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
40 #include "irgraph_t.h"
47 /* A variant of the loop tree that avoids loops without head.
48 This reduces the depth of the loop tree. */
49 #define NO_LOOPS_WITHOUT_HEAD 1
51 /** The outermost graph the scc is computed for. */
52 static ir_graph *outermost_ir_graph;
53 /** Current loop construction is working on. */
54 static ir_loop *current_loop;
55 /** Counts the number of allocated loop nodes.
56 * Each loop node gets a unique number.
57 * @todo What for? ev. remove.
59 static int loop_node_cnt = 0;
60 /** Counter to generate depth first numbering of visited nodes. */
61 static int current_dfn = 1;
63 static int max_loop_depth = 0;
65 void link_to_reg_end(ir_node *n, void *env);
66 void set_projx_link(ir_node *cb_projx, ir_node *end_projx);
67 ir_node *get_projx_link(ir_node *cb_projx);
69 /**********************************************************************/
70 /* Node attributes **/
71 /**********************************************************************/
73 /**********************************************************************/
74 /* Node attributes needed for the construction. **/
75 /**********************************************************************/
77 typedef struct scc_info {
78 int in_stack; /**< Marks whether node is on the stack. */
79 int dfn; /**< Depth first search number. */
80 int uplink; /**< dfn number of ancestor. */
81 /* ir_loop *loop; *//* Refers to the containing loop. */
83 struct section *section;
90 * Allocates a new SCC info on the given obstack.
92 static inline scc_info *new_scc_info(struct obstack *obst) {
93 scc_info *info = obstack_alloc(obst, sizeof(*info));
94 memset(info, 0, sizeof(*info));
99 * Mark node n being on the SCC stack.
101 static inline void mark_irn_in_stack(ir_node *n) {
102 scc_info *scc = get_irn_link(n);
108 * Mark node n NOT being on the SCC stack.
110 static inline void mark_irn_not_in_stack(ir_node *n) {
111 scc_info *scc = get_irn_link(n);
117 * Checks if a node is on the SCC stack.
119 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) {
129 scc_info *scc = get_irn_link(n);
131 scc->uplink = uplink;
135 * Returns the uplink number for a node.
137 static int get_irn_uplink(ir_node *n) {
138 scc_info *scc = get_irn_link(n);
144 * Sets the depth-first-search number for a node.
146 static inline void set_irn_dfn(ir_node *n, int dfn) {
147 scc_info *scc = get_irn_link(n);
153 * Returns the depth-first-search number of a node.
155 static int get_irn_dfn(ir_node *n) {
156 scc_info *scc = get_irn_link(n);
162 static ir_loop *find_nodes_loop(ir_node *n, ir_loop *l) {
166 /* Test whether n is contained in this loop. */
167 for (i = 0; i < get_loop_n_nodes(l); i++)
168 if (n == get_loop_node(l, i)) return l;
170 /* Is this a leave in the loop tree? If so loop not found. */
171 if (get_loop_n_sons(l) == 0) return NULL;
173 /* Else descend in the loop tree. */
174 for (i = 0; i < get_loop_n_sons(l); i++) {
175 res = find_nodes_loop(n, get_loop_son(l, i));
181 /* @@@ temporary implementation, costly!!! */
182 ir_loop * get_irn_loop(ir_node *n) {
183 ir_loop *l = get_irg_loop(current_ir_graph);
184 l = find_nodes_loop(n, l);
189 /**********************************************************************/
191 /**********************************************************************/
193 static ir_node **stack = NULL;
194 static int tos = 0; /* top of stack */
197 * initializes the stack
199 static inline void init_stack(void) {
201 ARR_RESIZE(ir_node *, stack, 1000);
203 stack = NEW_ARR_F(ir_node *, 1000);
211 static void finish_stack(void) {
217 * push a node onto the stack
219 * @param n The node to push
221 static inline void push(ir_node *n) {
222 if (tos == ARR_LEN(stack)) {
223 int nlen = ARR_LEN(stack) * 2;
224 ARR_RESIZE(ir_node *, stack, nlen);
227 mark_irn_in_stack(n);
231 * pop a node from the stack
233 * @return The topmost node
235 static inline ir_node *pop(void) {
236 ir_node *n = stack[--tos];
237 mark_irn_not_in_stack(n);
242 * The nodes up to n belong to the current loop.
