1/* High-level loop manipulation functions.
2 Copyright (C) 2004-2017 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 "params.h"
45#include "tree-inline.h"
46
47/* All bitmaps for rewriting into loop-closed SSA go on this obstack,
48 so that we can free them all at once. */
49static bitmap_obstack loop_renamer_obstack;
50
51/* Creates an induction variable with value BASE + STEP * iteration in LOOP.
52 It is expected that neither BASE nor STEP are shared with other expressions
53 (unless the sharing rules allow this). Use VAR as a base var_decl for it
54 (if NULL, a new temporary will be created). The increment will occur at
55 INCR_POS (after it if AFTER is true, before it otherwise). INCR_POS and
56 AFTER can be computed using standard_iv_increment_position. The ssa versions
57 of the variable before and after increment will be stored in VAR_BEFORE and
58 VAR_AFTER (unless they are NULL). */
59
60void
61create_iv (tree base, tree step, tree var, struct loop *loop,
62 gimple_stmt_iterator *incr_pos, bool after,
63 tree *var_before, tree *var_after)
64{
65 gassign *stmt;
66 gphi *phi;
67 tree initial, step1;
68 gimple_seq stmts;
69 tree vb, va;
70 enum tree_code incr_op = PLUS_EXPR;
71 edge pe = loop_preheader_edge (loop);
72
73 if (var != NULL_TREE)
74 {
75 vb = make_ssa_name (var);
76 va = make_ssa_name (var);
77 }
78 else
79 {
80 vb = make_temp_ssa_name (TREE_TYPE (base), NULL, "ivtmp");
81 va = make_temp_ssa_name (TREE_TYPE (base), NULL, "ivtmp");
82 }
83 if (var_before)
84 *var_before = vb;
85 if (var_after)
86 *var_after = va;
87
88 /* For easier readability of the created code, produce MINUS_EXPRs
89 when suitable. */
90 if (TREE_CODE (step) == INTEGER_CST)
91 {
92 if (TYPE_UNSIGNED (TREE_TYPE (step)))
93 {
94 step1 = fold_build1 (NEGATE_EXPR, TREE_TYPE (step), step);
95 if (tree_int_cst_lt (step1, step))
96 {
97 incr_op = MINUS_EXPR;
98 step = step1;
99 }
100 }
101 else
102 {
103 bool ovf;
104
105 if (!tree_expr_nonnegative_warnv_p (step, &ovf)
106 && may_negate_without_overflow_p (step))
107 {
108 incr_op = MINUS_EXPR;
109 step = fold_build1 (NEGATE_EXPR, TREE_TYPE (step), step);
110 }
111 }
112 }
113 if (POINTER_TYPE_P (TREE_TYPE (base)))
114 {
115 if (TREE_CODE (base) == ADDR_EXPR)
116 mark_addressable (TREE_OPERAND (base, 0));
117 step = convert_to_ptrofftype (step);
118 if (incr_op == MINUS_EXPR)
119 step = fold_build1 (NEGATE_EXPR, TREE_TYPE (step), step);
120 incr_op = POINTER_PLUS_EXPR;
121 }
122 /* Gimplify the step if necessary. We put the computations in front of the
123 loop (i.e. the step should be loop invariant). */
124 step = force_gimple_operand (step, &stmts, true, NULL_TREE);
125 if (stmts)
126 gsi_insert_seq_on_edge_immediate (pe, stmts);
127
128 stmt = gimple_build_assign (va, incr_op, vb, step);
129 if (after)
130 gsi_insert_after (incr_pos, stmt, GSI_NEW_STMT);
131 else
132 gsi_insert_before (incr_pos, stmt, GSI_NEW_STMT);
133
134 initial = force_gimple_operand (base, &stmts, true, var);
135 if (stmts)
136 gsi_insert_seq_on_edge_immediate (pe, stmts);
137
138 phi = create_phi_node (vb, loop->header);
139 add_phi_arg (phi, initial, loop_preheader_edge (loop), UNKNOWN_LOCATION);
140 add_phi_arg (phi, va, loop_latch_edge (loop), UNKNOWN_LOCATION);
141}
142
143/* Return the innermost superloop LOOP of USE_LOOP that is a superloop of
144 both DEF_LOOP and USE_LOOP. */
145
146static inline struct loop *
147find_sibling_superloop (struct loop *use_loop, struct loop *def_loop)
148{
149 unsigned ud = loop_depth (use_loop);
150 unsigned dd = loop_depth (def_loop);
151 gcc_assert (ud > 0 && dd > 0);
152 if (ud > dd)
153 use_loop = superloop_at_depth (use_loop, dd);
154 if (ud < dd)
155 def_loop = superloop_at_depth (def_loop, ud);
156 while (loop_outer (use_loop) != loop_outer (def_loop))
157 {
158 use_loop = loop_outer (use_loop);
159 def_loop = loop_outer (def_loop);
160 gcc_assert (use_loop && def_loop);
161 }
162 return use_loop;
163}
164
165/* DEF_BB is a basic block containing a DEF that needs rewriting into
166 loop-closed SSA form. USE_BLOCKS is the set of basic blocks containing
167 uses of DEF that "escape" from the loop containing DEF_BB (i.e. blocks in
168 USE_BLOCKS are dominated by DEF_BB but not in the loop father of DEF_B).
169 ALL_EXITS[I] is the set of all basic blocks that exit loop I.
170
171 Compute the subset of LOOP_EXITS that exit the loop containing DEF_BB
172 or one of its loop fathers, in which DEF is live. This set is returned
173 in the bitmap LIVE_EXITS.
174
175 Instead of computing the complete livein set of the def, we use the loop
176 nesting tree as a form of poor man's structure analysis. This greatly
177 speeds up the analysis, which is important because this function may be
178 called on all SSA names that need rewriting, one at a time. */
179
180static void
181compute_live_loop_exits (bitmap live_exits, bitmap use_blocks,
182 bitmap *loop_exits, basic_block def_bb)
183{
184 unsigned i;
185 bitmap_iterator bi;
186 struct loop *def_loop = def_bb->loop_father;
187 unsigned def_loop_depth = loop_depth (def_loop);
188 bitmap def_loop_exits;
189
190 /* Normally the work list size is bounded by the number of basic
191 blocks in the largest loop. We don't know this number, but we
192 can be fairly sure that it will be relatively small. */
193 auto_vec<basic_block> worklist (MAX (8, n_basic_blocks_for_fn (cfun) / 128));
194
195 EXECUTE_IF_SET_IN_BITMAP (use_blocks, 0, i, bi)
196 {
197 basic_block use_bb = BASIC_BLOCK_FOR_FN (cfun, i);
198 struct loop *use_loop = use_bb->loop_father;
199 gcc_checking_assert (def_loop != use_loop
200 && ! flow_loop_nested_p (def_loop, use_loop));
201 if (! flow_loop_nested_p (use_loop, def_loop))
202 use_bb = find_sibling_superloop (use_loop, def_loop)->header;
203 if (bitmap_set_bit (live_exits, use_bb->index))
204 worklist.safe_push (use_bb);
205 }
206
207 /* Iterate until the worklist is empty. */
208 while (! worklist.is_empty ())
209 {
210 edge e;
211 edge_iterator ei;
212
213 /* Pull a block off the worklist. */
214 basic_block bb = worklist.pop ();
215
216 /* Make sure we have at least enough room in the work list
217 for all predecessors of this block. */
218 worklist.reserve (EDGE_COUNT (bb->preds));
219
220 /* For each predecessor block. */
221 FOR_EACH_EDGE (e, ei, bb->preds)
222 {
223 basic_block pred = e->src;
224 struct loop *pred_loop = pred->loop_father;
225 unsigned pred_loop_depth = loop_depth (pred_loop);
226 bool pred_visited;
227
228 /* We should have met DEF_BB along the way. */
229 gcc_assert (pred != ENTRY_BLOCK_PTR_FOR_FN (cfun));
230
231 if (pred_loop_depth >= def_loop_depth)
232 {
233 if (pred_loop_depth > def_loop_depth)
234 pred_loop = superloop_at_depth (pred_loop, def_loop_depth);
235 /* If we've reached DEF_LOOP, our train ends here. */
236 if (pred_loop == def_loop)
237 continue;
238 }
239 else if (! flow_loop_nested_p (pred_loop, def_loop))
240 pred = find_sibling_superloop (pred_loop, def_loop)->header;
241
242 /* Add PRED to the LIVEIN set. PRED_VISITED is true if
243 we had already added PRED to LIVEIN before. */
244 pred_visited = !bitmap_set_bit (live_exits, pred->index);
245
246 /* If we have visited PRED before, don't add it to the worklist.
