1 /* Alias analysis for trees. 2 Copyright (C) 2004-2019 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 cannot 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 poly_int64 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 && ptrdiff_tree_p (gimple_assign_rhs2 (stmt), &extra_offset)) 693 { 694 ptr = gimple_assign_rhs1 (stmt); 695 extra_offset *= BITS_PER_UNIT; 696 } 697 } 698 699 if (TREE_CODE (ptr) == ADDR_EXPR) 700 { 701 ref->base = get_addr_base_and_unit_offset (TREE_OPERAND (ptr, 0), &t); 702 if (ref->base) 703 ref->offset = BITS_PER_UNIT * t; 704 else 705 { 706 size = NULL_TREE; 707 ref->offset = 0; 708 ref->base = get_base_address (TREE_OPERAND (ptr, 0)); 709 } 710 } 711 else 712 { 713 gcc_assert (POINTER_TYPE_P (TREE_TYPE (ptr))); 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 && poly_int_tree_p (size, &size_hwi) 721 && coeffs_in_range_p (size_hwi, 0, 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 poly_int64 offset1, poly_int64 max_size1, 783 tree ref2, 784 alias_set_type ref2_alias_set, 785 alias_set_type base2_alias_set, 786 poly_int64 offset2, poly_int64 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 poly_int64 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_maybe_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 poly_int64 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_maybe_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 poly_int64 offset1, poly_int64 max_size1, 1094 tree ref2, tree base2, 1095 poly_int64 offset2, poly_int64 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_maybe_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 poly_int64 offset1, poly_int64 max_size1, 1128 alias_set_type ref1_alias_set, 1129 alias_set_type base1_alias_set, 1130 tree ref2 ATTRIBUTE_UNUSED, tree base2, 1131 poly_int64 offset2, poly_int64 max_size2, 1132 alias_set_type ref2_alias_set, 1133 alias_set_type base2_alias_set, bool tbaa_p) 1134 { 1135 tree ptr1; 1136 tree ptrtype1, dbase2; 1137 1138 gcc_checking_assert ((TREE_CODE (base1) == MEM_REF 1139 || TREE_CODE (base1) == TARGET_MEM_REF) 1140 && DECL_P (base2)); 1141 1142 ptr1 = TREE_OPERAND (base1, 0); 1143 poly_offset_int moff = mem_ref_offset (base1) << LOG2_BITS_PER_UNIT; 1144 1145 /* If only one reference is based on a variable, they cannot alias if 1146 the pointer access is beyond the extent of the variable access. 1147 (the pointer base cannot validly point to an offset less than zero 1148 of the variable). 1149 ??? IVOPTs creates bases that do not honor this restriction, 1150 so do not apply this optimization for TARGET_MEM_REFs. */ 1151 if (TREE_CODE (base1) != TARGET_MEM_REF 1152 && !ranges_maybe_overlap_p (offset1 + moff, -1, offset2, max_size2)) 1153 return false; 1154 /* They also cannot alias if the pointer may not point to the decl. */ 1155 if (!ptr_deref_may_alias_decl_p (ptr1, base2)) 1156 return false; 1157 1158 /* Disambiguations that rely on strict aliasing rules follow. */ 1159 if (!flag_strict_aliasing || !tbaa_p) 1160 return true; 1161 1162 ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1)); 1163 1164 /* If the alias set for a pointer access is zero all bets are off. */ 1165 if (base1_alias_set == 0) 1166 return true; 1167 1168 /* When we are trying to disambiguate an access with a pointer dereference 1169 as base versus one with a decl as base we can use both the size 1170 of the decl and its dynamic type for extra disambiguation. 1171 ??? We do not know anything about the dynamic type of the decl 1172 other than that its alias-set contains base2_alias_set as a subset 1173 which does not help us here. */ 1174 /* As we know nothing useful about the dynamic type of the decl just 1175 use the usual conflict check rather than a subset test. 1176 ??? We could introduce -fvery-strict-aliasing when the language 1177 does not allow decls to have a dynamic type that differs from their 1178 static type. Then we can check 1179 !alias_set_subset_of (base1_alias_set, base2_alias_set) instead. */ 1180 if (base1_alias_set != base2_alias_set 1181 && !alias_sets_conflict_p (base1_alias_set, base2_alias_set)) 1182 return false; 1183 /* If the size of the access relevant for TBAA through the pointer 1184 is bigger than the size of the decl we can't possibly access the 1185 decl via that pointer. */ 1186 if (DECL_SIZE (base2) && COMPLETE_TYPE_P (TREE_TYPE (ptrtype1)) 1187 && poly_int_tree_p (DECL_SIZE (base2)) 1188 && poly_int_tree_p (TYPE_SIZE (TREE_TYPE (ptrtype1))) 1189 /* ??? This in turn may run afoul when a decl of type T which is 1190 a member of union type U is accessed through a pointer to 1191 type U and sizeof T is smaller than sizeof U. */ 1192 && TREE_CODE (TREE_TYPE (ptrtype1)) != UNION_TYPE 1193 && TREE_CODE (TREE_TYPE (ptrtype1)) != QUAL_UNION_TYPE 1194 && known_lt (wi::to_poly_widest (DECL_SIZE (base2)), 1195 wi::to_poly_widest (TYPE_SIZE (TREE_TYPE (ptrtype1))))) 1196 return false; 1197 1198 if (!ref2) 1199 return true; 1200 1201 /* If the decl is accessed via a MEM_REF, reconstruct the base 1202 we can use for TBAA and an appropriately adjusted offset. */ 1203 dbase2 = ref2; 1204 while (handled_component_p (dbase2)) 1205 dbase2 = TREE_OPERAND (dbase2, 0); 1206 poly_int64 doffset1 = offset1; 1207 poly_offset_int doffset2 = offset2; 1208 if (TREE_CODE (dbase2) == MEM_REF 1209 || TREE_CODE (dbase2) == TARGET_MEM_REF) 1210 doffset2 -= mem_ref_offset (dbase2) << LOG2_BITS_PER_UNIT; 1211 1212 /* If either reference is view-converted, give up now. */ 1213 if (same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) != 1 1214 || same_type_for_tbaa (TREE_TYPE (dbase2), TREE_TYPE (base2)) != 1) 1215 return true; 1216 1217 /* If both references are through the same type, they do not alias 1218 if the accesses do not overlap. This does extra disambiguation 1219 for mixed/pointer accesses but requires strict aliasing. 1220 For MEM_REFs we require that the component-ref offset we computed 1221 is relative to the start of the type which we ensure by 1222 comparing rvalue and access type and disregarding the constant 1223 pointer offset. */ 1224 if ((TREE_CODE (base1) != TARGET_MEM_REF 1225 || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1))) 1226 && same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (dbase2)) == 1) 1227 return ranges_maybe_overlap_p (doffset1, max_size1, doffset2, max_size2); 1228 1229 if (ref1 && ref2 1230 && nonoverlapping_component_refs_p (ref1, ref2)) 1231 return false; 1232 1233 /* Do access-path based disambiguation. */ 1234 if (ref1 && ref2 1235 && (handled_component_p (ref1) || handled_component_p (ref2))) 1236 return aliasing_component_refs_p (ref1, 1237 ref1_alias_set, base1_alias_set, 1238 offset1, max_size1, 1239 ref2, 1240 ref2_alias_set, base2_alias_set, 1241 offset2, max_size2, true); 1242 1243 return true; 1244 } 1245 1246 /* Return true if two indirect references based on *PTR1 1247 and *PTR2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and 1248 [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. *PTR1 and *PTR2 have 1249 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1 1250 in which case they are computed on-demand. REF1 and REF2 1251 if non-NULL are the complete memory reference trees. */ 1252 1253 static bool 1254 indirect_refs_may_alias_p (tree ref1 ATTRIBUTE_UNUSED, tree base1, 1255 poly_int64 offset1, poly_int64 max_size1, 1256 alias_set_type ref1_alias_set, 1257 alias_set_type base1_alias_set, 1258 tree ref2 ATTRIBUTE_UNUSED, tree base2, 1259 poly_int64 offset2, poly_int64 max_size2, 1260 alias_set_type ref2_alias_set, 1261 alias_set_type base2_alias_set, bool tbaa_p) 1262 { 1263 tree ptr1; 1264 tree ptr2; 1265 tree