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 Compute the strongly connected regions and build
23 * backedge/loop datastructures.
24 * A variation on the Tarjan algorithm. See also [Trapp:99],
26 * @author Goetz Lindenmaier
38 #include "irgraph_t.h"
45 /* A variant of the loop tree that avoids loops without head.
46 This reduces the depth of the loop tree. */
47 #define NO_LOOPS_WITHOUT_HEAD 1
49 /** The outermost graph the scc is computed for. */
50 static ir_graph *outermost_ir_graph;
51 /** Current loop construction is working on. */
52 static ir_loop *current_loop;
53 /** Counts the number of allocated loop nodes.
54 * Each loop node gets a unique number.
55 * @todo What for? ev. remove.
57 static int loop_node_cnt = 0;
58 /** Counter to generate depth first numbering of visited nodes. */
59 static int current_dfn = 1;
61 static int max_loop_depth = 0;
63 void link_to_reg_end(ir_node *n, void *env);
64 void set_projx_link(ir_node *cb_projx, ir_node *end_projx);
65 ir_node *get_projx_link(ir_node *cb_projx);
67 /**********************************************************************/
68 /* Node attributes **/
69 /**********************************************************************/
71 /**********************************************************************/
72 /* Node attributes needed for the construction. **/
73 /**********************************************************************/
75 typedef struct scc_info {
76 int in_stack; /**< Marks whether node is on the stack. */
77 int dfn; /**< Depth first search number. */
78 int uplink; /**< dfn number of ancestor. */
79 /* ir_loop *loop; *//* Refers to the containing loop. */
81 struct section *section;
88 * Allocates a new SCC info on the given obstack.
90 static inline scc_info *new_scc_info(struct obstack *obst)
92 return OALLOCZ(obst, scc_info);
96 * Mark node n being on the SCC stack.
98 static inline void mark_irn_in_stack(ir_node *n)
100 scc_info *scc = get_irn_link(n);
106 * Mark node n NOT being on the SCC stack.
108 static inline void mark_irn_not_in_stack(ir_node *n)
110 scc_info *scc = get_irn_link(n);
116 * Checks if a node is on the SCC stack.
118 static inline int irn_is_in_stack(ir_node *n)
120 scc_info *scc = get_irn_link(n);
122 return scc->in_stack;
126 * Sets the uplink number for a node.
128 static inline void set_irn_uplink(ir_node *n, int uplink)
130 scc_info *scc = get_irn_link(n);
132 scc->uplink = uplink;
136 * Returns the uplink number for a node.
138 static int get_irn_uplink(ir_node *n)
140 scc_info *scc = get_irn_link(n);
146 * Sets the depth-first-search number for a node.
148 static inline void set_irn_dfn(ir_node *n, int dfn)
150 scc_info *scc = get_irn_link(n);
156 * Returns the depth-first-search number of a node.
158 static int get_irn_dfn(ir_node *n)
160 scc_info *scc = get_irn_link(n);
166 static ir_loop *find_nodes_loop(ir_node *n, ir_loop *l)
171 /* Test whether n is contained in this loop. */
172 for (i = 0; i < get_loop_n_nodes(l); i++)
173 if (n == get_loop_node(l, i)) return l;
175 /* Is this a leave in the loop tree? If so loop not found. */
176 if (get_loop_n_sons(l) == 0) return NULL;
178 /* Else descend in the loop tree. */
179 for (i = 0; i < get_loop_n_sons(l); i++) {
180 res = find_nodes_loop(n, get_loop_son(l, i));
186 /* @@@ temporary implementation, costly!!! */
187 ir_loop * get_irn_loop(ir_node *n)
189 ir_loop *l = get_irg_loop(current_ir_graph);
190 l = find_nodes_loop(n, l);
195 /**********************************************************************/
197 /**********************************************************************/
199 static ir_node **stack = NULL;
200 static int tos = 0; /* top of stack */
203 * initializes the stack
205 static inline void init_stack(void)
208 ARR_RESIZE(ir_node *, stack, 1000);
210 stack = NEW_ARR_F(ir_node *, 1000);
218 static void finish_stack(void)
225 * push a node onto the stack
227 * @param n The node to push
229 static inline void push(ir_node *n)
231 if (tos == ARR_LEN(stack)) {
232 int nlen = ARR_LEN(stack) * 2;
233 ARR_RESIZE(ir_node *, stack, nlen);
236 mark_irn_in_stack(n);
240 * pop a node from the stack
242 * @return The topmost node
244 static inline ir_node *pop(void)
246 ir_node *n = stack[--tos];
247 mark_irn_not_in_stack(n);
252 * The nodes up to n belong to the current loop.
