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_KIND (link) == REG_DEP_ANTI)
164 else if (DEP_KIND (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;
373 /* Build the dependence information, using the sched_analyze function. */
375 init_deps (&tmp_deps);
377 /* Do the intra-block data dependence analysis for the given block. */
378 get_ebb_head_tail (g->bb, g->bb, &head, &tail);
379 sched_analyze (&tmp_deps, head, tail);
381 /* Build intra-loop data dependencies using the scheduler dependency
383 for (i = 0; i < g->num_nodes; i++)
385 ddg_node_ptr dest_node = &g->nodes[i];
387 if (! INSN_P (dest_node->insn))
390 FOR_EACH_DEP_LINK (link, INSN_BACK_DEPS (dest_node->insn))
392 dep_t dep = DEP_LINK_DEP (link);
393 ddg_node_ptr src_node = get_node_of_insn (g, DEP_PRO (dep));
399 create_ddg_dep_from_intra_loop_link (g, src_node, dest_node, dep);
402 /* If this insn modifies memory, add an edge to all insns that access
404 if (mem_access_insn_p (dest_node->insn))
408 for (j = 0; j <= i; j++)
410 ddg_node_ptr j_node = &g->nodes[j];
411 if (mem_access_insn_p (j_node->insn))
412 /* Don't bother calculating inter-loop dep if an intra-loop dep
414 if (! TEST_BIT (dest_node->successors, j))
415 add_inter_loop_mem_dep (g, dest_node, j_node);
420 /* Free the INSN_LISTs. */
421 finish_deps_global ();
422 free_deps (&tmp_deps);
426 /* Given a basic block, create its DDG and return a pointer to a variable
427 of ddg type that represents it.
428 Initialize the ddg structure fields to the appropriate values. */
430 create_ddg (basic_block bb, int closing_branch_deps)
433 rtx insn, first_note;
437 g = (ddg_ptr) xcalloc (1, sizeof (struct ddg));
440 g->closing_branch_deps = closing_branch_deps;
442 /* Count the number of insns in the BB. */
443 for (insn = BB_HEAD (bb); insn != NEXT_INSN (BB_END (bb));
444 insn = NEXT_INSN (insn))
446 if (! INSN_P (insn) || GET_CODE (PATTERN (insn)) == USE)
449 if (mem_read_insn_p (insn))
451 if (mem_write_insn_p (insn))
456 /* There is nothing to do for this BB. */
463 /* Allocate the nodes array, and initialize the nodes. */
464 g->num_nodes = num_nodes;
465 g->nodes = (ddg_node_ptr) xcalloc (num_nodes, sizeof (struct ddg_node));
466 g->closing_branch = NULL;
468 first_note = NULL_RTX;
469 for (insn = BB_HEAD (bb); insn != NEXT_INSN (BB_END (bb));
470 insn = NEXT_INSN (insn))
474 if (! first_note && NOTE_P (insn)
475 && NOTE_KIND (insn) != NOTE_INSN_BASIC_BLOCK)
481 gcc_assert (!g->closing_branch);
482 g->closing_branch = &g->nodes[i];
484 else if (GET_CODE (PATTERN (insn)) == USE)
491 g->nodes[i].cuid = i;
492 g->nodes[i].successors = sbitmap_alloc (num_nodes);
493 sbitmap_zero (g->nodes[i].successors);
494 g->nodes[i].predecessors = sbitmap_alloc (num_nodes);
495 sbitmap_zero (g->nodes[i].predecessors);
496 g->nodes[i].first_note = (first_note ? first_note : insn);
497 g->nodes[i++].insn = insn;
498 first_note = NULL_RTX;
501 /* We must have found a branch in DDG. */
502 gcc_assert (g->closing_branch);
505 /* Build the data dependency graph. */
506 build_intra_loop_deps (g);
507 build_inter_loop_deps (g);
511 /* Free all the memory allocated for the DDG. */