ptrtype1, ptrtype2; 1266 1267 gcc_checking_assert ((TREE_CODE (base1) == MEM_REF 1268 || TREE_CODE (base1) == TARGET_MEM_REF) 1269 && (TREE_CODE (base2) == MEM_REF 1270 || TREE_CODE (base2) == TARGET_MEM_REF)); 1271 1272 ptr1 = TREE_OPERAND (base1, 0); 1273 ptr2 = TREE_OPERAND (base2, 0); 1274 1275 /* If both bases are based on pointers they cannot alias if they may not 1276 point to the same memory object or if they point to the same object 1277 and the accesses do not overlap. */ 1278 if ((!cfun || gimple_in_ssa_p (cfun)) 1279 && operand_equal_p (ptr1, ptr2, 0) 1280 && (((TREE_CODE (base1) != TARGET_MEM_REF 1281 || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1))) 1282 && (TREE_CODE (base2) != TARGET_MEM_REF 1283 || (!TMR_INDEX (base2) && !TMR_INDEX2 (base2)))) 1284 || (TREE_CODE (base1) == TARGET_MEM_REF 1285 && TREE_CODE (base2) == TARGET_MEM_REF 1286 && (TMR_STEP (base1) == TMR_STEP (base2) 1287 || (TMR_STEP (base1) && TMR_STEP (base2) 1288 && operand_equal_p (TMR_STEP (base1), 1289 TMR_STEP (base2), 0))) 1290 && (TMR_INDEX (base1) == TMR_INDEX (base2) 1291 || (TMR_INDEX (base1) && TMR_INDEX (base2) 1292 && operand_equal_p (TMR_INDEX (base1), 1293 TMR_INDEX (base2), 0))) 1294 && (TMR_INDEX2 (base1) == TMR_INDEX2 (base2) 1295 || (TMR_INDEX2 (base1) && TMR_INDEX2 (base2) 1296 && operand_equal_p (TMR_INDEX2 (base1), 1297 TMR_INDEX2 (base2), 0)))))) 1298 { 1299 poly_offset_int moff1 = mem_ref_offset (base1) << LOG2_BITS_PER_UNIT; 1300 poly_offset_int moff2 = mem_ref_offset (base2) << LOG2_BITS_PER_UNIT; 1301 return ranges_maybe_overlap_p (offset1 + moff1, max_size1, 1302 offset2 + moff2, max_size2); 1303 } 1304 if (!ptr_derefs_may_alias_p (ptr1, ptr2)) 1305 return false; 1306 1307 /* Disambiguations that rely on strict aliasing rules follow. */ 1308 if (!flag_strict_aliasing || !tbaa_p) 1309 return true; 1310 1311 ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1)); 1312 ptrtype2 = TREE_TYPE (TREE_OPERAND (base2, 1)); 1313 1314 /* If the alias set for a pointer access is zero all bets are off. */ 1315 if (base1_alias_set == 0 1316 || base2_alias_set == 0) 1317 return true; 1318 1319 /* If both references are through the same type, they do not alias 1320 if the accesses do not overlap. This does extra disambiguation 1321 for mixed/pointer accesses but requires strict aliasing. */ 1322 if ((TREE_CODE (base1) != TARGET_MEM_REF 1323 || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1))) 1324 && (TREE_CODE (base2) != TARGET_MEM_REF 1325 || (!TMR_INDEX (base2) && !TMR_INDEX2 (base2))) 1326 && same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1 1327 && same_type_for_tbaa (TREE_TYPE (base2), TREE_TYPE (ptrtype2)) == 1 1328 && same_type_for_tbaa (TREE_TYPE (ptrtype1), 1329 TREE_TYPE (ptrtype2)) == 1 1330 /* But avoid treating arrays as "objects", instead assume they 1331 can overlap by an exact multiple of their element size. */ 1332 && TREE_CODE (TREE_TYPE (ptrtype1)) != ARRAY_TYPE) 1333 return ranges_maybe_overlap_p (offset1, max_size1, offset2, max_size2); 1334 1335 /* Do type-based disambiguation. */ 1336 if (base1_alias_set != base2_alias_set 1337 && !alias_sets_conflict_p (base1_alias_set, base2_alias_set)) 1338 return false; 1339 1340 /* If either reference is view-converted, give up now. */ 1341 if (same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) != 1 1342 || same_type_for_tbaa (TREE_TYPE (base2), TREE_TYPE (ptrtype2)) != 1) 1343 return true; 1344 1345 if (ref1 && ref2 1346 && nonoverlapping_component_refs_p (ref1, ref2)) 1347 return false; 1348 1349 /* Do access-path based disambiguation. */ 1350 if (ref1 && ref2 1351 && (handled_component_p (ref1) || handled_component_p (ref2))) 1352 return aliasing_component_refs_p (ref1, 1353 ref1_alias_set, base1_alias_set, 1354 offset1, max_size1, 1355 ref2, 1356 ref2_alias_set, base2_alias_set, 1357 offset2, max_size2, false); 1358 1359 return true; 1360 } 1361 1362 /* Return true, if the two memory references REF1 and REF2 may alias. */ 1363 1364 bool 1365 refs_may_alias_p_1 (ao_ref *ref1, ao_ref *ref2, bool tbaa_p) 1366 { 1367 tree base1, base2; 1368 poly_int64 offset1 = 0, offset2 = 0; 1369 poly_int64 max_size1 = -1, max_size2 = -1; 1370 bool var1_p, var2_p, ind1_p, ind2_p; 1371 1372 gcc_checking_assert ((!ref1->ref 1373 || TREE_CODE (ref1->ref) == SSA_NAME 1374 || DECL_P (ref1->ref) 1375 || TREE_CODE (ref1->ref) == STRING_CST 1376 || handled_component_p (ref1->ref) 1377 || TREE_CODE (ref1->ref) == MEM_REF 1378 || TREE_CODE (ref1->ref) == TARGET_MEM_REF) 1379 && (!ref2->ref 1380 || TREE_CODE (ref2->ref) == SSA_NAME 1381 || DECL_P (ref2->ref) 1382 || TREE_CODE (ref2->ref) == STRING_CST 1383 || handled_component_p (ref2->ref) 1384 || TREE_CODE (ref2->ref) == MEM_REF 1385 || TREE_CODE (ref2->ref) == TARGET_MEM_REF)); 1386 1387 /* Decompose the references into their base objects and the access. */ 1388 base1 = ao_ref_base (ref1); 1389 offset1 = ref1->offset; 1390 max_size1 = ref1->max_size; 1391 base2 = ao_ref_base (ref2); 1392 offset2 = ref2->offset; 1393 max_size2 = ref2->max_size; 1394 1395 /* We can end up with registers or constants as bases for example from 1396 *D.1663_44 = VIEW_CONVERT_EXPR<struct DB_LSN>(__tmp$B0F64_59); 1397 which is seen as a struct copy. */ 1398 if (TREE_CODE (base1) == SSA_NAME 1399 || TREE_CODE (base1) == CONST_DECL 1400 || TREE_CODE (base1) == CONSTRUCTOR 1401 || TREE_CODE (base1) == ADDR_EXPR 1402 || CONSTANT_CLASS_P (base1) 1403 || TREE_CODE (base2) == SSA_NAME 1404 || TREE_CODE (base2) == CONST_DECL 1405 || TREE_CODE (base2) == CONSTRUCTOR 1406 || TREE_CODE (base2) == ADDR_EXPR 1407 || CONSTANT_CLASS_P (base2)) 1408 return false; 1409 1410 /* We can end up referring to code via function and label decls. 1411 As we likely do not properly track code aliases conservatively 1412 bail out. */ 1413 if (TREE_CODE (base1) == FUNCTION_DECL 1414 || TREE_CODE (base1) == LABEL_DECL 1415 || TREE_CODE (base2) == FUNCTION_DECL 1416 || TREE_CODE (base2) == LABEL_DECL) 1417 return true; 1418 1419 /* Two volatile accesses always conflict. */ 1420 if (ref1->volatile_p 1421 && ref2->volatile_p) 1422 return true; 1423 1424 /* Defer to simple offset based disambiguation if we have 1425 references based on two decls. Do this before defering to 1426 TBAA to handle must-alias cases in conformance with the 1427 GCC extension of allowing type-punning through unions. */ 1428 var1_p = DECL_P (base1); 1429 var2_p = DECL_P (base2); 1430 if (var1_p && var2_p) 1431 return decl_refs_may_alias_p (ref1->ref, base1, offset1, max_size1, 1432 ref2->ref, base2, offset2, max_size2); 1433 1434 /* Handle restrict based accesses. 