ldstopt.c 57.1 KB
Newer Older
Christian Würdig's avatar
Christian Würdig committed
1
/*
2
 * Copyright (C) 1995-2011 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.
 */

Michael Beck's avatar
Michael Beck committed
20
21
22
23
/**
 * @file
 * @brief   Load/Store optimizations.
 * @author  Michael Beck
Michael Beck's avatar
Michael Beck committed
24
 */
Matthias Braun's avatar
Matthias Braun committed
25
#include "config.h"
Michael Beck's avatar
Michael Beck committed
26

27
#include <string.h>
Michael Beck's avatar
Michael Beck committed
28

29
#include "iroptimize.h"
30
31
32
33
34
35
36
#include "irnode_t.h"
#include "irgraph_t.h"
#include "irmode_t.h"
#include "iropt_t.h"
#include "ircons_t.h"
#include "irgmod.h"
#include "irgwalk.h"
37
#include "irtools.h"
38
39
40
41
#include "tv_t.h"
#include "dbginfo_t.h"
#include "iropt_dbg.h"
#include "irflag_t.h"
42
#include "array_t.h"
43
#include "irhooks.h"
Michael Beck's avatar
BugFix:    
Michael Beck committed
44
#include "iredges.h"
45
#include "irpass.h"
46
#include "irmemory.h"
47
#include "irnodehashmap.h"
48
#include "irgopt.h"
49
#include "set.h"
Matthias Braun's avatar
Matthias Braun committed
50
#include "be.h"
51
52
53
54
#include "debug.h"

/** The debug handle. */
DEBUG_ONLY(static firm_dbg_module_t *dbg;)
55

Michael Beck's avatar
Michael Beck committed
56
#undef IMAX
57
#define IMAX(a,b)   ((a) > (b) ? (a) : (b))
Michael Beck's avatar
Michael Beck committed
58

59
#define MAX_PROJ    IMAX(IMAX((long)pn_Load_max, (long)pn_Store_max), (long)pn_Call_max)
Michael Beck's avatar
Michael Beck committed
60

61
enum changes_t {
62
63
	DF_CHANGED = 1,       /**< data flow changed */
	CF_CHANGED = 2,       /**< control flow changed */
64
65
};

Michael Beck's avatar
Michael Beck committed
66
67
68
/**
 * walker environment
 */
69
typedef struct walk_env_t {
70
71
	struct obstack obst;          /**< list of all stores */
	unsigned changes;             /**< a bitmask of graph changes */
Michael Beck's avatar
Michael Beck committed
72
73
} walk_env_t;

74
/** A Load/Store info. */
75
typedef struct ldst_info_t {
76
	ir_node  *projs[MAX_PROJ+1];  /**< list of Proj's of this node */
77
78
79
	ir_node  *exc_block;          /**< the exception block if available */
	int      exc_idx;             /**< predecessor index in the exception block */
	unsigned visited;             /**< visited counter for breaking loops */
Michael Beck's avatar
Michael Beck committed
80
81
} ldst_info_t;

82
/**
83
 * flags for control flow.
84
85
 */
enum block_flags_t {
86
87
	BLOCK_HAS_COND = 1,      /**< Block has conditional control flow */
	BLOCK_HAS_EXC  = 2       /**< Block has exceptional control flow */
88
89
90
};

/**
91
 * a Block info.
92
 */
93
typedef struct block_info_t {
94
	unsigned flags;               /**< flags for the block */
95
96
} block_info_t;

97
98
99
100
101
102
103
/** the master visited flag for loop detection. */
static unsigned master_visited = 0;

#define INC_MASTER()       ++master_visited
#define MARK_NODE(info)    (info)->visited = master_visited
#define NODE_VISITED(info) (info)->visited >= master_visited

Michael Beck's avatar
Michael Beck committed
104
105
106
/**
 * get the Load/Store info of a node
 */
107
108
static ldst_info_t *get_ldst_info(ir_node *node, struct obstack *obst)
{
109
	ldst_info_t *info = (ldst_info_t*)get_irn_link(node);
Michael Beck's avatar
Michael Beck committed
110

111
	if (! info) {
112
		info = OALLOCZ(obst, ldst_info_t);
113
114
115
116
		set_irn_link(node, info);
	}
	return info;
}  /* get_ldst_info */
Michael Beck's avatar
Michael Beck committed
117

118
119
120
/**
 * get the Block info of a node
 */
121
122
static block_info_t *get_block_info(ir_node *node, struct obstack *obst)
{
123
	block_info_t *info = (block_info_t*)get_irn_link(node);
124

125
	if (! info) {
126
		info = OALLOCZ(obst, block_info_t);
127
128
129
130
		set_irn_link(node, info);
	}
	return info;
}  /* get_block_info */
131

Michael Beck's avatar
Michael Beck committed
132
/**
Michael Beck's avatar
Michael Beck committed
133
 * update the projection info for a Load/Store
Michael Beck's avatar
Michael Beck committed
134
 */
135
static unsigned update_projs(ldst_info_t *info, ir_node *proj)
Michael Beck's avatar
Michael Beck committed
136
{
137
	long nr = get_Proj_proj(proj);
Michael Beck's avatar
Michael Beck committed
138

139
	assert(0 <= nr && nr <= MAX_PROJ && "Wrong proj from LoadStore");
Michael Beck's avatar
Michael Beck committed
140

