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
44 #include "irgraph_t.h"
51 /* A variant of the loop tree that avoids loops without head.
52 This reduces the depth of the loop tree. */
53 #define NO_LOOPS_WITHOUT_HEAD 1
55 /** The outermost graph the scc is computed for. */
56 static ir_graph *outermost_ir_graph;
57 /** Current loop construction is working on. */
58 static ir_loop *current_loop;
59 /** Counts the number of allocated loop nodes.
60 * Each loop node gets a unique number.
61 * @todo What for? ev. remove.
63 static int loop_node_cnt = 0;
64 /** Counter to generate depth first numbering of visited nodes. */
65 static int current_dfn = 1;
67 static int max_loop_depth = 0;
69 void link_to_reg_end(ir_node *n, void *env);
70 void set_projx_link(ir_node *cb_projx, ir_node *end_projx);
71 ir_node *get_projx_link(ir_node *cb_projx);
73 /**********************************************************************/
74 /* Node attributes **/
75 /**********************************************************************/
77 /**********************************************************************/
78 /* Node attributes needed for the construction. **/
79 /**********************************************************************/
81 typedef struct scc_info {
82 int in_stack; /**< Marks whether node is on the stack. */
83 int dfn; /**< Depth first search number. */
84 int uplink; /**< dfn number of ancestor. */
85 /* ir_loop *loop; *//* Refers to the containing loop. */
87 struct section *section;
94 * Allocates a new SCC info on the given obstack.
96 static INLINE scc_info *new_scc_info(struct obstack *obst) {
97 scc_info *info = obstack_alloc(obst, sizeof(*info));
98 memset(info, 0, sizeof(*info));
103 * Mark node n being on the SCC stack.
105 static INLINE void mark_irn_in_stack(ir_node *n) {
106 scc_info *scc = get_irn_link(n);
112 * Mark node n NOT being on the SCC stack.
114 static INLINE void mark_irn_not_in_stack(ir_node *n) {
115 scc_info *scc = get_irn_link(n);
121 * Checks if a node is on the SCC stack.
123 static INLINE int irn_is_in_stack(ir_node *n) {
124 scc_info *scc = get_irn_link(n);
126 return scc->in_stack;
130 * Sets the uplink number for a node.
132 static INLINE void set_irn_uplink(ir_node *n, int uplink) {
133 scc_info *scc = get_irn_link(n);
135 scc->uplink = uplink;
139 * Returns the uplink number for a node.
141 static int get_irn_uplink(ir_node *n) {
142 scc_info *scc = get_irn_link(n);
148 * Sets the depth-first-search number for a node.
150 static INLINE void set_irn_dfn(ir_node *n, int dfn) {
151 scc_info *scc = get_irn_link(n);
157 * Returns the depth-first-search number of a node.
159 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) {
170 /* Test whether n is contained in this loop. */
171 for (i = 0; i < get_loop_n_nodes(l); i++)
172 if (n == get_loop_node(l, i)) return l;
174 /* Is this a leave in the loop tree? If so loop not found. */
175 if (get_loop_n_sons(l) == 0) return NULL;
177 /* Else descend in the loop tree. */
178 for (i = 0; i < get_loop_n_sons(l); i++) {
179 res = find_nodes_loop(n, get_loop_son(l, i));
185 /* @@@ temporary implementation, costly!!! */
186 ir_loop * get_irn_loop(ir_node *n) {
187 ir_loop *l = get_irg_loop(current_ir_graph);
188 l = find_nodes_loop(n, l);
193 /**********************************************************************/
195 /**********************************************************************/
197 static ir_node **stack = NULL;
198 static int tos = 0; /* top of stack */
201 * initializes the stack
203 static INLINE void init_stack(void) {
205 ARR_RESIZE(ir_node *, stack, 1000);
207 stack = NEW_ARR_F(ir_node *, 1000);
215 static void finish_stack(void) {
221 * push a node onto the stack
223 * @param n The node to push
225 static INLINE void push(ir_node *n) {
226 if (tos == ARR_LEN(stack)) {
227 int nlen = ARR_LEN(stack) * 2;
228 ARR_RESIZE(ir_node *, stack, nlen);
231 mark_irn_in_stack(n);
235 * pop a node from the stack
237 * @return The topmost node
239 static INLINE ir_node *pop(void) {
240 ir_node *n = stack[--tos];
241 mark_irn_not_in_stack(n);
246 * The nodes up to n belong to the current loop.