247 If BB dominates PRED, then we're probably looking at a loop.
248 We're only interested in looking up in the dominance tree
249 because DEF_BB dominates all the uses. */
250 if (pred_visited || dominated_by_p (CDI_DOMINATORS, pred, bb))
251 continue;
252
253 worklist.quick_push (pred);
254 }
255 }
256
257 def_loop_exits = BITMAP_ALLOC (&loop_renamer_obstack);
258 for (struct loop *loop = def_loop;
259 loop != current_loops->tree_root;
260 loop = loop_outer (loop))
261 bitmap_ior_into (def_loop_exits, loop_exits[loop->num]);
262 bitmap_and_into (live_exits, def_loop_exits);
263 BITMAP_FREE (def_loop_exits);
264}
265
266/* Add a loop-closing PHI for VAR in basic block EXIT. */
267
268static void
269add_exit_phi (basic_block exit, tree var)
270{
271 gphi *phi;
272 edge e;
273 edge_iterator ei;
274
275 /* Check that at least one of the edges entering the EXIT block exits
276 the loop, or a superloop of that loop, that VAR is defined in. */
277 if (flag_checking)
278 {
279 gimple *def_stmt = SSA_NAME_DEF_STMT (var);
280 basic_block def_bb = gimple_bb (def_stmt);
281 FOR_EACH_EDGE (e, ei, exit->preds)
282 {
283 struct loop *aloop = find_common_loop (def_bb->loop_father,
284 e->src->loop_father);
285 if (!flow_bb_inside_loop_p (aloop, e->dest))
286 break;
287 }
288 gcc_assert (e);
289 }
290
291 phi = create_phi_node (NULL_TREE, exit);
292 create_new_def_for (var, phi, gimple_phi_result_ptr (phi));
293 FOR_EACH_EDGE (e, ei, exit->preds)
294 add_phi_arg (phi, var, e, UNKNOWN_LOCATION);
295
296 if (dump_file && (dump_flags & TDF_DETAILS))
297 {
298 fprintf (dump_file, ";; Created LCSSA PHI: ");
299 print_gimple_stmt (dump_file, phi, 0, dump_flags);
300 }
301}
302
303/* Add exit phis for VAR that is used in LIVEIN.
304 Exits of the loops are stored in LOOP_EXITS. */
305
306static void
307add_exit_phis_var (tree var, bitmap use_blocks, bitmap *loop_exits)
308{
309 unsigned index;
310 bitmap_iterator bi;
311 basic_block def_bb = gimple_bb (SSA_NAME_DEF_STMT (var));
312 bitmap live_exits = BITMAP_ALLOC (&loop_renamer_obstack);
313
314 gcc_checking_assert (! bitmap_bit_p (use_blocks, def_bb->index));
315
316 compute_live_loop_exits (live_exits, use_blocks, loop_exits, def_bb);
317
318 EXECUTE_IF_SET_IN_BITMAP (live_exits, 0, index, bi)
319 {
320 add_exit_phi (BASIC_BLOCK_FOR_FN (cfun, index), var);
321 }
322
323 BITMAP_FREE (live_exits);
324}
325
326/* Add exit phis for the names marked in NAMES_TO_RENAME.
327 Exits of the loops are stored in EXITS. Sets of blocks where the ssa
328 names are used are stored in USE_BLOCKS. */
329
330static void
331add_exit_phis (bitmap names_to_rename, bitmap *use_blocks, bitmap *loop_exits)
332{
333 unsigned i;
334 bitmap_iterator bi;
335
336 EXECUTE_IF_SET_IN_BITMAP (names_to_rename, 0, i, bi)
337 {
338 add_exit_phis_var (ssa_name (i), use_blocks[i], loop_exits);
339 }
340}
341
342/* Fill the array of bitmaps LOOP_EXITS with all loop exit edge targets. */
343
344static void
345get_loops_exits (bitmap *loop_exits)
346{
347 struct loop *loop;
348 unsigned j;
349 edge e;
350
351 FOR_EACH_LOOP (loop, 0)
352 {
353 vec<edge> exit_edges = get_loop_exit_edges (loop);
354 loop_exits[loop->num] = BITMAP_ALLOC (&loop_renamer_obstack);
355 FOR_EACH_VEC_ELT (exit_edges, j, e)
356 bitmap_set_bit (loop_exits[loop->num], e->dest->index);
357 exit_edges.release ();
358 }
359}
360
361/* For USE in BB, if it is used outside of the loop it is defined in,
362 mark it for rewrite. Record basic block BB where it is used
363 to USE_BLOCKS. Record the ssa name index to NEED_PHIS bitmap.
