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 3, 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 COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
23 #include "coretypes.h"
26 #include "hard-reg-set.h"
29 #include "basic-block.h"
34 #include "tree-flow.h"
35 #include "pointer-set.h"
39 static void flow_loops_cfg_dump (FILE *);
41 /* Dump loop related CFG information. */
44 flow_loops_cfg_dump (FILE *file)
56 fprintf (file, ";; %d succs { ", bb->index);
57 FOR_EACH_EDGE (succ, ei, bb->succs)
58 fprintf (file, "%d ", succ->dest->index);
59 fprintf (file, "}\n");
63 /* Return nonzero if the nodes of LOOP are a subset of OUTER. */
66 flow_loop_nested_p (const struct loop *outer, const struct loop *loop)
68 unsigned odepth = loop_depth (outer);
70 return (loop_depth (loop) > odepth
71 && VEC_index (loop_p, loop->superloops, odepth) == outer);
74 /* Returns the loop such that LOOP is nested DEPTH (indexed from zero)
78 superloop_at_depth (struct loop *loop, unsigned depth)
80 unsigned ldepth = loop_depth (loop);
82 gcc_assert (depth <= ldepth);
87 return VEC_index (loop_p, loop->superloops, depth);
90 /* Returns the list of the latch edges of LOOP. */
92 static VEC (edge, heap) *
93 get_loop_latch_edges (const struct loop *loop)
97 VEC (edge, heap) *ret = NULL;
99 FOR_EACH_EDGE (e, ei, loop->header->preds)
101 if (dominated_by_p (CDI_DOMINATORS, e->src, loop->header))
102 VEC_safe_push (edge, heap, ret, e);
108 /* Dump the loop information specified by LOOP to the stream FILE
109 using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
112 flow_loop_dump (const struct loop *loop, FILE *file,
113 void (*loop_dump_aux) (const struct loop *, FILE *, int),
118 VEC (edge, heap) *latches;
121 if (! loop || ! loop->header)
124 fprintf (file, ";;\n;; Loop %d\n", loop->num);
126 fprintf (file, ";; header %d, ", loop->header->index);
128 fprintf (file, "latch %d\n", loop->latch->index);
131 fprintf (file, "multiple latches:");
132 latches = get_loop_latch_edges (loop);
133 for (i = 0; VEC_iterate (edge, latches, i, e); i++)
134 fprintf (file, " %d", e->src->index);
135 VEC_free (edge, heap, latches);
136 fprintf (file, "\n");
139 fprintf (file, ";; depth %d, outer %ld\n",
140 loop_depth (loop), (long) (loop_outer (loop)
141 ? loop_outer (loop)->num : -1));
143 fprintf (file, ";; nodes:");
144 bbs = get_loop_body (loop);
145 for (i = 0; i < loop->num_nodes; i++)
146 fprintf (file, " %d", bbs[i]->index);
148 fprintf (file, "\n");
151 loop_dump_aux (loop, file, verbose);
154 /* Dump the loop information about loops to the stream FILE,
155 using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
158 flow_loops_dump (FILE *file, void (*loop_dump_aux) (const struct loop *, FILE *, int), int verbose)
163 if (!current_loops || ! file)
166 fprintf (file, ";; %d loops found\n", number_of_loops ());
168 FOR_EACH_LOOP (li, loop, LI_INCLUDE_ROOT)
170 flow_loop_dump (loop, file, loop_dump_aux, verbose);
174 flow_loops_cfg_dump (file);
177 /* Free data allocated for LOOP. */
180 flow_loop_free (struct loop *loop)
182 struct loop_exit *exit, *next;
184 VEC_free (loop_p, gc, loop->superloops);
186 /* Break the list of the loop exit records. They will be freed when the
187 corresponding edge is rescanned or removed, and this avoids
188 accessing the (already released) head of the list stored in the
190 for (exit = loop->exits->next; exit != loop->exits; exit = next)
197 ggc_free (loop->exits);
201 /* Free all the memory allocated for LOOPS. */
204 flow_loops_free (struct loops *loops)
211 /* Free the loop descriptors. */
212 for (i = 0; VEC_iterate (loop_p, loops->larray, i, loop); i++)
217 flow_loop_free (loop);
220 VEC_free (loop_p, gc, loops->larray);
224 /* Find the nodes contained within the LOOP with header HEADER.
