1 /* Alias analysis for trees. 2 Copyright (C) 2004-2017 Free Software Foundation, Inc. 3 Contributed by Diego Novillo <dnovillo@redhat.com> 4 5 This file is part of GCC. 6 7 GCC is free software; you can redistribute it and/or modify 8 it under the terms of the GNU General Public License as published by 9 the Free Software Foundation; either version 3, or (at your option) 10 any later version. 11 12 GCC is distributed in the hope that it will be useful, 13 but WITHOUT ANY WARRANTY; without even the implied warranty of 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 GNU General Public License for more details. 16 17 You should have received a copy of the GNU General Public License 18 along with GCC; see the file COPYING3. If not see 19 <http://www.gnu.org/licenses/>. */ 20 21 #include "config.h" 22 #include "system.h" 23 #include "coretypes.h" 24 #include "backend.h" 25 #include "target.h" 26 #include "rtl.h" 27 #include "tree.h" 28 #include "gimple.h" 29 #include "timevar.h" /* for TV_ALIAS_STMT_WALK */ 30 #include "ssa.h" 31 #include "cgraph.h" 32 #include "tree-pretty-print.h" 33 #include "alias.h" 34 #include "fold-const.h" 35 #include "langhooks.h" 36 #include "dumpfile.h" 37 #include "tree-eh.h" 38 #include "tree-dfa.h" 39 #include "ipa-reference.h" 40 #include "varasm.h" 41 42 /* Broad overview of how alias analysis on gimple works: 43 44 Statements clobbering or using memory are linked through the 45 virtual operand factored use-def chain. The virtual operand 46 is unique per function, its symbol is accessible via gimple_vop (cfun). 47 Virtual operands are used for efficiently walking memory statements 48 in the gimple IL and are useful for things like value-numbering as 49 a generation count for memory references. 50 51 SSA_NAME pointers may have associated points-to information 52 accessible via the SSA_NAME_PTR_INFO macro. Flow-insensitive 53 points-to information is (re-)computed by the TODO_rebuild_alias 54 pass manager todo. Points-to information is also used for more 55 precise tracking of call-clobbered and call-used variables and 56 related disambiguations. 57 58 This file contains functions for disambiguating memory references, 59 the so called alias-oracle and tools for walking of the gimple IL. 60 61 The main alias-oracle entry-points are 62 63 bool stmt_may_clobber_ref_p (gimple *, tree) 64 65 This function queries if a statement may invalidate (parts of) 66 the memory designated by the reference tree argument. 67 68 bool ref_maybe_used_by_stmt_p (gimple *, tree) 69 70 This function queries if a statement may need (parts of) the 71 memory designated by the reference tree argument. 72 73 There are variants of these functions that only handle the call 74 part of a statement, call_may_clobber_ref_p and ref_maybe_used_by_call_p. 75 Note that these do not disambiguate against a possible call lhs. 76 77 bool refs_may_alias_p (tree, tree) 78 79 This function tries to disambiguate two reference trees. 80 81 bool ptr_deref_may_alias_global_p (tree) 82 83 This function queries if dereferencing a pointer variable may 84 alias global memory. 85 86 More low-level disambiguators are available and documented in 87 this file. Low-level disambiguators dealing with points-to 88 information are in tree-ssa-structalias.c. */ 89 90 91 /* Query statistics for the different low-level disambiguators. 92 A high-level query may trigger multiple of them. */ 93 94 static struct { 95 unsigned HOST_WIDE_INT refs_may_alias_p_may_alias; 96 unsigned HOST_WIDE_INT refs_may_alias_p_no_alias; 97 unsigned HOST_WIDE_INT ref_maybe_used_by_call_p_may_alias; 98 unsigned HOST_WIDE_INT ref_maybe_used_by_call_p_no_alias; 99 unsigned HOST_WIDE_INT call_may_clobber_ref_p_may_alias; 100 unsigned HOST_WIDE_INT call_may_clobber_ref_p_no_alias; 101 } alias_stats; 102 103 void 104 dump_alias_stats (FILE *s) 105 { 106 fprintf (s, "\nAlias oracle query stats:\n"); 107 fprintf (s, " refs_may_alias_p: " 108 HOST_WIDE_INT_PRINT_DEC" disambiguations, " 109 HOST_WIDE_INT_PRINT_DEC" queries\n", 110 alias_stats.refs_may_alias_p_no_alias, 111 alias_stats.refs_may_alias_p_no_alias 112 + alias_stats.refs_may_alias_p_may_alias); 113 fprintf (s, " ref_maybe_used_by_call_p: " 114 HOST_WIDE_INT_PRINT_DEC" disambiguations, " 115 HOST_WIDE_INT_PRINT_DEC" queries\n", 116 alias_stats.ref_maybe_used_by_call_p_no_alias, 117 alias_stats.refs_may_alias_p_no_alias 118 + alias_stats.ref_maybe_used_by_call_p_may_alias); 119 fprintf (s, " call_may_clobber_ref_p: " 120 HOST_WIDE_INT_PRINT_DEC" disambiguations, " 121 HOST_WIDE_INT_PRINT_DEC" queries\n", 122 alias_stats.call_may_clobber_ref_p_no_alias, 123 alias_stats.call_may_clobber_ref_p_no_alias 124 + alias_stats.call_may_clobber_ref_p_may_alias); 125 dump_alias_stats_in_alias_c (s); 126 } 127 128 129 /* Return true, if dereferencing PTR may alias with a global variable. */ 130 131 bool 132 ptr_deref_may_alias_global_p (tree ptr) 133 { 134 struct ptr_info_def *pi; 135 136 /* If we end up with a pointer constant here that may point 137 to global memory. */ 138 if (TREE_CODE (ptr) != SSA_NAME) 139 return true; 140 141 pi = SSA_NAME_PTR_INFO (ptr); 142 143 /* If we do not have points-to information for this variable, 144 we have to punt. */ 145 if (!pi) 146 return true; 147 148 /* ??? This does not use TBAA to prune globals ptr may not access. */ 149 return pt_solution_includes_global (&pi->pt); 150 } 151 152 /* Return true if dereferencing PTR may alias DECL. 153 The caller is responsible for applying TBAA to see if PTR 154 may access DECL at all. */ 155 156 static bool 157 ptr_deref_may_alias_decl_p (tree ptr, tree decl) 158 { 159 struct ptr_info_def *pi; 160 161 /* Conversions are irrelevant for points-to information and 162 data-dependence analysis can feed us those. */ 163 STRIP_NOPS (ptr); 164 165 /* Anything we do not explicilty handle aliases. */ 166 if ((TREE_CODE (ptr) != SSA_NAME 167 && TREE_CODE (ptr) != ADDR_EXPR 168 && TREE_CODE (ptr) != POINTER_PLUS_EXPR) 169 || !POINTER_TYPE_P (TREE_TYPE (ptr)) 170 || (!VAR_P (decl) 171 && TREE_CODE (decl) != PARM_DECL 172 && TREE_CODE (decl) != RESULT_DECL)) 173 return true; 174 175 /* Disregard pointer offsetting. */ 176 if (TREE_CODE (ptr) == POINTER_PLUS_EXPR) 177 { 178 do 179 { 180 ptr = TREE_OPERAND (ptr, 0); 181 } 182 while (TREE_CODE (ptr) == POINTER_PLUS_EXPR); 183 return ptr_deref_may_alias_decl_p (ptr, decl); 184 } 185 186 /* ADDR_EXPR pointers either just offset another pointer or directly 187 specify the pointed-to set. */ 188 if (TREE_CODE (ptr) == ADDR_EXPR) 189 { 190 tree base = get_base_address (TREE_OPERAND (ptr, 0)); 191 if (base 192 && (TREE_CODE (base) == MEM_REF 193 || TREE_CODE (base) == TARGET_MEM_REF)) 194 ptr = TREE_OPERAND (base, 0); 195 else if (base 196 && DECL_P (base)) 197 return compare_base_decls (base, decl) != 0; 198 else if (base 199 && CONSTANT_CLASS_P (base)) 200 return false; 201 else 202 return true; 203 } 204 205 /* Non-aliased variables can not be pointed to. */ 206 if (!may_be_aliased (decl)) 207 return false; 208 209 /* If we do not have useful points-to information for this pointer 210 we cannot disambiguate anything else. */ 211 pi = SSA_NAME_PTR_INFO (ptr); 212 if (!pi) 213 return true; 214 215 return pt_solution_includes (&pi->pt, decl); 216 } 217 218 /* Return true if dereferenced PTR1 and PTR2 may alias. 219 The caller is responsible for applying TBAA to see if accesses 220 through PTR1 and PTR2 may conflict at all. */ 221 222 bool 223 ptr_derefs_may_alias_p (tree ptr1, tree ptr2) 224 { 225 struct ptr_info_def *pi1, *pi2; 226 227 /* Conversions are irrelevant for points-to information and 228 data-dependence analysis can feed us those. */ 229 STRIP_NOPS (ptr1); 230 STRIP_NOPS (ptr2); 231 232 /* Disregard pointer offsetting. */ 233 if (TREE_CODE (ptr1) == POINTER_PLUS_EXPR) 234 { 235 do 236 { 237 ptr1 = TREE_OPERAND (ptr1, 0); 238 } 239 while (TREE_CODE (ptr1) == POINTER_PLUS_EXPR); 240 return ptr_derefs_may_alias_p (ptr1, ptr2); 241 } 242 if (TREE_CODE (ptr2) == POINTER_PLUS_EXPR) 243 { 244 do 245 { 246 ptr2 = TREE_OPERAND (ptr2, 0); 247 } 248 while (TREE_CODE (ptr2) == POINTER_PLUS_EXPR); 249 return ptr_derefs_may_alias_p (ptr1, ptr2); 250 } 251 252 /* ADDR_EXPR pointers either just offset another pointer or directly 253 specify the pointed-to set. */ 254 if (TREE_CODE (ptr1) == ADDR_EXPR) 255 { 256 tree base = get_base_address (TREE_OPERAND (ptr1, 0)); 257 if (base 258 && (TREE_CODE (base) == MEM_REF 259 || TREE_CODE (base) == TARGET_MEM_REF)) 260 return ptr_derefs_may_alias_p (TREE_OPERAND (base, 0), ptr2); 261 else if (base 262 && DECL_P (base)) 263 return ptr_deref_may_alias_decl_p (ptr2, base); 264 else 265 return true; 266 } 267 if (TREE_CODE (ptr2) == ADDR_EXPR) 268 { 269 tree base = get_base_address (TREE_OPERAND (ptr2, 0)); 270 if (base 271 && (TREE_CODE (base) == MEM_REF 272 || TREE_CODE (base) == TARGET_MEM_REF)) 273 return ptr_derefs_may_alias_p (ptr1, TREE_OPERAND (base, 0)); 274 else if (base 275 && DECL_P (base)) 276 return ptr_deref_may_alias_decl_p (ptr1, base); 277 else 278 return true; 279 } 280 281 /* From here we require SSA name pointers. Anything else aliases. */ 282 if (TREE_CODE (ptr1) != SSA_NAME 283 || TREE_CODE (ptr2) != SSA_NAME 284 || !POINTER_TYPE_P (TREE_TYPE (ptr1)) 285 || !POINTER_TYPE_P (TREE_TYPE (ptr2))) 286 return true; 287 288 /* We may end up with two empty points-to solutions for two same pointers. 289 In this case we still want to say both pointers alias, so shortcut 290 that here. */ 291 if (ptr1 == ptr2) 292 return true; 293 294 /* If we do not have useful points-to information for either pointer 295 we cannot disambiguate anything else. */ 296 pi1 = SSA_NAME_PTR_INFO (ptr1); 297 pi2 = SSA_NAME_PTR_INFO (ptr2); 298 if (!pi1 || !pi2) 299 return true; 300 301 /* ??? This does not use TBAA to prune decls from the intersection 302 that not both pointers may access. */ 303 return pt_solutions_intersect (&pi1->pt, &pi2->pt); 304 } 305 306 /* Return true if dereferencing PTR may alias *REF. 307 The caller is responsible for applying TBAA to see if PTR 308 may access *REF at all. */ 309 310 static bool 311 ptr_deref_may_alias_ref_p_1 (tree ptr, ao_ref *ref) 312 { 313 tree base = ao_ref_base (ref); 314 315 if (TREE_CODE (base) == MEM_REF 316 || TREE_CODE (base) == TARGET_MEM_REF) 317 return ptr_derefs_may_alias_p (ptr, TREE_OPERAND (base, 0)); 318 else if (DECL_P (base)) 319 return ptr_deref_may_alias_decl_p (ptr, base); 320 321 return true; 322 } 323 324 /* Returns true if PTR1 and PTR2 compare unequal because of points-to. */ 325 326 bool 327 ptrs_compare_unequal (tree ptr1, tree ptr2) 328 { 329 /* First resolve the pointers down to a SSA name pointer base or 330 a VAR_DECL, PARM_DECL or RESULT_DECL. This explicitely does 331 not yet try to handle LABEL_DECLs, FUNCTION_DECLs, CONST_DECLs 332 or STRING_CSTs which needs points-to adjustments to track them 333 in the points-to sets. */ 334 tree obj1 = NULL_TREE; 335 tree obj2 = NULL_TREE; 336 if (TREE_CODE (ptr1) == ADDR_EXPR) 337 { 338 tree tem = get_base_address (TREE_OPERAND (ptr1, 0)); 339 if (! tem) 340 return false; 341 if (VAR_P (tem) 342 || TREE_CODE (tem) == PARM_DECL 343 || TREE_CODE (tem) == RESULT_DECL) 344 obj1 = tem; 345 else if (TREE_CODE (tem) == MEM_REF) 346 ptr1 = TREE_OPERAND (tem, 0); 347 } 348 if (TREE_CODE (ptr2) == ADDR_EXPR) 349 { 350 tree tem = get_base_address (TREE_OPERAND (ptr2, 0)); 351 if (! tem) 352 return false; 353 if (VAR_P (tem) 354 || TREE_CODE (tem) == PARM_DECL 355 || TREE_CODE (tem) == RESULT_DECL) 356 obj2 = tem; 357 else if (TREE_CODE (tem) == MEM_REF) 358 ptr2 = TREE_OPERAND (tem, 0); 359 } 360 361 /* Canonicalize ptr vs. object. */ 362 if (TREE_CODE (ptr1) == SSA_NAME && obj2) 363 { 364 std::swap (ptr1, ptr2); 365 std::swap (obj1, obj2); 366 } 367 368 if (obj1 && obj2) 369 /* Other code handles this correctly, no need to duplicate it here. */; 370 else if (obj1 && TREE_CODE (ptr2) == SSA_NAME) 371 { 372 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr2); 373 /* We may not use restrict to optimize pointer comparisons. 