253 * Removes them from the stack and adds them to the current loop.
255 static inline void pop_scc_to_loop(ir_node *n)
263 set_irn_dfn(m, loop_node_cnt);
264 add_loop_node(current_loop, m);
265 set_irn_loop(m, current_loop);
269 /* GL ??? my last son is my grandson??? Removes loops with no
270 ir_nodes in them. Such loops have only another loop as son. (Why
271 can't they have two loops as sons? Does it never get that far? ) */
272 static void close_loop(ir_loop *l)
274 int last = get_loop_n_elements(l) - 1;
275 loop_element lelement = get_loop_element(l, last);
276 ir_loop *last_son = lelement.son;
278 if (get_kind(last_son) == k_ir_loop &&
279 get_loop_n_elements(last_son) == 1) {
282 lelement = get_loop_element(last_son, 0);
285 if (get_kind(gson) == k_ir_loop) {
286 loop_element new_last_son;
288 gson->outer_loop = l;
289 new_last_son.son = gson;
290 l->children[last] = new_last_son;
297 /* Removes and unmarks all nodes up to n from the stack.
298 The nodes must be visited once more to assign them to a scc. */
299 static inline void pop_scc_unmark_visit(ir_node *n)
305 set_irn_visited(m, 0);
309 /**********************************************************************/
310 /* The loop datastructure. **/
311 /**********************************************************************/
313 /* Allocates a new loop as son of current_loop. Sets current_loop
314 to the new loop and returns the father. */
315 static ir_loop *new_loop(void)
317 ir_loop *father = current_loop;
318 ir_loop *son = alloc_loop(father, outermost_ir_graph->obst);
320 if (son->depth > max_loop_depth) max_loop_depth = son->depth;
325 /**********************************************************************/
326 /* Constructing and destructing the loop/backedge information. **/
327 /**********************************************************************/
329 /* Initialization steps. **********************************************/
331 static inline void init_node(ir_node *n, void *env)
333 struct obstack *obst = env;
334 set_irn_link(n, new_scc_info(obst));
338 static inline void init_scc_common(void)
345 static inline void init_scc(ir_graph *irg, struct obstack *obst)
348 irg_walk_graph(irg, init_node, NULL, obst);
350 irg_walk (irg, link_to_reg_end, NULL, NULL);
354 static inline void finish_scc(void)
359 #ifdef INTERPROCEDURAL_VIEW
360 static inline void init_ip_scc(struct obstack *obst)
363 cg_walk(init_node, NULL, obst);
365 #if EXPERIMENTAL_LOOP_TREE
366 cg_walk(link_to_reg_end, NULL, NULL);
372 * Check weather a given node represents the outer most Start
373 * block. In intra-procedural view this is the start block of the
374 * current graph, in interprocedural view it is the start block
375 * of the outer most graph.
377 * @param n the node to check
379 * This is the condition for breaking the scc recursion.
