0, want_unsigned = 0;
 249         int overflow = 0, do_warn = 0;
 250         int try_unsigned = 1;
 251         int bits;
 252
 253         errno = 0;
 254         value = parse_num(str, &end);
 255         if (end == str)
 256                 goto Float;
 257         if (value == ULLONG_MAX && errno == ERANGE)
 258                 overflow = 1;
 259         while (1) {
 260                 char c = *end++;
 261                 if (!c) {
 262                         break;
 263                 } else if (c == 'u' || c == 'U') {
 264                         if (want_unsigned)
 265                                 goto Enoint;
 266                         want_unsigned = 1;
 267                 } else if (c == 'l' || c == 'L') {
 268                         if (size)
 269                                 goto Enoint;
 270                         size = 1;
 271                         if (*end == c) {
 272                                 size = 2;
 273                                 end++;
 274                         }
 275                 } else
 276                         goto Float;
 277         }
 278         if (overflow)
 279                 goto Eoverflow;
 280         /* OK, it's a valid integer */
 281         /* decimals can be unsigned only if directly specified as such */
 282         if (str[0] != '0' && !want_unsigned)
 283                 try_unsigned = 0;
 284         if (!size) {
 285                 bits = bits_in_int - 1;
 286                 if (!(value & (~1ULL << bits))) {
 287                         if (!(value & (1ULL << bits))) {
 288                                 goto got_it;
 289                         } else if (try_unsigned) {
 290                                 want_unsigned = 1;
 291                                 goto got_it;
 292                         }
 293                 }
 294                 size = 1;
 295                 do_warn = 1;
 296         }
 297         if (size < 2) {
 298                 bits = bits_in_long - 1;
 299                 if (!(value & (~1ULL << bits))) {
 300                         if (!(value & (1ULL << bits))) {
 301                                 goto got_it;
 302                         } else if (try_unsigned) {
 303                                 want_unsigned = 1;
 304                                 goto got_it;
 305                         }
 306                         do_warn |= 2;
 307                 }
 308                 size = 2;
 309                 do_warn |= 1;
 310         }
 311         bits = bits_in_longlong - 1;
 312         if (value & (~1ULL << bits))
 313                 goto Eoverflow;
 314         if (!(value & (1ULL << bits)))
 315                 goto got_it;
 316         if (!try_unsigned)
 317                 warning(expr->pos, "decimal constant %s is too big for long long",
 318                         show_token(token));
 319         want_unsigned = 1;
 320 got_it:
 321         if (!Wbig_constants)
 322                 do_warn = 0;
 323
 324         if (do_warn)
 325                 warning(expr->pos, "constant %s is so big it is%s%s%s",
 326                         show_token(token),
 327                         want_unsigned ? " unsigned":"",
 328                         size > 0 ? " long":"",
 329                         size > 1 ? " long":"");
 330         if (do_warn & 2)
 331                 warning(expr->pos,
 332                         "decimal constant %s is between LONG_MAX and ULONG_MAX."
 333                         " For C99 that means long long, C90 compilers are very "
 334                         "likely to produce unsigned long (and a warning) here",
 335                         show_token(token));
 336         expr->type = EXPR_VALUE;
 337         expr->flags = CEF_SET_INT;
 338         expr->ctype = ctype_integer(size, want_unsigned);
 339         expr->value = value;
 340         return;
 341 Eoverflow:
 342         error_die(expr->pos, "constant %s is too big even for unsigned long long",
 343                         show_token(token));
 344         return;
 345 Float:
 346         expr->fvalue = string_to_ld(str, &end);
 347         if (str == end)
 348                 goto Enoint;
 349
 350         if (*end && end[1])
 351                 goto Enoint;
 352
 353         if (*end == 'f' || *end == 'F')
 354                 expr->ctype = &float_ctype;
 355         else if (*end == 'l' || *end == 'L')
 356                 expr->ctype = &ldouble_ctype;
 357         else if (!*end)
 358                 expr->ctype = &double_ctype;
 359         else
 360                 goto Enoint;
 361
 362         expr->flags = CEF_SET_FLOAT;
 363         expr->type = EXPR_FVALUE;
 364         return;
 365
 366 Enoint:
 367         error_die(expr->pos, "constant %s is not a valid number", show_token(token));
 368 }
 369
 370 struct token *primary_expression(struct token *token, struct expression **tree)
 371 {
 372         struct expression *expr = NULL;
 373
 374         switch (token_type(token)) {
 375         case TOKEN_CHAR ... TOKEN_WIDE_CHAR_EMBEDDED_3:
