1 /* DDG - Data Dependence Graph implementation.
2 Copyright (C) 2004, 2005, 2006, 2007
3 Free Software Foundation, Inc.
4 Contributed by Ayal Zaks and Mustafa Hagog <zaks,mustafa@il.ibm.com>
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
25 #include "coretypes.h"
30 #include "hard-reg-set.h"
34 #include "insn-config.h"
35 #include "insn-attr.h"
38 #include "sched-int.h"
40 #include "cfglayout.h"
47 /* A flag indicating that a ddg edge belongs to an SCC or not. */
48 enum edge_flag {NOT_IN_SCC = 0, IN_SCC};
50 /* Forward declarations. */
51 static void add_backarc_to_ddg (ddg_ptr, ddg_edge_ptr);
52 static void add_backarc_to_scc (ddg_scc_ptr, ddg_edge_ptr);
53 static void add_scc_to_ddg (ddg_all_sccs_ptr, ddg_scc_ptr);
54 static void create_ddg_dep_from_intra_loop_link (ddg_ptr, ddg_node_ptr,
56 static void create_ddg_dep_no_link (ddg_ptr, ddg_node_ptr, ddg_node_ptr,
57 dep_type, dep_data_type, int);
58 static ddg_edge_ptr create_ddg_edge (ddg_node_ptr, ddg_node_ptr, dep_type,
59 dep_data_type, int, int);
60 static void add_edge_to_ddg (ddg_ptr g, ddg_edge_ptr);
62 /* Auxiliary variable for mem_read_insn_p/mem_write_insn_p. */
63 static bool mem_ref_p;
65 /* Auxiliary function for mem_read_insn_p. */
67 mark_mem_use (rtx *x, void *data ATTRIBUTE_UNUSED)
74 /* Auxiliary function for mem_read_insn_p. */
76 mark_mem_use_1 (rtx *x, void *data)
78 for_each_rtx (x, mark_mem_use, data);
81 /* Returns nonzero if INSN reads from memory. */
83 mem_read_insn_p (rtx insn)
86 note_uses (&PATTERN (insn), mark_mem_use_1, NULL);
91 mark_mem_store (rtx loc, const_rtx setter ATTRIBUTE_UNUSED, void *data ATTRIBUTE_UNUSED)
97 /* Returns nonzero if INSN writes to memory. */
99 mem_write_insn_p (rtx insn)
102 note_stores (PATTERN (insn), mark_mem_store, NULL);
106 /* Returns nonzero if X has access to memory. */
108 rtx_mem_access_p (rtx x)
121 fmt = GET_RTX_FORMAT (code);
122 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
126 if (rtx_mem_access_p (XEXP (x, i)))
129 else if (fmt[i] == 'E')
130 for (j = 0; j < XVECLEN (x, i); j++)
132 if (rtx_mem_access_p (XVECEXP (x, i, j)))
139 /* Returns nonzero if INSN reads to or writes from memory. */
141 mem_access_insn_p (rtx insn)
143 return rtx_mem_access_p (PATTERN (insn));
146 /* Computes the dependence parameters (latency, distance etc.), creates
147 a ddg_edge and adds it to the given DDG. */
149 create_ddg_dep_from_intra_loop_link (ddg_ptr g, ddg_node_ptr src_node,
150 ddg_node_ptr dest_node, dep_t link)
153 int latency, distance = 0;
154 dep_type t = TRUE_DEP;
155 dep_data_type dt = (mem_access_insn_p (src_node->insn)
156 && mem_access_insn_p (dest_node->insn) ? MEM_DEP
158 gcc_assert (src_node->cuid < dest_node->cuid);
161 /* Note: REG_DEP_ANTI applies to MEM ANTI_DEP as well!! */
162 if (DEP_TYPE (link) == REG_DEP_ANTI)
164 else if (DEP_TYPE (link) == REG_DEP_OUTPUT)
167 /* We currently choose not to create certain anti-deps edges and
168 compensate for that by generating reg-moves based on the life-range
169 analysis. The anti-deps that will be deleted are the ones which
170 have true-deps edges in the opposite direction (in other words
171 the kernel has only one def of the relevant register). TODO:
172 support the removal of all anti-deps edges, i.e. including those
173 whose register has multiple defs in the loop. */
