1 /* Convert a program in SSA form into Normal form.
2 Copyright (C) 2004, 2005 Free Software Foundation, Inc.
3 Contributed by Andrew Macleod <amacleod@redhat.com>
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
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
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
24 #include "coretypes.h"
31 #include "langhooks.h"
32 #include "hard-reg-set.h"
33 #include "basic-block.h"
37 #include "diagnostic.h"
39 #include "tree-flow.h"
40 #include "tree-gimple.h"
41 #include "tree-inline.h"
45 #include "tree-dump.h"
46 #include "tree-ssa-live.h"
47 #include "tree-pass.h"
50 /* Flags to pass to remove_ssa_form. */
52 #define SSANORM_PERFORM_TER 0x1
53 #define SSANORM_COMBINE_TEMPS 0x2
54 #define SSANORM_COALESCE_PARTITIONS 0x4
57 DEF_VEC_ALLOC_I(int,heap);
59 /* Used to hold all the components required to do SSA PHI elimination.
60 The node and pred/succ list is a simple linear list of nodes and
61 edges represented as pairs of nodes.
63 The predecessor and successor list: Nodes are entered in pairs, where
64 [0] ->PRED, [1]->SUCC. All the even indexes in the array represent
65 predecessors, all the odd elements are successors.
68 When implemented as bitmaps, very large programs SSA->Normal times were
69 being dominated by clearing the interference graph.
71 Typically this list of edges is extremely small since it only includes
72 PHI results and uses from a single edge which have not coalesced with
73 each other. This means that no virtual PHI nodes are included, and
74 empirical evidence suggests that the number of edges rarely exceed
75 3, and in a bootstrap of GCC, the maximum size encountered was 7.
76 This also limits the number of possible nodes that are involved to
77 rarely more than 6, and in the bootstrap of gcc, the maximum number
78 of nodes encountered was 12. */
80 typedef struct _elim_graph {
81 /* Size of the elimination vectors. */
84 /* List of nodes in the elimination graph. */
85 VEC(tree,heap) *nodes;
87 /* The predecessor and successor edge list. */
88 VEC(int,heap) *edge_list;
93 /* Stack for visited nodes. */
96 /* The variable partition map. */
99 /* Edge being eliminated by this graph. */
102 /* List of constant copies to emit. These are pushed on in pairs. */
103 VEC(tree,heap) *const_copies;
107 /* Local functions. */
108 static tree create_temp (tree);
109 static void insert_copy_on_edge (edge, tree, tree);
110 static elim_graph new_elim_graph (int);
111 static inline void delete_elim_graph (elim_graph);
112 static inline void clear_elim_graph (elim_graph);
113 static inline int elim_graph_size (elim_graph);
114 static inline void elim_graph_add_node (elim_graph, tree);
115 static inline void elim_graph_add_edge (elim_graph, int, int);
116 static inline int elim_graph_remove_succ_edge (elim_graph, int);
118 static inline void eliminate_name (elim_graph, tree);
119 static void eliminate_build (elim_graph, basic_block);
120 static void elim_forward (elim_graph, int);
121 static int elim_unvisited_predecessor (elim_graph, int);
122 static void elim_backward (elim_graph, int);
123 static void elim_create (elim_graph, int);
124 static void eliminate_phi (edge, elim_graph);
125 static tree_live_info_p coalesce_ssa_name (var_map, int);
126 static void assign_vars (var_map);
127 static bool replace_use_variable (var_map, use_operand_p, tree *);
128 static bool replace_def_variable (var_map, def_operand_p, tree *);
129 static void eliminate_virtual_phis (void);
130 static void coalesce_abnormal_edges (var_map, conflict_graph, root_var_p);
131 static void print_exprs (FILE *, const char *, tree, const char *, tree,
133 static void print_exprs_edge (FILE *, edge, const char *, tree, const char *,
137 /* Create a temporary variable based on the type of variable T. Use T's name
144 const char *name = NULL;
147 if (TREE_CODE (t) == SSA_NAME)
148 t = SSA_NAME_VAR (t);
150 gcc_assert (TREE_CODE (t) == VAR_DECL || TREE_CODE (t) == PARM_DECL);
152 type = TREE_TYPE (t);
155 name = IDENTIFIER_POINTER (tmp);
159 tmp = create_tmp_var (type, name);
161 if (DECL_DEBUG_EXPR_IS_FROM (t) && DECL_DEBUG_EXPR (t))
163 SET_DECL_DEBUG_EXPR (tmp, DECL_DEBUG_EXPR (t));
164 DECL_DEBUG_EXPR_IS_FROM (tmp) = 1;
166 else if (!DECL_IGNORED_P (t))
168 SET_DECL_DEBUG_EXPR (tmp, t);
169 DECL_DEBUG_EXPR_IS_FROM (tmp) = 1;
171 DECL_ARTIFICIAL (tmp) = DECL_ARTIFICIAL (t);
172 DECL_IGNORED_P (tmp) = DECL_IGNORED_P (t);
173 add_referenced_tmp_var (tmp);
175 /* add_referenced_tmp_var will create the annotation and set up some
176 of the flags in the annotation. However, some flags we need to
177 inherit from our original variable. */
178 var_ann (tmp)->type_mem_tag = var_ann (t)->type_mem_tag;
179 if (is_call_clobbered (t))
180 mark_call_clobbered (tmp);
186 /* This helper function fill insert a copy from a constant or variable SRC to
187 variable DEST on edge E. */
190 insert_copy_on_edge (edge e, tree dest, tree src)
194 copy = build (MODIFY_EXPR, TREE_TYPE (dest), dest, src);
197 if (TREE_CODE (src) == ADDR_EXPR)
198 src = TREE_OPERAND (src, 0);
199 if (TREE_CODE (src) == VAR_DECL || TREE_CODE (src) == PARM_DECL)
202 if (dump_file && (dump_flags & TDF_DETAILS))
205 "Inserting a copy on edge BB%d->BB%d :",
208 print_generic_expr (dump_file, copy, dump_flags);
209 fprintf (dump_file, "\n");
212 bsi_insert_on_edge (e, copy);
216 /* Create an elimination graph with SIZE nodes and associated data
220 new_elim_graph (int size)
222 elim_graph g = (elim_graph) xmalloc (sizeof (struct _elim_graph));
224 g->nodes = VEC_alloc (tree, heap, 30);
225 g->const_copies = VEC_alloc (tree, heap, 20);
226 g->edge_list = VEC_alloc (int, heap, 20);
227 VARRAY_INT_INIT (g->stack, 30, " Elimination Stack");
229 g->visited = sbitmap_alloc (size);
235 /* Empty elimination graph G. */
238 clear_elim_graph (elim_graph g)
240 VEC_truncate (tree, g->nodes, 0);
241 VEC_truncate (int, g->edge_list, 0);
245 /* Delete elimination graph G. */
248 delete_elim_graph (elim_graph g)
250 sbitmap_free (g->visited);
251 VEC_free (int, heap, g->edge_list);
252 VEC_free (tree, heap, g->const_copies);
253 VEC_free (tree, heap, g->nodes);
258 /* Return the number of nodes in graph G. */