374 See PR71062. So we have to assume that restrict-pointed-to 375 may be in fact obj1. */ 376 if (!pi 377 || pi->pt.vars_contains_restrict 378 || pi->pt.vars_contains_interposable) 379 return false; 380 if (VAR_P (obj1) 381 && (TREE_STATIC (obj1) || DECL_EXTERNAL (obj1))) 382 { 383 varpool_node *node = varpool_node::get (obj1); 384 /* If obj1 may bind to NULL give up (see below). */ 385 if (! node 386 || ! node->nonzero_address () 387 || ! decl_binds_to_current_def_p (obj1)) 388 return false; 389 } 390 return !pt_solution_includes (&pi->pt, obj1); 391 } 392 393 /* ??? We'd like to handle ptr1 != NULL and ptr1 != ptr2 394 but those require pt.null to be conservatively correct. */ 395 396 return false; 397 } 398 399 /* Returns whether reference REF to BASE may refer to global memory. */ 400 401 static bool 402 ref_may_alias_global_p_1 (tree base) 403 { 404 if (DECL_P (base)) 405 return is_global_var (base); 406 else if (TREE_CODE (base) == MEM_REF 407 || TREE_CODE (base) == TARGET_MEM_REF) 408 return ptr_deref_may_alias_global_p (TREE_OPERAND (base, 0)); 409 return true; 410 } 411 412 bool 413 ref_may_alias_global_p (ao_ref *ref) 414 { 415 tree base = ao_ref_base (ref); 416 return ref_may_alias_global_p_1 (base); 417 } 418 419 bool 420 ref_may_alias_global_p (tree ref) 421 { 422 tree base = get_base_address (ref); 423 return ref_may_alias_global_p_1 (base); 424 } 425 426 /* Return true whether STMT may clobber global memory. */ 427 428 bool 429 stmt_may_clobber_global_p (gimple *stmt) 430 { 431 tree lhs; 432 433 if (!gimple_vdef (stmt)) 434 return false; 435 436 /* ??? We can ask the oracle whether an artificial pointer 437 dereference with a pointer with points-to information covering 438 all global memory (what about non-address taken memory?) maybe 439 clobbered by this call. As there is at the moment no convenient 440 way of doing that without generating garbage do some manual 441 checking instead. 442 ??? We could make a NULL ao_ref argument to the various 443 predicates special, meaning any global memory. */ 444 445 switch (gimple_code (stmt)) 446 { 447 case GIMPLE_ASSIGN: 448 lhs = gimple_assign_lhs (stmt); 449 return (TREE_CODE (lhs) != SSA_NAME 450 && ref_may_alias_global_p (lhs)); 451 case GIMPLE_CALL: 452 return true; 453 default: 454 return true; 455 } 456 } 457 458 459 /* Dump alias information on FILE. */ 460 461 void 462 dump_alias_info (FILE *file) 463 { 464 unsigned i; 465 tree ptr; 466 const char *funcname 467 = lang_hooks.decl_printable_name (current_function_decl, 2); 468 tree var; 469 470 fprintf (file, "\n\nAlias information for %s\n\n", funcname); 471 472 fprintf (file, "Aliased symbols\n\n"); 473 474 FOR_EACH_LOCAL_DECL (cfun, i, var) 475 { 476 if (may_be_aliased (var)) 477 dump_variable (file, var); 478 } 479 480 fprintf (file, "\nCall clobber information\n"); 481 482 fprintf (file, "\nESCAPED"); 483 dump_points_to_solution (file, &cfun->gimple_df->escaped); 484 485 fprintf (file, "\n\nFlow-insensitive points-to information\n\n"); 486 487 FOR_EACH_SSA_NAME (i, ptr, cfun) 488 { 489 struct ptr_info_def *pi; 490 491 if (!POINTER_TYPE_P (TREE_TYPE (ptr)) 492 || SSA_NAME_IN_FREE_LIST (ptr)) 493 continue; 494 495 pi = SSA_NAME_PTR_INFO (ptr); 496 if (pi) 497 dump_points_to_info_for (file, ptr); 498 } 499 500 fprintf (file, "\n"); 501 } 502 503 504 /* Dump alias information on stderr. */ 505 506 DEBUG_FUNCTION void 507 debug_alias_info (void) 508 { 509 dump_alias_info (stderr); 510 } 511 512 513 /* Dump the points-to set *PT into FILE. */ 514 515 void 516 dump_points_to_solution (FILE *file, struct pt_solution *pt) 517 { 518 if (pt->anything) 519 fprintf (file, ", points-to anything"); 520 521 if (pt->nonlocal) 522 fprintf (file, ", points-to non-local"); 523 524 if (pt->escaped) 525 fprintf (file, ", points-to escaped"); 526 527 if (pt->ipa_escaped) 528 fprintf (file, ", points-to unit escaped"); 529 530 if (pt->null) 531 fprintf (file, ", points-to NULL"); 532 533 if (pt->vars) 534 { 535 fprintf (file, ", points-to vars: "); 536 dump_decl_set (file, pt->vars); 537 if (pt->vars_contains_nonlocal 538 || pt->vars_contains_escaped 539 || pt->vars_contains_escaped_heap 540 || pt->vars_contains_restrict) 541 { 542 const char *comma = ""; 543 fprintf (file, " ("); 544 if (pt->vars_contains_nonlocal) 545 { 546 fprintf (file, "nonlocal"); 547 comma = ", "; 548 } 549 if (pt->vars_contains_escaped) 550 { 551 fprintf (file, "%sescaped", comma); 552 comma = ", "; 553 } 554 if (pt->vars_contains_escaped_heap) 555 { 556 fprintf (file, "%sescaped heap", comma); 557 comma = ", "; 558 } 559 if (pt->vars_contains_restrict) 560 { 561 fprintf (file, "%srestrict", comma); 562 comma = ", "; 563 } 564 if (pt->vars_contains_interposable) 565 fprintf (file, "%sinterposable", comma); 566 fprintf (file, ")"); 567 } 568 } 569 } 570 571 572 /* Unified dump function for pt_solution. */ 573 574 DEBUG_FUNCTION void 575 debug (pt_solution &ref) 576 { 577 dump_points_to_solution (stderr, &ref); 578 } 579 580 DEBUG_FUNCTION void 581 debug (pt_solution *ptr) 582 { 583 if (ptr) 584 debug (*ptr); 585 else 586 fprintf (stderr, "<nil>\n"); 587 } 588 589 590 /* Dump points-to information for SSA_NAME PTR into FILE. */ 591 592 void 593 dump_points_to_info_for (FILE *file, tree ptr) 594 { 595 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr); 596 597 print_generic_expr (file, ptr, dump_flags); 598 599 if (pi) 600 dump_points_to_solution (file, &pi->pt); 601 else 602 fprintf (file, ", points-to anything"); 603 604 fprintf (file, "\n"); 605 } 606 607 608 /* Dump points-to information for VAR into stderr. */ 609 610 DEBUG_FUNCTION void 611 debug_points_to_info_for (tree var) 612 { 613 dump_points_to_info_for (stderr, var); 614 } 615 616 617 /* Initializes the alias-oracle reference representation *R from REF. */ 618 619 void 620 ao_ref_init (ao_ref *r, tree ref) 621 { 622 r->ref = ref; 623 r->base = NULL_TREE; 624 r->offset = 0; 625 r->size = -1; 626 r->max_size = -1; 627 r->ref_alias_set = -1; 628 r->base_alias_set = -1; 629 r->volatile_p = ref ? TREE_THIS_VOLATILE (ref) : false; 630 } 631 632 /* Returns the base object of the memory reference *REF. */ 633 634 tree 635 ao_ref_base (ao_ref *ref) 636 { 637 bool reverse; 638 639 if (ref->base) 640 return ref->base; 641 ref->base = get_ref_base_and_extent (ref->ref, &ref->offset, &ref->size, 642 &ref->max_size, &reverse); 643 return ref->base; 644 } 645 646 /* Returns the base object alias set of the memory reference *REF. */ 647 648 alias_set_type 649 ao_ref_base_alias_set (ao_ref *ref) 650 { 651 tree base_ref; 652 if (ref->base_alias_set != -1) 653 return ref->base_alias_set; 654 if (!ref->ref) 655 return 0; 656 base_ref = ref->ref; 657 while (handled_component_p (base_ref)) 658 base_ref = TREE_OPERAND (base_ref, 0); 659 ref->base_alias_set = get_alias_set (base_ref); 660 return ref->base_alias_set; 661 } 662 663 /* Returns the reference alias set of the memory reference *REF. */ 664 665 alias_set_type 666 ao_ref_alias_set (ao_ref *ref) 667 { 668 if (ref->ref_alias_set != -1) 669 return ref->ref_alias_set; 670 ref->ref_alias_set = get_alias_set (ref->ref); 671 return ref->ref_alias_set; 672 } 673 674 /* Init an alias-oracle reference representation from a gimple pointer 675 PTR and a gimple size SIZE in bytes. If SIZE is NULL_TREE then the 676 size is assumed to be unknown. The access is assumed to be only 677 to or after of the pointer target, not before it. */ 678 679 void 680 ao_ref_init_from_ptr_and_size (ao_ref *ref, tree ptr, tree size) 681 { 682 HOST_WIDE_INT t, size_hwi, extra_offset = 0; 683 ref->ref = NULL_TREE; 684 if (TREE_CODE (ptr) == SSA_NAME) 685 { 686 gimple *stmt = SSA_NAME_DEF_STMT (ptr); 687 if (gimple_assign_single_p (stmt) 688 && gimple_assign_rhs_code (stmt) == ADDR_EXPR) 689 ptr = gimple_assign_rhs1 (stmt); 690 else if (is_gimple_assign (stmt) 691 && gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR 692 && TREE_CODE (gimple_assign_rhs2 (stmt)) == INTEGER_CST) 693 { 694 ptr = gimple_assign_rhs1 (stmt); 695 extra_offset = BITS_PER_UNIT 696 * int_cst_value (gimple_assign_rhs2 (stmt)); 697 } 698 } 699 700 if (TREE_CODE (ptr) == ADDR_EXPR) 701 { 702 ref->base = get_addr_base_and_unit_offset (TREE_OPERAND (ptr, 0), &t); 703 if (ref->base) 704 ref->offset = BITS_PER_UNIT * t; 705 else 706 { 707 size = NULL_TREE; 708 ref->offset = 0; 709 ref->base = get_base_address (TREE_OPERAND (ptr, 0)); 710 } 711 } 712 else 713 { 714 ref->base = build2 (MEM_REF, char_type_node, 715 ptr, null_pointer_node); 716 ref->offset = 0; 717 } 718 ref->offset += extra_offset; 719 if (size 720 && tree_fits_shwi_p (size) 721 && (size_hwi = tree_to_shwi (size)) <= HOST_WIDE_INT_MAX / BITS_PER_UNIT) 722 ref->max_size = ref->size = size_hwi * BITS_PER_UNIT; 723 else 724 ref->max_size = ref->size = -1; 725 ref->ref_alias_set = 0; 726 ref->base_alias_set = 0; 727 ref->volatile_p = false; 728 } 729 730 /* Return 1 if TYPE1 and TYPE2 are to be considered equivalent for the 731 purpose of TBAA. Return 0 if they are distinct and -1 if we cannot 732 decide. */ 733 734 static inline int 735 same_type_for_tbaa (tree type1, tree type2) 736 { 737 type1 = TYPE_MAIN_VARIANT (type1); 738 type2 = TYPE_MAIN_VARIANT (type2); 739 740 /* If we would have to do structural comparison bail out. */ 741 if (TYPE_STRUCTURAL_EQUALITY_P (type1) 742 || TYPE_STRUCTURAL_EQUALITY_P (type2)) 743 return -1; 744 745 /* Compare the canonical types. */ 746 if (TYPE_CANONICAL (type1) == TYPE_CANONICAL (type2)) 747 return 1; 748 749 /* ??? Array types are not properly unified in all cases as we have 750 spurious changes in the index types for example. Removing this 751 causes all sorts of problems with the Fortran frontend. */ 752 if (TREE_CODE (type1) == ARRAY_TYPE 753 && TREE_CODE (type2) == ARRAY_TYPE) 754 return -1; 755 756 /* ??? In Ada, an lvalue of an unconstrained type can be used to access an 757 object of one of its constrained subtypes, e.g. when a function with an 758 unconstrained parameter passed by reference is called on an object and 759 inlined. But, even in the case of a fixed size, type and subtypes are 760 not equivalent enough as to share the same TYPE_CANONICAL, since this 761 would mean that conversions between them are useless, whereas they are 762 not (e.g. type and subtypes can have different modes). So, in the end, 763 they are only guaranteed to have the same alias set. */ 764 if (get_alias_set (type1) == get_alias_set (type2)) 765 return -1; 766 767 /* The types are known to be not equal. */ 768 return 0; 769 } 770 771 /* Determine if the two component references REF1 and REF2 which are 772 based on access types TYPE1 and TYPE2 and of which at least one is based 773 on an indirect reference may alias. REF2 is the only one that can 774 be a decl in which case REF2_IS_DECL is true. 775 REF1_ALIAS_SET, BASE1_ALIAS_SET, REF2_ALIAS_SET and BASE2_ALIAS_SET 776 are the respective alias sets. */ 777 778 static bool 779 aliasing_component_refs_p (tree ref1, 780 alias_set_type ref1_alias_set, 781 alias_set_type base1_alias_set, 782 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1, 783 tree ref2, 784 alias_set_type ref2_alias_set, 785 alias_set_type base2_alias_set, 786 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2, 787 bool ref2_is_decl) 788 { 789 /* If one reference is a component references through pointers try to find a 790 common base and apply offset based disambiguation. This handles 791 for example 792 struct A { int i; int j; } *q; 793 struct B { struct A a; int k; } *p; 794 disambiguating q->i and p->a.j. */ 795 tree base1, base2; 796 tree type1, type2; 797 tree *refp; 798 int same_p; 799 800 /* Choose bases and base types