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.
38 /** The debug handle. */
39 DEBUG_ONLY(static firm_dbg_module_t *dbg;)
43 ir_node *head; /**< the head of the list */
47 typedef struct node_entry {
48 unsigned DFSnum; /**< the DFS number of this node */
49 unsigned low; /**< the low number of this node */
50 ir_node *header; /**< the header of this node */
51 int in_stack; /**< flag, set if the node is on the stack */
52 ir_node *next; /**< link to the next node the the same scc */
53 scc *pscc; /**< the scc of this node */
54 unsigned POnum; /**< the post order number for blocks */
57 /** The environment. */
58 typedef struct iv_env {
59 struct obstack obst; /**< an obstack for allocations */
60 ir_node **stack; /**< the node stack */
61 int tos; /**< tos index */
62 unsigned nextDFSnum; /**< the current DFS number */
63 unsigned POnum; /**< current post order number */
64 set *quad_map; /**< a map from (op, iv, rc) to node */
65 set *lftr_edges; /**< the set of lftr edges */
66 unsigned replaced; /**< number of replaced ops */
67 unsigned lftr_replaced; /**< number of applied linear function test replacements */
68 unsigned flags; /**< additional flags */
69 /** Function called to process a SCC. */
70 void (*process_scc)(scc *pscc, struct iv_env *env);
74 * An entry in the (op, node, node) -> node map.
76 typedef struct quadruple_t {
77 ir_opcode code; /**< the opcode of the reduced operation */
78 ir_node *op1; /**< the first operand the reduced operation */
79 ir_node *op2; /**< the second operand of the reduced operation */
81 ir_node *res; /**< the reduced operation */
87 typedef struct LFTR_edge {
88 ir_node *src; /**< the source node */
89 ir_node *dst; /**< the destination node */
90 ir_opcode code; /**< the opcode that must be applied */
91 ir_node *rc; /**< the region const that must be applied */
95 static ir_node *reduce(ir_node *orig, ir_node *iv, ir_node *rc, iv_env *env);
98 * Compare two LFTR edges.
100 static int LFTR_cmp(const void *e1, const void *e2, size_t size) {
101 const LFTR_edge *l1 = e1;
102 const LFTR_edge *l2 = e2;
104 return l1->src != l2->src;
111 static LFTR_edge *LFTR_find(ir_node *src, iv_env *env) {
116 return set_find(env->lftr_edges, &key, sizeof(key), HASH_PTR(src));
123 static void LFTR_add(ir_node *src, ir_node *dst, ir_opcode code, ir_node *rc, iv_env *env) {
132 * There might be more than one edge here. This is rather bad
133 * because we currently store only one.
135 // assert(LFTR_find(src, env) == NULL);
136 set_insert(env->lftr_edges, &key, sizeof(key), HASH_PTR(src));
140 * Gets the node_entry of a node
142 static node_entry *get_irn_ne(ir_node *irn, iv_env *env) {
143 node_entry *e = get_irn_link(irn);
146 e = obstack_alloc(&env->obst, sizeof(*e));
147 memset(e, 0, sizeof(*e));
148 set_irn_link(irn, e);
154 * Check if irn is an IV.
156 * @param irn the node to check
157 * @param env the environment
159 * @returns the header if it is one, NULL else
161 static ir_node *is_iv(ir_node *irn, iv_env *env) {
162 return get_irn_ne(irn, env)->header;
166 * Check if irn is a region constant.
167 * The block or irn must strictly dominate the header block.
169 * @param irn the node to check
170 * @param header_block the header block of the induction variable
172 static int is_rc(ir_node *irn, ir_node *header_block) {
173 ir_node *block = get_nodes_block(irn);
175 return (block != header_block) && block_dominates(block, header_block);
179 * Set compare function for the quad set.
181 static int quad_cmp(const void *e1, const void *e2, size_t size) {
182 const quadruple_t *c1 = e1;
183 const quadruple_t *c2 = e2;
185 return c1->code != c2->code || c1->op1 != c2->op1 || c1->op2 != c2->op2;
189 * Check if an reduced operation was already calculated.
191 * @param code the opcode of the operation
192 * @param op1 the first operand of the operation
193 * @param op2 the second operand of the operation
194 * @param env the environment
196 * @return the already reduced node or NULL if this operation is not yet reduced
198 static ir_node *search(ir_opcode code, ir_node *op1, ir_node *op2, iv_env *env) {
199 quadruple_t key, *entry;
205 entry = set_find(env->quad_map, &key, sizeof(key),
206 (code * 9) ^ HASH_PTR(op1) ^HASH_PTR(op2));
213 * Add an reduced operation.
