1/* High-level loop manipulation functions. 2 Copyright (C) 2004-2022 Free Software Foundation, Inc. 3 4This file is part of GCC. 5 6GCC is free software; you can redistribute it and/or modify it 7under the terms of the GNU General Public License as published by the 8Free Software Foundation; either version 3, or (at your option) any 9later version. 10 11GCC is distributed in the hope that it will be useful, but WITHOUT 12ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14for more details. 15 16You should have received a copy of the GNU General Public License 17along with GCC; see the file COPYING3. If not see 18<http://www.gnu.org/licenses/>. */ 19 20#include "config.h" 21#include "system.h" 22#include "coretypes.h" 23#include "backend.h" 24#include "tree.h" 25#include "gimple.h" 26#include "cfghooks.h" 27#include "tree-pass.h" /* ??? for TODO_update_ssa but this isn't a pass. */ 28#include "ssa.h" 29#include "gimple-pretty-print.h" 30#include "fold-const.h" 31#include "cfganal.h" 32#include "gimplify.h" 33#include "gimple-iterator.h" 34#include "gimplify-me.h" 35#include "tree-cfg.h" 36#include "tree-ssa-loop-ivopts.h" 37#include "tree-ssa-loop-manip.h" 38#include "tree-ssa-loop-niter.h" 39#include "tree-ssa-loop.h" 40#include "tree-into-ssa.h" 41#include "tree-ssa.h" 42#include "cfgloop.h" 43#include "tree-scalar-evolution.h" 44#include "tree-inline.h" 45 46/* All bitmaps for rewriting into loop-closed SSA go on this obstack, 47 so that we can free them all at once. */ 48static bitmap_obstack loop_renamer_obstack; 49 50/* Creates an induction variable with value BASE + STEP * iteration in LOOP. 51 It is expected that neither BASE nor STEP are shared with other expressions 52 (unless the sharing rules allow this). Use VAR as a base var_decl for it 53 (if NULL, a new temporary will be created). The increment will occur at 54 INCR_POS (after it if AFTER is true, before it otherwise). INCR_POS and 55 AFTER can be computed using standard_iv_increment_position. The ssa versions 56 of the variable before and after increment will be stored in VAR_BEFORE and 57 VAR_AFTER (unless they are NULL). */ 58 59void 60create_iv (tree base, tree step, tree var, class loop *loop, 61 gimple_stmt_iterator *incr_pos, bool after, 62 tree *var_before, tree *var_after) 63{ 64 gassign *stmt; 65 gphi *phi; 66 tree initial, step1; 67 gimple_seq stmts; 68 tree vb, va; 69 enum tree_code incr_op = PLUS_EXPR; 70 edge pe = loop_preheader_edge (loop); 71 72 if (var != NULL_TREE) 73 { 74 vb = make_ssa_name (var); 75 va = make_ssa_name (var); 76 } 77 else 78 { 79 vb = make_temp_ssa_name (TREE_TYPE (base), NULL, "ivtmp"); 80 va = make_temp_ssa_name (TREE_TYPE (base), NULL, "ivtmp"); 81 } 82 if (var_before) 83 *var_before = vb; 84 if (var_after) 85 *var_after = va; 86 87 /* For easier readability of the created code, produce MINUS_EXPRs 88 when suitable. */ 89 if (TREE_CODE (step) == INTEGER_CST) 90 { 91 if (TYPE_UNSIGNED (TREE_TYPE (step))) 92 { 93 step1 = fold_build1 (NEGATE_EXPR, TREE_TYPE (step), step); 94 if (tree_int_cst_lt (step1, step)) 95 { 96 incr_op = MINUS_EXPR; 97 step = step1; 98 } 99 } 100 else 101 { 102 bool ovf; 103 104 if (!tree_expr_nonnegative_warnv_p (step, &ovf) 105 && may_negate_without_overflow_p (step)) 106 { 107 incr_op = MINUS_EXPR; 108 step = fold_build1 (NEGATE_EXPR, TREE_TYPE (step), step); 109 } 110 } 111 } 112 if (POINTER_TYPE_P (TREE_TYPE (base))) 113 { 114 if (TREE_CODE (base) == ADDR_EXPR) 115 mark_addressable (TREE_OPERAND (base, 0)); 116 step = convert_to_ptrofftype (step); 117 if (incr_op == MINUS_EXPR) 118 step = fold_build1 (NEGATE_EXPR, TREE_TYPE (step), step); 119 incr_op = POINTER_PLUS_EXPR; 120 } 121 /* Gimplify the step if necessary. We put the computations in front of the 122 loop (i.e. the step should be loop invariant). */ 123 step = force_gimple_operand (step, &stmts, true, NULL_TREE); 124 if (stmts) 125 gsi_insert_seq_on_edge_immediate (pe, stmts); 126 127 stmt = gimple_build_assign (va, incr_op, vb, step); 128 /* Prevent the increment from inheriting a bogus location if it is not put 129 immediately after a statement whose location is known. */ 130 if (after) 131 { 132 if (gsi_end_p (*incr_pos) 133 || (is_gimple_debug (gsi_stmt (*incr_pos)) 134 && gsi_bb (*incr_pos) 135 && gsi_end_p (gsi_last_nondebug_bb (gsi_bb (*incr_pos))))) 136 { 137 edge e = single_succ_edge (gsi_bb (*incr_pos)); 138 gimple_set_location (stmt, e->goto_locus); 139 } 140 gsi_insert_after (incr_pos, stmt, GSI_NEW_STMT); 141 } 142 else 143 { 144 gimple_stmt_iterator gsi = *incr_pos; 145 if (!gsi_end_p (gsi) && is_gimple_debug (gsi_stmt (gsi))) 146 gsi_next_nondebug (&gsi); 147 if (!gsi_end_p (gsi)) 148 gimple_set_location (stmt, gimple_location (gsi_stmt (gsi))); 149 gsi_insert_before (incr_pos, stmt, GSI_NEW_STMT); 150 } 151 152 initial = force_gimple_operand (base, &stmts, true, var); 153 if (stmts) 154 gsi_insert_seq_on_edge_immediate (pe, stmts); 155 156 phi = create_phi_node (vb, loop->header); 157 add_phi_arg (phi, initial, loop_preheader_edge (loop), UNKNOWN_LOCATION); 158 add_phi_arg (phi, va, loop_latch_edge (loop), UNKNOWN_LOCATION); 159} 160 161/* Return the innermost superloop LOOP of USE_LOOP that is a superloop of 162 both DEF_LOOP and USE_LOOP. */ 163 164static inline class loop * 165find_sibling_superloop (class loop *use_loop, class loop *def_loop) 166{ 167 unsigned ud = loop_depth (use_loop); 168 unsigned dd = loop_depth (def_loop); 169 gcc_assert (ud > 0 && dd > 0); 170 if (ud > dd) 171 use_loop = superloop_at_depth (use_loop, dd); 172 if (ud < dd) 173 def_loop = superloop_at_depth (def_loop, ud); 174 while (loop_outer (use_loop) != loop_outer (def_loop)) 175 { 176 use_loop = loop_outer (use_loop); 177 def_loop = loop_outer (def_loop); 178 gcc_assert (use_loop && def_loop); 179 } 180 return use_loop; 181} 182 183/* DEF_BB is a basic block containing a DEF that needs rewriting into 184 loop-closed SSA form. USE_BLOCKS is the set of basic blocks containing 185 uses of DEF that "escape" from the loop containing DEF_BB (i.e. blocks in 186 USE_BLOCKS are dominated by DEF_BB but not in the loop father of DEF_B). 187 ALL_EXITS[I] is the set of all basic blocks that exit loop I. 188 189 Compute the subset of LOOP_EXITS that exit the loop containing DEF_BB 190 or one of its loop fathers, in which DEF is live. This set is returned 191 in the bitmap LIVE_EXITS. 