1 /* Support routines for Value Range Propagation (VRP). 2 Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011 3 Free Software Foundation, Inc. 4 Contributed by Diego Novillo <dnovillo@redhat.com>. 5 6 This file is part of GCC. 7 8 GCC is free software; you can redistribute it and/or modify 9 it under the terms of the GNU General Public License as published by 10 the Free Software Foundation; either version 3, or (at your option) 11 any later version. 12 13 GCC is distributed in the hope that it will be useful, 14 but WITHOUT ANY WARRANTY; without even the implied warranty of 15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 GNU General Public License for more details. 17 18 You should have received a copy of the GNU General Public License 19 along with GCC; see the file COPYING3. If not see 20 <http://www.gnu.org/licenses/>. */ 21 22 #include "config.h" 23 #include "system.h" 24 #include "coretypes.h" 25 #include "tm.h" 26 #include "ggc.h" 27 #include "flags.h" 28 #include "tree.h" 29 #include "basic-block.h" 30 #include "tree-flow.h" 31 #include "tree-pass.h" 32 #include "tree-dump.h" 33 #include "timevar.h" 34 #include "tree-pretty-print.h" 35 #include "gimple-pretty-print.h" 36 #include "diagnostic-core.h" 37 #include "intl.h" 38 #include "cfgloop.h" 39 #include "tree-scalar-evolution.h" 40 #include "tree-ssa-propagate.h" 41 #include "tree-chrec.h" 42 #include "gimple-fold.h" 43 #include "expr.h" 44 #include "optabs.h" 45 46 47 /* Type of value ranges. See value_range_d for a description of these 48 types. */ 49 enum value_range_type { VR_UNDEFINED, VR_RANGE, VR_ANTI_RANGE, VR_VARYING }; 50 51 /* Range of values that can be associated with an SSA_NAME after VRP 52 has executed. */ 53 struct value_range_d 54 { 55 /* Lattice value represented by this range. */ 56 enum value_range_type type; 57 58 /* Minimum and maximum values represented by this range. These 59 values should be interpreted as follows: 60 61 - If TYPE is VR_UNDEFINED or VR_VARYING then MIN and MAX must 62 be NULL. 63 64 - If TYPE == VR_RANGE then MIN holds the minimum value and 65 MAX holds the maximum value of the range [MIN, MAX]. 66 67 - If TYPE == ANTI_RANGE the variable is known to NOT 68 take any values in the range [MIN, MAX]. */ 69 tree min; 70 tree max; 71 72 /* Set of SSA names whose value ranges are equivalent to this one. 73 This set is only valid when TYPE is VR_RANGE or VR_ANTI_RANGE. */ 74 bitmap equiv; 75 }; 76 77 typedef struct value_range_d value_range_t; 78 79 /* Set of SSA names found live during the RPO traversal of the function 80 for still active basic-blocks. */ 81 static sbitmap *live; 82 83 /* Return true if the SSA name NAME is live on the edge E. */ 84 85 static bool 86 live_on_edge (edge e, tree name) 87 { 88 return (live[e->dest->index] 89 && TEST_BIT (live[e->dest->index], SSA_NAME_VERSION (name))); 90 } 91 92 /* Local functions. */ 93 static int compare_values (tree val1, tree val2); 94 static int compare_values_warnv (tree val1, tree val2, bool *); 95 static void vrp_meet (value_range_t *, value_range_t *); 96 static tree vrp_evaluate_conditional_warnv_with_ops (enum tree_code, 97 tree, tree, bool, bool *, 98 bool *); 99 100 /* Location information for ASSERT_EXPRs. Each instance of this 101 structure describes an ASSERT_EXPR for an SSA name. Since a single 102 SSA name may have more than one assertion associated with it, these 103 locations are kept in a linked list attached to the corresponding 104 SSA name. */ 105 struct assert_locus_d 106 { 107 /* Basic block where the assertion would be inserted. */ 108 basic_block bb; 109 110 /* Some assertions need to be inserted on an edge (e.g., assertions 111 generated by COND_EXPRs). In those cases, BB will be NULL. */ 112 edge e; 113 114 /* Pointer to the statement that generated this assertion. */ 115 gimple_stmt_iterator si; 116 117 /* Predicate code for the ASSERT_EXPR. Must be COMPARISON_CLASS_P. */ 118 enum tree_code comp_code; 119 120 /* Value being compared against. */ 121 tree val; 122 123 /* Expression to compare. */ 124 tree expr; 125 126 /* Next node in the linked list. */ 127 struct assert_locus_d *next; 128 }; 129 130 typedef struct assert_locus_d *assert_locus_t; 131 132 /* If bit I is present, it means that SSA name N_i has a list of 133 assertions that should be inserted in the IL. */ 134 static bitmap need_assert_for; 135 136 /* Array of locations lists where to insert assertions. ASSERTS_FOR[I] 137 holds a list of ASSERT_LOCUS_T nodes that describe where 138 ASSERT_EXPRs for SSA name N_I should be inserted. */ 139 static assert_locus_t *asserts_for; 140 141 /* Value range array. After propagation, VR_VALUE[I] holds the range 142 of values that SSA name N_I may take. */ 143 static unsigned num_vr_values; 144 static value_range_t **vr_value; 145 static bool values_propagated; 146 147 /* For a PHI node which sets SSA name N_I, VR_COUNTS[I] holds the 148 number of executable edges we saw the last time we visited the 149 node. */ 150 static int *vr_phi_edge_counts; 151 152 typedef struct { 153 gimple stmt; 154 tree vec; 155 } switch_update; 156 157 static VEC (edge, heap) *to_remove_edges; 158 DEF_VEC_O(switch_update); 159 DEF_VEC_ALLOC_O(switch_update, heap); 160 static VEC (switch_update, heap) *to_update_switch_stmts; 161 162 163 /* Return the maximum value for TYPE. */ 164 165 static inline tree 166 vrp_val_max (const_tree type) 167 { 168 if (!INTEGRAL_TYPE_P (type)) 169 return NULL_TREE; 170 171 return TYPE_MAX_VALUE (type); 172 } 173 174 /* Return the minimum value for TYPE. */ 175 176 static inline tree 177 vrp_val_min (const_tree type) 178 { 179 if (!INTEGRAL_TYPE_P (type)) 180 return NULL_TREE; 181 182 return TYPE_MIN_VALUE (type); 183 } 184 185 /* Return whether VAL is equal to the maximum value of its type. This 186 will be true for a positive overflow infinity. We can't do a 187 simple equality comparison with TYPE_MAX_VALUE because C typedefs 188 and Ada subtypes can produce types whose TYPE_MAX_VALUE is not == 189 to the integer constant with the same value in the type. */ 190 191 static inline bool 192 vrp_val_is_max (const_tree val) 193 { 194 tree type_max = vrp_val_max (TREE_TYPE (val)); 195 return (val == type_max 196 || (type_max != NULL_TREE 197 && operand_equal_p (val, type_max, 0))); 198 } 199 200 /* Return whether VAL is equal to the minimum value of its type. This 201 will be true for a negative overflow infinity. */ 202 203 static inline bool 204 vrp_val_is_min (const_tree val) 205 { 206 tree type_min = vrp_val_min (TREE_TYPE (val)); 207 return (val == type_min 208 || (type_min != NULL_TREE 209 && operand_equal_p (val, type_min, 0))); 210 } 211 212 213 /* Return whether TYPE should use an overflow infinity distinct from 214 TYPE_{MIN,MAX}_VALUE. We use an overflow infinity value to 215 represent a signed overflow during VRP computations. An infinity 216 is distinct from a half-range, which will go from some number to 217 TYPE_{MIN,MAX}_VALUE. */ 218 219 static inline bool 220 needs_overflow_infinity (const_tree type) 221 { 222 return INTEGRAL_TYPE_P (type) && !TYPE_OVERFLOW_WRAPS (type); 223 } 224 225 /* Return whether TYPE can support our overflow infinity 226 representation: we use the TREE_OVERFLOW flag, which only exists 227 for constants. If TYPE doesn't support this, we don't optimize 228 cases which would require signed overflow--we drop them to 229 VARYING. */ 230 231 static inline bool 232 supports_overflow_infinity (const_tree type) 233 { 234 tree min = vrp_val_min (type), max = vrp_val_max (type); 235 #ifdef ENABLE_CHECKING 236 gcc_assert (needs_overflow_infinity (type)); 237 #endif 238 return (min != NULL_TREE 239 && CONSTANT_CLASS_P (min) 240 && max != NULL_TREE 241 && CONSTANT_CLASS_P (max)); 242 } 243 244 /* VAL is the maximum or minimum value of a type. Return a 245 corresponding overflow infinity. */ 246 247 static inline tree 248 make_overflow_infinity (tree val) 249 { 250 gcc_checking_assert (val != NULL_TREE && CONSTANT_CLASS_P (val)); 251 val = copy_node (val); 252 TREE_OVERFLOW (val) = 1; 253 return val; 254 } 255 256 /* Return a negative overflow infinity for TYPE. */ 257 258 static inline tree 259 negative_overflow_infinity (tree type) 260 { 261 gcc_checking_assert (supports_overflow_infinity (type)); 262 return make_overflow_infinity (vrp_val_min (type)); 263 } 264 265 /* Return a positive overflow infinity for TYPE. */ 266 267 static inline tree 268 positive_overflow_infinity (tree type) 269 { 270 gcc_checking_assert (supports_overflow_infinity (type)); 271 return make_overflow_infinity (vrp_val_max (type)); 272 } 273 274 /* Return whether VAL is a negative overflow infinity. */ 275 276 static inline bool 277 is_negative_overflow_infinity (const_tree val) 278 { 279 return (needs_overflow_infinity (TREE_TYPE (val)) 280 && CONSTANT_CLASS_P (val) 281 && TREE_OVERFLOW (val) 282 && vrp_val_is_min (val)); 283 } 284 285 /* Return whether VAL is a positive overflow infinity. */ 286 287 static inline bool 288 is_positive_overflow_infinity (const_tree val) 289 { 290 return (needs_overflow_infinity (TREE_TYPE (val)) 291 && CONSTANT_CLASS_P (val) 292 && TREE_OVERFLOW (val) 293 && vrp_val_is_max (val)); 294 } 295 296 /* Return whether VAL is a positive or negative overflow infinity. */ 297 298 static inline bool 299 is_overflow_infinity (const_tree val) 300 { 301 return (needs_overflow_infinity (TREE_TYPE (val)) 302 && CONSTANT_CLASS_P (val) 303 && TREE_OVERFLOW (val) 304 && (vrp_val_is_min (val) || vrp_val_is_max (val))); 305 } 306 307 /* Return whether STMT has a constant rhs that is_overflow_infinity. */ 308 309 static inline bool 310 stmt_overflow_infinity (gimple stmt) 311 { 312 if (is_gimple_assign (stmt) 313 && get_gimple_rhs_class (gimple_assign_rhs_code (stmt)) == 314 GIMPLE_SINGLE_RHS) 315 return is_overflow_infinity (gimple_assign_rhs1 (stmt)); 316 return false; 317 } 318 319 /* If VAL is now an overflow infinity, return VAL. Otherwise, return 320 the same value with TREE_OVERFLOW clear. This can be used to avoid 321 confusing a regular value with an overflow value. */ 322 323 static inline tree 324 avoid_overflow_infinity (tree val) 325 { 326 if (!is_overflow_infinity (val)) 327 return val; 328 329 if (vrp_val_is_max (val)) 330 return vrp_val_max (TREE_TYPE (val)); 331 else 332 { 333 gcc_checking_assert (vrp_val_is_min (val)); 334 return vrp_val_min (TREE_TYPE (val)); 335 } 336 } 337 338 339 /* Return true if ARG is marked with the nonnull attribute in the 340 current function signature. */ 341 342 static bool 343 nonnull_arg_p (const_tree arg) 344 { 345 tree t, attrs, fntype; 346 unsigned HOST_WIDE_INT arg_num; 347 348 gcc_assert (TREE_CODE (arg) == PARM_DECL && POINTER_TYPE_P (TREE_TYPE (arg))); 349 350 /* The static chain decl is always non null. */ 351 if (arg == cfun->static_chain_decl) 352 return true; 353 354 fntype = TREE_TYPE (current_function_decl); 355 attrs = lookup_attribute ("nonnull", TYPE_ATTRIBUTES (fntype)); 356 357 /* If "nonnull" wasn't specified, we know nothing about the argument. */ 358 if (attrs == NULL_TREE) 359 return false; 360 361 /* If "nonnull" applies to all the arguments, then ARG is non-null. */ 362 if (TREE_VALUE (attrs) == NULL_TREE) 363 return true; 364 365 /* Get the position number for ARG in the function signature. */ 366 for (arg_num = 1, t = DECL_ARGUMENTS (current_function_decl); 367 t; 368 t = DECL_CHAIN (t), arg_num++) 369 { 370 if (t == arg) 371 break; 372 } 373 374 gcc_assert (t == arg); 375 376 /* Now see if ARG_NUM is mentioned in the nonnull list. */ 377 for (t = TREE_VALUE (attrs); t; t = TREE_CHAIN (t)) 378 { 379 if (compare_tree_int (TREE_VALUE (t), arg_num) == 0) 380 return true; 381 } 382 383 return false; 384 } 385 386 387 /* Set value range VR to VR_VARYING. */ 388 389 static inline void 390 set_value_range_to_varying (value_range_t *vr) 391 { 392 vr->type = VR_VARYING; 393 vr->min = vr->max = NULL_TREE; 394 if (vr->equiv) 395 bitmap_clear (vr->equiv); 396 } 397 398 399 /* Set value range VR to {T, MIN, MAX, EQUIV}. */ 400 401 static void 402 set_value_range (value_range_t *vr, enum value_range_type t, tree min, 403 tree max, bitmap equiv) 404 { 405 #if defined ENABLE_CHECKING 406 /* Check the validity of the range. */ 407 if (t == VR_RANGE || t == VR_ANTI_RANGE) 408 { 409 int cmp; 410 411 gcc_assert (min && max); 412 413 if (INTEGRAL_TYPE_P (TREE_TYPE (min)) && t == VR_ANTI_RANGE) 414 gcc_assert (!vrp_val_is_min (min) || !vrp_val_is_max (max)); 415 416 cmp = compare_values (min, max); 417 gcc_assert (cmp == 0 || cmp == -1 || cmp == -2); 418 419 if (needs_overflow_infinity (TREE_TYPE (min))) 420 gcc_assert (!is_overflow_infinity (min) 421 || !is_overflow_infinity (max)); 422 } 423 424 if (t == VR_UNDEFINED || t == VR_VARYING) 425 gcc_assert (min == NULL_TREE && max == NULL_TREE); 426 427 if (t == VR_UNDEFINED || t == VR_VARYING) 428 gcc_assert (equiv == NULL || bitmap_empty_p (equiv)); 429 #endif 430 431 vr->type = t; 432 vr->min = min; 433 vr->max = max; 434 435 /* Since updating the equivalence set involves deep copying the 436 bitmaps, only do it if absolutely necessary. */ 437 if (vr->equiv == NULL 438 && equiv != NULL) 439 vr->equiv = BITMAP_ALLOC (NULL); 440 441 if (equiv != vr->equiv) 442 { 443 if (equiv && !bitmap_empty_p (equiv)) 444 bitmap_copy (vr->equiv, equiv); 445 else 446 bitmap_clear (vr->equiv); 447 } 448 } 449 450 451 /* Set value range VR to the canonical form of {T, MIN, MAX, EQUIV}. 452 This means adjusting T, MIN and MAX representing the case of a 453 wrapping range with MAX < MIN covering [MIN, type_max] U [type_min, MAX] 454 as anti-rage ~[MAX+1, MIN-1]. Likewise for wrapping anti-ranges. 455 In corner cases where MAX+1 or MIN-1 wraps this will fall back 456 to varying. 457 This routine exists to ease canonicalization in the case where we 458 extract ranges from var + CST op limit. */ 459 460 static void 461 set_and_canonicalize_value_range (value_range_t *vr, enum value_range_type t, 462 tree min, tree max, bitmap equiv) 463 { 464 /* Nothing to canonicalize for symbolic or unknown or varying ranges. */ 465 if ((t != VR_RANGE 466 && t != VR_ANTI_RANGE) 467 || TREE_CODE (min) != INTEGER_CST 468 || TREE_CODE (max) != INTEGER_CST) 469 { 470 set_value_range (vr, t, min, max, equiv); 471 return; 472 } 473 474 /* Wrong order for min and max, to swap them and the VR type we need 475 to adjust them. */ 476 if (tree_int_cst_lt (max, min)) 477 { 478 tree one = build_int_cst (TREE_TYPE (min), 1); 479 tree tmp = int_const_binop (PLUS_EXPR, max, one); 480 max = int_const_binop (MINUS_EXPR, min, one); 481 min = tmp; 482 483 /* There's one corner case, if we had [C+1, C] before we now have 484 that again. But this represents an empty value range, so drop 485 to varying in this case. */ 486 if (tree_int_cst_lt (max, min)) 487 { 488 set_value_range_to_varying (vr); 489 return; 490 } 491 492 t = t == VR_RANGE ? VR_ANTI_RANGE : VR_RANGE; 493 } 494 495 /* Anti-ranges that can be represented as ranges should be so. */ 496 if (t == VR_ANTI_RANGE) 497 { 498 bool is_min = vrp_val_is_min (min); 499 bool is_max = vrp_val_is_max (max); 500 501 if (is_min && is_max) 502 { 503 /* We cannot deal with empty ranges, drop to varying. */ 504 set_value_range_to_varying (vr); 505 return; 506 } 507 else if (is_min 508 /* As a special exception preserve non-null ranges. */ 509 && !(TYPE_UNSIGNED (TREE_TYPE (min)) 510 && integer_zerop (max))) 511 { 512 tree one = build_int_cst (TREE_TYPE (max), 1); 513 min = int_const_binop (PLUS_EXPR, max, one); 514 max = vrp_val_max (TREE_TYPE (max)); 515 t = VR_RANGE; 516 } 517 else if (is_max) 518 { 519 tree one = build_int_cst (TREE_TYPE (min), 1); 520 max = int_const_binop (MINUS_EXPR, min, one); 521 min = vrp_val_min (TREE_TYPE (min)); 522 t = VR_RANGE; 523 } 524 } 525 526 set_value_range (vr, t, min, max, equiv); 527 } 528 529 /* Copy value range FROM into value range TO. */ 530 531 static inline void 532 copy_value_range (value_range_t *to, value_range_t *from) 533 { 534 set_value_range (to, from->type, from->min, from->max, from->equiv); 535 } 536 537 /* Set value range VR to a single value. This function is only called 538 with values we get from statements, and exists to clear the 539 TREE_OVERFLOW flag so that we don't think we have an overflow 540 infinity when we shouldn't. */ 541 542 static inline void 543 set_value_range_to_value (value_range_t *vr, tree val, bitmap equiv) 544 { 545 gcc_assert (is_gimple_min_invariant (val)); 546 val = avoid_overflow_infinity (val); 547 set_value_range (vr, VR_RANGE, val, val, equiv); 548 } 549 550 /* Set value range VR to a non-negative range of type TYPE. 551 OVERFLOW_INFINITY indicates whether to use an overflow infinity 552 rather than TYPE_MAX_VALUE; this should be true if we determine 553 that the range is nonnegative based on the assumption that signed 554 overflow does not occur. */ 555 556 static inline void 557 set_value_range_to_nonnegative (value_range_t *vr, tree type, 558 bool overflow_infinity) 559 { 560 tree zero; 561 562 if (overflow_infinity && !supports_overflow_infinity (type)) 563 { 564 set_value_range_to_varying (vr); 565 return; 566 } 567 568 zero = build_int_cst (type, 0); 569 set_value_range (vr, VR_RANGE, zero, 570 (overflow_infinity 571 ? positive_overflow_infinity (type) 572 : TYPE_MAX_VALUE (type)), 573 vr->equiv); 574 } 575 576 /* Set value range VR to a non-NULL range of type TYPE. */ 577 578 static inline void 579 set_value_range_to_nonnull (value_range_t *vr, tree type) 580 { 581 tree zero = build_int_cst (type, 0); 582 set_value_range (vr, VR_ANTI_RANGE, zero, zero, vr->equiv); 583 } 584 585 586 /* Set value range VR to a NULL range of type TYPE. */ 587 588 static inline void 589 set_value_range_to_null (value_range_t *vr, tree type) 590 { 591 set_value_range_to_value (vr, build_int_cst (type, 0), vr->equiv); 592 } 593 594 595 /* Set value range VR to a range of a truthvalue of type TYPE. */ 596 597 static inline void 598 set_value_range_to_truthvalue (value_range_t *vr, tree type) 599 { 600 if (TYPE_PRECISION (type) == 1) 601 set_value_range_to_varying (vr); 602 else 603 set_value_range (vr, VR_RANGE, 604 build_int_cst (type, 0), build_int_cst (type, 1), 605 vr->equiv); 606 } 607 608 609 /* Set value range VR to VR_UNDEFINED. */ 610 611 static inline void 612 set_value_range_to_undefined (value_range_t *vr) 613 { 614 vr->type = VR_UNDEFINED; 615 vr->min = vr->max = NULL_TREE; 616 if (vr->equiv) 617 bitmap_clear (vr->equiv); 618 } 619 620 621 /* If abs (min) < abs (max), set VR to [-max, max], if 622 abs (min) >= abs (max), set VR to [-min, min]. */ 623 624 static void 625 abs_extent_range (value_range_t *vr, tree min, tree max) 626 { 627 int cmp; 628 629 gcc_assert (TREE_CODE (min) == INTEGER_CST); 630 gcc_assert (TREE_CODE (max) == INTEGER_CST); 631 gcc_assert (INTEGRAL_TYPE_P (TREE_TYPE (min))); 632 gcc_assert (!TYPE_UNSIGNED (TREE_TYPE (min))); 633 min = fold_unary (ABS_EXPR, TREE_TYPE (min), min); 634 max = fold_unary (ABS_EXPR, TREE_TYPE (max), max); 635 if (TREE_OVERFLOW (min) || TREE_OVERFLOW (max)) 636 { 637 set_value_range_to_varying (vr); 638 return; 639 } 640 cmp = compare_values (min, max); 641 if (cmp == -1) 642 min = fold_unary (NEGATE_EXPR, TREE_TYPE (min), max); 643 else if (cmp == 0 || cmp == 1) 644 { 645 max = min; 646 min = fold_unary (NEGATE_EXPR, TREE_TYPE (min), min); 647 } 648 else 649 { 650 set_value_range_to_varying (vr); 651 return; 652 } 653 set_and_canonicalize_value_range (vr, VR_RANGE, min, max, NULL); 654 } 655 656 657 /* Return value range information for VAR. 658 659 If we have no values ranges recorded (ie, VRP is not running), then 660 return NULL. Otherwise create an empty range if none existed for VAR. */ 661 662 static value_range_t * 663 get_value_range (const_tree var) 664 { 665 static const struct value_range_d vr_const_varying 666 = { VR_VARYING, NULL_TREE, NULL_TREE, NULL }; 667 value_range_t *vr; 668 tree sym; 669 unsigned ver = SSA_NAME_VERSION (var); 670 671 /* If we have no recorded ranges, then return NULL. */ 672 if (! vr_value) 673 return NULL; 674 675 /* If we query the range for a new SSA name return an unmodifiable VARYING. 676 We should get here at most from the substitute-and-fold stage which 677 will never try to change values. */ 678 if (ver >= num_vr_values) 679 return CONST_CAST (value_range_t *, &vr_const_varying); 680 681 vr = vr_value[ver]; 682 if (vr) 683 return vr; 684 685 /* After propagation finished do not allocate new value-ranges. */ 686 if (values_propagated) 687 return CONST_CAST (value_range_t *, &vr_const_varying); 688 689 /* Create a default value range. */ 690 vr_value[ver] = vr = XCNEW (value_range_t); 691 692 /* Defer allocating the equivalence set. */ 693 vr->equiv = NULL; 694 695 /* If VAR is a default definition of a parameter, the variable can 696 take any value in VAR's type. */ 697 sym = SSA_NAME_VAR (var); 698 if (SSA_NAME_IS_DEFAULT_DEF (var)) 699 { 700 if (TREE_CODE (sym) == PARM_DECL) 701 { 702 /* Try to use the "nonnull" attribute to create ~[0, 0] 703 anti-ranges for pointers. Note that this is only valid with 704 default definitions of PARM_DECLs. */ 705 if (POINTER_TYPE_P (TREE_TYPE (sym)) 706 && nonnull_arg_p (sym)) 707 set_value_range_to_nonnull (vr, TREE_TYPE (sym)); 708 else 709 set_value_range_to_varying (vr); 710 } 711 else if (TREE_CODE (sym) == RESULT_DECL 712 && DECL_BY_REFERENCE (sym)) 713 set_value_range_to_nonnull (vr, TREE_TYPE (sym)); 714 } 715 716 return vr; 717 } 718 719 /* Return true, if VAL1 and VAL2 are equal values for VRP purposes. */ 720 721 static inline bool 722 vrp_operand_equal_p (const_tree val1, const_tree val2) 723 { 724 if (val1 == val2) 725 return true; 726 if (!val1 || !val2 || !operand_equal_p (val1, val2, 0)) 727 return false; 728 if (is_overflow_infinity (val1)) 729 return is_overflow_infinity (val2); 730 return true; 731 } 732 733 /* Return true, if the bitmaps B1 and B2 are equal. */ 734 735 static inline bool 736 vrp_bitmap_equal_p (const_bitmap b1, const_bitmap b2) 737 { 738 return (b1 == b2 739 || ((!b1 || bitmap_empty_p (b1)) 740 && (!b2 || bitmap_empty_p (b2))) 741 || (b1 && b2 742 && bitmap_equal_p (b1, b2))); 743 } 744 745 /* Update the value range and equivalence set for variable VAR to 746 NEW_VR. Return true if NEW_VR is different from VAR's previous 747 value. 748 749 NOTE: This function assumes that NEW_VR is a temporary value range 750 object created for the sole purpose of updating VAR's range. The 751 storage used by the equivalence set from NEW_VR will be freed by 752 this function. Do not call update_value_range when NEW_VR 753 is the range object associated with another SSA name. */ 754 755 static inline bool 756 update_value_range (const_tree var, value_range_t *new_vr) 757 { 758 value_range_t *old_vr; 759 bool is_new; 760 761 /* Update the value range, if necessary. */ 762 old_vr = get_value_range (var); 763 is_new = old_vr->type != new_vr->type 764 || !vrp_operand_equal_p (old_vr->min, new_vr->min) 765 || !vrp_operand_equal_p (old_vr->max, new_vr->max) 766 || !vrp_bitmap_equal_p (old_vr->equiv, new_vr->equiv); 767 768 if (is_new) 769 set_value_range (old_vr, new_vr->type, new_vr->min, new_vr->max, 770 new_vr->equiv); 771 772 BITMAP_FREE (new_vr->equiv); 773 774 return is_new; 775 } 776 777 778 /* Add VAR and VAR's equivalence set to EQUIV. This is the central 779 point where equivalence processing can be turned on/off. */ 780 781 static void 782 add_equivalence (bitmap *equiv, const_tree var) 783 { 784 unsigned ver = SSA_NAME_VERSION (var); 785 value_range_t *vr = vr_value[ver]; 786 787 if (*equiv == NULL) 788 *equiv = BITMAP_ALLOC (NULL); 789 bitmap_set_bit (*equiv, ver); 790 if (vr && vr->equiv) 791 bitmap_ior_into (*equiv, vr->equiv); 792 } 793 794 795 /* Return true if VR is ~[0, 0]. */ 796 797 static inline bool 798 range_is_nonnull (value_range_t *vr) 799 { 800 return vr->type == VR_ANTI_RANGE 801 && integer_zerop (vr->min) 802 && integer_zerop (vr->max); 803 } 804 805 806 /* Return true if VR is [0, 0]. */ 807 808 static inline bool 809 range_is_null (value_range_t *vr) 810 { 811 return vr->type == VR_RANGE 812 && integer_zerop (vr->min) 813 && integer_zerop (vr->max); 814 } 815 816 /* Return true if max and min of VR are INTEGER_CST. It's not necessary 817 a singleton. */ 818 819 static inline bool 820 range_int_cst_p (value_range_t *vr) 821 { 822 return (vr->type == VR_RANGE 823 && TREE_CODE (vr->max) == INTEGER_CST 824 && TREE_CODE (vr->min) == INTEGER_CST 825 && !TREE_OVERFLOW (vr->max) 826 && !TREE_OVERFLOW (vr->min)); 827 } 828 829 /* Return true if VR is a INTEGER_CST singleton. */ 830 831 static inline bool 832 range_int_cst_singleton_p (value_range_t *vr) 833 { 834 return (range_int_cst_p (vr) 835 && tree_int_cst_equal (vr->min, vr->max)); 836 } 837 838 /* Return true if value range VR involves at least one symbol. */ 839 840 static inline bool 841 symbolic_range_p (value_range_t *vr) 842 { 843 return (!is_gimple_min_invariant (vr->min) 844 || !is_gimple_min_invariant (vr->max)); 845 } 846 847 /* Return true if value range VR uses an overflow infinity. */ 848 849 static inline bool 850 overflow_infinity_range_p (value_range_t *vr) 851 { 852 return (vr->type == VR_RANGE 853 && (is_overflow_infinity (vr->min) 854 || is_overflow_infinity (vr->max))); 855 } 856 857 /* Return false if we can not make a valid comparison based on VR; 858 this will be the case if it uses an overflow infinity and overflow 859 is not undefined (i.e., -fno-strict-overflow is in effect). 860 Otherwise return true, and set *STRICT_OVERFLOW_P to true if VR 861 uses an overflow infinity. */ 862 863 static bool 864 usable_range_p (value_range_t *vr, bool *strict_overflow_p) 865 { 866 gcc_assert (vr->type == VR_RANGE); 867 if (is_overflow_infinity (vr->min)) 868 { 869 *strict_overflow_p = true; 870 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (vr->min))) 871 return false; 872 } 873 if (is_overflow_infinity (vr->max)) 874 { 875 *strict_overflow_p = true; 876 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (vr->max))) 877 return false; 878 } 879 return true; 880 } 881 882 883 /* Return true if the result of assignment STMT is know to be non-negative. 884 If the return value is based on the assumption that signed overflow is 885 undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't change 886 *STRICT_OVERFLOW_P.*/ 887 888 static bool 889 gimple_assign_nonnegative_warnv_p (gimple stmt, bool *strict_overflow_p) 890 { 891 enum tree_code code = gimple_assign_rhs_code (stmt); 892 switch (get_gimple_rhs_class (code)) 893 { 894 case GIMPLE_UNARY_RHS: 895 return tree_unary_nonnegative_warnv_p (gimple_assign_rhs_code (stmt), 896 gimple_expr_type (stmt), 897 gimple_assign_rhs1 (stmt), 898 strict_overflow_p); 899 case GIMPLE_BINARY_RHS: 900 return tree_binary_nonnegative_warnv_p (gimple_assign_rhs_code (stmt), 901 gimple_expr_type (stmt), 902 gimple_assign_rhs1 (stmt), 903 gimple_assign_rhs2 (stmt), 904 strict_overflow_p); 905 case GIMPLE_TERNARY_RHS: 906 return false; 907 case GIMPLE_SINGLE_RHS: 908 return tree_single_nonnegative_warnv_p (gimple_assign_rhs1 (stmt), 909 strict_overflow_p); 910 case GIMPLE_INVALID_RHS: 911 gcc_unreachable (); 912 default: 913 gcc_unreachable (); 914 } 915 } 916 917 /* Return true if return value of call STMT is know to be non-negative. 918 If the return value is based on the assumption that signed overflow is 919 undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't change 920 *STRICT_OVERFLOW_P.*/ 921 922 static bool 923 gimple_call_nonnegative_warnv_p (gimple stmt, bool *strict_overflow_p) 924 { 925 tree arg0 = gimple_call_num_args (stmt) > 0 ? 926 gimple_call_arg (stmt, 0) : NULL_TREE; 927 tree arg1 = gimple_call_num_args (stmt) > 1 ? 928 gimple_call_arg (stmt, 1) : NULL_TREE; 929 930 return tree_call_nonnegative_warnv_p (gimple_expr_type (stmt), 931 gimple_call_fndecl (stmt), 932 arg0, 933 arg1, 934 strict_overflow_p); 935 } 936 937 /* Return true if STMT is know to to compute a non-negative value. 938 If the return value is based on the assumption that signed overflow is 939 undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't change 940 *STRICT_OVERFLOW_P.*/ 941 942 static bool 943 gimple_stmt_nonnegative_warnv_p (gimple stmt, bool *strict_overflow_p) 944 { 945 switch (gimple_code (stmt)) 946 { 947 case GIMPLE_ASSIGN: 948 return gimple_assign_nonnegative_warnv_p (stmt, strict_overflow_p); 949 case GIMPLE_CALL: 950 return gimple_call_nonnegative_warnv_p (stmt, strict_overflow_p); 951 default: 952 gcc_unreachable (); 953 } 954 } 955 956 /* Return true if the result of assignment STMT is know to be non-zero. 957 If the return value is based on the assumption that signed overflow is 958 undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't change 959 *STRICT_OVERFLOW_P.*/ 960 961 static bool 962 gimple_assign_nonzero_warnv_p (gimple stmt, bool *strict_overflow_p) 963 { 964 enum tree_code code = gimple_assign_rhs_code (stmt); 965 switch (get_gimple_rhs_class (code)) 966 { 967 case GIMPLE_UNARY_RHS: 968 return tree_unary_nonzero_warnv_p (gimple_assign_rhs_code (stmt), 969 gimple_expr_type (stmt), 970 gimple_assign_rhs1 (stmt), 971 strict_overflow_p); 972 case GIMPLE_BINARY_RHS: 973 return tree_binary_nonzero_warnv_p (gimple_assign_rhs_code (stmt), 974 gimple_expr_type (stmt), 975 gimple_assign_rhs1 (stmt), 976 gimple_assign_rhs2 (stmt), 977 strict_overflow_p); 978 case GIMPLE_TERNARY_RHS: 979 return false; 980 case GIMPLE_SINGLE_RHS: 981 return tree_single_nonzero_warnv_p (gimple_assign_rhs1 (stmt), 982 strict_overflow_p); 983 case GIMPLE_INVALID_RHS: 984 gcc_unreachable (); 985 default: 986 gcc_unreachable (); 987 } 988 } 989 990 /* Return true if STMT is know to to compute a non-zero value. 991 If the return value is based on the assumption that signed overflow is 992 undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't change 993 *STRICT_OVERFLOW_P.*/ 994 995 static bool 996 gimple_stmt_nonzero_warnv_p (gimple stmt, bool *strict_overflow_p) 997 { 998 switch (gimple_code (stmt)) 999 { 1000 case GIMPLE_ASSIGN: 1001 return gimple_assign_nonzero_warnv_p (stmt, strict_overflow_p); 1002 case GIMPLE_CALL: 1003 return gimple_alloca_call_p (stmt); 1004 default: 1005 gcc_unreachable (); 1006 } 1007 } 1008 1009 /* Like tree_expr_nonzero_warnv_p, but this function uses value ranges 1010 obtained so far. */ 1011 1012 static bool 1013 vrp_stmt_computes_nonzero (gimple stmt, bool *strict_overflow_p) 1014 { 1015 if (gimple_stmt_nonzero_warnv_p (stmt, strict_overflow_p)) 1016 return true; 1017 1018 /* If we have an expression of the form &X->a, then the expression 1019 is nonnull if X is nonnull. */ 1020 if (is_gimple_assign (stmt) 1021 && gimple_assign_rhs_code (stmt) == ADDR_EXPR) 1022 { 1023 tree expr = gimple_assign_rhs1 (stmt); 1024 tree base = get_base_address (TREE_OPERAND (expr, 0)); 1025 1026 if (base != NULL_TREE 1027 && TREE_CODE (base) == MEM_REF 1028 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME) 1029 { 1030 value_range_t *vr = get_value_range (TREE_OPERAND (base, 0)); 1031 if (range_is_nonnull (vr)) 1032 return true; 1033 } 1034 } 1035 1036 return false; 1037 } 1038 1039 /* Returns true if EXPR is a valid value (as expected by compare_values) -- 1040 a gimple invariant, or SSA_NAME +- CST. */ 1041 1042 static bool 1043 valid_value_p (tree expr) 1044 { 1045 if (TREE_CODE (expr) == SSA_NAME) 1046 return true; 1047 1048 if (TREE_CODE (expr) == PLUS_EXPR 1049 || TREE_CODE (expr) == MINUS_EXPR) 1050 return (TREE_CODE (TREE_OPERAND (expr, 0)) == SSA_NAME 1051 && TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST); 1052 1053 return is_gimple_min_invariant (expr); 1054 } 1055 1056 /* Return 1057 1 if VAL < VAL2 1058 0 if !