381 static int is_outermost_Start(ir_node *n)
383 /* Test whether this is the outermost Start node. */
384 if (is_Block(n) && get_Block_n_cfgpreds(n) == 1) {
385 ir_node *pred = skip_Proj(get_Block_cfgpred(n, 0));
386 if (is_Start(pred) && get_nodes_block(pred) == n)
392 static inline int is_ip_Filter(ir_node *n)
394 #ifdef INTERPROCEDURAL_VIEW
395 return is_Filter(n) && get_interprocedural_view();
402 /* When to walk from nodes to blocks. Only for Control flow operations? */
403 static inline int get_start_index(ir_node *n)
405 #undef BLOCK_BEFORE_NODE
406 #define BLOCK_BEFORE_NODE 1
408 #if BLOCK_BEFORE_NODE
410 /* This version assures, that all nodes are ordered absolutely. This allows
411 to undef all nodes in the heap analysis if the block is false, which
413 I.e., with this code, the order on the loop tree is correct. But a
414 (single) test showed the loop tree is deeper. */
415 if (get_irn_op(n) == op_Phi ||
417 (is_ip_Filter(n)) || (
418 get_irg_pinned(get_irn_irg(n)) == op_pin_state_floats &&
419 get_irn_pinned(n) == op_pin_state_floats
421 // Here we could test for backedge at -1 which is illegal
428 /* This version causes deeper loop trees (at least we verified this
430 But it guarantees that Blocks are analysed before nodes contained in the
431 block. If so, we can set the value to undef if the block is not \
433 if (is_cfop(n) || is_fragile_op(n) || is_Start(n))
442 * Return non-zero if the given node is a legal loop header:
443 * Block, Phi, Filter.
445 * @param n the node to check
447 static inline int is_possible_loop_head(ir_node *n)
449 ir_op *op = get_irn_op(n);
450 return ((op == op_Block) ||
456 * Returns non-zero if n is a loop header, i.e., it is a Block, Phi
457 * or Filter node and has predecessors within the loop and out
460 * @param n the node to check
461 * @param root only needed for assertion.
463 static int is_head(ir_node *n, ir_node *root)
466 int some_outof_loop = 0, some_in_loop = 0;
468 /* Test for legal loop header: Block, Phi, ... */
469 if (!is_possible_loop_head(n))
472 if (!is_outermost_Start(n)) {
474 int uplink = get_irn_uplink(root);
478 arity = get_irn_arity(n);
479 for (i = get_start_index(n); i < arity; i++) {
481 if (is_backedge(n, i))
483 pred = get_irn_n(n, i);
484 if (! irn_is_in_stack(pred)) {
487 assert(get_irn_uplink(pred) >= uplink);
492 return some_outof_loop & some_in_loop;
496 * Returns non-zero if n is possible loop head of an endless loop.
497 * I.e., it is a Block, Phi or Filter node and has only predecessors
500 * @param n the node to check
501 * @param root only needed for assertion.
503 static int is_endless_head(ir_node *n, ir_node *root)
506 int none_outof_loop = 1, some_in_loop = 0;
508 /* Test for legal loop header: Block, Phi, ... */
509 if (!is_possible_loop_head(n))
512 if (!is_outermost_Start(n)) {
514 int uplink = get_irn_uplink(root);
518 arity = get_irn_arity(n);
519 for (i = get_start_index(n); i < arity; i++) {
521 if (is_backedge(n, i))
523 pred = get_irn_n(n, i);
524 if (!irn_is_in_stack(pred)) {
527 assert(get_irn_uplink(pred) >= uplink);
532 return none_outof_loop & some_in_loop;
535 /** Returns index of the predecessor with the smallest dfn number
536 greater-equal than limit. */
537 static int smallest_dfn_pred(ir_node *n, int limit)
539 int i, index = -2, min = -1;
541 if (!is_outermost_Start(n)) {
542 int arity = get_irn_arity(n);
543 for (i = get_start_index(n); i < arity; i++) {
544 ir_node *pred = get_irn_n(n, i);
545 if (is_backedge(n, i) || !irn_is_in_stack(pred))
547 if (get_irn_dfn(pred) >= limit && (min == -1 || get_irn_dfn(pred) < min)) {
549 min = get_irn_dfn(pred);
557 * Returns index of the predecessor with the largest dfn number.
559 static int largest_dfn_pred(ir_node *n)
561 int i, index = -2, max = -1;
563 if (!is_outermost_Start(n)) {
564 int arity = get_irn_arity(n);
565 for (i = get_start_index(n); i < arity; i++) {
566 ir_node *pred = get_irn_n(n, i);
567 if (is_backedge (n, i) || !irn_is_in_stack(pred))
569 if (get_irn_dfn(pred) > max) {
571 max = get_irn_dfn(pred);
579 * Searches the stack for possible loop heads. Tests these for backedges.
