expression.c

   1 /*
   2  * sparse/expression.c
   3  *
   4  * Copyright (C) 2003 Transmeta Corp.
   5  *               2003 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
  19 #include "lib.h"
  20 #include "token.h"
  21 #include "parse.h"
  22 #include "symbol.h"
  23 #include "scope.h"
  24 #include "expression.h"
  25 #include "target.h"
  26
  27 static int match_oplist(int op, ...)
  28 {
  29         va_list args;
  30
  31         va_start(args, op);
  32         for (;;) {
  33                 int nextop = va_arg(args, int);
  34                 if (!nextop)
  35                         return 0;
  36                 if (op == nextop)
  37                         return 1;
  38         }
  39 }
  40
  41 static struct token *comma_expression(struct token *, struct expression **);
  42
  43 struct token *parens_expression(struct token *token, struct expression **expr, const char *where)
  44 {
  45         token = expect(token, '(', where);
  46         if (match_op(token, '{')) {
  47                 struct expression *e = alloc_expression(token->pos, EXPR_STATEMENT);
  48                 struct statement *stmt = alloc_statement(token->pos, STMT_COMPOUND);
  49                 *expr = e;
  50                 e->statement = stmt;
  51                 start_symbol_scope();
  52                 token = compound_statement(token->next, stmt);
  53                 end_symbol_scope();
  54                 token = expect(token, '}', "at end of statement expression");
  55         } else
  56                 token = parse_expression(token, expr);
  57         return expect(token, ')', where);
  58 }
  59
  60 static struct token *string_expression(struct token *token, struct expression *expr)
  61 {
  62         struct string *string = token->string;
  63         struct token *next = token->next;
  64
  65         if (token_type(next) == TOKEN_STRING) {
  66                 int totlen = string->length;
  67                 char *data;
  68
  69                 do {
  70                         totlen += next->string->length-1;
  71                         next = next->next;
  72                 } while (token_type(next) == TOKEN_STRING);
  73
  74                 string = __alloc_string(totlen);
  75                 string->length = totlen;
  76                 data = string->data;
  77                 next = token;
  78                 do {
  79                         struct string *s = next->string;
  80                         int len = s->length;
  81
  82                         next = next->next;
  83                         memcpy(data, s->data, len);
  84                         data += len-1;
  85                 } while (token_type(next) == TOKEN_STRING);
  86         }
  87         expr->string = string;
  88         return next;
  89 }
  90
  91 static void get_fp_value(struct expression *expr, struct token *token)
  92 {
  93         static int fp_warned;
  94
  95         expr->ctype = &double_ctype;
  96         expr->value = 0;
  97         if (!fp_warned) {
  98                 warn(token->pos, "FP values not yet implemented");
  99                 fp_warned = 1;
 100         }
 101 }
 102
 103 static void get_number_value(struct expression *expr, struct token *token)
 104 {
 105         const char *str = token->number;
 106         unsigned long long value = 0;
 107         unsigned int base = 10, digit, bits;
 108         unsigned long modifiers, extramod;
 109
 110         if (str[0] == '0') {
 111                 switch (str[1]) {
 112                 case 'x': case 'X':
 113                         base = 18;      // the -= 2 for the octal case will
 114                         str++;          // skip the '0'
 115                 /* fallthrough */
 116                 case '0'...'7':
 117                         str++;          // skip the '0' or 'x/X'
 118                         base -= 2;      // the fall-through will make this 8
 119                 }
 120         }
 121         for (;;) {
 122                 char c = *str++;
 123                 if (c == '_')
 124                         continue;
 125                 digit = hexval(c);
 126                 if (digit >= base)
 127                         break;
 128                 value = value * base + digit;
 129         }
 130         str--;
 131         modifiers = 0;
 132         for (;;) {
 133                 char c = *str++;
 134                 if (c == 'u' || c == 'U') {
 135                         modifiers |= MOD_UNSIGNED;
 136                         continue;
 137                 }
 138                 if (c == 'l' || c == 'L') {
 139                         if (modifiers & MOD_LONG)
 140                                 modifiers |= MOD_LONGLONG;
 141                         modifiers |= MOD_LONG;
 142                         continue;
 143                 }
 144                 if (c) {
 145                         get_fp_value(expr, token);
 146                         return;
 147                 }
 148                 break;
 149         }
 150
 151         bits = bits_in_longlong;
 152         extramod = 0;
 153         if (!(modifiers & MOD_LONGLONG)) {
 154                 if (value & (~1ULL << (bits_in_long-1))) {
 155                         extramod = MOD_LONGLONG | MOD_LONG;
 156                 } else {
 157                         bits = bits_in_long;
 158                         if (!(modifiers & MOD_LONG)) {
 159                                 if (value & (~1ULL << (bits_in_int-1))) {
 160                                         extramod = MOD_LONG;
 161                                 } else
 162                                         bits = bits_in_int;
 163                         }
 164                 }
 165         }
 166         if (!(modifiers & MOD_UNSIGNED)) {
 167                 if (value & (1ULL << (bits-1))) {
 168                         extramod |= MOD_UNSIGNED;
 169                 }
 170         }
 171         if (extramod) {
 172                 /*
 173                  * Special case: "int" gets promoted directly to "long"
 174                  * for normal decimal numbers..
