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) {
718 if (irn_visited_else_mark(n))
721 /* Initialize the node */
722 set_irn_dfn(n, current_dfn); /* Depth first number for this node */
723 set_irn_uplink(n, current_dfn); /* ... is default uplink. */
724 set_irn_loop(n, NULL);
728 /* AS: get_start_index might return -1 for Control Flow Nodes, and thus a negative
729 array index would be passed to is_backedge(). But CFG Nodes dont't have a backedge array,
730 so is_backedge does not access array[-1] but correctly returns false! */
732 if (!is_outermost_Start(n)) {
733 int i, arity = get_irn_arity(n);
735 for (i = get_start_index(n); i < arity; ++i) {
737 if (is_backedge(n, i))
741 if (irn_is_in_stack(m)) {
742 /* Uplink of m is smaller if n->m is a backedge.
743 Propagate the uplink to mark the loop. */
744 if (get_irn_uplink(m) < get_irn_uplink(n))
745 set_irn_uplink(n, get_irn_uplink(m));
750 if (get_irn_dfn(n) == get_irn_uplink(n)) {
751 /* This condition holds for
752 1) the node with the incoming backedge.
753 That is: We found a loop!
754 2) Straight line code, because no uplink has been propagated, so the
755 uplink still is the same as the dfn.
757 But n might not be a proper loop head for the analysis. Proper loop
758 heads are Block and Phi nodes. find_tail() searches the stack for
759 Block's and Phi's and takes those nodes as loop heads for the current
760 loop instead and marks the incoming edge as backedge. */
762 ir_node *tail = find_tail(n);
764 /* We have a loop, that is no straight line code,
765 because we found a loop head!
766 Next actions: Open a new loop on the loop tree and
767 try to find inner loops */
769 #if NO_LOOPS_WITHOUT_HEAD
770 /* This is an adaption of the algorithm from fiasco / optscc to
771 * avoid loops without Block or Phi as first node. This should
772 * severely reduce the number of evaluations of nodes to detect
773 * a fixpoint in the heap analysis.
774 * Further it avoids loops without firm nodes that cause errors
775 * in the heap analyses.
776 * But attention: don't do it for the outermost loop: This loop
777 * is not iterated. A first block can be a loop head in case of
778 * an endless recursion. */
782 if ((get_loop_n_elements(current_loop) > 0) || (is_outermost_loop(current_loop))) {
790 ir_loop *l = new_loop();
793 /* Remove the loop from the stack ... */
794 pop_scc_unmark_visit(n);
796 /* The current backedge has been marked, that is temporarily eliminated,
797 by find tail. Start the scc algorithm
798 again on the subgraph that is left (the current loop without the backedge)
799 in order to find more inner loops. */
802 assert(irn_visited(n));
803 #if NO_LOOPS_WITHOUT_HEAD
808 /* No loop head was found, that is we have straight line code.
809 Pop all nodes from the stack to the current loop. */
815 #ifdef INTERPROCEDURAL_VIEW
816 static void my_scc(ir_node *n) {
818 if (irn_visited_else_mark(n))
821 /* Initialize the node */
822 set_irn_dfn(n, current_dfn); /* Depth first number for this node */
823 set_irn_uplink(n, current_dfn); /* ... is default uplink. */
824 set_irn_loop(n, NULL);
828 /* AS: get_start_index might return -1 for Control Flow Nodes, and thus a negative
829 array index would be passed to is_backedge(). But CFG Nodes dont't have a backedge array,
830 so is_backedge does not access array[-1] but correctly returns false! */
832 if (!is_outermost_Start(n)) {
833 int arity = get_irn_arity(n);
835 for (i = get_start_index(n); i < arity; i++) {
837 if (is_backedge(n, i)) continue;
838 m = get_irn_n(n, i); /* get_irn_ip_pred(n, i); */
839 /* if (!m || is_Unknown(m)) continue; */
841 if (irn_is_in_stack(m)) {
842 /* Uplink of m is smaller if n->m is a backedge.
843 Propagate the uplink to mark the loop. */
844 if (get_irn_uplink(m) < get_irn_uplink(n))
845 set_irn_uplink(n, get_irn_uplink(m));
850 if (get_irn_dfn(n) == get_irn_uplink(n)) {
851 /* This condition holds for
852 1) the node with the incoming backedge.
