expression.c

   1 /*
   2  * sparse/expression.c
   3  *
   4  * Copyright (C) 2003 Transmeta Corp.
   5  *               2003-2004 Linus Torvalds
   6  *
   7  *  Licensed under the Open Software License version 1.1
   8  *
   9  * This is the expression parsing part of parsing C.
  10  */
  11 #include <stdarg.h>
  12 #include <stdlib.h>
  13 #include <stdio.h>
  14 #include <string.h>
  15 #include <ctype.h>
  16 #include <unistd.h>
  17 #include <fcntl.h>
  18 #include <errno.h>
  19 #include <limits.h>
  20
  21 #include "lib.h"
  22 #include "allocate.h"
  23 #include "token.h"
  24 #include "parse.h"
  25 #include "symbol.h"
  26 #include "scope.h"
  27 #include "expression.h"
  28 #include "target.h"
  29
  30 static int match_oplist(int op, ...)
  31 {
  32         va_list args;
  33         int nextop;
  34
  35         va_start(args, op);
  36         do {
  37                 nextop = va_arg(args, int);
  38         } while (nextop != 0 && nextop != op);
  39         va_end(args);
  40
  41         return nextop != 0;
  42 }
  43
  44 static struct token *comma_expression(struct token *, struct expression **);
  45
  46 struct token *parens_expression(struct token *token, struct expression **expr, const char *where)
  47 {
  48         token = expect(token, '(', where);
  49         if (match_op(token, '{')) {
  50                 struct expression *e = alloc_expression(token->pos, EXPR_STATEMENT);
  51                 struct statement *stmt = alloc_statement(token->pos, STMT_COMPOUND);
  52                 *expr = e;
  53                 e->statement = stmt;
  54                 start_symbol_scope();
  55                 token = compound_statement(token->next, stmt);
  56                 end_symbol_scope();
  57                 token = expect(token, '}', "at end of statement expression");
  58         } else
  59                 token = parse_expression(token, expr);
  60         return expect(token, ')', where);
  61 }
  62
  63 /*
  64  * Handle __func__, __FUNCTION__ and __PRETTY_FUNCTION__ token
  65  * conversion
  66  */
  67 static int convert_one_fn_token(struct token *token)
  68 {
  69         struct symbol *sym = current_fn;
  70
  71         if (sym) {
  72                 struct ident *ident = sym->ident;
  73                 if (ident) {
  74                         int len = ident->len;
  75                         struct string *string;
  76
  77                         string = __alloc_string(len+1);
  78                         memcpy(string->data, ident->name, len);
  79                         string->data[len] = 0;
  80                         string->length = len+1;
  81                         token_type(token) = TOKEN_STRING;
  82                         token->string = string;
  83                         return 1;
  84                 }
  85         }
  86         return 0;
  87 }
  88
  89 static int convert_function(struct token *next)
  90 {
  91         int retval = 0;
  92         for (;;) {
  93                 struct token *token = next;
  94                 next = next->next;
  95                 switch (token_type(token)) {
  96                 case TOKEN_STRING:
  97                         continue;
  98                 case TOKEN_IDENT:
  99                         if (token->ident == &__func___ident ||
 100                             token->ident == &__FUNCTION___ident ||
 101                             token->ident == &__PRETTY_FUNCTION___ident) {
 102                                 if (!convert_one_fn_token(token))
 103                                         break;
 104                                 retval = 1;
 105                                 continue;
 106                         }
 107                 /* Fall through */
 108                 default:
 109                         break;
 110                 }
 111                 break;
 112         }
 113         return retval;
 114 }
 115
 116 static struct token *parse_type(struct token *token, struct expression **tree)
 117 {
 118         struct symbol *sym;
 119         *tree = alloc_expression(token->pos, EXPR_TYPE);
 120         (*tree)->flags = Int_const_expr; /* sic */
 121         token = typename(token, &sym, 0);
 122         if (sym->ident)
 123                 sparse_error(token->pos,
 124                              "type expression should not include identifier "
 125                              "\"%s\"", sym->ident->name);
 126         (*tree)->symbol = sym;
 127         return token;
 128 }
 129
 130 static struct token *builtin_types_compatible_p_expr(struct token *token,
 131                                                      struct expression **tree)
 132 {
