2 * Copyright (C) 1995-2011 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
40 #include "irgraph_t.h"
41 #include "iredges_t.h"
53 #define UNKNOWN_OUTERMOST_LOOP ((unsigned)-1)
55 typedef struct be_use_t {
58 unsigned outermost_loop;
64 * The "uses" environment.
67 set *uses; /**< cache: contains all computed uses so far. */
68 ir_graph *irg; /**< the graph for this environment. */
69 const be_lv_t *lv; /**< the liveness for the graph. */
70 ir_visited_t visited_counter; /**< current search counter. */
71 DEBUG_ONLY(firm_dbg_module_t *dbg; /**< debug module for debug messages. */)
75 * Set-compare two uses.
77 static int cmp_use(const void *a, const void *b, size_t n)
79 const be_use_t *p = (const be_use_t*)a;
80 const be_use_t *q = (const be_use_t*)b;
83 return !(p->block == q->block && p->node == q->node);
86 static be_next_use_t get_next_use(be_uses_t *env, ir_node *from,
87 const ir_node *def, int skip_from_uses);
90 * Return the use for the given definition in the given block if exists,
93 * @param env the uses environment
94 * @param block the block we search the use in
95 * @param def the definition of the value we are searching
97 static const be_use_t *get_or_set_use_block(be_uses_t *env,
101 unsigned hash = HASH_COMBINE(hash_irn(block), hash_irn(def));
107 result = (be_use_t*)set_find(env->uses, &temp, sizeof(temp), hash);
109 if (result == NULL) {
110 // insert templ first as we might end in a loop in the get_next_use
112 temp.next_use = USES_INFINITY;
113 temp.outermost_loop = UNKNOWN_OUTERMOST_LOOP;
115 result = (be_use_t*)set_insert(env->uses, &temp, sizeof(temp), hash);
118 if (result->outermost_loop == UNKNOWN_OUTERMOST_LOOP && result->visited < env->visited_counter) {
119 be_next_use_t next_use;
121 result->visited = env->visited_counter;
122 next_use = get_next_use(env, sched_first(block), def, 0);
123 if (next_use.outermost_loop != UNKNOWN_OUTERMOST_LOOP) {
124 result->next_use = next_use.time;
125 result->outermost_loop = next_use.outermost_loop;
126 DBG((env->dbg, LEVEL_5, "Setting nextuse of %+F in block %+F to %u (outermostloop %d)\n",
127 def, block, result->next_use, result->outermost_loop));
135 * Check if a value of the given definition is used in the given block
138 * @param block the block to check
139 * @param def the definition of the value
141 * @return non-zero if the value is used in the given block as a Phi argument
142 * in one of its successor blocks.
144 static int be_is_phi_argument(const ir_node *block, const ir_node *def)
147 ir_node *succ_block = NULL;
151 if (get_irn_n_edges_kind(block, EDGE_KIND_BLOCK) < 1)
153 if (get_irn_n_edges_kind(block, EDGE_KIND_BLOCK) != 1)
157 succ_block = get_first_block_succ(block);
159 arity = get_Block_n_cfgpreds(succ_block);
161 /* no Phis in the successor */
165 /* find the index of block in its successor */
166 for (i = 0; i < arity; ++i) {
167 if (get_Block_cfgpred_block(succ_block, i) == block)
172 /* iterate over the Phi nodes in the successor and check if def is
173 * one of its arguments */
174 sched_foreach(succ_block, node) {
178 /* found first non-Phi node, we can stop the search here */
182 arg = get_irn_n(node, i);
191 * Retrieve the scheduled index (the "step") of this node in its
194 * @param node the node
196 static inline unsigned get_step(const ir_node *node)
198 return (unsigned)PTR_TO_INT(get_irn_link(node));
202 * Set the scheduled index (the "step") of this node in its
205 * @param node the node
206 * @param step the scheduled index of the node
208 static inline void set_step(ir_node *node, unsigned step)
210 set_irn_link(node, INT_TO_PTR(step));
214 * Find the next use of a value defined by def, starting at node from.