 376                 expr = alloc_expression(token->pos, EXPR_VALUE);
 377                 expr->flags = CEF_SET_CHAR;
 378                 expr->ctype = token_type(token) < TOKEN_WIDE_CHAR ? &int_ctype : &long_ctype;
 379                 get_char_constant(token, &expr->value);
 380                 token = token->next;
 381                 break;
 382
 383         case TOKEN_NUMBER:
 384                 expr = alloc_expression(token->pos, EXPR_VALUE);
 385                 get_number_value(expr, token); /* will see if it's an integer */
 386                 token = token->next;
 387                 break;
 388
 389         case TOKEN_ZERO_IDENT: {
 390                 expr = alloc_expression(token->pos, EXPR_SYMBOL);
 391                 expr->flags = CEF_SET_INT;
 392                 expr->ctype = &int_ctype;
 393                 expr->symbol = &zero_int;
 394                 expr->symbol_name = token->ident;
 395                 token = token->next;
 396                 break;
 397         }
 398
 399         case TOKEN_IDENT: {
 400                 struct symbol *sym = lookup_symbol(token->ident, NS_SYMBOL | NS_TYPEDEF);
 401                 struct token *next = token->next;
 402
 403                 if (!sym) {
 404                         sym = handle_func(token);
 405                         if (token->ident == &__builtin_types_compatible_p_ident) {
 406                                 token = builtin_types_compatible_p_expr(token, &expr);
 407                                 break;
 408                         }
 409                         if (token->ident == &__builtin_offsetof_ident) {
 410                                 token = builtin_offsetof_expr(token, &expr);
 411                                 break;
 412                         }
 413                 } else if (sym->enum_member) {
 414                         expr = alloc_expression(token->pos, EXPR_VALUE);
 415                         *expr = *sym->initializer;
 416                         /* we want the right position reported, thus the copy */
 417                         expr->pos = token->pos;
 418                         expr->flags = CEF_SET_ENUM;
 419                         token = next;
 420                         break;
 421                 }
 422
 423                 expr = alloc_expression(token->pos, EXPR_SYMBOL);
 424
 425                 /*
 426                  * We support types as real first-class citizens, with type
 427                  * comparisons etc:
 428                  *
 429                  *      if (typeof(a) == int) ..
 430                  */
 431                 if (sym && sym->namespace == NS_TYPEDEF) {
 432                         sparse_error(token->pos, "typename in expression");
 433                         sym = NULL;
 434                 }
 435                 expr->symbol_name = token->ident;
 436                 expr->symbol = sym;
 437
 438                 /*
 439                  * A pointer to an lvalue designating a static storage
 440                  * duration object is an address constant [6.6(9)].
 441                  */
 442                 if (sym && (sym->ctype.modifiers & (MOD_TOPLEVEL | MOD_STATIC)))
 443                         expr->flags = CEF_ADDR;
 444
 445                 token = next;
 446                 break;
 447         }
 448
 449         case TOKEN_STRING:
 450         case TOKEN_WIDE_STRING:
 451                 expr = alloc_expression(token->pos, EXPR_STRING);
 452                 token = get_string_constant(token, expr);
 453                 break;
 454
 455         case TOKEN_SPECIAL:
 456                 if (token->special == '(') {
 457                         expr = alloc_expression(token->pos, EXPR_PREOP);
 458                         expr->op = '(';
 459                         token = parens_expression(token, &expr->unop, "in expression");
 460                         break;
 461                 }
 462                 if (token->special == '[' && lookup_type(token->next)) {
 463                         expr = alloc_expression(token->pos, EXPR_TYPE);
 464                         token = typename(token->next, &expr->symbol, NULL);
 465                         token = expect(token, ']', "in type expression");
 466                         break;
 467                 }
 468
 469         default:
 470                 ;
 471         }
 472         *tree = expr;
 473         return token;
 474 }
 475
 476 static struct token *expression_list(struct token *token, struct expression_list **list)
 477 {
 478         while (!match_op(token, ')')) {
 479                 struct expression *expr = NULL;
 480                 token = assignment_expression(token, &expr);
 481                 if (!expr)
 482                         break;
 483                 add_expression(list, expr);
 484                 if (!match_op(token, ','))
 485                         break;
 486                 token = token->next;
 487         }
 488         return token;
 489 }
 490
 491 /*
 492  * extend to deal with the ambiguous C grammar for parsing
 493  * a cast expressions followed by an initializer.