 133         struct expression *expr = alloc_expression(
 134                 token->pos, EXPR_COMPARE);
 135         expr->flags = Int_const_expr;
 136         expr->op = SPECIAL_EQUAL;
 137         token = token->next;
 138         if (!match_op(token, '('))
 139                 return expect(token, '(',
 140                               "after __builtin_types_compatible_p");
 141         token = token->next;
 142         token = parse_type(token, &expr->left);
 143         if (!match_op(token, ','))
 144                 return expect(token, ',',
 145                               "in __builtin_types_compatible_p");
 146         token = token->next;
 147         token = parse_type(token, &expr->right);
 148         if (!match_op(token, ')'))
 149                 return expect(token, ')',
 150                               "at end of __builtin_types_compatible_p");
 151         token = token->next;
 152
 153         *tree = expr;
 154         return token;
 155 }
 156
 157 static struct token *builtin_offsetof_expr(struct token *token,
 158                                            struct expression **tree)
 159 {
 160         struct expression *expr = NULL;
 161         struct expression **p = &expr;
 162         struct symbol *sym;
 163         int op = '.';
 164
 165         token = token->next;
 166         if (!match_op(token, '('))
 167                 return expect(token, '(', "after __builtin_offset");
 168
 169         token = token->next;
 170         token = typename(token, &sym, 0);
 171         if (sym->ident)
 172                 sparse_error(token->pos,
 173                              "type expression should not include identifier "
 174                              "\"%s\"", sym->ident->name);
 175
 176         if (!match_op(token, ','))
 177                 return expect(token, ',', "in __builtin_offset");
 178
 179         while (1) {
 180                 struct expression *e;
 181                 switch (op) {
 182                 case ')':
 183                         expr->in = sym;
 184                         *tree = expr;
 185                 default:
 186                         return expect(token, ')', "at end of __builtin_offset");
 187                 case SPECIAL_DEREFERENCE:
 188                         e = alloc_expression(token->pos, EXPR_OFFSETOF);
 189                         e->flags = Int_const_expr;
 190                         e->op = '[';
 191                         *p = e;
 192                         p = &e->down;
 193                         /* fall through */
 194                 case '.':
 195                         token = token->next;
 196                         e = alloc_expression(token->pos, EXPR_OFFSETOF);
 197                         e->flags = Int_const_expr;
 198                         e->op = '.';
 199                         if (token_type(token) != TOKEN_IDENT) {
 200                                 sparse_error(token->pos, "Expected member name");
 201                                 return token;
 202                         }
 203                         e->ident = token->ident;
 204                         token = token->next;
 205                         break;
 206                 case '[':
 207                         token = token->next;
 208                         e = alloc_expression(token->pos, EXPR_OFFSETOF);
 209                         e->flags = Int_const_expr;
 210                         e->op = '[';
 211                         token = parse_expression(token, &e->index);
 212                         token = expect(token, ']',
 213                                         "at end of array dereference");
 214                         if (!e->index)
 215                                 return token;
 216                 }
 217                 *p = e;
 218                 p = &e->down;
 219                 op = token_type(token) == TOKEN_SPECIAL ? token->special : 0;
 220         }
 221 }
 222
 223 static struct token *string_expression(struct token *token, struct expression *expr)
 224 {
 225         struct string *string = token->string;
 226         struct token *next = token->next;
 227
 228         convert_function(token);
 229
 230         if (token_type(next) == TOKEN_STRING) {
 231                 int totlen = string->length-1;
 232                 char *data;
 233
 234                 do {
 235                         totlen += next->string->length-1;
 236                         next = next->next;
 237                 } while (token_type(next) == TOKEN_STRING);
 238
 239                 if (totlen > MAX_STRING) {
 240                         warning(token->pos, "trying to concatenate %d-character string (%d bytes max)", totlen, MAX_STRING);