364 Note that for USEs in phis, BB should be the src of the edge corresponding to
365 the use, rather than the bb containing the phi. */
366
367static void
368find_uses_to_rename_use (basic_block bb, tree use, bitmap *use_blocks,
369 bitmap need_phis)
370{
371 unsigned ver;
372 basic_block def_bb;
373 struct loop *def_loop;
374
375 if (TREE_CODE (use) != SSA_NAME)
376 return;
377
378 ver = SSA_NAME_VERSION (use);
379 def_bb = gimple_bb (SSA_NAME_DEF_STMT (use));
380 if (!def_bb)
381 return;
382 def_loop = def_bb->loop_father;
383
384 /* If the definition is not inside a loop, it is not interesting. */
385 if (!loop_outer (def_loop))
386 return;
387
388 /* If the use is not outside of the loop it is defined in, it is not
389 interesting. */
390 if (flow_bb_inside_loop_p (def_loop, bb))
391 return;
392
393 /* If we're seeing VER for the first time, we still have to allocate
394 a bitmap for its uses. */
395 if (bitmap_set_bit (need_phis, ver))
396 use_blocks[ver] = BITMAP_ALLOC (&loop_renamer_obstack);
397 bitmap_set_bit (use_blocks[ver], bb->index);
398}
399
400/* For uses matching USE_FLAGS in STMT, mark names that are used outside of the
401 loop they are defined to rewrite. Record the set of blocks in which the ssa
402 names are used to USE_BLOCKS, and the ssa names themselves to NEED_PHIS. */
403
404static void
405find_uses_to_rename_stmt (gimple *stmt, bitmap *use_blocks, bitmap need_phis,
406 int use_flags)
407{
408 ssa_op_iter iter;
409 tree var;
410 basic_block bb = gimple_bb (stmt);
411
412 if (is_gimple_debug (stmt))
413 return;
414
415 /* FOR_EACH_SSA_TREE_OPERAND iterator does not allows SSA_OP_VIRTUAL_USES
416 only. */
417 if (use_flags == SSA_OP_VIRTUAL_USES)
418 {
419 tree vuse = gimple_vuse (stmt);
420 if (vuse != NULL_TREE)
421 find_uses_to_rename_use (bb, gimple_vuse (stmt), use_blocks, need_phis);
422 }
423 else
424 FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, use_flags)
425 find_uses_to_rename_use (bb, var, use_blocks, need_phis);
426}
427
428/* Marks names matching USE_FLAGS that are used in BB and outside of the loop
429 they are defined in for rewrite. Records the set of blocks in which the ssa
430 names are used to USE_BLOCKS. Record the SSA names that will
431 need exit PHIs in NEED_PHIS. */
432
433static void
434find_uses_to_rename_bb (basic_block bb, bitmap *use_blocks, bitmap need_phis,
435 int use_flags)
436{
437 edge e;
438 edge_iterator ei;
439 bool do_virtuals = (use_flags & SSA_OP_VIRTUAL_USES) != 0;
440 bool do_nonvirtuals = (use_flags & SSA_OP_USE) != 0;
441
442 FOR_EACH_EDGE (e, ei, bb->succs)
443 for (gphi_iterator bsi = gsi_start_phis (e->dest); !gsi_end_p (bsi);
444 gsi_next (&bsi))
445 {
446 gphi *phi = bsi.phi ();
447 bool virtual_p = virtual_operand_p (gimple_phi_result (phi));
448 if ((virtual_p && do_virtuals)
449 || (!virtual_p && do_nonvirtuals))
450 find_uses_to_rename_use (bb, PHI_ARG_DEF_FROM_EDGE (phi, e),
451 use_blocks, need_phis);
452 }
453
454 for (gimple_stmt_iterator bsi = gsi_start_bb (bb); !gsi_end_p (bsi);
455 gsi_next (&bsi))
456 find_uses_to_rename_stmt (gsi_stmt (bsi), use_blocks, need_phis,
457 use_flags);
458}
459
460/* Marks names matching USE_FLAGS that are used outside of the loop they are
461 defined in for rewrite. Records the set of blocks in which the ssa names are
462 used to USE_BLOCKS. Record the SSA names that will need exit PHIs in
463 NEED_PHIS. If CHANGED_BBS is not NULL, scan only blocks in this set. */
464
465static void
466find_uses_to_rename (bitmap changed_bbs, bitmap *use_blocks, bitmap need_phis,
467 int use_flags)
468{
469 basic_block bb;
470 unsigned index;
471 bitmap_iterator bi;
472
473 if (changed_bbs)
474 EXECUTE_IF_SET_IN_BITMAP (changed_bbs, 0, index, bi)
475 {
476 bb = BASIC_BLOCK_FOR_FN (cfun, index);
477 if (bb)
478 find_uses_to_rename_bb (bb, use_blocks, need_phis, use_flags);
479 }
480 else
481 FOR_EACH_BB_FN (bb, cfun)
482 find_uses_to_rename_bb (bb, use_blocks, need_phis, use_flags);
483}
484
485/* Mark uses of DEF that are used outside of the loop they are defined in for
486 rewrite. Record the set of blocks in which the ssa names are used to
487 USE_BLOCKS. Record the SSA names that will need exit PHIs in NEED_PHIS. */
488
489static void
490find_uses_to_rename_def (tree def, bitmap *use_blocks, bitmap need_phis)
491{
492 gimple *use_stmt;
493 imm_use_iterator imm_iter;
494
495 FOR_EACH_IMM_USE_STMT (use_stmt, imm_iter, def)
496 {
497 if (is_gimple_debug (use_stmt))
498 continue;
499
500 basic_block use_bb = gimple_bb (use_stmt);
501
502 use_operand_p use_p;
503 FOR_EACH_IMM_USE_ON_STMT (use_p, imm_iter)
504 {
505 if (gimple_code (use_stmt) == GIMPLE_PHI)
506 {
507 edge e = gimple_phi_arg_edge (as_a <gphi *> (use_stmt),
508 PHI_ARG_INDEX_FROM_USE (use_p));
509 use_bb = e->src;
510 }
511 find_uses_to_rename_use (use_bb, USE_FROM_PTR (use_p), use_blocks,
512 need_phis);
513 }
514 }
515}
516
517/* Marks names matching USE_FLAGS that are defined in LOOP and used outside of
518 it for rewrite. Records the set of blocks in which the ssa names are used to
519 USE_BLOCKS. Record the SSA names that will need exit PHIs in NEED_PHIS. */
520
521static void
522find_uses_to_rename_in_loop (struct loop *loop, bitmap *use_blocks,
523 bitmap need_phis, int use_flags)
524{
525 bool do_virtuals = (use_flags & SSA_OP_VIRTUAL_USES) != 0;
526 bool do_nonvirtuals = (use_flags & SSA_OP_USE) != 0;
527 int def_flags = ((do_virtuals ? SSA_OP_VIRTUAL_DEFS : 0)
528 | (do_nonvirtuals ? SSA_OP_DEF : 0));
529
530
531 basic_block *bbs = get_loop_body (loop);
532
533 for (unsigned int i = 0; i < loop->num_nodes; i++)
534 {
535 basic_block bb = bbs[i];
536
537 for (gphi_iterator bsi = gsi_start_phis (bb); !gsi_end_p (bsi);
538 gsi_next (&bsi))
539 {
540 gphi *phi = bsi.phi ();
541 tree res = gimple_phi_result (phi);
542 bool virtual_p = virtual_operand_p (res);
543 if ((virtual_p && do_virtuals)
544 || (!virtual_p && do_nonvirtuals))
545 find_uses_to_rename_def (res, use_blocks, need_phis);
546 }
547
548 for (gimple_stmt_iterator bsi = gsi_start_bb (bb); !gsi_end_p (bsi);
549 gsi_next (&bsi))
550 {
551 gimple *stmt = gsi_stmt (bsi);
552 /* FOR_EACH_SSA_TREE_OPERAND iterator does not allows
553 SSA_OP_VIRTUAL_DEFS only. */
554 if (def_flags == SSA_OP_VIRTUAL_DEFS)
555 {
556 tree vdef = gimple_vdef (stmt);
557 if (vdef != NULL)
558 find_uses_to_rename_def (vdef, use_blocks, need_phis);
559 }
560 else
561 {
562 tree var;
563 ssa_op_iter iter;
564 FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, def_flags)
565 find_uses_to_rename_def (var, use_blocks, need_phis);
566 }
567 }
568 }
569
570 XDELETEVEC (bbs);
571}
572
573/* Rewrites the program into a loop closed ssa form -- i.e. inserts extra
574 phi nodes to ensure that no variable is used outside the loop it is
575 defined in.
576
577 This strengthening of the basic ssa form has several advantages:
578
579 1) Updating it during unrolling/peeling/versioning is trivial, since
580 we do not need to care about the uses outside of the loop.
581 The same applies to virtual operands which are also rewritten into
582 loop closed SSA form. Note that virtual operands are always live
583 until function exit.
584 2) The behavior of all uses of an induction variable is the same.
585 Without this, you need to distinguish the case when the variable
586 is used outside of the loop it is defined in, for example
587
588 for (i = 0; i < 100; i++)
589 {
590 for (j = 0; j < 100; j++)
591 {
592 k = i + j;
593 use1 (k);
594 }
595 use2 (k);
596 }
597
598 Looking from the outer loop with the normal SSA form, the first use of k
599 is not well-behaved, while the second one is an induction variable with
600 base 99 and step 1.
601
602 If LOOP is non-null, only rewrite uses that have defs in LOOP. Otherwise,
603 if CHANGED_BBS is not NULL, we look for uses outside loops only in the
604 basic blocks in this set.
