2 * Interblock liveness analysis.
3 * @author Sebastian Hack
11 #include "iredges_t.h"
13 #include "irprintf_t.h"
18 #include "besched_t.h"
20 #define DBG_MODULE "firm.be.liveness"
22 #define LV_STD_SIZE 128
23 #define LV_USE_BINARY_SEARCH
24 #undef LV_INTESIVE_CHECKS
26 static INLINE int is_liveness_node(const ir_node *irn)
28 return !is_Block(irn) && !is_Bad(irn);
31 int (be_lv_next_irn)(const struct _be_lv_t *lv, const ir_node *bl, unsigned flags, int i)
33 return _be_lv_next_irn(lv, bl, flags, i);
36 const ir_node * (be_lv_get_irn)(const struct _be_lv_t *lv, const ir_node *bl, int i)
38 return _be_lv_get_irn(lv, bl, i);
41 int (be_is_live_in)(const be_lv_t *lv, const ir_node *block, const ir_node *irn)
43 return _be_is_live_xxx(lv, block, irn, be_lv_state_in);
46 int (be_is_live_out)(const be_lv_t *lv, const ir_node *block, const ir_node *irn)
48 return _be_is_live_xxx(lv, block, irn, be_lv_state_out);
51 int (be_is_live_end)(const be_lv_t *lv, const ir_node *block, const ir_node *irn)
53 return _be_is_live_xxx(lv, block, irn, be_lv_state_end);
57 #ifdef LV_USE_BINARY_SEARCH
58 static INLINE unsigned _be_liveness_bsearch(struct _be_lv_info_t *arr, unsigned idx)
60 struct _be_lv_info_t *payload = arr + 1;
62 unsigned n = arr[0].u.head.n_members;
71 if(idx < payload[0].u.node.idx)
74 if(idx > payload[n - 1].u.node.idx)
78 /* start a binary search for the requested node. */
80 int md = lo + ((hi - lo) >> 1);
81 unsigned md_idx = payload[md].u.node.idx;
89 assert(payload[res].u.node.idx == idx);
96 #ifdef LV_INTESIVE_CHECKS
99 for(i = res; i < n; ++i)
100 assert(payload[i].u.node.idx >= idx);
102 for(i = 0; i < res; ++i)
103 assert(payload[i].u.node.idx < idx);
113 * This function searches linearily for the node in the array.
115 static INLINE unsigned _be_liveness_bsearch(struct _be_lv_info_t *arr, unsigned idx) {
116 unsigned n = arr[0].u.head.n_members;
119 for(i = 0; i < n; ++i) {
120 if(arr[i + 1].u.node.idx == idx)
128 struct _be_lv_info_node_t *be_lv_get(const struct _be_lv_t *li, const ir_node *bl, const ir_node *irn)
130 struct _be_lv_info_t *irn_live = phase_get_irn_data(&li->ph, bl);
133 unsigned idx = get_irn_idx(irn);
135 /* Get the position of the index in the array. */
136 int pos = _be_liveness_bsearch(irn_live, idx);
138 /* Get the record in question. 1 must be added, since the first record contains information about the array and must be skipped. */
139 struct _be_lv_info_node_t *res = &irn_live[pos + 1].u.node;
141 /* Check, if the irn is in deed in the array. */
149 static struct _be_lv_info_node_t *be_lv_get_or_set(struct _be_lv_t *li, ir_node *bl, ir_node *irn)
151 struct _be_lv_info_t *irn_live = phase_get_or_set_irn_data(&li->ph, bl);
153 unsigned idx = get_irn_idx(irn);
155 /* Get the position of the index in the array. */
156 unsigned pos = _be_liveness_bsearch(irn_live, idx);
158 /* Get the record in question. 1 must be added, since the first record contains information about the array and must be skipped. */
159 struct _be_lv_info_node_t *res = &irn_live[pos + 1].u.node;
161 /* Check, if the irn is in deed in the array. */
162 if(res->idx != idx) {
163 struct _be_lv_info_t *payload;
164 unsigned n_members = irn_live[0].u.head.n_members;
165 unsigned n_size = irn_live[0].u.head.n_size;
168 if(n_members == n_size - 1) {
169 unsigned new_size = 2 * n_size * sizeof(irn_live[0]);
170 struct _be_lv_info_t *nw = phase_alloc(&li->ph, new_size);
171 memcpy(nw, irn_live, new_size);
172 nw[0].u.head.n_size = new_size;
174 phase_set_irn_data(&li->ph, irn, nw);
177 payload = &irn_live[1];
178 for(i = n_members; i > pos; --i) {
179 payload[i] = payload[i - 1];
182 ++irn_live[0].u.head.n_members;
184 res = &payload[pos].u.node;
189 #ifdef LV_INTESIVE_CHECKS
192 unsigned n = irn_live[0].u.head.n_members;
194 struct _be_lv_info_t *payload = &irn_live[1];
196 for(i = 0; i < n; ++i) {
197 assert(payload[i].u.node.idx >= last);
198 last = payload[i].u.node.idx;
207 * Removes a node from the list of live variables of a block.