192 193 Instead of computing the complete livein set of the def, we use the loop 194 nesting tree as a form of poor man's structure analysis. This greatly 195 speeds up the analysis, which is important because this function may be 196 called on all SSA names that need rewriting, one at a time. */ 197 198static void 199compute_live_loop_exits (bitmap live_exits, bitmap use_blocks, 200 bitmap *loop_exits, basic_block def_bb) 201{ 202 unsigned i; 203 bitmap_iterator bi; 204 class loop *def_loop = def_bb->loop_father; 205 unsigned def_loop_depth = loop_depth (def_loop); 206 bitmap def_loop_exits; 207 208 /* Normally the work list size is bounded by the number of basic 209 blocks in the largest loop. We don't know this number, but we 210 can be fairly sure that it will be relatively small. */ 211 auto_vec<basic_block> worklist (MAX (8, n_basic_blocks_for_fn (cfun) / 128)); 212 213 EXECUTE_IF_SET_IN_BITMAP (use_blocks, 0, i, bi) 214 { 215 basic_block use_bb = BASIC_BLOCK_FOR_FN (cfun, i); 216 class loop *use_loop = use_bb->loop_father; 217 gcc_checking_assert (def_loop != use_loop 218 && ! flow_loop_nested_p (def_loop, use_loop)); 219 if (! flow_loop_nested_p (use_loop, def_loop)) 220 use_bb = find_sibling_superloop (use_loop, def_loop)->header; 221 if (bitmap_set_bit (live_exits, use_bb->index)) 222 worklist.safe_push (use_bb); 223 } 224 225 /* Iterate until the worklist is empty. */ 226 while (! worklist.is_empty ()) 227 { 228 edge e; 229 edge_iterator ei; 230 231 /* Pull a block off the worklist. */ 232 basic_block bb = worklist.pop (); 233 234 /* Make sure we have at least enough room in the work list 235 for all predecessors of this block. */ 236 worklist.reserve (EDGE_COUNT (bb->preds)); 237 238 /* For each predecessor block. */ 239 FOR_EACH_EDGE (e, ei, bb->preds) 240 { 241 basic_block pred = e->src; 242 class loop *pred_loop = pred->loop_father; 243 unsigned pred_loop_depth = loop_depth (pred_loop); 244 bool pred_visited; 245 246 /* We should have met DEF_BB along the way. */ 247 gcc_assert (pred != ENTRY_BLOCK_PTR_FOR_FN (cfun)); 248 249 if (pred_loop_depth >= def_loop_depth) 250 { 251 if (pred_loop_depth > def_loop_depth) 252 pred_loop = superloop_at_depth (pred_loop, def_loop_depth); 253 /* If we've reached DEF_LOOP, our train ends here. */ 254 if (pred_loop == def_loop) 255 continue; 256 } 257 else if (! flow_loop_nested_p (pred_loop, def_loop)) 258 pred = find_sibling_superloop (pred_loop, def_loop)->header; 259 260 /* Add PRED to the LIVEIN set. PRED_VISITED is true if 261 we had already added PRED to LIVEIN before. */ 262 pred_visited = !bitmap_set_bit (live_exits, pred->index); 263 264 /* If we have visited PRED before, don't add it to the worklist. 265 If BB dominates PRED, then we're probably looking at a loop. 266 We're only interested in looking up in the dominance tree 267 because DEF_BB dominates all the uses. */ 268 if (pred_visited || dominated_by_p (CDI_DOMINATORS, pred, bb)) 269 continue; 270 271 worklist.quick_push (pred); 272 } 273 } 274 275 def_loop_exits = BITMAP_ALLOC (&loop_renamer_obstack); 276 for (class loop *loop = def_loop; 277 loop != current_loops->tree_root; 278 loop = loop_outer (loop)) 279 bitmap_ior_into (def_loop_exits, loop_exits[loop->num]); 280 bitmap_and_into (live_exits, def_loop_exits); 281 BITMAP_FREE (def_loop_exits); 282} 283 284/* Add a loop-closing PHI for VAR in basic block EXIT. */ 285 286static void 287add_exit_phi (basic_block exit, tree var) 288{ 289 gphi *phi; 290 edge e; 291 edge_iterator ei; 292 293 /* Check that at least one of the edges entering the EXIT block exits 294 the loop, or a superloop of that loop, that VAR is defined in. */ 295 if (flag_checking) 296 { 297 gimple *def_stmt = SSA_NAME_DEF_STMT (var); 298 basic_block def_bb = gimple_bb (def_stmt); 299 FOR_EACH_EDGE (e, ei, exit->preds) 300 { 301 class loop *aloop = find_common_loop (def_bb->loop_father, 302 e->src->loop_father); 303 if (!flow_bb_inside_loop_p (aloop, e->dest)) 304 break; 305 } 306 gcc_assert (e); 307 } 308 309 phi = create_phi_node (NULL_TREE, exit); 310 create_new_def_for (var, phi, gimple_phi_result_ptr (phi)); 311 FOR_EACH_EDGE (e, ei, exit->preds) 312 add_phi_arg (phi, var, e, UNKNOWN_LOCATION); 313 314 if (dump_file && (dump_flags & TDF_DETAILS)) 315 { 316 fprintf (dump_file, ";; Created LCSSA PHI: "); 317 print_gimple_stmt (dump_file, phi, 0, dump_flags); 318 } 319} 320 321/* Add exit phis for VAR that is used in LIVEIN. 322 Exits of the loops are stored in LOOP_EXITS. */ 323 324static void 325add_exit_phis_var (tree var, bitmap use_blocks, bitmap *loop_exits) 326{ 327 unsigned index; 328 bitmap_iterator bi; 329 basic_block def_bb = gimple_bb (SSA_NAME_DEF_STMT (var)); 330 bitmap live_exits = BITMAP_ALLOC (&loop_renamer_obstack); 331 332 gcc_checking_assert (! bitmap_bit_p (use_blocks, def_bb->index)); 333 334 compute_live_loop_exits (live_exits, use_blocks, loop_exits, def_bb); 335 336 EXECUTE_IF_SET_IN_BITMAP (live_exits, 0, index, bi) 337 { 338 add_exit_phi (BASIC_BLOCK_FOR_FN (cfun, index), var); 339 } 340 341 BITMAP_FREE (live_exits); 342} 343 344/* Add exit phis for the names marked in NAMES_TO_RENAME. 345 Exits of the loops are stored in EXITS. Sets of blocks where the ssa 346 names are used are stored in USE_BLOCKS. */ 347 348static void 349add_exit_phis (bitmap names_to_rename, bitmap *use_blocks, bitmap *loop_exits) 350{ 351 unsigned i; 352 bitmap_iterator bi; 353 354 EXECUTE_IF_SET_IN_BITMAP (names_to_rename, 0, i, bi) 355 { 356 add_exit_phis_var (ssa_name (i), use_blocks[i], loop_exits); 357 } 358} 359 360/* Fill the array of bitmaps LOOP_EXITS with all loop exit edge targets. */ 361 362static void 363get_loops_exits (bitmap *loop_exits) 364{ 365 unsigned j; 366 edge e; 367 368 for (auto loop : loops_list (cfun, 0)) 369 { 370 auto_vec<edge> exit_edges = get_loop_exit_edges (loop); 371 loop_exits[loop->num] = BITMAP_ALLOC (&loop_renamer_obstack); 372 FOR_EACH_VEC_ELT (exit_edges, j, e) 373 bitmap_set_bit (loop_exits[loop->num], e->dest->index); 374 } 375} 376 377/* For USE in BB, if it is used outside of the loop it is defined in, 378 mark it for rewrite. Record basic block BB where it is used 379 to USE_BLOCKS. Record the ssa name index to NEED_PHIS bitmap. 380 Note that for USEs in phis, BB should be the src of the edge corresponding to 381 the use, rather than the bb containing the phi. */ 382 383static void 384find_uses_to_rename_use (basic_block bb, tree use, bitmap *use_blocks, 385 bitmap need_phis) 386{ 387 unsigned ver; 388 basic_block def_bb; 389 class loop *def_loop; 390 391 if (TREE_CODE (use) != SSA_NAME) 392 return; 393 394 ver = SSA_NAME_VERSION (use); 395 def_bb = gimple_bb (SSA_NAME_DEF_STMT (use)); 396 if (!def_bb) 397 return; 398 def_loop = def_bb->loop_father; 399 400 /* If the definition is not inside a loop, it is not interesting. */ 401 if (!loop_outer (def_loop)) 402 return; 403 404 /* If the use is not outside of the loop it is defined in, it is not 405 interesting. */ 406 if (flow_bb_inside_loop_p (def_loop, bb)) 407 return; 408 409 /* If we're seeing VER for the first time, we still have to allocate 410 a bitmap for its uses. */ 411 if (bitmap_set_bit (need_phis, ver)) 412 use_blocks[ver] = BITMAP_ALLOC (&loop_renamer_obstack); 413 bitmap_set_bit (use_blocks[ver], bb->index); 414} 415 416/* For uses matching USE_FLAGS in STMT, mark names that are used outside of the 417 loop they are defined to rewrite. Record the set of blocks in which the ssa 418 names are used to USE_BLOCKS, and the ssa names themselves to NEED_PHIS. */ 