to search for. */ 801 base1 = ref1; 802 while (handled_component_p (base1)) 803 base1 = TREE_OPERAND (base1, 0); 804 type1 = TREE_TYPE (base1); 805 base2 = ref2; 806 while (handled_component_p (base2)) 807 base2 = TREE_OPERAND (base2, 0); 808 type2 = TREE_TYPE (base2); 809 810 /* Now search for the type1 in the access path of ref2. This 811 would be a common base for doing offset based disambiguation on. */ 812 refp = &ref2; 813 while (handled_component_p (*refp) 814 && same_type_for_tbaa (TREE_TYPE (*refp), type1) == 0) 815 refp = &TREE_OPERAND (*refp, 0); 816 same_p = same_type_for_tbaa (TREE_TYPE (*refp), type1); 817 /* If we couldn't compare types we have to bail out. */ 818 if (same_p == -1) 819 return true; 820 else if (same_p == 1) 821 { 822 HOST_WIDE_INT offadj, sztmp, msztmp; 823 bool reverse; 824 get_ref_base_and_extent (*refp, &offadj, &sztmp, &msztmp, &reverse); 825 offset2 -= offadj; 826 get_ref_base_and_extent (base1, &offadj, &sztmp, &msztmp, &reverse); 827 offset1 -= offadj; 828 return ranges_overlap_p (offset1, max_size1, offset2, max_size2); 829 } 830 /* If we didn't find a common base, try the other way around. */ 831 refp = &ref1; 832 while (handled_component_p (*refp) 833 && same_type_for_tbaa (TREE_TYPE (*refp), type2) == 0) 834 refp = &TREE_OPERAND (*refp, 0); 835 same_p = same_type_for_tbaa (TREE_TYPE (*refp), type2); 836 /* If we couldn't compare types we have to bail out. */ 837 if (same_p == -1) 838 return true; 839 else if (same_p == 1) 840 { 841 HOST_WIDE_INT offadj, sztmp, msztmp; 842 bool reverse; 843 get_ref_base_and_extent (*refp, &offadj, &sztmp, &msztmp, &reverse); 844 offset1 -= offadj; 845 get_ref_base_and_extent (base2, &offadj, &sztmp, &msztmp, &reverse); 846 offset2 -= offadj; 847 return ranges_overlap_p (offset1, max_size1, offset2, max_size2); 848 } 849 850 /* If we have two type access paths B1.path1 and B2.path2 they may 851 only alias if either B1 is in B2.path2 or B2 is in B1.path1. 852 But we can still have a path that goes B1.path1...B2.path2 with 853 a part that we do not see. So we can only disambiguate now 854 if there is no B2 in the tail of path1 and no B1 on the 855 tail of path2. */ 856 if (base1_alias_set == ref2_alias_set 857 || alias_set_subset_of (base1_alias_set, ref2_alias_set)) 858 return true; 859 /* If this is ptr vs. decl then we know there is no ptr ... decl path. */ 860 if (!ref2_is_decl) 861 return (base2_alias_set == ref1_alias_set 862 || alias_set_subset_of (base2_alias_set, ref1_alias_set)); 863 return false; 864 } 865 866 /* Return true if we can determine that component references REF1 and REF2, 867 that are within a common DECL, cannot overlap. */ 868 869 static bool 870 nonoverlapping_component_refs_of_decl_p (tree ref1, tree ref2) 871 { 872 auto_vec<tree, 16> component_refs1; 873 auto_vec<tree, 16> component_refs2; 874 875 /* Create the stack of handled components for REF1. */ 876 while (handled_component_p (ref1)) 877 { 878 component_refs1.safe_push (ref1); 879 ref1 = TREE_OPERAND (ref1, 0); 880 } 881 if (TREE_CODE (ref1) == MEM_REF) 882 { 883 if (!integer_zerop (TREE_OPERAND (ref1, 1))) 884 return false; 885 ref1 = TREE_OPERAND (TREE_OPERAND (ref1, 0), 0); 886 } 887 888 /* Create the stack of handled components for REF2. */ 889 while (handled_component_p (ref2)) 890 { 891 component_refs2.safe_push (ref2); 892 ref2 = TREE_OPERAND (ref2, 0); 893 } 894 if (TREE_CODE (ref2) == MEM_REF) 895 { 896 if (!integer_zerop (TREE_OPERAND (ref2, 1))) 897 return false; 898 ref2 = TREE_OPERAND (TREE_OPERAND (ref2, 0), 0); 899 } 900 901 /* Bases must be either same or uncomparable. */ 902 gcc_checking_assert (ref1 == ref2 903 || (DECL_P (ref1) && DECL_P (ref2) 904 && compare_base_decls (ref1, ref2) != 0)); 905 906 /* Pop the stacks in parallel and examine the COMPONENT_REFs of the same 907 rank. This is sufficient because we start from the same DECL and you 908 cannot reference several fields at a time with COMPONENT_REFs (unlike 909 with ARRAY_RANGE_REFs for arrays) so you always need the same number 910 of them to access a sub-component, unless you're in a union, in which 911 case the return value will precisely be false. */ 912 while (true) 913 { 914 do 915 { 916 if (component_refs1.is_empty ()) 917 return false; 918 ref1 = component_refs1.pop (); 919 } 920 while (!RECORD_OR_UNION_TYPE_P (TREE_TYPE (TREE_OPERAND (ref1, 0)))); 921 922 do 923 { 924 if (component_refs2.is_empty ()) 925 return false; 926 ref2 = component_refs2.pop (); 927 } 928 while (!RECORD_OR_UNION_TYPE_P (TREE_TYPE (TREE_OPERAND (ref2, 0)))); 929 930 /* Beware of BIT_FIELD_REF. */ 931 if (TREE_CODE (ref1) != COMPONENT_REF 932 || TREE_CODE (ref2) != COMPONENT_REF) 933 return false; 934 935 tree field1 = TREE_OPERAND (ref1, 1); 936 tree field2 = TREE_OPERAND (ref2, 1); 937 938 /* ??? We cannot simply use the type of operand #0 of the refs here 939 as the Fortran compiler smuggles type punning into COMPONENT_REFs 940 for common blocks instead of using unions like everyone else. */ 941 tree type1 = DECL_CONTEXT (field1); 942 tree type2 = DECL_CONTEXT (field2); 943 944 /* We cannot disambiguate fields in a union or qualified union. */ 945 if (type1 != type2 || TREE_CODE (type1) != RECORD_TYPE) 946 return false; 947 948 if (field1 != field2) 949 { 950 /* A field and its representative need to be considered the 951 same. */ 952 if (DECL_BIT_FIELD_REPRESENTATIVE (field1) == field2 953 || DECL_BIT_FIELD_REPRESENTATIVE (field2) == field1) 954 return false; 955 /* Different fields of the same record type cannot overlap. 956 ??? Bitfields can overlap at RTL level so punt on them. */ 957 if (DECL_BIT_FIELD (field1) && DECL_BIT_FIELD (field2)) 958 return false; 959 return true; 960 } 961 } 962 963 return false; 964 } 965 966 /* qsort compare function to sort FIELD_DECLs after their 967 DECL_FIELD_CONTEXT TYPE_UID. */ 968 969 static inline int 970 ncr_compar (const void *field1_, const void *field2_) 971 { 972 const_tree field1 = *(const_tree *) const_cast <void *>(field1_); 973 const_tree field2 = *(const_tree *) const_cast <void *>(field2_); 974 unsigned int uid1 = TYPE_UID (DECL_FIELD_CONTEXT (field1)); 975 unsigned int uid2 = TYPE_UID (DECL_FIELD_CONTEXT (field2)); 976 if (uid1 < uid2) 977 return -1; 978 else if (uid1 > uid2) 979 return 1; 980 return 0; 981 } 982 983 /* Return true if we can determine that the fields referenced cannot 984 overlap for any pair of objects. */ 985 986 static bool 987 nonoverlapping_component_refs_p (const_tree x, const_tree y) 988 { 989 if (!flag_strict_aliasing 990 || !x || !y 991 || TREE_CODE (x) != COMPONENT_REF 992 || TREE_CODE (y) != COMPONENT_REF) 993 return false; 994 995 auto_vec<const_tree, 16> fieldsx; 996 while (TREE_CODE (x) == COMPONENT_REF) 997 { 998 tree field = TREE_OPERAND (x, 1); 999 tree type = DECL_FIELD_CONTEXT (field); 1000 if (TREE_CODE (type) == RECORD_TYPE) 1001 fieldsx.safe_push (field); 1002 x = TREE_OPERAND (x, 0); 1003 } 1004 if (fieldsx.length () == 0) 1005 return false; 1006 auto_vec<const_tree, 16> fieldsy; 1007 while (TREE_CODE (y) == COMPONENT_REF) 1008 { 1009 tree field = TREE_OPERAND (y, 1); 1010 tree type = DECL_FIELD_CONTEXT (field); 1011 if (TREE_CODE (type) == RECORD_TYPE) 1012 fieldsy.safe_push (TREE_OPERAND (y, 1)); 1013 y = TREE_OPERAND (y, 0); 1014 } 1015 if (fieldsy.length () == 0) 1016 return false; 1017 1018 /* Most common case first. */ 1019 if (fieldsx.length () == 1 1020 && fieldsy.length () == 1) 1021 return ((DECL_FIELD_CONTEXT (fieldsx[0]) 1022 == DECL_FIELD_CONTEXT (fieldsy[0])) 1023 && fieldsx[0] != fieldsy[0] 1024 && !(DECL_BIT_FIELD (fieldsx[0]) && DECL_BIT_FIELD (fieldsy[0]))); 1025 1026 if (fieldsx.length () == 2) 1027 { 1028 if (ncr_compar (&fieldsx[0], &fieldsx[1]) == 1) 1029 std::swap (fieldsx[0], fieldsx[1]); 1030 } 1031 else 1032 fieldsx.qsort (ncr_compar); 1033 1034 if (fieldsy.length () == 2) 1035 { 1036 if (ncr_compar (&fieldsy[0], &fieldsy[1]) == 1) 1037 std::swap (fieldsy[0], fieldsy[1]); 1038 } 1039 else 1040 fieldsy.qsort (ncr_compar); 1041 1042 unsigned i = 0, j = 0; 1043 do 1044 { 1045 const_tree fieldx = fieldsx[i]; 1046 const_tree fieldy = fieldsy[j]; 1047 tree typex = DECL_FIELD_CONTEXT (fieldx); 1048 tree typey = DECL_FIELD_CONTEXT (fieldy); 1049 if (typex == typey) 1050 { 1051 /* We're left with accessing different fields of a structure, 1052 no possible overlap. */ 1053 if (fieldx != fieldy) 1054 { 1055 /* A field and its representative need to be considered the 1056 same. */ 1057 if (DECL_BIT_FIELD_REPRESENTATIVE (fieldx) == fieldy 1058 || DECL_BIT_FIELD_REPRESENTATIVE (fieldy) == fieldx) 1059 return false; 1060 /* Different fields of the same record type cannot overlap. 1061 ??? Bitfields can overlap at RTL level so punt on them. */ 1062 if (DECL_BIT_FIELD (fieldx) && DECL_BIT_FIELD (fieldy)) 1063 return false; 1064 return true; 1065 } 1066 } 1067 if (TYPE_UID (typex) < TYPE_UID (typey)) 1068 { 1069 i++; 1070 if (i == fieldsx.length ()) 1071 break; 1072 } 1073 else 1074 { 1075 j++; 1076 if (j == fieldsy.length ()) 1077 break; 1078 } 1079 } 1080 while (1); 1081 1082 return false; 1083 } 1084 1085 1086 /* Return true if two memory references based on the variables BASE1 1087 and BASE2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and 1088 [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. REF1 and REF2 1089 if non-NULL are the complete memory reference trees. */ 1090 1091 static bool 1092 decl_refs_may_alias_p (tree ref1, tree base1, 1093 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1, 1094 tree ref2, tree base2, 1095 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2) 1096 { 1097 gcc_checking_assert (DECL_P (base1) && DECL_P (base2)); 1098 1099 /* If both references are based on different variables, they cannot alias. */ 1100 if (compare_base_decls (base1, base2) == 0) 1101 return false; 1102 1103 /* If both references are based on the same variable, they cannot alias if 1104 the accesses do not overlap. */ 1105 if (!ranges_overlap_p (offset1, max_size1, offset2, max_size2)) 1106 return false; 1107 1108 /* For components with variable position, the above test isn't sufficient, 1109 so we disambiguate component references manually. */ 1110 if (ref1 && ref2 1111 && handled_component_p (ref1) && handled_component_p (ref2) 1112 && nonoverlapping_component_refs_of_decl_p (ref1, ref2)) 1113 return false; 1114 1115 return true; 1116 } 1117 1118 /* Return true if an indirect reference based on *PTR1 constrained 1119 to [OFFSET1, OFFSET1 + MAX_SIZE1) may alias a variable based on BASE2 1120 constrained to [OFFSET2, OFFSET2 + MAX_SIZE2). *PTR1 and BASE2 have 1121 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1 1122 in which case they are computed on-demand. REF1 and REF2 1123 if non-NULL are the complete memory reference trees. */ 1124 1125 static bool 1126 indirect_ref_may_alias_decl_p (tree ref1 ATTRIBUTE_UNUSED, tree base1, 1127 HOST_WIDE_INT offset1, 1128 HOST_WIDE_INT max_size1 ATTRIBUTE_UNUSED, 1129 alias_set_type ref1_alias_set, 1130 alias_set_type base1_alias_set, 1131 tree ref2 ATTRIBUTE_UNUSED, tree base2, 1132 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2, 1133 alias_set_type ref2_alias_set, 1134 alias_set_type base2_alias_set, bool tbaa_p) 1135 { 1136 tree ptr1; 1137 tree ptrtype1, dbase2; 1138 HOST_WIDE_INT offset1p = offset1, offset2p = offset2; 1139 HOST_WIDE_INT doffset1, doffset2; 1140 1141 gcc_checking_assert ((TREE_CODE (base1) == MEM_REF 1142 || TREE_CODE (base1) == TARGET_MEM_REF) 1143 && DECL_P (base2)); 1144 1145 ptr1 = TREE_OPERAND (base1, 0); 1146 1147 /* The offset embedded in MEM_REFs can be negative. Bias them 1148 so that the resulting offset adjustment is positive. */ 1149 offset_int moff = mem_ref_offset (base1); 1150 moff <<= LOG2_BITS_PER_UNIT; 1151 if (wi::neg_p (moff)) 1152 offset2p += (-moff).to_short_addr (); 1153 else 1154 offset1p += moff.to_short_addr (); 1155 1156 /* If only one reference is based on a variable, they cannot alias if 1157 the pointer access is beyond the extent of the variable access. 