3 * File name: ir/opt/opt_osr.c
4 * Purpose: Operator Strength Reduction, based on
5 * Keith D. Cooper, L. Taylor Simpson, Christopher A. Vick
10 * Copyright: (c) 2006 Universität Karlsruhe
11 * Licence: This file protected by GPL - GNU GENERAL PUBLIC LICENSE.
44 /** The debug handle. */
45 DEBUG_ONLY(static firm_dbg_module_t *dbg;)
49 ir_node *head; /**< the head of the list */
53 typedef struct node_entry {
54 unsigned DFSnum; /**< the DFS number of this node */
55 unsigned low; /**< the low number of this node */
56 ir_node *header; /**< the header of this node */
57 int in_stack; /**< flag, set if the node is on the stack */
58 ir_node *next; /**< link to the next node the the same scc */
59 scc *pscc; /**< the scc of this node */
60 unsigned POnum; /**< the post order number for blocks */
63 /** The environment. */
64 typedef struct iv_env {
65 struct obstack obst; /**< an obstack for allocations */
66 ir_node **stack; /**< the node stack */
67 int tos; /**< tos index */
68 unsigned nextDFSnum; /**< the current DFS number */
69 unsigned POnum; /**< current post order number */
70 set *quad_map; /**< a map from (op, iv, rc) to node */
71 set *lftr_edges; /**< the set of lftr edges */
72 unsigned replaced; /**< number of replaced ops */
73 unsigned lftr_replaced; /**< number of applied linear function test replacements */
74 unsigned flags; /**< additional flags */
75 /** Function called to process a SCC. */
76 void (*process_scc)(scc *pscc, struct iv_env *env);
80 * An entry in the (op, node, node) -> node map.
82 typedef struct quadruple_t {
83 ir_opcode code; /**< the opcode of the reduced operation */
84 ir_node *op1; /**< the first operand the reduced operation */
85 ir_node *op2; /**< the second operand of the reduced operation */
87 ir_node *res; /**< the reduced operation */
93 typedef struct LFTR_edge {
94 ir_node *src; /**< the source node */
95 ir_node *dst; /**< the destination node */
96 ir_opcode code; /**< the opcode that must be applied */
97 ir_node *rc; /**< the region const that must be applied */
101 static ir_node *reduce(ir_node *orig, ir_node *iv, ir_node *rc, iv_env *env);
104 * Compare two LFTR edges.
106 static int LFTR_cmp(const void *e1, const void *e2, size_t size) {
107 const LFTR_edge *l1 = e1;
108 const LFTR_edge *l2 = e2;
110 return l1->src != l2->src;
117 static LFTR_edge *LFTR_find(ir_node *src, iv_env *env) {
122 return set_find(env->lftr_edges, &key, sizeof(key), HASH_PTR(src));
129 static void LFTR_add(ir_node *src, ir_node *dst, ir_opcode code, ir_node *rc, iv_env *env) {
138 * There might be more than one edge here. This is rather bad
139 * because we currently store only one.
141 // assert(LFTR_find(src, env) == NULL);
142 set_insert(env->lftr_edges, &key, sizeof(key), HASH_PTR(src));
146 * Gets the node_entry of a node
148 static node_entry *get_irn_ne(ir_node *irn, iv_env *env) {
149 node_entry *e = get_irn_link(irn);
152 e = obstack_alloc(&env->obst, sizeof(*e));
153 memset(e, 0, sizeof(*e));
154 set_irn_link(irn, e);
160 * Check if irn is an IV.
162 * @param irn the node to check
163 * @param env the environment
165 * @returns the header if it is one, NULL else
167 static ir_node *is_iv(ir_node *irn, iv_env *env) {
168 return get_irn_ne(irn, env)->header;
172 * Check if irn is a region constant.
173 * The block or irn must strictly dominate the header block.