419 420static void 421find_uses_to_rename_stmt (gimple *stmt, bitmap *use_blocks, bitmap need_phis, 422 int use_flags) 423{ 424 ssa_op_iter iter; 425 tree var; 426 basic_block bb = gimple_bb (stmt); 427 428 if (is_gimple_debug (stmt)) 429 return; 430 431 /* FOR_EACH_SSA_TREE_OPERAND iterator does not allows SSA_OP_VIRTUAL_USES 432 only. */ 433 if (use_flags == SSA_OP_VIRTUAL_USES) 434 { 435 tree vuse = gimple_vuse (stmt); 436 if (vuse != NULL_TREE) 437 find_uses_to_rename_use (bb, gimple_vuse (stmt), use_blocks, need_phis); 438 } 439 else 440 FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, use_flags) 441 find_uses_to_rename_use (bb, var, use_blocks, need_phis); 442} 443 444/* Marks names matching USE_FLAGS that are used in BB and outside of the loop 445 they are defined in for rewrite. Records the set of blocks in which the ssa 446 names are used to USE_BLOCKS. Record the SSA names that will 447 need exit PHIs in NEED_PHIS. */ 448 449static void 450find_uses_to_rename_bb (basic_block bb, bitmap *use_blocks, bitmap need_phis, 451 int use_flags) 452{ 453 edge e; 454 edge_iterator ei; 455 bool do_virtuals = (use_flags & SSA_OP_VIRTUAL_USES) != 0; 456 bool do_nonvirtuals = (use_flags & SSA_OP_USE) != 0; 457 458 FOR_EACH_EDGE (e, ei, bb->succs) 459 for (gphi_iterator bsi = gsi_start_phis (e->dest); !gsi_end_p (bsi); 460 gsi_next (&bsi)) 461 { 462 gphi *phi = bsi.phi (); 463 bool virtual_p = virtual_operand_p (gimple_phi_result (phi)); 464 if ((virtual_p && do_virtuals) 465 || (!virtual_p && do_nonvirtuals)) 466 find_uses_to_rename_use (bb, PHI_ARG_DEF_FROM_EDGE (phi, e), 467 use_blocks, need_phis); 468 } 469 470 for (gimple_stmt_iterator bsi = gsi_start_bb (bb); !gsi_end_p (bsi); 471 gsi_next (&bsi)) 472 find_uses_to_rename_stmt (gsi_stmt (bsi), use_blocks, need_phis, 473 use_flags); 474} 475 476/* Marks names matching USE_FLAGS that are used outside of the loop they are 477 defined in for rewrite. Records the set of blocks in which the ssa names are 478 used to USE_BLOCKS. Record the SSA names that will need exit PHIs in 479 NEED_PHIS. If CHANGED_BBS is not NULL, scan only blocks in this set. */ 480 481static void 482find_uses_to_rename (bitmap changed_bbs, bitmap *use_blocks, bitmap need_phis, 483 int use_flags) 484{ 485 basic_block bb; 486 unsigned index; 487 bitmap_iterator bi; 488 489 if (changed_bbs) 490 EXECUTE_IF_SET_IN_BITMAP (changed_bbs, 0, index, bi) 491 { 492 bb = BASIC_BLOCK_FOR_FN (cfun, index); 493 if (bb) 494 find_uses_to_rename_bb (bb, use_blocks, need_phis, use_flags); 495 } 496 else 497 FOR_EACH_BB_FN (bb, cfun) 498 find_uses_to_rename_bb (bb, use_blocks, need_phis, use_flags); 499} 500 501/* Mark uses of DEF that are used outside of the loop they are defined in for 502 rewrite. Record the set of blocks in which the ssa names are used to 503 USE_BLOCKS. Record the SSA names that will need exit PHIs in NEED_PHIS. */ 504 505static void 506find_uses_to_rename_def (tree def, bitmap *use_blocks, bitmap need_phis) 507{ 508 gimple *use_stmt; 509 imm_use_iterator imm_iter; 510 511 FOR_EACH_IMM_USE_STMT (use_stmt, imm_iter, def) 512 { 513 if (is_gimple_debug (use_stmt)) 514 continue; 515 516 basic_block use_bb = gimple_bb (use_stmt); 517 518 use_operand_p use_p; 519 FOR_EACH_IMM_USE_ON_STMT (use_p, imm_iter) 520 { 521 if (gimple_code (use_stmt) == GIMPLE_PHI) 522 { 523 edge e = gimple_phi_arg_edge (as_a <gphi *> (use_stmt), 524 PHI_ARG_INDEX_FROM_USE (use_p)); 525 use_bb = e->src; 526 } 527 find_uses_to_rename_use (use_bb, USE_FROM_PTR (use_p), use_blocks, 528 need_phis); 529 } 530 } 531} 532 533/* Marks names matching USE_FLAGS that are defined in LOOP and used outside of 534 it for rewrite. Records the set of blocks in which the ssa names are used to 535 USE_BLOCKS. Record the SSA names that will need exit PHIs in NEED_PHIS. */ 536 537static void 538find_uses_to_rename_in_loop (class loop *loop, bitmap *use_blocks, 539 bitmap need_phis, int use_flags) 540{ 541 bool do_virtuals = (use_flags & SSA_OP_VIRTUAL_USES) != 0; 542 bool do_nonvirtuals = (use_flags & SSA_OP_USE) != 0; 543 int def_flags = ((do_virtuals ? SSA_OP_VIRTUAL_DEFS : 0) 544 | (do_nonvirtuals ? SSA_OP_DEF : 0)); 545 546 547 basic_block *bbs = get_loop_body (loop); 548 549 for (unsigned int i = 0; i < loop->num_nodes; i++) 550 { 551 basic_block bb = bbs[i]; 552 553 for (gphi_iterator bsi = gsi_start_phis (bb); !gsi_end_p (bsi); 554 gsi_next (&bsi)) 555 { 556 gphi *phi = bsi.phi (); 557 tree res = gimple_phi_result (phi); 558 bool virtual_p = virtual_operand_p (res); 559 if ((virtual_p && do_virtuals) 560 || (!virtual_p && do_nonvirtuals)) 561 find_uses_to_rename_def (res, use_blocks, need_phis); 562 } 563 564 for (gimple_stmt_iterator bsi = gsi_start_bb (bb); !gsi_end_p (bsi); 565 gsi_next (&bsi)) 566 { 567 gimple *stmt = gsi_stmt (bsi); 568 /* FOR_EACH_SSA_TREE_OPERAND iterator does not allows 569 SSA_OP_VIRTUAL_DEFS only. */ 570 if (def_flags == SSA_OP_VIRTUAL_DEFS) 571 { 572 tree vdef = gimple_vdef (stmt); 573 if (vdef != NULL) 574 find_uses_to_rename_def (vdef, use_blocks, need_phis); 575 } 576 else 577 { 578 tree var; 579 ssa_op_iter iter; 580 FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, def_flags) 581 find_uses_to_rename_def (var, use_blocks, need_phis); 582 } 583 } 584 } 585 586 XDELETEVEC (bbs); 587} 588 589/* Rewrites the program into a loop closed ssa form -- i.e. inserts extra 590 phi nodes to ensure that no variable is used outside the loop it is 591 defined in. 592 593 This strengthening of the basic ssa form has several advantages: 594 595 1) Updating it during unrolling/peeling/versioning is trivial, since 596 we do not need to care about the uses outside of the loop. 597 The same applies to virtual operands which are also rewritten into 598 loop closed SSA form. Note that virtual operands are always live 599 until function exit. 600 2) The behavior of all uses of an induction variable is the same. 601 Without this, you need to distinguish the case when the variable 602 is used outside of the loop it is defined in, for example 603 604 for (i = 0; i < 100; i++) 605 { 606 for (j = 0; j < 100; j++) 607 { 608 k = i + j; 609 use1 (k); 610 } 611 use2 (k); 612 } 613 614 Looking from the outer loop with the normal SSA form, the first use of k 615 is not well-behaved, while the second one is an induction variable with 616 base 99 and step 1. 617 618 If LOOP is non-null, only rewrite uses that have defs in LOOP. Otherwise, 619 if CHANGED_BBS is not NULL, we look for uses outside loops only in the 620 basic blocks in this set. 621 622 USE_FLAGS allows us to specify whether we want virtual, non-virtual or 623 both variables rewritten. 