1/* High-level loop manipulation functions.
2 Copyright (C) 2004-2023 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 If INCR_OP is PLUS_EXPR, the induction variable is BASE + STEP * iteration.
52 If INCR_OP is MINUS_EXPR, the induction variable is BASE - STEP * iteration.
53 It is expected that neither BASE nor STEP are shared with other expressions
54 (unless the sharing rules allow this). Use VAR as a base var_decl for it
55 (if NULL, a new temporary will be created). The increment will occur at
56 INCR_POS (after it if AFTER is true, before it otherwise). INCR_POS and
57 AFTER can be computed using standard_iv_increment_position. The ssa versions
58 of the variable before and after increment will be stored in VAR_BEFORE and
59 VAR_AFTER (unless they are NULL). */
60
61void
62create_iv (tree base, tree_code incr_op, tree step, tree var, class loop *loop,
63 gimple_stmt_iterator *incr_pos, bool after, tree *var_before,
64 tree *var_after)
65{
66 gassign *stmt;
67 gphi *phi;
68 tree initial, step1;
69 gimple_seq stmts;
70 tree vb, va;
71 gcc_assert (incr_op == PLUS_EXPR || incr_op == MINUS_EXPR);
72 edge pe = loop_preheader_edge (loop);
73
74 if (var != NULL_TREE)
75 {
76 vb = make_ssa_name (var);
77 va = make_ssa_name (var);
78 }
79 else
80 {
81 vb = make_temp_ssa_name (TREE_TYPE (base), NULL, name: "ivtmp");
82 va = make_temp_ssa_name (TREE_TYPE (base), NULL, name: "ivtmp");
83 }
84 if (var_before)
85 *var_before = vb;
86 if (var_after)
87 *var_after = va;
88
89 /* For easier readability of the created code, produce MINUS_EXPRs
90 when suitable. */
91 if (TREE_CODE (step) == INTEGER_CST)
92 {
93 if (TYPE_UNSIGNED (TREE_TYPE (step)))
94 {
95 step1 = fold_build1 (NEGATE_EXPR, TREE_TYPE (step), step);
96 if (tree_int_cst_lt (t1: step1, t2: step))
97 {
98 incr_op = (incr_op == PLUS_EXPR ? MINUS_EXPR : PLUS_EXPR);
99 step = step1;
100 }
101 }
102 else
103 {
104 bool ovf;
105
106 if (!tree_expr_nonnegative_warnv_p (step, &ovf)
107 && may_negate_without_overflow_p (step))
108 {
109 incr_op = (incr_op == PLUS_EXPR ? MINUS_EXPR : PLUS_EXPR);
110 step = fold_build1 (NEGATE_EXPR, TREE_TYPE (step), step);
111 }
112 }
113 }
114 if (POINTER_TYPE_P (TREE_TYPE (base)))
115 {
116 if (TREE_CODE (base) == ADDR_EXPR)
117 mark_addressable (TREE_OPERAND (base, 0));
118 step = convert_to_ptrofftype (step);
119 if (incr_op == MINUS_EXPR)
120 step = fold_build1 (NEGATE_EXPR, TREE_TYPE (step), step);
121 incr_op = POINTER_PLUS_EXPR;
122 }
123 /* Gimplify the step if necessary. We put the computations in front of the
124 loop (i.e. the step should be loop invariant). */
125 step = force_gimple_operand (step, &stmts, true, NULL_TREE);
126 if (stmts)
127 gsi_insert_seq_on_edge_immediate (pe, stmts);
128
129 stmt = gimple_build_assign (va, incr_op, vb, step);
130 /* Prevent the increment from inheriting a bogus location if it is not put
131 immediately after a statement whose location is known. */
132 if (after)
133 {
134 gimple_stmt_iterator gsi = *incr_pos;
135 if (!gsi_end_p (i: gsi))
136 gsi_next_nondebug (i: &gsi);
137 if (gsi_end_p (i: gsi))
138 {
139 edge e = single_succ_edge (bb: gsi_bb (i: *incr_pos));
140 gimple_set_location (g: stmt, location: e->goto_locus);
141 }
142 gsi_insert_after (incr_pos, stmt, GSI_NEW_STMT);
143 }
144 else
145 {
146 gimple_stmt_iterator gsi = *incr_pos;
147 if (!gsi_end_p (i: gsi) && is_gimple_debug (gs: gsi_stmt (i: gsi)))
148 gsi_next_nondebug (i: &gsi);
149 if (!gsi_end_p (i: gsi))
150 gimple_set_location (g: stmt, location: gimple_location (g: gsi_stmt (i: gsi)));
151 gsi_insert_before (incr_pos, stmt, GSI_NEW_STMT);
152 }
153
154 initial = force_gimple_operand (base, &stmts, true, var);
155 if (stmts)
156 gsi_insert_seq_on_edge_immediate (pe, stmts);
157
158 phi = create_phi_node (vb, loop->header);
159 add_phi_arg (phi, initial, loop_preheader_edge (loop), UNKNOWN_LOCATION);
160 add_phi_arg (phi, va, loop_latch_edge (loop), UNKNOWN_LOCATION);
161}
162
163/* Return the innermost superloop LOOP of USE_LOOP that is a superloop of
164 both DEF_LOOP and USE_LOOP. */
165
166static inline class loop *
167find_sibling_superloop (class loop *use_loop, class loop *def_loop)
168{
169 unsigned ud = loop_depth (loop: use_loop);
170 unsigned dd = loop_depth (loop: def_loop);
171 gcc_assert (ud > 0 && dd > 0);
172 if (ud > dd)
173 use_loop = superloop_at_depth (use_loop, dd);
174 if (ud < dd)
175 def_loop = superloop_at_depth (def_loop, ud);
176 while (loop_outer (loop: use_loop) != loop_outer (loop: def_loop))
177 {
178 use_loop = loop_outer (loop: use_loop);
179 def_loop = loop_outer (loop: def_loop);
180 gcc_assert (use_loop && def_loop);
181 }
182 return use_loop;
183}
184
185/* DEF_BB is a basic block containing a DEF that needs rewriting into
186 loop-closed SSA form. USE_BLOCKS is the set of basic blocks containing
187 uses of DEF that "escape" from the loop containing DEF_BB (i.e. blocks in
188 USE_BLOCKS are dominated by DEF_BB but not in the loop father of DEF_BB).
189 ALL_EXITS[I] is the set of all basic blocks that exit loop I.
190 DEF_LOOP_EXITS is a bitmap of loop exit blocks that exit the loop
191 containing DEF_BB or its outer loops.
192
193 Compute the subset of loop exit destinations that exit the loop
194 containing DEF_BB or one of its loop fathers, in which DEF is live.
