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(e->pos);
  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, NULL);
 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, NULL);
 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         int stringtype = token_type(token);
 228
 229         convert_function(token);
 230
 231         if (token_type(next) == stringtype) {
 232                 int totlen = string->length-1;
 233                 char *data;
 234
 235                 do {
 236                         totlen += next->string->length-1;
 237                         next = next->next;
 238                 } while (token_type(next) == stringtype);
 239
 240                 if (totlen > MAX_STRING) {
 241                         warning(token->pos, "trying to concatenate %d-character string (%d bytes max)", totlen, MAX_STRING);
 242                         totlen = MAX_STRING;
 243                 }
 244
 245                 string = __alloc_string(totlen+1);
 246                 string->length = totlen+1;
 247                 data = string->data;
 248                 next = token;
 249                 do {
 250                         struct string *s = next->string;
 251                         int len = s->length-1;
 252
 253                         if (len > totlen)
 254                                 len = totlen;
 255                         totlen -= len;
 256
 257                         next = next->next;
 258                         memcpy(data, s->data, len);
 259                         data += len;
 260                 } while (token_type(next) == stringtype);
 261                 *data = '\0';
 262         }
 263         expr->string = string;
 264         return next;
 265 }
 266
 267 #ifndef ULLONG_MAX
 268 #define ULLONG_MAX (~0ULL)
 269 #endif
 270
 271 static void get_number_value(struct expression *expr, struct token *token)
 272 {
 273         const char *str = token->number;
 274         unsigned long long value;
 275         char *end;
 276         int size = 0, want_unsigned = 0;
 277         int overflow = 0, do_warn = 0;
 278         int try_unsigned = 1;
 279         int bits;
 280
 281         errno = 0;
 282         value = strtoull(str, &end, 0);
 283         if (end == str)
 284                 goto Float;
 285         if (value == ULLONG_MAX && errno == ERANGE)
 286                 overflow = 1;
 287         while (1) {
 288                 char c = *end++;
 289                 if (!c) {
 290                         break;
 291                 } else if (c == 'u' || c == 'U') {
 292                         if (want_unsigned)
 293                                 goto Enoint;
 294                         want_unsigned = 1;
 295                 } else if (c == 'l' || c == 'L') {
 296                         if (size)
 297                                 goto Enoint;
 298                         size = 1;
 299                         if (*end == c) {
 300                                 size = 2;
 301                                 end++;
 302                         }
 303                 } else
 304                         goto Float;
 305         }
 306         if (overflow)
 307                 goto Eoverflow;
 308         /* OK, it's a valid integer */
 309         /* decimals can be unsigned only if directly specified as such */
 310         if (str[0] != '0' && !want_unsigned)
 311                 try_unsigned = 0;
 312         if (!size) {
 313                 bits = bits_in_int - 1;
 314                 if (!(value & (~1ULL << bits))) {
 315                         if (!(value & (1ULL << bits))) {
 316                                 goto got_it;
 317                         } else if (try_unsigned) {
 318                                 want_unsigned = 1;
 319                                 goto got_it;
 320                         }
 321                 }
 322                 size = 1;
 323                 do_warn = 1;
 324         }
 325         if (size < 2) {
 326                 bits = bits_in_long - 1;
 327                 if (!(value & (~1ULL << bits))) {
 328                         if (!(value & (1ULL << bits))) {
 329                                 goto got_it;
 330                         } else if (try_unsigned) {
 331                                 want_unsigned = 1;
 332                                 goto got_it;
 333                         }
 334                         do_warn |= 2;
 335                 }
 336                 size = 2;
 337                 do_warn |= 1;
 338         }
 339         bits = bits_in_longlong - 1;
 340         if (value & (~1ULL << bits))
 341                 goto Eoverflow;
 342         if (!(value & (1ULL << bits)))
 343                 goto got_it;
 344         if (!try_unsigned)
 345                 warning(expr->pos, "decimal constant %s is too big for long long",
 346                         show_token(token));
 347         want_unsigned = 1;
 348 got_it:
 349         if (do_warn)
 350                 warning(expr->pos, "constant %s is so big it is%s%s%s",
 351                         show_token(token),
 352                         want_unsigned ? " unsigned":"",
 353                         size > 0 ? " long":"",
 354                         size > 1 ? " long":"");
 355         if (do_warn & 2)
 356                 warning(expr->pos,
 357                         "decimal constant %s is between LONG_MAX and ULONG_MAX."
