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"
54 #define UNKNOWN_OUTERMOST_LOOP ((unsigned)-1)
56 typedef struct be_use_t {
59 unsigned outermost_loop;
65 * The "uses" environment.
68 set *uses; /**< cache: contains all computed uses so far. */
69 ir_graph *irg; /**< the graph for this environment. */
70 const be_lv_t *lv; /**< the liveness for the graph. */
71 ir_visited_t visited_counter; /**< current search counter. */
72 DEBUG_ONLY(firm_dbg_module_t *dbg; /**< debug module for debug messages. */)
76 * Set-compare two uses.
78 static int cmp_use(const void *a, const void *b, size_t n)
80 const be_use_t *p = (const be_use_t*)a;
81 const be_use_t *q = (const be_use_t*)b;
84 return !(p->block == q->block && p->node == q->node);
87 static be_next_use_t get_next_use(be_uses_t *env, ir_node *from,
88 const ir_node *def, int skip_from_uses);
91 * Return the use for the given definition in the given block if exists,
94 * @param env the uses environment
95 * @param block the block we search the use in
96 * @param def the definition of the value we are searching
98 static const be_use_t *get_or_set_use_block(be_uses_t *env,
102 unsigned hash = HASH_COMBINE(hash_irn(block), hash_irn(def));
108 result = (be_use_t*)set_find(env->uses, &temp, sizeof(temp), hash);
110 if (result == NULL) {
111 // insert templ first as we might end in a loop in the get_next_use
113 temp.next_use = USES_INFINITY;
114 temp.outermost_loop = UNKNOWN_OUTERMOST_LOOP;
116 result = (be_use_t*)set_insert(env->uses, &temp, sizeof(temp), hash);
119 if (result->outermost_loop == UNKNOWN_OUTERMOST_LOOP && result->visited < env->visited_counter) {
120 be_next_use_t next_use;
122 result->visited = env->visited_counter;
123 next_use = get_next_use(env, sched_first(block), def, 0);
124 if (next_use.outermost_loop != UNKNOWN_OUTERMOST_LOOP) {
125 result->next_use = next_use.time;
126 result->outermost_loop = next_use.outermost_loop;
127 DBG((env->dbg, LEVEL_5, "Setting nextuse of %+F in block %+F to %u (outermostloop %d)\n",
128 def, block, result->next_use, result->outermost_loop));
136 * Check if a value of the given definition is used in the given block
139 * @param block the block to check
140 * @param def the definition of the value
142 * @return non-zero if the value is used in the given block as a Phi argument
143 * in one of its successor blocks.
145 static int be_is_phi_argument(const ir_node *block, const ir_node *def)
148 ir_node *succ_block = NULL;
152 if (get_irn_n_edges_kind(block, EDGE_KIND_BLOCK) < 1)
154 if (get_irn_n_edges_kind(block, EDGE_KIND_BLOCK) != 1)
158 succ_block = get_first_block_succ(block);
160 arity = get_Block_n_cfgpreds(succ_block);
162 /* no Phis in the successor */
166 /* find the index of block in its successor */
167 for (i = 0; i < arity; ++i) {
168 if (get_Block_cfgpred_block(succ_block, i) == block)
173 /* iterate over the Phi nodes in the successor and check if def is
174 * one of its arguments */
175 sched_foreach(succ_block, node) {
179 /* found first non-Phi node, we can stop the search here */
183 arg = get_irn_n(node, i);
192 * Retrieve the scheduled index (the "step") of this node in its
195 * @param node the node
197 static inline unsigned get_step(const ir_node *node)
199 return (unsigned)PTR_TO_INT(get_irn_link(node));
203 * Set the scheduled index (the "step") of this node in its
206 * @param node the node
207 * @param step the scheduled index of the node
209 static inline void set_step(ir_node *node, unsigned step)
211 set_irn_link(node, INT_TO_PTR(step));
215 * Find the next use of a value defined by def, starting at node from.