 494  */
 495 static struct token *postfix_expression(struct token *token, struct expression **tree, struct expression *cast_init_expr)
 496 {
 497         struct expression *expr = cast_init_expr;
 498
 499         if (!expr)
 500                 token = primary_expression(token, &expr);
 501
 502         while (expr && token_type(token) == TOKEN_SPECIAL) {
 503                 switch (token->special) {
 504                 case '[': {                     /* Array dereference */
 505                         struct expression *deref = alloc_expression(token->pos, EXPR_PREOP);
 506                         struct expression *add = alloc_expression(token->pos, EXPR_BINOP);
 507
 508                         deref->op = '*';
 509                         deref->unop = add;
 510
 511                         add->op = '+';
 512                         add->left = expr;
 513                         token = parse_expression(token->next, &add->right);
 514                         token = expect(token, ']', "at end of array dereference");
 515                         expr = deref;
 516                         continue;
 517                 }
 518                 case SPECIAL_INCREMENT:         /* Post-increment */
 519                 case SPECIAL_DECREMENT: {       /* Post-decrement */
 520                         struct expression *post = alloc_expression(token->pos, EXPR_POSTOP);
 521                         post->op = token->special;
 522                         post->unop = expr;
 523                         expr = post;
 524                         token = token->next;
 525                         continue;
 526                 }
 527                 case SPECIAL_DEREFERENCE: {     /* Structure pointer member dereference */
 528                         /* "x->y" is just shorthand for "(*x).y" */
 529                         struct expression *inner = alloc_expression(token->pos, EXPR_PREOP);
 530                         inner->op = '*';
 531                         inner->unop = expr;
 532                         expr = inner;
 533                 }
 534                 /* Fall through!! */
 535                 case '.': {                     /* Structure member dereference */
 536                         struct expression *deref = alloc_expression(token->pos, EXPR_DEREF);
 537                         deref->op = '.';
 538                         deref->deref = expr;
 539                         token = token->next;
 540                         if (token_type(token) != TOKEN_IDENT) {
 541                                 sparse_error(token->pos, "Expected member name");
 542                                 break;
 543                         }
 544                         deref->member = token->ident;
 545                         deref->member_offset = -1;
 546                         token = token->next;
 547                         expr = deref;
 548                         continue;
 549                 }
 550
 551                 case '(': {                     /* Function call */
 552                         struct expression *call = alloc_expression(token->pos, EXPR_CALL);
 553                         call->op = '(';
 554                         call->fn = expr;
 555                         token = expression_list(token->next, &call->args);
 556                         token = expect(token, ')', "in function call");
 557                         expr = call;
 558                         continue;
 559                 }
 560
 561                 default:
 562                         break;
 563                 }
 564                 break;
 565         }
 566         *tree = expr;
 567         return token;
 568 }
 569
 570 static struct token *cast_expression(struct token *token, struct expression **tree);
 571 static struct token *unary_expression(struct token *token, struct expression **tree);
 572
 573 static struct token *type_info_expression(struct token *token,
 574         struct expression **tree, int type)
 575 {
 576         struct expression *expr = alloc_expression(token->pos, type);
 577         struct token *p;
 578
 579         *tree = expr;
 580         expr->flags = CEF_SET_ICE; /* XXX: VLA support will need that changed */
 581         token = token->next;
 582         if (!match_op(token, '(') || !lookup_type(token->next))
 583                 return unary_expression(token, &expr->cast_expression);
 584         p = token;
 585         token = typename(token->next, &expr->cast_type, NULL);
 586
 587         if (!match_op(token, ')')) {
 588                 static const char * error[] = {
 589                         [EXPR_SIZEOF] = "at end of sizeof",
 590                         [EXPR_ALIGNOF] = "at end of __alignof__",
 591                         [EXPR_PTRSIZEOF] = "at end of __sizeof_ptr__"
 592                 };
 593                 return expect(token, ')', error[type]);
 594         }
 595
 596         token = token->next;
 597         /*
 598          * C99 ambiguity: the typename might have been the beginning
 599          * of a typed initializer expression..