215 * @param code the opcode of the operation
216 * @param op1 the first operand of the operation
217 * @param op2 the second operand of the operation
218 * @param result the result of the reduced operation
219 * @param env the environment
221 static void add(ir_opcode code, ir_node *op1, ir_node *op2, ir_node *result, iv_env *env) {
229 set_insert(env->quad_map, &key, sizeof(key),
230 (code * 9) ^ HASH_PTR(op1) ^HASH_PTR(op2));
234 * Find a location where to place a bin-op whose operands are in
237 * @param block1 the block of the first operand
238 * @param block2 the block of the second operand
240 * Note that we know here that such a place must exists. Moreover, this means
241 * that either block1 dominates block2 or vice versa. So, just return
244 static ir_node *find_location(ir_node *block1, ir_node *block2) {
245 if (block_dominates(block1, block2))
247 assert(block_dominates(block2, block1));
252 * Create a node that executes an op1 code op1 operation.
254 * @param code the opcode to execute
255 * @param db debug info to add to the new node
256 * @param op1 the first operand
257 * @param op2 the second operand
258 * @param mode the mode of the new operation
260 * @return the newly created node
262 static ir_node *do_apply(ir_opcode code, dbg_info *db, ir_node *op1, ir_node *op2, ir_mode *mode) {
263 ir_graph *irg = current_ir_graph;
265 ir_node *block = find_location(get_nodes_block(op1), get_nodes_block(op2));
269 result = new_rd_Mul(db, irg, block, op1, op2, mode);
272 result = new_rd_Add(db, irg, block, op1, op2, mode);
275 result = new_rd_Sub(db, irg, block, op1, op2, mode);
285 * The Apply operation.
287 * @param orig the node that represent the original operation and determines
288 * the opcode, debug-info and mode of a newly created one
289 * @param op1 the first operand
290 * @param op2 the second operand
291 * @param env the environment
293 * @return the newly created node
295 static ir_node *apply(ir_node *orig, ir_node *op1, ir_node *op2, iv_env *env) {
296 ir_opcode code = get_irn_opcode(orig);
297 ir_node *result = search(code, op1, op2, env);
300 dbg_info *db = get_irn_dbg_info(orig);
301 ir_node *op1_header = get_irn_ne(op1, env)->header;
302 ir_node *op2_header = get_irn_ne(op2, env)->header;
304 if (op1_header != NULL && is_rc(op2, op1_header)) {
305 result = reduce(orig, op1, op2, env);
307 else if (op2_header != NULL && is_rc(op1, op2_header)) {
308 result = reduce(orig, op2, op1, env);
311 result = do_apply(code, db, op1, op2, get_irn_mode(orig));
312 get_irn_ne(result, env)->header = NULL; }
318 * The Reduce operation.
320 * @param orig the node that represent the original operation and determines
321 * the opcode, debug-info and mode of a newly created one
322 * @param iv the induction variable
323 * @param rc the region constant
324 * @param env the environment
326 * @return the reduced node
328 static ir_node *reduce(ir_node *orig, ir_node *iv, ir_node *rc, iv_env *env) {
329 ir_opcode code = get_irn_opcode(orig);
330 ir_node *result = search(code, iv, rc, env);
333 node_entry *e, *iv_e;
335 ir_mode *mode = get_irn_mode(orig);
337 result = exact_copy(iv);
339 /* Beware: we must always create a new nduction variable with the same mode
340 as the node we are replacing. Espicially this means the mode might be changed
341 from P to I and back. This is always possible, because we have only Phi, Add
343 set_irn_mode(result, mode);
344 add(code, iv, rc, result, env);
345 DB((dbg, LEVEL_3, " Created new %+F for %+F (%s %+F)\n", result, iv,
346 get_irn_opname(orig), rc));
348 iv_e = get_irn_ne(iv, env);
349 e = get_irn_ne(result, env);
350 e->header = iv_e->header;
352 /* create the LFTR edge */
353 LFTR_add(iv, result, code, rc, env);
355 n = get_irn_arity(result);
356 for (i = 0; i < n; ++i) {
357 ir_node *o = get_irn_n(result, i);
359 e = get_irn_ne(o, env);
360 if (e->header == iv_e->header)
361 o = reduce(orig, o, rc, env);
362 else if (is_Phi(result))
363 o = apply(orig, o, rc, env);
366 o = apply(orig, o, rc, env);
368 set_irn_n(result, i, o);
372 DB((dbg, LEVEL_3, " Already Created %+F for %+F (%s %+F)\n", result, iv,
373 get_irn_opname(orig), rc));
379 * The Replace operation.