195 This set is returned in the bitmap LIVE_EXITS.
196
197 Instead of computing the complete livein set of the def, we use the loop
198 nesting tree as a form of poor man's structure analysis. This greatly
199 speeds up the analysis, which is important because this function may be
200 called on all SSA names that need rewriting, one at a time. */
201
202static void
203compute_live_loop_exits (bitmap live_exits, bitmap use_blocks,
204 basic_block def_bb, bitmap def_loop_exits)
205{
206 unsigned i;
207 bitmap_iterator bi;
208 class loop *def_loop = def_bb->loop_father;
209 unsigned def_loop_depth = loop_depth (loop: def_loop);
210
211 /* Normally the work list size is bounded by the number of basic
212 blocks in the largest loop. We don't know this number, but we
213 can be fairly sure that it will be relatively small. */
214 auto_vec<basic_block, 8> worklist (MAX (8, n_basic_blocks_for_fn (cfun) / 128));
215
216 EXECUTE_IF_SET_IN_BITMAP (use_blocks, 0, i, bi)
217 {
218 basic_block use_bb = BASIC_BLOCK_FOR_FN (cfun, i);
219 class loop *use_loop = use_bb->loop_father;
220 gcc_checking_assert (def_loop != use_loop
221 && ! flow_loop_nested_p (def_loop, use_loop));
222 if (! flow_loop_nested_p (use_loop, def_loop))
223 use_bb = find_sibling_superloop (use_loop, def_loop)->header;
224 if (bitmap_set_bit (live_exits, use_bb->index))
225 worklist.safe_push (obj: use_bb);
226 }
227
228 /* Iterate until the worklist is empty. */
229 while (! worklist.is_empty ())
230 {
231 edge e;
232 edge_iterator ei;
233
234 /* Pull a block off the worklist. */
235 basic_block bb = worklist.pop ();
236
237 /* Make sure we have at least enough room in the work list
238 for all predecessors of this block. */
239 worklist.reserve (EDGE_COUNT (bb->preds));
240
241 /* For each predecessor block. */
242 FOR_EACH_EDGE (e, ei, bb->preds)
243 {
244 basic_block pred = e->src;
245 class loop *pred_loop = pred->loop_father;
246 unsigned pred_loop_depth = loop_depth (loop: pred_loop);
247 bool pred_visited;
248
249 /* We should have met DEF_BB along the way. */
250 gcc_assert (pred != ENTRY_BLOCK_PTR_FOR_FN (cfun));
251
252 if (pred_loop_depth >= def_loop_depth)
253 {
254 if (pred_loop_depth > def_loop_depth)
255 pred_loop = superloop_at_depth (pred_loop, def_loop_depth);
256 /* If we've reached DEF_LOOP, our train ends here. */
257 if (pred_loop == def_loop)
258 continue;
259 }
260 else if (! flow_loop_nested_p (pred_loop, def_loop))
261 pred = find_sibling_superloop (use_loop: pred_loop, def_loop)->header;
262
263 /* Add PRED to the LIVEIN set. PRED_VISITED is true if
264 we had already added PRED to LIVEIN before. */
265 pred_visited = !bitmap_set_bit (live_exits, pred->index);
266
267 /* If we have visited PRED before, don't add it to the worklist.
268 If BB dominates PRED, then we're probably looking at a loop.
269 We're only interested in looking up in the dominance tree
270 because DEF_BB dominates all the uses. */
271 if (pred_visited || dominated_by_p (CDI_DOMINATORS, pred, bb))
272 continue;
273
274 worklist.quick_push (obj: pred);
275 }
276 }
277
278 bitmap_and_into (live_exits, def_loop_exits);
279}
280
281/* Add a loop-closing PHI for VAR in basic block EXIT. */
282
283static void
284add_exit_phi (basic_block exit, tree var)
285{
286 gphi *phi;
287 edge e;
288 edge_iterator ei;
289
290 /* Check that at least one of the edges entering the EXIT block exits
291 the loop, or a superloop of that loop, that VAR is defined in. */
292 if (flag_checking)
293 {
294 gimple *def_stmt = SSA_NAME_DEF_STMT (var);
295 basic_block def_bb = gimple_bb (g: def_stmt);
296 FOR_EACH_EDGE (e, ei, exit->preds)
297 {
298 class loop *aloop = find_common_loop (def_bb->loop_father,
299 e->src->loop_father);
300 if (!flow_bb_inside_loop_p (aloop, e->dest))
301 break;
302 }
303 gcc_assert (e);
304 }
305
306 phi = create_phi_node (NULL_TREE, exit);
307 create_new_def_for (var, phi, gimple_phi_result_ptr (gs: phi));
308 FOR_EACH_EDGE (e, ei, exit->preds)
309 add_phi_arg (phi, var, e, UNKNOWN_LOCATION);
310
311 if (dump_file && (dump_flags & TDF_DETAILS))
312 {
313 fprintf (stream: dump_file, format: ";; Created LCSSA PHI: ");
314 print_gimple_stmt (dump_file, phi, 0, dump_flags);
315 }
316}
317
318/* Add exit phis for VAR that is used in LIVEIN.
319 Exits of the loops are stored in LOOP_EXITS. Returns the number
320 of PHIs added for VAR. */
321
322static unsigned
323add_exit_phis_var (tree var, bitmap use_blocks, bitmap def_loop_exits)
324{
325 unsigned index;
326 bitmap_iterator bi;
327 basic_block def_bb = gimple_bb (SSA_NAME_DEF_STMT (var));
328
329 gcc_checking_assert (! bitmap_bit_p (use_blocks, def_bb->index));
330
331 auto_bitmap live_exits (&loop_renamer_obstack);
332 compute_live_loop_exits (live_exits, use_blocks, def_bb, def_loop_exits);
333
334 unsigned cnt = 0;
335 EXECUTE_IF_SET_IN_BITMAP (live_exits, 0, index, bi)
336 {
337 add_exit_phi (BASIC_BLOCK_FOR_FN (cfun, index), var);
338 cnt++;
339 }
340 return cnt;
341}
342
343static int
344loop_name_cmp (const void *p1, const void *p2)
345{
346 auto l1 = (const std::pair<int, int> *)p1;
347 auto l2 = (const std::pair<int, int> *)p2;
348 if (l1->first < l2->first)
349 return -1;
350 else if (l1->first > l2->first)
351 return 1;
352 return 0;
353}
354
355/* Add exit phis for the names marked in NAMES_TO_RENAME.
356 Exits of the loops are stored in EXITS. Sets of blocks where the ssa
357 names are used are stored in USE_BLOCKS. Returns whether any name
358 required multiple LC PHI nodes. */
359
360static bool
361add_exit_phis (bitmap names_to_rename, bitmap *use_blocks)
362{
363 unsigned i;
364 bitmap_iterator bi;
365 bool multiple_p = false;
366
367 /* Sort names_to_rename after definition loop so we can avoid re-computing
368 def_loop_exits. */
369 auto_vec<std::pair<int, int> > names (bitmap_count_bits (names_to_rename));
370 EXECUTE_IF_SET_IN_BITMAP (names_to_rename, 0, i, bi)
371 {
372 tree name = ssa_name (i);
373 loop_p def_loop = gimple_bb (SSA_NAME_DEF_STMT (name))->loop_father;
374 names.quick_push (obj: std::make_pair (x&: def_loop->num, y&: i));
375 }
376 names.qsort (loop_name_cmp);
377
378 auto_bitmap def_loop_exits (&loop_renamer_obstack);
379 loop_p last_def_loop = NULL;
380 for (auto p : names)
381 {
382 loop_p def_loop = get_loop (cfun, num: p.first);
383 if (def_loop != last_def_loop)
384 {
385 bitmap_clear (def_loop_exits);
386 last_def_loop = def_loop;
387 for (class loop *loop = def_loop; loop != current_loops->tree_root;
388 loop = loop_outer (loop))
389 for (auto exit = loop->exits->next; exit->e; exit = exit->next)
390 bitmap_set_bit (def_loop_exits, exit->e->dest->index);
391 }
392 if (add_exit_phis_var (ssa_name (p.second), use_blocks: use_blocks[p.second],
393 def_loop_exits) > 1)
394 multiple_p = true;
395 }
396
397 return multiple_p;
398}
399
400/* For USE in BB, if it is used outside of the loop it is defined in,
401 mark it for rewrite. Record basic block BB where it is used
402 to USE_BLOCKS. Record the ssa name index to NEED_PHIS bitmap.