(VAL < VAL2) 1059 -2 if those are incomparable. */ 1060 static inline int 1061 operand_less_p (tree val, tree val2) 1062 { 1063 /* LT is folded faster than GE and others. Inline the common case. */ 1064 if (TREE_CODE (val) == INTEGER_CST && TREE_CODE (val2) == INTEGER_CST) 1065 { 1066 if (TYPE_UNSIGNED (TREE_TYPE (val))) 1067 return INT_CST_LT_UNSIGNED (val, val2); 1068 else 1069 { 1070 if (INT_CST_LT (val, val2)) 1071 return 1; 1072 } 1073 } 1074 else 1075 { 1076 tree tcmp; 1077 1078 fold_defer_overflow_warnings (); 1079 1080 tcmp = fold_binary_to_constant (LT_EXPR, boolean_type_node, val, val2); 1081 1082 fold_undefer_and_ignore_overflow_warnings (); 1083 1084 if (!tcmp 1085 || TREE_CODE (tcmp) != INTEGER_CST) 1086 return -2; 1087 1088 if (!integer_zerop (tcmp)) 1089 return 1; 1090 } 1091 1092 /* val >= val2, not considering overflow infinity. */ 1093 if (is_negative_overflow_infinity (val)) 1094 return is_negative_overflow_infinity (val2) ? 0 : 1; 1095 else if (is_positive_overflow_infinity (val2)) 1096 return is_positive_overflow_infinity (val) ? 0 : 1; 1097 1098 return 0; 1099 } 1100 1101 /* Compare two values VAL1 and VAL2. Return 1102 1103 -2 if VAL1 and VAL2 cannot be compared at compile-time, 1104 -1 if VAL1 < VAL2, 1105 0 if VAL1 == VAL2, 1106 +1 if VAL1 > VAL2, and 1107 +2 if VAL1 != VAL2 1108 1109 This is similar to tree_int_cst_compare but supports pointer values 1110 and values that cannot be compared at compile time. 1111 1112 If STRICT_OVERFLOW_P is not NULL, then set *STRICT_OVERFLOW_P to 1113 true if the return value is only valid if we assume that signed 1114 overflow is undefined. */ 1115 1116 static int 1117 compare_values_warnv (tree val1, tree val2, bool *strict_overflow_p) 1118 { 1119 if (val1 == val2) 1120 return 0; 1121 1122 /* Below we rely on the fact that VAL1 and VAL2 are both pointers or 1123 both integers. */ 1124 gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1)) 1125 == POINTER_TYPE_P (TREE_TYPE (val2))); 1126 /* Convert the two values into the same type. This is needed because 1127 sizetype causes sign extension even for unsigned types. */ 1128 val2 = fold_convert (TREE_TYPE (val1), val2); 1129 STRIP_USELESS_TYPE_CONVERSION (val2); 1130 1131 if ((TREE_CODE (val1) == SSA_NAME 1132 || TREE_CODE (val1) == PLUS_EXPR 1133 || TREE_CODE (val1) == MINUS_EXPR) 1134 && (TREE_CODE (val2) == SSA_NAME 1135 || TREE_CODE (val2) == PLUS_EXPR 1136 || TREE_CODE (val2) == MINUS_EXPR)) 1137 { 1138 tree n1, c1, n2, c2; 1139 enum tree_code code1, code2; 1140 1141 /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME', 1142 return -1 or +1 accordingly. If VAL1 and VAL2 don't use the 1143 same name, return -2. */ 1144 if (TREE_CODE (val1) == SSA_NAME) 1145 { 1146 code1 = SSA_NAME; 1147 n1 = val1; 1148 c1 = NULL_TREE; 1149 } 1150 else 1151 { 1152 code1 = TREE_CODE (val1); 1153 n1 = TREE_OPERAND (val1, 0); 1154 c1 = TREE_OPERAND (val1, 1); 1155 if (tree_int_cst_sgn (c1) == -1) 1156 { 1157 if (is_negative_overflow_infinity (c1)) 1158 return -2; 1159 c1 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c1), c1); 1160 if (!c1) 1161 return -2; 1162 code1 = code1 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR; 1163 } 1164 } 1165 1166 if (TREE_CODE (val2) == SSA_NAME) 1167 { 1168 code2 = SSA_NAME; 1169 n2 = val2; 1170 c2 = NULL_TREE; 1171 } 1172 else 1173 { 1174 code2 = TREE_CODE (val2); 1175 n2 = TREE_OPERAND (val2, 0); 1176 c2 = TREE_OPERAND (val2, 1); 1177 if (tree_int_cst_sgn (c2) == -1) 1178 { 1179 if (is_negative_overflow_infinity (c2)) 1180 return -2; 1181 c2 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c2), c2); 1182 if (!c2) 1183 return -2; 1184 code2 = code2 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR; 1185 } 1186 } 1187 1188 /* Both values must use the same name. */ 1189 if (n1 != n2) 1190 return -2; 1191 1192 if (code1 == SSA_NAME 1193 && code2 == SSA_NAME) 1194 /* NAME == NAME */ 1195 return 0; 1196 1197 /* If overflow is defined we cannot simplify more. */ 1198 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (val1))) 1199 return -2; 1200 1201 if (strict_overflow_p != NULL 1202 && (code1 == SSA_NAME || !TREE_NO_WARNING (val1)) 1203 && (code2 == SSA_NAME || !TREE_NO_WARNING (val2))) 1204 *strict_overflow_p = true; 1205 1206 if (code1 == SSA_NAME) 1207 { 1208 if (code2 == PLUS_EXPR) 1209 /* NAME < NAME + CST */ 1210 return -1; 1211 else if (code2 == MINUS_EXPR) 1212 /* NAME > NAME - CST */ 1213 return 1; 1214 } 1215 else if (code1 == PLUS_EXPR) 1216 { 1217 if (code2 == SSA_NAME) 1218 /* NAME + CST > NAME */ 1219 return 1; 1220 else if (code2 == PLUS_EXPR) 1221 /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */ 1222 return compare_values_warnv (c1, c2, strict_overflow_p); 1223 else if (code2 == MINUS_EXPR) 1224 /* NAME + CST1 > NAME - CST2 */ 1225 return 1; 1226 } 1227 else if (code1 == MINUS_EXPR) 1228 { 1229 if (code2 == SSA_NAME) 1230 /* NAME - CST < NAME */ 1231 return -1; 1232 else if (code2 == PLUS_EXPR) 1233 /* NAME - CST1 < NAME + CST2 */ 1234 return -1; 1235 else if (code2 == MINUS_EXPR) 1236 /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that 1237 C1 and C2 are swapped in the call to compare_values. */ 1238 return compare_values_warnv (c2, c1, strict_overflow_p); 1239 } 1240 1241 gcc_unreachable (); 1242 } 1243 1244 /* We cannot compare non-constants. */ 1245 if (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2)) 1246 return -2; 1247 1248 if (!POINTER_TYPE_P (TREE_TYPE (val1))) 1249 { 1250 /* We cannot compare overflowed values, except for overflow 1251 infinities. */ 1252 if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2)) 1253 { 1254 if (strict_overflow_p != NULL) 1255 *strict_overflow_p = true; 1256 if (is_negative_overflow_infinity (val1)) 1257 return is_negative_overflow_infinity (val2) ? 0 : -1; 1258 else if (is_negative_overflow_infinity (val2)) 1259 return 1; 1260 else if (is_positive_overflow_infinity (val1)) 1261 return is_positive_overflow_infinity (val2) ? 0 : 1; 1262 else if (is_positive_overflow_infinity (val2)) 1263 return -1; 1264 return -2; 1265 } 1266 1267 return tree_int_cst_compare (val1, val2); 1268 } 1269 else 1270 { 1271 tree t; 1272 1273 /* First see if VAL1 and VAL2 are not the same. */ 1274 if (val1 == val2 || operand_equal_p (val1, val2, 0)) 1275 return 0; 1276 1277 /* If VAL1 is a lower address than VAL2, return -1. */ 1278 if (operand_less_p (val1, val2) == 1) 1279 return -1; 1280 1281 /* If VAL1 is a higher address than VAL2, return +1. */ 1282 if (operand_less_p (val2, val1) == 1) 1283 return 1; 1284 1285 /* If VAL1 is different than VAL2, return +2. 1286 For integer constants we either have already returned -1 or 1 1287 or they are equivalent. We still might succeed in proving 1288 something about non-trivial operands. */ 1289 if (TREE_CODE (val1) != INTEGER_CST 1290 || TREE_CODE (val2) != INTEGER_CST) 1291 { 1292 t = fold_binary_to_constant (NE_EXPR, boolean_type_node, val1, val2); 1293 if (t && integer_onep (t)) 1294 return 2; 1295 } 1296 1297 return -2; 1298 } 1299 } 1300 1301 /* Compare values like compare_values_warnv, but treat comparisons of 1302 nonconstants which rely on undefined overflow as incomparable. */ 1303 1304 static int 1305 compare_values (tree val1, tree val2) 1306 { 1307 bool sop; 1308 int ret; 1309 1310 sop = false; 1311 ret = compare_values_warnv (val1, val2, &sop); 1312 if (sop 1313 && (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2))) 1314 ret = -2; 1315 return ret; 1316 } 1317 1318 1319 /* Return 1 if VAL is inside value range MIN <= VAL <= MAX, 1320 0 if VAL is not inside [MIN, MAX], 1321 -2 if we cannot tell either way. 1322 1323 Benchmark compile/20001226-1.c compilation time after changing this 1324 function. */ 1325 1326 static inline int 1327 value_inside_range (tree val, tree min, tree max) 1328 { 1329 int cmp1, cmp2; 1330 1331 cmp1 = operand_less_p (val, min); 1332 if (cmp1 == -2) 1333 return -2; 1334 if (cmp1 == 1) 1335 return 0; 1336 1337 cmp2 = operand_less_p (max, val); 1338 if (cmp2 == -2) 1339 return -2; 1340 1341 return !cmp2; 1342 } 1343 1344 1345 /* Return true if value ranges VR0 and VR1 have a non-empty 1346 intersection. 1347 1348 Benchmark compile/20001226-1.c compilation time after changing this 1349 function. 1350 */ 1351 1352 static inline bool 1353 value_ranges_intersect_p (value_range_t *vr0, value_range_t *vr1) 1354 { 1355 /* The value ranges do not intersect if the maximum of the first range is 1356 less than the minimum of the second range or vice versa. 1357 When those relations are unknown, we can't do any better. */ 1358 if (operand_less_p (vr0->max, vr1->min) != 0) 1359 return false; 1360 if (operand_less_p (vr1->max, vr0->min) != 0) 1361 return false; 1362 return true; 1363 } 1364 1365 1366 /* Return 1 if [MIN, MAX] includes the value zero, 0 if it does not 1367 include the value zero, -2 if we cannot tell. */ 1368 1369 static inline int 1370 range_includes_zero_p (tree min, tree max) 1371 { 1372 tree zero = build_int_cst (TREE_TYPE (min), 0); 1373 return value_inside_range (zero, min, max); 1374 } 1375 1376 /* Return true if *VR is know to only contain nonnegative values. */ 1377 1378 static inline bool 1379 value_range_nonnegative_p (value_range_t *vr) 1380 { 1381 /* Testing for VR_ANTI_RANGE is not useful here as any anti-range 1382 which would return a useful value should be encoded as a 1383 VR_RANGE. */ 1384 if (vr->type == VR_RANGE) 1385 { 1386 int result = compare_values (vr->min, integer_zero_node); 1387 return (result == 0 || result == 1); 1388 } 1389 1390 return false; 1391 } 1392 1393 /* Return true if T, an SSA_NAME, is known to be nonnegative. Return 1394 false otherwise or if no value range information is available. */ 1395 1396 bool 1397 ssa_name_nonnegative_p (const_tree t) 1398 { 1399 value_range_t *vr = get_value_range (t); 1400 1401 if (INTEGRAL_TYPE_P (t) 1402 && TYPE_UNSIGNED (t)) 1403 return true; 1404 1405 if (!vr) 1406 return false; 1407 1408 return value_range_nonnegative_p (vr); 1409 } 1410 1411 /* If *VR has a value rante that is a single constant value return that, 1412 otherwise return NULL_TREE. */ 1413 1414 static tree 1415 value_range_constant_singleton (value_range_t *vr) 1416 { 1417 if (vr->type == VR_RANGE 1418 && operand_equal_p (vr->min, vr->max, 0) 1419 && is_gimple_min_invariant (vr->min)) 1420 return vr->min; 1421 1422 return NULL_TREE; 1423 } 1424 1425 /* If OP has a value range with a single constant value return that, 1426 otherwise return NULL_TREE. This returns OP itself if OP is a 1427 constant. */ 1428 1429 static tree 1430 op_with_constant_singleton_value_range (tree op) 1431 { 1432 if (is_gimple_min_invariant (op)) 1433 return op; 1434 1435 if (TREE_CODE (op) != SSA_NAME) 1436 return NULL_TREE; 1437 1438 return value_range_constant_singleton (get_value_range (op)); 1439 } 1440 1441 /* Return true if op is in a boolean [0, 1] value-range. */ 1442 1443 static bool 1444 op_with_boolean_value_range_p (tree op) 1445 { 1446 value_range_t *vr; 1447 1448 if (TYPE_PRECISION (TREE_TYPE (op)) == 1) 1449 return true; 1450 1451 if (integer_zerop (op) 1452 || integer_onep (op)) 1453 return true; 1454 1455 if (TREE_CODE (op) != SSA_NAME) 1456 return false; 1457 1458 vr = get_value_range (op); 1459 return (vr->type == VR_RANGE 1460 && integer_zerop (vr->min) 1461 && integer_onep (vr->max)); 1462 } 1463 1464 /* Extract value range information from an ASSERT_EXPR EXPR and store 1465 it in *VR_P. */ 1466 1467 static void 1468 extract_range_from_assert (value_range_t *vr_p, tree expr) 1469 { 1470 tree var, cond, limit, min, max, type; 1471 value_range_t *var_vr, *limit_vr; 1472 enum tree_code cond_code; 1473 1474 var = ASSERT_EXPR_VAR (expr); 1475 cond = ASSERT_EXPR_COND (expr); 1476 1477 gcc_assert (COMPARISON_CLASS_P (cond)); 1478 1479 /* Find VAR in the ASSERT_EXPR conditional. */ 1480 if (var == TREE_OPERAND (cond, 0) 1481 || TREE_CODE (TREE_OPERAND (cond, 0)) == PLUS_EXPR 1482 || TREE_CODE (TREE_OPERAND (cond, 0)) == NOP_EXPR) 1483 { 1484 /* If the predicate is of the form VAR COMP LIMIT, then we just 1485 take LIMIT from the RHS and use the same comparison code. */ 1486 cond_code = TREE_CODE (cond); 1487 limit = TREE_OPERAND (cond, 1); 1488 cond = TREE_OPERAND (cond, 0); 1489 } 1490 else 1491 { 1492 /* If the predicate is of the form LIMIT COMP VAR, then we need 1493 to flip around the comparison code to create the proper range 1494 for VAR. */ 1495 cond_code = swap_tree_comparison (TREE_CODE (cond)); 1496 limit = TREE_OPERAND (cond, 0); 1497 cond = TREE_OPERAND (cond, 1); 1498 } 1499 1500 limit = avoid_overflow_infinity (limit); 1501 1502 type = TREE_TYPE (var); 1503 gcc_assert (limit != var); 1504 1505 /* For pointer arithmetic, we only keep track of pointer equality 1506 and inequality. */ 1507 if (POINTER_TYPE_P (type) && cond_code != NE_EXPR && cond_code != EQ_EXPR) 1508 { 1509 set_value_range_to_varying (vr_p); 1510 return; 1511 } 1512 1513 /* If LIMIT is another SSA name and LIMIT has a range of its own, 1514 try to use LIMIT's range to avoid creating symbolic ranges 1515 unnecessarily. */ 1516 limit_vr = (TREE_CODE (limit) == SSA_NAME) ? get_value_range (limit) : NULL; 1517 1518 /* LIMIT's range is only interesting if it has any useful information. */ 1519 if (limit_vr 1520 && (limit_vr->type == VR_UNDEFINED 1521 || limit_vr->type == VR_VARYING 1522 || symbolic_range_p (limit_vr))) 1523 limit_vr = NULL; 1524 1525 /* Initially, the new range has the same set of equivalences of 1526 VAR's range. This will be revised before returning the final 1527 value. Since assertions may be chained via mutually exclusive 1528 predicates, we will need to trim the set of equivalences before 1529 we are done. */ 1530 gcc_assert (vr_p->equiv == NULL); 1531 add_equivalence (&vr_p->equiv, var); 1532 1533 /* Extract a new range based on the asserted comparison for VAR and 1534 LIMIT's value range. Notice that if LIMIT has an anti-range, we 1535 will only use it for equality comparisons (EQ_EXPR). For any 1536 other kind of assertion, we cannot derive a range from LIMIT's 1537 anti-range that can be used to describe the new range. For 1538 instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10], 1539 then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is 1540 no single range for x_2 that could describe LE_EXPR, so we might 1541 as well build the range [b_4, +INF] for it. 1542 One special case we handle is extracting a range from a 1543 range test encoded as (unsigned)var + CST <= limit. */ 1544 if (TREE_CODE (cond) == NOP_EXPR 1545 || TREE_CODE (cond) == PLUS_EXPR) 1546 { 1547 if (TREE_CODE (cond) == PLUS_EXPR) 1548 { 1549 min = fold_build1 (NEGATE_EXPR, TREE_TYPE (TREE_OPERAND (cond, 1)), 1550 TREE_OPERAND (cond, 1)); 1551 max = int_const_binop (PLUS_EXPR, limit, min); 1552 cond = TREE_OPERAND (cond, 0); 1553 } 1554 else 1555 { 1556 min = build_int_cst (TREE_TYPE (var), 0); 1557 max = limit; 1558 } 1559 1560 /* Make sure to not set TREE_OVERFLOW on the final type 1561 conversion. We are willingly interpreting large positive 1562 unsigned values as negative singed values here. */ 1563 min = force_fit_type_double (TREE_TYPE (var), tree_to_double_int (min), 1564 0, false); 1565 max = force_fit_type_double (TREE_TYPE (var), tree_to_double_int (max), 1566 0, false); 1567 1568 /* We can transform a max, min range to an anti-range or 1569 vice-versa. Use set_and_canonicalize_value_range which does 1570 this for us. */ 1571 if (cond_code == LE_EXPR) 1572 set_and_canonicalize_value_range (vr_p, VR_RANGE, 1573 min, max, vr_p->equiv); 1574 else if (cond_code == GT_EXPR) 1575 set_and_canonicalize_value_range (vr_p, VR_ANTI_RANGE, 1576 min, max, vr_p->equiv); 1577 else 1578 gcc_unreachable (); 1579 } 1580 else if (cond_code == EQ_EXPR) 1581 { 1582 enum value_range_type range_type; 1583 1584 if (limit_vr) 1585 { 1586 range_type = limit_vr->type; 1587 min = limit_vr->min; 1588 max = limit_vr->max; 1589 } 1590 else 1591 { 1592 range_type = VR_RANGE; 1593 min = limit; 1594 max = limit; 1595 } 1596 1597 set_value_range (vr_p, range_type, min, max, vr_p->equiv); 1598 1599 /* When asserting the equality VAR == LIMIT and LIMIT is another 1600 SSA name, the new range will also inherit the equivalence set 1601 from LIMIT. */ 1602 if (TREE_CODE (limit) == SSA_NAME) 1603 add_equivalence (&vr_p->equiv, limit); 1604 } 1605 else if (cond_code == NE_EXPR) 1606 { 1607 /* As described above, when LIMIT's range is an anti-range and 1608 this assertion is an inequality (NE_EXPR), then we cannot 1609 derive anything from the anti-range. For instance, if 1610 LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does 1611 not imply that VAR's range is [0, 0]. So, in the case of 1612 anti-ranges, we just assert the inequality using LIMIT and 1613 not its anti-range. 1614 1615 If LIMIT_VR is a range, we can only use it to build a new 1616 anti-range if LIMIT_VR is a single-valued range. For 1617 instance, if LIMIT_VR is [0, 1], the predicate 1618 VAR != [0, 1] does not mean that VAR's range is ~[0, 1]. 1619 Rather, it means that for value 0 VAR should be ~[0, 0] 1620 and for value 1, VAR should be ~[1, 1]. We cannot 1621 represent these ranges. 1622 1623 The only situation in which we can build a valid 1624 anti-range is when LIMIT_VR is a single-valued range 1625 (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case, 1626 build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */ 1627 if (limit_vr 1628 && limit_vr->type == VR_RANGE 1629 && compare_values (limit_vr->min, limit_vr->max) == 0) 1630 { 1631 min = limit_vr->min; 1632 max = limit_vr->max; 1633 } 1634 else 1635 { 1636 /* In any other case, we cannot use LIMIT's range to build a 1637 valid anti-range. */ 1638 min = max = limit; 1639 } 1640 1641 /* If MIN and MAX cover the whole range for their type, then 1642 just use the original LIMIT. */ 1643 if (INTEGRAL_TYPE_P (type) 1644 && vrp_val_is_min (min) 1645 && vrp_val_is_max (max)) 1646 min = max = limit; 1647 1648 set_value_range (vr_p, VR_ANTI_RANGE, min, max, vr_p->equiv); 1649 } 1650 else if (cond_code == LE_EXPR || cond_code == LT_EXPR) 1651 { 1652 min = TYPE_MIN_VALUE (type); 1653 1654 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE) 1655 max = limit; 1656 else 1657 { 1658 /* If LIMIT_VR is of the form [N1, N2], we need to build the 1659 range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for 1660 LT_EXPR. */ 1661 max = limit_vr->max; 1662 } 1663 1664 /* If the maximum value forces us to be out of bounds, simply punt. 1665 It would be pointless to try and do anything more since this 1666 all should be optimized away above us. */ 1667 if ((cond_code == LT_EXPR 1668 && compare_values (max, min) == 0) 1669 || (CONSTANT_CLASS_P (max) && TREE_OVERFLOW (max))) 1670 set_value_range_to_varying (vr_p); 1671 else 1672 { 1673 /* For LT_EXPR, we create the range [MIN, MAX - 1]. */ 1674 if (cond_code == LT_EXPR) 1675 { 1676 if (TYPE_PRECISION (TREE_TYPE (max)) == 1 1677 && !TYPE_UNSIGNED (TREE_TYPE (max))) 1678 max = fold_build2 (PLUS_EXPR, TREE_TYPE (max), max, 1679 build_int_cst (TREE_TYPE (max), -1)); 1680 else 1681 max = fold_build2 (MINUS_EXPR, TREE_TYPE (max), max, 1682 build_int_cst (TREE_TYPE (max), 1)); 1683 if (EXPR_P (max)) 1684 TREE_NO_WARNING (max) = 1; 1685 } 1686 1687 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv); 1688 } 1689 } 1690 else if (cond_code == GE_EXPR || cond_code == GT_EXPR) 1691 { 1692 max = TYPE_MAX_VALUE (type); 1693 1694 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE) 1695 min = limit; 1696 else 1697 { 1698 /* If LIMIT_VR is of the form [N1, N2], we need to build the 1699 range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for 1700 GT_EXPR. */ 1701 min = limit_vr->min; 1702 } 1703 1704 /* If the minimum value forces us to be out of bounds, simply punt. 1705 It would be pointless to try and do anything more since this 1706 all should be optimized away above us. */ 1707 if ((cond_code == GT_EXPR 1708 && compare_values (min, max) == 0) 1709 || (CONSTANT_CLASS_P (min) && TREE_OVERFLOW (min))) 1710 set_value_range_to_varying (vr_p); 1711 else 1712 { 1713 /* For GT_EXPR, we create the range [MIN + 1, MAX]. */ 1714 if (cond_code == GT_EXPR) 1715 { 1716 if (TYPE_PRECISION (TREE_TYPE (min)) == 1 1717 && !TYPE_UNSIGNED (TREE_TYPE (min))) 1718 min = fold_build2 (MINUS_EXPR, TREE_TYPE (min), min, 1719 build_int_cst (TREE_TYPE (min), -1)); 1720 else 1721 min = fold_build2 (PLUS_EXPR, TREE_TYPE (min), min, 1722 build_int_cst (TREE_TYPE (min), 1)); 1723 if (EXPR_P (min)) 1724 TREE_NO_WARNING (min) = 1; 1725 } 1726 1727 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv); 1728 } 1729 } 1730 else 1731 gcc_unreachable (); 1732 1733 /* If VAR already had a known range, it may happen that the new 1734 range we have computed and VAR's range are not compatible. For 1735 instance, 1736 1737 if (p_5 == NULL) 1738 p_6 = ASSERT_EXPR <p_5, p_5 == NULL>; 1739 x_7 = p_6->fld; 1740 p_8 = ASSERT_EXPR <p_6, p_6 != NULL>; 1741 1742 While the above comes from a faulty program, it will cause an ICE 1743 later because p_8 and p_6 will have incompatible ranges and at 1744 the same time will be considered equivalent. A similar situation 1745 would arise from 1746 1747 if (i_5 > 10) 1748 i_6 = ASSERT_EXPR <i_5, i_5 > 10>; 1749 if (i_5 < 5) 1750 i_7 = ASSERT_EXPR <i_6, i_6 < 5>; 1751 1752 Again i_6 and i_7 will have incompatible ranges. It would be 1753 pointless to try and do anything with i_7's range because 1754 anything dominated by 'if (i_5 < 5)' will be optimized away. 1755 Note, due to the wa in which simulation proceeds, the statement 1756 i_7 = ASSERT_EXPR <...> we would never be visited because the 1757 conditional 'if (i_5 < 5)' always evaluates to false. However, 1758 this extra check does not hurt and may protect against future 1759 changes to VRP that may get into a situation similar to the 1760 NULL pointer dereference example. 1761 1762 Note that these compatibility tests are only needed when dealing 1763 with ranges or a mix of range and anti-range. If VAR_VR and VR_P 1764 are both anti-ranges, they will always be compatible, because two 1765 anti-ranges will always have a non-empty intersection. */ 1766 1767 var_vr = get_value_range (var); 1768 1769 /* We may need to make adjustments when VR_P and VAR_VR are numeric 1770 ranges or anti-ranges. */ 1771 if (vr_p->type == VR_VARYING 1772 || vr_p->type == VR_UNDEFINED 1773 || var_vr->type == VR_VARYING 1774 || var_vr->type == VR_UNDEFINED 1775 || symbolic_range_p (vr_p) 1776 || symbolic_range_p (var_vr)) 1777 return; 1778 1779 if (var_vr->type == VR_RANGE && vr_p->type == VR_RANGE) 1780 { 1781 /* If the two ranges have a non-empty intersection, we can 1782 refine the resulting range. Since the assert expression 1783 creates an equivalency and at the same time it asserts a 1784 predicate, we can take the intersection of the two ranges to 1785 get better precision. */ 1786 if (value_ranges_intersect_p (var_vr, vr_p)) 1787 { 1788 /* Use the larger of the two minimums. */ 1789 if (compare_values (vr_p->min, var_vr->min) == -1) 1790 min = var_vr->min; 1791 else 1792 min = vr_p->min; 1793 1794 /* Use the smaller of the two maximums. */ 1795 if (compare_values (vr_p->max, var_vr->max) == 1) 1796 max = var_vr->max; 1797 else 1798 max = vr_p->max; 1799 1800 set_value_range (vr_p, vr_p->type, min, max, vr_p->equiv); 1801 } 1802 else 1803 { 1804 /* The two ranges do not intersect, set the new range to 1805 VARYING, because we will not be able to do anything 1806 meaningful with it. */ 1807 set_value_range_to_varying (vr_p); 1808 } 1809 } 1810 else if ((var_vr->type == VR_RANGE && vr_p->type == VR_ANTI_RANGE) 1811 || (var_vr->type == VR_ANTI_RANGE && vr_p->type == VR_RANGE)) 1812 { 1813 /* A range and an anti-range will cancel each other only if 1814 their ends are the same. For instance, in the example above, 1815 p_8's range ~[0, 0] and p_6's range [0, 0] are incompatible, 1816 so VR_P should be set to VR_VARYING. */ 1817 if (compare_values (var_vr->min, vr_p->min) == 0 1818 && compare_values (var_vr->max, vr_p->max) == 0) 1819 set_value_range_to_varying (vr_p); 1820 else 1821 { 1822 tree min, max, anti_min, anti_max, real_min, real_max; 1823 int cmp; 1824 1825 /* We want to compute the logical AND of the two ranges; 1826 there are three cases to consider. 1827 1828 1829 1. The VR_ANTI_RANGE range is completely within the 1830 VR_RANGE and the endpoints of the ranges are 1831 different. In that case the resulting range 1832 should be whichever range is more precise. 1833 Typically that will be the VR_RANGE. 1834 1835 2. The VR_ANTI_RANGE is completely disjoint from 1836 the VR_RANGE. In this case the resulting range 1837 should be the VR_RANGE. 1838 1839 3. There is some overlap between the VR_ANTI_RANGE 1840 and the VR_RANGE. 1841 1842 3a. If the high limit of the VR_ANTI_RANGE resides 1843 within the VR_RANGE, then the result is a new 1844 VR_RANGE starting at the high limit of the 1845 VR_ANTI_RANGE + 1 and extending to the 1846 high limit of the original VR_RANGE. 1847 1848 3b. If the low limit of the VR_ANTI_RANGE resides 1849 within the VR_RANGE, then the result is a new 1850 VR_RANGE starting at the low limit of the original 1851 VR_RANGE and extending to the low limit of the 1852 VR_ANTI_RANGE - 1. */ 1853 if (vr_p->type == VR_ANTI_RANGE) 1854 { 1855 anti_min = vr_p->min; 1856 anti_max = vr_p->max; 1857 real_min = var_vr->min; 1858 real_max = var_vr->max; 1859 } 1860 else 1861 { 1862 anti_min = var_vr->min; 1863 anti_max = var_vr->max; 1864 real_min = vr_p->min; 1865 real_max = vr_p->max; 1866 } 1867 1868 1869 /* Case 1, VR_ANTI_RANGE completely within VR_RANGE, 1870 not including any endpoints. */ 1871 if (compare_values (anti_max, real_max) == -1 1872 && compare_values (anti_min, real_min) == 1) 1873 { 1874 /* If the range is covering the whole valid range of 1875 the type keep the anti-range. */ 1876 if (!vrp_val_is_min (real_min) 1877 || !vrp_val_is_max (real_max)) 1878 set_value_range (vr_p, VR_RANGE, real_min, 1879 real_max, vr_p->equiv); 1880 } 1881 /* Case 2, VR_ANTI_RANGE completely disjoint from 1882 VR_RANGE. */ 1883 else if (compare_values (anti_min, real_max) == 1 1884 || compare_values (anti_max, real_min) == -1) 1885 { 1886 set_value_range (vr_p, VR_RANGE, real_min, 1887 real_max, vr_p->equiv); 1888 } 1889 /* Case 3a, the anti-range extends into the low 1890 part of the real range. Thus creating a new 1891 low for the real range. */ 1892 else if (((cmp = compare_values (anti_max, real_min)) == 1 1893 || cmp == 0) 1894 && compare_values (anti_max, real_max) == -1) 1895 { 1896 gcc_assert (!is_positive_overflow_infinity (anti_max)); 1897 if (needs_overflow_infinity (TREE_TYPE (anti_max)) 1898 && vrp_val_is_max (anti_max)) 1899 { 1900 if (!supports_overflow_infinity (TREE_TYPE (var_vr->min))) 1901 { 1902 set_value_range_to_varying (vr_p); 1903 return; 1904 } 1905 min = positive_overflow_infinity (TREE_TYPE (var_vr->min)); 1906 } 1907 else if (!POINTER_TYPE_P (TREE_TYPE (var_vr->min))) 1908 { 1909 if (TYPE_PRECISION (TREE_TYPE (var_vr->min)) == 1 1910 && !TYPE_UNSIGNED (TREE_TYPE (var_vr->min))) 1911 min = fold_build2 (MINUS_EXPR, TREE_TYPE (var_vr->min), 1912 anti_max, 1913 build_int_cst (TREE_TYPE (var_vr->min), 1914 -1)); 1915 else 1916 min = fold_build2 (PLUS_EXPR, TREE_TYPE (var_vr->min), 1917 anti_max, 1918 build_int_cst (TREE_TYPE (var_vr->min), 1919 1)); 1920 } 1921 else 1922 min = fold_build_pointer_plus_hwi (anti_max, 1); 1923 max = real_max; 1924 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv); 1925 } 1926 /* Case 3b, the anti-range extends into the high 1927 part of the real range. Thus creating a new 1928 higher for the real range. */ 1929 else if (compare_values (anti_min, real_min) == 1 1930 && ((cmp = compare_values (anti_min, real_max)) == -1 1931 || cmp == 0)) 1932 { 1933 gcc_assert (!is_negative_overflow_infinity (anti_min)); 1934 if (needs_overflow_infinity (TREE_TYPE (anti_min)) 1935 && vrp_val_is_min (anti_min)) 1936 { 1937 if (!supports_overflow_infinity (TREE_TYPE (var_vr->min))) 1938 { 1939 set_value_range_to_varying (vr_p); 1940 return; 1941 } 1942 max = negative_overflow_infinity (TREE_TYPE (var_vr->min)); 1943 } 1944 else if (!POINTER_TYPE_P (TREE_TYPE (var_vr->min))) 1945 { 1946 if (TYPE_PRECISION (TREE_TYPE (var_vr->min)) == 1 1947 && !TYPE_UNSIGNED (TREE_TYPE (var_vr->min))) 1948 max = fold_build2 (PLUS_EXPR, TREE_TYPE (var_vr->min), 1949 anti_min, 1950 build_int_cst (TREE_TYPE (var_vr->min), 1951 -1)); 1952 else 1953 max = fold_build2 (MINUS_EXPR, TREE_TYPE (var_vr->min), 1954 anti_min, 1955 build_int_cst (TREE_TYPE (var_vr->min), 1956 1)); 1957 } 1958 else 1959 max = fold_build_pointer_plus_hwi (anti_min, -1); 1960 min = real_min; 1961 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv); 1962 } 1963 } 1964 } 1965 } 1966 1967 1968 /* Extract range information from SSA name VAR and store it in VR. If 1969 VAR has an interesting range, use it. Otherwise, create the 1970 range [VAR, VAR] and return it. This is useful in situations where 1971 we may have conditionals testing values of VARYING names. For 1972 instance, 1973 1974 x_3 = y_5; 1975 if (x_3 > y_5) 1976 ... 1977 1978 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is 1979 always false. */ 1980 1981 static void 1982 extract_range_from_ssa_name (value_range_t *vr, tree var) 1983 { 1984 value_range_t *var_vr = get_value_range (var); 1985 1986 if (var_vr->type != VR_UNDEFINED && var_vr->type != VR_VARYING) 1987 copy_value_range (vr, var_vr); 1988 else 1989 set_value_range (vr, VR_RANGE, var, var, NULL); 1990 1991 add_equivalence (&vr->equiv, var); 1992 } 1993 1994 1995 /* Wrapper around int_const_binop. If the operation overflows and we 1996 are not using wrapping arithmetic, then adjust the result to be 1997 -INF or +INF depending on CODE, VAL1 and VAL2. This can return 1998 NULL_TREE if we need to use an overflow infinity representation but 1999 the type does not support it. */ 2000 2001 static tree 2002 vrp_int_const_binop (enum tree_code code, tree val1, tree val2) 2003 { 2004 tree res; 2005 2006 res = int_const_binop (code, val1, val2); 2007 2008 /* If we are using unsigned arithmetic, operate symbolically 2009 on -INF and +INF as int_const_binop only handles signed overflow. */ 2010 if (TYPE_UNSIGNED (TREE_TYPE (val1))) 2011 { 2012 int checkz = compare_values (res, val1); 2013 bool overflow = false; 2014 2015 /* Ensure that res = val1 [+*] val2 >= val1 2016 or that res = val1 - val2 <= val1. */ 2017 if ((code == PLUS_EXPR 2018 && !(checkz == 1 || checkz == 0)) 2019 || (code == MINUS_EXPR 2020 && !