1158 (the pointer base cannot validly point to an offset less than zero 1159 of the variable). 1160 ??? IVOPTs creates bases that do not honor this restriction, 1161 so do not apply this optimization for TARGET_MEM_REFs. */ 1162 if (TREE_CODE (base1) != TARGET_MEM_REF 1163 && !ranges_overlap_p (MAX (0, offset1p), -1, offset2p, max_size2)) 1164 return false; 1165 /* They also cannot alias if the pointer may not point to the decl. */ 1166 if (!ptr_deref_may_alias_decl_p (ptr1, base2)) 1167 return false; 1168 1169 /* Disambiguations that rely on strict aliasing rules follow. */ 1170 if (!flag_strict_aliasing || !tbaa_p) 1171 return true; 1172 1173 ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1)); 1174 1175 /* If the alias set for a pointer access is zero all bets are off. */ 1176 if (base1_alias_set == 0) 1177 return true; 1178 1179 /* When we are trying to disambiguate an access with a pointer dereference 1180 as base versus one with a decl as base we can use both the size 1181 of the decl and its dynamic type for extra disambiguation. 1182 ??? We do not know anything about the dynamic type of the decl 1183 other than that its alias-set contains base2_alias_set as a subset 1184 which does not help us here. */ 1185 /* As we know nothing useful about the dynamic type of the decl just 1186 use the usual conflict check rather than a subset test. 1187 ??? We could introduce -fvery-strict-aliasing when the language 1188 does not allow decls to have a dynamic type that differs from their 1189 static type. Then we can check 1190 !alias_set_subset_of (base1_alias_set, base2_alias_set) instead. */ 1191 if (base1_alias_set != base2_alias_set 1192 && !alias_sets_conflict_p (base1_alias_set, base2_alias_set)) 1193 return false; 1194 /* If the size of the access relevant for TBAA through the pointer 1195 is bigger than the size of the decl we can't possibly access the 1196 decl via that pointer. */ 1197 if (DECL_SIZE (base2) && COMPLETE_TYPE_P (TREE_TYPE (ptrtype1)) 1198 && TREE_CODE (DECL_SIZE (base2)) == INTEGER_CST 1199 && TREE_CODE (TYPE_SIZE (TREE_TYPE (ptrtype1))) == INTEGER_CST 1200 /* ??? This in turn may run afoul when a decl of type T which is 1201 a member of union type U is accessed through a pointer to 1202 type U and sizeof T is smaller than sizeof U. */ 1203 && TREE_CODE (TREE_TYPE (ptrtype1)) != UNION_TYPE 1204 && TREE_CODE (TREE_TYPE (ptrtype1)) != QUAL_UNION_TYPE 1205 && tree_int_cst_lt (DECL_SIZE (base2), TYPE_SIZE (TREE_TYPE (ptrtype1)))) 1206 return false; 1207 1208 if (!ref2) 1209 return true; 1210 1211 /* If the decl is accessed via a MEM_REF, reconstruct the base 1212 we can use for TBAA and an appropriately adjusted offset. */ 1213 dbase2 = ref2; 1214 while (handled_component_p (dbase2)) 1215 dbase2 = TREE_OPERAND (dbase2, 0); 1216 doffset1 = offset1; 1217 doffset2 = offset2; 1218 if (TREE_CODE (dbase2) == MEM_REF 1219 || TREE_CODE (dbase2) == TARGET_MEM_REF) 1220 { 1221 offset_int moff = mem_ref_offset (dbase2); 1222 moff <<= LOG2_BITS_PER_UNIT; 1223 if (wi::neg_p (moff)) 1224 doffset1 -= (-moff).to_short_addr (); 1225 else 1226 doffset2 -= moff.to_short_addr (); 1227 } 1228 1229 /* If either reference is view-converted, give up now. */ 1230 if (same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) != 1 1231 || same_type_for_tbaa (TREE_TYPE (dbase2), TREE_TYPE (base2)) != 1) 1232 return true; 1233 1234 /* If both references are through the same type, they do not alias 1235 if the accesses do not overlap. This does extra disambiguation 1236 for mixed/pointer accesses but requires strict aliasing. 1237 For MEM_REFs we require that the component-ref offset we computed 1238 is relative to the start of the type which we ensure by 1239 comparing rvalue and access type and disregarding the constant 1240 pointer offset. */ 1241 if ((TREE_CODE (base1) != TARGET_MEM_REF 1242 || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1))) 1243 && same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (dbase2)) == 1) 1244 return ranges_overlap_p (doffset1, max_size1, doffset2, max_size2); 1245 1246 if (ref1 && ref2 1247 && nonoverlapping_component_refs_p (ref1, ref2)) 1248 return false; 1249 1250 /* Do access-path based disambiguation. */ 1251 if (ref1 && ref2 1252 && (handled_component_p (ref1) || handled_component_p (ref2))) 1253 return aliasing_component_refs_p (ref1, 1254 ref1_alias_set, base1_alias_set, 1255 offset1, max_size1, 1256 ref2, 1257 ref2_alias_set, base2_alias_set, 1258 offset2, max_size2, true); 1259 1260 return true; 1261 } 1262 1263 /* Return true if two indirect references based on *PTR1 1264 and *PTR2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and 1265 [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. *PTR1 and *PTR2 have 1266 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1 1267 in which case they are computed on-demand. REF1 and REF2 1268 if non-NULL are the complete memory reference trees. */ 1269 1270 static bool 1271 indirect_refs_may_alias_p (tree ref1 ATTRIBUTE_UNUSED, tree base1, 1272 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1, 1273 alias_set_type ref1_alias_set, 1274 alias_set_type base1_alias_set, 1275 tree ref2 ATTRIBUTE_UNUSED, tree base2, 1276 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2, 1277 alias_set_type ref2_alias_set, 1278 alias_set_type base2_alias_set, bool tbaa_p) 1279 { 1280 tree ptr1; 1281 tree ptr2; 1282 tree ptrtype1, ptrtype2; 1283 1284 gcc_checking_assert ((TREE_CODE (base1) == MEM_REF 1285 || TREE_CODE (base1) == TARGET_MEM_REF) 1286 && (TREE_CODE (base2) == MEM_REF 1287 || TREE_CODE (base2) == TARGET_MEM_REF)); 1288 1289 ptr1 = TREE_OPERAND (base1, 0); 1290 ptr2 = TREE_OPERAND (base2, 0); 1291 1292 /* If both bases are based on pointers they cannot alias if they may not 1293 point to the same memory object or if they point to the same object 1294 and the accesses do not overlap. */ 1295 if ((!cfun || gimple_in_ssa_p (cfun)) 1296 && operand_equal_p (ptr1, ptr2, 0) 1297 && (((TREE_CODE (base1) != TARGET_MEM_REF 1298 || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1))) 1299 && (TREE_CODE (base2) != TARGET_MEM_REF 1300 || (!TMR_INDEX (base2) && !TMR_INDEX2 (base2)))) 1301 || (TREE_CODE (base1) == TARGET_MEM_REF 1302 && TREE_CODE (base2) == TARGET_MEM_REF 1303 && (TMR_STEP (base1) == TMR_STEP (base2) 1304 || (TMR_STEP (base1) && TMR_STEP (base2) 1305 && operand_equal_p (TMR_STEP (base1), 1306 TMR_STEP (base2), 0))) 1307 && (TMR_INDEX (base1) == TMR_INDEX (base2) 1308 || (TMR_INDEX (base1) && TMR_INDEX (base2) 1309 && operand_equal_p (TMR_INDEX (base1), 1310 TMR_INDEX (base2), 0))) 1311 && (TMR_INDEX2 (base1) == TMR_INDEX2 (base2) 1312 || (TMR_INDEX2 (base1) && TMR_INDEX2 (base2) 1313 && operand_equal_p (TMR_INDEX2 (base1), 1314 TMR_INDEX2 (base2), 0)))))) 1315 { 1316 offset_int moff; 1317 /* The offset embedded in MEM_REFs can be negative. Bias them 1318 so that the resulting offset adjustment is positive. */ 1319 moff = mem_ref_offset (base1); 1320 moff <<= LOG2_BITS_PER_UNIT; 1321 if (wi::neg_p (moff)) 1322 offset2 += (-moff).to_short_addr (); 1323 else 1324 offset1 += moff.to_shwi (); 1325 moff = mem_ref_offset (base2); 1326 moff <<= LOG2_BITS_PER_UNIT; 1327 if (wi::neg_p (moff)) 1328 offset1 += (-moff).to_short_addr (); 1329 else 1330 offset2 += moff.to_short_addr (); 1331 return ranges_overlap_p (offset1, max_size1, offset2, max_size2); 1332 } 1333 if (!ptr_derefs_may_alias_p (ptr1, ptr2)) 1334 return false; 1335 1336 /* Disambiguations that rely on strict aliasing rules follow. */ 1337 if (!flag_strict_aliasing || !tbaa_p) 1338 return true; 1339 1340 ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1)); 1341 ptrtype2 = TREE_TYPE (TREE_OPERAND (base2, 1)); 1342 1343 /* If the alias set for a pointer access is zero all bets are off. */ 1344 if (base1_alias_set == 0 1345 || base2_alias_set == 0) 1346 return true; 1347 1348 /* If both references are through the same type, they do not alias 1349 if the accesses do not overlap. This does extra disambiguation 1350 for mixed/pointer accesses but requires strict aliasing. */ 1351 if ((TREE_CODE (base1) != TARGET_MEM_REF 1352 || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1))) 1353 && (TREE_CODE (base2) != TARGET_MEM_REF 1354 || (!TMR_INDEX (base2) && !TMR_INDEX2 (base2))) 1355 && same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1 1356 && same_type_for_tbaa (TREE_TYPE (base2), TREE_TYPE (ptrtype2)) == 1 1357 && same_type_for_tbaa (TREE_TYPE (ptrtype1), 1358 TREE_TYPE (ptrtype2)) == 1 1359 /* But avoid treating arrays as "objects", instead assume they 1360 can overlap by an exact multiple of their element size. */ 1361 && TREE_CODE (TREE_TYPE (ptrtype1)) != ARRAY_TYPE) 1362 return ranges_overlap_p (offset1, max_size1, offset2, max_size2); 1363 1364 /* Do type-based disambiguation. */ 1365 if (base1_alias_set != base2_alias_set 1366 && !alias_sets_conflict_p (base1_alias_set, base2_alias_set)) 1367 return false; 1368 1369 /* If either reference is view-converted, give up now. */ 1370 if (same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) != 1 1371 || same_type_for_tbaa (TREE_TYPE (base2), TREE_TYPE (ptrtype2)) != 1) 1372 return true; 1373 1374 if (ref1 && ref2 1375 && nonoverlapping_component_refs_p (ref1, ref2)) 1376 return false; 1377 1378 /* Do access-path based disambiguation. */ 1379 if (ref1 && ref2 1380 && (handled_component_p (ref1) || handled_component_p (ref2))) 1381 return aliasing_component_refs_p (ref1, 1382 ref1_alias_set, base1_alias_set, 1383 offset1, max_size1, 1384 ref2, 1385 ref2_alias_set, base2_alias_set, 1386 offset2, max_size2, false); 1387 1388 return true; 1389 } 1390 1391 /* Return true, if the two memory references REF1 and REF2 may alias. */ 1392 1393 bool 1394 refs_may_alias_p_1 (ao_ref *ref1, ao_ref *ref2, bool tbaa_p) 1395 { 1396 tree base1, base2; 1397 HOST_WIDE_INT offset1 = 0, offset2 = 0; 1398 HOST_WIDE_INT max_size1 = -1, max_size2 = -1; 1399 bool var1_p, var2_p, ind1_p, ind2_p; 1400 1401 gcc_checking_assert ((!ref1->ref 1402 || TREE_CODE (ref1->ref) == SSA_NAME 1403 || DECL_P (ref1->ref) 1404 || TREE_CODE (ref1->ref) == STRING_CST 1405 || handled_component_p (ref1->ref) 1406 || TREE_CODE (ref1->ref) == MEM_REF 1407 || TREE_CODE (ref1->ref) == TARGET_MEM_REF) 1408 && (!ref2->ref 1409 || TREE_CODE (ref2->ref) == SSA_NAME 1410 || DECL_P (ref2->ref) 1411 || TREE_CODE (ref2->ref) == STRING_CST 1412 || handled_component_p (ref2->ref) 1413 || TREE_CODE (ref2->ref) == MEM_REF 1414 || TREE_CODE (ref2->ref) == TARGET_MEM_REF)); 1415 1416 /* Decompose the references into their base objects and the access. */ 1417 base1 = ao_ref_base (ref1); 1418 offset1 = ref1->offset; 1419 max_size1 = ref1->max_size; 1420 base2 = ao_ref_base (ref2); 1421 offset2 = ref2->offset; 1422 max_size2 = ref2->max_size; 1423 1424 /* We can end up with registers or constants as bases for example from 1425 *D.1663_44 = VIEW_CONVERT_EXPR<struct DB_LSN>(__tmp$B0F64_59); 1426 which is seen as a struct copy. */ 1427 if (TREE_CODE (base1) == SSA_NAME 1428 || TREE_CODE (base1) == CONST_DECL 1429 || TREE_CODE (base1) == CONSTRUCTOR 1430 || TREE_CODE (base1) == ADDR_EXPR 1431 || CONSTANT_CLASS_P (base1) 1432 || TREE_CODE (base2) == SSA_NAME 1433 || TREE_CODE (base2) == CONST_DECL 1434 || TREE_CODE (base2) == CONSTRUCTOR 1435 || TREE_CODE (base2) == ADDR_EXPR 1436 || CONSTANT_CLASS_P (base2)) 1437 return false; 1438 1439 /* We can end up referring to code via function and label decls. 