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 typedef struct be_use_t {
62 * The "uses" environment.
65 set *uses; /**< cache: contains all computed uses so far. */
66 ir_graph *irg; /**< the graph for this environment. */
67 const be_lv_t *lv; /**< the liveness for the graph. */
68 ir_visited_t visited_counter; /**< current search counter. */
69 DEBUG_ONLY(firm_dbg_module_t *dbg; /**< debug module for debug messages. */)
73 * Set-compare two uses.
75 static int cmp_use(const void *a, const void *b, size_t n)
77 const be_use_t *p = (const be_use_t*)a;
78 const be_use_t *q = (const be_use_t*)b;
81 return !(p->block == q->block && p->node == q->node);
84 static be_next_use_t get_next_use(be_uses_t *env, ir_node *from,
85 const ir_node *def, int skip_from_uses);
88 * Return the use for the given definition in the given block if exists,
91 * @param env the uses environment
92 * @param block the block we search the use in
93 * @param def the definition of the value we are searching
95 static const be_use_t *get_or_set_use_block(be_uses_t *env,
99 unsigned hash = HASH_COMBINE(hash_irn(block), hash_irn(def));
105 result = (be_use_t*)set_find(env->uses, &temp, sizeof(temp), hash);
107 if (result == NULL) {
108 // insert templ first as we might end in a loop in the get_next_use
110 temp.next_use = USES_INFINITY;
111 temp.outermost_loop = -1;
113 result = (be_use_t*)set_insert(env->uses, &temp, sizeof(temp), hash);
116 if (result->outermost_loop < 0 && result->visited < env->visited_counter) {
117 be_next_use_t next_use;
119 result->visited = env->visited_counter;
120 next_use = get_next_use(env, sched_first(block), def, 0);
121 if (next_use.outermost_loop >= 0) {
122 result->next_use = next_use.time;
123 result->outermost_loop = next_use.outermost_loop;
124 DBG((env->dbg, LEVEL_5, "Setting nextuse of %+F in block %+F to %u (outermostloop %d)\n",
125 def, block, result->next_use, result->outermost_loop));
133 * Check if a value of the given definition is used in the given block
136 * @param block the block to check
137 * @param def the definition of the value
139 * @return non-zero if the value is used in the given block as a Phi argument
140 * in one of its successor blocks.
142 static int be_is_phi_argument(const ir_node *block, const ir_node *def)
145 ir_node *succ_block = NULL;
149 if (get_irn_n_edges_kind(block, EDGE_KIND_BLOCK) < 1)
151 if (get_irn_n_edges_kind(block, EDGE_KIND_BLOCK) != 1)
155 succ_block = get_first_block_succ(block);
157 arity = get_Block_n_cfgpreds(succ_block);
159 /* no Phis in the successor */
163 /* find the index of block in its successor */
164 for (i = 0; i < arity; ++i) {
165 if (get_Block_cfgpred_block(succ_block, i) == block)
170 /* iterate over the Phi nodes in the successor and check if def is
171 * one of its arguments */
172 sched_foreach(succ_block, node) {
176 /* found first non-Phi node, we can stop the search here */
180 arg = get_irn_n(node, i);
189 * Retrieve the scheduled index (the "step") of this node in its
192 * @param node the node
194 static inline unsigned get_step(const ir_node *node)
196 return (unsigned)PTR_TO_INT(get_irn_link(node));
200 * Set the scheduled index (the "step") of this node in its
203 * @param node the node
204 * @param step the scheduled index of the node
206 static inline void set_step(ir_node *node, unsigned step)
208 set_irn_link(node, INT_TO_PTR(step));
212 * Find the next use of a value defined by def, starting at node from.