243 * Removes them from the stack and adds them to the current loop.
245 static inline void pop_scc_to_loop(ir_node *n) {
253 set_irn_dfn(m, loop_node_cnt);
254 add_loop_node(current_loop, m);
255 set_irn_loop(m, current_loop);
259 /* i might be bigger than 1 for dead (and that's why bad) loops */
261 printf("Mehr als eine Iteration!!!!!!!!!!!!!!!!!!!!!!!!!!!!11111\n");
265 /* GL ??? my last son is my grandson??? Removes loops with no
266 ir_nodes in them. Such loops have only another loop as son. (Why
267 can't they have two loops as sons? Does it never get that far? ) */
268 static void close_loop(ir_loop *l) {
269 int last = get_loop_n_elements(l) - 1;
270 loop_element lelement = get_loop_element(l, last);
271 ir_loop *last_son = lelement.son;
273 if (get_kind(last_son) == k_ir_loop &&
274 get_loop_n_elements(last_son) == 1) {
277 lelement = get_loop_element(last_son, 0);
280 if (get_kind(gson) == k_ir_loop) {
281 loop_element new_last_son;
283 gson->outer_loop = l;
284 new_last_son.son = gson;
285 l->children[last] = new_last_son;
292 /* Removes and unmarks all nodes up to n from the stack.
293 The nodes must be visited once more to assign them to a scc. */
294 static inline void pop_scc_unmark_visit(ir_node *n) {
299 set_irn_visited(m, 0);
303 /**********************************************************************/
304 /* The loop datastructure. **/
305 /**********************************************************************/
307 /* Allocates a new loop as son of current_loop. Sets current_loop
308 to the new loop and returns the father. */
309 static ir_loop *new_loop(void) {
310 ir_loop *father = current_loop;
311 ir_loop *son = alloc_loop(father, outermost_ir_graph->obst);
313 if (son->depth > max_loop_depth) max_loop_depth = son->depth;
318 /**********************************************************************/
319 /* Constructing and destructing the loop/backedge information. **/
320 /**********************************************************************/
322 /* Initialization steps. **********************************************/
324 static inline void init_node(ir_node *n, void *env) {
325 struct obstack *obst = env;
326 set_irn_link(n, new_scc_info(obst));
330 static inline void init_scc_common(void) {
336 static inline void init_scc(ir_graph *irg, struct obstack *obst) {
338 irg_walk_graph(irg, init_node, NULL, obst);
340 irg_walk (irg, link_to_reg_end, NULL, NULL);
344 static inline void finish_scc(void)
349 #ifdef INTERPROCEDURAL_VIEW
350 static inline void init_ip_scc(struct obstack *obst) {
352 cg_walk(init_node, NULL, obst);
354 #if EXPERIMENTAL_LOOP_TREE
355 cg_walk(link_to_reg_end, NULL, NULL);
361 * Check weather a given node represents the outer most Start
362 * block. In intra-procedural view this is the start block of the
363 * current graph, in interprocedural view it is the start block
364 * of the outer most graph.
366 * @param n the node to check
368 * This is the condition for breaking the scc recursion.
370 static int is_outermost_Start(ir_node *n) {
371 /* Test whether this is the outermost Start node. */
372 if (is_Block(n) && get_Block_n_cfgpreds(n) == 1) {
373 ir_node *pred = skip_Proj(get_Block_cfgpred(n, 0));
374 if (is_Start(pred) && get_nodes_block(pred) == n)
380 /* When to walk from nodes to blocks. Only for Control flow operations? */
381 static inline int get_start_index(ir_node *n) {
382 #undef BLOCK_BEFORE_NODE
383 #define BLOCK_BEFORE_NODE 1
385 #if BLOCK_BEFORE_NODE
387 /* This version assures, that all nodes are ordered absolutely. This allows
388 to undef all nodes in the heap analysis if the block is false, which means
390 I.e., with this code, the order on the loop tree is correct. But a (single)
391 test showed the loop tree is deeper. */
392 if (get_irn_op(n) == op_Phi ||
394 (is_Filter(n) && get_interprocedural_view()) || (
395 get_irg_pinned(get_irn_irg(n)) == op_pin_state_floats &&
396 get_irn_pinned(n) == op_pin_state_floats
398 // Here we could test for backedge at -1 which is illegal
405 /* This version causes deeper loop trees (at least we verified this
407 But it guarantees that Blocks are analysed before nodes contained in the
408 block. If so, we can set the value to undef if the block is not \
410 if (is_cfop(n) || is_fragile_op(n) || is_Start(n))
419 * Return non-zero if the given node is a legal loop header:
420 * Block, Phi, Filter.
