1 /* Natural loop discovery code for GNU compiler.
2 Copyright (C) 2000, 2001, 2003, 2004, 2005, 2006, 2007
3 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
24 #include "coretypes.h"
27 #include "hard-reg-set.h"
30 #include "basic-block.h"
35 #include "tree-flow.h"
36 #include "pointer-set.h"
40 static void flow_loops_cfg_dump (FILE *);
42 /* Dump loop related CFG information. */
45 flow_loops_cfg_dump (FILE *file)
57 fprintf (file, ";; %d succs { ", bb->index);
58 FOR_EACH_EDGE (succ, ei, bb->succs)
59 fprintf (file, "%d ", succ->dest->index);
60 fprintf (file, "}\n");
64 /* Return nonzero if the nodes of LOOP are a subset of OUTER. */
67 flow_loop_nested_p (const struct loop *outer, const struct loop *loop)
69 unsigned odepth = loop_depth (outer);
71 return (loop_depth (loop) > odepth
72 && VEC_index (loop_p, loop->superloops, odepth) == outer);
75 /* Returns the loop such that LOOP is nested DEPTH (indexed from zero)
79 superloop_at_depth (struct loop *loop, unsigned depth)
81 unsigned ldepth = loop_depth (loop);
83 gcc_assert (depth <= ldepth);
88 return VEC_index (loop_p, loop->superloops, depth);
91 /* Returns the list of the latch edges of LOOP. */
93 static VEC (edge, heap) *
94 get_loop_latch_edges (const struct loop *loop)
98 VEC (edge, heap) *ret = NULL;
100 FOR_EACH_EDGE (e, ei, loop->header->preds)
102 if (dominated_by_p (CDI_DOMINATORS, e->src, loop->header))
103 VEC_safe_push (edge, heap, ret, e);
109 /* Dump the loop information specified by LOOP to the stream FILE
110 using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
113 flow_loop_dump (const struct loop *loop, FILE *file,
114 void (*loop_dump_aux) (const struct loop *, FILE *, int),
119 VEC (edge, heap) *latches;
122 if (! loop || ! loop->header)
125 fprintf (file, ";;\n;; Loop %d\n", loop->num);
127 fprintf (file, ";; header %d, ", loop->header->index);
129 fprintf (file, "latch %d\n", loop->latch->index);
132 fprintf (file, "multiple latches:");
133 latches = get_loop_latch_edges (loop);
134 for (i = 0; VEC_iterate (edge, latches, i, e); i++)
135 fprintf (file, " %d", e->src->index);
136 VEC_free (edge, heap, latches);
137 fprintf (file, "\n");
140 fprintf (file, ";; depth %d, outer %ld\n",
141 loop_depth (loop), (long) (loop_outer (loop)
142 ? loop_outer (loop)->num : -1));
144 fprintf (file, ";; nodes:");
145 bbs = get_loop_body (loop);
146 for (i = 0; i < loop->num_nodes; i++)
147 fprintf (file, " %d", bbs[i]->index);
149 fprintf (file, "\n");
152 loop_dump_aux (loop, file, verbose);
155 /* Dump the loop information about loops to the stream FILE,
156 using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
159 flow_loops_dump (FILE *file, void (*loop_dump_aux) (const struct loop *, FILE *, int), int verbose)
164 if (!current_loops || ! file)
167 fprintf (file, ";; %d loops found\n", number_of_loops ());
169 FOR_EACH_LOOP (li, loop, LI_INCLUDE_ROOT)
171 flow_loop_dump (loop, file, loop_dump_aux, verbose);
175 flow_loops_cfg_dump (file);
178 /* Free data allocated for LOOP. */
181 flow_loop_free (struct loop *loop)
183 struct loop_exit *exit, *next;
185 VEC_free (loop_p, gc, loop->superloops);
187 /* Break the list of the loop exit records. They will be freed when the
188 corresponding edge is rescanned or removed, and this avoids
189 accessing the (already released) head of the list stored in the
191 for (exit = loop->exits->next; exit != loop->exits; exit = next)
198 ggc_free (loop->exits);
202 /* Free all the memory allocated for LOOPS. */
205 flow_loops_free (struct loops *loops)
212 /* Free the loop descriptors. */
213 for (i = 0; VEC_iterate (loop_p, loops->larray, i, loop); i++)
218 flow_loop_free (loop);
221 VEC_free (loop_p, gc, loops->larray);
225 /* Find the nodes contained within the LOOP with header HEADER.