225 Return the number of nodes within the loop. */
228 flow_loop_nodes_find (basic_block header, struct loop *loop)
230 VEC (basic_block, heap) *stack = NULL;
233 edge_iterator latch_ei;
234 unsigned depth = loop_depth (loop);
236 header->loop_father = loop;
237 header->loop_depth = depth;
239 FOR_EACH_EDGE (latch, latch_ei, loop->header->preds)
241 if (latch->src->loop_father == loop
242 || !dominated_by_p (CDI_DOMINATORS, latch->src, loop->header))
246 VEC_safe_push (basic_block, heap, stack, latch->src);
247 latch->src->loop_father = loop;
248 latch->src->loop_depth = depth;
250 while (!VEC_empty (basic_block, stack))
256 node = VEC_pop (basic_block, stack);
258 FOR_EACH_EDGE (e, ei, node->preds)
260 basic_block ancestor = e->src;
262 if (ancestor->loop_father != loop)
264 ancestor->loop_father = loop;
265 ancestor->loop_depth = depth;
267 VEC_safe_push (basic_block, heap, stack, ancestor);
272 VEC_free (basic_block, heap, stack);
277 /* Records the vector of superloops of the loop LOOP, whose immediate
278 superloop is FATHER. */
281 establish_preds (struct loop *loop, struct loop *father)
284 unsigned depth = loop_depth (father) + 1;
287 VEC_truncate (loop_p, loop->superloops, 0);
288 VEC_reserve (loop_p, gc, loop->superloops, depth);
289 for (i = 0; VEC_iterate (loop_p, father->superloops, i, ploop); i++)
290 VEC_quick_push (loop_p, loop->superloops, ploop);
291 VEC_quick_push (loop_p, loop->superloops, father);
293 for (ploop = loop->inner; ploop; ploop = ploop->next)
294 establish_preds (ploop, loop);
297 /* Add LOOP to the loop hierarchy tree where FATHER is father of the
298 added loop. If LOOP has some children, take care of that their
299 pred field will be initialized correctly. */
302 flow_loop_tree_node_add (struct loop *father, struct loop *loop)
304 loop->next = father->inner;
305 father->inner = loop;
307 establish_preds (loop, father);
310 /* Remove LOOP from the loop hierarchy tree. */
313 flow_loop_tree_node_remove (struct loop *loop)
315 struct loop *prev, *father;
317 father = loop_outer (loop);
319 /* Remove loop from the list of sons. */
320 if (father->inner == loop)
321 father->inner = loop->next;
324 for (prev = father->inner; prev->next != loop; prev = prev->next)
326 prev->next = loop->next;
329 VEC_truncate (loop_p, loop->superloops, 0);
332 /* Allocates and returns new loop structure. */
337 struct loop *loop = GGC_CNEW (struct loop);
339 loop->exits = GGC_CNEW (struct loop_exit);
340 loop->exits->next = loop->exits->prev = loop->exits;
345 /* Initializes loops structure LOOPS, reserving place for NUM_LOOPS loops
346 (including the root of the loop tree). */
349 init_loops_structure (struct loops *loops, unsigned num_loops)
353 memset (loops, 0, sizeof *loops);
354 loops->larray = VEC_alloc (loop_p, gc, num_loops);
356 /* Dummy loop containing whole function. */
357 root = alloc_loop ();
358 root->num_nodes = n_basic_blocks;
359 root->latch = EXIT_BLOCK_PTR;
360 root->header = ENTRY_BLOCK_PTR;
361 ENTRY_BLOCK_PTR->loop_father = root;
362 EXIT_BLOCK_PTR->loop_father = root;
364 VEC_quick_push (loop_p, loops->larray, root);
365 loops->tree_root = root;
368 /* Find all the natural loops in the function and save in LOOPS structure and
369 recalculate loop_depth information in basic block structures.
370 Return the number of natural loops found. */
373 flow_loops_find (struct loops *loops)
384 /* Ensure that the dominators are computed. */
385 calculate_dominance_info (CDI_DOMINATORS);
387 /* Taking care of this degenerate case makes the rest of
388 this code simpler. */
389 if (n_basic_blocks == NUM_FIXED_BLOCKS)
391 init_loops_structure (loops, 1);
398 /* Count the number of loop headers. This should be the
399 same as the number of natural loops. */
400 headers = sbitmap_alloc (last_basic_block);
401 sbitmap_zero (headers);
408 header->loop_depth = 0;
410 /* If we have an abnormal predecessor, do not consider the
411 loop (not worth the problems). */
412 FOR_EACH_EDGE (e, ei, header->preds)
413 if (e->flags & EDGE_ABNORMAL)
418 FOR_EACH_EDGE (e, ei, header->preds)
420 basic_block latch = e->src;
422 gcc_assert (!(e->flags & EDGE_ABNORMAL));
424 /* Look for back edges where a predecessor is dominated
425 by this block. A natural loop has a single entry
426 node (header) that dominates all the nodes in the