605
606 USE_FLAGS allows us to specify whether we want virtual, non-virtual or
607 both variables rewritten.
608
609 UPDATE_FLAG is used in the call to update_ssa. See
610 TODO_update_ssa* for documentation. */
611
612void
613rewrite_into_loop_closed_ssa_1 (bitmap changed_bbs, unsigned update_flag,
614 int use_flags, struct loop *loop)
615{
616 bitmap *use_blocks;
617 bitmap names_to_rename;
618
619 loops_state_set (LOOP_CLOSED_SSA);
620 if (number_of_loops (cfun) <= 1)
621 return;
622
623 /* If the pass has caused the SSA form to be out-of-date, update it
624 now. */
625 if (update_flag != 0)
626 update_ssa (update_flag);
627 else if (flag_checking)
628 verify_ssa (true, true);
629
630 bitmap_obstack_initialize (&loop_renamer_obstack);
631
632 names_to_rename = BITMAP_ALLOC (&loop_renamer_obstack);
633
634 /* Uses of names to rename. We don't have to initialize this array,
635 because we know that we will only have entries for the SSA names
636 in NAMES_TO_RENAME. */
637 use_blocks = XNEWVEC (bitmap, num_ssa_names);
638
639 if (loop != NULL)
640 {
641 gcc_assert (changed_bbs == NULL);
642 find_uses_to_rename_in_loop (loop, use_blocks, names_to_rename,
643 use_flags);
644 }
645 else
646 {
647 gcc_assert (loop == NULL);
648 find_uses_to_rename (changed_bbs, use_blocks, names_to_rename, use_flags);
649 }
650
651 if (!bitmap_empty_p (names_to_rename))
652 {
653 /* An array of bitmaps where LOOP_EXITS[I] is the set of basic blocks
654 that are the destination of an edge exiting loop number I. */
655 bitmap *loop_exits = XNEWVEC (bitmap, number_of_loops (cfun));
656 get_loops_exits (loop_exits);
657
658 /* Add the PHI nodes on exits of the loops for the names we need to
659 rewrite. */
660 add_exit_phis (names_to_rename, use_blocks, loop_exits);
661
662 free (loop_exits);
663
664 /* Fix up all the names found to be used outside their original
665 loops. */
666 update_ssa (TODO_update_ssa);
667 }
668
669 bitmap_obstack_release (&loop_renamer_obstack);
670 free (use_blocks);
671}
672
673/* Rewrites the non-virtual defs and uses into a loop closed ssa form. If
674 CHANGED_BBS is not NULL, we look for uses outside loops only in the basic
675 blocks in this set. UPDATE_FLAG is used in the call to update_ssa. See
676 TODO_update_ssa* for documentation. */
677
678void
679rewrite_into_loop_closed_ssa (bitmap changed_bbs, unsigned update_flag)
680{
681 rewrite_into_loop_closed_ssa_1 (changed_bbs, update_flag, SSA_OP_USE, NULL);
682}
683
684/* Rewrites virtual defs and uses with def in LOOP into loop closed ssa
685 form. */
686
687void
688rewrite_virtuals_into_loop_closed_ssa (struct loop *loop)
689{
690 rewrite_into_loop_closed_ssa_1 (NULL, 0, SSA_OP_VIRTUAL_USES, loop);
691}
692
693/* Check invariants of the loop closed ssa form for the def in DEF_BB. */
694
695static void
696check_loop_closed_ssa_def (basic_block def_bb, tree def)
697{
698 use_operand_p use_p;
699 imm_use_iterator iterator;
700 FOR_EACH_IMM_USE_FAST (use_p, iterator, def)
701 {
702 if (is_gimple_debug (USE_STMT (use_p)))
703 continue;
704
705 basic_block use_bb = gimple_bb (USE_STMT (use_p));
706 if (is_a <gphi *> (USE_STMT (use_p)))
707 use_bb = EDGE_PRED (use_bb, PHI_ARG_INDEX_FROM_USE (use_p))->src;
708
709 gcc_assert (flow_bb_inside_loop_p (def_bb->loop_father, use_bb));
710 }
711}
712
713/* Checks invariants of loop closed ssa form in BB. */
714
715static void
716check_loop_closed_ssa_bb (basic_block bb)
717{
718 for (gphi_iterator bsi = gsi_start_phis (bb); !gsi_end_p (bsi);
719 gsi_next (&bsi))
720 {
721 gphi *phi = bsi.phi ();
722
723 if (!virtual_operand_p (PHI_RESULT (phi)))
724 check_loop_closed_ssa_def (bb, PHI_RESULT (phi));
725 }
726
727 for (gimple_stmt_iterator bsi = gsi_start_nondebug_bb (bb); !gsi_end_p (bsi);
728 gsi_next_nondebug (&bsi))
729 {
730 ssa_op_iter iter;
731 tree var;
732 gimple *stmt = gsi_stmt (bsi);
733
734 FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_DEF)
735 check_loop_closed_ssa_def (bb, var);
736 }
737}
738
739/* Checks that invariants of the loop closed ssa form are preserved.
740 Call verify_ssa when VERIFY_SSA_P is true. Note all loops are checked
741 if LOOP is NULL, otherwise, only LOOP is checked. */
742
743DEBUG_FUNCTION void
744verify_loop_closed_ssa (bool verify_ssa_p, struct loop *loop)
745{
746 if (number_of_loops (cfun) <= 1)
747 return;
748
749 if (verify_ssa_p)
750 verify_ssa (false, true);
751
752 timevar_push (TV_VERIFY_LOOP_CLOSED);
753
754 if (loop == NULL)
755 {
756 basic_block bb;
757
758 FOR_EACH_BB_FN (bb, cfun)
759 if (bb->loop_father && bb->loop_father->num > 0)
760 check_loop_closed_ssa_bb (bb);
761 }
762 else
763 {
764 basic_block *bbs = get_loop_body (loop);
765
766 for (unsigned i = 0; i < loop->num_nodes; ++i)
767 check_loop_closed_ssa_bb (bbs[i]);
768
769 free (bbs);
770 }
771
772 timevar_pop (TV_VERIFY_LOOP_CLOSED);
773}
774
775/* Split loop exit edge EXIT. The things are a bit complicated by a need to
776 preserve the loop closed ssa form. The newly created block is returned. */
777
778basic_block
779split_loop_exit_edge (edge exit)
780{
781 basic_block dest = exit->dest;
782 basic_block bb = split_edge (exit);
783 gphi *phi, *new_phi;
784 tree new_name, name;
785 use_operand_p op_p;
786 gphi_iterator psi;
787 source_location locus;
788
789 for (psi = gsi_start_phis (dest); !gsi_end_p (psi); gsi_next (&psi))
790 {
791 phi = psi.phi ();
792 op_p = PHI_ARG_DEF_PTR_FROM_EDGE (phi, single_succ_edge (bb));
793 locus = gimple_phi_arg_location_from_edge (phi, single_succ_edge (bb));
794
795 name = USE_FROM_PTR (op_p);
796
797 /* If the argument of the PHI node is a constant, we do not need
798 to keep it inside loop. */
799 if (TREE_CODE (name) != SSA_NAME)
800 continue;
801
802 /* Otherwise create an auxiliary phi node that will copy the value
803 of the SSA name out of the loop. */
804 new_name = duplicate_ssa_name (name, NULL);
805 new_phi = create_phi_node (new_name, bb);
806 add_phi_arg (new_phi, name, exit, locus);
807 SET_USE (op_p, new_name);
808 }
809
810 return bb;
811}
812
813/* Returns the basic block in that statements should be emitted for induction
814 variables incremented at the end of the LOOP. */
815
816basic_block
817ip_end_pos (struct loop *loop)
818{
819 return loop->latch;
820}
821
822/* Returns the basic block in that statements should be emitted for induction
823 variables incremented just before exit condition of a LOOP. */
824
825basic_block
826ip_normal_pos (struct loop *loop)
827{
828 gimple *last;
829 basic_block bb;
