2 * Copyright (C) 1995-2008 University of Karlsruhe. All right reserved.
4 * This file is part of libFirm.
6 * This file may be distributed and/or modified under the terms of the
7 * GNU General Public License version 2 as published by the Free Software
8 * Foundation and appearing in the file LICENSE.GPL included in the
9 * packaging of this file.
11 * Licensees holding valid libFirm Professional Edition licenses may use
12 * this file in accordance with the libFirm Commercial License.
13 * Agreement provided with the Software.
15 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
16 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * @brief Cliff Click's Combined Analysis/Optimization
23 * @author Michael Beck
26 * Note that the current implementation lack the leaders/followers
29 * Note further that we use the terminology from Click's work here, which is different
30 * in some cases from Firm terminology. Especially, Click's type is a
31 * Firm tarval/entity, nevertheless we call it type here for "maximum compatibility".
39 #include "iroptimize.h"
46 #include "irgraph_t.h"
61 /* define this to check that all type translations are monotone */
62 #define VERIFY_MONOTONE
64 typedef struct node_t node_t;
65 typedef struct partition_t partition_t;
66 typedef struct opcode_key_t opcode_key_t;
67 typedef struct listmap_entry_t listmap_entry_t;
69 /** The type of the compute function. */
70 typedef void (*compute_func)(node_t *node);
76 ir_opcode code; /**< The Firm opcode. */
77 ir_mode *mode; /**< The mode of all nodes in the partition. */
79 long proj; /**< For Proj nodes, its proj number */
80 ir_entity *ent; /**< For Sel Nodes, its entity */
85 * An entry in the list_map.
87 struct listmap_entry_t {
88 void *id; /**< The id. */
89 node_t *list; /**< The associated list for this id. */
90 listmap_entry_t *next; /**< Link to the next entry in the map. */
93 /** We must map id's to lists. */
94 typedef struct listmap_t {
95 set *map; /**< Map id's to listmap_entry_t's */
96 listmap_entry_t *values; /**< List of all values in the map. */
100 * A lattice element. Because we handle constants and symbolic constants different, we
101 * have to use this union.
112 ir_node *node; /**< The IR-node itself. */
113 list_head node_list; /**< Double-linked list of entries. */
114 list_head cprop_list; /**< Double-linked partition.cprop list. */
115 partition_t *part; /**< points to the partition this node belongs to */
116 node_t *next; /**< Next node on local list (partition.touched, fallen). */
117 lattice_elem_t type; /**< The associated lattice element "type". */
118 int max_user_input; /**< Maximum input number of Def-Use edges. */
119 int next_edge; /**< Index of the next Def-Use edge to use. */
120 unsigned on_touched:1; /**< Set, if this node is on the partition.touched set. */
121 unsigned on_cprop:1; /**< Set, if this node is on the partition.cprop list. */
122 unsigned on_fallen:1; /**< Set, if this node is on the fallen list. */
126 * A partition containing congruent nodes.
129 list_head entries; /**< The head of partition node list. */
130 list_head cprop; /**< The head of partition.cprop list. */
131 partition_t *wl_next; /**< Next entry in the work list if any. */
132 partition_t *touched_next; /**< Points to the next partition in the touched set. */
133 partition_t *cprop_next; /**< Points to the next partition in the cprop list. */
134 partition_t *split_next; /**< Points to the next partition in the list that must be split by split_by(). */
135 node_t *touched; /**< The partition.touched set of this partition. */
136 unsigned n_nodes; /**< Number of entries in this partition. */
137 unsigned n_touched; /**< Number of entries in the partition.touched. */
138 int max_user_inputs; /**< Maximum number of user inputs of all entries. */
139 unsigned on_worklist:1; /**< Set, if this partition is in the work list. */
140 unsigned on_touched:1; /**< Set, if this partition is on the touched set. */
141 unsigned on_cprop:1; /**< Set, if this partition is on the cprop list. */
143 partition_t *dbg_next; /**< Link all partitions for debugging */
144 unsigned nr; /**< A unique number for (what-)mapping, >0. */
148 typedef struct environment_t {
149 struct obstack obst; /**< obstack to allocate data structures. */
150 partition_t *worklist; /**< The work list. */
151 partition_t *cprop; /**< The constant propagation list. */
152 partition_t *touched; /**< the touched set. */
153 partition_t *initial; /**< The initial partition. */
154 set *opcode2id_map; /**< The opcodeMode->id map. */
155 pmap *type2id_map; /**< The type->id map. */
156 int end_idx; /**< -1 for local and 0 for global congruences. */
157 int lambda_input; /**< Captured argument for lambda_partition(). */
158 int modified; /**< Set, if the graph was modified. */
160 partition_t *dbg_list; /**< List of all partitions. */
164 /** Type of the what function. */
165 typedef void *(*what_func)(const node_t *node, environment_t *env);
167 #define get_irn_node(irn) ((node_t *)get_irn_link(irn))
168 #define set_irn_node(irn, node) set_irn_link(irn, node)
170 /* we do NOT use tarval_unreachable here, instead we use Top for this purpose */
171 #undef tarval_unreachable
172 #define tarval_unreachable tarval_top
175 /** The debug module handle. */
176 DEBUG_ONLY(static firm_dbg_module_t *dbg;)
178 /** Next partition number. */
179 DEBUG_ONLY(static unsigned part_nr = 0);
182 static INLINE lattice_elem_t get_partition_type(const partition_t *X);
185 * Dump partition to output.
187 static void dump_partition(const char *msg, const partition_t *part) {
190 lattice_elem_t type = get_partition_type(part);
192 DB((dbg, LEVEL_2, "%s part%u (%u, %+F) {\n ", msg, part->nr, part->n_nodes, type));
193 list_for_each_entry(node_t, node, &part->entries, node_list) {
194 DB((dbg, LEVEL_2, "%s%+F", first ? "" : ", ", node->node));
197 DB((dbg, LEVEL_2, "\n}\n"));
201 * Dump all partitions.