 175                  */
 176                 modifiers |= extramod;
 177                 if (base == 10 && modifiers == MOD_UNSIGNED) {
 178                         modifiers = MOD_LONG;
 179                         if (bits_in_long == bits_in_int)
 180                                 modifiers = MOD_LONG | MOD_UNSIGNED;
 181                 }
 182
 183                 /* Hex or octal constants don't complain about missing signedness */
 184                 if (base == 10 || extramod != MOD_UNSIGNED)
 185                         warn(expr->pos, "constant %s is so big it is%s%s%s",
 186                                 show_token(token),
 187                                 (modifiers & MOD_UNSIGNED) ? " unsigned":"",
 188                                 (modifiers & MOD_LONG) ? " long":"",
 189                                 (modifiers & MOD_LONGLONG) ? " long":"");
 190         }
 191
 192         expr->type = EXPR_VALUE;
 193         expr->ctype = ctype_integer(modifiers);
 194         expr->value = value;
 195 }
 196
 197 struct token *primary_expression(struct token *token, struct expression **tree)
 198 {
 199         struct expression *expr = NULL;
 200
 201         switch (token_type(token)) {
 202         case TOKEN_CHAR:
 203                 expr = alloc_expression(token->pos, EXPR_VALUE);
 204                 expr->ctype = &int_ctype;
 205                 expr->value = (unsigned char) token->character;
 206                 token = token->next;
 207                 break;
 208
 209         case TOKEN_NUMBER:
 210                 expr = alloc_expression(token->pos, EXPR_VALUE);
 211                 get_number_value(expr, token);
 212                 token = token->next;
 213                 break;
 214
 215         case TOKEN_IDENT: {
 216                 struct symbol *sym = lookup_symbol(token->ident, NS_SYMBOL | NS_TYPEDEF);
 217                 struct token *next = token->next;
 218
 219                 expr = alloc_expression(token->pos, EXPR_SYMBOL);
 220
 221                 /*
 222                  * We support types as real first-class citizens, with type
 223                  * comparisons etc:
 224                  *
 225                  *      if (typeof(a) == int) ..
 226                  */
 227                 if (sym && sym->namespace == NS_TYPEDEF) {
 228                         warn(token->pos, "typename in expression");
 229                         sym = NULL;
 230                 }
 231                 expr->symbol_name = token->ident;
 232                 expr->symbol = sym;
 233                 token = next;
 234                 break;
 235         }
 236
 237         case TOKEN_STRING: {
 238                 expr = alloc_expression(token->pos, EXPR_STRING);
 239                 token = string_expression(token, expr);
 240                 break;
 241         }
 242
 243         case TOKEN_SPECIAL:
 244                 if (token->special == '(') {
 245                         expr = alloc_expression(token->pos, EXPR_PREOP);
 246                         expr->op = '(';
 247                         token = parens_expression(token, &expr->unop, "in expression");
 248                         break;
 249                 }
 250                 if (token->special == '[' && lookup_type(token->next)) {
 251                         expr = alloc_expression(token->pos, EXPR_TYPE);
 252                         token = typename(token->next, &expr->symbol);
 253                         token = expect(token, ']', "in type expression");
 254                         break;
 255                 }
 256
 257         default:
 258                 ;
 259         }
 260         *tree = expr;
 261         return token;
 262 }
 263
 264 static struct token *expression_list(struct token *token, struct expression_list **list)
 265 {
 266         while (!match_op(token, ')')) {
 267                 struct expression *expr = NULL;
 268                 token = assignment_expression(token, &expr);
 269                 if (!expr)
 270                         break;
 271                 add_expression(list, expr);
 272                 if (!match_op(token, ','))
 273                         break;
 274                 token = token->next;
 275         }
 276         return token;
 277 }
 278
 279 /*
 280  * extend to deal with the ambiguous C grammar for parsing
 281  * a cast expressions followed by an initializer.
