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 /* Find all the natural loops in the function and save in LOOPS structure and
347 recalculate loop_depth information in basic block structures.
348 Return the number of natural loops found. */
351 flow_loops_find (struct loops *loops)
363 memset (loops, 0, sizeof *loops);
365 /* Taking care of this degenerate case makes the rest of
366 this code simpler. */
367 if (n_basic_blocks == NUM_FIXED_BLOCKS)
373 /* Ensure that the dominators are computed. */
374 calculate_dominance_info (CDI_DOMINATORS);
376 /* Count the number of loop headers. This should be the
377 same as the number of natural loops. */
378 headers = sbitmap_alloc (last_basic_block);
379 sbitmap_zero (headers);
386 header->loop_depth = 0;
388 /* If we have an abnormal predecessor, do not consider the
389 loop (not worth the problems). */
390 FOR_EACH_EDGE (e, ei, header->preds)
391 if (e->flags & EDGE_ABNORMAL)
396 FOR_EACH_EDGE (e, ei, header->preds)
398 basic_block latch = e->src;
400 gcc_assert (!(e->flags & EDGE_ABNORMAL));
402 /* Look for back edges where a predecessor is dominated
403 by this block. A natural loop has a single entry
404 node (header) that dominates all the nodes in the
405 loop. It also has single back edge to the header
406 from a latch node. */
407 if (latch != ENTRY_BLOCK_PTR
408 && dominated_by_p (CDI_DOMINATORS, latch, header))
410 /* Shared headers should be eliminated by now. */
411 SET_BIT (headers, header->index);
417 /* Allocate loop structures. */
418 loops->larray = VEC_alloc (loop_p, gc, num_loops + 1);
420 /* Dummy loop containing whole function. */
421 root = alloc_loop ();
422 root->num_nodes = n_basic_blocks;
423 root->latch = EXIT_BLOCK_PTR;
424 root->header = ENTRY_BLOCK_PTR;
425 ENTRY_BLOCK_PTR->loop_father = root;
426 EXIT_BLOCK_PTR->loop_father = root;
428 VEC_quick_push (loop_p, loops->larray, root);
429 loops->tree_root = root;
431 /* Find and record information about all the natural loops
434 bb->loop_father = loops->tree_root;
438 /* Compute depth first search order of the CFG so that outer
439 natural loops will be found before inner natural loops. */
440 dfs_order = XNEWVEC (int, n_basic_blocks);
441 rc_order = XNEWVEC (int, n_basic_blocks);
442 pre_and_rev_post_order_compute (dfs_order, rc_order, false);
446 for (b = 0; b < n_basic_blocks - NUM_FIXED_BLOCKS; b++)
451 /* Search the nodes of the CFG in reverse completion order
452 so that we can find outer loops first. */
453 if (!TEST_BIT (headers, rc_order[b]))
456 header = BASIC_BLOCK (rc_order[b]);
458 loop = alloc_loop ();
459 VEC_quick_push (loop_p, loops->larray, loop);
461 loop->header = header;
462 loop->num = num_loops;
465 flow_loop_tree_node_add (header->loop_father, loop);
466 loop->num_nodes = flow_loop_nodes_find (loop->header, loop);
468 /* Look for the latch for this header block, if it has just a
470 FOR_EACH_EDGE (e, ei, header->preds)
472 basic_block latch = e->src;
474 if (flow_bb_inside_loop_p (loop, latch))
476 if (loop->latch != NULL)
478 /* More than one latch edge. */
491 sbitmap_free (headers);
495 return VEC_length (loop_p, loops->larray);
498 /* Ratio of frequencies of edges so that one of more latch edges is
499 considered to belong to inner loop with same header. */
500 #define HEAVY_EDGE_RATIO 8
502 /* Minimum number of samples for that we apply
503 find_subloop_latch_edge_by_profile heuristics. */
504 #define HEAVY_EDGE_MIN_SAMPLES 10
506 /* If the profile info is available, finds an edge in LATCHES that much more
507 frequent than the remaining edges. Returns such an edge, or NULL if we do
