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 FIRM_IMPL2(is_live_in, int, const ir_node *, const ir_node *)
23 FIRM_IMPL2(is_live_out, int, const ir_node *, const ir_node *)
24 FIRM_IMPL2(is_live_end, int, const ir_node *, const ir_node *)
26 /** The offset of the liveness information in a firm node. */
27 size_t live_irg_data_offset = 0;
29 void be_liveness_init(void)
31 live_irg_data_offset = register_additional_graph_data(sizeof(irn_live_t));
35 * Mark a node as live-in in a block.
37 static INLINE void mark_live_in(ir_node *block, const ir_node *irn)
39 _get_or_set_live(block, irn, live_state_in);
43 * Mark a node as live-out in a block.
45 static INLINE void mark_live_out(ir_node *block, const ir_node *irn)
47 _get_or_set_live(block, irn, live_state_out | live_state_end);
51 * Mark a node as live-end in a block.
53 static INLINE void mark_live_end(ir_node *block, const ir_node *irn)
55 _get_or_set_live(block, irn, live_state_end);
59 * Mark a node (value) live out at a certain block. Do this also
60 * transitively, i.e. if the block is not the block of the value's
61 * definition, all predecessors are also marked live.
62 * @param def The node (value).
63 * @param block The block to mark the value live out of.
64 * @param visited A set were all visited blocks are recorded.
65 * @param is_true_out Is the node real out there or only live at the end
68 static void live_end_at_block(ir_node *def, ir_node *block, bitset_t *visited, int is_true_out)
70 mark_live_end(block, def);
72 mark_live_out(block, def);
74 if(!bitset_contains_irn(visited, block)) {
75 bitset_add_irn(visited, block);
78 * If this block is not the definition block, we have to go up
81 if(get_nodes_block(def) != block) {
84 mark_live_in(block, def);
86 for(i = 0, n = get_Block_n_cfgpreds(block); i < n; ++i)
87 live_end_at_block(def, get_Block_cfgpred_block(block, i), visited, 1);
94 * Liveness analysis for a value.
95 * This functions is meant to be called by a firm walker, to compute the
96 * set of all blocks a value is live in.
97 * @param irn The node (value).
100 static void liveness_for_node(ir_node *irn, void *data)
102 bitset_t *visited = data;
103 const ir_edge_t *edge;
106 /* Don't compute liveness information for non-data nodes. */
107 if(!is_data_node(irn))
110 bitset_clear_all(visited);
111 def_block = get_nodes_block(irn);
113 /* Go over all uses of the value */
114 foreach_out_edge(irn, edge) {
115 ir_node *use = edge->src;
119 * If the usage is no data node, skip this use, since it does not
120 * affect the liveness of the node.
122 if(!is_data_node(use))
125 /* Get the block where the usage is in. */
126 use_block = get_nodes_block(use);
129 * If the use is a phi function, determine the corresponding block
130 * through which the value reaches the phi function and mark the
131 * value as live out of that block.
134 ir_node *pred_block = get_Block_cfgpred_block(use_block, edge->pos);
135 live_end_at_block(irn, pred_block, visited, 0);
139 * Else, the value is live in at this block. Mark it and call live
140 * out on the predecessors.
142 else if(def_block != use_block) {
145 mark_live_in(use_block, irn);
147 for(i = 0, n = get_Block_n_cfgpreds(use_block); i < n; ++i) {
148 ir_node *pred_block = get_Block_cfgpred_block(use_block, i);
149 live_end_at_block(irn, pred_block, visited, 1);
156 * Compare two live entries.