226 Return the number of nodes within the loop. */
229 flow_loop_nodes_find (basic_block header, struct loop *loop)
231 VEC (basic_block, heap) *stack = NULL;
234 edge_iterator latch_ei;
235 unsigned depth = loop_depth (loop);
237 header->loop_father = loop;
238 header->loop_depth = depth;
240 FOR_EACH_EDGE (latch, latch_ei, loop->header->preds)
242 if (latch->src->loop_father == loop
243 || !dominated_by_p (CDI_DOMINATORS, latch->src, loop->header))
247 VEC_safe_push (basic_block, heap, stack, latch->src);
248 latch->src->loop_father = loop;
249 latch->src->loop_depth = depth;
251 while (!VEC_empty (basic_block, stack))
257 node = VEC_pop (basic_block, stack);
259 FOR_EACH_EDGE (e, ei, node->preds)
261 basic_block ancestor = e->src;
263 if (ancestor->loop_father != loop)
265 ancestor->loop_father = loop;
266 ancestor->loop_depth = depth;
268 VEC_safe_push (basic_block, heap, stack, ancestor);
273 VEC_free (basic_block, heap, stack);
278 /* Records the vector of superloops of the loop LOOP, whose immediate
279 superloop is FATHER. */
282 establish_preds (struct loop *loop, struct loop *father)
285 unsigned depth = loop_depth (father) + 1;
288 VEC_truncate (loop_p, loop->superloops, 0);
289 VEC_reserve (loop_p, gc, loop->superloops, depth);
290 for (i = 0; VEC_iterate (loop_p, father->superloops, i, ploop); i++)
291 VEC_quick_push (loop_p, loop->superloops, ploop);
292 VEC_quick_push (loop_p, loop->superloops, father);
294 for (ploop = loop->inner; ploop; ploop = ploop->next)
295 establish_preds (ploop, loop);
298 /* Add LOOP to the loop hierarchy tree where FATHER is father of the
299 added loop. If LOOP has some children, take care of that their
300 pred field will be initialized correctly. */
303 flow_loop_tree_node_add (struct loop *father, struct loop *loop)
305 loop->next = father->inner;
306 father->inner = loop;
308 establish_preds (loop, father);
311 /* Remove LOOP from the loop hierarchy tree. */
314 flow_loop_tree_node_remove (struct loop *loop)
316 struct loop *prev, *father;
318 father = loop_outer (loop);
320 /* Remove loop from the list of sons. */
321 if (father->inner == loop)
322 father->inner = loop->next;
325 for (prev = father->inner; prev->next != loop; prev = prev->next)
327 prev->next = loop->next;
330 VEC_truncate (loop_p, loop->superloops, 0);
333 /* Allocates and returns new loop structure. */
338 struct loop *loop = GGC_CNEW (struct loop);
340 loop->exits = GGC_CNEW (struct loop_exit);
341 loop->exits->next = loop->exits->prev = loop->exits;
346 /* Initializes loops structure LOOPS, reserving place for NUM_LOOPS loops
347 (including the root of the loop tree). */
350 init_loops_structure (struct loops *loops, unsigned num_loops)
354 memset (loops, 0, sizeof *loops);
355 loops->larray = VEC_alloc (loop_p, gc, num_loops);
357 /* Dummy loop containing whole function. */
358 root = alloc_loop ();
359 root->num_nodes = n_basic_blocks;
360 root->latch = EXIT_BLOCK_PTR;
361 root->header = ENTRY_BLOCK_PTR;
362 ENTRY_BLOCK_PTR->loop_father = root;
363 EXIT_BLOCK_PTR->loop_father = root;
365 VEC_quick_push (loop_p, loops->larray, root);
366 loops->tree_root = root;
369 /* Find all the natural loops in the function and save in LOOPS structure and
370 recalculate loop_depth information in basic block structures.