141
142
143
144
145
146
147
148
149
150
	if (info->projs[nr]) {
		/* there is already one, do CSE */
		exchange(proj, info->projs[nr]);
		return DF_CHANGED;
	}
	else {
		info->projs[nr] = proj;
		return 0;
	}
}  /* update_projs */
Michael Beck's avatar
Michael Beck committed
151
152

/**
153
154
155
156
157
 * update the exception block info for a Load/Store node.
 *
 * @param info   the load/store info struct
 * @param block  the exception handler block for this load/store
 * @param pos    the control flow input of the block
Michael Beck's avatar
Michael Beck committed
158
 */
159
static unsigned update_exc(ldst_info_t *info, ir_node *block, int pos)
Michael Beck's avatar
Michael Beck committed
160
{
161
	assert(info->exc_block == NULL && "more than one exception block found");
Michael Beck's avatar
Michael Beck committed
162

163
164
165
166
	info->exc_block = block;
	info->exc_idx   = pos;
	return 0;
}  /* update_exc */
Michael Beck's avatar
Michael Beck committed
167
168
169

/**
 * walker, collects all Load/Store/Proj nodes
170
 *
171
 * walks from Start -> End
Michael Beck's avatar
Michael Beck committed
172
 */
Michael Beck's avatar
Michael Beck committed
173
static void collect_nodes(ir_node *node, void *env)
Michael Beck's avatar
Michael Beck committed
174
{
175
176
	walk_env_t  *wenv   = (walk_env_t *)env;
	unsigned     opcode = get_irn_opcode(node);
177
178
179
	ir_node     *pred, *blk, *pred_blk;
	ldst_info_t *ldst_info;

180
181
182
	if (opcode == iro_Proj) {
		pred   = get_Proj_pred(node);
		opcode = get_irn_opcode(pred);
183

184
		if (opcode == iro_Load || opcode == iro_Store || opcode == iro_Call) {
185
			ldst_info = get_ldst_info(pred, &wenv->obst);
186
187
188
189

			wenv->changes |= update_projs(ldst_info, node);

			/*
190
191
192
193
194
			 * Place the Proj's to the same block as the
			 * predecessor Load. This is always ok and prevents
			 * "non-SSA" form after optimizations if the Proj
			 * is in a wrong block.
			 */
195
196
197
198
199
200
201
			blk      = get_nodes_block(node);
			pred_blk = get_nodes_block(pred);
			if (blk != pred_blk) {
				wenv->changes |= DF_CHANGED;
				set_nodes_block(node, pred_blk);
			}
		}
202
	} else if (opcode == iro_Block) {
203
204
205
		int i;

		for (i = get_Block_n_cfgpreds(node) - 1; i >= 0; --i) {
206
			ir_node      *pred_block, *proj;
207
			block_info_t *bl_info;
208
209
210
			int          is_exc = 0;

			pred = proj = get_Block_cfgpred(node, i);
211

212
213
			if (is_Proj(proj)) {
				pred   = get_Proj_pred(proj);
Matthias Braun's avatar
Matthias Braun committed
214
				is_exc = is_x_except_Proj(proj);
215
			}
216
217
218
219
220
221

			/* ignore Bad predecessors, they will be removed later */
			if (is_Bad(pred))
				continue;

			pred_block = get_nodes_block(pred);
222
			bl_info    = get_block_info(pred_block, &wenv->obst);
223

224
			if (is_fragile_op(pred) && is_exc)
225
226
227
228
				bl_info->flags |= BLOCK_HAS_EXC;
			else if (is_irn_forking(pred))
				bl_info->flags |= BLOCK_HAS_COND;

229
230
			opcode = get_irn_opcode(pred);
			if (is_exc && (opcode == iro_Load || opcode == iro_Store || opcode == iro_Call)) {
231
				ldst_info = get_ldst_info(pred, &wenv->obst);
232
233
234
235
236
237

				wenv->changes |= update_exc(ldst_info, node, i);
			}
		}
	}
}  /* collect_nodes */
Michael Beck's avatar
Michael Beck committed
238

Michael Beck's avatar
Michael Beck committed
239
/**
240
 * Returns an entity if the address ptr points to a constant one.
241
242
243
244
 *
 * @param ptr  the address
 *
 * @return an entity or NULL
Michael Beck's avatar
Michael Beck committed
245
 */
246
static ir_entity *find_constant_entity(ir_node *ptr)
Michael Beck's avatar
Michael Beck committed
247
{
248
	for (;;) {
249
		if (is_SymConst(ptr) && get_SymConst_kind(ptr) == symconst_addr_ent) {
250
			return get_SymConst_entity(ptr);
251
		} else if (is_Sel(ptr)) {
252
253
254
255
256
257
258
259
260
261
262
263
264
265
			ir_entity *ent = get_Sel_entity(ptr);
			ir_type   *tp  = get_entity_owner(ent);

			/* Do not fiddle with polymorphism. */
			if (is_Class_type(get_entity_owner(ent)) &&
				((get_entity_n_overwrites(ent)    != 0) ||
				(get_entity_n_overwrittenby(ent) != 0)   ) )
				return NULL;

			if (is_Array_type(tp)) {
				/* check bounds */
				int i, n;

				for (i = 0, n = get_Sel_n_indexs(ptr); i < n; ++i) {
Matthias Braun's avatar
Matthias Braun committed
266
267
268
269
					ir_node   *bound;
					ir_tarval *tlower, *tupper;
					ir_node   *index = get_Sel_index(ptr, i);
					ir_tarval *tv    = computed_value(index);
270
271
272
273
274
275
276
277
278
279
280
281
282