(checkz == 0 || checkz == -1))) 2021 { 2022 overflow = true; 2023 } 2024 /* Checking for multiplication overflow is done by dividing the 2025 output of the multiplication by the first input of the 2026 multiplication. If the result of that division operation is 2027 not equal to the second input of the multiplication, then the 2028 multiplication overflowed. */ 2029 else if (code == MULT_EXPR && !integer_zerop (val1)) 2030 { 2031 tree tmp = int_const_binop (TRUNC_DIV_EXPR, 2032 res, 2033 val1); 2034 int check = compare_values (tmp, val2); 2035 2036 if (check != 0) 2037 overflow = true; 2038 } 2039 2040 if (overflow) 2041 { 2042 res = copy_node (res); 2043 TREE_OVERFLOW (res) = 1; 2044 } 2045 2046 } 2047 else if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (val1))) 2048 /* If the singed operation wraps then int_const_binop has done 2049 everything we want. */ 2050 ; 2051 else if ((TREE_OVERFLOW (res) 2052 && !TREE_OVERFLOW (val1) 2053 && !TREE_OVERFLOW (val2)) 2054 || is_overflow_infinity (val1) 2055 || is_overflow_infinity (val2)) 2056 { 2057 /* If the operation overflowed but neither VAL1 nor VAL2 are 2058 overflown, return -INF or +INF depending on the operation 2059 and the combination of signs of the operands. */ 2060 int sgn1 = tree_int_cst_sgn (val1); 2061 int sgn2 = tree_int_cst_sgn (val2); 2062 2063 if (needs_overflow_infinity (TREE_TYPE (res)) 2064 && !supports_overflow_infinity (TREE_TYPE (res))) 2065 return NULL_TREE; 2066 2067 /* We have to punt on adding infinities of different signs, 2068 since we can't tell what the sign of the result should be. 2069 Likewise for subtracting infinities of the same sign. */ 2070 if (((code == PLUS_EXPR && sgn1 != sgn2) 2071 || (code == MINUS_EXPR && sgn1 == sgn2)) 2072 && is_overflow_infinity (val1) 2073 && is_overflow_infinity (val2)) 2074 return NULL_TREE; 2075 2076 /* Don't try to handle division or shifting of infinities. */ 2077 if ((code == TRUNC_DIV_EXPR 2078 || code == FLOOR_DIV_EXPR 2079 || code == CEIL_DIV_EXPR 2080 || code == EXACT_DIV_EXPR 2081 || code == ROUND_DIV_EXPR 2082 || code == RSHIFT_EXPR) 2083 && (is_overflow_infinity (val1) 2084 || is_overflow_infinity (val2))) 2085 return NULL_TREE; 2086 2087 /* Notice that we only need to handle the restricted set of 2088 operations handled by extract_range_from_binary_expr. 2089 Among them, only multiplication, addition and subtraction 2090 can yield overflow without overflown operands because we 2091 are working with integral types only... except in the 2092 case VAL1 = -INF and VAL2 = -1 which overflows to +INF 2093 for division too. */ 2094 2095 /* For multiplication, the sign of the overflow is given 2096 by the comparison of the signs of the operands. */ 2097 if ((code == MULT_EXPR && sgn1 == sgn2) 2098 /* For addition, the operands must be of the same sign 2099 to yield an overflow. Its sign is therefore that 2100 of one of the operands, for example the first. For 2101 infinite operands X + -INF is negative, not positive. */ 2102 || (code == PLUS_EXPR 2103 && (sgn1 >= 0 2104 ? !is_negative_overflow_infinity (val2) 2105 : is_positive_overflow_infinity (val2))) 2106 /* For subtraction, non-infinite operands must be of 2107 different signs to yield an overflow. Its sign is 2108 therefore that of the first operand or the opposite of 2109 that of the second operand. A first operand of 0 counts 2110 as positive here, for the corner case 0 - (-INF), which 2111 overflows, but must yield +INF. For infinite operands 0 2112 - INF is negative, not positive. */ 2113 || (code == MINUS_EXPR 2114 && (sgn1 >= 0 2115 ? !is_positive_overflow_infinity (val2) 2116 : is_negative_overflow_infinity (val2))) 2117 /* We only get in here with positive shift count, so the 2118 overflow direction is the same as the sign of val1. 2119 Actually rshift does not overflow at all, but we only 2120 handle the case of shifting overflowed -INF and +INF. */ 2121 || (code == RSHIFT_EXPR 2122 && sgn1 >= 0) 2123 /* For division, the only case is -INF / -1 = +INF. */ 2124 || code == TRUNC_DIV_EXPR 2125 || code == FLOOR_DIV_EXPR 2126 || code == CEIL_DIV_EXPR 2127 || code == EXACT_DIV_EXPR 2128 || code == ROUND_DIV_EXPR) 2129 return (needs_overflow_infinity (TREE_TYPE (res)) 2130 ? positive_overflow_infinity (TREE_TYPE (res)) 2131 : TYPE_MAX_VALUE (TREE_TYPE (res))); 2132 else 2133 return (needs_overflow_infinity (TREE_TYPE (res)) 2134 ? negative_overflow_infinity (TREE_TYPE (res)) 2135 : TYPE_MIN_VALUE (TREE_TYPE (res))); 2136 } 2137 2138 return res; 2139 } 2140 2141 2142 /* For range VR compute two double_int bitmasks. In *MAY_BE_NONZERO 2143 bitmask if some bit is unset, it means for all numbers in the range 2144 the bit is 0, otherwise it might be 0 or 1. In *MUST_BE_NONZERO 2145 bitmask if some bit is set, it means for all numbers in the range 2146 the bit is 1, otherwise it might be 0 or 1. */ 2147 2148 static bool 2149 zero_nonzero_bits_from_vr (value_range_t *vr, 2150 double_int *may_be_nonzero, 2151 double_int *must_be_nonzero) 2152 { 2153 *may_be_nonzero = double_int_minus_one; 2154 *must_be_nonzero = double_int_zero; 2155 if (!range_int_cst_p (vr)) 2156 return false; 2157 2158 if (range_int_cst_singleton_p (vr)) 2159 { 2160 *may_be_nonzero = tree_to_double_int (vr->min); 2161 *must_be_nonzero = *may_be_nonzero; 2162 } 2163 else if (tree_int_cst_sgn (vr->min) >= 0 2164 || tree_int_cst_sgn (vr->max) < 0) 2165 { 2166 double_int dmin = tree_to_double_int (vr->min); 2167 double_int dmax = tree_to_double_int (vr->max); 2168 double_int xor_mask = double_int_xor (dmin, dmax); 2169 *may_be_nonzero = double_int_ior (dmin, dmax); 2170 *must_be_nonzero = double_int_and (dmin, dmax); 2171 if (xor_mask.high != 0) 2172 { 2173 unsigned HOST_WIDE_INT mask 2174 = ((unsigned HOST_WIDE_INT) 1 2175 << floor_log2 (xor_mask.high)) - 1; 2176 may_be_nonzero->low = ALL_ONES; 2177 may_be_nonzero->high |= mask; 2178 must_be_nonzero->low = 0; 2179 must_be_nonzero->high &= ~mask; 2180 } 2181 else if (xor_mask.low != 0) 2182 { 2183 unsigned HOST_WIDE_INT mask 2184 = ((unsigned HOST_WIDE_INT) 1 2185 << floor_log2 (xor_mask.low)) - 1; 2186 may_be_nonzero->low |= mask; 2187 must_be_nonzero->low &= ~mask; 2188 } 2189 } 2190 2191 return true; 2192 } 2193 2194 /* Helper to extract a value-range *VR for a multiplicative operation 2195 *VR0 CODE *VR1. */ 2196 2197 static void 2198 extract_range_from_multiplicative_op_1 (value_range_t *vr, 2199 enum tree_code code, 2200 value_range_t *vr0, value_range_t *vr1) 2201 { 2202 enum value_range_type type; 2203 tree val[4]; 2204 size_t i; 2205 tree min, max; 2206 bool sop; 2207 int cmp; 2208 2209 /* Multiplications, divisions and shifts are a bit tricky to handle, 2210 depending on the mix of signs we have in the two ranges, we 2211 need to operate on different values to get the minimum and 2212 maximum values for the new range. One approach is to figure 2213 out all the variations of range combinations and do the 2214 operations. 2215 2216 However, this involves several calls to compare_values and it 2217 is pretty convoluted. It's simpler to do the 4 operations 2218 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP 2219 MAX1) and then figure the smallest and largest values to form 2220 the new range. */ 2221 gcc_assert (code == MULT_EXPR 2222 || code == TRUNC_DIV_EXPR 2223 || code == FLOOR_DIV_EXPR 2224 || code == CEIL_DIV_EXPR 2225 || code == EXACT_DIV_EXPR 2226 || code == ROUND_DIV_EXPR 2227 || code == RSHIFT_EXPR); 2228 gcc_assert ((vr0->type == VR_RANGE 2229 || (code == MULT_EXPR && vr0->type == VR_ANTI_RANGE)) 2230 && vr0->type == vr1->type); 2231 2232 type = vr0->type; 2233 2234 /* Compute the 4 cross operations. */ 2235 sop = false; 2236 val[0] = vrp_int_const_binop (code, vr0->min, vr1->min); 2237 if (val[0] == NULL_TREE) 2238 sop = true; 2239 2240 if (vr1->max == vr1->min) 2241 val[1] = NULL_TREE; 2242 else 2243 { 2244 val[1] = vrp_int_const_binop (code, vr0->min, vr1->max); 2245 if (val[1] == NULL_TREE) 2246 sop = true; 2247 } 2248 2249 if (vr0->max == vr0->min) 2250 val[2] = NULL_TREE; 2251 else 2252 { 2253 val[2] = vrp_int_const_binop (code, vr0->max, vr1->min); 2254 if (val[2] == NULL_TREE) 2255 sop = true; 2256 } 2257 2258 if (vr0->min == vr0->max || vr1->min == vr1->max) 2259 val[3] = NULL_TREE; 2260 else 2261 { 2262 val[3] = vrp_int_const_binop (code, vr0->max, vr1->max); 2263 if (val[3] == NULL_TREE) 2264 sop = true; 2265 } 2266 2267 if (sop) 2268 { 2269 set_value_range_to_varying (vr); 2270 return; 2271 } 2272 2273 /* Set MIN to the minimum of VAL[i] and MAX to the maximum 2274 of VAL[i]. */ 2275 min = val[0]; 2276 max = val[0]; 2277 for (i = 1; i < 4; i++) 2278 { 2279 if (!is_gimple_min_invariant (min) 2280 || (TREE_OVERFLOW (min) && !is_overflow_infinity (min)) 2281 || !is_gimple_min_invariant (max) 2282 || (TREE_OVERFLOW (max) && !is_overflow_infinity (max))) 2283 break; 2284 2285 if (val[i]) 2286 { 2287 if (!is_gimple_min_invariant (val[i]) 2288 || (TREE_OVERFLOW (val[i]) 2289 && !is_overflow_infinity (val[i]))) 2290 { 2291 /* If we found an overflowed value, set MIN and MAX 2292 to it so that we set the resulting range to 2293 VARYING. */ 2294 min = max = val[i]; 2295 break; 2296 } 2297 2298 if (compare_values (val[i], min) == -1) 2299 min = val[i]; 2300 2301 if (compare_values (val[i], max) == 1) 2302 max = val[i]; 2303 } 2304 } 2305 2306 /* If either MIN or MAX overflowed, then set the resulting range to 2307 VARYING. But we do accept an overflow infinity 2308 representation. */ 2309 if (min == NULL_TREE 2310 || !is_gimple_min_invariant (min) 2311 || (TREE_OVERFLOW (min) && !is_overflow_infinity (min)) 2312 || max == NULL_TREE 2313 || !is_gimple_min_invariant (max) 2314 || (TREE_OVERFLOW (max) && !is_overflow_infinity (max))) 2315 { 2316 set_value_range_to_varying (vr); 2317 return; 2318 } 2319 2320 /* We punt if: 2321 1) [-INF, +INF] 2322 2) [-INF, +-INF(OVF)] 2323 3) [+-INF(OVF), +INF] 2324 4) [+-INF(OVF), +-INF(OVF)] 2325 We learn nothing when we have INF and INF(OVF) on both sides. 2326 Note that we do accept [-INF, -INF] and [+INF, +INF] without 2327 overflow. */ 2328 if ((vrp_val_is_min (min) || is_overflow_infinity (min)) 2329 && (vrp_val_is_max (max) || is_overflow_infinity (max))) 2330 { 2331 set_value_range_to_varying (vr); 2332 return; 2333 } 2334 2335 cmp = compare_values (min, max); 2336 if (cmp == -2 || cmp == 1) 2337 { 2338 /* If the new range has its limits swapped around (MIN > MAX), 2339 then the operation caused one of them to wrap around, mark 2340 the new range VARYING. */ 2341 set_value_range_to_varying (vr); 2342 } 2343 else 2344 set_value_range (vr, type, min, max, NULL); 2345 } 2346 2347 /* Extract range information from a binary operation CODE based on 2348 the ranges of each of its operands, *VR0 and *VR1 with resulting 2349 type EXPR_TYPE. The resulting range is stored in *VR. */ 2350 2351 static void 2352 extract_range_from_binary_expr_1 (value_range_t *vr, 2353 enum tree_code code, tree expr_type, 2354 value_range_t *vr0_, value_range_t *vr1_) 2355 { 2356 value_range_t vr0 = *vr0_, vr1 = *vr1_; 2357 enum value_range_type type; 2358 tree min = NULL_TREE, max = NULL_TREE; 2359 int cmp; 2360 2361 if (!INTEGRAL_TYPE_P (expr_type) 2362 && !POINTER_TYPE_P (expr_type)) 2363 { 2364 set_value_range_to_varying (vr); 2365 return; 2366 } 2367 2368 /* Not all binary expressions can be applied to ranges in a 2369 meaningful way. Handle only arithmetic operations. */ 2370 if (code != PLUS_EXPR 2371 && code != MINUS_EXPR 2372 && code != POINTER_PLUS_EXPR 2373 && code != MULT_EXPR 2374 && code != TRUNC_DIV_EXPR 2375 && code != FLOOR_DIV_EXPR 2376 && code != CEIL_DIV_EXPR 2377 && code != EXACT_DIV_EXPR 2378 && code != ROUND_DIV_EXPR 2379 && code != TRUNC_MOD_EXPR 2380 && code != RSHIFT_EXPR 2381 && code != MIN_EXPR 2382 && code != MAX_EXPR 2383 && code != BIT_AND_EXPR 2384 && code != BIT_IOR_EXPR 2385 && code != BIT_XOR_EXPR) 2386 { 2387 set_value_range_to_varying (vr); 2388 return; 2389 } 2390 2391 /* If both ranges are UNDEFINED, so is the result. */ 2392 if (vr0.type == VR_UNDEFINED && vr1.type == VR_UNDEFINED) 2393 { 2394 set_value_range_to_undefined (vr); 2395 return; 2396 } 2397 /* If one of the ranges is UNDEFINED drop it to VARYING for the following 2398 code. At some point we may want to special-case operations that 2399 have UNDEFINED result for all or some value-ranges of the not UNDEFINED 2400 operand. */ 2401 else if (vr0.type == VR_UNDEFINED) 2402 set_value_range_to_varying (&vr0); 2403 else if (vr1.type == VR_UNDEFINED) 2404 set_value_range_to_varying (&vr1); 2405 2406 /* The type of the resulting value range defaults to VR0.TYPE. */ 2407 type = vr0.type; 2408 2409 /* Refuse to operate on VARYING ranges, ranges of different kinds 2410 and symbolic ranges. As an exception, we allow BIT_AND_EXPR 2411 because we may be able to derive a useful range even if one of 2412 the operands is VR_VARYING or symbolic range. Similarly for 2413 divisions. TODO, we may be able to derive anti-ranges in 2414 some cases. */ 2415 if (code != BIT_AND_EXPR 2416 && code != BIT_IOR_EXPR 2417 && code != TRUNC_DIV_EXPR 2418 && code != FLOOR_DIV_EXPR 2419 && code != CEIL_DIV_EXPR 2420 && code != EXACT_DIV_EXPR 2421 && code != ROUND_DIV_EXPR 2422 && code != TRUNC_MOD_EXPR 2423 && (vr0.type == VR_VARYING 2424 || vr1.type == VR_VARYING 2425 || vr0.type != vr1.type 2426 || symbolic_range_p (&vr0) 2427 || symbolic_range_p (&vr1))) 2428 { 2429 set_value_range_to_varying (vr); 2430 return; 2431 } 2432 2433 /* Now evaluate the expression to determine the new range. */ 2434 if (POINTER_TYPE_P (expr_type)) 2435 { 2436 if (code == MIN_EXPR || code == MAX_EXPR) 2437 { 2438 /* For MIN/MAX expressions with pointers, we only care about 2439 nullness, if both are non null, then the result is nonnull. 2440 If both are null, then the result is null. Otherwise they 2441 are varying. */ 2442 if (range_is_nonnull (&vr0) && range_is_nonnull (&vr1)) 2443 set_value_range_to_nonnull (vr, expr_type); 2444 else if (range_is_null (&vr0) && range_is_null (&vr1)) 2445 set_value_range_to_null (vr, expr_type); 2446 else 2447 set_value_range_to_varying (vr); 2448 } 2449 else if (code == POINTER_PLUS_EXPR) 2450 { 2451 /* For pointer types, we are really only interested in asserting 2452 whether the expression evaluates to non-NULL. */ 2453 if (range_is_nonnull (&vr0) || range_is_nonnull (&vr1)) 2454 set_value_range_to_nonnull (vr, expr_type); 2455 else if (range_is_null (&vr0) && range_is_null (&vr1)) 2456 set_value_range_to_null (vr, expr_type); 2457 else 2458 set_value_range_to_varying (vr); 2459 } 2460 else if (code == BIT_AND_EXPR) 2461 { 2462 /* For pointer types, we are really only interested in asserting 2463 whether the expression evaluates to non-NULL. */ 2464 if (range_is_nonnull (&vr0) && range_is_nonnull (&vr1)) 2465 set_value_range_to_nonnull (vr, expr_type); 2466 else if (range_is_null (&vr0) || range_is_null (&vr1)) 2467 set_value_range_to_null (vr, expr_type); 2468 else 2469 set_value_range_to_varying (vr); 2470 } 2471 else 2472 set_value_range_to_varying (vr); 2473 2474 return; 2475 } 2476 2477 /* For integer ranges, apply the operation to each end of the 2478 range and see what we end up with. */ 2479 if (code == PLUS_EXPR) 2480 { 2481 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to 2482 VR_VARYING. It would take more effort to compute a precise 2483 range for such a case. For example, if we have op0 == 1 and 2484 op1 == -1 with their ranges both being ~[0,0], we would have 2485 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0]. 2486 Note that we are guaranteed to have vr0.type == vr1.type at 2487 this point. */ 2488 if (vr0.type == VR_ANTI_RANGE) 2489 { 2490 set_value_range_to_varying (vr); 2491 return; 2492 } 2493 2494 /* For operations that make the resulting range directly 2495 proportional to the original ranges, apply the operation to 2496 the same end of each range. */ 2497 min = vrp_int_const_binop (code, vr0.min, vr1.min); 2498 max = vrp_int_const_binop (code, vr0.max, vr1.max); 2499 2500 /* If both additions overflowed the range kind is still correct. 2501 This happens regularly with subtracting something in unsigned 2502 arithmetic. 2503 ??? See PR30318 for all the cases we do not handle. */ 2504 if ((TREE_OVERFLOW (min) && !is_overflow_infinity (min)) 2505 && (TREE_OVERFLOW (max) && !is_overflow_infinity (max))) 2506 { 2507 min = build_int_cst_wide (TREE_TYPE (min), 2508 TREE_INT_CST_LOW (min), 2509 TREE_INT_CST_HIGH (min)); 2510 max = build_int_cst_wide (TREE_TYPE (max), 2511 TREE_INT_CST_LOW (max), 2512 TREE_INT_CST_HIGH (max)); 2513 } 2514 } 2515 else if (code == MIN_EXPR 2516 || code == MAX_EXPR) 2517 { 2518 if (vr0.type == VR_ANTI_RANGE) 2519 { 2520 /* For MIN_EXPR and MAX_EXPR with two VR_ANTI_RANGEs, 2521 the resulting VR_ANTI_RANGE is the same - intersection 2522 of the two ranges. */ 2523 min = vrp_int_const_binop (MAX_EXPR, vr0.min, vr1.min); 2524 max = vrp_int_const_binop (MIN_EXPR, vr0.max, vr1.max); 2525 } 2526 else 2527 { 2528 /* For operations that make the resulting range directly 2529 proportional to the original ranges, apply the operation to 2530 the same end of each range. */ 2531 min = vrp_int_const_binop (code, vr0.min, vr1.min); 2532 max = vrp_int_const_binop (code, vr0.max, vr1.max); 2533 } 2534 } 2535 else if (code == MULT_EXPR) 2536 { 2537 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs, 2538 drop to VR_VARYING. It would take more effort to compute a 2539 precise range for such a case. For example, if we have 2540 op0 == 65536 and op1 == 65536 with their ranges both being 2541 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so 2542 we cannot claim that the product is in ~[0,0]. Note that we 2543 are guaranteed to have vr0.type == vr1.type at this 2544 point. */ 2545 if (vr0.type == VR_ANTI_RANGE 2546 && !TYPE_OVERFLOW_UNDEFINED (expr_type)) 2547 { 2548 set_value_range_to_varying (vr); 2549 return; 2550 } 2551 2552 extract_range_from_multiplicative_op_1 (vr, code, &vr0, &vr1); 2553 return; 2554 } 2555 else if (code == RSHIFT_EXPR) 2556 { 2557 /* If we have a RSHIFT_EXPR with any shift values outside [0..prec-1], 2558 then drop to VR_VARYING. Outside of this range we get undefined 2559 behavior from the shift operation. We cannot even trust 2560 SHIFT_COUNT_TRUNCATED at this stage, because that applies to rtl 2561 shifts, and the operation at the tree level may be widened. */ 2562 if (vr1.type != VR_RANGE 2563 || !value_range_nonnegative_p (&vr1) 2564 || TREE_CODE (vr1.max) != INTEGER_CST 2565 || compare_tree_int (vr1.max, TYPE_PRECISION (expr_type) - 1) == 1) 2566 { 2567 set_value_range_to_varying (vr); 2568 return; 2569 } 2570 2571 extract_range_from_multiplicative_op_1 (vr, code, &vr0, &vr1); 2572 return; 2573 } 2574 else if (code == TRUNC_DIV_EXPR 2575 || code == FLOOR_DIV_EXPR 2576 || code == CEIL_DIV_EXPR 2577 || code == EXACT_DIV_EXPR 2578 || code == ROUND_DIV_EXPR) 2579 { 2580 if (vr0.type != VR_RANGE || symbolic_range_p (&vr0)) 2581 { 2582 /* For division, if op1 has VR_RANGE but op0 does not, something 2583 can be deduced just from that range. Say [min, max] / [4, max] 2584 gives [min / 4, max / 4] range. */ 2585 if (vr1.type == VR_RANGE 2586 && !symbolic_range_p (&vr1) 2587 && range_includes_zero_p (vr1.min, vr1.max) == 0) 2588 { 2589 vr0.type = type = VR_RANGE; 2590 vr0.min = vrp_val_min (expr_type); 2591 vr0.max = vrp_val_max (expr_type); 2592 } 2593 else 2594 { 2595 set_value_range_to_varying (vr); 2596 return; 2597 } 2598 } 2599 2600 /* For divisions, if flag_non_call_exceptions is true, we must 2601 not eliminate a division by zero. */ 2602 if (cfun->can_throw_non_call_exceptions 2603 && (vr1.type != VR_RANGE 2604 || range_includes_zero_p (vr1.min, vr1.max) != 0)) 2605 { 2606 set_value_range_to_varying (vr); 2607 return; 2608 } 2609 2610 /* For divisions, if op0 is VR_RANGE, we can deduce a range 2611 even if op1 is VR_VARYING, VR_ANTI_RANGE, symbolic or can 2612 include 0. */ 2613 if (vr0.type == VR_RANGE 2614 && (vr1.type != VR_RANGE 2615 || range_includes_zero_p (vr1.min, vr1.max) != 0)) 2616 { 2617 tree zero = build_int_cst (TREE_TYPE (vr0.min), 0); 2618 int cmp; 2619 2620 min = NULL_TREE; 2621 max = NULL_TREE; 2622 if (TYPE_UNSIGNED (expr_type) 2623 || value_range_nonnegative_p (&vr1)) 2624 { 2625 /* For unsigned division or when divisor is known 2626 to be non-negative, the range has to cover 2627 all numbers from 0 to max for positive max 2628 and all numbers from min to 0 for negative min. */ 2629 cmp = compare_values (vr0.max, zero); 2630 if (cmp == -1) 2631 max = zero; 2632 else if (cmp == 0 || cmp == 1) 2633 max = vr0.max; 2634 else 2635 type = VR_VARYING; 2636 cmp = compare_values (vr0.min, zero); 2637 if (cmp == 1) 2638 min = zero; 2639 else if (cmp == 0 || cmp == -1) 2640 min = vr0.min; 2641 else 2642 type = VR_VARYING; 2643 } 2644 else 2645 { 2646 /* Otherwise the range is -max .. max or min .. -min 2647 depending on which bound is bigger in absolute value, 2648 as the division can change the sign. */ 2649 abs_extent_range (vr, vr0.min, vr0.max); 2650 return; 2651 } 2652 if (type == VR_VARYING) 2653 { 2654 set_value_range_to_varying (vr); 2655 return; 2656 } 2657 } 2658 else 2659 { 2660 extract_range_from_multiplicative_op_1 (vr, code, &vr0, &vr1); 2661 return; 2662 } 2663 } 2664 else if (code == TRUNC_MOD_EXPR) 2665 { 2666 if (vr1.type != VR_RANGE 2667 || range_includes_zero_p (vr1.min, vr1.max) != 0 2668 || vrp_val_is_min (vr1.min)) 2669 { 2670 set_value_range_to_varying (vr); 2671 return; 2672 } 2673 type = VR_RANGE; 2674 /* Compute MAX <|vr1.min|, |vr1.max|> - 1. */ 2675 max = fold_unary_to_constant (ABS_EXPR, expr_type, vr1.min); 2676 if (tree_int_cst_lt (max, vr1.max)) 2677 max = vr1.max; 2678 max = int_const_binop (MINUS_EXPR, max, integer_one_node); 2679 /* If the dividend is non-negative the modulus will be 2680 non-negative as well. */ 2681 if (TYPE_UNSIGNED (expr_type) 2682 || value_range_nonnegative_p (&vr0)) 2683 min = build_int_cst (TREE_TYPE (max), 0); 2684 else 2685 min = fold_unary_to_constant (NEGATE_EXPR, expr_type, max); 2686 } 2687 else if (code == MINUS_EXPR) 2688 { 2689 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to 2690 VR_VARYING. It would take more effort to compute a precise 2691 range for such a case. For example, if we have op0 == 1 and 2692 op1 == 1 with their ranges both being ~[0,0], we would have 2693 op0 - op1 == 0, so we cannot claim that the difference is in 2694 ~[0,0]. Note that we are guaranteed to have 2695 vr0.type == vr1.type at this point. */ 2696 if (vr0.type == VR_ANTI_RANGE) 2697 { 2698 set_value_range_to_varying (vr); 2699 return; 2700 } 2701 2702 /* For MINUS_EXPR, apply the operation to the opposite ends of 2703 each range. */ 2704 min = vrp_int_const_binop (code, vr0.min, vr1.max); 2705 max = vrp_int_const_binop (code, vr0.max, vr1.min); 2706 } 2707 else if (code == BIT_AND_EXPR || code == BIT_IOR_EXPR || code == BIT_XOR_EXPR) 2708 { 2709 bool int_cst_range0, int_cst_range1; 2710 double_int may_be_nonzero0, may_be_nonzero1; 2711 double_int must_be_nonzero0, must_be_nonzero1; 2712 2713 int_cst_range0 = zero_nonzero_bits_from_vr (&vr0, &may_be_nonzero0, 2714 &must_be_nonzero0); 2715 int_cst_range1 = zero_nonzero_bits_from_vr (&vr1, &may_be_nonzero1, 2716 &must_be_nonzero1); 2717 2718 type = VR_RANGE; 2719 if (code == BIT_AND_EXPR) 2720 { 2721 double_int dmax; 2722 min = double_int_to_tree (expr_type, 2723 double_int_and (must_be_nonzero0, 2724 must_be_nonzero1)); 2725 dmax = double_int_and (may_be_nonzero0, may_be_nonzero1); 2726 /* If both input ranges contain only negative values we can 2727 truncate the result range maximum to the minimum of the 2728 input range maxima. */ 2729 if (int_cst_range0 && int_cst_range1 2730 && tree_int_cst_sgn (vr0.max) < 0 2731 && tree_int_cst_sgn (vr1.max) < 0) 2732 { 2733 dmax = double_int_min (dmax, tree_to_double_int (vr0.max), 2734 TYPE_UNSIGNED (expr_type)); 2735 dmax = double_int_min (dmax, tree_to_double_int (vr1.max), 2736 TYPE_UNSIGNED (expr_type)); 2737 } 2738 /* If either input range contains only non-negative values 2739 we can truncate the result range maximum to the respective 2740 maximum of the input range. */ 2741 if (int_cst_range0 && tree_int_cst_sgn (vr0.min) >= 0) 2742 dmax = double_int_min (dmax, tree_to_double_int (vr0.max), 2743 TYPE_UNSIGNED (expr_type)); 2744 if (int_cst_range1 && tree_int_cst_sgn (vr1.min) >= 0) 2745 dmax = double_int_min (dmax, tree_to_double_int (vr1.max), 2746 TYPE_UNSIGNED (expr_type)); 2747 max = double_int_to_tree (expr_type, dmax); 2748 } 2749 else if (code == BIT_IOR_EXPR) 2750 { 2751 double_int dmin; 2752 max = double_int_to_tree (expr_type, 2753 double_int_ior (may_be_nonzero0, 2754 may_be_nonzero1)); 2755 dmin = double_int_ior (must_be_nonzero0, must_be_nonzero1); 2756 /* If the input ranges contain only positive values we can 2757 truncate the minimum of the result range to the maximum 2758 of the input range minima. */ 2759 if (int_cst_range0 && int_cst_range1 2760 && tree_int_cst_sgn (vr0.min) >= 0 2761 && tree_int_cst_sgn (vr1.min) >= 0) 2762 { 2763 dmin = double_int_max (dmin, tree_to_double_int (vr0.min), 2764 TYPE_UNSIGNED (expr_type)); 2765 dmin = double_int_max (dmin, tree_to_double_int (vr1.min), 2766 TYPE_UNSIGNED (expr_type)); 2767 } 2768 /* If either input range contains only negative values 2769 we can truncate the minimum of the result range to the 2770 respective minimum range. */ 2771 if (int_cst_range0 && tree_int_cst_sgn (vr0.max) < 0) 2772 dmin = double_int_max (dmin, tree_to_double_int (vr0.min), 2773 TYPE_UNSIGNED (expr_type)); 2774 if (int_cst_range1 && tree_int_cst_sgn (vr1.max) < 0) 2775 dmin = double_int_max (dmin, tree_to_double_int (vr1.min), 2776 TYPE_UNSIGNED (expr_type)); 2777 min = double_int_to_tree (expr_type, dmin); 2778 } 2779 else if (code == BIT_XOR_EXPR) 2780 { 2781 double_int result_zero_bits, result_one_bits; 2782 result_zero_bits 2783 = double_int_ior (double_int_and (must_be_nonzero0, 2784 must_be_nonzero1), 2785 double_int_not 2786 (double_int_ior (may_be_nonzero0, 2787 may_be_nonzero1))); 2788 result_one_bits 2789 = double_int_ior (double_int_and 2790 (must_be_nonzero0, 2791 double_int_not (may_be_nonzero1)), 2792 double_int_and 2793 (must_be_nonzero1, 2794 double_int_not (may_be_nonzero0))); 2795 max = double_int_to_tree (expr_type, 2796 double_int_not (result_zero_bits)); 2797 min = double_int_to_tree (expr_type, result_one_bits); 2798 /* If the range has all positive or all negative values the 2799 result is better than VARYING. */ 2800 if (tree_int_cst_sgn (min) < 0 2801 || tree_int_cst_sgn (max) >= 0) 2802 ; 2803 else 2804 max = min = NULL_TREE; 2805 } 2806 } 2807 else 2808 gcc_unreachable (); 2809 2810 /* If either MIN or MAX overflowed, then set the resulting range to 2811 VARYING. But we do accept an overflow infinity 2812 representation. */ 2813 if (min == NULL_TREE 2814 || !is_gimple_min_invariant (min) 2815 || (TREE_OVERFLOW (min) && !is_overflow_infinity (min)) 2816 || max == NULL_TREE 2817 || !is_gimple_min_invariant (max) 2818 || (TREE_OVERFLOW (max) && !is_overflow_infinity (max))) 2819 { 2820 set_value_range_to_varying (vr); 2821 return; 2822 } 2823 2824 /* We punt if: 2825 1) [-INF, +INF] 2826 2) [-INF, +-INF(OVF)] 2827 3) [+-INF(OVF), +INF] 2828 4) [+-INF(OVF), +-INF(OVF)] 2829 We learn nothing when we have INF and INF(OVF) on both sides. 2830 Note that we do accept [-INF, -INF] and [+INF, +INF] without 2831 overflow. */ 2832 if ((vrp_val_is_min (min) || is_overflow_infinity (min)) 2833 && (vrp_val_is_max (max) || is_overflow_infinity (max))) 2834 { 2835 set_value_range_to_varying (vr); 2836 return; 2837 } 2838 2839 cmp = compare_values (min, max); 2840 if (cmp == -2 || cmp == 1) 2841 { 2842 /* If the new range has its limits swapped around (MIN > MAX), 2843 then the operation caused one of them to wrap around, mark 2844 the new range VARYING. */ 2845 set_value_range_to_varying (vr); 2846 } 2847 else 2848 set_value_range (vr, type, min, max, NULL); 2849 } 2850 2851 /* Extract range information from a binary expression OP0 CODE OP1 based on 2852 the ranges of each of its operands with resulting type EXPR_TYPE. 2853 The resulting range is stored in *VR. */ 2854 2855 static void 2856 extract_range_from_binary_expr (value_range_t *vr, 2857 enum tree_code code, 2858 tree expr_type, tree op0, tree op1) 2859 { 2860 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; 2861 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; 2862 2863 /* Get value ranges for each operand. For constant operands, create 2864 a new value range with the operand to simplify processing. */ 2865 if (TREE_CODE (op0) == SSA_NAME) 2866 vr0 = *(get_value_range (op0)); 2867 else if (is_gimple_min_invariant (op0)) 2868 set_value_range_to_value (&vr0, op0, NULL); 2869 else 2870 set_value_range_to_varying (&vr0); 2871 2872 if (TREE_CODE (op1) == SSA_NAME) 2873 vr1 = *(get_value_range (op1)); 2874 else if (is_gimple_min_invariant (op1)) 2875 set_value_range_to_value (&vr1, op1, NULL); 2876 else 2877 set_value_range_to_varying (&vr1); 2878 2879 extract_range_from_binary_expr_1 (vr, code, expr_type, &vr0, &vr1); 2880 } 2881 2882 /* Extract range information from a unary operation CODE based on 2883 the range of its operand *VR0 with type OP0_TYPE with resulting type TYPE. 2884 The The resulting range is stored in *VR. */ 2885 2886 static void 2887 extract_range_from_unary_expr_1 (value_range_t *vr, 2888 enum tree_code code, tree type, 2889 value_range_t *vr0_, tree op0_type) 2890 { 2891 value_range_t vr0 = *vr0_; 2892 2893 /* VRP only operates on integral and pointer types. */ 2894 if (!(INTEGRAL_TYPE_P (op0_type) 2895 || POINTER_TYPE_P (op0_type)) 2896 || !