208 * @return 1 if the node was live at that block, 0 if not.
210 static int be_lv_remove(struct _be_lv_t *li, ir_node *bl, ir_node *irn)
212 struct _be_lv_info_t *irn_live = phase_get_irn_data(&li->ph, bl);
215 unsigned n = irn_live[0].u.head.n_members;
216 unsigned idx = get_irn_idx(irn);
217 unsigned pos = _be_liveness_bsearch(irn_live, idx);
218 struct _be_lv_info_t *payload = irn_live + 1;
219 struct _be_lv_info_node_t *res = &payload[pos].u.node;
221 /* The node is in deed in the block's array. Let's remove it. */
222 if(res->idx == idx) {
225 for(i = pos + 1; i < n; ++i)
226 payload[i - 1] = payload[i];
228 payload[n - 1].u.node.idx = 0;
229 payload[n - 1].u.node.flags = 0;
231 --irn_live[0].u.head.n_members;
232 DBG((li->dbg, LEVEL_3, "\tdeleting %+F from %+F at pos %d\n", irn, bl, pos));
240 static void register_node(be_lv_t *lv, const ir_node *irn)
242 unsigned idx = get_irn_idx(irn);
243 if(idx >= bitset_size(lv->nodes)) {
244 bitset_t *nw = bitset_malloc(2 * idx);
245 bitset_copy(nw, lv->nodes);
246 bitset_free(lv->nodes);
250 bitset_set(lv->nodes, idx);
254 * Mark a node as live-in in a block.
256 static INLINE void mark_live_in(be_lv_t *lv, ir_node *block, ir_node *irn)
258 struct _be_lv_info_node_t *n = be_lv_get_or_set(lv, block, irn);
259 DBG((lv->dbg, LEVEL_2, "marking %+F live in at %+F\n", irn, block));
260 n->flags |= be_lv_state_in;
261 register_node(lv, irn);
265 * Mark a node as live-out in a block.
267 static INLINE void mark_live_out(be_lv_t *lv, ir_node *block, ir_node *irn)
269 struct _be_lv_info_node_t *n = be_lv_get_or_set(lv, block, irn);
270 DBG((lv->dbg, LEVEL_2, "marking %+F live out at %+F\n", irn, block));
271 n->flags |= be_lv_state_out | be_lv_state_end;
272 register_node(lv, irn);
276 * Mark a node as live-end in a block.
278 static INLINE void mark_live_end(be_lv_t *lv, ir_node *block, ir_node *irn)
280 struct _be_lv_info_node_t *n = be_lv_get_or_set(lv, block, irn);
281 DBG((lv->dbg, LEVEL_2, "marking %+F live end at %+F\n", irn, block));
282 n->flags |= be_lv_state_end;
283 register_node(lv, irn);
287 * Mark a node (value) live out at a certain block. Do this also
288 * transitively, i.e. if the block is not the block of the value's
289 * definition, all predecessors are also marked live.
290 * @param def The node (value).
291 * @param block The block to mark the value live out of.
292 * @param visited A set were all visited blocks are recorded.