371 Return the number of natural loops found. */
374 flow_loops_find (struct loops *loops)
385 /* Ensure that the dominators are computed. */
386 calculate_dominance_info (CDI_DOMINATORS);
388 /* Taking care of this degenerate case makes the rest of
389 this code simpler. */
390 if (n_basic_blocks == NUM_FIXED_BLOCKS)
392 init_loops_structure (loops, 1);
399 /* Count the number of loop headers. This should be the
400 same as the number of natural loops. */
401 headers = sbitmap_alloc (last_basic_block);
402 sbitmap_zero (headers);
409 header->loop_depth = 0;
411 /* If we have an abnormal predecessor, do not consider the
412 loop (not worth the problems). */
413 FOR_EACH_EDGE (e, ei, header->preds)
414 if (e->flags & EDGE_ABNORMAL)
419 FOR_EACH_EDGE (e, ei, header->preds)
421 basic_block latch = e->src;
423 gcc_assert (!(e->flags & EDGE_ABNORMAL));
425 /* Look for back edges where a predecessor is dominated
426 by this block. A natural loop has a single entry
427 node (header) that dominates all the nodes in the
428 loop. It also has single back edge to the header
429 from a latch node. */
430 if (latch != ENTRY_BLOCK_PTR
431 && dominated_by_p (CDI_DOMINATORS, latch, header))
433 /* Shared headers should be eliminated by now. */
434 SET_BIT (headers, header->index);
440 /* Allocate loop structures. */
441 init_loops_structure (loops, num_loops + 1);
443 /* Find and record information about all the natural loops
446 bb->loop_father = loops->tree_root;
450 /* Compute depth first search order of the CFG so that outer
451 natural loops will be found before inner natural loops. */
452 dfs_order = XNEWVEC (int, n_basic_blocks);
453 rc_order = XNEWVEC (int, n_basic_blocks);
454 pre_and_rev_post_order_compute (dfs_order, rc_order, false);
458 for (b = 0; b < n_basic_blocks - NUM_FIXED_BLOCKS; b++)
463 /* Search the nodes of the CFG in reverse completion order
464 so that we can find outer loops first. */
465 if (!TEST_BIT (headers, rc_order[b]))
468 header = BASIC_BLOCK (rc_order[b]);
470 loop = alloc_loop ();
471 VEC_quick_push (loop_p, loops->larray, loop);
473 loop->header = header;
474 loop->num = num_loops;
477 flow_loop_tree_node_add (header->loop_father, loop);
478 loop->num_nodes = flow_loop_nodes_find (loop->header, loop);
480 /* Look for the latch for this header block, if it has just a
482 FOR_EACH_EDGE (e, ei, header->preds)
484 basic_block latch = e->src;
486 if (flow_bb_inside_loop_p (loop, latch))
488 if (loop->latch != NULL)
490 /* More than one latch edge. */
503 sbitmap_free (headers);
507 return VEC_length (loop_p, loops->larray);
510 /* Ratio of frequencies of edges so that one of more latch edges is
511 considered to belong to inner loop with same header. */
512 #define HEAVY_EDGE_RATIO 8
514 /* Minimum number of samples for that we apply
515 find_subloop_latch_edge_by_profile heuristics. */
516 #define HEAVY_EDGE_MIN_SAMPLES 10
518 /* If the profile info is available, finds an edge in LATCHES that much more
519 frequent than the remaining edges. Returns such an edge, or NULL if we do
522 We do not use guessed profile here, only the measured one. The guessed
523 profile is usually too flat and unreliable for this (and it is mostly based
524 on the loop structure of the program, so it does not make much sense to
525 derive the loop structure from it). */
528 find_subloop_latch_edge_by_profile (VEC (edge, heap) *latches)
532 gcov_type mcount = 0, tcount = 0;
534 for (i = 0; VEC_iterate (edge, latches, i, e); i++)
536 if (e->count > mcount)
544 if (tcount < HEAVY_EDGE_MIN_SAMPLES
545 || (tcount - mcount) * HEAVY_EDGE_RATIO > tcount)
550 "Found latch edge %d -> %d using profile information.\n",
551 me->src->index, me->dest->index);
555 /* Among LATCHES, guesses a latch edge of LOOP corresponding to subloop, based
556 on the structure of induction variables. Returns this edge, or NULL if we
559 We are quite conservative, and look just for an obvious simple innermost
560 loop (which is the case where we would lose the most performance by not
561 disambiguating the loop). More precisely, we look for the following
562 situation: The source of the chosen latch edge dominates sources of all
563 the other latch edges. Additionally, the header does not contain a phi node
564 such that the argument from the chosen edge is equal to the argument from
568 find_subloop_latch_edge_by_ivs (struct loop *loop, VEC (edge, heap) *latches)
570 edge e, latch = VEC_index (edge, latches, 0);
575 /* Find the candidate for the latch edge. */
576 for (i = 1; VEC_iterate (edge, latches, i, e); i++)
577 if (dominated_by_p (CDI_DOMINATORS, latch->src, e->src))