1435 ??? ao_ref_base strips inner MEM_REF [&decl], recover from that 1436 here. */ 1437 tree rbase1 = base1; 1438 tree rbase2 = base2; 1439 if (var1_p) 1440 { 1441 rbase1 = ref1->ref; 1442 if (rbase1) 1443 while (handled_component_p (rbase1)) 1444 rbase1 = TREE_OPERAND (rbase1, 0); 1445 } 1446 if (var2_p) 1447 { 1448 rbase2 = ref2->ref; 1449 if (rbase2) 1450 while (handled_component_p (rbase2)) 1451 rbase2 = TREE_OPERAND (rbase2, 0); 1452 } 1453 if (rbase1 && rbase2 1454 && (TREE_CODE (base1) == MEM_REF || TREE_CODE (base1) == TARGET_MEM_REF) 1455 && (TREE_CODE (base2) == MEM_REF || TREE_CODE (base2) == TARGET_MEM_REF) 1456 /* If the accesses are in the same restrict clique... */ 1457 && MR_DEPENDENCE_CLIQUE (base1) == MR_DEPENDENCE_CLIQUE (base2) 1458 /* But based on different pointers they do not alias. */ 1459 && MR_DEPENDENCE_BASE (base1) != MR_DEPENDENCE_BASE (base2)) 1460 return false; 1461 1462 ind1_p = (TREE_CODE (base1) == MEM_REF 1463 || TREE_CODE (base1) == TARGET_MEM_REF); 1464 ind2_p = (TREE_CODE (base2) == MEM_REF 1465 || TREE_CODE (base2) == TARGET_MEM_REF); 1466 1467 /* Canonicalize the pointer-vs-decl case. */ 1468 if (ind1_p && var2_p) 1469 { 1470 std::swap (offset1, offset2); 1471 std::swap (max_size1, max_size2); 1472 std::swap (base1, base2); 1473 std::swap (ref1, ref2); 1474 var1_p = true; 1475 ind1_p = false; 1476 var2_p = false; 1477 ind2_p = true; 1478 } 1479 1480 /* First defer to TBAA if possible. */ 1481 if (tbaa_p 1482 && flag_strict_aliasing 1483 && !alias_sets_conflict_p (ao_ref_alias_set (ref1), 1484 ao_ref_alias_set (ref2))) 1485 return false; 1486 1487 /* If the reference is based on a pointer that points to memory 1488 that may not be written to then the other reference cannot possibly 1489 clobber it. */ 1490 if ((TREE_CODE (TREE_OPERAND (base2, 0)) == SSA_NAME 1491 && SSA_NAME_POINTS_TO_READONLY_MEMORY (TREE_OPERAND (base2, 0))) 1492 || (ind1_p 1493 && TREE_CODE (TREE_OPERAND (base1, 0)) == SSA_NAME 1494 && SSA_NAME_POINTS_TO_READONLY_MEMORY (TREE_OPERAND (base1, 0)))) 1495 return false; 1496 1497 /* Dispatch to the pointer-vs-decl or pointer-vs-pointer disambiguators. */ 1498 if (var1_p && ind2_p) 1499 return indirect_ref_may_alias_decl_p (ref2->ref, base2, 1500 offset2, max_size2, 1501 ao_ref_alias_set (ref2), 1502 ao_ref_base_alias_set (ref2), 1503 ref1->ref, base1, 1504 offset1, max_size1, 1505 ao_ref_alias_set (ref1), 1506 ao_ref_base_alias_set (ref1), 1507 tbaa_p); 1508 else if (ind1_p && ind2_p) 1509 return indirect_refs_may_alias_p (ref1->ref, base1, 1510 offset1, max_size1, 1511 ao_ref_alias_set (ref1), 1512 ao_ref_base_alias_set (ref1), 1513 ref2->ref, base2, 1514 offset2, max_size2, 1515 ao_ref_alias_set (ref2), 1516 ao_ref_base_alias_set (ref2), 1517 tbaa_p); 1518 1519 gcc_unreachable (); 1520 } 1521 1522 static bool 1523 refs_may_alias_p (tree ref1, ao_ref *ref2, bool tbaa_p) 1524 { 1525 ao_ref r1; 1526 ao_ref_init (&r1, ref1); 1527 return refs_may_alias_p_1 (&r1, ref2, tbaa_p); 1528 } 1529 1530 bool 1531 refs_may_alias_p (tree ref1, tree ref2, bool tbaa_p) 1532 { 1533 ao_ref r1, r2; 1534 bool res; 1535 ao_ref_init (&r1, ref1); 1536 ao_ref_init (&r2, ref2); 1537 res = refs_may_alias_p_1 (&r1, &r2, tbaa_p); 1538 if (res) 1539 ++alias_stats.refs_may_alias_p_may_alias; 1540 else 1541 ++alias_stats.refs_may_alias_p_no_alias; 1542 return res; 1543 } 1544 1545 /* Returns true if there is a anti-dependence for the STORE that 1546 executes after the LOAD. */ 1547 1548 bool 1549 refs_anti_dependent_p (tree load, tree store) 1550 { 1551 ao_ref r1, r2; 1552 ao_ref_init (&r1, load); 1553 ao_ref_init (&r2, store); 1554 return refs_may_alias_p_1 (&r1, &r2, false); 1555 } 1556 1557 /* Returns true if there is a output dependence for the stores 1558 STORE1 and STORE2. */ 1559 1560 bool 1561 refs_output_dependent_p (tree store1, tree store2) 1562 { 1563 ao_ref r1, r2; 1564 ao_ref_init (&r1, store1); 1565 ao_ref_init (&r2, store2); 1566 return refs_may_alias_p_1 (&r1, &r2, false); 1567 } 1568 1569 /* If the call CALL may use the memory reference REF return true, 1570 otherwise return false. */ 1571 1572 static bool 1573 ref_maybe_used_by_call_p_1 (gcall *call, ao_ref *ref, bool tbaa_p) 1574 { 1575 tree base, callee; 1576 unsigned i; 1577 int flags = gimple_call_flags (call); 1578 1579 /* Const functions without a static chain do not implicitly use memory. */ 1580 if (!gimple_call_chain (call) 1581 && (flags & (ECF_CONST|ECF_NOVOPS))) 1582 goto process_args; 1583 1584 base = ao_ref_base (ref); 1585 if (!base) 1586 return true; 1587 1588 /* A call that is not without side-effects might involve volatile 1589 accesses and thus conflicts with all other volatile accesses. */ 1590 if (ref->volatile_p) 1591 return true; 1592 1593 /* If the reference is based on a decl that is not aliased the call 1594 cannot possibly use it. */ 1595 if (DECL_P (base) 1596 && !may_be_aliased (base) 1597 /* But local statics can be used through recursion. */ 1598 && !is_global_var (base)) 1599 goto process_args; 1600 1601 callee = gimple_call_fndecl (call); 1602 1603 /* Handle those builtin functions explicitly that do not act as 1604 escape points. See tree-ssa-structalias.c:find_func_aliases 1605 for the list of builtins we might need to handle here. */ 1606 if (callee != NULL_TREE 1607 && gimple_call_builtin_p (call, BUILT_IN_NORMAL)) 1608 switch (DECL_FUNCTION_CODE (callee)) 1609 { 1610 /* All the following functions read memory pointed to by 1611 their second argument. strcat/strncat additionally 1612 reads memory pointed to by the first argument. */ 1613 case BUILT_IN_STRCAT: 1614 case BUILT_IN_STRNCAT: 1615 { 1616 ao_ref dref; 1617 ao_ref_init_from_ptr_and_size (&dref, 1618 gimple_call_arg (call, 0), 1619 NULL_TREE); 1620 if (refs_may_alias_p_1 (&dref, ref, false)) 1621 return true; 1622 } 1623 /* FALLTHRU */ 1624 case BUILT_IN_STRCPY: 1625 case BUILT_IN_STRNCPY: 1626 case BUILT_IN_MEMCPY: 1627 case BUILT_IN_MEMMOVE: 1628 case BUILT_IN_MEMPCPY: 1629 case BUILT_IN_STPCPY: 1630 case BUILT_IN_STPNCPY: 1631 case BUILT_IN_TM_MEMCPY: 1632 case BUILT_IN_TM_MEMMOVE: 1633 { 1634 ao_ref dref; 1635 tree size = NULL_TREE; 1636 if (gimple_call_num_args (call) == 3) 1637 size = gimple_call_arg (call, 2); 1638 ao_ref_init_from_ptr_and_size (&dref, 1639 gimple_call_arg (call, 1), 1640 size); 1641 return refs_may_alias_p_1 (&dref, ref, false); 1642 } 1643 case BUILT_IN_STRCAT_CHK: 1644 case BUILT_IN_STRNCAT_CHK: 1645 { 1646 ao_ref dref; 1647 ao_ref_init_from_ptr_and_size (&dref, 1648 gimple_call_arg (call, 0), 1649 NULL_TREE); 1650 if (refs_may_alias_p_1 (&dref, ref, false)) 1651 return true; 1652 } 1653 /* FALLTHRU */ 1654 case BUILT_IN_STRCPY_CHK: 1655 case BUILT_IN_STRNCPY_CHK: 1656 case BUILT_IN_MEMCPY_CHK: 1657 case BUILT_IN_MEMMOVE_CHK: 1658 case BUILT_IN_MEMPCPY_CHK: 1659 case BUILT_IN_STPCPY_CHK: 1660 case BUILT_IN_STPNCPY_CHK: 1661 { 1662 ao_ref dref; 1663 tree size = NULL_TREE; 1664 if (gimple_call_num_args (call) == 4) 1665 size = gimple_call_arg (call, 2); 1666 ao_ref_init_from_ptr_and_size (&dref, 1667 gimple_call_arg (call, 1), 1668 size); 1669 return refs_may_alias_p_1 (&dref, ref, false); 1670 } 1671 case BUILT_IN_BCOPY: 1672 { 1673 ao_ref dref; 1674 tree size = gimple_call_arg (call, 2); 1675 ao_ref_init_from_ptr_and_size (&dref, 1676 gimple_call_arg (call, 0), 1677 size); 1678 return refs_may_alias_p_1 (&dref, ref, false); 1679 } 1680 1681 /* The following functions read memory pointed to by their 1682 first argument. */ 1683 CASE_BUILT_IN_TM_LOAD (1): 1684 CASE_BUILT_IN_TM_LOAD (2): 1685 CASE_BUILT_IN_TM_LOAD (4): 1686 CASE_BUILT_IN_TM_LOAD (8): 1687 CASE_BUILT_IN_TM_LOAD (FLOAT): 1688 CASE_BUILT_IN_TM_LOAD (DOUBLE): 1689 CASE_BUILT_IN_TM_LOAD (LDOUBLE): 1690 CASE_BUILT_IN_TM_LOAD (M64): 1691 CASE_BUILT_IN_TM_LOAD (M128): 1692 CASE_BUILT_IN_TM_LOAD (M256): 1693 case BUILT_IN_TM_LOG: 1694 case BUILT_IN_TM_LOG_1: 1695 case BUILT_IN_TM_LOG_2: 1696 case BUILT_IN_TM_LOG_4: 1697 case BUILT_IN_TM_LOG_8: 1698 case BUILT_IN_TM_LOG_FLOAT: 1699 case BUILT_IN_TM_LOG_DOUBLE: 1700 case BUILT_IN_TM_LOG_LDOUBLE: 1701 case BUILT_IN_TM_LOG_M64: 1702 case BUILT_IN_TM_LOG_M128: 1703 case BUILT_IN_TM_LOG_M256: 1704 return ptr_deref_may_alias_ref_p_1 (gimple_call_arg (call, 0), ref); 1705 1706 /* These read memory pointed to by the first argument. */ 1707 case BUILT_IN_STRDUP: 1708 case BUILT_IN_STRNDUP: 1709 case BUILT_IN_REALLOC: 1710 { 1711 ao_ref dref; 1712 tree size = NULL_TREE; 1713 if (gimple_call_num_args (call) == 2) 1714 size = gimple_call_arg (call, 1); 1715 ao_ref_init_from_ptr_and_size (&dref, 1716 gimple_call_arg (call, 0), 1717 size); 1718 return refs_may_alias_p_1 (&dref, ref, false); 1719 } 1720 /* These read memory pointed to by