830 edge exit;
831
832 if (!single_pred_p (loop->latch))
833 return NULL;
834
835 bb = single_pred (loop->latch);
836 last = last_stmt (bb);
837 if (!last
838 || gimple_code (last) != GIMPLE_COND)
839 return NULL;
840
841 exit = EDGE_SUCC (bb, 0);
842 if (exit->dest == loop->latch)
843 exit = EDGE_SUCC (bb, 1);
844
845 if (flow_bb_inside_loop_p (loop, exit->dest))
846 return NULL;
847
848 return bb;
849}
850
851/* Stores the standard position for induction variable increment in LOOP
852 (just before the exit condition if it is available and latch block is empty,
853 end of the latch block otherwise) to BSI. INSERT_AFTER is set to true if
854 the increment should be inserted after *BSI. */
855
856void
857standard_iv_increment_position (struct loop *loop, gimple_stmt_iterator *bsi,
858 bool *insert_after)
859{
860 basic_block bb = ip_normal_pos (loop), latch = ip_end_pos (loop);
861 gimple *last = last_stmt (latch);
862
863 if (!bb
864 || (last && gimple_code (last) != GIMPLE_LABEL))
865 {
866 *bsi = gsi_last_bb (latch);
867 *insert_after = true;
868 }
869 else
870 {
871 *bsi = gsi_last_bb (bb);
872 *insert_after = false;
873 }
874}
875
876/* Copies phi node arguments for duplicated blocks. The index of the first
877 duplicated block is FIRST_NEW_BLOCK. */
878
879static void
880copy_phi_node_args (unsigned first_new_block)
881{
882 unsigned i;
883
884 for (i = first_new_block; i < (unsigned) last_basic_block_for_fn (cfun); i++)
885 BASIC_BLOCK_FOR_FN (cfun, i)->flags |= BB_DUPLICATED;
886
887 for (i = first_new_block; i < (unsigned) last_basic_block_for_fn (cfun); i++)
888 add_phi_args_after_copy_bb (BASIC_BLOCK_FOR_FN (cfun, i));
889
890 for (i = first_new_block; i < (unsigned) last_basic_block_for_fn (cfun); i++)
891 BASIC_BLOCK_FOR_FN (cfun, i)->flags &= ~BB_DUPLICATED;
892}
893
894
895/* The same as cfgloopmanip.c:duplicate_loop_to_header_edge, but also
896 updates the PHI nodes at start of the copied region. In order to
897 achieve this, only loops whose exits all lead to the same location
898 are handled.
899
900 Notice that we do not completely update the SSA web after
901 duplication. The caller is responsible for calling update_ssa
902 after the loop has been duplicated. */
903
904bool
905gimple_duplicate_loop_to_header_edge (struct loop *loop, edge e,
906 unsigned int ndupl, sbitmap wont_exit,
907 edge orig, vec<edge> *to_remove,
908 int flags)
909{
910 unsigned first_new_block;
911
912 if (!loops_state_satisfies_p (LOOPS_HAVE_SIMPLE_LATCHES))
913 return false;
914 if (!loops_state_satisfies_p (LOOPS_HAVE_PREHEADERS))
915 return false;
916
917 first_new_block = last_basic_block_for_fn (cfun);
918 if (!duplicate_loop_to_header_edge (loop, e, ndupl, wont_exit,
919 orig, to_remove, flags))
920 return false;
921
922 /* Readd the removed phi args for e. */
923 flush_pending_stmts (e);
924
925 /* Copy the phi node arguments. */
926 copy_phi_node_args (first_new_block);
927
928 scev_reset ();
929
930 return true;
931}
932
933/* Returns true if we can unroll LOOP FACTOR times. Number
934 of iterations of the loop is returned in NITER. */
935
936bool
937can_unroll_loop_p (struct loop *loop, unsigned factor,
938 struct tree_niter_desc *niter)
939{
940 edge exit;
941
942 /* Check whether unrolling is possible. We only want to unroll loops
943 for that we are able to determine number of iterations. We also
944 want to split the extra iterations of the loop from its end,
945 therefore we require that the loop has precisely one
946 exit. */
947
948 exit = single_dom_exit (loop);
949 if (!exit)
950 return false;
951
952 if (!number_of_iterations_exit (loop, exit, niter, false)
953 || niter->cmp == ERROR_MARK
954 /* Scalar evolutions analysis might have copy propagated
955 the abnormal ssa names into these expressions, hence
956 emitting the computations based on them during loop
957 unrolling might create overlapping life ranges for
958 them, and failures in out-of-ssa. */
959 || contains_abnormal_ssa_name_p (niter->may_be_zero)
960 || contains_abnormal_ssa_name_p (niter->control.base)
961 || contains_abnormal_ssa_name_p (niter->control.step)
962 || contains_abnormal_ssa_name_p (niter->bound))
963 return false;
964
965 /* And of course, we must be able to duplicate the loop. */
966 if (!can_duplicate_loop_p (loop))
967 return false;
968
969 /* The final loop should be small enough. */
970 if (tree_num_loop_insns (loop, &eni_size_weights) * factor
971 > (unsigned) PARAM_VALUE (PARAM_MAX_UNROLLED_INSNS))
972 return false;
973
974 return true;
975}
976
977/* Determines the conditions that control execution of LOOP unrolled FACTOR
978 times. DESC is number of iterations of LOOP. ENTER_COND is set to
979 condition that must be true if the main loop can be entered.
980 EXIT_BASE, EXIT_STEP, EXIT_CMP and EXIT_BOUND are set to values describing
981 how the exit from the unrolled loop should be controlled. */
982
983static void
984determine_exit_conditions (struct loop *loop, struct tree_niter_desc *desc,
985 unsigned factor, tree *enter_cond,
986 tree *exit_base, tree *exit_step,
987 enum tree_code *exit_cmp, tree *exit_bound)
988{
989 gimple_seq stmts;
990 tree base = desc->control.base;
991 tree step = desc->control.step;
992 tree bound = desc->bound;
993 tree type = TREE_TYPE (step);
994 tree bigstep, delta;
995 tree min = lower_bound_in_type (type, type);
996 tree max = upper_bound_in_type (type, type);
997 enum tree_code cmp = desc->cmp;
998 tree cond = boolean_true_node, assum;
999
1000 /* For pointers, do the arithmetics in the type of step. */
1001 base = fold_convert (type, base);
1002 bound = fold_convert (type, bound);
1003
1004 *enter_cond = boolean_false_node;
1005 *exit_base = NULL_TREE;
1006 *exit_step = NULL_TREE;
1007 *exit_cmp = ERROR_MARK;
1008 *exit_bound = NULL_TREE;
1009 gcc_assert (cmp != ERROR_MARK);
1010
1011 /* We only need to be correct when we answer question
1012 "Do at least FACTOR more iterations remain?" in the unrolled loop.
1013 Thus, transforming BASE + STEP * i <> BOUND to
1014 BASE + STEP * i < BOUND is ok. */
1015 if (cmp == NE_EXPR)
1016 {
1017 if (tree_int_cst_sign_bit (step))
1018 cmp = GT_EXPR;
1019 else
1020 cmp = LT_EXPR;
1021 }
1022 else if (cmp == LT_EXPR)
1023 {
1024 gcc_assert (!tree_int_cst_sign_bit (step));
1025 }
1026 else if (cmp == GT_EXPR)
1027 {
1028 gcc_assert (tree_int_cst_sign_bit (step));
1029 }
1030 else
1031 gcc_unreachable ();
1032
1033 /* The main body of the loop may be entered iff:
1034
1035 1) desc->may_be_zero is false.