					/* check if the index is constant */
					if (tv == tarval_bad)
						return NULL;

					bound  = get_array_lower_bound(tp, i);
					tlower = computed_value(bound);
					bound  = get_array_upper_bound(tp, i);
					tupper = computed_value(bound);

					if (tlower == tarval_bad || tupper == tarval_bad)
						return NULL;

283
					if (tarval_cmp(tv, tlower) == ir_relation_less)
284
						return NULL;
285
					if (tarval_cmp(tupper, tv) == ir_relation_less)
286
287
288
289
290
291
						return NULL;

					/* ok, bounds check finished */
				}
			}

Matthias Braun's avatar
Matthias Braun committed
292
			if (get_entity_linkage(ent) & IR_LINKAGE_CONSTANT)
293
294
295
296
				return ent;

			/* try next */
			ptr = get_Sel_ptr(ptr);
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
		} else if (is_Add(ptr)) {
			ir_node *l = get_Add_left(ptr);
			ir_node *r = get_Add_right(ptr);

			if (get_irn_mode(l) == get_irn_mode(ptr) && is_Const(r))
				ptr = l;
			else if (get_irn_mode(r) == get_irn_mode(ptr) && is_Const(l))
				ptr = r;
			else
				return NULL;

			/* for now, we support only one addition, reassoc should fold all others */
			if (! is_SymConst(ptr) && !is_Sel(ptr))
				return NULL;
		} else if (is_Sub(ptr)) {
			ir_node *l = get_Sub_left(ptr);
			ir_node *r = get_Sub_right(ptr);

315
			if (get_irn_mode(l) == get_irn_mode(ptr) && is_Const(r))
316
317
318
319
320
321
				ptr = l;
			else
				return NULL;
			/* for now, we support only one substraction, reassoc should fold all others */
			if (! is_SymConst(ptr) && !is_Sel(ptr))
				return NULL;
322
323
324
325
		} else
			return NULL;
	}
}  /* find_constant_entity */
Michael Beck's avatar
Michael Beck committed
326

Michael Beck's avatar
Michael Beck committed
327
328
329
/**
 * Return the Selection index of a Sel node from dimension n
 */
330
331
static long get_Sel_array_index_long(ir_node *n, int dim)
{
332
	ir_node *index = get_Sel_index(n, dim);
Michael Beck's avatar
Michael Beck committed
333
	assert(is_Const(index));
334
335
	return get_tarval_long(get_Const_tarval(index));
}  /* get_Sel_array_index_long */
336

337
338
339
typedef struct path_entry {
	ir_entity         *ent;
	struct path_entry *next;
340
	size_t            index;
341
342
} path_entry;

343
344
static ir_node *rec_find_compound_ent_value(ir_node *ptr, path_entry *next)
{
345
	path_entry       entry, *p;
346
	ir_entity        *ent, *field;
347
	ir_initializer_t *initializer;
Matthias Braun's avatar
Matthias Braun committed
348
	ir_tarval        *tv;
349
	ir_type          *tp;
350
	size_t           n;
351

352
	entry.next = next;
353
354
	if (is_SymConst(ptr)) {
		/* found the root */
355
		ent         = get_SymConst_entity(ptr);
356
		initializer = get_entity_initializer(ent);
357
		for (p = next; p != NULL;) {
358
359
			if (initializer->kind != IR_INITIALIZER_COMPOUND)
				return NULL;
360
361
			n  = get_initializer_compound_n_entries(initializer);
			tp = get_entity_type(ent);
362

363
364
365
366
367
368
369
370
371
372
			if (is_Array_type(tp)) {
				ent = get_array_element_entity(tp);
				if (ent != p->ent) {
					/* a missing [0] */
					if (0 >= n)
						return NULL;
					initializer = get_initializer_compound_value(initializer, 0);
					continue;
				}
			}
373
			if (p->index >= n)
374
375
				return NULL;
			initializer = get_initializer_compound_value(initializer, p->index);
376
377
378
379
380
381
382
383
384
385
386
387
388

			ent = p->ent;
			p   = p->next;
		}
		tp = get_entity_type(ent);
		while (is_Array_type(tp)) {
			ent = get_array_element_entity(tp);
			tp = get_entity_type(ent);
			/* a missing [0] */
			n  = get_initializer_compound_n_entries(initializer);
			if (0 >= n)
				return NULL;
			initializer = get_initializer_compound_value(initializer, 0);
389
		}
390

391
392
393
394
395
396
397
398
399
		switch (initializer->kind) {
		case IR_INITIALIZER_CONST:
			return get_initializer_const_value(initializer);
		case IR_INITIALIZER_TARVAL:
		case IR_INITIALIZER_NULL:
		default:
			return NULL;
		}
	} else if (is_Sel(ptr)) {
400
401
402
403
		entry.ent = field = get_Sel_entity(ptr);
		tp = get_entity_owner(field);
		if (is_Array_type(tp)) {
			assert(get_Sel_n_indexs(ptr) == 1 && "multi dim arrays not implemented");
404
			entry.index = get_Sel_array_index_long(ptr, 0) - get_array_lower_bound_int(tp, 0);
405
		} else {
406
			size_t i, n_members = get_compound_n_members(tp);
407
408
409
410
411
412
413
414
415
416
417
			for (i = 0; i < n_members; ++i) {
				if (get_compound_member(tp, i) == field)
					break;
			}
			if (i >= n_members) {
				/* not found: should NOT happen */
				return NULL;
			}
			entry.index = i;
		}
		return rec_find_compound_ent_value(get_Sel_ptr(ptr), &entry);
418
419
420
	}  else if (is_Add(ptr)) {
		ir_mode  *mode;
		unsigned pos;
421