the first argument. */ 1721 case BUILT_IN_INDEX: 1722 case BUILT_IN_STRCHR: 1723 case BUILT_IN_STRRCHR: 1724 { 1725 ao_ref dref; 1726 ao_ref_init_from_ptr_and_size (&dref, 1727 gimple_call_arg (call, 0), 1728 NULL_TREE); 1729 return refs_may_alias_p_1 (&dref, ref, false); 1730 } 1731 /* These read memory pointed to by the first argument with size 1732 in the third argument. */ 1733 case BUILT_IN_MEMCHR: 1734 { 1735 ao_ref dref; 1736 ao_ref_init_from_ptr_and_size (&dref, 1737 gimple_call_arg (call, 0), 1738 gimple_call_arg (call, 2)); 1739 return refs_may_alias_p_1 (&dref, ref, false); 1740 } 1741 /* These read memory pointed to by the first and second arguments. */ 1742 case BUILT_IN_STRSTR: 1743 case BUILT_IN_STRPBRK: 1744 { 1745 ao_ref dref; 1746 ao_ref_init_from_ptr_and_size (&dref, 1747 gimple_call_arg (call, 0), 1748 NULL_TREE); 1749 if (refs_may_alias_p_1 (&dref, ref, false)) 1750 return true; 1751 ao_ref_init_from_ptr_and_size (&dref, 1752 gimple_call_arg (call, 1), 1753 NULL_TREE); 1754 return refs_may_alias_p_1 (&dref, ref, false); 1755 } 1756 1757 /* The following builtins do not read from memory. */ 1758 case BUILT_IN_FREE: 1759 case BUILT_IN_MALLOC: 1760 case BUILT_IN_POSIX_MEMALIGN: 1761 case BUILT_IN_ALIGNED_ALLOC: 1762 case BUILT_IN_CALLOC: 1763 CASE_BUILT_IN_ALLOCA: 1764 case BUILT_IN_STACK_SAVE: 1765 case BUILT_IN_STACK_RESTORE: 1766 case BUILT_IN_MEMSET: 1767 case BUILT_IN_TM_MEMSET: 1768 case BUILT_IN_MEMSET_CHK: 1769 case BUILT_IN_FREXP: 1770 case BUILT_IN_FREXPF: 1771 case BUILT_IN_FREXPL: 1772 case BUILT_IN_GAMMA_R: 1773 case BUILT_IN_GAMMAF_R: 1774 case BUILT_IN_GAMMAL_R: 1775 case BUILT_IN_LGAMMA_R: 1776 case BUILT_IN_LGAMMAF_R: 1777 case BUILT_IN_LGAMMAL_R: 1778 case BUILT_IN_MODF: 1779 case BUILT_IN_MODFF: 1780 case BUILT_IN_MODFL: 1781 case BUILT_IN_REMQUO: 1782 case BUILT_IN_REMQUOF: 1783 case BUILT_IN_REMQUOL: 1784 case BUILT_IN_SINCOS: 1785 case BUILT_IN_SINCOSF: 1786 case BUILT_IN_SINCOSL: 1787 case BUILT_IN_ASSUME_ALIGNED: 1788 case BUILT_IN_VA_END: 1789 return false; 1790 /* __sync_* builtins and some OpenMP builtins act as threading 1791 barriers. */ 1792 #undef DEF_SYNC_BUILTIN 1793 #define DEF_SYNC_BUILTIN(ENUM, NAME, TYPE, ATTRS) case ENUM: 1794 #include "sync-builtins.def" 1795 #undef DEF_SYNC_BUILTIN 1796 case BUILT_IN_GOMP_ATOMIC_START: 1797 case BUILT_IN_GOMP_ATOMIC_END: 1798 case BUILT_IN_GOMP_BARRIER: 1799 case BUILT_IN_GOMP_BARRIER_CANCEL: 1800 case BUILT_IN_GOMP_TASKWAIT: 1801 case BUILT_IN_GOMP_TASKGROUP_END: 1802 case BUILT_IN_GOMP_CRITICAL_START: 1803 case BUILT_IN_GOMP_CRITICAL_END: 1804 case BUILT_IN_GOMP_CRITICAL_NAME_START: 1805 case BUILT_IN_GOMP_CRITICAL_NAME_END: 1806 case BUILT_IN_GOMP_LOOP_END: 1807 case BUILT_IN_GOMP_LOOP_END_CANCEL: 1808 case BUILT_IN_GOMP_ORDERED_START: 1809 case BUILT_IN_GOMP_ORDERED_END: 1810 case BUILT_IN_GOMP_SECTIONS_END: 1811 case BUILT_IN_GOMP_SECTIONS_END_CANCEL: 1812 case BUILT_IN_GOMP_SINGLE_COPY_START: 1813 case BUILT_IN_GOMP_SINGLE_COPY_END: 1814 return true; 1815 1816 default: 1817 /* Fallthru to general call handling. */; 1818 } 1819 1820 /* Check if base is a global static variable that is not read 1821 by the function. */ 1822 if (callee != NULL_TREE && VAR_P (base) && TREE_STATIC (base)) 1823 { 1824 struct cgraph_node *node = cgraph_node::get (callee); 1825 bitmap not_read; 1826 1827 /* FIXME: Callee can be an OMP builtin that does not have a call graph 1828 node yet. We should enforce that there are nodes for all decls in the 1829 IL and remove this check instead. */ 1830 if (node 1831 && (not_read = ipa_reference_get_not_read_global (node)) 1832 && bitmap_bit_p (not_read, ipa_reference_var_uid (base))) 1833 goto process_args; 1834 } 1835 1836 /* Check if the base variable is call-used. */ 1837 if (DECL_P (base)) 1838 { 1839 if (pt_solution_includes (gimple_call_use_set (call), base)) 1840 return true; 1841 } 1842 else if ((TREE_CODE (base) == MEM_REF 1843 || TREE_CODE (base) == TARGET_MEM_REF) 1844 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME) 1845 { 1846 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0)); 1847 if (!pi) 1848 return true; 1849 1850 if (pt_solutions_intersect (gimple_call_use_set (call), &pi->pt)) 1851 return true; 1852 } 1853 else 1854 return true; 1855 1856 /* Inspect call arguments for passed-by-value aliases. */ 1857 process_args: 1858 for (i = 0; i < gimple_call_num_args (call); ++i) 1859 { 1860 tree op = gimple_call_arg (call, i); 1861 int flags = gimple_call_arg_flags (call, i); 1862 1863 if (flags & EAF_UNUSED) 1864 continue; 1865 1866 if (TREE_CODE (op) == WITH_SIZE_EXPR) 1867 op = TREE_OPERAND (op, 0); 1868 1869 if (TREE_CODE (op) != SSA_NAME 1870 && !is_gimple_min_invariant (op)) 1871 { 1872 ao_ref r; 1873 ao_ref_init (&r, op); 1874 if (refs_may_alias_p_1 (&r, ref, tbaa_p)) 1875 return true; 1876 } 1877 } 1878 1879 return false; 1880 } 1881 1882 static bool 1883 ref_maybe_used_by_call_p (gcall *call, ao_ref *ref, bool tbaa_p) 1884 { 1885 bool res; 1886 res = ref_maybe_used_by_call_p_1 (call, ref, tbaa_p); 1887 if (res) 1888 ++alias_stats.ref_maybe_used_by_call_p_may_alias; 1889 else 1890 ++alias_stats.ref_maybe_used_by_call_p_no_alias; 1891 return res; 1892 } 1893 1894 1895 /* If the statement STMT may use the memory reference REF return 1896 true, otherwise return false. */ 1897 1898 bool 1899 ref_maybe_used_by_stmt_p (gimple *stmt, ao_ref *ref, bool tbaa_p) 1900 { 1901 if (is_gimple_assign (stmt)) 1902 { 1903 tree rhs; 1904 1905 /* All memory assign statements are single. */ 1906 if (!gimple_assign_single_p (stmt)) 1907 return false; 1908 1909 rhs = gimple_assign_rhs1 (stmt); 1910 if (is_gimple_reg (rhs) 1911 || is_gimple_min_invariant (rhs) 1912 || gimple_assign_rhs_code (stmt) == CONSTRUCTOR) 1913 return false; 1914 1915 return refs_may_alias_p (rhs, ref, tbaa_p); 1916 } 1917 else if (is_gimple_call (stmt)) 1918 return ref_maybe_used_by_call_p (as_a <gcall *> (stmt), ref, tbaa_p); 1919 else if (greturn *return_stmt = dyn_cast <greturn *> (stmt)) 1920 { 1921 tree retval = gimple_return_retval (return_stmt); 1922 if (retval 1923 && TREE_CODE (retval) != SSA_NAME 1924 && !is_gimple_min_invariant (retval) 1925 && refs_may_alias_p (retval, ref, tbaa_p)) 1926 return true; 1927 /* If ref escapes the function then the return acts as a use. */ 1928 tree base = ao_ref_base (ref); 1929 if (!base) 1930 ; 1931 else if (DECL_P (base)) 1932 return is_global_var (base); 1933 else if (TREE_CODE (base) == MEM_REF 1934 || TREE_CODE (base) == TARGET_MEM_REF) 1935 return ptr_deref_may_alias_global_p (TREE_OPERAND (base, 0)); 1936 return false; 1937 } 1938 1939 return true; 1940 } 1941 1942 bool 1943 ref_maybe_used_by_stmt_p (gimple *stmt, tree ref, bool tbaa_p) 1944 { 1945 ao_ref r; 1946 ao_ref_init (&r, ref); 1947 return ref_maybe_used_by_stmt_p (stmt, &r, tbaa_p); 1948 } 1949 1950 /* If the call in statement CALL may clobber the memory reference REF 1951 return true, otherwise return false. */ 1952 1953 bool 1954 call_may_clobber_ref_p_1 (gcall *call, ao_ref *ref) 1955 { 1956 tree base; 1957 tree callee; 1958 1959 /* If the call is pure or const it cannot clobber anything. */ 1960 if (gimple_call_flags (call) 1961 & (ECF_PURE|ECF_CONST|ECF_LOOPING_CONST_OR_PURE|ECF_NOVOPS)) 1962 return false; 1963 if (gimple_call_internal_p (call)) 1964 switch (gimple_call_internal_fn (call)) 1965 { 1966 /* Treat these internal calls like ECF_PURE for aliasing, 1967 they don't write to any memory the program should care about. 