216 * @param env the uses environment
217 * @param from the node at which we should start the search
218 * @param def the definition of the value
219 * @param skip_from_uses if non-zero, ignore from uses
221 static be_next_use_t get_next_use(be_uses_t *env, ir_node *from,
222 const ir_node *def, int skip_from_uses)
225 ir_node *block = get_nodes_block(from);
226 ir_node *next_use_node;
229 unsigned next_use_step;
230 const ir_edge_t *edge;
232 assert(skip_from_uses == 0 || skip_from_uses == 1);
233 if (skip_from_uses) {
234 from = sched_next(from);
237 next_use_node = NULL;
238 next_use_step = INT_MAX;
239 timestep = get_step(from);
240 foreach_out_edge(def, edge) {
242 node = get_edge_src_irn(edge);
246 if (get_nodes_block(node) != block)
251 node_step = get_step(node);
252 if (node_step < timestep)
254 if (node_step < next_use_step) {
255 next_use_node = node;
256 next_use_step = node_step;
260 if (next_use_node != NULL) {
261 be_next_use_t result;
262 result.time = next_use_step - timestep + skip_from_uses;
263 result.outermost_loop = get_loop_depth(get_irn_loop(block));
264 result.before = next_use_node;
268 node = sched_last(block);
269 step = get_step(node) + 1 + timestep + skip_from_uses;
271 if (be_is_phi_argument(block, def)) {
272 // TODO we really should continue searching the uses of the phi,
273 // as a phi isn't a real use that implies a reload (because we could
274 // easily spill the whole phi)
276 be_next_use_t result;
278 result.outermost_loop = get_loop_depth(get_irn_loop(block));
279 result.before = block;
284 unsigned next_use = USES_INFINITY;
285 unsigned outermost_loop;
286 be_next_use_t result;
287 ir_loop *loop = get_irn_loop(block);
288 unsigned loopdepth = get_loop_depth(loop);
289 int found_visited = 0;
291 ir_graph *irg = get_irn_irg(block);
292 ir_node *startblock = get_irg_start_block(irg);
294 result.before = NULL;
295 outermost_loop = loopdepth;
296 foreach_block_succ(block, edge) {
298 const ir_node *succ_block = get_edge_src_irn(edge);
302 if (succ_block == startblock)
305 DBG((env->dbg, LEVEL_5, "Checking succ of block %+F: %+F (for use of %+F)\n", block, succ_block, def));
306 if (!be_is_live_in(env->lv, succ_block, def)) {
307 //next_use = USES_INFINITY;
308 DBG((env->dbg, LEVEL_5, " not live in\n"));
312 use = get_or_set_use_block(env, succ_block, def);
313 DBG((env->dbg, LEVEL_5, "Found %u (loopdepth %u) (we're in block %+F)\n", use->next_use,
314 use->outermost_loop, block));
315 if (USES_IS_INFINITE(use->next_use)) {
316 if (use->outermost_loop == UNKNOWN_OUTERMOST_LOOP) {
323 use_dist = use->next_use;
325 succ_loop = get_irn_loop(succ_block);
326 if (get_loop_depth(succ_loop) < loopdepth) {
327 unsigned factor = (loopdepth - get_loop_depth(succ_loop)) * 5000;
328 DBG((env->dbg, LEVEL_5, "Increase usestep because of loop out edge %d -> %d (%u)\n", factor));
329 // TODO we should use the number of nodes in the loop or so...
333 if (use_dist < next_use) {
335 outermost_loop = use->outermost_loop;
336 result.before = use->node;
340 if (loopdepth < outermost_loop)
341 outermost_loop = loopdepth;
343 result.time = next_use + step;
344 result.outermost_loop = outermost_loop;
346 if (!found_use && found_visited) {
347 // the current result is correct for the current search, but isn't
348 // generally correct, so mark it
349 result.outermost_loop = UNKNOWN_OUTERMOST_LOOP;
351 DBG((env->dbg, LEVEL_5, "Result: %d (outerloop: %u)\n", result.time, result.outermost_loop));
356 be_next_use_t be_get_next_use(be_uses_t *env, ir_node *from,
357 const ir_node *def, int skip_from_uses)
359 ++env->visited_counter;
360 return get_next_use(env, from, def, skip_from_uses);
364 * Pre-block walker, set the step number for every scheduled node
365 * in increasing order.
367 * After this, two scheduled nodes can be easily compared for the
368 * "scheduled earlier in block" property.
370 static void set_sched_step_walker(ir_node *block, void *data)
376 sched_foreach(block, node) {
377 set_step(node, step);
384 be_uses_t *be_begin_uses(ir_graph *irg, const be_lv_t *lv)
386 be_uses_t *env = XMALLOC(be_uses_t);
390 //set_using_irn_link(irg);
392 /* precalculate sched steps */
393 irg_block_walk_graph(irg, set_sched_step_walker, NULL, NULL);
395 env->uses = new_set(cmp_use, 512);
398 env->visited_counter = 0;
399 FIRM_DBG_REGISTER(env->dbg, "firm.be.uses");
404 void be_end_uses(be_uses_t *env)
406 //clear_using_irn_link(env->irg);