422
423
424
425
426
427
428
429
430
431
		{
			ir_node *l = get_Add_left(ptr);
			ir_node *r = get_Add_right(ptr);
			if (is_Const(r)) {
				ptr = l;
				tv  = get_Const_tarval(r);
			} else {
				ptr = r;
				tv  = get_Const_tarval(l);
			}
432
433
434
		}
ptr_arith:
		mode = get_tarval_mode(tv);
435

436
437
438
439
440
441
		/* ptr must be a Sel or a SymConst, this was checked in find_constant_entity() */
		if (is_Sel(ptr)) {
			field = get_Sel_entity(ptr);
		} else {
			field = get_SymConst_entity(ptr);
		}
442

443
444
445
446
447
448
449
450
451
452
453
		/* count needed entries */
		pos = 0;
		for (ent = field;;) {
			tp = get_entity_type(ent);
			if (! is_Array_type(tp))
				break;
			ent = get_array_element_entity(tp);
			++pos;
		}
		/* should be at least ONE entry */
		if (pos == 0)
454
455
			return NULL;

456
457
458
459
460
461
		/* allocate the right number of entries */
		NEW_ARR_A(path_entry, p, pos);

		/* fill them up */
		pos = 0;
		for (ent = field;;) {
Matthias Braun's avatar
Matthias Braun committed
462
463
464
465
			unsigned   size;
			ir_tarval *sz, *tv_index, *tlower, *tupper;
			long       index;
			ir_node   *bound;
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491

			tp = get_entity_type(ent);
			if (! is_Array_type(tp))
				break;
			ent = get_array_element_entity(tp);
			p[pos].ent  = ent;
			p[pos].next = &p[pos + 1];

			size = get_type_size_bytes(get_entity_type(ent));
			sz   = new_tarval_from_long(size, mode);

			tv_index = tarval_div(tv, sz);
			tv       = tarval_mod(tv, sz);

			if (tv_index == tarval_bad || tv == tarval_bad)
				return NULL;

			assert(get_array_n_dimensions(tp) == 1 && "multiarrays not implemented");
			bound  = get_array_lower_bound(tp, 0);
			tlower = computed_value(bound);
			bound  = get_array_upper_bound(tp, 0);
			tupper = computed_value(bound);

			if (tlower == tarval_bad || tupper == tarval_bad)
				return NULL;

492
			if (tarval_cmp(tv_index, tlower) == ir_relation_less)
493
				return NULL;
494
			if (tarval_cmp(tupper, tv_index) == ir_relation_less)
495
496
497
498
499
500
501
502
503
				return NULL;

			/* ok, bounds check finished */
			index = get_tarval_long(tv_index);
			p[pos].index = index;
			++pos;
		}
		if (! tarval_is_null(tv)) {
			/* hmm, wrong access */
504
			return NULL;
505
506
507
508
509
510
		}
		p[pos - 1].next = next;
		return rec_find_compound_ent_value(ptr, p);
	} else if (is_Sub(ptr)) {
		ir_node *l = get_Sub_left(ptr);
		ir_node *r = get_Sub_right(ptr);
511

512
513
514
515
		ptr = l;
		tv  = get_Const_tarval(r);
		tv  = tarval_neg(tv);
		goto ptr_arith;
516
	}
517
	return NULL;
518
519
}

520
521
static ir_node *find_compound_ent_value(ir_node *ptr)
{
522
523
524
	return rec_find_compound_ent_value(ptr, NULL);
}

525
526
527
528
/* forward */
static void reduce_adr_usage(ir_node *ptr);

/**
Christoph Mallon's avatar
Christoph Mallon committed
529
 * Update a Load that may have lost its users.
530
 */
531
532
static void handle_load_update(ir_node *load)
{
533
	ldst_info_t *info = (ldst_info_t*)get_irn_link(load);
534

535
536
537
	/* do NOT touch volatile loads for now */
	if (get_Load_volatility(load) == volatility_is_volatile)
		return;
538

539
540
541
	if (! info->projs[pn_Load_res] && ! info->projs[pn_Load_X_except]) {
		ir_node *ptr = get_Load_ptr(load);
		ir_node *mem = get_Load_mem(load);
542

Christoph Mallon's avatar
Christoph Mallon committed
543
		/* a Load whose value is neither used nor exception checked, remove it */
Andreas Zwinkau's avatar
Andreas Zwinkau committed
544
		exchange(info->projs[pn_Load_M], mem);
545
		if (info->projs[pn_Load_X_regular])
546
			exchange(info->projs[pn_Load_X_regular], new_r_Jmp(get_nodes_block(load)));
547
		kill_node(load);
548
549
550
		reduce_adr_usage(ptr);
	}
}  /* handle_load_update */
551
552

/**
Christoph Mallon's avatar
Christoph Mallon committed
553
 * A use of an address node has vanished. Check if this was a Proj
554
555
 * node and update the counters.
 */
556
557
static void reduce_adr_usage(ir_node *ptr)
{
558
559
560
561
562
	ir_node *pred;
	if (!is_Proj(ptr))
		return;
	if (get_irn_n_edges(ptr) > 0)
		return;
563

564
565
566
	/* this Proj is dead now */
	pred = get_Proj_pred(ptr);
	if (is_Load(pred)) {
567
		ldst_info_t *info = (ldst_info_t*)get_irn_link(pred);
568
		info->projs[get_Proj_proj(ptr)] = NULL;
569