247 * Removes them from the stack and adds them to the current loop.
249 static INLINE void pop_scc_to_loop(ir_node *n) {
257 set_irn_dfn(m, loop_node_cnt);
258 add_loop_node(current_loop, m);
259 set_irn_loop(m, current_loop);
263 /* i might be bigger than 1 for dead (and that's why bad) loops */
265 printf("Mehr als eine Iteration!!!!!!!!!!!!!!!!!!!!!!!!!!!!11111\n");
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) {
273 int last = get_loop_n_elements(l) - 1;
274 loop_element lelement = get_loop_element(l, last);
275 ir_loop *last_son = lelement.son;
277 if (get_kind(last_son) == k_ir_loop &&
278 get_loop_n_elements(last_son) == 1) {
281 lelement = get_loop_element(last_son, 0);
284 if (get_kind(gson) == k_ir_loop) {
285 loop_element new_last_son;
287 gson->outer_loop = l;
288 new_last_son.son = gson;
289 l->children[last] = new_last_son;
296 /* Removes and unmarks all nodes up to n from the stack.
297 The nodes must be visited once more to assign them to a scc. */
298 static INLINE void pop_scc_unmark_visit(ir_node *n) {
303 set_irn_visited(m, 0);
307 /**********************************************************************/
308 /* The loop datastructure. **/
309 /**********************************************************************/
311 /* Allocates a new loop as son of current_loop. Sets current_loop
312 to the new loop and returns the father. */
313 static ir_loop *new_loop(void) {
314 ir_loop *father = current_loop;
315 ir_loop *son = alloc_loop(father, outermost_ir_graph->obst);
317 if (son->depth > max_loop_depth) max_loop_depth = son->depth;
322 /**********************************************************************/
323 /* Constructing and destructing the loop/backedge information. **/
324 /**********************************************************************/
326 /* Initialization steps. **********************************************/
328 static INLINE void init_node(ir_node *n, void *env) {
329 struct obstack *obst = env;
330 set_irn_link(n, new_scc_info(obst));
334 static INLINE void init_scc_common(void) {
340 static INLINE void init_scc(ir_graph *irg, struct obstack *obst) {
342 irg_walk_graph(irg, init_node, NULL, obst);
344 irg_walk (irg, link_to_reg_end, NULL, NULL);
348 static INLINE void finish_scc(void)
353 #ifdef INTERPROCEDURAL_VIEW
354 static INLINE void init_ip_scc(struct obstack *obst) {
356 cg_walk(init_node, NULL, obst);
358 #if EXPERIMENTAL_LOOP_TREE
359 cg_walk(link_to_reg_end, NULL, NULL);
365 * Check weather a given node represents the outer most Start
366 * block. In intra-procedural view this is the start block of the
367 * current graph, in interprocedural view it is the start block
368 * of the outer most graph.
370 * @param n the node to check
372 * This is the condition for breaking the scc recursion.
374 static int is_outermost_Start(ir_node *n) {
375 /* Test whether this is the outermost Start node. */
376 if (is_Block(n) && get_Block_n_cfgpreds(n) == 1) {
377 ir_node *pred = skip_Proj(get_Block_cfgpred(n, 0));
378 if (is_Start(pred) && get_nodes_block(pred) == n)
384 /* When to walk from nodes to blocks. Only for Control flow operations? */
385 static INLINE int get_start_index(ir_node *n) {
386 #undef BLOCK_BEFORE_NODE
387 #define BLOCK_BEFORE_NODE 1
389 #if BLOCK_BEFORE_NODE
391 /* This version assures, that all nodes are ordered absolutely. This allows
392 to undef all nodes in the heap analysis if the block is false, which means
394 I.e., with this code, the order on the loop tree is correct. But a (single)
395 test showed the loop tree is deeper. */
396 if (get_irn_op(n) == op_Phi ||
398 (is_Filter(n) && get_interprocedural_view()) || (
399 get_irg_pinned(get_irn_irg(n)) == op_pin_state_floats &&
400 get_irn_pinned(n) == op_pin_state_floats
402 // Here we could test for backedge at -1 which is illegal
409 /* This version causes deeper loop trees (at least we verified this
411 But it guarantees that Blocks are analysed before nodes contained in the
412 block. If so, we can set the value to undef if the block is not \
414 if (is_cfop(n) || is_fragile_op(n) || is_Start(n))
423 * Return non-zero if the given node is a legal loop header:
424 * Block, Phi, Filter.