(INTEGRAL_TYPE_P (type) 2897 || POINTER_TYPE_P (type))) 2898 { 2899 set_value_range_to_varying (vr); 2900 return; 2901 } 2902 2903 /* If VR0 is UNDEFINED, so is the result. */ 2904 if (vr0.type == VR_UNDEFINED) 2905 { 2906 set_value_range_to_undefined (vr); 2907 return; 2908 } 2909 2910 if (CONVERT_EXPR_CODE_P (code)) 2911 { 2912 tree inner_type = op0_type; 2913 tree outer_type = type; 2914 2915 /* If the expression evaluates to a pointer, we are only interested in 2916 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */ 2917 if (POINTER_TYPE_P (type)) 2918 { 2919 if (range_is_nonnull (&vr0)) 2920 set_value_range_to_nonnull (vr, type); 2921 else if (range_is_null (&vr0)) 2922 set_value_range_to_null (vr, type); 2923 else 2924 set_value_range_to_varying (vr); 2925 return; 2926 } 2927 2928 /* If VR0 is varying and we increase the type precision, assume 2929 a full range for the following transformation. */ 2930 if (vr0.type == VR_VARYING 2931 && INTEGRAL_TYPE_P (inner_type) 2932 && TYPE_PRECISION (inner_type) < TYPE_PRECISION (outer_type)) 2933 { 2934 vr0.type = VR_RANGE; 2935 vr0.min = TYPE_MIN_VALUE (inner_type); 2936 vr0.max = TYPE_MAX_VALUE (inner_type); 2937 } 2938 2939 /* If VR0 is a constant range or anti-range and the conversion is 2940 not truncating we can convert the min and max values and 2941 canonicalize the resulting range. Otherwise we can do the 2942 conversion if the size of the range is less than what the 2943 precision of the target type can represent and the range is 2944 not an anti-range. */ 2945 if ((vr0.type == VR_RANGE 2946 || vr0.type == VR_ANTI_RANGE) 2947 && TREE_CODE (vr0.min) == INTEGER_CST 2948 && TREE_CODE (vr0.max) == INTEGER_CST 2949 && (!is_overflow_infinity (vr0.min) 2950 || (vr0.type == VR_RANGE 2951 && TYPE_PRECISION (outer_type) > TYPE_PRECISION (inner_type) 2952 && needs_overflow_infinity (outer_type) 2953 && supports_overflow_infinity (outer_type))) 2954 && (!is_overflow_infinity (vr0.max) 2955 || (vr0.type == VR_RANGE 2956 && TYPE_PRECISION (outer_type) > TYPE_PRECISION (inner_type) 2957 && needs_overflow_infinity (outer_type) 2958 && supports_overflow_infinity (outer_type))) 2959 && (TYPE_PRECISION (outer_type) >= TYPE_PRECISION (inner_type) 2960 || (vr0.type == VR_RANGE 2961 && integer_zerop (int_const_binop (RSHIFT_EXPR, 2962 int_const_binop (MINUS_EXPR, vr0.max, vr0.min), 2963 size_int (TYPE_PRECISION (outer_type))))))) 2964 { 2965 tree new_min, new_max; 2966 if (is_overflow_infinity (vr0.min)) 2967 new_min = negative_overflow_infinity (outer_type); 2968 else 2969 new_min = force_fit_type_double (outer_type, 2970 tree_to_double_int (vr0.min), 2971 0, false); 2972 if (is_overflow_infinity (vr0.max)) 2973 new_max = positive_overflow_infinity (outer_type); 2974 else 2975 new_max = force_fit_type_double (outer_type, 2976 tree_to_double_int (vr0.max), 2977 0, false); 2978 set_and_canonicalize_value_range (vr, vr0.type, 2979 new_min, new_max, NULL); 2980 return; 2981 } 2982 2983 set_value_range_to_varying (vr); 2984 return; 2985 } 2986 else if (code == NEGATE_EXPR) 2987 { 2988 /* -X is simply 0 - X, so re-use existing code that also handles 2989 anti-ranges fine. */ 2990 value_range_t zero = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; 2991 set_value_range_to_value (&zero, build_int_cst (type, 0), NULL); 2992 extract_range_from_binary_expr_1 (vr, MINUS_EXPR, type, &zero, &vr0); 2993 return; 2994 } 2995 else if (code == ABS_EXPR) 2996 { 2997 tree min, max; 2998 int cmp; 2999 3000 /* Pass through vr0 in the easy cases. */ 3001 if (TYPE_UNSIGNED (type) 3002 || value_range_nonnegative_p (&vr0)) 3003 { 3004 copy_value_range (vr, &vr0); 3005 return; 3006 } 3007 3008 /* For the remaining varying or symbolic ranges we can't do anything 3009 useful. */ 3010 if (vr0.type == VR_VARYING 3011 || symbolic_range_p (&vr0)) 3012 { 3013 set_value_range_to_varying (vr); 3014 return; 3015 } 3016 3017 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a 3018 useful range. */ 3019 if (!TYPE_OVERFLOW_UNDEFINED (type) 3020 && ((vr0.type == VR_RANGE 3021 && vrp_val_is_min (vr0.min)) 3022 || (vr0.type == VR_ANTI_RANGE 3023 && !vrp_val_is_min (vr0.min)))) 3024 { 3025 set_value_range_to_varying (vr); 3026 return; 3027 } 3028 3029 /* ABS_EXPR may flip the range around, if the original range 3030 included negative values. */ 3031 if (is_overflow_infinity (vr0.min)) 3032 min = positive_overflow_infinity (type); 3033 else if (!vrp_val_is_min (vr0.min)) 3034 min = fold_unary_to_constant (code, type, vr0.min); 3035 else if (!needs_overflow_infinity (type)) 3036 min = TYPE_MAX_VALUE (type); 3037 else if (supports_overflow_infinity (type)) 3038 min = positive_overflow_infinity (type); 3039 else 3040 { 3041 set_value_range_to_varying (vr); 3042 return; 3043 } 3044 3045 if (is_overflow_infinity (vr0.max)) 3046 max = positive_overflow_infinity (type); 3047 else if (!vrp_val_is_min (vr0.max)) 3048 max = fold_unary_to_constant (code, type, vr0.max); 3049 else if (!needs_overflow_infinity (type)) 3050 max = TYPE_MAX_VALUE (type); 3051 else if (supports_overflow_infinity (type) 3052 /* We shouldn't generate [+INF, +INF] as set_value_range 3053 doesn't like this and ICEs. */ 3054 && !is_positive_overflow_infinity (min)) 3055 max = positive_overflow_infinity (type); 3056 else 3057 { 3058 set_value_range_to_varying (vr); 3059 return; 3060 } 3061 3062 cmp = compare_values (min, max); 3063 3064 /* If a VR_ANTI_RANGEs contains zero, then we have 3065 ~[-INF, min(MIN, MAX)]. */ 3066 if (vr0.type == VR_ANTI_RANGE) 3067 { 3068 if (range_includes_zero_p (vr0.min, vr0.max) == 1) 3069 { 3070 /* Take the lower of the two values. */ 3071 if (cmp != 1) 3072 max = min; 3073 3074 /* Create ~[-INF, min (abs(MIN), abs(MAX))] 3075 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when 3076 flag_wrapv is set and the original anti-range doesn't include 3077 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */ 3078 if (TYPE_OVERFLOW_WRAPS (type)) 3079 { 3080 tree type_min_value = TYPE_MIN_VALUE (type); 3081 3082 min = (vr0.min != type_min_value 3083 ? int_const_binop (PLUS_EXPR, type_min_value, 3084 integer_one_node) 3085 : type_min_value); 3086 } 3087 else 3088 { 3089 if (overflow_infinity_range_p (&vr0)) 3090 min = negative_overflow_infinity (type); 3091 else 3092 min = TYPE_MIN_VALUE (type); 3093 } 3094 } 3095 else 3096 { 3097 /* All else has failed, so create the range [0, INF], even for 3098 flag_wrapv since TYPE_MIN_VALUE is in the original 3099 anti-range. */ 3100 vr0.type = VR_RANGE; 3101 min = build_int_cst (type, 0); 3102 if (needs_overflow_infinity (type)) 3103 { 3104 if (supports_overflow_infinity (type)) 3105 max = positive_overflow_infinity (type); 3106 else 3107 { 3108 set_value_range_to_varying (vr); 3109 return; 3110 } 3111 } 3112 else 3113 max = TYPE_MAX_VALUE (type); 3114 } 3115 } 3116 3117 /* If the range contains zero then we know that the minimum value in the 3118 range will be zero. */ 3119 else if (range_includes_zero_p (vr0.min, vr0.max) == 1) 3120 { 3121 if (cmp == 1) 3122 max = min; 3123 min = build_int_cst (type, 0); 3124 } 3125 else 3126 { 3127 /* If the range was reversed, swap MIN and MAX. */ 3128 if (cmp == 1) 3129 { 3130 tree t = min; 3131 min = max; 3132 max = t; 3133 } 3134 } 3135 3136 cmp = compare_values (min, max); 3137 if (cmp == -2 || cmp == 1) 3138 { 3139 /* If the new range has its limits swapped around (MIN > MAX), 3140 then the operation caused one of them to wrap around, mark 3141 the new range VARYING. */ 3142 set_value_range_to_varying (vr); 3143 } 3144 else 3145 set_value_range (vr, vr0.type, min, max, NULL); 3146 return; 3147 } 3148 else if (code == BIT_NOT_EXPR) 3149 { 3150 /* ~X is simply -1 - X, so re-use existing code that also handles 3151 anti-ranges fine. */ 3152 value_range_t minusone = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; 3153 set_value_range_to_value (&minusone, build_int_cst (type, -1), NULL); 3154 extract_range_from_binary_expr_1 (vr, MINUS_EXPR, 3155 type, &minusone, &vr0); 3156 return; 3157 } 3158 else if (code == PAREN_EXPR) 3159 { 3160 copy_value_range (vr, &vr0); 3161 return; 3162 } 3163 3164 /* For unhandled operations fall back to varying. */ 3165 set_value_range_to_varying (vr); 3166 return; 3167 } 3168 3169 3170 /* Extract range information from a unary expression CODE OP0 based on 3171 the range of its operand with resulting type TYPE. 3172 The resulting range is stored in *VR. */ 3173 3174 static void 3175 extract_range_from_unary_expr (value_range_t *vr, enum tree_code code, 3176 tree type, tree op0) 3177 { 3178 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; 3179 3180 /* Get value ranges for the operand. For constant operands, create 3181 a new value range with the operand to simplify processing. */ 3182 if (TREE_CODE (op0) == SSA_NAME) 3183 vr0 = *(get_value_range (op0)); 3184 else if (is_gimple_min_invariant (op0)) 3185 set_value_range_to_value (&vr0, op0, NULL); 3186 else 3187 set_value_range_to_varying (&vr0); 3188 3189 extract_range_from_unary_expr_1 (vr, code, type, &vr0, TREE_TYPE (op0)); 3190 } 3191 3192 3193 /* Extract range information from a conditional expression STMT based on 3194 the ranges of each of its operands and the expression code. */ 3195 3196 static void 3197 extract_range_from_cond_expr (value_range_t *vr, gimple stmt) 3198 { 3199 tree op0, op1; 3200 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; 3201 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; 3202 3203 /* Get value ranges for each operand. For constant operands, create 3204 a new value range with the operand to simplify processing. */ 3205 op0 = gimple_assign_rhs2 (stmt); 3206 if (TREE_CODE (op0) == SSA_NAME) 3207 vr0 = *(get_value_range (op0)); 3208 else if (is_gimple_min_invariant (op0)) 3209 set_value_range_to_value (&vr0, op0, NULL); 3210 else 3211 set_value_range_to_varying (&vr0); 3212 3213 op1 = gimple_assign_rhs3 (stmt); 3214 if (TREE_CODE (op1) == SSA_NAME) 3215 vr1 = *(get_value_range (op1)); 3216 else if (is_gimple_min_invariant (op1)) 3217 set_value_range_to_value (&vr1, op1, NULL); 3218 else 3219 set_value_range_to_varying (&vr1); 3220 3221 /* The resulting value range is the union of the operand ranges */ 3222 copy_value_range (vr, &vr0); 3223 vrp_meet (vr, &vr1); 3224 } 3225 3226 3227 /* Extract range information from a comparison expression EXPR based 3228 on the range of its operand and the expression code. */ 3229 3230 static void 3231 extract_range_from_comparison (value_range_t *vr, enum tree_code code, 3232 tree type, tree op0, tree op1) 3233 { 3234 bool sop = false; 3235 tree val; 3236 3237 val = vrp_evaluate_conditional_warnv_with_ops (code, op0, op1, false, &sop, 3238 NULL); 3239 3240 /* A disadvantage of using a special infinity as an overflow 3241 representation is that we lose the ability to record overflow 3242 when we don't have an infinity. So we have to ignore a result 3243 which relies on overflow. */ 3244 3245 if (val && !is_overflow_infinity (val) && !sop) 3246 { 3247 /* Since this expression was found on the RHS of an assignment, 3248 its type may be different from _Bool. Convert VAL to EXPR's 3249 type. */ 3250 val = fold_convert (type, val); 3251 if (is_gimple_min_invariant (val)) 3252 set_value_range_to_value (vr, val, vr->equiv); 3253 else 3254 set_value_range (vr, VR_RANGE, val, val, vr->equiv); 3255 } 3256 else 3257 /* The result of a comparison is always true or false. */ 3258 set_value_range_to_truthvalue (vr, type); 3259 } 3260 3261 /* Try to derive a nonnegative or nonzero range out of STMT relying 3262 primarily on generic routines in fold in conjunction with range data. 3263 Store the result in *VR */ 3264 3265 static void 3266 extract_range_basic (value_range_t *vr, gimple stmt) 3267 { 3268 bool sop = false; 3269 tree type = gimple_expr_type (stmt); 3270 3271 if (INTEGRAL_TYPE_P (type) 3272 && gimple_stmt_nonnegative_warnv_p (stmt, &sop)) 3273 set_value_range_to_nonnegative (vr, type, 3274 sop || stmt_overflow_infinity (stmt)); 3275 else if (vrp_stmt_computes_nonzero (stmt, &sop) 3276 && !sop) 3277 set_value_range_to_nonnull (vr, type); 3278 else 3279 set_value_range_to_varying (vr); 3280 } 3281 3282 3283 /* Try to compute a useful range out of assignment STMT and store it 3284 in *VR. */ 3285 3286 static void 3287 extract_range_from_assignment (value_range_t *vr, gimple stmt) 3288 { 3289 enum tree_code code = gimple_assign_rhs_code (stmt); 3290 3291 if (code == ASSERT_EXPR) 3292 extract_range_from_assert (vr, gimple_assign_rhs1 (stmt)); 3293 else if (code == SSA_NAME) 3294 extract_range_from_ssa_name (vr, gimple_assign_rhs1 (stmt)); 3295 else if (TREE_CODE_CLASS (code) == tcc_binary) 3296 extract_range_from_binary_expr (vr, gimple_assign_rhs_code (stmt), 3297 gimple_expr_type (stmt), 3298 gimple_assign_rhs1 (stmt), 3299 gimple_assign_rhs2 (stmt)); 3300 else if (TREE_CODE_CLASS (code) == tcc_unary) 3301 extract_range_from_unary_expr (vr, gimple_assign_rhs_code (stmt), 3302 gimple_expr_type (stmt), 3303 gimple_assign_rhs1 (stmt)); 3304 else if (code == COND_EXPR) 3305 extract_range_from_cond_expr (vr, stmt); 3306 else if (TREE_CODE_CLASS (code) == tcc_comparison) 3307 extract_range_from_comparison (vr, gimple_assign_rhs_code (stmt), 3308 gimple_expr_type (stmt), 3309 gimple_assign_rhs1 (stmt), 3310 gimple_assign_rhs2 (stmt)); 3311 else if (get_gimple_rhs_class (code) == GIMPLE_SINGLE_RHS 3312 && is_gimple_min_invariant (gimple_assign_rhs1 (stmt))) 3313 set_value_range_to_value (vr, gimple_assign_rhs1 (stmt), NULL); 3314 else 3315 set_value_range_to_varying (vr); 3316 3317 if (vr->type == VR_VARYING) 3318 extract_range_basic (vr, stmt); 3319 } 3320 3321 /* Given a range VR, a LOOP and a variable VAR, determine whether it 3322 would be profitable to adjust VR using scalar evolution information 3323 for VAR. If so, update VR with the new limits. */ 3324 3325 static void 3326 adjust_range_with_scev (value_range_t *vr, struct loop *loop, 3327 gimple stmt, tree var) 3328 { 3329 tree init, step, chrec, tmin, tmax, min, max, type, tem; 3330 enum ev_direction dir; 3331 3332 /* TODO. Don't adjust anti-ranges. An anti-range may provide 3333 better opportunities than a regular range, but I'm not sure. */ 3334 if (vr->type == VR_ANTI_RANGE) 3335 return; 3336 3337 chrec = instantiate_parameters (loop, analyze_scalar_evolution (loop, var)); 3338 3339 /* Like in PR19590, scev can return a constant function. */ 3340 if (is_gimple_min_invariant (chrec)) 3341 { 3342 set_value_range_to_value (vr, chrec, vr->equiv); 3343 return; 3344 } 3345 3346 if (TREE_CODE (chrec) != POLYNOMIAL_CHREC) 3347 return; 3348 3349 init = initial_condition_in_loop_num (chrec, loop->num); 3350 tem = op_with_constant_singleton_value_range (init); 3351 if (tem) 3352 init = tem; 3353 step = evolution_part_in_loop_num (chrec, loop->num); 3354 tem = op_with_constant_singleton_value_range (step); 3355 if (tem) 3356 step = tem; 3357 3358 /* If STEP is symbolic, we can't know whether INIT will be the 3359 minimum or maximum value in the range. Also, unless INIT is 3360 a simple expression, compare_values and possibly other functions 3361 in tree-vrp won't be able to handle it. */ 3362 if (step == NULL_TREE 3363 || !is_gimple_min_invariant (step) 3364 || !valid_value_p (init)) 3365 return; 3366 3367 dir = scev_direction (chrec); 3368 if (/* Do not adjust ranges if we do not know whether the iv increases 3369 or decreases, ... */ 3370 dir == EV_DIR_UNKNOWN 3371 /* ... or if it may wrap. */ 3372 || scev_probably_wraps_p (init, step, stmt, get_chrec_loop (chrec), 3373 true)) 3374 return; 3375 3376 /* We use TYPE_MIN_VALUE and TYPE_MAX_VALUE here instead of 3377 negative_overflow_infinity and positive_overflow_infinity, 3378 because we have concluded that the loop probably does not 3379 wrap. */ 3380 3381 type = TREE_TYPE (var); 3382 if (POINTER_TYPE_P (type) || !TYPE_MIN_VALUE (type)) 3383 tmin = lower_bound_in_type (type, type); 3384 else 3385 tmin = TYPE_MIN_VALUE (type); 3386 if (POINTER_TYPE_P (type) || !TYPE_MAX_VALUE (type)) 3387 tmax = upper_bound_in_type (type, type); 3388 else 3389 tmax = TYPE_MAX_VALUE (type); 3390 3391 /* Try to use estimated number of iterations for the loop to constrain the 3392 final value in the evolution. */ 3393 if (TREE_CODE (step) == INTEGER_CST 3394 && is_gimple_val (init) 3395 && (TREE_CODE (init) != SSA_NAME 3396 || get_value_range (init)->type == VR_RANGE)) 3397 { 3398 double_int nit; 3399 3400 if (estimated_loop_iterations (loop, true, &nit)) 3401 { 3402 value_range_t maxvr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; 3403 double_int dtmp; 3404 bool unsigned_p = TYPE_UNSIGNED (TREE_TYPE (step)); 3405 int overflow = 0; 3406 3407 dtmp = double_int_mul_with_sign (tree_to_double_int (step), nit, 3408 unsigned_p, &overflow); 3409 /* If the multiplication overflowed we can't do a meaningful 3410 adjustment. Likewise if the result doesn't fit in the type 3411 of the induction variable. For a signed type we have to 3412 check whether the result has the expected signedness which 3413 is that of the step as number of iterations is unsigned. */ 3414 if (!overflow 3415 && double_int_fits_to_tree_p (TREE_TYPE (init), dtmp) 3416 && (unsigned_p 3417 || ((dtmp.high ^ TREE_INT_CST_HIGH (step)) >= 0))) 3418 { 3419 tem = double_int_to_tree (TREE_TYPE (init), dtmp); 3420 extract_range_from_binary_expr (&maxvr, PLUS_EXPR, 3421 TREE_TYPE (init), init, tem); 3422 /* Likewise if the addition did. */ 3423 if (maxvr.type == VR_RANGE) 3424 { 3425 tmin = maxvr.min; 3426 tmax = maxvr.max; 3427 } 3428 } 3429 } 3430 } 3431 3432 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED) 3433 { 3434 min = tmin; 3435 max = tmax; 3436 3437 /* For VARYING or UNDEFINED ranges, just about anything we get 3438 from scalar evolutions should be better. */ 3439 3440 if (dir == EV_DIR_DECREASES) 3441 max = init; 3442 else 3443 min = init; 3444 3445 /* If we would create an invalid range, then just assume we 3446 know absolutely nothing. This may be over-conservative, 3447 but it's clearly safe, and should happen only in unreachable 3448 parts of code, or for invalid programs. */ 3449 if (compare_values (min, max) == 1) 3450 return; 3451 3452 set_value_range (vr, VR_RANGE, min, max, vr->equiv); 3453 } 3454 else if (vr->type == VR_RANGE) 3455 { 3456 min = vr->min; 3457 max = vr->max; 3458 3459 if (dir == EV_DIR_DECREASES) 3460 { 3461 /* INIT is the maximum value. If INIT is lower than VR->MAX 3462 but no smaller than VR->MIN, set VR->MAX to INIT. */ 3463 if (compare_values (init, max) == -1) 3464 max = init; 3465 3466 /* According to the loop information, the variable does not 3467 overflow. If we think it does, probably because of an 3468 overflow due to arithmetic on a different INF value, 3469 reset now. */ 3470 if (is_negative_overflow_infinity (min) 3471 || compare_values (min, tmin) == -1) 3472 min = tmin; 3473 3474 } 3475 else 3476 { 3477 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */ 3478 if (compare_values (init, min) == 1) 3479 min = init; 3480 3481 if (is_positive_overflow_infinity (max) 3482 || compare_values (tmax, max) == -1) 3483 max = tmax; 3484 } 3485 3486 /* If we just created an invalid range with the minimum 3487 greater than the maximum, we fail conservatively. 3488 This should happen only in unreachable 3489 parts of code, or for invalid programs. */ 3490 if (compare_values (min, max) == 1) 3491 return; 3492 3493 set_value_range (vr, VR_RANGE, min, max, vr->equiv); 3494 } 3495 } 3496 3497 /* Return true if VAR may overflow at STMT. This checks any available 3498 loop information to see if we can determine that VAR does not 3499 overflow. */ 3500 3501 static bool 3502 vrp_var_may_overflow (tree var, gimple stmt) 3503 { 3504 struct loop *l; 3505 tree chrec, init, step; 3506 3507 if (current_loops == NULL) 3508 return true; 3509 3510 l = loop_containing_stmt (stmt); 3511 if (l == NULL 3512 || !loop_outer (l)) 3513 return true; 3514 3515 chrec = instantiate_parameters (l, analyze_scalar_evolution (l, var)); 3516 if (TREE_CODE (chrec) != POLYNOMIAL_CHREC) 3517 return true; 3518 3519 init = initial_condition_in_loop_num (chrec, l->num); 3520 step = evolution_part_in_loop_num (chrec, l->num); 3521 3522 if (step == NULL_TREE 3523 || !is_gimple_min_invariant (step) 3524 || !valid_value_p (init)) 3525 return true; 3526 3527 /* If we get here, we know something useful about VAR based on the 3528 loop information. If it wraps, it may overflow. */ 3529 3530 if (scev_probably_wraps_p (init, step, stmt, get_chrec_loop (chrec), 3531 true)) 3532 return true; 3533 3534 if (dump_file && (dump_flags & TDF_DETAILS) != 0) 3535 { 3536 print_generic_expr (dump_file, var, 0); 3537 fprintf (dump_file, ": loop information indicates does not overflow\n"); 3538 } 3539 3540 return false; 3541 } 3542 3543 3544 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP: 3545 3546 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for 3547 all the values in the ranges. 3548 3549 - Return BOOLEAN_FALSE_NODE if the comparison always returns false. 3550 3551 - Return NULL_TREE if it is not always possible to determine the 3552 value of the comparison. 3553 3554 Also set *STRICT_OVERFLOW_P to indicate whether a range with an 3555 overflow infinity was used in the test. */ 3556 3557 3558 static tree 3559 compare_ranges (enum tree_code comp, value_range_t *vr0, value_range_t *vr1, 3560 bool *strict_overflow_p) 3561 { 3562 /* VARYING or UNDEFINED ranges cannot be compared. */ 3563 if (vr0->type == VR_VARYING 3564 || vr0->type == VR_UNDEFINED 3565 || vr1->type == VR_VARYING 3566 || vr1->type == VR_UNDEFINED) 3567 return NULL_TREE; 3568 3569 /* Anti-ranges need to be handled separately. */ 3570 if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE) 3571 { 3572 /* If both are anti-ranges, then we cannot compute any 3573 comparison. */ 3574 if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE) 3575 return NULL_TREE; 3576 3577 /* These comparisons are never statically computable. */ 3578 if (comp == GT_EXPR 3579 || comp == GE_EXPR 3580 || comp == LT_EXPR 3581 || comp == LE_EXPR) 3582 return NULL_TREE; 3583 3584 /* Equality can be computed only between a range and an 3585 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */ 3586 if (vr0->type == VR_RANGE) 3587 { 3588 /* To simplify processing, make VR0 the anti-range. */ 3589 value_range_t *tmp = vr0; 3590 vr0 = vr1; 3591 vr1 = tmp; 3592 } 3593 3594 gcc_assert (comp == NE_EXPR || comp == EQ_EXPR); 3595 3596 if (compare_values_warnv (vr0->min, vr1->min, strict_overflow_p) == 0 3597 && compare_values_warnv (vr0->max, vr1->max, strict_overflow_p) == 0) 3598 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node; 3599 3600 return NULL_TREE; 3601 } 3602 3603 if (!usable_range_p (vr0, strict_overflow_p) 3604 || !usable_range_p (vr1, strict_overflow_p)) 3605 return NULL_TREE; 3606 3607 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the 3608 operands around and change the comparison code. */ 3609 if (comp == GT_EXPR || comp == GE_EXPR) 3610 { 3611 value_range_t *tmp; 3612 comp = (comp == GT_EXPR) ? LT_EXPR : LE_EXPR; 3613 tmp = vr0; 3614 vr0 = vr1; 3615 vr1 = tmp; 3616 } 3617 3618 if (comp == EQ_EXPR) 3619 { 3620 /* Equality may only be computed if both ranges represent 3621 exactly one value. */ 3622 if (compare_values_warnv (vr0->min, vr0->max, strict_overflow_p) == 0 3623 && compare_values_warnv (vr1->min, vr1->max, strict_overflow_p) == 0) 3624 { 3625 int cmp_min = compare_values_warnv (vr0->min, vr1->min, 3626 strict_overflow_p); 3627 int cmp_max = compare_values_warnv (vr0->max, vr1->max, 3628 strict_overflow_p); 3629 if (cmp_min == 0 && cmp_max == 0) 3630 return boolean_true_node; 3631 else if (cmp_min != -2 && cmp_max != -2) 3632 return boolean_false_node; 3633 } 3634 /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */ 3635 else if (compare_values_warnv (vr0->min, vr1->max, 3636 strict_overflow_p) == 1 3637 || compare_values_warnv (vr1->min, vr0->max, 3638 strict_overflow_p) == 1) 3639 return boolean_false_node; 3640 3641 return NULL_TREE; 3642 } 3643 else if (comp == NE_EXPR) 3644 { 3645 int cmp1, cmp2; 3646 3647 /* If VR0 is completely to the left or completely to the right 3648 of VR1, they are always different. Notice that we need to 3649 make sure that both comparisons yield similar results to 3650 avoid comparing values that cannot be compared at 3651 compile-time. */ 3652 cmp1 = compare_values_warnv (vr0->max, vr1->min, strict_overflow_p); 3653 cmp2 = compare_values_warnv (vr0->min, vr1->max, strict_overflow_p); 3654 if ((cmp1 == -1 && cmp2 == -1) || (cmp1 == 1 && cmp2 == 1)) 3655 return boolean_true_node; 3656 3657 /* If VR0 and VR1 represent a single value and are identical, 3658 return false. */ 3659 else if (compare_values_warnv (vr0->min, vr0->max, 3660 strict_overflow_p) == 0 3661 && compare_values_warnv (vr1->min, vr1->max, 3662 strict_overflow_p) == 0 3663 && compare_values_warnv (vr0->min, vr1->min, 3664 strict_overflow_p) == 0 3665 && compare_values_warnv (vr0->max, vr1->max, 3666 strict_overflow_p) == 0) 3667 return boolean_false_node; 3668 3669 /* Otherwise, they may or may not be different. */ 3670 else 3671 return NULL_TREE; 3672 } 3673 else if (comp == LT_EXPR || comp == LE_EXPR) 3674 { 3675 int tst; 3676 3677 /* If VR0 is to the left of VR1, return true. */ 3678 tst = compare_values_warnv (vr0->max, vr1->min, strict_overflow_p); 3679 if ((comp == LT_EXPR && tst == -1) 3680 || (comp == LE_EXPR && (tst == -1 || tst == 0))) 3681 { 3682 if (overflow_infinity_range_p (vr0) 3683 || overflow_infinity_range_p (vr1)) 3684 *strict_overflow_p = true; 3685 return boolean_true_node; 3686 } 3687 3688 /* If VR0 is to the right of VR1, return false. */ 3689 tst = compare_values_warnv (vr0->min, vr1->max, strict_overflow_p); 3690 if ((comp == LT_EXPR && (tst == 0 || tst == 1)) 3691 || (comp == LE_EXPR && tst == 1)) 3692 { 3693 if (overflow_infinity_range_p (vr0) 3694 || overflow_infinity_range_p (vr1)) 3695 *strict_overflow_p = true; 3696 return boolean_false_node; 3697 } 3698 3699 /* Otherwise, we don't know. */ 3700 return NULL_TREE; 3701 } 3702 3703 gcc_unreachable (); 3704 } 3705 3706 3707 /* Given a value range VR, a value VAL and a comparison code COMP, return 3708 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the 3709 values in VR. Return BOOLEAN_FALSE_NODE if the comparison 3710 always returns false. Return NULL_TREE if it is not always 3711 possible to determine the value of the comparison. Also set 3712 *STRICT_OVERFLOW_P to indicate whether a range with an overflow 3713 infinity was used in the test. */ 3714 3715 static tree 3716 compare_range_with_value (enum tree_code comp, value_range_t *vr, tree val, 3717 bool *strict_overflow_p) 3718 { 3719 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED) 3720 return NULL_TREE; 3721 3722 /* Anti-ranges need to be handled separately. */ 3723 if (vr->type == VR_ANTI_RANGE) 3724 { 3725 /* For anti-ranges, the only predicates that we can compute at 3726 compile time are equality and inequality. */ 3727 if (comp == GT_EXPR 3728 || comp == GE_EXPR 3729 || comp == LT_EXPR 3730 || comp == LE_EXPR) 3731 return NULL_TREE; 3732 3733 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */ 3734 if (value_inside_range (val, vr->min, vr->max) == 1) 3735 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node; 3736 3737 return NULL_TREE; 3738 } 3739 3740 if (!usable_range_p (vr, strict_overflow_p)) 3741 return NULL_TREE; 3742 3743 if (comp == EQ_EXPR) 3744 { 3745 /* EQ_EXPR may only be computed if VR represents exactly 3746 one value. */ 3747 if (compare_values_warnv (vr->min, vr->max, strict_overflow_p) == 0) 3748 { 3749 int cmp = compare_values_warnv (vr->min, val, strict_overflow_p); 3750 if (cmp == 0) 3751 return boolean_true_node; 3752 else if (cmp == -1 || cmp == 1 || cmp == 2) 3753 return boolean_false_node; 3754 } 3755 else if (compare_values_warnv (val, vr->min, strict_overflow_p) == -1 3756 || compare_values_warnv (vr->max, val, strict_overflow_p) == -1) 3757 return boolean_false_node; 3758 3759 return NULL_TREE; 3760 } 3761 else if (comp == NE_EXPR) 3762 { 3763 /* If VAL is not inside VR, then they are always different. */ 3764 if (compare_values_warnv (vr->max, val, strict_overflow_p) == -1 3765 || compare_values_warnv (vr->min, val, strict_overflow_p) == 1) 3766 return boolean_true_node; 3767 3768 /* If VR represents exactly one value equal to VAL, then return 3769 false. */ 3770 if (compare_values_warnv (vr->min, vr->max, strict_overflow_p) == 0 3771 && compare_values_warnv (vr->min, val, strict_overflow_p) == 0) 3772 return boolean_false_node; 3773 3774 /* Otherwise, they may or may not be different. */ 3775 return NULL_TREE; 3776 } 3777 else if (comp == LT_EXPR || comp == LE_EXPR) 3778 { 3779 int tst; 3780 3781 /* If VR is to the left of VAL, return true. */ 3782 tst = compare_values_warnv (vr->max, val, strict_overflow_p); 3783 if ((comp == LT_EXPR && tst == -1) 3784 || (comp == LE_EXPR && (tst == -1 || tst == 0))) 3785 { 3786 if (overflow_infinity_range_p (vr)) 3787 *strict_overflow_p = true; 3788 return boolean_true_node; 3789 } 3790 3791 /* If VR is to the right of VAL, return false. */ 3792 tst = compare_values_warnv (vr->min, val, strict_overflow_p); 3793 if ((comp == LT_EXPR && (tst == 0 || tst == 1)) 3794 || (comp == LE_EXPR && tst == 1)) 3795 { 3796 if (overflow_infinity_range_p (vr)) 3797 *strict_overflow_p = true; 3798 return boolean_false_node; 3799 } 3800 3801 /* Otherwise, we don't know. */ 3802 return NULL_TREE; 3803 } 3804 else if (comp == GT_EXPR || comp == GE_EXPR) 3805 { 3806 int tst; 3807 3808 /* If VR is to the right of VAL, return true. */ 3809 tst = compare_values_warnv (vr->min, val, strict_overflow_p); 3810 if ((comp == GT_EXPR && tst == 1) 3811 || (comp == GE_EXPR && (tst == 0 || tst == 1))) 3812 { 3813 if (overflow_infinity_range_p (vr)) 3814 *strict_overflow_p = true; 3815 return boolean_true_node; 3816 } 3817 3818 /* If VR is to the left of VAL, return false. */ 3819 tst = compare_values_warnv (vr->max, val, strict_overflow_p); 3820 if ((comp == GT_EXPR && (tst == -1 || tst == 0)) 3821 || (comp == GE_EXPR && tst == -1)) 3822 { 3823 if (overflow_infinity_range_p (vr)) 3824 *strict_overflow_p = true; 3825 return boolean_false_node; 3826 } 3827 3828 /* Otherwise, we don't know. */ 3829 return NULL_TREE; 3830 } 3831 3832 gcc_unreachable (); 3833 } 3834 3835 3836 /* Debugging dumps. */ 3837 3838 void dump_value_range (FILE *, value_range_t *); 3839 void debug_value_range (value_range_t *); 3840 void dump_all_value_ranges (FILE *); 3841 void debug_all_value_ranges (void); 3842 void dump_vr_equiv (FILE *, bitmap); 3843 void debug_vr_equiv (bitmap); 3844 3845 3846 /* Dump value range VR to FILE. */ 3847 3848 void 3849 dump_value_range (FILE *file, value_range_t *vr) 3850 { 3851 if (vr == NULL) 3852 fprintf (file, "[]"); 3853 else if (vr->type == VR_UNDEFINED) 3854 fprintf (file, "UNDEFINED"); 3855 else if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE) 3856 { 3857 tree type = TREE_TYPE (vr->min); 3858 3859 fprintf (file, "%s[", (vr->type == VR_ANTI_RANGE) ? "~" : ""); 3860 3861 if (is_negative_overflow_infinity (vr->min)) 3862 fprintf (file, "-INF(OVF)"); 3863 else if (INTEGRAL_TYPE_P (type) 3864 && !TYPE_UNSIGNED (type) 3865 && vrp_val_is_min (vr->min)) 3866 fprintf (file, "-INF"); 3867 else 3868 print_generic_expr (file, vr->min, 0); 3869 3870 fprintf (file, ", "); 3871 3872 if (is_positive_overflow_infinity (vr->max)) 3873 fprintf (file, "+INF(OVF)"); 3874 else if (INTEGRAL_TYPE_P (type) 3875 && vrp_val_is_max (vr->max)) 3876 fprintf (file, "+INF"); 3877 else 3878 print_generic_expr (file, vr->max, 0); 3879 3880 fprintf (file, "]"); 3881 3882 if (vr->equiv) 3883 { 3884 bitmap_iterator bi; 3885 unsigned i, c = 0; 3886 3887 fprintf (file, " EQUIVALENCES: { "); 3888 3889 EXECUTE_IF_SET_IN_BITMAP (vr->equiv, 0, i, bi) 3890 { 3891 print_generic_expr (file, ssa_name (i), 0); 3892 fprintf (file, " "); 3893 c++; 3894 } 3895 3896 fprintf (file, "} (%u elements)", c); 3897 } 3898 } 3899 else if (vr->type == VR_VARYING) 3900 fprintf (file, "VARYING"); 3901 else 3902 fprintf (file, "INVALID RANGE"); 3903 } 3904 3905 3906 /* Dump value range VR to stderr. */ 3907 3908 DEBUG_FUNCTION void 3909 debug_value_range (value_range_t *vr) 3910 { 3911 dump_value_range (stderr, vr); 3912 fprintf (stderr, "\n"); 3913 } 3914 3915 3916 /* Dump value ranges of all SSA_NAMEs to FILE. */ 3917 3918 void 3919 dump_all_value_ranges (FILE *file) 3920 { 3921 size_t i; 3922 3923 for (i = 0; i < num_vr_values; i++) 3924 { 3925 if (vr_value[i]) 3926 { 3927 print_generic_expr (file, ssa_name (i), 0); 3928 fprintf (file, ": "); 3929 dump_value_range (file, vr_value[i]); 3930 fprintf (file, "\n"); 3931 } 3932 } 3933 3934 fprintf (file, "\n"); 3935 } 3936 3937 3938 /* Dump all value ranges to stderr. */ 3939 3940 DEBUG_FUNCTION void 3941 debug_all_value_ranges (void) 3942 { 3943 dump_all_value_ranges (stderr); 3944 } 3945 3946 3947 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V, 3948 create a new SSA name N and return the assertion assignment 3949 'V = ASSERT_EXPR <V, V OP W>'. */ 3950 3951 static gimple 3952 build_assert_expr_for (tree cond, tree v) 3953 { 3954 tree n; 3955 gimple assertion; 3956 3957 gcc_assert (TREE_CODE (v) == SSA_NAME); 3958 n = duplicate_ssa_name (v, NULL); 3959 3960 if (COMPARISON_CLASS_P (cond)) 3961 { 3962 tree a = build2 (ASSERT_EXPR, TREE_TYPE (v), v, cond); 3963 assertion = gimple_build_assign (n, a); 3964 } 3965 else if (TREE_CODE (cond) == SSA_NAME) 3966 { 3967 /* Given V, build the assignment N = true. */ 3968 gcc_assert (v == cond); 3969 assertion = gimple_build_assign (n, boolean_true_node); 3970 } 3971 else 3972 gcc_unreachable (); 3973 3974 SSA_NAME_DEF_STMT (n) = assertion; 3975 3976 /* The new ASSERT_EXPR, creates a new SSA name that replaces the 3977 operand of the ASSERT_EXPR. Register the new name and the old one 3978 in the replacement table so that we can fix the SSA web after 3979 adding all the ASSERT_EXPRs. */ 3980 register_new_name_mapping (n, v); 3981 3982 return assertion; 3983 } 3984 3985 3986 /* Return false if EXPR is a predicate expression involving floating 3987 point values. */ 3988 3989 static inline bool 3990 fp_predicate (gimple stmt) 3991 { 3992 GIMPLE_CHECK (stmt, GIMPLE_COND); 3993 3994 return FLOAT_TYPE_P (TREE_TYPE (gimple_cond_lhs (stmt))); 3995 } 3996 3997 3998 /* If the range of values taken by OP can be inferred after STMT executes, 3999 return the comparison code (COMP_CODE_P) and value (VAL_P) that 4000 describes the inferred range. Return true if a range could be 4001 inferred. */ 4002 4003 static bool 4004 infer_value_range (gimple stmt, tree op, enum tree_code *comp_code_p, tree *val_p) 4005 { 4006 *val_p = NULL_TREE; 4007 *comp_code_p = ERROR_MARK; 4008 4009 /* Do not attempt to infer anything in names that flow through 4010 abnormal edges. */ 4011 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op)) 4012 return false; 4013 4014 /* Similarly, don't infer anything from statements that may throw 4015 exceptions. */ 4016 if (stmt_could_throw_p (stmt)) 4017 return false; 4018 4019 /* If STMT is the last statement of a basic block with no 4020 successors, there is no point inferring anything about any of its 4021 operands. We would not be able to find a proper insertion point 4022 for the assertion, anyway. */ 4023 if (stmt_ends_bb_p (stmt) && EDGE_COUNT (gimple_bb (stmt)->succs) == 0) 4024 return false; 4025 4026 /* We can only assume that a pointer dereference will yield 4027 non-NULL if -fdelete-null-pointer-checks is enabled. */ 4028 if (flag_delete_null_pointer_checks 4029 && POINTER_TYPE_P (TREE_TYPE (op)) 4030 && gimple_code (stmt) != GIMPLE_ASM) 4031 { 4032 unsigned num_uses, num_loads, num_stores; 4033 4034 count_uses_and_derefs (op, stmt, &num_uses, &num_loads, &num_stores); 4035 if (num_loads + num_stores > 0) 4036 { 4037 *val_p = build_int_cst (TREE_TYPE (op), 0); 4038 *comp_code_p = NE_EXPR; 4039 return true; 4040 } 4041 } 4042 4043 return false; 4044 } 4045 4046 4047 void dump_asserts_for (FILE *, tree); 4048 void debug_asserts_for (tree); 4049 void dump_all_asserts (FILE *); 4050 void debug_all_asserts (void); 4051 4052 /* Dump all the registered assertions for NAME to FILE. */ 4053 4054 void 4055 dump_asserts_for (FILE *file, tree name) 4056 { 4057 assert_locus_t loc; 4058 4059 fprintf (file, "Assertions to be inserted for "); 4060 print_generic_expr (file, name, 0); 4061 fprintf (file, "\n"); 4062 4063 loc = asserts_for[SSA_NAME_VERSION (name)]; 4064 while (loc) 4065 { 4066 fprintf (file, "\t"); 4067 print_gimple_stmt (file, gsi_stmt (loc->si), 0, 0); 4068 fprintf (file, "\n\tBB #%d", loc->bb->index); 4069 if (loc->e) 4070 { 4071 fprintf (file, "\n\tEDGE %d->%d", loc->e->src->index, 4072 loc->e->dest->index); 4073 dump_edge_info (file, loc->e, 0); 4074 } 4075 fprintf (file, "\n\tPREDICATE: "); 4076 print_generic_expr (file, name, 0); 4077 fprintf (file, " %s ", tree_code_name[(int)loc->comp_code]); 4078 print_generic_expr (file, loc->val, 0); 4079 fprintf (file, "\n\n"); 4080 loc = loc->next; 4081 } 4082 4083 fprintf (file, "\n"); 4084 } 4085 4086 4087 /* Dump all the registered assertions for NAME to stderr. */ 4088 4089 DEBUG_FUNCTION void 4090 debug_asserts_for (tree name) 4091 { 4092 dump_asserts_for (stderr, name); 4093 } 4094 4095 4096 /* Dump all the registered assertions for all the names to FILE. */ 4097 4098 void 4099 dump_all_asserts (FILE *file) 4100 { 4101 unsigned i; 4102 bitmap_iterator bi; 4103 4104 fprintf (file, "\nASSERT_EXPRs to be inserted\n\n"); 4105 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi) 4106 dump_asserts_for (file, ssa_name (i)); 4107 fprintf (file, "\n"); 4108 } 4109 4110 4111 /* Dump all the registered assertions for all the names to stderr. */ 4112 4113 DEBUG_FUNCTION void 4114 debug_all_asserts (void) 4115 { 4116 dump_all_asserts (stderr); 4117 } 4118 4119 4120 /* If NAME doesn't have an ASSERT_EXPR registered for asserting 4121 'EXPR COMP_CODE VAL' at a location that dominates block BB or 4122 E->DEST, then register this location as a possible insertion point 4123 for ASSERT_EXPR <NAME, EXPR COMP_CODE VAL>. 