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 Methods to compute when a value will be used again.
23 * @author Sebastian Hack, Matthias Braun
42 #include "irgraph_t.h"
43 #include "iredges_t.h"
50 #include "besched_t.h"
55 #define SCAN_INTERBLOCK_USES
57 typedef struct _be_use_t {
69 unsigned visited_counter;
70 DEBUG_ONLY(firm_dbg_module_t *dbg;)
73 static int cmp_use(const void *a, const void *b, size_t n)
75 const be_use_t *p = a;
76 const be_use_t *q = b;
79 return !(p->block == q->block && p->node == q->node);
82 static be_next_use_t get_next_use(be_uses_t *env, ir_node *from,
83 unsigned from_step, const ir_node *def,
86 static const be_use_t *get_or_set_use_block(be_uses_t *env,
90 unsigned hash = HASH_COMBINE(hash_irn(block), hash_irn(def));
96 result = set_find(env->uses, &temp, sizeof(temp), hash);
99 // insert templ first as we might end in a loop in the get_next_use
101 temp.next_use = USES_INFINITY;
102 temp.outermost_loop = -1;
104 result = set_insert(env->uses, &temp, sizeof(temp), hash);
107 if(result->outermost_loop < 0 && result->visited < env->visited_counter) {
108 be_next_use_t next_use;
110 result->visited = env->visited_counter;
111 next_use = get_next_use(env, sched_first(block), 0, def, 0);
112 if(next_use.outermost_loop >= 0) {
113 result->next_use = next_use.time;
114 result->outermost_loop = next_use.outermost_loop;
115 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));
122 static int be_is_phi_argument(const ir_node *block, const ir_node *def)
125 ir_node *succ_block = NULL;
126 const ir_edge_t *edge;
130 if(get_irn_n_edges_kind(block, EDGE_KIND_BLOCK) > 1)
134 foreach_block_succ(block, edge) {
135 succ_block = get_edge_src_irn(edge);
139 arity = get_Block_n_cfgpreds(succ_block);
143 for(i = 0; i < arity; ++i) {
144 if(get_Block_cfgpred_block(succ_block, i) == block)
149 sched_foreach(succ_block, node) {
155 arg = get_irn_n(node, i);
164 unsigned get_step(const ir_node *node)
166 return PTR_TO_INT(get_irn_link(node));
169 static be_next_use_t get_next_use(be_uses_t *env, ir_node *from,
170 unsigned from_step, const ir_node *def,
173 unsigned step = from_step;
174 ir_node *block = get_nodes_block(from);
178 unsigned next_use_step;
179 const ir_edge_t *edge;
182 assert(skip_from_uses == 0 || skip_from_uses == 1);
184 from = sched_next(from);
188 next_use_step = INT_MAX;
189 timestep = get_step(from);
190 foreach_out_edge(def, edge) {
191 ir_node *node = get_edge_src_irn(edge);
196 if(get_nodes_block(node) != block)
201 node_step = get_step(node);
202 if(node_step < timestep)
204 if(node_step < next_use_step) {
206 next_use_step = node_step;
210 if(next_use != NULL) {
211 be_next_use_t result;
212 result.time = next_use_step - timestep + skip_from_uses;
213 result.outermost_loop = get_loop_depth(get_irn_loop(block));
214 result.before = next_use;
218 node = sched_last(block);
219 step = get_step(node) + 1 + timestep + skip_from_uses;
223 from = sched_next(from);
227 sched_foreach_from(from, node) {
235 arity = get_irn_arity(node);
236 for (i = 0; i < arity; ++i) {
237 const ir_node *operand = get_irn_n(node, i);
239 if (operand == def) {
240 be_next_use_t result;
242 DBG((env->dbg, LEVEL_3, "found use of %+F at %+F\n", operand, node));
245 * Spills/Reloads are a special case, they're not really a
246 * usage of a value, continue searching
248 if (be_is_Spill(node) || be_is_Reload(node)) {
249 return be_get_next_use(env, node, step, node, 1);
253 result.outermost_loop = get_loop_depth(get_irn_loop(block));
254 result.before = node;
263 if(be_is_phi_argument(block, def)) {
264 // TODO we really should continue searching the uses of the phi,
265 // as a phi isn't a real use that implies a reload (because we could
266 // easily spill the whole phi)
268 be_next_use_t result;
270 result.outermost_loop = get_loop_depth(get_irn_loop(block));
271 result.before = block;
275 #ifdef SCAN_INTERBLOCK_USES
277 unsigned next_use = USES_INFINITY;
279 be_next_use_t result;
280 ir_loop *loop = get_irn_loop(block);
281 int loopdepth = get_loop_depth(loop);
282 int found_visited = 0;
284 ir_graph *irg = get_irn_irg(block);
285 ir_node *startblock = get_irg_start_block(irg);
287 result.before = NULL;
288 outermost_loop = loopdepth;
289 foreach_block_succ(block, edge) {
291 const ir_node *succ_block = get_edge_src_irn(edge);
295 if(succ_block == startblock)
298 DBG((env->dbg, LEVEL_5, "Checking succ of block %+F: %+F (for use of %+F)\n", block, succ_block, def));
299 if(!be_is_live_in(env->lv, succ_block, def)) {
300 //next_use = USES_INFINITY;
301 DBG((env->dbg, LEVEL_5, " not live in\n"));
305 use = get_or_set_use_block(env, succ_block, def);
306 DBG((env->dbg, LEVEL_5, "Found %u (loopdepth %d) (we're in block %+F)\n", use->next_use,
307 use->outermost_loop, block));
308 if(USES_IS_INFINITE(use->next_use)) {
309 if(use->outermost_loop < 0) {
316 use_dist = use->next_use;
318 succ_loop = get_irn_loop(succ_block);
319 if(get_loop_depth(succ_loop) < loopdepth) {
320 unsigned factor = (loopdepth - get_loop_depth(succ_loop)) * 5000;
321 DBG((env->dbg, LEVEL_5, "Increase usestep because of loop out edge %d -> %d (%u)\n", factor));
322 // TODO we should use the number of nodes in the loop or so...
326 if(use_dist < next_use) {
328 outermost_loop = use->outermost_loop;
329 result.before = use->node;
333 if(loopdepth < outermost_loop)
334 outermost_loop = loopdepth;
336 result.time = next_use + step;
337 result.outermost_loop = outermost_loop;
339 if(!found_use && found_visited) {
340 // the current result is correct for the current search, but isn't
341 // generally correct, so mark it
342 result.outermost_loop = -1;
344 DBG((env->dbg, LEVEL_5, "Result: %d (outerloop: %d)\n", result.time, result.outermost_loop));
348 return USES_INFINITY;
352 be_next_use_t be_get_next_use(be_uses_t *env, ir_node *from,
353 unsigned from_step, const ir_node *def,
356 env->visited_counter++;
357 return get_next_use(env, from, from_step, def, skip_from_uses);
361 void set_sched_step_walker(ir_node *block, void *data)
367 sched_foreach(block, node) {
368 set_irn_link(node, INT_TO_PTR(step));
377 be_uses_t *be_begin_uses(ir_graph *irg, const be_lv_t *lv)
379 be_uses_t *env = xmalloc(sizeof(env[0]));
383 //set_using_irn_link(irg);
385 /* precalculate sched steps */
386 irg_block_walk_graph(irg, set_sched_step_walker, NULL, NULL);
388 env->uses = new_set(cmp_use, 512);
391 env->visited_counter = 0;
392 FIRM_DBG_REGISTER(env->dbg, "firm.be.uses");
397 void be_end_uses(be_uses_t *env)
399 //clear_using_irn_link(env->irg);