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 ||
397 get_irn_op(n) == op_Block ||
398 (get_irn_op(n) == op_Filter && get_interprocedural_view()) ||
399 (get_irg_pinned(get_irn_irg(n)) == op_pin_state_floats &&
400 get_irn_pinned(n) == op_pin_state_floats))
401 // Here we could test for backedge at -1 which is illegal
408 /* This version causes deeper loop trees (at least we verified this
410 But it guarantees that Blocks are analysed before nodes contained in the
411 block. If so, we can set the value to undef if the block is not \
413 if (is_cfop(n) || is_fragile_op(n) || get_irn_op(n) == op_Start)
422 * Return non-zero if the given node is a legal loop header:
423 * Block, Phi, Filter.
425 * @param n the node to check
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
439 * @param n the node to check
440 * @param root only needed for assertion.
442 static int is_head(ir_node *n, ir_node *root) {
444 int some_outof_loop = 0, some_in_loop = 0;
446 /* Test for legal loop header: Block, Phi, ... */
447 if (!is_possible_loop_head(n))
450 if (!is_outermost_Start(n)) {
452 int uplink = get_irn_uplink(root);
454 arity = get_irn_arity(n);
455 for (i = get_start_index(n); i < arity; i++) {
457 if (is_backedge(n, i))
459 pred = get_irn_n(n, i);
460 if (! irn_is_in_stack(pred)) {
463 assert(get_irn_uplink(pred) >= uplink);
468 return some_outof_loop & some_in_loop;
472 * Returns non-zero if n is possible loop head of an endless loop.
473 * I.e., it is a Block, Phi or Filter node and has only predecessors
476 * @param n the node to check
477 * @param root only needed for assertion.
479 static int is_endless_head(ir_node *n, ir_node *root) {
481 int none_outof_loop = 1, some_in_loop = 0;
483 /* Test for legal loop header: Block, Phi, ... */
484 if (!is_possible_loop_head(n))
487 if (!is_outermost_Start(n)) {
489 int uplink = get_irn_uplink(root);
491 arity = get_irn_arity(n);
492 for (i = get_start_index(n); i < arity; i++) {
494 if (is_backedge(n, i))
496 pred = get_irn_n(n, i);
497 if (!irn_is_in_stack(pred)) {
500 assert(get_irn_uplink(pred) >= uplink);
505 return none_outof_loop & some_in_loop;
508 /** Returns index of the predecessor with the smallest dfn number
509 greater-equal than limit. */
510 static int smallest_dfn_pred(ir_node *n, int limit) {
511 int i, index = -2, min = -1;
513 if (!is_outermost_Start(n)) {
514 int arity = get_irn_arity(n);
515 for (i = get_start_index(n); i < arity; i++) {
516 ir_node *pred = get_irn_n(n, i);
517 if (is_backedge(n, i) || !irn_is_in_stack(pred))
519 if (get_irn_dfn(pred) >= limit && (min == -1 || get_irn_dfn(pred) < min)) {
521 min = get_irn_dfn(pred);
529 * Returns index of the predecessor with the largest dfn number.
531 static int largest_dfn_pred(ir_node *n) {
532 int i, index = -2, max = -1;
534 if (!is_outermost_Start(n)) {
535 int arity = get_irn_arity(n);
536 for (i = get_start_index(n); i < arity; i++) {
537 ir_node *pred = get_irn_n(n, i);
538 if (is_backedge (n, i) || !irn_is_in_stack(pred))
540 if (get_irn_dfn(pred) > max) {
542 max = get_irn_dfn(pred);
550 * Searches the stack for possible loop heads. Tests these for backedges.
551 * If it finds a head with an unmarked backedge it marks this edge and
552 * returns the tail of the loop.
553 * If it finds no backedge returns NULL.
554 * ("disable_backedge" in fiasco)
556 * @param n A node where uplink == dfn.
558 static ir_node *find_tail(ir_node *n) {
560 int i, res_index = -2;
563 if (!icfg && rm_cyclic_phis && remove_cyclic_phis (n)) return NULL;
565 m = stack[tos-1]; /* tos = top of stack */
567 res_index = smallest_dfn_pred(m, 0);
568 if ((res_index == -2) && /* no smallest dfn pred found. */
572 if (m == n) return NULL; // Is this to catch Phi - self loops?