570
571
		/* this node lost its result proj, handle that */
		handle_load_update(pred);
572
573
	}
}  /* reduce_adr_usage */
574

575
576
577
578
/**
 * Check, if an already existing value of mode old_mode can be converted
 * into the needed one new_mode without loss.
 */
579
580
static int can_use_stored_value(ir_mode *old_mode, ir_mode *new_mode)
{
581
582
	unsigned old_size;
	unsigned new_size;
583
	if (old_mode == new_mode)
584
585
586
587
		return true;

	old_size = get_mode_size_bits(old_mode);
	new_size = get_mode_size_bits(new_mode);
588
589

	/* if both modes are two-complement ones, we can always convert the
590
591
592
	   Stored value into the needed one. (on big endian machines we currently
	   only support this for modes of same size) */
	if (old_size >= new_size &&
593
		  get_mode_arithmetic(old_mode) == irma_twos_complement &&
594
595
596
597
598
599
600
		  get_mode_arithmetic(new_mode) == irma_twos_complement &&
		  (!be_get_backend_param()->byte_order_big_endian
	        || old_size == new_size)) {
		return true;
	}
	return false;
}
601

Michael Beck's avatar
Michael Beck committed
602
/**
603
 * Check whether a Call is at least pure, i.e. does only read memory.
604
 */
605
606
static unsigned is_Call_pure(ir_node *call)
{
607
608
609
610
611
612
613
614
	ir_type *call_tp = get_Call_type(call);
	unsigned prop = get_method_additional_properties(call_tp);

	/* check first the call type */
	if ((prop & (mtp_property_const|mtp_property_pure)) == 0) {
		/* try the called entity */
		ir_node *ptr = get_Call_ptr(call);

615
616
		if (is_SymConst_addr_ent(ptr)) {
			ir_entity *ent = get_SymConst_entity(ptr);
617
618
619
620
621
622
623

			prop = get_entity_additional_properties(ent);
		}
	}
	return (prop & (mtp_property_const|mtp_property_pure)) != 0;
}  /* is_Call_pure */

Michael Beck's avatar
Michael Beck committed
624
static ir_node *get_base_and_offset(ir_node *ptr, long *pOffset)
625
{
Michael Beck's avatar
Michael Beck committed
626
627
	ir_mode *mode  = get_irn_mode(ptr);
	long    offset = 0;
628
629

	/* TODO: long might not be enough, we should probably use some tarval thingy... */
Michael Beck's avatar
Michael Beck committed
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
	for (;;) {
		if (is_Add(ptr)) {
			ir_node *l = get_Add_left(ptr);
			ir_node *r = get_Add_right(ptr);

			if (get_irn_mode(l) != mode || !is_Const(r))
				break;

			offset += get_tarval_long(get_Const_tarval(r));
			ptr     = l;
		} else if (is_Sub(ptr)) {
			ir_node *l = get_Sub_left(ptr);
			ir_node *r = get_Sub_right(ptr);

			if (get_irn_mode(l) != mode || !is_Const(r))
				break;

			offset -= get_tarval_long(get_Const_tarval(r));
			ptr     = l;
		} else if (is_Sel(ptr)) {
			ir_entity *ent = get_Sel_entity(ptr);
			ir_type   *tp  = get_entity_owner(ent);

			if (is_Array_type(tp)) {
				int     size;
				ir_node *index;

				/* only one dimensional arrays yet */
				if (get_Sel_n_indexs(ptr) != 1)
					break;
				index = get_Sel_index(ptr, 0);
				if (! is_Const(index))
					break;

				tp = get_entity_type(ent);
				if (get_type_state(tp) != layout_fixed)
					break;

				size    = get_type_size_bytes(tp);
				offset += size * get_tarval_long(get_Const_tarval(index));
			} else {
				if (get_type_state(tp) != layout_fixed)
					break;
				offset += get_entity_offset(ent);
			}
			ptr = get_Sel_ptr(ptr);
		} else
677
678
679
			break;
	}

Michael Beck's avatar
Michael Beck committed
680
681
	*pOffset = offset;
	return ptr;
682
683
}

Michael Beck's avatar
Michael Beck committed
684
static int try_load_after_store(ir_node *load,
685
686
687
688
		ir_node *load_base_ptr, long load_offset, ir_node *store)
{
	ldst_info_t *info;
	ir_node *store_ptr      = get_Store_ptr(store);
Michael Beck's avatar
Michael Beck committed
689
690
	long     store_offset;
	ir_node *store_base_ptr = get_base_and_offset(store_ptr, &store_offset);
691
692
693
694
695
696
697
698
699
700
701
702
	ir_node *store_value;
	ir_mode *store_mode;
	ir_node *load_ptr;
	ir_mode *load_mode;
	long     load_mode_len;
	long     store_mode_len;
	long     delta;
	int      res;

	if (load_base_ptr != store_base_ptr)
		return 0;

Michael Beck's avatar
Michael Beck committed
703
704
	load_mode      = get_Load_mode(load);
	load_mode_len  = get_mode_size_bytes(load_mode);
705
706
	store_mode     = get_irn_mode(get_Store_value(store));
	store_mode_len = get_mode_size_bytes(store_mode);
Michael Beck's avatar
Michael Beck committed
707
	delta          = load_offset - store_offset;
708
	store_value    = get_Store_value(store);
709

710
	if (delta != 0 || store_mode != load_mode) {
711
712
713
714
		/* TODO: implement for big-endian */
		if (delta < 0 || delta + load_mode_len > store_mode_len
				|| (be_get_backend_param()->byte_order_big_endian
				    && load_mode_len != store_mode_len))
715
			return 0;
716