520 for (i = 0; i < g->num_nodes; i++)
522 ddg_edge_ptr e = g->nodes[i].out;
526 ddg_edge_ptr next = e->next_out;
531 sbitmap_free (g->nodes[i].successors);
532 sbitmap_free (g->nodes[i].predecessors);
534 if (g->num_backarcs > 0)
541 print_ddg_edge (FILE *file, ddg_edge_ptr e)
557 fprintf (file, " [%d -(%c,%d,%d)-> %d] ", INSN_UID (e->src->insn),
558 dep_c, e->latency, e->distance, INSN_UID (e->dest->insn));
561 /* Print the DDG nodes with there in/out edges to the dump file. */
563 print_ddg (FILE *file, ddg_ptr g)
567 for (i = 0; i < g->num_nodes; i++)
571 fprintf (file, "Node num: %d\n", g->nodes[i].cuid);
572 print_rtl_single (file, g->nodes[i].insn);
573 fprintf (file, "OUT ARCS: ");
574 for (e = g->nodes[i].out; e; e = e->next_out)
575 print_ddg_edge (file, e);
577 fprintf (file, "\nIN ARCS: ");
578 for (e = g->nodes[i].in; e; e = e->next_in)
579 print_ddg_edge (file, e);
581 fprintf (file, "\n");
585 /* Print the given DDG in VCG format. */
587 vcg_print_ddg (FILE *file, ddg_ptr g)
591 fprintf (file, "graph: {\n");
592 for (src_cuid = 0; src_cuid < g->num_nodes; src_cuid++)
595 int src_uid = INSN_UID (g->nodes[src_cuid].insn);
597 fprintf (file, "node: {title: \"%d_%d\" info1: \"", src_cuid, src_uid);
598 print_rtl_single (file, g->nodes[src_cuid].insn);
599 fprintf (file, "\"}\n");
600 for (e = g->nodes[src_cuid].out; e; e = e->next_out)
602 int dst_uid = INSN_UID (e->dest->insn);
603 int dst_cuid = e->dest->cuid;
605 /* Give the backarcs a different color. */
607 fprintf (file, "backedge: {color: red ");
609 fprintf (file, "edge: { ");
611 fprintf (file, "sourcename: \"%d_%d\" ", src_cuid, src_uid);
612 fprintf (file, "targetname: \"%d_%d\" ", dst_cuid, dst_uid);
613 fprintf (file, "label: \"%d_%d\"}\n", e->latency, e->distance);
616 fprintf (file, "}\n");
619 /* Dump the sccs in SCCS. */
621 print_sccs (FILE *file, ddg_all_sccs_ptr sccs, ddg_ptr g)
624 sbitmap_iterator sbi;
630 fprintf (file, "\n;; Number of SCC nodes - %d\n", sccs->num_sccs);
631 for (i = 0; i < sccs->num_sccs; i++)
633 fprintf (file, "SCC number: %d\n", i);
634 EXECUTE_IF_SET_IN_SBITMAP (sccs->sccs[i]->nodes, 0, u, sbi)
636 fprintf (file, "insn num %d\n", u);
637 print_rtl_single (file, g->nodes[u].insn);
640 fprintf (file, "\n");
643 /* Create an edge and initialize it with given values. */
645 create_ddg_edge (ddg_node_ptr src, ddg_node_ptr dest,
646 dep_type t, dep_data_type dt, int l, int d)
648 ddg_edge_ptr e = (ddg_edge_ptr) xmalloc (sizeof (struct ddg_edge));
656 e->next_in = e->next_out = NULL;
661 /* Add the given edge to the in/out linked lists of the DDG nodes. */
663 add_edge_to_ddg (ddg_ptr g ATTRIBUTE_UNUSED, ddg_edge_ptr e)
665 ddg_node_ptr src = e->src;
666 ddg_node_ptr dest = e->dest;
668 /* Should have allocated the sbitmaps. */
669 gcc_assert (src->successors && dest->predecessors);
671 SET_BIT (src->successors, dest->cuid);
672 SET_BIT (dest->predecessors, src->cuid);
673 e->next_in = dest->in;
675 e->next_out = src->out;
681 /* Algorithm for computing the recurrence_length of an scc. We assume at
682 for now that cycles in the data dependence graph contain a single backarc.