403 Note that for USEs in phis, BB should be the src of the edge corresponding to
404 the use, rather than the bb containing the phi. */
405
406static void
407find_uses_to_rename_use (basic_block bb, tree use, bitmap *use_blocks,
408 bitmap need_phis)
409{
410 unsigned ver;
411 basic_block def_bb;
412 class loop *def_loop;
413
414 if (TREE_CODE (use) != SSA_NAME)
415 return;
416
417 ver = SSA_NAME_VERSION (use);
418 def_bb = gimple_bb (SSA_NAME_DEF_STMT (use));
419 if (!def_bb)
420 return;
421 def_loop = def_bb->loop_father;
422
423 /* If the definition is not inside a loop, it is not interesting. */
424 if (!loop_outer (loop: def_loop))
425 return;
426
427 /* If the use is not outside of the loop it is defined in, it is not
428 interesting. */
429 if (flow_bb_inside_loop_p (def_loop, bb))
430 return;
431
432 /* If we're seeing VER for the first time, we still have to allocate
433 a bitmap for its uses. */
434 if (bitmap_set_bit (need_phis, ver))
435 use_blocks[ver] = BITMAP_ALLOC (obstack: &loop_renamer_obstack);
436 bitmap_set_bit (use_blocks[ver], bb->index);
437}
438
439/* For uses matching USE_FLAGS in STMT, mark names that are used outside of the
440 loop they are defined to rewrite. Record the set of blocks in which the ssa
441 names are used to USE_BLOCKS, and the ssa names themselves to NEED_PHIS. */
442
443static void
444find_uses_to_rename_stmt (gimple *stmt, bitmap *use_blocks, bitmap need_phis,
445 int use_flags)
446{
447 ssa_op_iter iter;
448 tree var;
449 basic_block bb = gimple_bb (g: stmt);
450
451 if (is_gimple_debug (gs: stmt))
452 return;
453
454 /* FOR_EACH_SSA_TREE_OPERAND iterator does not allows SSA_OP_VIRTUAL_USES
455 only. */
456 if (use_flags == SSA_OP_VIRTUAL_USES)
457 {
458 tree vuse = gimple_vuse (g: stmt);
459 if (vuse != NULL_TREE)
460 find_uses_to_rename_use (bb, use: gimple_vuse (g: stmt), use_blocks, need_phis);
461 }
462 else
463 FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, use_flags)
464 find_uses_to_rename_use (bb, use: var, use_blocks, need_phis);
465}
466
467/* Marks names matching USE_FLAGS that are used in BB and outside of the loop
468 they are defined in for rewrite. Records the set of blocks in which the ssa
469 names are used to USE_BLOCKS. Record the SSA names that will
470 need exit PHIs in NEED_PHIS. */
471
472static void
473find_uses_to_rename_bb (basic_block bb, bitmap *use_blocks, bitmap need_phis,
474 int use_flags)
475{
476 edge e;
477 edge_iterator ei;
478 bool do_virtuals = (use_flags & SSA_OP_VIRTUAL_USES) != 0;
479 bool do_nonvirtuals = (use_flags & SSA_OP_USE) != 0;
480
481 FOR_EACH_EDGE (e, ei, bb->succs)
482 for (gphi_iterator bsi = gsi_start_phis (e->dest); !gsi_end_p (i: bsi);
483 gsi_next (i: &bsi))
484 {
485 gphi *phi = bsi.phi ();
486 bool virtual_p = virtual_operand_p (op: gimple_phi_result (gs: phi));
487 if ((virtual_p && do_virtuals)
488 || (!virtual_p && do_nonvirtuals))
489 find_uses_to_rename_use (bb, PHI_ARG_DEF_FROM_EDGE (phi, e),
490 use_blocks, need_phis);
491 }
492
493 for (gimple_stmt_iterator bsi = gsi_start_bb (bb); !gsi_end_p (i: bsi);
494 gsi_next (i: &bsi))
495 find_uses_to_rename_stmt (stmt: gsi_stmt (i: bsi), use_blocks, need_phis,
496 use_flags);
497}
498
499/* Marks names matching USE_FLAGS that are used outside of the loop they are
500 defined in for rewrite. Records the set of blocks in which the ssa names are
501 used to USE_BLOCKS. Record the SSA names that will need exit PHIs in
502 NEED_PHIS. If CHANGED_BBS is not NULL, scan only blocks in this set. */
503
504static void
505find_uses_to_rename (bitmap changed_bbs, bitmap *use_blocks, bitmap need_phis,
506 int use_flags)
507{
508 basic_block bb;
509 unsigned index;
510 bitmap_iterator bi;
511
512 if (changed_bbs)
513 EXECUTE_IF_SET_IN_BITMAP (changed_bbs, 0, index, bi)
514 {
515 bb = BASIC_BLOCK_FOR_FN (cfun, index);
516 if (bb)
517 find_uses_to_rename_bb (bb, use_blocks, need_phis, use_flags);
518 }
519 else
520 FOR_EACH_BB_FN (bb, cfun)
521 find_uses_to_rename_bb (bb, use_blocks, need_phis, use_flags);
522}
523
524/* Rewrites the program into a loop closed ssa form -- i.e. inserts extra
525 phi nodes to ensure that no variable is used outside the loop it is
526 defined in.
527
528 This strengthening of the basic ssa form has several advantages:
529
530 1) Updating it during unrolling/peeling/versioning is trivial, since
531 we do not need to care about the uses outside of the loop.
532 The same applies to virtual operands which are also rewritten into
533 loop closed SSA form. Note that virtual operands are always live
534 until function exit.
535 2) The behavior of all uses of an induction variable is the same.
536 Without this, you need to distinguish the case when the variable
537 is used outside of the loop it is defined in, for example
538
539 for (i = 0; i < 100; i++)
540 {
541 for (j = 0; j < 100; j++)
542 {
543 k = i + j;
544 use1 (k);
545 }
546 use2 (k);
547 }
548
549 Looking from the outer loop with the normal SSA form, the first use of k
550 is not well-behaved, while the second one is an induction variable with
551 base 99 and step 1.
552
553 If CHANGED_BBS is not NULL, we look for uses outside loops only in the
554 basic blocks in this set.
555
556 USE_FLAGS allows us to specify whether we want virtual, non-virtual or
557 both variables rewritten.