1440 As we likely do not properly track code aliases conservatively 1441 bail out. */ 1442 if (TREE_CODE (base1) == FUNCTION_DECL 1443 || TREE_CODE (base1) == LABEL_DECL 1444 || TREE_CODE (base2) == FUNCTION_DECL 1445 || TREE_CODE (base2) == LABEL_DECL) 1446 return true; 1447 1448 /* Two volatile accesses always conflict. */ 1449 if (ref1->volatile_p 1450 && ref2->volatile_p) 1451 return true; 1452 1453 /* Defer to simple offset based disambiguation if we have 1454 references based on two decls. Do this before defering to 1455 TBAA to handle must-alias cases in conformance with the 1456 GCC extension of allowing type-punning through unions. */ 1457 var1_p = DECL_P (base1); 1458 var2_p = DECL_P (base2); 1459 if (var1_p && var2_p) 1460 return decl_refs_may_alias_p (ref1->ref, base1, offset1, max_size1, 1461 ref2->ref, base2, offset2, max_size2); 1462 1463 /* Handle restrict based accesses. 1464 ??? ao_ref_base strips inner MEM_REF [&decl], recover from that 1465 here. */ 1466 tree rbase1 = base1; 1467 tree rbase2 = base2; 1468 if (var1_p) 1469 { 1470 rbase1 = ref1->ref; 1471 if (rbase1) 1472 while (handled_component_p (rbase1)) 1473 rbase1 = TREE_OPERAND (rbase1, 0); 1474 } 1475 if (var2_p) 1476 { 1477 rbase2 = ref2->ref; 1478 if (rbase2) 1479 while (handled_component_p (rbase2)) 1480 rbase2 = TREE_OPERAND (rbase2, 0); 1481 } 1482 if (rbase1 && rbase2 1483 && (TREE_CODE (base1) == MEM_REF || TREE_CODE (base1) == TARGET_MEM_REF) 1484 && (TREE_CODE (base2) == MEM_REF || TREE_CODE (base2) == TARGET_MEM_REF) 1485 /* If the accesses are in the same restrict clique... */ 1486 && MR_DEPENDENCE_CLIQUE (base1) == MR_DEPENDENCE_CLIQUE (base2) 1487 /* But based on different pointers they do not alias. */ 1488 && MR_DEPENDENCE_BASE (base1) != MR_DEPENDENCE_BASE (base2)) 1489 return false; 1490 1491 ind1_p = (TREE_CODE (base1) == MEM_REF 1492 || TREE_CODE (base1) == TARGET_MEM_REF); 1493 ind2_p = (TREE_CODE (base2) == MEM_REF 1494 || TREE_CODE (base2) == TARGET_MEM_REF); 1495 1496 /* Canonicalize the pointer-vs-decl case. */ 1497 if (ind1_p && var2_p) 1498 { 1499 std::swap (offset1, offset2); 1500 std::swap (max_size1, max_size2); 1501 std::swap (base1, base2); 1502 std::swap (ref1, ref2); 1503 var1_p = true; 1504 ind1_p = false; 1505 var2_p = false; 1506 ind2_p = true; 1507 } 1508 1509 /* First defer to TBAA if possible. */ 1510 if (tbaa_p 1511 && flag_strict_aliasing 1512 && !alias_sets_conflict_p (ao_ref_alias_set (ref1), 1513 ao_ref_alias_set (ref2))) 1514 return false; 1515 1516 /* Dispatch to the pointer-vs-decl or pointer-vs-pointer disambiguators. */ 1517 if (var1_p && ind2_p) 1518 return indirect_ref_may_alias_decl_p (ref2->ref, base2, 1519 offset2, max_size2, 1520 ao_ref_alias_set (ref2), 1521 ao_ref_base_alias_set (ref2), 1522 ref1->ref, base1, 1523 offset1, max_size1, 1524 ao_ref_alias_set (ref1), 1525 ao_ref_base_alias_set (ref1), 1526 tbaa_p); 1527 else if (ind1_p && ind2_p) 1528 return indirect_refs_may_alias_p (ref1->ref, base1, 1529 offset1, max_size1, 1530 ao_ref_alias_set (ref1), 1531 ao_ref_base_alias_set (ref1), 1532 ref2->ref, base2, 1533 offset2, max_size2, 1534 ao_ref_alias_set (ref2), 1535 ao_ref_base_alias_set (ref2), 1536 tbaa_p); 1537 1538 gcc_unreachable (); 1539 } 1540 1541 static bool 1542 refs_may_alias_p (tree ref1, ao_ref *ref2) 1543 { 1544 ao_ref r1; 1545 ao_ref_init (&r1, ref1); 1546 return refs_may_alias_p_1 (&r1, ref2, true); 1547 } 1548 1549 bool 1550 refs_may_alias_p (tree ref1, tree ref2) 1551 { 1552 ao_ref r1, r2; 1553 bool res; 1554 ao_ref_init (&r1, ref1); 1555 ao_ref_init (&r2, ref2); 1556 res = refs_may_alias_p_1 (&r1, &r2, true); 1557 if (res) 1558 ++alias_stats.refs_may_alias_p_may_alias; 1559 else 1560 ++alias_stats.refs_may_alias_p_no_alias; 1561 return res; 1562 } 1563 1564 /* Returns true if there is a anti-dependence for the STORE that 1565 executes after the LOAD. */ 1566 1567 bool 1568 refs_anti_dependent_p (tree load, tree store) 1569 { 1570 ao_ref r1, r2; 1571 ao_ref_init (&r1, load); 1572 ao_ref_init (&r2, store); 1573 return refs_may_alias_p_1 (&r1, &r2, false); 1574 } 1575 1576 /* Returns true if there is a output dependence for the stores 1577 STORE1 and STORE2. */ 1578 1579 bool 1580 refs_output_dependent_p (tree store1, tree store2) 1581 { 1582 ao_ref r1, r2; 1583 ao_ref_init (&r1, store1); 1584 ao_ref_init (&r2, store2); 1585 return refs_may_alias_p_1 (&r1, &r2, false); 1586 } 1587 1588 /* If the call CALL may use the memory reference REF return true, 1589 otherwise return false. */ 1590 1591 static bool 1592 ref_maybe_used_by_call_p_1 (gcall *call, ao_ref *ref) 1593 { 1594 tree base, callee; 1595 unsigned i; 1596 int flags = gimple_call_flags (call); 1597 1598 /* Const functions without a static chain do not implicitly use memory. */ 1599 if (!gimple_call_chain (call) 1600 && (flags & (ECF_CONST|ECF_NOVOPS))) 1601 goto process_args; 1602 1603 base = ao_ref_base (ref); 1604 if (!base) 1605 return true; 1606 1607 /* A call that is not without side-effects might involve volatile 1608 accesses and thus conflicts with all other volatile accesses. */ 1609 if (ref->volatile_p) 1610 return true; 1611 1612 /* If the reference is based on a decl that is not aliased the call 1613 cannot possibly use it. */ 1614 if (DECL_P (base) 1615 && !may_be_aliased (base) 1616 /* But local statics can be used through recursion. */ 1617 && !is_global_var (base)) 1618 goto process_args; 1619 1620 callee = gimple_call_fndecl (call); 1621 1622 /* Handle those builtin functions explicitly that do not act as 1623 escape points. See tree-ssa-structalias.c:find_func_aliases 1624 for the list of builtins we might need to handle here. */ 1625 if (callee != NULL_TREE 1626 && gimple_call_builtin_p (call, BUILT_IN_NORMAL)) 1627 switch (DECL_FUNCTION_CODE (callee)) 1628 { 1629 /* All the following functions read memory pointed to by 1630 their second argument. strcat/strncat additionally 1631 reads memory pointed to by the first argument. */ 1632 case BUILT_IN_STRCAT: 1633 case BUILT_IN_STRNCAT: 1634 { 1635 ao_ref dref; 1636 ao_ref_init_from_ptr_and_size (&dref, 1637 gimple_call_arg (call, 0), 1638 NULL_TREE); 1639 if (refs_may_alias_p_1 (&dref, ref, false)) 1640 return true; 1641 } 1642 /* FALLTHRU */ 1643 case BUILT_IN_STRCPY: 1644 case BUILT_IN_STRNCPY: 1645 case BUILT_IN_MEMCPY: 1646 case BUILT_IN_MEMMOVE: 1647 case BUILT_IN_MEMPCPY: 1648 case BUILT_IN_STPCPY: 1649 case BUILT_IN_STPNCPY: 1650 case BUILT_IN_TM_MEMCPY: 1651 case BUILT_IN_TM_MEMMOVE: 1652 { 1653 ao_ref dref; 1654 tree size = NULL_TREE; 1655 if (gimple_call_num_args (call) == 3) 1656 size = gimple_call_arg (call, 2); 1657 ao_ref_init_from_ptr_and_size (&dref, 1658 gimple_call_arg (call, 1), 1659 size); 1660 return refs_may_alias_p_1 (&dref, ref, false); 1661 } 1662 case BUILT_IN_STRCAT_CHK: 1663 case BUILT_IN_STRNCAT_CHK: 1664 { 1665 ao_ref dref; 1666 ao_ref_init_from_ptr_and_size (&dref, 1667 gimple_call_arg (call, 0), 1668 NULL_TREE); 1669 if (refs_may_alias_p_1 (&dref, ref, false)) 1670 return true; 1671 } 1672 /* FALLTHRU */ 1673 case BUILT_IN_STRCPY_CHK: 1674 case BUILT_IN_STRNCPY_CHK: 1675 case BUILT_IN_MEMCPY_CHK: 1676 case BUILT_IN_MEMMOVE_CHK: 1677 case BUILT_IN_MEMPCPY_CHK: 1678 case BUILT_IN_STPCPY_CHK: 1679 case BUILT_IN_STPNCPY_CHK: 1680 { 1681 ao_ref dref; 1682 tree size = NULL_TREE; 1683 if (gimple_call_num_args (call) == 4) 1684 size = gimple_call_arg (call, 2); 1685 ao_ref_init_from_ptr_and_size (&dref, 1686 gimple_call_arg (call, 1), 1687 size); 1688 return refs_may_alias_p_1 (&dref, ref, false); 1689 } 1690 case BUILT_IN_BCOPY: 1691 { 1692 ao_ref dref; 1693 tree size = gimple_call_arg (call, 2); 1694 ao_ref_init_from_ptr_and_size (&dref, 1695 gimple_call_arg (call, 0), 1696 size); 1697 return refs_may_alias_p_1 (&dref, ref, false); 1698 } 1699 1700 /* The following functions read memory pointed to by their 1701 first argument. */ 1702 CASE_BUILT_IN_TM_LOAD (1): 1703 CASE_BUILT_IN_TM_LOAD (2): 1704 CASE_BUILT_IN_TM_LOAD (4): 1705 CASE_BUILT_IN_TM_LOAD (8): 1706 CASE_BUILT_IN_TM_LOAD (FLOAT): 1707 CASE_BUILT_IN_TM_LOAD (DOUBLE): 1708 CASE_BUILT_IN_TM_LOAD (LDOUBLE): 1709 CASE_BUILT_IN_TM_LOAD (M64): 1710 CASE_BUILT_IN_TM_LOAD (M128): 1711 CASE_BUILT_IN_TM_LOAD (M256): 1712 case BUILT_IN_TM_LOG: 1713 case BUILT_IN_TM_LOG_1: 1714 case BUILT_IN_TM_LOG_2: 1715 case BUILT_IN_TM_LOG_4: 1716 case BUILT_IN_TM_LOG_8: 1717 case BUILT_IN_TM_LOG_FLOAT: 1718 case BUILT_IN_TM_LOG_DOUBLE: 1719 case BUILT_IN_TM_LOG_LDOUBLE: 1720 case BUILT_IN_TM_LOG_M64: 1721 case BUILT_IN_TM_LOG_M128: 1722 case BUILT_IN_TM_LOG_M256: 1723 return ptr_deref_may_alias_ref_p_1 (gimple_call_arg (call, 0), ref); 1724 1725 /* These read memory pointed to by the first argument. */ 1726 case BUILT_IN_STRDUP: 1727 case BUILT_IN_STRNDUP: 1728 case BUILT_IN_REALLOC: 1729 { 1730 ao_ref dref; 1731 tree size = NULL_TREE; 1732 if (gimple_call_num_args (call) == 2) 1733 size = gimple_call_arg (call, 1); 1734 ao_ref_init_from_ptr_and_size (&dref, 1735 gimple_call_arg (call, 0), 1736 size); 1737 return refs_may_alias_p_1 (&dref, ref, false); 1738 } 1739 /* These read memory pointed to by the first argument. */ 1740 case BUILT_IN_INDEX: 1741 case BUILT_IN_STRCHR: 1742 case BUILT_IN_STRRCHR: 1743 { 1744 ao_ref dref; 1745 ao_ref_init_from_ptr_and_size (&dref, 1746 gimple_call_arg (call, 0), 1747 NULL_TREE); 1748 return refs_may_alias_p_1 (&dref, ref, false); 1749 } 1750 /* These read memory pointed to by the first argument with size 1751 in the third argument. */ 1752 case BUILT_IN_MEMCHR: 1753 { 1754 ao_ref dref; 1755 ao_ref_init_from_ptr_and_size (&dref, 1756 gimple_call_arg (call, 0), 1757 gimple_call_arg (call, 2)); 1758 return refs_may_alias_p_1 (&dref, ref, false); 1759 } 1760 /* These read memory pointed to by the first and second arguments. */ 1761 case BUILT_IN_STRSTR: 1762 case BUILT_IN_STRPBRK: 1763 { 1764 ao_ref dref; 1765 ao_ref_init_from_ptr_and_size (&dref, 1766 gimple_call_arg (call, 0), 1767 NULL_TREE); 1768 if (refs_may_alias_p_1 (&dref, ref, false)) 1769 return true; 1770 ao_ref_init_from_ptr_and_size (&dref, 1771 gimple_call_arg (call, 1), 1772 NULL_TREE); 1773 return refs_may_alias_p_1 (&dref, ref, false); 1774 } 1775 1776 /* The following builtins do not read from memory. */ 1777 case BUILT_IN_FREE: 1778 case BUILT_IN_MALLOC: 1779 case BUILT_IN_POSIX_MEMALIGN: 1780 case BUILT_IN_ALIGNED_ALLOC: 1781 case BUILT_IN_CALLOC: 1782 case BUILT_IN_ALLOCA: 1783 case BUILT_IN_ALLOCA_WITH_ALIGN: 1784 case BUILT_IN_STACK_SAVE: 1785 case BUILT_IN_STACK_RESTORE: 1786 case BUILT_IN_MEMSET: 1787 case BUILT_IN_TM_MEMSET: 1788 case BUILT_IN_MEMSET_CHK: 1789 case BUILT_IN_FREXP: 1790 case BUILT_IN_FREXPF: 1791 case BUILT_IN_FREXPL: 1792 case BUILT_IN_GAMMA_R: 1793 case BUILT_IN_GAMMAF_R: 1794 case BUILT_IN_GAMMAL_R: 1795 case BUILT_IN_LGAMMA_R: 1796 case BUILT_IN_LGAMMAF_R: 1797 case BUILT_IN_LGAMMAL_R: 1798 case BUILT_IN_MODF: 1799 case BUILT_IN_MODFF: 1800 case BUILT_IN_MODFL: 1801 case BUILT_IN_REMQUO: 1802 case BUILT_IN_REMQUOF: 1803 case BUILT_IN_REMQUOL: 1804 case BUILT_IN_SINCOS: 1805 case BUILT_IN_SINCOSF: 1806 case BUILT_IN_SINCOSL: 1807 case BUILT_IN_ASSUME_ALIGNED: 1808 case BUILT_IN_VA_END: 1809 return false; 1810 /* __sync_* builtins and some OpenMP builtins act as threading 1811 barriers. */ 1812 #undef DEF_SYNC_BUILTIN 1813 #define DEF_SYNC_BUILTIN(ENUM, NAME, TYPE, ATTRS) case ENUM: 1814 #include "sync-builtins.def" 1815 #undef DEF_SYNC_BUILTIN 1816 case BUILT_IN_GOMP_ATOMIC_START: 1817 case BUILT_IN_GOMP_ATOMIC_END: 1818 case BUILT_IN_GOMP_BARRIER: 1819 case BUILT_IN_GOMP_BARRIER_CANCEL: 1820 case BUILT_IN_GOMP_TASKWAIT: 1821 case BUILT_IN_GOMP_TASKGROUP_END: 1822 case BUILT_IN_GOMP_CRITICAL_START: 1823 case BUILT_IN_GOMP_CRITICAL_END: 1824 case BUILT_IN_GOMP_CRITICAL_NAME_START: 1825 case BUILT_IN_GOMP_CRITICAL_NAME_END: 1826 case BUILT_IN_GOMP_LOOP_END: 1827 case BUILT_IN_GOMP_LOOP_END_CANCEL: 1828 case BUILT_IN_GOMP_ORDERED_START: 1829 case BUILT_IN_GOMP_ORDERED_END: 1830 case BUILT_IN_GOMP_SECTIONS_END: 1831 case BUILT_IN_GOMP_SECTIONS_END_CANCEL: 1832 case BUILT_IN_GOMP_SINGLE_COPY_START: 1833 case BUILT_IN_GOMP_SINGLE_COPY_END: 