427 loop. It also has single back edge to the header
428 from a latch node. */
429 if (latch != ENTRY_BLOCK_PTR
430 && dominated_by_p (CDI_DOMINATORS, latch, header))
432 /* Shared headers should be eliminated by now. */
433 SET_BIT (headers, header->index);
439 /* Allocate loop structures. */
440 init_loops_structure (loops, num_loops + 1);
442 /* Find and record information about all the natural loops
445 bb->loop_father = loops->tree_root;
449 /* Compute depth first search order of the CFG so that outer
450 natural loops will be found before inner natural loops. */
451 dfs_order = XNEWVEC (int, n_basic_blocks);
452 rc_order = XNEWVEC (int, n_basic_blocks);
453 pre_and_rev_post_order_compute (dfs_order, rc_order, false);
457 for (b = 0; b < n_basic_blocks - NUM_FIXED_BLOCKS; b++)
462 /* Search the nodes of the CFG in reverse completion order
463 so that we can find outer loops first. */
464 if (!TEST_BIT (headers, rc_order[b]))
467 header = BASIC_BLOCK (rc_order[b]);
469 loop = alloc_loop ();
470 VEC_quick_push (loop_p, loops->larray, loop);
472 loop->header = header;
473 loop->num = num_loops;
476 flow_loop_tree_node_add (header->loop_father, loop);
477 loop->num_nodes = flow_loop_nodes_find (loop->header, loop);
479 /* Look for the latch for this header block, if it has just a
481 FOR_EACH_EDGE (e, ei, header->preds)
483 basic_block latch = e->src;
485 if (flow_bb_inside_loop_p (loop, latch))
487 if (loop->latch != NULL)
489 /* More than one latch edge. */
502 sbitmap_free (headers);
506 return VEC_length (loop_p, loops->larray);
509 /* Ratio of frequencies of edges so that one of more latch edges is
510 considered to belong to inner loop with same header. */
511 #define HEAVY_EDGE_RATIO 8
513 /* Minimum number of samples for that we apply
514 find_subloop_latch_edge_by_profile heuristics. */
515 #define HEAVY_EDGE_MIN_SAMPLES 10
517 /* If the profile info is available, finds an edge in LATCHES that much more
518 frequent than the remaining edges. Returns such an edge, or NULL if we do
521 We do not use guessed profile here, only the measured one. The guessed
522 profile is usually too flat and unreliable for this (and it is mostly based
523 on the loop structure of the program, so it does not make much sense to
524 derive the loop structure from it). */
527 find_subloop_latch_edge_by_profile (VEC (edge, heap) *latches)
531 gcov_type mcount = 0, tcount = 0;
533 for (i = 0; VEC_iterate (edge, latches, i, e); i++)
535 if (e->count > mcount)
543 if (tcount < HEAVY_EDGE_MIN_SAMPLES
544 || (tcount - mcount) * HEAVY_EDGE_RATIO > tcount)
549 "Found latch edge %d -> %d using profile information.\n",
550 me->src->index, me->dest->index);
554 /* Among LATCHES, guesses a latch edge of LOOP corresponding to subloop, based
555 on the structure of induction variables. Returns this edge, or NULL if we
558 We are quite conservative, and look just for an obvious simple innermost
559 loop (which is the case where we would lose the most performance by not
560 disambiguating the loop). More precisely, we look for the following
561 situation: The source of the chosen latch edge dominates sources of all
562 the other latch edges. Additionally, the header does not contain a phi node
563 such that the argument from the chosen edge is equal to the argument from
567 find_subloop_latch_edge_by_ivs (struct loop *loop, VEC (edge, heap) *latches)
569 edge e, latch = VEC_index (edge, latches, 0);
574 /* Find the candidate for the latch edge. */
575 for (i = 1; VEC_iterate (edge, latches, i, e); i++)
576 if (dominated_by_p (CDI_DOMINATORS, latch->src, e->src))
579 /* Verify that it dominates all the latch edges. */
580 for (i = 0; VEC_iterate (edge, latches, i, e); i++)
581 if (!dominated_by_p (CDI_DOMINATORS, e->src, latch->src))
584 /* Check for a phi node that would deny that this is a latch edge of
586 for (phi = phi_nodes (loop->header); phi; phi = PHI_CHAIN (phi))
588 lop = PHI_ARG_DEF_FROM_EDGE (phi, latch);
590 /* Ignore the values that are not changed inside the subloop. */
591 if (TREE_CODE (lop) != SSA_NAME
592 || SSA_NAME_DEF_STMT (lop) == phi)
594 bb = bb_for_stmt (SSA_NAME_DEF_STMT (lop));
595 if (!bb || !flow_bb_inside_loop_p (loop, bb))
598 for (i = 0; VEC_iterate (edge, latches, i, e); i++)
600 && PHI_ARG_DEF_FROM_EDGE (phi, e) == lop)