261 elim_graph_size (elim_graph g)
263 return VEC_length (tree, g->nodes);
267 /* Add NODE to graph G, if it doesn't exist already. */
270 elim_graph_add_node (elim_graph g, tree node)
275 for (x = 0; VEC_iterate (tree, g->nodes, x, t); x++)
278 VEC_safe_push (tree, heap, g->nodes, node);
282 /* Add the edge PRED->SUCC to graph G. */
285 elim_graph_add_edge (elim_graph g, int pred, int succ)
287 VEC_safe_push (int, heap, g->edge_list, pred);
288 VEC_safe_push (int, heap, g->edge_list, succ);
292 /* Remove an edge from graph G for which NODE is the predecessor, and
293 return the successor node. -1 is returned if there is no such edge. */
296 elim_graph_remove_succ_edge (elim_graph g, int node)
300 for (x = 0; x < VEC_length (int, g->edge_list); x += 2)
301 if (VEC_index (int, g->edge_list, x) == node)
303 VEC_replace (int, g->edge_list, x, -1);
304 y = VEC_index (int, g->edge_list, x + 1);
305 VEC_replace (int, g->edge_list, x + 1, -1);
312 /* Find all the nodes in GRAPH which are successors to NODE in the
313 edge list. VAR will hold the partition number found. CODE is the
314 code fragment executed for every node found. */
316 #define FOR_EACH_ELIM_GRAPH_SUCC(GRAPH, NODE, VAR, CODE) \
320 for (x_ = 0; x_ < VEC_length (int, (GRAPH)->edge_list); x_ += 2) \
322 y_ = VEC_index (int, (GRAPH)->edge_list, x_); \
325 (VAR) = VEC_index (int, (GRAPH)->edge_list, x_ + 1); \
331 /* Find all the nodes which are predecessors of NODE in the edge list for
332 GRAPH. VAR will hold the partition number found. CODE is the
333 code fragment executed for every node found. */
335 #define FOR_EACH_ELIM_GRAPH_PRED(GRAPH, NODE, VAR, CODE) \
339 for (x_ = 0; x_ < VEC_length (int, (GRAPH)->edge_list); x_ += 2) \
341 y_ = VEC_index (int, (GRAPH)->edge_list, x_ + 1); \
344 (VAR) = VEC_index (int, (GRAPH)->edge_list, x_); \
350 /* Add T to elimination graph G. */
353 eliminate_name (elim_graph g, tree T)
355 elim_graph_add_node (g, T);
359 /* Build elimination graph G for basic block BB on incoming PHI edge
363 eliminate_build (elim_graph g, basic_block B)
369 clear_elim_graph (g);
371 for (phi = phi_nodes (B); phi; phi = PHI_CHAIN (phi))
373 T0 = var_to_partition_to_var (g->map, PHI_RESULT (phi));
375 /* Ignore results which are not in partitions. */
379 Ti = PHI_ARG_DEF (phi, g->e->dest_idx);
381 /* If this argument is a constant, or a SSA_NAME which is being
382 left in SSA form, just queue a copy to be emitted on this
384 if (!phi_ssa_name_p (Ti)
385 || (TREE_CODE (Ti) == SSA_NAME
386 && var_to_partition (g->map, Ti) == NO_PARTITION))
388 /* Save constant copies until all other copies have been emitted
390 VEC_safe_push (tree, heap, g->const_copies, T0);
391 VEC_safe_push (tree, heap, g->const_copies, Ti);
395 Ti = var_to_partition_to_var (g->map, Ti);
398 eliminate_name (g, T0);
399 eliminate_name (g, Ti);
400 p0 = var_to_partition (g->map, T0);
401 pi = var_to_partition (g->map, Ti);
402 elim_graph_add_edge (g, p0, pi);
409 /* Push successors of T onto the elimination stack for G. */
412 elim_forward (elim_graph g, int T)
415 SET_BIT (g->visited, T);
416 FOR_EACH_ELIM_GRAPH_SUCC (g, T, S,
418 if (!TEST_BIT (g->visited, S))
421 VARRAY_PUSH_INT (g->stack, T);
425 /* Return 1 if there unvisited predecessors of T in graph G. */
428 elim_unvisited_predecessor (elim_graph g, int T)
431 FOR_EACH_ELIM_GRAPH_PRED (g, T, P,
433 if (!TEST_BIT (g->visited, P))
439 /* Process predecessors first, and insert a copy. */
442 elim_backward (elim_graph g, int T)
445 SET_BIT (g->visited, T);
446 FOR_EACH_ELIM_GRAPH_PRED (g, T, P,
448 if (!TEST_BIT (g->visited, P))
450 elim_backward (g, P);
451 insert_copy_on_edge (g->e,
452 partition_to_var (g->map, P),
453 partition_to_var (g->map, T));
458 /* Insert required copies for T in graph G. Check for a strongly connected
459 region, and create a temporary to break the cycle if one is found. */
462 elim_create (elim_graph g, int T)
467 if (elim_unvisited_predecessor (g, T))
469 U = create_temp (partition_to_var (g->map, T));
470 insert_copy_on_edge (g->e, U, partition_to_var (g->map, T));
471 FOR_EACH_ELIM_GRAPH_PRED (g, T, P,
473 if (!TEST_BIT (g->visited, P))
475 elim_backward (g, P);
476 insert_copy_on_edge (g->e, partition_to_var (g->map, P), U);
482 S = elim_graph_remove_succ_edge (g, T);
485 SET_BIT (g->visited, T);
486 insert_copy_on_edge (g->e,
487 partition_to_var (g->map, T),
488 partition_to_var (g->map, S));
494 /* Eliminate all the phi nodes on edge E in graph G. */
497 eliminate_phi (edge e, elim_graph g)
500 basic_block B = e->dest;
502 gcc_assert (VEC_length (tree, g->const_copies) == 0);
504 /* Abnormal edges already have everything coalesced. */
505 if (e->flags & EDGE_ABNORMAL)
510 eliminate_build (g, B);
512 if (elim_graph_size (g) != 0)
516 sbitmap_zero (g->visited);
517 VARRAY_POP_ALL (g->stack);
519 for (x = 0; VEC_iterate (tree, g->nodes, x, var); x++)
521 int p = var_to_partition (g->map, var);
522 if (!TEST_BIT (g->visited, p))
526 sbitmap_zero (g->visited);
527 while (VARRAY_ACTIVE_SIZE (g->stack) > 0)
529 x = VARRAY_TOP_INT (g->stack);
530 VARRAY_POP (g->stack);
531 if (!TEST_BIT (g->visited, x))
536 /* If there are any pending constant copies, issue them now. */
537 while (VEC_length (tree, g->const_copies) > 0)
540 src = VEC_pop (tree, g->const_copies);
541 dest = VEC_pop (tree, g->const_copies);
542 insert_copy_on_edge (e, dest, src);
547 /* Shortcut routine to print messages to file F of the form:
548 "STR1 EXPR1 STR2 EXPR2 STR3." */
551 print_exprs (FILE *f, const char *str1, tree expr1, const char *str2,
552 tree expr2, const char *str3)
554 fprintf (f, "%s", str1);
555 print_generic_expr (f, expr1, TDF_SLIM);
556 fprintf (f, "%s", str2);
557 print_generic_expr (f, expr2, TDF_SLIM);
558 fprintf (f, "%s", str3);
562 /* Shortcut routine to print abnormal edge messages to file F of the form:
563 "STR1 EXPR1 STR2 EXPR2 across edge E. */
566 print_exprs_edge (FILE *f, edge e, const char *str1, tree expr1,
567 const char *str2, tree expr2)
569 print_exprs (f, str1, expr1, str2, expr2, " across an abnormal edge");
570 fprintf (f, " from BB%d->BB%d\n", e->src->index,
575 /* Coalesce partitions in MAP which are live across abnormal edges in GRAPH.