624 625 UPDATE_FLAG is used in the call to update_ssa. See 626 TODO_update_ssa* for documentation. */ 627 628void 629rewrite_into_loop_closed_ssa_1 (bitmap changed_bbs, unsigned update_flag, 630 int use_flags, class loop *loop) 631{ 632 bitmap *use_blocks; 633 bitmap names_to_rename; 634 635 loops_state_set (LOOP_CLOSED_SSA); 636 if (number_of_loops (cfun) <= 1) 637 return; 638 639 /* If the pass has caused the SSA form to be out-of-date, update it 640 now. */ 641 if (update_flag != 0) 642 update_ssa (update_flag); 643 else if (flag_checking) 644 verify_ssa (true, true); 645 646 bitmap_obstack_initialize (&loop_renamer_obstack); 647 648 names_to_rename = BITMAP_ALLOC (&loop_renamer_obstack); 649 650 /* Uses of names to rename. We don't have to initialize this array, 651 because we know that we will only have entries for the SSA names 652 in NAMES_TO_RENAME. */ 653 use_blocks = XNEWVEC (bitmap, num_ssa_names); 654 655 if (loop != NULL) 656 { 657 gcc_assert (changed_bbs == NULL); 658 find_uses_to_rename_in_loop (loop, use_blocks, names_to_rename, 659 use_flags); 660 } 661 else 662 { 663 gcc_assert (loop == NULL); 664 find_uses_to_rename (changed_bbs, use_blocks, names_to_rename, use_flags); 665 } 666 667 if (!bitmap_empty_p (names_to_rename)) 668 { 669 /* An array of bitmaps where LOOP_EXITS[I] is the set of basic blocks 670 that are the destination of an edge exiting loop number I. */ 671 bitmap *loop_exits = XNEWVEC (bitmap, number_of_loops (cfun)); 672 get_loops_exits (loop_exits); 673 674 /* Add the PHI nodes on exits of the loops for the names we need to 675 rewrite. */ 676 add_exit_phis (names_to_rename, use_blocks, loop_exits); 677 678 free (loop_exits); 679 680 /* Fix up all the names found to be used outside their original 681 loops. */ 682 update_ssa (TODO_update_ssa); 683 } 684 685 bitmap_obstack_release (&loop_renamer_obstack); 686 free (use_blocks); 687} 688 689/* Rewrites the non-virtual defs and uses into a loop closed ssa form. If 690 CHANGED_BBS is not NULL, we look for uses outside loops only in the basic 691 blocks in this set. UPDATE_FLAG is used in the call to update_ssa. See 692 TODO_update_ssa* for documentation. */ 693 694void 695rewrite_into_loop_closed_ssa (bitmap changed_bbs, unsigned update_flag) 696{ 697 rewrite_into_loop_closed_ssa_1 (changed_bbs, update_flag, SSA_OP_USE, NULL); 698} 699 700/* Rewrites virtual defs and uses with def in LOOP into loop closed ssa 701 form. */ 702 703void 704rewrite_virtuals_into_loop_closed_ssa (class loop *loop) 705{ 706 rewrite_into_loop_closed_ssa_1 (NULL, 0, SSA_OP_VIRTUAL_USES, loop); 707} 708 709/* Check invariants of the loop closed ssa form for the def in DEF_BB. */ 710 711static void 712check_loop_closed_ssa_def (basic_block def_bb, tree def) 713{ 714 use_operand_p use_p; 715 imm_use_iterator iterator; 716 FOR_EACH_IMM_USE_FAST (use_p, iterator, def) 717 { 718 if (is_gimple_debug (USE_STMT (use_p))) 719 continue; 720 721 basic_block use_bb = gimple_bb (USE_STMT (use_p)); 722 if (is_a <gphi *> (USE_STMT (use_p))) 723 use_bb = EDGE_PRED (use_bb, PHI_ARG_INDEX_FROM_USE (use_p))->src; 724 725 gcc_assert (flow_bb_inside_loop_p (def_bb->loop_father, use_bb)); 726 } 727} 728 729/* Checks invariants of loop closed ssa form in BB. */ 730 731static void 732check_loop_closed_ssa_bb (basic_block bb) 733{ 734 for (gphi_iterator bsi = gsi_start_phis (bb); !gsi_end_p (bsi); 735 gsi_next (&bsi)) 736 { 737 gphi *phi = bsi.phi (); 738 739 if (!virtual_operand_p (PHI_RESULT (phi))) 740 check_loop_closed_ssa_def (bb, PHI_RESULT (phi)); 741 } 742 743 for (gimple_stmt_iterator bsi = gsi_start_nondebug_bb (bb); !gsi_end_p (bsi); 744 gsi_next_nondebug (&bsi)) 745 { 746 ssa_op_iter iter; 747 tree var; 748 gimple *stmt = gsi_stmt (bsi); 749 750 FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_DEF) 751 check_loop_closed_ssa_def (bb, var); 752 } 753} 754 755/* Checks that invariants of the loop closed ssa form are preserved. 756 Call verify_ssa when VERIFY_SSA_P is true. Note all loops are checked 757 if LOOP is NULL, otherwise, only LOOP is checked. */ 758 759DEBUG_FUNCTION void 760verify_loop_closed_ssa (bool verify_ssa_p, class loop *loop) 761{ 762 if (number_of_loops (cfun) <= 1) 763 return; 764 765 if (verify_ssa_p) 766 verify_ssa (false, true); 767 768 timevar_push (TV_VERIFY_LOOP_CLOSED); 769 770 if (loop == NULL) 771 { 772 basic_block bb; 773 774 FOR_EACH_BB_FN (bb, cfun) 775 if (bb->loop_father && bb->loop_father->num > 0) 776 check_loop_closed_ssa_bb (bb); 777 } 778 else 779 { 780 basic_block *bbs = get_loop_body (loop); 781 782 for (unsigned i = 0; i < loop->num_nodes; ++i) 783 check_loop_closed_ssa_bb (bbs[i]); 784 785 free (bbs); 786 } 787 788 timevar_pop (TV_VERIFY_LOOP_CLOSED); 789} 790 791/* Split loop exit edge EXIT. The things are a bit complicated by a need to 792 preserve the loop closed ssa form. If COPY_CONSTANTS_P is true then 793 forwarder PHIs are also created for constant arguments. 794 The newly created block is returned. */ 795 796basic_block 797split_loop_exit_edge (edge exit, bool copy_constants_p) 798{ 799 basic_block dest = exit->dest; 800 basic_block bb = split_edge (exit); 801 gphi *phi, *new_phi; 802 tree new_name, name; 803 use_operand_p op_p; 804 gphi_iterator psi; 805 location_t locus; 806 807 for (psi = gsi_start_phis (dest); !gsi_end_p (psi); gsi_next (&psi)) 808 { 809 phi = psi.phi (); 810 op_p = PHI_ARG_DEF_PTR_FROM_EDGE (phi, single_succ_edge (bb)); 811 locus = gimple_phi_arg_location_from_edge (phi, single_succ_edge (bb)); 812 813 name = USE_FROM_PTR (op_p); 814 815 /* If the argument of the PHI node is a constant, we do not need 816 to keep it inside loop. */ 817 if (TREE_CODE (name) != SSA_NAME 818 && !copy_constants_p) 819 continue; 820 821 /* Otherwise create an auxiliary phi node that will copy the value 822 of the SSA name out of the loop. */ 823 new_name = duplicate_ssa_name (PHI_RESULT (phi), NULL); 824 new_phi = create_phi_node (new_name, bb); 825 add_phi_arg (new_phi, name, exit, locus); 826 SET_USE (op_p, new_name); 827 } 828 829 return bb; 830} 831 832/* Returns the basic block in that statements should be emitted for induction 833 variables incremented at the end of the LOOP. */ 834 835basic_block 836ip_end_pos (class loop *loop) 837{ 838 return loop->latch; 839} 840 841/* Returns the basic block in that statements should be emitted for induction 842 variables incremented just before exit condition of a LOOP. */ 843 844basic_block 845ip_normal_pos (class loop *loop) 846{ 847 gimple *last; 848 basic_block bb; 849 edge exit; 850 851 if (!single_pred_p (loop->latch)) 852 return NULL; 853 854 bb = single_pred (loop->latch); 855 last = last_stmt (bb); 856 if (!last 857 || gimple_code (last) != GIMPLE_COND) 858 return NULL; 859 860 exit = EDGE_SUCC (bb, 0); 861 if (exit->dest == loop->latch) 862 exit = EDGE_SUCC (bb, 1); 863 864 if (flow_bb_inside_loop_p (loop, exit->dest)) 865 return NULL; 866 867 return bb; 868} 869 870/* Stores the standard position for induction variable increment in LOOP 871 (just before the exit condition if it is available and latch block is empty, 872 end of the latch block otherwise) to BSI. INSERT_AFTER is set to true if 873 the increment should be inserted after *BSI. */ 874 875void 