606 "Found latch edge %d -> %d using iv structure.\n",
607 latch->src->index, latch->dest->index);
611 /* If we can determine that one of the several latch edges of LOOP behaves
612 as a latch edge of a separate subloop, returns this edge. Otherwise
616 find_subloop_latch_edge (struct loop *loop)
618 VEC (edge, heap) *latches = get_loop_latch_edges (loop);
621 if (VEC_length (edge, latches) > 1)
623 latch = find_subloop_latch_edge_by_profile (latches);
626 /* We consider ivs to guess the latch edge only in SSA. Perhaps we
627 should use cfghook for this, but it is hard to imagine it would
628 be useful elsewhere. */
629 && current_ir_type () == IR_GIMPLE)
630 latch = find_subloop_latch_edge_by_ivs (loop, latches);
633 VEC_free (edge, heap, latches);
637 /* Callback for make_forwarder_block. Returns true if the edge E is marked
638 in the set MFB_REIS_SET. */
640 static struct pointer_set_t *mfb_reis_set;
642 mfb_redirect_edges_in_set (edge e)
644 return pointer_set_contains (mfb_reis_set, e);
647 /* Creates a subloop of LOOP with latch edge LATCH. */
650 form_subloop (struct loop *loop, edge latch)
654 struct loop *new_loop;
656 mfb_reis_set = pointer_set_create ();
657 FOR_EACH_EDGE (e, ei, loop->header->preds)
660 pointer_set_insert (mfb_reis_set, e);
662 new_entry = make_forwarder_block (loop->header, mfb_redirect_edges_in_set,
664 pointer_set_destroy (mfb_reis_set);
666 loop->header = new_entry->src;
668 /* Find the blocks and subloops that belong to the new loop, and add it to
669 the appropriate place in the loop tree. */
670 new_loop = alloc_loop ();
671 new_loop->header = new_entry->dest;
672 new_loop->latch = latch->src;
673 add_loop (new_loop, loop);
676 /* Make all the latch edges of LOOP to go to a single forwarder block --
677 a new latch of LOOP. */
680 merge_latch_edges (struct loop *loop)
682 VEC (edge, heap) *latches = get_loop_latch_edges (loop);
686 gcc_assert (VEC_length (edge, latches) > 0);
688 if (VEC_length (edge, latches) == 1)
689 loop->latch = VEC_index (edge, latches, 0)->src;
693 fprintf (dump_file, "Merged latch edges of loop %d\n", loop->num);
695 mfb_reis_set = pointer_set_create ();
696 for (i = 0; VEC_iterate (edge, latches, i, e); i++)
697 pointer_set_insert (mfb_reis_set, e);
698 latch = make_forwarder_block (loop->header, mfb_redirect_edges_in_set,
700 pointer_set_destroy (mfb_reis_set);
702 loop->header = latch->dest;
703 loop->latch = latch->src;
706 VEC_free (edge, heap, latches);
709 /* LOOP may have several latch edges. Transform it into (possibly several)
710 loops with single latch edge. */
713 disambiguate_multiple_latches (struct loop *loop)
717 /* We eliminate the multiple latches by splitting the header to the forwarder
718 block F and the rest R, and redirecting the edges. There are two cases:
720 1) If there is a latch edge E that corresponds to a subloop (we guess
721 that based on profile -- if it is taken much more often than the
722 remaining edges; and on trees, using the information about induction
723 variables of the loops), we redirect E to R, all the remaining edges to
724 F, then rescan the loops and try again for the outer loop.
725 2) If there is no such edge, we redirect all latch edges to F, and the
726 entry edges to R, thus making F the single latch of the loop. */
729 fprintf (dump_file, "Disambiguating loop %d with multiple latches\n",
732 /* During latch merging, we may need to redirect the entry edges to a new
733 block. This would cause problems if the entry edge was the one from the
734 entry block. To avoid having to handle this case specially, split
736 e = find_edge (ENTRY_BLOCK_PTR, loop->header);
742 e = find_subloop_latch_edge (loop);
746 form_subloop (loop, e);
749 merge_latch_edges (loop);
752 /* Split loops with multiple latch edges. */
755 disambiguate_loops_with_multiple_latches (void)
760 FOR_EACH_LOOP (li, loop, 0)
763 disambiguate_multiple_latches (loop);
767 /* Return nonzero if basic block BB belongs to LOOP. */
769 flow_bb_inside_loop_p (const struct loop *loop, const basic_block bb)
771 struct loop *source_loop;
773 if (bb == ENTRY_BLOCK_PTR || bb == EXIT_BLOCK_PTR)
776 source_loop = bb->loop_father;
777 return loop == source_loop || flow_loop_nested_p (loop, source_loop);
780 /* Enumeration predicate for get_loop_body_with_size. */