381 * @param irn the node that will be replaced
382 * @param iv the induction variable
383 * @param rc the region constant
384 * @param env the environment
386 static int replace(ir_node *irn, ir_node *iv, ir_node *rc, iv_env *env) {
388 ir_loop *iv_loop = get_irn_loop(get_nodes_block(iv));
389 ir_loop *irn_loop = get_irn_loop(get_nodes_block(irn));
391 /* only replace nodes that are in the same (or deeper loops) */
392 if (get_loop_depth(irn_loop) >= get_loop_depth(iv_loop)) {
393 DB((dbg, LEVEL_2, " Replacing %+F\n", irn));
395 result = reduce(irn, iv, rc, env);
397 node_entry *e, *iv_e;
399 hook_strength_red(current_ir_graph, irn);
400 exchange(irn, result);
401 e = get_irn_ne(result, env);
402 iv_e = get_irn_ne(iv, env);
403 e->header = iv_e->header;
411 * Check if a node can be replaced (+, -, *).
413 * @param irn the node to check
414 * @param env the environment
416 * @return non-zero if irn should be Replace'd
418 static int check_replace(ir_node *irn, iv_env *env) {
419 ir_node *left, *right, *iv, *rc;
420 ir_op *op = get_irn_op(irn);
421 ir_opcode code = get_op_code(op);
430 left = get_binop_left(irn);
431 right = get_binop_right(irn);
433 liv = is_iv(left, env);
434 riv = is_iv(right, env);
435 if (liv && is_rc(right, liv)) {
436 iv = left; rc = right;
438 else if (riv && is_op_commutative(op) &&
440 iv = right; rc = left;
444 if (code == iro_Mul && env->flags & osr_flag_ignore_x86_shift) {
446 tarval *tv = get_Const_tarval(rc);
448 if (tarval_is_long(tv)) {
449 long value = get_tarval_long(tv);
451 if (value == 2 || value == 4 || value == 8) {
452 /* do not reduce multiplications by 2, 4, 8 */
459 return replace(irn, iv, rc, env);
469 * Check which SCC's are induction variables.
472 * @param env the environment
474 static void classify_iv(scc *pscc, iv_env *env) {
475 ir_node *irn, *next, *header = NULL;
476 node_entry *b, *h = NULL;
477 int j, only_phi, num_outside;
480 /* find the header block for this scc */
481 for (irn = pscc->head; irn; irn = next) {
482 node_entry *e = get_irn_link(irn);
483 ir_node *block = get_nodes_block(irn);
486 b = get_irn_ne(block, env);
489 if (h->POnum < b->POnum) {
500 /* check if this scc contains only Phi, Add or Sub nodes */
504 for (irn = pscc->head; irn; irn = next) {
505 node_entry *e = get_irn_ne(irn, env);
508 switch (get_irn_opcode(irn)) {
514 for (j = get_irn_arity(irn) - 1; j >= 0; --j) {
515 ir_node *pred = get_irn_n(irn, j);
516 node_entry *pe = get_irn_ne(pred, env);
518 if (pe->pscc != e->pscc) {
519 /* not in the same SCC, must be a region const */
520 if (! is_rc(pred, header)) {
521 /* not an induction variable */
527 } else if (out_rc != pred) {
534 /* not an induction variable */
538 /* found an induction variable */
539 DB((dbg, LEVEL_2, " Found an induction variable:\n "));
540 if (only_phi && num_outside == 1) {
541 /* a phi cycle with only one real predecessor can be collapsed */
542 DB((dbg, LEVEL_2, " Found an USELESS Phi cycle:\n "));
544 for (irn = pscc->head; irn; irn = next) {
545 node_entry *e = get_irn_ne(irn, env);
548 exchange(irn, out_rc);
554 /* set the header for every node in this scc */
555 for (irn = pscc->head; irn; irn = next) {
556 node_entry *e = get_irn_ne(irn, env);
559 DB((dbg, LEVEL_2, " %+F,", irn));
561 DB((dbg, LEVEL_2, "\n"));
565 for (irn = pscc->head; irn; irn = next) {
566 node_entry *e = get_irn_ne(irn, env);
569 if (! check_replace(irn, env))
575 * Process a SCC for the operator strength reduction.