580 /* Verify that it dominates all the latch edges. */
581 for (i = 0; VEC_iterate (edge, latches, i, e); i++)
582 if (!dominated_by_p (CDI_DOMINATORS, e->src, latch->src))
585 /* Check for a phi node that would deny that this is a latch edge of
587 for (phi = phi_nodes (loop->header); phi; phi = PHI_CHAIN (phi))
589 lop = PHI_ARG_DEF_FROM_EDGE (phi, latch);
591 /* Ignore the values that are not changed inside the subloop. */
592 if (TREE_CODE (lop) != SSA_NAME
593 || SSA_NAME_DEF_STMT (lop) == phi)
595 bb = bb_for_stmt (SSA_NAME_DEF_STMT (lop));
596 if (!bb || !flow_bb_inside_loop_p (loop, bb))
599 for (i = 0; VEC_iterate (edge, latches, i, e); i++)
601 && PHI_ARG_DEF_FROM_EDGE (phi, e) == lop)
607 "Found latch edge %d -> %d using iv structure.\n",
608 latch->src->index, latch->dest->index);
612 /* If we can determine that one of the several latch edges of LOOP behaves
613 as a latch edge of a separate subloop, returns this edge. Otherwise
617 find_subloop_latch_edge (struct loop *loop)
619 VEC (edge, heap) *latches = get_loop_latch_edges (loop);
622 if (VEC_length (edge, latches) > 1)
624 latch = find_subloop_latch_edge_by_profile (latches);
627 /* We consider ivs to guess the latch edge only in SSA. Perhaps we
628 should use cfghook for this, but it is hard to imagine it would
629 be useful elsewhere. */
630 && current_ir_type () == IR_GIMPLE)
631 latch = find_subloop_latch_edge_by_ivs (loop, latches);
634 VEC_free (edge, heap, latches);
638 /* Callback for make_forwarder_block. Returns true if the edge E is marked
639 in the set MFB_REIS_SET. */
641 static struct pointer_set_t *mfb_reis_set;
643 mfb_redirect_edges_in_set (edge e)
645 return pointer_set_contains (mfb_reis_set, e);
648 /* Creates a subloop of LOOP with latch edge LATCH. */
651 form_subloop (struct loop *loop, edge latch)
655 struct loop *new_loop;
657 mfb_reis_set = pointer_set_create ();
658 FOR_EACH_EDGE (e, ei, loop->header->preds)
661 pointer_set_insert (mfb_reis_set, e);
663 new_entry = make_forwarder_block (loop->header, mfb_redirect_edges_in_set,
665 pointer_set_destroy (mfb_reis_set);
667 loop->header = new_entry->src;
669 /* Find the blocks and subloops that belong to the new loop, and add it to
670 the appropriate place in the loop tree. */
671 new_loop = alloc_loop ();
672 new_loop->header = new_entry->dest;
673 new_loop->latch = latch->src;
674 add_loop (new_loop, loop);
677 /* Make all the latch edges of LOOP to go to a single forwarder block --
678 a new latch of LOOP. */
681 merge_latch_edges (struct loop *loop)
683 VEC (edge, heap) *latches = get_loop_latch_edges (loop);
687 gcc_assert (VEC_length (edge, latches) > 0);
689 if (VEC_length (edge, latches) == 1)
690 loop->latch = VEC_index (edge, latches, 0)->src;
694 fprintf (dump_file, "Merged latch edges of loop %d\n", loop->num);
696 mfb_reis_set = pointer_set_create ();
697 for (i = 0; VEC_iterate (edge, latches, i, e); i++)
698 pointer_set_insert (mfb_reis_set, e);
699 latch = make_forwarder_block (loop->header, mfb_redirect_edges_in_set,
701 pointer_set_destroy (mfb_reis_set);
703 loop->header = latch->dest;
704 loop->latch = latch->src;
707 VEC_free (edge, heap, latches);
710 /* LOOP may have several latch edges. Transform it into (possibly several)
711 loops with single latch edge. */
714 disambiguate_multiple_latches (struct loop *loop)
718 /* We eliminate the multiple latches by splitting the header to the forwarder
719 block F and the rest R, and redirecting the edges. There are two cases:
721 1) If there is a latch edge E that corresponds to a subloop (we guess
722 that based on profile -- if it is taken much more often than the
723 remaining edges; and on trees, using the information about induction
724 variables of the loops), we redirect E to R, all the remaining edges to
725 F, then rescan the loops and try again for the outer loop.
726 2) If there is no such edge, we redirect all latch edges to F, and the
727 entry edges to R, thus making F the single latch of the loop. */
730 fprintf (dump_file, "Disambiguating loop %d with multiple latches\n",
733 /* During latch merging, we may need to redirect the entry edges to a new
734 block. This would cause problems if the entry edge was the one from the
735 entry block. To avoid having to handle this case specially, split
737 e = find_edge (ENTRY_BLOCK_PTR, loop->header);
743 e = find_subloop_latch_edge (loop);
747 form_subloop (loop, e);
750 merge_latch_edges (loop);
753 /* Split loops with multiple latch edges. */
756 disambiguate_loops_with_multiple_latches (void)
761 FOR_EACH_LOOP (li, loop, 0)
764 disambiguate_multiple_latches (loop);
768 /* Return nonzero if basic block BB belongs to LOOP. */
