beuses.c 9.35 KB
Newer Older
Christian Würdig's avatar
Christian Würdig committed
1
/*
Michael Beck's avatar
Michael Beck committed
2
 * Copyright (C) 1995-2008 University of Karlsruhe.  All right reserved.
Christian Würdig's avatar
Christian Würdig committed
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
 *
 * This file is part of libFirm.
 *
 * This file may be distributed and/or modified under the terms of the
 * GNU General Public License version 2 as published by the Free Software
 * Foundation and appearing in the file LICENSE.GPL included in the
 * packaging of this file.
 *
 * Licensees holding valid libFirm Professional Edition licenses may use
 * this file in accordance with the libFirm Commercial License.
 * Agreement provided with the Software.
 *
 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE.
 */

Sebastian Hack's avatar
Sebastian Hack committed
20
/**
Christian Würdig's avatar
Christian Würdig committed
21
22
23
24
25
 * @file
 * @brief       Methods to compute when a value will be used again.
 * @author      Sebastian Hack, Matthias Braun
 * @date        27.06.2005
 * @version     $Id$
Sebastian Hack's avatar
Sebastian Hack committed
26
 */
27
#include "config.h"
Sebastian Hack's avatar
Sebastian Hack committed
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46

#include <limits.h>
#include <stdlib.h>

#include "config.h"
#include "obst.h"
#include "pmap.h"
#include "debug.h"

#include "irgwalk.h"
#include "irnode_t.h"
#include "ircons_t.h"
#include "irgraph_t.h"
#include "iredges_t.h"
#include "irdom_t.h"

#include "be_t.h"
#include "beutil.h"
#include "belive_t.h"
47
#include "benode.h"
48
#include "besched.h"
Sebastian Hack's avatar
Sebastian Hack committed
49
#include "beirgmod.h"
50
#include "bearch.h"
Christian Würdig's avatar
Christian Würdig committed
51
#include "beuses.h"
Sebastian Hack's avatar
Sebastian Hack committed
52

53
#define SCAN_INTERBLOCK_USES
Daniel Grund's avatar
Daniel Grund committed
54

Sebastian Hack's avatar
Sebastian Hack committed
55
typedef struct _be_use_t {
56
57
	const ir_node *block;
	const ir_node *node;
58
	int outermost_loop;
Daniel Grund's avatar
Daniel Grund committed
59
	unsigned next_use;
60
	unsigned visited;
Sebastian Hack's avatar
Sebastian Hack committed
61
62
63
} be_use_t;

struct _be_uses_t {
64
65
66
  	set *uses;
	ir_graph *irg;
	const be_lv_t *lv;
67
	unsigned visited_counter;
68
	DEBUG_ONLY(firm_dbg_module_t *dbg;)
Sebastian Hack's avatar
Sebastian Hack committed
69
70
71
72
};

static int cmp_use(const void *a, const void *b, size_t n)
{
73
74
	const be_use_t *p = a;
	const be_use_t *q = b;
75
76
	(void) n;

77
	return !(p->block == q->block && p->node == q->node);
Sebastian Hack's avatar
Sebastian Hack committed
78
79
}

80
81
82
83
84
static be_next_use_t get_next_use(be_uses_t *env, ir_node *from,
								  unsigned from_step, const ir_node *def,
								  int skip_from_uses);

static const be_use_t *get_or_set_use_block(be_uses_t *env,
85
86
                                            const ir_node *block,
                                            const ir_node *def)
Sebastian Hack's avatar
Sebastian Hack committed
87
{
88
	unsigned hash = HASH_COMBINE(hash_irn(block), hash_irn(def));
89
90
	be_use_t temp;
	be_use_t* result;
91

92
93
	temp.block = block;
	temp.node = def;
94
	result = set_find(env->uses, &temp, sizeof(temp), hash);
Sebastian Hack's avatar
Sebastian Hack committed
95