 358                         " For C99 that means long long, C90 compilers are very "
 359                         "likely to produce unsigned long (and a warning) here",
 360                         show_token(token));
 361         expr->type = EXPR_VALUE;
 362         expr->flags = Int_const_expr;
 363         expr->ctype = ctype_integer(size, want_unsigned);
 364         expr->value = value;
 365         return;
 366 Eoverflow:
 367         error_die(expr->pos, "constant %s is too big even for unsigned long long",
 368                         show_token(token));
 369         return;
 370 Float:
 371         expr->fvalue = string_to_ld(str, &end);
 372         if (str == end)
 373                 goto Enoint;
 374
 375         if (*end && end[1])
 376                 goto Enoint;
 377
 378         if (*end == 'f' || *end == 'F')
 379                 expr->ctype = &float_ctype;
 380         else if (*end == 'l' || *end == 'L')
 381                 expr->ctype = &ldouble_ctype;
 382         else if (!*end)
 383                 expr->ctype = &double_ctype;
 384         else
 385                 goto Enoint;
 386
 387         expr->flags = Float_literal;
 388         expr->type = EXPR_FVALUE;
 389         return;
 390
 391 Enoint:
 392         error_die(expr->pos, "constant %s is not a valid number", show_token(token));
 393 }
 394
 395 struct token *primary_expression(struct token *token, struct expression **tree)
 396 {
 397         struct expression *expr = NULL;
 398
 399         switch (token_type(token)) {
 400         case TOKEN_CHAR:
 401         case TOKEN_WIDE_CHAR:
 402                 expr = alloc_expression(token->pos, EXPR_VALUE);
 403                 expr->flags = Int_const_expr;
 404                 expr->ctype = token_type(token) == TOKEN_CHAR ? &int_ctype : &long_ctype;
 405                 expr->value = (unsigned char) token->character;
 406                 token = token->next;
 407                 break;
 408
 409         case TOKEN_NUMBER:
 410                 expr = alloc_expression(token->pos, EXPR_VALUE);
 411                 get_number_value(expr, token); /* will see if it's an integer */
 412                 token = token->next;
 413                 break;
 414
 415         case TOKEN_ZERO_IDENT: {
 416                 expr = alloc_expression(token->pos, EXPR_SYMBOL);
 417                 expr->flags = Int_const_expr;
 418                 expr->ctype = &int_ctype;
 419                 expr->symbol = &zero_int;
 420                 expr->symbol_name = token->ident;
 421                 token = token->next;
 422                 break;
 423         }
 424
 425         case TOKEN_IDENT: {
 426                 struct symbol *sym = lookup_symbol(token->ident, NS_SYMBOL | NS_TYPEDEF);
 427                 struct token *next = token->next;
 428
 429                 if (!sym) {
 430                         if (convert_function(token))
 431                                 goto handle_string;
 432                         if (token->ident == &__builtin_types_compatible_p_ident) {
 433                                 token = builtin_types_compatible_p_expr(token, &expr);
 434                                 break;
 435                         }
 436                         if (token->ident == &__builtin_offsetof_ident) {
 437                                 token = builtin_offsetof_expr(token, &expr);
 438                                 break;
 439                         }
 440                 } else if (sym->enum_member) {
 441                         expr = alloc_expression(token->pos, EXPR_VALUE);
 442                         *expr = *sym->initializer;
 443                         /* we want the right position reported, thus the copy */
 444                         expr->pos = token->pos;
 445                         expr->flags = Int_const_expr;
 446                         token = next;
 447                         break;
 448                 }
 449
 450                 expr = alloc_expression(token->pos, EXPR_SYMBOL);
 451
 452                 /*
 453                  * We support types as real first-class citizens, with type
 454                  * comparisons etc:
 455                  *
 456                  *      if (typeof(a) == int) ..