580 * If it finds a head with an unmarked backedge it marks this edge and
581 * returns the tail of the loop.
582 * If it finds no backedge returns NULL.
583 * ("disable_backedge" in fiasco)
585 * @param n A node where uplink == dfn.
587 static ir_node *find_tail(ir_node *n)
590 int i, res_index = -2;
593 if (!icfg && rm_cyclic_phis && remove_cyclic_phis (n)) return NULL;
595 m = stack[tos-1]; /* tos = top of stack */
597 res_index = smallest_dfn_pred(m, 0);
598 if ((res_index == -2) && /* no smallest dfn pred found. */
602 if (m == n) return NULL; // Is this to catch Phi - self loops?
603 for (i = tos-2; i >= 0; --i) {
607 res_index = smallest_dfn_pred(m, get_irn_dfn(m) + 1);
608 if (res_index == -2) /* no smallest dfn pred found. */
609 res_index = largest_dfn_pred(m);
611 if ((m == n) && (res_index == -2)) { /* don't walk past loop head. */
617 /* We should not walk past our selves on the stack: The upcoming nodes
618 are not in this loop. We assume a loop not reachable from Start. */
626 /* A dead loop not reachable from Start. */
627 for (i = tos-2; i >= 0; --i) {
629 if (is_endless_head(m, n)) {
630 res_index = smallest_dfn_pred(m, get_irn_dfn(m) + 1);
631 if (res_index == -2) /* no smallest dfn pred found. */
632 res_index = largest_dfn_pred (m);
635 if (m == n) { break; } /* It's not an unreachable loop, either. */
637 //assert(0 && "no head found on stack");
641 if (res_index <= -2) {
642 /* It's a completely bad loop: without Phi/Block nodes that can
643 be a head. I.e., the code is "dying". We break the loop by
644 setting Bad nodes. */
645 int arity = get_irn_arity(n);
646 ir_node *bad = get_irg_bad(get_irn_irg(n));
647 for (i = -1; i < arity; ++i) {
648 set_irn_n(n, i, bad);
652 assert(res_index > -2);
654 set_backedge(m, res_index);
655 return is_outermost_Start(n) ? NULL : get_irn_n(m, res_index);
659 #if EXPERIMENTAL_LOOP_TREE
661 /* ----------------------------------------------------------------
662 AS: This is experimental code to build loop trees suitable for
663 the heap analysis. Does not work correctly right now... :-(
666 Search in stack for the corresponding first Call-End-ProjX that
667 corresponds to one of the control flow predecessors of the given
668 block, that is the possible callers.
669 returns: the control predecessor to chose\
670 or -1 if no corresponding Call-End-Node could be found
672 - -------------------------------------------------------------- */
674 int search_endproj_in_stack(ir_node *start_block)
677 assert(is_Block(start_block));
678 for (i = tos - 1; i >= 0; --i)
680 if (get_irn_op(stack[i]) == op_Proj && get_irn_mode(stack[i]) == mode_X &&
681 get_irn_op(get_irn_n(stack[i], 0)) == op_EndReg)
683 printf("FOUND PROJ!!!!!!!!!!!!!!!!!!!!!!!!!!\n");
684 ir_node *end_projx = stack[i];
686 int arity = get_irn_arity(start_block);
687 for (j = 0; j < arity; j++)
689 ir_node *begin_projx = get_Block_cfgpred(get_irg_start_block(get_irn_irg(end_projx)),
690 get_Proj_proj(end_projx));
691 if (get_irn_n(start_block, j) == begin_projx)
693 printf("FOUND IT!!!!!!!!!!!!!!!!!!\n");
703 static pmap *projx_link = NULL;
705 void link_to_reg_end (ir_node *n, void *env)
707 if (get_irn_op(n) == op_Proj &&
708 get_irn_mode(n) == mode_X &&
709 get_irn_op(get_irn_n(n, 0)) == op_EndReg) {
710 /* Reg End Projx -> Find the CallBegin Projx and hash it */
711 ir_node *end_projx = n;
712 ir_node *begin_projx = get_Block_cfgpred(get_irg_start_block(get_irn_irg(end_projx)),
713 get_Proj_proj(end_projx));
714 set_projx_link(begin_projx, end_projx);
718 void set_projx_link(ir_node *cb_projx, ir_node *end_projx)
720 if (projx_link == NULL)
721 projx_link = pmap_create();
722 pmap_insert(projx_link, (void *)cb_projx, (void *)end_projx);
725 ir_node *get_projx_link(ir_node *cb_projx)
727 return((ir_node *) pmap_get(projx_link, (void *)cb_projx));
732 static inline int is_outermost_loop(ir_loop *l)
734 return l == get_loop_outer_loop(l);
738 /*-----------------------------------------------------------*
739 * The core algorithm. *
740 *-----------------------------------------------------------*/
743 * The core algorithm: Find strongly coupled components.