853 That is: We found a loop!
854 2) Straight line code, because no uplink has been propagated, so the
855 uplink still is the same as the dfn.
857 But n might not be a proper loop head for the analysis. Proper loop
858 heads are Block and Phi nodes. find_tail searches the stack for
859 Block's and Phi's and takes those nodes as loop heads for the current
860 loop instead and marks the incoming edge as backedge. */
862 ir_node *tail = find_tail(n);
864 /* We have a loop, that is no straight line code,
865 because we found a loop head!
866 Next actions: Open a new loop on the loop tree and
867 try to find inner loops */
869 #if NO_LOOPS_WITHOUT_HEAD
870 /* This is an adaption of the algorithm from fiasco / optscc to
871 * avoid loops without Block or Phi as first node. This should
872 * severely reduce the number of evaluations of nodes to detect
873 * a fixpoint in the heap analysis.
874 * Further it avoids loops without firm nodes that cause errors
875 * in the heap analyses. */
879 if ((get_loop_n_elements(current_loop) > 0) || (is_outermost_loop(current_loop))) {
887 ir_loop *l = new_loop();
890 /* Remove the loop from the stack ... */
891 pop_scc_unmark_visit(n);
893 /* The current backedge has been marked, that is temporarily eliminated,
894 by find tail. Start the scc algorithm
895 anew on the subgraph that is left (the current loop without the backedge)
896 in order to find more inner loops. */
899 assert(irn_visited(n));
900 #if NO_LOOPS_WITHOUT_HEAD
905 /* No loop head was found, that is we have straightline code.
906 Pop all nodes from the stack to the current loop. */
911 #endif /* INTERPROCEDURAL_VIEW */
913 /* Constructs backedge information for irg. In interprocedural view constructs
914 backedges for all methods called by irg, too. */
915 int construct_backedges(ir_graph *irg) {
916 ir_graph *rem = current_ir_graph;
920 assert(!get_interprocedural_view() &&
921 "not implemented, use construct_ip_backedges()");
924 current_ir_graph = irg;
925 outermost_ir_graph = irg;
928 init_scc(irg, &temp);
931 new_loop(); /* sets current_loop */
932 head_rem = current_loop; /* Just for assertion */
934 inc_irg_visited(irg);
936 scc(get_irg_end(irg));
939 obstack_free(&temp, NULL);
941 assert(head_rem == current_loop);
942 mature_loops(current_loop, irg->obst);
943 set_irg_loop(irg, current_loop);
944 set_irg_loopinfo_state(irg, loopinfo_consistent);
945 assert(get_irg_loop(irg)->kind == k_ir_loop);
946 current_ir_graph = rem;
947 return max_loop_depth;
951 #ifdef INTERPROCEDURAL_VIEW
952 int construct_ip_backedges(void) {
953 ir_graph *rem = current_ir_graph;
954 int rem_ipv = get_interprocedural_view();
959 assert(get_irp_ip_view_state() == ip_view_valid);
961 outermost_ir_graph = get_irp_main_irg();
967 new_loop(); /* sets current_loop */
968 set_interprocedural_view(1);
970 inc_max_irg_visited();
971 for (i = 0; i < get_irp_n_irgs(); i++)
972 set_irg_visited(get_irp_irg(i), get_max_irg_visited());
974 /** We have to start the walk at the same nodes as cg_walk. **/
975 /* Walk starting at unreachable procedures. Only these
976 * have End blocks visible in interprocedural view. */
977 for (i = 0; i < get_irp_n_irgs(); i++) {
979 current_ir_graph = get_irp_irg(i);
981 sb = get_irg_start_block(current_ir_graph);
983 if ((get_Block_n_cfgpreds(sb) > 1) ||
984 (get_nodes_block(get_Block_cfgpred(sb, 0)) != sb))
987 scc(get_irg_end(current_ir_graph));
990 /* Check whether we walked all procedures: there could be procedures
991 with cyclic calls but no call from the outside. */
992 for (i = 0; i < get_irp_n_irgs(); i++) {
994 current_ir_graph = get_irp_irg(i);
996 /* Test start block: if inner procedure end and end block are not
997 * visible and therefore not marked. */
998 sb = get_irg_start_block(current_ir_graph);
999 if (get_irn_visited(sb) < get_irg_visited(current_ir_graph)) scc(sb);
1002 /* Walk all endless loops in inner procedures.