203 static void dump_all_partitions(const environment_t *env) {
204 const partition_t *P;
206 DB((dbg, LEVEL_2, "All partitions\n===============\n"));
207 for (P = env->dbg_list; P != NULL; P = P->dbg_next)
208 dump_partition("", P);
212 #define dump_partition(msg, part)
213 #define dump_all_partitions(env)
216 #if defined(VERIFY_MONOTONE) && defined (DEBUG_libfirm)
218 * Verify that a type transition is monotone
220 static void verify_type(const lattice_elem_t old_type, const lattice_elem_t new_type) {
221 if (old_type.tv == new_type.tv) {
225 if (old_type.tv == tarval_top) {
226 /* from Top down-to is always allowed */
229 if (old_type.tv == tarval_reachable) {
230 panic("verify_type(): wrong translation from %+F to %+F", old_type, new_type);
232 if (new_type.tv == tarval_bottom || new_type.tv == tarval_reachable) {
236 panic("verify_type(): wrong translation from %+F to %+F", old_type, new_type);
239 #define verify_type(old_type, new_type)
243 * Compare two pointer values of a listmap.
245 static int listmap_cmp_ptr(const void *elt, const void *key, size_t size) {
246 const listmap_entry_t *e1 = elt;
247 const listmap_entry_t *e2 = key;
250 return e1->id != e2->id;
251 } /* listmap_cmp_ptr */
254 * Initializes a listmap.
256 * @param map the listmap
258 static void listmap_init(listmap_t *map) {
259 map->map = new_set(listmap_cmp_ptr, 16);
264 * Terminates a listmap.
266 * @param map the listmap
268 static void listmap_term(listmap_t *map) {
273 * Return the associated listmap entry for a given id.
275 * @param map the listmap
276 * @param id the id to search for
278 * @return the asociated listmap entry for the given id
280 static listmap_entry_t *listmap_find(listmap_t *map, void *id) {
281 listmap_entry_t key, *entry;
286 entry = set_insert(map->map, &key, sizeof(key), HASH_PTR(id));
288 if (entry->list == NULL) {
289 /* a new entry, put into the list */
290 entry->next = map->values;
297 * Calculate the hash value for an opcode map entry.
299 * @param entry an opcode map entry
301 * @return a hash value for the given opcode map entry
303 static unsigned opcode_hash(const opcode_key_t *entry) {
304 return (entry->mode - (ir_mode *)0) * 9 + entry->code + entry->u.proj * 3 + HASH_PTR(entry->u.ent);
308 * Compare two entries in the opcode map.
310 static int cmp_opcode(const void *elt, const void *key, size_t size) {
311 const opcode_key_t *o1 = elt;
312 const opcode_key_t *o2 = key;
315 return o1->code != o2->code || o1->mode != o2->mode ||
316 o1->u.proj != o2->u.proj || o1->u.ent != o2->u.ent;
320 * Compare two Def-Use edges for input position.
322 static int cmp_def_use_edge(const void *a, const void *b) {
323 const ir_def_use_edge *ea = a;
324 const ir_def_use_edge *eb = b;
326 /* no overrun, because range is [-1, MAXINT] */
327 return ea->pos - eb->pos;
328 } /* cmp_def_use_edge */
331 * We need the Def-Use edges sorted.
333 static void sort_irn_outs(node_t *node) {
334 ir_node *irn = node->node;
335 int n_outs = get_irn_n_outs(irn);
338 qsort(&irn->out[1], n_outs, sizeof(irn->out[0]), cmp_def_use_edge);
340 node->max_user_input = irn->out[n_outs].pos;
341 } /* sort_irn_outs */
344 * Return the type of a node.
346 * @param irn an IR-node
348 * @return the associated type of this node
350 static INLINE lattice_elem_t get_node_type(const ir_node *irn) {
351 return get_irn_node(irn)->type;
352 } /* get_node_type */
355 * Return the tarval of a node.
357 * @param irn an IR-node
359 * @return the associated type of this node
361 static INLINE tarval *get_node_tarval(const ir_node *irn) {
362 lattice_elem_t type = get_node_type(irn);
364 if (is_tarval(type.tv))
366 return tarval_bottom;
367 } /* get_node_type */
370 * Add a partition to the worklist.
372 static INLINE void add_to_worklist(partition_t *X, environment_t *env) {
373 assert(X->on_worklist == 0);
374 X->wl_next = env->worklist;
380 * Create a new empty partition.
382 * @param env the environment
384 * @return a newly allocated partition
386 static INLINE partition_t *new_partition(environment_t *env) {
387 partition_t *part = obstack_alloc(&env->obst, sizeof(*part));
389 INIT_LIST_HEAD(&part->entries);
390 INIT_LIST_HEAD(&part->cprop);
391 part->wl_next = NULL;
392 part->touched_next = NULL;
393 part->cprop_next = NULL;
394 part->split_next = NULL;
395 part->touched = NULL;
398 part->max_user_inputs = 0;
399 part->on_worklist = 0;
400 part->on_touched = 0;
403 part->dbg_next = env->dbg_list;
404 env->dbg_list = part;
405 part->nr = part_nr++;
409 } /* new_partition */
412 * Get the first node from a partition.
414 static INLINE node_t *get_first_node(const partition_t *X) {
415 return list_entry(X->entries.next, node_t, node_list);
419 * Return the type of a partition (assuming partition is non-empty and
420 * all elements have the same type).
422 * @param X a partition
424 * @return the type of the first element of the partition
426 static INLINE lattice_elem_t get_partition_type(const partition_t *X) {
427 const node_t *first = get_first_node(X);
429 } /* get_partition_type */
432 * Creates a partition node for the given IR-node and place it
433 * into the given partition.
435 * @param irn an IR-node
436 * @param part a partition to place the node in
437 * @param env the environment
439 * @return the created node
441 static node_t *create_partition_node(ir_node *irn, partition_t *part, environment_t *env) {
442 /* create a partition node and place it in the partition */
443 node_t *node = obstack_alloc(&env->obst, sizeof(*node));
445 INIT_LIST_HEAD(&node->node_list);
446 INIT_LIST_HEAD(&node->cprop_list);
450 node->type.tv = tarval_top;
451 node->max_user_input = 0;
453 node->on_touched = 0;
456 set_irn_node(irn, node);
458 list_add_tail(&node->node_list, &part->entries);
462 } /* create_partition_node */
465 * Pre-Walker, init all Block-Phi lists.
467 static void init_block_phis(ir_node *irn, void *env) {
471 set_Block_phis(irn, NULL);
476 * Post-Walker, initialize all Nodes' type to U or top and place
477 * all nodes into the TOP partition.