576 RV is the root variable groupings of the partitions in MAP. Since code
577 cannot be inserted on these edges, failure to coalesce something across
578 an abnormal edge is an error. */
581 coalesce_abnormal_edges (var_map map, conflict_graph graph, root_var_p rv)
589 /* Code cannot be inserted on abnormal edges. Look for all abnormal
590 edges, and coalesce any PHI results with their arguments across
594 FOR_EACH_EDGE (e, ei, bb->succs)
595 if (e->dest != EXIT_BLOCK_PTR && e->flags & EDGE_ABNORMAL)
596 for (phi = phi_nodes (e->dest); phi; phi = PHI_CHAIN (phi))
598 /* Visit each PHI on the destination side of this abnormal
599 edge, and attempt to coalesce the argument with the result. */
600 var = PHI_RESULT (phi);
601 x = var_to_partition (map, var);
603 /* Ignore results which are not relevant. */
604 if (x == NO_PARTITION)
607 tmp = PHI_ARG_DEF (phi, e->dest_idx);
608 #ifdef ENABLE_CHECKING
609 if (!phi_ssa_name_p (tmp))
611 print_exprs_edge (stderr, e,
612 "\nConstant argument in PHI. Can't insert :",
614 internal_error ("SSA corruption");
617 gcc_assert (phi_ssa_name_p (tmp));
619 y = var_to_partition (map, tmp);
620 gcc_assert (x != NO_PARTITION);
621 gcc_assert (y != NO_PARTITION);
622 #ifdef ENABLE_CHECKING
623 if (root_var_find (rv, x) != root_var_find (rv, y))
625 print_exprs_edge (stderr, e, "\nDifferent root vars: ",
626 root_var (rv, root_var_find (rv, x)),
628 root_var (rv, root_var_find (rv, y)));
629 internal_error ("SSA corruption");
632 gcc_assert (root_var_find (rv, x) == root_var_find (rv, y));
637 #ifdef ENABLE_CHECKING
638 if (conflict_graph_conflict_p (graph, x, y))
640 print_exprs_edge (stderr, e, "\n Conflict ",
641 partition_to_var (map, x),
642 " and ", partition_to_var (map, y));
643 internal_error ("SSA corruption");
646 gcc_assert (!conflict_graph_conflict_p (graph, x, y));
649 /* Now map the partitions back to their real variables. */
650 var = partition_to_var (map, x);
651 tmp = partition_to_var (map, y);
652 if (dump_file && (dump_flags & TDF_DETAILS))
654 print_exprs_edge (dump_file, e,
655 "ABNORMAL: Coalescing ",
658 z = var_union (map, var, tmp);
659 #ifdef ENABLE_CHECKING
660 if (z == NO_PARTITION)
662 print_exprs_edge (stderr, e, "\nUnable to coalesce",
663 partition_to_var (map, x), " and ",
664 partition_to_var (map, y));
665 internal_error ("SSA corruption");
668 gcc_assert (z != NO_PARTITION);
670 gcc_assert (z == x || z == y);
672 conflict_graph_merge_regs (graph, x, y);
674 conflict_graph_merge_regs (graph, y, x);
680 /* Reduce the number of live ranges in MAP. Live range information is
681 returned if FLAGS indicates that we are combining temporaries, otherwise
682 NULL is returned. The only partitions which are associated with actual
683 variables at this point are those which are forced to be coalesced for
684 various reason. (live on entry, live across abnormal edges, etc.). */
686 static tree_live_info_p
687 coalesce_ssa_name (var_map map, int flags)
693 tree_live_info_p liveinfo;
695 conflict_graph graph;
697 coalesce_list_p cl = NULL;
699 if (num_var_partitions (map) <= 1)
702 liveinfo = calculate_live_on_entry (map);
703 calculate_live_on_exit (liveinfo);
704 rv = root_var_init (map);
706 /* Remove single element variable from the list. */
707 root_var_compact (rv);
709 cl = create_coalesce_list (map);
711 /* Add all potential copies via PHI arguments to the list. */
714 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
716 tree res = PHI_RESULT (phi);
717 int p = var_to_partition (map, res);
718 if (p == NO_PARTITION)
720 for (x = 0; x < (unsigned)PHI_NUM_ARGS (phi); x++)
722 tree arg = PHI_ARG_DEF (phi, x);
725 if (TREE_CODE (arg) != SSA_NAME)
727 if (SSA_NAME_VAR (res) != SSA_NAME_VAR (arg))
729 p2 = var_to_partition (map, PHI_ARG_DEF (phi, x));
730 if (p2 != NO_PARTITION)
731 add_coalesce (cl, p, p2, 1);
736 /* Coalesce all the result decls together. */
739 for (x = 0; x < num_var_partitions (map); x++)
741 tree p = partition_to_var (map, x);
742 if (TREE_CODE (SSA_NAME_VAR(p)) == RESULT_DECL)
744 if (var == NULL_TREE)
750 add_coalesce (cl, i, x, 1);
754 /* Build a conflict graph. */
755 graph = build_tree_conflict_graph (liveinfo, rv, cl);
759 if (dump_file && (dump_flags & TDF_DETAILS))
761 fprintf (dump_file, "Before sorting:\n");
762 dump_coalesce_list (dump_file, cl);
765 sort_coalesce_list (cl);
767 if (dump_file && (dump_flags & TDF_DETAILS))
769 fprintf (dump_file, "\nAfter sorting:\n");
770 dump_coalesce_list (dump_file, cl);
774 /* Put the single element variables back in. */
775 root_var_decompact (rv);
777 /* First, coalesce all live on entry variables to their root variable.
778 This will ensure the first use is coming from the correct location. */
780 live = sbitmap_alloc (num_var_partitions (map));
783 /* Set 'live' vector to indicate live on entry partitions. */
784 num = num_var_partitions (map);
785 for (x = 0 ; x < num; x++)
787 var = partition_to_var (map, x);
788 if (default_def (SSA_NAME_VAR (var)) == var)
792 if ((flags & SSANORM_COMBINE_TEMPS) == 0)
794 delete_tree_live_info (liveinfo);
798 /* Assign root variable as partition representative for each live on entry
800 EXECUTE_IF_SET_IN_SBITMAP (live, 0, x,
802 var = root_var (rv, root_var_find (rv, x));
804 /* If these aren't already coalesced... */
805 if (partition_to_var (map, x) != var)
807 /* This root variable should have not already been assigned
808 to another partition which is not coalesced with this one. */
809 gcc_assert (!ann->out_of_ssa_tag);
811 if (dump_file && (dump_flags & TDF_DETAILS))
813 print_exprs (dump_file, "Must coalesce ",
814 partition_to_var (map, x),
815 " with the root variable ", var, ".\n");
818 change_partition_var (map, var, x);
824 /* Coalesce partitions live across abnormal edges. */
825 coalesce_abnormal_edges (map, graph, rv);
827 if (dump_file && (dump_flags & TDF_DETAILS))
828 dump_var_map (dump_file, map);
830 /* Coalesce partitions. */
831 coalesce_tpa_members (rv, graph, map, cl,
832 ((dump_flags & TDF_DETAILS) ? dump_file
835 if (flags & SSANORM_COALESCE_PARTITIONS)
836 coalesce_tpa_members (rv, graph, map, NULL,
837 ((dump_flags & TDF_DETAILS) ? dump_file
840 delete_coalesce_list (cl);
841 root_var_delete (rv);
842 conflict_graph_delete (graph);
848 /* Take the ssa-name var_map MAP, and assign real variables to each
852 assign_vars (var_map map)
859 rv = root_var_init (map);
863 /* Coalescing may already have forced some partitions to their root
864 variable. Find these and tag them. */
866 num = num_var_partitions (map);
867 for (x = 0; x < num; x++)
869 var = partition_to_var (map, x);
870 if (TREE_CODE (var) != SSA_NAME)
872 /* Coalescing will already have verified that more than one
873 partition doesn't have the same root variable. Simply marked
874 the variable as assigned. */
876 ann->out_of_ssa_tag = 1;
877 if (dump_file && (dump_flags & TDF_DETAILS))
879 fprintf (dump_file, "partition %d has variable ", x);
880 print_generic_expr (dump_file, var, TDF_SLIM);
881 fprintf (dump_file, " assigned to it.\n");
887 num = root_var_num (rv);
888 for (x = 0; x < num; x++)
890 var = root_var (rv, x);
892 for (i = root_var_first_partition (rv, x);
894 i = root_var_next_partition (rv, i))
896 t = partition_to_var (map, i);
898 if (t == var || TREE_CODE (t) != SSA_NAME)
901 rep = var_to_partition (map, t);
903 if (!ann->out_of_ssa_tag)
905 if (dump_file && (dump_flags & TDF_DETAILS))
906 print_exprs (dump_file, "", t, " --> ", var, "\n");
907 change_partition_var (map, var, rep);
911 if (dump_file && (dump_flags & TDF_DETAILS))
912 print_exprs (dump_file, "", t, " not coalesced with ", var,
915 var = create_temp (t);
916 change_partition_var (map, var, rep);
919 if (dump_file && (dump_flags & TDF_DETAILS))
921 fprintf (dump_file, " --> New temp: '");
922 print_generic_expr (dump_file, var, TDF_SLIM);
923 fprintf (dump_file, "'\n");
928 root_var_delete (rv);
932 /* Replace use operand P with whatever variable it has been rewritten to based
933 on the partitions in MAP. EXPR is an optional expression vector over SSA
934 versions which is used to replace P with an expression instead of a variable.
