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);
216 static INLINE void free_stack(void) {
226 * push a node onto the stack
228 * @param n The node to push
230 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) {
245 ir_node *n = stack[--tos];
246 mark_irn_not_in_stack(n);
251 * The nodes up to n belong to the current loop.
252 * Removes them from the stack and adds them to the current loop.
254 static INLINE void pop_scc_to_loop(ir_node *n) {
262 set_irn_dfn(m, loop_node_cnt);
263 add_loop_node(current_loop, m);
264 set_irn_loop(m, current_loop);
268 /* i might be bigger than 1 for dead (and that's why bad) loops */
270 printf("Mehr als eine Iteration!!!!!!!!!!!!!!!!!!!!!!!!!!!!11111\n");
274 /* GL ??? my last son is my grandson??? Removes loops with no
275 ir_nodes in them. Such loops have only another loop as son. (Why
276 can't they have two loops as sons? Does it never get that far? ) */
277 static void close_loop(ir_loop *l) {
278 int last = get_loop_n_elements(l) - 1;
279 loop_element lelement = get_loop_element(l, last);
280 ir_loop *last_son = lelement.son;
282 if (get_kind(last_son) == k_ir_loop &&
283 get_loop_n_elements(last_son) == 1) {
286 lelement = get_loop_element(last_son, 0);
289 if (get_kind(gson) == k_ir_loop) {
290 loop_element new_last_son;
292 gson->outer_loop = l;
293 new_last_son.son = gson;
294 l->children[last] = new_last_son;
301 /* Removes and unmarks all nodes up to n from the stack.
302 The nodes must be visited once more to assign them to a scc. */
303 static INLINE void pop_scc_unmark_visit(ir_node *n) {
308 set_irn_visited(m, 0);
312 /**********************************************************************/
313 /* The loop datastructure. **/
314 /**********************************************************************/
316 /* Allocates a new loop as son of current_loop. Sets current_loop
317 to the new loop and returns the father. */
318 static ir_loop *new_loop(void) {
319 ir_loop *father = current_loop;
320 ir_loop *son = alloc_loop(father, outermost_ir_graph->obst);
322 if (son->depth > max_loop_depth) max_loop_depth = son->depth;
327 /**********************************************************************/
328 /* Constructing and destructing the loop/backedge information. **/
329 /**********************************************************************/
331 /* Initialization steps. **********************************************/
333 static INLINE void init_node(ir_node *n, void *env) {
334 struct obstack *obst = env;
335 set_irn_link(n, new_scc_info(obst));
339 static INLINE void init_scc_common(void) {
345 static INLINE void init_scc(ir_graph *irg, struct obstack *obst) {
347 irg_walk_graph(irg, init_node, NULL, obst);
349 irg_walk (irg, link_to_reg_end, NULL, NULL);
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);
364 /* Condition for breaking the recursion. */
365 static int is_outermost_Start(ir_node *n) {
366 /* Test whether this is the outermost Start node. If so
367 recursion must end. */
368 if ((get_irn_op(n) == op_Block) &&
369 (get_Block_n_cfgpreds(n) == 1) &&
370 (get_irn_op(skip_Proj(get_Block_cfgpred(n, 0))) == op_Start) &&
371 (get_nodes_block(skip_Proj(get_Block_cfgpred(n, 0))) == n)) {
375 /* @@@ Bad condition:
376 not possible in interprocedural view as outermost_graph is
377 not necessarily the only with a dead-end start block.