422 * @param n the node to check
424 static inline int is_possible_loop_head(ir_node *n) {
425 ir_op *op = get_irn_op(n);
426 return ((op == op_Block) ||
428 ((op == op_Filter) && get_interprocedural_view()));
432 * Returns non-zero if n is a loop header, i.e., it is a Block, Phi
433 * or Filter node and has predecessors within the loop and out
436 * @param n the node to check
437 * @param root only needed for assertion.
439 static int is_head(ir_node *n, ir_node *root) {
441 int some_outof_loop = 0, some_in_loop = 0;
443 /* Test for legal loop header: Block, Phi, ... */
444 if (!is_possible_loop_head(n))
447 if (!is_outermost_Start(n)) {
449 int uplink = get_irn_uplink(root);
453 arity = get_irn_arity(n);
454 for (i = get_start_index(n); i < arity; i++) {
456 if (is_backedge(n, i))
458 pred = get_irn_n(n, i);
459 if (! irn_is_in_stack(pred)) {
462 assert(get_irn_uplink(pred) >= uplink);
467 return some_outof_loop & some_in_loop;
471 * Returns non-zero if n is possible loop head of an endless loop.
472 * I.e., it is a Block, Phi or Filter node and has only predecessors
475 * @param n the node to check
476 * @param root only needed for assertion.
478 static int is_endless_head(ir_node *n, ir_node *root) {
480 int none_outof_loop = 1, some_in_loop = 0;
482 /* Test for legal loop header: Block, Phi, ... */
483 if (!is_possible_loop_head(n))
486 if (!is_outermost_Start(n)) {
488 int uplink = get_irn_uplink(root);
492 arity = get_irn_arity(n);
493 for (i = get_start_index(n); i < arity; i++) {
495 if (is_backedge(n, i))
497 pred = get_irn_n(n, i);
498 if (!irn_is_in_stack(pred)) {
501 assert(get_irn_uplink(pred) >= uplink);
506 return none_outof_loop & some_in_loop;
509 /** Returns index of the predecessor with the smallest dfn number
510 greater-equal than limit. */
511 static int smallest_dfn_pred(ir_node *n, int limit) {
512 int i, index = -2, min = -1;
514 if (!is_outermost_Start(n)) {
515 int arity = get_irn_arity(n);
516 for (i = get_start_index(n); i < arity; i++) {
517 ir_node *pred = get_irn_n(n, i);
518 if (is_backedge(n, i) || !irn_is_in_stack(pred))
520 if (get_irn_dfn(pred) >= limit && (min == -1 || get_irn_dfn(pred) < min)) {
522 min = get_irn_dfn(pred);
530 * Returns index of the predecessor with the largest dfn number.
532 static int largest_dfn_pred(ir_node *n) {
533 int i, index = -2, max = -1;
535 if (!is_outermost_Start(n)) {
536 int arity = get_irn_arity(n);
537 for (i = get_start_index(n); i < arity; i++) {
538 ir_node *pred = get_irn_n(n, i);
539 if (is_backedge (n, i) || !irn_is_in_stack(pred))
541 if (get_irn_dfn(pred) > max) {
543 max = get_irn_dfn(pred);
551 * Searches the stack for possible loop heads. Tests these for backedges.
552 * If it finds a head with an unmarked backedge it marks this edge and
553 * returns the tail of the loop.
554 * If it finds no backedge returns NULL.
555 * ("disable_backedge" in fiasco)
557 * @param n A node where uplink == dfn.
559 static ir_node *find_tail(ir_node *n) {
561 int i, res_index = -2;
564 if (!icfg && rm_cyclic_phis && remove_cyclic_phis (n)) return NULL;
566 m = stack[tos-1]; /* tos = top of stack */
568 res_index = smallest_dfn_pred(m, 0);
569 if ((res_index == -2) && /* no smallest dfn pred found. */
573 if (m == n) return NULL; // Is this to catch Phi - self loops?