96
	if (result == NULL) {
97
98
99
		// insert templ first as we might end in a loop in the get_next_use
		// call otherwise
		temp.next_use = USES_INFINITY;
100
101
102
103
104
		temp.outermost_loop = -1;
		temp.visited = 0;
		result = set_insert(env->uses, &temp, sizeof(temp), hash);
	}

105
	if (result->outermost_loop < 0 && result->visited < env->visited_counter) {
106
		be_next_use_t next_use;
Sebastian Hack's avatar
Sebastian Hack committed
107

108
109
		result->visited = env->visited_counter;
		next_use = get_next_use(env, sched_first(block), 0, def, 0);
110
		if (next_use.outermost_loop >= 0) {
111
112
113
114
			result->next_use = next_use.time;
			result->outermost_loop = next_use.outermost_loop;
			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));
		}
115
	}
116

117
	return result;
Sebastian Hack's avatar
Sebastian Hack committed
118
119
}

120
static int be_is_phi_argument(const ir_node *block, const ir_node *def)
121
{
122
	ir_node *node;
Matthias Braun's avatar
Matthias Braun committed
123
	ir_node *succ_block = NULL;
124
125
126
	const ir_edge_t *edge;
	int arity, i;

127
128
129
130
#if 1
	if (get_irn_n_edges_kind(block, EDGE_KIND_BLOCK) < 1)
#else
	if (get_irn_n_edges_kind(block, EDGE_KIND_BLOCK) != 1)
131
#endif
132
		return 0;
133
134
135
136
137
138
139

	foreach_block_succ(block, edge) {
		succ_block = get_edge_src_irn(edge);
		break;
	}

	arity = get_Block_n_cfgpreds(succ_block);
140
	if (arity <= 1)
141
142
		return 0;

143
144
	for (i = 0; i < arity; ++i) {
		if (get_Block_cfgpred_block(succ_block, i) == block)
145
146
147
148
149
150
151
			break;
	}
	assert(i < arity);

	sched_foreach(succ_block, node) {
		ir_node *arg;

152
		if (!is_Phi(node))
153
154
155
			break;

		arg = get_irn_n(node, i);
156
		if (arg == def)
157
158
159
160
			return 1;
	}

	return 0;
161
162
}

163
static inline unsigned get_step(const ir_node *node)
164
165
166
167
{
	return PTR_TO_INT(get_irn_link(node));
}

168
169
170
static be_next_use_t get_next_use(be_uses_t *env, ir_node *from,
								  unsigned from_step, const ir_node *def,
								  int skip_from_uses)
Sebastian Hack's avatar
Sebastian Hack committed
171
{
172
	unsigned  step  = from_step;
173
174
175
176
	ir_node  *block = get_nodes_block(from);
	ir_node  *next_use;
	ir_node  *node;
	unsigned  timestep;
177
	unsigned  next_use_step;
178
	const ir_edge_t *edge;
Sebastian Hack's avatar
Sebastian Hack committed
179

180
181
#if 1
	assert(skip_from_uses == 0 || skip_from_uses == 1);
182
	if (skip_from_uses) {
183
184
185
186
187
188
189
190
191
192
		from = sched_next(from);
	}

	next_use      = NULL;
	next_use_step = INT_MAX;
	timestep      = get_step(from);
	foreach_out_edge(def, edge) {
		ir_node  *node = get_edge_src_irn(edge);
		unsigned  node_step;

193
		if (is_Anchor(node))
194
			continue;
195
		if (get_nodes_block(node) != block)
196
			continue;
197
		if (is_Phi(node))
198
199
200
			continue;

		node_step = get_step(node);
201
		if (node_step < timestep)
202
			continue;
203
		if (node_step < next_use_step) {
204
205
206
207
208
			next_use      = node;
			next_use_step = node_step;
		}
	}