558
559 UPDATE_FLAG is used in the call to update_ssa. See
560 TODO_update_ssa* for documentation. */
561
562static void
563rewrite_into_loop_closed_ssa_1 (bitmap changed_bbs, unsigned update_flag,
564 int use_flags)
565{
566 bitmap *use_blocks;
567 bitmap names_to_rename;
568
569 loops_state_set (flags: LOOP_CLOSED_SSA);
570 if (number_of_loops (cfun) <= 1)
571 return;
572
573 /* If the pass has caused the SSA form to be out-of-date, update it
574 now. */
575 if (update_flag != 0)
576 update_ssa (update_flag);
577 else if (flag_checking)
578 verify_ssa (true, true);
579
580 bitmap_obstack_initialize (&loop_renamer_obstack);
581
582 names_to_rename = BITMAP_ALLOC (obstack: &loop_renamer_obstack);
583
584 /* Uses of names to rename. We don't have to initialize this array,
585 because we know that we will only have entries for the SSA names
586 in NAMES_TO_RENAME. */
587 use_blocks = XNEWVEC (bitmap, num_ssa_names);
588 find_uses_to_rename (changed_bbs, use_blocks, need_phis: names_to_rename, use_flags);
589
590 if (!bitmap_empty_p (map: names_to_rename))
591 {
592 bool release_recorded_exits_p = false;
593 if (!loops_state_satisfies_p (flags: LOOPS_HAVE_RECORDED_EXITS))
594 {
595 /* Doing one scan over the whole function is cheaper than
596 traversing the loop tree and gathering BBs of each loop. */
597 record_loop_exits ();
598 release_recorded_exits_p = true;
599 }
600
601 /* Add the PHI nodes on exits of the loops for the names we need to
602 rewrite. When no variable required multiple LC PHI nodes to be
603 inserted then we know that all uses outside of the loop are
604 dominated by the single LC SSA definition and no further PHI
605 node insertions are required. */
606 bool need_phis_p = add_exit_phis (names_to_rename, use_blocks);
607
608 if (release_recorded_exits_p)
609 release_recorded_exits (cfun);
610
611 /* Fix up all the names found to be used outside their original
612 loops. */
613 update_ssa (need_phis_p ? TODO_update_ssa : TODO_update_ssa_no_phi);
614 }
615
616 bitmap_obstack_release (&loop_renamer_obstack);
617 free (ptr: use_blocks);
618}
619
620/* Rewrites the defs and uses into a loop closed ssa form.
621 If CHANGED_BBS is not NULL, we look for uses outside loops only in the basic
622 blocks in this set. UPDATE_FLAG is used in the call to update_ssa. See
623 TODO_update_ssa* for documentation. */
624
625void
626rewrite_into_loop_closed_ssa (bitmap changed_bbs, unsigned update_flag)
627{
628 rewrite_into_loop_closed_ssa_1 (changed_bbs, update_flag, SSA_OP_ALL_USES);
629}
630
631/* Check invariants of the loop closed ssa form for the def in DEF_BB. */
632
633static void
634check_loop_closed_ssa_def (basic_block def_bb, tree def)
635{
636 use_operand_p use_p;
637 imm_use_iterator iterator;
638 FOR_EACH_IMM_USE_FAST (use_p, iterator, def)
639 {
640 if (is_gimple_debug (USE_STMT (use_p)))
641 continue;
642
643 basic_block use_bb = gimple_bb (USE_STMT (use_p));
644 if (is_a <gphi *> (USE_STMT (use_p)))
645 use_bb = EDGE_PRED (use_bb, PHI_ARG_INDEX_FROM_USE (use_p))->src;
646
647 gcc_assert (flow_bb_inside_loop_p (def_bb->loop_father, use_bb));
648 }
649}
650
651/* Checks invariants of loop closed ssa form in BB. */
652
653static void
654check_loop_closed_ssa_bb (basic_block bb)
655{
656 for (gphi_iterator bsi = gsi_start_phis (bb); !gsi_end_p (i: bsi);
657 gsi_next (i: &bsi))
658 {
659 gphi *phi = bsi.phi ();
660
661 check_loop_closed_ssa_def (def_bb: bb, PHI_RESULT (phi));
662 }
663
664 for (gimple_stmt_iterator bsi = gsi_start_nondebug_bb (bb); !gsi_end_p (i: bsi);
665 gsi_next_nondebug (i: &bsi))
666 {
667 ssa_op_iter iter;
668 tree var;
669 gimple *stmt = gsi_stmt (i: bsi);
670
671 FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_ALL_DEFS)
672 check_loop_closed_ssa_def (def_bb: bb, def: var);
673 }
674}
675
676/* Checks that invariants of the loop closed ssa form are preserved.
677 Call verify_ssa when VERIFY_SSA_P is true. Note all loops are checked
678 if LOOP is NULL, otherwise, only LOOP is checked. */
679
680DEBUG_FUNCTION void
681verify_loop_closed_ssa (bool verify_ssa_p, class loop *loop)
682{
683 if (number_of_loops (cfun) <= 1)
684 return;
685
686 timevar_push (tv: TV_VERIFY_LOOP_CLOSED);
687
688 if (loop == NULL)
689 {
690 basic_block bb;
691
692 if (verify_ssa_p)
693 verify_ssa (false, true);
694
695 FOR_EACH_BB_FN (bb, cfun)
696 if (bb->loop_father && bb->loop_father->num > 0)
697 check_loop_closed_ssa_bb (bb);
698 }
699 else
700 {
701 basic_block *bbs = get_loop_body (loop);
702
703 /* We do not have loop-local SSA verification so just
704 check there's no update queued. */
705 if (verify_ssa_p)
706 gcc_assert (!need_ssa_update_p (cfun));
707
708 for (unsigned i = 0; i < loop->num_nodes; ++i)
709 check_loop_closed_ssa_bb (bb: bbs[i]);
710
711 free (ptr: bbs);
712 }
713
714 timevar_pop (tv: TV_VERIFY_LOOP_CLOSED);
715}
716
717/* Split loop exit edge EXIT. The things are a bit complicated by a need to
718 preserve the loop closed ssa form. If COPY_CONSTANTS_P is true then
719 forwarder PHIs are also created for constant arguments.