876standard_iv_increment_position (class loop *loop, gimple_stmt_iterator *bsi, 877 bool *insert_after) 878{ 879 basic_block bb = ip_normal_pos (loop), latch = ip_end_pos (loop); 880 gimple *last = last_stmt (latch); 881 882 if (!bb 883 || (last && gimple_code (last) != GIMPLE_LABEL)) 884 { 885 *bsi = gsi_last_bb (latch); 886 *insert_after = true; 887 } 888 else 889 { 890 *bsi = gsi_last_bb (bb); 891 *insert_after = false; 892 } 893} 894 895/* Copies phi node arguments for duplicated blocks. The index of the first 896 duplicated block is FIRST_NEW_BLOCK. */ 897 898static void 899copy_phi_node_args (unsigned first_new_block) 900{ 901 unsigned i; 902 903 for (i = first_new_block; i < (unsigned) last_basic_block_for_fn (cfun); i++) 904 BASIC_BLOCK_FOR_FN (cfun, i)->flags |= BB_DUPLICATED; 905 906 for (i = first_new_block; i < (unsigned) last_basic_block_for_fn (cfun); i++) 907 add_phi_args_after_copy_bb (BASIC_BLOCK_FOR_FN (cfun, i)); 908 909 for (i = first_new_block; i < (unsigned) last_basic_block_for_fn (cfun); i++) 910 BASIC_BLOCK_FOR_FN (cfun, i)->flags &= ~BB_DUPLICATED; 911} 912 913 914/* The same as cfgloopmanip.cc:duplicate_loop_body_to_header_edge, but also 915 updates the PHI nodes at start of the copied region. In order to 916 achieve this, only loops whose exits all lead to the same location 917 are handled. 918 919 Notice that we do not completely update the SSA web after 920 duplication. The caller is responsible for calling update_ssa 921 after the loop has been duplicated. */ 922 923bool 924gimple_duplicate_loop_body_to_header_edge (class loop *loop, edge e, 925 unsigned int ndupl, 926 sbitmap wont_exit, edge orig, 927 vec<edge> *to_remove, int flags) 928{ 929 unsigned first_new_block; 930 931 if (!loops_state_satisfies_p (LOOPS_HAVE_SIMPLE_LATCHES)) 932 return false; 933 if (!loops_state_satisfies_p (LOOPS_HAVE_PREHEADERS)) 934 return false; 935 936 first_new_block = last_basic_block_for_fn (cfun); 937 if (!duplicate_loop_body_to_header_edge (loop, e, ndupl, wont_exit, orig, 938 to_remove, flags)) 939 return false; 940 941 /* Readd the removed phi args for e. */ 942 flush_pending_stmts (e); 943 944 /* Copy the phi node arguments. */ 945 copy_phi_node_args (first_new_block); 946 947 scev_reset (); 948 949 return true; 950} 951 952/* Returns true if we can unroll LOOP FACTOR times. Number 953 of iterations of the loop is returned in NITER. */ 954 955bool 956can_unroll_loop_p (class loop *loop, unsigned factor, 957 class tree_niter_desc *niter) 958{ 959 edge exit; 960 961 /* Check whether unrolling is possible. We only want to unroll loops 962 for that we are able to determine number of iterations. We also 963 want to split the extra iterations of the loop from its end, 964 therefore we require that the loop has precisely one 965 exit. */ 966 967 exit = single_dom_exit (loop); 968 if (!exit) 969 return false; 970 971 if (!number_of_iterations_exit (loop, exit, niter, false) 972 || niter->cmp == ERROR_MARK 973 /* Scalar evolutions analysis might have copy propagated 974 the abnormal ssa names into these expressions, hence 975 emitting the computations based on them during loop 976 unrolling might create overlapping life ranges for 977 them, and failures in out-of-ssa. */ 978 || contains_abnormal_ssa_name_p (niter->may_be_zero) 979 || contains_abnormal_ssa_name_p (niter->control.base) 980 || contains_abnormal_ssa_name_p (niter->control.step) 981 || contains_abnormal_ssa_name_p (niter->bound)) 982 return false; 983 984 /* And of course, we must be able to duplicate the loop. */ 985 if (!can_duplicate_loop_p (loop)) 986 return false; 987 988 /* The final loop should be small enough. */ 989 if (tree_num_loop_insns (loop, &eni_size_weights) * factor 990 > (unsigned) param_max_unrolled_insns) 991 return false; 992 993 return true; 994} 995 996/* Determines the conditions that control execution of LOOP unrolled FACTOR 997 times. DESC is number of iterations of LOOP. ENTER_COND is set to 998 condition that must be true if the main loop can be entered. 999 If the loop does not always iterate an exact multiple of FACTOR times, 1000 EXIT_BASE, EXIT_STEP, EXIT_CMP and EXIT_BOUND are set to values describing 1001 how the exit from the unrolled loop should be controlled. Otherwise, 1002 the trees are set to null and EXIT_CMP is set to ERROR_MARK. */ 1003 1004static void 1005determine_exit_conditions (class loop *loop, class tree_niter_desc *desc, 1006 unsigned factor, tree *enter_cond, 1007 tree *exit_base, tree *exit_step, 1008 enum tree_code *exit_cmp, tree *exit_bound) 1009{ 1010 gimple_seq stmts; 1011 tree base = desc->control.base; 1012 tree step = desc->control.step; 1013 tree bound = desc->bound; 1014 tree type = TREE_TYPE (step); 1015 tree bigstep, delta; 1016 tree min = lower_bound_in_type (type, type); 1017 tree max = upper_bound_in_type (type, type); 1018 enum tree_code cmp = desc->cmp; 1019 tree cond = boolean_true_node, assum; 1020 1021 /* For pointers, do the arithmetics in the type of step. */ 1022 base = fold_convert (type, base); 1023 bound = fold_convert (type, bound); 1024 1025 *enter_cond = boolean_false_node; 1026 *exit_base = NULL_TREE; 1027 *exit_step = NULL_TREE; 1028 *exit_cmp = ERROR_MARK; 1029 *exit_bound = NULL_TREE; 1030 gcc_assert (cmp != ERROR_MARK); 1031 1032 /* We only need to be correct when we answer question 1033 "Do at least FACTOR more iterations remain?" in the unrolled loop. 1034 Thus, transforming BASE + STEP * i <> BOUND to 1035 BASE + STEP * i < BOUND is ok. */ 1036 if (cmp == NE_EXPR) 1037 { 1038 if (tree_int_cst_sign_bit (step)) 1039 cmp = GT_EXPR; 1040 else 1041 cmp = LT_EXPR; 1042 } 1043 else if (cmp == LT_EXPR) 1044 { 1045 gcc_assert (!tree_int_cst_sign_bit (step)); 1046 } 1047 else if (cmp == GT_EXPR) 1048 { 1049 gcc_assert (tree_int_cst_sign_bit (step)); 1050 } 1051 else 1052 gcc_unreachable (); 1053 1054 /* The main body of the loop may be entered iff: 1055 1056 1) desc->may_be_zero is false. 1057 2) it is possible to check that there are at least FACTOR iterations 1058 of the loop, i.e., BOUND - step * FACTOR does not overflow. 