 282  */
 283 static struct token *postfix_expression(struct token *token, struct expression **tree, struct expression *cast_init_expr)
 284 {
 285         struct expression *expr = cast_init_expr;
 286
 287         if (!expr)
 288                 token = primary_expression(token, &expr);
 289
 290         while (expr && token_type(token) == TOKEN_SPECIAL) {
 291                 switch (token->special) {
 292                 case '[': {                     /* Array dereference */
 293                         struct expression *deref = alloc_expression(token->pos, EXPR_PREOP);
 294                         struct expression *add = alloc_expression(token->pos, EXPR_BINOP);
 295
 296                         deref->op = '*';
 297                         deref->unop = add;
 298
 299                         add->op = '+';
 300                         add->left = expr;
 301                         token = parse_expression(token->next, &add->right);
 302                         token = expect(token, ']', "at end of array dereference");
 303                         expr = deref;
 304                         continue;
 305                 }
 306                 case SPECIAL_INCREMENT:         /* Post-increment */
 307                 case SPECIAL_DECREMENT: {       /* Post-decrement */
 308                         struct expression *post = alloc_expression(token->pos, EXPR_POSTOP);
 309                         post->op = token->special;
 310                         post->unop = expr;
 311                         expr = post;
 312                         token = token->next;
 313                         continue;
 314                 }
 315                 case SPECIAL_DEREFERENCE: {     /* Structure pointer member dereference */
 316                         /* "x->y" is just shorthand for "(*x).y" */
 317                         struct expression *inner = alloc_expression(token->pos, EXPR_PREOP);
 318                         inner->op = '*';
 319                         inner->unop = expr;
 320                         expr = inner;
 321                 }
 322                 /* Fallthrough!! */
 323                 case '.': {                     /* Structure member dereference */
 324                         struct expression *deref = alloc_expression(token->pos, EXPR_DEREF);
 325                         deref->op = '.';
 326                         deref->deref = expr;
 327                         token = token->next;
 328                         if (token_type(token) != TOKEN_IDENT) {
 329                                 warn(token->pos, "Expected member name");
 330                                 break;
 331                         }
 332                         deref->member = token->ident;
 333                         token = token->next;
 334                         expr = deref;
 335                         continue;
 336                 }
 337
 338                 case '(': {                     /* Function call */
 339                         struct expression *call = alloc_expression(token->pos, EXPR_CALL);
 340                         call->op = '(';
 341                         call->fn = expr;
 342                         token = expression_list(token->next, &call->args);
 343                         token = expect(token, ')', "in function call");
 344                         expr = call;
 345                         continue;
 346                 }
 347
 348                 default:
 349                         break;
 350                 }
 351                 break;
 352         }
 353         *tree = expr;
 354         return token;
 355 }
 356
 357 static struct token *cast_expression(struct token *token, struct expression **tree);
 358 static struct token *unary_expression(struct token *token, struct expression **tree)
 359 {
 360         if (token_type(token) == TOKEN_IDENT &&
 361             (token->ident == &sizeof_ident ||
 362              token->ident == &__alignof___ident)) {
 363                 struct expression *sizeof_ex = alloc_expression(token->pos, EXPR_SIZEOF);
 364                 *tree = sizeof_ex;
 365                 tree = &sizeof_ex->unop;
 366                 token = token->next;
 367                 if (!match_op(token, '(') || !lookup_type(token->next))
 368                         return unary_expression(token, &sizeof_ex->cast_expression);
 369                 token = typename(token->next, &sizeof_ex->cast_type);
 370                 return expect(token, ')', "at end of sizeof type-name");
 371         }
 372
 373         if (token_type(token) == TOKEN_SPECIAL) {