720 The newly created block is returned. */
721
722basic_block
723split_loop_exit_edge (edge exit, bool copy_constants_p)
724{
725 basic_block dest = exit->dest;
726 basic_block bb = split_edge (exit);
727 gphi *phi, *new_phi;
728 tree new_name, name;
729 use_operand_p op_p;
730 gphi_iterator psi;
731 location_t locus;
732
733 for (psi = gsi_start_phis (dest); !gsi_end_p (i: psi); gsi_next (i: &psi))
734 {
735 phi = psi.phi ();
736 op_p = PHI_ARG_DEF_PTR_FROM_EDGE (phi, single_succ_edge (bb));
737 locus = gimple_phi_arg_location_from_edge (phi, e: single_succ_edge (bb));
738
739 name = USE_FROM_PTR (op_p);
740
741 /* If the argument of the PHI node is a constant, we do not need
742 to keep it inside loop. */
743 if (TREE_CODE (name) != SSA_NAME
744 && !copy_constants_p)
745 continue;
746
747 /* Otherwise create an auxiliary phi node that will copy the value
748 of the SSA name out of the loop. */
749 new_name = duplicate_ssa_name (PHI_RESULT (phi), NULL);
750 new_phi = create_phi_node (new_name, bb);
751 add_phi_arg (new_phi, name, exit, locus);
752 SET_USE (op_p, new_name);
753 }
754
755 return bb;
756}
757
758/* Returns the basic block in that statements should be emitted for induction
759 variables incremented at the end of the LOOP. */
760
761basic_block
762ip_end_pos (class loop *loop)
763{
764 return loop->latch;
765}
766
767/* Returns the basic block in that statements should be emitted for induction
768 variables incremented just before exit condition of a LOOP. */
769
770basic_block
771ip_normal_pos (class loop *loop)
772{
773 basic_block bb;
774 edge exit;
775
776 if (!single_pred_p (bb: loop->latch))
777 return NULL;
778
779 bb = single_pred (bb: loop->latch);
780 if (!safe_is_a <gcond *> (p: *gsi_last_bb (bb)))
781 return NULL;
782
783 exit = EDGE_SUCC (bb, 0);
784 if (exit->dest == loop->latch)
785 exit = EDGE_SUCC (bb, 1);
786
787 if (flow_bb_inside_loop_p (loop, exit->dest))
788 return NULL;
789
790 return bb;
791}
792
793/* Stores the standard position for induction variable increment in LOOP
794 (just before the exit condition if it is available and latch block is empty,
795 end of the latch block otherwise) to BSI. INSERT_AFTER is set to true if
796 the increment should be inserted after *BSI. */
797
798void
799standard_iv_increment_position (class loop *loop, gimple_stmt_iterator *bsi,
800 bool *insert_after)
801{
802 basic_block bb = ip_normal_pos (loop), latch = ip_end_pos (loop);
803 gimple *last = last_nondebug_stmt (latch);
804
805 if (!bb
806 || (last && gimple_code (g: last) != GIMPLE_LABEL))
807 {
808 *bsi = gsi_last_bb (bb: latch);
809 *insert_after = true;
810 }
811 else
812 {
813 *bsi = gsi_last_bb (bb);
814 *insert_after = false;
815 }
816}
817
818/* Copies phi node arguments for duplicated blocks. The index of the first
819 duplicated block is FIRST_NEW_BLOCK. */
820
821static void
822copy_phi_node_args (unsigned first_new_block)
823{
824 unsigned i;
825
826 for (i = first_new_block; i < (unsigned) last_basic_block_for_fn (cfun); i++)
827 BASIC_BLOCK_FOR_FN (cfun, i)->flags |= BB_DUPLICATED;
828
829 for (i = first_new_block; i < (unsigned) last_basic_block_for_fn (cfun); i++)
830 add_phi_args_after_copy_bb (BASIC_BLOCK_FOR_FN (cfun, i));
831
832 for (i = first_new_block; i < (unsigned) last_basic_block_for_fn (cfun); i++)
833 BASIC_BLOCK_FOR_FN (cfun, i)->flags &= ~BB_DUPLICATED;
834}
835
836
837/* The same as cfgloopmanip.cc:duplicate_loop_body_to_header_edge, but also
838 updates the PHI nodes at start of the copied region. In order to
839 achieve this, only loops whose exits all lead to the same location
840 are handled.
841
842 Notice that we do not completely update the SSA web after
843 duplication. The caller is responsible for calling update_ssa
844 after the loop has been duplicated. */
845
846bool
847gimple_duplicate_loop_body_to_header_edge (class loop *loop, edge e,
848 unsigned int ndupl,
849 sbitmap wont_exit, edge orig,
850 vec<edge> *to_remove, int flags)
851{
852 unsigned first_new_block;
853
854 if (!loops_state_satisfies_p (flags: LOOPS_HAVE_SIMPLE_LATCHES))
855 return false;
856 if (!loops_state_satisfies_p (flags: LOOPS_HAVE_PREHEADERS))
857 return false;
858
859 first_new_block = last_basic_block_for_fn (cfun);
860 if (!duplicate_loop_body_to_header_edge (loop, e, ndupl, wont_exit, orig,
861 to_remove, flags))
862 return false;
863
864 /* Readd the removed phi args for e. */
865 flush_pending_stmts (e);
866
867 /* Copy the phi node arguments. */
868 copy_phi_node_args (first_new_block);
869
870 scev_reset ();
871
872 return true;
873}
874
875/* Returns true if we can unroll LOOP FACTOR times. Number
876 of iterations of the loop is returned in NITER. */
877
878bool
879can_unroll_loop_p (class loop *loop, unsigned factor,
880 class tree_niter_desc *niter)
881{
882 edge exit;
883
884 /* Check whether unrolling is possible. We only want to unroll loops
885 for that we are able to determine number of iterations. We also
886 want to split the extra iterations of the loop from its end,
887 therefore we require that the loop has precisely one
888 exit. */
889
890 exit = single_dom_exit (loop);
891 if (!exit)
892 return false;
893
894 if (!number_of_iterations_exit (loop, exit, niter, false)
895 || niter->cmp == ERROR_MARK
896 /* Scalar evolutions analysis might have copy propagated
897 the abnormal ssa names into these expressions, hence
898 emitting the computations based on them during loop
899 unrolling might create overlapping life ranges for
900 them, and failures in out-of-ssa. */
901 || contains_abnormal_ssa_name_p (niter->may_be_zero)
902 || contains_abnormal_ssa_name_p (niter->control.base)
903 || contains_abnormal_ssa_name_p (niter->control.step)
904 || contains_abnormal_ssa_name_p (niter->bound))
905 return false;
906
907 /* And of course, we must be able to duplicate the loop. */
908 if (!can_duplicate_loop_p (loop))
909 return false;
910
911 /* The final loop should be small enough. */
912 if (tree_num_loop_insns (loop, &eni_size_weights) * factor
913 > (unsigned) param_max_unrolled_insns)
914 return false;
915
916 return true;
917}
918
919/* Determines the conditions that control execution of LOOP unrolled FACTOR
920 times. DESC is number of iterations of LOOP. ENTER_COND is set to
921 condition that must be true if the main loop can be entered.
922 If the loop does not always iterate an exact multiple of FACTOR times,
923 EXIT_BASE, EXIT_STEP, EXIT_CMP and EXIT_BOUND are set to values describing
924 how the exit from the unrolled loop should be controlled. Otherwise,
925 the trees are set to null and EXIT_CMP is set to ERROR_MARK. */
926
927static void
928determine_exit_conditions (class loop *loop, class tree_niter_desc *desc,
929 unsigned factor, tree *enter_cond,
930 tree *exit_base, tree *exit_step,
931 enum tree_code *exit_cmp, tree *exit_bound)
932{
933 gimple_seq stmts;
934 tree base = desc->control.base;
935 tree step = desc->control.step;
936 tree bound = desc->bound;
937 tree type = TREE_TYPE (step);
938 tree bigstep, delta;
939 tree min = lower_bound_in_type (type, type);
940 tree max = upper_bound_in_type (type, type);
941 enum tree_code cmp = desc->cmp;
942 tree cond = boolean_true_node, assum;
943
944 /* For pointers, do the arithmetics in the type of step. */
945 base = fold_convert (type, base);
946 bound = fold_convert (type, bound);
947
948 *enter_cond = boolean_false_node;
949 *exit_base = NULL_TREE;
950 *exit_step = NULL_TREE;
951 *exit_cmp = ERROR_MARK;
952 *exit_bound = NULL_TREE;
953 gcc_assert (cmp != ERROR_MARK);
954
955 /* We only need to be correct when we answer question
956 "Do at least FACTOR more iterations remain?" in the unrolled loop.