1036 2) it is possible to check that there are at least FACTOR iterations
1037 of the loop, i.e., BOUND - step * FACTOR does not overflow.
1038 3) # of iterations is at least FACTOR */
1039
1040 if (!integer_zerop (desc->may_be_zero))
1041 cond = fold_build2 (TRUTH_AND_EXPR, boolean_type_node,
1042 invert_truthvalue (desc->may_be_zero),
1043 cond);
1044
1045 bigstep = fold_build2 (MULT_EXPR, type, step,
1046 build_int_cst_type (type, factor));
1047 delta = fold_build2 (MINUS_EXPR, type, bigstep, step);
1048 if (cmp == LT_EXPR)
1049 assum = fold_build2 (GE_EXPR, boolean_type_node,
1050 bound,
1051 fold_build2 (PLUS_EXPR, type, min, delta));
1052 else
1053 assum = fold_build2 (LE_EXPR, boolean_type_node,
1054 bound,
1055 fold_build2 (PLUS_EXPR, type, max, delta));
1056 cond = fold_build2 (TRUTH_AND_EXPR, boolean_type_node, assum, cond);
1057
1058 bound = fold_build2 (MINUS_EXPR, type, bound, delta);
1059 assum = fold_build2 (cmp, boolean_type_node, base, bound);
1060 cond = fold_build2 (TRUTH_AND_EXPR, boolean_type_node, assum, cond);
1061
1062 cond = force_gimple_operand (unshare_expr (cond), &stmts, false, NULL_TREE);
1063 if (stmts)
1064 gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts);
1065 /* cond now may be a gimple comparison, which would be OK, but also any
1066 other gimple rhs (say a && b). In this case we need to force it to
1067 operand. */
1068 if (!is_gimple_condexpr (cond))
1069 {
1070 cond = force_gimple_operand (cond, &stmts, true, NULL_TREE);
1071 if (stmts)
1072 gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts);
1073 }
1074 *enter_cond = cond;
1075
1076 base = force_gimple_operand (unshare_expr (base), &stmts, true, NULL_TREE);
1077 if (stmts)
1078 gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts);
1079 bound = force_gimple_operand (unshare_expr (bound), &stmts, true, NULL_TREE);
1080 if (stmts)
1081 gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts);
1082
1083 *exit_base = base;
1084 *exit_step = bigstep;
1085 *exit_cmp = cmp;
1086 *exit_bound = bound;
1087}
1088
1089/* Scales the frequencies of all basic blocks in LOOP that are strictly
1090 dominated by BB by NUM/DEN. */
1091
1092static void
1093scale_dominated_blocks_in_loop (struct loop *loop, basic_block bb,
1094 profile_count num, profile_count den)
1095{
1096 basic_block son;
1097
1098 if (!den.nonzero_p () && !(num == profile_count::zero ()))
1099 return;
1100
1101 for (son = first_dom_son (CDI_DOMINATORS, bb);
1102 son;
1103 son = next_dom_son (CDI_DOMINATORS, son))
1104 {
1105 if (!flow_bb_inside_loop_p (loop, son))
1106 continue;
1107 scale_bbs_frequencies_profile_count (&son, 1, num, den);
1108 scale_dominated_blocks_in_loop (loop, son, num, den);
1109 }
1110}
1111
1112/* Return estimated niter for LOOP after unrolling by FACTOR times. */
1113
1114gcov_type
1115niter_for_unrolled_loop (struct loop *loop, unsigned factor)
1116{
1117 gcc_assert (factor != 0);
1118 bool profile_p = false;
1119 gcov_type est_niter = expected_loop_iterations_unbounded (loop, &profile_p);
1120 /* Note that this is really CEIL (est_niter + 1, factor) - 1, where the
1121 "+ 1" converts latch iterations to loop iterations and the "- 1"
1122 converts back. */
1123 gcov_type new_est_niter = est_niter / factor;
1124
1125 if (est_niter == -1)
1126 return -1;
1127
1128 /* Without profile feedback, loops for which we do not know a better estimate
1129 are assumed to roll 10 times. When we unroll such loop, it appears to
1130 roll too little, and it may even seem to be cold. To avoid this, we
1131 ensure that the created loop appears to roll at least 5 times (but at
1132 most as many times as before unrolling). Don't do adjustment if profile
1133 feedback is present. */
1134 if (new_est_niter < 5 && !profile_p)
1135 {
1136 if (est_niter < 5)
1137 new_est_niter = est_niter;
1138 else
1139 new_est_niter = 5;
1140 }
1141
1142 if (loop->any_upper_bound)
1143 {
1144 /* As above, this is really CEIL (upper_bound + 1, factor) - 1. */
1145 widest_int bound = wi::udiv_floor (loop->nb_iterations_upper_bound,
1146 factor);
1147 if (wi::ltu_p (bound, new_est_niter))
1148 new_est_niter = bound.to_uhwi ();
1149 }
1150
1151 return new_est_niter;
1152}
1153
1154/* Unroll LOOP FACTOR times. DESC describes number of iterations of LOOP.
1155 EXIT is the exit of the loop to that DESC corresponds.
1156
1157 If N is number of iterations of the loop and MAY_BE_ZERO is the condition
1158 under that loop exits in the first iteration even if N != 0,
1159
1160 while (1)
1161 {
1162 x = phi (init, next);
1163
1164 pre;
1165 if (st)
1166 break;
1167 post;
1168 }
1169
1170 becomes (with possibly the exit conditions formulated a bit differently,
1171 avoiding the need to create a new iv):
1172
1173 if (MAY_BE_ZERO || N < FACTOR)
1174 goto rest;
1175
1176 do
1177 {
1178 x = phi (init, next);
1179
1180 pre;
1181 post;
1182 pre;
1183 post;
1184 ...
1185 pre;
1186 post;
1187 N -= FACTOR;
1188
1189 } while (N >= FACTOR);
1190
1191 rest:
1192 init' = phi (init, x);
1193
1194 while (1)
1195 {
1196 x = phi (init', next);
1197
1198 pre;
1199 if (st)
1200 break;
1201 post;
1202 }
1203
1204 Before the loop is unrolled, TRANSFORM is called for it (only for the
1205 unrolled loop, but not for its versioned copy). DATA is passed to
1206 TRANSFORM. */
1207
1208/* Probability in % that the unrolled loop is entered. Just a guess. */
1209#define PROB_UNROLLED_LOOP_ENTERED 90
1210
1211void
1212tree_transform_and_unroll_loop (struct loop *loop, unsigned factor,
1213 edge exit, struct tree_niter_desc *desc,
1214 transform_callback transform,
1215 void *data)
1216{
1217 gcond *exit_if;
1218 tree ctr_before, ctr_after;
1219 tree enter_main_cond, exit_base, exit_step, exit_bound;
1220 enum tree_code exit_cmp;
1221 gphi *phi_old_loop, *phi_new_loop, *phi_rest;
1222 gphi_iterator psi_old_loop, psi_new_loop;
1223 tree init, next, new_init;
1224 struct loop *new_loop;
1225 basic_block rest, exit_bb;
1226 edge old_entry, new_entry, old_latch, precond_edge, new_exit;
1227 edge new_nonexit, e;
1228 gimple_stmt_iterator bsi;
1229 use_operand_p op;
1230 bool ok;
1231 unsigned i;
1232 profile_probability prob, prob_entry, scale_unrolled;
1233 profile_count freq_e, freq_h;
1234 gcov_type new_est_niter = niter_for_unrolled_loop (loop, factor);
1235 unsigned irr = loop_preheader_edge (loop)->flags & EDGE_IRREDUCIBLE_LOOP;
1236 auto_vec<edge> to_remove;
1237
1238 determine_exit_conditions (loop, desc, factor,
1239 &enter_main_cond, &exit_base, &exit_step,
1240 &exit_cmp, &exit_bound);
1241
1242 /* Let us assume that the unrolled loop is quite likely to be entered. */
1243 if (integer_nonzerop (enter_main_cond))
1244 prob_entry = profile_probability::always ();
1245 else
1246 prob_entry = profile_probability::guessed_always ()
1247 .apply_scale (PROB_UNROLLED_LOOP_ENTERED, 100);
1248
1249 /* The values for scales should keep profile consistent, and somewhat close
1250 to correct.