935 If the stmt is changed, return true. */
938 replace_use_variable (var_map map, use_operand_p p, tree *expr)
941 tree var = USE_FROM_PTR (p);
943 /* Check if we are replacing this variable with an expression. */
946 int version = SSA_NAME_VERSION (var);
949 tree new_expr = TREE_OPERAND (expr[version], 1);
950 SET_USE (p, new_expr);
951 /* Clear the stmt's RHS, or GC might bite us. */
952 TREE_OPERAND (expr[version], 1) = NULL_TREE;
957 new_var = var_to_partition_to_var (map, var);
960 SET_USE (p, new_var);
961 set_is_used (new_var);
968 /* Replace def operand DEF_P with whatever variable it has been rewritten to
969 based on the partitions in MAP. EXPR is an optional expression vector over
970 SSA versions which is used to replace DEF_P with an expression instead of a
971 variable. If the stmt is changed, return true. */
974 replace_def_variable (var_map map, def_operand_p def_p, tree *expr)
977 tree var = DEF_FROM_PTR (def_p);
979 /* Check if we are replacing this variable with an expression. */
982 int version = SSA_NAME_VERSION (var);
985 tree new_expr = TREE_OPERAND (expr[version], 1);
986 SET_DEF (def_p, new_expr);
987 /* Clear the stmt's RHS, or GC might bite us. */
988 TREE_OPERAND (expr[version], 1) = NULL_TREE;
993 new_var = var_to_partition_to_var (map, var);
996 SET_DEF (def_p, new_var);
997 set_is_used (new_var);
1004 /* Remove any PHI node which is a virtual PHI. */
1007 eliminate_virtual_phis (void)
1014 for (phi = phi_nodes (bb); phi; phi = next)
1016 next = PHI_CHAIN (phi);
1017 if (!is_gimple_reg (SSA_NAME_VAR (PHI_RESULT (phi))))
1019 #ifdef ENABLE_CHECKING
1021 /* There should be no arguments of this PHI which are in
1022 the partition list, or we get incorrect results. */
1023 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
1025 tree arg = PHI_ARG_DEF (phi, i);
1026 if (TREE_CODE (arg) == SSA_NAME
1027 && is_gimple_reg (SSA_NAME_VAR (arg)))
1029 fprintf (stderr, "Argument of PHI is not virtual (");
1030 print_generic_expr (stderr, arg, TDF_SLIM);
1031 fprintf (stderr, "), but the result is :");
1032 print_generic_stmt (stderr, phi, TDF_SLIM);
1033 internal_error ("SSA corruption");
1037 remove_phi_node (phi, NULL_TREE);
1044 /* This routine will coalesce variables in MAP of the same type which do not
1045 interfere with each other. LIVEINFO is the live range info for variables
1046 of interest. This will both reduce the memory footprint of the stack, and
1047 allow us to coalesce together local copies of globals and scalarized
1051 coalesce_vars (var_map map, tree_live_info_p liveinfo)
1058 conflict_graph graph;
1060 cl = create_coalesce_list (map);
1062 /* Merge all the live on entry vectors for coalesced partitions. */
1063 for (x = 0; x < num_var_partitions (map); x++)
1065 var = partition_to_var (map, x);
1066 p = var_to_partition (map, var);
1068 live_merge_and_clear (liveinfo, p, x);
1071 /* When PHI nodes are turned into copies, the result of each PHI node
1072 becomes live on entry to the block. Mark these now. */
1078 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
1080 p = var_to_partition (map, PHI_RESULT (phi));
1082 /* Skip virtual PHI nodes. */
1083 if (p == (unsigned)NO_PARTITION)
1086 make_live_on_entry (liveinfo, bb, p);
1088 /* Each argument is a potential copy operation. Add any arguments
1089 which are not coalesced to the result to the coalesce list. */
1090 for (x = 0; x < (unsigned)PHI_NUM_ARGS (phi); x++)
1092 arg = PHI_ARG_DEF (phi, x);
1093 if (!phi_ssa_name_p (arg))
1095 p2 = var_to_partition (map, arg);
1096 if (p2 == (unsigned)NO_PARTITION)
1099 add_coalesce (cl, p, p2, 1);
1105 /* Re-calculate live on exit info. */
1106 calculate_live_on_exit (liveinfo);
1108 if (dump_file && (dump_flags & TDF_DETAILS))
1110 fprintf (dump_file, "Live range info for variable memory coalescing.\n");
1111 dump_live_info (dump_file, liveinfo, LIVEDUMP_ALL);
1113 fprintf (dump_file, "Coalesce list from phi nodes:\n");
1114 dump_coalesce_list (dump_file, cl);
1118 tv = type_var_init (map);
1120 type_var_dump (dump_file, tv);
1121 type_var_compact (tv);
1123 type_var_dump (dump_file, tv);
1125 graph = build_tree_conflict_graph (liveinfo, tv, cl);
1127 type_var_decompact (tv);
1128 if (dump_file && (dump_flags & TDF_DETAILS))
1130 fprintf (dump_file, "type var list now looks like:n");
1131 type_var_dump (dump_file, tv);
1133 fprintf (dump_file, "Coalesce list after conflict graph build:\n");
1134 dump_coalesce_list (dump_file, cl);
1137 sort_coalesce_list (cl);
1138 if (dump_file && (dump_flags & TDF_DETAILS))
1140 fprintf (dump_file, "Coalesce list after sorting:\n");
1141 dump_coalesce_list (dump_file, cl);
1144 coalesce_tpa_members (tv, graph, map, cl,
1145 ((dump_flags & TDF_DETAILS) ? dump_file : NULL));
1147 type_var_delete (tv);
1148 delete_coalesce_list (cl);
1152 /* Temporary Expression Replacement (TER)
1154 Replace SSA version variables during out-of-ssa with their defining
1155 expression if there is only one use of the variable.
1157 A pass is made through the function, one block at a time. No cross block
1158 information is tracked.
1160 Variables which only have one use, and whose defining stmt is considered
1161 a replaceable expression (see check_replaceable) are entered into
1162 consideration by adding a list of dependent partitions to the version_info
1163 vector for that ssa_name_version. This information comes from the partition
1164 mapping for each USE. At the same time, the partition_dep_list vector for
1165 these partitions have this version number entered into their lists.
1167 When the use of a replaceable ssa_variable is encountered, the dependence
1168 list in version_info[] is moved to the "pending_dependence" list in case
1169 the current expression is also replaceable. (To be determined later in
1170 processing this stmt.) version_info[] for the version is then updated to
1171 point to the defining stmt and the 'replaceable' bit is set.
1173 Any partition which is defined by a statement 'kills' any expression which
1174 is dependent on this partition. Every ssa version in the partitions'
1175 dependence list is removed from future consideration.
1177 All virtual references are lumped together. Any expression which is
1178 dependent on any virtual variable (via a VUSE) has a dependence added
1179 to the special partition defined by VIRTUAL_PARTITION.
1181 Whenever a V_MAY_DEF is seen, all expressions dependent this
1182 VIRTUAL_PARTITION are removed from consideration.
1184 At the end of a basic block, all expression are removed from consideration
1185 in preparation for the next block.
1187 The end result is a vector over SSA_NAME_VERSION which is passed back to
1188 rewrite_out_of_ssa. As the SSA variables are being rewritten, instead of
1189 replacing the SSA_NAME tree element with the partition it was assigned,
1190 it is replaced with the RHS of the defining expression. */
1193 /* Dependency list element. This can contain either a partition index or a
1194 version number, depending on which list it is in. */
1196 typedef struct value_expr_d
1199 struct value_expr_d *next;
1203 /* Temporary Expression Replacement (TER) table information. */
1205 typedef struct temp_expr_table_d
1208 void **version_info;
1209 value_expr_p *partition_dep_list;
1211 bool saw_replaceable;
1212 int virtual_partition;
1213 bitmap partition_in_use;
1214 value_expr_p free_list;
1215 value_expr_p pending_dependence;
1216 } *temp_expr_table_p;
1218 /* Used to indicate a dependency on V_MAY_DEFs. */
1219 #define VIRTUAL_PARTITION(table) (table->virtual_partition)
1221 static temp_expr_table_p new_temp_expr_table (var_map);
1222 static tree *free_temp_expr_table (temp_expr_table_p);
1223 static inline value_expr_p new_value_expr (temp_expr_table_p);
1224 static inline void free_value_expr (temp_expr_table_p, value_expr_p);
1225 static inline value_expr_p find_value_in_list (value_expr_p, int,