745 * @param n node to start
747 static void scc(ir_node *n)
749 if (irn_visited_else_mark(n))
752 /* Initialize the node */
753 set_irn_dfn(n, current_dfn); /* Depth first number for this node */
754 set_irn_uplink(n, current_dfn); /* ... is default uplink. */
755 set_irn_loop(n, NULL);
759 /* AS: get_start_index might return -1 for Control Flow Nodes, and thus a negative
760 array index would be passed to is_backedge(). But CFG Nodes dont't have a backedge array,
761 so is_backedge does not access array[-1] but correctly returns false! */
763 if (!is_outermost_Start(n)) {
764 int i, arity = get_irn_arity(n);
766 for (i = get_start_index(n); i < arity; ++i) {
768 if (is_backedge(n, i))
772 if (irn_is_in_stack(m)) {
773 /* Uplink of m is smaller if n->m is a backedge.
774 Propagate the uplink to mark the loop. */
775 if (get_irn_uplink(m) < get_irn_uplink(n))
776 set_irn_uplink(n, get_irn_uplink(m));
781 if (get_irn_dfn(n) == get_irn_uplink(n)) {
782 /* This condition holds for
783 1) the node with the incoming backedge.
784 That is: We found a loop!
785 2) Straight line code, because no uplink has been propagated, so the
786 uplink still is the same as the dfn.
788 But n might not be a proper loop head for the analysis. Proper loop
789 heads are Block and Phi nodes. find_tail() searches the stack for
790 Block's and Phi's and takes those nodes as loop heads for the current
791 loop instead and marks the incoming edge as backedge. */
793 ir_node *tail = find_tail(n);
795 /* We have a loop, that is no straight line code,
796 because we found a loop head!
797 Next actions: Open a new loop on the loop tree and
798 try to find inner loops */
800 #if NO_LOOPS_WITHOUT_HEAD
801 /* This is an adaption of the algorithm from fiasco / optscc to
802 * avoid loops without Block or Phi as first node. This should
803 * severely reduce the number of evaluations of nodes to detect
804 * a fixpoint in the heap analysis.
805 * Further it avoids loops without firm nodes that cause errors
806 * in the heap analyses.
807 * But attention: don't do it for the outermost loop: This loop
808 * is not iterated. A first block can be a loop head in case of
809 * an endless recursion. */
813 if ((get_loop_n_elements(current_loop) > 0) || (is_outermost_loop(current_loop))) {
821 ir_loop *l = new_loop();
824 /* Remove the loop from the stack ... */
825 pop_scc_unmark_visit(n);
827 /* The current backedge has been marked, that is temporarily eliminated,
828 by find tail. Start the scc algorithm
829 again on the subgraph that is left (the current loop without the backedge)
830 in order to find more inner loops. */
833 assert(irn_visited(n));
834 #if NO_LOOPS_WITHOUT_HEAD
839 /* No loop head was found, that is we have straight line code.