426 * @param n the node to check
428 static INLINE int is_possible_loop_head(ir_node *n) {
429 ir_op *op = get_irn_op(n);
430 return ((op == op_Block) ||
432 ((op == op_Filter) && get_interprocedural_view()));
436 * Returns non-zero if n is a loop header, i.e., it is a Block, Phi
437 * or Filter node and has predecessors within the loop and out
440 * @param n the node to check
441 * @param root only needed for assertion.
443 static int is_head(ir_node *n, ir_node *root) {
445 int some_outof_loop = 0, some_in_loop = 0;
447 /* Test for legal loop header: Block, Phi, ... */
448 if (!is_possible_loop_head(n))
451 if (!is_outermost_Start(n)) {
453 int uplink = get_irn_uplink(root);
457 arity = get_irn_arity(n);
458 for (i = get_start_index(n); i < arity; i++) {
460 if (is_backedge(n, i))
462 pred = get_irn_n(n, i);
463 if (! irn_is_in_stack(pred)) {
466 assert(get_irn_uplink(pred) >= uplink);
471 return some_outof_loop & some_in_loop;
475 * Returns non-zero if n is possible loop head of an endless loop.
476 * I.e., it is a Block, Phi or Filter node and has only predecessors
479 * @param n the node to check
480 * @param root only needed for assertion.
482 static int is_endless_head(ir_node *n, ir_node *root) {
484 int none_outof_loop = 1, some_in_loop = 0;
486 /* Test for legal loop header: Block, Phi, ... */
487 if (!is_possible_loop_head(n))
490 if (!is_outermost_Start(n)) {
492 int uplink = get_irn_uplink(root);
496 arity = get_irn_arity(n);
497 for (i = get_start_index(n); i < arity; i++) {
499 if (is_backedge(n, i))
501 pred = get_irn_n(n, i);
502 if (!irn_is_in_stack(pred)) {
505 assert(get_irn_uplink(pred) >= uplink);
510 return none_outof_loop & some_in_loop;
513 /** Returns index of the predecessor with the smallest dfn number
514 greater-equal than limit. */
515 static int smallest_dfn_pred(ir_node *n, int limit) {
516 int i, index = -2, min = -1;
518 if (!is_outermost_Start(n)) {
519 int arity = get_irn_arity(n);
520 for (i = get_start_index(n); i < arity; i++) {
521 ir_node *pred = get_irn_n(n, i);
522 if (is_backedge(n, i) || !irn_is_in_stack(pred))
524 if (get_irn_dfn(pred) >= limit && (min == -1 || get_irn_dfn(pred) < min)) {
526 min = get_irn_dfn(pred);
534 * Returns index of the predecessor with the largest dfn number.
536 static int largest_dfn_pred(ir_node *n) {
537 int i, index = -2, max = -1;
539 if (!is_outermost_Start(n)) {
540 int arity = get_irn_arity(n);
541 for (i = get_start_index(n); i < arity; i++) {
542 ir_node *pred = get_irn_n(n, i);
543 if (is_backedge (n, i) || !irn_is_in_stack(pred))
545 if (get_irn_dfn(pred) > max) {
547 max = get_irn_dfn(pred);
555 * Searches the stack for possible loop heads. Tests these for backedges.
556 * If it finds a head with an unmarked backedge it marks this edge and
557 * returns the tail of the loop.
558 * If it finds no backedge returns NULL.
559 * ("disable_backedge" in fiasco)
561 * @param n A node where uplink == dfn.
563 static ir_node *find_tail(ir_node *n) {
565 int i, res_index = -2;
568 if (!icfg && rm_cyclic_phis && remove_cyclic_phis (n)) return NULL;
570 m = stack[tos-1]; /* tos = top of stack */
572 res_index = smallest_dfn_pred(m, 0);
573 if ((res_index == -2) && /* no smallest dfn pred found. */
577 if (m == n) return NULL; // Is this to catch Phi - self loops?