510 We do not use guessed profile here, only the measured one. The guessed
511 profile is usually too flat and unreliable for this (and it is mostly based
512 on the loop structure of the program, so it does not make much sense to
513 derive the loop structure from it). */
516 find_subloop_latch_edge_by_profile (VEC (edge, heap) *latches)
520 gcov_type mcount = 0, tcount = 0;
522 for (i = 0; VEC_iterate (edge, latches, i, e); i++)
524 if (e->count > mcount)
532 if (tcount < HEAVY_EDGE_MIN_SAMPLES
533 || (tcount - mcount) * HEAVY_EDGE_RATIO > tcount)
538 "Found latch edge %d -> %d using profile information.\n",
539 me->src->index, me->dest->index);
543 /* Among LATCHES, guesses a latch edge of LOOP corresponding to subloop, based
544 on the structure of induction variables. Returns this edge, or NULL if we
547 We are quite conservative, and look just for an obvious simple innermost
548 loop (which is the case where we would lose the most performance by not
549 disambiguating the loop). More precisely, we look for the following
550 situation: The source of the chosen latch edge dominates sources of all
551 the other latch edges. Additionally, the header does not contain a phi node
552 such that the argument from the chosen edge is equal to the argument from
556 find_subloop_latch_edge_by_ivs (struct loop *loop, VEC (edge, heap) *latches)
558 edge e, latch = VEC_index (edge, latches, 0);
563 /* Find the candidate for the latch edge. */
564 for (i = 1; VEC_iterate (edge, latches, i, e); i++)
565 if (dominated_by_p (CDI_DOMINATORS, latch->src, e->src))
568 /* Verify that it dominates all the latch edges. */
569 for (i = 0; VEC_iterate (edge, latches, i, e); i++)
570 if (!dominated_by_p (CDI_DOMINATORS, e->src, latch->src))
573 /* Check for a phi node that would deny that this is a latch edge of
575 for (phi = phi_nodes (loop->header); phi; phi = PHI_CHAIN (phi))
577 lop = PHI_ARG_DEF_FROM_EDGE (phi, latch);
579 /* Ignore the values that are not changed inside the subloop. */
580 if (TREE_CODE (lop) != SSA_NAME
581 || SSA_NAME_DEF_STMT (lop) == phi)
583 bb = bb_for_stmt (SSA_NAME_DEF_STMT (lop));
584 if (!bb || !flow_bb_inside_loop_p (loop, bb))
587 for (i = 0; VEC_iterate (edge, latches, i, e); i++)
589 && PHI_ARG_DEF_FROM_EDGE (phi, e) == lop)
595 "Found latch edge %d -> %d using iv structure.\n",
596 latch->src->index, latch->dest->index);
600 /* If we can determine that one of the several latch edges of LOOP behaves
601 as a latch edge of a separate subloop, returns this edge. Otherwise
605 find_subloop_latch_edge (struct loop *loop)
607 VEC (edge, heap) *latches = get_loop_latch_edges (loop);
610 if (VEC_length (edge, latches) > 1)
612 latch = find_subloop_latch_edge_by_profile (latches);
615 /* We consider ivs to guess the latch edge only in SSA. Perhaps we
616 should use cfghook for this, but it is hard to imagine it would
617 be useful elsewhere. */
618 && current_ir_type () == IR_GIMPLE)
619 latch = find_subloop_latch_edge_by_ivs (loop, latches);
622 VEC_free (edge, heap, latches);
626 /* Callback for make_forwarder_block. Returns true if the edge E is marked
627 in the set MFB_REIS_SET. */
629 static struct pointer_set_t *mfb_reis_set;
631 mfb_redirect_edges_in_set (edge e)
633 return pointer_set_contains (mfb_reis_set, e);
636 /* Creates a subloop of LOOP with latch edge LATCH. */
639 form_subloop (struct loop *loop, edge latch)
643 struct loop *new_loop;
645 mfb_reis_set = pointer_set_create ();
646 FOR_EACH_EDGE (e, ei, loop->header->preds)
649 pointer_set_insert (mfb_reis_set, e);