770 flow_bb_inside_loop_p (const struct loop *loop, const basic_block bb)
772 struct loop *source_loop;
774 if (bb == ENTRY_BLOCK_PTR || bb == EXIT_BLOCK_PTR)
777 source_loop = bb->loop_father;
778 return loop == source_loop || flow_loop_nested_p (loop, source_loop);
781 /* Enumeration predicate for get_loop_body_with_size. */
783 glb_enum_p (basic_block bb, void *glb_loop)
785 struct loop *loop = (struct loop *) glb_loop;
786 return (bb != loop->header
787 && dominated_by_p (CDI_DOMINATORS, bb, loop->header));
790 /* Gets basic blocks of a LOOP. Header is the 0-th block, rest is in dfs
791 order against direction of edges from latch. Specially, if
792 header != latch, latch is the 1-st block. LOOP cannot be the fake
793 loop tree root, and its size must be at most MAX_SIZE. The blocks
794 in the LOOP body are stored to BODY, and the size of the LOOP is
798 get_loop_body_with_size (const struct loop *loop, basic_block *body,
801 return dfs_enumerate_from (loop->header, 1, glb_enum_p,
802 body, max_size, (void *) loop);
805 /* Gets basic blocks of a LOOP. Header is the 0-th block, rest is in dfs
806 order against direction of edges from latch. Specially, if
807 header != latch, latch is the 1-st block. */
810 get_loop_body (const struct loop *loop)
812 basic_block *body, bb;
815 gcc_assert (loop->num_nodes);
817 body = XCNEWVEC (basic_block, loop->num_nodes);
819 if (loop->latch == EXIT_BLOCK_PTR)
821 /* There may be blocks unreachable from EXIT_BLOCK, hence we need to
822 special-case the fake loop that contains the whole function. */
823 gcc_assert (loop->num_nodes == (unsigned) n_basic_blocks);
824 body[tv++] = loop->header;
825 body[tv++] = EXIT_BLOCK_PTR;
830 tv = get_loop_body_with_size (loop, body, loop->num_nodes);
832 gcc_assert (tv == loop->num_nodes);
836 /* Fills dominance descendants inside LOOP of the basic block BB into
837 array TOVISIT from index *TV. */
840 fill_sons_in_loop (const struct loop *loop, basic_block bb,
841 basic_block *tovisit, int *tv)
843 basic_block son, postpone = NULL;
845 tovisit[(*tv)++] = bb;
846 for (son = first_dom_son (CDI_DOMINATORS, bb);
848 son = next_dom_son (CDI_DOMINATORS, son))
850 if (!flow_bb_inside_loop_p (loop, son))
853 if (dominated_by_p (CDI_DOMINATORS, loop->latch, son))
858 fill_sons_in_loop (loop, son, tovisit, tv);
862 fill_sons_in_loop (loop, postpone, tovisit, tv);
865 /* Gets body of a LOOP (that must be different from the outermost loop)
866 sorted by dominance relation. Additionally, if a basic block s dominates
867 the latch, then only blocks dominated by s are be after it. */
870 get_loop_body_in_dom_order (const struct loop *loop)
872 basic_block *tovisit;
875 gcc_assert (loop->num_nodes);
877 tovisit = XCNEWVEC (basic_block, loop->num_nodes);
879 gcc_assert (loop->latch != EXIT_BLOCK_PTR);
882 fill_sons_in_loop (loop, loop->header, tovisit, &tv);
884 gcc_assert (tv == (int) loop->num_nodes);
889 /* Get body of a LOOP in breadth first sort order. */
892 get_loop_body_in_bfs_order (const struct loop *loop)
900 gcc_assert (loop->num_nodes);
901 gcc_assert (loop->latch != EXIT_BLOCK_PTR);
903 blocks = XCNEWVEC (basic_block, loop->num_nodes);
904 visited = BITMAP_ALLOC (NULL);
907 while (i < loop->num_nodes)
912 if (!bitmap_bit_p (visited, bb->index))
914 /* This basic block is now visited */
915 bitmap_set_bit (visited, bb->index);
919 FOR_EACH_EDGE (e, ei, bb->succs)
921 if (flow_bb_inside_loop_p (loop, e->dest))
923 if (!bitmap_bit_p (visited, e->dest->index))
925 bitmap_set_bit (visited, e->dest->index);
926 blocks[i++] = e->dest;
931 gcc_assert (i >= vc);
936 BITMAP_FREE (visited);
940 /* Hash function for struct loop_exit. */
943 loop_exit_hash (const void *ex)
945 const struct loop_exit *const exit = (const struct loop_exit *) ex;
947 return htab_hash_pointer (exit->e);
950 /* Equality function for struct loop_exit. Compares with edge. */
953 loop_exit_eq (const void *ex, const void *e)
955 const struct loop_exit *const exit = (const struct loop_exit *) ex;
960 /* Frees the list of loop exit descriptions EX. */
963 loop_exit_free (void *ex)
965 struct loop_exit *exit = (struct loop_exit *) ex, *next;
967 for (; exit; exit = next)
971 exit->next->prev = exit->prev;
972 exit->prev->next = exit->next;
978 /* Returns the list of records for E as an exit of a loop. */
980 static struct loop_exit *
981 get_exit_descriptions (edge e)
983 return (struct loop_exit *) htab_find_with_hash (current_loops->exits, e,
984 htab_hash_pointer (e));
987 /* Updates the lists of loop exits in that E appears.
988 If REMOVED is true, E is being removed, and we
989 just remove it from the lists of exits.
