1 /* Parse expressions for GDB. 2 3 Copyright (C) 1986, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 4 1998, 1999, 2000, 2001, 2004, 2005, 2007, 2008, 2009 5 Free Software Foundation, Inc. 6 7 Modified from expread.y by the Department of Computer Science at the 8 State University of New York at Buffalo, 1991. 9 10 This file is part of GDB. 11 12 This program is free software; you can redistribute it and/or modify 13 it under the terms of the GNU General Public License as published by 14 the Free Software Foundation; either version 3 of the License, or 15 (at your option) any later version. 16 17 This program is distributed in the hope that it will be useful, 18 but WITHOUT ANY WARRANTY; without even the implied warranty of 19 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 20 GNU General Public License for more details. 21 22 You should have received a copy of the GNU General Public License 23 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 24 25 /* Parse an expression from text in a string, 26 and return the result as a struct expression pointer. 27 That structure contains arithmetic operations in reverse polish, 28 with constants represented by operations that are followed by special data. 29 See expression.h for the details of the format. 30 What is important here is that it can be built up sequentially 31 during the process of parsing; the lower levels of the tree always 32 come first in the result. */ 33 34 #include <ctype.h> 35 36 #include "defs.h" 37 #include "arch-utils.h" 38 #include "gdb_string.h" 39 #include "symtab.h" 40 #include "gdbtypes.h" 41 #include "frame.h" 42 #include "expression.h" 43 #include "value.h" 44 #include "command.h" 45 #include "language.h" 46 #include "f-lang.h" 47 #include "parser-defs.h" 48 #include "gdbcmd.h" 49 #include "symfile.h" /* for overlay functions */ 50 #include "inferior.h" 51 #include "doublest.h" 52 #include "gdb_assert.h" 53 #include "block.h" 54 #include "source.h" 55 #include "objfiles.h" 56 #include "exceptions.h" 57 #include "user-regs.h" 58 59 /* Standard set of definitions for printing, dumping, prefixifying, 60 * and evaluating expressions. */ 61 62 const struct exp_descriptor exp_descriptor_standard = 63 { 64 print_subexp_standard, 65 operator_length_standard, 66 op_name_standard, 67 dump_subexp_body_standard, 68 evaluate_subexp_standard 69 }; 70 71 /* Global variables declared in parser-defs.h (and commented there). */ 72 struct expression *expout; 73 int expout_size; 74 int expout_ptr; 75 struct block *expression_context_block; 76 CORE_ADDR expression_context_pc; 77 struct block *innermost_block; 78 int arglist_len; 79 union type_stack_elt *type_stack; 80 int type_stack_depth, type_stack_size; 81 char *lexptr; 82 char *prev_lexptr; 83 int paren_depth; 84 int comma_terminates; 85 86 /* True if parsing an expression to find a field reference. This is 87 only used by completion. */ 88 int in_parse_field; 89 90 /* The index of the last struct expression directly before a '.' or 91 '->'. This is set when parsing and is only used when completing a 92 field name. It is -1 if no dereference operation was found. */ 93 static int expout_last_struct = -1; 94 95 /* A temporary buffer for identifiers, so we can null-terminate them. 96 97 We allocate this with xrealloc. parse_exp_1 used to allocate with 98 alloca, using the size of the whole expression as a conservative 99 estimate of the space needed. However, macro expansion can 100 introduce names longer than the original expression; there's no 101 practical way to know beforehand how large that might be. */ 102 char *namecopy; 103 size_t namecopy_size; 104 105 static int expressiondebug = 0; 106 static void 107 show_expressiondebug (struct ui_file *file, int from_tty, 108 struct cmd_list_element *c, const char *value) 109 { 110 fprintf_filtered (file, _("Expression debugging is %s.\n"), value); 111 } 112 113 static void free_funcalls (void *ignore); 114 115 static int prefixify_expression (struct expression *); 116 117 static int prefixify_subexp (struct expression *, struct expression *, int, 118 int); 119 120 static struct expression *parse_exp_in_context (char **, struct block *, int, 121 int, int *); 122 123 void _initialize_parse (void); 124 125 /* Data structure for saving values of arglist_len for function calls whose 126 arguments contain other function calls. */ 127 128 struct funcall 129 { 130 struct funcall *next; 131 int arglist_len; 132 }; 133 134 static struct funcall *funcall_chain; 135 136 /* Begin counting arguments for a function call, 137 saving the data about any containing call. */ 138 139 void 140 start_arglist (void) 141 { 142 struct funcall *new; 143 144 new = (struct funcall *) xmalloc (sizeof (struct funcall)); 145 new->next = funcall_chain; 146 new->arglist_len = arglist_len; 147 arglist_len = 0; 148 funcall_chain = new; 149 } 150 151 /* Return the number of arguments in a function call just terminated, 152 and restore the data for the containing function call. */ 153 154 int 155 end_arglist (void) 156 { 157 int val = arglist_len; 158 struct funcall *call = funcall_chain; 159 funcall_chain = call->next; 160 arglist_len = call->arglist_len; 161 xfree (call); 162 return val; 163 } 164 165 /* Free everything in the funcall chain. 