957 Thus, transforming BASE + STEP * i <> BOUND to
958 BASE + STEP * i < BOUND is ok. */
959 if (cmp == NE_EXPR)
960 {
961 if (tree_int_cst_sign_bit (step))
962 cmp = GT_EXPR;
963 else
964 cmp = LT_EXPR;
965 }
966 else if (cmp == LT_EXPR)
967 {
968 gcc_assert (!tree_int_cst_sign_bit (step));
969 }
970 else if (cmp == GT_EXPR)
971 {
972 gcc_assert (tree_int_cst_sign_bit (step));
973 }
974 else
975 gcc_unreachable ();
976
977 /* The main body of the loop may be entered iff:
978
979 1) desc->may_be_zero is false.
980 2) it is possible to check that there are at least FACTOR iterations
981 of the loop, i.e., BOUND - step * FACTOR does not overflow.
982 3) # of iterations is at least FACTOR */
983
984 if (!integer_zerop (desc->may_be_zero))
985 cond = fold_build2 (TRUTH_AND_EXPR, boolean_type_node,
986 invert_truthvalue (desc->may_be_zero),
987 cond);
988
989 bigstep = fold_build2 (MULT_EXPR, type, step,
990 build_int_cst_type (type, factor));
991 delta = fold_build2 (MINUS_EXPR, type, bigstep, step);
992 if (cmp == LT_EXPR)
993 assum = fold_build2 (GE_EXPR, boolean_type_node,
994 bound,
995 fold_build2 (PLUS_EXPR, type, min, delta));
996 else
997 assum = fold_build2 (LE_EXPR, boolean_type_node,
998 bound,
999 fold_build2 (PLUS_EXPR, type, max, delta));
1000 cond = fold_build2 (TRUTH_AND_EXPR, boolean_type_node, assum, cond);
1001
1002 bound = fold_build2 (MINUS_EXPR, type, bound, delta);
1003 assum = fold_build2 (cmp, boolean_type_node, base, bound);
1004 cond = fold_build2 (TRUTH_AND_EXPR, boolean_type_node, assum, cond);
1005
1006 if (integer_nonzerop (cond)
1007 && integer_zerop (desc->may_be_zero))
1008 {
1009 /* Convert the latch count to an iteration count. */
1010 tree niter = fold_build2 (PLUS_EXPR, type, desc->niter,
1011 build_one_cst (type));
1012 if (multiple_of_p (type, niter, build_int_cst (type, factor)))
1013 return;
1014 }
1015
1016 cond = force_gimple_operand (unshare_expr (cond), &stmts, false, NULL_TREE);
1017 if (stmts)
1018 gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts);
1019 /* cond now may be a gimple comparison, which would be OK, but also any
1020 other gimple rhs (say a && b). In this case we need to force it to
1021 operand. */
1022 if (!is_gimple_condexpr_for_cond (cond))
1023 {
1024 cond = force_gimple_operand (cond, &stmts, true, NULL_TREE);
1025 if (stmts)
1026 gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts);
1027 }
1028 *enter_cond = cond;
1029
1030 base = force_gimple_operand (unshare_expr (base), &stmts, true, NULL_TREE);
1031 if (stmts)
1032 gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts);
1033 bound = force_gimple_operand (unshare_expr (bound), &stmts, true, NULL_TREE);
1034 if (stmts)
1035 gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts);
1036
1037 *exit_base = base;
1038 *exit_step = bigstep;
1039 *exit_cmp = cmp;
1040 *exit_bound = bound;
1041}
1042
1043/* Unroll LOOP FACTOR times. LOOP is known to have a single exit edge
1044 whose source block dominates the latch. DESC describes the number of
1045 iterations of LOOP.
1046
1047 If N is number of iterations of the loop and MAY_BE_ZERO is the condition
1048 under that loop exits in the first iteration even if N != 0,
1049
1050 while (1)
1051 {
1052 x = phi (init, next);
1053
1054 pre;
1055 if (st)
1056 break;
1057 post;
1058 }
1059
1060 becomes (with possibly the exit conditions formulated a bit differently,
1061 avoiding the need to create a new iv):
1062
1063 if (MAY_BE_ZERO || N < FACTOR)
1064 goto rest;
1065
1066 do
1067 {
1068 x = phi (init, next);
1069
1070 pre;
1071 post;
1072 pre;
1073 post;
1074 ...
1075 pre;
1076 post;
1077 N -= FACTOR;
1078
1079 } while (N >= FACTOR);
1080
1081 rest:
1082 init' = phi (init, x);
1083
1084 while (1)
1085 {
1086 x = phi (init', next);
1087
1088 pre;
1089 if (st)
1090 break;
1091 post;
1092 }
1093
1094 Before the loop is unrolled, TRANSFORM is called for it (only for the
1095 unrolled loop, but not for its versioned copy). DATA is passed to
1096 TRANSFORM. */
1097
1098/* Probability in % that the unrolled loop is entered. Just a guess. */
1099#define PROB_UNROLLED_LOOP_ENTERED 90
1100
1101void
1102tree_transform_and_unroll_loop (class loop *loop, unsigned factor,
1103 class tree_niter_desc *desc,
1104 transform_callback transform,
1105 void *data)
1106{
1107 unsigned irr = loop_preheader_edge (loop)->flags & EDGE_IRREDUCIBLE_LOOP;
1108
1109 enum tree_code exit_cmp;
1110 tree enter_main_cond, exit_base, exit_step, exit_bound;
1111 bool flat = maybe_flat_loop_profile (loop);
1112 determine_exit_conditions (loop, desc, factor,
1113 enter_cond: &enter_main_cond, exit_base: &exit_base, exit_step: &exit_step,
1114 exit_cmp: &exit_cmp, exit_bound: &exit_bound);
1115 bool single_loop_p = !exit_base;
1116
1117 gcond *exit_if = nullptr;
1118 class loop *new_loop = nullptr;
1119 edge new_exit;
1120 if (!single_loop_p)
1121 {
1122 profile_count entry_count = loop_preheader_edge (loop)->src->count;
1123 /* Let us assume that the unrolled loop is quite likely to be entered. */
1124 profile_probability prob_entry;
1125 if (integer_nonzerop (enter_main_cond))
1126 prob_entry = profile_probability::always ();
1127 else
1128 prob_entry = profile_probability::guessed_always ()
1129 .apply_scale (PROB_UNROLLED_LOOP_ENTERED, den: 100);
1130
1131
1132 /* The values for scales should keep profile consistent, and somewhat
1133 close to correct. */
1134 new_loop = loop_version (loop, enter_main_cond, NULL, prob_entry,
1135 prob_entry.invert (),
1136 prob_entry,