 241                         totlen = MAX_STRING;
 242                 }
 243
 244                 string = __alloc_string(totlen+1);
 245                 string->length = totlen+1;
 246                 data = string->data;
 247                 next = token;
 248                 do {
 249                         struct string *s = next->string;
 250                         int len = s->length-1;
 251
 252                         if (len > totlen)
 253                                 len = totlen;
 254                         totlen -= len;
 255
 256                         next = next->next;
 257                         memcpy(data, s->data, len);
 258                         data += len;
 259                 } while (token_type(next) == TOKEN_STRING);
 260                 *data = '\0';
 261         }
 262         expr->string = string;
 263         return next;
 264 }
 265
 266 #ifndef ULLONG_MAX
 267 #define ULLONG_MAX (~0ULL)
 268 #endif
 269
 270 static void get_number_value(struct expression *expr, struct token *token)
 271 {
 272         const char *str = token->number;
 273         unsigned long long value;
 274         char *end;
 275         unsigned long modifiers = 0;
 276         int overflow = 0, do_warn = 0;
 277         int try_unsigned = 1;
 278         int bits;
 279
 280         errno = 0;
 281         value = strtoull(str, &end, 0);
 282         if (end == str)
 283                 goto Float;
 284         if (value == ULLONG_MAX && errno == ERANGE)
 285                 overflow = 1;
 286         while (1) {
 287                 unsigned long added;
 288                 char c = *end++;
 289                 if (!c) {
 290                         break;
 291                 } else if (c == 'u' || c == 'U') {
 292                         added = MOD_UNSIGNED;
 293                 } else if (c == 'l' || c == 'L') {
 294                         added = MOD_LONG;
 295                         if (*end == c) {
 296                                 added |= MOD_LONGLONG;
 297                                 end++;
 298                         }
 299                 } else
 300                         goto Float;
 301                 if (modifiers & added)
 302                         goto Enoint;
 303                 modifiers |= added;
 304         }
 305         if (overflow)
 306                 goto Eoverflow;
 307         /* OK, it's a valid integer */
 308         /* decimals can be unsigned only if directly specified as such */
 309         if (str[0] != '0' && !(modifiers & MOD_UNSIGNED))
 310                 try_unsigned = 0;
 311         if (!(modifiers & MOD_LONG)) {
 312                 bits = bits_in_int - 1;
 313                 if (!(value & (~1ULL << bits))) {
 314                         if (!(value & (1ULL << bits))) {
 315                                 goto got_it;
 316                         } else if (try_unsigned) {
 317                                 modifiers |= MOD_UNSIGNED;
 318                                 goto got_it;
 319                         }
 320                 }
 321                 modifiers |= MOD_LONG;
 322                 do_warn = 1;
 323         }
 324         if (!(modifiers & MOD_LONGLONG)) {
 325                 bits = bits_in_long - 1;
 326                 if (!(value & (~1ULL << bits))) {
 327                         if (!(value & (1ULL << bits))) {
 328                                 goto got_it;
 329                         } else if (try_unsigned) {
 330                                 modifiers |= MOD_UNSIGNED;
 331                                 goto got_it;
 332                         }
 333                         do_warn |= 2;
 334                 }
 335                 modifiers |= MOD_LONGLONG;
 336                 do_warn |= 1;
 337         }
 338         bits = bits_in_longlong - 1;
 339         if (value & (~1ULL << bits))
 340                 goto Eoverflow;
 341         if (!(value & (1ULL << bits)))
 342                 goto got_it;
 343         if (!try_unsigned)
 344                 warning(expr->pos, "decimal constant %s is too big for long long",
 345                         show_token(token));
 346         modifiers |= MOD_UNSIGNED;
 347 got_it:
 348         if (do_warn)
 349                 warning(expr->pos, "constant %s is so big it is%s%s%s",
 350                         show_token(token),
 351                         (modifiers & MOD_UNSIGNED) ? " unsigned":"",
 352                         (modifiers & MOD_LONG) ? " long":"",
 353                         (modifiers & MOD_LONGLONG) ? " long":"");
 354         if (do_warn & 2)
 355                 warning(expr->pos,
 356                         "decimal constant %s is between LONG_MAX and ULONG_MAX."