166 Used when there is an error inside parsing. */ 167 168 static void 169 free_funcalls (void *ignore) 170 { 171 struct funcall *call, *next; 172 173 for (call = funcall_chain; call; call = next) 174 { 175 next = call->next; 176 xfree (call); 177 } 178 } 179 180 /* This page contains the functions for adding data to the struct expression 181 being constructed. */ 182 183 /* Add one element to the end of the expression. */ 184 185 /* To avoid a bug in the Sun 4 compiler, we pass things that can fit into 186 a register through here */ 187 188 void 189 write_exp_elt (union exp_element expelt) 190 { 191 if (expout_ptr >= expout_size) 192 { 193 expout_size *= 2; 194 expout = (struct expression *) 195 xrealloc ((char *) expout, sizeof (struct expression) 196 + EXP_ELEM_TO_BYTES (expout_size)); 197 } 198 expout->elts[expout_ptr++] = expelt; 199 } 200 201 void 202 write_exp_elt_opcode (enum exp_opcode expelt) 203 { 204 union exp_element tmp; 205 memset (&tmp, 0, sizeof (union exp_element)); 206 207 tmp.opcode = expelt; 208 209 write_exp_elt (tmp); 210 } 211 212 void 213 write_exp_elt_sym (struct symbol *expelt) 214 { 215 union exp_element tmp; 216 memset (&tmp, 0, sizeof (union exp_element)); 217 218 tmp.symbol = expelt; 219 220 write_exp_elt (tmp); 221 } 222 223 void 224 write_exp_elt_block (struct block *b) 225 { 226 union exp_element tmp; 227 memset (&tmp, 0, sizeof (union exp_element)); 228 tmp.block = b; 229 write_exp_elt (tmp); 230 } 231 232 void 233 write_exp_elt_objfile (struct objfile *objfile) 234 { 235 union exp_element tmp; 236 memset (&tmp, 0, sizeof (union exp_element)); 237 tmp.objfile = objfile; 238 write_exp_elt (tmp); 239 } 240 241 void 242 write_exp_elt_longcst (LONGEST expelt) 243 { 244 union exp_element tmp; 245 memset (&tmp, 0, sizeof (union exp_element)); 246 247 tmp.longconst = expelt; 248 249 write_exp_elt (tmp); 250 } 251 252 void 253 write_exp_elt_dblcst (DOUBLEST expelt) 254 { 255 union exp_element tmp; 256 memset (&tmp, 0, sizeof (union exp_element)); 257 258 tmp.doubleconst = expelt; 259 260 write_exp_elt (tmp); 261 } 262 263 void 264 write_exp_elt_decfloatcst (gdb_byte expelt[16]) 265 { 266 union exp_element tmp; 267 int index; 268 269 for (index = 0; index < 16; index++) 270 tmp.decfloatconst[index] = expelt[index]; 271 272 write_exp_elt (tmp); 273 } 274 275 void 276 write_exp_elt_type (struct type *expelt) 277 { 278 union exp_element tmp; 279 memset (&tmp, 0, sizeof (union exp_element)); 280 281 tmp.type = expelt; 282 283 write_exp_elt (tmp); 284 } 285 286 void 287 write_exp_elt_intern (struct internalvar *expelt) 288 { 289 union exp_element tmp; 290 memset (&tmp, 0, sizeof (union exp_element)); 291 292 tmp.internalvar = expelt; 293 294 write_exp_elt (tmp); 295 } 296 297 /* Add a string constant to the end of the expression. 298 299 String constants are stored by first writing an expression element 300 that contains the length of the string, then stuffing the string 301 constant itself into however many expression elements are needed 302 to hold it, and then writing another expression element that contains 303 the length of the string. I.E. an expression element at each end of 304 the string records the string length, so you can skip over the 305 expression elements containing the actual string bytes from either 306 end of the string. Note that this also allows gdb to handle 307 strings with embedded null bytes, as is required for some languages. 308 309 Don't be fooled by the fact that the string is null byte terminated, 310 this is strictly for the convenience of debugging gdb itself. 311 Gdb does not depend up the string being null terminated, since the 312 actual length is recorded in expression elements at each end of the 313 string. The null byte is taken into consideration when computing how 314 many expression elements are required to hold the string constant, of 315 course. */ 316 317 318 void 319 write_exp_string (struct stoken str) 320 { 321 int len = str.length; 322 int lenelt; 323 char *strdata; 324 325 /* Compute the number of expression elements required to hold the string 326 (including a null byte terminator), along with one expression element 327 at each end to record the actual string length (not including the 328 null byte terminator). */ 329 330 lenelt = 2 + BYTES_TO_EXP_ELEM (len + 1); 331 332 /* Ensure that we have enough available expression elements to store 333 everything. */ 334 335 if ((expout_ptr + lenelt) >= expout_size) 336 { 337 expout_size = max (expout_size * 2, expout_ptr + lenelt + 10); 338 expout = (struct expression *) 339 xrealloc ((char *) expout, (sizeof (struct expression) 340 + EXP_ELEM_TO_BYTES (expout_size))); 341 } 342 343 /* Write the leading length expression element (which advances the current 344 expression element index), then write the string constant followed by a 345 terminating null byte, and then write the trailing length expression 346 element. */ 347 348 write_exp_elt_longcst ((LONGEST) len); 349 strdata = (char *) &expout->elts[expout_ptr]; 350 memcpy (strdata, str.ptr, len); 351 *(strdata + len) = '\0'; 352 expout_ptr += lenelt - 2; 353 write_exp_elt_longcst ((LONGEST) len); 354 } 355 356 /* Add a vector of string constants to the end of the expression. 