174 if (flag_modulo_sched_allow_regmoves && (t == ANTI_DEP && dt == REG_DEP))
178 set = single_set (dest_node->insn);
181 int regno = REGNO (SET_DEST (set));
182 struct df_ref *first_def =
183 df_bb_regno_first_def_find (g->bb, regno);
184 struct df_rd_bb_info *bb_info = DF_RD_BB_INFO (g->bb);
186 if (bitmap_bit_p (bb_info->gen, first_def->id))
191 latency = dep_cost (link);
192 e = create_ddg_edge (src_node, dest_node, t, dt, latency, distance);
193 add_edge_to_ddg (g, e);
196 /* The same as the above function, but it doesn't require a link parameter. */
198 create_ddg_dep_no_link (ddg_ptr g, ddg_node_ptr from, ddg_node_ptr to,
199 dep_type d_t, dep_data_type d_dt, int distance)
203 enum reg_note dep_kind;
204 struct _dep _dep, *dep = &_dep;
207 dep_kind = REG_DEP_ANTI;
208 else if (d_t == OUTPUT_DEP)
209 dep_kind = REG_DEP_OUTPUT;
212 gcc_assert (d_t == TRUE_DEP);
214 dep_kind = REG_DEP_TRUE;
217 init_dep (dep, from->insn, to->insn, dep_kind);
221 e = create_ddg_edge (from, to, d_t, d_dt, l, distance);
223 add_backarc_to_ddg (g, e);
225 add_edge_to_ddg (g, e);
229 /* Given a downwards exposed register def LAST_DEF (which is the last
230 definition of that register in the bb), add inter-loop true dependences
231 to all its uses in the next iteration, an output dependence to the
232 first def of the same register (possibly itself) in the next iteration
233 and anti-dependences from its uses in the current iteration to the
234 first definition in the next iteration. */
236 add_cross_iteration_register_deps (ddg_ptr g, struct df_ref *last_def)
238 int regno = DF_REF_REGNO (last_def);
239 struct df_link *r_use;
240 int has_use_in_bb_p = false;
241 rtx def_insn = DF_REF_INSN (last_def);
242 ddg_node_ptr last_def_node = get_node_of_insn (g, def_insn);
243 ddg_node_ptr use_node;
244 #ifdef ENABLE_CHECKING
245 struct df_rd_bb_info *bb_info = DF_RD_BB_INFO (g->bb);
247 struct df_ref *first_def = df_bb_regno_first_def_find (g->bb, regno);
249 gcc_assert (last_def_node);
250 gcc_assert (first_def);
252 #ifdef ENABLE_CHECKING
253 if (last_def->id != first_def->id)
254 gcc_assert (!bitmap_bit_p (bb_info->gen, first_def->id));
257 /* Create inter-loop true dependences and anti dependences. */
258 for (r_use = DF_REF_CHAIN (last_def); r_use != NULL; r_use = r_use->next)
260 rtx use_insn = DF_REF_INSN (r_use->ref);
262 if (BLOCK_FOR_INSN (use_insn) != g->bb)
265 /* ??? Do not handle uses with DF_REF_IN_NOTE notes. */
266 use_node = get_node_of_insn (g, use_insn);
267 gcc_assert (use_node);
268 has_use_in_bb_p = true;
269 if (use_node->cuid <= last_def_node->cuid)
271 /* Add true deps from last_def to it's uses in the next
272 iteration. Any such upwards exposed use appears before
274 create_ddg_dep_no_link (g, last_def_node, use_node, TRUE_DEP,
279 /* Add anti deps from last_def's uses in the current iteration
280 to the first def in the next iteration. We do not add ANTI
281 dep when there is an intra-loop TRUE dep in the opposite
282 direction, but use regmoves to fix such disregarded ANTI
283 deps when broken. If the first_def reaches the USE then
284 there is such a dep. */
285 ddg_node_ptr first_def_node = get_node_of_insn (g,
288 gcc_assert (first_def_node);
290 if (last_def->id != first_def->id
291 || !flag_modulo_sched_allow_regmoves)
292 create_ddg_dep_no_link (g, use_node, first_def_node, ANTI_DEP,
297 /* Create an inter-loop output dependence between LAST_DEF (which is the