 357                         " For C99 that means long long, C90 compilers are very "
 358                         "likely to produce unsigned long (and a warning) here",
 359                         show_token(token));
 360         expr->type = EXPR_VALUE;
 361         expr->flags = Int_const_expr;
 362         expr->ctype = ctype_integer(modifiers);
 363         expr->value = value;
 364         return;
 365 Eoverflow:
 366         error_die(expr->pos, "constant %s is too big even for unsigned long long",
 367                         show_token(token));
 368         return;
 369 Float:
 370         expr->fvalue = string_to_ld(str, &end);
 371         if (str == end)
 372                 goto Enoint;
 373
 374         if (*end && end[1])
 375                 goto Enoint;
 376
 377         if (*end == 'f' || *end == 'F')
 378                 expr->ctype = &float_ctype;
 379         else if (*end == 'l' || *end == 'L')
 380                 expr->ctype = &ldouble_ctype;
 381         else if (!*end)
 382                 expr->ctype = &double_ctype;
 383         else
 384                 goto Enoint;
 385
 386         expr->flags = Float_literal;
 387         expr->type = EXPR_FVALUE;
 388         return;
 389
 390 Enoint:
 391         error_die(expr->pos, "constant %s is not a valid number", show_token(token));
 392 }
 393
 394 struct token *primary_expression(struct token *token, struct expression **tree)
 395 {
 396         struct expression *expr = NULL;
 397
 398         switch (token_type(token)) {
 399         case TOKEN_CHAR:
 400                 expr = alloc_expression(token->pos, EXPR_VALUE);
 401                 expr->flags = Int_const_expr;
 402                 expr->ctype = &int_ctype;
 403                 expr->value = (unsigned char) token->character;
 404                 token = token->next;
 405                 break;
 406
 407         case TOKEN_NUMBER:
 408                 expr = alloc_expression(token->pos, EXPR_VALUE);
 409                 get_number_value(expr, token); /* will see if it's an integer */
 410                 token = token->next;
 411                 break;
 412
 413         case TOKEN_ZERO_IDENT: {
 414                 expr = alloc_expression(token->pos, EXPR_SYMBOL);
 415                 expr->flags = Int_const_expr;
 416                 expr->ctype = &int_ctype;
 417                 expr->symbol = &zero_int;
 418                 expr->symbol_name = token->ident;
 419                 token = token->next;
 420                 break;
 421         }
 422
 423         case TOKEN_IDENT: {
 424                 struct symbol *sym = lookup_symbol(token->ident, NS_SYMBOL | NS_TYPEDEF);
 425                 struct token *next = token->next;
 426
 427                 if (!sym) {
 428                         if (convert_function(token))
 429                                 goto handle_string;
 430                         if (token->ident == &__builtin_types_compatible_p_ident) {
 431                                 token = builtin_types_compatible_p_expr(token, &expr);
 432                                 break;
 433                         }
 434                         if (token->ident == &__builtin_offsetof_ident) {
 435                                 token = builtin_offsetof_expr(token, &expr);
 436                                 break;
 437                         }
 438                 } else if (sym->enum_member) {
 439                         expr = alloc_expression(token->pos, EXPR_VALUE);
 440                         *expr = *sym->initializer;
 441                         /* we want the right position reported, thus the copy */
 442                         expr->pos = token->pos;
 443                         expr->flags = Int_const_expr;
 444                         token = next;
 445                         break;
 446                 }
 447
 448                 expr = alloc_expression(token->pos, EXPR_SYMBOL);
 449
 450                 /*
 451                  * We support types as real first-class citizens, with type
 452                  * comparisons etc:
 453                  *
 454                  *      if (typeof(a) == int) ..
 455                  */
 456                 if (sym && sym->namespace == NS_TYPEDEF) {
 457                         sparse_error(token->pos, "typename in expression");
 458                         sym = NULL;
 459                 }
 460                 expr->symbol_name = token->ident;
 461                 expr->symbol = sym;
 462                 token = next;
 463                 break;
 464         }
 465
 466         case TOKEN_STRING: {
 467         handle_string:
 468                 expr = alloc_expression(token->pos, EXPR_STRING);
 469                 token = string_expression(token, expr);
 470                 break;
 471         }
 472
 473         case TOKEN_SPECIAL:
 474                 if (token->special == '(') {
 475                         expr = alloc_expression(token->pos, EXPR_PREOP);
 476                         expr->op = '(';
 477                         token = parens_expression(token, &expr->unop, "in expression");
 478                         if (expr->unop)
 479                                 expr->flags = expr->unop->flags;
 480                         break;
 481                 }
 482                 if (token->special == '[' && lookup_type(token->next)) {
 483                         expr = alloc_expression(token->pos, EXPR_TYPE);
 484                         expr->flags = Int_const_expr; /* sic */
 485                         token = typename(token->next, &expr->symbol, 0);
 486                         token = expect(token, ']', "in type expression");
 487                         break;
 488                 }
 489
 490         default:
 491                 ;
 492         }
 493         *tree = expr;
 494         return token;
 495 }
 496
 497 static struct token *expression_list(struct token *token, struct expression_list **list)
 498 {
 499         while (!match_op(token, ')')) {
 500                 struct expression *expr = NULL;
 501                 token = assignment_expression(token, &expr);
 502                 if (!expr)
 503                         break;
 504                 add_expression(list, expr);
 505                 if (!match_op(token, ','))
 506                         break;
 507                 token = token->next;
 508         }
 509         return token;
 510 }
 511
 512 /*
 513  * extend to deal with the ambiguous C grammar for parsing
 514  * a cast expressions followed by an initializer.