1003 * We recognize an inner procedure if the End node is not visited. */
1004 for (i = 0; i < get_irp_n_irgs(); i++) {
1006 current_ir_graph = get_irp_irg(i);
1008 e = get_irg_end(current_ir_graph);
1009 if (get_irn_visited(e) < get_irg_visited(current_ir_graph)) {
1011 /* Don't visit the End node. */
1012 for (j = 0; j < get_End_n_keepalives(e); j++)
1013 scc(get_End_keepalive(e, j));
1017 set_irg_loop(outermost_ir_graph, current_loop);
1018 set_irg_loopinfo_state(current_ir_graph, loopinfo_ip_consistent);
1019 assert(get_irg_loop(outermost_ir_graph)->kind == k_ir_loop);
1021 obstack_free(&temp, NULL);
1022 current_ir_graph = rem;
1023 set_interprocedural_view(rem_ipv);
1024 return max_loop_depth;
1027 void my_construct_ip_backedges(void) {
1028 ir_graph *rem = current_ir_graph;
1029 int rem_ipv = get_interprocedural_view();
1032 assert(get_irp_ip_view_state() == ip_view_valid);
1034 outermost_ir_graph = get_irp_main_irg();
1038 current_loop = NULL;
1039 new_loop(); /* sets current_loop */
1040 set_interprocedural_view(1);
1042 inc_max_irg_visited();
1043 for (i = 0; i < get_irp_n_irgs(); i++)
1044 set_irg_visited(get_irp_irg(i), get_max_irg_visited());
1046 /** We have to start the walk at the same nodes as cg_walk. **/
1047 /* Walk starting at unreachable procedures. Only these
1048 * have End blocks visible in interprocedural view. */
1049 for (i = 0; i < get_irp_n_irgs(); i++) {
1051 current_ir_graph = get_irp_irg(i);
1053 sb = get_irg_start_block(current_ir_graph);
1055 if ((get_Block_n_cfgpreds(sb) > 1) ||
1056 (get_nodes_block(get_Block_cfgpred(sb, 0)) != sb)) continue;
1058 my_scc(get_irg_end(current_ir_graph));
1061 /* Check whether we walked all procedures: there could be procedures
1062 with cyclic calls but no call from the outside. */
1063 for (i = 0; i < get_irp_n_irgs(); i++) {
1065 current_ir_graph = get_irp_irg(i);
1067 /* Test start block: if inner procedure end and end block are not
1068 * visible and therefore not marked. */
1069 sb = get_irg_start_block(current_ir_graph);
1070 if (get_irn_visited(sb) < get_irg_visited(current_ir_graph))
1074 /* Walk all endless loops in inner procedures.
1075 * We recognize an inner procedure if the End node is not visited. */
1076 for (i = 0; i < get_irp_n_irgs(); i++) {
1078 current_ir_graph = get_irp_irg(i);
1080 e = get_irg_end(current_ir_graph);
1081 if (get_irn_visited(e) < get_irg_visited(current_ir_graph)) {
1083 /* Don't visit the End node. */
1084 for (j = 0; j < get_End_n_keepalives(e); j++) scc(get_End_keepalive(e, j));
1088 set_irg_loop(outermost_ir_graph, current_loop);
1089 set_irg_loopinfo_state(current_ir_graph, loopinfo_ip_consistent);
1090 assert(get_irg_loop(outermost_ir_graph)->kind == k_ir_loop);
1092 current_ir_graph = rem;
1093 set_interprocedural_view(rem_ipv);
1097 static void reset_backedges(ir_node *n) {
1098 if (is_possible_loop_head(n)) {
1099 #ifdef INTERPROCEDURAL_VIEW
1100 int rem = get_interprocedural_view();
1102 set_interprocedural_view(1);
1104 set_interprocedural_view(1);
1106 set_interprocedural_view(rem);
1115 static void loop_reset_backedges(ir_loop *l) {
1117 reset_backedges(get_loop_node(l, 0));
1118 for (i = 0; i < get_loop_n_nodes(l); ++i)
1119 set_irn_loop(get_loop_node(l, i), NULL);
1120 for (i = 0; i < get_loop_n_sons(l); ++i) {
1121 loop_reset_backedges(get_loop_son(l, i));
1126 static void loop_reset_node(ir_node *n, void *env) {
1128 set_irn_loop(n, NULL);
1133 /** Removes all loop information.