578 for (i = tos-2; i >= 0; --i) {
582 res_index = smallest_dfn_pred(m, get_irn_dfn(m) + 1);
583 if (res_index == -2) /* no smallest dfn pred found. */
584 res_index = largest_dfn_pred(m);
586 if ((m == n) && (res_index == -2)) { /* don't walk past loop head. */
592 /* We should not walk past our selves on the stack: The upcoming nodes
593 are not in this loop. We assume a loop not reachable from Start. */
601 /* A dead loop not reachable from Start. */
602 for (i = tos-2; i >= 0; --i) {
604 if (is_endless_head(m, n)) {
605 res_index = smallest_dfn_pred(m, get_irn_dfn(m) + 1);
606 if (res_index == -2) /* no smallest dfn pred found. */
607 res_index = largest_dfn_pred (m);
610 if (m == n) { break; } /* It's not an unreachable loop, either. */
612 //assert(0 && "no head found on stack");
616 if (res_index <= -2) {
617 /* It's a completely bad loop: without Phi/Block nodes that can
618 be a head. I.e., the code is "dying". We break the loop by
619 setting Bad nodes. */
620 int arity = get_irn_arity(n);
621 ir_node *bad = get_irg_bad(get_irn_irg(n));
622 for (i = -1; i < arity; ++i) {
623 set_irn_n(n, i, bad);
627 assert(res_index > -2);
629 set_backedge(m, res_index);
630 return is_outermost_Start(n) ? NULL : get_irn_n(m, res_index);
634 #if EXPERIMENTAL_LOOP_TREE
636 /* ----------------------------------------------------------------
637 AS: This is experimental code to build loop trees suitable for
638 the heap analysis. Does not work correctly right now... :-(
641 Search in stack for the corresponding first Call-End-ProjX that
642 corresponds to one of the control flow predecessors of the given
643 block, that is the possible callers.
644 returns: the control predecessor to chose\
645 or -1 if no corresponding Call-End-Node could be found
647 - -------------------------------------------------------------- */
649 int search_endproj_in_stack(ir_node *start_block) {
651 assert(is_Block(start_block));
652 for(i = tos - 1; i >= 0; --i)
654 if(get_irn_op(stack[i]) == op_Proj && get_irn_mode(stack[i]) == mode_X &&
655 get_irn_op(get_irn_n(stack[i], 0)) == op_EndReg)
657 printf("FOUND PROJ!!!!!!!!!!!!!!!!!!!!!!!!!!\n");
658 ir_node *end_projx = stack[i];
660 int arity = get_irn_arity(start_block);
661 for(j = 0; j < arity; j++)
663 ir_node *begin_projx = get_Block_cfgpred(get_irg_start_block(get_irn_irg(end_projx)),
664 get_Proj_proj(end_projx));
665 if(get_irn_n(start_block, j) == begin_projx)
667 printf("FOUND IT!!!!!!!!!!!!!!!!!!\n");
677 static pmap *projx_link = NULL;
679 void link_to_reg_end (ir_node *n, void *env) {
680 if(get_irn_op(n) == op_Proj &&
681 get_irn_mode(n) == mode_X &&
682 get_irn_op(get_irn_n(n, 0)) == op_EndReg) {
683 /* Reg End Projx -> Find the CallBegin Projx and hash it */
684 ir_node *end_projx = n;
685 ir_node *begin_projx = get_Block_cfgpred(get_irg_start_block(get_irn_irg(end_projx)),
686 get_Proj_proj(end_projx));
687 set_projx_link(begin_projx, end_projx);
691 void set_projx_link(ir_node *cb_projx, ir_node *end_projx) {
692 if(projx_link == NULL)
693 projx_link = pmap_create();
694 pmap_insert(projx_link, (void *)cb_projx, (void *)end_projx);
697 ir_node *get_projx_link(ir_node *cb_projx) {
698 return((ir_node *) pmap_get(projx_link, (void *)cb_projx));
703 static INLINE int is_outermost_loop(ir_loop *l) {
704 return l == get_loop_outer_loop(l);
708 /*-----------------------------------------------------------*
709 * The core algorithm. *
710 *-----------------------------------------------------------*/
713 * The core algorithm: Find strongly coupled components.