298 last def in its block, being downwards exposed) and the first def in
299 its block. Avoid creating a self output dependence. Avoid creating
300 an output dependence if there is a dependence path between the two
301 defs starting with a true dependence to a use which can be in the
302 next iteration; followed by an anti dependence of that use to the
303 first def (i.e. if there is a use between the two defs.) */
304 if (!has_use_in_bb_p)
306 ddg_node_ptr dest_node;
308 if (last_def->id == first_def->id)
311 dest_node = get_node_of_insn (g, first_def->insn);
312 gcc_assert (dest_node);
313 create_ddg_dep_no_link (g, last_def_node, dest_node,
314 OUTPUT_DEP, REG_DEP, 1);
317 /* Build inter-loop dependencies, by looking at DF analysis backwards. */
319 build_inter_loop_deps (ddg_ptr g)
322 struct df_rd_bb_info *rd_bb_info;
325 rd_bb_info = DF_RD_BB_INFO (g->bb);
327 /* Find inter-loop register output, true and anti deps. */
328 EXECUTE_IF_SET_IN_BITMAP (rd_bb_info->gen, 0, rd_num, bi)
330 struct df_ref *rd = DF_DEFS_GET (rd_num);
332 add_cross_iteration_register_deps (g, rd);
337 /* Given two nodes, analyze their RTL insns and add inter-loop mem deps
340 add_inter_loop_mem_dep (ddg_ptr g, ddg_node_ptr from, ddg_node_ptr to)
342 if (mem_write_insn_p (from->insn))
344 if (mem_read_insn_p (to->insn))
345 create_ddg_dep_no_link (g, from, to, TRUE_DEP, MEM_DEP, 1);
346 else if (from->cuid != to->cuid)
347 create_ddg_dep_no_link (g, from, to, OUTPUT_DEP, MEM_DEP, 1);
351 if (mem_read_insn_p (to->insn))
353 else if (from->cuid != to->cuid)
355 create_ddg_dep_no_link (g, from, to, ANTI_DEP, MEM_DEP, 1);
356 create_ddg_dep_no_link (g, to, from, TRUE_DEP, MEM_DEP, 1);
362 /* Perform intra-block Data Dependency analysis and connect the nodes in
363 the DDG. We assume the loop has a single basic block. */
365 build_intra_loop_deps (ddg_ptr g)
368 /* Hold the dependency analysis state during dependency calculations. */
369 struct deps tmp_deps;
372 /* Build the dependence information, using the sched_analyze function. */
374 init_deps (&tmp_deps);
376 /* Do the intra-block data dependence analysis for the given block. */
377 get_ebb_head_tail (g->bb, g->bb, &head, &tail);
378 sched_analyze (&tmp_deps, head, tail);
380 /* Build intra-loop data dependencies using the scheduler dependency
382 for (i = 0; i < g->num_nodes; i++)
384 ddg_node_ptr dest_node = &g->nodes[i];
385 sd_iterator_def sd_it;
388 if (! INSN_P (dest_node->insn))
391 FOR_EACH_DEP (dest_node->insn, SD_LIST_BACK, sd_it, dep)
393 ddg_node_ptr src_node = get_node_of_insn (g, DEP_PRO (dep));
398 create_ddg_dep_from_intra_loop_link (g, src_node, dest_node, dep);
401 /* If this insn modifies memory, add an edge to all insns that access
403 if (mem_access_insn_p (dest_node->insn))
407 for (j = 0; j <= i; j++)
409 ddg_node_ptr j_node = &g->nodes[j];
410 if (mem_access_insn_p (j_node->insn))
411 /* Don't bother calculating inter-loop dep if an intra-loop dep
413 if (! TEST_BIT (dest_node->successors, j))
414 add_inter_loop_mem_dep (g, dest_node, j_node);
419 /* Free the INSN_LISTs. */
420 finish_deps_global ();
421 free_deps (&tmp_deps);
423 /* Free dependencies. */
424 sched_free_deps (head, tail, false);
428 /* Given a basic block, create its DDG and return a pointer to a variable
429 of ddg type that represents it.