 457                  */
 458                 if (sym && sym->namespace == NS_TYPEDEF) {
 459                         sparse_error(token->pos, "typename in expression");
 460                         sym = NULL;
 461                 }
 462                 expr->symbol_name = token->ident;
 463                 expr->symbol = sym;
 464                 token = next;
 465                 break;
 466         }
 467
 468         case TOKEN_STRING:
 469         case TOKEN_WIDE_STRING: {
 470         handle_string:
 471                 expr = alloc_expression(token->pos, EXPR_STRING);
 472                 expr->wide = token_type(token) == TOKEN_WIDE_STRING;
 473                 token = string_expression(token, expr);
 474                 break;
 475         }
 476
 477         case TOKEN_SPECIAL:
 478                 if (token->special == '(') {
 479                         expr = alloc_expression(token->pos, EXPR_PREOP);
 480                         expr->op = '(';
 481                         token = parens_expression(token, &expr->unop, "in expression");
 482                         if (expr->unop)
 483                                 expr->flags = expr->unop->flags;
 484                         break;
 485                 }
 486                 if (token->special == '[' && lookup_type(token->next)) {
 487                         expr = alloc_expression(token->pos, EXPR_TYPE);
 488                         expr->flags = Int_const_expr; /* sic */
 489                         token = typename(token->next, &expr->symbol, NULL);
 490                         token = expect(token, ']', "in type expression");
 491                         break;
 492                 }
 493
 494         default:
 495                 ;
 496         }
 497         *tree = expr;
 498         return token;
 499 }
 500
 501 static struct token *expression_list(struct token *token, struct expression_list **list)
 502 {
 503         while (!match_op(token, ')')) {
 504                 struct expression *expr = NULL;
 505                 token = assignment_expression(token, &expr);
 506                 if (!expr)
 507                         break;
 508                 add_expression(list, expr);
 509                 if (!match_op(token, ','))
 510                         break;
 511                 token = token->next;
 512         }
 513         return token;
 514 }
 515
 516 /*
 517  * extend to deal with the ambiguous C grammar for parsing
 518  * a cast expressions followed by an initializer.
 519  */
 520 static struct token *postfix_expression(struct token *token, struct expression **tree, struct expression *cast_init_expr)
 521 {
 522         struct expression *expr = cast_init_expr;
 523
 524         if (!expr)
 525                 token = primary_expression(token, &expr);
 526
 527         while (expr && token_type(token) == TOKEN_SPECIAL) {
 528                 switch (token->special) {
 529                 case '[': {                     /* Array dereference */
 530                         struct expression *deref = alloc_expression(token->pos, EXPR_PREOP);
 531                         struct expression *add = alloc_expression(token->pos, EXPR_BINOP);
 532
 533                         deref->op = '*';
 534                         deref->unop = add;
 535
 536                         add->op = '+';
 537                         add->left = expr;
 538                         token = parse_expression(token->next, &add->right);
 539                         token = expect(token, ']', "at end of array dereference");
 540                         expr = deref;
 541                         continue;
 542                 }
 543                 case SPECIAL_INCREMENT:         /* Post-increment */
 544                 case SPECIAL_DECREMENT: {       /* Post-decrement */
 545                         struct expression *post = alloc_expression(token->pos, EXPR_POSTOP);
 546                         post->op = token->special;
 547                         post->unop = expr;
 548                         expr = post;
 549                         token = token->next;
 550                         continue;
 551                 }
 552                 case SPECIAL_DEREFERENCE: {     /* Structure pointer member dereference */
 553                         /* "x->y" is just shorthand for "(*x).y" */
 554                         struct expression *inner = alloc_expression(token->pos, EXPR_PREOP);
 555                         inner->op = '*';
 556                         inner->unop = expr;
 557                         expr = inner;
 558                 }
 559                 /* Fall through!! */
 560                 case '.': {                     /* Structure member dereference */
 561                         struct expression *deref = alloc_expression(token->pos, EXPR_DEREF);
 562                         deref->op = '.';
 563                         deref->deref = expr;