209
	if (next_use != NULL) {
210
211
212
		be_next_use_t result;
		result.time           = next_use_step - timestep + skip_from_uses;
		result.outermost_loop = get_loop_depth(get_irn_loop(block));
213
		result.before         = next_use;
214
215
216
217
218
219
220
		return result;
	}

	node = sched_last(block);
	step = get_step(node) + 1 + timestep + skip_from_uses;

#else
221
	if (skip_from_uses) {
Michael Beck's avatar
BugFix:    
Michael Beck committed
222
		from = sched_next(from);
223
		++step;
224
	}
Sebastian Hack's avatar
Sebastian Hack committed
225

226
227
	sched_foreach_from(from, node) {
		int i, arity;
Christian Würdig's avatar
Christian Würdig committed
228

229
		if (is_Phi(node)) {
230
231
232
233
			step++;
			continue;
		}

234
235
236
		arity = get_irn_arity(node);
		for (i = 0; i < arity; ++i) {
			const ir_node *operand = get_irn_n(node, i);
Christian Würdig's avatar
Christian Würdig committed
237

238
			if (operand == def) {
Michael Beck's avatar
Michael Beck committed
239
240
				be_next_use_t result;

241
242
243
244
245
246
				DBG((env->dbg, LEVEL_3, "found use of %+F at %+F\n", operand, node));

				/**
				 * Spills/Reloads are a special case, they're not really a
				 * usage of a value, continue searching
				 */
Christian Würdig's avatar
Christian Würdig committed
247
				if (be_is_Spill(node) || be_is_Reload(node)) {
248
					return be_get_next_use(env, node, step, node, 1);
249
				}
250

251
				result.time           = step;
252
				result.outermost_loop = get_loop_depth(get_irn_loop(block));
253
				result.before         = node;
254
				return result;
Christian Würdig's avatar
Christian Würdig committed
255
256
257
258
259
			}
		}

		step++;
	}
260
#endif
Sebastian Hack's avatar
Sebastian Hack committed
261

262
	if (be_is_phi_argument(block, def)) {
263
264
265
		// TODO we really should continue searching the uses of the phi,
		// as a phi isn't a real use that implies a reload (because we could
		// easily spill the whole phi)
266
267

		be_next_use_t result;
268
		result.time           = step;
269
		result.outermost_loop = get_loop_depth(get_irn_loop(block));
270
		result.before         = block;
271
		return result;
272
	}
273
274
275

#ifdef SCAN_INTERBLOCK_USES
	{
276
	unsigned next_use   = USES_INFINITY;
277
278
	int outermost_loop;
	be_next_use_t result;
279
280
281
282
283
	ir_loop *loop       = get_irn_loop(block);
	int loopdepth       = get_loop_depth(loop);
	int found_visited   = 0;
	int found_use       = 0;
	ir_graph *irg       = get_irn_irg(block);
284
285
	ir_node *startblock = get_irg_start_block(irg);

286
	result.before  = NULL;
287
	outermost_loop = loopdepth;
288
289
290
	foreach_block_succ(block, edge) {
		const be_use_t *use;
		const ir_node *succ_block = get_edge_src_irn(edge);
291
		ir_loop *succ_loop;
292
		unsigned use_dist;
Christian Würdig's avatar
Christian Würdig committed
293

294
		if (succ_block == startblock)
295
			continue;
Sebastian Hack's avatar
Sebastian Hack committed
296

297
		DBG((env->dbg, LEVEL_5, "Checking succ of block %+F: %+F (for use of %+F)\n", block, succ_block, def));
298
		if (!be_is_live_in(env->lv, succ_block, def)) {
299
300
301
302
			//next_use = USES_INFINITY;
			DBG((env->dbg, LEVEL_5, "   not live in\n"));
			continue;
		}
303