 600          */
 601         if (match_op(token, '{')) {
 602                 struct expression *cast = alloc_expression(p->pos, EXPR_CAST);
 603                 cast->cast_type = expr->cast_type;
 604                 expr->cast_type = NULL;
 605                 expr->cast_expression = cast;
 606                 token = initializer(&cast->cast_expression, token);
 607                 token = postfix_expression(token, &expr->cast_expression, cast);
 608         }
 609         return token;
 610 }
 611
 612 static struct token *unary_expression(struct token *token, struct expression **tree)
 613 {
 614         if (token_type(token) == TOKEN_IDENT) {
 615                 struct ident *ident = token->ident;
 616                 if (ident->reserved) {
 617                         static const struct {
 618                                 struct ident *id;
 619                                 int type;
 620                         } type_information[] = {
 621                                 { &sizeof_ident, EXPR_SIZEOF },
 622                                 { &__alignof___ident, EXPR_ALIGNOF },
 623                                 { &__alignof_ident, EXPR_ALIGNOF },
 624                                 { &_Alignof_ident, EXPR_ALIGNOF },
 625                                 { &__sizeof_ptr___ident, EXPR_PTRSIZEOF },
 626                         };
 627                         int i;
 628                         for (i = 0; i < ARRAY_SIZE(type_information); i++) {
 629                                 if (ident == type_information[i].id)
 630                                         return type_info_expression(token, tree, type_information[i].type);
 631                         }
 632                 }
 633         }
 634
 635         if (token_type(token) == TOKEN_SPECIAL) {
 636                 if (match_oplist(token->special,
 637                     SPECIAL_INCREMENT, SPECIAL_DECREMENT,
 638                     '&', '*', 0)) {
 639                         struct expression *unop;
 640                         struct expression *unary;
 641                         struct token *next;
 642
 643                         next = cast_expression(token->next, &unop);
 644                         if (!unop) {
 645                                 sparse_error(token->pos, "Syntax error in unary expression");
 646                                 *tree = NULL;
 647                                 return next;
 648                         }
 649                         unary = alloc_expression(token->pos, EXPR_PREOP);
 650                         unary->op = token->special;
 651                         unary->unop = unop;
 652                         *tree = unary;
 653                         return next;
 654                 }
 655                 /* possibly constant ones */
 656                 if (match_oplist(token->special, '+', '-', '~', '!', 0)) {
 657                         struct expression *unop;
 658                         struct expression *unary;
 659                         struct token *next;
 660
 661                         next = cast_expression(token->next, &unop);
 662                         if (!unop) {
 663                                 sparse_error(token->pos, "Syntax error in unary expression");
 664                                 *tree = NULL;
 665                                 return next;
 666                         }
 667                         unary = alloc_expression(token->pos, EXPR_PREOP);
 668                         unary->op = token->special;
 669                         unary->unop = unop;
 670                         *tree = unary;
 671                         return next;
 672                 }
 673                 /* Gcc extension: &&label gives the address of a label */
 674                 if (match_op(token, SPECIAL_LOGICAL_AND) &&
 675                     token_type(token->next) == TOKEN_IDENT) {
 676                         struct expression *label = alloc_expression(token->pos, EXPR_LABEL);
 677                         struct symbol *sym = label_symbol(token->next);
 678                         if (!(sym->ctype.modifiers & MOD_ADDRESSABLE)) {
 679                                 sym->ctype.modifiers |= MOD_ADDRESSABLE;
 680                                 add_symbol(&function_computed_target_list, sym);
 681                         }
 682                         label->flags = CEF_ADDR;
 683                         label->label_symbol = sym;
 684                         *tree = label;
 685                         return token->next->next;
 686                 }
 687
 688         }
 689
 690         return postfix_expression(token, tree, NULL);
 691 }
 692
 693 /*
 694  * Ambiguity: a '(' can be either a cast-expression or
 695  * a primary-expression depending on whether it is followed
 696  * by a type or not.