1059 3) # of iterations is at least FACTOR */ 1060 1061 if (!integer_zerop (desc->may_be_zero)) 1062 cond = fold_build2 (TRUTH_AND_EXPR, boolean_type_node, 1063 invert_truthvalue (desc->may_be_zero), 1064 cond); 1065 1066 bigstep = fold_build2 (MULT_EXPR, type, step, 1067 build_int_cst_type (type, factor)); 1068 delta = fold_build2 (MINUS_EXPR, type, bigstep, step); 1069 if (cmp == LT_EXPR) 1070 assum = fold_build2 (GE_EXPR, boolean_type_node, 1071 bound, 1072 fold_build2 (PLUS_EXPR, type, min, delta)); 1073 else 1074 assum = fold_build2 (LE_EXPR, boolean_type_node, 1075 bound, 1076 fold_build2 (PLUS_EXPR, type, max, delta)); 1077 cond = fold_build2 (TRUTH_AND_EXPR, boolean_type_node, assum, cond); 1078 1079 bound = fold_build2 (MINUS_EXPR, type, bound, delta); 1080 assum = fold_build2 (cmp, boolean_type_node, base, bound); 1081 cond = fold_build2 (TRUTH_AND_EXPR, boolean_type_node, assum, cond); 1082 1083 if (integer_nonzerop (cond) 1084 && integer_zerop (desc->may_be_zero)) 1085 { 1086 /* Convert the latch count to an iteration count. */ 1087 tree niter = fold_build2 (PLUS_EXPR, type, desc->niter, 1088 build_one_cst (type)); 1089 if (multiple_of_p (type, niter, bigstep)) 1090 return; 1091 } 1092 1093 cond = force_gimple_operand (unshare_expr (cond), &stmts, false, NULL_TREE); 1094 if (stmts) 1095 gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts); 1096 /* cond now may be a gimple comparison, which would be OK, but also any 1097 other gimple rhs (say a && b). In this case we need to force it to 1098 operand. */ 1099 if (!is_gimple_condexpr (cond)) 1100 { 1101 cond = force_gimple_operand (cond, &stmts, true, NULL_TREE); 1102 if (stmts) 1103 gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts); 1104 } 1105 *enter_cond = cond; 1106 1107 base = force_gimple_operand (unshare_expr (base), &stmts, true, NULL_TREE); 1108 if (stmts) 1109 gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts); 1110 bound = force_gimple_operand (unshare_expr (bound), &stmts, true, NULL_TREE); 1111 if (stmts) 1112 gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts); 1113 1114 *exit_base = base; 1115 *exit_step = bigstep; 1116 *exit_cmp = cmp; 1117 *exit_bound = bound; 1118} 1119 1120/* Scales the frequencies of all basic blocks in LOOP that are strictly 1121 dominated by BB by NUM/DEN. */ 1122 1123static void 1124scale_dominated_blocks_in_loop (class loop *loop, basic_block bb, 1125 profile_count num, profile_count den) 1126{ 1127 basic_block son; 1128 1129 if (!den.nonzero_p () && !(num == profile_count::zero ())) 1130 return; 1131 1132 for (son = first_dom_son (CDI_DOMINATORS, bb); 1133 son; 1134 son = next_dom_son (CDI_DOMINATORS, son)) 1135 { 1136 if (!flow_bb_inside_loop_p (loop, son)) 1137 continue; 1138 scale_bbs_frequencies_profile_count (&son, 1, num, den); 1139 scale_dominated_blocks_in_loop (loop, son, num, den); 1140 } 1141} 1142 1143/* Return estimated niter for LOOP after unrolling by FACTOR times. */ 1144 1145gcov_type 1146niter_for_unrolled_loop (class loop *loop, unsigned factor) 1147{ 1148 gcc_assert (factor != 0); 1149 bool profile_p = false; 1150 gcov_type est_niter = expected_loop_iterations_unbounded (loop, &profile_p); 1151 /* Note that this is really CEIL (est_niter + 1, factor) - 1, where the 1152 "+ 1" converts latch iterations to loop iterations and the "- 1" 1153 converts back. */ 1154 gcov_type new_est_niter = est_niter / factor; 1155 1156 if (est_niter == -1) 1157 return -1; 1158 1159 /* Without profile feedback, loops for which we do not know a better estimate 1160 are assumed to roll 10 times. When we unroll such loop, it appears to 1161 roll too little, and it may even seem to be cold. To avoid this, we 1162 ensure that the created loop appears to roll at least 5 times (but at 1163 most as many times as before unrolling). Don't do adjustment if profile 1164 feedback is present. */ 1165 if (new_est_niter < 5 && !profile_p) 1166 { 1167 if (est_niter < 5) 1168 new_est_niter = est_niter; 1169 else 1170 new_est_niter = 5; 1171 } 1172 1173 if (loop->any_upper_bound) 1174 { 1175 /* As above, this is really CEIL (upper_bound + 1, factor) - 1. */ 1176 widest_int bound = wi::udiv_floor (loop->nb_iterations_upper_bound, 1177 factor); 1178 if (wi::ltu_p (bound, new_est_niter)) 1179 new_est_niter = bound.to_uhwi (); 1180 } 1181 1182 return new_est_niter; 1183} 1184 1185/* Unroll LOOP FACTOR times. LOOP is known to have a single exit edge 1186 whose source block dominates the latch. DESC describes the number of 1187 iterations of LOOP. 1188 1189 If N is number of iterations of the loop and MAY_BE_ZERO is the condition 1190 under that loop exits in the first iteration even if N != 0, 1191 1192 while (1) 1193 { 1194 x = phi (init, next); 1195 1196 pre; 1197 if (st) 1198 break; 1199 post; 1200 } 1201 1202 becomes (with possibly the exit conditions formulated a bit differently, 1203 avoiding the need to create a new iv): 1204 1205 if (MAY_BE_ZERO || N < FACTOR) 1206 goto rest; 1207 1208 do 1209 { 1210 x = phi (init, next); 1211 1212 pre; 1213 post; 1214 pre; 1215 post; 1216 ... 1217 pre; 1218 post; 1219 N -= FACTOR; 1220 1221 } while (N >= FACTOR); 1222 1223 rest: 1224 init' = phi (init, x); 1225 1226 while (1) 1227 { 1228 x = phi (init', next); 1229 1230 pre; 1231 if (st) 1232 break; 1233 post; 1234 } 1235 1236 Before the loop is unrolled, TRANSFORM is called for it (only for the 1237 unrolled loop, but not for its versioned copy). DATA is passed to 1238 TRANSFORM. */ 1239 1240/* Probability in % that the unrolled loop is entered. Just a guess. */ 1241#define PROB_UNROLLED_LOOP_ENTERED 90 1242 1243void 1244tree_transform_and_unroll_loop (class loop *loop, unsigned factor, 1245 class tree_niter_desc *desc, 1246 transform_callback transform, 1247 void *data) 1248{ 1249 gcov_type new_est_niter = niter_for_unrolled_loop (loop, factor); 1250 unsigned irr = loop_preheader_edge (loop)->flags & EDGE_IRREDUCIBLE_LOOP; 1251 1252 enum tree_code exit_cmp; 1253 tree enter_main_cond, exit_base, exit_step, exit_bound; 1254 determine_exit_conditions (loop, desc, factor, 1255 &enter_main_cond, &exit_base, &exit_step, 1256 &exit_cmp, &exit_bound); 1257 bool single_loop_p = !exit_base; 1258 1259 /* Let us assume that the unrolled loop is quite likely to be entered. */ 1260 profile_probability prob_entry; 1261 if (integer_nonzerop (enter_main_cond)) 1262 prob_entry = profile_probability::always (); 1263 else 1264 prob_entry = profile_probability::guessed_always () 1265 .apply_scale (PROB_UNROLLED_LOOP_ENTERED, 100); 1266 1267 gcond *exit_if = nullptr; 1268 class loop *new_loop = nullptr; 1269 edge new_exit; 1270 if (!single_loop_p) 1271 { 1272 edge exit = single_dom_exit (loop); 1273 1274 /* The values for scales should keep profile consistent, and somewhat 1275 close to correct. 