4124 4125 BB, E and SI provide the exact insertion point for the new 4126 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted 4127 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on 4128 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E 4129 must not be NULL. */ 4130 4131 static void 4132 register_new_assert_for (tree name, tree expr, 4133 enum tree_code comp_code, 4134 tree val, 4135 basic_block bb, 4136 edge e, 4137 gimple_stmt_iterator si) 4138 { 4139 assert_locus_t n, loc, last_loc; 4140 basic_block dest_bb; 4141 4142 gcc_checking_assert (bb == NULL || e == NULL); 4143 4144 if (e == NULL) 4145 gcc_checking_assert (gimple_code (gsi_stmt (si)) != GIMPLE_COND 4146 && gimple_code (gsi_stmt (si)) != GIMPLE_SWITCH); 4147 4148 /* Never build an assert comparing against an integer constant with 4149 TREE_OVERFLOW set. This confuses our undefined overflow warning 4150 machinery. */ 4151 if (TREE_CODE (val) == INTEGER_CST 4152 && TREE_OVERFLOW (val)) 4153 val = build_int_cst_wide (TREE_TYPE (val), 4154 TREE_INT_CST_LOW (val), TREE_INT_CST_HIGH (val)); 4155 4156 /* The new assertion A will be inserted at BB or E. We need to 4157 determine if the new location is dominated by a previously 4158 registered location for A. If we are doing an edge insertion, 4159 assume that A will be inserted at E->DEST. Note that this is not 4160 necessarily true. 4161 4162 If E is a critical edge, it will be split. But even if E is 4163 split, the new block will dominate the same set of blocks that 4164 E->DEST dominates. 4165 4166 The reverse, however, is not true, blocks dominated by E->DEST 4167 will not be dominated by the new block created to split E. So, 4168 if the insertion location is on a critical edge, we will not use 4169 the new location to move another assertion previously registered 4170 at a block dominated by E->DEST. */ 4171 dest_bb = (bb) ? bb : e->dest; 4172 4173 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and 4174 VAL at a block dominating DEST_BB, then we don't need to insert a new 4175 one. Similarly, if the same assertion already exists at a block 4176 dominated by DEST_BB and the new location is not on a critical 4177 edge, then update the existing location for the assertion (i.e., 4178 move the assertion up in the dominance tree). 4179 4180 Note, this is implemented as a simple linked list because there 4181 should not be more than a handful of assertions registered per 4182 name. If this becomes a performance problem, a table hashed by 4183 COMP_CODE and VAL could be implemented. */ 4184 loc = asserts_for[SSA_NAME_VERSION (name)]; 4185 last_loc = loc; 4186 while (loc) 4187 { 4188 if (loc->comp_code == comp_code 4189 && (loc->val == val 4190 || operand_equal_p (loc->val, val, 0)) 4191 && (loc->expr == expr 4192 || operand_equal_p (loc->expr, expr, 0))) 4193 { 4194 /* If the assertion NAME COMP_CODE VAL has already been 4195 registered at a basic block that dominates DEST_BB, then 4196 we don't need to insert the same assertion again. Note 4197 that we don't check strict dominance here to avoid 4198 replicating the same assertion inside the same basic 4199 block more than once (e.g., when a pointer is 4200 dereferenced several times inside a block). 4201 4202 An exception to this rule are edge insertions. If the 4203 new assertion is to be inserted on edge E, then it will 4204 dominate all the other insertions that we may want to 4205 insert in DEST_BB. So, if we are doing an edge 4206 insertion, don't do this dominance check. */ 4207 if (e == NULL 4208 && dominated_by_p (CDI_DOMINATORS, dest_bb, loc->bb)) 4209 return; 4210 4211 /* Otherwise, if E is not a critical edge and DEST_BB 4212 dominates the existing location for the assertion, move 4213 the assertion up in the dominance tree by updating its 4214 location information. */ 4215 if ((e == NULL || !EDGE_CRITICAL_P (e)) 4216 && dominated_by_p (CDI_DOMINATORS, loc->bb, dest_bb)) 4217 { 4218 loc->bb = dest_bb; 4219 loc->e = e; 4220 loc->si = si; 4221 return; 4222 } 4223 } 4224 4225 /* Update the last node of the list and move to the next one. */ 4226 last_loc = loc; 4227 loc = loc->next; 4228 } 4229 4230 /* If we didn't find an assertion already registered for 4231 NAME COMP_CODE VAL, add a new one at the end of the list of 4232 assertions associated with NAME. */ 4233 n = XNEW (struct assert_locus_d); 4234 n->bb = dest_bb; 4235 n->e = e; 4236 n->si = si; 4237 n->comp_code = comp_code; 4238 n->val = val; 4239 n->expr = expr; 4240 n->next = NULL; 4241 4242 if (last_loc) 4243 last_loc->next = n; 4244 else 4245 asserts_for[SSA_NAME_VERSION (name)] = n; 4246 4247 bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name)); 4248 } 4249 4250 /* (COND_OP0 COND_CODE COND_OP1) is a predicate which uses NAME. 4251 Extract a suitable test code and value and store them into *CODE_P and 4252 *VAL_P so the predicate is normalized to NAME *CODE_P *VAL_P. 4253 4254 If no extraction was possible, return FALSE, otherwise return TRUE. 4255 4256 If INVERT is true, then we invert the result stored into *CODE_P. */ 4257 4258 static bool 4259 extract_code_and_val_from_cond_with_ops (tree name, enum tree_code cond_code, 4260 tree cond_op0, tree cond_op1, 4261 bool invert, enum tree_code *code_p, 4262 tree *val_p) 4263 { 4264 enum tree_code comp_code; 4265 tree val; 4266 4267 /* Otherwise, we have a comparison of the form NAME COMP VAL 4268 or VAL COMP NAME. */ 4269 if (name == cond_op1) 4270 { 4271 /* If the predicate is of the form VAL COMP NAME, flip 4272 COMP around because we need to register NAME as the 4273 first operand in the predicate. */ 4274 comp_code = swap_tree_comparison (cond_code); 4275 val = cond_op0; 4276 } 4277 else 4278 { 4279 /* The comparison is of the form NAME COMP VAL, so the 4280 comparison code remains unchanged. */ 4281 comp_code = cond_code; 4282 val = cond_op1; 4283 } 4284 4285 /* Invert the comparison code as necessary. */ 4286 if (invert) 4287 comp_code = invert_tree_comparison (comp_code, 0); 4288 4289 /* VRP does not handle float types. */ 4290 if (SCALAR_FLOAT_TYPE_P (TREE_TYPE (val))) 4291 return false; 4292 4293 /* Do not register always-false predicates. 4294 FIXME: this works around a limitation in fold() when dealing with 4295 enumerations. Given 'enum { N1, N2 } x;', fold will not 4296 fold 'if (x > N2)' to 'if (0)'. */ 4297 if ((comp_code == GT_EXPR || comp_code == LT_EXPR) 4298 && INTEGRAL_TYPE_P (TREE_TYPE (val))) 4299 { 4300 tree min = TYPE_MIN_VALUE (TREE_TYPE (val)); 4301 tree max = TYPE_MAX_VALUE (TREE_TYPE (val)); 4302 4303 if (comp_code == GT_EXPR 4304 && (!max 4305 || compare_values (val, max) == 0)) 4306 return false; 4307 4308 if (comp_code == LT_EXPR 4309 && (!min 4310 || compare_values (val, min) == 0)) 4311 return false; 4312 } 4313 *code_p = comp_code; 4314 *val_p = val; 4315 return true; 4316 } 4317 4318 /* Try to register an edge assertion for SSA name NAME on edge E for 4319 the condition COND contributing to the conditional jump pointed to by BSI. 4320 Invert the condition COND if INVERT is true. 4321 Return true if an assertion for NAME could be registered. */ 4322 4323 static bool 4324 register_edge_assert_for_2 (tree name, edge e, gimple_stmt_iterator bsi, 4325 enum tree_code cond_code, 4326 tree cond_op0, tree cond_op1, bool invert) 4327 { 4328 tree val; 4329 enum tree_code comp_code; 4330 bool retval = false; 4331 4332 if (!extract_code_and_val_from_cond_with_ops (name, cond_code, 4333 cond_op0, 4334 cond_op1, 4335 invert, &comp_code, &val)) 4336 return false; 4337 4338 /* Only register an ASSERT_EXPR if NAME was found in the sub-graph 4339 reachable from E. */ 4340 if (live_on_edge (e, name) 4341 && !has_single_use (name)) 4342 { 4343 register_new_assert_for (name, name, comp_code, val, NULL, e, bsi); 4344 retval = true; 4345 } 4346 4347 /* In the case of NAME <= CST and NAME being defined as 4348 NAME = (unsigned) NAME2 + CST2 we can assert NAME2 >= -CST2 4349 and NAME2 <= CST - CST2. We can do the same for NAME > CST. 4350 This catches range and anti-range tests. */ 4351 if ((comp_code == LE_EXPR 4352 || comp_code == GT_EXPR) 4353 && TREE_CODE (val) == INTEGER_CST 4354 && TYPE_UNSIGNED (TREE_TYPE (val))) 4355 { 4356 gimple def_stmt = SSA_NAME_DEF_STMT (name); 4357 tree cst2 = NULL_TREE, name2 = NULL_TREE, name3 = NULL_TREE; 4358 4359 /* Extract CST2 from the (optional) addition. */ 4360 if (is_gimple_assign (def_stmt) 4361 && gimple_assign_rhs_code (def_stmt) == PLUS_EXPR) 4362 { 4363 name2 = gimple_assign_rhs1 (def_stmt); 4364 cst2 = gimple_assign_rhs2 (def_stmt); 4365 if (TREE_CODE (name2) == SSA_NAME 4366 && TREE_CODE (cst2) == INTEGER_CST) 4367 def_stmt = SSA_NAME_DEF_STMT (name2); 4368 } 4369 4370 /* Extract NAME2 from the (optional) sign-changing cast. */ 4371 if (gimple_assign_cast_p (def_stmt)) 4372 { 4373 if (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (def_stmt)) 4374 && ! TYPE_UNSIGNED (TREE_TYPE (gimple_assign_rhs1 (def_stmt))) 4375 && (TYPE_PRECISION (gimple_expr_type (def_stmt)) 4376 == TYPE_PRECISION (TREE_TYPE (gimple_assign_rhs1 (def_stmt))))) 4377 name3 = gimple_assign_rhs1 (def_stmt); 4378 } 4379 4380 /* If name3 is used later, create an ASSERT_EXPR for it. */ 4381 if (name3 != NULL_TREE 4382 && TREE_CODE (name3) == SSA_NAME 4383 && (cst2 == NULL_TREE 4384 || TREE_CODE (cst2) == INTEGER_CST) 4385 && INTEGRAL_TYPE_P (TREE_TYPE (name3)) 4386 && live_on_edge (e, name3) 4387 && !has_single_use (name3)) 4388 { 4389 tree tmp; 4390 4391 /* Build an expression for the range test. */ 4392 tmp = build1 (NOP_EXPR, TREE_TYPE (name), name3); 4393 if (cst2 != NULL_TREE) 4394 tmp = build2 (PLUS_EXPR, TREE_TYPE (name), tmp, cst2); 4395 4396 if (dump_file) 4397 { 4398 fprintf (dump_file, "Adding assert for "); 4399 print_generic_expr (dump_file, name3, 0); 4400 fprintf (dump_file, " from "); 4401 print_generic_expr (dump_file, tmp, 0); 4402 fprintf (dump_file, "\n"); 4403 } 4404 4405 register_new_assert_for (name3, tmp, comp_code, val, NULL, e, bsi); 4406 4407 retval = true; 4408 } 4409 4410 /* If name2 is used later, create an ASSERT_EXPR for it. */ 4411 if (name2 != NULL_TREE 4412 && TREE_CODE (name2) == SSA_NAME 4413 && TREE_CODE (cst2) == INTEGER_CST 4414 && INTEGRAL_TYPE_P (TREE_TYPE (name2)) 4415 && live_on_edge (e, name2) 4416 && !has_single_use (name2)) 4417 { 4418 tree tmp; 4419 4420 /* Build an expression for the range test. */ 4421 tmp = name2; 4422 if (TREE_TYPE (name) != TREE_TYPE (name2)) 4423 tmp = build1 (NOP_EXPR, TREE_TYPE (name), tmp); 4424 if (cst2 != NULL_TREE) 4425 tmp = build2 (PLUS_EXPR, TREE_TYPE (name), tmp, cst2); 4426 4427 if (dump_file) 4428 { 4429 fprintf (dump_file, "Adding assert for "); 4430 print_generic_expr (dump_file, name2, 0); 4431 fprintf (dump_file, " from "); 4432 print_generic_expr (dump_file, tmp, 0); 4433 fprintf (dump_file, "\n"); 4434 } 4435 4436 register_new_assert_for (name2, tmp, comp_code, val, NULL, e, bsi); 4437 4438 retval = true; 4439 } 4440 } 4441 4442 return retval; 4443 } 4444 4445 /* OP is an operand of a truth value expression which is known to have 4446 a particular value. Register any asserts for OP and for any 4447 operands in OP's defining statement. 4448 4449 If CODE is EQ_EXPR, then we want to register OP is zero (false), 4450 if CODE is NE_EXPR, then we want to register OP is nonzero (true). */ 4451 4452 static bool 4453 register_edge_assert_for_1 (tree op, enum tree_code code, 4454 edge e, gimple_stmt_iterator bsi) 4455 { 4456 bool retval = false; 4457 gimple op_def; 4458 tree val; 4459 enum tree_code rhs_code; 4460 4461 /* We only care about SSA_NAMEs. */ 4462 if (TREE_CODE (op) != SSA_NAME) 4463 return false; 4464 4465 /* We know that OP will have a zero or nonzero value. If OP is used 4466 more than once go ahead and register an assert for OP. 4467 4468 The FOUND_IN_SUBGRAPH support is not helpful in this situation as 4469 it will always be set for OP (because OP is used in a COND_EXPR in 4470 the subgraph). */ 4471 if (!has_single_use (op)) 4472 { 4473 val = build_int_cst (TREE_TYPE (op), 0); 4474 register_new_assert_for (op, op, code, val, NULL, e, bsi); 4475 retval = true; 4476 } 4477 4478 /* Now look at how OP is set. If it's set from a comparison, 4479 a truth operation or some bit operations, then we may be able 4480 to register information about the operands of that assignment. */ 4481 op_def = SSA_NAME_DEF_STMT (op); 4482 if (gimple_code (op_def) != GIMPLE_ASSIGN) 4483 return retval; 4484 4485 rhs_code = gimple_assign_rhs_code (op_def); 4486 4487 if (TREE_CODE_CLASS (rhs_code) == tcc_comparison) 4488 { 4489 bool invert = (code == EQ_EXPR ? true : false); 4490 tree op0 = gimple_assign_rhs1 (op_def); 4491 tree op1 = gimple_assign_rhs2 (op_def); 4492 4493 if (TREE_CODE (op0) == SSA_NAME) 4494 retval |= register_edge_assert_for_2 (op0, e, bsi, rhs_code, op0, op1, 4495 invert); 4496 if (TREE_CODE (op1) == SSA_NAME) 4497 retval |= register_edge_assert_for_2 (op1, e, bsi, rhs_code, op0, op1, 4498 invert); 4499 } 4500 else if ((code == NE_EXPR 4501 && gimple_assign_rhs_code (op_def) == BIT_AND_EXPR) 4502 || (code == EQ_EXPR 4503 && gimple_assign_rhs_code (op_def) == BIT_IOR_EXPR)) 4504 { 4505 /* Recurse on each operand. */ 4506 retval |= register_edge_assert_for_1 (gimple_assign_rhs1 (op_def), 4507 code, e, bsi); 4508 retval |= register_edge_assert_for_1 (gimple_assign_rhs2 (op_def), 4509 code, e, bsi); 4510 } 4511 else if (gimple_assign_rhs_code (op_def) == BIT_NOT_EXPR 4512 && TYPE_PRECISION (TREE_TYPE (gimple_assign_lhs (op_def))) == 1) 4513 { 4514 /* Recurse, flipping CODE. */ 4515 code = invert_tree_comparison (code, false); 4516 retval |= register_edge_assert_for_1 (gimple_assign_rhs1 (op_def), 4517 code, e, bsi); 4518 } 4519 else if (gimple_assign_rhs_code (op_def) == SSA_NAME) 4520 { 4521 /* Recurse through the copy. */ 4522 retval |= register_edge_assert_for_1 (gimple_assign_rhs1 (op_def), 4523 code, e, bsi); 4524 } 4525 else if (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (op_def))) 4526 { 4527 /* Recurse through the type conversion. */ 4528 retval |= register_edge_assert_for_1 (gimple_assign_rhs1 (op_def), 4529 code, e, bsi); 4530 } 4531 4532 return retval; 4533 } 4534 4535 /* Try to register an edge assertion for SSA name NAME on edge E for 4536 the condition COND contributing to the conditional jump pointed to by SI. 4537 Return true if an assertion for NAME could be registered. */ 4538 4539 static bool 4540 register_edge_assert_for (tree name, edge e, gimple_stmt_iterator si, 4541 enum tree_code cond_code, tree cond_op0, 4542 tree cond_op1) 4543 { 4544 tree val; 4545 enum tree_code comp_code; 4546 bool retval = false; 4547 bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0; 4548 4549 /* Do not attempt to infer anything in names that flow through 4550 abnormal edges. */ 4551 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name)) 4552 return false; 4553 4554 if (!extract_code_and_val_from_cond_with_ops (name, cond_code, 4555 cond_op0, cond_op1, 4556 is_else_edge, 4557 &comp_code, &val)) 4558 return false; 4559 4560 /* Register ASSERT_EXPRs for name. */ 4561 retval |= register_edge_assert_for_2 (name, e, si, cond_code, cond_op0, 4562 cond_op1, is_else_edge); 4563 4564 4565 /* If COND is effectively an equality test of an SSA_NAME against 4566 the value zero or one, then we may be able to assert values 4567 for SSA_NAMEs which flow into COND. */ 4568 4569 /* In the case of NAME == 1 or NAME != 0, for BIT_AND_EXPR defining 4570 statement of NAME we can assert both operands of the BIT_AND_EXPR 4571 have nonzero value. */ 4572 if (((comp_code == EQ_EXPR && integer_onep (val)) 4573 || (comp_code == NE_EXPR && integer_zerop (val)))) 4574 { 4575 gimple def_stmt = SSA_NAME_DEF_STMT (name); 4576 4577 if (is_gimple_assign (def_stmt) 4578 && gimple_assign_rhs_code (def_stmt) == BIT_AND_EXPR) 4579 { 4580 tree op0 = gimple_assign_rhs1 (def_stmt); 4581 tree op1 = gimple_assign_rhs2 (def_stmt); 4582 retval |= register_edge_assert_for_1 (op0, NE_EXPR, e, si); 4583 retval |= register_edge_assert_for_1 (op1, NE_EXPR, e, si); 4584 } 4585 } 4586 4587 /* In the case of NAME == 0 or NAME != 1, for BIT_IOR_EXPR defining 4588 statement of NAME we can assert both operands of the BIT_IOR_EXPR 4589 have zero value. */ 4590 if (((comp_code == EQ_EXPR && integer_zerop (val)) 4591 || (comp_code == NE_EXPR && integer_onep (val)))) 4592 { 4593 gimple def_stmt = SSA_NAME_DEF_STMT (name); 4594 4595 /* For BIT_IOR_EXPR only if NAME == 0 both operands have 4596 necessarily zero value, or if type-precision is one. */ 4597 if (is_gimple_assign (def_stmt) 4598 && (gimple_assign_rhs_code (def_stmt) == BIT_IOR_EXPR 4599 && (TYPE_PRECISION (TREE_TYPE (name)) == 1 4600 || comp_code == EQ_EXPR))) 4601 { 4602 tree op0 = gimple_assign_rhs1 (def_stmt); 4603 tree op1 = gimple_assign_rhs2 (def_stmt); 4604 retval |= register_edge_assert_for_1 (op0, EQ_EXPR, e, si); 4605 retval |= register_edge_assert_for_1 (op1, EQ_EXPR, e, si); 4606 } 4607 } 4608 4609 return retval; 4610 } 4611 4612 4613 /* Determine whether the outgoing edges of BB should receive an 4614 ASSERT_EXPR for each of the operands of BB's LAST statement. 4615 The last statement of BB must be a COND_EXPR. 4616 4617 If any of the sub-graphs rooted at BB have an interesting use of 4618 the predicate operands, an assert location node is added to the 4619 list of assertions for the corresponding operands. */ 4620 4621 static bool 4622 find_conditional_asserts (basic_block bb, gimple last) 4623 { 4624 bool need_assert; 4625 gimple_stmt_iterator bsi; 4626 tree op; 4627 edge_iterator ei; 4628 edge e; 4629 ssa_op_iter iter; 4630 4631 need_assert = false; 4632 bsi = gsi_for_stmt (last); 4633 4634 /* Look for uses of the operands in each of the sub-graphs 4635 rooted at BB. We need to check each of the outgoing edges 4636 separately, so that we know what kind of ASSERT_EXPR to 4637 insert. */ 4638 FOR_EACH_EDGE (e, ei, bb->succs) 4639 { 4640 if (e->dest == bb) 4641 continue; 4642 4643 /* Register the necessary assertions for each operand in the 4644 conditional predicate. */ 4645 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE) 4646 { 4647 need_assert |= register_edge_assert_for (op, e, bsi, 4648 gimple_cond_code (last), 4649 gimple_cond_lhs (last), 4650 gimple_cond_rhs (last)); 4651 } 4652 } 4653 4654 return need_assert; 4655 } 4656 4657 struct case_info 4658 { 4659 tree expr; 4660 basic_block bb; 4661 }; 4662 4663 /* Compare two case labels sorting first by the destination bb index 4664 and then by the case value. */ 4665 4666 static int 4667 compare_case_labels (const void *p1, const void *p2) 4668 { 4669 const struct case_info *ci1 = (const struct case_info *) p1; 4670 const struct case_info *ci2 = (const struct case_info *) p2; 4671 int idx1 = ci1->bb->index; 4672 int idx2 = ci2->bb->index; 4673 4674 if (idx1 < idx2) 4675 return -1; 4676 else if (idx1 == idx2) 4677 { 4678 /* Make sure the default label is first in a group. */ 4679 if (!CASE_LOW (ci1->expr)) 4680 return -1; 4681 else if (!CASE_LOW (ci2->expr)) 4682 return 1; 4683 else 4684 return tree_int_cst_compare (CASE_LOW (ci1->expr), 4685 CASE_LOW (ci2->expr)); 4686 } 4687 else 4688 return 1; 4689 } 4690 4691 /* Determine whether the outgoing edges of BB should receive an 4692 ASSERT_EXPR for each of the operands of BB's LAST statement. 4693 The last statement of BB must be a SWITCH_EXPR. 4694 4695 If any of the sub-graphs rooted at BB have an interesting use of 4696 the predicate operands, an assert location node is added to the 4697 list of assertions for the corresponding operands. */ 4698 4699 static bool 4700 find_switch_asserts (basic_block bb, gimple last) 4701 { 4702 bool need_assert; 4703 gimple_stmt_iterator bsi; 4704 tree op; 4705 edge e; 4706 struct case_info *ci; 4707 size_t n = gimple_switch_num_labels (last); 4708 #if GCC_VERSION >= 4000 4709 unsigned int idx; 4710 #else 4711 /* Work around GCC 3.4 bug (PR 37086). */ 4712 volatile unsigned int idx; 4713 #endif 4714 4715 need_assert = false; 4716 bsi = gsi_for_stmt (last); 4717 op = gimple_switch_index (last); 4718 if (TREE_CODE (op) != SSA_NAME) 4719 return false; 4720 4721 /* Build a vector of case labels sorted by destination label. */ 4722 ci = XNEWVEC (struct case_info, n); 4723 for (idx = 0; idx < n; ++idx) 4724 { 4725 ci[idx].expr = gimple_switch_label (last, idx); 4726 ci[idx].bb = label_to_block (CASE_LABEL (ci[idx].expr)); 4727 } 4728 qsort (ci, n, sizeof (struct case_info), compare_case_labels); 4729 4730 for (idx = 0; idx < n; ++idx) 4731 { 4732 tree min, max; 4733 tree cl = ci[idx].expr; 4734 basic_block cbb = ci[idx].bb; 4735 4736 min = CASE_LOW (cl); 4737 max = CASE_HIGH (cl); 4738 4739 /* If there are multiple case labels with the same destination 4740 we need to combine them to a single value range for the edge. */ 4741 if (idx + 1 < n && cbb == ci[idx + 1].bb) 4742 { 4743 /* Skip labels until the last of the group. */ 4744 do { 4745 ++idx; 4746 } while (idx < n && cbb == ci[idx].bb); 4747 --idx; 4748 4749 /* Pick up the maximum of the case label range. */ 4750 if (CASE_HIGH (ci[idx].expr)) 4751 max = CASE_HIGH (ci[idx].expr); 4752 else 4753 max = CASE_LOW (ci[idx].expr); 4754 } 4755 4756 /* Nothing to do if the range includes the default label until we 4757 can register anti-ranges. */ 4758 if (min == NULL_TREE) 4759 continue; 4760 4761 /* Find the edge to register the assert expr on. */ 4762 e = find_edge (bb, cbb); 4763 4764 /* Register the necessary assertions for the operand in the 4765 SWITCH_EXPR. */ 4766 need_assert |= register_edge_assert_for (op, e, bsi, 4767 max ? GE_EXPR : EQ_EXPR, 4768 op, 4769 fold_convert (TREE_TYPE (op), 4770 min)); 4771 if (max) 4772 { 4773 need_assert |= register_edge_assert_for (op, e, bsi, LE_EXPR, 4774 op, 4775 fold_convert (TREE_TYPE (op), 4776 max)); 4777 } 4778 } 4779 4780 XDELETEVEC (ci); 4781 return need_assert; 4782 } 4783 4784 4785 /* Traverse all the statements in block BB looking for statements that 4786 may generate useful assertions for the SSA names in their operand. 4787 If a statement produces a useful assertion A for name N_i, then the 4788 list of assertions already generated for N_i is scanned to 4789 determine if A is actually needed. 4790 4791 If N_i already had the assertion A at a location dominating the 4792 current location, then nothing needs to be done. Otherwise, the 4793 new location for A is recorded instead. 4794 4795 1- For every statement S in BB, all the variables used by S are 4796 added to bitmap FOUND_IN_SUBGRAPH. 4797 4798 2- If statement S uses an operand N in a way that exposes a known 4799 value range for N, then if N was not already generated by an 4800 ASSERT_EXPR, create a new assert location for N. For instance, 4801 if N is a pointer and the statement dereferences it, we can 4802 assume that N is not NULL. 4803 4804 3- COND_EXPRs are a special case of #2. We can derive range 4805 information from the predicate but need to insert different 4806 ASSERT_EXPRs for each of the sub-graphs rooted at the 4807 conditional block. If the last statement of BB is a conditional 4808 expression of the form 'X op Y', then 4809 4810 a) Remove X and Y from the set FOUND_IN_SUBGRAPH. 4811 4812 b) If the conditional is the only entry point to the sub-graph 4813 corresponding to the THEN_CLAUSE, recurse into it. On 4814 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then 4815 an ASSERT_EXPR is added for the corresponding variable. 4816 4817 c) Repeat step (b) on the ELSE_CLAUSE. 4818 4819 d) Mark X and Y in FOUND_IN_SUBGRAPH. 4820 4821 For instance, 4822 4823 if (a == 9) 4824 b = a; 4825 else 4826 b = c + 1; 4827 4828 In this case, an assertion on the THEN clause is useful to 4829 determine that 'a' is always 9 on that edge. However, an assertion 4830 on the ELSE clause would be unnecessary. 4831 4832 4- If BB does not end in a conditional expression, then we recurse 4833 into BB's dominator children. 4834 4835 At the end of the recursive traversal, every SSA name will have a 4836 list of locations where ASSERT_EXPRs should be added. When a new 4837 location for name N is found, it is registered by calling 4838 register_new_assert_for. That function keeps track of all the 4839 registered assertions to prevent adding unnecessary assertions. 4840 For instance, if a pointer P_4 is dereferenced more than once in a 4841 dominator tree, only the location dominating all the dereference of 4842 P_4 will receive an ASSERT_EXPR. 4843 4844 If this function returns true, then it means that there are names 4845 for which we need to generate ASSERT_EXPRs. Those assertions are 4846 inserted by process_assert_insertions. */ 4847 4848 static bool 4849 find_assert_locations_1 (basic_block bb, sbitmap live) 4850 { 4851 gimple_stmt_iterator si; 4852 gimple last; 4853 gimple phi; 4854 bool need_assert; 4855 4856 need_assert = false; 4857 last = last_stmt (bb); 4858 4859 /* If BB's last statement is a conditional statement involving integer 4860 operands, determine if we need to add ASSERT_EXPRs. */ 4861 if (last 4862 && gimple_code (last) == GIMPLE_COND 4863 && !fp_predicate (last) 4864 && !ZERO_SSA_OPERANDS (last, SSA_OP_USE)) 4865 need_assert |= find_conditional_asserts (bb, last); 4866 4867 /* If BB's last statement is a switch statement involving integer 4868 operands, determine if we need to add ASSERT_EXPRs. */ 4869 if (last 4870 && gimple_code (last) == GIMPLE_SWITCH 4871 && !ZERO_SSA_OPERANDS (last, SSA_OP_USE)) 4872 need_assert |= find_switch_asserts (bb, last); 4873 4874 /* Traverse all the statements in BB marking used names and looking 4875 for statements that may infer assertions for their used operands. */ 4876 for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si)) 4877 { 4878 gimple stmt; 4879 tree op; 4880 ssa_op_iter i; 4881 4882 stmt = gsi_stmt (si); 4883 4884 if (is_gimple_debug (stmt)) 4885 continue; 4886 4887 /* See if we can derive an assertion for any of STMT's operands. */ 4888 FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE) 4889 { 4890 tree value; 4891 enum tree_code comp_code; 4892 4893 /* Mark OP in our live bitmap. */ 4894 SET_BIT (live, SSA_NAME_VERSION (op)); 4895 4896 /* If OP is used in such a way that we can infer a value 4897 range for it, and we don't find a previous assertion for 4898 it, create a new assertion location node for OP. */ 4899 if (infer_value_range (stmt, op, &comp_code, &value)) 4900 { 4901 /* If we are able to infer a nonzero value range for OP, 4902 then walk backwards through the use-def chain to see if OP 4903 was set via a typecast. 4904 4905 If so, then we can also infer a nonzero value range 4906 for the operand of the NOP_EXPR. */ 4907 if (comp_code == NE_EXPR && integer_zerop (value)) 4908 { 4909 tree t = op; 4910 gimple def_stmt = SSA_NAME_DEF_STMT (t); 4911 4912 while (is_gimple_assign (def_stmt) 4913 && gimple_assign_rhs_code (def_stmt) == NOP_EXPR 4914 && TREE_CODE 4915 (gimple_assign_rhs1 (def_stmt)) == SSA_NAME 4916 && POINTER_TYPE_P 4917 (TREE_TYPE (gimple_assign_rhs1 (def_stmt)))) 4918 { 4919 t = gimple_assign_rhs1 (def_stmt); 4920 def_stmt = SSA_NAME_DEF_STMT (t); 4921 4922 /* Note we want to register the assert for the 4923 operand of the NOP_EXPR after SI, not after the 4924 conversion. */ 4925 if (! has_single_use (t)) 4926 { 4927 register_new_assert_for (t, t, comp_code, value, 4928 bb, NULL, si); 4929 need_assert = true; 4930 } 4931 } 4932 } 4933 4934 /* If OP is used only once, namely in this STMT, don't 4935 bother creating an ASSERT_EXPR for it. Such an 4936 ASSERT_EXPR would do nothing but increase compile time. */ 4937 if (!has_single_use (op)) 4938 { 4939 register_new_assert_for (op, op, comp_code, value, 4940 bb, NULL, si); 4941 need_assert = true; 4942 } 4943 } 4944 } 4945 } 4946 4947 /* Traverse all PHI nodes in BB marking used operands. */ 4948 for (si = gsi_start_phis (bb); !gsi_end_p(si); gsi_next (&si)) 4949 { 4950 use_operand_p arg_p; 4951 ssa_op_iter i; 4952 phi = gsi_stmt (si); 4953 4954 FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE) 4955 { 4956 tree arg = USE_FROM_PTR (arg_p); 4957 if (TREE_CODE (arg) == SSA_NAME) 4958 SET_BIT (live, SSA_NAME_VERSION (arg)); 4959 } 4960 } 4961 4962 return need_assert; 4963 } 4964 4965 /* Do an RPO walk over the function computing SSA name liveness 4966 on-the-fly and deciding on assert expressions to insert. 