1968 They have important other side-effects, and read memory, 1969 so can't be ECF_NOVOPS. */ 1970 case IFN_UBSAN_NULL: 1971 case IFN_UBSAN_BOUNDS: 1972 case IFN_UBSAN_VPTR: 1973 case IFN_UBSAN_OBJECT_SIZE: 1974 case IFN_UBSAN_PTR: 1975 case IFN_ASAN_CHECK: 1976 return false; 1977 default: 1978 break; 1979 } 1980 1981 base = ao_ref_base (ref); 1982 if (!base) 1983 return true; 1984 1985 if (TREE_CODE (base) == SSA_NAME 1986 || CONSTANT_CLASS_P (base)) 1987 return false; 1988 1989 /* A call that is not without side-effects might involve volatile 1990 accesses and thus conflicts with all other volatile accesses. */ 1991 if (ref->volatile_p) 1992 return true; 1993 1994 /* If the reference is based on a decl that is not aliased the call 1995 cannot possibly clobber it. */ 1996 if (DECL_P (base) 1997 && !may_be_aliased (base) 1998 /* But local non-readonly statics can be modified through recursion 1999 or the call may implement a threading barrier which we must 2000 treat as may-def. */ 2001 && (TREE_READONLY (base) 2002 || !is_global_var (base))) 2003 return false; 2004 2005 /* If the reference is based on a pointer that points to memory 2006 that may not be written to then the call cannot possibly clobber it. */ 2007 if ((TREE_CODE (base) == MEM_REF 2008 || TREE_CODE (base) == TARGET_MEM_REF) 2009 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME 2010 && SSA_NAME_POINTS_TO_READONLY_MEMORY (TREE_OPERAND (base, 0))) 2011 return false; 2012 2013 callee = gimple_call_fndecl (call); 2014 2015 /* Handle those builtin functions explicitly that do not act as 2016 escape points. See tree-ssa-structalias.c:find_func_aliases 2017 for the list of builtins we might need to handle here. */ 2018 if (callee != NULL_TREE 2019 && gimple_call_builtin_p (call, BUILT_IN_NORMAL)) 2020 switch (DECL_FUNCTION_CODE (callee)) 2021 { 2022 /* All the following functions clobber memory pointed to by 2023 their first argument. */ 2024 case BUILT_IN_STRCPY: 2025 case BUILT_IN_STRNCPY: 2026 case BUILT_IN_MEMCPY: 2027 case BUILT_IN_MEMMOVE: 2028 case BUILT_IN_MEMPCPY: 2029 case BUILT_IN_STPCPY: 2030 case BUILT_IN_STPNCPY: 2031 case BUILT_IN_STRCAT: 2032 case BUILT_IN_STRNCAT: 2033 case BUILT_IN_MEMSET: 2034 case BUILT_IN_TM_MEMSET: 2035 CASE_BUILT_IN_TM_STORE (1): 2036 CASE_BUILT_IN_TM_STORE (2): 2037 CASE_BUILT_IN_TM_STORE (4): 2038 CASE_BUILT_IN_TM_STORE (8): 2039 CASE_BUILT_IN_TM_STORE (FLOAT): 2040 CASE_BUILT_IN_TM_STORE (DOUBLE): 2041 CASE_BUILT_IN_TM_STORE (LDOUBLE): 2042 CASE_BUILT_IN_TM_STORE (M64): 2043 CASE_BUILT_IN_TM_STORE (M128): 2044 CASE_BUILT_IN_TM_STORE (M256): 2045 case BUILT_IN_TM_MEMCPY: 2046 case BUILT_IN_TM_MEMMOVE: 2047 { 2048 ao_ref dref; 2049 tree size = NULL_TREE; 2050 /* Don't pass in size for strncat, as the maximum size 2051 is strlen (dest) + n + 1 instead of n, resp. 2052 n + 1 at dest + strlen (dest), but strlen (dest) isn't 2053 known. */ 2054 if (gimple_call_num_args (call) == 3 2055 && DECL_FUNCTION_CODE (callee) != BUILT_IN_STRNCAT) 2056 size = gimple_call_arg (call, 2); 2057 ao_ref_init_from_ptr_and_size (&dref, 2058 gimple_call_arg (call, 0), 2059 size); 2060 return refs_may_alias_p_1 (&dref, ref, false); 2061 } 2062 case BUILT_IN_STRCPY_CHK: 2063 case BUILT_IN_STRNCPY_CHK: 2064 case BUILT_IN_MEMCPY_CHK: 2065 case BUILT_IN_MEMMOVE_CHK: 2066 case BUILT_IN_MEMPCPY_CHK: 2067 case BUILT_IN_STPCPY_CHK: 2068 case BUILT_IN_STPNCPY_CHK: 2069 case BUILT_IN_STRCAT_CHK: 2070 case BUILT_IN_STRNCAT_CHK: 2071 case BUILT_IN_MEMSET_CHK: 2072 { 2073 ao_ref dref; 2074 tree size = NULL_TREE; 2075 /* Don't pass in size for __strncat_chk, as the maximum size 2076 is strlen (dest) + n + 1 instead of n, resp. 2077 n + 1 at dest + strlen (dest), but strlen (dest) isn't 2078 known. */ 2079 if (gimple_call_num_args (call) == 4 2080 && DECL_FUNCTION_CODE (callee) != BUILT_IN_STRNCAT_CHK) 2081 size = gimple_call_arg (call, 2); 2082 ao_ref_init_from_ptr_and_size (&dref, 2083 gimple_call_arg (call, 0), 2084 size); 2085 return refs_may_alias_p_1 (&dref, ref, false); 2086 } 2087 case BUILT_IN_BCOPY: 2088 { 2089 ao_ref dref; 2090 tree size = gimple_call_arg (call, 2); 2091 ao_ref_init_from_ptr_and_size (&dref, 2092 gimple_call_arg (call, 1), 2093 size); 2094 return refs_may_alias_p_1 (&dref, ref, false); 2095 } 2096 /* Allocating memory does not have any side-effects apart from 2097 being the definition point for the pointer. */ 2098 case BUILT_IN_MALLOC: 2099 case BUILT_IN_ALIGNED_ALLOC: 2100 case BUILT_IN_CALLOC: 2101 case BUILT_IN_STRDUP: 2102 case BUILT_IN_STRNDUP: 2103 /* Unix98 specifies that errno is set on allocation failure. */ 2104 if (flag_errno_math 2105 && targetm.ref_may_alias_errno (ref)) 2106 return true; 2107 return false; 2108 case BUILT_IN_STACK_SAVE: 2109 CASE_BUILT_IN_ALLOCA: 2110 case BUILT_IN_ASSUME_ALIGNED: 2111 return false; 2112 /* But posix_memalign stores a pointer into the memory pointed to 2113 by its first argument. */ 2114 case BUILT_IN_POSIX_MEMALIGN: 2115 { 2116 tree ptrptr = gimple_call_arg (call, 0); 2117 ao_ref dref; 2118 ao_ref_init_from_ptr_and_size (&dref, ptrptr, 2119 TYPE_SIZE_UNIT (ptr_type_node)); 2120 return (refs_may_alias_p_1 (&dref, ref, false) 2121 || (flag_errno_math 2122 && targetm.ref_may_alias_errno (ref))); 2123 } 2124 /* Freeing memory kills the pointed-to memory. More importantly 2125 the call has to serve as a barrier for moving loads and stores 2126 across it. */ 2127 case BUILT_IN_FREE: 2128 case BUILT_IN_VA_END: 2129 { 2130 tree ptr = gimple_call_arg (call, 0); 2131 return ptr_deref_may_alias_ref_p_1 (ptr, ref); 2132 } 2133 /* Realloc serves both as allocation point and deallocation point. */ 2134 case BUILT_IN_REALLOC: 2135 { 2136 tree ptr = gimple_call_arg (call, 0); 2137 /* Unix98 specifies that errno is set on allocation failure. */ 2138 return ((flag_errno_math 2139 && targetm.ref_may_alias_errno (ref)) 2140 || ptr_deref_may_alias_ref_p_1 (ptr, ref)); 2141 } 2142 case BUILT_IN_GAMMA_R: 2143 case BUILT_IN_GAMMAF_R: 2144 case BUILT_IN_GAMMAL_R: 2145 case BUILT_IN_LGAMMA_R: 2146 case BUILT_IN_LGAMMAF_R: 2147 case BUILT_IN_LGAMMAL_R: 2148 { 2149 tree out = gimple_call_arg (call, 1); 2150 if (ptr_deref_may_alias_ref_p_1 (out, ref)) 2151 return true; 2152 if (flag_errno_math) 2153 break; 2154 return false; 2155 } 2156 case BUILT_IN_FREXP: 2157 case BUILT_IN_FREXPF: 2158 case BUILT_IN_FREXPL: 2159 case BUILT_IN_MODF: 2160 case BUILT_IN_MODFF: 2161 case BUILT_IN_MODFL: 2162 { 2163 tree out = gimple_call_arg (call, 1); 2164 return ptr_deref_may_alias_ref_p_1 (out, ref); 2165 } 2166 case BUILT_IN_REMQUO: 2167 case BUILT_IN_REMQUOF: 2168 case BUILT_IN_REMQUOL: 2169 { 2170 tree out = gimple_call_arg (call, 2); 2171 if (ptr_deref_may_alias_ref_p_1 (out, ref)) 2172 return true; 2173 if (flag_errno_math) 2174 break; 2175 return false; 2176 } 2177 case BUILT_IN_SINCOS: 2178 case BUILT_IN_SINCOSF: 2179 case BUILT_IN_SINCOSL: 2180 { 2181 tree sin = gimple_call_arg (call, 1); 2182 tree cos = gimple_call_arg (call, 2); 2183 return (ptr_deref_may_alias_ref_p_1 (sin, ref) 2184 || ptr_deref_may_alias_ref_p_1 (cos, ref)); 2185 } 2186 /* __sync_* builtins and some OpenMP builtins act as threading 2187 barriers. */ 2188 #undef DEF_SYNC_BUILTIN 2189 #define DEF_SYNC_BUILTIN(ENUM, NAME, TYPE, ATTRS) case ENUM: 2190 #include "sync-builtins.def" 2191 #undef DEF_SYNC_BUILTIN 2192 case BUILT_IN_GOMP_ATOMIC_START: 2193 case BUILT_IN_GOMP_ATOMIC_END: 2194 case BUILT_IN_GOMP_BARRIER: 2195 case BUILT_IN_GOMP_BARRIER_CANCEL: 2196 case BUILT_IN_GOMP_TASKWAIT: 2197 case BUILT_IN_GOMP_TASKGROUP_END: 2198 case BUILT_IN_GOMP_CRITICAL_START: 2199 case BUILT_IN_GOMP_CRITICAL_END: 2200 case BUILT_IN_GOMP_CRITICAL_NAME_START: 2201 case BUILT_IN_GOMP_CRITICAL_NAME_END: 2202 case BUILT_IN_GOMP_LOOP_END: 2203 case BUILT_IN_GOMP_LOOP_END_CANCEL: 2204 case BUILT_IN_GOMP_ORDERED_START: 2205 case BUILT_IN_GOMP_ORDERED_END: 