1134 Resets all backedges */
1135 void free_loop_information(ir_graph *irg) {
1136 /* We can not use this recursion, as the loop might contain
1137 illegal nodes by now. Why else would we throw away the
1139 if (get_irg_loop(irg)) loop_reset_backedges(get_irg_loop(irg));
1141 irg_walk_graph(irg, loop_reset_node, NULL, NULL);
1142 set_irg_loop(irg, NULL);
1143 set_irg_loopinfo_state(current_ir_graph, loopinfo_none);
1144 /* We cannot free the loop nodes, they are on the obstack. */
1148 void free_all_loop_information(void) {
1150 #ifdef INTERPROCEDURAL_VIEW
1151 int rem = get_interprocedural_view();
1152 set_interprocedural_view(1); /* To visit all filter nodes */
1154 for (i = 0; i < get_irp_n_irgs(); i++) {
1155 free_loop_information(get_irp_irg(i));
1157 #ifdef INTERPROCEDURAL_VIEW
1158 set_interprocedural_view(rem);
1166 /* Debug stuff *************************************************/
1168 static int test_loop_node(ir_loop *l) {
1169 int i, has_node = 0, found_problem = 0;
1172 assert(l && l->kind == k_ir_loop);
1174 if (get_loop_n_elements(l) == 0) {
1176 dump_loop(l, "-ha");
1179 le = get_loop_element(l, 0);
1180 if (*(le.kind) != k_ir_node) {
1181 assert(le.kind && *(le.kind) == k_ir_loop);
1184 dump_loop(l, "-ha");
1187 if ((*(le.kind) == k_ir_node) && !is_possible_loop_head(le.node)) {
1189 dump_loop(l, "-ha");
1192 if ((get_loop_depth(l) != 0) &&
1193 (*(le.kind) == k_ir_node) && !has_backedges(le.node)) {
1195 dump_loop(l, "-ha");
1200 for (i = 0; i < get_loop_n_elements(l); ++i) {
1201 le = get_loop_element(l, i);
1202 if (*(le.kind) == k_ir_node)
1205 if (test_loop_node(le.son)) found_problem = 1;
1208 if (has_node == 0) {
1210 dump_loop(l, "-ha");
1213 return found_problem;
1216 /** Prints all loop nodes that
1217 * - do not have any firm nodes, only loop sons
1218 * - the header is not a Phi, Block or Filter.
1220 void find_strange_loop_nodes(ir_loop *l) {
1221 int found_problem = 0;
1222 found_problem = test_loop_node(l);
1223 printf("Finished Test\n\n");
1224 if (found_problem) exit(0);
1228 /* ------------------------------------------------------------------- */
1229 /* Simple analyses based on the loop information */
1230 /* ------------------------------------------------------------------- */
1232 int is_loop_variant(ir_loop *l, ir_loop *b) {
1235 if (l == b) return 1;
1237 n_elems = get_loop_n_elements(l);
1238 for (i = 0; i < n_elems; ++i) {
1239 loop_element e = get_loop_element(l, i);
1240 if (is_ir_loop(e.kind))
1241 if (is_loop_variant(e.son, b))
1248 /* Test whether a value is loop invariant.
1250 * @param n The node to be tested.
1251 * @param block A block node. We pass the block, not the loop as we must
1252 * start off with a block loop to find all proper uses.
1254 * Returns non-zero, if the node n is not changed in the loop block
1255 * belongs to or in inner loops of this blocks loop. */
1256 int is_loop_invariant(const ir_node *n, const ir_node *block) {
1257 ir_loop *l = get_irn_loop(block);
1258 const ir_node *b = is_Block(n) ? n : get_nodes_block(n);
1259 return !is_loop_variant(l, get_irn_loop(b));