479 static void create_initial_partitions(ir_node *irn, void *ctx) {
480 environment_t *env = ctx;
481 partition_t *part = env->initial;
484 node = create_partition_node(irn, part, env);
486 if (node->max_user_input > part->max_user_inputs)
487 part->max_user_inputs = node->max_user_input;
490 add_Block_phi(get_nodes_block(irn), irn);
492 } /* create_initial_partitions */
495 * Add a partition to the touched set if not already there.
497 * @param part the partition
498 * @param env the environment
500 static INLINE void add_to_touched(partition_t *part, environment_t *env) {
501 if (part->on_touched == 0) {
502 part->touched_next = env->touched;
504 part->on_touched = 1;
506 } /* add_to_touched */
509 * Add a node to the entry.partition.touched set if not already there.
513 static INLINE void add_to_partition_touched(node_t *y) {
514 if (y->on_touched == 0) {
515 partition_t *part = y->part;
517 y->next = part->touched;
522 } /* add_to_partition_touched */
525 * Update the worklist: If Z is on worklist then add Z' to worklist.
526 * Else add the smaller of Z and Z' to worklist.
528 * @param Z the Z partition
529 * @param Z_prime the Z' partition, a previous part of Z
530 * @param env the environment
532 static void update_worklist(partition_t *Z, partition_t *Z_prime, environment_t *env) {
533 if (Z->on_worklist || Z_prime->n_nodes < Z->n_nodes) {
534 add_to_worklist(Z_prime, env);
536 add_to_worklist(Z, env);
538 } /* update_worklist */
541 * Split a partition by a local list.
543 * @param Z the Z partition to split
544 * @param g a (non-empty) node list
545 * @param env the environment
547 * @return a new partition containing the nodes of g
549 static partition_t *split(partition_t *Z, node_t *g, environment_t *env) {
550 partition_t *Z_prime;
553 int max_input, max_arity, arity;
555 dump_partition("Splitting ", Z);
559 /* Remove g from Z. */
560 for (node = g; node != NULL; node = node->next) {
561 list_del(&node->node_list);
564 assert(n < Z->n_nodes);
567 /* Move g to a new partition, Z
\92. */
568 Z_prime = new_partition(env);
569 max_arity = max_input = 0;
570 for (node = g; node != NULL; node = node->next) {
571 list_add(&node->node_list, &Z_prime->entries);
572 node->part = Z_prime;
573 arity = get_irn_arity(node->node);
574 if (arity > max_arity)
576 if (node->max_user_input > max_input)
577 max_input = node->max_user_input;
579 Z_prime->max_user_inputs = max_input;
580 Z_prime->n_nodes = n;
582 update_worklist(Z, Z_prime, env);
584 dump_partition("Now ", Z);
585 dump_partition("Created new ", Z_prime);
590 * Returns non-zero if the i'th input of a Phi node is live.
592 * @param phi a Phi-node
593 * @param i an input number
595 * @return non-zero if the i'th input of the given Phi node is live
597 static int is_live_input(ir_node *phi, int i) {
599 ir_node *block = get_nodes_block(phi);
600 ir_node *pred = get_Block_cfgpred(block, i);
601 lattice_elem_t type = get_node_type(pred);
603 return type.tv != tarval_unreachable;
605 /* else it's the control input, always live */
607 } /* is_live_input */
610 * Return non-zero if a type is a constant.
612 static int is_constant_type(lattice_elem_t type) {
613 if (type.tv != tarval_bottom && type.tv != tarval_top)
616 } /* is_constant_type */
619 * Place a node on the cprop list.
622 * @param env the environment
624 static void add_node_to_cprop(node_t *y, environment_t *env) {
625 /* Add y to y.partition.cprop. */
626 if (y->on_cprop == 0) {
627 partition_t *Y = y->part;
629 list_add_tail(&y->cprop_list, &Y->cprop);
632 DB((dbg, LEVEL_3, "Add %+F to part%u.cprop\n", y->node, Y->nr));
634 /* place its partition on the cprop list */
635 if (Y->on_cprop == 0) {
636 Y->cprop_next = env->cprop;
641 if (get_irn_mode(y->node) == mode_T) {
642 /* mode_T nodes always produce tarval_bottom, so we must explicitly
643 add it's Proj's to get constant evaluation to work */
646 for (i = get_irn_n_outs(y->node) - 1; i >= 0; --i) {
647 node_t *proj = get_irn_node(get_irn_out(y->node, i));
649 add_node_to_cprop(proj, env);
653 if (is_Block(y->node)) {
654 /* Due to the way we handle Phi's, we must place all Phis of a block on the list
655 * if someone placed the block. The Block is only placed if the reachability
656 * changes, and this must be re-evaluated in compute_Phi(). */
658 for (phi = get_Block_phis(y->node); phi != NULL; phi = get_Phi_next(phi)) {
659 node_t *p = get_irn_node(phi);
660 add_node_to_cprop(p, env);
663 } /* add_node_to_cprop */
666 * Check whether a type is neither Top or a constant.
667 * Note: U is handled like Top here, R is a constant.
669 * @param type the type to check
671 static int type_is_neither_top_nor_const(const lattice_elem_t type) {
672 if (is_tarval(type.tv)) {
673 if (type.tv == tarval_top)
675 if (tarval_is_constant(type.tv))
685 * Split the partitions if caused by the first entry on the worklist.
687 * @param env the environment
689 static void cause_splits(environment_t *env) {
690 partition_t *X, *Y, *Z;
696 /* remove the first partition from the worklist */
698 env->worklist = X->wl_next;
701 dump_partition("Cause_split: ", X);
702 end_idx = env->end_idx;
703 for (i = -1; i <= X->max_user_inputs; ++i) {
704 /* empty the touched set: already done, just clear the list */
707 list_for_each_entry(node_t, x, &X->entries, node_list) {
713 num_edges = get_irn_n_outs(x->node);
715 while (x->next_edge <= num_edges) {
716 ir_def_use_edge *edge = &x->node->out[x->next_edge];
718 /* check if we have necessary edges */
726 /* ignore the "control input" for non-pinned nodes
727 if we are running in GCSE mode */
728 if (i < end_idx && get_irn_pinned(succ) != op_pin_state_pinned)
731 y = get_irn_node(succ);
732 if (is_constant_type(y->type)) {
733 code = get_irn_opcode(succ);
734 if (code == iro_Sub || code == iro_Cmp)
735 add_node_to_cprop(y, env);
738 /* Partitions of constants should not be split simply because their Nodes have unequal
739 functions or incongruent inputs. */
740 if (type_is_neither_top_nor_const(y->type) &&
741 (! is_Phi(y->node) || is_live_input(y->node, i))) {
743 add_to_touched(Y, env);
744 add_to_partition_touched(y);
749 for (Z = env->touched; Z != NULL; Z = Z->touched_next) {
750 /* remove it from the touched set */
753 if (Z->n_nodes != Z->n_touched) {
754 DB((dbg, LEVEL_2, "Split part%d by touched\n", Z->nr));
755 split(Z, Z->touched, env);
757 /* Empty local Z.touched. */
758 for (e = Z->touched; e != NULL; e = e->next) {
768 * Implements split_by_what(): Split a partition by characteristics given
769 * by the what function.