574 for (i = tos-2; i >= 0; --i) {
578 res_index = smallest_dfn_pred(m, get_irn_dfn(m) + 1);
579 if (res_index == -2) /* no smallest dfn pred found. */
580 res_index = largest_dfn_pred(m);
582 if ((m == n) && (res_index == -2)) { /* don't walk past loop head. */
588 /* We should not walk past our selves on the stack: The upcoming nodes
589 are not in this loop. We assume a loop not reachable from Start. */
597 /* A dead loop not reachable from Start. */
598 for (i = tos-2; i >= 0; --i) {
600 if (is_endless_head(m, n)) {
601 res_index = smallest_dfn_pred(m, get_irn_dfn(m) + 1);
602 if (res_index == -2) /* no smallest dfn pred found. */
603 res_index = largest_dfn_pred (m);
606 if (m == n) { break; } /* It's not an unreachable loop, either. */
608 //assert(0 && "no head found on stack");
612 if (res_index <= -2) {
613 /* It's a completely bad loop: without Phi/Block nodes that can
614 be a head. I.e., the code is "dying". We break the loop by
615 setting Bad nodes. */
616 int arity = get_irn_arity(n);
617 ir_node *bad = get_irg_bad(get_irn_irg(n));
618 for (i = -1; i < arity; ++i) {
619 set_irn_n(n, i, bad);
623 assert(res_index > -2);
625 set_backedge(m, res_index);
626 return is_outermost_Start(n) ? NULL : get_irn_n(m, res_index);
630 #if EXPERIMENTAL_LOOP_TREE
632 /* ----------------------------------------------------------------
633 AS: This is experimental code to build loop trees suitable for
634 the heap analysis. Does not work correctly right now... :-(
637 Search in stack for the corresponding first Call-End-ProjX that
638 corresponds to one of the control flow predecessors of the given
639 block, that is the possible callers.
640 returns: the control predecessor to chose\
641 or -1 if no corresponding Call-End-Node could be found
643 - -------------------------------------------------------------- */
645 int search_endproj_in_stack(ir_node *start_block) {
647 assert(is_Block(start_block));
648 for(i = tos - 1; i >= 0; --i)
650 if(get_irn_op(stack[i]) == op_Proj && get_irn_mode(stack[i]) == mode_X &&
651 get_irn_op(get_irn_n(stack[i], 0)) == op_EndReg)
653 printf("FOUND PROJ!!!!!!!!!!!!!!!!!!!!!!!!!!\n");
654 ir_node *end_projx = stack[i];
656 int arity = get_irn_arity(start_block);
657 for(j = 0; j < arity; j++)
659 ir_node *begin_projx = get_Block_cfgpred(get_irg_start_block(get_irn_irg(end_projx)),
660 get_Proj_proj(end_projx));
661 if(get_irn_n(start_block, j) == begin_projx)
663 printf("FOUND IT!!!!!!!!!!!!!!!!!!\n");
673 static pmap *projx_link = NULL;
675 void link_to_reg_end (ir_node *n, void *env) {
676 if(get_irn_op(n) == op_Proj &&
677 get_irn_mode(n) == mode_X &&
678 get_irn_op(get_irn_n(n, 0)) == op_EndReg) {
679 /* Reg End Projx -> Find the CallBegin Projx and hash it */
680 ir_node *end_projx = n;
681 ir_node *begin_projx = get_Block_cfgpred(get_irg_start_block(get_irn_irg(end_projx)),
682 get_Proj_proj(end_projx));
683 set_projx_link(begin_projx, end_projx);
687 void set_projx_link(ir_node *cb_projx, ir_node *end_projx) {
688 if(projx_link == NULL)
689 projx_link = pmap_create();
690 pmap_insert(projx_link, (void *)cb_projx, (void *)end_projx);
693 ir_node *get_projx_link(ir_node *cb_projx) {
694 return((ir_node *) pmap_get(projx_link, (void *)cb_projx));
699 static inline int is_outermost_loop(ir_loop *l) {
700 return l == get_loop_outer_loop(l);
704 /*-----------------------------------------------------------*
705 * The core algorithm. *
706 *-----------------------------------------------------------*/
709 * The core algorithm: Find strongly coupled components.