378 Besides current_ir_graph is not set properly. */
379 if ((get_irn_op(n) == op_Block) &&
380 (n == get_irg_start_block(current_ir_graph))) {
381 if ((!get_interprocedural_view()) ||
382 (current_ir_graph == outermost_ir_graph))
389 /* When to walk from nodes to blocks. Only for Control flow operations? */
390 static INLINE int get_start_index(ir_node *n) {
391 #undef BLOCK_BEFORE_NODE
392 #define BLOCK_BEFORE_NODE 1
394 #if BLOCK_BEFORE_NODE
396 /* This version assures, that all nodes are ordered absolutely. This allows
397 to undef all nodes in the heap analysis if the block is false, which means
399 I.e., with this code, the order on the loop tree is correct. But a (single)
400 test showed the loop tree is deeper. */
401 if (get_irn_op(n) == op_Phi ||
402 get_irn_op(n) == op_Block ||
403 (get_irn_op(n) == op_Filter && get_interprocedural_view()) ||
404 (get_irg_pinned(get_irn_irg(n)) == op_pin_state_floats &&
405 get_irn_pinned(n) == op_pin_state_floats))
406 // Here we could test for backedge at -1 which is illegal
413 /* This version causes deeper loop trees (at least we verified this
415 But it guarantees that Blocks are analysed before nodes contained in the
416 block. If so, we can set the value to undef if the block is not \
418 if (is_cfop(n) || is_fragile_op(n) || get_irn_op(n) == op_Start)
426 /* Test for legal loop header: Block, Phi, ... */
427 static INLINE int is_possible_loop_head(ir_node *n) {
428 ir_op *op = get_irn_op(n);
429 return ((op == op_Block) ||
431 ((op == op_Filter) && get_interprocedural_view()));
435 * Returns non-zero if n is a loop header, i.e., it is a Block, Phi
436 * or Filter node and has predecessors within the loop and out
438 * @param root: only needed for assertion.
440 static int is_head(ir_node *n, ir_node *root) {
442 int some_outof_loop = 0, some_in_loop = 0;
444 /* Test for legal loop header: Block, Phi, ... */
445 if (!is_possible_loop_head(n))
448 if (!is_outermost_Start(n)) {
449 arity = get_irn_arity(n);
450 for (i = get_start_index(n); i < arity; i++) {
451 ir_node *pred = get_irn_n(n, i);
453 if (is_backedge(n, i))
455 if (!irn_is_in_stack(pred)) {
458 if (get_irn_uplink(pred) < get_irn_uplink(root)) {
459 assert(get_irn_uplink(pred) >= get_irn_uplink(root));
465 return some_outof_loop && some_in_loop;
469 * Returns non-zero if n is possible loop head of an endless loop.
470 * I.e., it is a Block, Phi or Filter node and has only predecessors
472 * @param root: only needed for assertion.
474 static int is_endless_head(ir_node *n, ir_node *root) {
476 int some_outof_loop = 0, some_in_loop = 0;
478 /* Test for legal loop header: Block, Phi, ... */
479 if (!is_possible_loop_head(n))
482 if (!is_outermost_Start(n)) {
483 arity = get_irn_arity(n);
484 for (i = get_start_index(n); i < arity; i++) {
485 ir_node *pred = get_irn_n(n, i);
487 if (is_backedge(n, i)) { continue; }
488 if (!irn_is_in_stack(pred)) {
489 some_outof_loop = 1; //printf(" some out of loop ");
491 if (get_irn_uplink(pred) < get_irn_uplink(root)) {
492 assert(get_irn_uplink(pred) >= get_irn_uplink(root));
498 return !some_outof_loop && some_in_loop;
501 /** Returns index of the predecessor with the smallest dfn number
502 greater-equal than limit. */
503 static int smallest_dfn_pred(ir_node *n, int limit) {
504 int i, index = -2, min = -1;
506 if (!is_outermost_Start(n)) {
507 int arity = get_irn_arity(n);
508 for (i = get_start_index(n); i < arity; i++) {
509 ir_node *pred = get_irn_n(n, i);
511 if (is_backedge(n, i) || !irn_is_in_stack(pred)) continue;
512 if (get_irn_dfn(pred) >= limit && (min == -1 || get_irn_dfn(pred) < min)) {
514 min = get_irn_dfn(pred);
521 /* Returns index of the predecessor with the largest dfn number. */
522 static int largest_dfn_pred(ir_node *n) {
523 int i, index = -2, max = -1;
525 if (!is_outermost_Start(n)) {
526 int arity = get_irn_arity(n);
527 for (i = get_start_index(n); i < arity; i++) {
528 ir_node *pred = get_irn_n(n, i);
529 if (is_backedge (n, i) || !irn_is_in_stack(pred)) continue;
530 if (get_irn_dfn(pred) > max) {
532 max = get_irn_dfn(pred);
540 * Searches the stack for possible loop heads. Tests these for backedges.
541 * If it finds a head with an unmarked backedge it marks this edge and
542 * returns the tail of the loop.
543 * If it finds no backedge returns NULL.
544 * ("disable_backedge" in fiasco)
546 * @param n A node where uplink == dfn.