651 new_entry = make_forwarder_block (loop->header, mfb_redirect_edges_in_set,
653 pointer_set_destroy (mfb_reis_set);
655 loop->header = new_entry->src;
657 /* Find the blocks and subloops that belong to the new loop, and add it to
658 the appropriate place in the loop tree. */
659 new_loop = alloc_loop ();
660 new_loop->header = new_entry->dest;
661 new_loop->latch = latch->src;
662 add_loop (new_loop, loop);
665 /* Make all the latch edges of LOOP to go to a single forwarder block --
666 a new latch of LOOP. */
669 merge_latch_edges (struct loop *loop)
671 VEC (edge, heap) *latches = get_loop_latch_edges (loop);
675 gcc_assert (VEC_length (edge, latches) > 0);
677 if (VEC_length (edge, latches) == 1)
678 loop->latch = VEC_index (edge, latches, 0)->src;
682 fprintf (dump_file, "Merged latch edges of loop %d\n", loop->num);
684 mfb_reis_set = pointer_set_create ();
685 for (i = 0; VEC_iterate (edge, latches, i, e); i++)
686 pointer_set_insert (mfb_reis_set, e);
687 latch = make_forwarder_block (loop->header, mfb_redirect_edges_in_set,
689 pointer_set_destroy (mfb_reis_set);
691 loop->header = latch->dest;
692 loop->latch = latch->src;
695 VEC_free (edge, heap, latches);
698 /* LOOP may have several latch edges. Transform it into (possibly several)
699 loops with single latch edge. */
702 disambiguate_multiple_latches (struct loop *loop)
706 /* We eliminate the multiple latches by splitting the header to the forwarder
707 block F and the rest R, and redirecting the edges. There are two cases:
709 1) If there is a latch edge E that corresponds to a subloop (we guess
710 that based on profile -- if it is taken much more often than the
711 remaining edges; and on trees, using the information about induction
712 variables of the loops), we redirect E to R, all the remaining edges to
713 F, then rescan the loops and try again for the outer loop.
714 2) If there is no such edge, we redirect all latch edges to F, and the
715 entry edges to R, thus making F the single latch of the loop. */
718 fprintf (dump_file, "Disambiguating loop %d with multiple latches\n",
721 /* During latch merging, we may need to redirect the entry edges to a new
722 block. This would cause problems if the entry edge was the one from the
723 entry block. To avoid having to handle this case specially, split
725 e = find_edge (ENTRY_BLOCK_PTR, loop->header);
731 e = find_subloop_latch_edge (loop);
735 form_subloop (loop, e);
738 merge_latch_edges (loop);
741 /* Split loops with multiple latch edges. */
744 disambiguate_loops_with_multiple_latches (void)
749 FOR_EACH_LOOP (li, loop, 0)
752 disambiguate_multiple_latches (loop);
756 /* Return nonzero if basic block BB belongs to LOOP. */
758 flow_bb_inside_loop_p (const struct loop *loop, const basic_block bb)
760 struct loop *source_loop;
762 if (bb == ENTRY_BLOCK_PTR || bb == EXIT_BLOCK_PTR)
765 source_loop = bb->loop_father;
766 return loop == source_loop || flow_loop_nested_p (loop, source_loop);
769 /* Enumeration predicate for get_loop_body_with_size. */
771 glb_enum_p (basic_block bb, void *glb_loop)
773 struct loop *loop = (struct loop *) glb_loop;
774 return (bb != loop->header
775 && dominated_by_p (CDI_DOMINATORS, bb, loop->header));
778 /* Gets basic blocks of a LOOP. Header is the 0-th block, rest is in dfs
779 order against direction of edges from latch. Specially, if
780 header != latch, latch is the 1-st block. LOOP cannot be the fake
781 loop tree root, and its size must be at most MAX_SIZE. The blocks
782 in the LOOP body are stored to BODY, and the size of the LOOP is
786 get_loop_body_with_size (const struct loop *loop, basic_block *body,