573 for (i = tos-2; i >= 0; --i) {
577 res_index = smallest_dfn_pred(m, get_irn_dfn(m) + 1);
578 if (res_index == -2) /* no smallest dfn pred found. */
579 res_index = largest_dfn_pred(m);
581 if ((m == n) && (res_index == -2)) { /* don't walk past loop head. */
587 /* We should not walk past our selves on the stack: The upcoming nodes
588 are not in this loop. We assume a loop not reachable from Start. */
596 /* A dead loop not reachable from Start. */
597 for (i = tos-2; i >= 0; --i) {
599 if (is_endless_head(m, n)) {
600 res_index = smallest_dfn_pred(m, get_irn_dfn(m) + 1);
601 if (res_index == -2) /* no smallest dfn pred found. */
602 res_index = largest_dfn_pred (m);
605 if (m == n) { break; } /* It's not an unreachable loop, either. */
607 //assert(0 && "no head found on stack");
611 if (res_index <= -2) {
612 /* It's a completely bad loop: without Phi/Block nodes that can
613 be a head. I.e., the code is "dying". We break the loop by
614 setting Bad nodes. */
615 int arity = get_irn_arity(n);
616 ir_node *bad = get_irg_bad(get_irn_irg(n));
617 for (i = -1; i < arity; ++i) {
618 set_irn_n(n, i, bad);
622 assert(res_index > -2);
624 set_backedge(m, res_index);
625 return is_outermost_Start(n) ? NULL : get_irn_n(m, res_index);
629 #if EXPERIMENTAL_LOOP_TREE
631 /* ----------------------------------------------------------------
632 AS: This is experimental code to build loop trees suitable for
633 the heap analysis. Does not work correctly right now... :-(
636 Search in stack for the corresponding first Call-End-ProjX that
637 corresponds to one of the control flow predecessors of the given
638 block, that is the possible callers.
639 returns: the control predecessor to chose\
640 or -1 if no corresponding Call-End-Node could be found
642 - -------------------------------------------------------------- */
644 int search_endproj_in_stack(ir_node *start_block) {
646 assert(is_Block(start_block));
647 for(i = tos - 1; i >= 0; --i)
649 if(get_irn_op(stack[i]) == op_Proj && get_irn_mode(stack[i]) == mode_X &&
650 get_irn_op(get_irn_n(stack[i], 0)) == op_EndReg)
652 printf("FOUND PROJ!!!!!!!!!!!!!!!!!!!!!!!!!!\n");
653 ir_node *end_projx = stack[i];
655 int arity = get_irn_arity(start_block);
656 for(j = 0; j < arity; j++)
658 ir_node *begin_projx = get_Block_cfgpred(get_irg_start_block(get_irn_irg(end_projx)),
659 get_Proj_proj(end_projx));
660 if(get_irn_n(start_block, j) == begin_projx)
662 printf("FOUND IT!!!!!!!!!!!!!!!!!!\n");
672 static pmap *projx_link = NULL;
674 void link_to_reg_end (ir_node *n, void *env) {
675 if(get_irn_op(n) == op_Proj &&
676 get_irn_mode(n) == mode_X &&
677 get_irn_op(get_irn_n(n, 0)) == op_EndReg) {
678 /* Reg End Projx -> Find the CallBegin Projx and hash it */
679 ir_node *end_projx = n;
680 ir_node *begin_projx = get_Block_cfgpred(get_irg_start_block(get_irn_irg(end_projx)),
681 get_Proj_proj(end_projx));
682 set_projx_link(begin_projx, end_projx);
686 void set_projx_link(ir_node *cb_projx, ir_node *end_projx) {
687 if(projx_link == NULL)
688 projx_link = pmap_create();
689 pmap_insert(projx_link, (void *)cb_projx, (void *)end_projx);
692 ir_node *get_projx_link(ir_node *cb_projx) {
693 return((ir_node *) pmap_get(projx_link, (void *)cb_projx));
698 static INLINE int is_outermost_loop(ir_loop *l) {
699 return l == get_loop_outer_loop(l);
703 /*-----------------------------------------------------------*
704 * The core algorithm. *
705 *-----------------------------------------------------------*/
708 * The core algorithm: Find strongly coupled components.