175 * @param irn the node to check
176 * @param header_block the header block of the induction variable
178 static int is_rc(ir_node *irn, ir_node *header_block) {
179 ir_node *block = get_nodes_block(irn);
181 return (block != header_block) && block_dominates(block, header_block);
185 * Set compare function for the quad set.
187 static int quad_cmp(const void *e1, const void *e2, size_t size) {
188 const quadruple_t *c1 = e1;
189 const quadruple_t *c2 = e2;
191 return c1->code != c2->code || c1->op1 != c2->op1 || c1->op2 != c2->op2;
195 * Check if an reduced operation was already calculated.
197 * @param code the opcode of the operation
198 * @param op1 the first operand of the operation
199 * @param op2 the second operand of the operation
200 * @param env the environment
202 * @return the already reduced node or NULL if this operation is not yet reduced
204 static ir_node *search(ir_opcode code, ir_node *op1, ir_node *op2, iv_env *env) {
205 quadruple_t key, *entry;
211 entry = set_find(env->quad_map, &key, sizeof(key),
212 (code * 9) ^ HASH_PTR(op1) ^HASH_PTR(op2));
219 * Add an reduced operation.
221 * @param code the opcode of the operation
222 * @param op1 the first operand of the operation
223 * @param op2 the second operand of the operation
224 * @param result the result of the reduced operation
225 * @param env the environment
227 static void add(ir_opcode code, ir_node *op1, ir_node *op2, ir_node *result, iv_env *env) {
235 set_insert(env->quad_map, &key, sizeof(key),
236 (code * 9) ^ HASH_PTR(op1) ^HASH_PTR(op2));
240 * Find a location where to place a bin-op whose operands are in
243 * @param block1 the block of the first operand
244 * @param block2 the block of the second operand
246 * Note that we know here that such a place must exists. Moreover, this means
247 * that either block1 dominates block2 or vice versa. So, just return
250 static ir_node *find_location(ir_node *block1, ir_node *block2) {
251 if (block_dominates(block1, block2))
253 assert(block_dominates(block2, block1));
258 * Create a node that executes an op1 code op1 operation.
260 * @param code the opcode to execute
261 * @param db debug info to add to the new node
262 * @param op1 the first operand
263 * @param op2 the second operand
264 * @param mode the mode of the new operation
266 * @return the newly created node
268 static ir_node *do_apply(ir_opcode code, dbg_info *db, ir_node *op1, ir_node *op2, ir_mode *mode) {
269 ir_graph *irg = current_ir_graph;
271 ir_node *block = find_location(get_nodes_block(op1), get_nodes_block(op2));
275 result = new_rd_Mul(db, irg, block, op1, op2, mode);
278 result = new_rd_Add(db, irg, block, op1, op2, mode);
281 result = new_rd_Sub(db, irg, block, op1, op2, mode);
291 * The Apply operation.
293 * @param orig the node that represent the original operation and determines
294 * the opcode, debug-info and mode of a newly created one
295 * @param op1 the first operand
296 * @param op2 the second operand
297 * @param env the environment
299 * @return the newly created node
301 static ir_node *apply(ir_node *orig, ir_node *op1, ir_node *op2, iv_env *env) {
302 ir_opcode code = get_irn_opcode(orig);
303 ir_node *result = search(code, op1, op2, env);
306 dbg_info *db = get_irn_dbg_info(orig);
307 ir_node *op1_header = get_irn_ne(op1, env)->header;
308 ir_node *op2_header = get_irn_ne(op2, env)->header;
310 if (op1_header != NULL && is_rc(op2, op1_header)) {
311 result = reduce(orig, op1, op2, env);
313 else if (op2_header != NULL && is_rc(op1, op2_header)) {
314 result = reduce(orig, op2, op1, env);
317 result = do_apply(code, db, op1, op2, get_irn_mode(orig));
318 get_irn_ne(result, env)->header = NULL; }
324 * The Reduce operation.