357 358 This adds an OP_STRING operation, but encodes the contents 359 differently from write_exp_string. The language is expected to 360 handle evaluation of this expression itself. 361 362 After the usual OP_STRING header, TYPE is written into the 363 expression as a long constant. The interpretation of this field is 364 up to the language evaluator. 365 366 Next, each string in VEC is written. The length is written as a 367 long constant, followed by the contents of the string. */ 368 369 void 370 write_exp_string_vector (int type, struct stoken_vector *vec) 371 { 372 int i, n_slots, len; 373 374 /* Compute the size. We compute the size in number of slots to 375 avoid issues with string padding. */ 376 n_slots = 0; 377 for (i = 0; i < vec->len; ++i) 378 { 379 /* One slot for the length of this element, plus the number of 380 slots needed for this string. */ 381 n_slots += 1 + BYTES_TO_EXP_ELEM (vec->tokens[i].length); 382 } 383 384 /* One more slot for the type of the string. */ 385 ++n_slots; 386 387 /* Now compute a phony string length. */ 388 len = EXP_ELEM_TO_BYTES (n_slots) - 1; 389 390 n_slots += 4; 391 if ((expout_ptr + n_slots) >= expout_size) 392 { 393 expout_size = max (expout_size * 2, expout_ptr + n_slots + 10); 394 expout = (struct expression *) 395 xrealloc ((char *) expout, (sizeof (struct expression) 396 + EXP_ELEM_TO_BYTES (expout_size))); 397 } 398 399 write_exp_elt_opcode (OP_STRING); 400 write_exp_elt_longcst (len); 401 write_exp_elt_longcst (type); 402 403 for (i = 0; i < vec->len; ++i) 404 { 405 write_exp_elt_longcst (vec->tokens[i].length); 406 memcpy (&expout->elts[expout_ptr], vec->tokens[i].ptr, 407 vec->tokens[i].length); 408 expout_ptr += BYTES_TO_EXP_ELEM (vec->tokens[i].length); 409 } 410 411 write_exp_elt_longcst (len); 412 write_exp_elt_opcode (OP_STRING); 413 } 414 415 /* Add a bitstring constant to the end of the expression. 416 417 Bitstring constants are stored by first writing an expression element 418 that contains the length of the bitstring (in bits), then stuffing the 419 bitstring constant itself into however many expression elements are 420 needed to hold it, and then writing another expression element that 421 contains the length of the bitstring. I.E. an expression element at 422 each end of the bitstring records the bitstring length, so you can skip 423 over the expression elements containing the actual bitstring bytes from 424 either end of the bitstring. */ 425 426 void 427 write_exp_bitstring (struct stoken str) 428 { 429 int bits = str.length; /* length in bits */ 430 int len = (bits + HOST_CHAR_BIT - 1) / HOST_CHAR_BIT; 431 int lenelt; 432 char *strdata; 433 434 /* Compute the number of expression elements required to hold the bitstring, 435 along with one expression element at each end to record the actual 436 bitstring length in bits. */ 437 438 lenelt = 2 + BYTES_TO_EXP_ELEM (len); 439 440 /* Ensure that we have enough available expression elements to store 441 everything. */ 442 443 if ((expout_ptr + lenelt) >= expout_size) 444 { 445 expout_size = max (expout_size * 2, expout_ptr + lenelt + 10); 446 expout = (struct expression *) 447 xrealloc ((char *) expout, (sizeof (struct expression) 448 + EXP_ELEM_TO_BYTES (expout_size))); 449 } 450 451 /* Write the leading length expression element (which advances the current 452 expression element index), then write the bitstring constant, and then 453 write the trailing length expression element. */ 454 455 write_exp_elt_longcst ((LONGEST) bits); 456 strdata = (char *) &expout->elts[expout_ptr]; 457 memcpy (strdata, str.ptr, len); 458 expout_ptr += lenelt - 2; 459 write_exp_elt_longcst ((LONGEST) bits); 460 } 461 462 /* Add the appropriate elements for a minimal symbol to the end of 463 the expression. */ 464 465 void 466 write_exp_msymbol (struct minimal_symbol *msymbol) 467 { 468 struct objfile *objfile = msymbol_objfile (msymbol); 469 struct gdbarch *gdbarch = get_objfile_arch (objfile); 470 471 CORE_ADDR addr = SYMBOL_VALUE_ADDRESS (msymbol); 472 struct obj_section *section = SYMBOL_OBJ_SECTION (msymbol); 473 enum minimal_symbol_type type = MSYMBOL_TYPE (msymbol); 474 CORE_ADDR pc; 475 476 /* The