293 * @param is_true_out Is the node real out there or only live at the end
296 static void live_end_at_block(be_lv_t *lv, ir_node *def, ir_node *block, bitset_t *visited, int is_true_out)
298 mark_live_end(lv, block, def);
300 mark_live_out(lv, block, def);
302 if(!bitset_contains_irn(visited, block)) {
303 bitset_add_irn(visited, block);
306 * If this block is not the definition block, we have to go up
309 if(get_nodes_block(def) != block) {
312 mark_live_in(lv, block, def);
314 for(i = 0, n = get_Block_n_cfgpreds(block); i < n; ++i)
315 live_end_at_block(lv, def, get_Block_cfgpred_block(block, i), visited, 1);
321 struct _lv_walker_t {
327 * Liveness analysis for a value.
328 * This functions is meant to be called by a firm walker, to compute the
329 * set of all blocks a value is live in.
330 * @param irn The node (value).
331 * @param env Ignored.
333 static void liveness_for_node(ir_node *irn, void *data)
335 struct _lv_walker_t *walker = data;
336 be_lv_t *lv = walker->lv;
337 bitset_t *visited = walker->data;
338 const ir_edge_t *edge;
341 /* Don't compute liveness information for non-data nodes. */
342 if(!is_liveness_node(irn))
345 bitset_clear_all(visited);
346 def_block = get_nodes_block(irn);
348 /* Go over all uses of the value */
349 foreach_out_edge(irn, edge) {
350 ir_node *use = edge->src;
354 * If the usage is no data node, skip this use, since it does not
355 * affect the liveness of the node.
357 if(!is_liveness_node(use))
360 /* Get the block where the usage is in. */
361 use_block = get_nodes_block(use);
364 * If the use is a phi function, determine the corresponding block
365 * through which the value reaches the phi function and mark the
366 * value as live out of that block.
369 ir_node *pred_block = get_Block_cfgpred_block(use_block, edge->pos);
370 live_end_at_block(lv, irn, pred_block, visited, 0);
374 * Else, the value is live in at this block. Mark it and call live
375 * out on the predecessors.
377 else if(def_block != use_block) {
380 mark_live_in(lv, use_block, irn);
382 for(i = 0, n = get_Block_n_cfgpreds(use_block); i < n; ++i) {
383 ir_node *pred_block = get_Block_cfgpred_block(use_block, i);
384 live_end_at_block(lv, irn, pred_block, visited, 1);
390 static void lv_remove_irn_walker(ir_node *bl, void *data)
392 struct _lv_walker_t *w = data;
394 ir_node *irn = w->data;
395 be_lv_remove(lv, bl, irn);
398 static const char *lv_flags_to_str(unsigned flags)
400 static const char *states[] = {
411 return states[flags & 7];
414 static void lv_dump_block(void *context, FILE *f, const ir_node *bl)
417 be_lv_t *lv = context;
418 struct _be_lv_info_t *info = phase_get_irn_data(&lv->ph, bl);
420 fprintf(f, "liveness:\n");
422 unsigned n = info[0].u.head.n_members;
425 for(i = 0; i < n; ++i) {
426 struct _be_lv_info_node_t *n = &info[i+1].u.node;
427 ir_fprintf(f, "%s %+F\n", lv_flags_to_str(n->flags), get_idx_irn(lv->irg, n->idx));
433 static void *lv_phase_data_init(phase_t *phase, ir_node *irn, void *old)
435 struct _be_lv_info_t *info = phase_alloc(phase, LV_STD_SIZE * sizeof(info[0]));
436 memset(info, 0, LV_STD_SIZE * sizeof(info[0]));
437 info[0].u.head.n_size = LV_STD_SIZE - 1;
441 static void compute_liveness(be_lv_t *lv)
443 struct _lv_walker_t w;
445 w.data = bitset_malloc(get_irg_last_idx(lv->irg));