1227 static inline void add_value_to_list (temp_expr_table_p, value_expr_p *, int);
1228 static inline void add_info_to_list (temp_expr_table_p, value_expr_p *,
1230 static value_expr_p remove_value_from_list (value_expr_p *, int);
1231 static void add_dependance (temp_expr_table_p, int, tree);
1232 static bool check_replaceable (temp_expr_table_p, tree);
1233 static void finish_expr (temp_expr_table_p, int, bool);
1234 static void mark_replaceable (temp_expr_table_p, tree);
1235 static inline void kill_expr (temp_expr_table_p, int, bool);
1236 static inline void kill_virtual_exprs (temp_expr_table_p, bool);
1237 static void find_replaceable_in_bb (temp_expr_table_p, basic_block);
1238 static tree *find_replaceable_exprs (var_map);
1239 static void dump_replaceable_exprs (FILE *, tree *);
1242 /* Create a new TER table for MAP. */
1244 static temp_expr_table_p
1245 new_temp_expr_table (var_map map)
1247 temp_expr_table_p t;
1249 t = (temp_expr_table_p) xmalloc (sizeof (struct temp_expr_table_d));
1252 t->version_info = xcalloc (num_ssa_names + 1, sizeof (void *));
1253 t->partition_dep_list = xcalloc (num_var_partitions (map) + 1,
1254 sizeof (value_expr_p));
1256 t->replaceable = BITMAP_ALLOC (NULL);
1257 t->partition_in_use = BITMAP_ALLOC (NULL);
1259 t->saw_replaceable = false;
1260 t->virtual_partition = num_var_partitions (map);
1261 t->free_list = NULL;
1262 t->pending_dependence = NULL;
1268 /* Free TER table T. If there are valid replacements, return the expression
1272 free_temp_expr_table (temp_expr_table_p t)
1277 #ifdef ENABLE_CHECKING
1279 for (x = 0; x <= num_var_partitions (t->map); x++)
1280 gcc_assert (!t->partition_dep_list[x]);
1283 while ((p = t->free_list))
1285 t->free_list = p->next;
1289 BITMAP_FREE (t->partition_in_use);
1290 BITMAP_FREE (t->replaceable);
1292 free (t->partition_dep_list);
1293 if (t->saw_replaceable)
1294 ret = (tree *)t->version_info;
1296 free (t->version_info);
1303 /* Allocate a new value list node. Take it from the free list in TABLE if
1306 static inline value_expr_p
1307 new_value_expr (temp_expr_table_p table)
1310 if (table->free_list)
1312 p = table->free_list;
1313 table->free_list = p->next;
1316 p = (value_expr_p) xmalloc (sizeof (struct value_expr_d));
1322 /* Add value list node P to the free list in TABLE. */
1325 free_value_expr (temp_expr_table_p table, value_expr_p p)
1327 p->next = table->free_list;
1328 table->free_list = p;
1332 /* Find VALUE if it's in LIST. Return a pointer to the list object if found,
1333 else return NULL. If LAST_PTR is provided, it will point to the previous
1334 item upon return, or NULL if this is the first item in the list. */
1336 static inline value_expr_p
1337 find_value_in_list (value_expr_p list, int value, value_expr_p *last_ptr)
1340 value_expr_p last = NULL;
1342 for (curr = list; curr; last = curr, curr = curr->next)
1344 if (curr->value == value)
1353 /* Add VALUE to LIST, if it isn't already present. TAB is the expression
1357 add_value_to_list (temp_expr_table_p tab, value_expr_p *list, int value)
1361 if (!find_value_in_list (*list, value, NULL))
1363 info = new_value_expr (tab);
1364 info->value = value;
1371 /* Add value node INFO if it's value isn't already in LIST. Free INFO if
1372 it is already in the list. TAB is the expression table. */
1375 add_info_to_list (temp_expr_table_p tab, value_expr_p *list, value_expr_p info)
1377 if (find_value_in_list (*list, info->value, NULL))
1378 free_value_expr (tab, info);
1387 /* Look for VALUE in LIST. If found, remove it from the list and return it's
1391 remove_value_from_list (value_expr_p *list, int value)
1393 value_expr_p info, last;
1395 info = find_value_in_list (*list, value, &last);
1401 last->next = info->next;
1407 /* Add a dependency between the def of ssa VERSION and VAR. If VAR is
1408 replaceable by an expression, add a dependence each of the elements of the
1409 expression. These are contained in the pending list. TAB is the
1410 expression table. */
1413 add_dependance (temp_expr_table_p tab, int version, tree var)
1418 i = SSA_NAME_VERSION (var);
1419 if (bitmap_bit_p (tab->replaceable, i))
1421 /* This variable is being substituted, so use whatever dependences
1422 were queued up when we marked this as replaceable earlier. */
1423 while ((info = tab->pending_dependence))
1425 tab->pending_dependence = info->next;
1426 /* Get the partition this variable was dependent on. Reuse this
1427 object to represent the current expression instead. */
1429 info->value = version;
1430 add_info_to_list (tab, &(tab->partition_dep_list[x]), info);
1431 add_value_to_list (tab,
1432 (value_expr_p *)&(tab->version_info[version]), x);
1433 bitmap_set_bit (tab->partition_in_use, x);
1438 i = var_to_partition (tab->map, var);
1439 gcc_assert (i != NO_PARTITION);
1440 add_value_to_list (tab, &(tab->partition_dep_list[i]), version);
1441 add_value_to_list (tab,
1442 (value_expr_p *)&(tab->version_info[version]), i);
1443 bitmap_set_bit (tab->partition_in_use, i);
1448 /* Check if expression STMT is suitable for replacement in table TAB. If so,
1449 create an expression entry. Return true if this stmt is replaceable. */
1452 check_replaceable (temp_expr_table_p tab, tree stmt)
1456 var_map map = tab->map;
1460 if (TREE_CODE (stmt) != MODIFY_EXPR)
1463 /* Punt if there is more than 1 def, or more than 1 use. */
1464 def = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_DEF);
1468 if (version_ref_count (map, def) != 1)
1471 /* There must be no V_MAY_DEFS or V_MUST_DEFS. */
1472 if (!(ZERO_SSA_OPERANDS (stmt, (SSA_OP_VMAYDEF | SSA_OP_VMUSTDEF))))
1475 /* Float expressions must go through memory if float-store is on. */
1476 if (flag_float_store && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (stmt, 1))))
1479 /* Calls to functions with side-effects cannot be replaced. */
1480 if ((call_expr = get_call_expr_in (stmt)) != NULL_TREE)
1482 int call_flags = call_expr_flags (call_expr);
1483 if (TREE_SIDE_EFFECTS (call_expr)
1484 && !(call_flags & (ECF_PURE | ECF_CONST | ECF_NORETURN)))
1488 version = SSA_NAME_VERSION (def);
1490 /* Add this expression to the dependency list for each use partition. */
1491 FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_USE)
1493 add_dependance (tab, version, var);
1496 /* If there are VUSES, add a dependence on virtual defs. */
1497 if (!ZERO_SSA_OPERANDS (stmt, SSA_OP_VUSE))
1499 add_value_to_list (tab, (value_expr_p *)&(tab->version_info[version]),
1500 VIRTUAL_PARTITION (tab));
1501 add_value_to_list (tab,
1502 &(tab->partition_dep_list[VIRTUAL_PARTITION (tab)]),
1504 bitmap_set_bit (tab->partition_in_use, VIRTUAL_PARTITION (tab));
1511 /* This function will remove the expression for VERSION from replacement
1512 consideration.n table TAB If 'replace' is true, it is marked as
1513 replaceable, otherwise not. */
1516 finish_expr (temp_expr_table_p tab, int version, bool replace)
1518 value_expr_p info, tmp;
1521 /* Remove this expression from its dependent lists. The partition dependence
1522 list is retained and transfered later to whomever uses this version. */
1523 for (info = (value_expr_p) tab->version_info[version]; info; info = tmp)
1525 partition = info->value;
1526 gcc_assert (tab->partition_dep_list[partition]);
1527 tmp = remove_value_from_list (&(tab->partition_dep_list[partition]),
1530 free_value_expr (tab, tmp);
1531 /* Only clear the bit when the dependency list is emptied via
1532 a replacement. Otherwise kill_expr will take care of it. */
1533 if (!(tab->partition_dep_list[partition]) && replace)
1534 bitmap_clear_bit (tab->partition_in_use, partition);
1537 free_value_expr (tab, info);
1542 tab->saw_replaceable = true;
1543 bitmap_set_bit (tab->replaceable, version);
1547 gcc_assert (!bitmap_bit_p (tab->replaceable, version));
1548 tab->version_info[version] = NULL;
1553 /* Mark the expression associated with VAR as replaceable, and enter
1554 the defining stmt into the version_info table TAB. */