 564                         token = token->next;
 565                         if (token_type(token) != TOKEN_IDENT) {
 566                                 sparse_error(token->pos, "Expected member name");
 567                                 break;
 568                         }
 569                         deref->member = token->ident;
 570                         token = token->next;
 571                         expr = deref;
 572                         continue;
 573                 }
 574
 575                 case '(': {                     /* Function call */
 576                         struct expression *call = alloc_expression(token->pos, EXPR_CALL);
 577                         call->op = '(';
 578                         call->fn = expr;
 579                         token = expression_list(token->next, &call->args);
 580                         token = expect(token, ')', "in function call");
 581                         expr = call;
 582                         continue;
 583                 }
 584
 585                 default:
 586                         break;
 587                 }
 588                 break;
 589         }
 590         *tree = expr;
 591         return token;
 592 }
 593
 594 static struct token *cast_expression(struct token *token, struct expression **tree);
 595 static struct token *unary_expression(struct token *token, struct expression **tree);
 596
 597 static struct token *type_info_expression(struct token *token,
 598         struct expression **tree, int type)
 599 {
 600         struct expression *expr = alloc_expression(token->pos, type);
 601         struct token *p;
 602
 603         *tree = expr;
 604         expr->flags = Int_const_expr; /* XXX: VLA support will need that changed */
 605         token = token->next;
 606         if (!match_op(token, '(') || !lookup_type(token->next))
 607                 return unary_expression(token, &expr->cast_expression);
 608         p = token;
 609         token = typename(token->next, &expr->cast_type, NULL);
 610
 611         if (!match_op(token, ')')) {
 612                 static const char * error[] = {
 613                         [EXPR_SIZEOF] = "at end of sizeof",
 614                         [EXPR_ALIGNOF] = "at end of __alignof__",
 615                         [EXPR_PTRSIZEOF] = "at end of __sizeof_ptr__"
 616                 };
 617                 return expect(token, ')', error[type]);
 618         }
 619
 620         token = token->next;
 621         /*
 622          * C99 ambiguity: the typename might have been the beginning
 623          * of a typed initializer expression..
 624          */
 625         if (match_op(token, '{')) {
 626                 struct expression *cast = alloc_expression(p->pos, EXPR_CAST);
 627                 cast->cast_type = expr->cast_type;
 628                 expr->cast_type = NULL;
 629                 expr->cast_expression = cast;
 630                 token = initializer(&cast->cast_expression, token);
 631                 token = postfix_expression(token, &expr->cast_expression, cast);
 632         }
 633         return token;
 634 }
 635
 636 static struct token *unary_expression(struct token *token, struct expression **tree)
 637 {
 638         if (token_type(token) == TOKEN_IDENT) {
 639                 struct ident *ident = token->ident;
 640                 if (ident->reserved) {
 641                         static const struct {
 642                                 struct ident *id;
 643                                 int type;
 644                         } type_information[] = {
 645                                 { &sizeof_ident, EXPR_SIZEOF },
 646                                 { &__alignof___ident, EXPR_ALIGNOF },
 647                                 { &__alignof_ident, EXPR_ALIGNOF },
 648                                 { &__sizeof_ptr___ident, EXPR_PTRSIZEOF },
 649                         };
 650                         int i;
 651                         for (i = 0; i < 3; i++) {
 652                                 if (ident == type_information[i].id)
 653                                         return type_info_expression(token, tree, type_information[i].type);
 654                         }
 655                 }
 656         }
 657
 658         if (token_type(token) == TOKEN_SPECIAL) {
 659                 if (match_oplist(token->special,
 660                     SPECIAL_INCREMENT, SPECIAL_DECREMENT,
 661                     '&', '*', 0)) {
 662                         struct expression *unop;
 663                         struct expression *unary;
 664                         struct token *next;
 665
 666                         next = cast_expression(token->next, &unop);
 667                         if (!unop) {
 668                                 sparse_error(token->pos, "Syntax error in unary expression");
 669                                 *tree = NULL;