683 This simplifies the algorithm, and can be generalized later. */
685 set_recurrence_length (ddg_scc_ptr scc, ddg_ptr g)
690 for (j = 0; j < scc->num_backarcs; j++)
692 ddg_edge_ptr backarc = scc->backarcs[j];
694 int distance = backarc->distance;
695 ddg_node_ptr src = backarc->dest;
696 ddg_node_ptr dest = backarc->src;
698 length = longest_simple_path (g, src->cuid, dest->cuid, scc->nodes);
701 /* fprintf (stderr, "Backarc not on simple cycle in SCC.\n"); */
704 length += backarc->latency;
705 result = MAX (result, (length / distance));
707 scc->recurrence_length = result;
710 /* Create a new SCC given the set of its nodes. Compute its recurrence_length
711 and mark edges that belong to this scc as IN_SCC. */
713 create_scc (ddg_ptr g, sbitmap nodes)
717 sbitmap_iterator sbi;
719 scc = (ddg_scc_ptr) xmalloc (sizeof (struct ddg_scc));
720 scc->backarcs = NULL;
721 scc->num_backarcs = 0;
722 scc->nodes = sbitmap_alloc (g->num_nodes);
723 sbitmap_copy (scc->nodes, nodes);
725 /* Mark the backarcs that belong to this SCC. */
726 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, u, sbi)
729 ddg_node_ptr n = &g->nodes[u];
731 for (e = n->out; e; e = e->next_out)
732 if (TEST_BIT (nodes, e->dest->cuid))
734 e->aux.count = IN_SCC;
736 add_backarc_to_scc (scc, e);
740 set_recurrence_length (scc, g);
744 /* Cleans the memory allocation of a given SCC. */
746 free_scc (ddg_scc_ptr scc)
751 sbitmap_free (scc->nodes);
752 if (scc->num_backarcs > 0)
753 free (scc->backarcs);
758 /* Add a given edge known to be a backarc to the given DDG. */
760 add_backarc_to_ddg (ddg_ptr g, ddg_edge_ptr e)
762 int size = (g->num_backarcs + 1) * sizeof (ddg_edge_ptr);
764 add_edge_to_ddg (g, e);
765 g->backarcs = (ddg_edge_ptr *) xrealloc (g->backarcs, size);
766 g->backarcs[g->num_backarcs++] = e;
769 /* Add backarc to an SCC. */
771 add_backarc_to_scc (ddg_scc_ptr scc, ddg_edge_ptr e)
773 int size = (scc->num_backarcs + 1) * sizeof (ddg_edge_ptr);
775 scc->backarcs = (ddg_edge_ptr *) xrealloc (scc->backarcs, size);
776 scc->backarcs[scc->num_backarcs++] = e;
779 /* Add the given SCC to the DDG. */
781 add_scc_to_ddg (ddg_all_sccs_ptr g, ddg_scc_ptr scc)
783 int size = (g->num_sccs + 1) * sizeof (ddg_scc_ptr);
785 g->sccs = (ddg_scc_ptr *) xrealloc (g->sccs, size);
786 g->sccs[g->num_sccs++] = scc;
789 /* Given the instruction INSN return the node that represents it. */
791 get_node_of_insn (ddg_ptr g, rtx insn)
795 for (i = 0; i < g->num_nodes; i++)
796 if (insn == g->nodes[i].insn)
801 /* Given a set OPS of nodes in the DDG, find the set of their successors
802 which are not in OPS, and set their bits in SUCC. Bits corresponding to
803 OPS are cleared from SUCC. Leaves the other bits in SUCC unchanged. */
805 find_successors (sbitmap succ, ddg_ptr g, sbitmap ops)
808 sbitmap_iterator sbi;
810 EXECUTE_IF_SET_IN_SBITMAP (ops, 0, i, sbi)
812 const sbitmap node_succ = NODE_SUCCESSORS (&g->nodes[i]);
813 sbitmap_a_or_b (succ, succ, node_succ);