782 glb_enum_p (basic_block bb, void *glb_loop)
784 struct loop *loop = (struct loop *) glb_loop;
785 return (bb != loop->header
786 && dominated_by_p (CDI_DOMINATORS, bb, loop->header));
789 /* Gets basic blocks of a LOOP. Header is the 0-th block, rest is in dfs
790 order against direction of edges from latch. Specially, if
791 header != latch, latch is the 1-st block. LOOP cannot be the fake
792 loop tree root, and its size must be at most MAX_SIZE. The blocks
793 in the LOOP body are stored to BODY, and the size of the LOOP is
797 get_loop_body_with_size (const struct loop *loop, basic_block *body,
800 return dfs_enumerate_from (loop->header, 1, glb_enum_p,
801 body, max_size, (void *) loop);
804 /* Gets basic blocks of a LOOP. Header is the 0-th block, rest is in dfs
805 order against direction of edges from latch. Specially, if
806 header != latch, latch is the 1-st block. */
809 get_loop_body (const struct loop *loop)
811 basic_block *body, bb;
814 gcc_assert (loop->num_nodes);
816 body = XCNEWVEC (basic_block, loop->num_nodes);
818 if (loop->latch == EXIT_BLOCK_PTR)
820 /* There may be blocks unreachable from EXIT_BLOCK, hence we need to
821 special-case the fake loop that contains the whole function. */
822 gcc_assert (loop->num_nodes == (unsigned) n_basic_blocks);
823 body[tv++] = loop->header;
824 body[tv++] = EXIT_BLOCK_PTR;
829 tv = get_loop_body_with_size (loop, body, loop->num_nodes);
831 gcc_assert (tv == loop->num_nodes);
835 /* Fills dominance descendants inside LOOP of the basic block BB into
836 array TOVISIT from index *TV. */
839 fill_sons_in_loop (const struct loop *loop, basic_block bb,
840 basic_block *tovisit, int *tv)
842 basic_block son, postpone = NULL;
844 tovisit[(*tv)++] = bb;
845 for (son = first_dom_son (CDI_DOMINATORS, bb);
847 son = next_dom_son (CDI_DOMINATORS, son))
849 if (!flow_bb_inside_loop_p (loop, son))
852 if (dominated_by_p (CDI_DOMINATORS, loop->latch, son))
857 fill_sons_in_loop (loop, son, tovisit, tv);
861 fill_sons_in_loop (loop, postpone, tovisit, tv);
864 /* Gets body of a LOOP (that must be different from the outermost loop)
865 sorted by dominance relation. Additionally, if a basic block s dominates
866 the latch, then only blocks dominated by s are be after it. */
869 get_loop_body_in_dom_order (const struct loop *loop)
871 basic_block *tovisit;
874 gcc_assert (loop->num_nodes);
876 tovisit = XCNEWVEC (basic_block, loop->num_nodes);
878 gcc_assert (loop->latch != EXIT_BLOCK_PTR);
881 fill_sons_in_loop (loop, loop->header, tovisit, &tv);
883 gcc_assert (tv == (int) loop->num_nodes);
888 /* Get body of a LOOP in breadth first sort order. */
891 get_loop_body_in_bfs_order (const struct loop *loop)
899 gcc_assert (loop->num_nodes);
900 gcc_assert (loop->latch != EXIT_BLOCK_PTR);
902 blocks = XCNEWVEC (basic_block, loop->num_nodes);
903 visited = BITMAP_ALLOC (NULL);
906 while (i < loop->num_nodes)
911 if (!bitmap_bit_p (visited, bb->index))
913 /* This basic block is now visited */
914 bitmap_set_bit (visited, bb->index);
918 FOR_EACH_EDGE (e, ei, bb->succs)
920 if (flow_bb_inside_loop_p (loop, e->dest))
922 if (!bitmap_bit_p (visited, e->dest->index))
924 bitmap_set_bit (visited, e->dest->index);
925 blocks[i++] = e->dest;
930 gcc_assert (i >= vc);
935 BITMAP_FREE (visited);
939 /* Hash function for struct loop_exit. */
942 loop_exit_hash (const void *ex)
944 const struct loop_exit *const exit = (const struct loop_exit *) ex;
946 return htab_hash_pointer (exit->e);
949 /* Equality function for struct loop_exit. Compares with edge. */
952 loop_exit_eq (const void *ex, const void *e)
954 const struct loop_exit *const exit = (const struct loop_exit *) ex;
959 /* Frees the list of loop exit descriptions EX. */
962 loop_exit_free (void *ex)
964 struct loop_exit *exit = (struct loop_exit *) ex, *next;
966 for (; exit; exit = next)
970 exit->next->prev = exit->prev;
971 exit->prev->next = exit->next;
977 /* Returns the list of records for E as an exit of a loop. */
979 static struct loop_exit *
980 get_exit_descriptions (edge e)
982 return (struct loop_exit *) htab_find_with_hash (current_loops->exits, e,
983 htab_hash_pointer (e));
986 /* Updates the lists of loop exits in that E appears.
987 If REMOVED is true, E is being removed, and we
988 just remove it from the lists of exits.