710 * @param n node to start
712 static void scc(ir_node *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) {
818 /* Initialize the node */
819 set_irn_dfn(n, current_dfn); /* Depth first number for this node */
820 set_irn_uplink(n, current_dfn); /* ... is default uplink. */
821 set_irn_loop(n, NULL);
825 /* AS: get_start_index might return -1 for Control Flow Nodes, and thus a negative
826 array index would be passed to is_backedge(). But CFG Nodes dont't have a backedge array,
827 so is_backedge does not access array[-1] but correctly returns false! */
829 if (!is_outermost_Start(n)) {
830 int arity = get_irn_arity(n);
832 for (i = get_start_index(n); i < arity; i++) {
834 if (is_backedge(n, i)) continue;
835 m = get_irn_n(n, i); /* get_irn_ip_pred(n, i); */
836 /* if ((!m) || (get_irn_op(m) == op_Unknown)) continue; */
838 if (irn_is_in_stack(m)) {
839 /* Uplink of m is smaller if n->m is a backedge.
840 Propagate the uplink to mark the loop. */
841 if (get_irn_uplink(m) < get_irn_uplink(n))
842 set_irn_uplink(n, get_irn_uplink(m));
847 if (get_irn_dfn(n) == get_irn_uplink(n)) {
848 /* This condition holds for
849 1) the node with the incoming backedge.
850 That is: We found a loop!
851 2) Straight line code, because no uplink has been propagated, so the
852 uplink still is the same as the dfn.
854 But n might not be a proper loop head for the analysis. Proper loop
855 heads are Block and Phi nodes. find_tail searches the stack for
856 Block's and Phi's and takes those nodes as loop heads for the current
857 loop instead and marks the incoming edge as backedge. */
859 ir_node *tail = find_tail(n);
861 /* We have a loop, that is no straight line code,
862 because we found a loop head!
863 Next actions: Open a new loop on the loop tree and
864 try to find inner loops */
866 #if NO_LOOPS_WITHOUT_HEAD
867 /* This is an adaption of the algorithm from fiasco / optscc to
868 * avoid loops without Block or Phi as first node. This should
869 * severely reduce the number of evaluations of nodes to detect
870 * a fixpoint in the heap analysis.
871 * Further it avoids loops without firm nodes that cause errors
872 * in the heap analyses. */
876 if ((get_loop_n_elements(current_loop) > 0) || (is_outermost_loop(current_loop))) {
884 ir_loop *l = new_loop();
887 /* Remove the loop from the stack ... */
888 pop_scc_unmark_visit(n);
890 /* The current backedge has been marked, that is temporarily eliminated,
891 by find tail. Start the scc algorithm
892 anew on the subgraph that is left (the current loop without the backedge)
893 in order to find more inner loops. */
896 assert(irn_visited(n));
897 #if NO_LOOPS_WITHOUT_HEAD
902 /* No loop head was found, that is we have straightline code.
903 Pop all nodes from the stack to the current loop. */
908 #endif /* INTERPROCEDURAL_VIEW */
910 /* Constructs backedge information for irg. In interprocedural view constructs
911 backedges for all methods called by irg, too. */
912 int construct_backedges(ir_graph *irg) {
913 ir_graph *rem = current_ir_graph;
917 assert(!get_interprocedural_view() &&
918 "not implemented, use construct_ip_backedges()");
921 current_ir_graph = irg;
922 outermost_ir_graph = irg;
925 init_scc(irg, &temp);
928 new_loop(); /* sets current_loop */
929 head_rem = current_loop; /* Just for assertion */
931 inc_irg_visited(irg);
933 scc(get_irg_end(irg));
936 obstack_free(&temp, NULL);
938 assert(head_rem == current_loop);
939 mature_loops(current_loop, irg->obst);
940 set_irg_loop(irg, current_loop);
941 set_irg_loopinfo_state(irg, loopinfo_consistent);
942 assert(get_irg_loop(irg)->kind == k_ir_loop);
943 current_ir_graph = rem;
944 return max_loop_depth;
948 #ifdef INTERPROCEDURAL_VIEW
949 int construct_ip_backedges(void) {
950 ir_graph *rem = current_ir_graph;
951 int rem_ipv = get_interprocedural_view();
956 assert(get_irp_ip_view_state() == ip_view_valid);
958 outermost_ir_graph = get_irp_main_irg();
964 new_loop(); /* sets current_loop */
965 set_interprocedural_view(1);
967 inc_max_irg_visited();
968 for (i = 0; i < get_irp_n_irgs(); i++)
969 set_irg_visited(get_irp_irg(i), get_max_irg_visited());
971 /** We have to start the walk at the same nodes as cg_walk. **/
972 /* Walk starting at unreachable procedures. Only these
973 * have End blocks visible in interprocedural view. */
974 for (i = 0; i < get_irp_n_irgs(); i++) {
976 current_ir_graph = get_irp_irg(i);
978 sb = get_irg_start_block(current_ir_graph);
980 if ((get_Block_n_cfgpreds(sb) > 1) ||
981 (get_nodes_block(get_Block_cfgpred(sb, 0)) != sb))
984 scc(get_irg_end(current_ir_graph));
987 /* Check whether we walked all procedures: there could be procedures
988 with cyclic calls but no call from the outside. */
989 for (i = 0; i < get_irp_n_irgs(); i++) {
991 current_ir_graph = get_irp_irg(i);
993 /* Test start block: if inner procedure end and end block are not
994 * visible and therefore not marked. */
995 sb = get_irg_start_block(current_ir_graph);
996 if (get_irn_visited(sb) < get_irg_visited(current_ir_graph)) scc(sb);
999 /* Walk all endless loops in inner procedures.