2206 case BUILT_IN_GOMP_SECTIONS_END: 2207 case BUILT_IN_GOMP_SECTIONS_END_CANCEL: 2208 case BUILT_IN_GOMP_SINGLE_COPY_START: 2209 case BUILT_IN_GOMP_SINGLE_COPY_END: 2210 return true; 2211 default: 2212 /* Fallthru to general call handling. */; 2213 } 2214 2215 /* Check if base is a global static variable that is not written 2216 by the function. */ 2217 if (callee != NULL_TREE && VAR_P (base) && TREE_STATIC (base)) 2218 { 2219 struct cgraph_node *node = cgraph_node::get (callee); 2220 bitmap not_written; 2221 2222 if (node 2223 && (not_written = ipa_reference_get_not_written_global (node)) 2224 && bitmap_bit_p (not_written, ipa_reference_var_uid (base))) 2225 return false; 2226 } 2227 2228 /* Check if the base variable is call-clobbered. */ 2229 if (DECL_P (base)) 2230 return pt_solution_includes (gimple_call_clobber_set (call), base); 2231 else if ((TREE_CODE (base) == MEM_REF 2232 || TREE_CODE (base) == TARGET_MEM_REF) 2233 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME) 2234 { 2235 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0)); 2236 if (!pi) 2237 return true; 2238 2239 return pt_solutions_intersect (gimple_call_clobber_set (call), &pi->pt); 2240 } 2241 2242 return true; 2243 } 2244 2245 /* If the call in statement CALL may clobber the memory reference REF 2246 return true, otherwise return false. */ 2247 2248 bool 2249 call_may_clobber_ref_p (gcall *call, tree ref) 2250 { 2251 bool res; 2252 ao_ref r; 2253 ao_ref_init (&r, ref); 2254 res = call_may_clobber_ref_p_1 (call, &r); 2255 if (res) 2256 ++alias_stats.call_may_clobber_ref_p_may_alias; 2257 else 2258 ++alias_stats.call_may_clobber_ref_p_no_alias; 2259 return res; 2260 } 2261 2262 2263 /* If the statement STMT may clobber the memory reference REF return true, 2264 otherwise return false. */ 2265 2266 bool 2267 stmt_may_clobber_ref_p_1 (gimple *stmt, ao_ref *ref, bool tbaa_p) 2268 { 2269 if (is_gimple_call (stmt)) 2270 { 2271 tree lhs = gimple_call_lhs (stmt); 2272 if (lhs 2273 && TREE_CODE (lhs) != SSA_NAME) 2274 { 2275 ao_ref r; 2276 ao_ref_init (&r, lhs); 2277 if (refs_may_alias_p_1 (ref, &r, tbaa_p)) 2278 return true; 2279 } 2280 2281 return call_may_clobber_ref_p_1 (as_a <gcall *> (stmt), ref); 2282 } 2283 else if (gimple_assign_single_p (stmt)) 2284 { 2285 tree lhs = gimple_assign_lhs (stmt); 2286 if (TREE_CODE (lhs) != SSA_NAME) 2287 { 2288 ao_ref r; 2289 ao_ref_init (&r, lhs); 2290 return refs_may_alias_p_1 (ref, &r, tbaa_p); 2291 } 2292 } 2293 else if (gimple_code (stmt) == GIMPLE_ASM) 2294 return true; 2295 2296 return false; 2297 } 2298 2299 bool 2300 stmt_may_clobber_ref_p (gimple *stmt, tree ref, bool tbaa_p) 2301 { 2302 ao_ref r; 2303 ao_ref_init (&r, ref); 2304 return stmt_may_clobber_ref_p_1 (stmt, &r, tbaa_p); 2305 } 2306 2307 /* Return true if store1 and store2 described by corresponding tuples 2308 <BASE, OFFSET, SIZE, MAX_SIZE> have the same size and store to the same 2309 address. */ 2310 2311 static bool 2312 same_addr_size_stores_p (tree base1, poly_int64 offset1, poly_int64 size1, 2313 poly_int64 max_size1, 2314 tree base2, poly_int64 offset2, poly_int64 size2, 2315 poly_int64 max_size2) 2316 { 2317 /* Offsets need to be 0. */ 2318 if (maybe_ne (offset1, 0) 2319 || maybe_ne (offset2, 0)) 2320 return false; 2321 2322 bool base1_obj_p = SSA_VAR_P (base1); 2323 bool base2_obj_p = SSA_VAR_P (base2); 2324 2325 /* We need one object. */ 2326 if (base1_obj_p == base2_obj_p) 2327 return false; 2328 tree obj = base1_obj_p ? base1 : base2; 2329 2330 /* And we need one MEM_REF. */ 2331 bool base1_memref_p = TREE_CODE (base1) == MEM_REF; 2332 bool base2_memref_p = TREE_CODE (base2) == MEM_REF; 2333 if (base1_memref_p == base2_memref_p) 2334 return false; 2335 tree memref = base1_memref_p ? base1 : base2; 2336 2337 /* Sizes need to be valid. */ 2338 if (!known_size_p (max_size1) 2339 || !known_size_p (max_size2) 2340 || !known_size_p (size1) 2341 || !known_size_p (size2)) 2342 return false; 2343 2344 /* Max_size needs to match size. */ 2345 if (maybe_ne (max_size1, size1) 2346 || maybe_ne (max_size2, size2)) 2347 return false; 2348 2349 /* Sizes need to match. */ 2350 if (maybe_ne (size1, size2)) 2351 return false; 2352 2353 2354 /* Check that memref is a store to pointer with singleton points-to info. */ 2355 if (!integer_zerop (TREE_OPERAND (memref, 1))) 2356 return false; 2357 tree ptr = TREE_OPERAND (memref, 0); 2358 if (TREE_CODE (ptr) != SSA_NAME) 2359 return false; 2360 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr); 2361 unsigned int pt_uid; 2362 if (pi == NULL 2363 || !pt_solution_singleton_or_null_p (&pi->pt, &pt_uid)) 2364 return false; 2365 2366 /* Be conservative with non-call exceptions when the address might 2367 be NULL. */ 2368 if (cfun->can_throw_non_call_exceptions && pi->pt.null) 2369 return false; 2370 2371 /* Check that ptr points relative to obj. */ 2372 unsigned int obj_uid = DECL_PT_UID (obj); 2373 if (obj_uid != pt_uid) 2374 return false; 2375 2376 /* Check that the object size is the same as the store size. That ensures us 2377 that ptr points to the start of obj. */ 2378 return (DECL_SIZE (obj) 2379 && poly_int_tree_p (DECL_SIZE (obj)) 2380 && known_eq (wi::to_poly_offset (DECL_SIZE (obj)), size1)); 2381 } 2382 2383 /* If STMT kills the memory reference REF return true, otherwise 2384 return false. */ 2385 2386 bool 2387 stmt_kills_ref_p (gimple *stmt, ao_ref *ref) 2388 { 2389 if (!ao_ref_base (ref)) 2390 return false; 2391 2392 if (gimple_has_lhs (stmt) 2393 && TREE_CODE (gimple_get_lhs (stmt)) != SSA_NAME 2394 /* The assignment is not necessarily carried out if it can throw 2395 and we can catch it in the current function where we could inspect 2396 the previous value. 2397 ??? We only need to care about the RHS throwing. For aggregate 2398 assignments or similar calls and non-call exceptions the LHS 2399 might throw as well. */ 2400 && !stmt_can_throw_internal (cfun, stmt)) 2401 { 2402 tree lhs = gimple_get_lhs (stmt); 2403 /* If LHS is literally a base of the access we are done. */ 2404 if (ref->ref) 2405 { 2406 tree base = ref->ref; 2407 tree innermost_dropped_array_ref = NULL_TREE; 2408 if (handled_component_p (base)) 2409 { 2410 tree saved_lhs0 = NULL_TREE; 2411 if (handled_component_p (lhs)) 2412 { 2413 saved_lhs0 = TREE_OPERAND (lhs, 0); 2414 TREE_OPERAND (lhs, 0) = integer_zero_node; 2415 } 2416 do 2417 { 2418 /* Just compare the outermost handled component, if 2419 they are equal we have found a possible common 2420 base. */ 2421 tree saved_base0 = TREE_OPERAND (base, 0); 2422 TREE_OPERAND (base, 0) = integer_zero_node; 2423 bool res = operand_equal_p (lhs, base, 0); 2424 TREE_OPERAND (base, 0) = saved_base0; 2425 if (res) 2426 break; 2427 /* Remember if we drop an array-ref that we need to 2428 double-check not being at struct end. */ 2429 if (TREE_CODE (base) == ARRAY_REF 2430 || TREE_CODE (base) == ARRAY_RANGE_REF) 2431 innermost_dropped_array_ref = base; 2432 /* Otherwise drop handled components of the access. */ 2433 base = saved_base0; 2434 } 2435 while (handled_component_p (base)); 2436 if (saved_lhs0) 2437 TREE_OPERAND (lhs, 0) = saved_lhs0; 2438 } 2439 /* Finally check if the lhs has the same address and size as the 2440 base candidate of the access. Watch out if we have dropped 2441 an array-ref that was at struct end, this means ref->ref may 2442 be outside of the TYPE_SIZE of its base. */ 2443 if ((! innermost_dropped_array_ref 2444 || ! array_at_struct_end_p (innermost_dropped_array_ref)) 2445 && (lhs == base 2446 || (((TYPE_SIZE (TREE_TYPE (lhs)) 2447 == TYPE_SIZE (TREE_TYPE (base))) 2448 || (TYPE_SIZE (TREE_TYPE (lhs)) 2449 && TYPE_SIZE (TREE_TYPE (base)) 