430 Initialize the ddg structure fields to the appropriate values. */
432 create_ddg (basic_block bb, int closing_branch_deps)
435 rtx insn, first_note;
439 g = (ddg_ptr) xcalloc (1, sizeof (struct ddg));
442 g->closing_branch_deps = closing_branch_deps;
444 /* Count the number of insns in the BB. */
445 for (insn = BB_HEAD (bb); insn != NEXT_INSN (BB_END (bb));
446 insn = NEXT_INSN (insn))
448 if (! INSN_P (insn) || GET_CODE (PATTERN (insn)) == USE)
451 if (mem_read_insn_p (insn))
453 if (mem_write_insn_p (insn))
458 /* There is nothing to do for this BB. */
465 /* Allocate the nodes array, and initialize the nodes. */
466 g->num_nodes = num_nodes;
467 g->nodes = (ddg_node_ptr) xcalloc (num_nodes, sizeof (struct ddg_node));
468 g->closing_branch = NULL;
470 first_note = NULL_RTX;
471 for (insn = BB_HEAD (bb); insn != NEXT_INSN (BB_END (bb));
472 insn = NEXT_INSN (insn))
476 if (! first_note && NOTE_P (insn)
477 && NOTE_KIND (insn) != NOTE_INSN_BASIC_BLOCK)
483 gcc_assert (!g->closing_branch);
484 g->closing_branch = &g->nodes[i];
486 else if (GET_CODE (PATTERN (insn)) == USE)
493 g->nodes[i].cuid = i;
494 g->nodes[i].successors = sbitmap_alloc (num_nodes);
495 sbitmap_zero (g->nodes[i].successors);
496 g->nodes[i].predecessors = sbitmap_alloc (num_nodes);
497 sbitmap_zero (g->nodes[i].predecessors);
498 g->nodes[i].first_note = (first_note ? first_note : insn);
499 g->nodes[i++].insn = insn;
500 first_note = NULL_RTX;
503 /* We must have found a branch in DDG. */
504 gcc_assert (g->closing_branch);
507 /* Build the data dependency graph. */
508 build_intra_loop_deps (g);
509 build_inter_loop_deps (g);
513 /* Free all the memory allocated for the DDG. */
522 for (i = 0; i < g->num_nodes; i++)
524 ddg_edge_ptr e = g->nodes[i].out;
528 ddg_edge_ptr next = e->next_out;
533 sbitmap_free (g->nodes[i].successors);
534 sbitmap_free (g->nodes[i].predecessors);
536 if (g->num_backarcs > 0)
543 print_ddg_edge (FILE *file, ddg_edge_ptr e)
559 fprintf (file, " [%d -(%c,%d,%d)-> %d] ", INSN_UID (e->src->insn),
560 dep_c, e->latency, e->distance, INSN_UID (e->dest->insn));
563 /* Print the DDG nodes with there in/out edges to the dump file. */
565 print_ddg (FILE *file, ddg_ptr g)
569 for (i = 0; i < g->num_nodes; i++)
573 fprintf (file, "Node num: %d\n", g->nodes[i].cuid);
574 print_rtl_single (file, g->nodes[i].insn);
575 fprintf (file, "OUT ARCS: ");
576 for (e = g->nodes[i].out; e; e = e->next_out)
577 print_ddg_edge (file, e);
579 fprintf (file, "\nIN ARCS: ");
580 for (e = g->nodes[i].in; e; e = e->next_in)
581 print_ddg_edge (file, e);
583 fprintf (file, "\n");
587 /* Print the given DDG in VCG format. */
589 vcg_print_ddg (FILE *file, ddg_ptr g)
593 fprintf (file, "graph: {\n");
594 for (src_cuid = 0; src_cuid < g->num_nodes; src_cuid++)
597 int src_uid = INSN_UID (g->nodes[src_cuid].insn);
599 fprintf (file, "node: {title: \"%d_%d\" info1: \"", src_cuid, src_uid);
600 print_rtl_single (file, g->nodes[src_cuid].insn);
601 fprintf (file, "\"}\n");
602 for (e = g->nodes[src_cuid].out; e; e = e->next_out)
604 int dst_uid = INSN_UID (e->dest->insn);
605 int dst_cuid = e->dest->cuid;
607 /* Give the backarcs a different color. */
609 fprintf (file, "backedge: {color: red ");
611 fprintf (file, "edge: { ");
613 fprintf (file, "sourcename: \"%d_%d\" ", src_cuid, src_uid);
614 fprintf (file, "targetname: \"%d_%d\" ", dst_cuid, dst_uid);
615 fprintf (file, "label: \"%d_%d\"}\n", e->latency, e->distance);