771 * @param X the partition to split
772 * @param What a function returning an Id for every node of the partition X
773 * @param P a list to store the result partitions
774 * @param env the environment
778 static partition_t *split_by_what(partition_t *X, what_func What,
779 partition_t **P, environment_t *env) {
782 listmap_entry_t *iter;
785 /* Let map be an empty mapping from the range of What to (local) list of Nodes. */
787 list_for_each_entry(node_t, x, &X->entries, node_list) {
788 void *id = What(x, env);
789 listmap_entry_t *entry;
792 /* input not allowed, ignore */
795 /* Add x to map[What(x)]. */
796 entry = listmap_find(&map, id);
797 x->next = entry->list;
800 /* Let P be a set of Partitions. */
802 /* for all sets S except one in the range of map do */
803 for (iter = map.values; iter != NULL; iter = iter->next) {
804 if (iter->next == NULL) {
805 /* this is the last entry, ignore */
810 /* Add SPLIT( X, S ) to P. */
811 DB((dbg, LEVEL_2, "Split part%d by what\n", X->nr));
812 R = split(X, S, env);
822 } /* split_by_what */
824 /** lambda n.(n.type) */
825 static void *lambda_type(const node_t *node, environment_t *env) {
827 return node->type.tv;
830 /** lambda n.(n.opcode) */
831 static void *lambda_opcode(const node_t *node, environment_t *env) {
832 opcode_key_t key, *entry;
833 ir_node *irn = node->node;
835 key.code = get_irn_opcode(irn);
836 key.mode = get_irn_mode(irn);
840 switch (get_irn_opcode(irn)) {
842 key.u.proj = get_Proj_proj(irn);
845 key.u.ent = get_Sel_entity(irn);
851 entry = set_insert(env->opcode2id_map, &key, sizeof(key), opcode_hash(&key));
853 } /* lambda_opcode */
855 /** lambda n.(n[i].partition) */
856 static void *lambda_partition(const node_t *node, environment_t *env) {
857 ir_node *skipped = skip_Proj(node->node);
860 int i = env->lambda_input;
862 if (i >= get_irn_arity(node->node)) {
863 /* we are outside the allowed range */
867 /* ignore the "control input" for non-pinned nodes
868 if we are running in GCSE mode */
869 if (i < env->end_idx && get_irn_pinned(skipped) != op_pin_state_pinned)
872 pred = i == -1 ? get_irn_n(skipped, i) : get_irn_n(node->node, i);
873 p = get_irn_node(pred);
876 } /* lambda_partition */
879 * Checks whether a type is a constant.
881 static int is_type_constant(lattice_elem_t type) {
882 if (is_tarval(type.tv))
883 return tarval_is_constant(type.tv);
884 /* else it is a symconst */
889 * Implements split_by().
891 * @param X the partition to split
892 * @param env the environment
894 static void split_by(partition_t *X, environment_t *env) {
895 partition_t *P = NULL;
898 DB((dbg, LEVEL_2, "WHAT = lambda n.(n.type) on part%d\n", X->nr));
899 P = split_by_what(X, lambda_type, &P, env);
904 if (Y->n_nodes > 1) {
905 lattice_elem_t type = get_partition_type(Y);
907 /* we do not want split the TOP or constant partitions */
908 if (type.tv != tarval_top && !is_type_constant(type)) {
909 partition_t *Q = NULL;
911 DB((dbg, LEVEL_2, "WHAT = lambda n.(n.opcode) on part%d\n", Y->nr));
912 Q = split_by_what(Y, lambda_opcode, &Q, env);
918 if (Z->n_nodes > 1) {
919 const node_t *first = get_first_node(Z);
920 int arity = get_irn_arity(first->node);
924 * BEWARE: during splitting by input 2 for instance we might
925 * create new partitions which are different by input 1, so collect
926 * them and split further.
928 Z->split_next = NULL;
931 for (input = arity - 1; input >= -1; --input) {
933 partition_t *Z_prime = R;
936 if (Z_prime->n_nodes > 1) {
937 env->lambda_input = input;
938 DB((dbg, LEVEL_2, "WHAT = lambda n.(n[%d].partition) on part%d\n", input, Z_prime->nr));
939 S = split_by_what(Z_prime, lambda_partition, &S, env);
941 Z_prime->split_next = S;
956 * (Re-)compute the type for a given node.
958 * @param node the node
960 static void default_compute(node_t *node) {
962 ir_node *irn = node->node;
963 node_t *block = get_irn_node(get_nodes_block(irn));
965 if (block->type.tv == tarval_unreachable) {
966 node->type.tv = tarval_top;
970 /* if any of the data inputs have type top, the result is type top */
971 for (i = get_irn_arity(irn) - 1; i >= 0; --i) {
972 ir_node *pred = get_irn_n(irn, i);
973 node_t *p = get_irn_node(pred);
975 if (p->type.tv == tarval_top) {
976 node->type.tv = tarval_top;
981 if (get_irn_mode(node->node) == mode_X)
982 node->type.tv = tarval_reachable;
984 node->type.tv = computed_value(irn);
985 } /* default_compute */
988 * (Re-)compute the type for a Block node.
990 * @param node the node
992 static void compute_Block(node_t *node) {
994 ir_node *block = node->node;
996 for (i = get_Block_n_cfgpreds(block) - 1; i >= 0; --i) {
997 node_t *pred = get_irn_node(get_Block_cfgpred(block, i));
999 if (pred->type.tv == tarval_reachable) {
1000 /* A block is reachable, if at least of predecessor is reachable. */
1001 node->type.tv = tarval_reachable;
1005 node->type.tv = tarval_top;
1006 } /* compute_Block */
1009 * (Re-)compute the type for a Bad node.