 374                 if (match_oplist(token->special,
 375                     SPECIAL_INCREMENT, SPECIAL_DECREMENT,
 376                     '&', '*', '+', '-', '~', '!', 0)) {
 377                         struct expression *unop;
 378                         struct expression *unary;
 379                         struct token *next;
 380
 381                         next = cast_expression(token->next, &unop);
 382                         if (!unop) {
 383                                 warn(token->pos, "Syntax error in unary expression");
 384                                 return next;
 385                         }
 386                         unary = alloc_expression(token->pos, EXPR_PREOP);
 387                         unary->op = token->special;
 388                         unary->unop = unop;
 389                         *tree = unary;
 390                         return next;
 391                 }
 392
 393                 /* Gcc extension: &&label gives the address of a label */
 394                 if (match_op(token, SPECIAL_LOGICAL_AND) &&
 395                     token_type(token->next) == TOKEN_IDENT) {
 396                         struct expression *label = alloc_expression(token->pos, EXPR_LABEL);
 397                         label->label_symbol = label_symbol(token->next);
 398                         *tree = label;
 399                         return token->next->next;
 400                 }
 401
 402         }
 403
 404         return postfix_expression(token, tree, NULL);
 405 }
 406
 407 /*
 408  * Ambiguity: a '(' can be either a cast-expression or
 409  * a primary-expression depending on whether it is followed
 410  * by a type or not.
 411  *
 412  * additional ambiguity: a "cast expression" followed by
 413  * an initializer is really a postfix-expression.
 414  */
 415 static struct token *cast_expression(struct token *token, struct expression **tree)
 416 {
 417         if (match_op(token, '(')) {
 418                 struct token *next = token->next;
 419                 if (lookup_type(next)) {
 420                         struct expression *cast = alloc_expression(next->pos, EXPR_CAST);
 421                         struct symbol *sym;
 422
 423                         token = typename(next, &sym);
 424                         cast->cast_type = sym;
 425                         token = expect(token, ')', "at end of cast operator");
 426                         if (match_op(token, '{')) {
 427                                 token = initializer(&cast->cast_expression, token);
 428                                 return postfix_expression(token, tree, cast);
 429                         }
 430                         *tree = cast;
 431                         token = cast_expression(token, &cast->cast_expression);
 432                         return token;
 433                 }
 434         }
 435         return unary_expression(token, tree);
 436 }
 437
 438 /* Generic left-to-right binop parsing */
 439 static struct token *lr_binop_expression(struct token *token, struct expression **tree,
 440         enum expression_type type, struct token *(*inner)(struct token *, struct expression **), ...)
 441 {
 442         struct expression *left = NULL;
 443         struct token * next = inner(token, &left);
 444
 445         if (left) {
 446                 while (token_type(next) == TOKEN_SPECIAL) {
 447                         struct expression *top, *right = NULL;
 448                         int op = next->special;
 449                         va_list args;
 450
 451                         va_start(args, inner);
 452                         for (;;) {
 453                                 int nextop = va_arg(args, int);
 454                                 if (!nextop)
 455                                         goto out;
 456                                 if (op == nextop)
 457                                         break;
 458                         }
 459                         va_end(args);
 460                         top = alloc_expression(next->pos, type);
 461                         next = inner(next->next, &right);
 462                         if (!right) {
 463                                 warn(next->pos, "No right hand side of '%s'-expression", show_special(op));
 464                                 break;
 465                         }
 466                         top->op = op;
 467                         top->left = left;
 468                         top->right = right;
 469                         left = top;
 470                 }
 471         }
 472 out:
 473         *tree = left;
 474         return next;