214 * @param env the uses environment
215 * @param from the node at which we should start the search
216 * @param def the definition of the value
217 * @param skip_from_uses if non-zero, ignore from uses
219 static be_next_use_t get_next_use(be_uses_t *env, ir_node *from,
220 const ir_node *def, int skip_from_uses)
223 ir_node *block = get_nodes_block(from);
227 unsigned next_use_step;
228 const ir_edge_t *edge;
230 assert(skip_from_uses == 0 || skip_from_uses == 1);
231 if (skip_from_uses) {
232 from = sched_next(from);
236 next_use_step = INT_MAX;
237 timestep = get_step(from);
238 foreach_out_edge(def, edge) {
239 ir_node *node = get_edge_src_irn(edge);
244 if (get_nodes_block(node) != block)
249 node_step = get_step(node);
250 if (node_step < timestep)
252 if (node_step < next_use_step) {
254 next_use_step = node_step;
258 if (next_use != NULL) {
259 be_next_use_t result;
260 result.time = next_use_step - timestep + skip_from_uses;
261 result.outermost_loop = get_loop_depth(get_irn_loop(block));
262 result.before = next_use;
266 node = sched_last(block);
267 step = get_step(node) + 1 + timestep + skip_from_uses;
269 if (be_is_phi_argument(block, def)) {
270 // TODO we really should continue searching the uses of the phi,
271 // as a phi isn't a real use that implies a reload (because we could
272 // easily spill the whole phi)
274 be_next_use_t result;
276 result.outermost_loop = get_loop_depth(get_irn_loop(block));
277 result.before = block;
282 unsigned next_use = USES_INFINITY;
284 be_next_use_t result;
285 ir_loop *loop = get_irn_loop(block);
286 int loopdepth = get_loop_depth(loop);
287 int found_visited = 0;
289 ir_graph *irg = get_irn_irg(block);
290 ir_node *startblock = get_irg_start_block(irg);
292 result.before = NULL;
293 outermost_loop = loopdepth;
294 foreach_block_succ(block, edge) {
296 const ir_node *succ_block = get_edge_src_irn(edge);
300 if (succ_block == startblock)
303 DBG((env->dbg, LEVEL_5, "Checking succ of block %+F: %+F (for use of %+F)\n", block, succ_block, def));
304 if (!be_is_live_in(env->lv, succ_block, def)) {
305 //next_use = USES_INFINITY;
306 DBG((env->dbg, LEVEL_5, " not live in\n"));
310 use = get_or_set_use_block(env, succ_block, def);
311 DBG((env->dbg, LEVEL_5, "Found %u (loopdepth %d) (we're in block %+F)\n", use->next_use,
312 use->outermost_loop, block));
313 if (USES_IS_INFINITE(use->next_use)) {
314 if (use->outermost_loop < 0) {
321 use_dist = use->next_use;
323 succ_loop = get_irn_loop(succ_block);
324 if (get_loop_depth(succ_loop) < loopdepth) {
325 unsigned factor = (loopdepth - get_loop_depth(succ_loop)) * 5000;
326 DBG((env->dbg, LEVEL_5, "Increase usestep because of loop out edge %d -> %d (%u)\n", factor));
327 // TODO we should use the number of nodes in the loop or so...
331 if (use_dist < next_use) {
333 outermost_loop = use->outermost_loop;
334 result.before = use->node;
338 if (loopdepth < outermost_loop)
339 outermost_loop = loopdepth;
341 result.time = next_use + step;
342 result.outermost_loop = outermost_loop;
344 if (!found_use && found_visited) {
345 // the current result is correct for the current search, but isn't
346 // generally correct, so mark it
347 result.outermost_loop = -1;
349 DBG((env->dbg, LEVEL_5, "Result: %d (outerloop: %d)\n", result.time, result.outermost_loop));
354 be_next_use_t be_get_next_use(be_uses_t *env, ir_node *from,
355 const ir_node *def, int skip_from_uses)
357 ++env->visited_counter;
358 return get_next_use(env, from, def, skip_from_uses);
362 * Pre-block walker, set the step number for every scheduled node
363 * in increasing order.
365 * After this, two scheduled nodes can be easily compared for the
366 * "scheduled earlier in block" property.
368 static void set_sched_step_walker(ir_node *block, void *data)
374 sched_foreach(block, node) {
375 set_step(node, step);
382 be_uses_t *be_begin_uses(ir_graph *irg, const be_lv_t *lv)
384 be_uses_t *env = XMALLOC(be_uses_t);
388 //set_using_irn_link(irg);
390 /* precalculate sched steps */
391 irg_block_walk_graph(irg, set_sched_step_walker, NULL, NULL);
393 env->uses = new_set(cmp_use, 512);
396 env->visited_counter = 0;
397 FIRM_DBG_REGISTER(env->dbg, "firm.be.uses");
402 void be_end_uses(be_uses_t *env)
404 //clear_using_irn_link(env->irg);