1276 1277 TODO: The current value of SCALE_REST makes it appear that the loop 1278 that is created by splitting the remaining iterations of the unrolled 1279 loop is executed the same number of times as the original loop, and 1280 with the same frequencies, which is obviously wrong. This does not 1281 appear to cause problems, so we do not bother with fixing it for now. 1282 To make the profile correct, we would need to change the probability 1283 of the exit edge of the loop, and recompute the distribution of 1284 frequencies in its body because of this change (scale the frequencies 1285 of blocks before and after the exit by appropriate factors). */ 1286 profile_probability scale_unrolled = prob_entry; 1287 new_loop = loop_version (loop, enter_main_cond, NULL, prob_entry, 1288 prob_entry.invert (), scale_unrolled, 1289 profile_probability::guessed_always (), 1290 true); 1291 gcc_assert (new_loop != NULL); 1292 update_ssa (TODO_update_ssa); 1293 1294 /* Prepare the cfg and update the phi nodes. Move the loop exit to the 1295 loop latch (and make its condition dummy, for the moment). */ 1296 basic_block rest = loop_preheader_edge (new_loop)->src; 1297 edge precond_edge = single_pred_edge (rest); 1298 split_edge (loop_latch_edge (loop)); 1299 basic_block exit_bb = single_pred (loop->latch); 1300 1301 /* Since the exit edge will be removed, the frequency of all the blocks 1302 in the loop that are dominated by it must be scaled by 1303 1 / (1 - exit->probability). */ 1304 if (exit->probability.initialized_p ()) 1305 scale_dominated_blocks_in_loop (loop, exit->src, 1306 /* We are scaling up here so 1307 probability does not fit. */ 1308 loop->header->count, 1309 loop->header->count 1310 - loop->header->count.apply_probability 1311 (exit->probability)); 1312 1313 gimple_stmt_iterator bsi = gsi_last_bb (exit_bb); 1314 exit_if = gimple_build_cond (EQ_EXPR, integer_zero_node, 1315 integer_zero_node, 1316 NULL_TREE, NULL_TREE); 1317 1318 gsi_insert_after (&bsi, exit_if, GSI_NEW_STMT); 1319 new_exit = make_edge (exit_bb, rest, EDGE_FALSE_VALUE | irr); 1320 rescan_loop_exit (new_exit, true, false); 1321 1322 /* Set the probability of new exit to the same of the old one. Fix 1323 the frequency of the latch block, by scaling it back by 1324 1 - exit->probability. */ 1325 new_exit->probability = exit->probability; 1326 edge new_nonexit = single_pred_edge (loop->latch); 1327 new_nonexit->probability = exit->probability.invert (); 1328 new_nonexit->flags = EDGE_TRUE_VALUE; 1329 if (new_nonexit->probability.initialized_p ()) 1330 scale_bbs_frequencies (&loop->latch, 1, new_nonexit->probability); 1331 1332 edge old_entry = loop_preheader_edge (loop); 1333 edge new_entry = loop_preheader_edge (new_loop); 1334 edge old_latch = loop_latch_edge (loop); 1335 for (gphi_iterator psi_old_loop = gsi_start_phis (loop->header), 1336 psi_new_loop = gsi_start_phis (new_loop->header); 1337 !gsi_end_p (psi_old_loop); 1338 gsi_next (&psi_old_loop), gsi_next (&psi_new_loop)) 1339 { 1340 gphi *phi_old_loop = psi_old_loop.phi (); 1341 gphi *phi_new_loop = psi_new_loop.phi (); 1342 1343 tree init = PHI_ARG_DEF_FROM_EDGE (phi_old_loop, old_entry); 1344 use_operand_p op 1345 = PHI_ARG_DEF_PTR_FROM_EDGE (phi_new_loop, new_entry); 1346 gcc_assert (operand_equal_for_phi_arg_p (init, USE_FROM_PTR (op))); 1347 tree next = PHI_ARG_DEF_FROM_EDGE (phi_old_loop, old_latch); 1348 1349 /* Prefer using original variable as a base for the new ssa name. 1350 This is necessary for virtual ops, and useful in order to avoid 1351 losing debug info for real ops. */ 1352 tree new_init; 1353 if (TREE_CODE (next) == SSA_NAME 1354 && useless_type_conversion_p (TREE_TYPE (next), 1355 TREE_TYPE (init))) 1356 new_init = copy_ssa_name (next); 1357 else if (TREE_CODE (init) == SSA_NAME 1358 && useless_type_conversion_p (TREE_TYPE (init), 1359 TREE_TYPE (next))) 1360 new_init = copy_ssa_name (init); 1361 else if (useless_type_conversion_p (TREE_TYPE (next), 1362 TREE_TYPE (init))) 1363 new_init = make_temp_ssa_name (TREE_TYPE (next), NULL, 1364 "unrinittmp"); 1365 else 1366 new_init = make_temp_ssa_name (TREE_TYPE (init), NULL, 1367 "unrinittmp"); 1368 1369 gphi *phi_rest = create_phi_node (new_init, rest); 1370 add_phi_arg (phi_rest, init, precond_edge, UNKNOWN_LOCATION); 1371 add_phi_arg (phi_rest, next, new_exit, UNKNOWN_LOCATION); 1372 SET_USE (op, new_init); 1373 } 1374 1375 remove_path (exit); 1376 } 1377 else 1378 new_exit = single_dom_exit (loop); 1379 1380 /* Transform the loop. */ 1381 if (transform) 1382 (*transform) (loop, data); 1383 1384 /* Unroll the loop and remove the exits in all iterations except for the 1385 last one. */ 1386 auto_sbitmap wont_exit (factor); 1387 bitmap_ones (wont_exit); 1388 bitmap_clear_bit (wont_exit, factor - 1); 1389 1390 auto_vec<edge> to_remove; 1391 bool ok 1392 = gimple_duplicate_loop_body_to_header_edge (loop, loop_latch_edge (loop), 1393 factor - 1, wont_exit, 1394 new_exit, &to_remove, 1395 DLTHE_FLAG_UPDATE_FREQ); 1396 gcc_assert (ok); 1397 1398 for (edge e : to_remove) 1399 { 1400 ok = remove_path (e); 1401 gcc_assert (ok); 1402 } 1403 update_ssa (TODO_update_ssa); 1404 1405 new_exit = single_dom_exit (loop); 1406 if (!single_loop_p) 1407 { 1408 /* Ensure that the frequencies in the loop match the new estimated 1409 number of iterations, and change the probability of the new 1410 exit edge. */ 1411 1412 profile_count freq_h = loop->header->count; 1413 profile_count freq_e = (loop_preheader_edge (loop))->count (); 1414 if (freq_h.nonzero_p ()) 1415 { 1416 /* Avoid dropping loop body profile counter to 0 because of zero 1417 count in loop's preheader. */ 1418 if (freq_h.nonzero_p () && !(freq_e == profile_count::zero ())) 1419 freq_e = freq_e.force_nonzero (); 1420 scale_loop_frequencies (loop, freq_e.probability_in (freq_h)); 1421 } 1422 1423 basic_block rest = new_exit->dest; 1424 new_exit->probability = profile_probability::always () 1425 .apply_scale (1, new_est_niter + 1); 1426 1427 rest->count += new_exit->count (); 1428 1429 edge new_nonexit = single_pred_edge (loop->latch); 1430 profile_probability prob = new_nonexit->probability; 1431 new_nonexit->probability = new_exit->probability.invert (); 1432 prob = new_nonexit->probability / prob; 1433 if (prob.initialized_p ()) 1434 scale_bbs_frequencies (&loop->latch, 1, prob); 1435 1436 /* Finally create the new counter for number of iterations and add 1437 the new exit instruction. */ 1438 tree ctr_before, ctr_after; 1439 gimple_stmt_iterator bsi = gsi_last_nondebug_bb (new_exit->src); 1440 exit_if = as_a <gcond *> (gsi_stmt (bsi)); 1441 create_iv (exit_base, exit_step, NULL_TREE, loop, 1442 &bsi, false, &ctr_before, &ctr_after); 1443 gimple_cond_set_code (exit_if, exit_cmp); 1444 gimple_cond_set_lhs (exit_if, ctr_after); 1445 gimple_cond_set_rhs (exit_if, exit_bound); 1446 update_stmt (exit_if); 1447 } 1448 else 1449 { 1450 /* gimple_duplicate_loop_to_header_edge has adjusted the loop body's 1451 original profile counts in line with the unroll factor. However, 1452 the old counts might not have been consistent with the old 1453 iteration count. 1454 1455 Therefore, if the iteration count is known exactly, make sure that the 1456 profile counts of the loop header (and any other blocks that might be 1457 executed in the final iteration) are consistent with the combination 1458 of (a) the incoming profile count and (b) the new iteration count. */ 1459 profile_count in_count = loop_preheader_edge (loop)->count (); 1460 profile_count old_header_count = loop->header->count; 1461 if (in_count.nonzero_p () 1462 && old_header_count.nonzero_p () 1463 && TREE_CODE (desc->niter) == INTEGER_CST) 1464 { 1465 /* The + 1 converts latch counts to iteration counts. */ 1466 profile_count new_header_count 1467 = (in_count.apply_scale (new_est_niter + 1, 1)); 1468 basic_block *body = get_loop_body (loop); 1469 scale_bbs_frequencies_profile_count (body, loop->num_nodes, 1470 new_header_count, 1471 old_header_count); 1472 free (body); 1473 } 1474 1475 /* gimple_duplicate_loop_to_header_edge discarded FACTOR - 1 1476 exit edges and adjusted the loop body's profile counts for the 1477 new probabilities of the remaining non-exit edges. However, 1478 the remaining exit edge still has the same probability as it 1479 did before, even though it is now more likely. 