989 If NEW_EDGE is true and E is not a loop exit, we
990 do not try to remove it from loop exit lists. */
993 rescan_loop_exit (edge e, bool new_edge, bool removed)
996 struct loop_exit *exits = NULL, *exit;
997 struct loop *aloop, *cloop;
999 if ((current_loops->state & LOOPS_HAVE_RECORDED_EXITS) == 0)
1003 && e->src->loop_father != NULL
1004 && e->dest->loop_father != NULL
1005 && !flow_bb_inside_loop_p (e->src->loop_father, e->dest))
1007 cloop = find_common_loop (e->src->loop_father, e->dest->loop_father);
1008 for (aloop = e->src->loop_father;
1010 aloop = loop_outer (aloop))
1012 exit = GGC_NEW (struct loop_exit);
1015 exit->next = aloop->exits->next;
1016 exit->prev = aloop->exits;
1017 exit->next->prev = exit;
1018 exit->prev->next = exit;
1020 exit->next_e = exits;
1025 if (!exits && new_edge)
1028 slot = htab_find_slot_with_hash (current_loops->exits, e,
1029 htab_hash_pointer (e),
1030 exits ? INSERT : NO_INSERT);
1037 loop_exit_free (*slot);
1041 htab_clear_slot (current_loops->exits, slot);
1044 /* For each loop, record list of exit edges, and start maintaining these
1048 record_loop_exits (void)
1057 if (current_loops->state & LOOPS_HAVE_RECORDED_EXITS)
1059 current_loops->state |= LOOPS_HAVE_RECORDED_EXITS;
1061 gcc_assert (current_loops->exits == NULL);
1062 current_loops->exits = htab_create_alloc (2 * number_of_loops (),
1066 ggc_calloc, ggc_free);
1070 FOR_EACH_EDGE (e, ei, bb->succs)
1072 rescan_loop_exit (e, true, false);
1077 /* Dumps information about the exit in *SLOT to FILE.
1078 Callback for htab_traverse. */
1081 dump_recorded_exit (void **slot, void *file)
1083 struct loop_exit *exit = (struct loop_exit *) *slot;
1087 for (; exit != NULL; exit = exit->next_e)
1090 fprintf ((FILE*) file, "Edge %d->%d exits %u loops\n",
1091 e->src->index, e->dest->index, n);
1096 /* Dumps the recorded exits of loops to FILE. */
1098 extern void dump_recorded_exits (FILE *);
1100 dump_recorded_exits (FILE *file)
1102 if (!current_loops->exits)
1104 htab_traverse (current_loops->exits, dump_recorded_exit, file);
1107 /* Releases lists of loop exits. */
1110 release_recorded_exits (void)
1112 gcc_assert (current_loops->state & LOOPS_HAVE_RECORDED_EXITS);
1113 htab_delete (current_loops->exits);
1114 current_loops->exits = NULL;
1115 current_loops->state &= ~LOOPS_HAVE_RECORDED_EXITS;
1118 /* Returns the list of the exit edges of a LOOP. */
1121 get_loop_exit_edges (const struct loop *loop)
1123 VEC (edge, heap) *edges = NULL;
1128 struct loop_exit *exit;
1130 gcc_assert (loop->latch != EXIT_BLOCK_PTR);
1132 /* If we maintain the lists of exits, use them. Otherwise we must
1133 scan the body of the loop. */
1134 if (current_loops->state & LOOPS_HAVE_RECORDED_EXITS)
1136 for (exit = loop->exits->next; exit->e; exit = exit->next)
1137 VEC_safe_push (edge, heap, edges, exit->e);
1141 body = get_loop_body (loop);
1142 for (i = 0; i < loop->num_nodes; i++)
1143 FOR_EACH_EDGE (e, ei, body[i]->succs)
1145 if (!flow_bb_inside_loop_p (loop, e->dest))
1146 VEC_safe_push (edge, heap, edges, e);
1154 /* Counts the number of conditional branches inside LOOP. */
1157 num_loop_branches (const struct loop *loop)
1162 gcc_assert (loop->latch != EXIT_BLOCK_PTR);
1164 body = get_loop_body (loop);
1166 for (i = 0; i < loop->num_nodes; i++)
1167 if (EDGE_COUNT (body[i]->succs) >= 2)
1174 /* Adds basic block BB to LOOP. */
1176 add_bb_to_loop (basic_block bb, struct loop *loop)
1183 gcc_assert (bb->loop_father == NULL);
1184 bb->loop_father = loop;
1185 bb->loop_depth = loop_depth (loop);
1187 for (i = 0; VEC_iterate (loop_p, loop->superloops, i, ploop); i++)
1190 FOR_EACH_EDGE (e, ei, bb->succs)
1192 rescan_loop_exit (e, true, false);
1194 FOR_EACH_EDGE (e, ei, bb->preds)
1196 rescan_loop_exit (e, true, false);
1200 /* Remove basic block BB from loops. */
1202 remove_bb_from_loops (basic_block bb)