 670                                 return next;
 671                         }
 672                         unary = alloc_expression(token->pos, EXPR_PREOP);
 673                         unary->op = token->special;
 674                         unary->unop = unop;
 675                         *tree = unary;
 676                         return next;
 677                 }
 678                 /* possibly constant ones */
 679                 if (match_oplist(token->special, '+', '-', '~', '!', 0)) {
 680                         struct expression *unop;
 681                         struct expression *unary;
 682                         struct token *next;
 683
 684                         next = cast_expression(token->next, &unop);
 685                         if (!unop) {
 686                                 sparse_error(token->pos, "Syntax error in unary expression");
 687                                 *tree = NULL;
 688                                 return next;
 689                         }
 690                         unary = alloc_expression(token->pos, EXPR_PREOP);
 691                         unary->op = token->special;
 692                         unary->unop = unop;
 693                         unary->flags = unop->flags & Int_const_expr;
 694                         *tree = unary;
 695                         return next;
 696                 }
 697                 /* Gcc extension: &&label gives the address of a label */
 698                 if (match_op(token, SPECIAL_LOGICAL_AND) &&
 699                     token_type(token->next) == TOKEN_IDENT) {
 700                         struct expression *label = alloc_expression(token->pos, EXPR_LABEL);
 701                         struct symbol *sym = label_symbol(token->next);
 702                         if (!(sym->ctype.modifiers & MOD_ADDRESSABLE)) {
 703                                 sym->ctype.modifiers |= MOD_ADDRESSABLE;
 704                                 add_symbol(&function_computed_target_list, sym);
 705                         }
 706                         label->label_symbol = sym;
 707                         *tree = label;
 708                         return token->next->next;
 709                 }
 710
 711         }
 712
 713         return postfix_expression(token, tree, NULL);
 714 }
 715
 716 /*
 717  * Ambiguity: a '(' can be either a cast-expression or
 718  * a primary-expression depending on whether it is followed
 719  * by a type or not.
 720  *
 721  * additional ambiguity: a "cast expression" followed by
 722  * an initializer is really a postfix-expression.
 723  */
 724 static struct token *cast_expression(struct token *token, struct expression **tree)
 725 {
 726         if (match_op(token, '(')) {
 727                 struct token *next = token->next;
 728                 if (lookup_type(next)) {
 729                         struct expression *cast = alloc_expression(next->pos, EXPR_CAST);
 730                         struct expression *v;
 731                         struct symbol *sym;
 732                         int is_force;
 733
 734                         token = typename(next, &sym, &is_force);
 735                         cast->cast_type = sym;
 736                         token = expect(token, ')', "at end of cast operator");
 737                         if (match_op(token, '{')) {
 738                                 if (is_force)
 739                                         warning(sym->pos,
 740                                                 "[force] in compound literal");
 741                                 token = initializer(&cast->cast_expression, token);
 742                                 return postfix_expression(token, tree, cast);
 743                         }
 744                         *tree = cast;
 745                         if (is_force)
 746                                 cast->type = EXPR_FORCE_CAST;
 747                         token = cast_expression(token, &v);
 748                         if (!v)
 749                                 return token;
 750                         cast->cast_expression = v;
 751                         if (v->flags & Int_const_expr)
 752                                 cast->flags = Int_const_expr;
 753                         else if (v->flags & Float_literal) /* and _not_ int */
 754                                 cast->flags = Int_const_expr | Float_literal;
 755                         return token;
 756                 }
 757         }
 758         return unary_expression(token, tree);
 759 }
 760
 761 /*
 762  * Generic left-to-right binop parsing
 763  *
 764  * This _really_ needs to be inlined, because that makes the inner
 765  * function call statically deterministic rather than a totally
 766  * unpredictable indirect call. But gcc-3 is so "clever" that it
 767  * doesn't do so by default even when you tell it to inline it.