711 * @param n node to start
713 static void scc(ir_node *n) {
714 if (irn_visited_else_mark(n))
717 /* Initialize the node */
718 set_irn_dfn(n, current_dfn); /* Depth first number for this node */
719 set_irn_uplink(n, current_dfn); /* ... is default uplink. */
720 set_irn_loop(n, NULL);
724 /* AS: get_start_index might return -1 for Control Flow Nodes, and thus a negative
725 array index would be passed to is_backedge(). But CFG Nodes dont't have a backedge array,
726 so is_backedge does not access array[-1] but correctly returns false! */
728 if (!is_outermost_Start(n)) {
729 int i, arity = get_irn_arity(n);
731 for (i = get_start_index(n); i < arity; ++i) {
733 if (is_backedge(n, i))
737 if (irn_is_in_stack(m)) {
738 /* Uplink of m is smaller if n->m is a backedge.
739 Propagate the uplink to mark the loop. */
740 if (get_irn_uplink(m) < get_irn_uplink(n))
741 set_irn_uplink(n, get_irn_uplink(m));
746 if (get_irn_dfn(n) == get_irn_uplink(n)) {
747 /* This condition holds for
748 1) the node with the incoming backedge.
749 That is: We found a loop!
750 2) Straight line code, because no uplink has been propagated, so the
751 uplink still is the same as the dfn.
753 But n might not be a proper loop head for the analysis. Proper loop
754 heads are Block and Phi nodes. find_tail() searches the stack for
755 Block's and Phi's and takes those nodes as loop heads for the current
756 loop instead and marks the incoming edge as backedge. */
758 ir_node *tail = find_tail(n);
760 /* We have a loop, that is no straight line code,
761 because we found a loop head!
762 Next actions: Open a new loop on the loop tree and
763 try to find inner loops */
765 #if NO_LOOPS_WITHOUT_HEAD
766 /* This is an adaption of the algorithm from fiasco / optscc to
767 * avoid loops without Block or Phi as first node. This should
768 * severely reduce the number of evaluations of nodes to detect
769 * a fixpoint in the heap analysis.
770 * Further it avoids loops without firm nodes that cause errors
771 * in the heap analyses.
772 * But attention: don't do it for the outermost loop: This loop
773 * is not iterated. A first block can be a loop head in case of
774 * an endless recursion. */
778 if ((get_loop_n_elements(current_loop) > 0) || (is_outermost_loop(current_loop))) {
786 ir_loop *l = new_loop();
789 /* Remove the loop from the stack ... */
790 pop_scc_unmark_visit(n);
792 /* The current backedge has been marked, that is temporarily eliminated,
793 by find tail. Start the scc algorithm
794 again on the subgraph that is left (the current loop without the backedge)
795 in order to find more inner loops. */
798 assert(irn_visited(n));
799 #if NO_LOOPS_WITHOUT_HEAD
804 /* No loop head was found, that is we have straight line code.
805 Pop all nodes from the stack to the current loop. */
811 #ifdef INTERPROCEDURAL_VIEW
812 static void my_scc(ir_node *n) {
814 if (irn_visited_else_mark(n))
817 /* Initialize the node */
818 set_irn_dfn(n, current_dfn); /* Depth first number for this node */
819 set_irn_uplink(n, current_dfn); /* ... is default uplink. */
820 set_irn_loop(n, NULL);
824 /* AS: get_start_index might return -1 for Control Flow Nodes, and thus a negative
825 array index would be passed to is_backedge(). But CFG Nodes dont't have a backedge array,
826 so is_backedge does not access array[-1] but correctly returns false! */
828 if (!is_outermost_Start(n)) {
829 int arity = get_irn_arity(n);
831 for (i = get_start_index(n); i < arity; i++) {
833 if (is_backedge(n, i)) continue;
834 m = get_irn_n(n, i); /* get_irn_ip_pred(n, i); */
835 /* if (!m || is_Unknown(m)) continue; */
837 if (irn_is_in_stack(m)) {
838 /* Uplink of m is smaller if n->m is a backedge.