789 return dfs_enumerate_from (loop->header, 1, glb_enum_p,
790 body, max_size, (void *) loop);
793 /* Gets basic blocks of a LOOP. Header is the 0-th block, rest is in dfs
794 order against direction of edges from latch. Specially, if
795 header != latch, latch is the 1-st block. */
798 get_loop_body (const struct loop *loop)
800 basic_block *body, bb;
803 gcc_assert (loop->num_nodes);
805 body = XCNEWVEC (basic_block, loop->num_nodes);
807 if (loop->latch == EXIT_BLOCK_PTR)
809 /* There may be blocks unreachable from EXIT_BLOCK, hence we need to
810 special-case the fake loop that contains the whole function. */
811 gcc_assert (loop->num_nodes == (unsigned) n_basic_blocks);
812 body[tv++] = loop->header;
813 body[tv++] = EXIT_BLOCK_PTR;
818 tv = get_loop_body_with_size (loop, body, loop->num_nodes);
820 gcc_assert (tv == loop->num_nodes);
824 /* Fills dominance descendants inside LOOP of the basic block BB into
825 array TOVISIT from index *TV. */
828 fill_sons_in_loop (const struct loop *loop, basic_block bb,
829 basic_block *tovisit, int *tv)
831 basic_block son, postpone = NULL;
833 tovisit[(*tv)++] = bb;
834 for (son = first_dom_son (CDI_DOMINATORS, bb);
836 son = next_dom_son (CDI_DOMINATORS, son))
838 if (!flow_bb_inside_loop_p (loop, son))
841 if (dominated_by_p (CDI_DOMINATORS, loop->latch, son))
846 fill_sons_in_loop (loop, son, tovisit, tv);
850 fill_sons_in_loop (loop, postpone, tovisit, tv);
853 /* Gets body of a LOOP (that must be different from the outermost loop)
854 sorted by dominance relation. Additionally, if a basic block s dominates
855 the latch, then only blocks dominated by s are be after it. */
858 get_loop_body_in_dom_order (const struct loop *loop)
860 basic_block *tovisit;
863 gcc_assert (loop->num_nodes);
865 tovisit = XCNEWVEC (basic_block, loop->num_nodes);
867 gcc_assert (loop->latch != EXIT_BLOCK_PTR);
870 fill_sons_in_loop (loop, loop->header, tovisit, &tv);
872 gcc_assert (tv == (int) loop->num_nodes);
877 /* Get body of a LOOP in breadth first sort order. */
880 get_loop_body_in_bfs_order (const struct loop *loop)
888 gcc_assert (loop->num_nodes);
889 gcc_assert (loop->latch != EXIT_BLOCK_PTR);
891 blocks = XCNEWVEC (basic_block, loop->num_nodes);
892 visited = BITMAP_ALLOC (NULL);
895 while (i < loop->num_nodes)
900 if (!bitmap_bit_p (visited, bb->index))
902 /* This basic block is now visited */
903 bitmap_set_bit (visited, bb->index);
907 FOR_EACH_EDGE (e, ei, bb->succs)
909 if (flow_bb_inside_loop_p (loop, e->dest))
911 if (!bitmap_bit_p (visited, e->dest->index))
913 bitmap_set_bit (visited, e->dest->index);
914 blocks[i++] = e->dest;
919 gcc_assert (i >= vc);
924 BITMAP_FREE (visited);
928 /* Hash function for struct loop_exit. */
931 loop_exit_hash (const void *ex)
933 struct loop_exit *exit = (struct loop_exit *) ex;
935 return htab_hash_pointer (exit->e);
938 /* Equality function for struct loop_exit. Compares with edge. */
941 loop_exit_eq (const void *ex, const void *e)
943 struct loop_exit *exit = (struct loop_exit *) ex;
948 /* Frees the list of loop exit descriptions EX. */
951 loop_exit_free (void *ex)
953 struct loop_exit *exit = (struct loop_exit *) ex, *next;
955 for (; exit; exit = next)
959 exit->next->prev = exit->prev;
960 exit->prev->next = exit->next;
966 /* Returns the list of records for E as an exit of a loop. */
968 static struct loop_exit *
969 get_exit_descriptions (edge e)
971 return (struct loop_exit *) htab_find_with_hash (current_loops->exits, e,
972 htab_hash_pointer (e));
975 /* Updates the lists of loop exits in that E appears.