326 * @param orig the node that represent the original operation and determines
327 * the opcode, debug-info and mode of a newly created one
328 * @param iv the induction variable
329 * @param rc the region constant
330 * @param env the environment
332 * @return the reduced node
334 static ir_node *reduce(ir_node *orig, ir_node *iv, ir_node *rc, iv_env *env) {
335 ir_opcode code = get_irn_opcode(orig);
336 ir_node *result = search(code, iv, rc, env);
339 node_entry *e, *iv_e;
341 ir_mode *mode = get_irn_mode(orig);
343 result = exact_copy(iv);
345 /* Beware: we must always create a new nduction variable with the same mode
346 as the node we are replacing. Espicially this means the mode might be changed
347 from P to I and back. This is always possible, because we have only Phi, Add
349 set_irn_mode(result, mode);
350 add(code, iv, rc, result, env);
351 DB((dbg, LEVEL_3, " Created new %+F for %+F (%s %+F)\n", result, iv,
352 get_irn_opname(orig), rc));
354 iv_e = get_irn_ne(iv, env);
355 e = get_irn_ne(result, env);
356 e->header = iv_e->header;
358 /* create the LFTR edge */
359 LFTR_add(iv, result, code, rc, env);
361 n = get_irn_arity(result);
362 for (i = 0; i < n; ++i) {
363 ir_node *o = get_irn_n(result, i);
365 e = get_irn_ne(o, env);
366 if (e->header == iv_e->header)
367 o = reduce(orig, o, rc, env);
368 else if (is_Phi(result))
369 o = apply(orig, o, rc, env);
372 o = apply(orig, o, rc, env);
374 set_irn_n(result, i, o);
378 DB((dbg, LEVEL_3, " Already Created %+F for %+F (%s %+F)\n", result, iv,
379 get_irn_opname(orig), rc));
385 * The Replace operation.
387 * @param irn the node that will be replaced
388 * @param iv the induction variable
389 * @param rc the region constant
390 * @param env the environment
392 static int replace(ir_node *irn, ir_node *iv, ir_node *rc, iv_env *env) {
394 ir_loop *iv_loop = get_irn_loop(get_nodes_block(iv));
395 ir_loop *irn_loop = get_irn_loop(get_nodes_block(irn));
397 /* only replace nodes that are in the same (or deeper loops) */
398 if (get_loop_depth(irn_loop) >= get_loop_depth(iv_loop)) {
399 DB((dbg, LEVEL_2, " Replacing %+F\n", irn));
401 result = reduce(irn, iv, rc, env);
403 node_entry *e, *iv_e;
405 hook_strength_red(current_ir_graph, irn);
406 exchange(irn, result);
407 e = get_irn_ne(result, env);
408 iv_e = get_irn_ne(iv, env);
409 e->header = iv_e->header;
417 * Check if a node can be replaced (+, -, *).
419 * @param irn the node to check
420 * @param env the environment
422 * @return non-zero if irn should be Replace'd
424 static int check_replace(ir_node *irn, iv_env *env) {
425 ir_node *left, *right, *iv, *rc;
426 ir_op *op = get_irn_op(irn);
427 ir_opcode code = get_op_code(op);
436 left = get_binop_left(irn);
437 right = get_binop_right(irn);
439 liv = is_iv(left, env);
440 riv = is_iv(right, env);
441 if (liv && is_rc(right, liv)) {
442 iv = left; rc = right;
444 else if (riv && is_op_commutative(op) &&
446 iv = right; rc = left;
450 if (code == iro_Mul && env->flags & osr_flag_ignore_x86_shift) {
452 tarval *tv = get_Const_tarval(rc);
454 if (tarval_is_long(tv)) {
455 long value = get_tarval_long(tv);
457 if (value == 2 || value == 4 || value == 8) {
458 /* do not reduce multiplications by 2, 4, 8 */
465 return replace(irn, iv, rc, env);
475 * Check which SCC's are induction variables.