990 If NEW_EDGE is true and E is not a loop exit, we
991 do not try to remove it from loop exit lists. */
994 rescan_loop_exit (edge e, bool new_edge, bool removed)
997 struct loop_exit *exits = NULL, *exit;
998 struct loop *aloop, *cloop;
1000 if ((current_loops->state & LOOPS_HAVE_RECORDED_EXITS) == 0)
1004 && e->src->loop_father != NULL
1005 && e->dest->loop_father != NULL
1006 && !flow_bb_inside_loop_p (e->src->loop_father, e->dest))
1008 cloop = find_common_loop (e->src->loop_father, e->dest->loop_father);
1009 for (aloop = e->src->loop_father;
1011 aloop = loop_outer (aloop))
1013 exit = GGC_NEW (struct loop_exit);
1016 exit->next = aloop->exits->next;
1017 exit->prev = aloop->exits;
1018 exit->next->prev = exit;
1019 exit->prev->next = exit;
1021 exit->next_e = exits;
1026 if (!exits && new_edge)
1029 slot = htab_find_slot_with_hash (current_loops->exits, e,
1030 htab_hash_pointer (e),
1031 exits ? INSERT : NO_INSERT);
1038 loop_exit_free (*slot);
1042 htab_clear_slot (current_loops->exits, slot);
1045 /* For each loop, record list of exit edges, and start maintaining these
1049 record_loop_exits (void)
1058 if (current_loops->state & LOOPS_HAVE_RECORDED_EXITS)
1060 current_loops->state |= LOOPS_HAVE_RECORDED_EXITS;
1062 gcc_assert (current_loops->exits == NULL);
1063 current_loops->exits = htab_create_alloc (2 * number_of_loops (),
1067 ggc_calloc, ggc_free);
1071 FOR_EACH_EDGE (e, ei, bb->succs)
1073 rescan_loop_exit (e, true, false);
1078 /* Dumps information about the exit in *SLOT to FILE.
1079 Callback for htab_traverse. */
1082 dump_recorded_exit (void **slot, void *file)
1084 struct loop_exit *exit = (struct loop_exit *) *slot;
1088 for (; exit != NULL; exit = exit->next_e)
1091 fprintf ((FILE*) file, "Edge %d->%d exits %u loops\n",
1092 e->src->index, e->dest->index, n);
1097 /* Dumps the recorded exits of loops to FILE. */
1099 extern void dump_recorded_exits (FILE *);
1101 dump_recorded_exits (FILE *file)
1103 if (!current_loops->exits)
1105 htab_traverse (current_loops->exits, dump_recorded_exit, file);
1108 /* Releases lists of loop exits. */
1111 release_recorded_exits (void)
1113 gcc_assert (current_loops->state & LOOPS_HAVE_RECORDED_EXITS);
1114 htab_delete (current_loops->exits);
1115 current_loops->exits = NULL;
1116 current_loops->state &= ~LOOPS_HAVE_RECORDED_EXITS;
1119 /* Returns the list of the exit edges of a LOOP. */
1122 get_loop_exit_edges (const struct loop *loop)
1124 VEC (edge, heap) *edges = NULL;
1129 struct loop_exit *exit;
1131 gcc_assert (loop->latch != EXIT_BLOCK_PTR);
1133 /* If we maintain the lists of exits, use them. Otherwise we must
1134 scan the body of the loop. */
1135 if (current_loops->state & LOOPS_HAVE_RECORDED_EXITS)
1137 for (exit = loop->exits->next; exit->e; exit = exit->next)
1138 VEC_safe_push (edge, heap, edges, exit->e);
1142 body = get_loop_body (loop);
1143 for (i = 0; i < loop->num_nodes; i++)
1144 FOR_EACH_EDGE (e, ei, body[i]->succs)
1146 if (!flow_bb_inside_loop_p (loop, e->dest))
1147 VEC_safe_push (edge, heap, edges, e);
1155 /* Counts the number of conditional branches inside LOOP. */
1158 num_loop_branches (const struct loop *loop)
1163 gcc_assert (loop->latch != EXIT_BLOCK_PTR);
1165 body = get_loop_body (loop);
1167 for (i = 0; i < loop->num_nodes; i++)
1168 if (EDGE_COUNT (body[i]->succs) >= 2)
1175 /* Adds basic block BB to LOOP. */
1177 add_bb_to_loop (basic_block bb, struct loop *loop)
1184 gcc_assert (bb->loop_father == NULL);
1185 bb->loop_father = loop;
1186 bb->loop_depth = loop_depth (loop);
1188 for (i = 0; VEC_iterate (loop_p, loop->superloops, i, ploop); i++)
1191 FOR_EACH_EDGE (e, ei, bb->succs)
1193 rescan_loop_exit (e, true, false);
1195 FOR_EACH_EDGE (e, ei, bb->preds)
1197 rescan_loop_exit (e, true, false);
1201 /* Remove basic block BB from loops. */