618 fprintf (file, "}\n");
621 /* Dump the sccs in SCCS. */
623 print_sccs (FILE *file, ddg_all_sccs_ptr sccs, ddg_ptr g)
626 sbitmap_iterator sbi;
632 fprintf (file, "\n;; Number of SCC nodes - %d\n", sccs->num_sccs);
633 for (i = 0; i < sccs->num_sccs; i++)
635 fprintf (file, "SCC number: %d\n", i);
636 EXECUTE_IF_SET_IN_SBITMAP (sccs->sccs[i]->nodes, 0, u, sbi)
638 fprintf (file, "insn num %d\n", u);
639 print_rtl_single (file, g->nodes[u].insn);
642 fprintf (file, "\n");
645 /* Create an edge and initialize it with given values. */
647 create_ddg_edge (ddg_node_ptr src, ddg_node_ptr dest,
648 dep_type t, dep_data_type dt, int l, int d)
650 ddg_edge_ptr e = (ddg_edge_ptr) xmalloc (sizeof (struct ddg_edge));
658 e->next_in = e->next_out = NULL;
663 /* Add the given edge to the in/out linked lists of the DDG nodes. */
665 add_edge_to_ddg (ddg_ptr g ATTRIBUTE_UNUSED, ddg_edge_ptr e)
667 ddg_node_ptr src = e->src;
668 ddg_node_ptr dest = e->dest;
670 /* Should have allocated the sbitmaps. */
671 gcc_assert (src->successors && dest->predecessors);
673 SET_BIT (src->successors, dest->cuid);
674 SET_BIT (dest->predecessors, src->cuid);
675 e->next_in = dest->in;
677 e->next_out = src->out;
683 /* Algorithm for computing the recurrence_length of an scc. We assume at
684 for now that cycles in the data dependence graph contain a single backarc.
685 This simplifies the algorithm, and can be generalized later. */
687 set_recurrence_length (ddg_scc_ptr scc, ddg_ptr g)
692 for (j = 0; j < scc->num_backarcs; j++)
694 ddg_edge_ptr backarc = scc->backarcs[j];
696 int distance = backarc->distance;
697 ddg_node_ptr src = backarc->dest;
698 ddg_node_ptr dest = backarc->src;
700 length = longest_simple_path (g, src->cuid, dest->cuid, scc->nodes);
703 /* fprintf (stderr, "Backarc not on simple cycle in SCC.\n"); */
706 length += backarc->latency;
707 result = MAX (result, (length / distance));
709 scc->recurrence_length = result;
712 /* Create a new SCC given the set of its nodes. Compute its recurrence_length
713 and mark edges that belong to this scc as IN_SCC. */
715 create_scc (ddg_ptr g, sbitmap nodes)
719 sbitmap_iterator sbi;
721 scc = (ddg_scc_ptr) xmalloc (sizeof (struct ddg_scc));
722 scc->backarcs = NULL;
723 scc->num_backarcs = 0;
724 scc->nodes = sbitmap_alloc (g->num_nodes);
725 sbitmap_copy (scc->nodes, nodes);
727 /* Mark the backarcs that belong to this SCC. */
728 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, u, sbi)
731 ddg_node_ptr n = &g->nodes[u];
733 for (e = n->out; e; e = e->next_out)
734 if (TEST_BIT (nodes, e->dest->cuid))
736 e->aux.count = IN_SCC;
738 add_backarc_to_scc (scc, e);
742 set_recurrence_length (scc, g);
746 /* Cleans the memory allocation of a given SCC. */
748 free_scc (ddg_scc_ptr scc)
753 sbitmap_free (scc->nodes);
754 if (scc->num_backarcs > 0)
755 free (scc->backarcs);
760 /* Add a given edge known to be a backarc to the given DDG. */
762 add_backarc_to_ddg (ddg_ptr g, ddg_edge_ptr e)
764 int size = (g->num_backarcs + 1) * sizeof (ddg_edge_ptr);
766 add_edge_to_ddg (g, e);
767 g->backarcs = (ddg_edge_ptr *) xrealloc (g->backarcs, size);
768 g->backarcs[g->num_backarcs++] = e;
771 /* Add backarc to an SCC. */
773 add_backarc_to_scc (ddg_scc_ptr scc, ddg_edge_ptr e)
775 int size = (scc->num_backarcs + 1) * sizeof (ddg_edge_ptr);
777 scc->backarcs = (ddg_edge_ptr *) xrealloc (scc->backarcs, size);
778 scc->backarcs[scc->num_backarcs++] = e;