2450 && operand_equal_p (TYPE_SIZE (TREE_TYPE (lhs)), 2451 TYPE_SIZE (TREE_TYPE (base)), 2452 0))) 2453 && operand_equal_p (lhs, base, 2454 OEP_ADDRESS_OF 2455 | OEP_MATCH_SIDE_EFFECTS)))) 2456 return true; 2457 } 2458 2459 /* Now look for non-literal equal bases with the restriction of 2460 handling constant offset and size. */ 2461 /* For a must-alias check we need to be able to constrain 2462 the access properly. */ 2463 if (!ref->max_size_known_p ()) 2464 return false; 2465 poly_int64 size, offset, max_size, ref_offset = ref->offset; 2466 bool reverse; 2467 tree base = get_ref_base_and_extent (lhs, &offset, &size, &max_size, 2468 &reverse); 2469 /* We can get MEM[symbol: sZ, index: D.8862_1] here, 2470 so base == ref->base does not always hold. */ 2471 if (base != ref->base) 2472 { 2473 /* Try using points-to info. */ 2474 if (same_addr_size_stores_p (base, offset, size, max_size, ref->base, 2475 ref->offset, ref->size, ref->max_size)) 2476 return true; 2477 2478 /* If both base and ref->base are MEM_REFs, only compare the 2479 first operand, and if the second operand isn't equal constant, 2480 try to add the offsets into offset and ref_offset. */ 2481 if (TREE_CODE (base) == MEM_REF && TREE_CODE (ref->base) == MEM_REF 2482 && TREE_OPERAND (base, 0) == TREE_OPERAND (ref->base, 0)) 2483 { 2484 if (!tree_int_cst_equal (TREE_OPERAND (base, 1), 2485 TREE_OPERAND (ref->base, 1))) 2486 { 2487 poly_offset_int off1 = mem_ref_offset (base); 2488 off1 <<= LOG2_BITS_PER_UNIT; 2489 off1 += offset; 2490 poly_offset_int off2 = mem_ref_offset (ref->base); 2491 off2 <<= LOG2_BITS_PER_UNIT; 2492 off2 += ref_offset; 2493 if (!off1.to_shwi (&offset) || !off2.to_shwi (&ref_offset)) 2494 size = -1; 2495 } 2496 } 2497 else 2498 size = -1; 2499 } 2500 /* For a must-alias check we need to be able to constrain 2501 the access properly. */ 2502 if (known_eq (size, max_size) 2503 && known_subrange_p (ref_offset, ref->max_size, offset, size)) 2504 return true; 2505 } 2506 2507 if (is_gimple_call (stmt)) 2508 { 2509 tree callee = gimple_call_fndecl (stmt); 2510 if (callee != NULL_TREE 2511 && gimple_call_builtin_p (stmt, BUILT_IN_NORMAL)) 2512 switch (DECL_FUNCTION_CODE (callee)) 2513 { 2514 case BUILT_IN_FREE: 2515 { 2516 tree ptr = gimple_call_arg (stmt, 0); 2517 tree base = ao_ref_base (ref); 2518 if (base && TREE_CODE (base) == MEM_REF 2519 && TREE_OPERAND (base, 0) == ptr) 2520 return true; 2521 break; 2522 } 2523 2524 case BUILT_IN_MEMCPY: 2525 case BUILT_IN_MEMPCPY: 2526 case BUILT_IN_MEMMOVE: 2527 case BUILT_IN_MEMSET: 2528 case BUILT_IN_MEMCPY_CHK: 2529 case BUILT_IN_MEMPCPY_CHK: 2530 case BUILT_IN_MEMMOVE_CHK: 2531 case BUILT_IN_MEMSET_CHK: 2532 case BUILT_IN_STRNCPY: 2533 case BUILT_IN_STPNCPY: 2534 { 2535 /* For a must-alias check we need to be able to constrain 2536 the access properly. */ 2537 if (!ref->max_size_known_p ()) 2538 return false; 2539 tree dest = gimple_call_arg (stmt, 0); 2540 tree len = gimple_call_arg (stmt, 2); 2541 if (!poly_int_tree_p (len)) 2542 return false; 2543 tree rbase = ref->base; 2544 poly_offset_int roffset = ref->offset; 2545 ao_ref dref; 2546 ao_ref_init_from_ptr_and_size (&dref, dest, len); 2547 tree base = ao_ref_base (&dref); 2548 poly_offset_int offset = dref.offset; 2549 if (!base || !known_size_p (dref.size)) 2550 return false; 2551 if (TREE_CODE (base) == MEM_REF) 2552 { 2553 if (TREE_CODE (rbase) != MEM_REF) 2554 return false; 2555 // Compare pointers. 2556 offset += mem_ref_offset (base) << LOG2_BITS_PER_UNIT; 2557 roffset += mem_ref_offset (rbase) << LOG2_BITS_PER_UNIT; 2558 base = TREE_OPERAND (base, 0); 2559 rbase = TREE_OPERAND (rbase, 0); 2560 } 2561 if (base == rbase 2562 && known_subrange_p (roffset, ref->max_size, offset, 2563 wi::to_poly_offset (len) 2564 << LOG2_BITS_PER_UNIT)) 2565 return true; 2566 break; 2567 } 2568 2569 case BUILT_IN_VA_END: 2570 { 2571 tree ptr = gimple_call_arg (stmt, 0); 2572 if (TREE_CODE (ptr) == ADDR_EXPR) 2573 { 2574 tree base = ao_ref_base (ref); 2575 if (TREE_OPERAND (ptr, 0) == base) 2576 return true; 2577 } 2578 break; 2579 } 2580 2581 default:; 2582 } 2583 } 2584 return false; 2585 } 2586 2587 bool 2588 stmt_kills_ref_p (gimple *stmt, tree ref) 2589 { 2590 ao_ref r; 2591 ao_ref_init (&r, ref); 2592 return stmt_kills_ref_p (stmt, &r); 2593 } 2594 2595 2596 /* Walk the virtual use-def chain of VUSE until hitting the virtual operand 2597 TARGET or a statement clobbering the memory reference REF in which 2598 case false is returned. The walk starts with VUSE, one argument of PHI. */ 2599 2600 static bool 2601 maybe_skip_until (gimple *phi, tree &target, basic_block target_bb, 2602 ao_ref *ref, tree vuse, bool tbaa_p, unsigned int &limit, 2603 bitmap *visited, bool abort_on_visited, 2604 void *(*translate)(ao_ref *, tree, void *, bool *), 2605 void *data) 2606 { 2607 basic_block bb = gimple_bb (phi); 2608 2609 if (!*visited) 2610 *visited = BITMAP_ALLOC (NULL); 2611 2612 bitmap_set_bit (*visited, SSA_NAME_VERSION (PHI_RESULT (phi))); 2613 2614 /* Walk until we hit the target. */ 2615 while (vuse != target) 2616 { 2617 gimple *def_stmt = SSA_NAME_DEF_STMT (vuse); 2618 /* If we are searching for the target VUSE by walking up to 2619 TARGET_BB dominating the original PHI we are finished once 2620 we reach a default def or a definition in a block dominating 2621 that block. Update TARGET and return. */ 2622 if (!target 2623 && (gimple_nop_p (def_stmt) 2624 || dominated_by_p (CDI_DOMINATORS, 2625 target_bb, gimple_bb (def_stmt)))) 2626 { 2627 target = vuse; 2628 return true; 2629 } 2630 2631 /* Recurse for PHI nodes. */ 2632 if (gimple_code (def_stmt) == GIMPLE_PHI) 2633 { 2634 /* An already visited PHI node ends the walk successfully. */ 2635 if (bitmap_bit_p (*visited, SSA_NAME_VERSION (PHI_RESULT (def_stmt)))) 2636 return !abort_on_visited; 2637 vuse = get_continuation_for_phi (def_stmt, ref, tbaa_p, limit, 2638 visited, abort_on_visited, 2639 translate, data); 2640 if (!vuse) 2641 return false; 2642 continue; 2643 } 2644 else if (gimple_nop_p (def_stmt)) 2645 return false; 2646 else 2647 { 2648 /* A clobbering statement or the end of the IL ends it failing. */ 2649 if ((int)limit <= 0) 2650 return false; 2651 --limit; 2652 if (stmt_may_clobber_ref_p_1 (def_stmt, ref, tbaa_p)) 2653 { 2654 bool disambiguate_only = true; 2655 if (translate 2656 && (*translate) (ref, vuse, data, &disambiguate_only) == NULL) 2657 ; 2658 else 2659 return false; 2660 } 2661 } 2662 /* If we reach a new basic-block see if we already skipped it 2663 in a previous walk that ended successfully. */ 2664 if (gimple_bb (def_stmt) != bb) 2665 { 2666 if (!bitmap_set_bit (*visited, SSA_NAME_VERSION (vuse))) 2667 return !abort_on_visited; 2668 bb = gimple_bb (def_stmt); 2669 } 2670 vuse = gimple_vuse (def_stmt); 2671 } 2672 return true; 2673 } 2674 2675 2676 /* Starting from a PHI node for the virtual operand of the memory reference 2677 REF find a continuation virtual operand that allows to continue walking 2678 statements dominating PHI skipping only statements that cannot possibly 2679 clobber REF. Decrements LIMIT for each alias disambiguation done 2680 and aborts the walk, returning NULL_TREE if it reaches zero. 2681 Returns NULL_TREE if no suitable virtual operand can be found. */ 2682 2683 tree 2684 get_continuation_for_phi (gimple *phi, ao_ref *ref, bool tbaa_p, 2685 unsigned int &limit, bitmap *visited, 2686 bool abort_on_visited, 2687 void *(*translate)(ao_ref *, tree, void *, bool *), 2688 void *data) 2689 { 2690 unsigned nargs = gimple_phi_num_args (phi); 2691 2692 /* Through a single-argument PHI we can simply look through. */ 2693 if (nargs == 1) 2694 return PHI_ARG_DEF (phi, 0); 2695 2696 /* For two or more arguments try to pairwise skip non-aliasing code 2697 until we hit the phi argument definition that dominates the other one. */ 2698 basic_block phi_bb = gimple_bb (phi); 2699 tree arg0, arg1; 2700 unsigned i; 2701 2702 /* Find a candidate for the virtual operand which definition 2703 dominates those of all others. */ 2704 /* First look if any of the args themselves satisfy this. */ 2705 for (i = 0; i < nargs; ++i) 2706 { 2707 arg0 = PHI_ARG_DEF (phi, i); 2708 if (SSA_NAME_IS_DEFAULT_DEF (arg0)) 2709 break; 2710 basic_block def_bb = gimple_bb (SSA_NAME_DEF_STMT (arg0)); 2711 if (def_bb != phi_bb 2712 && dominated_by_p (CDI_DOMINATORS, phi_bb, def_bb)) 2713 break; 2714 arg0 = NULL_TREE; 2715 } 2716 /* If not, look if we can reach such candidate by walking defs 2717 until we hit the immediate dominator. maybe_skip_until will 2718 do that for us. */ 2719 basic_block dom = get_immediate_dominator (CDI_DOMINATORS, phi_bb); 2720 2721 /* Then check against the (to be) found candidate. */ 2722 for (i = 0; i < nargs; ++i) 2723 { 2724 arg1 = PHI_ARG_DEF (phi, i); 2725 if (arg1 == arg0) 2726 ; 2727 else if (! maybe_skip_until (phi, arg0, dom, ref, arg1, tbaa_p, 2728 limit, visited, 2729 abort_on_visited, 2730 /* Do not translate when walking over 2731 backedges. */ 2732 dominated_by_p 2733 (CDI_DOMINATORS, 2734 gimple_bb (SSA_NAME_DEF_STMT (arg1)), 2735 phi_bb) 2736 ? NULL : translate, data)) 2737 return NULL_TREE; 2738 } 2739 2740 return arg0; 2741 } 2742 2743 /* Based on the memory reference REF and its virtual use VUSE call 2744 WALKER for each virtual use that is equivalent to VUSE, including VUSE 2745 itself. That is, for each virtual use for which its defining statement 2746 does not clobber REF. 2747 2748 WALKER is called with REF, the current virtual use and DATA. If 2749 WALKER returns non-NULL the walk stops and its result is returned. 2750 At the end of a non-successful walk NULL is returned. 2751 2752 TRANSLATE if non-NULL is called with a pointer to REF, the virtual 2753 use which definition is a statement that may clobber REF and DATA. 2754 If TRANSLATE returns (void *)-1 the walk stops and NULL is returned. 2755 If TRANSLATE returns non-NULL the walk stops and its result is returned. 2756 If TRANSLATE returns NULL the walk continues and TRANSLATE is supposed 2757 to adjust REF and *DATA to make that valid. 2758 2759 VALUEIZE if non-NULL is called with the next VUSE that is considered 2760 and return value is substituted for that. This can be used to 2761 implement optimistic value-numbering for example. Note that the 2762 VUSE argument is assumed to be valueized already. 2763 2764 LIMIT specifies the number of alias queries we are allowed to do, 2765 the walk stops when it reaches zero and NULL is returned. LIMIT 2766 is decremented by the number of alias queries (plus adjustments 2767 done by the callbacks) upon return. 2768 2769 TODO: Cache the vector of equivalent vuses per ref, vuse pair. */ 2770 2771 void * 2772 walk_non_aliased_vuses (ao_ref *ref, tree vuse, bool tbaa_p, 2773 void *(*walker)(ao_ref *, tree, void *), 2774 void *(*translate)(ao_ref *, tree, void *, bool *), 2775 tree (*valueize)(tree), 2776 unsigned &limit, void *data) 2777 { 2778 bitmap visited = NULL; 2779 void *res; 2780 bool translated = false; 2781 2782 timevar_push (TV_ALIAS_STMT_WALK); 2783 2784 do 2785 { 2786 gimple *def_stmt; 2787 2788 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */ 2789 res = (*walker) (ref, vuse, data); 2790 /* Abort walk. */ 2791 if (res == (void *)-1) 2792 { 2793 res = NULL; 2794 break; 2795 } 2796 /* Lookup succeeded. */ 2797 else if (res != NULL) 2798 break; 2799 2800 if (valueize) 2801 { 2802 vuse = valueize (vuse); 2803 if (!vuse) 2804 { 2805 res = NULL; 2806 break; 2807 } 2808 } 2809 def_stmt = SSA_NAME_DEF_STMT (vuse); 2810 if (gimple_nop_p (def_stmt)) 2811 break; 2812 else if (gimple_code (def_stmt) == GIMPLE_PHI) 2813 vuse = get_continuation_for_phi (def_stmt, ref, tbaa_p, limit, 2814 &visited, translated, translate, data); 2815 else 2816 { 2817 if ((int)limit <= 0) 2818 { 2819 res = NULL; 2820 break; 2821 } 2822 --limit; 2823 if (stmt_may_clobber_ref_p_1 (def_stmt, ref, tbaa_p)) 2824 { 2825 if (!translate) 2826 break; 2827 bool disambiguate_only = false; 2828 res = (*translate) (ref, vuse, data, &disambiguate_only); 2829 /* Failed lookup and translation. */ 2830 if (res == (void *)-1) 2831 { 2832 res = NULL; 2833 break; 2834 } 2835 /* Lookup succeeded. */ 2836 else if (res != NULL) 2837 break; 2838 /* Translation succeeded, continue walking. */ 2839 translated = translated || !disambiguate_only; 2840 } 2841 vuse = gimple_vuse (def_stmt); 2842 } 2843 } 2844 while (vuse); 2845 2846 if (visited) 2847 BITMAP_FREE (visited); 2848 2849 timevar_pop (TV_ALIAS_STMT_WALK); 2850 2851 return res; 2852 } 2853 2854 2855 /* Based on the memory reference REF call WALKER for each vdef which 2856 defining statement may clobber REF, starting with VDEF. If REF 2857 is NULL_TREE, each defining statement is visited. 2858 2859 WALKER is called with REF, the current vdef and DATA. If WALKER 2860 returns true the walk is stopped, otherwise it continues. 2861 2862 If function entry is reached, FUNCTION_ENTRY_REACHED is set to true. 2863 The pointer may be NULL and then we do not track this information. 2864 2865 At PHI nodes walk_aliased_vdefs forks into one walk for reach 2866 PHI argument (but only one walk continues on merge points), the 2867 return value is true if any of the walks was successful. 2868 2869 The function returns the number of statements walked or -1 if 2870 LIMIT stmts were walked and the walk was aborted at this point. 2871 If LIMIT is zero the walk is not aborted. */ 2872 2873 static int 2874 walk_aliased_vdefs_1 (ao_ref *ref, tree vdef, 2875 bool (*walker)(ao_ref *, tree, void *), void *data, 2876 bitmap *visited, unsigned int cnt, 2877 bool *function_entry_reached, unsigned limit) 2878 { 2879 do 2880 { 2881 gimple *def_stmt = SSA_NAME_DEF_STMT (vdef); 2882 2883 if (*visited 2884 && !bitmap_set_bit (*visited, SSA_NAME_VERSION (vdef))) 2885 return cnt; 2886 2887 if (gimple_nop_p (def_stmt)) 2888 { 2889 if (function_entry_reached) 2890 *function_entry_reached = true; 2891 return cnt; 2892 } 2893 else if (gimple_code (def_stmt) == GIMPLE_PHI) 2894 { 2895 unsigned i; 2896 if (!*visited) 2897 *visited = BITMAP_ALLOC (NULL); 2898 for (i = 0; i < gimple_phi_num_args (def_stmt); ++i) 2899 { 2900 int res = walk_aliased_vdefs_1 (ref, 2901 gimple_phi_arg_def (def_stmt, i), 2902 walker, data, visited, cnt, 2903 function_entry_reached, limit); 2904 if (res == -1) 2905 return -1; 2906 cnt = res; 2907 } 2908 return cnt; 2909 } 2910 2911 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */ 2912 cnt++; 2913 if (cnt == limit) 2914 return -1; 2915 if ((!ref 2916 || stmt_may_clobber_ref_p_1 (def_stmt, ref)) 2917 && (*walker) (ref, vdef, data)) 2918 return cnt; 2919 2920 vdef = gimple_vuse (def_stmt); 2921 } 2922 while (1); 2923 } 2924 2925 int 2926 walk_aliased_vdefs (ao_ref *ref, tree vdef, 2927 bool (*walker)(ao_ref *, tree, void *), void *data, 2928 bitmap *visited, 2929 bool *function_entry_reached, unsigned int limit) 2930 { 2931 bitmap local_visited = NULL; 2932 int ret; 2933 2934 timevar_push (TV_ALIAS_STMT_WALK); 2935 2936 if (function_entry_reached) 2937 *function_entry_reached = false; 2938 2939 ret = walk_aliased_vdefs_1 (ref, vdef, walker, data, 2940 visited ? visited : &local_visited, 0, 2941 function_entry_reached, limit); 2942 if (local_visited) 2943 BITMAP_FREE (local_visited); 2944 2945 timevar_pop (TV_ALIAS_STMT_WALK); 2946 2947 return ret; 2948 } 2949 2950