4967 Returns true if there are assert expressions to be inserted. */ 4968 4969 static bool 4970 find_assert_locations (void) 4971 { 4972 int *rpo = XCNEWVEC (int, last_basic_block + NUM_FIXED_BLOCKS); 4973 int *bb_rpo = XCNEWVEC (int, last_basic_block + NUM_FIXED_BLOCKS); 4974 int *last_rpo = XCNEWVEC (int, last_basic_block + NUM_FIXED_BLOCKS); 4975 int rpo_cnt, i; 4976 bool need_asserts; 4977 4978 live = XCNEWVEC (sbitmap, last_basic_block + NUM_FIXED_BLOCKS); 4979 rpo_cnt = pre_and_rev_post_order_compute (NULL, rpo, false); 4980 for (i = 0; i < rpo_cnt; ++i) 4981 bb_rpo[rpo[i]] = i; 4982 4983 need_asserts = false; 4984 for (i = rpo_cnt-1; i >= 0; --i) 4985 { 4986 basic_block bb = BASIC_BLOCK (rpo[i]); 4987 edge e; 4988 edge_iterator ei; 4989 4990 if (!live[rpo[i]]) 4991 { 4992 live[rpo[i]] = sbitmap_alloc (num_ssa_names); 4993 sbitmap_zero (live[rpo[i]]); 4994 } 4995 4996 /* Process BB and update the live information with uses in 4997 this block. */ 4998 need_asserts |= find_assert_locations_1 (bb, live[rpo[i]]); 4999 5000 /* Merge liveness into the predecessor blocks and free it. */ 5001 if (!sbitmap_empty_p (live[rpo[i]])) 5002 { 5003 int pred_rpo = i; 5004 FOR_EACH_EDGE (e, ei, bb->preds) 5005 { 5006 int pred = e->src->index; 5007 if (e->flags & EDGE_DFS_BACK) 5008 continue; 5009 5010 if (!live[pred]) 5011 { 5012 live[pred] = sbitmap_alloc (num_ssa_names); 5013 sbitmap_zero (live[pred]); 5014 } 5015 sbitmap_a_or_b (live[pred], live[pred], live[rpo[i]]); 5016 5017 if (bb_rpo[pred] < pred_rpo) 5018 pred_rpo = bb_rpo[pred]; 5019 } 5020 5021 /* Record the RPO number of the last visited block that needs 5022 live information from this block. */ 5023 last_rpo[rpo[i]] = pred_rpo; 5024 } 5025 else 5026 { 5027 sbitmap_free (live[rpo[i]]); 5028 live[rpo[i]] = NULL; 5029 } 5030 5031 /* We can free all successors live bitmaps if all their 5032 predecessors have been visited already. */ 5033 FOR_EACH_EDGE (e, ei, bb->succs) 5034 if (last_rpo[e->dest->index] == i 5035 && live[e->dest->index]) 5036 { 5037 sbitmap_free (live[e->dest->index]); 5038 live[e->dest->index] = NULL; 5039 } 5040 } 5041 5042 XDELETEVEC (rpo); 5043 XDELETEVEC (bb_rpo); 5044 XDELETEVEC (last_rpo); 5045 for (i = 0; i < last_basic_block + NUM_FIXED_BLOCKS; ++i) 5046 if (live[i]) 5047 sbitmap_free (live[i]); 5048 XDELETEVEC (live); 5049 5050 return need_asserts; 5051 } 5052 5053 /* Create an ASSERT_EXPR for NAME and insert it in the location 5054 indicated by LOC. Return true if we made any edge insertions. */ 5055 5056 static bool 5057 process_assert_insertions_for (tree name, assert_locus_t loc) 5058 { 5059 /* Build the comparison expression NAME_i COMP_CODE VAL. */ 5060 gimple stmt; 5061 tree cond; 5062 gimple assert_stmt; 5063 edge_iterator ei; 5064 edge e; 5065 5066 /* If we have X <=> X do not insert an assert expr for that. */ 5067 if (loc->expr == loc->val) 5068 return false; 5069 5070 cond = build2 (loc->comp_code, boolean_type_node, loc->expr, loc->val); 5071 assert_stmt = build_assert_expr_for (cond, name); 5072 if (loc->e) 5073 { 5074 /* We have been asked to insert the assertion on an edge. This 5075 is used only by COND_EXPR and SWITCH_EXPR assertions. */ 5076 gcc_checking_assert (gimple_code (gsi_stmt (loc->si)) == GIMPLE_COND 5077 || (gimple_code (gsi_stmt (loc->si)) 5078 == GIMPLE_SWITCH)); 5079 5080 gsi_insert_on_edge (loc->e, assert_stmt); 5081 return true; 5082 } 5083 5084 /* Otherwise, we can insert right after LOC->SI iff the 5085 statement must not be the last statement in the block. */ 5086 stmt = gsi_stmt (loc->si); 5087 if (!stmt_ends_bb_p (stmt)) 5088 { 5089 gsi_insert_after (&loc->si, assert_stmt, GSI_SAME_STMT); 5090 return false; 5091 } 5092 5093 /* If STMT must be the last statement in BB, we can only insert new 5094 assertions on the non-abnormal edge out of BB. Note that since 5095 STMT is not control flow, there may only be one non-abnormal edge 5096 out of BB. */ 5097 FOR_EACH_EDGE (e, ei, loc->bb->succs) 5098 if (!(e->flags & EDGE_ABNORMAL)) 5099 { 5100 gsi_insert_on_edge (e, assert_stmt); 5101 return true; 5102 } 5103 5104 gcc_unreachable (); 5105 } 5106 5107 5108 /* Process all the insertions registered for every name N_i registered 5109 in NEED_ASSERT_FOR. The list of assertions to be inserted are 5110 found in ASSERTS_FOR[i]. */ 5111 5112 static void 5113 process_assert_insertions (void) 5114 { 5115 unsigned i; 5116 bitmap_iterator bi; 5117 bool update_edges_p = false; 5118 int num_asserts = 0; 5119 5120 if (dump_file && (dump_flags & TDF_DETAILS)) 5121 dump_all_asserts (dump_file); 5122 5123 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi) 5124 { 5125 assert_locus_t loc = asserts_for[i]; 5126 gcc_assert (loc); 5127 5128 while (loc) 5129 { 5130 assert_locus_t next = loc->next; 5131 update_edges_p |= process_assert_insertions_for (ssa_name (i), loc); 5132 free (loc); 5133 loc = next; 5134 num_asserts++; 5135 } 5136 } 5137 5138 if (update_edges_p) 5139 gsi_commit_edge_inserts (); 5140 5141 statistics_counter_event (cfun, "Number of ASSERT_EXPR expressions inserted", 5142 num_asserts); 5143 } 5144 5145 5146 /* Traverse the flowgraph looking for conditional jumps to insert range 5147 expressions. These range expressions are meant to provide information 5148 to optimizations that need to reason in terms of value ranges. They 5149 will not be expanded into RTL. For instance, given: 5150 5151 x = ... 5152 y = ... 5153 if (x < y) 5154 y = x - 2; 5155 else 5156 x = y + 3; 5157 5158 this pass will transform the code into: 5159 5160 x = ... 5161 y = ... 5162 if (x < y) 5163 { 5164 x = ASSERT_EXPR <x, x < y> 5165 y = x - 2 5166 } 5167 else 5168 { 5169 y = ASSERT_EXPR <y, x <= y> 5170 x = y + 3 5171 } 5172 5173 The idea is that once copy and constant propagation have run, other 5174 optimizations will be able to determine what ranges of values can 'x' 5175 take in different paths of the code, simply by checking the reaching 5176 definition of 'x'. */ 5177 5178 static void 5179 insert_range_assertions (void) 5180 { 5181 need_assert_for = BITMAP_ALLOC (NULL); 5182 asserts_for = XCNEWVEC (assert_locus_t, num_ssa_names); 5183 5184 calculate_dominance_info (CDI_DOMINATORS); 5185 5186 if (find_assert_locations ()) 5187 { 5188 process_assert_insertions (); 5189 update_ssa (TODO_update_ssa_no_phi); 5190 } 5191 5192 if (dump_file && (dump_flags & TDF_DETAILS)) 5193 { 5194 fprintf (dump_file, "\nSSA form after inserting ASSERT_EXPRs\n"); 5195 dump_function_to_file (current_function_decl, dump_file, dump_flags); 5196 } 5197 5198 free (asserts_for); 5199 BITMAP_FREE (need_assert_for); 5200 } 5201 5202 /* Checks one ARRAY_REF in REF, located at LOCUS. Ignores flexible arrays 5203 and "struct" hacks. If VRP can determine that the 5204 array subscript is a constant, check if it is outside valid 5205 range. If the array subscript is a RANGE, warn if it is 5206 non-overlapping with valid range. 5207 IGNORE_OFF_BY_ONE is true if the ARRAY_REF is inside a ADDR_EXPR. */ 5208 5209 static void 5210 check_array_ref (location_t location, tree ref, bool ignore_off_by_one) 5211 { 5212 value_range_t* vr = NULL; 5213 tree low_sub, up_sub; 5214 tree low_bound, up_bound, up_bound_p1; 5215 tree base; 5216 5217 if (TREE_NO_WARNING (ref)) 5218 return; 5219 5220 low_sub = up_sub = TREE_OPERAND (ref, 1); 5221 up_bound = array_ref_up_bound (ref); 5222 5223 /* Can not check flexible arrays. */ 5224 if (!up_bound 5225 || TREE_CODE (up_bound) != INTEGER_CST) 5226 return; 5227 5228 /* Accesses to trailing arrays via pointers may access storage 5229 beyond the types array bounds. */ 5230 base = get_base_address (ref); 5231 if (base && TREE_CODE (base) == MEM_REF) 5232 { 5233 tree cref, next = NULL_TREE; 5234 5235 if (TREE_CODE (TREE_OPERAND (ref, 0)) != COMPONENT_REF) 5236 return; 5237 5238 cref = TREE_OPERAND (ref, 0); 5239 if (TREE_CODE (TREE_TYPE (TREE_OPERAND (cref, 0))) == RECORD_TYPE) 5240 for (next = DECL_CHAIN (TREE_OPERAND (cref, 1)); 5241 next && TREE_CODE (next) != FIELD_DECL; 5242 next = DECL_CHAIN (next)) 5243 ; 5244 5245 /* If this is the last field in a struct type or a field in a 5246 union type do not warn. */ 5247 if (!next) 5248 return; 5249 } 5250 5251 low_bound = array_ref_low_bound (ref); 5252 up_bound_p1 = int_const_binop (PLUS_EXPR, up_bound, integer_one_node); 5253 5254 if (TREE_CODE (low_sub) == SSA_NAME) 5255 { 5256 vr = get_value_range (low_sub); 5257 if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE) 5258 { 5259 low_sub = vr->type == VR_RANGE ? vr->max : vr->min; 5260 up_sub = vr->type == VR_RANGE ? vr->min : vr->max; 5261 } 5262 } 5263 5264 if (vr && vr->type == VR_ANTI_RANGE) 5265 { 5266 if (TREE_CODE (up_sub) == INTEGER_CST 5267 && tree_int_cst_lt (up_bound, up_sub) 5268 && TREE_CODE (low_sub) == INTEGER_CST 5269 && tree_int_cst_lt (low_sub, low_bound)) 5270 { 5271 warning_at (location, OPT_Warray_bounds, 5272 "array subscript is outside array bounds"); 5273 TREE_NO_WARNING (ref) = 1; 5274 } 5275 } 5276 else if (TREE_CODE (up_sub) == INTEGER_CST 5277 && (ignore_off_by_one 5278 ? (tree_int_cst_lt (up_bound, up_sub) 5279 && !tree_int_cst_equal (up_bound_p1, up_sub)) 5280 : (tree_int_cst_lt (up_bound, up_sub) 5281 || tree_int_cst_equal (up_bound_p1, up_sub)))) 5282 { 5283 warning_at (location, OPT_Warray_bounds, 5284 "array subscript is above array bounds"); 5285 TREE_NO_WARNING (ref) = 1; 5286 } 5287 else if (TREE_CODE (low_sub) == INTEGER_CST 5288 && tree_int_cst_lt (low_sub, low_bound)) 5289 { 5290 warning_at (location, OPT_Warray_bounds, 5291 "array subscript is below array bounds"); 5292 TREE_NO_WARNING (ref) = 1; 5293 } 5294 } 5295 5296 /* Searches if the expr T, located at LOCATION computes 5297 address of an ARRAY_REF, and call check_array_ref on it. */ 5298 5299 static void 5300 search_for_addr_array (tree t, location_t location) 5301 { 5302 while (TREE_CODE (t) == SSA_NAME) 5303 { 5304 gimple g = SSA_NAME_DEF_STMT (t); 5305 5306 if (gimple_code (g) != GIMPLE_ASSIGN) 5307 return; 5308 5309 if (get_gimple_rhs_class (gimple_assign_rhs_code (g)) 5310 != GIMPLE_SINGLE_RHS) 5311 return; 5312 5313 t = gimple_assign_rhs1 (g); 5314 } 5315 5316 5317 /* We are only interested in addresses of ARRAY_REF's. */ 5318 if (TREE_CODE (t) != ADDR_EXPR) 5319 return; 5320 5321 /* Check each ARRAY_REFs in the reference chain. */ 5322 do 5323 { 5324 if (TREE_CODE (t) == ARRAY_REF) 5325 check_array_ref (location, t, true /*ignore_off_by_one*/); 5326 5327 t = TREE_OPERAND (t, 0); 5328 } 5329 while (handled_component_p (t)); 5330 5331 if (TREE_CODE (t) == MEM_REF 5332 && TREE_CODE (TREE_OPERAND (t, 0)) == ADDR_EXPR 5333 && !TREE_NO_WARNING (t)) 5334 { 5335 tree tem = TREE_OPERAND (TREE_OPERAND (t, 0), 0); 5336 tree low_bound, up_bound, el_sz; 5337 double_int idx; 5338 if (TREE_CODE (TREE_TYPE (tem)) != ARRAY_TYPE 5339 || TREE_CODE (TREE_TYPE (TREE_TYPE (tem))) == ARRAY_TYPE 5340 || !TYPE_DOMAIN (TREE_TYPE (tem))) 5341 return; 5342 5343 low_bound = TYPE_MIN_VALUE (TYPE_DOMAIN (TREE_TYPE (tem))); 5344 up_bound = TYPE_MAX_VALUE (TYPE_DOMAIN (TREE_TYPE (tem))); 5345 el_sz = TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (tem))); 5346 if (!low_bound 5347 || TREE_CODE (low_bound) != INTEGER_CST 5348 || !up_bound 5349 || TREE_CODE (up_bound) != INTEGER_CST 5350 || !el_sz 5351 || TREE_CODE (el_sz) != INTEGER_CST) 5352 return; 5353 5354 idx = mem_ref_offset (t); 5355 idx = double_int_sdiv (idx, tree_to_double_int (el_sz), TRUNC_DIV_EXPR); 5356 if (double_int_scmp (idx, double_int_zero) < 0) 5357 { 5358 warning_at (location, OPT_Warray_bounds, 5359 "array subscript is below array bounds"); 5360 TREE_NO_WARNING (t) = 1; 5361 } 5362 else if (double_int_scmp (idx, 5363 double_int_add 5364 (double_int_add 5365 (tree_to_double_int (up_bound), 5366 double_int_neg 5367 (tree_to_double_int (low_bound))), 5368 double_int_one)) > 0) 5369 { 5370 warning_at (location, OPT_Warray_bounds, 5371 "array subscript is above array bounds"); 5372 TREE_NO_WARNING (t) = 1; 5373 } 5374 } 5375 } 5376 5377 /* walk_tree() callback that checks if *TP is 5378 an ARRAY_REF inside an ADDR_EXPR (in which an array 5379 subscript one outside the valid range is allowed). Call 5380 check_array_ref for each ARRAY_REF found. The location is 5381 passed in DATA. */ 5382 5383 static tree 5384 check_array_bounds (tree *tp, int *walk_subtree, void *data) 5385 { 5386 tree t = *tp; 5387 struct walk_stmt_info *wi = (struct walk_stmt_info *) data; 5388 location_t location; 5389 5390 if (EXPR_HAS_LOCATION (t)) 5391 location = EXPR_LOCATION (t); 5392 else 5393 { 5394 location_t *locp = (location_t *) wi->info; 5395 location = *locp; 5396 } 5397 5398 *walk_subtree = TRUE; 5399 5400 if (TREE_CODE (t) == ARRAY_REF) 5401 check_array_ref (location, t, false /*ignore_off_by_one*/); 5402 5403 if (TREE_CODE (t) == MEM_REF 5404 || (TREE_CODE (t) == RETURN_EXPR && TREE_OPERAND (t, 0))) 5405 search_for_addr_array (TREE_OPERAND (t, 0), location); 5406 5407 if (TREE_CODE (t) == ADDR_EXPR) 5408 *walk_subtree = FALSE; 5409 5410 return NULL_TREE; 5411 } 5412 5413 /* Walk over all statements of all reachable BBs and call check_array_bounds 5414 on them. */ 5415 5416 static void 5417 check_all_array_refs (void) 5418 { 5419 basic_block bb; 5420 gimple_stmt_iterator si; 5421 5422 FOR_EACH_BB (bb) 5423 { 5424 edge_iterator ei; 5425 edge e; 5426 bool executable = false; 5427 5428 /* Skip blocks that were found to be unreachable. */ 5429 FOR_EACH_EDGE (e, ei, bb->preds) 5430 executable |= !!(e->flags & EDGE_EXECUTABLE); 5431 if (!executable) 5432 continue; 5433 5434 for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si)) 5435 { 5436 gimple stmt = gsi_stmt (si); 5437 struct walk_stmt_info wi; 5438 if (!gimple_has_location (stmt)) 5439 continue; 5440 5441 if (is_gimple_call (stmt)) 5442 { 5443 size_t i; 5444 size_t n = gimple_call_num_args (stmt); 5445 for (i = 0; i < n; i++) 5446 { 5447 tree arg = gimple_call_arg (stmt, i); 5448 search_for_addr_array (arg, gimple_location (stmt)); 5449 } 5450 } 5451 else 5452 { 5453 memset (&wi, 0, sizeof (wi)); 5454 wi.info = CONST_CAST (void *, (const void *) 5455 gimple_location_ptr (stmt)); 5456 5457 walk_gimple_op (gsi_stmt (si), 5458 check_array_bounds, 5459 &wi); 5460 } 5461 } 5462 } 5463 } 5464 5465 /* Convert range assertion expressions into the implied copies and 5466 copy propagate away the copies. Doing the trivial copy propagation 5467 here avoids the need to run the full copy propagation pass after 5468 VRP. 5469 5470 FIXME, this will eventually lead to copy propagation removing the 5471 names that had useful range information attached to them. For 5472 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>, 5473 then N_i will have the range [3, +INF]. 5474 5475 However, by converting the assertion into the implied copy 5476 operation N_i = N_j, we will then copy-propagate N_j into the uses 5477 of N_i and lose the range information. We may want to hold on to 5478 ASSERT_EXPRs a little while longer as the ranges could be used in 5479 things like jump threading. 5480 5481 The problem with keeping ASSERT_EXPRs around is that passes after 5482 VRP need to handle them appropriately. 5483 5484 Another approach would be to make the range information a first 5485 class property of the SSA_NAME so that it can be queried from 5486 any pass. This is made somewhat more complex by the need for 5487 multiple ranges to be associated with one SSA_NAME. */ 5488 5489 static void 5490 remove_range_assertions (void) 5491 { 5492 basic_block bb; 5493 gimple_stmt_iterator si; 5494 5495 /* Note that the BSI iterator bump happens at the bottom of the 5496 loop and no bump is necessary if we're removing the statement 5497 referenced by the current BSI. */ 5498 FOR_EACH_BB (bb) 5499 for (si = gsi_start_bb (bb); !gsi_end_p (si);) 5500 { 5501 gimple stmt = gsi_stmt (si); 5502 gimple use_stmt; 5503 5504 if (is_gimple_assign (stmt) 5505 && gimple_assign_rhs_code (stmt) == ASSERT_EXPR) 5506 { 5507 tree rhs = gimple_assign_rhs1 (stmt); 5508 tree var; 5509 tree cond = fold (ASSERT_EXPR_COND (rhs)); 5510 use_operand_p use_p; 5511 imm_use_iterator iter; 5512 5513 gcc_assert (cond != boolean_false_node); 5514 5515 /* Propagate the RHS into every use of the LHS. */ 5516 var = ASSERT_EXPR_VAR (rhs); 5517 FOR_EACH_IMM_USE_STMT (use_stmt, iter, 5518 gimple_assign_lhs (stmt)) 5519 FOR_EACH_IMM_USE_ON_STMT (use_p, iter) 5520 { 5521 SET_USE (use_p, var); 5522 gcc_assert (TREE_CODE (var) == SSA_NAME); 5523 } 5524 5525 /* And finally, remove the copy, it is not needed. */ 5526 gsi_remove (&si, true); 5527 release_defs (stmt); 5528 } 5529 else 5530 gsi_next (&si); 5531 } 5532 } 5533 5534 5535 /* Return true if STMT is interesting for VRP. */ 5536 5537 static bool 5538 stmt_interesting_for_vrp (gimple stmt) 5539 { 5540 if (gimple_code (stmt) == GIMPLE_PHI 5541 && is_gimple_reg (gimple_phi_result (stmt)) 5542 && (INTEGRAL_TYPE_P (TREE_TYPE (gimple_phi_result (stmt))) 5543 || POINTER_TYPE_P (TREE_TYPE (gimple_phi_result (stmt))))) 5544 return true; 5545 else if (is_gimple_assign (stmt) || is_gimple_call (stmt)) 5546 { 5547 tree lhs = gimple_get_lhs (stmt); 5548 5549 /* In general, assignments with virtual operands are not useful 5550 for deriving ranges, with the obvious exception of calls to 5551 builtin functions. */ 5552 if (lhs && TREE_CODE (lhs) == SSA_NAME 5553 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs)) 5554 || POINTER_TYPE_P (TREE_TYPE (lhs))) 5555 && ((is_gimple_call (stmt) 5556 && gimple_call_fndecl (stmt) != NULL_TREE 5557 && DECL_BUILT_IN (gimple_call_fndecl (stmt))) 5558 || !gimple_vuse (stmt))) 5559 return true; 5560 } 5561 else if (gimple_code (stmt) == GIMPLE_COND 5562 || gimple_code (stmt) == GIMPLE_SWITCH) 5563 return true; 5564 5565 return false; 5566 } 5567 5568 5569 /* Initialize local data structures for VRP. */ 5570 5571 static void 5572 vrp_initialize (void) 5573 { 5574 basic_block bb; 5575 5576 values_propagated = false; 5577 num_vr_values = num_ssa_names; 5578 vr_value = XCNEWVEC (value_range_t *, num_vr_values); 5579 vr_phi_edge_counts = XCNEWVEC (int, num_ssa_names); 5580 5581 FOR_EACH_BB (bb) 5582 { 5583 gimple_stmt_iterator si; 5584 5585 for (si = gsi_start_phis (bb); !gsi_end_p (si); gsi_next (&si)) 5586 { 5587 gimple phi = gsi_stmt (si); 5588 if (!stmt_interesting_for_vrp (phi)) 5589 { 5590 tree lhs = PHI_RESULT (phi); 5591 set_value_range_to_varying (get_value_range (lhs)); 5592 prop_set_simulate_again (phi, false); 5593 } 5594 else 5595 prop_set_simulate_again (phi, true); 5596 } 5597 5598 for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si)) 5599 { 5600 gimple stmt = gsi_stmt (si); 5601 5602 /* If the statement is a control insn, then we do not 5603 want to avoid simulating the statement once. Failure 5604 to do so means that those edges will never get added. */ 5605 if (stmt_ends_bb_p (stmt)) 5606 prop_set_simulate_again (stmt, true); 5607 else if (!stmt_interesting_for_vrp (stmt)) 5608 { 5609 ssa_op_iter i; 5610 tree def; 5611 FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_DEF) 5612 set_value_range_to_varying (get_value_range (def)); 5613 prop_set_simulate_again (stmt, false); 5614 } 5615 else 5616 prop_set_simulate_again (stmt, true); 5617 } 5618 } 5619 } 5620 5621 /* Return the singleton value-range for NAME or NAME. */ 5622 5623 static inline tree 5624 vrp_valueize (tree name) 5625 { 5626 if (TREE_CODE (name) == SSA_NAME) 5627 { 5628 value_range_t *vr = get_value_range (name); 5629 if (vr->type == VR_RANGE 5630 && (vr->min == vr->max 5631 || operand_equal_p (vr->min, vr->max, 0))) 5632 return vr->min; 5633 } 5634 return name; 5635 } 5636 5637 /* Visit assignment STMT. If it produces an interesting range, record 5638 the SSA name in *OUTPUT_P. */ 5639 5640 static enum ssa_prop_result 5641 vrp_visit_assignment_or_call (gimple stmt, tree *output_p) 5642 { 5643 tree def, lhs; 5644 ssa_op_iter iter; 5645 enum gimple_code code = gimple_code (stmt); 5646 lhs = gimple_get_lhs (stmt); 5647 5648 /* We only keep track of ranges in integral and pointer types. */ 5649 if (TREE_CODE (lhs) == SSA_NAME 5650 && ((INTEGRAL_TYPE_P (TREE_TYPE (lhs)) 5651 /* It is valid to have NULL MIN/MAX values on a type. See 5652 build_range_type. */ 5653 && TYPE_MIN_VALUE (TREE_TYPE (lhs)) 5654 && TYPE_MAX_VALUE (TREE_TYPE (lhs))) 5655 || POINTER_TYPE_P (TREE_TYPE (lhs)))) 5656 { 5657 value_range_t new_vr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; 5658 5659 /* Try folding the statement to a constant first. */ 5660 tree tem = gimple_fold_stmt_to_constant (stmt, vrp_valueize); 5661 if (tem && !is_overflow_infinity (tem)) 5662 set_value_range (&new_vr, VR_RANGE, tem, tem, NULL); 5663 /* Then dispatch to value-range extracting functions. */ 5664 else if (code == GIMPLE_CALL) 5665 extract_range_basic (&new_vr, stmt); 5666 else 5667 extract_range_from_assignment (&new_vr, stmt); 5668 5669 if (update_value_range (lhs, &new_vr)) 5670 { 5671 *output_p = lhs; 5672 5673 if (dump_file && (dump_flags & TDF_DETAILS)) 5674 { 5675 fprintf (dump_file, "Found new range for "); 5676 print_generic_expr (dump_file, lhs, 0); 5677 fprintf (dump_file, ": "); 5678 dump_value_range (dump_file, &new_vr); 5679 fprintf (dump_file, "\n\n"); 5680 } 5681 5682 if (new_vr.type == VR_VARYING) 5683 return SSA_PROP_VARYING; 5684 5685 return SSA_PROP_INTERESTING; 5686 } 5687 5688 return SSA_PROP_NOT_INTERESTING; 5689 } 5690 5691 /* Every other statement produces no useful ranges. */ 5692 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF) 5693 set_value_range_to_varying (get_value_range (def)); 5694 5695 return SSA_PROP_VARYING; 5696 } 5697 5698 /* Helper that gets the value range of the SSA_NAME with version I 5699 or a symbolic range containing the SSA_NAME only if the value range 5700 is varying or undefined. */ 5701 5702 static inline value_range_t 5703 get_vr_for_comparison (int i) 5704 { 5705 value_range_t vr = *get_value_range (ssa_name (i)); 5706 5707 /* If name N_i does not have a valid range, use N_i as its own 5708 range. This allows us to compare against names that may 5709 have N_i in their ranges. */ 5710 if (vr.type == VR_VARYING || vr.type == VR_UNDEFINED) 5711 { 5712 vr.type = VR_RANGE; 5713 vr.min = ssa_name (i); 5714 vr.max = ssa_name (i); 5715 } 5716 5717 return vr; 5718 } 5719 5720 /* Compare all the value ranges for names equivalent to VAR with VAL 5721 using comparison code COMP. Return the same value returned by 5722 compare_range_with_value, including the setting of 5723 *STRICT_OVERFLOW_P. */ 5724 5725 static tree 5726 compare_name_with_value (enum tree_code comp, tree var, tree val, 5727 bool *strict_overflow_p) 5728 { 5729 bitmap_iterator bi; 5730 unsigned i; 5731 bitmap e; 5732 tree retval, t; 5733 int used_strict_overflow; 5734 bool sop; 5735 value_range_t equiv_vr; 5736 5737 /* Get the set of equivalences for VAR. */ 5738 e = get_value_range (var)->equiv; 5739 5740 /* Start at -1. Set it to 0 if we do a comparison without relying 5741 on overflow, or 1 if all comparisons rely on overflow. */ 5742 used_strict_overflow = -1; 5743 5744 /* Compare vars' value range with val. */ 5745 equiv_vr = get_vr_for_comparison (SSA_NAME_VERSION (var)); 5746 sop = false; 5747 retval = compare_range_with_value (comp, &equiv_vr, val, &sop); 5748 if (retval) 5749 used_strict_overflow = sop ? 1 : 0; 5750 5751 /* If the equiv set is empty we have done all work we need to do. */ 5752 if (e == NULL) 5753 { 5754 if (retval 5755 && used_strict_overflow > 0) 5756 *strict_overflow_p = true; 5757 return retval; 5758 } 5759 5760 EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi) 5761 { 5762 equiv_vr = get_vr_for_comparison (i); 5763 sop = false; 5764 t = compare_range_with_value (comp, &equiv_vr, val, &sop); 5765 if (t) 5766 { 5767 /* If we get different answers from different members 5768 of the equivalence set this check must be in a dead 5769 code region. Folding it to a trap representation 5770 would be correct here. For now just return don't-know. */ 5771 if (retval != NULL 5772 && t != retval) 5773 { 5774 retval = NULL_TREE; 5775 break; 5776 } 5777 retval = t; 5778 5779 if (!sop) 5780 used_strict_overflow = 0; 5781 else if (used_strict_overflow < 0) 5782 used_strict_overflow = 1; 5783 } 5784 } 5785 5786 if (retval 5787 && used_strict_overflow > 0) 5788 *strict_overflow_p = true; 5789 5790 return retval; 5791 } 5792 5793 5794 /* Given a comparison code COMP and names N1 and N2, compare all the 5795 ranges equivalent to N1 against all the ranges equivalent to N2 5796 to determine the value of N1 COMP N2. Return the same value 5797 returned by compare_ranges. Set *STRICT_OVERFLOW_P to indicate 5798 whether we relied on an overflow infinity in the comparison. */ 5799 5800 5801 static tree 5802 compare_names (enum tree_code comp, tree n1, tree n2, 5803 bool *strict_overflow_p) 5804 { 5805 tree t, retval; 5806 bitmap e1, e2; 5807 bitmap_iterator bi1, bi2; 5808 unsigned i1, i2; 5809 int used_strict_overflow; 5810 static bitmap_obstack *s_obstack = NULL; 5811 static bitmap s_e1 = NULL, s_e2 = NULL; 5812 5813 /* Compare the ranges of every name equivalent to N1 against the 5814 ranges of every name equivalent to N2. */ 5815 e1 = get_value_range (n1)->equiv; 5816 e2 = get_value_range (n2)->equiv; 5817 5818 /* Use the fake bitmaps if e1 or e2 are not available. */ 5819 if (s_obstack == NULL) 5820 { 5821 s_obstack = XNEW (bitmap_obstack); 5822 bitmap_obstack_initialize (s_obstack); 5823 s_e1 = BITMAP_ALLOC (s_obstack); 5824 s_e2 = BITMAP_ALLOC (s_obstack); 5825 } 5826 if (e1 == NULL) 5827 e1 = s_e1; 5828 if (e2 == NULL) 5829 e2 = s_e2; 5830 5831 /* Add N1 and N2 to their own set of equivalences to avoid 5832 duplicating the body of the loop just to check N1 and N2 5833 ranges. */ 5834 bitmap_set_bit (e1, SSA_NAME_VERSION (n1)); 5835 bitmap_set_bit (e2, SSA_NAME_VERSION (n2)); 5836 5837 /* If the equivalence sets have a common intersection, then the two 5838 names can be compared without checking their ranges. */ 5839 if (bitmap_intersect_p (e1, e2)) 5840 { 5841 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1)); 5842 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2)); 5843 5844 return (comp == EQ_EXPR || comp == GE_EXPR || comp == LE_EXPR) 5845 ? boolean_true_node 5846 : boolean_false_node; 5847 } 5848 5849 /* Start at -1. Set it to 0 if we do a comparison without relying 5850 on overflow, or 1 if all comparisons rely on overflow. */ 5851 used_strict_overflow = -1; 5852 5853 /* Otherwise, compare all the equivalent ranges. First, add N1 and 5854 N2 to their own set of equivalences to avoid duplicating the body 5855 of the loop just to check N1 and N2 ranges. */ 5856 EXECUTE_IF_SET_IN_BITMAP (e1, 0, i1, bi1) 5857 { 5858 value_range_t vr1 = get_vr_for_comparison (i1); 5859 5860 t = retval = NULL_TREE; 5861 EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2) 5862 { 5863 bool sop = false; 5864 5865 value_range_t vr2 = get_vr_for_comparison (i2); 5866 5867 t = compare_ranges (comp, &vr1, &vr2, &sop); 5868 if (t) 5869 { 5870 /* If we get different answers from different members 5871 of the equivalence set this check must be in a dead 5872 code region. Folding it to a trap representation 5873 would be correct here. For now just return don't-know. */ 5874 if (retval != NULL 5875 && t != retval) 5876 { 5877 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1)); 5878 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2)); 5879 return NULL_TREE; 5880 } 5881 retval = t; 5882 5883 if (!sop) 5884 used_strict_overflow = 0; 5885 else if (used_strict_overflow < 0) 5886 used_strict_overflow = 1; 5887 } 5888 } 5889 5890 if (retval) 5891 { 5892 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1)); 5893 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2)); 5894 if (used_strict_overflow > 0) 5895 *strict_overflow_p = true; 5896 return retval; 5897 } 5898 } 5899 5900 /* None of the equivalent ranges are useful in computing this 5901 comparison. */ 5902 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1)); 5903 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2)); 5904 return NULL_TREE; 5905 } 5906 5907 /* Helper function for vrp_evaluate_conditional_warnv. */ 5908 5909 static tree 5910 vrp_evaluate_conditional_warnv_with_ops_using_ranges (enum tree_code code, 5911 tree op0, tree op1, 5912 bool * strict_overflow_p) 5913 { 5914 value_range_t *vr0, *vr1; 5915 5916 vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL; 5917 vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL; 5918 5919 if (vr0 && vr1) 5920 return compare_ranges (code, vr0, vr1, strict_overflow_p); 5921 else if (vr0 && vr1 == NULL) 5922 return compare_range_with_value (code, vr0, op1, strict_overflow_p); 5923 else if (vr0 == NULL && vr1) 5924 return (compare_range_with_value 5925 (swap_tree_comparison (code), vr1, op0, strict_overflow_p)); 5926 return NULL; 5927 } 5928 5929 /* Helper function for vrp_evaluate_conditional_warnv. */ 5930 5931 static tree 5932 vrp_evaluate_conditional_warnv_with_ops (enum tree_code code, tree op0, 5933 tree op1, bool use_equiv_p, 5934 bool *strict_overflow_p, bool *only_ranges) 5935 { 5936 tree ret; 5937 if (only_ranges) 5938 *only_ranges = true; 5939 5940 /* We only deal with integral and pointer types. */ 5941 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0)) 5942 && !POINTER_TYPE_P (TREE_TYPE (op0))) 5943 return NULL_TREE; 5944 5945 if (use_equiv_p) 5946 { 5947 if (only_ranges 5948 && (ret = vrp_evaluate_conditional_warnv_with_ops_using_ranges 5949 (code, op0, op1, strict_overflow_p))) 5950 return ret; 5951 *only_ranges = false; 5952 if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME) 5953 return compare_names (code, op0, op1, strict_overflow_p); 5954 else if (TREE_CODE (op0) == SSA_NAME) 5955 return compare_name_with_value (code, op0, op1, strict_overflow_p); 5956 else if (TREE_CODE (op1) == SSA_NAME) 5957 return (compare_name_with_value 5958 (swap_tree_comparison (code), op1, op0, strict_overflow_p)); 5959 } 5960 else 5961 return vrp_evaluate_conditional_warnv_with_ops_using_ranges (code, op0, op1, 5962 strict_overflow_p); 5963 return NULL_TREE; 5964 } 5965 5966 /* Given (CODE OP0 OP1) within STMT, try to simplify it based on value range 5967 information. Return NULL if the conditional can not be evaluated. 