1/* Routines for performing Temporary Expression Replacement (TER) in SSA trees. 2 Copyright (C) 2003-2015 Free Software Foundation, Inc. 3 Contributed by Andrew MacLeod <amacleod@redhat.com> 4 5This file is part of GCC. 6 7GCC is free software; you can redistribute it and/or modify 8it under the terms of the GNU General Public License as published by 9the Free Software Foundation; either version 3, or (at your option) 10any later version. 11 12GCC is distributed in the hope that it will be useful, 13but WITHOUT ANY WARRANTY; without even the implied warranty of 14MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15GNU General Public License for more details. 16 17You should have received a copy of the GNU General Public License 18along with GCC; see the file COPYING3. If not see 19<http://www.gnu.org/licenses/>. */ 20 21 22#include "config.h" 23#include "system.h" 24#include "coretypes.h" 25#include "tm.h" 26#include "hash-set.h" 27#include "machmode.h" 28#include "vec.h" 29#include "double-int.h" 30#include "input.h" 31#include "alias.h" 32#include "symtab.h" 33#include "wide-int.h" 34#include "inchash.h" 35#include "tree.h" 36#include "fold-const.h" 37#include "gimple-pretty-print.h" 38#include "bitmap.h" 39#include "predict.h" 40#include "vec.h" 41#include "hashtab.h" 42#include "hash-set.h" 43#include "machmode.h" 44#include "hard-reg-set.h" 45#include "input.h" 46#include "function.h" 47#include "dominance.h" 48#include "cfg.h" 49#include "basic-block.h" 50#include "tree-ssa-alias.h" 51#include "internal-fn.h" 52#include "gimple-expr.h" 53#include "is-a.h" 54#include "gimple.h" 55#include "gimple-iterator.h" 56#include "gimple-ssa.h" 57#include "tree-phinodes.h" 58#include "ssa-iterators.h" 59#include "stringpool.h" 60#include "tree-ssanames.h" 61#include "dumpfile.h" 62#include "tree-ssa-live.h" 63#include "tree-ssa-ter.h" 64#include "tree-outof-ssa.h" 65#include "flags.h" 66#include "gimple-walk.h" 67 68 69/* Temporary Expression Replacement (TER) 70 71 Replace SSA version variables during out-of-ssa with their defining 72 expression if there is only one use of the variable. 73 74 This pass is required in order for the RTL expansion pass to see larger 75 chunks of code. This allows it to make better choices on RTL pattern 76 selection. When expand is rewritten and merged with out-of-ssa, and 77 understands SSA, this should be eliminated. 78 79 A pass is made through the function, one block at a time. No cross block 80 information is tracked. 81 82 Variables which only have one use, and whose defining stmt is considered 83 a replaceable expression (see ssa_is_replaceable_p) are tracked to see whether 84 they can be replaced at their use location. 85 86 n_12 = C * 10 87 a_2 = b_5 + 6 88 v_9 = a_2 * n_12 89 90 if there are the only use of n_12 and a_2, TER will substitute in their 91 expressions in v_9, and end up with: 92 93 v_9 = (b_5 + 6) * (C * 10) 94 95 which will then have the ssa_name assigned to regular variables, and the 96 resulting code which will be passed to the expander looks something like: 97 98 v = (b + 6) * (C * 10) 99 100 101 This requires ensuring that none of the variables used by the expression 102 change between the def point and where it is used. Furthermore, if any 103 of the ssa_names used in this expression are themselves replaceable, we 104 have to ensure none of that expressions' arguments change either. 