 768  *
 769  * Making it a macro avoids the inlining problem, and also means
 770  * that we can pass in the op-comparison as an expression rather
 771  * than create a data structure for it.
 772  */
 773
 774 #define LR_BINOP_EXPRESSION(__token, tree, type, inner, compare)        \
 775         struct expression *left = NULL;                                 \
 776         struct token * next = inner(__token, &left);                    \
 777                                                                         \
 778         if (left) {                                                     \
 779                 while (token_type(next) == TOKEN_SPECIAL) {             \
 780                         struct expression *top, *right = NULL;          \
 781                         int op = next->special;                         \
 782                                                                         \
 783                         if (!(compare))                                 \
 784                                 goto out;                               \
 785                         top = alloc_expression(next->pos, type);        \
 786                         next = inner(next->next, &right);               \
 787                         if (!right) {                                   \
 788                                 sparse_error(next->pos, "No right hand side of '%s'-expression", show_special(op));     \
 789                                 break;                                  \
 790                         }                                               \
 791                         top->flags = left->flags & right->flags         \
 792                                                 & Int_const_expr;       \
 793                         top->op = op;                                   \
 794                         top->left = left;                               \
 795                         top->right = right;                             \
 796                         left = top;                                     \
 797                 }                                                       \
 798         }                                                               \
 799 out:                                                                    \
 800         *tree = left;                                                   \
 801         return next;                                                    \
 802
 803 static struct token *multiplicative_expression(struct token *token, struct expression **tree)
 804 {
 805         LR_BINOP_EXPRESSION(
 806                 token, tree, EXPR_BINOP, cast_expression,
 807                 (op == '*') || (op == '/') || (op == '%')
 808         );
 809 }
 810
 811 static struct token *additive_expression(struct token *token, struct expression **tree)
 812 {
 813         LR_BINOP_EXPRESSION(
 814                 token, tree, EXPR_BINOP, multiplicative_expression,
 815                 (op == '+') || (op == '-')
 816         );
 817 }
 818
 819 static struct token *shift_expression(struct token *token, struct expression **tree)
 820 {
 821         LR_BINOP_EXPRESSION(
 822                 token, tree, EXPR_BINOP, additive_expression,
 823                 (op == SPECIAL_LEFTSHIFT) || (op == SPECIAL_RIGHTSHIFT)
 824         );
 825 }
 826
 827 static struct token *relational_expression(struct token *token, struct expression **tree)
 828 {
 829         LR_BINOP_EXPRESSION(
 830                 token, tree, EXPR_COMPARE, shift_expression,
 831                 (op == '<') || (op == '>') ||
 832                 (op == SPECIAL_LTE) || (op == SPECIAL_GTE)
 833         );
 834 }
 835
 836 static struct token *equality_expression(struct token *token, struct expression **tree)
 837 {
 838         LR_BINOP_EXPRESSION(
 839                 token, tree, EXPR_COMPARE, relational_expression,
 840                 (op == SPECIAL_EQUAL) || (op == SPECIAL_NOTEQUAL)
 841         );
 842 }
 843
 844 static struct token *bitwise_and_expression(struct token *token, struct expression **tree)
 845 {