446 irg_walk_graph(lv->irg, liveness_for_node, NULL, &w);
450 /* Compute the inter block liveness for a graph. */
451 be_lv_t *be_liveness(ir_graph *irg)
453 be_lv_t *lv = xmalloc(sizeof(lv[0]));
455 memset(lv, 0, sizeof(lv[0]));
456 FIRM_DBG_REGISTER(lv->dbg, DBG_MODULE);
458 lv->nodes = bitset_malloc(2 * get_irg_last_idx(irg));
459 lv->hook_info.context = lv;
460 lv->hook_info.hook._hook_node_info = lv_dump_block;
461 register_hook(hook_node_info, &lv->hook_info);
462 phase_init(&lv->ph, "liveness", irg, PHASE_DEFAULT_GROWTH, lv_phase_data_init);
463 compute_liveness(lv);
468 void be_liveness_recompute(be_lv_t *lv)
470 unsigned last_idx = get_irg_last_idx(lv->irg);
471 if(last_idx >= bitset_size(lv->nodes)) {
472 bitset_free(lv->nodes);
473 lv->nodes = bitset_malloc(last_idx * 2);
477 bitset_clear_all(lv->nodes);
480 phase_init(&lv->ph, "liveness", lv->irg, PHASE_DEFAULT_GROWTH, lv_phase_data_init);
481 compute_liveness(lv);
485 void be_liveness_free(be_lv_t *lv)
487 unregister_hook(hook_node_info, &lv->hook_info);
489 bitset_free(lv->nodes);
493 void be_liveness_remove(be_lv_t *lv, ir_node *irn)
495 unsigned idx = get_irn_idx(irn);
496 struct _lv_walker_t w;
499 * Removes a single irn from the liveness information.
500 * Since an irn can only be live at blocks dominated by the block of its
501 * definition, we only have to process that dominance subtree.
505 dom_tree_walk(get_nodes_block(irn), lv_remove_irn_walker, NULL, &w);
506 if(idx <= bitset_size(lv->nodes))
507 bitset_clear(lv->nodes, idx);
510 void be_liveness_introduce(be_lv_t *lv, ir_node *irn)
512 struct _lv_walker_t w;
514 w.data = bitset_malloc(get_irg_last_idx(lv->irg));
515 liveness_for_node(irn, &w);
519 void be_liveness_update(be_lv_t *lv, ir_node *irn)
521 be_liveness_remove(lv, irn);
522 be_liveness_introduce(lv, irn);
525 static void lv_add_missing_walker(ir_node *irn, void *data)
527 struct _lv_walker_t *w = data;
528 if(!is_Block(irn) && !bitset_contains_irn(w->lv->nodes, irn)) {
529 liveness_for_node(irn, w);
533 void be_liveness_add_missing(be_lv_t *lv)
535 struct _lv_walker_t w;
537 w.data = bitset_malloc(get_irg_last_idx(lv->irg));
538 irg_walk_graph(lv->irg, lv_add_missing_walker, NULL, &w);
542 static void lv_check_walker(ir_node *bl, void *data)
544 struct _lv_walker_t *w = data;
546 be_lv_t *fresh = w->data;
548 struct _be_lv_info_t *curr = phase_get_irn_data(&lv->ph, bl);
549 struct _be_lv_info_t *fr = phase_get_irn_data(&fresh->ph, bl);
551 if(!fr && curr && curr[0].u.head.n_members > 0) {
554 ir_fprintf(stderr, "%+F liveness should be empty but current liveness contains:\n", bl);
555 for(i = 0; i < curr[0].u.head.n_members; ++i) {
556 ir_fprintf(stderr, "\t%+F\n", get_idx_irn(lv->irg, curr[1 + i].u.node.idx));
561 unsigned n_curr = curr[0].u.head.n_members;
562 unsigned n_fresh = fr[0].u.head.n_members;
566 if(n_curr != n_fresh) {
567 ir_fprintf(stderr, "%+F: liveness set sizes differ. curr %d, correct %d\n", bl, n_curr, n_fresh);
569 ir_fprintf(stderr, "current:\n");
570 for(i = 0; i < n_curr; ++i) {
571 struct _be_lv_info_node_t *n = &curr[1 + i].u.node;
572 ir_fprintf(stderr, "%+F %u %+F %s\n", bl, i, get_idx_irn(lv->irg, n->idx), lv_flags_to_str(n->flags));
575 ir_fprintf(stderr, "correct:\n");
576 for(i = 0; i < n_fresh; ++i) {