 515  */
 516 static struct token *postfix_expression(struct token *token, struct expression **tree, struct expression *cast_init_expr)
 517 {
 518         struct expression *expr = cast_init_expr;
 519
 520         if (!expr)
 521                 token = primary_expression(token, &expr);
 522
 523         while (expr && token_type(token) == TOKEN_SPECIAL) {
 524                 switch (token->special) {
 525                 case '[': {                     /* Array dereference */
 526                         struct expression *deref = alloc_expression(token->pos, EXPR_PREOP);
 527                         struct expression *add = alloc_expression(token->pos, EXPR_BINOP);
 528
 529                         deref->op = '*';
 530                         deref->unop = add;
 531
 532                         add->op = '+';
 533                         add->left = expr;
 534                         token = parse_expression(token->next, &add->right);
 535                         token = expect(token, ']', "at end of array dereference");
 536                         expr = deref;
 537                         continue;
 538                 }
 539                 case SPECIAL_INCREMENT:         /* Post-increment */
 540                 case SPECIAL_DECREMENT: {       /* Post-decrement */
 541                         struct expression *post = alloc_expression(token->pos, EXPR_POSTOP);
 542                         post->op = token->special;
 543                         post->unop = expr;
 544                         expr = post;
 545                         token = token->next;
 546                         continue;
 547                 }
 548                 case SPECIAL_DEREFERENCE: {     /* Structure pointer member dereference */
 549                         /* "x->y" is just shorthand for "(*x).y" */
 550                         struct expression *inner = alloc_expression(token->pos, EXPR_PREOP);
 551                         inner->op = '*';
 552                         inner->unop = expr;
 553                         expr = inner;
 554                 }
 555                 /* Fall through!! */
 556                 case '.': {                     /* Structure member dereference */
 557                         struct expression *deref = alloc_expression(token->pos, EXPR_DEREF);
 558                         deref->op = '.';
 559                         deref->deref = expr;
 560                         token = token->next;
 561                         if (token_type(token) != TOKEN_IDENT) {
 562                                 sparse_error(token->pos, "Expected member name");
 563                                 break;
 564                         }
 565                         deref->member = token->ident;
 566                         token = token->next;
 567                         expr = deref;
 568                         continue;
 569                 }
 570
 571                 case '(': {                     /* Function call */
 572                         struct expression *call = alloc_expression(token->pos, EXPR_CALL);
 573                         call->op = '(';
 574                         call->fn = expr;
 575                         token = expression_list(token->next, &call->args);
 576                         token = expect(token, ')', "in function call");
 577                         expr = call;
 578                         continue;
 579                 }
 580
 581                 default:
 582                         break;
 583                 }
 584                 break;
 585         }
 586         *tree = expr;
 587         return token;
 588 }
 589
 590 static struct token *cast_expression(struct token *token, struct expression **tree);
 591 static struct token *unary_expression(struct token *token, struct expression **tree);
 592
 593 static struct token *type_info_expression(struct token *token,
 594         struct expression **tree, int type)
 595 {
 596         struct expression *expr = alloc_expression(token->pos, type);
 597
 598         *tree = expr;
 599         expr->flags = Int_const_expr; /* XXX: VLA support will need that changed */
 600         token = token->next;
 601         if (!match_op(token, '(') || !lookup_type(token->next))
 602                 return unary_expression(token, &expr->cast_expression);
 603         token = typename(token->next, &expr->cast_type, 0);
 604
 605         if (!match_op(token, ')')) {
 606                 static const char * error[] = {
 607                         [EXPR_SIZEOF] = "at end of sizeof",
 608                         [EXPR_ALIGNOF] = "at end of __alignof__",
 609                         [EXPR_PTRSIZEOF] = "at end of __sizeof_ptr__"
 610                 };
 611                 return expect(token, ')', error[type]);
 612         }
 613
 614         token = token->next;
 615         /*
 616          * C99 ambiguity: the typename might have been the beginning
 617          * of a typed initializer expression..