781 /* Add the given SCC to the DDG. */
783 add_scc_to_ddg (ddg_all_sccs_ptr g, ddg_scc_ptr scc)
785 int size = (g->num_sccs + 1) * sizeof (ddg_scc_ptr);
787 g->sccs = (ddg_scc_ptr *) xrealloc (g->sccs, size);
788 g->sccs[g->num_sccs++] = scc;
791 /* Given the instruction INSN return the node that represents it. */
793 get_node_of_insn (ddg_ptr g, rtx insn)
797 for (i = 0; i < g->num_nodes; i++)
798 if (insn == g->nodes[i].insn)
803 /* Given a set OPS of nodes in the DDG, find the set of their successors
804 which are not in OPS, and set their bits in SUCC. Bits corresponding to
805 OPS are cleared from SUCC. Leaves the other bits in SUCC unchanged. */
807 find_successors (sbitmap succ, ddg_ptr g, sbitmap ops)
810 sbitmap_iterator sbi;
812 EXECUTE_IF_SET_IN_SBITMAP (ops, 0, i, sbi)
814 const sbitmap node_succ = NODE_SUCCESSORS (&g->nodes[i]);
815 sbitmap_a_or_b (succ, succ, node_succ);
818 /* We want those that are not in ops. */
819 sbitmap_difference (succ, succ, ops);
822 /* Given a set OPS of nodes in the DDG, find the set of their predecessors
823 which are not in OPS, and set their bits in PREDS. Bits corresponding to
824 OPS are cleared from PREDS. Leaves the other bits in PREDS unchanged. */
826 find_predecessors (sbitmap preds, ddg_ptr g, sbitmap ops)
829 sbitmap_iterator sbi;
831 EXECUTE_IF_SET_IN_SBITMAP (ops, 0, i, sbi)
833 const sbitmap node_preds = NODE_PREDECESSORS (&g->nodes[i]);
834 sbitmap_a_or_b (preds, preds, node_preds);
837 /* We want those that are not in ops. */
838 sbitmap_difference (preds, preds, ops);
842 /* Compare function to be passed to qsort to order the backarcs in descending
845 compare_sccs (const void *s1, const void *s2)
847 const int rec_l1 = (*(const ddg_scc_ptr *)s1)->recurrence_length;
848 const int rec_l2 = (*(const ddg_scc_ptr *)s2)->recurrence_length;
849 return ((rec_l2 > rec_l1) - (rec_l2 < rec_l1));
853 /* Order the backarcs in descending recMII order using compare_sccs. */
855 order_sccs (ddg_all_sccs_ptr g)
857 qsort (g->sccs, g->num_sccs, sizeof (ddg_scc_ptr),
858 (int (*) (const void *, const void *)) compare_sccs);
861 #ifdef ENABLE_CHECKING
862 /* Check that every node in SCCS belongs to exactly one strongly connected
863 component and that no element of SCCS is empty. */
865 check_sccs (ddg_all_sccs_ptr sccs, int num_nodes)
868 sbitmap tmp = sbitmap_alloc (num_nodes);
871 for (i = 0; i < sccs->num_sccs; i++)
873 gcc_assert (!sbitmap_empty_p (sccs->sccs[i]->nodes));
874 /* Verify that every node in sccs is in exactly one strongly
875 connected component. */
876 gcc_assert (!sbitmap_any_common_bits (tmp, sccs->sccs[i]->nodes));
877 sbitmap_a_or_b (tmp, tmp, sccs->sccs[i]->nodes);
883 /* Perform the Strongly Connected Components decomposing algorithm on the
884 DDG and return DDG_ALL_SCCS structure that contains them. */
886 create_ddg_all_sccs (ddg_ptr g)
889 int num_nodes = g->num_nodes;
890 sbitmap from = sbitmap_alloc (num_nodes);
891 sbitmap to = sbitmap_alloc (num_nodes);
892 sbitmap scc_nodes = sbitmap_alloc (num_nodes);
893 ddg_all_sccs_ptr sccs = (ddg_all_sccs_ptr)
894 xmalloc (sizeof (struct ddg_all_sccs));
900 for (i = 0; i < g->num_backarcs; i++)
903 ddg_edge_ptr backarc = g->backarcs[i];
904 ddg_node_ptr src = backarc->src;
905 ddg_node_ptr dest = backarc->dest;
907 /* If the backarc already belongs to an SCC, continue. */
908 if (backarc->aux.count == IN_SCC)
911 sbitmap_zero (scc_nodes);
914 SET_BIT (from, dest->cuid);