minimal symbol might point to a function descriptor; 477 resolve it to the actual code address instead. */ 478 pc = gdbarch_convert_from_func_ptr_addr (gdbarch, addr, ¤t_target); 479 if (pc != addr) 480 { 481 /* In this case, assume we have a code symbol instead of 482 a data symbol. */ 483 type = mst_text; 484 section = NULL; 485 addr = pc; 486 } 487 488 if (overlay_debugging) 489 addr = symbol_overlayed_address (addr, section); 490 491 write_exp_elt_opcode (OP_LONG); 492 /* Let's make the type big enough to hold a 64-bit address. */ 493 write_exp_elt_type (objfile_type (objfile)->builtin_core_addr); 494 write_exp_elt_longcst ((LONGEST) addr); 495 write_exp_elt_opcode (OP_LONG); 496 497 if (section && section->the_bfd_section->flags & SEC_THREAD_LOCAL) 498 { 499 write_exp_elt_opcode (UNOP_MEMVAL_TLS); 500 write_exp_elt_objfile (objfile); 501 write_exp_elt_type (objfile_type (objfile)->nodebug_tls_symbol); 502 write_exp_elt_opcode (UNOP_MEMVAL_TLS); 503 return; 504 } 505 506 write_exp_elt_opcode (UNOP_MEMVAL); 507 switch (type) 508 { 509 case mst_text: 510 case mst_file_text: 511 case mst_solib_trampoline: 512 write_exp_elt_type (objfile_type (objfile)->nodebug_text_symbol); 513 break; 514 515 case mst_data: 516 case mst_file_data: 517 case mst_bss: 518 case mst_file_bss: 519 write_exp_elt_type (objfile_type (objfile)->nodebug_data_symbol); 520 break; 521 522 default: 523 write_exp_elt_type (objfile_type (objfile)->nodebug_unknown_symbol); 524 break; 525 } 526 write_exp_elt_opcode (UNOP_MEMVAL); 527 } 528 529 /* Mark the current index as the starting location of a structure 530 expression. This is used when completing on field names. */ 531 532 void 533 mark_struct_expression (void) 534 { 535 expout_last_struct = expout_ptr; 536 } 537 538 539 /* Recognize tokens that start with '$'. These include: 540 541 $regname A native register name or a "standard 542 register name". 543 544 $variable A convenience variable with a name chosen 545 by the user. 546 547 $digits Value history with index <digits>, starting 548 from the first value which has index 1. 549 550 $$digits Value history with index <digits> relative 551 to the last value. I.E. $$0 is the last 552 value, $$1 is the one previous to that, $$2 553 is the one previous to $$1, etc. 554 555 $ | $0 | $$0 The last value in the value history. 556 557 $$ An abbreviation for the second to the last 558 value in the value history, I.E. $$1 559 560 */ 561 562 void 563 write_dollar_variable (struct stoken str) 564 { 565 struct symbol *sym = NULL; 566 struct minimal_symbol *msym = NULL; 567 struct internalvar *isym = NULL; 568 569 /* Handle the tokens $digits; also $ (short for $0) and $$ (short for $$1) 570 and $$digits (equivalent to $<-digits> if you could type that). */ 571 572 int negate = 0; 573 int i = 1; 574 /* Double dollar means negate the number and add -1 as well. 575 Thus $$ alone means -1. */ 576 if (str.length >= 2 && str.ptr[1] == '$') 577 { 578 negate = 1; 579 i = 2; 580 } 581 if (i == str.length) 582 { 583 /* Just dollars (one or two) */ 584 i = -negate; 585 goto handle_last; 586 } 587 /* Is the rest of the token digits? */ 588 for (; i < str.length; i++) 589 if (!(str.ptr[i] >= '0' && str.ptr[i] <= '9')) 590 break; 591 if (i == str.length) 592 { 593 i = atoi (str.ptr + 1 + negate); 594 if (negate) 595 i = -i; 596 goto handle_last; 597 } 598 599 /* Handle tokens that refer to machine registers: 600 $ followed by a register name. */ 601 i = user_reg_map_name_to_regnum (parse_gdbarch, 602 str.ptr + 1, str.length - 1); 603 if (i >= 0) 604 goto handle_register; 605 606 /* Any names starting with $ are probably debugger internal variables. */ 607 608 isym = lookup_only_internalvar (copy_name (str) + 1); 609 if (isym) 610 { 611 write_exp_elt_opcode (OP_INTERNALVAR); 612 write_exp_elt_intern (isym); 613 write_exp_elt_opcode (OP_INTERNALVAR); 614 return; 615 } 616 617 /* On some systems, such as HP-UX and hppa-linux, certain system routines 618 have names beginning with $ or $$. Check for those, first. */ 619 620 sym = lookup_symbol (copy_name (str), (struct block *) NULL, 621 VAR_DOMAIN, (int *) NULL); 622 if (sym) 623 { 624 write_exp_elt_opcode (OP_VAR_VALUE); 625 write_exp_elt_block (block_found); /* set by lookup_symbol */ 626 write_exp_elt_sym (sym); 627 write_exp_elt_opcode (OP_VAR_VALUE); 628 return; 629 } 630 msym = lookup_minimal_symbol (copy_name (str), NULL, NULL); 631 if (msym) 632 { 633 write_exp_msymbol (msym); 634 return; 635 } 636 637 /* Any other names are assumed to be debugger internal variables. */ 638 639 write_exp_elt_opcode (OP_INTERNALVAR); 640 write_exp_elt_intern (create_internalvar (copy_name (str) + 1)); 641 write_exp_elt_opcode (OP_INTERNALVAR); 642 return; 643 handle_last: 644 write_exp_elt_opcode (OP_LAST); 645 write_exp_elt_longcst ((LONGEST) i); 646 write_exp_elt_opcode (OP_LAST); 647 return; 648 handle_register: 649 