 697  *
 698  * additional ambiguity: a "cast expression" followed by
 699  * an initializer is really a postfix-expression.
 700  */
 701 static struct token *cast_expression(struct token *token, struct expression **tree)
 702 {
 703         if (match_op(token, '(')) {
 704                 struct token *next = token->next;
 705                 if (lookup_type(next)) {
 706                         struct expression *cast = alloc_expression(next->pos, EXPR_CAST);
 707                         struct expression *v;
 708                         struct symbol *sym;
 709                         int is_force;
 710
 711                         token = typename(next, &sym, &is_force);
 712                         cast->cast_type = sym;
 713                         token = expect(token, ')', "at end of cast operator");
 714                         if (match_op(token, '{')) {
 715                                 if (toplevel(block_scope))
 716                                         sym->ctype.modifiers |= MOD_TOPLEVEL;
 717                                 if (is_force)
 718                                         warning(sym->pos,
 719                                                 "[force] in compound literal");
 720                                 token = initializer(&cast->cast_expression, token);
 721                                 return postfix_expression(token, tree, cast);
 722                         }
 723                         *tree = cast;
 724                         if (is_force)
 725                                 cast->type = EXPR_FORCE_CAST;
 726                         token = cast_expression(token, &v);
 727                         if (!v)
 728                                 return token;
 729                         cast->cast_expression = v;
 730                         return token;
 731                 }
 732         }
 733         return unary_expression(token, tree);
 734 }
 735
 736 /*
 737  * Generic left-to-right binop parsing
 738  *
 739  * This _really_ needs to be inlined, because that makes the inner
 740  * function call statically deterministic rather than a totally
 741  * unpredictable indirect call. But gcc-3 is so "clever" that it
 742  * doesn't do so by default even when you tell it to inline it.
 743  *
 744  * Making it a macro avoids the inlining problem, and also means
 745  * that we can pass in the op-comparison as an expression rather
 746  * than create a data structure for it.
 747  */
 748
 749 #define LR_BINOP_EXPRESSION(__token, tree, type, inner, compare)        \
 750         struct expression *left = NULL;                                 \
 751         struct token * next = inner(__token, &left);                    \
 752                                                                         \
 753         if (left) {                                                     \
 754                 while (token_type(next) == TOKEN_SPECIAL) {             \
 755                         struct expression *top, *right = NULL;          \
 756                         int op = next->special;                         \
 757                                                                         \
 758                         if (!(compare))                                 \
 759                                 goto out;                               \
 760                         top = alloc_expression(next->pos, type);        \
 761                         next = inner(next->next, &right);               \
 762                         if (!right) {                                   \
 763                                 sparse_error(next->pos, "No right hand side of '%s'-expression", show_special(op));     \
 764                                 break;                                  \
 765                         }                                               \
 766                         top->op = op;                                   \
 767                         top->left = left;                               \
 768                         top->right = right;                             \
 769                         left = top;                                     \
 770                 }                                                       \
 771         }                                                               \
 772 out:                                                                    \
 773         *tree = left;                                                   \
 774         return next;                                                    \
 775
 776 static struct token *multiplicative_expression(struct token *token, struct expression **tree)
 777 {
 778         LR_BINOP_EXPRESSION(
 779                 token, tree, EXPR_BINOP, cast_expression,
 780                 (op == '*') || (op == '/') || (op == '%')
 781         );
 782 }
 783
 784 static struct token *additive_expression(struct token *token, struct expression **tree)