915 SET_BIT (to, src->cuid);
917 if (find_nodes_on_paths (scc_nodes, g, from, to))
919 scc = create_scc (g, scc_nodes);
920 add_scc_to_ddg (sccs, scc);
926 sbitmap_free (scc_nodes);
927 #ifdef ENABLE_CHECKING
928 check_sccs (sccs, num_nodes);
933 /* Frees the memory allocated for all SCCs of the DDG, but keeps the DDG. */
935 free_ddg_all_sccs (ddg_all_sccs_ptr all_sccs)
942 for (i = 0; i < all_sccs->num_sccs; i++)
943 free_scc (all_sccs->sccs[i]);
949 /* Given FROM - a bitmap of source nodes - and TO - a bitmap of destination
950 nodes - find all nodes that lie on paths from FROM to TO (not excluding
951 nodes from FROM and TO). Return nonzero if nodes exist. */
953 find_nodes_on_paths (sbitmap result, ddg_ptr g, sbitmap from, sbitmap to)
958 int num_nodes = g->num_nodes;
959 sbitmap_iterator sbi;
961 sbitmap workset = sbitmap_alloc (num_nodes);
962 sbitmap reachable_from = sbitmap_alloc (num_nodes);
963 sbitmap reach_to = sbitmap_alloc (num_nodes);
964 sbitmap tmp = sbitmap_alloc (num_nodes);
966 sbitmap_copy (reachable_from, from);
967 sbitmap_copy (tmp, from);
973 sbitmap_copy (workset, tmp);
975 EXECUTE_IF_SET_IN_SBITMAP (workset, 0, u, sbi)
978 ddg_node_ptr u_node = &g->nodes[u];
980 for (e = u_node->out; e != (ddg_edge_ptr) 0; e = e->next_out)
982 ddg_node_ptr v_node = e->dest;
983 int v = v_node->cuid;
985 if (!TEST_BIT (reachable_from, v))
987 SET_BIT (reachable_from, v);
995 sbitmap_copy (reach_to, to);
996 sbitmap_copy (tmp, to);
1002 sbitmap_copy (workset, tmp);
1004 EXECUTE_IF_SET_IN_SBITMAP (workset, 0, u, sbi)
1007 ddg_node_ptr u_node = &g->nodes[u];
1009 for (e = u_node->in; e != (ddg_edge_ptr) 0; e = e->next_in)
1011 ddg_node_ptr v_node = e->src;
1012 int v = v_node->cuid;
1014 if (!TEST_BIT (reach_to, v))
1016 SET_BIT (reach_to, v);
1024 answer = sbitmap_a_and_b_cg (result, reachable_from, reach_to);
1025 sbitmap_free (workset);
1026 sbitmap_free (reachable_from);
1027 sbitmap_free (reach_to);
1033 /* Updates the counts of U_NODE's successors (that belong to NODES) to be
1034 at-least as large as the count of U_NODE plus the latency between them.
1035 Sets a bit in TMP for each successor whose count was changed (increased).
1036 Returns nonzero if any count was changed. */
1038 update_dist_to_successors (ddg_node_ptr u_node, sbitmap nodes, sbitmap tmp)
1043 for (e = u_node->out; e; e = e->next_out)
1045 ddg_node_ptr v_node = e->dest;
1046 int v = v_node->cuid;
1048 if (TEST_BIT (nodes, v)
1049 && (e->distance == 0)
1050 && (v_node->aux.count < u_node->aux.count + e->latency))
1052 v_node->aux.count = u_node->aux.count + e->latency;
1061 /* Find the length of a longest path from SRC to DEST in G,
1062 going only through NODES, and disregarding backarcs. */
1064 longest_simple_path (struct ddg * g, int src, int dest, sbitmap nodes)
1070 int num_nodes = g->num_nodes;
1071 sbitmap workset = sbitmap_alloc (num_nodes);
1072 sbitmap tmp = sbitmap_alloc (num_nodes);
1075 /* Data will hold the distance of the longest path found so far from
1076 src to each node. Initialize to -1 = less than minimum. */
1077 for (i = 0; i < g->num_nodes; i++)
1078 g->nodes[i].aux.count = -1;
1079 g->nodes[src].aux.count = 0;
1086 sbitmap_iterator sbi;
1089 sbitmap_copy (workset, tmp);
1091 EXECUTE_IF_SET_IN_SBITMAP (workset, 0, u, sbi)
1093 ddg_node_ptr u_node = &g->nodes[u];
1095 change |= update_dist_to_successors (u_node, nodes, tmp);
1098 result = g->nodes[dest].aux.count;
1099 sbitmap_free (workset);