1011 * @param node the node
1013 static void compute_Bad(node_t *node) {
1014 /* Bad nodes ALWAYS compute Top */
1015 node->type.tv = tarval_top;
1019 * (Re-)compute the type for an Unknown node.
1021 * @param node the node
1023 static void compute_Unknown(node_t *node) {
1024 /* While Unknown nodes compute Top, but this is dangerous:
1025 * a if (unknown) would lead to BOTH control flows unreachable.
1026 * While this is correct in the given semantics, it would destroy the Firm
1028 * For now, we compute bottom here.
1030 node->type.tv = tarval_bottom;
1031 } /* compute_Unknown */
1034 * (Re-)compute the type for a Jmp node.
1036 * @param node the node
1038 static void compute_Jmp(node_t *node) {
1039 node_t *block = get_irn_node(get_nodes_block(node->node));
1041 node->type = block->type;
1045 * (Re-)compute the type for the End node.
1047 * @param node the node
1049 static void compute_End(node_t *node) {
1050 /* the End node is NOT dead of course */
1051 node->type.tv = tarval_reachable;
1055 * (Re-)compute the type for a SymConst node.
1057 * @param node the node
1059 static void compute_SymConst(node_t *node) {
1060 ir_node *irn = node->node;
1061 node_t *block = get_irn_node(get_nodes_block(irn));
1063 if (block->type.tv == tarval_unreachable) {
1064 node->type.tv = tarval_top;
1067 switch (get_SymConst_kind(irn)) {
1068 case symconst_addr_ent:
1069 /* case symconst_addr_name: cannot handle this yet */
1070 node->type.sym = get_SymConst_symbol(irn);
1073 node->type.tv = computed_value(irn);
1075 } /* compute_SymConst */
1078 * (Re-)compute the type for a Phi node.
1080 * @param node the node
1082 static void compute_Phi(node_t *node) {
1084 ir_node *phi = node->node;
1085 lattice_elem_t type;
1087 /* if a Phi is in a unreachable block, its type is TOP */
1088 node_t *block = get_irn_node(get_nodes_block(phi));
1090 if (block->type.tv == tarval_unreachable) {
1091 node->type.tv = tarval_top;
1095 /* Phi implements the Meet operation */
1096 type.tv = tarval_top;
1097 for (i = get_Phi_n_preds(phi) - 1; i >= 0; --i) {
1098 node_t *pred = get_irn_node(get_Phi_pred(phi, i));
1099 node_t *pred_X = get_irn_node(get_Block_cfgpred(block->node, i));
1101 if (pred_X->type.tv == tarval_unreachable || pred->type.tv == tarval_top) {
1102 /* ignore TOP inputs: We must check here for unreachable blocks,
1103 because Firm constants live in the Start Block are NEVER Top.
1104 Else, a Phi (1,2) will produce Bottom, even if the 2 for instance
1105 comes from a unreachable input. */
1108 if (pred->type.tv == tarval_bottom) {
1109 node->type.tv = tarval_bottom;
1111 } else if (type.tv == tarval_top) {
1112 /* first constant found */
1114 } else if (type.tv != pred->type.tv) {
1115 /* different constants or tarval_bottom */
1116 node->type.tv = tarval_bottom;
1119 /* else nothing, constants are the same */
1125 * (Re-)compute the type for an Add. Special case: one nodes is a Zero Const.
1127 * @param node the node
1129 static void compute_Add(node_t *node) {
1130 ir_node *sub = node->node;
1131 node_t *l = get_irn_node(get_Add_left(sub));
1132 node_t *r = get_irn_node(get_Add_right(sub));
1133 lattice_elem_t a = l->type;
1134 lattice_elem_t b = r->type;
1135 node_t *block = get_irn_node(get_nodes_block(sub));
1138 if (block->type.tv == tarval_unreachable) {
1139 node->type.tv = tarval_top;
1143 if (a.tv == tarval_top || b.tv == tarval_top) {
1144 node->type.tv = tarval_top;
1145 } else if (a.tv == tarval_bottom || b.tv == tarval_bottom) {
1146 node->type.tv = tarval_bottom;
1148 /* x + 0 = 0 + x = x, but beware of floating point +0 + -0, so we
1149 must call tarval_add() first to handle this case! */
1150 if (is_tarval(a.tv)) {
1151 if (is_tarval(b.tv)) {
1152 node->type.tv = tarval_add(a.tv, b.tv);
1155 mode = get_tarval_mode(a.tv);
1156 if (a.tv == get_mode_null(mode)) {
1160 } else if (is_tarval(b.tv)) {
1161 mode = get_tarval_mode(b.tv);
1162 if (b.tv == get_mode_null(mode)) {
1167 node->type.tv = tarval_bottom;
1172 * Returns true if a type is a constant.
1174 static int is_con(const lattice_elem_t type) {
1175 return is_entity(type.sym.entity_p) || tarval_is_constant(type.tv);
1179 * (Re-)compute the type for a Sub. Special case: both nodes are congruent.
1181 * @param node the node
1183 static void compute_Sub(node_t *node) {
1184 ir_node *sub = node->node;
1185 node_t *l = get_irn_node(get_Sub_left(sub));
1186 node_t *r = get_irn_node(get_Sub_right(sub));
1187 lattice_elem_t a = l->type;
1188 lattice_elem_t b = r->type;
1189 node_t *block = get_irn_node(get_nodes_block(sub));
1191 if (block->type.tv == tarval_unreachable) {
1192 node->type.tv = tarval_top;
1195 if (a.tv == tarval_top || b.tv == tarval_top) {
1196 node->type.tv = tarval_top;
1197 } else if (is_con(a) && is_con(b)) {
1198 if (is_tarval(a.tv) && is_tarval(b.tv)) {
1199 node->type.tv = tarval_sub(a.tv, b.tv, get_irn_mode(sub));
1200 } else if (is_tarval(a.tv) && tarval_is_null(a.tv)) {
1202 } else if (is_tarval(b.tv) && tarval_is_null(b.tv)) {
1205 node->type.tv = tarval_bottom;
1207 } else if (r->part == l->part &&
1208 (!mode_is_float(get_irn_mode(l->node)))) {
1209 if (node->type.tv == tarval_top) {
1211 * BEWARE: a - a is NOT always 0 for floating Point values, as
1212 * NaN op NaN = NaN, so we must check this here.