840 Pop all nodes from the stack to the current loop. */
846 #ifdef INTERPROCEDURAL_VIEW
847 static void my_scc(ir_node *n)
850 if (irn_visited_else_mark(n))
853 /* Initialize the node */
854 set_irn_dfn(n, current_dfn); /* Depth first number for this node */
855 set_irn_uplink(n, current_dfn); /* ... is default uplink. */
856 set_irn_loop(n, NULL);
860 /* AS: get_start_index might return -1 for Control Flow Nodes, and thus a negative
861 array index would be passed to is_backedge(). But CFG Nodes dont't have a backedge array,
862 so is_backedge does not access array[-1] but correctly returns false! */
864 if (!is_outermost_Start(n)) {
865 int arity = get_irn_arity(n);
867 for (i = get_start_index(n); i < arity; i++) {
869 if (is_backedge(n, i)) continue;
870 m = get_irn_n(n, i); /* get_irn_ip_pred(n, i); */
871 /* if (!m || is_Unknown(m)) continue; */
873 if (irn_is_in_stack(m)) {
874 /* Uplink of m is smaller if n->m is a backedge.
875 Propagate the uplink to mark the loop. */
876 if (get_irn_uplink(m) < get_irn_uplink(n))
877 set_irn_uplink(n, get_irn_uplink(m));
882 if (get_irn_dfn(n) == get_irn_uplink(n)) {
883 /* This condition holds for
884 1) the node with the incoming backedge.
885 That is: We found a loop!
886 2) Straight line code, because no uplink has been propagated, so the
887 uplink still is the same as the dfn.
889 But n might not be a proper loop head for the analysis. Proper loop
890 heads are Block and Phi nodes. find_tail searches the stack for
891 Block's and Phi's and takes those nodes as loop heads for the current
892 loop instead and marks the incoming edge as backedge. */
894 ir_node *tail = find_tail(n);
896 /* We have a loop, that is no straight line code,
897 because we found a loop head!
898 Next actions: Open a new loop on the loop tree and
899 try to find inner loops */
901 #if NO_LOOPS_WITHOUT_HEAD
902 /* This is an adaption of the algorithm from fiasco / optscc to
903 * avoid loops without Block or Phi as first node. This should
904 * severely reduce the number of evaluations of nodes to detect
905 * a fixpoint in the heap analysis.
906 * Further it avoids loops without firm nodes that cause errors
907 * in the heap analyses. */
911 if ((get_loop_n_elements(current_loop) > 0) || (is_outermost_loop(current_loop))) {
919 ir_loop *l = new_loop();
922 /* Remove the loop from the stack ... */
923 pop_scc_unmark_visit(n);
925 /* The current backedge has been marked, that is temporarily eliminated,
926 by find tail. Start the scc algorithm
927 anew on the subgraph that is left (the current loop without the backedge)
928 in order to find more inner loops. */
931 assert(irn_visited(n));
932 #if NO_LOOPS_WITHOUT_HEAD
937 /* No loop head was found, that is we have straightline code.
938 Pop all nodes from the stack to the current loop. */
943 #endif /* INTERPROCEDURAL_VIEW */
945 /* Constructs backedge information for irg. In interprocedural view constructs
946 backedges for all methods called by irg, too. */
947 int construct_backedges(ir_graph *irg)
949 ir_graph *rem = current_ir_graph;
953 #ifdef INTERPROCEDURAL_VIEW
954 assert(!get_interprocedural_view() &&
955 "not implemented, use construct_ip_backedges()");
959 current_ir_graph = irg;
960 outermost_ir_graph = irg;
963 init_scc(irg, &temp);
966 new_loop(); /* sets current_loop */
967 head_rem = current_loop; /* Just for assertion */
969 inc_irg_visited(irg);
971 scc(get_irg_end(irg));
974 obstack_free(&temp, NULL);
976 assert(head_rem == current_loop);
977 mature_loops(current_loop, irg->obst);
978 set_irg_loop(irg, current_loop);
979 set_irg_loopinfo_state(irg, loopinfo_consistent);
980 assert(get_irg_loop(irg)->kind == k_ir_loop);