1203 remove_bb_from_loops (basic_block bb)
1206 struct loop *loop = bb->loop_father;
1211 gcc_assert (loop != NULL);
1213 for (i = 0; VEC_iterate (loop_p, loop->superloops, i, ploop); i++)
1215 bb->loop_father = NULL;
1218 FOR_EACH_EDGE (e, ei, bb->succs)
1220 rescan_loop_exit (e, false, true);
1222 FOR_EACH_EDGE (e, ei, bb->preds)
1224 rescan_loop_exit (e, false, true);
1228 /* Finds nearest common ancestor in loop tree for given loops. */
1230 find_common_loop (struct loop *loop_s, struct loop *loop_d)
1232 unsigned sdepth, ddepth;
1234 if (!loop_s) return loop_d;
1235 if (!loop_d) return loop_s;
1237 sdepth = loop_depth (loop_s);
1238 ddepth = loop_depth (loop_d);
1240 if (sdepth < ddepth)
1241 loop_d = VEC_index (loop_p, loop_d->superloops, sdepth);
1242 else if (sdepth > ddepth)
1243 loop_s = VEC_index (loop_p, loop_s->superloops, ddepth);
1245 while (loop_s != loop_d)
1247 loop_s = loop_outer (loop_s);
1248 loop_d = loop_outer (loop_d);
1253 /* Removes LOOP from structures and frees its data. */
1256 delete_loop (struct loop *loop)
1258 /* Remove the loop from structure. */
1259 flow_loop_tree_node_remove (loop);
1261 /* Remove loop from loops array. */
1262 VEC_replace (loop_p, current_loops->larray, loop->num, NULL);
1264 /* Free loop data. */
1265 flow_loop_free (loop);
1268 /* Cancels the LOOP; it must be innermost one. */
1271 cancel_loop (struct loop *loop)
1275 struct loop *outer = loop_outer (loop);
1277 gcc_assert (!loop->inner);
1279 /* Move blocks up one level (they should be removed as soon as possible). */
1280 bbs = get_loop_body (loop);
1281 for (i = 0; i < loop->num_nodes; i++)
1282 bbs[i]->loop_father = outer;
1287 /* Cancels LOOP and all its subloops. */
1289 cancel_loop_tree (struct loop *loop)
1292 cancel_loop_tree (loop->inner);
1296 /* Checks that information about loops is correct
1297 -- sizes of loops are all right
1298 -- results of get_loop_body really belong to the loop
1299 -- loop header have just single entry edge and single latch edge
1300 -- loop latches have only single successor that is header of their loop
1301 -- irreducible loops are correctly marked
1304 verify_loop_structure (void)
1306 unsigned *sizes, i, j;
1308 basic_block *bbs, bb;
1312 unsigned num = number_of_loops ();
1314 struct loop_exit *exit, *mexit;
1317 sizes = XCNEWVEC (unsigned, num);
1321 for (loop = bb->loop_father; loop; loop = loop_outer (loop))
1324 FOR_EACH_LOOP (li, loop, LI_INCLUDE_ROOT)
1328 if (loop->num_nodes != sizes[i])
1330 error ("size of loop %d should be %d, not %d",
1331 i, sizes[i], loop->num_nodes);
1336 /* Check get_loop_body. */
1337 FOR_EACH_LOOP (li, loop, 0)
1339 bbs = get_loop_body (loop);
1341 for (j = 0; j < loop->num_nodes; j++)
1342 if (!flow_bb_inside_loop_p (loop, bbs[j]))
1344 error ("bb %d do not belong to loop %d",
1345 bbs[j]->index, loop->num);
1351 /* Check headers and latches. */
1352 FOR_EACH_LOOP (li, loop, 0)
1356 if ((current_loops->state & LOOPS_HAVE_PREHEADERS)
1357 && EDGE_COUNT (loop->header->preds) != 2)
1359 error ("loop %d's header does not have exactly 2 entries", i);
1362 if (current_loops->state & LOOPS_HAVE_SIMPLE_LATCHES)
1364 if (!single_succ_p (loop->latch))
1366 error ("loop %d's latch does not have exactly 1 successor", i);
1369 if (single_succ (loop->latch) != loop->header)
1371 error ("loop %d's latch does not have header as successor", i);
1374 if (loop->latch->loop_father != loop)
1376 error ("loop %d's latch does not belong directly to it", i);
1380 if (loop->header->loop_father != loop)
1382 error ("loop %d's header does not belong directly to it", i);
1385 if ((current_loops->state & LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
1386 && (loop_latch_edge (loop)->flags & EDGE_IRREDUCIBLE_LOOP))
1388 error ("loop %d's latch is marked as part of irreducible region", i);
1393 /* Check irreducible loops. */