816 /* We want those that are not in ops. */
817 sbitmap_difference (succ, succ, ops);
820 /* Given a set OPS of nodes in the DDG, find the set of their predecessors
821 which are not in OPS, and set their bits in PREDS. Bits corresponding to
822 OPS are cleared from PREDS. Leaves the other bits in PREDS unchanged. */
824 find_predecessors (sbitmap preds, ddg_ptr g, sbitmap ops)
827 sbitmap_iterator sbi;
829 EXECUTE_IF_SET_IN_SBITMAP (ops, 0, i, sbi)
831 const sbitmap node_preds = NODE_PREDECESSORS (&g->nodes[i]);
832 sbitmap_a_or_b (preds, preds, node_preds);
835 /* We want those that are not in ops. */
836 sbitmap_difference (preds, preds, ops);
840 /* Compare function to be passed to qsort to order the backarcs in descending
843 compare_sccs (const void *s1, const void *s2)
845 const int rec_l1 = (*(const ddg_scc_ptr *)s1)->recurrence_length;
846 const int rec_l2 = (*(const ddg_scc_ptr *)s2)->recurrence_length;
847 return ((rec_l2 > rec_l1) - (rec_l2 < rec_l1));
851 /* Order the backarcs in descending recMII order using compare_sccs. */
853 order_sccs (ddg_all_sccs_ptr g)
855 qsort (g->sccs, g->num_sccs, sizeof (ddg_scc_ptr),
856 (int (*) (const void *, const void *)) compare_sccs);
859 #ifdef ENABLE_CHECKING
860 /* Check that every node in SCCS belongs to exactly one strongly connected
861 component and that no element of SCCS is empty. */
863 check_sccs (ddg_all_sccs_ptr sccs, int num_nodes)
866 sbitmap tmp = sbitmap_alloc (num_nodes);
869 for (i = 0; i < sccs->num_sccs; i++)
871 gcc_assert (!sbitmap_empty_p (sccs->sccs[i]->nodes));
872 /* Verify that every node in sccs is in exactly one strongly
873 connected component. */
874 gcc_assert (!sbitmap_any_common_bits (tmp, sccs->sccs[i]->nodes));
875 sbitmap_a_or_b (tmp, tmp, sccs->sccs[i]->nodes);
881 /* Perform the Strongly Connected Components decomposing algorithm on the
882 DDG and return DDG_ALL_SCCS structure that contains them. */
884 create_ddg_all_sccs (ddg_ptr g)
887 int num_nodes = g->num_nodes;
888 sbitmap from = sbitmap_alloc (num_nodes);
889 sbitmap to = sbitmap_alloc (num_nodes);
890 sbitmap scc_nodes = sbitmap_alloc (num_nodes);
891 ddg_all_sccs_ptr sccs = (ddg_all_sccs_ptr)
892 xmalloc (sizeof (struct ddg_all_sccs));
898 for (i = 0; i < g->num_backarcs; i++)
901 ddg_edge_ptr backarc = g->backarcs[i];
902 ddg_node_ptr src = backarc->src;
903 ddg_node_ptr dest = backarc->dest;
905 /* If the backarc already belongs to an SCC, continue. */
906 if (backarc->aux.count == IN_SCC)
909 sbitmap_zero (scc_nodes);
912 SET_BIT (from, dest->cuid);
913 SET_BIT (to, src->cuid);
915 if (find_nodes_on_paths (scc_nodes, g, from, to))
917 scc = create_scc (g, scc_nodes);
918 add_scc_to_ddg (sccs, scc);
924 sbitmap_free (scc_nodes);
925 #ifdef ENABLE_CHECKING
926 check_sccs (sccs, num_nodes);
931 /* Frees the memory allocated for all SCCs of the DDG, but keeps the DDG. */
933 free_ddg_all_sccs (ddg_all_sccs_ptr all_sccs)
940 for (i = 0; i < all_sccs->num_sccs; i++)
941 free_scc (all_sccs->sccs[i]);