1557 mark_replaceable (temp_expr_table_p tab, tree var)
1560 int version = SSA_NAME_VERSION (var);
1561 finish_expr (tab, version, true);
1563 /* Move the dependence list to the pending list. */
1564 if (tab->version_info[version])
1566 info = (value_expr_p) tab->version_info[version];
1567 for ( ; info->next; info = info->next)
1569 info->next = tab->pending_dependence;
1570 tab->pending_dependence = (value_expr_p)tab->version_info[version];
1573 tab->version_info[version] = SSA_NAME_DEF_STMT (var);
1577 /* This function marks any expression in TAB which is dependent on PARTITION
1578 as NOT replaceable. CLEAR_BIT is used to determine whether partition_in_use
1579 should have its bit cleared. Since this routine can be called within an
1580 EXECUTE_IF_SET_IN_BITMAP, the bit can't always be cleared. */
1583 kill_expr (temp_expr_table_p tab, int partition, bool clear_bit)
1587 /* Mark every active expr dependent on this var as not replaceable. */
1588 while ((ptr = tab->partition_dep_list[partition]) != NULL)
1589 finish_expr (tab, ptr->value, false);
1592 bitmap_clear_bit (tab->partition_in_use, partition);
1596 /* This function kills all expressions in TAB which are dependent on virtual
1597 DEFs. CLEAR_BIT determines whether partition_in_use gets cleared. */
1600 kill_virtual_exprs (temp_expr_table_p tab, bool clear_bit)
1602 kill_expr (tab, VIRTUAL_PARTITION (tab), clear_bit);
1606 /* This function processes basic block BB, and looks for variables which can
1607 be replaced by their expressions. Results are stored in TAB. */
1610 find_replaceable_in_bb (temp_expr_table_p tab, basic_block bb)
1612 block_stmt_iterator bsi;
1616 var_map map = tab->map;
1620 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
1622 stmt = bsi_stmt (bsi);
1623 ann = stmt_ann (stmt);
1625 /* Determine if this stmt finishes an existing expression. */
1626 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_USE)
1628 if (tab->version_info[SSA_NAME_VERSION (def)])
1630 bool same_root_var = false;
1634 /* See if the root variables are the same. If they are, we
1635 do not want to do the replacement to avoid problems with
1636 code size, see PR tree-optimization/17549. */
1637 FOR_EACH_SSA_TREE_OPERAND (def2, stmt, iter2, SSA_OP_DEF)
1638 if (SSA_NAME_VAR (def) == SSA_NAME_VAR (def2))
1640 same_root_var = true;
1644 /* Mark expression as replaceable unless stmt is volatile
1645 or DEF sets the same root variable as STMT. */
1646 if (!ann->has_volatile_ops && !same_root_var)
1647 mark_replaceable (tab, def);
1649 finish_expr (tab, SSA_NAME_VERSION (def), false);
1653 /* Next, see if this stmt kills off an active expression. */
1654 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
1656 partition = var_to_partition (map, def);
1657 if (partition != NO_PARTITION && tab->partition_dep_list[partition])
1658 kill_expr (tab, partition, true);
1661 /* Now see if we are creating a new expression or not. */
1662 if (!ann->has_volatile_ops)
1663 check_replaceable (tab, stmt);
1665 /* Free any unused dependency lists. */
1666 while ((p = tab->pending_dependence))
1668 tab->pending_dependence = p->next;
1669 free_value_expr (tab, p);
1672 /* A V_{MAY,MUST}_DEF kills any expression using a virtual operand. */
1673 if (!ZERO_SSA_OPERANDS (stmt, SSA_OP_VIRTUAL_DEFS))
1674 kill_virtual_exprs (tab, true);
1679 /* This function is the driver routine for replacement of temporary expressions
1680 in the SSA->normal phase, operating on MAP. If there are replaceable
1681 expressions, a table is returned which maps SSA versions to the
1682 expressions they should be replaced with. A NULL_TREE indicates no
1683 replacement should take place. If there are no replacements at all,
1684 NULL is returned by the function, otherwise an expression vector indexed
1685 by SSA_NAME version numbers. */
1688 find_replaceable_exprs (var_map map)
1692 temp_expr_table_p table;
1695 table = new_temp_expr_table (map);
1700 find_replaceable_in_bb (table, bb);
1701 EXECUTE_IF_SET_IN_BITMAP ((table->partition_in_use), 0, i, bi)
1703 kill_expr (table, i, false);
1707 ret = free_temp_expr_table (table);
1712 /* Dump TER expression table EXPR to file F. */
1715 dump_replaceable_exprs (FILE *f, tree *expr)
1719 fprintf (f, "\nReplacing Expressions\n");
1720 for (x = 0; x < (int)num_ssa_names + 1; x++)
1724 var = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_DEF);
1725 gcc_assert (var != NULL_TREE);
1726 print_generic_expr (f, var, TDF_SLIM);
1727 fprintf (f, " replace with --> ");
1728 print_generic_expr (f, TREE_OPERAND (stmt, 1), TDF_SLIM);
1735 /* Helper function for discover_nonconstant_array_refs.
1736 Look for ARRAY_REF nodes with non-constant indexes and mark them
1740 discover_nonconstant_array_refs_r (tree * tp, int *walk_subtrees,
1741 void *data ATTRIBUTE_UNUSED)
1745 if (IS_TYPE_OR_DECL_P (t))
1747 else if (TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
1749 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
1750 && is_gimple_min_invariant (TREE_OPERAND (t, 1))
1751 && (!TREE_OPERAND (t, 2)
1752 || is_gimple_min_invariant (TREE_OPERAND (t, 2))))
1753 || (TREE_CODE (t) == COMPONENT_REF
1754 && (!TREE_OPERAND (t,2)
1755 || is_gimple_min_invariant (TREE_OPERAND (t, 2))))
1756 || TREE_CODE (t) == BIT_FIELD_REF
1757 || TREE_CODE (t) == REALPART_EXPR
1758 || TREE_CODE (t) == IMAGPART_EXPR
1759 || TREE_CODE (t) == VIEW_CONVERT_EXPR
1760 || TREE_CODE (t) == NOP_EXPR
1761 || TREE_CODE (t) == CONVERT_EXPR)
1762 t = TREE_OPERAND (t, 0);
1764 if (TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
1766 t = get_base_address (t);
1767 if (t && DECL_P (t))
1768 TREE_ADDRESSABLE (t) = 1;
1778 /* RTL expansion is not able to compile array references with variable
1779 offsets for arrays stored in single register. Discover such
1780 expressions and mark variables as addressable to avoid this
1784 discover_nonconstant_array_refs (void)
1787 block_stmt_iterator bsi;
1791 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
1792 walk_tree (bsi_stmt_ptr (bsi), discover_nonconstant_array_refs_r,
1798 /* This function will rewrite the current program using the variable mapping
1799 found in MAP. If the replacement vector VALUES is provided, any
1800 occurrences of partitions with non-null entries in the vector will be
1801 replaced with the expression in the vector instead of its mapped
1805 rewrite_trees (var_map map, tree *values)
1809 block_stmt_iterator si;
1814 #ifdef ENABLE_CHECKING
1815 /* Search for PHIs where the destination has no partition, but one
1816 or more arguments has a partition. This should not happen and can
1817 create incorrect code. */
1822 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
1824 tree T0 = var_to_partition_to_var (map, PHI_RESULT (phi));
1826 if (T0 == NULL_TREE)
1830 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
1832 tree arg = PHI_ARG_DEF (phi, i);
1834 if (TREE_CODE (arg) == SSA_NAME
1835 && var_to_partition (map, arg) != NO_PARTITION)
1837 fprintf (stderr, "Argument of PHI is in a partition :(");
1838 print_generic_expr (stderr, arg, TDF_SLIM);
1839 fprintf (stderr, "), but the result is not :");
1840 print_generic_stmt (stderr, phi, TDF_SLIM);
1841 internal_error ("SSA corruption");
1849 /* Replace PHI nodes with any required copies. */
1850 g = new_elim_graph (map->num_partitions);
1854 for (si = bsi_start (bb); !bsi_end_p (si); )
1856 tree stmt = bsi_stmt (si);
1857 use_operand_p use_p, copy_use_p;
1858 def_operand_p def_p;
1859 bool remove = false, is_copy = false;
1864 ann = stmt_ann (stmt);
1867 if (TREE_CODE (stmt) == MODIFY_EXPR
1868 && (TREE_CODE (TREE_OPERAND (stmt, 1)) == SSA_NAME))
1871 copy_use_p = NULL_USE_OPERAND_P;
1872 FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE)
1874 if (replace_use_variable (map, use_p, values))
1883 def_p = SINGLE_SSA_DEF_OPERAND (stmt, SSA_OP_DEF);
1887 /* Mark this stmt for removal if it is the list of replaceable