976 If REMOVED is true, E is being removed, and we
977 just remove it from the lists of exits.
978 If NEW_EDGE is true and E is not a loop exit, we
979 do not try to remove it from loop exit lists. */
982 rescan_loop_exit (edge e, bool new_edge, bool removed)
985 struct loop_exit *exits = NULL, *exit;
986 struct loop *aloop, *cloop;
988 if ((current_loops->state & LOOPS_HAVE_RECORDED_EXITS) == 0)
992 && e->src->loop_father != NULL
993 && e->dest->loop_father != NULL
994 && !flow_bb_inside_loop_p (e->src->loop_father, e->dest))
996 cloop = find_common_loop (e->src->loop_father, e->dest->loop_father);
997 for (aloop = e->src->loop_father;
999 aloop = loop_outer (aloop))
1001 exit = GGC_NEW (struct loop_exit);
1004 exit->next = aloop->exits->next;
1005 exit->prev = aloop->exits;
1006 exit->next->prev = exit;
1007 exit->prev->next = exit;
1009 exit->next_e = exits;
1014 if (!exits && new_edge)
1017 slot = htab_find_slot_with_hash (current_loops->exits, e,
1018 htab_hash_pointer (e),
1019 exits ? INSERT : NO_INSERT);
1026 loop_exit_free (*slot);
1030 htab_clear_slot (current_loops->exits, slot);
1033 /* For each loop, record list of exit edges, and start maintaining these
1037 record_loop_exits (void)
1046 if (current_loops->state & LOOPS_HAVE_RECORDED_EXITS)
1048 current_loops->state |= LOOPS_HAVE_RECORDED_EXITS;
1050 gcc_assert (current_loops->exits == NULL);
1051 current_loops->exits = htab_create_alloc (2 * number_of_loops (),
1055 ggc_calloc, ggc_free);
1059 FOR_EACH_EDGE (e, ei, bb->succs)
1061 rescan_loop_exit (e, true, false);
1066 /* Dumps information about the exit in *SLOT to FILE.