1251
1252 TODO: The current value of SCALE_REST makes it appear that the loop that
1253 is created by splitting the remaining iterations of the unrolled loop is
1254 executed the same number of times as the original loop, and with the same
1255 frequencies, which is obviously wrong. This does not appear to cause
1256 problems, so we do not bother with fixing it for now. To make the profile
1257 correct, we would need to change the probability of the exit edge of the
1258 loop, and recompute the distribution of frequencies in its body because
1259 of this change (scale the frequencies of blocks before and after the exit
1260 by appropriate factors). */
1261 scale_unrolled = prob_entry;
1262
1263 new_loop = loop_version (loop, enter_main_cond, NULL, prob_entry,
1264 prob_entry.invert (), scale_unrolled,
1265 profile_probability::guessed_always (),
1266 true);
1267 gcc_assert (new_loop != NULL);
1268 update_ssa (TODO_update_ssa);
1269
1270 /* Prepare the cfg and update the phi nodes. Move the loop exit to the
1271 loop latch (and make its condition dummy, for the moment). */
1272 rest = loop_preheader_edge (new_loop)->src;
1273 precond_edge = single_pred_edge (rest);
1274 split_edge (loop_latch_edge (loop));
1275 exit_bb = single_pred (loop->latch);
1276
1277 /* Since the exit edge will be removed, the frequency of all the blocks
1278 in the loop that are dominated by it must be scaled by
1279 1 / (1 - exit->probability). */
1280 if (exit->probability.initialized_p ())
1281 scale_dominated_blocks_in_loop (loop, exit->src,
1282 /* We are scaling up here so probability
1283 does not fit. */
1284 loop->header->count,
1285 loop->header->count
1286 - loop->header->count.apply_probability
1287 (exit->probability));
1288
1289 bsi = gsi_last_bb (exit_bb);
1290 exit_if = gimple_build_cond (EQ_EXPR, integer_zero_node,
1291 integer_zero_node,
1292 NULL_TREE, NULL_TREE);
1293
1294 gsi_insert_after (&bsi, exit_if, GSI_NEW_STMT);
1295 new_exit = make_edge (exit_bb, rest, EDGE_FALSE_VALUE | irr);
1296 rescan_loop_exit (new_exit, true, false);
1297
1298 /* Set the probability of new exit to the same of the old one. Fix
1299 the frequency of the latch block, by scaling it back by
1300 1 - exit->probability. */
1301 new_exit->probability = exit->probability;
1302 new_nonexit = single_pred_edge (loop->latch);
1303 new_nonexit->probability = exit->probability.invert ();
1304 new_nonexit->flags = EDGE_TRUE_VALUE;
1305 if (new_nonexit->probability.initialized_p ())
1306 scale_bbs_frequencies (&loop->latch, 1, new_nonexit->probability);
1307
1308 old_entry = loop_preheader_edge (loop);
1309 new_entry = loop_preheader_edge (new_loop);
1310 old_latch = loop_latch_edge (loop);
1311 for (psi_old_loop = gsi_start_phis (loop->header),
1312 psi_new_loop = gsi_start_phis (new_loop->header);
1313 !gsi_end_p (psi_old_loop);
1314 gsi_next (&psi_old_loop), gsi_next (&psi_new_loop))
1315 {
1316 phi_old_loop = psi_old_loop.phi ();
1317 phi_new_loop = psi_new_loop.phi ();
1318
1319 init = PHI_ARG_DEF_FROM_EDGE (phi_old_loop, old_entry);
1320 op = PHI_ARG_DEF_PTR_FROM_EDGE (phi_new_loop, new_entry);
1321 gcc_assert (operand_equal_for_phi_arg_p (init, USE_FROM_PTR (op)));
1322 next = PHI_ARG_DEF_FROM_EDGE (phi_old_loop, old_latch);
1323
1324 /* Prefer using original variable as a base for the new ssa name.
1325 This is necessary for virtual ops, and useful in order to avoid
1326 losing debug info for real ops. */
1327 if (TREE_CODE (next) == SSA_NAME
1328 && useless_type_conversion_p (TREE_TYPE (next),
1329 TREE_TYPE (init)))
1330 new_init = copy_ssa_name (next);
1331 else if (TREE_CODE (init) == SSA_NAME
1332 && useless_type_conversion_p (TREE_TYPE (init),
1333 TREE_TYPE (next)))
1334 new_init = copy_ssa_name (init);
1335 else if (useless_type_conversion_p (TREE_TYPE (next), TREE_TYPE (init)))
1336 new_init = make_temp_ssa_name (TREE_TYPE (next), NULL, "unrinittmp");
1337 else
1338 new_init = make_temp_ssa_name (TREE_TYPE (init), NULL, "unrinittmp");
1339
1340 phi_rest = create_phi_node (new_init, rest);
1341
1342 add_phi_arg (phi_rest, init, precond_edge, UNKNOWN_LOCATION);
1343 add_phi_arg (phi_rest, next, new_exit, UNKNOWN_LOCATION);
1344 SET_USE (op, new_init);
1345 }
1346
1347 remove_path (exit);
1348
1349 /* Transform the loop. */
1350 if (transform)
1351 (*transform) (loop, data);
1352
1353 /* Unroll the loop and remove the exits in all iterations except for the
1354 last one. */
1355 auto_sbitmap wont_exit (factor);
1356 bitmap_ones (wont_exit);
1357 bitmap_clear_bit (wont_exit, factor - 1);
1358
1359 ok = gimple_duplicate_loop_to_header_edge
1360 (loop, loop_latch_edge (loop), factor - 1,
1361 wont_exit, new_exit, &to_remove, DLTHE_FLAG_UPDATE_FREQ);
1362 gcc_assert (ok);
1363
1364 FOR_EACH_VEC_ELT (to_remove, i, e)
1365 {
1366 ok = remove_path (e);
1367 gcc_assert (ok);
1368 }
1369 update_ssa (TODO_update_ssa);
1370
1371 /* Ensure that the frequencies in the loop match the new estimated
1372 number of iterations, and change the probability of the new
1373 exit edge. */
1374
1375 freq_h = loop->header->count;
1376 freq_e = (loop_preheader_edge (loop))->count ();
1377 if (freq_h.nonzero_p ())
1378 {
1379 /* Avoid dropping loop body profile counter to 0 because of zero count
1380 in loop's preheader. */
1381 freq_e = freq_e.force_nonzero ();
1382 scale_loop_frequencies (loop, freq_e.probability_in (freq_h));
1383 }
1384
1385 exit_bb = single_pred (loop->latch);
1386 new_exit = find_edge (exit_bb, rest);
1387 new_exit->probability = profile_probability::always ()
1388 .apply_scale (1, new_est_niter + 1);
1389
1390 rest->count += new_exit->count ();
1391
1392 new_nonexit = single_pred_edge (loop->latch);
1393 prob = new_nonexit->probability;
1394 new_nonexit->probability = new_exit->probability.invert ();
1395 prob = new_nonexit->probability / prob;