1889 if (values && values[SSA_NAME_VERSION (DEF_FROM_PTR (def_p))])
1893 if (replace_def_variable (map, def_p, NULL))
1895 /* If both SSA_NAMEs coalesce to the same variable,
1896 mark the now redundant copy for removal. */
1899 gcc_assert (copy_use_p != NULL_USE_OPERAND_P);
1900 if (DEF_FROM_PTR (def_p) == USE_FROM_PTR (copy_use_p))
1906 FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, iter, SSA_OP_DEF)
1907 if (replace_def_variable (map, def_p, NULL))
1910 /* Remove any stmts marked for removal. */
1917 phi = phi_nodes (bb);
1921 FOR_EACH_EDGE (e, ei, bb->preds)
1922 eliminate_phi (e, g);
1926 delete_elim_graph (g);
1930 DEF_VEC_ALLOC_P(edge,heap);
1932 /* These are the local work structures used to determine the best place to
1933 insert the copies that were placed on edges by the SSA->normal pass.. */
1934 static VEC(edge,heap) *edge_leader;
1935 static VEC(tree,heap) *stmt_list;
1936 static bitmap leader_has_match = NULL;
1937 static edge leader_match = NULL;
1940 /* Pass this function to make_forwarder_block so that all the edges with
1941 matching PENDING_STMT lists to 'curr_stmt_list' get redirected. */
1943 same_stmt_list_p (edge e)
1945 return (e->aux == (PTR) leader_match) ? true : false;
1949 /* Return TRUE if S1 and S2 are equivalent copies. */
1951 identical_copies_p (tree s1, tree s2)
1953 #ifdef ENABLE_CHECKING
1954 gcc_assert (TREE_CODE (s1) == MODIFY_EXPR);
1955 gcc_assert (TREE_CODE (s2) == MODIFY_EXPR);
1956 gcc_assert (DECL_P (TREE_OPERAND (s1, 0)));
1957 gcc_assert (DECL_P (TREE_OPERAND (s2, 0)));
1960 if (TREE_OPERAND (s1, 0) != TREE_OPERAND (s2, 0))
1963 s1 = TREE_OPERAND (s1, 1);
1964 s2 = TREE_OPERAND (s2, 1);
1973 /* Compare the PENDING_STMT list for two edges, and return true if the lists
1974 contain the same sequence of copies. */
1977 identical_stmt_lists_p (edge e1, edge e2)
1979 tree t1 = PENDING_STMT (e1);
1980 tree t2 = PENDING_STMT (e2);
1981 tree_stmt_iterator tsi1, tsi2;
1983 gcc_assert (TREE_CODE (t1) == STATEMENT_LIST);
1984 gcc_assert (TREE_CODE (t2) == STATEMENT_LIST);
1986 for (tsi1 = tsi_start (t1), tsi2 = tsi_start (t2);
1987 !tsi_end_p (tsi1) && !tsi_end_p (tsi2);
1988 tsi_next (&tsi1), tsi_next (&tsi2))
1990 if (!identical_copies_p (tsi_stmt (tsi1), tsi_stmt (tsi2)))
1994 if (!tsi_end_p (tsi1) || ! tsi_end_p (tsi2))
2001 /* Allocate data structures used in analyze_edges_for_bb. */
2004 init_analyze_edges_for_bb (void)
2006 edge_leader = VEC_alloc (edge, heap, 25);
2007 stmt_list = VEC_alloc (tree, heap, 25);
2008 leader_has_match = BITMAP_ALLOC (NULL);
2012 /* Free data structures used in analyze_edges_for_bb. */
2015 fini_analyze_edges_for_bb (void)
2017 VEC_free (edge, heap, edge_leader);
2018 VEC_free (tree, heap, stmt_list);
2019 BITMAP_FREE (leader_has_match);
2023 /* Look at all the incoming edges to block BB, and decide where the best place
2024 to insert the stmts on each edge are, and perform those insertions. Output
2025 any debug information to DEBUG_FILE. */
2028 analyze_edges_for_bb (basic_block bb, FILE *debug_file)
2034 bool have_opportunity;
2035 block_stmt_iterator bsi;
2037 edge single_edge = NULL;
2043 /* Blocks which contain at least one abnormal edge cannot use
2044 make_forwarder_block. Look for these blocks, and commit any PENDING_STMTs
2045 found on edges in these block. */
2046 have_opportunity = true;
2047 FOR_EACH_EDGE (e, ei, bb->preds)
2048 if (e->flags & EDGE_ABNORMAL)
2050 have_opportunity = false;
2054 if (!have_opportunity)
2056 FOR_EACH_EDGE (e, ei, bb->preds)
2057 if (PENDING_STMT (e))
2058 bsi_commit_one_edge_insert (e, NULL);
2061 /* Find out how many edges there are with interesting pending stmts on them.
2062 Commit the stmts on edges we are not interested in. */
2063 FOR_EACH_EDGE (e, ei, bb->preds)
2065 if (PENDING_STMT (e))
2067 gcc_assert (!(e->flags & EDGE_ABNORMAL));
2068 if (e->flags & EDGE_FALLTHRU)
2070 bsi = bsi_start (e->src);
2071 if (!bsi_end_p (bsi))
2073 stmt = bsi_stmt (bsi);
2075 gcc_assert (stmt != NULL_TREE);
2076 is_label = (TREE_CODE (stmt) == LABEL_EXPR);
2077 /* Punt if it has non-label stmts, or isn't local. */
2078 if (!is_label || DECL_NONLOCAL (TREE_OPERAND (stmt, 0))
2079 || !bsi_end_p (bsi))
2081 bsi_commit_one_edge_insert (e, NULL);
2091 /* If there aren't at least 2 edges, no sharing will happen. */
2095 bsi_commit_one_edge_insert (single_edge, NULL);
2099 /* Ensure that we have empty worklists. */
2100 #ifdef ENABLE_CHECKING
2101 gcc_assert (VEC_length (edge, edge_leader) == 0);
2102 gcc_assert (VEC_length (tree, stmt_list) == 0);
2103 gcc_assert (bitmap_empty_p (leader_has_match));
2106 /* Find the "leader" block for each set of unique stmt lists. Preference is
2107 given to FALLTHRU blocks since they would need a GOTO to arrive at another
2108 block. The leader edge destination is the block which all the other edges
2109 with the same stmt list will be redirected to. */
2110 have_opportunity = false;
2111 FOR_EACH_EDGE (e, ei, bb->preds)
2113 if (PENDING_STMT (e))
2117 /* Look for the same stmt list in edge leaders list. */
2118 for (x = 0; VEC_iterate (edge, edge_leader, x, leader); x++)
2120 if (identical_stmt_lists_p (leader, e))
2122 /* Give this edge the same stmt list pointer. */
2123 PENDING_STMT (e) = NULL;
2125 bitmap_set_bit (leader_has_match, x);
2126 have_opportunity = found = true;
2131 /* If no similar stmt list, add this edge to the leader list. */
2134 VEC_safe_push (edge, heap, edge_leader, e);
2135 VEC_safe_push (tree, heap, stmt_list, PENDING_STMT (e));
2140 /* If there are no similar lists, just issue the stmts. */
2141 if (!have_opportunity)
2143 for (x = 0; VEC_iterate (edge, edge_leader, x, leader); x++)
2144 bsi_commit_one_edge_insert (leader, NULL);
2145 VEC_truncate (edge, edge_leader, 0);
2146 VEC_truncate (tree, stmt_list, 0);
2147 bitmap_clear (leader_has_match);
2153 fprintf (debug_file, "\nOpportunities in BB %d for stmt/block reduction:\n",
2157 /* For each common list, create a forwarding block and issue the stmt's
2159 for (x = 0; VEC_iterate (edge, edge_leader, x, leader); x++)
2160 if (bitmap_bit_p (leader_has_match, x))
2163 block_stmt_iterator bsi;
2164 tree curr_stmt_list;
2166 leader_match = leader;
2168 /* The tree_* cfg manipulation routines use the PENDING_EDGE field
2169 for various PHI manipulations, so it gets cleared whhen calls are
2170 made to make_forwarder_block(). So make sure the edge is clear,
2171 and use the saved stmt list. */
2172 PENDING_STMT (leader) = NULL;
2173 leader->aux = leader;
2174 curr_stmt_list = VEC_index (tree, stmt_list, x);
2176 new_edge = make_forwarder_block (leader->dest, same_stmt_list_p,
2178 bb = new_edge->dest;
2181 fprintf (debug_file, "Splitting BB %d for Common stmt list. ",
2182 leader->dest->index);
2183 fprintf (debug_file, "Original block is now BB%d.\n", bb->index);
2184 print_generic_stmt (debug_file, curr_stmt_list, TDF_VOPS);
2187 FOR_EACH_EDGE (e, ei, new_edge->src->preds)
2191 fprintf (debug_file, " Edge (%d->%d) lands here.\n",
2192 e->src->index, e->dest->index);
2195 bsi = bsi_last (leader->dest);
2196 bsi_insert_after (&bsi, curr_stmt_list, BSI_NEW_STMT);
2198 leader_match = NULL;
2199 /* We should never get a new block now. */
2203 PENDING_STMT (leader) = VEC_index (tree, stmt_list, x);
2204 bsi_commit_one_edge_insert (leader, NULL);
2208 /* Clear the working data structures. */
2209 VEC_truncate (edge, edge_leader, 0);
2210 VEC_truncate (tree, stmt_list, 0);
2211 bitmap_clear (leader_has_match);
2215 /* This function will analyze the insertions which were performed on edges,
2216 and decide whether they should be left on that edge, or whether it is more
2217 efficient to emit some subset of them in a single block. All stmts are
2218 inserted somewhere, and if non-NULL, debug information is printed via
2222 perform_edge_inserts (FILE *dump_file)
2227 fprintf(dump_file, "Analyzing Edge Insertions.\n");
2229 /* analyze_edges_for_bb calls make_forwarder_block, which tries to