write_exp_elt_opcode (OP_REGISTER); 650 str.length--; 651 str.ptr++; 652 write_exp_string (str); 653 write_exp_elt_opcode (OP_REGISTER); 654 return; 655 } 656 657 658 char * 659 find_template_name_end (char *p) 660 { 661 int depth = 1; 662 int just_seen_right = 0; 663 int just_seen_colon = 0; 664 int just_seen_space = 0; 665 666 if (!p || (*p != '<')) 667 return 0; 668 669 while (*++p) 670 { 671 switch (*p) 672 { 673 case '\'': 674 case '\"': 675 case '{': 676 case '}': 677 /* In future, may want to allow these?? */ 678 return 0; 679 case '<': 680 depth++; /* start nested template */ 681 if (just_seen_colon || just_seen_right || just_seen_space) 682 return 0; /* but not after : or :: or > or space */ 683 break; 684 case '>': 685 if (just_seen_colon || just_seen_right) 686 return 0; /* end a (nested?) template */ 687 just_seen_right = 1; /* but not after : or :: */ 688 if (--depth == 0) /* also disallow >>, insist on > > */ 689 return ++p; /* if outermost ended, return */ 690 break; 691 case ':': 692 if (just_seen_space || (just_seen_colon > 1)) 693 return 0; /* nested class spec coming up */ 694 just_seen_colon++; /* we allow :: but not :::: */ 695 break; 696 case ' ': 697 break; 698 default: 699 if (!((*p >= 'a' && *p <= 'z') || /* allow token chars */ 700 (*p >= 'A' && *p <= 'Z') || 701 (*p >= '0' && *p <= '9') || 702 (*p == '_') || (*p == ',') || /* commas for template args */ 703 (*p == '&') || (*p == '*') || /* pointer and ref types */ 704 (*p == '(') || (*p == ')') || /* function types */ 705 (*p == '[') || (*p == ']'))) /* array types */ 706 return 0; 707 } 708 if (*p != ' ') 709 just_seen_space = 0; 710 if (*p != ':') 711 just_seen_colon = 0; 712 if (*p != '>') 713 just_seen_right = 0; 714 } 715 return 0; 716 } 717 718 719 720 /* Return a null-terminated temporary copy of the name 721 of a string token. */ 722 723 char * 724 copy_name (struct stoken token) 725 { 726 /* Make sure there's enough space for the token. */ 727 if (namecopy_size < token.length + 1) 728 { 729 namecopy_size = token.length + 1; 730 namecopy = xrealloc (namecopy, token.length + 1); 731 } 732 733 memcpy (namecopy, token.ptr, token.length); 734 namecopy[token.length] = 0; 735 736 return namecopy; 737 } 738 739 /* Reverse an expression from suffix form (in which it is constructed) 740 to prefix form (in which we can conveniently print or execute it). 741 Ordinarily this always returns -1. However, if EXPOUT_LAST_STRUCT 742 is not -1 (i.e., we are trying to complete a field name), it will 743 return the index of the subexpression which is the left-hand-side 744 of the struct operation at EXPOUT_LAST_STRUCT. */ 745 746 static int 747 prefixify_expression (struct expression *expr) 748 { 749 int len = sizeof (struct expression) + EXP_ELEM_TO_BYTES (expr->nelts); 750 struct expression *temp; 751 int inpos = expr->nelts, outpos = 0; 752 753 temp = (struct expression *) alloca (len); 754 755 /* Copy the original expression into temp. */ 756 memcpy (temp, expr, len); 757 758 return prefixify_subexp (temp, expr, inpos, outpos); 759 } 760 761 /* Return the number of exp_elements in the postfix subexpression 762 of EXPR whose operator is at index ENDPOS - 1 in EXPR. */ 763 764 int 765 length_of_subexp (struct expression *expr, int endpos) 766 { 767 int oplen, args, i; 768 769 operator_length (expr, endpos, &oplen, &args); 770 771 while (args > 0) 772 { 773 oplen += length_of_subexp (expr, endpos - oplen); 774 args--; 775 } 776 777 return oplen; 778 } 779 780 /* Sets *OPLENP to the length of the operator whose (last) index is 781 ENDPOS - 1 in EXPR, and sets *ARGSP to the number of arguments that 782 operator takes. */ 783 784 void 785 operator_length (struct expression *expr, int endpos, int *oplenp, int *argsp) 786 { 787 expr->language_defn->la_exp_desc->operator_length (expr, endpos, 788 oplenp, argsp); 789 } 790 791 /* Default value for operator_length in exp_descriptor vectors. */ 792 793 void 794 operator_length_standard (struct expression *expr, int endpos, 795 int *oplenp, int *argsp) 796 { 797 int oplen = 1; 798 int args = 0; 799 enum f90_range_type range_type; 800 int i; 801 802 if (endpos < 1) 803 error (_("?error in operator_length_standard")); 804 805 i = (int) expr->elts[endpos - 1].opcode; 806 807 switch (i) 808 { 809 /* C++ */ 810 case OP_SCOPE: 811 oplen = longest_to_int (expr->elts[endpos - 2].longconst); 812 oplen = 5 + BYTES_TO_EXP_ELEM (oplen + 1); 813 break; 814 815 case OP_LONG: 816 case OP_DOUBLE: 817 case OP_DECFLOAT: 818 case OP_VAR_VALUE: 819 oplen = 4; 820 break; 821 822 case OP_TYPE: 823 case OP_BOOL: 824 case OP_LAST: 825 case OP_INTERNALVAR: 826 oplen = 3; 827 break; 828 829 case OP_COMPLEX: 830 oplen = 3; 831 args = 2; 832 break; 833 834 case OP_FUNCALL: 835 case OP_F77_UNDETERMINED_ARGLIST: 836 oplen = 3; 837 args = 1 + longest_to_int (expr->elts[endpos - 2].longconst); 838 break; 839 840 case OP_OBJC_MSGCALL: /* Objective C message (method) call */ 841 oplen = 4; 842 args = 1 + longest_to_int (expr->elts[endpos - 2].longconst); 843 break; 844 845 case UNOP_MAX: 846 case UNOP_MIN: 847 oplen = 3; 848 break; 849 850 case BINOP_VAL: 851 case UNOP_CAST: 852 case UNOP_MEMVAL: 853 oplen = 3; 854 args = 1; 855 break; 856 857 case UNOP_MEMVAL_TLS: 858 oplen = 4; 859 args = 1; 860 break; 861 862 case UNOP_ABS: 863 case UNOP_CAP: 864 case UNOP_CHR: 865 case UNOP_FLOAT: 866 case UNOP_HIGH: 867 case UNOP_ODD: 868 case UNOP_ORD: 869 case UNOP_TRUNC: 870 oplen = 1; 871 args = 1; 872 break; 873 874 case OP_LABELED: 875 case STRUCTOP_STRUCT: 876 case STRUCTOP_PTR: 877 args = 1; 878 /* fall through */ 879 case OP_REGISTER: 880 case OP_M2_STRING: 881 case OP_STRING: 882 case OP_OBJC_NSSTRING: /* Objective C Foundation Class NSString constant */ 883 case OP_OBJC_SELECTOR: /* Objective C "@selector" pseudo-op */ 884 case OP_NAME: 885 oplen = longest_to_int (expr->elts[endpos - 2].longconst); 886 oplen = 4 + BYTES_TO_EXP_ELEM (oplen + 1); 887 break; 888 889 case OP_BITSTRING: 890 oplen = longest_to_int (expr->elts[endpos - 2].longconst); 891 oplen = (oplen + HOST_CHAR_BIT - 1) / HOST_CHAR_BIT; 892 oplen = 4 + BYTES_TO_EXP_ELEM (oplen); 893 break; 894 895 case OP_ARRAY: 896 oplen = 4; 897 args = longest_to_int (expr->elts[endpos - 2].longconst); 898 args -= longest_to_int (expr->elts[endpos - 3].longconst); 899 args += 1; 900 break; 901 902 case TERNOP_COND: 903 case TERNOP_SLICE: 904 case TERNOP_SLICE_COUNT: 905 args = 3; 906 break; 907 908 /* Modula-2 */ 909 case MULTI_SUBSCRIPT: 910 oplen = 3; 911 args = 1 + longest_to_int (expr->elts[endpos - 2].longconst); 912 break; 913 914 case BINOP_ASSIGN_MODIFY: 915 oplen = 3; 916 args = 2; 917 break; 918 919 /* C++ */ 920 case OP_THIS: 921 case OP_OBJC_SELF: 922 oplen = 2; 923 break; 924 925 case OP_F90_RANGE: 926 oplen = 3; 927 928 range_type = longest_to_int (expr->elts[endpos - 2].longconst); 929 switch (range_type) 930 { 931 case LOW_BOUND_DEFAULT: 932 case HIGH_BOUND_DEFAULT: 933 args = 1; 934 break; 935 case BOTH_BOUND_DEFAULT: 936 args = 0; 937 break; 938 case NONE_BOUND_DEFAULT: 939 args = 2; 940 break; 941 } 942 943 break; 944 945 default: 946 args = 1 + (i < (int) BINOP_END); 947 } 948 949 *oplenp = oplen; 950 *argsp = args; 951 } 952 953 /* Copy the subexpression ending just before index INEND in INEXPR 954 into OUTEXPR, starting at index OUTBEG. 955 In the process, convert it from suffix to prefix form. 956 If EXPOUT_LAST_STRUCT is -1, then this function always returns -1. 957 Otherwise, it returns the index of the subexpression which is the 958 left-hand-side of the expression at EXPOUT_LAST_STRUCT. */ 959 960 static int 961 prefixify_subexp (struct expression *inexpr, 962 struct expression *outexpr, int inend, int outbeg) 963 { 964 int oplen; 965 int args; 966 int i; 967 int *arglens; 968 enum exp_opcode opcode; 969 int result = -1; 970 971 operator_length (inexpr, inend, &oplen, &args); 972 973 /* Copy the final operator itself, from the end of the input 974 to the beginning of the output. */ 975 inend -= oplen; 976 memcpy (&outexpr->elts[outbeg], &inexpr->elts[inend], 977 EXP_ELEM_TO_BYTES (oplen)); 978 outbeg += oplen; 979 980 if (expout_last_struct == inend) 981 result = outbeg - oplen; 982 983 /* Find the lengths of the arg subexpressions. */ 984 arglens = (int *) alloca (args * sizeof (int)); 985 for (i = args - 1; i >= 0; i--) 986 { 987 oplen = length_of_subexp (inexpr, inend); 988 arglens[i] = oplen; 989 inend -= oplen; 990 } 991 992 /* Now copy each subexpression, preserving the order of 993 the subexpressions, but prefixifying each one. 994 In this loop, inend starts at the beginning of 995 the expression this level is working on 996 and marches forward over the arguments. 997 outbeg does similarly in the output. */ 998 for (i = 0; i < args; i++) 999 { 1000 int r; 1001 oplen = arglens[i]; 1002 inend += oplen; 1003 r = prefixify_subexp (inexpr, outexpr, inend, outbeg); 1004 if (r != -1) 1005 { 1006 /* Return immediately. We probably have only parsed a 1007 partial expression, so we don't want to try to reverse 1008 the other operands. */ 1009 return r; 1010 } 1011 outbeg += oplen; 1012 } 1013 1014 return result; 1015 } 1016 1017 /* This page contains the two entry points to this file. */ 1018 1019 /* Read an expression from the string *STRINGPTR points to, 1020 parse it, and return a pointer to a struct expression that we malloc. 1021 Use block BLOCK as the lexical context for variable names; 1022 if BLOCK is zero, use the block of the selected stack frame. 1023 Meanwhile, advance *STRINGPTR to point after the expression, 1024 at the first nonwhite character that is not part of the expression 1025 (possibly a null character). 