1834 return true; 1835 1836 default: 1837 /* Fallthru to general call handling. */; 1838 } 1839 1840 /* Check if base is a global static variable that is not read 1841 by the function. */ 1842 if (callee != NULL_TREE && VAR_P (base) && TREE_STATIC (base)) 1843 { 1844 struct cgraph_node *node = cgraph_node::get (callee); 1845 bitmap not_read; 1846 1847 /* FIXME: Callee can be an OMP builtin that does not have a call graph 1848 node yet. We should enforce that there are nodes for all decls in the 1849 IL and remove this check instead. */ 1850 if (node 1851 && (not_read = ipa_reference_get_not_read_global (node)) 1852 && bitmap_bit_p (not_read, ipa_reference_var_uid (base))) 1853 goto process_args; 1854 } 1855 1856 /* Check if the base variable is call-used. */ 1857 if (DECL_P (base)) 1858 { 1859 if (pt_solution_includes (gimple_call_use_set (call), base)) 1860 return true; 1861 } 1862 else if ((TREE_CODE (base) == MEM_REF 1863 || TREE_CODE (base) == TARGET_MEM_REF) 1864 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME) 1865 { 1866 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0)); 1867 if (!pi) 1868 return true; 1869 1870 if (pt_solutions_intersect (gimple_call_use_set (call), &pi->pt)) 1871 return true; 1872 } 1873 else 1874 return true; 1875 1876 /* Inspect call arguments for passed-by-value aliases. */ 1877 process_args: 1878 for (i = 0; i < gimple_call_num_args (call); ++i) 1879 { 1880 tree op = gimple_call_arg (call, i); 1881 int flags = gimple_call_arg_flags (call, i); 1882 1883 if (flags & EAF_UNUSED) 1884 continue; 1885 1886 if (TREE_CODE (op) == WITH_SIZE_EXPR) 1887 op = TREE_OPERAND (op, 0); 1888 1889 if (TREE_CODE (op) != SSA_NAME 1890 && !is_gimple_min_invariant (op)) 1891 { 1892 ao_ref r; 1893 ao_ref_init (&r, op); 1894 if (refs_may_alias_p_1 (&r, ref, true)) 1895 return true; 1896 } 1897 } 1898 1899 return false; 1900 } 1901 1902 static bool 1903 ref_maybe_used_by_call_p (gcall *call, ao_ref *ref) 1904 { 1905 bool res; 1906 res = ref_maybe_used_by_call_p_1 (call, ref); 1907 if (res) 1908 ++alias_stats.ref_maybe_used_by_call_p_may_alias; 1909 else 1910 ++alias_stats.ref_maybe_used_by_call_p_no_alias; 1911 return res; 1912 } 1913 1914 1915 /* If the statement STMT may use the memory reference REF return 1916 true, otherwise return false. */ 1917 1918 bool 1919 ref_maybe_used_by_stmt_p (gimple *stmt, ao_ref *ref) 1920 { 1921 if (is_gimple_assign (stmt)) 1922 { 1923 tree rhs; 1924 1925 /* All memory assign statements are single. */ 1926 if (!gimple_assign_single_p (stmt)) 1927 return false; 1928 1929 rhs = gimple_assign_rhs1 (stmt); 1930 if (is_gimple_reg (rhs) 1931 || is_gimple_min_invariant (rhs) 1932 || gimple_assign_rhs_code (stmt) == CONSTRUCTOR) 1933 return false; 1934 1935 return refs_may_alias_p (rhs, ref); 1936 } 1937 else if (is_gimple_call (stmt)) 1938 return ref_maybe_used_by_call_p (as_a <gcall *> (stmt), ref); 1939 else if (greturn *return_stmt = dyn_cast <greturn *> (stmt)) 1940 { 1941 tree retval = gimple_return_retval (return_stmt); 1942 if (retval 1943 && TREE_CODE (retval) != SSA_NAME 1944 && !is_gimple_min_invariant (retval) 1945 && refs_may_alias_p (retval, ref)) 1946 return true; 1947 /* If ref escapes the function then the return acts as a use. */ 1948 tree base = ao_ref_base (ref); 1949 if (!base) 1950 ; 1951 else if (DECL_P (base)) 1952 return is_global_var (base); 1953 else if (TREE_CODE (base) == MEM_REF 1954 || TREE_CODE (base) == TARGET_MEM_REF) 1955 return ptr_deref_may_alias_global_p (TREE_OPERAND (base, 0)); 1956 return false; 1957 } 1958 1959 return true; 1960 } 1961 1962 bool 1963 ref_maybe_used_by_stmt_p (gimple *stmt, tree ref) 1964 { 1965 ao_ref r; 1966 ao_ref_init (&r, ref); 1967 return ref_maybe_used_by_stmt_p (stmt, &r); 1968 } 1969 1970 /* If the call in statement CALL may clobber the memory reference REF 1971 return true, otherwise return false. */ 1972 1973 bool 1974 call_may_clobber_ref_p_1 (gcall *call, ao_ref *ref) 1975 { 1976 tree base; 1977 tree callee; 1978 1979 /* If the call is pure or const it cannot clobber anything. */ 1980 if (gimple_call_flags (call) 1981 & (ECF_PURE|ECF_CONST|ECF_LOOPING_CONST_OR_PURE|ECF_NOVOPS)) 1982 return false; 1983 if (gimple_call_internal_p (call)) 1984 switch (gimple_call_internal_fn (call)) 1985 { 1986 /* Treat these internal calls like ECF_PURE for aliasing, 1987 they don't write to any memory the program should care about. 1988 They have important other side-effects, and read memory, 1989 so can't be ECF_NOVOPS. */ 1990 case IFN_UBSAN_NULL: 1991 case IFN_UBSAN_BOUNDS: 1992 case IFN_UBSAN_VPTR: 1993 case IFN_UBSAN_OBJECT_SIZE: 1994 case IFN_ASAN_CHECK: 1995 return false; 1996 default: 1997 break; 1998 } 1999 2000 base = ao_ref_base (ref); 2001 if (!base) 2002 return true; 2003 2004 if (TREE_CODE (base) == SSA_NAME 2005 || CONSTANT_CLASS_P (base)) 2006 return false; 2007 2008 /* A call that is not without side-effects might involve volatile 2009 accesses and thus conflicts with all other volatile accesses. */ 2010 if (ref->volatile_p) 2011 return true; 2012 2013 /* If the reference is based on a decl that is not aliased the call 2014 cannot possibly clobber it. */ 2015 if (DECL_P (base) 2016 && !may_be_aliased (base) 2017 /* But local non-readonly statics can be modified through recursion 2018 or the call may implement a threading barrier which we must 2019 treat as may-def. */ 2020 && (TREE_READONLY (base) 2021 || !is_global_var (base))) 2022 return false; 2023 2024 callee = gimple_call_fndecl (call); 2025 2026 /* Handle those builtin functions explicitly that do not act as 2027 escape points. See tree-ssa-structalias.c:find_func_aliases 2028 for the list of builtins we might need to handle here. */ 2029 if (callee != NULL_TREE 2030 && gimple_call_builtin_p (call, BUILT_IN_NORMAL)) 2031 switch (DECL_FUNCTION_CODE (callee)) 2032 { 2033 /* All the following functions clobber memory pointed to by 2034 their first argument. */ 2035 case BUILT_IN_STRCPY: 2036 case BUILT_IN_STRNCPY: 2037 case BUILT_IN_MEMCPY: 2038 case BUILT_IN_MEMMOVE: 2039 case BUILT_IN_MEMPCPY: 2040 case BUILT_IN_STPCPY: 2041 case BUILT_IN_STPNCPY: 2042 case BUILT_IN_STRCAT: 2043 case BUILT_IN_STRNCAT: 2044 case BUILT_IN_MEMSET: 2045 case BUILT_IN_TM_MEMSET: 2046 CASE_BUILT_IN_TM_STORE (1): 2047 CASE_BUILT_IN_TM_STORE (2): 2048 CASE_BUILT_IN_TM_STORE (4): 2049 CASE_BUILT_IN_TM_STORE (8): 2050 CASE_BUILT_IN_TM_STORE (FLOAT): 2051 CASE_BUILT_IN_TM_STORE (DOUBLE): 2052 CASE_BUILT_IN_TM_STORE (LDOUBLE): 2053 CASE_BUILT_IN_TM_STORE (M64): 2054 CASE_BUILT_IN_TM_STORE (M128): 2055 CASE_BUILT_IN_TM_STORE (M256): 2056 case BUILT_IN_TM_MEMCPY: 2057 case BUILT_IN_TM_MEMMOVE: 2058 { 2059 ao_ref dref; 2060 tree size = NULL_TREE; 2061 /* Don't pass in size for strncat, as the maximum size 2062 is strlen (dest) + n + 1 instead of n, resp. 2063 n + 1 at dest + strlen (dest), but strlen (dest) isn't 2064 known. */ 2065 if (gimple_call_num_args (call) == 3 2066 && DECL_FUNCTION_CODE (callee) != BUILT_IN_STRNCAT) 2067 size = gimple_call_arg (call, 2); 2068 ao_ref_init_from_ptr_and_size (&dref, 2069 gimple_call_arg (call, 0), 2070 size); 2071 return refs_may_alias_p_1 (&dref, ref, false); 2072 } 2073 case BUILT_IN_STRCPY_CHK: 2074 case BUILT_IN_STRNCPY_CHK: 2075 case BUILT_IN_MEMCPY_CHK: 2076 case BUILT_IN_MEMMOVE_CHK: 2077 case BUILT_IN_MEMPCPY_CHK: 2078 case BUILT_IN_STPCPY_CHK: 2079 case BUILT_IN_STPNCPY_CHK: 2080 case BUILT_IN_STRCAT_CHK: 2081 case BUILT_IN_STRNCAT_CHK: 2082 case BUILT_IN_MEMSET_CHK: 2083 { 2084 ao_ref dref; 2085 tree size = NULL_TREE; 2086 /* Don't pass in size for __strncat_chk, as the maximum size 2087 is strlen (dest) + n + 1 instead of n, resp. 2088 n + 1 at dest + strlen (dest), but strlen (dest) isn't 2089 known. */ 2090 if (gimple_call_num_args (call) == 4 2091 && DECL_FUNCTION_CODE (callee) != BUILT_IN_STRNCAT_CHK) 2092 size = gimple_call_arg (call, 2); 2093 ao_ref_init_from_ptr_and_size (&dref, 2094 gimple_call_arg (call, 0), 2095 size); 2096 return refs_may_alias_p_1 (&dref, ref, false); 2097 } 2098 case BUILT_IN_BCOPY: 2099 { 2100 ao_ref dref; 2101 tree size = gimple_call_arg (call, 2); 2102 ao_ref_init_from_ptr_and_size (&dref, 2103 gimple_call_arg (call, 1), 2104 size); 2105 return refs_may_alias_p_1 (&dref, ref, false); 2106 } 2107 /* Allocating memory does not have any side-effects apart from 2108 being the definition point for the pointer. */ 2109 case BUILT_IN_MALLOC: 2110 case BUILT_IN_ALIGNED_ALLOC: 2111 case BUILT_IN_CALLOC: 2112 case BUILT_IN_STRDUP: 2113 case BUILT_IN_STRNDUP: 2114 /* Unix98 specifies that errno is set on allocation failure. */ 2115 if (flag_errno_math 2116 && targetm.ref_may_alias_errno (ref)) 2117 return true; 2118 return false; 2119 case BUILT_IN_STACK_SAVE: 2120 case BUILT_IN_ALLOCA: 2121 case BUILT_IN_ALLOCA_WITH_ALIGN: 2122 case BUILT_IN_ASSUME_ALIGNED: 2123 return false; 2124 /* But posix_memalign stores a pointer into the memory pointed to 2125 by its first argument. */ 2126 case BUILT_IN_POSIX_MEMALIGN: 2127 { 2128 tree ptrptr = gimple_call_arg (call, 0); 2129 ao_ref dref; 2130 ao_ref_init_from_ptr_and_size (&dref, ptrptr, 2131 TYPE_SIZE_UNIT (ptr_type_node)); 2132 return (refs_may_alias_p_1 (&dref, ref, false) 2133 || (flag_errno_math 2134 && targetm.ref_may_alias_errno (ref))); 2135 } 2136 /* Freeing memory kills the pointed-to memory. More importantly 2137 the call has to serve as a barrier for moving loads and stores 2138 across it. */ 2139 case BUILT_IN_FREE: 2140 case BUILT_IN_VA_END: 2141 { 2142 tree ptr = gimple_call_arg (call, 0); 2143 return ptr_deref_may_alias_ref_p_1 (ptr, ref); 2144 } 2145 /* Realloc serves both as allocation point and deallocation point. */ 2146 case BUILT_IN_REALLOC: 2147 { 2148 tree ptr = gimple_call_arg (call, 0); 2149 /* Unix98 specifies that errno is set on allocation failure. */ 2150 return ((flag_errno_math 2151 && targetm.ref_may_alias_errno (ref)) 2152 || ptr_deref_may_alias_ref_p_1 (ptr, ref)); 2153 } 2154 case BUILT_IN_GAMMA_R: 2155 case BUILT_IN_GAMMAF_R: 2156 case BUILT_IN_GAMMAL_R: 2157 case BUILT_IN_LGAMMA_R: 2158 case BUILT_IN_LGAMMAF_R: 2159 case BUILT_IN_LGAMMAL_R: 2160 { 2161 tree out = gimple_call_arg (call, 1); 2162 if (ptr_deref_may_alias_ref_p_1 (out, ref)) 2163 return true; 2164 if (flag_errno_math) 2165 break; 2166 return false; 2167 } 2168 case BUILT_IN_FREXP: 2169 case BUILT_IN_FREXPF: 2170 case BUILT_IN_FREXPL: 2171 case BUILT_IN_MODF: 2172 case BUILT_IN_MODFF: 2173 case BUILT_IN_MODFL: 2174 { 2175 tree out = gimple_call_arg (call, 1); 2176 return ptr_deref_may_alias_ref_p_1 (out, ref); 2177 } 2178 case BUILT_IN_REMQUO: 2179 case BUILT_IN_REMQUOF: 2180 case BUILT_IN_REMQUOL: 2181 { 2182 tree out = gimple_call_arg (call, 2); 2183 if (ptr_deref_may_alias_ref_p_1 (out, ref)) 2184 return true; 2185 if (flag_errno_math) 2186 break; 2187 return false; 2188 } 2189 case BUILT_IN_SINCOS: 2190 case BUILT_IN_SINCOSF: 2191 case BUILT_IN_SINCOSL: 2192 { 2193 tree sin = gimple_call_arg (call, 1); 2194 tree cos = gimple_call_arg (call, 2); 2195 return (ptr_deref_may_alias_ref_p_1 (sin, ref) 2196 || ptr_deref_may_alias_ref_p_1 (cos, ref)); 2197 } 2198 /* __sync_* builtins and some OpenMP builtins act as threading 2199 barriers. */ 2200 #undef DEF_SYNC_BUILTIN 2201 #define DEF_SYNC_BUILTIN(ENUM, NAME, TYPE, ATTRS) case ENUM: 2202 #include "sync-builtins.def" 2203 #undef DEF_SYNC_BUILTIN 2204 case BUILT_IN_GOMP_ATOMIC_START: 2205 case BUILT_IN_GOMP_ATOMIC_END: 2206 case BUILT_IN_GOMP_BARRIER: 2207 case BUILT_IN_GOMP_BARRIER_CANCEL: 2208 case BUILT_IN_GOMP_TASKWAIT: 2209 case BUILT_IN_GOMP_TASKGROUP_END: 2210 case BUILT_IN_GOMP_CRITICAL_START: 2211 case BUILT_IN_GOMP_CRITICAL_END: 2212 case BUILT_IN_GOMP_CRITICAL_NAME_START: 2213 case BUILT_IN_GOMP_CRITICAL_NAME_END: 2214 case BUILT_IN_GOMP_LOOP_END: 2215 case BUILT_IN_GOMP_LOOP_END_CANCEL: 2216 case BUILT_IN_GOMP_ORDERED_START: 2217 case