839 Propagate the uplink to mark the loop. */
840 if (get_irn_uplink(m) < get_irn_uplink(n))
841 set_irn_uplink(n, get_irn_uplink(m));
846 if (get_irn_dfn(n) == get_irn_uplink(n)) {
847 /* This condition holds for
848 1) the node with the incoming backedge.
849 That is: We found a loop!
850 2) Straight line code, because no uplink has been propagated, so the
851 uplink still is the same as the dfn.
853 But n might not be a proper loop head for the analysis. Proper loop
854 heads are Block and Phi nodes. find_tail searches the stack for
855 Block's and Phi's and takes those nodes as loop heads for the current
856 loop instead and marks the incoming edge as backedge. */
858 ir_node *tail = find_tail(n);
860 /* We have a loop, that is no straight line code,
861 because we found a loop head!
862 Next actions: Open a new loop on the loop tree and
863 try to find inner loops */
865 #if NO_LOOPS_WITHOUT_HEAD
866 /* This is an adaption of the algorithm from fiasco / optscc to
867 * avoid loops without Block or Phi as first node. This should
868 * severely reduce the number of evaluations of nodes to detect
869 * a fixpoint in the heap analysis.
870 * Further it avoids loops without firm nodes that cause errors
871 * in the heap analyses. */
875 if ((get_loop_n_elements(current_loop) > 0) || (is_outermost_loop(current_loop))) {
883 ir_loop *l = new_loop();
886 /* Remove the loop from the stack ... */
887 pop_scc_unmark_visit(n);
889 /* The current backedge has been marked, that is temporarily eliminated,
890 by find tail. Start the scc algorithm
891 anew on the subgraph that is left (the current loop without the backedge)
892 in order to find more inner loops. */
895 assert(irn_visited(n));
896 #if NO_LOOPS_WITHOUT_HEAD
901 /* No loop head was found, that is we have straightline code.
902 Pop all nodes from the stack to the current loop. */
907 #endif /* INTERPROCEDURAL_VIEW */
909 /* Constructs backedge information for irg. In interprocedural view constructs
910 backedges for all methods called by irg, too. */
911 int construct_backedges(ir_graph *irg) {
912 ir_graph *rem = current_ir_graph;
916 assert(!get_interprocedural_view() &&
917 "not implemented, use construct_ip_backedges()");
920 current_ir_graph = irg;
921 outermost_ir_graph = irg;
924 init_scc(irg, &temp);
927 new_loop(); /* sets current_loop */
928 head_rem = current_loop; /* Just for assertion */
930 inc_irg_visited(irg);
932 scc(get_irg_end(irg));
935 obstack_free(&temp, NULL);
937 assert(head_rem == current_loop);
938 mature_loops(current_loop, irg->obst);
939 set_irg_loop(irg, current_loop);
940 set_irg_loopinfo_state(irg, loopinfo_consistent);
941 assert(get_irg_loop(irg)->kind == k_ir_loop);
942 current_ir_graph = rem;
943 return max_loop_depth;
947 #ifdef INTERPROCEDURAL_VIEW
948 int construct_ip_backedges(void) {
949 ir_graph *rem = current_ir_graph;
950 int rem_ipv = get_interprocedural_view();
955 assert(get_irp_ip_view_state() == ip_view_valid);
957 outermost_ir_graph = get_irp_main_irg();
963 new_loop(); /* sets current_loop */
964 set_interprocedural_view(1);
966 inc_max_irg_visited();
967 for (i = 0; i < get_irp_n_irgs(); i++)
968 set_irg_visited(get_irp_irg(i), get_max_irg_visited());
970 /** We have to start the walk at the same nodes as cg_walk. **/
971 /* Walk starting at unreachable procedures. Only these
972 * have End blocks visible in interprocedural view. */
973 for (i = 0; i < get_irp_n_irgs(); i++) {
975 current_ir_graph = get_irp_irg(i);
977 sb = get_irg_start_block(current_ir_graph);
979 if ((get_Block_n_cfgpreds(sb) > 1) ||
980 (get_nodes_block(get_Block_cfgpred(sb, 0)) != sb))
983 scc(get_irg_end(current_ir_graph));
986 /* Check whether we walked all procedures: there could be procedures
987 with cyclic calls but no call from the outside. */
988 for (i = 0; i < get_irp_n_irgs(); i++) {
990 current_ir_graph = get_irp_irg(i);
992 /* Test start block: if inner procedure end and end block are not
993 * visible and therefore not marked. */
994 sb = get_irg_start_block(current_ir_graph);
995 if (get_irn_visited(sb) < get_irg_visited(current_ir_graph)) scc(sb);
998 /* Walk all endless loops in inner procedures.