715 * @param n node to start
717 static void scc(ir_node *n) {
722 /* Initialize the node */
723 set_irn_dfn(n, current_dfn); /* Depth first number for this node */
724 set_irn_uplink(n, current_dfn); /* ... is default uplink. */
725 set_irn_loop(n, NULL);
729 /* AS: get_start_index might return -1 for Control Flow Nodes, and thus a negative
730 array index would be passed to is_backedge(). But CFG Nodes dont't have a backedge array,
731 so is_backedge does not access array[-1] but correctly returns false! */
733 if (!is_outermost_Start(n)) {
734 int i, arity = get_irn_arity(n);
736 for (i = get_start_index(n); i < arity; ++i) {
738 if (is_backedge(n, i))
742 if (irn_is_in_stack(m)) {
743 /* Uplink of m is smaller if n->m is a backedge.
744 Propagate the uplink to mark the loop. */
745 if (get_irn_uplink(m) < get_irn_uplink(n))
746 set_irn_uplink(n, get_irn_uplink(m));
751 if (get_irn_dfn(n) == get_irn_uplink(n)) {
752 /* This condition holds for
753 1) the node with the incoming backedge.
754 That is: We found a loop!
755 2) Straight line code, because no uplink has been propagated, so the
756 uplink still is the same as the dfn.
758 But n might not be a proper loop head for the analysis. Proper loop
759 heads are Block and Phi nodes. find_tail() searches the stack for
760 Block's and Phi's and takes those nodes as loop heads for the current
761 loop instead and marks the incoming edge as backedge. */
763 ir_node *tail = find_tail(n);
765 /* We have a loop, that is no straight line code,
766 because we found a loop head!
767 Next actions: Open a new loop on the loop tree and
768 try to find inner loops */
770 #if NO_LOOPS_WITHOUT_HEAD
771 /* This is an adaption of the algorithm from fiasco / optscc to
772 * avoid loops without Block or Phi as first node. This should
773 * severely reduce the number of evaluations of nodes to detect
774 * a fixpoint in the heap analysis.
775 * Further it avoids loops without firm nodes that cause errors
776 * in the heap analyses.
777 * But attention: don't do it for the outermost loop: This loop
778 * is not iterated. A first block can be a loop head in case of
779 * an endless recursion. */
783 if ((get_loop_n_elements(current_loop) > 0) || (is_outermost_loop(current_loop))) {
791 ir_loop *l = new_loop();
794 /* Remove the loop from the stack ... */
795 pop_scc_unmark_visit(n);
797 /* The current backedge has been marked, that is temporarily eliminated,
798 by find tail. Start the scc algorithm
799 again on the subgraph that is left (the current loop without the backedge)
800 in order to find more inner loops. */
803 assert(irn_visited(n));
804 #if NO_LOOPS_WITHOUT_HEAD
809 /* No loop head was found, that is we have straight line code.
810 Pop all nodes from the stack to the current loop. */
816 #ifdef INTERPROCEDURAL_VIEW
817 static void my_scc(ir_node *n) {
823 /* Initialize the node */
824 set_irn_dfn(n, current_dfn); /* Depth first number for this node */
825 set_irn_uplink(n, current_dfn); /* ... is default uplink. */
826 set_irn_loop(n, NULL);
830 /* AS: get_start_index might return -1 for Control Flow Nodes, and thus a negative
831 array index would be passed to is_backedge(). But CFG Nodes dont't have a backedge array,
832 so is_backedge does not access array[-1] but correctly returns false! */
834 if (!is_outermost_Start(n)) {
835 int arity = get_irn_arity(n);
837 for (i = get_start_index(n); i < arity; i++) {
839 if (is_backedge(n, i)) continue;
840 m = get_irn_n(n, i); /* get_irn_ip_pred(n, i); */
841 /* if (!m || is_Unknown(m)) continue; */
843 if (irn_is_in_stack(m)) {
844 /* Uplink of m is smaller if n->m is a backedge.