1067 Callback for htab_traverse. */
1070 dump_recorded_exit (void **slot, void *file)
1072 struct loop_exit *exit = (struct loop_exit *) *slot;
1076 for (; exit != NULL; exit = exit->next_e)
1079 fprintf ((FILE*) file, "Edge %d->%d exits %u loops\n",
1080 e->src->index, e->dest->index, n);
1085 /* Dumps the recorded exits of loops to FILE. */
1087 extern void dump_recorded_exits (FILE *);
1089 dump_recorded_exits (FILE *file)
1091 if (!current_loops->exits)
1093 htab_traverse (current_loops->exits, dump_recorded_exit, file);
1096 /* Releases lists of loop exits. */
1099 release_recorded_exits (void)
1101 gcc_assert (current_loops->state & LOOPS_HAVE_RECORDED_EXITS);
1102 htab_delete (current_loops->exits);
1103 current_loops->exits = NULL;
1104 current_loops->state &= ~LOOPS_HAVE_RECORDED_EXITS;
1107 /* Returns the list of the exit edges of a LOOP. */
1110 get_loop_exit_edges (const struct loop *loop)
1112 VEC (edge, heap) *edges = NULL;
1117 struct loop_exit *exit;
1119 gcc_assert (loop->latch != EXIT_BLOCK_PTR);
1121 /* If we maintain the lists of exits, use them. Otherwise we must
1122 scan the body of the loop. */
1123 if (current_loops->state & LOOPS_HAVE_RECORDED_EXITS)
1125 for (exit = loop->exits->next; exit->e; exit = exit->next)
1126 VEC_safe_push (edge, heap, edges, exit->e);
1130 body = get_loop_body (loop);
1131 for (i = 0; i < loop->num_nodes; i++)
1132 FOR_EACH_EDGE (e, ei, body[i]->succs)
1134 if (!flow_bb_inside_loop_p (loop, e->dest))
1135 VEC_safe_push (edge, heap, edges, e);
1143 /* Counts the number of conditional branches inside LOOP. */
1146 num_loop_branches (const struct loop *loop)
1151 gcc_assert (loop->latch != EXIT_BLOCK_PTR);
1153 body = get_loop_body (loop);
1155 for (i = 0; i < loop->num_nodes; i++)
1156 if (EDGE_COUNT (body[i]->succs) >= 2)
1163 /* Adds basic block BB to LOOP. */
1165 add_bb_to_loop (basic_block bb, struct loop *loop)
1172 gcc_assert (bb->loop_father == NULL);
1173 bb->loop_father = loop;
1174 bb->loop_depth = loop_depth (loop);
1176 for (i = 0; VEC_iterate (loop_p, loop->superloops, i, ploop); i++)
1179 FOR_EACH_EDGE (e, ei, bb->succs)
1181 rescan_loop_exit (e, true, false);
1183 FOR_EACH_EDGE (e, ei, bb->preds)
1185 rescan_loop_exit (e, true, false);
1189 /* Remove basic block BB from loops. */
1191 remove_bb_from_loops (basic_block bb)
1194 struct loop *loop = bb->loop_father;
1199 gcc_assert (loop != NULL);
1201 for (i = 0; VEC_iterate (loop_p, loop->superloops, i, ploop); i++)
1203 bb->loop_father = NULL;
1206 FOR_EACH_EDGE (e, ei, bb->succs)
1208 rescan_loop_exit (e, false, true);
1210 FOR_EACH_EDGE (e, ei, bb->preds)
1212 rescan_loop_exit (e, false, true);
1216 /* Finds nearest common ancestor in loop tree for given loops. */
1218 find_common_loop (struct loop *loop_s, struct loop *loop_d)
1220 unsigned sdepth, ddepth;
1222 if (!loop_s) return loop_d;
1223 if (!loop_d) return loop_s;
1225 sdepth = loop_depth (loop_s);
1226 ddepth = loop_depth (loop_d);
1228 if (sdepth < ddepth)
1229 loop_d = VEC_index (loop_p, loop_d->superloops, sdepth);
1230 else if (sdepth > ddepth)
1231 loop_s = VEC_index (loop_p, loop_s->superloops, ddepth);
1233 while (loop_s != loop_d)
1235 loop_s = loop_outer (loop_s);
1236 loop_d = loop_outer (loop_d);
1241 /* Removes LOOP from structures and frees its data. */
1244 delete_loop (struct loop *loop)