577 struct _be_lv_info_node_t *n = &fr[1 + i].u.node;
578 ir_fprintf(stderr, "%+F %u %+F %s\n", bl, i, get_idx_irn(lv->irg, n->idx), lv_flags_to_str(n->flags));
584 void be_liveness_check(be_lv_t *lv)
586 struct _lv_walker_t w;
587 be_lv_t *fresh = be_liveness(lv->irg);
591 irg_block_walk_graph(lv->irg, lv_check_walker, NULL, &w);
592 be_liveness_free(fresh);
596 static void lv_dump_block_walker(ir_node *irn, void *data)
598 struct _lv_walker_t *w = data;
600 lv_dump_block(w->lv, w->data, irn);
604 /* Dump the liveness information for a graph. */
605 void be_liveness_dump(const be_lv_t *lv, FILE *f)
607 struct _lv_walker_t w;
609 w.lv = (be_lv_t *) lv;
611 irg_block_walk_graph(lv->irg, lv_dump_block_walker, NULL, &w);
614 /* Dump the liveness information for a graph. */
615 void be_liveness_dumpto(const be_lv_t *lv, const char *cls_name)
619 ir_snprintf(buf, sizeof(buf), "%F_%s-live.txt", lv->irg, cls_name);
620 if((f = fopen(buf, "wt")) != NULL) {
621 be_liveness_dump(lv, f);
627 * Walker: checks the every predecessors of a node dominate
630 static void dom_check(ir_node *irn, void *data)
632 if(!is_Block(irn) && irn != get_irg_end(get_irn_irg(irn))) {
634 ir_node *bl = get_nodes_block(irn);
636 for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
637 ir_node *op = get_irn_n(irn, i);
638 ir_node *def_bl = get_nodes_block(op);
639 ir_node *use_bl = bl;
642 use_bl = get_Block_cfgpred_block(bl, i);
644 if(!block_dominates(def_bl, use_bl)) {
645 ir_fprintf(stderr, "%+F in %+F must dominate %+F for user %+F\n", op, def_bl, use_bl, irn);
652 /* Check, if the SSA dominance property is fulfilled. */
653 void be_check_dominance(ir_graph *irg)
655 irg_walk_graph(irg, dom_check, NULL, NULL);
658 pset *be_liveness_transfer(const arch_env_t *arch_env, const arch_register_class_t *cls, ir_node *irn, pset *live)
662 FIRM_DBG_REGISTER(firm_dbg_module_t *dbg, DBG_MODULE);
665 DBG((dbg, LEVEL_1, "%+F\n", irn));
666 for(x = pset_first(live); x; x = pset_next(live))
667 DBG((dbg, LEVEL_1, "\tlive: %+F\n", x));
670 /* You should better break out of your loop when hitting the first phi function. */
671 assert(!is_Phi(irn) && "liveness_transfer produces invalid results for phi nodes");
673 if(arch_irn_consider_in_reg_alloc(arch_env, cls, irn)) {
674 ir_node *del = pset_remove_ptr(live, irn);
678 for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
679 ir_node *op = get_irn_n(irn, i);
681 if(arch_irn_consider_in_reg_alloc(arch_env, cls, op))
682 pset_insert_ptr(live, op);
688 pset *be_liveness_end_of_block(const be_lv_t *lv, const arch_env_t *arch_env, const arch_register_class_t *cls, const ir_node *bl, pset *live)
691 be_lv_foreach(lv, bl, be_lv_state_end, i) {
692 ir_node *irn = be_lv_get_irn(lv, bl, i);
693 if(arch_irn_consider_in_reg_alloc(arch_env, cls, irn))
694 pset_insert_ptr(live, irn);
700 pset *be_liveness_nodes_live_at(const be_lv_t *lv, const arch_env_t *arch_env, const arch_register_class_t *cls, const ir_node *pos, pset *live)
702 const ir_node *bl = is_Block(pos) ? pos : get_nodes_block(pos);
705 be_liveness_end_of_block(lv, arch_env, cls, bl, live);
706 sched_foreach_reverse(bl, irn) {
708 * If we encounter the node we want to insert the Perm after,
709 * exit immediately, so that this node is still live
714 be_liveness_transfer(arch_env, cls, irn, live);