981 current_ir_graph = rem;
982 return max_loop_depth;
986 #ifdef INTERPROCEDURAL_VIEW
987 int construct_ip_backedges(void)
989 ir_graph *rem = current_ir_graph;
990 int rem_ipv = get_interprocedural_view();
995 assert(get_irp_ip_view_state() == ip_view_valid);
997 outermost_ir_graph = get_irp_main_irg();
1002 current_loop = NULL;
1003 new_loop(); /* sets current_loop */
1004 set_interprocedural_view(1);
1006 inc_max_irg_visited();
1007 for (i = 0; i < get_irp_n_irgs(); i++)
1008 set_irg_visited(get_irp_irg(i), get_max_irg_visited());
1010 /** We have to start the walk at the same nodes as cg_walk. **/
1011 /* Walk starting at unreachable procedures. Only these
1012 * have End blocks visible in interprocedural view. */
1013 for (i = 0; i < get_irp_n_irgs(); i++) {
1015 current_ir_graph = get_irp_irg(i);
1017 sb = get_irg_start_block(current_ir_graph);
1019 if ((get_Block_n_cfgpreds(sb) > 1) ||
1020 (get_nodes_block(get_Block_cfgpred(sb, 0)) != sb))
1023 scc(get_irg_end(current_ir_graph));
1026 /* Check whether we walked all procedures: there could be procedures
1027 with cyclic calls but no call from the outside. */
1028 for (i = 0; i < get_irp_n_irgs(); i++) {
1030 current_ir_graph = get_irp_irg(i);
1032 /* Test start block: if inner procedure end and end block are not
1033 * visible and therefore not marked. */
1034 sb = get_irg_start_block(current_ir_graph);
1035 if (get_irn_visited(sb) < get_irg_visited(current_ir_graph)) scc(sb);
1038 /* Walk all endless loops in inner procedures.
1039 * We recognize an inner procedure if the End node is not visited. */
1040 for (i = 0; i < get_irp_n_irgs(); i++) {
1042 current_ir_graph = get_irp_irg(i);
1044 e = get_irg_end(current_ir_graph);
1045 if (get_irn_visited(e) < get_irg_visited(current_ir_graph)) {
1047 /* Don't visit the End node. */
1048 for (j = 0; j < get_End_n_keepalives(e); j++)
1049 scc(get_End_keepalive(e, j));
1053 set_irg_loop(outermost_ir_graph, current_loop);
1054 set_irg_loopinfo_state(current_ir_graph, loopinfo_ip_consistent);
1055 assert(get_irg_loop(outermost_ir_graph)->kind == k_ir_loop);
1057 obstack_free(&temp, NULL);
1058 current_ir_graph = rem;
1059 set_interprocedural_view(rem_ipv);
1060 return max_loop_depth;
1063 void my_construct_ip_backedges(void)
1065 ir_graph *rem = current_ir_graph;
1066 int rem_ipv = get_interprocedural_view();
1069 assert(get_irp_ip_view_state() == ip_view_valid);
1071 outermost_ir_graph = get_irp_main_irg();
1075 current_loop = NULL;
1076 new_loop(); /* sets current_loop */
1077 set_interprocedural_view(1);
1079 inc_max_irg_visited();
1080 for (i = 0; i < get_irp_n_irgs(); i++)
1081 set_irg_visited(get_irp_irg(i), get_max_irg_visited());
1083 /** We have to start the walk at the same nodes as cg_walk. **/
1084 /* Walk starting at unreachable procedures. Only these
1085 * have End blocks visible in interprocedural view. */
1086 for (i = 0; i < get_irp_n_irgs(); i++) {
1088 current_ir_graph = get_irp_irg(i);
1090 sb = get_irg_start_block(current_ir_graph);
1092 if ((get_Block_n_cfgpreds(sb) > 1) ||
1093 (get_nodes_block(get_Block_cfgpred(sb, 0)) != sb)) continue;
1095 my_scc(get_irg_end(current_ir_graph));
1098 /* Check whether we walked all procedures: there could be procedures
1099 with cyclic calls but no call from the outside. */
1100 for (i = 0; i < get_irp_n_irgs(); i++) {
1102 current_ir_graph = get_irp_irg(i);
1104 /* Test start block: if inner procedure end and end block are not
1105 * visible and therefore not marked. */
1106 sb = get_irg_start_block(current_ir_graph);
1107 if (get_irn_visited(sb) < get_irg_visited(current_ir_graph))
1111 /* Walk all endless loops in inner procedures.