478 * @param env the environment
480 static void classify_iv(scc *pscc, iv_env *env) {
481 ir_node *irn, *next, *header = NULL;
482 node_entry *b, *h = NULL;
483 int j, only_phi, num_outside;
486 /* find the header block for this scc */
487 for (irn = pscc->head; irn; irn = next) {
488 node_entry *e = get_irn_link(irn);
489 ir_node *block = get_nodes_block(irn);
492 b = get_irn_ne(block, env);
495 if (h->POnum < b->POnum) {
506 /* check if this scc contains only Phi, Add or Sub nodes */
510 for (irn = pscc->head; irn; irn = next) {
511 node_entry *e = get_irn_ne(irn, env);
514 switch (get_irn_opcode(irn)) {
520 for (j = get_irn_arity(irn) - 1; j >= 0; --j) {
521 ir_node *pred = get_irn_n(irn, j);
522 node_entry *pe = get_irn_ne(pred, env);
524 if (pe->pscc != e->pscc) {
525 /* not in the same SCC, must be a region const */
526 if (! is_rc(pred, header)) {
527 /* not an induction variable */
533 } else if (out_rc != pred) {
540 /* not an induction variable */
544 /* found an induction variable */
545 DB((dbg, LEVEL_2, " Found an induction variable:\n "));
546 if (only_phi && num_outside == 1) {
547 /* a phi cycle with only one real predecessor can be collapsed */
548 DB((dbg, LEVEL_2, " Found an USELESS Phi cycle:\n "));
550 for (irn = pscc->head; irn; irn = next) {
551 node_entry *e = get_irn_ne(irn, env);
554 exchange(irn, out_rc);
560 /* set the header for every node in this scc */
561 for (irn = pscc->head; irn; irn = next) {
562 node_entry *e = get_irn_ne(irn, env);
565 DB((dbg, LEVEL_2, " %+F,", irn));
567 DB((dbg, LEVEL_2, "\n"));
571 for (irn = pscc->head; irn; irn = next) {
572 node_entry *e = get_irn_ne(irn, env);
575 if (! check_replace(irn, env))
581 * Process a SCC for the operator strength reduction.
583 * @param pscc the SCC
584 * @param env the environment
586 static void process_scc(scc *pscc, iv_env *env) {
587 ir_node *head = pscc->head;
588 node_entry *e = get_irn_link(head);
594 DB((dbg, LEVEL_4, " SCC at %p:\n ", pscc));
595 for (irn = pscc->head; irn; irn = next) {
596 node_entry *e = get_irn_link(irn);
600 DB((dbg, LEVEL_4, " %+F,", irn));
602 DB((dbg, LEVEL_4, "\n"));
606 if (e->next == NULL) {
607 /* this SCC has only a single member */
608 check_replace(head, env);
610 classify_iv(pscc, env);
615 * If an SCC is a Phi only cycle, remove it.
617 static void remove_phi_cycle(scc *pscc, iv_env *env) {
622 /* check if this scc contains only Phi, Add or Sub nodes */
624 for (irn = pscc->head; irn; irn = next) {
625 node_entry *e = get_irn_ne(irn, env);
631 for (j = get_irn_arity(irn) - 1; j >= 0; --j) {
632 ir_node *pred = get_irn_n(irn, j);
633 node_entry *pe = get_irn_ne(pred, env);
635 if (pe->pscc != e->pscc) {
636 /* not in the same SCC, must be the only input */
639 } else if (out_rc != pred) {
645 /* found a Phi cycle */
646 DB((dbg, LEVEL_2, " Found an USELESS Phi cycle:\n "));
648 for (irn = pscc->head; irn; irn = next) {
649 node_entry *e = get_irn_ne(irn, env);
652 exchange(irn, out_rc);
658 * Process a SCC for the Phi cycle removement.