2230 incrementally update the dominator information. Since we don't
2231 need dominator information after this pass, go ahead and free the
2232 dominator information. */
2233 free_dominance_info (CDI_DOMINATORS);
2234 free_dominance_info (CDI_POST_DOMINATORS);
2236 /* Allocate data structures used in analyze_edges_for_bb. */
2237 init_analyze_edges_for_bb ();
2240 analyze_edges_for_bb (bb, dump_file);
2242 analyze_edges_for_bb (EXIT_BLOCK_PTR, dump_file);
2244 /* Free data structures used in analyze_edges_for_bb. */
2245 fini_analyze_edges_for_bb ();
2247 #ifdef ENABLE_CHECKING
2253 FOR_EACH_EDGE (e, ei, bb->preds)
2255 if (PENDING_STMT (e))
2256 error (" Pending stmts not issued on PRED edge (%d, %d)\n",
2257 e->src->index, e->dest->index);
2259 FOR_EACH_EDGE (e, ei, bb->succs)
2261 if (PENDING_STMT (e))
2262 error (" Pending stmts not issued on SUCC edge (%d, %d)\n",
2263 e->src->index, e->dest->index);
2266 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2268 if (PENDING_STMT (e))
2269 error (" Pending stmts not issued on ENTRY edge (%d, %d)\n",
2270 e->src->index, e->dest->index);
2272 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
2274 if (PENDING_STMT (e))
2275 error (" Pending stmts not issued on EXIT edge (%d, %d)\n",
2276 e->src->index, e->dest->index);
2283 /* Remove the variables specified in MAP from SSA form. Any debug information
2284 is sent to DUMP. FLAGS indicate what options should be used. */
2287 remove_ssa_form (FILE *dump, var_map map, int flags)
2289 tree_live_info_p liveinfo;
2293 tree *values = NULL;
2298 /* If we are not combining temps, don't calculate live ranges for variables
2299 with only one SSA version. */
2300 if ((flags & SSANORM_COMBINE_TEMPS) == 0)
2301 compact_var_map (map, VARMAP_NO_SINGLE_DEFS);
2303 compact_var_map (map, VARMAP_NORMAL);
2305 if (dump_file && (dump_flags & TDF_DETAILS))
2306 dump_var_map (dump_file, map);
2308 liveinfo = coalesce_ssa_name (map, flags);
2310 /* Make sure even single occurrence variables are in the list now. */
2311 if ((flags & SSANORM_COMBINE_TEMPS) == 0)
2312 compact_var_map (map, VARMAP_NORMAL);
2314 if (dump_file && (dump_flags & TDF_DETAILS))
2316 fprintf (dump_file, "After Coalescing:\n");
2317 dump_var_map (dump_file, map);
2320 if (flags & SSANORM_PERFORM_TER)
2322 values = find_replaceable_exprs (map);
2323 if (values && dump_file && (dump_flags & TDF_DETAILS))
2324 dump_replaceable_exprs (dump_file, values);
2327 /* Assign real variables to the partitions now. */
2330 if (dump_file && (dump_flags & TDF_DETAILS))
2332 fprintf (dump_file, "After Root variable replacement:\n");
2333 dump_var_map (dump_file, map);
2336 if ((flags & SSANORM_COMBINE_TEMPS) && liveinfo)
2338 coalesce_vars (map, liveinfo);
2339 if (dump_file && (dump_flags & TDF_DETAILS))
2341 fprintf (dump_file, "After variable memory coalescing:\n");
2342 dump_var_map (dump_file, map);
2347 delete_tree_live_info (liveinfo);
2349 rewrite_trees (map, values);
2354 /* Remove phi nodes which have been translated back to real variables. */
2357 for (phi = phi_nodes (bb); phi; phi = next)
2359 next = PHI_CHAIN (phi);
2360 remove_phi_node (phi, NULL_TREE);
2364 /* we no longer maintain the SSA operand cache at this point. */
2365 fini_ssa_operands ();
2367 /* If any copies were inserted on edges, analyze and insert them now. */
2368 perform_edge_inserts (dump_file);
2373 /* Search every PHI node for arguments associated with backedges which
2374 we can trivially determine will need a copy (the argument is either
2375 not an SSA_NAME or the argument has a different underlying variable
2376 than the PHI result).
2378 Insert a copy from the PHI argument to a new destination at the
2379 end of the block with the backedge to the top of the loop. Update
2380 the PHI argument to reference this new destination. */
2383 insert_backedge_copies (void)
2391 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
2393 tree result = PHI_RESULT (phi);
2397 if (!is_gimple_reg (result))
2400 result_var = SSA_NAME_VAR (result);
2401 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
2403 tree arg = PHI_ARG_DEF (phi, i);
2404 edge e = PHI_ARG_EDGE (phi, i);
2406 /* If the argument is not an SSA_NAME, then we will
2407 need a constant initialization. If the argument is
2408 an SSA_NAME with a different underlying variable and
2409 we are not combining temporaries, then we will
2410 need a copy statement. */
2411 if ((e->flags & EDGE_DFS_BACK)
2412 && (TREE_CODE (arg) != SSA_NAME
2413 || (!flag_tree_combine_temps
2414 && SSA_NAME_VAR (arg) != result_var)))
2416 tree stmt, name, last = NULL;
2417 block_stmt_iterator bsi;
2419 bsi = bsi_last (PHI_ARG_EDGE (phi, i)->src);
2420 if (!bsi_end_p (bsi))
2421 last = bsi_stmt (bsi);
2423 /* In theory the only way we ought to get back to the
2424 start of a loop should be with a COND_EXPR or GOTO_EXPR.
2425 However, better safe than sorry.
2427 If the block ends with a control statement or
2428 something that might throw, then we have to
2429 insert this assignment before the last
2430 statement. Else insert it after the last statement. */
2431 if (last && stmt_ends_bb_p (last))
2433 /* If the last statement in the block is the definition
2434 site of the PHI argument, then we can't insert
2435 anything after it. */
2436 if (TREE_CODE (arg) == SSA_NAME
2437 && SSA_NAME_DEF_STMT (arg) == last)
2441 /* Create a new instance of the underlying
2442 variable of the PHI result. */
2443 stmt = build (MODIFY_EXPR, TREE_TYPE (result_var),
2444 NULL, PHI_ARG_DEF (phi, i));
2445 name = make_ssa_name (result_var, stmt);
2446 TREE_OPERAND (stmt, 0) = name;
2448 /* Insert the new statement into the block and update
2450 if (last && stmt_ends_bb_p (last))
2451 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2453 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2454 SET_PHI_ARG_DEF (phi, i, name);
2461 /* Take the current function out of SSA form, as described in
2462 R. Morgan, ``Building an Optimizing Compiler'',
2463 Butterworth-Heinemann, Boston, MA, 1998. pp 176-186. */
2466 rewrite_out_of_ssa (void)
2472 /* If elimination of a PHI requires inserting a copy on a backedge,
2473 then we will have to split the backedge which has numerous
2474 undesirable performance effects.
2476 A significant number of such cases can be handled here by inserting
2477 copies into the loop itself. */
2478 insert_backedge_copies ();
2480 if (!flag_tree_live_range_split)
2481 ssa_flags |= SSANORM_COALESCE_PARTITIONS;
2483 eliminate_virtual_phis ();
2485 if (dump_file && (dump_flags & TDF_DETAILS))
2486 dump_tree_cfg (dump_file, dump_flags & ~TDF_DETAILS);
2488 /* We cannot allow unssa to un-gimplify trees before we instrument them. */
2489 if (flag_tree_ter && !flag_mudflap)
2490 var_flags = SSA_VAR_MAP_REF_COUNT;
2492 map = create_ssa_var_map (var_flags);
2494 if (flag_tree_combine_temps)
2495 ssa_flags |= SSANORM_COMBINE_TEMPS;
2496 if (flag_tree_ter && !flag_mudflap)
2497 ssa_flags |= SSANORM_PERFORM_TER;
2499 remove_ssa_form (dump_file, map, ssa_flags);
2501 if (dump_file && (dump_flags & TDF_DETAILS))
2502 dump_tree_cfg (dump_file, dump_flags & ~TDF_DETAILS);
2504 /* Flush out flow graph and SSA data. */
2505 delete_var_map (map);
2507 /* Mark arrays indexed with non-constant indices with TREE_ADDRESSABLE. */
2508 discover_nonconstant_array_refs ();
2514 /* Define the parameters of the out of SSA pass. */
2516 struct tree_opt_pass pass_del_ssa =
2518 "optimized", /* name */
2520 rewrite_out_of_ssa, /* execute */
2523 0, /* static_pass_number */
2524 TV_TREE_SSA_TO_NORMAL, /* tv_id */
2525 PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */
2526 0, /* properties_provided */
2527 /* ??? If TER is enabled, we also kill gimple. */
2528 PROP_ssa, /* properties_destroyed */
2529 TODO_verify_ssa | TODO_verify_flow
2530 | TODO_verify_stmts, /* todo_flags_start */
2531 TODO_dump_func | TODO_ggc_collect, /* todo_flags_finish */