548 static ir_node *find_tail(ir_node *n) {
550 int i, res_index = -2;
553 if (!icfg && rm_cyclic_phis && remove_cyclic_phis (n)) return NULL;
555 m = stack[tos-1]; /* tos = top of stack */
556 if (is_head (m, n)) {
557 res_index = smallest_dfn_pred(m, 0);
558 if ((res_index == -2) && /* no smallest dfn pred found. */
562 if (m == n) return NULL; // Is this to catch Phi - self loops?
563 for (i = tos-2; i >= 0; --i) {
566 if (is_head (m, n)) {
567 res_index = smallest_dfn_pred (m, get_irn_dfn(m) + 1);
568 if (res_index == -2) /* no smallest dfn pred found. */
569 res_index = largest_dfn_pred (m);
571 if ((m == n) && (res_index == -2)) { /* don't walk past loop head. */
577 /* We should not walk past our selves on the stack: The upcoming nodes
578 are not in this loop. We assume a loop not reachable from Start. */
587 /* A dead loop not reachable from Start. */
588 for (i = tos-2; i >= 0; --i) {
590 if (is_endless_head (m, n)) {
591 res_index = smallest_dfn_pred (m, get_irn_dfn(m) + 1);
592 if (res_index == -2) /* no smallest dfn pred found. */
593 res_index = largest_dfn_pred (m);
596 if (m == n) { break; } /* It's not an unreachable loop, either. */
598 //assert(0 && "no head found on stack");
602 if (res_index <= -2) {
603 /* It's a completely bad loop: without Phi/Block nodes that can
604 be a head. I.e., the code is "dying". We break the loop by
605 setting Bad nodes. */
606 int arity = get_irn_arity(n);
607 for (i = -1; i < arity; ++i) {
608 set_irn_n(n, i, get_irg_bad(get_irn_irg(n)));
612 assert (res_index > -2);
614 set_backedge(m, res_index);
615 return is_outermost_Start(n) ? NULL : get_irn_n(m, res_index);
619 #if EXPERIMENTAL_LOOP_TREE
621 /* ----------------------------------------------------------------
622 AS: This is experimental code to build loop trees suitable for
623 the heap analysis. Does not work correctly right now... :-(
626 Search in stack for the corresponding first Call-End-ProjX that
627 corresponds to one of the control flow predecessors of the given
628 block, that is the possible callers.
629 returns: the control predecessor to chose\
630 or -1 if no corresponding Call-End-Node could be found
632 - -------------------------------------------------------------- */
634 int search_endproj_in_stack(ir_node *start_block) {
636 assert(is_Block(start_block));
637 for(i = tos - 1; i >= 0; --i)
639 if(get_irn_op(stack[i]) == op_Proj && get_irn_mode(stack[i]) == mode_X &&
640 get_irn_op(get_irn_n(stack[i], 0)) == op_EndReg)
642 printf("FOUND PROJ!!!!!!!!!!!!!!!!!!!!!!!!!!\n");
643 ir_node *end_projx = stack[i];
645 int arity = get_irn_arity(start_block);
646 for(j = 0; j < arity; j++)
648 ir_node *begin_projx = get_Block_cfgpred(get_irg_start_block(get_irn_irg(end_projx)),
649 get_Proj_proj(end_projx));
650 if(get_irn_n(start_block, j) == begin_projx)
652 printf("FOUND IT!!!!!!!!!!!!!!!!!!\n");
662 static pmap *projx_link = NULL;
664 void link_to_reg_end (ir_node *n, void *env) {
665 if(get_irn_op(n) == op_Proj &&
666 get_irn_mode(n) == mode_X &&
667 get_irn_op(get_irn_n(n, 0)) == op_EndReg) {
668 /* Reg End Projx -> Find the CallBegin Projx and hash it */
669 ir_node *end_projx = n;
670 ir_node *begin_projx = get_Block_cfgpred(get_irg_start_block(get_irn_irg(end_projx)),
671 get_Proj_proj(end_projx));
672 set_projx_link(begin_projx, end_projx);
676 void set_projx_link(ir_node *cb_projx, ir_node *end_projx) {
677 if(projx_link == NULL)
678 projx_link = pmap_create();
679 pmap_insert(projx_link, (void *)cb_projx, (void *)end_projx);
682 ir_node *get_projx_link(ir_node *cb_projx) {
683 return((ir_node *) pmap_get(projx_link, (void *)cb_projx));
688 static INLINE int is_outermost_loop(ir_loop *l) {
689 return l == get_loop_outer_loop(l);
693 /*-----------------------------------------------------------*
694 * The core algorithm. *