660 * @param pscc the SCC
661 * @param env the environment
663 static void process_phi_only_scc(scc *pscc, iv_env *env) {
664 ir_node *head = pscc->head;
665 node_entry *e = get_irn_link(head);
671 DB((dbg, LEVEL_4, " SCC at %p:\n ", pscc));
672 for (irn = pscc->head; irn; irn = next) {
673 node_entry *e = get_irn_link(irn);
677 DB((dbg, LEVEL_4, " %+F,", irn));
679 DB((dbg, LEVEL_4, "\n"));
684 remove_phi_cycle(pscc, env);
689 * Push a node onto the stack.
691 * @param env the environment
692 * @param n the node to push
694 static void push(iv_env *env, ir_node *n) {
697 if (env->tos == ARR_LEN(env->stack)) {
698 int nlen = ARR_LEN(env->stack) * 2;
699 ARR_RESIZE(ir_node *, env->stack, nlen);
701 env->stack[env->tos++] = n;
702 e = get_irn_ne(n, env);
707 * pop a node from the stack
709 * @param env the environment
711 * @return The topmost node
713 static ir_node *pop(iv_env *env)
715 ir_node *n = env->stack[--env->tos];
716 node_entry *e = get_irn_ne(n, env);
723 * Do Tarjan's SCC algorithm and drive OSR.
725 * @param irn start at this node
726 * @param env the environment
728 static void dfs(ir_node *irn, iv_env *env)
731 node_entry *node = get_irn_ne(irn, env);
733 mark_irn_visited(irn);
735 /* do not put blocks into the scc */
737 n = get_irn_arity(irn);
738 for (i = 0; i < n; ++i) {
739 ir_node *pred = get_irn_n(irn, i);
741 if (irn_not_visited(pred))
746 ir_node *block = get_nodes_block(irn);
748 node->DFSnum = env->nextDFSnum++;
749 node->low = node->DFSnum;
752 /* handle the block */
753 if (irn_not_visited(block))
756 n = get_irn_arity(irn);
757 for (i = 0; i < n; ++i) {
758 ir_node *pred = get_irn_n(irn, i);
759 node_entry *o = get_irn_ne(pred, env);
761 if (irn_not_visited(pred)) {
763 node->low = MIN(node->low, o->low);
765 if (o->DFSnum < node->DFSnum && o->in_stack)
766 node->low = MIN(o->DFSnum, node->low);
768 if (node->low == node->DFSnum) {
769 scc *pscc = obstack_alloc(&env->obst, sizeof(*pscc));
777 e = get_irn_ne(x, env);
779 e->next = pscc->head;
783 env->process_scc(pscc, env);
789 * Do the DFS by starting at the End node of a graph.
791 * @param irg the graph to process
792 * @param env the environment
794 static void do_dfs(ir_graph *irg, iv_env *env) {
795 ir_graph *rem = current_ir_graph;
796 ir_node *end = get_irg_end(irg);
799 current_ir_graph = irg;
800 inc_irg_visited(irg);
802 /* visit all visible nodes */
805 /* visit the keep-alives */
806 n = get_End_n_keepalives(end);
807 for (i = 0; i < n; ++i) {
808 ir_node *ka = get_End_keepalive(end, i);
810 if (irn_not_visited(ka))
814 current_ir_graph = rem;
818 * Post-block-walker: assign the post-order number.
820 static void assign_po(ir_node *block, void *ctx) {
822 node_entry *e = get_irn_ne(block, env);
824 e->POnum = env->POnum++;
829 * Follows the LFTR edges and return the last node in the chain.
831 * @param irn the node that should be followed
832 * @param env the IV environment
835 * In the current implementation only the last edge is stored, so
836 * only one chain exists. That's why we might miss some opportunities.
838 static ir_node *followEdges(ir_node *irn, iv_env *env) {
840 LFTR_edge *e = LFTR_find(irn, env);
849 * Apply one LFTR edge operation.