105 Although SSA_NAMES themselves don't change, this pass is performed after 106 coalescing has coalesced different SSA_NAMES together, so there could be a 107 definition of an SSA_NAME which is coalesced with a use that causes a 108 problem, i.e., 109 110 PHI b_5 = <b_8(2), b_14(1)> 111 <...> 112 a_2 = b_5 + 6 113 b_8 = c_4 + 4 114 v_9 = a_2 * n_12 115 <...> 116 117 If b_5, b_8 and b_14 are all coalesced together... 118 The expression b_5 + 6 CANNOT replace the use in the statement defining v_9 119 because b_8 is in fact killing the value of b_5 since they share a partition 120 and will be assigned the same memory or register location. 121 122 TER implements this but stepping through the instructions in a block and 123 tracking potential expressions for replacement, and the partitions they are 124 dependent on. Expressions are represented by the SSA_NAME_VERSION of the 125 DEF on the LHS of a GIMPLE_ASSIGN and the expression is the RHS. 126 127 When a stmt is determined to be a possible replacement expression, the 128 following steps are taken: 129 130 EXPR_DECL_UID bitmap is allocated and set to the base variable UID of the 131 def and any uses in the expression. non-NULL means the expression is being 132 tracked. The UID's themselves are used to prevent TER substitution into 133 accumulating sequences, i.e., 134 135 x = x + y 136 x = x + z 137 x = x + w 138 etc. 139 this can result in very large expressions which don't accomplish anything 140 see PR tree-optimization/17549. 141 142 PARTITION_DEPENDENCIES is another bitmap array, and it has a bit set for any 143 partition which is used in the expression. This is primarily used to remove 144 an expression from the partition kill lists when a decision is made whether 145 to replace it or not. This is indexed by ssa version number as well, and 146 indicates a partition number. virtual operands are not tracked individually, 147 but they are summarized by an artificial partition called VIRTUAL_PARTITION. 148 This means a MAY or MUST def will kill *ALL* expressions that are dependent 149 on a virtual operand. 150 Note that the EXPR_DECL_UID and this bitmap represent very similar 151 information, but the info in one is not easy to obtain from the other. 152 153 KILL_LIST is yet another bitmap array, this time it is indexed by partition 154 number, and represents a list of active expressions which will will no 155 longer be valid if a definition into this partition takes place. 156 157 PARTITION_IN_USE is simply a bitmap which is used to track which partitions 158 currently have something in their kill list. This is used at the end of 159 a block to clear out the KILL_LIST bitmaps at the end of each block. 160 161 NEW_REPLACEABLE_DEPENDENCIES is used as a temporary place to store 162 dependencies which will be reused by the current definition. All the uses 163 on an expression are processed before anything else is done. If a use is 164 determined to be a replaceable expression AND the current stmt is also going 165 to be replaceable, all the dependencies of this replaceable use will be 166 picked up by the current stmt's expression. Rather than recreate them, they 167 are simply copied here and then copied into the new expression when it is 168 processed. 