717
718
719
		if (get_mode_arithmetic(store_mode) != irma_twos_complement ||
			get_mode_arithmetic(load_mode)  != irma_twos_complement)
			return 0;
720

Michael Beck's avatar
Michael Beck committed
721

722
723
724
		/* produce a shift to adjust offset delta */
		if (delta > 0) {
			ir_node *cnst;
725
			ir_graph *irg = get_irn_irg(load);
726

727
			cnst        = new_r_Const_long(irg, mode_Iu, delta * 8);
728
			store_value = new_r_Shr(get_nodes_block(load),
729
730
731
732
733
									store_value, cnst, store_mode);
		}

		/* add an convert if needed */
		if (store_mode != load_mode) {
734
			store_value = new_r_Conv(get_nodes_block(load), store_value, load_mode);
735
		}
736
737
	}

Michael Beck's avatar
Michael Beck committed
738
739
	DBG_OPT_RAW(load, store_value);

740
	info = (ldst_info_t*)get_irn_link(load);
741
742
743
744
745
746
	if (info->projs[pn_Load_M])
		exchange(info->projs[pn_Load_M], get_Load_mem(load));

	res = 0;
	/* no exception */
	if (info->projs[pn_Load_X_except]) {
747
		ir_graph *irg = get_irn_irg(load);
Matthias Braun's avatar
Matthias Braun committed
748
		exchange( info->projs[pn_Load_X_except], new_r_Bad(irg, mode_X));
749
750
751
		res |= CF_CHANGED;
	}
	if (info->projs[pn_Load_X_regular]) {
752
		exchange( info->projs[pn_Load_X_regular], new_r_Jmp(get_nodes_block(load)));
753
754
755
756
757
758
759
760
761
762
763
764
		res |= CF_CHANGED;
	}

	if (info->projs[pn_Load_res])
		exchange(info->projs[pn_Load_res], store_value);

	load_ptr = get_Load_ptr(load);
	kill_node(load);
	reduce_adr_usage(load_ptr);
	return res | DF_CHANGED;
}

765
766
767
768
/**
 * Follow the memory chain as long as there are only Loads,
 * alias free Stores, and constant Calls and try to replace the
 * current Load by a previous ones.
Michael Beck's avatar
Michael Beck committed
769
770
771
772
773
774
 * Note that in unreachable loops it might happen that we reach
 * load again, as well as we can fall into a cycle.
 * We break such cycles using a special visited flag.
 *
 * INC_MASTER() must be called before dive into
 */
775
776
static unsigned follow_Mem_chain(ir_node *load, ir_node *curr)
{
Michael Beck's avatar
Michael Beck committed
777
	unsigned    res = 0;
778
	ldst_info_t *info = (ldst_info_t*)get_irn_link(load);
Michael Beck's avatar
Michael Beck committed
779
780
781
782
	ir_node     *pred;
	ir_node     *ptr       = get_Load_ptr(load);
	ir_node     *mem       = get_Load_mem(load);
	ir_mode     *load_mode = get_Load_mode(load);
783
784

	for (pred = curr; load != pred; ) {
785
		ldst_info_t *pred_info = (ldst_info_t*)get_irn_link(pred);
786
787

		/*
788
789
		 * a Load immediately after a Store -- a read after write.
		 * We may remove the Load, if both Load & Store does not have an
Matthias Braun's avatar
Matthias Braun committed
790
		 * exception handler OR they are in the same Block. In the latter
791
792
793
794
795
		 * case the Load cannot throw an exception when the previous Store was
		 * quiet.
		 *
		 * Why we need to check for Store Exception? If the Store cannot
		 * be executed (ROM) the exception handler might simply jump into
Matthias Braun's avatar
Matthias Braun committed
796
		 * the load Block :-(
797
798
		 * We could make it a little bit better if we would know that the
		 * exception handler of the Store jumps directly to the end...
799
		 */
800
801
		if (is_Store(pred) && ((pred_info->projs[pn_Store_X_except] == NULL
				&& info->projs[pn_Load_X_except] == NULL)
Matthias Braun's avatar
Matthias Braun committed
802
				|| get_nodes_block(load) == get_nodes_block(pred)))
803
		{
Michael Beck's avatar
Michael Beck committed
804
805
806
807
808
			long    load_offset;
			ir_node *base_ptr = get_base_and_offset(ptr, &load_offset);
			int     changes   = try_load_after_store(load, base_ptr, load_offset, pred);

			if (changes != 0)
809
				return res | changes;
810
		} else if (is_Load(pred) && get_Load_ptr(pred) == ptr &&
811
		           can_use_stored_value(get_Load_mode(pred), load_mode)) {
812
813
			/*
			 * a Load after a Load -- a read after read.
Matthias Braun's avatar
Matthias Braun committed
814
815
816
817
			 * We may remove the second Load, if it does not have an exception
			 * handler OR they are in the same Block. In the later case
			 * the Load cannot throw an exception when the previous Load was
			 * quiet.
818
			 *
Matthias Braun's avatar
Matthias Braun committed
819
820
821
			 * Here, there is no need to check if the previous Load has an
			 * exception hander because they would have exact the same
			 * exception...
822
823
824
			 *
			 * TODO: implement load-after-load with different mode for big
			 *       endian
825
			 */
Matthias Braun's avatar
Matthias Braun committed
826
827
			if (info->projs[pn_Load_X_except] == NULL
					|| get_nodes_block(load) == get_nodes_block(pred)) {
828
829
				ir_node *value;