 475 }
 476
 477 static struct token *multiplicative_expression(struct token *token, struct expression **tree)
 478 {
 479         return lr_binop_expression(token, tree, EXPR_BINOP, cast_expression, '*', '/', '%', 0);
 480 }
 481
 482 static struct token *additive_expression(struct token *token, struct expression **tree)
 483 {
 484         return lr_binop_expression(token, tree, EXPR_BINOP, multiplicative_expression, '+', '-', 0);
 485 }
 486
 487 static struct token *shift_expression(struct token *token, struct expression **tree)
 488 {
 489         return lr_binop_expression(token, tree, EXPR_BINOP, additive_expression, SPECIAL_LEFTSHIFT, SPECIAL_RIGHTSHIFT, 0);
 490 }
 491
 492 static struct token *relational_expression(struct token *token, struct expression **tree)
 493 {
 494         return lr_binop_expression(token, tree, EXPR_COMPARE, shift_expression, '<', '>', SPECIAL_LTE, SPECIAL_GTE, 0);
 495 }
 496
 497 static struct token *equality_expression(struct token *token, struct expression **tree)
 498 {
 499         return lr_binop_expression(token, tree, EXPR_COMPARE, relational_expression, SPECIAL_EQUAL, SPECIAL_NOTEQUAL, 0);
 500 }
 501
 502 static struct token *bitwise_and_expression(struct token *token, struct expression **tree)
 503 {
 504         return lr_binop_expression(token, tree, EXPR_BINOP, equality_expression, '&', 0);
 505 }
 506
 507 static struct token *bitwise_xor_expression(struct token *token, struct expression **tree)
 508 {
 509         return lr_binop_expression(token, tree, EXPR_BINOP, bitwise_and_expression, '^', 0);
 510 }
 511
 512 static struct token *bitwise_or_expression(struct token *token, struct expression **tree)
 513 {
 514         return lr_binop_expression(token, tree, EXPR_BINOP, bitwise_xor_expression, '|', 0);
 515 }
 516
 517 static struct token *logical_and_expression(struct token *token, struct expression **tree)
 518 {
 519         return lr_binop_expression(token, tree, EXPR_LOGICAL, bitwise_or_expression, SPECIAL_LOGICAL_AND, 0);
 520 }
 521
 522 static struct token *logical_or_expression(struct token *token, struct expression **tree)
 523 {
 524         return lr_binop_expression(token, tree, EXPR_LOGICAL, logical_and_expression, SPECIAL_LOGICAL_OR, 0);
 525 }
 526
 527 struct token *conditional_expression(struct token *token, struct expression **tree)
 528 {
 529         token = logical_or_expression(token, tree);
 530         if (match_op(token, '?')) {
 531                 struct expression *expr = alloc_expression(token->pos, EXPR_CONDITIONAL);
 532                 expr->op = token->special;
 533                 expr->left = *tree;
 534                 *tree = expr;
 535                 token = parse_expression(token->next, &expr->cond_true);
 536                 token = expect(token, ':', "in conditional expression");
 537                 token = conditional_expression(token, &expr->cond_false);
 538         }
 539         return token;
 540 }
 541
 542 struct token *assignment_expression(struct token *token, struct expression **tree)
 543 {
 544         token = conditional_expression(token, tree);
 545         if (token_type(token) == TOKEN_SPECIAL) {
 546                 static const int assignments[] = {
 547                         '=',
 548                         SPECIAL_ADD_ASSIGN, SPECIAL_SUB_ASSIGN,
 549                         SPECIAL_MUL_ASSIGN, SPECIAL_DIV_ASSIGN,
 550                         SPECIAL_MOD_ASSIGN, SPECIAL_SHL_ASSIGN,
 551                         SPECIAL_SHR_ASSIGN, SPECIAL_AND_ASSIGN,
 552                         SPECIAL_OR_ASSIGN,  SPECIAL_XOR_ASSIGN };
 553                 int i, op = token->special;
 554                 for (i = 0; i < sizeof(assignments)/sizeof(int); i++)
 555                         if (assignments[i] == op) {
 556                                 struct expression * expr = alloc_expression(token->pos, EXPR_ASSIGNMENT);
 557                                 expr->left = *tree;
 558                                 expr->op = op;
 559                                 *tree = expr;
 560                                 return assignment_expression(token->next, &expr->right);
 561                         }
 562         }
 563         return token;
 564 }
 565
 566 static struct token *comma_expression(struct token *token, struct expression **tree)
 567 {
 568         return lr_binop_expression(token, tree, EXPR_COMMA, assignment_expression, ',', 0);
 569 }
 570
 571 struct token *parse_expression(struct token *token, struct expression **tree)
 572 {
 573         return comma_expression(token,tree);
 574 }
 575
 576