5968 The ranges of all the names equivalent with the operands in COND 5969 will be used when trying to compute the value. If the result is 5970 based on undefined signed overflow, issue a warning if 5971 appropriate. */ 5972 5973 static tree 5974 vrp_evaluate_conditional (enum tree_code code, tree op0, tree op1, gimple stmt) 5975 { 5976 bool sop; 5977 tree ret; 5978 bool only_ranges; 5979 5980 /* Some passes and foldings leak constants with overflow flag set 5981 into the IL. Avoid doing wrong things with these and bail out. */ 5982 if ((TREE_CODE (op0) == INTEGER_CST 5983 && TREE_OVERFLOW (op0)) 5984 || (TREE_CODE (op1) == INTEGER_CST 5985 && TREE_OVERFLOW (op1))) 5986 return NULL_TREE; 5987 5988 sop = false; 5989 ret = vrp_evaluate_conditional_warnv_with_ops (code, op0, op1, true, &sop, 5990 &only_ranges); 5991 5992 if (ret && sop) 5993 { 5994 enum warn_strict_overflow_code wc; 5995 const char* warnmsg; 5996 5997 if (is_gimple_min_invariant (ret)) 5998 { 5999 wc = WARN_STRICT_OVERFLOW_CONDITIONAL; 6000 warnmsg = G_("assuming signed overflow does not occur when " 6001 "simplifying conditional to constant"); 6002 } 6003 else 6004 { 6005 wc = WARN_STRICT_OVERFLOW_COMPARISON; 6006 warnmsg = G_("assuming signed overflow does not occur when " 6007 "simplifying conditional"); 6008 } 6009 6010 if (issue_strict_overflow_warning (wc)) 6011 { 6012 location_t location; 6013 6014 if (!gimple_has_location (stmt)) 6015 location = input_location; 6016 else 6017 location = gimple_location (stmt); 6018 warning_at (location, OPT_Wstrict_overflow, "%s", warnmsg); 6019 } 6020 } 6021 6022 if (warn_type_limits 6023 && ret && only_ranges 6024 && TREE_CODE_CLASS (code) == tcc_comparison 6025 && TREE_CODE (op0) == SSA_NAME) 6026 { 6027 /* If the comparison is being folded and the operand on the LHS 6028 is being compared against a constant value that is outside of 6029 the natural range of OP0's type, then the predicate will 6030 always fold regardless of the value of OP0. If -Wtype-limits 6031 was specified, emit a warning. */ 6032 tree type = TREE_TYPE (op0); 6033 value_range_t *vr0 = get_value_range (op0); 6034 6035 if (vr0->type != VR_VARYING 6036 && INTEGRAL_TYPE_P (type) 6037 && vrp_val_is_min (vr0->min) 6038 && vrp_val_is_max (vr0->max) 6039 && is_gimple_min_invariant (op1)) 6040 { 6041 location_t location; 6042 6043 if (!gimple_has_location (stmt)) 6044 location = input_location; 6045 else 6046 location = gimple_location (stmt); 6047 6048 warning_at (location, OPT_Wtype_limits, 6049 integer_zerop (ret) 6050 ? G_("comparison always false " 6051 "due to limited range of data type") 6052 : G_("comparison always true " 6053 "due to limited range of data type")); 6054 } 6055 } 6056 6057 return ret; 6058 } 6059 6060 6061 /* Visit conditional statement STMT. If we can determine which edge 6062 will be taken out of STMT's basic block, record it in 6063 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return 6064 SSA_PROP_VARYING. */ 6065 6066 static enum ssa_prop_result 6067 vrp_visit_cond_stmt (gimple stmt, edge *taken_edge_p) 6068 { 6069 tree val; 6070 bool sop; 6071 6072 *taken_edge_p = NULL; 6073 6074 if (dump_file && (dump_flags & TDF_DETAILS)) 6075 { 6076 tree use; 6077 ssa_op_iter i; 6078 6079 fprintf (dump_file, "\nVisiting conditional with predicate: "); 6080 print_gimple_stmt (dump_file, stmt, 0, 0); 6081 fprintf (dump_file, "\nWith known ranges\n"); 6082 6083 FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE) 6084 { 6085 fprintf (dump_file, "\t"); 6086 print_generic_expr (dump_file, use, 0); 6087 fprintf (dump_file, ": "); 6088 dump_value_range (dump_file, vr_value[SSA_NAME_VERSION (use)]); 6089 } 6090 6091 fprintf (dump_file, "\n"); 6092 } 6093 6094 /* Compute the value of the predicate COND by checking the known 6095 ranges of each of its operands. 6096 6097 Note that we cannot evaluate all the equivalent ranges here 6098 because those ranges may not yet be final and with the current 6099 propagation strategy, we cannot determine when the value ranges 6100 of the names in the equivalence set have changed. 6101 6102 For instance, given the following code fragment 6103 6104 i_5 = PHI <8, i_13> 6105 ... 6106 i_14 = ASSERT_EXPR <i_5, i_5 != 0> 6107 if (i_14 == 1) 6108 ... 6109 6110 Assume that on the first visit to i_14, i_5 has the temporary 6111 range [8, 8] because the second argument to the PHI function is 6112 not yet executable. We derive the range ~[0, 0] for i_14 and the 6113 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for 6114 the first time, since i_14 is equivalent to the range [8, 8], we 6115 determine that the predicate is always false. 6116 6117 On the next round of propagation, i_13 is determined to be 6118 VARYING, which causes i_5 to drop down to VARYING. So, another 6119 visit to i_14 is scheduled. In this second visit, we compute the 6120 exact same range and equivalence set for i_14, namely ~[0, 0] and 6121 { i_5 }. But we did not have the previous range for i_5 6122 registered, so vrp_visit_assignment thinks that the range for 6123 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)' 6124 is not visited again, which stops propagation from visiting 6125 statements in the THEN clause of that if(). 6126 6127 To properly fix this we would need to keep the previous range 6128 value for the names in the equivalence set. This way we would've 6129 discovered that from one visit to the other i_5 changed from 6130 range [8, 8] to VR_VARYING. 6131 6132 However, fixing this apparent limitation may not be worth the 6133 additional checking. Testing on several code bases (GCC, DLV, 6134 MICO, TRAMP3D and SPEC2000) showed that doing this results in 6135 4 more predicates folded in SPEC. */ 6136 sop = false; 6137 6138 val = vrp_evaluate_conditional_warnv_with_ops (gimple_cond_code (stmt), 6139 gimple_cond_lhs (stmt), 6140 gimple_cond_rhs (stmt), 6141 false, &sop, NULL); 6142 if (val) 6143 { 6144 if (!sop) 6145 *taken_edge_p = find_taken_edge (gimple_bb (stmt), val); 6146 else 6147 { 6148 if (dump_file && (dump_flags & TDF_DETAILS)) 6149 fprintf (dump_file, 6150 "\nIgnoring predicate evaluation because " 6151 "it assumes that signed overflow is undefined"); 6152 val = NULL_TREE; 6153 } 6154 } 6155 6156 if (dump_file && (dump_flags & TDF_DETAILS)) 6157 { 6158 fprintf (dump_file, "\nPredicate evaluates to: "); 6159 if (val == NULL_TREE) 6160 fprintf (dump_file, "DON'T KNOW\n"); 6161 else 6162 print_generic_stmt (dump_file, val, 0); 6163 } 6164 6165 return (*taken_edge_p) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING; 6166 } 6167 6168 /* Searches the case label vector VEC for the index *IDX of the CASE_LABEL 6169 that includes the value VAL. The search is restricted to the range 6170 [START_IDX, n - 1] where n is the size of VEC. 6171 6172 If there is a CASE_LABEL for VAL, its index is placed in IDX and true is 6173 returned. 6174 6175 If there is no CASE_LABEL for VAL and there is one that is larger than VAL, 6176 it is placed in IDX and false is returned. 6177 6178 If VAL is larger than any CASE_LABEL, n is placed on IDX and false is 6179 returned. */ 6180 6181 static bool 6182 find_case_label_index (gimple stmt, size_t start_idx, tree val, size_t *idx) 6183 { 6184 size_t n = gimple_switch_num_labels (stmt); 6185 size_t low, high; 6186 6187 /* Find case label for minimum of the value range or the next one. 6188 At each iteration we are searching in [low, high - 1]. */ 6189 6190 for (low = start_idx, high = n; high != low; ) 6191 { 6192 tree t; 6193 int cmp; 6194 /* Note that i != high, so we never ask for n. */ 6195 size_t i = (high + low) / 2; 6196 t = gimple_switch_label (stmt, i); 6197 6198 /* Cache the result of comparing CASE_LOW and val. */ 6199 cmp = tree_int_cst_compare (CASE_LOW (t), val); 6200 6201 if (cmp == 0) 6202 { 6203 /* Ranges cannot be empty. */ 6204 *idx = i; 6205 return true; 6206 } 6207 else if (cmp > 0) 6208 high = i; 6209 else 6210 { 6211 low = i + 1; 6212 if (CASE_HIGH (t) != NULL 6213 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0) 6214 { 6215 *idx = i; 6216 return true; 6217 } 6218 } 6219 } 6220 6221 *idx = high; 6222 return false; 6223 } 6224 6225 /* Searches the case label vector VEC for the range of CASE_LABELs that is used 6226 for values between MIN and MAX. The first index is placed in MIN_IDX. The 6227 last index is placed in MAX_IDX. If the range of CASE_LABELs is empty 6228 then MAX_IDX < MIN_IDX. 6229 Returns true if the default label is not needed. */ 6230 6231 static bool 6232 find_case_label_range (gimple stmt, tree min, tree max, size_t *min_idx, 6233 size_t *max_idx) 6234 { 6235 size_t i, j; 6236 bool min_take_default = !find_case_label_index (stmt, 1, min, &i); 6237 bool max_take_default = !find_case_label_index (stmt, i, max, &j); 6238 6239 if (i == j 6240 && min_take_default 6241 && max_take_default) 6242 { 6243 /* Only the default case label reached. 6244 Return an empty range. */ 6245 *min_idx = 1; 6246 *max_idx = 0; 6247 return false; 6248 } 6249 else 6250 { 6251 bool take_default = min_take_default || max_take_default; 6252 tree low, high; 6253 size_t k; 6254 6255 if (max_take_default) 6256 j--; 6257 6258 /* If the case label range is continuous, we do not need 6259 the default case label. Verify that. */ 6260 high = CASE_LOW (gimple_switch_label (stmt, i)); 6261 if (CASE_HIGH (gimple_switch_label (stmt, i))) 6262 high = CASE_HIGH (gimple_switch_label (stmt, i)); 6263 for (k = i + 1; k <= j; ++k) 6264 { 6265 low = CASE_LOW (gimple_switch_label (stmt, k)); 6266 if (!integer_onep (int_const_binop (MINUS_EXPR, low, high))) 6267 { 6268 take_default = true; 6269 break; 6270 } 6271 high = low; 6272 if (CASE_HIGH (gimple_switch_label (stmt, k))) 6273 high = CASE_HIGH (gimple_switch_label (stmt, k)); 6274 } 6275 6276 *min_idx = i; 6277 *max_idx = j; 6278 return !take_default; 6279 } 6280 } 6281 6282 /* Visit switch statement STMT. If we can determine which edge 6283 will be taken out of STMT's basic block, record it in 6284 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return 6285 SSA_PROP_VARYING. */ 6286 6287 static enum ssa_prop_result 6288 vrp_visit_switch_stmt (gimple stmt, edge *taken_edge_p) 6289 { 6290 tree op, val; 6291 value_range_t *vr; 6292 size_t i = 0, j = 0; 6293 bool take_default; 6294 6295 *taken_edge_p = NULL; 6296 op = gimple_switch_index (stmt); 6297 if (TREE_CODE (op) != SSA_NAME) 6298 return SSA_PROP_VARYING; 6299 6300 vr = get_value_range (op); 6301 if (dump_file && (dump_flags & TDF_DETAILS)) 6302 { 6303 fprintf (dump_file, "\nVisiting switch expression with operand "); 6304 print_generic_expr (dump_file, op, 0); 6305 fprintf (dump_file, " with known range "); 6306 dump_value_range (dump_file, vr); 6307 fprintf (dump_file, "\n"); 6308 } 6309 6310 if (vr->type != VR_RANGE 6311 || symbolic_range_p (vr)) 6312 return SSA_PROP_VARYING; 6313 6314 /* Find the single edge that is taken from the switch expression. */ 6315 take_default = !find_case_label_range (stmt, vr->min, vr->max, &i, &j); 6316 6317 /* Check if the range spans no CASE_LABEL. If so, we only reach the default 6318 label */ 6319 if (j < i) 6320 { 6321 gcc_assert (take_default); 6322 val = gimple_switch_default_label (stmt); 6323 } 6324 else 6325 { 6326 /* Check if labels with index i to j and maybe the default label 6327 are all reaching the same label. */ 6328 6329 val = gimple_switch_label (stmt, i); 6330 if (take_default 6331 && CASE_LABEL (gimple_switch_default_label (stmt)) 6332 != CASE_LABEL (val)) 6333 { 6334 if (dump_file && (dump_flags & TDF_DETAILS)) 6335 fprintf (dump_file, " not a single destination for this " 6336 "range\n"); 6337 return SSA_PROP_VARYING; 6338 } 6339 for (++i; i <= j; ++i) 6340 { 6341 if (CASE_LABEL (gimple_switch_label (stmt, i)) != CASE_LABEL (val)) 6342 { 6343 if (dump_file && (dump_flags & TDF_DETAILS)) 6344 fprintf (dump_file, " not a single destination for this " 6345 "range\n"); 6346 return SSA_PROP_VARYING; 6347 } 6348 } 6349 } 6350 6351 *taken_edge_p = find_edge (gimple_bb (stmt), 6352 label_to_block (CASE_LABEL (val))); 6353 6354 if (dump_file && (dump_flags & TDF_DETAILS)) 6355 { 6356 fprintf (dump_file, " will take edge to "); 6357 print_generic_stmt (dump_file, CASE_LABEL (val), 0); 6358 } 6359 6360 return SSA_PROP_INTERESTING; 6361 } 6362 6363 6364 /* Evaluate statement STMT. If the statement produces a useful range, 6365 return SSA_PROP_INTERESTING and record the SSA name with the 6366 interesting range into *OUTPUT_P. 6367 6368 If STMT is a conditional branch and we can determine its truth 6369 value, the taken edge is recorded in *TAKEN_EDGE_P. 6370 6371 If STMT produces a varying value, return SSA_PROP_VARYING. */ 6372 6373 static enum ssa_prop_result 6374 vrp_visit_stmt (gimple stmt, edge *taken_edge_p, tree *output_p) 6375 { 6376 tree def; 6377 ssa_op_iter iter; 6378 6379 if (dump_file && (dump_flags & TDF_DETAILS)) 6380 { 6381 fprintf (dump_file, "\nVisiting statement:\n"); 6382 print_gimple_stmt (dump_file, stmt, 0, dump_flags); 6383 fprintf (dump_file, "\n"); 6384 } 6385 6386 if (!stmt_interesting_for_vrp (stmt)) 6387 gcc_assert (stmt_ends_bb_p (stmt)); 6388 else if (is_gimple_assign (stmt) || is_gimple_call (stmt)) 6389 { 6390 /* In general, assignments with virtual operands are not useful 6391 for deriving ranges, with the obvious exception of calls to 6392 builtin functions. */ 6393 if ((is_gimple_call (stmt) 6394 && gimple_call_fndecl (stmt) != NULL_TREE 6395 && DECL_BUILT_IN (gimple_call_fndecl (stmt))) 6396 || !gimple_vuse (stmt)) 6397 return vrp_visit_assignment_or_call (stmt, output_p); 6398 } 6399 else if (gimple_code (stmt) == GIMPLE_COND) 6400 return vrp_visit_cond_stmt (stmt, taken_edge_p); 6401 else if (gimple_code (stmt) == GIMPLE_SWITCH) 6402 return vrp_visit_switch_stmt (stmt, taken_edge_p); 6403 6404 /* All other statements produce nothing of interest for VRP, so mark 6405 their outputs varying and prevent further simulation. */ 6406 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF) 6407 set_value_range_to_varying (get_value_range (def)); 6408 6409 return SSA_PROP_VARYING; 6410 } 6411 6412 6413 /* Meet operation for value ranges. Given two value ranges VR0 and 6414 VR1, store in VR0 a range that contains both VR0 and VR1. This 6415 may not be the smallest possible such range. */ 6416 6417 static void 6418 vrp_meet (value_range_t *vr0, value_range_t *vr1) 6419 { 6420 if (vr0->type == VR_UNDEFINED) 6421 { 6422 /* Drop equivalences. See PR53465. */ 6423 set_value_range (vr0, vr1->type, vr1->min, vr1->max, NULL); 6424 return; 6425 } 6426 6427 if (vr1->type == VR_UNDEFINED) 6428 { 6429 /* VR0 already has the resulting range, just drop equivalences. 6430 See PR53465. */ 6431 if (vr0->equiv) 6432 bitmap_clear (vr0->equiv); 6433 return; 6434 } 6435 6436 if (vr0->type == VR_VARYING) 6437 { 6438 /* Nothing to do. VR0 already has the resulting range. */ 6439 return; 6440 } 6441 6442 if (vr1->type == VR_VARYING) 6443 { 6444 set_value_range_to_varying (vr0); 6445 return; 6446 } 6447 6448 if (vr0->type == VR_RANGE && vr1->type == VR_RANGE) 6449 { 6450 int cmp; 6451 tree min, max; 6452 6453 /* Compute the convex hull of the ranges. The lower limit of 6454 the new range is the minimum of the two ranges. If they 6455 cannot be compared, then give up. */ 6456 cmp = compare_values (vr0->min, vr1->min); 6457 if (cmp == 0 || cmp == 1) 6458 min = vr1->min; 6459 else if (cmp == -1) 6460 min = vr0->min; 6461 else 6462 goto give_up; 6463 6464 /* Similarly, the upper limit of the new range is the maximum 6465 of the two ranges. If they cannot be compared, then 6466 give up. */ 6467 cmp = compare_values (vr0->max, vr1->max); 6468 if (cmp == 0 || cmp == -1) 6469 max = vr1->max; 6470 else if (cmp == 1) 6471 max = vr0->max; 6472 else 6473 goto give_up; 6474 6475 /* Check for useless ranges. */ 6476 if (INTEGRAL_TYPE_P (TREE_TYPE (min)) 6477 && ((vrp_val_is_min (min) || is_overflow_infinity (min)) 6478 && (vrp_val_is_max (max) || is_overflow_infinity (max)))) 6479 goto give_up; 6480 6481 /* The resulting set of equivalences is the intersection of 6482 the two sets. */ 6483 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv) 6484 bitmap_and_into (vr0->equiv, vr1->equiv); 6485 else if (vr0->equiv && !vr1->equiv) 6486 bitmap_clear (vr0->equiv); 6487 6488 set_value_range (vr0, vr0->type, min, max, vr0->equiv); 6489 } 6490 else if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE) 6491 { 6492 /* Two anti-ranges meet only if their complements intersect. 6493 Only handle the case of identical ranges. */ 6494 if (compare_values (vr0->min, vr1->min) == 0 6495 && compare_values (vr0->max, vr1->max) == 0 6496 && compare_values (vr0->min, vr0->max) == 0) 6497 { 6498 /* The resulting set of equivalences is the intersection of 6499 the two sets. */ 6500 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv) 6501 bitmap_and_into (vr0->equiv, vr1->equiv); 6502 else if (vr0->equiv && !vr1->equiv) 6503 bitmap_clear (vr0->equiv); 6504 } 6505 else 6506 goto give_up; 6507 } 6508 else if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE) 6509 { 6510 /* For a numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4], 6511 only handle the case where the ranges have an empty intersection. 6512 The result of the meet operation is the anti-range. */ 6513 if (!symbolic_range_p (vr0) 6514 && !symbolic_range_p (vr1) 6515 && !value_ranges_intersect_p (vr0, vr1)) 6516 { 6517 /* Copy most of VR1 into VR0. Don't copy VR1's equivalence 6518 set. We need to compute the intersection of the two 6519 equivalence sets. */ 6520 if (vr1->type == VR_ANTI_RANGE) 6521 set_value_range (vr0, vr1->type, vr1->min, vr1->max, vr0->equiv); 6522 6523 /* The resulting set of equivalences is the intersection of 6524 the two sets. */ 6525 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv) 6526 bitmap_and_into (vr0->equiv, vr1->equiv); 6527 else if (vr0->equiv && !vr1->equiv) 6528 bitmap_clear (vr0->equiv); 6529 } 6530 else 6531 goto give_up; 6532 } 6533 else 6534 gcc_unreachable (); 6535 6536 return; 6537 6538 give_up: 6539 /* Failed to find an efficient meet. Before giving up and setting 6540 the result to VARYING, see if we can at least derive a useful 6541 anti-range. FIXME, all this nonsense about distinguishing 6542 anti-ranges from ranges is necessary because of the odd 6543 semantics of range_includes_zero_p and friends. */ 6544 if (!symbolic_range_p (vr0) 6545 && ((vr0->type == VR_RANGE 6546 && range_includes_zero_p (vr0->min, vr0->max) == 0) 6547 || (vr0->type == VR_ANTI_RANGE 6548 && range_includes_zero_p (vr0->min, vr0->max) == 1)) 6549 && !symbolic_range_p (vr1) 6550 && ((vr1->type == VR_RANGE 6551 && range_includes_zero_p (vr1->min, vr1->max) == 0) 6552 || (vr1->type == VR_ANTI_RANGE 6553 && range_includes_zero_p (vr1->min, vr1->max) == 1))) 6554 { 6555 set_value_range_to_nonnull (vr0, TREE_TYPE (vr0->min)); 6556 6557 /* Since this meet operation did not result from the meeting of 6558 two equivalent names, VR0 cannot have any equivalences. */ 6559 if (vr0->equiv) 6560 bitmap_clear (vr0->equiv); 6561 } 6562 else 6563 set_value_range_to_varying (vr0); 6564 } 6565 6566 6567 /* Visit all arguments for PHI node PHI that flow through executable 6568 edges. If a valid value range can be derived from all the incoming 6569 value ranges, set a new range for the LHS of PHI. */ 6570 6571 static enum ssa_prop_result 6572 vrp_visit_phi_node (gimple phi) 6573 { 6574 size_t i; 6575 tree lhs = PHI_RESULT (phi); 6576 value_range_t *lhs_vr = get_value_range (lhs); 6577 value_range_t vr_result = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; 6578 bool first = true; 6579 int edges, old_edges; 6580 struct loop *l; 6581 6582 if (dump_file && (dump_flags & TDF_DETAILS)) 6583 { 6584 fprintf (dump_file, "\nVisiting PHI node: "); 6585 print_gimple_stmt (dump_file, phi, 0, dump_flags); 6586 } 6587 6588 edges = 0; 6589 for (i = 0; i < gimple_phi_num_args (phi); i++) 6590 { 6591 edge e = gimple_phi_arg_edge (phi, i); 6592 6593 if (dump_file && (dump_flags & TDF_DETAILS)) 6594 { 6595 fprintf (dump_file, 6596 "\n Argument #%d (%d -> %d %sexecutable)\n", 6597 (int) i, e->src->index, e->dest->index, 6598 (e->flags & EDGE_EXECUTABLE) ? "" : "not "); 6599 } 6600 6601 if (e->flags & EDGE_EXECUTABLE) 6602 { 6603 tree arg = PHI_ARG_DEF (phi, i); 6604 value_range_t vr_arg; 6605 6606 ++edges; 6607 6608 if (TREE_CODE (arg) == SSA_NAME) 6609 { 6610 vr_arg = *(get_value_range (arg)); 6611 } 6612 else 6613 { 6614 if (is_overflow_infinity (arg)) 6615 { 6616 arg = copy_node (arg); 6617 TREE_OVERFLOW (arg) = 0; 6618 } 6619 6620 vr_arg.type = VR_RANGE; 6621 vr_arg.min = arg; 6622 vr_arg.max = arg; 6623 vr_arg.equiv = NULL; 6624 } 6625 6626 if (dump_file && (dump_flags & TDF_DETAILS)) 6627 { 6628 fprintf (dump_file, "\t"); 6629 print_generic_expr (dump_file, arg, dump_flags); 6630 fprintf (dump_file, "\n\tValue: "); 6631 dump_value_range (dump_file, &vr_arg); 6632 fprintf (dump_file, "\n"); 6633 } 6634 6635 if (first) 6636 copy_value_range (&vr_result, &vr_arg); 6637 else 6638 vrp_meet (&vr_result, &vr_arg); 6639 first = false; 6640 6641 if (vr_result.type == VR_VARYING) 6642 break; 6643 } 6644 } 6645 6646 if (vr_result.type == VR_VARYING) 6647 goto varying; 6648 else if (vr_result.type == VR_UNDEFINED) 6649 goto update_range; 6650 6651 old_edges = vr_phi_edge_counts[SSA_NAME_VERSION (lhs)]; 6652 vr_phi_edge_counts[SSA_NAME_VERSION (lhs)] = edges; 6653 6654 /* To prevent infinite iterations in the algorithm, derive ranges 6655 when the new value is slightly bigger or smaller than the 6656 previous one. We don't do this if we have seen a new executable 6657 edge; this helps us avoid an overflow infinity for conditionals 6658 which are not in a loop. */ 6659 if (edges > 0 6660 && gimple_phi_num_args (phi) > 1 6661 && edges == old_edges) 6662 { 6663 int cmp_min = compare_values (lhs_vr->min, vr_result.min); 6664 int cmp_max = compare_values (lhs_vr->max, vr_result.max); 6665 6666 /* For non VR_RANGE or for pointers fall back to varying if 6667 the range changed. */ 6668 if ((lhs_vr->type != VR_RANGE || vr_result.type != VR_RANGE 6669 || POINTER_TYPE_P (TREE_TYPE (lhs))) 6670 && (cmp_min != 0 || cmp_max != 0)) 6671 goto varying; 6672 6673 /* If the new minimum is smaller or larger than the previous 6674 one, go all the way to -INF. In the first case, to avoid 6675 iterating millions of times to reach -INF, and in the 6676 other case to avoid infinite bouncing between different 6677 minimums. */ 6678 if (cmp_min > 0 || cmp_min < 0) 6679 { 6680 if (!needs_overflow_infinity (TREE_TYPE (vr_result.min)) 6681 || !vrp_var_may_overflow (lhs, phi)) 6682 vr_result.min = TYPE_MIN_VALUE (TREE_TYPE (vr_result.min)); 6683 else if (supports_overflow_infinity (TREE_TYPE (vr_result.min))) 6684 vr_result.min = 6685 negative_overflow_infinity (TREE_TYPE (vr_result.min)); 6686 } 6687 6688 /* Similarly, if the new maximum is smaller or larger than 6689 the previous one, go all the way to +INF. */ 6690 if (cmp_max < 0 || cmp_max > 0) 6691 { 6692 if (!needs_overflow_infinity (TREE_TYPE (vr_result.max)) 6693 || !vrp_var_may_overflow (lhs, phi)) 6694 vr_result.max = TYPE_MAX_VALUE (TREE_TYPE (vr_result.max)); 6695 else if (supports_overflow_infinity (TREE_TYPE (vr_result.max))) 6696 vr_result.max = 6697 positive_overflow_infinity (TREE_TYPE (vr_result.max)); 6698 } 6699 6700 /* If we dropped either bound to +-INF then if this is a loop 6701 PHI node SCEV may known more about its value-range. */ 6702 if ((cmp_min > 0 || cmp_min < 0 6703 || cmp_max < 0 || cmp_max > 0) 6704 && current_loops 6705 && (l = loop_containing_stmt (phi)) 6706 && l->header == gimple_bb (phi)) 6707 adjust_range_with_scev (&vr_result, l, phi, lhs); 6708 6709 /* If we will end up with a (-INF, +INF) range, set it to 6710 VARYING. Same if the previous max value was invalid for 6711 the type and we end up with vr_result.min > vr_result.max. */ 6712 if ((vrp_val_is_max (vr_result.max) 6713 && vrp_val_is_min (vr_result.min)) 6714 || compare_values (vr_result.min, 6715 vr_result.max) > 0) 6716 goto varying; 6717 } 6718 6719 /* If the new range is different than the previous value, keep 6720 iterating. */ 6721 update_range: 6722 if (update_value_range (lhs, &vr_result)) 6723 { 6724 if (dump_file && (dump_flags & TDF_DETAILS)) 6725 { 6726 fprintf (dump_file, "Found new range for "); 6727 print_generic_expr (dump_file, lhs, 0); 6728 fprintf (dump_file, ": "); 6729 dump_value_range (dump_file, &vr_result); 6730 fprintf (dump_file, "\n\n"); 6731 } 6732 6733 return SSA_PROP_INTERESTING; 6734 } 6735 6736 /* Nothing changed, don't add outgoing edges. */ 6737 return SSA_PROP_NOT_INTERESTING; 6738 6739 /* No match found. Set the LHS to VARYING. */ 6740 varying: 6741 set_value_range_to_varying (lhs_vr); 6742 return SSA_PROP_VARYING; 6743 } 6744 6745 /* Simplify boolean operations if the source is known 6746 to be already a boolean. */ 6747 static bool 6748 simplify_truth_ops_using_ranges (gimple_stmt_iterator *gsi, gimple stmt) 6749 { 6750 enum tree_code rhs_code = gimple_assign_rhs_code (stmt); 6751 tree lhs, op0, op1; 6752 bool need_conversion; 6753 6754 /* We handle only !=/== case here. */ 6755 gcc_assert (rhs_code == EQ_EXPR || rhs_code == NE_EXPR); 6756 6757 op0 = gimple_assign_rhs1 (stmt); 6758 if (!op_with_boolean_value_range_p (op0)) 6759 return false; 6760 6761 op1 = gimple_assign_rhs2 (stmt); 6762 if (!op_with_boolean_value_range_p (op1)) 6763 return false; 6764 6765 /* Reduce number of cases to handle to NE_EXPR. As there is no 6766 BIT_XNOR_EXPR we cannot replace A == B with a single statement. */ 6767 if (rhs_code == EQ_EXPR) 6768 { 6769 if (TREE_CODE (op1) == INTEGER_CST) 6770 op1 = int_const_binop (BIT_XOR_EXPR, op1, integer_one_node); 6771 else 6772 return false; 6773 } 6774 6775 lhs = gimple_assign_lhs (stmt); 6776 need_conversion 6777 = !useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (op0)); 6778 6779 /* Make sure to not sign-extend a 1-bit 1 when converting the result. */ 6780 if (need_conversion 6781 && !TYPE_UNSIGNED (TREE_TYPE (op0)) 6782 && TYPE_PRECISION (TREE_TYPE (op0)) == 1 6783 && TYPE_PRECISION (TREE_TYPE (lhs)) > 1) 6784 return false; 6785 6786 /* For A != 0 we can substitute A itself. */ 6787 if (integer_zerop (op1)) 6788 gimple_assign_set_rhs_with_ops (gsi, 6789 need_conversion 6790 ? NOP_EXPR : TREE_CODE (op0), 6791 op0, NULL_TREE); 6792 /* For A != B we substitute A ^ B. Either with conversion. */ 6793 else if (need_conversion) 6794 { 6795 gimple newop; 6796 tree tem = create_tmp_reg (TREE_TYPE (op0), NULL); 6797 newop = gimple_build_assign_with_ops (BIT_XOR_EXPR, tem, op0, op1); 6798 tem = make_ssa_name (tem, newop); 6799 gimple_assign_set_lhs (newop, tem); 6800 gsi_insert_before (gsi, newop, GSI_SAME_STMT); 6801 update_stmt (newop); 6802 gimple_assign_set_rhs_with_ops (gsi, NOP_EXPR, tem, NULL_TREE); 6803 } 6804 /* Or without. */ 6805 else 6806 gimple_assign_set_rhs_with_ops (gsi, BIT_XOR_EXPR, op0, op1); 6807 update_stmt (gsi_stmt (*gsi)); 6808 6809 return true; 6810 } 6811 6812 /* Simplify a division or modulo operator to a right shift or 6813 bitwise and if the first operand is unsigned or is greater 6814 than zero and the second operand is an exact power of two. */ 6815 6816 static bool 6817 simplify_div_or_mod_using_ranges (gimple stmt) 6818 { 6819 enum tree_code rhs_code = gimple_assign_rhs_code (stmt); 6820 tree val = NULL; 6821 tree op0 = gimple_assign_rhs1 (stmt); 6822 tree op1 = gimple_assign_rhs2 (stmt); 6823 value_range_t *vr = get_value_range (gimple_assign_rhs1 (stmt)); 6824 6825 if (TYPE_UNSIGNED (TREE_TYPE (op0))) 6826 { 6827 val = integer_one_node; 6828 } 6829 else 6830 { 6831 bool sop = false; 6832 6833 val = compare_range_with_value (GE_EXPR, vr, integer_zero_node, &sop); 6834 6835 if (val 6836 && sop 6837 && integer_onep (val) 6838 && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC)) 6839 { 6840 location_t location; 6841 6842 if (!gimple_has_location (stmt)) 6843 location = input_location; 6844 else 6845 location = gimple_location (stmt); 6846 warning_at (location, OPT_Wstrict_overflow, 6847 "assuming signed overflow does not occur when " 6848 "simplifying %</%> or %<%%%> to %<>>%> or %<&%>"); 6849 } 6850 } 6851 6852 if (val && integer_onep (val)) 6853 { 6854 tree t; 6855 6856 if (rhs_code == TRUNC_DIV_EXPR) 6857 { 6858 t = build_int_cst (integer_type_node, tree_log2 (op1)); 6859 gimple_assign_set_rhs_code (stmt, RSHIFT_EXPR); 6860 gimple_assign_set_rhs1 (stmt, op0); 6861 gimple_assign_set_rhs2 (stmt, t); 6862 } 6863 else 6864 { 6865 t = build_int_cst (TREE_TYPE (op1), 1); 6866 t = int_const_binop (MINUS_EXPR, op1, t); 6867 t = fold_convert (TREE_TYPE (op0), t); 6868 6869 gimple_assign_set_rhs_code (stmt, BIT_AND_EXPR); 6870 gimple_assign_set_rhs1 (stmt, op0); 6871 gimple_assign_set_rhs2 (stmt, t); 6872 } 6873 6874 update_stmt (stmt); 6875 return true; 6876 } 6877 6878 return false; 6879 } 6880 6881 /* If the operand to an ABS_EXPR is >= 0, then eliminate the 6882 ABS_EXPR. If the operand is <= 0, then simplify the 6883 ABS_EXPR into a NEGATE_EXPR. */ 6884 6885 static bool 6886 simplify_abs_using_ranges (gimple stmt) 6887 { 6888 tree val = NULL; 6889 tree op = gimple_assign_rhs1 (stmt); 6890 tree type = TREE_TYPE (op); 6891 value_range_t *vr = get_value_range (op); 6892 6893 if (TYPE_UNSIGNED (type)) 6894 { 6895 val = integer_zero_node; 6896 } 6897 else if (vr) 6898 { 6899 bool sop = false; 6900 6901 val = compare_range_with_value (LE_EXPR, vr, integer_zero_node, &sop); 6902 if (!val) 6903 { 6904 sop = false; 6905 val = compare_range_with_value (GE_EXPR, vr, integer_zero_node, 6906 &sop); 6907 6908 if (val) 6909 { 6910 if (integer_zerop (val)) 6911 val = integer_one_node; 6912 else if (integer_onep (val)) 6913 val = integer_zero_node; 6914 } 6915 } 6916 6917 if (val 6918 && (integer_onep (val) || integer_zerop (val))) 6919 { 6920 if (sop && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC)) 6921 { 6922 location_t location; 6923 6924 if (!gimple_has_location (stmt)) 6925 location = input_location; 6926 else 6927 location = gimple_location (stmt); 6928 warning_at (location, OPT_Wstrict_overflow, 6929 "assuming signed overflow does not occur when " 6930 "simplifying %<abs (X)%> to %<X%> or %<-X%>"); 6931 } 6932 6933 gimple_assign_set_rhs1 (stmt, op); 6934 if (integer_onep (val)) 6935 gimple_assign_set_rhs_code (stmt, NEGATE_EXPR); 6936 else 6937 gimple_assign_set_rhs_code (stmt, SSA_NAME); 6938 update_stmt (stmt); 6939 return true; 6940 } 6941 } 6942 6943 return false; 6944 } 6945 6946 /* Optimize away redundant BIT_AND_EXPR and BIT_IOR_EXPR. 6947 If all the bits that are being cleared by & are already 6948 known to be zero from VR, or all the bits that are being 6949 set by | are already known to be one from VR, the bit 6950 operation is redundant. */ 6951 6952 static bool 6953 simplify_bit_ops_using_ranges (gimple_stmt_iterator *gsi, gimple stmt) 6954 { 6955 tree op0 = gimple_assign_rhs1 (stmt); 6956 tree op1 = gimple_assign_rhs2 (stmt); 6957 tree op = NULL_TREE; 6958 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; 6959 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; 6960 double_int may_be_nonzero0, may_be_nonzero1; 6961 double_int must_be_nonzero0, must_be_nonzero1; 6962 double_int mask; 6963 6964 if (TREE_CODE (op0) == SSA_NAME) 6965 vr0 = *(get_value_range (op0)); 6966 else if (is_gimple_min_invariant (op0)) 6967 set_value_range_to_value (&vr0, op0, NULL); 6968 else 6969 return false; 6970 6971 if (TREE_CODE (op1) == SSA_NAME) 6972 vr1 = *(get_value_range (op1)); 6973 else if (is_gimple_min_invariant (op1)) 6974 set_value_range_to_value (&vr1, op1, NULL); 6975 else 6976 return false; 6977 6978 if (!zero_nonzero_bits_from_vr (&vr0, &may_be_nonzero0, &must_be_nonzero0)) 6979 return false; 6980 if (!zero_nonzero_bits_from_vr (&vr1, &may_be_nonzero1, &must_be_nonzero1)) 6981 return false; 6982 6983 switch (gimple_assign_rhs_code (stmt)) 6984 { 6985 case BIT_AND_EXPR: 6986 mask = double_int_and_not (may_be_nonzero0, must_be_nonzero1); 6987 if (double_int_zero_p (mask)) 6988 { 6989 op = op0; 6990 break; 6991 } 6992 mask = double_int_and_not (may_be_nonzero1, must_be_nonzero0); 6993 if (double_int_zero_p (mask)) 6994 { 6995 op = op1; 6996 break; 6997 } 6998 break; 6999 case BIT_IOR_EXPR: 7000 mask = double_int_and_not (may_be_nonzero0, must_be_nonzero1); 7001 if (double_int_zero_p (mask)) 7002 { 7003 op = op1; 7004 break; 7005 } 7006 mask = double_int_and_not (may_be_nonzero1, must_be_nonzero0); 7007 if (double_int_zero_p (mask)) 7008 { 7009 op = op0; 7010 break; 7011 } 7012 break; 7013 default: 7014 gcc_unreachable (); 7015 } 7016 7017 if (op == NULL_TREE) 7018 return false; 7019 7020 gimple_assign_set_rhs_with_ops (gsi, TREE_CODE (op), op, NULL); 7021 update_stmt (gsi_stmt (*gsi)); 7022 return true; 7023 } 7024 7025 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has 7026 a known value range VR. 7027 7028 If there is one and only one value which will satisfy the 7029 conditional, then return that value. Else return NULL. */ 7030 7031 static tree 7032 test_for_singularity (enum tree_code cond_code, tree op0, 7033 tree op1, value_range_t *vr) 7034 { 7035 tree min = NULL; 7036 tree max = NULL; 7037 7038 /* Extract minimum/maximum values which satisfy the 7039 the conditional as it was written. */ 7040 if (cond_code == LE_EXPR || cond_code == LT_EXPR) 7041 { 7042 /* This should not be negative infinity; there is no overflow 7043 here. */ 7044 min = TYPE_MIN_VALUE (TREE_TYPE (op0)); 7045 7046 max = op1; 7047 if (cond_code == LT_EXPR && !is_overflow_infinity (max)) 7048 { 7049 tree one = build_int_cst (TREE_TYPE (op0), 1); 7050 max = fold_build2 (MINUS_EXPR, TREE_TYPE (op0), max, one); 7051 if (EXPR_P (max)) 7052 TREE_NO_WARNING (max) = 1; 7053 } 7054 } 7055 else if (cond_code == GE_EXPR || cond_code == GT_EXPR) 7056 { 7057 /* This should not be positive infinity; there is no overflow 7058 here. */ 7059 max = TYPE_MAX_VALUE (TREE_TYPE (op0)); 7060 7061 min = op1; 7062 if (cond_code == GT_EXPR && !is_overflow_infinity (min)) 7063 { 7064 tree one = build_int_cst (TREE_TYPE (op0), 1); 7065 min = fold_build2 (PLUS_EXPR, TREE_TYPE (op0), min, one); 7066 if (EXPR_P (min)) 7067 TREE_NO_WARNING (min) = 1; 7068 } 7069 } 7070 7071 /* Now refine the minimum and maximum values using any 7072 value range information we have for op0. */ 7073 if (min && max) 7074 { 7075 if (compare_values (vr->min, min) == 1) 7076 min = vr->min; 7077 if (compare_values (vr->max, max) == -1) 7078 max = vr->max; 7079 7080 /* If the new min/max values have converged to a single value, 7081 then there is only one value which can satisfy the condition, 7082 return that value. */ 7083 if (operand_equal_p (min, max, 0) && is_gimple_min_invariant (min)) 7084 return min; 7085 } 7086 return NULL; 7087 } 7088 7089 /* Simplify a conditional using a relational operator to an equality 7090 test if the range information indicates only one value can satisfy 7091 the original conditional. */ 7092 7093 static bool 7094 simplify_cond_using_ranges (gimple stmt) 7095 { 7096 tree op0 = gimple_cond_lhs (stmt); 7097 tree op1 = gimple_cond_rhs (stmt); 7098 enum tree_code cond_code = gimple_cond_code (stmt); 7099 7100 if (cond_code != NE_EXPR 7101 && cond_code != EQ_EXPR 7102 && TREE_CODE (op0) == SSA_NAME 7103 && INTEGRAL_TYPE_P (TREE_TYPE (op0)) 7104 && is_gimple_min_invariant (op1)) 7105 { 7106 value_range_t *vr = get_value_range (op0); 7107 7108 /* If we have range information for OP0, then we might be 7109 able to simplify this conditional. */ 7110 if (vr->type == VR_RANGE) 7111 { 7112 tree new_tree = test_for_singularity (cond_code, op0, op1, vr); 7113 7114 if (new_tree) 7115 { 7116 if (dump_file) 7117 { 7118 fprintf (dump_file, "Simplified relational "); 7119 print_gimple_stmt (dump_file, stmt, 0, 0); 7120 fprintf (dump_file, " into "); 7121 } 7122 7123 gimple_cond_set_code (stmt, EQ_EXPR); 7124 gimple_cond_set_lhs (stmt, op0); 7125 gimple_cond_set_rhs (stmt, new_tree); 7126 7127 update_stmt (stmt); 7128 7129 if (dump_file) 7130 { 7131 print_gimple_stmt (dump_file, stmt, 0, 0); 7132 fprintf (dump_file, "\n"); 7133 } 7134 7135 return true; 7136 } 7137 7138 /* Try again after inverting the condition. We only deal 7139 with integral types here, so no need to worry about 7140 issues with inverting FP comparisons. */ 7141 cond_code = invert_tree_comparison (cond_code, false); 7142 new_tree = test_for_singularity (cond_code, op0, op1, vr); 7143 7144 if (new_tree) 7145 { 7146 if (dump_file) 7147 { 7148 fprintf (dump_file, "Simplified relational "); 7149 print_gimple_stmt (dump_file, stmt, 0, 0); 7150 fprintf (dump_file, " into "); 7151 } 7152 7153 gimple_cond_set_code (stmt, NE_EXPR); 7154 gimple_cond_set_lhs (stmt, op0); 7155 gimple_cond_set_rhs (stmt, new_tree); 7156 7157 update_stmt (stmt); 7158 7159 if (dump_file) 7160 { 7161 print_gimple_stmt (dump_file, stmt, 0, 0); 7162 fprintf (dump_file, "\n"); 7163 } 7164 7165 return true; 7166 } 7167 } 7168 } 7169 7170 return false; 7171 } 7172 7173 /* Simplify a switch statement using the value range of the switch 7174 argument. */ 7175 7176 static bool 7177 simplify_switch_using_ranges (gimple stmt) 7178 { 7179 tree op = gimple_switch_index (stmt); 7180 value_range_t *vr; 7181 bool take_default; 7182 edge e; 7183 edge_iterator ei; 7184 size_t i = 0, j = 0, n, n2; 7185 tree vec2; 7186 switch_update su; 7187 7188 if (TREE_CODE (op) == SSA_NAME) 7189 { 7190 vr = get_value_range (op); 7191 7192 /* We can only handle integer ranges. */ 7193 if (vr->type != VR_RANGE 7194 || symbolic_range_p (vr)) 7195 return false; 7196 7197 /* Find case label for min/max of the value range. */ 7198 take_default = !find_case_label_range (stmt, vr->min, vr->max, &i, &j); 7199 } 7200 else if (TREE_CODE (op) == INTEGER_CST) 7201 { 7202 take_default = !find_case_label_index (stmt, 1, op, &i); 7203 if (take_default) 7204 { 7205 i = 1; 7206 j = 0; 7207 } 7208 else 7209 { 7210 j = i; 7211 } 7212 } 7213 else 7214 return false; 7215 7216 n = gimple_switch_num_labels (stmt); 7217 7218 /* Bail out if this is just all edges taken. */ 7219 if (i == 1 7220 && j == n - 1 7221 && take_default) 7222 return false; 7223 7224 /* Build a new vector of taken case labels. */ 7225 vec2 = make_tree_vec (j - i + 1 + (int)take_default); 7226 n2 = 0; 7227 7228 /* Add the default edge, if necessary. */ 7229 if (take_default) 7230 TREE_VEC_ELT (vec2, n2++) = gimple_switch_default_label (stmt); 7231 7232 for (; i <= j; ++i, ++n2) 7233 TREE_VEC_ELT (vec2, n2) = gimple_switch_label (stmt, i); 7234 7235 /* Mark needed edges. */ 7236 for (i = 0; i < n2; ++i) 7237 { 7238 e = find_edge (gimple_bb (stmt), 7239 label_to_block (CASE_LABEL (TREE_VEC_ELT (vec2, i)))); 7240 e->aux = (void *)-1; 7241 } 7242 7243 /* Queue not needed edges for later removal. */ 7244 FOR_EACH_EDGE (e, ei, gimple_bb (stmt)->succs) 7245 { 7246 if (e->aux == (void *)-1) 7247 { 7248 e->aux = NULL; 7249 continue; 7250 } 7251 7252 if (dump_file && (dump_flags & TDF_DETAILS)) 7253 { 7254 fprintf (dump_file, "removing unreachable case label\n"); 7255 } 7256 VEC_safe_push (edge, heap, to_remove_edges, e); 7257 e->flags &= ~EDGE_EXECUTABLE; 7258 } 7259 7260 /* And queue an update for the stmt. */ 7261 su.stmt = stmt; 7262 su.vec = vec2; 7263 VEC_safe_push (switch_update, heap, to_update_switch_stmts, &su); 7264 return false; 7265 } 7266 7267 /* Simplify an integral conversion from an SSA name in STMT. */ 7268 7269 static bool 7270 simplify_conversion_using_ranges (gimple stmt) 7271 { 7272 tree innerop, middleop, finaltype; 7273 gimple def_stmt; 7274 value_range_t *innervr; 7275 bool inner_unsigned_p, middle_unsigned_p, final_unsigned_p; 7276 unsigned inner_prec, middle_prec, final_prec; 7277 double_int innermin, innermed, innermax, middlemin, middlemed, middlemax; 7278 7279 finaltype = TREE_TYPE (gimple_assign_lhs (stmt)); 7280 if (!INTEGRAL_TYPE_P (finaltype)) 7281 return false; 7282 middleop = gimple_assign_rhs1 (stmt); 7283 def_stmt = SSA_NAME_DEF_STMT (middleop); 7284 if (!is_gimple_assign (def_stmt) 7285 || !CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (def_stmt))) 7286 return false; 7287 innerop = gimple_assign_rhs1 (def_stmt); 7288 if (TREE_CODE (innerop) != SSA_NAME) 7289 return false; 7290 7291 /* Get the value-range of the inner operand. */ 7292 innervr = get_value_range (innerop); 7293 if (innervr->type != VR_RANGE 7294 || TREE_CODE (innervr->min) != INTEGER_CST 7295 || TREE_CODE (innervr->max) != INTEGER_CST) 7296 return false; 7297 7298 /* Simulate the conversion chain to check if the result is equal if 7299 the middle conversion is removed. */ 7300 innermin = tree_to_double_int (innervr->min); 7301 innermax = tree_to_double_int (innervr->max); 7302 7303 inner_prec = TYPE_PRECISION (TREE_TYPE (innerop)); 7304 middle_prec = TYPE_PRECISION (TREE_TYPE (middleop)); 7305 final_prec = TYPE_PRECISION (finaltype); 7306 7307 /* If the first conversion is not injective, the second must not 7308 be widening. */ 7309 if (double_int_cmp (double_int_sub (innermax, innermin), 7310 double_int_mask (middle_prec), true) > 0 7311 && middle_prec < final_prec) 7312 return false; 7313 /* We also want a medium value so that we can track the effect that 7314 narrowing conversions with sign change have. */ 7315 inner_unsigned_p = TYPE_UNSIGNED (TREE_TYPE (innerop)); 7316 if (inner_unsigned_p) 7317 innermed = double_int_rshift (double_int_mask (inner_prec), 7318 1, inner_prec, false); 7319 else 7320 innermed = double_int_zero; 7321 if (double_int_cmp (innermin, innermed, inner_unsigned_p) >= 0 7322 || double_int_cmp (innermed, innermax, inner_unsigned_p) >= 0) 7323 innermed = innermin; 7324 7325 middle_unsigned_p = TYPE_UNSIGNED (TREE_TYPE (middleop)); 7326 middlemin = double_int_ext (innermin, middle_prec, middle_unsigned_p); 7327 middlemed = double_int_ext (innermed, middle_prec, middle_unsigned_p); 7328 middlemax = double_int_ext (innermax, middle_prec, middle_unsigned_p); 7329 7330 /* Require that the final conversion applied to both the original 7331 and the intermediate range produces the same result. */ 7332 final_unsigned_p = TYPE_UNSIGNED (finaltype); 7333 if (!double_int_equal_p (double_int_ext (middlemin, 7334 final_prec, final_unsigned_p), 7335 double_int_ext (innermin, 7336 final_prec, final_unsigned_p)) 7337 || !double_int_equal_p (double_int_ext (middlemed, 7338 final_prec, final_unsigned_p), 7339 double_int_ext (innermed, 7340 final_prec, final_unsigned_p)) 7341 || !double_int_equal_p (double_int_ext (middlemax, 7342 final_prec, final_unsigned_p), 7343 double_int_ext (innermax, 7344 final_prec, final_unsigned_p))) 7345 return false; 7346 7347 gimple_assign_set_rhs1 (stmt, innerop); 7348 update_stmt (stmt); 7349 return true; 7350 } 7351 7352 /* Return whether the value range *VR fits in an integer type specified 7353 by PRECISION and UNSIGNED_P. */ 7354 7355 static bool 7356 range_fits_type_p (value_range_t *vr, unsigned precision, bool unsigned_p) 7357 { 7358 tree src_type; 7359 unsigned src_precision; 7360 double_int tem; 7361 7362 /* We can only handle integral and pointer types. */ 7363 src_type = TREE_TYPE (vr->min); 7364 if (!INTEGRAL_TYPE_P (src_type) 7365 && !POINTER_TYPE_P (src_type)) 7366 return false; 7367 7368 /* An extension is always fine, so is an identity transform. */ 7369 src_precision = TYPE_PRECISION (TREE_TYPE (vr->min)); 7370 if (src_precision < precision 7371 || (src_precision == precision 7372 && TYPE_UNSIGNED (src_type) == unsigned_p)) 7373 return true; 7374 7375 /* Now we can only handle ranges with constant bounds. */ 7376 if (vr->type != VR_RANGE 7377 || TREE_CODE (vr->min) != INTEGER_CST 7378 || TREE_CODE (vr->max) != INTEGER_CST) 7379 return false; 7380 7381 /* For precision-preserving sign-changes the MSB of the double-int 7382 has to be clear. */ 7383 if (src_precision == precision 7384 && (TREE_INT_CST_HIGH (vr->min) | TREE_INT_CST_HIGH (vr->max)) < 0) 7385 return false; 7386 7387 /* Then we can perform the conversion on both ends and compare 7388 the result for equality. */ 7389 tem = double_int_ext (tree_to_double_int (vr->min), precision, unsigned_p); 7390 if (!double_int_equal_p (tree_to_double_int (vr->min), tem)) 7391 return false; 7392 tem = double_int_ext (tree_to_double_int (vr->max), precision, unsigned_p); 7393 if (!double_int_equal_p (tree_to_double_int (vr->max), tem)) 7394 return false; 7395 7396 return true; 7397 } 7398 7399 /* Simplify a conversion from integral SSA name to float in STMT. */ 7400 7401 static bool 7402 simplify_float_conversion_using_ranges (gimple_stmt_iterator *gsi, gimple stmt) 7403 { 7404 tree rhs1 = gimple_assign_rhs1 (stmt); 7405 value_range_t *vr = get_value_range (rhs1); 7406 enum machine_mode fltmode = TYPE_MODE (TREE_TYPE (gimple_assign_lhs (stmt))); 7407 enum machine_mode mode; 7408 tree tem; 7409 gimple conv; 7410 7411 /* We can only handle constant ranges. */ 7412 if (vr->type != VR_RANGE 7413 || TREE_CODE (vr->min) != INTEGER_CST 7414 || TREE_CODE (vr->max) != INTEGER_CST) 7415 return false; 7416 7417 /* First check if we can use a signed type in place of an unsigned. */ 7418 if (TYPE_UNSIGNED (TREE_TYPE (rhs1)) 7419 && (can_float_p (fltmode, TYPE_MODE (TREE_TYPE (rhs1)), 0) 7420 != CODE_FOR_nothing) 7421 && range_fits_type_p (vr, GET_MODE_PRECISION 7422 (TYPE_MODE (TREE_TYPE (rhs1))), 0)) 7423 mode = TYPE_MODE (TREE_TYPE (rhs1)); 7424 /* If we can do the conversion in the current input mode do nothing. */ 7425 else if (can_float_p (fltmode, TYPE_MODE (TREE_TYPE (rhs1)), 7426 TYPE_UNSIGNED (TREE_TYPE (rhs1)))) 7427 return false; 7428 /* Otherwise search for a mode we can use, starting from the narrowest 7429 integer mode available. */ 7430 else 7431 { 7432 mode = GET_CLASS_NARROWEST_MODE (MODE_INT); 7433 do 7434 { 7435 /* If we cannot do a signed conversion to float from mode 7436 or if the value-range does not fit in the signed type 7437 try with a wider mode. */ 7438 if (can_float_p (fltmode, mode, 0) != CODE_FOR_nothing 7439 && range_fits_type_p (vr, GET_MODE_PRECISION (mode), 0)) 7440 break; 7441 7442 mode = GET_MODE_WIDER_MODE (mode); 7443 /* But do not widen the input. Instead leave that to the 7444 optabs expansion code. */ 7445 if (GET_MODE_PRECISION (mode) > TYPE_PRECISION (TREE_TYPE (rhs1))) 7446 return false; 7447 } 7448 while (mode != VOIDmode); 7449 if (mode == VOIDmode) 7450 return false; 7451 } 7452 7453 /* It works, insert a truncation or sign-change before the 7454 float conversion. */ 7455 tem = create_tmp_var (build_nonstandard_integer_type 7456 (GET_MODE_PRECISION (mode), 0), NULL); 7457 conv = gimple_build_assign_with_ops (NOP_EXPR, tem, rhs1, NULL_TREE); 7458 tem = make_ssa_name (tem, conv); 7459 gimple_assign_set_lhs (conv, tem); 7460 gsi_insert_before (gsi, conv, GSI_SAME_STMT); 7461 gimple_assign_set_rhs1 (stmt, tem); 7462 update_stmt (stmt); 7463 7464 return true; 7465 } 7466 7467 /* Simplify STMT using ranges if possible. */ 7468 7469 static bool 7470 simplify_stmt_using_ranges (gimple_stmt_iterator *gsi) 7471 { 7472 gimple stmt = gsi_stmt (*gsi); 7473 if (is_gimple_assign (stmt)) 7474 { 7475 enum tree_code rhs_code = gimple_assign_rhs_code (stmt); 7476 tree rhs1 = gimple_assign_rhs1 (stmt); 7477 7478 switch (rhs_code) 7479 { 7480 case EQ_EXPR: 7481 case NE_EXPR: 7482 /* Transform EQ_EXPR, NE_EXPR into BIT_XOR_EXPR or identity 7483 if the RHS is zero or one, and the LHS are known to be boolean 7484 values. */ 7485 if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1))) 7486 return simplify_truth_ops_using_ranges (gsi, stmt); 7487 break; 7488 7489 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR 7490 and BIT_AND_EXPR respectively if the first operand is greater 7491 than zero and the second operand is an exact power of two. */ 7492 case TRUNC_DIV_EXPR: 7493 case TRUNC_MOD_EXPR: 7494 if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1)) 7495 && integer_pow2p (gimple_assign_rhs2 (stmt))) 7496 return simplify_div_or_mod_using_ranges (stmt); 7497 break; 7498 7499 /* Transform ABS (X) into X or -X as appropriate. */ 7500 case ABS_EXPR: 7501 if (TREE_CODE (rhs1) == SSA_NAME 7502 && INTEGRAL_TYPE_P (TREE_TYPE (rhs1))) 7503 return simplify_abs_using_ranges (stmt); 7504 break; 7505 7506 case BIT_AND_EXPR: 7507 case BIT_IOR_EXPR: 7508 /* Optimize away BIT_AND_EXPR and BIT_IOR_EXPR 7509 if all the bits being cleared are already cleared or 7510 all the bits being set are already set. */ 7511 if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1))) 7512 return simplify_bit_ops_using_ranges (gsi, stmt); 7513 break; 7514 7515 CASE_CONVERT: 7516 if (TREE_CODE (rhs1) == SSA_NAME 7517 && INTEGRAL_TYPE_P (TREE_TYPE (rhs1))) 7518 return simplify_conversion_using_ranges (stmt); 7519 break; 7520 7521 case FLOAT_EXPR: 7522 if (TREE_CODE (rhs1) == SSA_NAME 7523 && INTEGRAL_TYPE_P (TREE_TYPE (rhs1))) 7524 return simplify_float_conversion_using_ranges (gsi, stmt); 7525 break; 7526 7527 default: 7528 break; 7529 } 7530 } 7531 else if (gimple_code (stmt) == GIMPLE_COND) 7532 return simplify_cond_using_ranges (stmt); 7533 else if (gimple_code (stmt) == GIMPLE_SWITCH) 7534 return simplify_switch_using_ranges (stmt); 7535 7536 return false; 7537 } 7538 7539 /* If the statement pointed by SI has a predicate whose value can be 7540 computed using the value range information computed by VRP, compute 7541 its value and return true. Otherwise, return false. */ 7542 7543 static bool 7544 fold_predicate_in (gimple_stmt_iterator *si) 7545 { 7546 bool assignment_p = false; 7547 tree val; 7548 gimple stmt = gsi_stmt (*si); 7549 7550 if (is_gimple_assign (stmt) 7551 && TREE_CODE_CLASS (gimple_assign_rhs_code (stmt)) == tcc_comparison) 7552 { 7553 assignment_p = true; 7554 val = vrp_evaluate_conditional (gimple_assign_rhs_code (stmt), 7555 gimple_assign_rhs1 (stmt), 7556 gimple_assign_rhs2 (stmt), 7557 stmt); 7558 } 7559 else if (gimple_code (stmt) == GIMPLE_COND) 7560 val = vrp_evaluate_conditional (gimple_cond_code (stmt), 7561 gimple_cond_lhs (stmt), 7562 gimple_cond_rhs (stmt), 7563 stmt); 7564 else 7565 return false; 7566 7567 if (val) 7568 { 7569 if (assignment_p) 7570 val = fold_convert (gimple_expr_type (stmt), val); 7571 7572 if (dump_file) 7573 { 7574 fprintf (dump_file, "Folding predicate "); 7575 print_gimple_expr (dump_file, stmt, 0, 0); 7576 fprintf (dump_file, " to "); 7577 print_generic_expr (dump_file, val, 0); 7578 fprintf (dump_file, "\n"); 7579 } 7580 7581 if (is_gimple_assign (stmt)) 7582 gimple_assign_set_rhs_from_tree (si, val); 7583 else 7584 { 7585 gcc_assert (gimple_code (stmt) == GIMPLE_COND); 7586 if (integer_zerop (val)) 7587 gimple_cond_make_false (stmt); 7588 else if (integer_onep (val)) 7589 gimple_cond_make_true (stmt); 7590 else 7591 gcc_unreachable (); 7592 } 7593 7594 return true; 7595 } 7596 7597 return false; 7598 } 7599 7600 /* Callback for substitute_and_fold folding the stmt at *SI. */ 7601 7602 static bool 7603 vrp_fold_stmt (gimple_stmt_iterator *si) 7604 { 7605 if (fold_predicate_in (si)) 7606 return true; 7607 7608 return simplify_stmt_using_ranges (si); 7609 } 7610 7611 /* Stack of dest,src equivalency pairs that need to be restored after 7612 each attempt to thread a block's incoming edge to an outgoing edge. 7613 7614 A NULL entry is used to mark the end of pairs which need to be 7615 restored. */ 7616 static VEC(tree,heap) *stack; 7617 7618 /* A trivial wrapper so that we can present the generic jump threading 7619 code with a simple API for simplifying statements. STMT is the 7620 statement we want to simplify, WITHIN_STMT provides the location 7621 for any overflow warnings. */ 7622 7623 static tree 7624 simplify_stmt_for_jump_threading (gimple stmt, gimple within_stmt) 7625 { 7626 /* We only use VRP information to simplify conditionals. This is 7627 overly conservative, but it's unclear if doing more would be 7628 worth the compile time cost. */ 7629 if (gimple_code (stmt) != GIMPLE_COND) 7630 return NULL; 7631 7632 return vrp_evaluate_conditional (gimple_cond_code (stmt), 7633 gimple_cond_lhs (stmt), 7634 gimple_cond_rhs (stmt), within_stmt); 7635 } 7636 7637 /* Blocks which have more than one predecessor and more than 7638 one successor present jump threading opportunities, i.e., 7639 when the block is reached from a specific predecessor, we 7640 may be able to determine which of the outgoing edges will 7641 be traversed. When this optimization applies, we are able 7642 to avoid conditionals at runtime and we may expose secondary 7643 optimization opportunities. 7644 7645 This routine is effectively a driver for the generic jump 7646 threading code. It basically just presents the generic code 7647 with edges that may be suitable for jump threading. 7648 7649 Unlike DOM, we do not iterate VRP if jump threading was successful. 7650 While iterating may expose new opportunities for VRP, it is expected 7651 those opportunities would be very limited and the compile time cost 7652 to expose those opportunities would be significant. 7653 7654 As jump threading opportunities are discovered, they are registered 7655 for later realization. */ 7656 7657 static void 7658 identify_jump_threads (void) 7659 { 7660 basic_block bb; 7661 gimple dummy; 7662 int i; 7663 edge e; 7664 7665 /* Ugh. When substituting values earlier in this pass we can 7666 wipe the dominance information. So rebuild the dominator 7667 information as we need it within the jump threading code. */ 7668 calculate_dominance_info (CDI_DOMINATORS); 7669 7670 /* We do not allow VRP information to be used for jump threading 7671 across a back edge in the CFG. Otherwise it becomes too 7672 difficult to avoid eliminating loop exit tests. Of course 7673 EDGE_DFS_BACK is not accurate at this time so we have to 7674 recompute it. */ 7675 mark_dfs_back_edges (); 7676 7677 /* Do not thread across edges we are about to remove. Just marking 7678 them as EDGE_DFS_BACK will do. */ 7679 FOR_EACH_VEC_ELT (edge, to_remove_edges, i, e) 7680 e->flags |= EDGE_DFS_BACK; 7681 7682 /* Allocate our unwinder stack to unwind any temporary equivalences 7683 that might be recorded. */ 7684 stack = VEC_alloc (tree, heap, 20); 7685 7686 /* To avoid lots of silly node creation, we create a single 7687 conditional and just modify it in-place when attempting to 7688 thread jumps. */ 7689 dummy = gimple_build_cond (EQ_EXPR, 7690 integer_zero_node, integer_zero_node, 7691 NULL, NULL); 7692 7693 /* Walk through all the blocks finding those which present a 7694 potential jump threading opportunity. We could set this up 7695 as a dominator walker and record data during the walk, but 7696 I doubt it's worth the effort for the classes of jump 7697 threading opportunities we are trying to identify at this 7698 point in compilation. */ 7699 FOR_EACH_BB (bb) 7700 { 7701 gimple last; 7702 7703 /* If the generic jump threading code does not find this block 7704 interesting, then there is nothing to do. */ 7705 if (! potentially_threadable_block (bb)) 7706 continue; 7707 7708 /* We only care about blocks ending in a COND_EXPR. While there 7709 may be some value in handling SWITCH_EXPR here, I doubt it's 7710 terribly important. */ 7711 last = gsi_stmt (gsi_last_bb (bb)); 7712 7713 /* We're basically looking for a switch or any kind of conditional with 7714 integral or pointer type arguments. Note the type of the second 7715 argument will be the same as the first argument, so no need to 7716 check it explicitly. */ 7717 if (gimple_code (last) == GIMPLE_SWITCH 7718 || (gimple_code (last) == GIMPLE_COND 7719 && TREE_CODE (gimple_cond_lhs (last)) == SSA_NAME 7720 && (INTEGRAL_TYPE_P (TREE_TYPE (gimple_cond_lhs (last))) 7721 || POINTER_TYPE_P (TREE_TYPE (gimple_cond_lhs (last)))) 7722 && (TREE_CODE (gimple_cond_rhs (last)) == SSA_NAME 7723 || is_gimple_min_invariant (gimple_cond_rhs (last))))) 7724 { 7725 edge_iterator ei; 7726 7727 /* We've got a block with multiple predecessors and multiple 7728 successors which also ends in a suitable conditional or 7729 switch statement. For each predecessor, see if we can thread 7730 it to a specific successor. */ 7731 FOR_EACH_EDGE (e, ei, bb->preds) 7732 { 7733 /* Do not thread across back edges or abnormal edges 7734 in the CFG. */ 7735 if (e->flags & (EDGE_DFS_BACK | EDGE_COMPLEX)) 7736 continue; 7737 7738 thread_across_edge (dummy, e, true, &stack, 7739 simplify_stmt_for_jump_threading); 7740 } 7741 } 7742 } 7743 7744 /* We do not actually update the CFG or SSA graphs at this point as 7745 ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet 7746 handle ASSERT_EXPRs gracefully. */ 7747 } 7748 7749 /* We identified all the jump threading opportunities earlier, but could 7750 not transform the CFG at that time. This routine transforms the 7751 CFG and arranges for the dominator tree to be rebuilt if necessary. 7752 7753 Note the SSA graph update will occur during the normal TODO 7754 processing by the pass manager. */ 7755 static void 7756 finalize_jump_threads (void) 7757 { 7758 thread_through_all_blocks (false); 7759 VEC_free (tree, heap, stack); 7760 } 7761 7762 7763 /* Traverse all the blocks folding conditionals with known ranges. */ 7764 7765 static void 7766 vrp_finalize (void) 7767 { 7768 size_t i; 7769 7770 values_propagated = true; 7771 7772 if (dump_file) 7773 { 7774 fprintf (dump_file, "\nValue ranges after VRP:\n\n"); 7775 dump_all_value_ranges (dump_file); 7776 fprintf (dump_file, "\n"); 7777 } 7778 7779 substitute_and_fold (op_with_constant_singleton_value_range, 7780 vrp_fold_stmt, false); 7781 7782 if (warn_array_bounds) 7783 check_all_array_refs (); 7784 7785 /* We must identify jump threading opportunities before we release 7786 the datastructures built by VRP. */ 7787 identify_jump_threads (); 7788 7789 /* Free allocated memory. */ 7790 for (i = 0; i < num_vr_values; i++) 7791 if (vr_value[i]) 7792 { 7793 BITMAP_FREE (vr_value[i]->equiv); 7794 free (vr_value[i]); 7795 } 7796 7797 free (vr_value); 7798 free (vr_phi_edge_counts); 7799 7800 /* So that we can distinguish between VRP data being available 7801 and not available. */ 7802 vr_value = NULL; 7803 vr_phi_edge_counts = NULL; 7804 } 7805 7806 7807 /* Main entry point to VRP (Value Range Propagation). This pass is 7808 loosely based on J. R. C. Patterson, ``Accurate Static Branch 7809 Prediction by Value Range Propagation,'' in SIGPLAN Conference on 7810 Programming Language Design and Implementation, pp. 67-78, 1995. 7811 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html 7812 7813 This is essentially an SSA-CCP pass modified to deal with ranges 7814 instead of constants. 7815 7816 While propagating ranges, we may find that two or more SSA name 7817 have equivalent, though distinct ranges. For instance, 7818 7819 1 x_9 = p_3->a; 7820 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0> 7821 3 if (p_4 == q_2) 7822 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>; 7823 5 endif 7824 6 if (q_2) 7825 7826 In the code above, pointer p_5 has range [q_2, q_2], but from the 7827 code we can also determine that p_5 cannot be NULL and, if q_2 had 7828 a non-varying range, p_5's range should also be compatible with it. 7829 7830 These equivalences are created by two expressions: ASSERT_EXPR and 7831 copy operations. Since p_5 is an assertion on p_4, and p_4 was the 7832 result of another assertion, then we can use the fact that p_5 and 7833 p_4 are equivalent when evaluating p_5's range. 7834 7835 Together with value ranges, we also propagate these equivalences 7836 between names so that we can take advantage of information from 7837 multiple ranges when doing final replacement. Note that this 7838 equivalency relation is transitive but not symmetric. 7839 7840 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we 7841 cannot assert that q_2 is equivalent to p_5 because q_2 may be used 7842 in contexts where that assertion does not hold (e.g., in line 6). 7843 7844 TODO, the main difference between this pass and Patterson's is that 7845 we do not propagate edge probabilities. We only compute whether 7846 edges can be taken or not. That is, instead of having a spectrum 7847 of jump probabilities between 0 and 1, we only deal with 0, 1 and 7848 DON'T KNOW. In the future, it may be worthwhile to propagate 7849 probabilities to aid branch prediction. */ 7850 7851 static unsigned int 7852 execute_vrp (void) 7853 { 7854 int i; 7855 edge e; 7856 switch_update *su; 7857 7858 loop_optimizer_init (LOOPS_NORMAL | LOOPS_HAVE_RECORDED_EXITS); 7859 rewrite_into_loop_closed_ssa (NULL, TODO_update_ssa); 7860 scev_initialize (); 7861 7862 insert_range_assertions (); 7863 7864 /* Estimate number of iterations - but do not use undefined behavior 7865 for this. We can't do this lazily as other functions may compute 7866 this using undefined behavior. */ 7867 free_numbers_of_iterations_estimates (); 7868 estimate_numbers_of_iterations (false); 7869 7870 to_remove_edges = VEC_alloc (edge, heap, 10); 7871 to_update_switch_stmts = VEC_alloc (switch_update, heap, 5); 7872 threadedge_initialize_values (); 7873 7874 vrp_initialize (); 7875 ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node); 7876 vrp_finalize (); 7877 7878 free_numbers_of_iterations_estimates (); 7879 7880 /* ASSERT_EXPRs must be removed before finalizing jump threads 7881 as finalizing jump threads calls the CFG cleanup code which 7882 does not properly handle ASSERT_EXPRs. */ 7883 remove_range_assertions (); 7884 7885 /* If we exposed any new variables, go ahead and put them into 7886 SSA form now, before we handle jump threading. This simplifies 7887 interactions between rewriting of _DECL nodes into SSA form 7888 and rewriting SSA_NAME nodes into SSA form after block 7889 duplication and CFG manipulation. */ 7890 update_ssa (TODO_update_ssa); 7891 7892 finalize_jump_threads (); 7893 7894 /* Remove dead edges from SWITCH_EXPR optimization. This leaves the 7895 CFG in a broken state and requires a cfg_cleanup run. */ 7896 FOR_EACH_VEC_ELT (edge, to_remove_edges, i, e) 7897 remove_edge (e); 7898 /* Update SWITCH_EXPR case label vector. */ 7899 FOR_EACH_VEC_ELT (switch_update, to_update_switch_stmts, i, su) 7900 { 7901 size_t j; 7902 size_t n = TREE_VEC_LENGTH (su->vec); 7903 tree label; 7904 gimple_switch_set_num_labels (su->stmt, n); 7905 for (j = 0; j < n; j++) 7906 gimple_switch_set_label (su->stmt, j, TREE_VEC_ELT (su->vec, j)); 7907 /* As we may have replaced the default label with a regular one 7908 make sure to make it a real default label again. This ensures 7909 optimal expansion. */ 7910 label = gimple_switch_default_label (su->stmt); 7911 CASE_LOW (label) = NULL_TREE; 7912 CASE_HIGH (label) = NULL_TREE; 7913 } 7914 7915 if (VEC_length (edge, to_remove_edges) > 0) 7916 free_dominance_info (CDI_DOMINATORS); 7917 7918 VEC_free (edge, heap, to_remove_edges); 7919 VEC_free (switch_update, heap, to_update_switch_stmts); 7920 threadedge_finalize_values (); 7921 7922 scev_finalize (); 7923 loop_optimizer_finalize (); 7924 return 0; 7925 } 7926 7927 static bool 7928 gate_vrp (void) 7929 { 7930 return flag_tree_vrp != 0; 7931 } 7932 7933 struct gimple_opt_pass pass_vrp = 7934 { 7935 { 7936 GIMPLE_PASS, 7937 "vrp", /* name */ 7938 gate_vrp, /* gate */ 7939 execute_vrp, /* execute */ 7940 NULL, /* sub */ 7941 NULL, /* next */ 7942 0, /* static_pass_number */ 7943 TV_TREE_VRP, /* tv_id */ 7944 PROP_ssa, /* properties_required */ 7945 0, /* properties_provided */ 7946 0, /* properties_destroyed */ 7947 0, /* todo_flags_start */ 7948 TODO_cleanup_cfg 7949 | TODO_update_ssa 7950 | TODO_verify_ssa 7951 | TODO_verify_flow 7952 | TODO_ggc_collect /* todo_flags_finish */ 7953 } 7954 }; 7955