169 170 a_2 = b_5 + 6 171 v_8 = a_2 + c_4 172 173 a_2's expression 'b_5 + 6' is determined to be replaceable at the use 174 location. It is dependent on the partition 'b_5' is in. This is cached into 175 the NEW_REPLACEABLE_DEPENDENCIES bitmap, and when v_8 is examined for 176 replaceability, it is a candidate, and it is dependent on the partition 177 b_5 is in *NOT* a_2, as well as c_4's partition. 178 179 if v_8 is also replaceable: 180 181 x_9 = v_8 * 5 182 183 x_9 is dependent on partitions b_5, and c_4 184 185 if a statement is found which has either of those partitions written to 186 before x_9 is used, then x_9 itself is NOT replaceable. */ 187 188 189/* Temporary Expression Replacement (TER) table information. */ 190 191typedef struct temp_expr_table_d 192{ 193 var_map map; 194 bitmap *partition_dependencies; /* Partitions expr is dependent on. */ 195 bitmap replaceable_expressions; /* Replacement expression table. */ 196 bitmap *expr_decl_uids; /* Base uids of exprs. */ 197 bitmap *kill_list; /* Expr's killed by a partition. */ 198 int virtual_partition; /* Pseudo partition for virtual ops. */ 199 bitmap partition_in_use; /* Partitions with kill entries. */ 200 bitmap new_replaceable_dependencies; /* Holding place for pending dep's. */ 201 int *num_in_part; /* # of ssa_names in a partition. */ 202 int *call_cnt; /* Call count at definition. */ 203} *temp_expr_table_p; 204 205/* Used to indicate a dependency on VDEFs. */ 206#define VIRTUAL_PARTITION(table) (table->virtual_partition) 207 208/* A place for the many, many bitmaps we create. */ 209static bitmap_obstack ter_bitmap_obstack; 210 211#ifdef ENABLE_CHECKING 212extern void debug_ter (FILE *, temp_expr_table_p); 213#endif 214 215 216/* Create a new TER table for MAP. */ 217 218static temp_expr_table_p 219new_temp_expr_table (var_map map) 220{ 221 temp_expr_table_p t; 222 unsigned x; 223 224 t = XNEW (struct temp_expr_table_d); 225 t->map = map; 226 227 t->partition_dependencies = XCNEWVEC (bitmap, num_ssa_names + 1); 228 t->expr_decl_uids = XCNEWVEC (bitmap, num_ssa_names + 1); 229 t->kill_list = XCNEWVEC (bitmap, num_var_partitions (map) + 1); 230 231 t->partition_in_use = BITMAP_ALLOC (&ter_bitmap_obstack); 232 233 t->virtual_partition = num_var_partitions (map); 234 t->new_replaceable_dependencies = BITMAP_ALLOC (&ter_bitmap_obstack); 235 236 t->replaceable_expressions = NULL; 237 t->num_in_part = XCNEWVEC (int, num_var_partitions (map)); 238 for (x = 1; x < num_ssa_names; x++) 239 { 240 int p; 241 tree name = ssa_name (x); 242 if (!name) 243 continue; 244 p = var_to_partition (map, name); 245 if (p != NO_PARTITION) 246 t->num_in_part[p]++; 247 } 248 t->call_cnt = XCNEWVEC (int, num_ssa_names + 1); 249 250 return t; 251} 252 253 254/* Free TER table T. If there are valid replacements, return the expression 255 vector. */ 256 257static bitmap 258free_temp_expr_table (temp_expr_table_p t) 259{ 260 bitmap ret = NULL; 261 262#ifdef ENABLE_CHECKING 263 unsigned x; 264 for (x = 0; x <= num_var_partitions (t->map); x++) 265 gcc_assert (!t->kill_list[x]); 266 for (x = 0; x < num_ssa_names; x++) 267 { 268 gcc_assert (t->expr_decl_uids[x] == NULL); 269 gcc_assert (t->partition_dependencies[x] == NULL); 270 } 271#endif 272 273 BITMAP_FREE (t->partition_in_use); 274 BITMAP_FREE (t->new_replaceable_dependencies); 275 276 free (t->expr_decl_uids); 277 free (t->kill_list); 278 free (t->partition_dependencies); 279 free (t->num_in_part); 280 free (t->call_cnt); 281 282 if (t->replaceable_expressions) 283 ret = t->replaceable_expressions; 284 285 free (t); 286 return ret; 287} 288 289 