 618          */
 619         if (match_op(token, '{'))
 620                 token = initializer(&expr->cast_expression, token);
 621         return token;
 622 }
 623
 624 static struct token *unary_expression(struct token *token, struct expression **tree)
 625 {
 626         if (token_type(token) == TOKEN_IDENT) {
 627                 struct ident *ident = token->ident;
 628                 if (ident->reserved) {
 629                         static const struct {
 630                                 struct ident *id;
 631                                 int type;
 632                         } type_information[] = {
 633                                 { &sizeof_ident, EXPR_SIZEOF },
 634                                 { &__alignof___ident, EXPR_ALIGNOF },
 635                                 { &__alignof_ident, EXPR_ALIGNOF },
 636                                 { &__sizeof_ptr___ident, EXPR_PTRSIZEOF },
 637                         };
 638                         int i;
 639                         for (i = 0; i < 3; i++) {
 640                                 if (ident == type_information[i].id)
 641                                         return type_info_expression(token, tree, type_information[i].type);
 642                         }
 643                 }
 644         }
 645
 646         if (token_type(token) == TOKEN_SPECIAL) {
 647                 if (match_oplist(token->special,
 648                     SPECIAL_INCREMENT, SPECIAL_DECREMENT,
 649                     '&', '*', 0)) {
 650                         struct expression *unop;
 651                         struct expression *unary;
 652                         struct token *next;
 653
 654                         next = cast_expression(token->next, &unop);
 655                         if (!unop) {
 656                                 sparse_error(token->pos, "Syntax error in unary expression");
 657                                 *tree = NULL;
 658                                 return next;
 659                         }
 660                         unary = alloc_expression(token->pos, EXPR_PREOP);
 661                         unary->op = token->special;
 662                         unary->unop = unop;
 663                         *tree = unary;
 664                         return next;
 665                 }
 666                 /* possibly constant ones */
 667                 if (match_oplist(token->special, '+', '-', '~', '!', 0)) {
 668                         struct expression *unop;
 669                         struct expression *unary;
 670                         struct token *next;
 671
 672                         next = cast_expression(token->next, &unop);
 673                         if (!unop) {
 674                                 sparse_error(token->pos, "Syntax error in unary expression");
 675                                 *tree = NULL;
 676                                 return next;
 677                         }
 678                         unary = alloc_expression(token->pos, EXPR_PREOP);
 679                         unary->op = token->special;
 680                         unary->unop = unop;
 681                         unary->flags = unop->flags & Int_const_expr;
 682                         *tree = unary;
 683                         return next;
 684                 }
 685                 /* Gcc extension: &&label gives the address of a label */
 686                 if (match_op(token, SPECIAL_LOGICAL_AND) &&
 687                     token_type(token->next) == TOKEN_IDENT) {
 688                         struct expression *label = alloc_expression(token->pos, EXPR_LABEL);
 689                         struct symbol *sym = label_symbol(token->next);
 690                         if (!(sym->ctype.modifiers & MOD_ADDRESSABLE)) {
 691                                 sym->ctype.modifiers |= MOD_ADDRESSABLE;
 692                                 add_symbol(&function_computed_target_list, sym);
 693                         }
 694                         label->label_symbol = sym;
 695                         *tree = label;
 696                         return token->next->next;
 697                 }
 698
 699         }
 700
 701         return postfix_expression(token, tree, NULL);
 702 }
 703
 704 /*
 705  * Ambiguity: a '(' can be either a cast-expression or
 706  * a primary-expression depending on whether it is followed
 707  * by a type or not.
 708  *
 709  * additional ambiguity: a "cast expression" followed by
 710  * an initializer is really a postfix-expression.