947 /* Given FROM - a bitmap of source nodes - and TO - a bitmap of destination
948 nodes - find all nodes that lie on paths from FROM to TO (not excluding
949 nodes from FROM and TO). Return nonzero if nodes exist. */
951 find_nodes_on_paths (sbitmap result, ddg_ptr g, sbitmap from, sbitmap to)
956 int num_nodes = g->num_nodes;
957 sbitmap_iterator sbi;
959 sbitmap workset = sbitmap_alloc (num_nodes);
960 sbitmap reachable_from = sbitmap_alloc (num_nodes);
961 sbitmap reach_to = sbitmap_alloc (num_nodes);
962 sbitmap tmp = sbitmap_alloc (num_nodes);
964 sbitmap_copy (reachable_from, from);
965 sbitmap_copy (tmp, from);
971 sbitmap_copy (workset, tmp);
973 EXECUTE_IF_SET_IN_SBITMAP (workset, 0, u, sbi)
976 ddg_node_ptr u_node = &g->nodes[u];
978 for (e = u_node->out; e != (ddg_edge_ptr) 0; e = e->next_out)
980 ddg_node_ptr v_node = e->dest;
981 int v = v_node->cuid;
983 if (!TEST_BIT (reachable_from, v))
985 SET_BIT (reachable_from, v);
993 sbitmap_copy (reach_to, to);
994 sbitmap_copy (tmp, to);
1000 sbitmap_copy (workset, tmp);
1002 EXECUTE_IF_SET_IN_SBITMAP (workset, 0, u, sbi)
1005 ddg_node_ptr u_node = &g->nodes[u];
1007 for (e = u_node->in; e != (ddg_edge_ptr) 0; e = e->next_in)
1009 ddg_node_ptr v_node = e->src;
1010 int v = v_node->cuid;
1012 if (!TEST_BIT (reach_to, v))
1014 SET_BIT (reach_to, v);
1022 answer = sbitmap_a_and_b_cg (result, reachable_from, reach_to);
1023 sbitmap_free (workset);
1024 sbitmap_free (reachable_from);
1025 sbitmap_free (reach_to);
1031 /* Updates the counts of U_NODE's successors (that belong to NODES) to be
1032 at-least as large as the count of U_NODE plus the latency between them.
1033 Sets a bit in TMP for each successor whose count was changed (increased).
1034 Returns nonzero if any count was changed. */
1036 update_dist_to_successors (ddg_node_ptr u_node, sbitmap nodes, sbitmap tmp)
1041 for (e = u_node->out; e; e = e->next_out)
1043 ddg_node_ptr v_node = e->dest;
1044 int v = v_node->cuid;
1046 if (TEST_BIT (nodes, v)
1047 && (e->distance == 0)
1048 && (v_node->aux.count < u_node->aux.count + e->latency))
1050 v_node->aux.count = u_node->aux.count + e->latency;
1059 /* Find the length of a longest path from SRC to DEST in G,
1060 going only through NODES, and disregarding backarcs. */
1062 longest_simple_path (struct ddg * g, int src, int dest, sbitmap nodes)
1068 int num_nodes = g->num_nodes;
1069 sbitmap workset = sbitmap_alloc (num_nodes);
1070 sbitmap tmp = sbitmap_alloc (num_nodes);
1073 /* Data will hold the distance of the longest path found so far from
1074 src to each node. Initialize to -1 = less than minimum. */
1075 for (i = 0; i < g->num_nodes; i++)
1076 g->nodes[i].aux.count = -1;
1077 g->nodes[src].aux.count = 0;
1084 sbitmap_iterator sbi;
1087 sbitmap_copy (workset, tmp);
1089 EXECUTE_IF_SET_IN_SBITMAP (workset, 0, u, sbi)
1091 ddg_node_ptr u_node = &g->nodes[u];
1093 change |= update_dist_to_successors (u_node, nodes, tmp);
1096 result = g->nodes[dest].aux.count;
1097 sbitmap_free (workset);