290/* Return TRUE if VERSION is to be replaced by an expression in TAB. */ 291 292static inline bool 293version_to_be_replaced_p (temp_expr_table_p tab, int version) 294{ 295 if (!tab->replaceable_expressions) 296 return false; 297 return bitmap_bit_p (tab->replaceable_expressions, version); 298} 299 300 301/* Add partition P to the list if partitions VERSION is dependent on. TAB is 302 the expression table */ 303 304static inline void 305make_dependent_on_partition (temp_expr_table_p tab, int version, int p) 306{ 307 if (!tab->partition_dependencies[version]) 308 tab->partition_dependencies[version] = BITMAP_ALLOC (&ter_bitmap_obstack); 309 310 bitmap_set_bit (tab->partition_dependencies[version], p); 311} 312 313 314/* Add VER to the kill list for P. TAB is the expression table */ 315 316static inline void 317add_to_partition_kill_list (temp_expr_table_p tab, int p, int ver) 318{ 319 if (!tab->kill_list[p]) 320 { 321 tab->kill_list[p] = BITMAP_ALLOC (&ter_bitmap_obstack); 322 bitmap_set_bit (tab->partition_in_use, p); 323 } 324 bitmap_set_bit (tab->kill_list[p], ver); 325} 326 327 328/* Remove VER from the partition kill list for P. TAB is the expression 329 table. */ 330 331static inline void 332remove_from_partition_kill_list (temp_expr_table_p tab, int p, int version) 333{ 334 gcc_checking_assert (tab->kill_list[p]); 335 bitmap_clear_bit (tab->kill_list[p], version); 336 if (bitmap_empty_p (tab->kill_list[p])) 337 { 338 bitmap_clear_bit (tab->partition_in_use, p); 339 BITMAP_FREE (tab->kill_list[p]); 340 } 341} 342 343 344/* Add a dependency between the def of ssa VERSION and VAR. If VAR is 345 replaceable by an expression, add a dependence each of the elements of the 346 expression. These are contained in the new_replaceable list. TAB is the 347 expression table. */ 348 349static void 350add_dependence (temp_expr_table_p tab, int version, tree var) 351{ 352 int i; 353 bitmap_iterator bi; 354 unsigned x; 355 356 i = SSA_NAME_VERSION (var); 357 if (version_to_be_replaced_p (tab, i)) 358 { 359 if (!bitmap_empty_p (tab->new_replaceable_dependencies)) 360 { 361 /* Version will now be killed by a write to any partition the 362 substituted expression would have been killed by. */ 363 EXECUTE_IF_SET_IN_BITMAP (tab->new_replaceable_dependencies, 0, x, bi) 364 add_to_partition_kill_list (tab, x, version); 365 366 /* Rather than set partition_dependencies and in_use lists bit by 367 bit, simply OR in the new_replaceable_dependencies bits. */ 368 if (!tab->partition_dependencies[version]) 369 tab->partition_dependencies[version] = 370 BITMAP_ALLOC (&ter_bitmap_obstack); 371 bitmap_ior_into (tab->partition_dependencies[version], 372 tab->new_replaceable_dependencies); 373 bitmap_ior_into (tab->partition_in_use, 374 tab->new_replaceable_dependencies); 375 /* It is only necessary to add these once. */ 376 bitmap_clear (tab->new_replaceable_dependencies); 377 } 378 } 379 else 380 { 381 i = var_to_partition (tab->map, var); 382 gcc_checking_assert (i != NO_PARTITION); 383 gcc_checking_assert (tab->num_in_part[i] != 0); 384 /* Only dependencies on ssa_names which are coalesced with something need 385 to be tracked. Partitions with containing only a single SSA_NAME 386 *cannot* have their value changed. */ 387 if (tab->num_in_part[i] > 1) 388 { 389 add_to_partition_kill_list (tab, i, version); 390 make_dependent_on_partition (tab, version, i); 391 } 392 } 393} 394 395 396/* This