304
305
306
		use = get_or_set_use_block(env, succ_block, def);
		DBG((env->dbg, LEVEL_5, "Found %u (loopdepth %d) (we're in block %+F)\n", use->next_use,
					use->outermost_loop, block));
307
308
		if (USES_IS_INFINITE(use->next_use)) {
			if (use->outermost_loop < 0) {
309
				found_visited = 1;
310
			}
311
312
			continue;
		}
313

314
315
		found_use = 1;
		use_dist = use->next_use;
316

317
		succ_loop = get_irn_loop(succ_block);
318
		if (get_loop_depth(succ_loop) < loopdepth) {
319
			unsigned factor = (loopdepth - get_loop_depth(succ_loop)) * 5000;
320
321
322
			DBG((env->dbg, LEVEL_5, "Increase usestep because of loop out edge %d -> %d (%u)\n", factor));
			// TODO we should use the number of nodes in the loop or so...
			use_dist += factor;
Sebastian Hack's avatar
Sebastian Hack committed
323
		}
324

325
		if (use_dist < next_use) {
326
			next_use       = use_dist;
327
			outermost_loop = use->outermost_loop;
328
			result.before  = use->node;
329
		}
Daniel Grund's avatar
Daniel Grund committed
330
	}
Sebastian Hack's avatar
Sebastian Hack committed
331

332
	if (loopdepth < outermost_loop)
333
		outermost_loop = loopdepth;
Sebastian Hack's avatar
Sebastian Hack committed
334

335
	result.time           = next_use + step;
336
	result.outermost_loop = outermost_loop;
Sebastian Hack's avatar
Sebastian Hack committed
337

338
	if (!found_use && found_visited) {
339
340
341
342
343
344
		// the current result is correct for the current search, but isn't
		// generally correct, so mark it
		result.outermost_loop = -1;
	}
	DBG((env->dbg, LEVEL_5, "Result: %d (outerloop: %d)\n", result.time, result.outermost_loop));
	return result;
345
346
347
348
	}
#else
	return USES_INFINITY;
#endif
Sebastian Hack's avatar
Sebastian Hack committed
349
350
}

351
352
353
354
355
356
357
358
be_next_use_t be_get_next_use(be_uses_t *env, ir_node *from,
                         unsigned from_step, const ir_node *def,
                         int skip_from_uses)
{
	env->visited_counter++;
	return get_next_use(env, from, from_step, def, skip_from_uses);
}

359
static void set_sched_step_walker(ir_node *block, void *data)
360
361
362
{
	ir_node  *node;
	unsigned step = 0;
363
	(void) data;
364
365
366

	sched_foreach(block, node) {
		set_irn_link(node, INT_TO_PTR(step));
367
		if (is_Phi(node))
368
369
370
371
372
			continue;
		++step;
	}
}

373
be_uses_t *be_begin_uses(ir_graph *irg, const be_lv_t *lv)
Sebastian Hack's avatar
Sebastian Hack committed
374
{
375
	be_uses_t *env = XMALLOC(be_uses_t);
Sebastian Hack's avatar
Sebastian Hack committed
376

377
	edges_assure(irg);
Sebastian Hack's avatar
Sebastian Hack committed
378

379
380
381
382
383
	//set_using_irn_link(irg);

	/* precalculate sched steps */
	irg_block_walk_graph(irg, set_sched_step_walker, NULL, NULL);

384
385
386
387
388
	env->uses = new_set(cmp_use, 512);
	env->irg = irg;
	env->lv = lv;
	env->visited_counter = 0;
	FIRM_DBG_REGISTER(env->dbg, "firm.be.uses");
Sebastian Hack's avatar
Sebastian Hack committed
389

390
	return env;
Sebastian Hack's avatar
Sebastian Hack committed
391
392
}

393
void be_end_uses(be_uses_t *env)
Sebastian Hack's avatar
Sebastian Hack committed
394
{
395
	//clear_using_irn_link(env->irg);
396
397
	del_set(env->uses);
	free(env);
Sebastian Hack's avatar
Sebastian Hack committed
398
}