577 * @param pscc the SCC
578 * @param env the environment
580 static void process_scc(scc *pscc, iv_env *env) {
581 ir_node *head = pscc->head;
582 node_entry *e = get_irn_link(head);
588 DB((dbg, LEVEL_4, " SCC at %p:\n ", pscc));
589 for (irn = pscc->head; irn; irn = next) {
590 node_entry *e = get_irn_link(irn);
594 DB((dbg, LEVEL_4, " %+F,", irn));
596 DB((dbg, LEVEL_4, "\n"));
600 if (e->next == NULL) {
601 /* this SCC has only a single member */
602 check_replace(head, env);
604 classify_iv(pscc, env);
609 * If an SCC is a Phi only cycle, remove it.
611 static void remove_phi_cycle(scc *pscc, iv_env *env) {
616 /* check if this scc contains only Phi, Add or Sub nodes */
618 for (irn = pscc->head; irn; irn = next) {
619 node_entry *e = get_irn_ne(irn, env);
625 for (j = get_irn_arity(irn) - 1; j >= 0; --j) {
626 ir_node *pred = get_irn_n(irn, j);
627 node_entry *pe = get_irn_ne(pred, env);
629 if (pe->pscc != e->pscc) {
630 /* not in the same SCC, must be the only input */
633 } else if (out_rc != pred) {
639 /* found a Phi cycle */
640 DB((dbg, LEVEL_2, " Found an USELESS Phi cycle:\n "));
642 for (irn = pscc->head; irn; irn = next) {
643 node_entry *e = get_irn_ne(irn, env);
646 exchange(irn, out_rc);
652 * Process a SCC for the Phi cycle removement.
654 * @param pscc the SCC
655 * @param env the environment
657 static void process_phi_only_scc(scc *pscc, iv_env *env) {
658 ir_node *head = pscc->head;
659 node_entry *e = get_irn_link(head);
665 DB((dbg, LEVEL_4, " SCC at %p:\n ", pscc));
666 for (irn = pscc->head; irn; irn = next) {
667 node_entry *e = get_irn_link(irn);
671 DB((dbg, LEVEL_4, " %+F,", irn));
673 DB((dbg, LEVEL_4, "\n"));
678 remove_phi_cycle(pscc, env);
683 * Push a node onto the stack.
685 * @param env the environment
686 * @param n the node to push
688 static void push(iv_env *env, ir_node *n) {
691 if (env->tos == ARR_LEN(env->stack)) {
692 int nlen = ARR_LEN(env->stack) * 2;
693 ARR_RESIZE(ir_node *, env->stack, nlen);
695 env->stack[env->tos++] = n;
696 e = get_irn_ne(n, env);
701 * pop a node from the stack
703 * @param env the environment
705 * @return The topmost node
707 static ir_node *pop(iv_env *env)
709 ir_node *n = env->stack[--env->tos];
710 node_entry *e = get_irn_ne(n, env);
717 * Do Tarjan's SCC algorithm and drive OSR.
719 * @param irn start at this node
720 * @param env the environment
722 static void dfs(ir_node *irn, iv_env *env)
725 node_entry *node = get_irn_ne(irn, env);
727 mark_irn_visited(irn);
729 /* do not put blocks into the scc */
731 n = get_irn_arity(irn);
732 for (i = 0; i < n; ++i) {
733 ir_node *pred = get_irn_n(irn, i);
735 if (irn_not_visited(pred))
740 ir_node *block = get_nodes_block(irn);
742 node->DFSnum = env->nextDFSnum++;
743 node->low = node->DFSnum;
746 /* handle the block */
747 if (irn_not_visited(block))
750 n = get_irn_arity(irn);
751 for (i = 0; i < n; ++i) {
752 ir_node *pred = get_irn_n(irn, i);
753 node_entry *o = get_irn_ne(pred, env);
755 if (irn_not_visited(pred)) {
757 node->low = MIN(node->low, o->low);
759 if (o->DFSnum < node->DFSnum && o->in_stack)
760 node->low = MIN(o->DFSnum, node->low);
762 if (node->low == node->DFSnum) {
763 scc *pscc = obstack_alloc(&env->obst, sizeof(*pscc));
771 e = get_irn_ne(x, env);
773 e->next = pscc->head;
777 env->process_scc(pscc, env);
783 * Do the DFS by starting at the End node of a graph.