1026 1027 If COMMA is nonzero, stop if a comma is reached. */ 1028 1029 struct expression * 1030 parse_exp_1 (char **stringptr, struct block *block, int comma) 1031 { 1032 return parse_exp_in_context (stringptr, block, comma, 0, NULL); 1033 } 1034 1035 /* As for parse_exp_1, except that if VOID_CONTEXT_P, then 1036 no value is expected from the expression. 1037 OUT_SUBEXP is set when attempting to complete a field name; in this 1038 case it is set to the index of the subexpression on the 1039 left-hand-side of the struct op. If not doing such completion, it 1040 is left untouched. */ 1041 1042 static struct expression * 1043 parse_exp_in_context (char **stringptr, struct block *block, int comma, 1044 int void_context_p, int *out_subexp) 1045 { 1046 volatile struct gdb_exception except; 1047 struct cleanup *old_chain; 1048 int subexp; 1049 1050 lexptr = *stringptr; 1051 prev_lexptr = NULL; 1052 1053 paren_depth = 0; 1054 type_stack_depth = 0; 1055 expout_last_struct = -1; 1056 1057 comma_terminates = comma; 1058 1059 if (lexptr == 0 || *lexptr == 0) 1060 error_no_arg (_("expression to compute")); 1061 1062 old_chain = make_cleanup (free_funcalls, 0 /*ignore*/); 1063 funcall_chain = 0; 1064 1065 expression_context_block = block; 1066 1067 /* If no context specified, try using the current frame, if any. */ 1068 if (!expression_context_block) 1069 expression_context_block = get_selected_block (&expression_context_pc); 1070 else 1071 expression_context_pc = BLOCK_START (expression_context_block); 1072 1073 /* Fall back to using the current source static context, if any. */ 1074 1075 if (!expression_context_block) 1076 { 1077 struct symtab_and_line cursal = get_current_source_symtab_and_line (); 1078 if (cursal.symtab) 1079 expression_context_block 1080 = BLOCKVECTOR_BLOCK (BLOCKVECTOR (cursal.symtab), STATIC_BLOCK); 1081 if (expression_context_block) 1082 expression_context_pc = BLOCK_START (expression_context_block); 1083 } 1084 1085 expout_size = 10; 1086 expout_ptr = 0; 1087 expout = (struct expression *) 1088 xmalloc (sizeof (struct expression) + EXP_ELEM_TO_BYTES (expout_size)); 1089 expout->language_defn = current_language; 1090 expout->gdbarch = get_current_arch (); 1091 1092 TRY_CATCH (except, RETURN_MASK_ALL) 1093 { 1094 if (current_language->la_parser ()) 1095 current_language->la_error (NULL); 1096 } 1097 if (except.reason < 0) 1098 { 1099 if (! in_parse_field) 1100 { 1101 xfree (expout); 1102 throw_exception (except); 1103 } 1104 } 1105 1106 discard_cleanups (old_chain); 1107 1108 /* Record the actual number of expression elements, and then 1109 reallocate the expression memory so that we free up any 1110 excess elements. */ 1111 1112 expout->nelts = expout_ptr; 1113 expout = (struct expression *) 1114 xrealloc ((char *) expout, 1115 sizeof (struct expression) + EXP_ELEM_TO_BYTES (expout_ptr));; 1116 1117 /* Convert expression from postfix form as generated by yacc 1118 parser, to a prefix form. */ 1119 1120 if (expressiondebug) 1121 dump_raw_expression (expout, gdb_stdlog, 1122 "before conversion to prefix form"); 1123 1124 subexp = prefixify_expression (expout); 1125 if (out_subexp) 1126 *out_subexp = subexp; 1127 1128 current_language->la_post_parser (&expout, void_context_p); 1129 1130 if (expressiondebug) 1131 dump_prefix_expression (expout, gdb_stdlog); 1132 1133 *stringptr = lexptr; 1134 return expout; 1135 } 1136 1137 /* Parse STRING as an expression, and complain if this fails 1138 to use up all of the contents of STRING. */ 1139 1140 struct expression * 1141 parse_expression (char *string) 1142 { 1143 struct expression *exp; 1144 exp = parse_exp_1 (&string, 0, 0); 1145 if (*string) 1146 error (_("Junk after end of expression.")); 1147 return exp; 1148 } 1149 1150 /* Parse STRING as an expression. If parsing ends in the middle of a 1151 field reference, return the type of the left-hand-side of the 1152 reference; furthermore, if the parsing ends in the field name, 1153 return the field name in *NAME. In all other cases, return NULL. 1154 Returned non-NULL *NAME must be freed by the caller. */ 1155 1156 struct type * 1157 parse_field_expression (char *string, char **name) 1158 { 1159 struct expression *exp = NULL; 1160 struct value *val; 1161 int subexp; 1162 volatile struct gdb_exception except; 1163 1164 TRY_CATCH (except, RETURN_MASK_ALL) 1165 { 1166 in_parse_field = 1; 1167 exp = parse_exp_in_context (&string, 0, 0, 0, &subexp); 1168 } 1169 in_parse_field = 0; 1170 if (except.reason < 0 || ! exp) 1171 return NULL; 1172 if (expout_last_struct == -1) 1173 { 1174 xfree (exp); 1175 return NULL; 1176 } 1177 1178 *name = extract_field_op (exp, &subexp); 1179 if (!