1246 /* Remove the loop from structure. */
1247 flow_loop_tree_node_remove (loop);
1249 /* Remove loop from loops array. */
1250 VEC_replace (loop_p, current_loops->larray, loop->num, NULL);
1252 /* Free loop data. */
1253 flow_loop_free (loop);
1256 /* Cancels the LOOP; it must be innermost one. */
1259 cancel_loop (struct loop *loop)
1263 struct loop *outer = loop_outer (loop);
1265 gcc_assert (!loop->inner);
1267 /* Move blocks up one level (they should be removed as soon as possible). */
1268 bbs = get_loop_body (loop);
1269 for (i = 0; i < loop->num_nodes; i++)
1270 bbs[i]->loop_father = outer;
1275 /* Cancels LOOP and all its subloops. */
1277 cancel_loop_tree (struct loop *loop)
1280 cancel_loop_tree (loop->inner);
1284 /* Checks that information about loops is correct
1285 -- sizes of loops are all right
1286 -- results of get_loop_body really belong to the loop
1287 -- loop header have just single entry edge and single latch edge
1288 -- loop latches have only single successor that is header of their loop
1289 -- irreducible loops are correctly marked
1292 verify_loop_structure (void)
1294 unsigned *sizes, i, j;
1296 basic_block *bbs, bb;
1300 unsigned num = number_of_loops ();
1302 struct loop_exit *exit, *mexit;
1305 sizes = XCNEWVEC (unsigned, num);
1309 for (loop = bb->loop_father; loop; loop = loop_outer (loop))
1312 FOR_EACH_LOOP (li, loop, LI_INCLUDE_ROOT)
1316 if (loop->num_nodes != sizes[i])
1318 error ("size of loop %d should be %d, not %d",
1319 i, sizes[i], loop->num_nodes);
1324 /* Check get_loop_body. */
1325 FOR_EACH_LOOP (li, loop, 0)
1327 bbs = get_loop_body (loop);
1329 for (j = 0; j < loop->num_nodes; j++)
1330 if (!flow_bb_inside_loop_p (loop, bbs[j]))
1332 error ("bb %d do not belong to loop %d",
1333 bbs[j]->index, loop->num);
1339 /* Check headers and latches. */
1340 FOR_EACH_LOOP (li, loop, 0)
1344 if ((current_loops->state & LOOPS_HAVE_PREHEADERS)
1345 && EDGE_COUNT (loop->header->preds) != 2)
1347 error ("loop %d's header does not have exactly 2 entries", i);
1350 if (current_loops->state & LOOPS_HAVE_SIMPLE_LATCHES)
1352 if (!single_succ_p (loop->latch))
1354 error ("loop %d's latch does not have exactly 1 successor", i);
1357 if (single_succ (loop->latch) != loop->header)
1359 error ("loop %d's latch does not have header as successor", i);
1362 if (loop->latch->loop_father != loop)
1364 error ("loop %d's latch does not belong directly to it", i);
1368 if (loop->header->loop_father != loop)
1370 error ("loop %d's header does not belong directly to it", i);
1373 if ((current_loops->state & LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
1374 && (loop_latch_edge (loop)->flags & EDGE_IRREDUCIBLE_LOOP))
1376 error ("loop %d's latch is marked as part of irreducible region", i);
1381 /* Check irreducible loops. */
1382 if (current_loops->state & LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
1384 /* Record old info. */
1385 irreds = sbitmap_alloc (last_basic_block);
1389 if (bb->flags & BB_IRREDUCIBLE_LOOP)
1390 SET_BIT (irreds, bb->index);
1392 RESET_BIT (irreds, bb->index);
1393 FOR_EACH_EDGE (e, ei, bb->succs)
1394 if (e->flags & EDGE_IRREDUCIBLE_LOOP)
1395 e->flags |= EDGE_ALL_FLAGS + 1;
1399 mark_irreducible_loops ();
1406 if ((bb->flags & BB_IRREDUCIBLE_LOOP)
1407 && !TEST_BIT (irreds, bb->index))