695 *-----------------------------------------------------------*/
697 static void scc(ir_node *n) {
699 if (irn_visited(n)) return;
702 /* Initialize the node */
703 set_irn_dfn(n, current_dfn); /* Depth first number for this node */
704 set_irn_uplink(n, current_dfn); /* ... is default uplink. */
705 set_irn_loop(n, NULL);
709 /* AS: get_start_index might return -1 for Control Flow Nodes, and thus a negative
710 array index would be passed to is_backedge(). But CFG Nodes dont't have a backedge array,
711 so is_backedge does not access array[-1] but correctly returns false! */
713 if (!is_outermost_Start(n)) {
714 int arity = get_irn_arity(n);
716 for (i = get_start_index(n); i < arity; i++) {
718 if (is_backedge(n, i)) continue;
719 m = get_irn_n(n, i); /* get_irn_ip_pred(n, i); */
720 /* if ((!m) || (get_irn_op(m) == op_Unknown)) continue; */
722 if (irn_is_in_stack(m)) {
723 /* Uplink of m is smaller if n->m is a backedge.
724 Propagate the uplink to mark the loop. */
725 if (get_irn_uplink(m) < get_irn_uplink(n))
726 set_irn_uplink(n, get_irn_uplink(m));
731 if (get_irn_dfn(n) == get_irn_uplink(n)) {
732 /* This condition holds for
733 1) the node with the incoming backedge.
734 That is: We found a loop!
735 2) Straight line code, because no uplink has been propagated, so the
736 uplink still is the same as the dfn.
738 But n might not be a proper loop head for the analysis. Proper loop
739 heads are Block and Phi nodes. find_tail searches the stack for
740 Block's and Phi's and takes those nodes as loop heads for the current
741 loop instead and marks the incoming edge as backedge. */
743 ir_node *tail = find_tail(n);
745 /* We have a loop, that is no straight line code,
746 because we found a loop head!
747 Next actions: Open a new loop on the loop tree and
748 try to find inner loops */
750 #if NO_LOOPS_WITHOUT_HEAD
751 /* This is an adaption of the algorithm from fiasco / optscc to
752 * avoid loops without Block or Phi as first node. This should
753 * severely reduce the number of evaluations of nodes to detect
754 * a fixpoint in the heap analysis.
755 * Further it avoids loops without firm nodes that cause errors
756 * in the heap analyses.
757 * But attention: don't do it for the outermost loop: This loop
758 * is not iterated. A first block can be a loop head in case of
759 * an endless recursion. */
763 if ((get_loop_n_elements(current_loop) > 0) || (is_outermost_loop(current_loop))) {
771 ir_loop *l = new_loop();
774 /* Remove the loop from the stack ... */
775 pop_scc_unmark_visit(n);
777 /* The current backedge has been marked, that is temporarily eliminated,
778 by find tail. Start the scc algorithm
779 anew on the subgraph that is left (the current loop without the backedge)
780 in order to find more inner loops. */
783 assert(irn_visited(n));
784 #if NO_LOOPS_WITHOUT_HEAD
789 /* No loop head was found, that is we have straight line code.
790 Pop all nodes from the stack to the current loop. */
796 static void my_scc(ir_node *n) {
802 /* Initialize the node */
803 set_irn_dfn(n, current_dfn); /* Depth first number for this node */
804 set_irn_uplink(n, current_dfn); /* ... is default uplink. */
805 set_irn_loop(n, NULL);
809 /* AS: get_start_index might return -1 for Control Flow Nodes, and thus a negative
810 array index would be passed to is_backedge(). But CFG Nodes dont't have a backedge array,
811 so is_backedge does not access array[-1] but correctly returns false! */
813 if (!is_outermost_Start(n)) {
814 int arity = get_irn_arity(n);
816 for (i = get_start_index(n); i < arity; i++) {
818 if (is_backedge(n, i)) continue;
819 m = get_irn_n(n, i); /* get_irn_ip_pred(n, i); */
820 /* if ((!m) || (get_irn_op(m) == op_Unknown)) continue; */
822 if (irn_is_in_stack(m)) {
823 /* Uplink of m is smaller if n->m is a backedge.