*name) 1180 { 1181 xfree (exp); 1182 return NULL; 1183 } 1184 /* (*NAME) is a part of the EXP memory block freed below. */ 1185 *name = xstrdup (*name); 1186 1187 val = evaluate_subexpression_type (exp, subexp); 1188 xfree (exp); 1189 1190 return value_type (val); 1191 } 1192 1193 /* A post-parser that does nothing */ 1194 1195 void 1196 null_post_parser (struct expression **exp, int void_context_p) 1197 { 1198 } 1199 1200 /* Stuff for maintaining a stack of types. Currently just used by C, but 1201 probably useful for any language which declares its types "backwards". */ 1202 1203 static void 1204 check_type_stack_depth (void) 1205 { 1206 if (type_stack_depth == type_stack_size) 1207 { 1208 type_stack_size *= 2; 1209 type_stack = (union type_stack_elt *) 1210 xrealloc ((char *) type_stack, type_stack_size * sizeof (*type_stack)); 1211 } 1212 } 1213 1214 void 1215 push_type (enum type_pieces tp) 1216 { 1217 check_type_stack_depth (); 1218 type_stack[type_stack_depth++].piece = tp; 1219 } 1220 1221 void 1222 push_type_int (int n) 1223 { 1224 check_type_stack_depth (); 1225 type_stack[type_stack_depth++].int_val = n; 1226 } 1227 1228 void 1229 push_type_address_space (char *string) 1230 { 1231 push_type_int (address_space_name_to_int (parse_gdbarch, string)); 1232 } 1233 1234 enum type_pieces 1235 pop_type (void) 1236 { 1237 if (type_stack_depth) 1238 return type_stack[--type_stack_depth].piece; 1239 return tp_end; 1240 } 1241 1242 int 1243 pop_type_int (void) 1244 { 1245 if (type_stack_depth) 1246 return type_stack[--type_stack_depth].int_val; 1247 /* "Can't happen". */ 1248 return 0; 1249 } 1250 1251 /* Pop the type stack and return the type which corresponds to FOLLOW_TYPE 1252 as modified by all the stuff on the stack. */ 1253 struct type * 1254 follow_types (struct type *follow_type) 1255 { 1256 int done = 0; 1257 int make_const = 0; 1258 int make_volatile = 0; 1259 int make_addr_space = 0; 1260 int array_size; 1261 1262 while (!done) 1263 switch (pop_type ()) 1264 { 1265 case tp_end: 1266 done = 1; 1267 if (make_const) 1268 follow_type = make_cv_type (make_const, 1269 TYPE_VOLATILE (follow_type), 1270 follow_type, 0); 1271 if (make_volatile) 1272 follow_type = make_cv_type (TYPE_CONST (follow_type), 1273 make_volatile, 1274 follow_type, 0); 1275 if (make_addr_space) 1276 follow_type = make_type_with_address_space (follow_type, 1277 make_addr_space); 1278 make_const = make_volatile = 0; 1279 make_addr_space = 0; 1280 break; 1281 case tp_const: 1282 make_const = 1; 1283 break; 1284 case tp_volatile: 1285 make_volatile = 1; 1286 break; 1287 case tp_space_identifier: 1288 make_addr_space = pop_type_int (); 1289 break; 1290 case tp_pointer: 1291 follow_type = lookup_pointer_type (follow_type); 1292 if (make_const) 1293 follow_type = make_cv_type (make_const, 1294 TYPE_VOLATILE (follow_type), 1295 follow_type, 0); 1296 if (make_volatile) 1297 follow_type = make_cv_type (TYPE_CONST (follow_type), 1298 make_volatile, 1299 follow_type, 0); 1300 if (make_addr_space) 1301 follow_type = make_type_with_address_space (follow_type, 1302 make_addr_space); 1303 make_const = make_volatile = 0; 1304 make_addr_space = 0; 1305 break; 1306 case tp_reference: 1307 follow_type = lookup_reference_type (follow_type); 1308 if (make_const) 1309 follow_type = make_cv_type (make_const, 1310 TYPE_VOLATILE (follow_type), 1311 follow_type, 0); 1312 if (make_volatile) 1313 follow_type = make_cv_type (TYPE_CONST (follow_type), 1314 make_volatile, 1315 follow_type, 0); 1316 if (make_addr_space) 1317 follow_type = make_type_with_address_space (follow_type, 1318 make_addr_space); 1319 make_const = make_volatile = 0; 1320 make_addr_space = 0; 1321 break; 1322 case tp_array: 1323 array_size = pop_type_int (); 1324 /* FIXME-type-allocation: need a way to free this type when we are 1325 done with it. */ 1326 follow_type = 1327 lookup_array_range_type (follow_type, 1328 0, array_size >= 0 ? array_size - 1 : 0); 1329 if (array_size < 0) 1330 TYPE_ARRAY_UPPER_BOUND_IS_UNDEFINED (follow_type) = 1; 1331 break; 1332 case tp_function: 1333 /* FIXME-type-allocation: need a way to free this type when we are 1334 done with it. */ 1335 follow_type = lookup_function_type (follow_type); 1336 break; 1337 } 1338 return follow_type; 1339 } 1340 1341 /* This function avoids direct calls to fprintf 1342 in the parser generated debug code. */ 1343 void 1344 parser_fprintf (FILE *x, const char *y, ...) 1345 { 1346 va_list args; 1347 va_start (args, y); 1348 if (x == stderr) 1349 vfprintf_unfiltered (gdb_stderr, y, args); 1350 else 1351 { 1352 fprintf_unfiltered (gdb_stderr, " Unknown FILE used.\n"); 1353 vfprintf_unfiltered (gdb_stderr, y, args); 1354 } 1355 va_end (args); 1356 } 1357 1358 void 1359 _initialize_parse (void) 1360 { 1361 type_stack_size = 80; 1362 type_stack_depth = 0; 1363 type_stack = (union type_stack_elt *) 1364 xmalloc (type_stack_size * sizeof (*type_stack)); 1365 1366 add_setshow_zinteger_cmd ("expression", class_maintenance, 1367 &expressiondebug, _("\ 1368 Set expression debugging."), _("\ 1369 Show expression debugging."), _("\ 1370 When non-zero, the internal representation of expressions will be printed."), 1371 NULL, 1372 show_expressiondebug, 1373 &setdebuglist, &showdebuglist); 1374 } 1375