1112 * We recognize an inner procedure if the End node is not visited. */
1113 for (i = 0; i < get_irp_n_irgs(); i++) {
1115 current_ir_graph = get_irp_irg(i);
1117 e = get_irg_end(current_ir_graph);
1118 if (get_irn_visited(e) < get_irg_visited(current_ir_graph)) {
1120 /* Don't visit the End node. */
1121 for (j = 0; j < get_End_n_keepalives(e); j++) scc(get_End_keepalive(e, j));
1125 set_irg_loop(outermost_ir_graph, current_loop);
1126 set_irg_loopinfo_state(current_ir_graph, loopinfo_ip_consistent);
1127 assert(get_irg_loop(outermost_ir_graph)->kind == k_ir_loop);
1129 current_ir_graph = rem;
1130 set_interprocedural_view(rem_ipv);
1134 static void reset_backedges(ir_node *n)
1136 if (is_possible_loop_head(n)) {
1137 #ifdef INTERPROCEDURAL_VIEW
1138 int rem = get_interprocedural_view();
1140 set_interprocedural_view(1);
1142 set_interprocedural_view(1);
1144 set_interprocedural_view(rem);
1153 static void loop_reset_backedges(ir_loop *l)
1156 reset_backedges(get_loop_node(l, 0));
1157 for (i = 0; i < get_loop_n_nodes(l); ++i)
1158 set_irn_loop(get_loop_node(l, i), NULL);
1159 for (i = 0; i < get_loop_n_sons(l); ++i) {
1160 loop_reset_backedges(get_loop_son(l, i));
1165 static void loop_reset_node(ir_node *n, void *env)
1168 set_irn_loop(n, NULL);
1173 /** Removes all loop information.
1174 Resets all backedges */
1175 void free_loop_information(ir_graph *irg)
1177 /* We can not use this recursion, as the loop might contain
1178 illegal nodes by now. Why else would we throw away the
1180 if (get_irg_loop(irg)) loop_reset_backedges(get_irg_loop(irg));
1182 irg_walk_graph(irg, loop_reset_node, NULL, NULL);
1183 set_irg_loop(irg, NULL);
1184 set_irg_loopinfo_state(current_ir_graph, loopinfo_none);
1185 /* We cannot free the loop nodes, they are on the obstack. */
1189 void free_all_loop_information(void)
1192 #ifdef INTERPROCEDURAL_VIEW
1193 int rem = get_interprocedural_view();
1194 set_interprocedural_view(1); /* To visit all filter nodes */
1196 for (i = 0; i < get_irp_n_irgs(); i++) {
1197 free_loop_information(get_irp_irg(i));
1199 #ifdef INTERPROCEDURAL_VIEW
1200 set_interprocedural_view(rem);
1204 /* ------------------------------------------------------------------- */
1205 /* Simple analyses based on the loop information */
1206 /* ------------------------------------------------------------------- */
1208 static int is_loop_variant(ir_loop *l, ir_loop *b)
1212 if (l == b) return 1;
1214 n_elems = get_loop_n_elements(l);
1215 for (i = 0; i < n_elems; ++i) {
1216 loop_element e = get_loop_element(l, i);
1217 if (is_ir_loop(e.kind))
1218 if (is_loop_variant(e.son, b))
1225 /* Test whether a value is loop invariant.
1227 * @param n The node to be tested.
1228 * @param block A block node. We pass the block, not the loop as we must
1229 * start off with a block loop to find all proper uses.
1231 * Returns non-zero, if the node n is not changed in the loop block
1232 * belongs to or in inner loops of this blocks loop. */
1233 int is_loop_invariant(const ir_node *n, const ir_node *block)
1235 ir_loop *l = get_irn_loop(block);
1236 const ir_node *b = is_Block(n) ? n : get_nodes_block(n);
1237 return !is_loop_variant(l, get_irn_loop(b));