785 * @param irg the graph to process
786 * @param env the environment
788 static void do_dfs(ir_graph *irg, iv_env *env) {
789 ir_graph *rem = current_ir_graph;
790 ir_node *end = get_irg_end(irg);
793 current_ir_graph = irg;
794 inc_irg_visited(irg);
796 /* visit all visible nodes */
799 /* visit the keep-alives */
800 n = get_End_n_keepalives(end);
801 for (i = 0; i < n; ++i) {
802 ir_node *ka = get_End_keepalive(end, i);
804 if (irn_not_visited(ka))
808 current_ir_graph = rem;
812 * Post-block-walker: assign the post-order number.
814 static void assign_po(ir_node *block, void *ctx) {
816 node_entry *e = get_irn_ne(block, env);
818 e->POnum = env->POnum++;
823 * Follows the LFTR edges and return the last node in the chain.
825 * @param irn the node that should be followed
826 * @param env the IV environment
829 * In the current implementation only the last edge is stored, so
830 * only one chain exists. That's why we might miss some opportunities.
832 static ir_node *followEdges(ir_node *irn, iv_env *env) {
834 LFTR_edge *e = LFTR_find(irn, env);
843 * Apply one LFTR edge operation.
844 * Return NULL if the transformation cannot be done safely without
847 * @param rc the IV node that should be translated
848 * @param e the LFTR edge
849 * @param env the IV environment
851 * @return the translated region constant or NULL
852 * if the translation was not possible
855 * In the current implementation only the last edge is stored, so
856 * only one chain exists. That's why we might miss some opportunities.
858 static ir_node *applyOneEdge(ir_node *rc, LFTR_edge *e, iv_env *env) {
859 if (env->flags & osr_flag_lftr_with_ov_check) {
860 tarval *tv_l, *tv_r, *tv;
861 tarval_int_overflow_mode_t ovmode;
863 /* overflow can only be decided for Consts */
864 if (! is_Const(e->rc)) {
865 DB((dbg, LEVEL_4, " = UNKNOWN (%+F)", e->rc));
869 tv_l = get_Const_tarval(rc);
870 tv_r = get_Const_tarval(e->rc);
872 ovmode = tarval_get_integer_overflow_mode();
873 tarval_set_integer_overflow_mode(TV_OVERFLOW_BAD);
877 tv = tarval_mul(tv_l, tv_r);
878 DB((dbg, LEVEL_4, " * %+F", tv_r));
881 tv = tarval_add(tv_l, tv_r);
882 DB((dbg, LEVEL_4, " + %+F", tv_r));
885 tv = tarval_sub(tv_l, tv_r);
886 DB((dbg, LEVEL_4, " - %+F", tv_r));
892 tarval_set_integer_overflow_mode(ovmode);
894 if (tv == tarval_bad) {
895 DB((dbg, LEVEL_4, " = OVERFLOW"));
898 return new_r_Const(current_ir_graph, get_irn_n(rc, -1), get_tarval_mode(tv), tv);
900 return do_apply(e->code, NULL, rc, e->rc, get_irn_mode(rc));
904 * Applies the operations represented by the LFTR edges to a
905 * region constant and returns the value.
906 * Return NULL if the transformation cannot be done safely without
909 * @param iv the IV node that starts the LFTR edge chain
910 * @param rc the region constant that should be translated
911 * @param env the IV environment
913 * @return the translated region constant or NULL
914 * if the translation was not possible
916 static ir_node *applyEdges(ir_node *iv, ir_node *rc, iv_env *env) {
919 if (env->flags & osr_flag_lftr_with_ov_check) {
920 /* overflow can only be decided for Consts */
921 if (! is_Const(rc)) {
922 DB((dbg, LEVEL_4, " = UNKNOWN (%+F)\n", rc));
925 DB((dbg, LEVEL_4, "%+F", get_Const_tarval(rc)));
928 for (irn = iv; rc;) {
929 LFTR_edge *e = LFTR_find(irn, env);
931 rc = applyOneEdge(rc, e, env);
937 DB((dbg, LEVEL_3, "\n"));
942 * Walker, finds Cmp(iv, rc) or Cmp(rc, iv)
943 * and tries to optimize them.