1396 if (prob.initialized_p ())
1397 scale_bbs_frequencies (&loop->latch, 1, prob);
1398
1399 /* Finally create the new counter for number of iterations and add the new
1400 exit instruction. */
1401 bsi = gsi_last_nondebug_bb (exit_bb);
1402 exit_if = as_a <gcond *> (gsi_stmt (bsi));
1403 create_iv (exit_base, exit_step, NULL_TREE, loop,
1404 &bsi, false, &ctr_before, &ctr_after);
1405 gimple_cond_set_code (exit_if, exit_cmp);
1406 gimple_cond_set_lhs (exit_if, ctr_after);
1407 gimple_cond_set_rhs (exit_if, exit_bound);
1408 update_stmt (exit_if);
1409
1410 checking_verify_flow_info ();
1411 checking_verify_loop_structure ();
1412 checking_verify_loop_closed_ssa (true, loop);
1413 checking_verify_loop_closed_ssa (true, new_loop);
1414}
1415
1416/* Wrapper over tree_transform_and_unroll_loop for case we do not
1417 want to transform the loop before unrolling. The meaning
1418 of the arguments is the same as for tree_transform_and_unroll_loop. */
1419
1420void
1421tree_unroll_loop (struct loop *loop, unsigned factor,
1422 edge exit, struct tree_niter_desc *desc)
1423{
1424 tree_transform_and_unroll_loop (loop, factor, exit, desc,
1425 NULL, NULL);
1426}
1427
1428/* Rewrite the phi node at position PSI in function of the main
1429 induction variable MAIN_IV and insert the generated code at GSI. */
1430
1431static void
1432rewrite_phi_with_iv (loop_p loop,
1433 gphi_iterator *psi,
1434 gimple_stmt_iterator *gsi,
1435 tree main_iv)
1436{
1437 affine_iv iv;
1438 gassign *stmt;
1439 gphi *phi = psi->phi ();
1440 tree atype, mtype, val, res = PHI_RESULT (phi);
1441
1442 if (virtual_operand_p (res) || res == main_iv)
1443 {
1444 gsi_next (psi);
1445 return;
1446 }
1447
1448 if (!simple_iv (loop, loop, res, &iv, true))
1449 {
1450 gsi_next (psi);
1451 return;
1452 }
1453
1454 remove_phi_node (psi, false);
1455
1456 atype = TREE_TYPE (res);
1457 mtype = POINTER_TYPE_P (atype) ? sizetype : atype;
1458 val = fold_build2 (MULT_EXPR, mtype, unshare_expr (iv.step),
1459 fold_convert (mtype, main_iv));
1460 val = fold_build2 (POINTER_TYPE_P (atype)
1461 ? POINTER_PLUS_EXPR : PLUS_EXPR,
1462 atype, unshare_expr (iv.base), val);
1463 val = force_gimple_operand_gsi (gsi, val, false, NULL_TREE, true,
1464 GSI_SAME_STMT);
1465 stmt = gimple_build_assign (res, val);
1466 gsi_insert_before (gsi, stmt, GSI_SAME_STMT);
1467}
1468
1469/* Rewrite all the phi nodes of LOOP in function of the main induction
1470 variable MAIN_IV. */
1471
1472static void
1473rewrite_all_phi_nodes_with_iv (loop_p loop, tree main_iv)
1474{
1475 unsigned i;
1476 basic_block *bbs = get_loop_body_in_dom_order (loop);
1477 gphi_iterator psi;
1478
1479 for (i = 0; i < loop->num_nodes; i++)
1480 {
1481 basic_block bb = bbs[i];
1482 gimple_stmt_iterator gsi = gsi_after_labels (bb);
1483
1484 if (bb->loop_father != loop)
1485 continue;
1486
1487 for (psi = gsi_start_phis (bb); !gsi_end_p (psi); )
1488 rewrite_phi_with_iv (loop, &psi, &gsi, main_iv);
1489 }
1490
1491 free (bbs);
1492}
1493
1494/* Bases all the induction variables in LOOP on a single induction variable
1495 (with base 0 and step 1), whose final value is compared with *NIT. When the
1496 IV type precision has to be larger than *NIT type precision, *NIT is
1497 converted to the larger type, the conversion code is inserted before the
1498 loop, and *NIT is updated to the new definition. When BUMP_IN_LATCH is true,
1499 the induction variable is incremented in the loop latch, otherwise it is
1500 incremented in the loop header. Return the induction variable that was
1501 created. */
1502
1503tree
1504canonicalize_loop_ivs (struct loop *loop, tree *nit, bool bump_in_latch)
1505{
1506 unsigned precision = TYPE_PRECISION (TREE_TYPE (*nit));
1507 unsigned original_precision = precision;
1508 tree type, var_before;
1509 gimple_stmt_iterator gsi;
1510 gphi_iterator psi;
1511 gcond *stmt;
1512 edge exit = single_dom_exit (loop);
1513 gimple_seq stmts;
1514 bool unsigned_p = false;
1515
1516 for (psi = gsi_start_phis (loop->header);
1517 !gsi_end_p (psi); gsi_next (&psi))
1518 {
1519 gphi *phi = psi.phi ();
1520 tree res = PHI_RESULT (phi);
1521 bool uns;
1522
1523 type = TREE_TYPE (res);
1524 if (virtual_operand_p (res)
1525 || (!INTEGRAL_TYPE_P (type)
1526 && !POINTER_TYPE_P (type))
1527 || TYPE_PRECISION (type) < precision)
1528 continue;
1529
1530 uns = POINTER_TYPE_P (type) | TYPE_UNSIGNED (type);
1531
1532 if (TYPE_PRECISION (type) > precision)
1533 unsigned_p = uns;
1534 else
1535 unsigned_p |= uns;
1536
1537 precision = TYPE_PRECISION (type);
1538 }
1539
1540 scalar_int_mode mode = smallest_int_mode_for_size (precision);
1541 precision = GET_MODE_PRECISION (mode);
1542 type = build_nonstandard_integer_type (precision, unsigned_p);
1543
1544 if (original_precision != precision)
1545 {
1546 *nit = fold_convert (type, *nit);
1547 *nit = force_gimple_operand (*nit, &stmts, true, NULL_TREE);
1548 if (stmts)
1549 gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts);
1550 }
1551
1552 if (bump_in_latch)
1553 gsi = gsi_last_bb (loop->latch);
1554 else
1555 gsi = gsi_last_nondebug_bb (loop->header);
1556 create_iv (build_int_cst_type (type, 0), build_int_cst (type, 1), NULL_TREE,
1557 loop, &gsi, bump_in_latch, &var_before, NULL);
1558
1559 rewrite_all_phi_nodes_with_iv (loop, var_before);
1560
1561 stmt = as_a <gcond *> (last_stmt (exit->src));
1562 /* Make the loop exit if the control condition is not satisfied. */
1563 if (exit->flags & EDGE_TRUE_VALUE)
1564 {
1565 edge te, fe;
1566
1567 extract_true_false_edges_from_block (exit->src, &te, &fe);
1568 te->flags = EDGE_FALSE_VALUE;
1569 fe->flags = EDGE_TRUE_VALUE;
1570 }
1571 gimple_cond_set_code (stmt, LT_EXPR);
1572 gimple_cond_set_lhs (stmt, var_before);
1573 gimple_cond_set_rhs (stmt, *nit);
1574 update_stmt (stmt);
1575
1576 return var_before;
1577}
1578