824 Propagate the uplink to mark the loop. */
825 if (get_irn_uplink(m) < get_irn_uplink(n))
826 set_irn_uplink(n, get_irn_uplink(m));
831 if (get_irn_dfn(n) == get_irn_uplink(n)) {
832 /* This condition holds for
833 1) the node with the incoming backedge.
834 That is: We found a loop!
835 2) Straight line code, because no uplink has been propagated, so the
836 uplink still is the same as the dfn.
838 But n might not be a proper loop head for the analysis. Proper loop
839 heads are Block and Phi nodes. find_tail searches the stack for
840 Block's and Phi's and takes those nodes as loop heads for the current
841 loop instead and marks the incoming edge as backedge. */
843 ir_node *tail = find_tail(n);
845 /* We have a loop, that is no straight line code,
846 because we found a loop head!
847 Next actions: Open a new loop on the loop tree and
848 try to find inner loops */
850 #if NO_LOOPS_WITHOUT_HEAD
851 /* This is an adaption of the algorithm from fiasco / optscc to
852 * avoid loops without Block or Phi as first node. This should
853 * severely reduce the number of evaluations of nodes to detect
854 * a fixpoint in the heap analysis.
855 * Further it avoids loops without firm nodes that cause errors
856 * in the heap analyses. */
860 if ((get_loop_n_elements(current_loop) > 0) || (is_outermost_loop(current_loop))) {
868 ir_loop *l = new_loop();
871 /* Remove the loop from the stack ... */
872 pop_scc_unmark_visit(n);
874 /* The current backedge has been marked, that is temporarily eliminated,
875 by find tail. Start the scc algorithm
876 anew on the subgraph that is left (the current loop without the backedge)
877 in order to find more inner loops. */
880 assert(irn_visited(n));
881 #if NO_LOOPS_WITHOUT_HEAD
886 /* No loop head was found, that is we have straightline code.
887 Pop all nodes from the stack to the current loop. */
893 /* Constructs backedge information for irg. In interprocedural view constructs
894 backedges for all methods called by irg, too. */
895 int construct_backedges(ir_graph *irg) {
896 ir_graph *rem = current_ir_graph;
900 assert(!get_interprocedural_view() &&
901 "not implemented, use construct_ip_backedges()");
904 current_ir_graph = irg;
905 outermost_ir_graph = irg;
908 init_scc(irg, &temp);
911 new_loop(); /* sets current_loop */
912 head_rem = current_loop; /* Just for assertion */
914 inc_irg_visited(irg);
916 scc(get_irg_end(irg));
918 assert(head_rem == current_loop);
919 mature_loops(current_loop, irg->obst);
920 set_irg_loop(irg, current_loop);
921 set_irg_loopinfo_state(irg, loopinfo_consistent);
922 assert(get_irg_loop(irg)->kind == k_ir_loop);
924 irg->loops = current_loop;
928 count_loop(the_loop, &count, &depth);
931 obstack_free(&temp, NULL);
932 current_ir_graph = rem;
933 return max_loop_depth;
937 #ifdef INTERPROCEDURAL_VIEW
938 int construct_ip_backedges(void) {
939 ir_graph *rem = current_ir_graph;
940 int rem_ipv = get_interprocedural_view();
945 assert(get_irp_ip_view_state() == ip_view_valid);
947 outermost_ir_graph = get_irp_main_irg();
953 new_loop(); /* sets current_loop */
954 set_interprocedural_view(1);
956 inc_max_irg_visited();
957 for (i = 0; i < get_irp_n_irgs(); i++)
958 set_irg_visited(get_irp_irg(i), get_max_irg_visited());
960 /** We have to start the walk at the same nodes as cg_walk. **/
961 /* Walk starting at unreachable procedures. Only these
962 * have End blocks visible in interprocedural view. */
963 for (i = 0; i < get_irp_n_irgs(); i++) {
965 current_ir_graph = get_irp_irg(i);
967 sb = get_irg_start_block(current_ir_graph);
969 if ((get_Block_n_cfgpreds(sb) > 1) ||
970 (get_nodes_block(get_Block_cfgpred(sb, 0)) != sb))
973 scc(get_irg_end(current_ir_graph));
976 /* Check whether we walked all procedures: there could be procedures
977 with cyclic calls but no call from the outside. */
978 for (i = 0; i < get_irp_n_irgs(); i++) {
980 current_ir_graph = get_irp_irg(i);
982 /* Test start block: if inner procedure end and end block are not
983 * visible and therefore not marked. */
984 sb = get_irg_start_block(current_ir_graph);
985 if (get_irn_visited(sb) < get_irg_visited(current_ir_graph)) scc(sb);
988 /* Walk all endless loops in inner procedures.