BUILT_IN_GOMP_ORDERED_END: 2218 case BUILT_IN_GOMP_SECTIONS_END: 2219 case BUILT_IN_GOMP_SECTIONS_END_CANCEL: 2220 case BUILT_IN_GOMP_SINGLE_COPY_START: 2221 case BUILT_IN_GOMP_SINGLE_COPY_END: 2222 return true; 2223 default: 2224 /* Fallthru to general call handling. */; 2225 } 2226 2227 /* Check if base is a global static variable that is not written 2228 by the function. */ 2229 if (callee != NULL_TREE && VAR_P (base) && TREE_STATIC (base)) 2230 { 2231 struct cgraph_node *node = cgraph_node::get (callee); 2232 bitmap not_written; 2233 2234 if (node 2235 && (not_written = ipa_reference_get_not_written_global (node)) 2236 && bitmap_bit_p (not_written, ipa_reference_var_uid (base))) 2237 return false; 2238 } 2239 2240 /* Check if the base variable is call-clobbered. */ 2241 if (DECL_P (base)) 2242 return pt_solution_includes (gimple_call_clobber_set (call), base); 2243 else if ((TREE_CODE (base) == MEM_REF 2244 || TREE_CODE (base) == TARGET_MEM_REF) 2245 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME) 2246 { 2247 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0)); 2248 if (!pi) 2249 return true; 2250 2251 return pt_solutions_intersect (gimple_call_clobber_set (call), &pi->pt); 2252 } 2253 2254 return true; 2255 } 2256 2257 /* If the call in statement CALL may clobber the memory reference REF 2258 return true, otherwise return false. */ 2259 2260 bool 2261 call_may_clobber_ref_p (gcall *call, tree ref) 2262 { 2263 bool res; 2264 ao_ref r; 2265 ao_ref_init (&r, ref); 2266 res = call_may_clobber_ref_p_1 (call, &r); 2267 if (res) 2268 ++alias_stats.call_may_clobber_ref_p_may_alias; 2269 else 2270 ++alias_stats.call_may_clobber_ref_p_no_alias; 2271 return res; 2272 } 2273 2274 2275 /* If the statement STMT may clobber the memory reference REF return true, 2276 otherwise return false. */ 2277 2278 bool 2279 stmt_may_clobber_ref_p_1 (gimple *stmt, ao_ref *ref) 2280 { 2281 if (is_gimple_call (stmt)) 2282 { 2283 tree lhs = gimple_call_lhs (stmt); 2284 if (lhs 2285 && TREE_CODE (lhs) != SSA_NAME) 2286 { 2287 ao_ref r; 2288 ao_ref_init (&r, lhs); 2289 if (refs_may_alias_p_1 (ref, &r, true)) 2290 return true; 2291 } 2292 2293 return call_may_clobber_ref_p_1 (as_a <gcall *> (stmt), ref); 2294 } 2295 else if (gimple_assign_single_p (stmt)) 2296 { 2297 tree lhs = gimple_assign_lhs (stmt); 2298 if (TREE_CODE (lhs) != SSA_NAME) 2299 { 2300 ao_ref r; 2301 ao_ref_init (&r, lhs); 2302 return refs_may_alias_p_1 (ref, &r, true); 2303 } 2304 } 2305 else if (gimple_code (stmt) == GIMPLE_ASM) 2306 return true; 2307 2308 return false; 2309 } 2310 2311 bool 2312 stmt_may_clobber_ref_p (gimple *stmt, tree ref) 2313 { 2314 ao_ref r; 2315 ao_ref_init (&r, ref); 2316 return stmt_may_clobber_ref_p_1 (stmt, &r); 2317 } 2318 2319 /* Return true if store1 and store2 described by corresponding tuples 2320 <BASE, OFFSET, SIZE, MAX_SIZE> have the same size and store to the same 2321 address. */ 2322 2323 static bool 2324 same_addr_size_stores_p (tree base1, HOST_WIDE_INT offset1, HOST_WIDE_INT size1, 2325 HOST_WIDE_INT max_size1, 2326 tree base2, HOST_WIDE_INT offset2, HOST_WIDE_INT size2, 2327 HOST_WIDE_INT max_size2) 2328 { 2329 /* Offsets need to be 0. */ 2330 if (offset1 != 0 2331 || offset2 != 0) 2332 return false; 2333 2334 bool base1_obj_p = SSA_VAR_P (base1); 2335 bool base2_obj_p = SSA_VAR_P (base2); 2336 2337 /* We need one object. */ 2338 if (base1_obj_p == base2_obj_p) 2339 return false; 2340 tree obj = base1_obj_p ? base1 : base2; 2341 2342 /* And we need one MEM_REF. */ 2343 bool base1_memref_p = TREE_CODE (base1) == MEM_REF; 2344 bool base2_memref_p = TREE_CODE (base2) == MEM_REF; 2345 if (base1_memref_p == base2_memref_p) 2346 return false; 2347 tree memref = base1_memref_p ? base1 : base2; 2348 2349 /* Sizes need to be valid. */ 2350 if (max_size1 == -1 || max_size2 == -1 2351 || size1 == -1 || size2 == -1) 2352 return false; 2353 2354 /* Max_size needs to match size. */ 2355 if (max_size1 != size1 2356 || max_size2 != size2) 2357 return false; 2358 2359 /* Sizes need to match. */ 2360 if (size1 != size2) 2361 return false; 2362 2363 2364 /* Check that memref is a store to pointer with singleton points-to info. */ 2365 if (!integer_zerop (TREE_OPERAND (memref, 1))) 2366 return false; 2367 tree ptr = TREE_OPERAND (memref, 0); 2368 if (TREE_CODE (ptr) != SSA_NAME) 2369 return false; 2370 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr); 2371 unsigned int pt_uid; 2372 if (pi == NULL 2373 || !pt_solution_singleton_or_null_p (&pi->pt, &pt_uid)) 2374 return false; 2375 2376 /* Be conservative with non-call exceptions when the address might 2377 be NULL. */ 2378 if (flag_non_call_exceptions && pi->pt.null) 2379 return false; 2380 2381 /* Check that ptr points relative to obj. */ 2382 unsigned int obj_uid = DECL_PT_UID (obj); 2383 if (obj_uid != pt_uid) 2384 return false; 2385 2386 /* Check that the object size is the same as the store size. That ensures us 2387 that ptr points to the start of obj. */ 2388 if (!tree_fits_shwi_p (DECL_SIZE (obj))) 2389 return false; 2390 HOST_WIDE_INT obj_size = tree_to_shwi (DECL_SIZE (obj)); 2391 return obj_size == size1; 2392 } 2393 2394 /* If STMT kills the memory reference REF return true, otherwise 2395 return false. */ 2396 2397 bool 2398 stmt_kills_ref_p (gimple *stmt, ao_ref *ref) 2399 { 2400 if (!ao_ref_base (ref)) 2401 return false; 2402 2403 if (gimple_has_lhs (stmt) 2404 && TREE_CODE (gimple_get_lhs (stmt)) != SSA_NAME 2405 /* The assignment is not necessarily carried out if it can throw 2406 and we can catch it in the current function where we could inspect 2407 the previous value. 2408 ??? We only need to care about the RHS throwing. For aggregate 2409 assignments or similar calls and non-call exceptions the LHS 2410 might throw as well. */ 2411 && !stmt_can_throw_internal (stmt)) 2412 { 2413 tree lhs = gimple_get_lhs (stmt); 2414 /* If LHS is literally a base of the access we are done. */ 2415 if (ref->ref) 2416 { 2417 tree base = ref->ref; 2418 tree innermost_dropped_array_ref = NULL_TREE; 2419 if (handled_component_p (base)) 2420 { 2421 tree saved_lhs0 = NULL_TREE; 2422 if (handled_component_p (lhs)) 2423 { 2424 saved_lhs0 = TREE_OPERAND (lhs, 0); 2425 TREE_OPERAND (lhs, 0) = integer_zero_node; 2426 } 2427 do 2428 { 2429 /* Just compare the outermost handled component, if 2430 they are equal we have found a possible common 2431 base. */ 2432 tree saved_base0 = TREE_OPERAND (base, 0); 2433 TREE_OPERAND (base, 0) = integer_zero_node; 2434 bool res = operand_equal_p (lhs, base, 0); 2435 TREE_OPERAND (base, 0) = saved_base0; 2436 if (res) 2437 break; 2438 /* Remember if we drop an array-ref that we need to 2439 double-check not being at struct end. */ 2440 if (TREE_CODE (base) == ARRAY_REF 2441 || TREE_CODE (base) == ARRAY_RANGE_REF) 2442 innermost_dropped_array_ref = base; 2443 /* Otherwise drop handled components of the access. */ 2444 base = saved_base0; 2445 } 2446 while (handled_component_p (base)); 2447 if (saved_lhs0) 2448 TREE_OPERAND (lhs, 0) = saved_lhs0; 2449 } 2450 /* Finally check if the lhs has the same address and size as the 2451 base candidate of the access. Watch out if we have dropped 2452 an array-ref that was at struct end, this means ref->ref may 2453 be outside of the TYPE_SIZE of its base. */ 2454 if ((! innermost_dropped_array_ref 2455 || ! array_at_struct_end_p (innermost_dropped_array_ref)) 2456 && (lhs == base 2457 || (((TYPE_SIZE (TREE_TYPE (lhs)) 2458 == TYPE_SIZE (TREE_TYPE (base))) 2459 || (TYPE_SIZE (TREE_TYPE (lhs)) 2460 && TYPE_SIZE (TREE_TYPE (base)) 2461 && operand_equal_p (TYPE_SIZE (TREE_TYPE (lhs)), 2462 TYPE_SIZE (TREE_TYPE (base)), 2463 0))) 2464 && operand_equal_p (lhs, base, 2465 OEP_ADDRESS_OF 2466 | OEP_MATCH_SIDE_EFFECTS)))) 2467 return true; 2468 } 2469 2470 /* Now look for non-literal equal bases with the restriction of 2471 handling constant offset and size. */ 2472 /* For a must-alias check we need to be able to constrain 2473 the access properly. */ 2474 if (ref->max_size == -1) 2475 return false; 2476 HOST_WIDE_INT size, offset, max_size, ref_offset = ref->offset; 2477 bool reverse; 2478 tree base 2479 = get_ref_base_and_extent (lhs, &offset, &size, &max_size, &reverse); 2480 /* We can get MEM[symbol: sZ, index: D.8862_1] here, 2481 so base == ref->base does not always hold. */ 2482 if (base != ref->base) 2483 { 2484 /* Try using points-to info. */ 2485 if (same_addr_size_stores_p (base, offset, size, max_size, ref->base, 2486 ref->offset, ref->size, ref->max_size)) 2487 return true; 2488 2489 /* If both base and ref->base are MEM_REFs, only compare the 2490 first operand, and if the second operand isn't equal constant, 2491 try to add the offsets into offset and ref_offset. */ 2492 if (TREE_CODE (base) == MEM_REF && TREE_CODE (ref->base) == MEM_REF 2493 && TREE_OPERAND (base, 0) == TREE_OPERAND (ref->base, 0)) 2494 { 2495 if (!tree_int_cst_equal (TREE_OPERAND (base, 1), 2496 TREE_OPERAND (ref->base, 1))) 2497 { 2498 offset_int off1 = mem_ref_offset (base); 2499 off1 <<= LOG2_BITS_PER_UNIT; 2500 off1 += offset; 2501 offset_int off2 = mem_ref_offset (ref->base); 2502 off2 <<= LOG2_BITS_PER_UNIT; 2503 off2 += ref_offset; 2504 if (wi::fits_shwi_p (off1) && wi::fits_shwi_p (off2)) 2505 { 2506 offset = off1.to_shwi (); 2507 ref_offset = off2.to_shwi (); 2508 } 2509 else 2510 size = -1; 2511 } 2512 } 2513 else 2514 size = -1; 2515 } 2516 /* For a must-alias check we need to be able to constrain 2517 the access properly. */ 2518 if (size != -1 && size == max_size) 2519 { 2520 if (offset <= ref_offset 2521 && offset + size >= ref_offset + ref->max_size) 2522 return true; 2523 } 2524 } 2525 2526 if (is_gimple_call (stmt)) 2527 { 2528 tree callee = gimple_call_fndecl (stmt); 2529 if (callee != NULL_TREE 2530 && gimple_call_builtin_p (stmt, BUILT_IN_NORMAL)) 2531 switch (DECL_FUNCTION_CODE (callee)) 2532 { 2533 case BUILT_IN_FREE: 2534 { 2535 tree ptr = gimple_call_arg (stmt, 0); 2536 tree base = ao_ref_base (ref); 2537 if (base && TREE_CODE (base) == MEM_REF 2538 && TREE_OPERAND (base, 0) == ptr) 2539 return true; 2540 break; 2541 } 2542 2543 case BUILT_IN_MEMCPY: 2544 case BUILT_IN_MEMPCPY: 2545 case BUILT_IN_MEMMOVE: 2546 case BUILT_IN_MEMSET: 2547 case BUILT_IN_MEMCPY_CHK: 2548 case BUILT_IN_MEMPCPY_CHK: 2549 case BUILT_IN_MEMMOVE_CHK: 2550 case BUILT_IN_MEMSET_CHK: 2551 { 2552 /* For a must-alias check we need to be able to constrain 2553 the access properly. */ 2554 if (ref->max_size == -1) 2555 return false; 2556 tree dest = gimple_call_arg (stmt, 0); 2557 tree len = gimple_call_arg (stmt, 2); 2558 if (!tree_fits_shwi_p (len)) 2559 return false; 2560 tree rbase = ref->base; 2561 offset_int roffset = ref->offset; 2562 ao_ref dref; 2563 ao_ref_init_from_ptr_and_size (&dref, dest, len); 2564 tree base = ao_ref_base (&dref); 2565 offset_int offset = dref.offset; 2566 if (!base || dref.size == -1) 2567 return false; 2568 if (TREE_CODE (base) == MEM_REF) 2569 { 2570 if (TREE_CODE (rbase) != MEM_REF) 2571 return false; 2572 // Compare pointers. 2573 offset += mem_ref_offset (base) << LOG2_BITS_PER_UNIT; 2574 roffset += mem_ref_offset (rbase) << LOG2_BITS_PER_UNIT; 2575 base = TREE_OPERAND (base, 0); 2576 rbase = TREE_OPERAND (rbase, 0); 2577 } 2578 if (base == rbase 2579 && offset <= roffset 2580 && (roffset + ref->max_size 2581 <= offset + (wi::to_offset (len) << LOG2_BITS_PER_UNIT))) 2582 return true; 2583 break; 2584 } 2585 2586 case BUILT_IN_VA_END: 2587 { 2588 tree ptr = gimple_call_arg (stmt, 0); 2589 if (TREE_CODE (ptr) == ADDR_EXPR) 2590 { 2591 tree base = ao_ref_base (ref); 2592 if (TREE_OPERAND (ptr, 0) == base) 2593 return true; 2594 } 2595 break; 2596 } 2597 2598 default:; 2599 } 2600 } 2601 return false; 2602 } 2603 2604 bool 2605 stmt_kills_ref_p (gimple *stmt, tree ref) 2606 { 2607 ao_ref r; 2608 ao_ref_init (&r, ref); 2609 return stmt_kills_ref_p (stmt, &r); 2610 } 2611 2612 2613 /* Walk the virtual use-def chain of VUSE until hitting the virtual operand 2614 TARGET or a statement clobbering the memory reference REF in which 2615 case false is returned. The walk starts with VUSE, one argument of PHI. */ 2616 2617 static bool 2618 maybe_skip_until (gimple *phi, tree target, ao_ref *ref, 2619 tree vuse, unsigned int *cnt, bitmap *visited, 2620 bool abort_on_visited, 2621 void *(*translate)(ao_ref *, tree, void *, bool *), 2622 void *data) 2623 { 2624 basic_block bb = gimple_bb (phi); 2625 2626 if (!