1137 /* We will later redirect exit from vectorized
1138 loop to new_loop. */
1139 profile_probability::always (),
1140 true);
1141 gcc_assert (new_loop != NULL);
1142 update_ssa (TODO_update_ssa_no_phi);
1143
1144 /* Prepare the cfg and update the phi nodes. Move the loop exit to the
1145 loop latch (and make its condition dummy, for the moment). */
1146 basic_block rest = loop_preheader_edge (new_loop)->src;
1147 edge precond_edge = single_pred_edge (bb: rest);
1148 split_edge (loop_latch_edge (loop));
1149 basic_block exit_bb = single_pred (bb: loop->latch);
1150 edge exit = single_dom_exit (loop);
1151
1152 /* Since the exit edge will be removed, the frequency of all the blocks
1153 in the loop that are dominated by it must be scaled. */
1154 if (exit->probability.initialized_p ())
1155 scale_dominated_blocks_in_loop (loop, bb: exit->src,
1156 /* We are scaling up here so
1157 probability does not fit. */
1158 num: exit->src->count,
1159 den: exit->src->count - exit->count ());
1160
1161 gimple_stmt_iterator bsi = gsi_last_bb (bb: exit_bb);
1162 exit_if = gimple_build_cond (EQ_EXPR, integer_zero_node,
1163 integer_zero_node,
1164 NULL_TREE, NULL_TREE);
1165
1166 gsi_insert_after (&bsi, exit_if, GSI_NEW_STMT);
1167 new_exit = make_edge (exit_bb, rest, EDGE_FALSE_VALUE | irr);
1168 rescan_loop_exit (new_exit, true, false);
1169
1170 /* Set the probability of new exit to the same of the old one. Fix
1171 the count of the latch block. */
1172 new_exit->probability = exit->probability;
1173 edge new_nonexit = single_pred_edge (bb: loop->latch);
1174 new_nonexit->probability = exit->probability.invert ();
1175 new_nonexit->flags = EDGE_TRUE_VALUE;
1176 set_edge_probability_and_rescale_others
1177 (exit, profile_probability::never ());
1178 loop->latch->count = new_nonexit->count ();
1179
1180 edge old_entry = loop_preheader_edge (loop);
1181 edge new_entry = loop_preheader_edge (new_loop);
1182 edge old_latch = loop_latch_edge (loop);
1183 for (gphi_iterator psi_old_loop = gsi_start_phis (loop->header),
1184 psi_new_loop = gsi_start_phis (new_loop->header);
1185 !gsi_end_p (i: psi_old_loop);
1186 gsi_next (i: &psi_old_loop), gsi_next (i: &psi_new_loop))
1187 {
1188 gphi *phi_old_loop = psi_old_loop.phi ();
1189 gphi *phi_new_loop = psi_new_loop.phi ();
1190
1191 tree init = PHI_ARG_DEF_FROM_EDGE (phi_old_loop, old_entry);
1192 use_operand_p op
1193 = PHI_ARG_DEF_PTR_FROM_EDGE (phi_new_loop, new_entry);
1194 gcc_assert (operand_equal_for_phi_arg_p (init, USE_FROM_PTR (op)));
1195 tree next = PHI_ARG_DEF_FROM_EDGE (phi_old_loop, old_latch);
1196
1197 /* Prefer using original variable as a base for the new ssa name.
1198 This is necessary for virtual ops, and useful in order to avoid
1199 losing debug info for real ops. */
1200 tree new_init;
1201 if (TREE_CODE (next) == SSA_NAME
1202 && useless_type_conversion_p (TREE_TYPE (next),
1203 TREE_TYPE (init)))
1204 new_init = copy_ssa_name (var: next);
1205 else if (TREE_CODE (init) == SSA_NAME
1206 && useless_type_conversion_p (TREE_TYPE (init),
1207 TREE_TYPE (next)))
1208 new_init = copy_ssa_name (var: init);
1209 else if (useless_type_conversion_p (TREE_TYPE (next),
1210 TREE_TYPE (init)))
1211 new_init = make_temp_ssa_name (TREE_TYPE (next), NULL,
1212 name: "unrinittmp");
1213 else
1214 new_init = make_temp_ssa_name (TREE_TYPE (init), NULL,
1215 name: "unrinittmp");
1216
1217 gphi *phi_rest = create_phi_node (new_init, rest);
1218 add_phi_arg (phi_rest, init, precond_edge, UNKNOWN_LOCATION);
1219 add_phi_arg (phi_rest, next, new_exit, UNKNOWN_LOCATION);
1220 SET_USE (op, new_init);
1221 }
1222
1223 remove_path (exit);
1224 /* We will later redirect exit from vectorized loop to new_loop. */
1225 loop_preheader_edge (new_loop)->src->count = entry_count;
1226
1227 /* The epilog loop latch executes at most factor - 1 times.
1228 Since the epilog is entered unconditionally it will need to handle
1229 up to factor executions of its body. */
1230 new_loop->any_upper_bound = true;
1231 new_loop->nb_iterations_upper_bound = factor - 1;
1232 /* We do not really know estimate on number of iterations, since we do not
1233 track any estimates modulo unroll factor.
1234 Drop estimate from loop_info and scale loop profile.
1235 It may be more realistic to scale loop profile to factor / 2 - 1,
1236 but vectorizer also uses factor - 1. */
1237 new_loop->any_estimate = false;
1238 scale_loop_profile (new_loop, profile_probability::always (), factor - 1);
1239 }
1240 else
1241 new_exit = single_dom_exit (loop);
1242
1243 /* Transform the loop. */
1244 if (transform)
1245 (*transform) (loop, data);
1246
1247 /* Unroll the loop and remove the exits in all iterations except for the
1248 last one. */
1249 auto_sbitmap wont_exit (factor);
1250 bitmap_ones (wont_exit);
1251 bitmap_clear_bit (map: wont_exit, bitno: factor - 1);
1252
1253 auto_vec<edge> to_remove;
1254 bool ok
1255 = gimple_duplicate_loop_body_to_header_edge
1256 (loop, e: loop_latch_edge (loop), ndupl: factor - 1, wont_exit,
1257 orig: new_exit, to_remove: &to_remove,
1258 DLTHE_FLAG_UPDATE_FREQ | (flat ? DLTHE_FLAG_FLAT_PROFILE : 0));
1259 gcc_assert (ok);
1260
1261 for (edge e : to_remove)
1262 {
1263 ok = remove_path (e);
1264 gcc_assert (ok);
1265 }
1266 update_ssa (TODO_update_ssa);
1267
1268 new_exit = single_dom_exit (loop);
1269 /* gimple_duplicate_loop_body_to_header_edge depending on
1270 DLTHE_FLAG_UPDATE_FREQ either keeps original frequency of the loop header
1271 or scales it down accordingly.