158 static int cmp_irn_live(const void *a, const void *b, size_t size)
160 const irn_live_t *p = a;
161 const irn_live_t *q = b;
163 return !(p->block == q->block && p->irn == q->irn);
166 static int (*old_dump_block_func)(ir_node *self, FILE *F, dump_reason_t reason) = NULL;
168 static int dump_block_func(ir_node *self, FILE *F, dump_reason_t reason)
171 case dump_node_opcode_txt:
172 fprintf(F, get_irn_opname(self));
174 case dump_node_mode_txt:
175 fprintf(F, get_irn_modename(self));
177 case dump_node_nodeattr_txt:
179 case dump_node_info_txt:
180 if(!get_irg_live_info(get_irn_irg(self))->live)
183 fprintf(F, "liveness information:\n");
186 live_foreach(self, li) {
187 ir_fprintf(F, "%+F", li->irn);
204 /* Compute the inter block liveness for a graph. */
205 void be_liveness(ir_graph *irg)
207 bitset_t *visited = bitset_irg_malloc(irg);
209 irg_live_info_t *live_info = get_irg_live_info(irg);
211 del_set(live_info->live);
213 live_info->live = new_set(cmp_irn_live, 8192);
214 irg_walk_graph(irg, liveness_for_node, NULL, visited);
216 old_dump_block_func = op_Block->ops.dump_node;
217 op_Block->ops.dump_node = dump_block_func;
219 bitset_free(visited);
223 * Pre-walker: dump liveness data to a file
225 static void dump_liveness_walker(ir_node *bl, void *data)
228 const irn_live_t *li;
231 ir_fprintf(f, "%+F\n", bl);
232 live_foreach(bl, li) {
244 ir_fprintf(f, "\t%+20F %s\n", li->irn, buf);
248 /* Dump the liveness information for a graph. */
249 void be_liveness_dump(ir_graph *irg, FILE *f)
251 irg_block_walk_graph(irg, dump_liveness_walker, NULL, f);
254 /* Dump the liveness information for a graph. */
255 void be_liveness_dumpto(ir_graph *irg, const char *cls_name)
259 ir_snprintf(buf, sizeof(buf), "%F_%s-live.txt", irg, cls_name);
260 if((f = fopen(buf, "wt")) != NULL) {
261 be_liveness_dump(irg, f);
267 * Walker: checks the every predecessors of a node dominate
270 static void dom_check(ir_node *irn, void *data)
272 if(!is_Block(irn) && irn != get_irg_end(get_irn_irg(irn))) {
274 ir_node *bl = get_nodes_block(irn);
276 for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
277 ir_node *op = get_irn_n(irn, i);
278 ir_node *def_bl = get_nodes_block(op);
279 ir_node *use_bl = bl;
282 use_bl = get_Block_cfgpred_block(bl, i);
284 if(!block_dominates(def_bl, use_bl)) {
285 ir_fprintf(stderr, "%+F in %+F must dominate %+F for user %+F\n", op, def_bl, use_bl, irn);
292 /* Check, if the SSA dominance property is fulfilled. */
293 void be_check_dominance(ir_graph *irg)
295 irg_walk_graph(irg, dom_check, NULL, NULL);
298 pset *be_liveness_transfer(const arch_env_t *arch_env, const arch_register_class_t *cls, ir_node *irn, pset *live)
302 FIRM_DBG_REGISTER(firm_dbg_module_t *dbg, DBG_MODULE);
305 DBG((dbg, LEVEL_1, "%+F\n", irn));
306 for(x = pset_first(live); x; x = pset_next(live))
307 DBG((dbg, LEVEL_1, "\tlive: %+F\n", x));
310 /* You should better break out of your loop when hitting the first phi function. */
311 assert(!is_Phi(irn) && "liveness_transfer produces invalid results for phi nodes");
313 if(arch_irn_consider_in_reg_alloc(arch_env, cls, irn)) {
314 ir_node *del = pset_remove_ptr(live, irn);
318 for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
319 ir_node *op = get_irn_n(irn, i);
321 if(arch_irn_consider_in_reg_alloc(arch_env, cls, op))
322 pset_insert_ptr(live, op);
328 pset *be_liveness_end_of_block(const arch_env_t *arch_env, const arch_register_class_t *cls, const ir_node *bl, pset *live)
332 live_foreach(bl, li) {
333 ir_node *irn = (ir_node *) li->irn;
334 if(live_is_end(li) && arch_irn_consider_in_reg_alloc(arch_env, cls, irn))
335 pset_insert_ptr(live, irn);
341 pset *be_liveness_nodes_live_at(const arch_env_t *arch_env, const arch_register_class_t *cls, const ir_node *pos, pset *live)
343 const ir_node *bl = is_Block(pos) ? pos : get_nodes_block(pos);
346 be_liveness_end_of_block(arch_env, cls, bl, live);
347 sched_foreach_reverse(bl, irn) {
349 * If we encounter the node we want to insert the Perm after,
350 * exit immediately, so that this node is still live
355 be_liveness_transfer(arch_env, cls, irn, live);