function will remove the expression for VERSION from replacement 397 consideration in table TAB. If FREE_EXPR is true, then remove the 398 expression from consideration as well by freeing the decl uid bitmap. */ 399 400static void 401finished_with_expr (temp_expr_table_p tab, int version, bool free_expr) 402{ 403 unsigned i; 404 bitmap_iterator bi; 405 406 /* Remove this expression from its dependent lists. The partition dependence 407 list is retained and transferred later to whomever uses this version. */ 408 if (tab->partition_dependencies[version]) 409 { 410 EXECUTE_IF_SET_IN_BITMAP (tab->partition_dependencies[version], 0, i, bi) 411 remove_from_partition_kill_list (tab, i, version); 412 BITMAP_FREE (tab->partition_dependencies[version]); 413 } 414 if (free_expr) 415 BITMAP_FREE (tab->expr_decl_uids[version]); 416} 417 418 419/* Return TRUE if expression STMT is suitable for replacement. 420 In addition to ssa_is_replaceable_p, require the same bb, and for -O0 421 same locus and same BLOCK), Considers memory loads as replaceable if aliasing 422 is available. */ 423 424static inline bool 425ter_is_replaceable_p (gimple stmt) 426{ 427 428 if (ssa_is_replaceable_p (stmt)) 429 { 430 use_operand_p use_p; 431 tree def; 432 gimple use_stmt; 433 location_t locus1, locus2; 434 tree block1, block2; 435 436 /* Only consider definitions which have a single use. ssa_is_replaceable_p 437 already performed this check, but the use stmt pointer is required for 438 further checks. */ 439 def = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_DEF); 440 if (!single_imm_use (def, &use_p, &use_stmt)) 441 return false; 442 443 /* If the use isn't in this block, it wont be replaced either. */ 444 if (gimple_bb (use_stmt) != gimple_bb (stmt)) 445 return false; 446 447 locus1 = gimple_location (stmt); 448 block1 = LOCATION_BLOCK (locus1); 449 locus1 = LOCATION_LOCUS (locus1); 450 451 if (gphi *phi = dyn_cast <gphi *> (use_stmt)) 452 locus2 = gimple_phi_arg_location (phi, 453 PHI_ARG_INDEX_FROM_USE (use_p)); 454 else 455 locus2 = gimple_location (use_stmt); 456 block2 = LOCATION_BLOCK (locus2); 457 locus2 = LOCATION_LOCUS (locus2); 458 459 if ((!optimize || optimize_debug) 460 && ((locus1 != UNKNOWN_LOCATION && locus1 != locus2) 461 || (block1 != NULL_TREE && block1 != block2))) 462 return false; 463 464 return true; 465 } 466 return false; 467} 468 469 470/* Create an expression entry for a replaceable expression. */ 471 472static void 473process_replaceable (temp_expr_table_p tab, gimple stmt, int call_cnt) 474{ 475 tree var, def, basevar; 476 int version; 477 ssa_op_iter iter; 478 bitmap def_vars, use_vars; 479 480 gcc_checking_assert (ter_is_replaceable_p (stmt)); 481 482 def = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_DEF); 483 version = SSA_NAME_VERSION (def); 484 def_vars = BITMAP_ALLOC (&ter_bitmap_obstack); 485 486 basevar = SSA_NAME_VAR (def); 487 if (basevar) 488 bitmap_set_bit (def_vars, DECL_UID (basevar)); 489 490 /* Add this expression to the dependency list for each use partition. */ 491 FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_USE) 492 { 493 int var_version = SSA_NAME_VERSION (var); 494 495 use_vars = tab->expr_decl_uids[var_version]; 496 add_dependence (tab, version, var); 497 if (use_vars) 498 { 499 bitmap_ior_into (def_vars, use_vars); 500 BITMAP_FREE (tab->expr_decl_uids[var_version]); 501 } 502 else if (SSA_NAME_VAR (var)) 503 