1272 However exit edge probability is kept as original. Fix it if needed
1273 and compensate. */
1274 update_loop_exit_probability_scale_dom_bbs (loop, exit_edge: new_exit);
1275 if (!single_loop_p)
1276 {
1277 /* Finally create the new counter for number of iterations and add
1278 the new exit instruction. */
1279 tree ctr_before, ctr_after;
1280 gimple_stmt_iterator bsi = gsi_last_nondebug_bb (bb: new_exit->src);
1281 exit_if = as_a <gcond *> (p: gsi_stmt (i: bsi));
1282 create_iv (base: exit_base, incr_op: PLUS_EXPR, step: exit_step, NULL_TREE, loop,
1283 incr_pos: &bsi, after: false, var_before: &ctr_before, var_after: &ctr_after);
1284 gimple_cond_set_code (gs: exit_if, code: exit_cmp);
1285 gimple_cond_set_lhs (gs: exit_if, lhs: ctr_after);
1286 gimple_cond_set_rhs (gs: exit_if, rhs: exit_bound);
1287 update_stmt (s: exit_if);
1288 }
1289 if (loop->any_upper_bound)
1290 loop->nb_iterations_upper_bound = wi::udiv_floor
1291 (x: loop->nb_iterations_upper_bound + 1, y: factor) - 1;
1292 if (loop->any_likely_upper_bound)
1293 loop->nb_iterations_likely_upper_bound = wi::udiv_floor
1294 (x: loop->nb_iterations_likely_upper_bound + 1, y: factor) - 1;
1295 if (loop->any_estimate)
1296 loop->nb_iterations_estimate = wi::udiv_floor
1297 (x: loop->nb_iterations_estimate + 1, y: factor) - 1;
1298
1299 checking_verify_flow_info ();
1300 checking_verify_loop_structure ();
1301 checking_verify_loop_closed_ssa (verify_ssa_p: true, loop);
1302 if (new_loop)
1303 checking_verify_loop_closed_ssa (verify_ssa_p: true, loop: new_loop);
1304}
1305
1306/* Wrapper over tree_transform_and_unroll_loop for case we do not
1307 want to transform the loop before unrolling. The meaning
1308 of the arguments is the same as for tree_transform_and_unroll_loop. */
1309
1310void
1311tree_unroll_loop (class loop *loop, unsigned factor,
1312 class tree_niter_desc *desc)
1313{
1314 tree_transform_and_unroll_loop (loop, factor, desc, NULL, NULL);
1315}
1316
1317/* Rewrite the phi node at position PSI in function of the main
1318 induction variable MAIN_IV and insert the generated code at GSI. */
1319
1320static void
1321rewrite_phi_with_iv (loop_p loop,
1322 gphi_iterator *psi,
1323 gimple_stmt_iterator *gsi,
1324 tree main_iv)
1325{
1326 affine_iv iv;
1327 gassign *stmt;
1328 gphi *phi = psi->phi ();
1329 tree atype, mtype, val, res = PHI_RESULT (phi);
1330
1331 if (virtual_operand_p (op: res) || res == main_iv)
1332 {
1333 gsi_next (i: psi);
1334 return;
1335 }
1336
1337 if (!simple_iv (loop, loop, res, &iv, true))
1338 {
1339 gsi_next (i: psi);
1340 return;
1341 }
1342
1343 remove_phi_node (psi, false);
1344
1345 atype = TREE_TYPE (res);
1346 mtype = POINTER_TYPE_P (atype) ? sizetype : atype;
1347 val = fold_build2 (MULT_EXPR, mtype, unshare_expr (iv.step),
1348 fold_convert (mtype, main_iv));
1349 val = fold_build2 (POINTER_TYPE_P (atype)
1350 ? POINTER_PLUS_EXPR : PLUS_EXPR,
1351 atype, unshare_expr (iv.base), val);
1352 val = force_gimple_operand_gsi (gsi, val, false, NULL_TREE, true,
1353 GSI_SAME_STMT);
1354 stmt = gimple_build_assign (res, val);
1355 gsi_insert_before (gsi, stmt, GSI_SAME_STMT);
1356}
1357
1358/* Rewrite all the phi nodes of LOOP in function of the main induction
1359 variable MAIN_IV. */
1360
1361static void
1362rewrite_all_phi_nodes_with_iv (loop_p loop, tree main_iv)
1363{
1364 unsigned i;
1365 basic_block *bbs = get_loop_body_in_dom_order (loop);
1366 gphi_iterator psi;
1367
1368 for (i = 0; i < loop->num_nodes; i++)
1369 {
1370 basic_block bb = bbs[i];
1371 gimple_stmt_iterator gsi = gsi_after_labels (bb);
1372
1373 if (bb->loop_father != loop)
1374 continue;
1375
1376 for (psi = gsi_start_phis (bb); !gsi_end_p (i: psi); )
1377 rewrite_phi_with_iv (loop, psi: &psi, gsi: &gsi, main_iv);
1378 }
1379
1380 free (ptr: bbs);
1381}
1382
1383/* Bases all the induction variables in LOOP on a single induction variable
1384 (with base 0 and step 1), whose final value is compared with *NIT. When the
1385 IV type precision has to be larger than *NIT type precision, *NIT is
1386 converted to the larger type, the conversion code is inserted before the
1387 loop, and *NIT is updated to the new definition. When BUMP_IN_LATCH is true,
1388 the induction variable is incremented in the loop latch, otherwise it is
1389 incremented in the loop header. Return the induction variable that was
1390 created. */
1391
1392tree
1393canonicalize_loop_ivs (class loop *loop, tree *nit, bool bump_in_latch)
1394{
1395 unsigned precision = TYPE_PRECISION (TREE_TYPE (*nit));
1396 unsigned original_precision = precision;
1397 tree type, var_before;
1398 gimple_stmt_iterator gsi;
1399 gphi_iterator psi;
1400 gcond *stmt;
1401 edge exit = single_dom_exit (loop);
1402 gimple_seq stmts;
1403 bool unsigned_p = false;
1404
1405 for (psi = gsi_start_phis (loop->header);
1406 !gsi_end_p (i: psi); gsi_next (i: &psi))
1407 {
1408 gphi *phi = psi.phi ();
1409 tree res = PHI_RESULT (phi);
1410 bool uns;
1411
1412 type = TREE_TYPE (res);
1413 if (virtual_operand_p (op: res)
1414 || (!INTEGRAL_TYPE_P (type)
1415 && !POINTER_TYPE_P (type))
1416 || TYPE_PRECISION (type) < precision)
1417 continue;
1418
1419 uns = POINTER_TYPE_P (type) | TYPE_UNSIGNED (type);
1420
1421 if (TYPE_PRECISION (type) > precision)
1422 unsigned_p = uns;
1423 else
1424 unsigned_p |= uns;
1425
1426 precision = TYPE_PRECISION (type);
1427 }
1428
1429 scalar_int_mode mode = smallest_int_mode_for_size (size: precision);
1430 precision = GET_MODE_PRECISION (mode);
1431 type = build_nonstandard_integer_type (precision, unsigned_p);
1432
1433 if (original_precision != precision
1434 || TYPE_UNSIGNED (TREE_TYPE (*nit)) != unsigned_p)
1435 {
1436 *nit = fold_convert (type, *nit);
1437 *nit = force_gimple_operand (*nit, &stmts, true, NULL_TREE);
1438 if (stmts)
1439 gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts);
1440 }
1441
1442 if (bump_in_latch)
1443 gsi = gsi_last_bb (bb: loop->latch);
1444 else
1445 gsi = gsi_last_nondebug_bb (bb: loop->header);
1446 create_iv (base: build_int_cst_type (type, 0), incr_op: PLUS_EXPR, step: build_int_cst (type, 1),
1447 NULL_TREE, loop, incr_pos: &gsi, after: bump_in_latch, var_before: &var_before, NULL);
1448
1449 rewrite_all_phi_nodes_with_iv (loop, main_iv: var_before);
1450
1451 stmt = as_a <gcond *> (p: *gsi_last_bb (bb: exit->src));
1452 /* Make the loop exit if the control condition is not satisfied. */
1453 if (exit->flags & EDGE_TRUE_VALUE)
1454 {
1455 edge te, fe;
1456
1457 extract_true_false_edges_from_block (exit->src, &te, &fe);
1458 te->flags = EDGE_FALSE_VALUE;
1459 fe->flags = EDGE_TRUE_VALUE;
1460 }
1461 gimple_cond_set_code (gs: stmt, code: LT_EXPR);
1462 gimple_cond_set_lhs (gs: stmt, lhs: var_before);
1463 gimple_cond_set_rhs (gs: stmt, rhs: *nit);
1464 update_stmt (s: stmt);
1465
1466 return var_before;
1467}
1468

source code of gcc/tree-ssa-loop-manip.cc