845 Propagate the uplink to mark the loop. */
846 if (get_irn_uplink(m) < get_irn_uplink(n))
847 set_irn_uplink(n, get_irn_uplink(m));
852 if (get_irn_dfn(n) == get_irn_uplink(n)) {
853 /* This condition holds for
854 1) the node with the incoming backedge.
855 That is: We found a loop!
856 2) Straight line code, because no uplink has been propagated, so the
857 uplink still is the same as the dfn.
859 But n might not be a proper loop head for the analysis. Proper loop
860 heads are Block and Phi nodes. find_tail searches the stack for
861 Block's and Phi's and takes those nodes as loop heads for the current
862 loop instead and marks the incoming edge as backedge. */
864 ir_node *tail = find_tail(n);
866 /* We have a loop, that is no straight line code,
867 because we found a loop head!
868 Next actions: Open a new loop on the loop tree and
869 try to find inner loops */
871 #if NO_LOOPS_WITHOUT_HEAD
872 /* This is an adaption of the algorithm from fiasco / optscc to
873 * avoid loops without Block or Phi as first node. This should
874 * severely reduce the number of evaluations of nodes to detect
875 * a fixpoint in the heap analysis.
876 * Further it avoids loops without firm nodes that cause errors
877 * in the heap analyses. */
881 if ((get_loop_n_elements(current_loop) > 0) || (is_outermost_loop(current_loop))) {
889 ir_loop *l = new_loop();
892 /* Remove the loop from the stack ... */
893 pop_scc_unmark_visit(n);
895 /* The current backedge has been marked, that is temporarily eliminated,
896 by find tail. Start the scc algorithm
897 anew on the subgraph that is left (the current loop without the backedge)
898 in order to find more inner loops. */
901 assert(irn_visited(n));
902 #if NO_LOOPS_WITHOUT_HEAD
907 /* No loop head was found, that is we have straightline code.
908 Pop all nodes from the stack to the current loop. */
913 #endif /* INTERPROCEDURAL_VIEW */
915 /* Constructs backedge information for irg. In interprocedural view constructs
916 backedges for all methods called by irg, too. */
917 int construct_backedges(ir_graph *irg) {
918 ir_graph *rem = current_ir_graph;
922 assert(!get_interprocedural_view() &&
923 "not implemented, use construct_ip_backedges()");
926 current_ir_graph = irg;
927 outermost_ir_graph = irg;
930 init_scc(irg, &temp);
933 new_loop(); /* sets current_loop */
934 head_rem = current_loop; /* Just for assertion */
936 inc_irg_visited(irg);
938 scc(get_irg_end(irg));
941 obstack_free(&temp, NULL);
943 assert(head_rem == current_loop);
944 mature_loops(current_loop, irg->obst);
945 set_irg_loop(irg, current_loop);
946 set_irg_loopinfo_state(irg, loopinfo_consistent);
947 assert(get_irg_loop(irg)->kind == k_ir_loop);
948 current_ir_graph = rem;
949 return max_loop_depth;
953 #ifdef INTERPROCEDURAL_VIEW
954 int construct_ip_backedges(void) {
955 ir_graph *rem = current_ir_graph;
956 int rem_ipv = get_interprocedural_view();
961 assert(get_irp_ip_view_state() == ip_view_valid);
963 outermost_ir_graph = get_irp_main_irg();
969 new_loop(); /* sets current_loop */
970 set_interprocedural_view(1);
972 inc_max_irg_visited();
973 for (i = 0; i < get_irp_n_irgs(); i++)
974 set_irg_visited(get_irp_irg(i), get_max_irg_visited());
976 /** We have to start the walk at the same nodes as cg_walk. **/
977 /* Walk starting at unreachable procedures. Only these
978 * have End blocks visible in interprocedural view. */
979 for (i = 0; i < get_irp_n_irgs(); i++) {
981 current_ir_graph = get_irp_irg(i);
983 sb = get_irg_start_block(current_ir_graph);
985 if ((get_Block_n_cfgpreds(sb) > 1) ||
986 (get_nodes_block(get_Block_cfgpred(sb, 0)) != sb))
989 scc(get_irg_end(current_ir_graph));
992 /* Check whether we walked all procedures: there could be procedures
993 with cyclic calls but no call from the outside. */
994 for (i = 0; i < get_irp_n_irgs(); i++) {
996 current_ir_graph = get_irp_irg(i);
998 /* Test start block: if inner procedure end and end block are not
999 * visible and therefore not marked. */
1000 sb = get_irg_start_block(current_ir_graph);
1001 if (get_irn_visited(sb) < get_irg_visited(current_ir_graph)) scc(sb);
1004 /* Walk all endless loops in inner procedures.