bitmap_set_bit (def_vars, DECL_UID (SSA_NAME_VAR (var))); 504 } 505 tab->expr_decl_uids[version] = def_vars; 506 507 /* If there are VUSES, add a dependence on virtual defs. */ 508 if (gimple_vuse (stmt)) 509 { 510 make_dependent_on_partition (tab, version, VIRTUAL_PARTITION (tab)); 511 add_to_partition_kill_list (tab, VIRTUAL_PARTITION (tab), version); 512 } 513 514 tab->call_cnt[version] = call_cnt; 515} 516 517 518/* This function removes any expression in TAB which is dependent on PARTITION 519 from consideration, making it not replaceable. */ 520 521static inline void 522kill_expr (temp_expr_table_p tab, int partition) 523{ 524 unsigned version; 525 526 /* Mark every active expr dependent on this var as not replaceable. 527 finished_with_expr can modify the bitmap, so we can't execute over it. */ 528 while (tab->kill_list[partition]) 529 { 530 version = bitmap_first_set_bit (tab->kill_list[partition]); 531 finished_with_expr (tab, version, true); 532 } 533 534 gcc_checking_assert (!tab->kill_list[partition]); 535} 536 537 538/* This function kills all expressions in TAB which are dependent on virtual 539 partitions. */ 540 541static inline void 542kill_virtual_exprs (temp_expr_table_p tab) 543{ 544 kill_expr (tab, VIRTUAL_PARTITION (tab)); 545} 546 547 548/* Mark the expression associated with VAR as replaceable, and enter 549 the defining stmt into the partition_dependencies table TAB. If 550 MORE_REPLACING is true, accumulate the pending partition dependencies. */ 551 552static void 553mark_replaceable (temp_expr_table_p tab, tree var, bool more_replacing) 554{ 555 int version = SSA_NAME_VERSION (var); 556 557 /* Move the dependence list to the pending listpending. */ 558 if (more_replacing && tab->partition_dependencies[version]) 559 bitmap_ior_into (tab->new_replaceable_dependencies, 560 tab->partition_dependencies[version]); 561 562 finished_with_expr (tab, version, !more_replacing); 563 564 /* Set the replaceable expression. 565 The bitmap for this "escapes" from this file so it's allocated 566 on the default obstack. */ 567 if (!tab->replaceable_expressions) 568 tab->replaceable_expressions = BITMAP_ALLOC (NULL); 569 bitmap_set_bit (tab->replaceable_expressions, version); 570} 571 572 573/* Helper function for find_ssaname_in_stores. Called via walk_tree to 574 find a SSA_NAME DATA somewhere in *TP. */ 575 576static tree 577find_ssaname (tree *tp, int *walk_subtrees, void *data) 578{ 579 tree var = (tree) data; 580 if (*tp == var) 581 return var; 582 else if (IS_TYPE_OR_DECL_P (*tp)) 583 *walk_subtrees = 0; 584 return NULL_TREE; 585} 586 587/* Helper function for find_replaceable_in_bb. Return true if SSA_NAME DATA 588 is used somewhere in T, which is a store in the statement. Called via 589 walk_stmt_load_store_addr_ops. */ 590 591static bool 592find_ssaname_in_store (gimple, tree, tree t, void *data) 593{ 594 return walk_tree (&t, find_ssaname, data, NULL) != NULL_TREE; 595} 596 597/* This function processes basic block BB, and looks for variables which can 598 be replaced by their expressions. Results are stored in the table TAB. */ 599 600static void 601find_replaceable_in_bb (temp_expr_table_p tab, basic_block bb) 602{ 603 gimple_stmt_iterator bsi; 604 gimple stmt; 605 tree def, use, fndecl; 606 int partition; 607 var_map map = tab->map; 608 ssa_op_iter iter; 609 bool stmt_replaceable; 610 int cur_call_cnt = 0; 611 612 for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi)) 