1214 ir_mode *mode = get_irn_mode(sub);
1215 node->type.tv = get_mode_null(mode);
1217 node->type.tv = tarval_bottom;
1220 node->type.tv = tarval_bottom;
1225 * (Re-)compute the type for Cmp.
1227 * @param node the node
1229 static void compute_Cmp(node_t *node) {
1230 ir_node *cmp = node->node;
1231 node_t *l = get_irn_node(get_Cmp_left(cmp));
1232 node_t *r = get_irn_node(get_Cmp_right(cmp));
1233 lattice_elem_t a = l->type;
1234 lattice_elem_t b = r->type;
1236 if (a.tv == tarval_top || b.tv == tarval_top) {
1237 node->type.tv = tarval_top;
1238 } else if (is_con(a) && is_con(b)) {
1239 /* both nodes are constants, we can propbably do something */
1240 node->type.tv = tarval_b_true;
1241 } else if (r->part == l->part) {
1242 /* both nodes congruent, we can probably do something */
1243 node->type.tv = tarval_b_true;
1245 node->type.tv = tarval_bottom;
1247 } /* compute_Proj_Cmp */
1250 * (Re-)compute the type for a Proj(Cmp).
1252 * @param node the node
1253 * @param cond the predecessor Cmp node
1255 static void compute_Proj_Cmp(node_t *node, ir_node *cmp) {
1256 ir_node *proj = node->node;
1257 node_t *l = get_irn_node(get_Cmp_left(cmp));
1258 node_t *r = get_irn_node(get_Cmp_right(cmp));
1259 lattice_elem_t a = l->type;
1260 lattice_elem_t b = r->type;
1261 pn_Cmp pnc = get_Proj_proj(proj);
1263 if (a.tv == tarval_top || b.tv == tarval_top) {
1264 node->type.tv = tarval_top;
1265 } else if (is_con(a) && is_con(b)) {
1266 default_compute(node);
1267 } else if (r->part == l->part &&
1268 (!mode_is_float(get_irn_mode(l->node)) || pnc == pn_Cmp_Lt || pnc == pn_Cmp_Gt)) {
1269 if (node->type.tv == tarval_top) {
1271 * BEWARE: a == a is NOT always True for floating Point values, as
1272 * NaN != NaN is defined, so we must check this here.
1274 node->type.tv = new_tarval_from_long(pnc & pn_Cmp_Eq, mode_b);
1276 node->type.tv = tarval_bottom;
1279 node->type.tv = tarval_bottom;
1281 } /* compute_Proj_Cmp */
1284 * (Re-)compute the type for a Proj(Cond).
1286 * @param node the node
1287 * @param cond the predecessor Cond node
1289 static void compute_Proj_Cond(node_t *node, ir_node *cond) {
1290 ir_node *proj = node->node;
1291 long pnc = get_Proj_proj(proj);
1292 ir_node *sel = get_Cond_selector(cond);
1293 node_t *selector = get_irn_node(sel);
1295 if (get_irn_mode(sel) == mode_b) {
1297 if (pnc == pn_Cond_true) {
1298 if (selector->type.tv == tarval_b_false) {
1299 node->type.tv = tarval_unreachable;
1300 } else if (selector->type.tv == tarval_b_true) {
1301 node->type.tv = tarval_reachable;
1302 } else if (selector->type.tv == tarval_bottom) {
1303 node->type.tv = tarval_reachable;
1305 assert(selector->type.tv == tarval_top);
1306 node->type.tv = tarval_unreachable;
1309 assert(pnc == pn_Cond_false);
1311 if (selector->type.tv == tarval_b_false) {
1312 node->type.tv = tarval_reachable;
1313 } else if (selector->type.tv == tarval_b_true) {
1314 node->type.tv = tarval_unreachable;
1315 } else if (selector->type.tv == tarval_bottom) {
1316 node->type.tv = tarval_reachable;
1318 assert(selector->type.tv == tarval_top);
1319 node->type.tv = tarval_unreachable;
1324 if (selector->type.tv == tarval_bottom) {
1325 node->type.tv = tarval_reachable;
1326 } else if (selector->type.tv == tarval_top) {
1327 node->type.tv = tarval_unreachable;
1329 long value = get_tarval_long(selector->type.tv);
1330 if (pnc == get_Cond_defaultProj(cond)) {
1331 /* default switch, have to check ALL other cases */
1334 for (i = get_irn_n_outs(cond) - 1; i >= 0; --i) {
1335 ir_node *succ = get_irn_out(cond, i);
1339 if (value == get_Proj_proj(succ)) {
1340 /* we found a match, will NOT take the default case */
1341 node->type.tv = tarval_unreachable;
1345 /* all cases checked, no match, will take default case */
1346 node->type.tv = tarval_reachable;
1349 node->type.tv = value == pnc ? tarval_reachable : tarval_unreachable;
1353 } /* compute_Proj_Cond */
1356 * (Re-)compute the type for a Proj-Nodes.
1358 * @param node the node
1360 static void compute_Proj(node_t *node) {
1361 ir_node *proj = node->node;
1362 ir_mode *mode = get_irn_mode(proj);
1363 node_t *block = get_irn_node(get_nodes_block(skip_Proj(proj)));
1364 ir_node *pred = get_Proj_pred(proj);
1366 if (get_Proj_proj(proj) == pn_Start_X_initial_exec && is_Start(pred)) {
1367 /* The initial_exec node is ALWAYS reachable. */
1368 node->type.tv = tarval_reachable;
1372 if (block->type.tv == tarval_unreachable) {
1373 /* a Proj in a unreachable Block stay Top */
1374 node->type.tv = tarval_top;
1377 if (get_irn_node(pred)->type.tv == tarval_top) {
1378 /* if the predecessor is Top, its Proj follow */
1379 node->type.tv = tarval_top;
1383 if (mode == mode_M) {
1384 /* mode M is always bottom */
1385 node->type.tv = tarval_bottom;
1388 if (mode != mode_X) {
1390 compute_Proj_Cmp(node, pred);
1392 default_compute(node);
1395 /* handle mode_X nodes */
1397 switch (get_irn_opcode(pred)) {
1399 /* the Proj_X from the Start is always reachable.
1400 However this is already handled at the top. */
1401 node->type.tv = tarval_reachable;
1404 compute_Proj_Cond(node, pred);
1407 default_compute(node);
1409 } /* compute_Proj */
1412 * (Re-)compute the type for a Confirm-Nodes.