999 * We recognize an inner procedure if the End node is not visited. */
1000 for (i = 0; i < get_irp_n_irgs(); i++) {
1002 current_ir_graph = get_irp_irg(i);
1004 e = get_irg_end(current_ir_graph);
1005 if (get_irn_visited(e) < get_irg_visited(current_ir_graph)) {
1007 /* Don't visit the End node. */
1008 for (j = 0; j < get_End_n_keepalives(e); j++)
1009 scc(get_End_keepalive(e, j));
1013 set_irg_loop(outermost_ir_graph, current_loop);
1014 set_irg_loopinfo_state(current_ir_graph, loopinfo_ip_consistent);
1015 assert(get_irg_loop(outermost_ir_graph)->kind == k_ir_loop);
1017 obstack_free(&temp, NULL);
1018 current_ir_graph = rem;
1019 set_interprocedural_view(rem_ipv);
1020 return max_loop_depth;
1023 void my_construct_ip_backedges(void) {
1024 ir_graph *rem = current_ir_graph;
1025 int rem_ipv = get_interprocedural_view();
1028 assert(get_irp_ip_view_state() == ip_view_valid);
1030 outermost_ir_graph = get_irp_main_irg();
1034 current_loop = NULL;
1035 new_loop(); /* sets current_loop */
1036 set_interprocedural_view(1);
1038 inc_max_irg_visited();
1039 for (i = 0; i < get_irp_n_irgs(); i++)
1040 set_irg_visited(get_irp_irg(i), get_max_irg_visited());
1042 /** We have to start the walk at the same nodes as cg_walk. **/
1043 /* Walk starting at unreachable procedures. Only these
1044 * have End blocks visible in interprocedural view. */
1045 for (i = 0; i < get_irp_n_irgs(); i++) {
1047 current_ir_graph = get_irp_irg(i);
1049 sb = get_irg_start_block(current_ir_graph);
1051 if ((get_Block_n_cfgpreds(sb) > 1) ||
1052 (get_nodes_block(get_Block_cfgpred(sb, 0)) != sb)) continue;
1054 my_scc(get_irg_end(current_ir_graph));
1057 /* Check whether we walked all procedures: there could be procedures
1058 with cyclic calls but no call from the outside. */
1059 for (i = 0; i < get_irp_n_irgs(); i++) {
1061 current_ir_graph = get_irp_irg(i);
1063 /* Test start block: if inner procedure end and end block are not
1064 * visible and therefore not marked. */
1065 sb = get_irg_start_block(current_ir_graph);
1066 if (get_irn_visited(sb) < get_irg_visited(current_ir_graph))
1070 /* Walk all endless loops in inner procedures.
1071 * We recognize an inner procedure if the End node is not visited. */
1072 for (i = 0; i < get_irp_n_irgs(); i++) {
1074 current_ir_graph = get_irp_irg(i);
1076 e = get_irg_end(current_ir_graph);
1077 if (get_irn_visited(e) < get_irg_visited(current_ir_graph)) {
1079 /* Don't visit the End node. */
1080 for (j = 0; j < get_End_n_keepalives(e); j++) scc(get_End_keepalive(e, j));
1084 set_irg_loop(outermost_ir_graph, current_loop);
1085 set_irg_loopinfo_state(current_ir_graph, loopinfo_ip_consistent);
1086 assert(get_irg_loop(outermost_ir_graph)->kind == k_ir_loop);
1088 current_ir_graph = rem;
1089 set_interprocedural_view(rem_ipv);
1093 static void reset_backedges(ir_node *n) {
1094 if (is_possible_loop_head(n)) {
1095 #ifdef INTERPROCEDURAL_VIEW
1096 int rem = get_interprocedural_view();
1098 set_interprocedural_view(1);
1100 set_interprocedural_view(1);
1102 set_interprocedural_view(rem);
1111 static void loop_reset_backedges(ir_loop *l) {
1113 reset_backedges(get_loop_node(l, 0));
1114 for (i = 0; i < get_loop_n_nodes(l); ++i)
1115 set_irn_loop(get_loop_node(l, i), NULL);
1116 for (i = 0; i < get_loop_n_sons(l); ++i) {
1117 loop_reset_backedges(get_loop_son(l, i));
1122 static void loop_reset_node(ir_node *n, void *env) {
1124 set_irn_loop(n, NULL);
1129 /** Removes all loop information.