613 { 614 stmt = gsi_stmt (bsi); 615 616 if (is_gimple_debug (stmt)) 617 continue; 618 619 stmt_replaceable = ter_is_replaceable_p (stmt); 620 621 /* Determine if this stmt finishes an existing expression. */ 622 FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE) 623 { 624 unsigned ver = SSA_NAME_VERSION (use); 625 626 /* If this use is a potential replacement variable, process it. */ 627 if (tab->expr_decl_uids[ver]) 628 { 629 bool same_root_var = false; 630 ssa_op_iter iter2; 631 bitmap vars = tab->expr_decl_uids[ver]; 632 633 /* See if the root variables are the same. If they are, we 634 do not want to do the replacement to avoid problems with 635 code size, see PR tree-optimization/17549. */ 636 if (!bitmap_empty_p (vars)) 637 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter2, SSA_OP_DEF) 638 { 639 if (SSA_NAME_VAR (def) 640 && bitmap_bit_p (vars, DECL_UID (SSA_NAME_VAR (def)))) 641 { 642 same_root_var = true; 643 break; 644 } 645 } 646 647 /* If the stmt does a memory store and the replacement 648 is a load aliasing it avoid creating overlapping 649 assignments which we cannot expand correctly. */ 650 if (gimple_vdef (stmt)) 651 { 652 gimple def_stmt = SSA_NAME_DEF_STMT (use); 653 while (is_gimple_assign (def_stmt) 654 && gimple_assign_rhs_code (def_stmt) == SSA_NAME) 655 def_stmt 656 = SSA_NAME_DEF_STMT (gimple_assign_rhs1 (def_stmt)); 657 if (gimple_vuse (def_stmt) 658 && gimple_assign_single_p (def_stmt) 659 && stmt_may_clobber_ref_p (stmt, 660 gimple_assign_rhs1 (def_stmt))) 661 { 662 /* For calls, it is not a problem if USE is among 663 call's arguments or say OBJ_TYPE_REF argument, 664 all those necessarily need to be evaluated before 665 the call that may clobber the memory. But if 666 LHS of the call refers to USE, expansion might 667 evaluate it after the call, prevent TER in that 668 case. 669 For inline asm, allow TER of loads into input 670 arguments, but disallow TER for USEs that occur 671 somewhere in outputs. */ 672 if (is_gimple_call (stmt) 673 || gimple_code (stmt) == GIMPLE_ASM) 674 { 675 if (walk_stmt_load_store_ops (stmt, use, NULL, 676 find_ssaname_in_store)) 677 same_root_var = true; 678 } 679 else 680 same_root_var = true; 681 } 682 } 683 684 /* Mark expression as replaceable unless stmt is volatile, or the 685 def variable has the same root variable as something in the 686 substitution list, or the def and use span a call such that 687 we'll expand lifetimes across a call. */ 688 if (gimple_has_volatile_ops (stmt) || same_root_var 689 || (tab->call_cnt[ver] != cur_call_cnt 690 && SINGLE_SSA_USE_OPERAND (SSA_NAME_DEF_STMT (use), SSA_OP_USE) 691 == NULL_USE_OPERAND_P)) 692 finished_with_expr (tab, ver, true); 693 else 694 mark_replaceable (tab, use, stmt_replaceable); 695 } 696 } 697 698 /* Next, see if this stmt kills off an active expression. */ 699 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF) 700 { 701 partition = var_to_partition (map, def); 702 if (partition != NO_PARTITION && tab->kill_list[partition]) 703 kill_expr (tab, partition); 704 } 705 706 /* Increment counter if this is a non BUILT_IN call. We allow 707 replacement over BUILT_IN calls since many will expand to inline 708 insns instead of a true call. */ 709 if (is_gimple_call (stmt) 710 && !