1205 struct loop *loop = bb->loop_father;
1210 gcc_assert (loop != NULL);
1212 for (i = 0; VEC_iterate (loop_p, loop->superloops, i, ploop); i++)
1214 bb->loop_father = NULL;
1217 FOR_EACH_EDGE (e, ei, bb->succs)
1219 rescan_loop_exit (e, false, true);
1221 FOR_EACH_EDGE (e, ei, bb->preds)
1223 rescan_loop_exit (e, false, true);
1227 /* Finds nearest common ancestor in loop tree for given loops. */
1229 find_common_loop (struct loop *loop_s, struct loop *loop_d)
1231 unsigned sdepth, ddepth;
1233 if (!loop_s) return loop_d;
1234 if (!loop_d) return loop_s;
1236 sdepth = loop_depth (loop_s);
1237 ddepth = loop_depth (loop_d);
1239 if (sdepth < ddepth)
1240 loop_d = VEC_index (loop_p, loop_d->superloops, sdepth);
1241 else if (sdepth > ddepth)
1242 loop_s = VEC_index (loop_p, loop_s->superloops, ddepth);
1244 while (loop_s != loop_d)
1246 loop_s = loop_outer (loop_s);
1247 loop_d = loop_outer (loop_d);
1252 /* Removes LOOP from structures and frees its data. */
1255 delete_loop (struct loop *loop)
1257 /* Remove the loop from structure. */
1258 flow_loop_tree_node_remove (loop);
1260 /* Remove loop from loops array. */
1261 VEC_replace (loop_p, current_loops->larray, loop->num, NULL);
1263 /* Free loop data. */
1264 flow_loop_free (loop);
1267 /* Cancels the LOOP; it must be innermost one. */
1270 cancel_loop (struct loop *loop)
1274 struct loop *outer = loop_outer (loop);
1276 gcc_assert (!loop->inner);
1278 /* Move blocks up one level (they should be removed as soon as possible). */
1279 bbs = get_loop_body (loop);
1280 for (i = 0; i < loop->num_nodes; i++)
1281 bbs[i]->loop_father = outer;
1286 /* Cancels LOOP and all its subloops. */
1288 cancel_loop_tree (struct loop *loop)
1291 cancel_loop_tree (loop->inner);
1295 /* Checks that information about loops is correct
1296 -- sizes of loops are all right
1297 -- results of get_loop_body really belong to the loop
1298 -- loop header have just single entry edge and single latch edge
1299 -- loop latches have only single successor that is header of their loop
1300 -- irreducible loops are correctly marked
1303 verify_loop_structure (void)
1305 unsigned *sizes, i, j;
1307 basic_block *bbs, bb;
1311 unsigned num = number_of_loops ();
1313 struct loop_exit *exit, *mexit;
1316 sizes = XCNEWVEC (unsigned, num);
1320 for (loop = bb->loop_father; loop; loop = loop_outer (loop))
1323 FOR_EACH_LOOP (li, loop, LI_INCLUDE_ROOT)
1327 if (loop->num_nodes != sizes[i])
1329 error ("size of loop %d should be %d, not %d",
1330 i, sizes[i], loop->num_nodes);
1335 /* Check get_loop_body. */
1336 FOR_EACH_LOOP (li, loop, 0)
1338 bbs = get_loop_body (loop);
1340 for (j = 0; j < loop->num_nodes; j++)
1341 if (!flow_bb_inside_loop_p (loop, bbs[j]))
1343 error ("bb %d do not belong to loop %d",
1344 bbs[j]->index, loop->num);
1350 /* Check headers and latches. */
1351 FOR_EACH_LOOP (li, loop, 0)
1355 if ((current_loops->state & LOOPS_HAVE_PREHEADERS)
1356 && EDGE_COUNT (loop->header->preds) != 2)
1358 error ("loop %d's header does not have exactly 2 entries", i);
1361 if (current_loops->state & LOOPS_HAVE_SIMPLE_LATCHES)
1363 if (!single_succ_p (loop->latch))
1365 error ("loop %d's latch does not have exactly 1 successor", i);
1368 if (single_succ (loop->latch) != loop->header)
1370 error ("loop %d's latch does not have header as successor", i);
1373 if (loop->latch->loop_father != loop)
1375 error ("loop %d's latch does not belong directly to it", i);
1379 if (loop->header->loop_father != loop)
1381 error ("loop %d's header does not belong directly to it", i);
1384 if ((current_loops->state & LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
1385 && (loop_latch_edge (loop)->flags & EDGE_IRREDUCIBLE_LOOP))
1387 error ("loop %d's latch is marked as part of irreducible region", i);
1392 /* Check irreducible loops. */