1480 1481 Therefore, all blocks executed after a failed exit test now have 1482 a profile count that is too high, and the sum of the profile counts 1483 for the header's incoming edges is greater than the profile count 1484 of the header itself. 1485 1486 Adjust the profile counts of all code in the loop body after 1487 the exit test so that the sum of the counts on entry to the 1488 header agree. */ 1489 profile_count old_latch_count = loop_latch_edge (loop)->count (); 1490 profile_count new_latch_count = loop->header->count - in_count; 1491 if (old_latch_count.nonzero_p () && new_latch_count.nonzero_p ()) 1492 scale_dominated_blocks_in_loop (loop, new_exit->src, new_latch_count, 1493 old_latch_count); 1494 1495 /* Set the probability of the exit edge based on NEW_EST_NITER 1496 (which estimates latch counts rather than iteration counts). 1497 Update the probabilities of other edges to match. 1498 1499 If the profile counts are large enough to give the required 1500 precision, the updates above will have made 1501 1502 e->dest->count / e->src->count ~= new e->probability 1503 1504 for every outgoing edge e of NEW_EXIT->src. */ 1505 profile_probability new_exit_prob = profile_probability::always () 1506 .apply_scale (1, new_est_niter + 1); 1507 change_edge_frequency (new_exit, new_exit_prob); 1508 } 1509 1510 checking_verify_flow_info (); 1511 checking_verify_loop_structure (); 1512 checking_verify_loop_closed_ssa (true, loop); 1513 checking_verify_loop_closed_ssa (true, new_loop); 1514} 1515 1516/* Wrapper over tree_transform_and_unroll_loop for case we do not 1517 want to transform the loop before unrolling. The meaning 1518 of the arguments is the same as for tree_transform_and_unroll_loop. */ 1519 1520void 1521tree_unroll_loop (class loop *loop, unsigned factor, 1522 class tree_niter_desc *desc) 1523{ 1524 tree_transform_and_unroll_loop (loop, factor, desc, NULL, NULL); 1525} 1526 1527/* Rewrite the phi node at position PSI in function of the main 1528 induction variable MAIN_IV and insert the generated code at GSI. */ 1529 1530static void 1531rewrite_phi_with_iv (loop_p loop, 1532 gphi_iterator *psi, 1533 gimple_stmt_iterator *gsi, 1534 tree main_iv) 1535{ 1536 affine_iv iv; 1537 gassign *stmt; 1538 gphi *phi = psi->phi (); 1539 tree atype, mtype, val, res = PHI_RESULT (phi); 1540 1541 if (virtual_operand_p (res) || res == main_iv) 1542 { 1543 gsi_next (psi); 1544 return; 1545 } 1546 1547 if (!simple_iv (loop, loop, res, &iv, true)) 1548 { 1549 gsi_next (psi); 1550 return; 1551 } 1552 1553 remove_phi_node (psi, false); 1554 1555 atype = TREE_TYPE (res); 1556 mtype = POINTER_TYPE_P (atype) ? sizetype : atype; 1557 val = fold_build2 (MULT_EXPR, mtype, unshare_expr (iv.step), 1558 fold_convert (mtype, main_iv)); 1559 val = fold_build2 (POINTER_TYPE_P (atype) 1560 ? POINTER_PLUS_EXPR : PLUS_EXPR, 1561 atype, unshare_expr (iv.base), val); 1562 val = force_gimple_operand_gsi (gsi, val, false, NULL_TREE, true, 1563 GSI_SAME_STMT); 1564 stmt = gimple_build_assign (res, val); 1565 gsi_insert_before (gsi, stmt, GSI_SAME_STMT); 1566} 1567 1568/* Rewrite all the phi nodes of LOOP in function of the main induction 1569 variable MAIN_IV. */ 1570 1571static void 1572rewrite_all_phi_nodes_with_iv (loop_p loop, tree main_iv) 1573{ 1574 unsigned i; 1575 basic_block *bbs = get_loop_body_in_dom_order (loop); 1576 gphi_iterator psi; 1577 1578 for (i = 0; i < loop->num_nodes; i++) 1579 { 1580 basic_block bb = bbs[i]; 1581 gimple_stmt_iterator gsi = gsi_after_labels (bb); 1582 1583 if (bb->loop_father != loop) 1584 continue; 1585 1586 for (psi = gsi_start_phis (bb); !gsi_end_p (psi); ) 1587 rewrite_phi_with_iv (loop, &psi, &gsi, main_iv); 1588 } 1589 1590 free (bbs); 1591} 1592 1593/* Bases all the induction variables in LOOP on a single induction variable 1594 (with base 0 and step 1), whose final value is compared with *NIT. When the 1595 IV type precision has to be larger than *NIT type precision, *NIT is 1596 converted to the larger type, the conversion code is inserted before the 1597 loop, and *NIT is updated to the new definition. When BUMP_IN_LATCH is true, 1598 the induction variable is incremented in the loop latch, otherwise it is 1599 incremented in the loop header. Return the induction variable that was 1600 created. */ 1601 1602tree 1603canonicalize_loop_ivs (class loop *loop, tree *nit, bool bump_in_latch) 1604{ 1605 unsigned precision = TYPE_PRECISION (TREE_TYPE (*nit)); 1606 unsigned original_precision = precision; 1607 tree type, var_before; 1608 gimple_stmt_iterator gsi; 1609 gphi_iterator psi; 1610 gcond *stmt; 1611 edge exit = single_dom_exit (loop); 1612 gimple_seq stmts; 1613 bool unsigned_p = false; 1614 1615 for (psi = gsi_start_phis (loop->header); 1616 !gsi_end_p (psi); gsi_next (&psi)) 1617 { 1618 gphi *phi = psi.phi (); 1619 tree res = PHI_RESULT (phi); 1620 bool uns; 1621 1622 type = TREE_TYPE (res); 1623 if (virtual_operand_p (res) 1624 || (!INTEGRAL_TYPE_P (type) 1625 && !POINTER_TYPE_P (type)) 1626 || TYPE_PRECISION (type) < precision) 1627 continue; 1628 1629 uns = POINTER_TYPE_P (type) | TYPE_UNSIGNED (type); 1630 1631 if (TYPE_PRECISION (type) > precision) 1632 unsigned_p = uns; 1633 else 1634 unsigned_p |= uns; 1635 1636 precision = TYPE_PRECISION (type); 1637 } 1638 1639 scalar_int_mode mode = smallest_int_mode_for_size (precision); 1640 precision = GET_MODE_PRECISION (mode); 1641 type = build_nonstandard_integer_type (precision, unsigned_p); 1642 1643 if (original_precision != precision 1644 || TYPE_UNSIGNED (TREE_TYPE (*nit)) != unsigned_p) 1645 { 1646 *nit = fold_convert (type, *nit); 1647 *nit = force_gimple_operand (*nit, &stmts, true, NULL_TREE); 1648 if (stmts) 1649 gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts); 1650 } 1651 1652 if (bump_in_latch) 1653 gsi = gsi_last_bb (loop->latch); 1654 else 1655 gsi = gsi_last_nondebug_bb (loop->header); 1656 create_iv (build_int_cst_type (type, 0), build_int_cst (type, 1), NULL_TREE, 1657 loop, &gsi, bump_in_latch, &var_before, NULL); 1658 1659 rewrite_all_phi_nodes_with_iv (loop, var_before); 1660 1661 stmt = as_a <gcond *> (last_stmt (exit->src)); 1662 /* Make the loop exit if the control condition is not satisfied. */ 1663 if (exit->flags & EDGE_TRUE_VALUE) 1664 { 1665 edge te, fe; 1666 1667 extract_true_false_edges_from_block (exit->src, &te, &fe); 1668 te->flags = EDGE_FALSE_VALUE; 1669 fe->flags = EDGE_TRUE_VALUE; 1670 } 1671 gimple_cond_set_code (stmt, LT_EXPR); 1672 gimple_cond_set_lhs (stmt, var_before); 1673 gimple_cond_set_rhs (stmt, *nit); 1674 update_stmt (stmt); 1675 1676 return var_before; 1677} 1678