217 * @param env the uses environment
218 * @param from the node at which we should start the search
219 * @param def the definition of the value
220 * @param skip_from_uses if non-zero, ignore from uses
222 static be_next_use_t get_next_use(be_uses_t *env, ir_node *from,
223 const ir_node *def, int skip_from_uses)
226 ir_node *block = get_nodes_block(from);
227 ir_node *next_use_node;
230 unsigned next_use_step;
231 const ir_edge_t *edge;
233 assert(skip_from_uses == 0 || skip_from_uses == 1);
234 if (skip_from_uses) {
235 from = sched_next(from);
238 next_use_node = NULL;
239 next_use_step = INT_MAX;
240 timestep = get_step(from);
241 foreach_out_edge(def, edge) {
243 node = get_edge_src_irn(edge);
247 if (get_nodes_block(node) != block)
252 node_step = get_step(node);
253 if (node_step < timestep)
255 if (node_step < next_use_step) {
256 next_use_node = node;
257 next_use_step = node_step;
261 if (next_use_node != NULL) {
262 be_next_use_t result;
263 result.time = next_use_step - timestep + skip_from_uses;
264 result.outermost_loop = get_loop_depth(get_irn_loop(block));
265 result.before = next_use_node;
269 node = sched_last(block);
270 step = get_step(node) + 1 + timestep + skip_from_uses;
272 if (be_is_phi_argument(block, def)) {
273 // TODO we really should continue searching the uses of the phi,
274 // as a phi isn't a real use that implies a reload (because we could
275 // easily spill the whole phi)
277 be_next_use_t result;
279 result.outermost_loop = get_loop_depth(get_irn_loop(block));
280 result.before = block;
285 unsigned next_use = USES_INFINITY;
286 unsigned outermost_loop;
287 be_next_use_t result;
288 ir_loop *loop = get_irn_loop(block);
289 unsigned loopdepth = get_loop_depth(loop);
290 int found_visited = 0;
292 ir_graph *irg = get_irn_irg(block);
293 ir_node *startblock = get_irg_start_block(irg);
295 result.before = NULL;
296 outermost_loop = loopdepth;
297 foreach_block_succ(block, edge) {
299 const ir_node *succ_block = get_edge_src_irn(edge);
303 if (succ_block == startblock)
306 DBG((env->dbg, LEVEL_5, "Checking succ of block %+F: %+F (for use of %+F)\n", block, succ_block, def));
307 if (!be_is_live_in(env->lv, succ_block, def)) {
308 //next_use = USES_INFINITY;
309 DBG((env->dbg, LEVEL_5, " not live in\n"));
313 use = get_or_set_use_block(env, succ_block, def);
314 DBG((env->dbg, LEVEL_5, "Found %u (loopdepth %u) (we're in block %+F)\n", use->next_use,
315 use->outermost_loop, block));
316 if (USES_IS_INFINITE(use->next_use)) {
317 if (use->outermost_loop == UNKNOWN_OUTERMOST_LOOP) {
324 use_dist = use->next_use;
326 succ_loop = get_irn_loop(succ_block);
327 if (get_loop_depth(succ_loop) < loopdepth) {
328 unsigned factor = (loopdepth - get_loop_depth(succ_loop)) * 5000;
329 DBG((env->dbg, LEVEL_5, "Increase usestep because of loop out edge %d -> %d (%u)\n", factor));
330 // TODO we should use the number of nodes in the loop or so...
334 if (use_dist < next_use) {
336 outermost_loop = use->outermost_loop;
337 result.before = use->node;
341 if (loopdepth < outermost_loop)
342 outermost_loop = loopdepth;
344 result.time = next_use + step;
345 result.outermost_loop = outermost_loop;
347 if (!found_use && found_visited) {
348 // the current result is correct for the current search, but isn't
349 // generally correct, so mark it
350 result.outermost_loop = UNKNOWN_OUTERMOST_LOOP;
352 DBG((env->dbg, LEVEL_5, "Result: %d (outerloop: %u)\n", result.time, result.outermost_loop));
357 be_next_use_t be_get_next_use(be_uses_t *env, ir_node *from,
358 const ir_node *def, int skip_from_uses)
360 ++env->visited_counter;
361 return get_next_use(env, from, def, skip_from_uses);
365 * Pre-block walker, set the step number for every scheduled node
366 * in increasing order.
368 * After this, two scheduled nodes can be easily compared for the
369 * "scheduled earlier in block" property.
371 static void set_sched_step_walker(ir_node *block, void *data)
377 sched_foreach(block, node) {
378 set_step(node, step);
385 be_uses_t *be_begin_uses(ir_graph *irg, const be_lv_t *lv)
387 be_uses_t *env = XMALLOC(be_uses_t);
391 //set_using_irn_link(irg);
393 /* precalculate sched steps */
394 irg_block_walk_graph(irg, set_sched_step_walker, NULL, NULL);
396 env->uses = new_set(cmp_use, 512);
399 env->visited_counter = 0;
400 FIRM_DBG_REGISTER(env->dbg, "firm.be.uses");
405 void be_end_uses(be_uses_t *env)
407 //clear_using_irn_link(env->irg);