1000 * We recognize an inner procedure if the End node is not visited. */
1001 for (i = 0; i < get_irp_n_irgs(); i++) {
1003 current_ir_graph = get_irp_irg(i);
1005 e = get_irg_end(current_ir_graph);
1006 if (get_irn_visited(e) < get_irg_visited(current_ir_graph)) {
1008 /* Don't visit the End node. */
1009 for (j = 0; j < get_End_n_keepalives(e); j++)
1010 scc(get_End_keepalive(e, j));
1014 set_irg_loop(outermost_ir_graph, current_loop);
1015 set_irg_loopinfo_state(current_ir_graph, loopinfo_ip_consistent);
1016 assert(get_irg_loop(outermost_ir_graph)->kind == k_ir_loop);
1018 obstack_free(&temp, NULL);
1019 current_ir_graph = rem;
1020 set_interprocedural_view(rem_ipv);
1021 return max_loop_depth;
1024 void my_construct_ip_backedges(void) {
1025 ir_graph *rem = current_ir_graph;
1026 int rem_ipv = get_interprocedural_view();
1029 assert(get_irp_ip_view_state() == ip_view_valid);
1031 outermost_ir_graph = get_irp_main_irg();
1035 current_loop = NULL;
1036 new_loop(); /* sets current_loop */
1037 set_interprocedural_view(1);
1039 inc_max_irg_visited();
1040 for (i = 0; i < get_irp_n_irgs(); i++)
1041 set_irg_visited(get_irp_irg(i), get_max_irg_visited());
1043 /** We have to start the walk at the same nodes as cg_walk. **/
1044 /* Walk starting at unreachable procedures. Only these
1045 * have End blocks visible in interprocedural view. */
1046 for (i = 0; i < get_irp_n_irgs(); i++) {
1048 current_ir_graph = get_irp_irg(i);
1050 sb = get_irg_start_block(current_ir_graph);
1052 if ((get_Block_n_cfgpreds(sb) > 1) ||
1053 (get_nodes_block(get_Block_cfgpred(sb, 0)) != sb)) continue;
1055 my_scc(get_irg_end(current_ir_graph));
1058 /* Check whether we walked all procedures: there could be procedures
1059 with cyclic calls but no call from the outside. */
1060 for (i = 0; i < get_irp_n_irgs(); i++) {
1062 current_ir_graph = get_irp_irg(i);
1064 /* Test start block: if inner procedure end and end block are not
1065 * visible and therefore not marked. */
1066 sb = get_irg_start_block(current_ir_graph);
1067 if (get_irn_visited(sb) < get_irg_visited(current_ir_graph))
1071 /* Walk all endless loops in inner procedures.
1072 * We recognize an inner procedure if the End node is not visited. */
1073 for (i = 0; i < get_irp_n_irgs(); i++) {
1075 current_ir_graph = get_irp_irg(i);
1077 e = get_irg_end(current_ir_graph);
1078 if (get_irn_visited(e) < get_irg_visited(current_ir_graph)) {
1080 /* Don't visit the End node. */
1081 for (j = 0; j < get_End_n_keepalives(e); j++) scc(get_End_keepalive(e, j));
1085 set_irg_loop(outermost_ir_graph, current_loop);
1086 set_irg_loopinfo_state(current_ir_graph, loopinfo_ip_consistent);
1087 assert(get_irg_loop(outermost_ir_graph)->kind == k_ir_loop);
1089 current_ir_graph = rem;
1090 set_interprocedural_view(rem_ipv);
1094 static void reset_backedges(ir_node *n) {
1095 if (is_possible_loop_head(n)) {
1096 #ifdef INTERPROCEDURAL_VIEW
1097 int rem = get_interprocedural_view();
1099 set_interprocedural_view(1);
1101 set_interprocedural_view(1);
1103 set_interprocedural_view(rem);
1112 static void loop_reset_backedges(ir_loop *l) {
1114 reset_backedges(get_loop_node(l, 0));
1115 for (i = 0; i < get_loop_n_nodes(l); ++i)
1116 set_irn_loop(get_loop_node(l, i), NULL);
1117 for (i = 0; i < get_loop_n_sons(l); ++i) {
1118 loop_reset_backedges(get_loop_son(l, i));
1123 static void loop_reset_node(ir_node *n, void *env) {
1125 set_irn_loop(n, NULL);
1130 /** Removes all loop information.