850 * Return NULL if the transformation cannot be done safely without
853 * @param rc the IV node that should be translated
854 * @param e the LFTR edge
855 * @param env the IV environment
857 * @return the translated region constant or NULL
858 * if the translation was not possible
861 * In the current implementation only the last edge is stored, so
862 * only one chain exists. That's why we might miss some opportunities.
864 static ir_node *applyOneEdge(ir_node *rc, LFTR_edge *e, iv_env *env) {
865 if (env->flags & osr_flag_lftr_with_ov_check) {
866 tarval *tv_l, *tv_r, *tv;
867 tarval_int_overflow_mode_t ovmode;
869 /* overflow can only be decided for Consts */
870 if (! is_Const(e->rc)) {
871 DB((dbg, LEVEL_4, " = UNKNOWN (%+F)", e->rc));
875 tv_l = get_Const_tarval(rc);
876 tv_r = get_Const_tarval(e->rc);
878 ovmode = tarval_get_integer_overflow_mode();
879 tarval_set_integer_overflow_mode(TV_OVERFLOW_BAD);
883 tv = tarval_mul(tv_l, tv_r);
884 DB((dbg, LEVEL_4, " * %+F", tv_r));
887 tv = tarval_add(tv_l, tv_r);
888 DB((dbg, LEVEL_4, " + %+F", tv_r));
891 tv = tarval_sub(tv_l, tv_r);
892 DB((dbg, LEVEL_4, " - %+F", tv_r));
898 tarval_set_integer_overflow_mode(ovmode);
900 if (tv == tarval_bad) {
901 DB((dbg, LEVEL_4, " = OVERFLOW"));
904 return new_r_Const(current_ir_graph, get_irn_n(rc, -1), get_tarval_mode(tv), tv);
906 return do_apply(e->code, NULL, rc, e->rc, get_irn_mode(rc));
910 * Applies the operations represented by the LFTR edges to a
911 * region constant and returns the value.
912 * Return NULL if the transformation cannot be done safely without
915 * @param iv the IV node that starts the LFTR edge chain
916 * @param rc the region constant that should be translated
917 * @param env the IV environment
919 * @return the translated region constant or NULL
920 * if the translation was not possible
922 static ir_node *applyEdges(ir_node *iv, ir_node *rc, iv_env *env) {
925 if (env->flags & osr_flag_lftr_with_ov_check) {
926 /* overflow can only be decided for Consts */
927 if (! is_Const(rc)) {
928 DB((dbg, LEVEL_4, " = UNKNOWN (%+F)\n", rc));
931 DB((dbg, LEVEL_4, "%+F", get_Const_tarval(rc)));
934 for (irn = iv; rc;) {
935 LFTR_edge *e = LFTR_find(irn, env);
937 rc = applyOneEdge(rc, e, env);
943 DB((dbg, LEVEL_3, "\n"));
948 * Walker, finds Cmp(iv, rc) or Cmp(rc, iv)
949 * and tries to optimize them.
951 static void do_lftr(ir_node *cmp, void *ctx) {
953 ir_node *left, *right, *liv, *riv;
955 ir_node *nleft = NULL, *nright = NULL;
957 if (get_irn_op(cmp) != op_Cmp)
960 left = get_Cmp_left(cmp);
961 right = get_Cmp_right(cmp);
963 liv = is_iv(left, env);
964 riv = is_iv(right, env);
965 if (liv && is_rc(right, liv)) {
966 iv = left; rc = right;
968 nright = applyEdges(iv, rc, env);
969 if (nright && nright != rc) {
970 nleft = followEdges(iv, env);
973 else if (riv && is_rc(left, riv)) {
974 iv = right; rc = left;
976 nleft = applyEdges(iv, rc, env);
977 if (nleft && nleft != rc) {
978 nright = followEdges(iv, env);
982 if (nleft && nright) {
983 DB((dbg, LEVEL_2, " LFTR for %+F\n", cmp));
984 set_Cmp_left(cmp, nleft);
985 set_Cmp_right(cmp, nright);
986 ++env->lftr_replaced;
991 * do linear function test replacement.