1130 Resets all backedges */
1131 void free_loop_information(ir_graph *irg) {
1132 /* We can not use this recursion, as the loop might contain
1133 illegal nodes by now. Why else would we throw away the
1135 if (get_irg_loop(irg)) loop_reset_backedges(get_irg_loop(irg));
1137 irg_walk_graph(irg, loop_reset_node, NULL, NULL);
1138 set_irg_loop(irg, NULL);
1139 set_irg_loopinfo_state(current_ir_graph, loopinfo_none);
1140 /* We cannot free the loop nodes, they are on the obstack. */
1144 void free_all_loop_information(void) {
1146 #ifdef INTERPROCEDURAL_VIEW
1147 int rem = get_interprocedural_view();
1148 set_interprocedural_view(1); /* To visit all filter nodes */
1150 for (i = 0; i < get_irp_n_irgs(); i++) {
1151 free_loop_information(get_irp_irg(i));
1153 #ifdef INTERPROCEDURAL_VIEW
1154 set_interprocedural_view(rem);
1162 /* Debug stuff *************************************************/
1164 static int test_loop_node(ir_loop *l) {
1165 int i, has_node = 0, found_problem = 0;
1168 assert(l && l->kind == k_ir_loop);
1170 if (get_loop_n_elements(l) == 0) {
1172 dump_loop(l, "-ha");
1175 le = get_loop_element(l, 0);
1176 if (*(le.kind) != k_ir_node) {
1177 assert(le.kind && *(le.kind) == k_ir_loop);
1180 dump_loop(l, "-ha");
1183 if ((*(le.kind) == k_ir_node) && !is_possible_loop_head(le.node)) {
1185 dump_loop(l, "-ha");
1188 if ((get_loop_depth(l) != 0) &&
1189 (*(le.kind) == k_ir_node) && !has_backedges(le.node)) {
1191 dump_loop(l, "-ha");
1196 for (i = 0; i < get_loop_n_elements(l); ++i) {
1197 le = get_loop_element(l, i);
1198 if (*(le.kind) == k_ir_node)
1201 if (test_loop_node(le.son)) found_problem = 1;
1204 if (has_node == 0) {
1206 dump_loop(l, "-ha");
1209 return found_problem;
1212 /** Prints all loop nodes that
1213 * - do not have any firm nodes, only loop sons
1214 * - the header is not a Phi, Block or Filter.
1216 void find_strange_loop_nodes(ir_loop *l) {
1217 int found_problem = 0;
1218 found_problem = test_loop_node(l);
1219 printf("Finished Test\n\n");
1220 if (found_problem) exit(0);
1224 /* ------------------------------------------------------------------- */
1225 /* Simple analyses based on the loop information */
1226 /* ------------------------------------------------------------------- */
1228 int is_loop_variant(ir_loop *l, ir_loop *b) {
1231 if (l == b) return 1;
1233 n_elems = get_loop_n_elements(l);
1234 for (i = 0; i < n_elems; ++i) {
1235 loop_element e = get_loop_element(l, i);
1236 if (is_ir_loop(e.kind))
1237 if (is_loop_variant(e.son, b))
1244 /* Test whether a value is loop invariant.
1246 * @param n The node to be tested.
1247 * @param block A block node. We pass the block, not the loop as we must
1248 * start off with a block loop to find all proper uses.
1250 * Returns non-zero, if the node n is not changed in the loop block
1251 * belongs to or in inner loops of this blocks loop. */
1252 int is_loop_invariant(const ir_node *n, const ir_node *block) {
1253 ir_loop *l = get_irn_loop(block);
1254 const ir_node *b = is_Block(n) ? n : get_nodes_block(n);
1255 return !is_loop_variant(l, get_irn_loop(b));