1005 * We recognize an inner procedure if the End node is not visited. */
1006 for (i = 0; i < get_irp_n_irgs(); i++) {
1008 current_ir_graph = get_irp_irg(i);
1010 e = get_irg_end(current_ir_graph);
1011 if (get_irn_visited(e) < get_irg_visited(current_ir_graph)) {
1013 /* Don't visit the End node. */
1014 for (j = 0; j < get_End_n_keepalives(e); j++)
1015 scc(get_End_keepalive(e, j));
1019 set_irg_loop(outermost_ir_graph, current_loop);
1020 set_irg_loopinfo_state(current_ir_graph, loopinfo_ip_consistent);
1021 assert(get_irg_loop(outermost_ir_graph)->kind == k_ir_loop);
1023 obstack_free(&temp, NULL);
1024 current_ir_graph = rem;
1025 set_interprocedural_view(rem_ipv);
1026 return max_loop_depth;
1029 void my_construct_ip_backedges(void) {
1030 ir_graph *rem = current_ir_graph;
1031 int rem_ipv = get_interprocedural_view();
1034 assert(get_irp_ip_view_state() == ip_view_valid);
1036 outermost_ir_graph = get_irp_main_irg();
1040 current_loop = NULL;
1041 new_loop(); /* sets current_loop */
1042 set_interprocedural_view(1);
1044 inc_max_irg_visited();
1045 for (i = 0; i < get_irp_n_irgs(); i++)
1046 set_irg_visited(get_irp_irg(i), get_max_irg_visited());
1048 /** We have to start the walk at the same nodes as cg_walk. **/
1049 /* Walk starting at unreachable procedures. Only these
1050 * have End blocks visible in interprocedural view. */
1051 for (i = 0; i < get_irp_n_irgs(); i++) {
1053 current_ir_graph = get_irp_irg(i);
1055 sb = get_irg_start_block(current_ir_graph);
1057 if ((get_Block_n_cfgpreds(sb) > 1) ||
1058 (get_nodes_block(get_Block_cfgpred(sb, 0)) != sb)) continue;
1060 my_scc(get_irg_end(current_ir_graph));
1063 /* Check whether we walked all procedures: there could be procedures
1064 with cyclic calls but no call from the outside. */
1065 for (i = 0; i < get_irp_n_irgs(); i++) {
1067 current_ir_graph = get_irp_irg(i);
1069 /* Test start block: if inner procedure end and end block are not
1070 * visible and therefore not marked. */
1071 sb = get_irg_start_block(current_ir_graph);
1072 if (get_irn_visited(sb) < get_irg_visited(current_ir_graph))
1076 /* Walk all endless loops in inner procedures.
1077 * We recognize an inner procedure if the End node is not visited. */
1078 for (i = 0; i < get_irp_n_irgs(); i++) {
1080 current_ir_graph = get_irp_irg(i);
1082 e = get_irg_end(current_ir_graph);
1083 if (get_irn_visited(e) < get_irg_visited(current_ir_graph)) {
1085 /* Don't visit the End node. */
1086 for (j = 0; j < get_End_n_keepalives(e); j++) scc(get_End_keepalive(e, j));
1090 set_irg_loop(outermost_ir_graph, current_loop);
1091 set_irg_loopinfo_state(current_ir_graph, loopinfo_ip_consistent);
1092 assert(get_irg_loop(outermost_ir_graph)->kind == k_ir_loop);
1094 current_ir_graph = rem;
1095 set_interprocedural_view(rem_ipv);
1099 static void reset_backedges(ir_node *n) {
1100 if (is_possible_loop_head(n)) {
1101 #ifdef INTERPROCEDURAL_VIEW
1102 int rem = get_interprocedural_view();
1104 set_interprocedural_view(1);
1106 set_interprocedural_view(1);
1108 set_interprocedural_view(rem);
1117 static void loop_reset_backedges(ir_loop *l) {
1119 reset_backedges(get_loop_node(l, 0));
1120 for (i = 0; i < get_loop_n_nodes(l); ++i)
1121 set_irn_loop(get_loop_node(l, i), NULL);
1122 for (i = 0; i < get_loop_n_sons(l); ++i) {
1123 loop_reset_backedges(get_loop_son(l, i));
1128 static void loop_reset_node(ir_node *n, void *env) {
1130 set_irn_loop(n, NULL);
1135 /** Removes all loop information.