830
831
				DBG_OPT_RAR(load, pred);

832
833
834
835
				/* the result is used */
				if (info->projs[pn_Load_res]) {
					if (pred_info->projs[pn_Load_res] == NULL) {
						/* create a new Proj again */
836
						pred_info->projs[pn_Load_res] = new_r_Proj(pred, get_Load_mode(pred), pn_Load_res);
837
838
					}
					value = pred_info->projs[pn_Load_res];
839
840
841

					/* add an convert if needed */
					if (get_Load_mode(pred) != load_mode) {
842
						value = new_r_Conv(get_nodes_block(load), value, load_mode);
843
844
					}

845
					exchange(info->projs[pn_Load_res], value);
846
847
				}

848
849
850
				if (info->projs[pn_Load_M])
					exchange(info->projs[pn_Load_M], mem);

851
852
				/* no exception */
				if (info->projs[pn_Load_X_except]) {
853
					ir_graph *irg = get_irn_irg(load);
Matthias Braun's avatar
Matthias Braun committed
854
					exchange(info->projs[pn_Load_X_except], new_r_Bad(irg, mode_X));
855
856
					res |= CF_CHANGED;
				}
857
				if (info->projs[pn_Load_X_regular]) {
858
					exchange( info->projs[pn_Load_X_regular], new_r_Jmp(get_nodes_block(load)));
859
860
					res |= CF_CHANGED;
				}
861

862
				kill_node(load);
863
864
865
866
867
				reduce_adr_usage(ptr);
				return res |= DF_CHANGED;
			}
		}

868
		if (is_Store(pred)) {
869
			/* check if we can pass through this store */
870
871
872
			ir_alias_relation rel = get_alias_relation(
				get_Store_ptr(pred),
				get_irn_mode(get_Store_value(pred)),
873
				ptr, load_mode);
874
			/* if the might be an alias, we cannot pass this Store */
Michael Beck's avatar
Michael Beck committed
875
			if (rel != ir_no_alias)
876
877
				break;
			pred = skip_Proj(get_Store_mem(pred));
878
		} else if (is_Load(pred)) {
879
			pred = skip_Proj(get_Load_mem(pred));
880
881
882
883
884
885
886
887
888
		} else if (is_Call(pred)) {
			if (is_Call_pure(pred)) {
				/* The called graph is at least pure, so there are no Store's
				   in it. We can handle it like a Load and skip it. */
				pred = skip_Proj(get_Call_mem(pred));
			} else {
				/* there might be Store's in the graph, stop here */
				break;
			}
889
890
891
892
893
894
895
896
897
898
899
		} else {
			/* follow only Load chains */
			break;
		}

		/* check for cycles */
		if (NODE_VISITED(pred_info))
			break;
		MARK_NODE(pred_info);
	}

900
	if (is_Sync(pred)) {
901
902
903
904
905
906
		int i;

		/* handle all Sync predecessors */
		for (i = get_Sync_n_preds(pred) - 1; i >= 0; --i) {
			res |= follow_Mem_chain(load, skip_Proj(get_Sync_pred(pred, i)));
			if (res)
907
				return res;
908
909
910
911
912
		}
	}

	return res;
}  /* follow_Mem_chain */
Michael Beck's avatar
Michael Beck committed
913

914
915
ir_node *can_replace_load_by_const(const ir_node *load, ir_node *c)
{
916
917
918
919
920
	ir_mode  *c_mode = get_irn_mode(c);
	ir_mode  *l_mode = get_Load_mode(load);
	ir_node  *block  = get_nodes_block(load);
	dbg_info *dbgi   = get_irn_dbg_info(load);
	ir_node  *res    = copy_const_value(dbgi, c, block);
921
922
923
924
925

	if (c_mode != l_mode) {
		/* check, if the mode matches OR can be easily converted info */
		if (is_reinterpret_cast(c_mode, l_mode)) {
			/* copy the value from the const code irg and cast it */
926
			res = new_rd_Conv(dbgi, block, res, l_mode);
Andreas Zwinkau's avatar
Andreas Zwinkau committed
927
928
		} else {
			return NULL;
929
930
931
		}
	}
	return res;
932
}
933

Michael Beck's avatar
Michael Beck committed
934
935
/**
 * optimize a Load
936
937
 *
 * @param load  the Load node
Michael Beck's avatar
Michael Beck committed
938
 */
939
static unsigned optimize_load(ir_node *load)
Michael Beck's avatar
Michael Beck committed
940
{
941
	ldst_info_t *info = (ldst_info_t*)get_irn_link(load);
Michael Beck's avatar
Michael Beck committed
942
943
944
945
	ir_node     *mem, *ptr, *value;
	ir_entity   *ent;
	long        dummy;
	unsigned    res = 0;
946
947
948
949
950
951
952
953
954

	/* do NOT touch volatile loads for now */
	if (get_Load_volatility(load) == volatility_is_volatile)
		return 0;

	/* the address of the load to be optimized */
	ptr = get_Load_ptr(load);

	/* The mem of the Load. Must still be returned after optimization. */
Christoph Mallon's avatar
Christoph Mallon committed
955
	mem = get_Load_mem(load);
956

957
958
959
	if (info->projs[pn_Load_res] == NULL
			&& info->projs[pn_Load_X_except] == NULL) {
		/* the value is never used and we don't care about exceptions, remove */
960
961
		exchange(info->projs[pn_Load_M], mem);