((fndecl = gimple_call_fndecl (stmt)) 711 && DECL_BUILT_IN (fndecl))) 712 cur_call_cnt++; 713 714 /* Now see if we are creating a new expression or not. */ 715 if (stmt_replaceable) 716 process_replaceable (tab, stmt, cur_call_cnt); 717 718 /* Free any unused dependency lists. */ 719 bitmap_clear (tab->new_replaceable_dependencies); 720 721 /* A V_{MAY,MUST}_DEF kills any expression using a virtual operand, 722 including the current stmt. */ 723 if (gimple_vdef (stmt)) 724 kill_virtual_exprs (tab); 725 } 726} 727 728 729/* This function is the driver routine for replacement of temporary expressions 730 in the SSA->normal phase, operating on MAP. If there are replaceable 731 expressions, a table is returned which maps SSA versions to the 732 expressions they should be replaced with. A NULL_TREE indicates no 733 replacement should take place. If there are no replacements at all, 734 NULL is returned by the function, otherwise an expression vector indexed 735 by SSA_NAME version numbers. */ 736 737bitmap 738find_replaceable_exprs (var_map map) 739{ 740 basic_block bb; 741 temp_expr_table_p table; 742 bitmap ret; 743 744 bitmap_obstack_initialize (&ter_bitmap_obstack); 745 table = new_temp_expr_table (map); 746 FOR_EACH_BB_FN (bb, cfun) 747 { 748 find_replaceable_in_bb (table, bb); 749 gcc_checking_assert (bitmap_empty_p (table->partition_in_use)); 750 } 751 ret = free_temp_expr_table (table); 752 bitmap_obstack_release (&ter_bitmap_obstack); 753 return ret; 754} 755 756/* Dump TER expression table EXPR to file F. */ 757 758void 759dump_replaceable_exprs (FILE *f, bitmap expr) 760{ 761 tree var; 762 unsigned x; 763 764 fprintf (f, "\nReplacing Expressions\n"); 765 for (x = 0; x < num_ssa_names; x++) 766 if (bitmap_bit_p (expr, x)) 767 { 768 var = ssa_name (x); 769 print_generic_expr (f, var, TDF_SLIM); 770 fprintf (f, " replace with --> "); 771 print_gimple_stmt (f, SSA_NAME_DEF_STMT (var), 0, TDF_SLIM); 772 fprintf (f, "\n"); 773 } 774 fprintf (f, "\n"); 775} 776 777 778#ifdef ENABLE_CHECKING 779/* Dump the status of the various tables in the expression table. This is used 780 exclusively to debug TER. F is the place to send debug info and T is the 781 table being debugged. */ 782 783DEBUG_FUNCTION void 784debug_ter (FILE *f, temp_expr_table_p t) 785{ 786 unsigned x, y; 787 bitmap_iterator bi; 788 789 fprintf (f, "\nDumping current state of TER\n virtual partition = %d\n", 790 VIRTUAL_PARTITION (t)); 791 if (t->replaceable_expressions) 792 dump_replaceable_exprs (f, t->replaceable_expressions); 793 fprintf (f, "Currently tracking the following expressions:\n"); 794 795 for (x = 1; x < num_ssa_names; x++) 796 if (t->expr_decl_uids[x]) 797 { 798 print_generic_expr (f, ssa_name (x), TDF_SLIM); 799 fprintf (f, " dep-parts : "); 800 if (t->partition_dependencies[x] 801 && !bitmap_empty_p (t->partition_dependencies[x])) 802 { 803 EXECUTE_IF_SET_IN_BITMAP (t->partition_dependencies[x], 0, y, bi) 804 fprintf (f, "P%d ",y); 805 } 806 fprintf (f, " basedecls: "); 807 EXECUTE_IF_SET_IN_BITMAP (t->expr_decl_uids[x], 0, y, bi) 808 fprintf (f, "%d ",y); 809 fprintf (f, " call_cnt : %d",t->call_cnt[x]); 810 fprintf (f, "\n"); 811 } 812 813 bitmap_print (f, t->partition_in_use, "Partitions in use ", 814 "\npartition KILL lists:\n"); 815 816 for (x = 0; x <= num_var_partitions (t->map); x++) 817 if (t->kill_list[x]) 818 { 819 fprintf (f, "Partition %d : ", x); 820 EXECUTE_IF_SET_IN_BITMAP (t->kill_list[x], 0, y, bi) 821 fprintf (f, "_%d ",y); 822 } 823 824 fprintf (f, "\n----------\n"); 825} 826#endif 827