1131 Resets all backedges */
1132 void free_loop_information(ir_graph *irg) {
1133 /* We can not use this recursion, as the loop might contain
1134 illegal nodes by now. Why else would we throw away the
1136 if (get_irg_loop(irg)) loop_reset_backedges(get_irg_loop(irg));
1138 irg_walk_graph(irg, loop_reset_node, NULL, NULL);
1139 set_irg_loop(irg, NULL);
1140 set_irg_loopinfo_state(current_ir_graph, loopinfo_none);
1141 /* We cannot free the loop nodes, they are on the obstack. */
1145 void free_all_loop_information(void) {
1147 #ifdef INTERPROCEDURAL_VIEW
1148 int rem = get_interprocedural_view();
1149 set_interprocedural_view(1); /* To visit all filter nodes */
1151 for (i = 0; i < get_irp_n_irgs(); i++) {
1152 free_loop_information(get_irp_irg(i));
1154 #ifdef INTERPROCEDURAL_VIEW
1155 set_interprocedural_view(rem);
1163 /* Debug stuff *************************************************/
1165 static int test_loop_node(ir_loop *l) {
1166 int i, has_node = 0, found_problem = 0;
1169 assert(l && l->kind == k_ir_loop);
1171 if (get_loop_n_elements(l) == 0) {
1173 dump_loop(l, "-ha");
1176 le = get_loop_element(l, 0);
1177 if (*(le.kind) != k_ir_node) {
1178 assert(le.kind && *(le.kind) == k_ir_loop);
1181 dump_loop(l, "-ha");
1184 if ((*(le.kind) == k_ir_node) && !is_possible_loop_head(le.node)) {
1186 dump_loop(l, "-ha");
1189 if ((get_loop_depth(l) != 0) &&
1190 (*(le.kind) == k_ir_node) && !has_backedges(le.node)) {
1192 dump_loop(l, "-ha");
1197 for (i = 0; i < get_loop_n_elements(l); ++i) {
1198 le = get_loop_element(l, i);
1199 if (*(le.kind) == k_ir_node)
1202 if (test_loop_node(le.son)) found_problem = 1;
1205 if (has_node == 0) {
1207 dump_loop(l, "-ha");
1210 return found_problem;
1213 /** Prints all loop nodes that
1214 * - do not have any firm nodes, only loop sons
1215 * - the header is not a Phi, Block or Filter.
1217 void find_strange_loop_nodes(ir_loop *l) {
1218 int found_problem = 0;
1219 found_problem = test_loop_node(l);
1220 printf("Finished Test\n\n");
1221 if (found_problem) exit(0);
1225 /* ------------------------------------------------------------------- */
1226 /* Simple analyses based on the loop information */
1227 /* ------------------------------------------------------------------- */
1229 int is_loop_variant(ir_loop *l, ir_loop *b) {
1232 if (l == b) return 1;
1234 n_elems = get_loop_n_elements(l);
1235 for (i = 0; i < n_elems; ++i) {
1236 loop_element e = get_loop_element(l, i);
1237 if (is_ir_loop(e.kind))
1238 if (is_loop_variant(e.son, b))
1245 /* Test whether a value is loop invariant.
1247 * @param n The node to be tested.
1248 * @param block A block node. We pass the block, not the loop as we must
1249 * start off with a block loop to find all proper uses.
1251 * Returns non-zero, if the node n is not changed in the loop block
1252 * belongs to or in inner loops of this blocks loop. */
1253 int is_loop_invariant(const ir_node *n, const ir_node *block) {
1254 ir_loop *l = get_irn_loop(block);
1255 const ir_node *b = is_Block(n) ? n : get_nodes_block(n);
1256 return !is_loop_variant(l, get_irn_loop(b));