 711  */
 712 static struct token *cast_expression(struct token *token, struct expression **tree)
 713 {
 714         if (match_op(token, '(')) {
 715                 struct token *next = token->next;
 716                 if (lookup_type(next)) {
 717                         struct expression *cast = alloc_expression(next->pos, EXPR_CAST);
 718                         struct expression *v;
 719                         struct symbol *sym;
 720                         int is_force;
 721
 722                         token = typename(next, &sym, MOD_FORCE);
 723                         cast->cast_type = sym;
 724                         is_force = sym->ctype.modifiers & MOD_FORCE;
 725                         sym->ctype.modifiers &= ~MOD_FORCE;
 726                         token = expect(token, ')', "at end of cast operator");
 727                         if (match_op(token, '{')) {
 728                                 if (is_force)
 729                                         warning(sym->pos,
 730                                                 "[force] in compound literal");
 731                                 token = initializer(&cast->cast_expression, token);
 732                                 return postfix_expression(token, tree, cast);
 733                         }
 734                         *tree = cast;
 735                         if (is_force)
 736                                 cast->type = EXPR_FORCE_CAST;
 737                         token = cast_expression(token, &v);
 738                         if (!v)
 739                                 return token;
 740                         cast->cast_expression = v;
 741                         if (v->flags & Int_const_expr)
 742                                 cast->flags = Int_const_expr;
 743                         else if (v->flags & Float_literal) /* and _not_ int */
 744                                 cast->flags = Int_const_expr | Float_literal;
 745                         return token;
 746                 }
 747         }
 748         return unary_expression(token, tree);
 749 }
 750
 751 /*
 752  * Generic left-to-right binop parsing
 753  *
 754  * This _really_ needs to be inlined, because that makes the inner
 755  * function call statically deterministic rather than a totally
 756  * unpredictable indirect call. But gcc-3 is so "clever" that it
 757  * doesn't do so by default even when you tell it to inline it.
 758  *
 759  * Making it a macro avoids the inlining problem, and also means
 760  * that we can pass in the op-comparison as an expression rather
 761  * than create a data structure for it.
 762  */
 763
 764 #define LR_BINOP_EXPRESSION(__token, tree, type, inner, compare)        \
 765         struct expression *left = NULL;                                 \
 766         struct token * next = inner(__token, &left);                    \
 767                                                                         \
 768         if (left) {                                                     \
 769                 while (token_type(next) == TOKEN_SPECIAL) {             \
 770                         struct expression *top, *right = NULL;          \
 771                         int op = next->special;                         \
 772                                                                         \
 773                         if (!(compare))                                 \
 774                                 goto out;                               \
 775                         top = alloc_expression(next->pos, type);        \
 776                         next = inner(next->next, &right);               \
 777                         if (!right) {                                   \
 778                                 sparse_error(next->pos, "No right hand side of '%s'-expression", show_special(op));     \
 779                                 break;                                  \
 780                         }                                               \
 781                         top->flags = left->flags & right->flags         \
 782                                                 & Int_const_expr;       \
 783                         top->op = op;                                   \
 784                         top->left = left;                               \
 785                         top->right = right;                             \
 786                         left = top;                                     \
 787                 }                                                       \
 788         }                                                               \
 789 out:                                                                    \
 790         *tree = left;                                                   \
 791         return next;                                                    \
 792
 793 static struct token *multiplicative_expression(struct token *token, struct expression **tree)
 794 {
 795         LR_BINOP_EXPRESSION(
 796                 token, tree, EXPR_BINOP, cast_expression,
 797                 (op == '*') || (op == '/') || (op == '%')
 798         );
 799 }
 800
 801 static struct token *additive_expression(struct token *token, struct expression **tree)
 802 {
 803         LR_BINOP_EXPRESSION(