1409 error ("basic block %d should be marked irreducible", bb->index);
1412 else if (!(bb->flags & BB_IRREDUCIBLE_LOOP)
1413 && TEST_BIT (irreds, bb->index))
1415 error ("basic block %d should not be marked irreducible", bb->index);
1418 FOR_EACH_EDGE (e, ei, bb->succs)
1420 if ((e->flags & EDGE_IRREDUCIBLE_LOOP)
1421 && !(e->flags & (EDGE_ALL_FLAGS + 1)))
1423 error ("edge from %d to %d should be marked irreducible",
1424 e->src->index, e->dest->index);
1427 else if (!(e->flags & EDGE_IRREDUCIBLE_LOOP)
1428 && (e->flags & (EDGE_ALL_FLAGS + 1)))
1430 error ("edge from %d to %d should not be marked irreducible",
1431 e->src->index, e->dest->index);
1434 e->flags &= ~(EDGE_ALL_FLAGS + 1);
1440 /* Check the recorded loop exits. */
1441 FOR_EACH_LOOP (li, loop, 0)
1443 if (!loop->exits || loop->exits->e != NULL)
1445 error ("corrupted head of the exits list of loop %d",
1451 /* Check that the list forms a cycle, and all elements except
1452 for the head are nonnull. */
1453 for (mexit = loop->exits, exit = mexit->next, i = 0;
1454 exit->e && exit != mexit;
1458 mexit = mexit->next;
1461 if (exit != loop->exits)
1463 error ("corrupted exits list of loop %d", loop->num);
1468 if ((current_loops->state & LOOPS_HAVE_RECORDED_EXITS) == 0)
1470 if (loop->exits->next != loop->exits)
1472 error ("nonempty exits list of loop %d, but exits are not recorded",
1479 if (current_loops->state & LOOPS_HAVE_RECORDED_EXITS)
1481 unsigned n_exits = 0, eloops;
1483 memset (sizes, 0, sizeof (unsigned) * num);
1487 if (bb->loop_father == current_loops->tree_root)
1489 FOR_EACH_EDGE (e, ei, bb->succs)
1491 if (flow_bb_inside_loop_p (bb->loop_father, e->dest))
1495 exit = get_exit_descriptions (e);
1498 error ("Exit %d->%d not recorded",
1499 e->src->index, e->dest->index);
1503 for (; exit; exit = exit->next_e)
1506 for (loop = bb->loop_father;
1507 loop != e->dest->loop_father;
1508 loop = loop_outer (loop))
1516 error ("Wrong list of exited loops for edge %d->%d",
1517 e->src->index, e->dest->index);
1523 if (n_exits != htab_elements (current_loops->exits))
1525 error ("Too many loop exits recorded");
1529 FOR_EACH_LOOP (li, loop, 0)
1532 for (exit = loop->exits->next; exit->e; exit = exit->next)
1534 if (eloops != sizes[loop->num])
1536 error ("%d exits recorded for loop %d (having %d exits)",
1537 eloops, loop->num, sizes[loop->num]);
1548 /* Returns latch edge of LOOP. */
1550 loop_latch_edge (const struct loop *loop)
1552 return find_edge (loop->latch, loop->header);
1555 /* Returns preheader edge of LOOP. */
1557 loop_preheader_edge (const struct loop *loop)
1562 gcc_assert ((current_loops->state & LOOPS_HAVE_PREHEADERS) != 0);
1564 FOR_EACH_EDGE (e, ei, loop->header->preds)
1565 if (e->src != loop->latch)
1571 /* Returns true if E is an exit of LOOP. */
1574 loop_exit_edge_p (const struct loop *loop, edge e)
1576 return (flow_bb_inside_loop_p (loop, e->src)
1577 && !flow_bb_inside_loop_p (loop, e->dest));
1580 /* Returns the single exit edge of LOOP, or NULL if LOOP has either no exit
1581 or more than one exit. If loops do not have the exits recorded, NULL
1582 is returned always. */
1585 single_exit (const struct loop *loop)
1587 struct loop_exit *exit = loop->exits->next;
1589 if ((current_loops->state & LOOPS_HAVE_RECORDED_EXITS) == 0)
1592 if (exit->e && exit->next == loop->exits)