 846         LR_BINOP_EXPRESSION(
 847                 token, tree, EXPR_BINOP, equality_expression,
 848                 (op == '&')
 849         );
 850 }
 851
 852 static struct token *bitwise_xor_expression(struct token *token, struct expression **tree)
 853 {
 854         LR_BINOP_EXPRESSION(
 855                 token, tree, EXPR_BINOP, bitwise_and_expression,
 856                 (op == '^')
 857         );
 858 }
 859
 860 static struct token *bitwise_or_expression(struct token *token, struct expression **tree)
 861 {
 862         LR_BINOP_EXPRESSION(
 863                 token, tree, EXPR_BINOP, bitwise_xor_expression,
 864                 (op == '|')
 865         );
 866 }
 867
 868 static struct token *logical_and_expression(struct token *token, struct expression **tree)
 869 {
 870         LR_BINOP_EXPRESSION(
 871                 token, tree, EXPR_LOGICAL, bitwise_or_expression,
 872                 (op == SPECIAL_LOGICAL_AND)
 873         );
 874 }
 875
 876 static struct token *logical_or_expression(struct token *token, struct expression **tree)
 877 {
 878         LR_BINOP_EXPRESSION(
 879                 token, tree, EXPR_LOGICAL, logical_and_expression,
 880                 (op == SPECIAL_LOGICAL_OR)
 881         );
 882 }
 883
 884 struct token *conditional_expression(struct token *token, struct expression **tree)
 885 {
 886         token = logical_or_expression(token, tree);
 887         if (*tree && match_op(token, '?')) {
 888                 struct expression *expr = alloc_expression(token->pos, EXPR_CONDITIONAL);
 889                 expr->op = token->special;
 890                 expr->left = *tree;
 891                 *tree = expr;
 892                 token = parse_expression(token->next, &expr->cond_true);
 893                 token = expect(token, ':', "in conditional expression");
 894                 token = conditional_expression(token, &expr->cond_false);
 895                 if (expr->left && expr->cond_false) {
 896                         int is_const = expr->left->flags &
 897                                         expr->cond_false->flags &
 898                                         Int_const_expr;
 899                         if (expr->cond_true)
 900                                 is_const &= expr->cond_true->flags;
 901                         expr->flags = is_const;
 902                 }
 903         }
 904         return token;
 905 }
 906
 907 struct token *assignment_expression(struct token *token, struct expression **tree)
 908 {
 909         token = conditional_expression(token, tree);
 910         if (*tree && token_type(token) == TOKEN_SPECIAL) {
 911                 static const int assignments[] = {
 912                         '=',
 913                         SPECIAL_ADD_ASSIGN, SPECIAL_SUB_ASSIGN,
 914                         SPECIAL_MUL_ASSIGN, SPECIAL_DIV_ASSIGN,
 915                         SPECIAL_MOD_ASSIGN, SPECIAL_SHL_ASSIGN,
 916                         SPECIAL_SHR_ASSIGN, SPECIAL_AND_ASSIGN,
 917                         SPECIAL_OR_ASSIGN,  SPECIAL_XOR_ASSIGN };
 918                 int i, op = token->special;
 919                 for (i = 0; i < sizeof(assignments)/sizeof(int); i++)
 920                         if (assignments[i] == op) {
 921                                 struct expression * expr = alloc_expression(token->pos, EXPR_ASSIGNMENT);
 922                                 expr->left = *tree;
 923                                 expr->op = op;
 924                                 *tree = expr;
 925                                 return assignment_expression(token->next, &expr->right);
 926                         }
 927         }
 928         return token;
 929 }
 930
 931 static struct token *comma_expression(struct token *token, struct expression **tree)
 932 {
 933         LR_BINOP_EXPRESSION(
 934                 token, tree, EXPR_COMMA, assignment_expression,
 935                 (op == ',')
 936         );
 937 }
 938
 939 struct token *parse_expression(struct token *token, struct expression **tree)
 940 {
 941         return comma_expression(token,tree);
 942 }
 943
 944