 804                 token, tree, EXPR_BINOP, multiplicative_expression,
 805                 (op == '+') || (op == '-')
 806         );
 807 }
 808
 809 static struct token *shift_expression(struct token *token, struct expression **tree)
 810 {
 811         LR_BINOP_EXPRESSION(
 812                 token, tree, EXPR_BINOP, additive_expression,
 813                 (op == SPECIAL_LEFTSHIFT) || (op == SPECIAL_RIGHTSHIFT)
 814         );
 815 }
 816
 817 static struct token *relational_expression(struct token *token, struct expression **tree)
 818 {
 819         LR_BINOP_EXPRESSION(
 820                 token, tree, EXPR_COMPARE, shift_expression,
 821                 (op == '<') || (op == '>') ||
 822                 (op == SPECIAL_LTE) || (op == SPECIAL_GTE)
 823         );
 824 }
 825
 826 static struct token *equality_expression(struct token *token, struct expression **tree)
 827 {
 828         LR_BINOP_EXPRESSION(
 829                 token, tree, EXPR_COMPARE, relational_expression,
 830                 (op == SPECIAL_EQUAL) || (op == SPECIAL_NOTEQUAL)
 831         );
 832 }
 833
 834 static struct token *bitwise_and_expression(struct token *token, struct expression **tree)
 835 {
 836         LR_BINOP_EXPRESSION(
 837                 token, tree, EXPR_BINOP, equality_expression,
 838                 (op == '&')
 839         );
 840 }
 841
 842 static struct token *bitwise_xor_expression(struct token *token, struct expression **tree)
 843 {
 844         LR_BINOP_EXPRESSION(
 845                 token, tree, EXPR_BINOP, bitwise_and_expression,
 846                 (op == '^')
 847         );
 848 }
 849
 850 static struct token *bitwise_or_expression(struct token *token, struct expression **tree)
 851 {
 852         LR_BINOP_EXPRESSION(
 853                 token, tree, EXPR_BINOP, bitwise_xor_expression,
 854                 (op == '|')
 855         );
 856 }
 857
 858 static struct token *logical_and_expression(struct token *token, struct expression **tree)
 859 {
 860         LR_BINOP_EXPRESSION(
 861                 token, tree, EXPR_LOGICAL, bitwise_or_expression,
 862                 (op == SPECIAL_LOGICAL_AND)
 863         );
 864 }
 865
 866 static struct token *logical_or_expression(struct token *token, struct expression **tree)
 867 {
 868         LR_BINOP_EXPRESSION(
 869                 token, tree, EXPR_LOGICAL, logical_and_expression,
 870                 (op == SPECIAL_LOGICAL_OR)
 871         );
 872 }
 873
 874 struct token *conditional_expression(struct token *token, struct expression **tree)
 875 {
 876         token = logical_or_expression(token, tree);
 877         if (*tree && match_op(token, '?')) {
 878                 struct expression *expr = alloc_expression(token->pos, EXPR_CONDITIONAL);
 879                 expr->op = token->special;
 880                 expr->left = *tree;
 881                 *tree = expr;
 882                 token = parse_expression(token->next, &expr->cond_true);
 883                 token = expect(token, ':', "in conditional expression");
 884                 token = conditional_expression(token, &expr->cond_false);
 885                 if (expr->left && expr->cond_false) {
 886                         int is_const = expr->left->flags &
 887                                         expr->cond_false->flags &
 888                                         Int_const_expr;
 889                         if (expr->cond_true)
 890                                 is_const &= expr->cond_true->flags;
 891                         expr->flags = is_const;
 892                 }
 893         }
 894         return token;
 895 }
 896
 897 struct token *assignment_expression(struct token *token, struct expression **tree)
 898 {
 899         token = conditional_expression(token, tree);
 900         if (*tree && token_type(token) == TOKEN_SPECIAL) {
 901                 static const int assignments[] = {
 902                         '=',
 903                         SPECIAL_ADD_ASSIGN, SPECIAL_SUB_ASSIGN,
 904                         SPECIAL_MUL_ASSIGN, SPECIAL_DIV_ASSIGN,
 905                         SPECIAL_MOD_ASSIGN, SPECIAL_SHL_ASSIGN,
 906                         SPECIAL_SHR_ASSIGN, SPECIAL_AND_ASSIGN,
 907                         SPECIAL_OR_ASSIGN,  SPECIAL_XOR_ASSIGN };
 908                 int i, op = token->special;
 909                 for (i = 0; i < sizeof(assignments)/sizeof(int); i++)
 910                         if (assignments[i] == op) {
 911                                 struct expression * expr = alloc_expression(token->pos, EXPR_ASSIGNMENT);
 912                                 expr->left = *tree;
 913                                 expr->op = op;
 914                                 *tree = expr;
 915                                 return assignment_expression(token->next, &expr->right);
 916                         }
 917         }
 918         return token;
 919 }
 920
 921 static struct token *comma_expression(struct token *token, struct expression **tree)
 922 {
 923         LR_BINOP_EXPRESSION(
 924                 token, tree, EXPR_COMMA, assignment_expression,
 925                 (op == ',')
 926         );
 927 }
 928
 929 struct token *parse_expression(struct token *token, struct expression **tree)
 930 {
 931         return comma_expression(token,tree);
 932 }
 933
 934