*visited) 2627 *visited = BITMAP_ALLOC (NULL); 2628 2629 bitmap_set_bit (*visited, SSA_NAME_VERSION (PHI_RESULT (phi))); 2630 2631 /* Walk until we hit the target. */ 2632 while (vuse != target) 2633 { 2634 gimple *def_stmt = SSA_NAME_DEF_STMT (vuse); 2635 /* Recurse for PHI nodes. */ 2636 if (gimple_code (def_stmt) == GIMPLE_PHI) 2637 { 2638 /* An already visited PHI node ends the walk successfully. */ 2639 if (bitmap_bit_p (*visited, SSA_NAME_VERSION (PHI_RESULT (def_stmt)))) 2640 return !abort_on_visited; 2641 vuse = get_continuation_for_phi (def_stmt, ref, cnt, 2642 visited, abort_on_visited, 2643 translate, data); 2644 if (!vuse) 2645 return false; 2646 continue; 2647 } 2648 else if (gimple_nop_p (def_stmt)) 2649 return false; 2650 else 2651 { 2652 /* A clobbering statement or the end of the IL ends it failing. */ 2653 ++*cnt; 2654 if (stmt_may_clobber_ref_p_1 (def_stmt, ref)) 2655 { 2656 bool disambiguate_only = true; 2657 if (translate 2658 && (*translate) (ref, vuse, data, &disambiguate_only) == NULL) 2659 ; 2660 else 2661 return false; 2662 } 2663 } 2664 /* If we reach a new basic-block see if we already skipped it 2665 in a previous walk that ended successfully. */ 2666 if (gimple_bb (def_stmt) != bb) 2667 { 2668 if (!bitmap_set_bit (*visited, SSA_NAME_VERSION (vuse))) 2669 return !abort_on_visited; 2670 bb = gimple_bb (def_stmt); 2671 } 2672 vuse = gimple_vuse (def_stmt); 2673 } 2674 return true; 2675 } 2676 2677 /* For two PHI arguments ARG0 and ARG1 try to skip non-aliasing code 2678 until we hit the phi argument definition that dominates the other one. 2679 Return that, or NULL_TREE if there is no such definition. */ 2680 2681 static tree 2682 get_continuation_for_phi_1 (gimple *phi, tree arg0, tree arg1, 2683 ao_ref *ref, unsigned int *cnt, 2684 bitmap *visited, bool abort_on_visited, 2685 void *(*translate)(ao_ref *, tree, void *, bool *), 2686 void *data) 2687 { 2688 gimple *def0 = SSA_NAME_DEF_STMT (arg0); 2689 gimple *def1 = SSA_NAME_DEF_STMT (arg1); 2690 tree common_vuse; 2691 2692 if (arg0 == arg1) 2693 return arg0; 2694 else if (gimple_nop_p (def0) 2695 || (!gimple_nop_p (def1) 2696 && dominated_by_p (CDI_DOMINATORS, 2697 gimple_bb (def1), gimple_bb (def0)))) 2698 { 2699 if (maybe_skip_until (phi, arg0, ref, arg1, cnt, 2700 visited, abort_on_visited, translate, data)) 2701 return arg0; 2702 } 2703 else if (gimple_nop_p (def1) 2704 || dominated_by_p (CDI_DOMINATORS, 2705 gimple_bb (def0), gimple_bb (def1))) 2706 { 2707 if (maybe_skip_until (phi, arg1, ref, arg0, cnt, 2708 visited, abort_on_visited, translate, data)) 2709 return arg1; 2710 } 2711 /* Special case of a diamond: 2712 MEM_1 = ... 2713 goto (cond) ? L1 : L2 2714 L1: store1 = ... #MEM_2 = vuse(MEM_1) 2715 goto L3 2716 L2: store2 = ... #MEM_3 = vuse(MEM_1) 2717 L3: MEM_4 = PHI<MEM_2, MEM_3> 2718 We were called with the PHI at L3, MEM_2 and MEM_3 don't 2719 dominate each other, but still we can easily skip this PHI node 2720 if we recognize that the vuse MEM operand is the same for both, 2721 and that we can skip both statements (they don't clobber us). 2722 This is still linear. Don't use maybe_skip_until, that might 2723 potentially be slow. */ 2724 else if ((common_vuse = gimple_vuse (def0)) 2725 && common_vuse == gimple_vuse (def1)) 2726 { 2727 bool disambiguate_only = true; 2728 *cnt += 2; 2729 if ((!stmt_may_clobber_ref_p_1 (def0, ref) 2730 || (translate 2731 && (*translate) (ref, arg0, data, &disambiguate_only) == NULL)) 2732 && (!stmt_may_clobber_ref_p_1 (def1, ref) 2733 || (translate 2734 && (*translate) (ref, arg1, data, &disambiguate_only) == NULL))) 2735 return common_vuse; 2736 } 2737 2738 return NULL_TREE; 2739 } 2740 2741 2742 /* Starting from a PHI node for the virtual operand of the memory reference 2743 REF find a continuation virtual operand that allows to continue walking 2744 statements dominating PHI skipping only statements that cannot possibly 2745 clobber REF. Increments *CNT for each alias disambiguation done. 2746 Returns NULL_TREE if no suitable virtual operand can be found. */ 2747 2748 tree 2749 get_continuation_for_phi (gimple *phi, ao_ref *ref, 2750 unsigned int *cnt, bitmap *visited, 2751 bool abort_on_visited, 2752 void *(*translate)(ao_ref *, tree, void *, bool *), 2753 void *data) 2754 { 2755 unsigned nargs = gimple_phi_num_args (phi); 2756 2757 /* Through a single-argument PHI we can simply look through. */ 2758 if (nargs == 1) 2759 return PHI_ARG_DEF (phi, 0); 2760 2761 /* For two or more arguments try to pairwise skip non-aliasing code 2762 until we hit the phi argument definition that dominates the other one. */ 2763 else if (nargs >= 2) 2764 { 2765 tree arg0, arg1; 2766 unsigned i; 2767 2768 /* Find a candidate for the virtual operand which definition 2769 dominates those of all others. */ 2770 arg0 = PHI_ARG_DEF (phi, 0); 2771 if (!SSA_NAME_IS_DEFAULT_DEF (arg0)) 2772 for (i = 1; i < nargs; ++i) 2773 { 2774 arg1 = PHI_ARG_DEF (phi, i); 2775 if (SSA_NAME_IS_DEFAULT_DEF (arg1)) 2776 { 2777 arg0 = arg1; 2778 break; 2779 } 2780 if (dominated_by_p (CDI_DOMINATORS, 2781 gimple_bb (SSA_NAME_DEF_STMT (arg0)), 2782 gimple_bb (SSA_NAME_DEF_STMT (arg1)))) 2783 arg0 = arg1; 2784 } 2785 2786 /* Then pairwise reduce against the found candidate. */ 2787 for (i = 0; i < nargs; ++i) 2788 { 2789 arg1 = PHI_ARG_DEF (phi, i); 2790 arg0 = get_continuation_for_phi_1 (phi, arg0, arg1, ref, 2791 cnt, visited, abort_on_visited, 2792 translate, data); 2793 if (!arg0) 2794 return NULL_TREE; 2795 } 2796 2797 return arg0; 2798 } 2799 2800 return NULL_TREE; 2801 } 2802 2803 /* Based on the memory reference REF and its virtual use VUSE call 2804 WALKER for each virtual use that is equivalent to VUSE, including VUSE 2805 itself. That is, for each virtual use for which its defining statement 2806 does not clobber REF. 2807 2808 WALKER is called with REF, the current virtual use and DATA. If 2809 WALKER returns non-NULL the walk stops and its result is returned. 2810 At the end of a non-successful walk NULL is returned. 2811 2812 TRANSLATE if non-NULL is called with a pointer to REF, the virtual 2813 use which definition is a statement that may clobber REF and DATA. 2814 If TRANSLATE returns (void *)-1 the walk stops and NULL is returned. 2815 If TRANSLATE returns non-NULL the walk stops and its result is returned. 2816 If TRANSLATE returns NULL the walk continues and TRANSLATE is supposed 2817 to adjust REF and *DATA to make that valid. 2818 2819 VALUEIZE if non-NULL is called with the next VUSE that is considered 2820 and return value is substituted for that. This can be used to 2821 implement optimistic value-numbering for example. Note that the 2822 VUSE argument is assumed to be valueized already. 2823 2824 TODO: Cache the vector of equivalent vuses per ref, vuse pair. */ 2825 2826 void * 2827 walk_non_aliased_vuses (ao_ref *ref, tree vuse, 2828 void *(*walker)(ao_ref *, tree, unsigned int, void *), 2829 void *(*translate)(ao_ref *, tree, void *, bool *), 2830 tree (*valueize)(tree), 2831 void *data) 2832 { 2833 bitmap visited = NULL; 2834 void *res; 2835 unsigned int cnt = 0; 2836 bool translated = false; 2837 2838 timevar_push (TV_ALIAS_STMT_WALK); 2839 2840 do 2841 { 2842 gimple *def_stmt; 2843 2844 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */ 2845 res = (*walker) (ref, vuse, cnt, data); 2846 /* Abort walk. */ 2847 if (res == (void *)-1) 2848 { 2849 res = NULL; 2850 break; 2851 } 2852 /* Lookup succeeded. */ 2853 else if (res != NULL) 2854 break; 2855 2856 if (valueize) 2857 vuse = valueize (vuse); 2858 def_stmt = SSA_NAME_DEF_STMT (vuse); 2859 if (gimple_nop_p (def_stmt)) 2860 break; 2861 else if (gimple_code (def_stmt) == GIMPLE_PHI) 2862 vuse = get_continuation_for_phi (def_stmt, ref, &cnt, 2863 &visited, translated, translate, data); 2864 else 2865 { 2866 cnt++; 2867 if (stmt_may_clobber_ref_p_1 (def_stmt, ref)) 2868 { 2869 if (!translate) 2870 break; 2871 bool disambiguate_only = false; 2872 res = (*translate) (ref, vuse, data, &disambiguate_only); 2873 /* Failed lookup and translation. */ 2874 if (res == (void *)-1) 2875 { 2876 res = NULL; 2877 break; 2878 } 2879 /* Lookup succeeded. */ 2880 else if (res != NULL) 2881 break; 2882 /* Translation succeeded, continue walking. */ 2883 translated = translated || !disambiguate_only; 2884 } 2885 vuse = gimple_vuse (def_stmt); 2886 } 2887 } 2888 while (vuse); 2889 2890 if (visited) 2891 BITMAP_FREE (visited); 2892 2893 timevar_pop (TV_ALIAS_STMT_WALK); 2894 2895 return res; 2896 } 2897 2898 2899 /* Based on the memory reference REF call WALKER for each vdef which 2900 defining statement may clobber REF, starting with VDEF. If REF 2901 is NULL_TREE, each defining statement is visited. 2902 2903 WALKER is called with REF, the current vdef and DATA. If WALKER 2904 returns true the walk is stopped, otherwise it continues. 2905 2906 If function entry is reached, FUNCTION_ENTRY_REACHED is set to true. 2907 The pointer may be NULL and then we do not track this information. 2908 2909 At PHI nodes walk_aliased_vdefs forks into one walk for reach 2910 PHI argument (but only one walk continues on merge points), the 2911 return value is true if any of the walks was successful. 2912 2913 The function returns the number of statements walked or -1 if 2914 LIMIT stmts were walked and the walk was aborted at this point. 2915 If LIMIT is zero the walk is not aborted. */ 2916 2917 static int 2918 walk_aliased_vdefs_1 (ao_ref *ref, tree vdef, 2919 bool (*walker)(ao_ref *, tree, void *), void *data, 2920 bitmap *visited, unsigned int cnt, 2921 bool *function_entry_reached, unsigned limit) 2922 { 2923 do 2924 { 2925 gimple *def_stmt = SSA_NAME_DEF_STMT (vdef); 2926 2927 if (*visited 2928 && !bitmap_set_bit (*visited, SSA_NAME_VERSION (vdef))) 2929 return cnt; 2930 2931 if (gimple_nop_p (def_stmt)) 2932 { 2933 if (function_entry_reached) 2934 *function_entry_reached = true; 2935 return cnt; 2936 } 2937 else if (gimple_code (def_stmt) == GIMPLE_PHI) 2938 { 2939 unsigned i; 2940 if (!*visited) 2941 *visited = BITMAP_ALLOC (NULL); 2942 for (i = 0; i < gimple_phi_num_args (def_stmt); ++i) 2943 { 2944 int res = walk_aliased_vdefs_1 (ref, 2945 gimple_phi_arg_def (def_stmt, i), 2946 walker, data, visited, cnt, 2947 function_entry_reached, limit); 2948 if (res == -1) 2949 return -1; 2950 cnt = res; 2951 } 2952 return cnt; 2953 } 2954 2955 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */ 2956 cnt++; 2957 if (cnt == limit) 2958 return -1; 2959 if ((!ref 2960 || stmt_may_clobber_ref_p_1 (def_stmt, ref)) 2961 && (*walker) (ref, vdef, data)) 2962 return cnt; 2963 2964 vdef = gimple_vuse (def_stmt); 2965 } 2966 while (1); 2967 } 2968 2969 int 2970 walk_aliased_vdefs (ao_ref *ref, tree vdef, 2971 bool (*walker)(ao_ref *, tree, void *), void *data, 2972 bitmap *visited, 2973 bool *function_entry_reached, unsigned int limit) 2974 { 2975 bitmap local_visited = NULL; 2976 int ret; 2977 2978 timevar_push (TV_ALIAS_STMT_WALK); 2979 2980 if (function_entry_reached) 2981 *function_entry_reached = false; 2982 2983 ret = walk_aliased_vdefs_1 (ref, vdef, walker, data, 2984 visited ? visited : &local_visited, 0, 2985 function_entry_reached, limit); 2986 if (local_visited) 2987 BITMAP_FREE (local_visited); 2988 2989 timevar_pop (TV_ALIAS_STMT_WALK); 2990 2991 return ret; 2992 } 2993 2994