1414 * @param node the node
1416 static void compute_Confirm(node_t *node) {
1417 ir_node *confirm = node->node;
1418 node_t *pred = get_irn_node(get_Confirm_value(confirm));
1420 if (get_Confirm_cmp(confirm) == pn_Cmp_Eq) {
1421 node_t *bound = get_irn_node(get_Confirm_bound(confirm));
1423 if (is_con(bound->type)) {
1424 /* is equal to a constant */
1425 node->type = bound->type;
1429 /* a Confirm is a copy OR a Const */
1430 node->type = pred->type;
1431 } /* compute_Confirm */
1434 * (Re-)compute the type for a given node.
1436 * @param node the node
1438 static void compute(node_t *node) {
1439 compute_func func = (compute_func)node->node->op->ops.generic;
1446 * Propagate constant evaluation.
1448 * @param env the environment
1450 static void propagate(environment_t *env) {
1453 lattice_elem_t old_type;
1458 while (env->cprop != NULL) {
1459 /* remove the first partition X from cprop */
1462 env->cprop = X->cprop_next;
1464 DB((dbg, LEVEL_2, "Propagate type on part%d\n", X->nr));
1467 while (! list_empty(&X->cprop)) {
1468 /* remove the first Node x from X.cprop */
1469 x = list_entry(X->cprop.next, node_t, cprop_list);
1470 list_del(&x->cprop_list);
1473 /* compute a new type for x */
1475 DB((dbg, LEVEL_3, "computing type of %+F\n", x->node));
1477 if (x->type.tv != old_type.tv) {
1478 verify_type(old_type, x->type);
1479 DB((dbg, LEVEL_2, "node %+F has changed type from %+F to %+F\n", x->node, old_type, x->type));
1481 if (x->on_fallen == 0) {
1482 /* Add x to fallen. Nodes might fall from T -> const -> _|_, so check that they are
1483 not already on the list. */
1488 DB((dbg, LEVEL_2, "Add node %+F to fallen\n", x->node));
1490 for (i = get_irn_n_outs(x->node) - 1; i >= 0; --i) {
1491 ir_node *succ = get_irn_out(x->node, i);
1492 node_t *y = get_irn_node(succ);
1494 /* Add y to y.partition.cprop. */
1495 add_node_to_cprop(y, env);
1500 if (n_fallen > 0 && n_fallen != X->n_nodes) {
1501 DB((dbg, LEVEL_2, "Splitting part%d by fallen\n", X->nr));
1502 Y = split(X, fallen, env);
1506 /* remove the nodes from the fallen list */
1507 for (x = fallen; x != NULL; x = x->next)
1516 * Get the leader for a given node from its congruence class.
1518 * @param irn the node
1520 static ir_node *get_leader(node_t *node) {
1521 partition_t *part = node->part;
1523 if (part->n_nodes > 1) {
1524 DB((dbg, LEVEL_2, "Found congruence class for %+F\n", node->node));
1526 return get_first_node(part)->node;
1532 * Return non-zero if the control flow predecessor node pred
1533 * is the only reachable control flow exit of its block.
1535 * @param pred the control flow exit
1537 static int can_exchange(ir_node *pred) {
1540 else if (is_Jmp(pred))
1542 else if (get_irn_mode(pred) == mode_T) {
1545 /* if the predecessor block has more than one
1546 reachable outputs we cannot remove the block */
1548 for (i = get_irn_n_outs(pred) - 1; i >= 0; --i) {
1549 ir_node *proj = get_irn_out(pred, i);
1552 /* skip non-control flow Proj's */
1553 if (get_irn_mode(proj) != mode_X)
1556 node = get_irn_node(proj);
1557 if (node->type.tv == tarval_reachable) {
1568 * Block Post-Walker, apply the analysis results on control flow by
1569 * shortening Phi's and Block inputs.
1571 static void apply_cf(ir_node *block, void *ctx) {
1572 environment_t *env = ctx;
1573 node_t *node = get_irn_node(block);
1575 ir_node **ins, **in_X;
1576 ir_node *phi, *next;
1578 if (block == get_irg_end_block(current_ir_graph) ||
1579 block == get_irg_start_block(current_ir_graph)) {
1580 /* the EndBlock is always reachable even if the analysis
1581 finds out the opposite :-) */
1584 if (node->type.tv == tarval_unreachable) {
1585 /* mark dead blocks */
1586 set_Block_dead(block);
1590 n = get_Block_n_cfgpreds(block);
1593 /* only one predecessor combine */
1594 ir_node *pred = skip_Proj(get_Block_cfgpred(block, 0));
1596 if (can_exchange(pred)) {
1597 exchange(block, get_nodes_block(pred));
1603 NEW_ARR_A(ir_node *, in_X, n);
1605 for (i = 0; i < n; ++i) {
1606 ir_node *pred = get_Block_cfgpred(block, i);
1607 node_t *node = get_irn_node(pred);
1609 if (node->type.tv == tarval_reachable) {
1616 NEW_ARR_A(ir_node *, ins, n);
1617 for (phi = get_Block_phis(block); phi != NULL; phi = next) {
1618 node_t *node = get_irn_node(phi);
1620 next = get_Phi_next(phi);
1621 if (is_tarval(node->type.tv) && tarval_is_constant(node->type.tv)) {
1622 /* this Phi is replaced by a constant */
1623 tarval *tv = node->type.tv;
1624 ir_node *c = new_r_Const(current_ir_graph, block, get_tarval_mode(tv), tv);
1626 set_irn_node(c, node);
1628 DB((dbg, LEVEL_1, "%+F is replaced by %+F\n", phi, c));
1633 for (i = 0; i < n; ++i) {
1634 node_t *pred = get_irn_node(get_Block_cfgpred(block, i));
1636 if (pred->type.tv == tarval_reachable) {
1637 ins[j++] = get_Phi_pred(phi, i);
1641 /* this Phi is replaced by a single predecessor */
1642 ir_node *s = ins[0];
1645 DB((dbg, LEVEL_1, "%+F is replaced by %+F\n", phi, s));
1649 set_irn_in(phi, j, ins);
1656 /* this Block has only one live predecessor */
1657 ir_node *pred = skip_Proj(in_X[0]);