1393 if (current_loops->state & LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
1395 /* Record old info. */
1396 irreds = sbitmap_alloc (last_basic_block);
1400 if (bb->flags & BB_IRREDUCIBLE_LOOP)
1401 SET_BIT (irreds, bb->index);
1403 RESET_BIT (irreds, bb->index);
1404 FOR_EACH_EDGE (e, ei, bb->succs)
1405 if (e->flags & EDGE_IRREDUCIBLE_LOOP)
1406 e->flags |= EDGE_ALL_FLAGS + 1;
1410 mark_irreducible_loops ();
1417 if ((bb->flags & BB_IRREDUCIBLE_LOOP)
1418 && !TEST_BIT (irreds, bb->index))
1420 error ("basic block %d should be marked irreducible", bb->index);
1423 else if (!(bb->flags & BB_IRREDUCIBLE_LOOP)
1424 && TEST_BIT (irreds, bb->index))
1426 error ("basic block %d should not be marked irreducible", bb->index);
1429 FOR_EACH_EDGE (e, ei, bb->succs)
1431 if ((e->flags & EDGE_IRREDUCIBLE_LOOP)
1432 && !(e->flags & (EDGE_ALL_FLAGS + 1)))
1434 error ("edge from %d to %d should be marked irreducible",
1435 e->src->index, e->dest->index);
1438 else if (!(e->flags & EDGE_IRREDUCIBLE_LOOP)
1439 && (e->flags & (EDGE_ALL_FLAGS + 1)))
1441 error ("edge from %d to %d should not be marked irreducible",
1442 e->src->index, e->dest->index);
1445 e->flags &= ~(EDGE_ALL_FLAGS + 1);
1451 /* Check the recorded loop exits. */
1452 FOR_EACH_LOOP (li, loop, 0)
1454 if (!loop->exits || loop->exits->e != NULL)
1456 error ("corrupted head of the exits list of loop %d",
1462 /* Check that the list forms a cycle, and all elements except
1463 for the head are nonnull. */
1464 for (mexit = loop->exits, exit = mexit->next, i = 0;
1465 exit->e && exit != mexit;
1469 mexit = mexit->next;
1472 if (exit != loop->exits)
1474 error ("corrupted exits list of loop %d", loop->num);
1479 if ((current_loops->state & LOOPS_HAVE_RECORDED_EXITS) == 0)
1481 if (loop->exits->next != loop->exits)
1483 error ("nonempty exits list of loop %d, but exits are not recorded",
1490 if (current_loops->state & LOOPS_HAVE_RECORDED_EXITS)
1492 unsigned n_exits = 0, eloops;
1494 memset (sizes, 0, sizeof (unsigned) * num);
1498 if (bb->loop_father == current_loops->tree_root)
1500 FOR_EACH_EDGE (e, ei, bb->succs)
1502 if (flow_bb_inside_loop_p (bb->loop_father, e->dest))
1506 exit = get_exit_descriptions (e);
1509 error ("Exit %d->%d not recorded",
1510 e->src->index, e->dest->index);
1514 for (; exit; exit = exit->next_e)
1517 for (loop = bb->loop_father;
1518 loop != e->dest->loop_father;
1519 loop = loop_outer (loop))
1527 error ("Wrong list of exited loops for edge %d->%d",
1528 e->src->index, e->dest->index);
1534 if (n_exits != htab_elements (current_loops->exits))
1536 error ("Too many loop exits recorded");
1540 FOR_EACH_LOOP (li, loop, 0)
1543 for (exit = loop->exits->next; exit->e; exit = exit->next)
1545 if (eloops != sizes[loop->num])
1547 error ("%d exits recorded for loop %d (having %d exits)",
1548 eloops, loop->num, sizes[loop->num]);
1559 /* Returns latch edge of LOOP. */
1561 loop_latch_edge (const struct loop *loop)
1563 return find_edge (loop->latch, loop->header);
1566 /* Returns preheader edge of LOOP. */
1568 loop_preheader_edge (const struct loop *loop)
1573 gcc_assert ((current_loops->state & LOOPS_HAVE_PREHEADERS) != 0);
1575 FOR_EACH_EDGE (e, ei, loop->header->preds)
1576 if (e->src != loop->latch)
1582 /* Returns true if E is an exit of LOOP. */
1585 loop_exit_edge_p (const struct loop *loop, edge e)
1587 return (flow_bb_inside_loop_p (loop, e->src)
1588 && !flow_bb_inside_loop_p (loop, e->dest));
1591 /* Returns the single exit edge of LOOP, or NULL if LOOP has either no exit
1592 or more than one exit. If loops do not have the exits recorded, NULL
1593 is returned always. */
1596 single_exit (const struct loop *loop)
1598 struct loop_exit *exit = loop->exits->next;
1600 if ((current_loops->state & LOOPS_HAVE_RECORDED_EXITS) == 0)
1603 if (exit->e && exit->next == loop->exits)