989 * We recognize an inner procedure if the End node is not visited. */
990 for (i = 0; i < get_irp_n_irgs(); i++) {
992 current_ir_graph = get_irp_irg(i);
994 e = get_irg_end(current_ir_graph);
995 if (get_irn_visited(e) < get_irg_visited(current_ir_graph)) {
997 /* Don't visit the End node. */
998 for (j = 0; j < get_End_n_keepalives(e); j++)
999 scc(get_End_keepalive(e, j));
1003 set_irg_loop(outermost_ir_graph, current_loop);
1004 set_irg_loopinfo_state(current_ir_graph, loopinfo_ip_consistent);
1005 assert(get_irg_loop(outermost_ir_graph)->kind == k_ir_loop);
1007 obstack_free(&temp, NULL);
1008 current_ir_graph = rem;
1009 set_interprocedural_view(rem_ipv);
1010 return max_loop_depth;
1013 void my_construct_ip_backedges(void) {
1014 ir_graph *rem = current_ir_graph;
1015 int rem_ipv = get_interprocedural_view();
1018 assert(get_irp_ip_view_state() == ip_view_valid);
1020 outermost_ir_graph = get_irp_main_irg();
1024 current_loop = NULL;
1025 new_loop(); /* sets current_loop */
1026 set_interprocedural_view(1);
1028 inc_max_irg_visited();
1029 for (i = 0; i < get_irp_n_irgs(); i++)
1030 set_irg_visited(get_irp_irg(i), get_max_irg_visited());
1032 /** We have to start the walk at the same nodes as cg_walk. **/
1033 /* Walk starting at unreachable procedures. Only these
1034 * have End blocks visible in interprocedural view. */
1035 for (i = 0; i < get_irp_n_irgs(); i++) {
1037 current_ir_graph = get_irp_irg(i);
1039 sb = get_irg_start_block(current_ir_graph);
1041 if ((get_Block_n_cfgpreds(sb) > 1) ||
1042 (get_nodes_block(get_Block_cfgpred(sb, 0)) != sb)) continue;
1044 my_scc(get_irg_end(current_ir_graph));
1047 /* Check whether we walked all procedures: there could be procedures
1048 with cyclic calls but no call from the outside. */
1049 for (i = 0; i < get_irp_n_irgs(); i++) {
1051 current_ir_graph = get_irp_irg(i);
1053 /* Test start block: if inner procedure end and end block are not
1054 * visible and therefore not marked. */
1055 sb = get_irg_start_block(current_ir_graph);
1056 if (get_irn_visited(sb) < get_irg_visited(current_ir_graph))
1060 /* Walk all endless loops in inner procedures.
1061 * We recognize an inner procedure if the End node is not visited. */
1062 for (i = 0; i < get_irp_n_irgs(); i++) {
1064 current_ir_graph = get_irp_irg(i);
1066 e = get_irg_end(current_ir_graph);
1067 if (get_irn_visited(e) < get_irg_visited(current_ir_graph)) {
1069 /* Don't visit the End node. */
1070 for (j = 0; j < get_End_n_keepalives(e); j++) scc(get_End_keepalive(e, j));
1074 set_irg_loop(outermost_ir_graph, current_loop);
1075 set_irg_loopinfo_state(current_ir_graph, loopinfo_ip_consistent);
1076 assert(get_irg_loop(outermost_ir_graph)->kind == k_ir_loop);
1078 current_ir_graph = rem;
1079 set_interprocedural_view(rem_ipv);
1083 static void reset_backedges(ir_node *n) {
1084 if (is_possible_loop_head(n)) {
1085 #ifdef INTERPROCEDURAL_VIEW
1086 int rem = get_interprocedural_view();
1088 set_interprocedural_view(1);
1090 set_interprocedural_view(1);
1092 set_interprocedural_view(rem);
1101 static void loop_reset_backedges(ir_loop *l) {
1103 reset_backedges(get_loop_node(l, 0));
1104 for (i = 0; i < get_loop_n_nodes(l); ++i)
1105 set_irn_loop(get_loop_node(l, i), NULL);
1106 for (i = 0; i < get_loop_n_sons(l); ++i) {
1107 loop_reset_backedges(get_loop_son(l, i));
1112 static void loop_reset_node(ir_node *n, void *env) {
1114 set_irn_loop(n, NULL);
1119 /** Removes all loop information.