1136 Resets all backedges */
1137 void free_loop_information(ir_graph *irg) {
1138 /* We can not use this recursion, as the loop might contain
1139 illegal nodes by now. Why else would we throw away the
1141 if (get_irg_loop(irg)) loop_reset_backedges(get_irg_loop(irg));
1143 irg_walk_graph(irg, loop_reset_node, NULL, NULL);
1144 set_irg_loop(irg, NULL);
1145 set_irg_loopinfo_state(current_ir_graph, loopinfo_none);
1146 /* We cannot free the loop nodes, they are on the obstack. */
1150 void free_all_loop_information(void) {
1152 #ifdef INTERPROCEDURAL_VIEW
1153 int rem = get_interprocedural_view();
1154 set_interprocedural_view(1); /* To visit all filter nodes */
1156 for (i = 0; i < get_irp_n_irgs(); i++) {
1157 free_loop_information(get_irp_irg(i));
1159 #ifdef INTERPROCEDURAL_VIEW
1160 set_interprocedural_view(rem);
1168 /* Debug stuff *************************************************/
1170 static int test_loop_node(ir_loop *l) {
1171 int i, has_node = 0, found_problem = 0;
1174 assert(l && l->kind == k_ir_loop);
1176 if (get_loop_n_elements(l) == 0) {
1178 dump_loop(l, "-ha");
1181 le = get_loop_element(l, 0);
1182 if (*(le.kind) != k_ir_node) {
1183 assert(le.kind && *(le.kind) == k_ir_loop);
1186 dump_loop(l, "-ha");
1189 if ((*(le.kind) == k_ir_node) && !is_possible_loop_head(le.node)) {
1191 dump_loop(l, "-ha");
1194 if ((get_loop_depth(l) != 0) &&
1195 (*(le.kind) == k_ir_node) && !has_backedges(le.node)) {
1197 dump_loop(l, "-ha");
1202 for (i = 0; i < get_loop_n_elements(l); ++i) {
1203 le = get_loop_element(l, i);
1204 if (*(le.kind) == k_ir_node)
1207 if (test_loop_node(le.son)) found_problem = 1;
1210 if (has_node == 0) {
1212 dump_loop(l, "-ha");
1215 return found_problem;
1218 /** Prints all loop nodes that
1219 * - do not have any firm nodes, only loop sons
1220 * - the header is not a Phi, Block or Filter.
1222 void find_strange_loop_nodes(ir_loop *l) {
1223 int found_problem = 0;
1224 found_problem = test_loop_node(l);
1225 printf("Finished Test\n\n");
1226 if (found_problem) exit(0);
1230 /* ------------------------------------------------------------------- */
1231 /* Simple analyses based on the loop information */
1232 /* ------------------------------------------------------------------- */
1234 int is_loop_variant(ir_loop *l, ir_loop *b) {
1237 if (l == b) return 1;
1239 n_elems = get_loop_n_elements(l);
1240 for (i = 0; i < n_elems; ++i) {
1241 loop_element e = get_loop_element(l, i);
1242 if (is_ir_loop(e.kind))
1243 if (is_loop_variant(e.son, b))
1250 /* Test whether a value is loop invariant.
1252 * @param n The node to be tested.
1253 * @param block A block node. We pass the block, not the loop as we must
1254 * start off with a block loop to find all proper uses.
1256 * Returns non-zero, if the node n is not changed in the loop block
1257 * belongs to or in inner loops of this blocks loop. */
1258 int is_loop_invariant(const ir_node *n, const ir_node *block) {
1259 ir_loop *l = get_irn_loop(block);
1260 const ir_node *b = is_Block(n) ? n : get_nodes_block(n);
1261 return !is_loop_variant(l, get_irn_loop(b));