962
963
		if (info->projs[pn_Load_X_regular]) {
			/* should not happen, but if it does, remove it */
964
			exchange(info->projs[pn_Load_X_regular], new_r_Jmp(get_nodes_block(load)));
965
966
			res |= CF_CHANGED;
		}
967
		kill_node(load);
968
969
970
971
		reduce_adr_usage(ptr);
		return res | DF_CHANGED;
	}

Matthias Braun's avatar
Matthias Braun committed
972
973
974
975
976
977
978
979
	value = NULL;
	/* check if we can determine the entity that will be loaded */
	ent = find_constant_entity(ptr);
	if (ent != NULL
			&& get_entity_visibility(ent) != ir_visibility_external) {
		/* a static allocation that is not external: there should be NO
		 * exception when loading even if we cannot replace the load itself.
		 */
Christoph Mallon's avatar
Christoph Mallon committed
980

Matthias Braun's avatar
Matthias Braun committed
981
982
983
984
985
986
987
988
989
990
991
992
		/* no exception, clear the info field as it might be checked later again */
		if (info->projs[pn_Load_X_except]) {
			ir_graph *irg = get_irn_irg(load);
			exchange(info->projs[pn_Load_X_except], new_r_Bad(irg, mode_X));
			info->projs[pn_Load_X_except] = NULL;
			res |= CF_CHANGED;
		}
		if (info->projs[pn_Load_X_regular]) {
			exchange(info->projs[pn_Load_X_regular], new_r_Jmp(get_nodes_block(load)));
			info->projs[pn_Load_X_regular] = NULL;
			res |= CF_CHANGED;
		}
Michael Beck's avatar
Michael Beck committed
993

Matthias Braun's avatar
Matthias Braun committed
994
995
996
997
998
999
1000
1001
		if (get_entity_linkage(ent) & IR_LINKAGE_CONSTANT) {
			if (has_entity_initializer(ent)) {
				/* new style initializer */
				value = find_compound_ent_value(ptr);
			}
			if (value != NULL) {
				ir_graph *irg = get_irn_irg(load);
				value = can_replace_load_by_const(load, value);
1002
				if (value != NULL && is_Sel(ptr)) {
Matthias Braun's avatar
Matthias Braun committed
1003
1004
1005
					/* frontend has inserted masking operations after bitfield accesses,
					 * so we might have to shift the const. */
					unsigned char bit_offset = get_entity_offset_bits_remainder(get_Sel_entity(ptr));
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
					if (bit_offset != 0) {
						if (is_Const(value)) {
							ir_tarval *tv_old = get_Const_tarval(value);
							ir_tarval *tv_offset = new_tarval_from_long(bit_offset, mode_Bu);
							ir_tarval *tv_new = tarval_shl(tv_old, tv_offset);
							value = new_r_Const(irg, tv_new);
						} else {
							value = NULL;
						}
					}
Andreas Zwinkau's avatar
Andreas Zwinkau committed
1016
				}
Michael Beck's avatar
Michael Beck committed
1017
			}
1018
		}
Michael Beck's avatar
Michael Beck committed
1019
1020
1021
	}
	if (value != NULL) {
		/* we completely replace the load by this value */
1022
		if (info->projs[pn_Load_X_except]) {
1023
			ir_graph *irg = get_irn_irg(load);
Matthias Braun's avatar
Matthias Braun committed
1024
			exchange(info->projs[pn_Load_X_except], new_r_Bad(irg, mode_X));
1025
			info->projs[pn_Load_X_except] = NULL;
1026
1027
1028
			res |= CF_CHANGED;
		}
		if (info->projs[pn_Load_X_regular]) {
1029
			exchange(info->projs[pn_Load_X_regular], new_r_Jmp(get_nodes_block(load)));
1030
1031
			info->projs[pn_Load_X_regular] = NULL;
			res |= CF_CHANGED;
1032
		}
Michael Beck's avatar
Michael Beck committed
1033
1034
1035
1036
1037
1038
1039
1040
		if (info->projs[pn_Load_M]) {
			exchange(info->projs[pn_Load_M], mem);
			res |= DF_CHANGED;
		}
		if (info->projs[pn_Load_res]) {
			exchange(info->projs[pn_Load_res], value);
			res |= DF_CHANGED;
		}
1041
		kill_node(load);
1042
		reduce_adr_usage(ptr);
Michael Beck's avatar
Michael Beck committed
1043
		return res;
1044
1045
1046
	}

	/* Check, if the address of this load is used more than once.
Michael Beck's avatar
Michael Beck committed
1047
	 * If not, more load cannot be removed in any case. */
1048
	if (get_irn_n_edges(ptr) <= 1 && get_irn_n_edges(get_base_and_offset(ptr, &dummy)) <= 1)
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
		return res;

	/*
	 * follow the memory chain as long as there are only Loads
	 * and try to replace current Load or Store by a previous one.
	 * Note that in unreachable loops it might happen that we reach
	 * load again, as well as we can fall into a cycle.
	 * We break such cycles using a special visited flag.
	 */
	INC_MASTER();
	res = follow_Mem_chain(load, skip_Proj(mem));
	return res;
}  /* optimize_load */
Michael Beck's avatar
Michael Beck committed
1062

1063
1064
1065
1066
1067
1068
1069
1070
1071
/**
 * Check whether a value of mode new_mode would completely overwrite a value
 * of mode old_mode in memory.
 */
static int is_completely_overwritten(ir_mode *old_mode, ir_mode *new_mode)
{
	return get_mode_size_bits(new_mode) >= get_mode_size_bits(old_mode);
}  /* is_completely_overwritten */

1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082