1394 if (current_loops->state & LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
1396 /* Record old info. */
1397 irreds = sbitmap_alloc (last_basic_block);
1401 if (bb->flags & BB_IRREDUCIBLE_LOOP)
1402 SET_BIT (irreds, bb->index);
1404 RESET_BIT (irreds, bb->index);
1405 FOR_EACH_EDGE (e, ei, bb->succs)
1406 if (e->flags & EDGE_IRREDUCIBLE_LOOP)
1407 e->flags |= EDGE_ALL_FLAGS + 1;
1411 mark_irreducible_loops ();
1418 if ((bb->flags & BB_IRREDUCIBLE_LOOP)
1419 && !TEST_BIT (irreds, bb->index))
1421 error ("basic block %d should be marked irreducible", bb->index);
1424 else if (!(bb->flags & BB_IRREDUCIBLE_LOOP)
1425 && TEST_BIT (irreds, bb->index))
1427 error ("basic block %d should not be marked irreducible", bb->index);
1430 FOR_EACH_EDGE (e, ei, bb->succs)
1432 if ((e->flags & EDGE_IRREDUCIBLE_LOOP)
1433 && !(e->flags & (EDGE_ALL_FLAGS + 1)))
1435 error ("edge from %d to %d should be marked irreducible",
1436 e->src->index, e->dest->index);
1439 else if (!(e->flags & EDGE_IRREDUCIBLE_LOOP)
1440 && (e->flags & (EDGE_ALL_FLAGS + 1)))
1442 error ("edge from %d to %d should not be marked irreducible",
1443 e->src->index, e->dest->index);
1446 e->flags &= ~(EDGE_ALL_FLAGS + 1);
1452 /* Check the recorded loop exits. */
1453 FOR_EACH_LOOP (li, loop, 0)
1455 if (!loop->exits || loop->exits->e != NULL)
1457 error ("corrupted head of the exits list of loop %d",
1463 /* Check that the list forms a cycle, and all elements except
1464 for the head are nonnull. */
1465 for (mexit = loop->exits, exit = mexit->next, i = 0;
1466 exit->e && exit != mexit;
1470 mexit = mexit->next;
1473 if (exit != loop->exits)
1475 error ("corrupted exits list of loop %d", loop->num);
1480 if ((current_loops->state & LOOPS_HAVE_RECORDED_EXITS) == 0)
1482 if (loop->exits->next != loop->exits)
1484 error ("nonempty exits list of loop %d, but exits are not recorded",
1491 if (current_loops->state & LOOPS_HAVE_RECORDED_EXITS)
1493 unsigned n_exits = 0, eloops;
1495 memset (sizes, 0, sizeof (unsigned) * num);
1499 if (bb->loop_father == current_loops->tree_root)
1501 FOR_EACH_EDGE (e, ei, bb->succs)
1503 if (flow_bb_inside_loop_p (bb->loop_father, e->dest))
1507 exit = get_exit_descriptions (e);
1510 error ("Exit %d->%d not recorded",
1511 e->src->index, e->dest->index);
1515 for (; exit; exit = exit->next_e)
1518 for (loop = bb->loop_father;
1519 loop != e->dest->loop_father;
1520 loop = loop_outer (loop))
1528 error ("Wrong list of exited loops for edge %d->%d",
1529 e->src->index, e->dest->index);
1535 if (n_exits != htab_elements (current_loops->exits))
1537 error ("Too many loop exits recorded");
1541 FOR_EACH_LOOP (li, loop, 0)
1544 for (exit = loop->exits->next; exit->e; exit = exit->next)
1546 if (eloops != sizes[loop->num])
1548 error ("%d exits recorded for loop %d (having %d exits)",
1549 eloops, loop->num, sizes[loop->num]);
1560 /* Returns latch edge of LOOP. */
1562 loop_latch_edge (const struct loop *loop)
1564 return find_edge (loop->latch, loop->header);
1567 /* Returns preheader edge of LOOP. */
1569 loop_preheader_edge (const struct loop *loop)
1574 gcc_assert ((current_loops->state & LOOPS_HAVE_PREHEADERS) != 0);
1576 FOR_EACH_EDGE (e, ei, loop->header->preds)
1577 if (e->src != loop->latch)
1583 /* Returns true if E is an exit of LOOP. */
1586 loop_exit_edge_p (const struct loop *loop, edge e)
1588 return (flow_bb_inside_loop_p (loop, e->src)
1589 && !flow_bb_inside_loop_p (loop, e->dest));
1592 /* Returns the single exit edge of LOOP, or NULL if LOOP has either no exit
1593 or more than one exit. If loops do not have the exits recorded, NULL
1594 is returned always. */
1597 single_exit (const struct loop *loop)
1599 struct loop_exit *exit = loop->exits->next;
1601 if ((current_loops->state & LOOPS_HAVE_RECORDED_EXITS) == 0)
1604 if (exit->e && exit->next == loop->exits)