945 static void do_lftr(ir_node *cmp, void *ctx) {
947 ir_node *left, *right, *liv, *riv;
949 ir_node *nleft = NULL, *nright = NULL;
951 if (get_irn_op(cmp) != op_Cmp)
954 left = get_Cmp_left(cmp);
955 right = get_Cmp_right(cmp);
957 liv = is_iv(left, env);
958 riv = is_iv(right, env);
959 if (liv && is_rc(right, liv)) {
960 iv = left; rc = right;
962 nright = applyEdges(iv, rc, env);
963 if (nright && nright != rc) {
964 nleft = followEdges(iv, env);
967 else if (riv && is_rc(left, riv)) {
968 iv = right; rc = left;
970 nleft = applyEdges(iv, rc, env);
971 if (nleft && nleft != rc) {
972 nright = followEdges(iv, env);
976 if (nleft && nright) {
977 DB((dbg, LEVEL_2, " LFTR for %+F\n", cmp));
978 set_Cmp_left(cmp, nleft);
979 set_Cmp_right(cmp, nright);
980 ++env->lftr_replaced;
985 * do linear function test replacement.
987 * @param irg the graph that should be optimized
988 * @param env the IV environment
990 static void lftr(ir_graph *irg, iv_env *env) {
991 irg_walk_graph(irg, NULL, do_lftr, env);
996 * Pre-walker: set all node links to NULL and fix the
997 * block of Proj nodes.
999 static void clear_and_fix(ir_node *irn, void *env)
1001 set_irn_link(irn, NULL);
1004 ir_node *pred = get_Proj_pred(irn);
1005 set_irn_n(irn, -1, get_irn_n(pred, -1));
1009 /* Performs Operator Strength Reduction for the passed graph. */
1010 void opt_osr(ir_graph *irg, unsigned flags) {
1014 if (! get_opt_strength_red()) {
1015 /* only kill Phi cycles */
1016 remove_phi_cycles(irg);
1020 rem = current_ir_graph;
1021 current_ir_graph = irg;
1023 FIRM_DBG_REGISTER(dbg, "firm.opt.osr");
1025 DB((dbg, LEVEL_1, "Doing Operator Strength Reduction for %+F\n", irg));
1027 obstack_init(&env.obst);
1028 env.stack = NEW_ARR_F(ir_node *, 128);
1032 env.quad_map = new_set(quad_cmp, 64);
1033 env.lftr_edges = new_set(LFTR_cmp, 64);
1035 env.lftr_replaced = 0;
1037 env.process_scc = process_scc;
1039 /* Clear all links and move Proj nodes into the
1040 the same block as it's predecessors.
1041 This can improve the placement of new nodes.
1043 irg_walk_graph(irg, NULL, clear_and_fix, NULL);
1045 /* we need dominance */
1047 assure_irg_outs(irg);
1049 /* calculate the post order number for blocks. */
1050 irg_out_block_walk(get_irg_start_block(irg), NULL, assign_po, &env);
1052 /* calculate the SCC's and drive OSR. */
1056 /* try linear function test replacements */
1059 set_irg_outs_inconsistent(irg);
1060 DB((dbg, LEVEL_1, "Replacements: %u + %u (lftr)\n\n", env.replaced, env.lftr_replaced));
1063 del_set(env.lftr_edges);
1064 del_set(env.quad_map);
1065 DEL_ARR_F(env.stack);
1066 obstack_free(&env.obst, NULL);
1068 current_ir_graph = rem;
1071 /* Remove any Phi cycles with only one real input. */
1072 void remove_phi_cycles(ir_graph *irg) {
1076 rem = current_ir_graph;
1077 current_ir_graph = irg;
1079 FIRM_DBG_REGISTER(dbg, "firm.opt.remove_phi");
1081 DB((dbg, LEVEL_1, "Doing Phi cycle removement for %+F\n", irg));
1083 obstack_init(&env.obst);
1084 env.stack = NEW_ARR_F(ir_node *, 128);
1088 env.quad_map = NULL;
1089 env.lftr_edges = NULL;
1091 env.lftr_replaced = 0;
1093 env.process_scc = process_phi_only_scc;
1095 /* Clear all links and move Proj nodes into the
1096 the same block as it's predecessors.
1097 This can improve the placement of new nodes.
1099 irg_walk_graph(irg, NULL, clear_and_fix, NULL);
1101 /* we need dominance */
1102 assure_irg_outs(irg);
1104 /* calculate the post order number for blocks. */
1105 irg_out_block_walk(get_irg_start_block(irg), NULL, assign_po, &env);
1107 /* calculate the SCC's and drive OSR. */
1111 set_irg_outs_inconsistent(irg);
1112 DB((dbg, LEVEL_1, "remove_phi_cycles: %u Cycles removed\n\n", env.replaced));
1115 DEL_ARR_F(env.stack);
1116 obstack_free(&env.obst, NULL);
1118 current_ir_graph = rem;