993 * @param irg the graph that should be optimized
994 * @param env the IV environment
996 static void lftr(ir_graph *irg, iv_env *env) {
997 irg_walk_graph(irg, NULL, do_lftr, env);
1002 * Pre-walker: set all node links to NULL and fix the
1003 * block of Proj nodes.
1005 static void clear_and_fix(ir_node *irn, void *env)
1007 set_irn_link(irn, NULL);
1010 ir_node *pred = get_Proj_pred(irn);
1011 set_irn_n(irn, -1, get_irn_n(pred, -1));
1015 /* Performs Operator Strength Reduction for the passed graph. */
1016 void opt_osr(ir_graph *irg, unsigned flags) {
1020 if (! get_opt_strength_red()) {
1021 /* only kill Phi cycles */
1022 remove_phi_cycles(irg);
1026 rem = current_ir_graph;
1027 current_ir_graph = irg;
1029 FIRM_DBG_REGISTER(dbg, "firm.opt.osr");
1031 DB((dbg, LEVEL_1, "Doing Operator Strength Reduction for %+F\n", irg));
1033 obstack_init(&env.obst);
1034 env.stack = NEW_ARR_F(ir_node *, 128);
1038 env.quad_map = new_set(quad_cmp, 64);
1039 env.lftr_edges = new_set(LFTR_cmp, 64);
1041 env.lftr_replaced = 0;
1043 env.process_scc = process_scc;
1045 /* Clear all links and move Proj nodes into the
1046 the same block as it's predecessors.
1047 This can improve the placement of new nodes.
1049 irg_walk_graph(irg, NULL, clear_and_fix, NULL);
1051 /* we need dominance */
1053 assure_irg_outs(irg);
1055 /* calculate the post order number for blocks. */
1056 irg_out_block_walk(get_irg_start_block(irg), NULL, assign_po, &env);
1058 /* calculate the SCC's and drive OSR. */
1062 /* try linear function test replacements */
1065 set_irg_outs_inconsistent(irg);
1066 DB((dbg, LEVEL_1, "Replacements: %u + %u (lftr)\n\n", env.replaced, env.lftr_replaced));
1069 del_set(env.lftr_edges);
1070 del_set(env.quad_map);
1071 DEL_ARR_F(env.stack);
1072 obstack_free(&env.obst, NULL);
1074 current_ir_graph = rem;
1077 /* Remove any Phi cycles with only one real input. */
1078 void remove_phi_cycles(ir_graph *irg) {
1082 rem = current_ir_graph;
1083 current_ir_graph = irg;
1085 FIRM_DBG_REGISTER(dbg, "firm.opt.remove_phi");
1087 DB((dbg, LEVEL_1, "Doing Phi cycle removement for %+F\n", irg));
1089 obstack_init(&env.obst);
1090 env.stack = NEW_ARR_F(ir_node *, 128);
1094 env.quad_map = NULL;
1095 env.lftr_edges = NULL;
1097 env.lftr_replaced = 0;
1099 env.process_scc = process_phi_only_scc;
1101 /* Clear all links and move Proj nodes into the
1102 the same block as it's predecessors.
1103 This can improve the placement of new nodes.
1105 irg_walk_graph(irg, NULL, clear_and_fix, NULL);
1107 /* we need dominance */
1108 assure_irg_outs(irg);
1110 /* calculate the post order number for blocks. */
1111 irg_out_block_walk(get_irg_start_block(irg), NULL, assign_po, &env);
1113 /* calculate the SCC's and drive OSR. */
1117 set_irg_outs_inconsistent(irg);
1118 DB((dbg, LEVEL_1, "remove_phi_cycles: %u Cycles removed\n\n", env.replaced));
1121 DEL_ARR_F(env.stack);
1122 obstack_free(&env.obst, NULL);
1124 current_ir_graph = rem;