4 * @author Sebastian Hack, Matthias Braun
6 * Methods to compute when a value will be used again.
8 * Copyright (C) 2005 Universitaet Karlsruhe
9 * Released under the GPL
26 #include "irgraph_t.h"
27 #include "iredges_t.h"
34 #include "besched_t.h"
38 #include "benodesets.h"
40 #define SCAN_INTERBLOCK_USES
42 typedef struct _be_use_t {
54 unsigned visited_counter;
55 DEBUG_ONLY(firm_dbg_module_t *dbg;)
58 static int cmp_use(const void *a, const void *b, size_t n)
60 const be_use_t *p = a;
61 const be_use_t *q = b;
62 return !(p->block == q->block && p->node == q->node);
65 static be_next_use_t get_next_use(be_uses_t *env, ir_node *from,
66 unsigned from_step, const ir_node *def,
69 static const be_use_t *get_or_set_use_block(be_uses_t *env,
73 unsigned hash = HASH_COMBINE(nodeset_hash(block), nodeset_hash(def));
79 result = set_find(env->uses, &temp, sizeof(temp), hash);
82 // insert templ first as we might end in a loop in the get_next_use
84 temp.next_use = USES_INFINITY;
85 temp.outermost_loop = -1;
87 result = set_insert(env->uses, &temp, sizeof(temp), hash);
90 if(result->outermost_loop < 0 && result->visited < env->visited_counter) {
91 be_next_use_t next_use;
93 result->visited = env->visited_counter;
94 next_use = get_next_use(env, sched_first(block), 0, def, 0);
95 if(next_use.outermost_loop >= 0) {
96 result->next_use = next_use.time;
97 result->outermost_loop = next_use.outermost_loop;
98 DBG((env->dbg, LEVEL_5, "Setting nextuse of %+F in block %+F to %u (outermostloop %d)\n", def, block, result->next_use, result->outermost_loop));
105 static int be_is_phi_argument(const be_lv_t *lv, const ir_node *block, const ir_node *def)
108 ir_node *succ_block = NULL;
109 const ir_edge_t *edge;
113 if(get_irn_n_edges_kind(block, EDGE_KIND_BLOCK) > 1)
117 foreach_block_succ(block, edge) {
118 succ_block = get_edge_src_irn(edge);
122 arity = get_Block_n_cfgpreds(succ_block);
126 for(i = 0; i < arity; ++i) {
127 if(get_Block_cfgpred_block(succ_block, i) == block)
132 sched_foreach(succ_block, node) {
138 arg = get_irn_n(node, i);
146 static be_next_use_t get_next_use(be_uses_t *env, ir_node *from,
147 unsigned from_step, const ir_node *def,
150 unsigned step = from_step;
151 ir_node *block = get_nodes_block(from);
153 const ir_edge_t *edge;
157 from = sched_next(from);
160 sched_foreach_from(from, node) {
168 arity = get_irn_arity(node);
169 for (i = 0; i < arity; ++i) {
170 const ir_node *operand = get_irn_n(node, i);
172 if (operand == def) {
173 be_next_use_t result;
175 DBG((env->dbg, LEVEL_3, "found use of %+F at %+F\n", operand, node));
178 * Spills/Reloads are a special case, they're not really a
179 * usage of a value, continue searching
181 if (be_is_Spill(node) || be_is_Reload(node)) {
182 return be_get_next_use(env, node, step, node, 1);
186 result.outermost_loop = get_loop_depth(get_irn_loop(block));
194 if(be_is_phi_argument(env->lv, block, def)) {
195 // TODO we really should continue searching the uses of the phi,
196 // as a phi isn't a real use that implies a reload (because we could
197 // easily spill the whole phi)
199 be_next_use_t result;
201 result.outermost_loop = get_loop_depth(get_irn_loop(block));
205 #ifdef SCAN_INTERBLOCK_USES
207 unsigned next_use = USES_INFINITY;
209 be_next_use_t result;
210 ir_loop *loop = get_irn_loop(block);
211 int loopdepth = get_loop_depth(loop);
212 int found_visited = 0;
214 ir_graph *irg = get_irn_irg(block);
215 ir_node *startblock = get_irg_start_block(irg);
217 outermost_loop = loopdepth;
218 foreach_block_succ(block, edge) {
220 const ir_node *succ_block = get_edge_src_irn(edge);
224 if(succ_block == startblock)
227 DBG((env->dbg, LEVEL_5, "Checking succ of block %+F: %+F (for use of %+F)\n", block, succ_block, def));
228 if(!be_is_live_in(env->lv, succ_block, def)) {
229 //next_use = USES_INFINITY;
230 DBG((env->dbg, LEVEL_5, " not live in\n"));
234 use = get_or_set_use_block(env, succ_block, def);
235 DBG((env->dbg, LEVEL_5, "Found %u (loopdepth %d) (we're in block %+F)\n", use->next_use,
236 use->outermost_loop, block));
237 if(USES_IS_INFINITE(use->next_use)) {
238 if(use->outermost_loop < 0) {
245 use_dist = use->next_use;
247 succ_loop = get_irn_loop(succ_block);
248 if(get_loop_depth(succ_loop) < loopdepth) {
249 int factor = (loopdepth - get_loop_depth(succ_loop)) * 5000;
250 DBG((env->dbg, LEVEL_5, "Increase usestep because of loop out edge %d -> %d (%u)\n", factor));
251 // TODO we should use the number of nodes in the loop or so...
255 if(use_dist < next_use) {
257 outermost_loop = use->outermost_loop;
261 if(loopdepth < outermost_loop)
262 outermost_loop = loopdepth;
264 result.time = next_use + step;
265 result.outermost_loop = outermost_loop;
267 if(!found_use && found_visited) {
268 // the current result is correct for the current search, but isn't
269 // generally correct, so mark it
270 result.outermost_loop = -1;
272 DBG((env->dbg, LEVEL_5, "Result: %d (outerloop: %d)\n", result.time, result.outermost_loop));
276 return USES_INFINITY;
280 be_next_use_t be_get_next_use(be_uses_t *env, ir_node *from,
281 unsigned from_step, const ir_node *def,
284 env->visited_counter++;
285 return get_next_use(env, from, from_step, def, skip_from_uses);
288 be_uses_t *be_begin_uses(ir_graph *irg, const be_lv_t *lv)
290 be_uses_t *env = xmalloc(sizeof(env[0]));
294 env->uses = new_set(cmp_use, 512);
297 env->visited_counter = 0;
298 FIRM_DBG_REGISTER(env->dbg, "firm.be.uses");
303 void be_end_uses(be_uses_t *env)