 785 {
 786         LR_BINOP_EXPRESSION(
 787                 token, tree, EXPR_BINOP, multiplicative_expression,
 788                 (op == '+') || (op == '-')
 789         );
 790 }
 791
 792 static struct token *shift_expression(struct token *token, struct expression **tree)
 793 {
 794         LR_BINOP_EXPRESSION(
 795                 token, tree, EXPR_BINOP, additive_expression,
 796                 (op == SPECIAL_LEFTSHIFT) || (op == SPECIAL_RIGHTSHIFT)
 797         );
 798 }
 799
 800 static struct token *relational_expression(struct token *token, struct expression **tree)
 801 {
 802         LR_BINOP_EXPRESSION(
 803                 token, tree, EXPR_COMPARE, shift_expression,
 804                 (op == '<') || (op == '>') ||
 805                 (op == SPECIAL_LTE) || (op == SPECIAL_GTE)
 806         );
 807 }
 808
 809 static struct token *equality_expression(struct token *token, struct expression **tree)
 810 {
 811         LR_BINOP_EXPRESSION(
 812                 token, tree, EXPR_COMPARE, relational_expression,
 813                 (op == SPECIAL_EQUAL) || (op == SPECIAL_NOTEQUAL)
 814         );
 815 }
 816
 817 static struct token *bitwise_and_expression(struct token *token, struct expression **tree)
 818 {
 819         LR_BINOP_EXPRESSION(
 820                 token, tree, EXPR_BINOP, equality_expression,
 821                 (op == '&')
 822         );
 823 }
 824
 825 static struct token *bitwise_xor_expression(struct token *token, struct expression **tree)
 826 {
 827         LR_BINOP_EXPRESSION(
 828                 token, tree, EXPR_BINOP, bitwise_and_expression,
 829                 (op == '^')
 830         );
 831 }
 832
 833 static struct token *bitwise_or_expression(struct token *token, struct expression **tree)
 834 {
 835         LR_BINOP_EXPRESSION(
 836                 token, tree, EXPR_BINOP, bitwise_xor_expression,
 837                 (op == '|')
 838         );
 839 }
 840
 841 static struct token *logical_and_expression(struct token *token, struct expression **tree)
 842 {
 843         LR_BINOP_EXPRESSION(
 844                 token, tree, EXPR_LOGICAL, bitwise_or_expression,
 845                 (op == SPECIAL_LOGICAL_AND)
 846         );
 847 }
 848
 849 static struct token *logical_or_expression(struct token *token, struct expression **tree)
 850 {
 851         LR_BINOP_EXPRESSION(
 852                 token, tree, EXPR_LOGICAL, logical_and_expression,
 853                 (op == SPECIAL_LOGICAL_OR)
 854         );
 855 }
 856
 857 struct token *conditional_expression(struct token *token, struct expression **tree)
 858 {
 859         token = logical_or_expression(token, tree);
 860         if (*tree && match_op(token, '?')) {
 861                 struct expression *expr = alloc_expression(token->pos, EXPR_CONDITIONAL);
 862                 expr->op = token->special;
 863                 expr->left = *tree;
 864                 *tree = expr;
 865                 token = parse_expression(token->next, &expr->cond_true);
 866                 token = expect(token, ':', "in conditional expression");
 867                 token = conditional_expression(token, &expr->cond_false);
 868         }
 869         return token;
 870 }
 871
 872 struct token *assignment_expression(struct token *token, struct expression **tree)
 873 {
 874         token = conditional_expression(token, tree);
 875         if (*tree && token_type(token) == TOKEN_SPECIAL) {
 876                 static const int assignments[] = {
 877                         '=',
 878                         SPECIAL_ADD_ASSIGN, SPECIAL_SUB_ASSIGN,
 879                         SPECIAL_MUL_ASSIGN, SPECIAL_DIV_ASSIGN,
 880                         SPECIAL_MOD_ASSIGN, SPECIAL_SHL_ASSIGN,
 881                         SPECIAL_SHR_ASSIGN, SPECIAL_AND_ASSIGN,
 882                         SPECIAL_OR_ASSIGN,  SPECIAL_XOR_ASSIGN };
 883                 int i, op = token->special;
 884                 for (i = 0; i < ARRAY_SIZE(assignments); i++)
 885                         if (assignments[i] == op) {
 886                                 struct expression * expr = alloc_expression(token->pos, EXPR_ASSIGNMENT);
 887                                 expr->left = *tree;
 888                                 expr->op = op;
 889                                 *tree = expr;
 890                                 return assignment_expression(token->next, &expr->right);
 891                         }
 892         }
 893         return token;
 894 }
 895
 896 static struct token *comma_expression(struct token *token, struct expression **tree)
 897 {
 898         LR_BINOP_EXPRESSION(
 899                 token, tree, EXPR_COMMA, assignment_expression,
 900                 (op == ',')
 901         );
 902 }
 903
 904 struct token *parse_expression(struct token *token, struct expression **tree)
 905 {
 906         return comma_expression(token,tree);
 907 }
 908
 909