1659 if (can_exchange(pred)) {
1660 exchange(block, get_nodes_block(pred));
1664 set_irn_in(block, k, in_X);
1670 * Post-Walker, apply the analysis results;
1672 static void apply_result(ir_node *irn, void *ctx) {
1673 environment_t *env = ctx;
1674 node_t *node = get_irn_node(irn);
1676 if (is_Block(irn) || is_End(irn) || is_Bad(irn)) {
1677 /* blocks already handled, do not touch the End node */
1679 node_t *block = get_irn_node(get_nodes_block(irn));
1681 if (block->type.tv == tarval_unreachable) {
1682 ir_node *bad = get_irg_bad(current_ir_graph);
1684 /* here, bad might already have a node, but this can be safely ignored
1685 as long as bad has at least ONE valid node */
1686 set_irn_node(bad, node);
1688 DB((dbg, LEVEL_1, "%+F is unreachable\n", irn));
1692 else if (node->type.tv == tarval_unreachable) {
1693 ir_node *bad = get_irg_bad(current_ir_graph);
1695 /* see comment above */
1696 set_irn_node(bad, node);
1698 DB((dbg, LEVEL_1, "%+F is unreachable\n", irn));
1702 else if (get_irn_mode(irn) == mode_X) {
1705 ir_node *cond = get_Proj_pred(irn);
1707 if (is_Cond(cond)) {
1708 node_t *sel = get_irn_node(get_Cond_selector(cond));
1710 if (is_tarval(sel->type.tv) && tarval_is_constant(sel->type.tv)) {
1711 /* Cond selector is a constant, make a Jmp */
1712 ir_node *jmp = new_r_Jmp(current_ir_graph, block->node);
1713 set_irn_node(jmp, node);
1715 DB((dbg, LEVEL_1, "%+F is replaced by %+F\n", irn, jmp));
1722 /* normal data node */
1723 if (is_tarval(node->type.tv) && tarval_is_constant(node->type.tv)) {
1724 tarval *tv = node->type.tv;
1726 if (! is_Const(irn)) {
1727 /* can be replaced by a constant */
1728 ir_node *c = new_r_Const(current_ir_graph, block->node, get_tarval_mode(tv), tv);
1729 set_irn_node(c, node);
1731 DB((dbg, LEVEL_1, "%+F is replaced by %+F\n", irn, c));
1735 } else if (is_entity(node->type.sym.entity_p)) {
1736 if (! is_SymConst(irn)) {
1737 /* can be replaced by a Symconst */
1738 ir_node *symc = new_r_SymConst(current_ir_graph, block->node, get_irn_mode(irn), node->type.sym, symconst_addr_ent);
1739 set_irn_node(symc, node);
1742 DB((dbg, LEVEL_1, "%+F is replaced by %+F\n", irn, symc));
1743 exchange(irn, symc);
1747 ir_node *leader = get_leader(node);
1749 if (leader != irn) {
1750 DB((dbg, LEVEL_1, "%+F from part%d is replaced by %+F\n", irn, node->part->nr, leader));
1751 exchange(irn, leader);
1757 } /* apply_result */
1759 #define SET(code) op_##code->ops.generic = (op_func)compute_##code
1762 * sets the generic functions to compute.
1764 static void set_compute_functions(void) {
1767 /* set the default compute function */
1768 for (i = get_irp_n_opcodes() - 1; i >= 0; --i) {
1769 ir_op *op = get_irp_opcode(i);
1770 op->ops.generic = (op_func)default_compute;
1773 /* set specific functions */
1786 } /* set_compute_functions */
1788 static int dump_partition_hook(FILE *F, ir_node *n, ir_node *local) {
1789 ir_node *irn = local != NULL ? local : n;
1790 node_t *node = get_irn_node(irn);
1792 ir_fprintf(F, "info2 : \"partition %u type %+F\"\n", node->part->nr, node->type);
1796 void combo(ir_graph *irg) {
1800 ir_graph *rem = current_ir_graph;
1802 current_ir_graph = irg;
1804 /* register a debug mask */
1805 FIRM_DBG_REGISTER(dbg, "firm.opt.combo");
1806 //firm_dbg_set_mask(dbg, SET_LEVEL_3);
1808 DB((dbg, LEVEL_1, "Doing COMBO for %+F\n", irg));
1810 obstack_init(&env.obst);
1811 env.worklist = NULL;
1815 #ifdef DEBUG_libfirm
1816 env.dbg_list = NULL;
1818 env.opcode2id_map = new_set(cmp_opcode, iro_Last * 4);
1819 env.type2id_map = pmap_create();
1820 env.end_idx = get_opt_global_cse() ? 0 : -1;
1821 env.lambda_input = 0;
1824 assure_irg_outs(irg);
1826 /* we have our own value_of function */
1827 set_value_of_func(get_node_tarval);
1829 set_compute_functions();
1830 DEBUG_ONLY(part_nr = 0);
1832 /* create the initial partition and place it on the work list */
1833 env.initial = new_partition(&env);
1834 add_to_worklist(env.initial, &env);
1835 irg_walk_graph(irg, init_block_phis, create_initial_partitions, &env);
1837 /* Place the START Node's partition on cprop.
1838 Place the START Node on its local worklist. */
1839 initial_X = get_irg_initial_exec(irg);
1840 start = get_irn_node(initial_X);
1841 add_node_to_cprop(start, &env);
1845 if (env.worklist != NULL)
1847 } while (env.cprop != NULL || env.worklist != NULL);
1849 dump_all_partitions(&env);
1852 set_dump_node_vcgattr_hook(dump_partition_hook);
1853 dump_ir_block_graph(irg, "-partition");
1854 set_dump_node_vcgattr_hook(NULL);
1856 (void)dump_partition_hook;
1859 /* apply the result */
1860 irg_block_walk_graph(irg, NULL, apply_cf, &env);
1861 irg_walk_graph(irg, NULL, apply_result, &env);
1864 /* control flow might changed */
1865 set_irg_outs_inconsistent(irg);
1866 set_irg_extblk_inconsistent(irg);
1867 set_irg_doms_inconsistent(irg);
1868 set_irg_loopinfo_inconsistent(irg);
1871 pmap_destroy(env.type2id_map);
1872 del_set(env.opcode2id_map);
1873 obstack_free(&env.obst, NULL);
1875 /* restore value_of() default behavior */
1876 set_value_of_func(NULL);
1877 current_ir_graph = rem;