1120 Resets all backedges */
1121 void free_loop_information(ir_graph *irg) {
1122 /* We can not use this recursion, as the loop might contain
1123 illegal nodes by now. Why else would we throw away the
1125 if (get_irg_loop(irg)) loop_reset_backedges(get_irg_loop(irg));
1127 irg_walk_graph(irg, loop_reset_node, NULL, NULL);
1128 set_irg_loop(irg, NULL);
1129 set_irg_loopinfo_state(current_ir_graph, loopinfo_none);
1130 /* We cannot free the loop nodes, they are on the obstack. */
1134 void free_all_loop_information(void) {
1136 #ifdef INTERPROCEDURAL_VIEW
1137 int rem = get_interprocedural_view();
1138 set_interprocedural_view(1); /* To visit all filter nodes */
1140 for (i = 0; i < get_irp_n_irgs(); i++) {
1141 free_loop_information(get_irp_irg(i));
1143 #ifdef INTERPROCEDURAL_VIEW
1144 set_interprocedural_view(rem);
1152 /* Debug stuff *************************************************/
1154 static int test_loop_node(ir_loop *l) {
1155 int i, has_node = 0, found_problem = 0;
1158 assert(l && l->kind == k_ir_loop);
1160 if (get_loop_n_elements(l) == 0) {
1162 dump_loop(l, "-ha");
1165 le = get_loop_element(l, 0);
1166 if (*(le.kind) != k_ir_node) {
1167 assert(le.kind && *(le.kind) == k_ir_loop);
1170 dump_loop(l, "-ha");
1173 if ((*(le.kind) == k_ir_node) && !is_possible_loop_head(le.node)) {
1175 dump_loop(l, "-ha");
1178 if ((get_loop_depth(l) != 0) &&
1179 (*(le.kind) == k_ir_node) && !has_backedges(le.node)) {
1181 dump_loop(l, "-ha");
1186 for (i = 0; i < get_loop_n_elements(l); ++i) {
1187 le = get_loop_element(l, i);
1188 if (*(le.kind) == k_ir_node)
1191 if (test_loop_node(le.son)) found_problem = 1;
1194 if (has_node == 0) {
1196 dump_loop(l, "-ha");
1199 return found_problem;
1202 /** Prints all loop nodes that
1203 * - do not have any firm nodes, only loop sons
1204 * - the header is not a Phi, Block or Filter.
1206 void find_strange_loop_nodes(ir_loop *l) {
1207 int found_problem = 0;
1208 found_problem = test_loop_node(l);
1209 printf("Finished Test\n\n");
1210 if (found_problem) exit(0);
1214 /* ------------------------------------------------------------------- */
1215 /* Simple analyses based on the loop information */
1216 /* ------------------------------------------------------------------- */
1218 int is_loop_variant(ir_loop *l, ir_loop *b) {
1221 if (l == b) return 1;
1223 n_elems = get_loop_n_elements(l);
1224 for (i = 0; i < n_elems; ++i) {
1225 loop_element e = get_loop_element(l, i);
1226 if (is_ir_loop(e.kind))
1227 if (is_loop_variant(e.son, b))
1234 /* Test whether a value is loop invariant.
1236 * @param n The node to be tested.
1237 * @param block A block node. We pass the block, not the loop as we must
1238 * start off with a block loop to find all proper uses.
1240 * Returns non-zero, if the node n is not changed in the loop block
1241 * belongs to or in inner loops of this blocks loop. */
1242 int is_loop_invariant(ir_node *n, ir_node *block) {
1243 ir_loop *l = get_irn_loop(block);
1244 ir_node *b = is_Block(n) ? n : get_nodes_block(n);
1245 return !is_loop_variant(l, get_irn_loop(b));