ldstopt.c 59 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.
 */

Michael Beck's avatar
Michael Beck committed
20
21
22
23
24
/**
 * @file
 * @brief   Load/Store optimizations.
 * @author  Michael Beck
 * @version $Id$
Michael Beck's avatar
Michael Beck committed
25
 */
Michael Beck's avatar
Michael Beck committed
26
27
28
29
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

30
#include <string.h>
Michael Beck's avatar
Michael Beck committed
31

32
#include "iroptimize.h"
33
34
35
36
37
38
39
40
41
42
43
44
45
46
#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"
#include "irvrfy.h"
#include "tv_t.h"
#include "dbginfo_t.h"
#include "iropt_dbg.h"
#include "irflag_t.h"
#include "array.h"
#include "irhooks.h"
Michael Beck's avatar
BugFix:    
Michael Beck committed
47
#include "iredges.h"
48
49
#include "irtools.h"
#include "opt_polymorphy.h"
50
#include "irmemory.h"
51
#include "xmalloc.h"
52
53
54
55
56
57
#include "irphase_t.h"
#include "irgopt.h"
#include "debug.h"

/** The debug handle. */
DEBUG_ONLY(static firm_dbg_module_t *dbg;)
58
59
60
61

#ifdef DO_CACHEOPT
#include "cacheopt/cachesim.h"
#endif
Michael Beck's avatar
Michael Beck committed
62
63
64
65

#undef IMAX
#define IMAX(a,b)	((a) > (b) ? (a) : (b))

66
#define MAX_PROJ	IMAX(IMAX(pn_Load_max, pn_Store_max), pn_Call_max)
Michael Beck's avatar
Michael Beck committed
67

68
enum changes_t {
69
70
	DF_CHANGED = 1,       /**< data flow changed */
	CF_CHANGED = 2,       /**< control flow changed */
71
72
};

Michael Beck's avatar
Michael Beck committed
73
74
75
76
/**
 * walker environment
 */
typedef struct _walk_env_t {
77
78
	struct obstack obst;          /**< list of all stores */
	unsigned changes;             /**< a bitmask of graph changes */
Michael Beck's avatar
Michael Beck committed
79
80
} walk_env_t;

81
/** A Load/Store info. */
Michael Beck's avatar
Michael Beck committed
82
typedef struct _ldst_info_t {
83
84
85
86
	ir_node  *projs[MAX_PROJ];    /**< list of Proj's of this node */
	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
87
88
} ldst_info_t;

89
/**
90
 * flags for control flow.
91
92
 */
enum block_flags_t {
93
94
	BLOCK_HAS_COND = 1,      /**< Block has conditional control flow */
	BLOCK_HAS_EXC  = 2       /**< Block has exceptional control flow */
95
96
97
};

/**
98
 * a Block info.
99
100
 */
typedef struct _block_info_t {
101
	unsigned flags;               /**< flags for the block */
102
103
} block_info_t;

104
105
106
107
108
109
110
/** 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
111
112
113
/**
 * get the Load/Store info of a node
 */
114
static ldst_info_t *get_ldst_info(ir_node *node, struct obstack *obst) {
115
	ldst_info_t *info = get_irn_link(node);
Michael Beck's avatar
Michael Beck committed
116

117
	if (! info) {
118
		info = obstack_alloc(obst, sizeof(*info));
119
120
121
122
123
		memset(info, 0, sizeof(*info));
		set_irn_link(node, info);
	}
	return info;
}  /* get_ldst_info */
Michael Beck's avatar
Michael Beck committed
124

125
126
127
/**
 * get the Block info of a node
 */
128
static block_info_t *get_block_info(ir_node *node, struct obstack *obst) {
129
	block_info_t *info = get_irn_link(node);
130

131
	if (! info) {
132
		info = obstack_alloc(obst, sizeof(*info));
133
134
135
136
137
		memset(info, 0, sizeof(*info));
		set_irn_link(node, info);
	}
	return info;
}  /* get_block_info */
138

Michael Beck's avatar
Michael Beck committed
139
/**
Michael Beck's avatar
Michael Beck committed
140
 * update the projection info for a Load/Store
Michael Beck's avatar
Michael Beck committed
141
 */
142
static unsigned update_projs(ldst_info_t *info, ir_node *proj)
Michael Beck's avatar
Michael Beck committed
143
{
144
	long nr = get_Proj_proj(proj);
Michael Beck's avatar
Michael Beck committed
145

146
	assert(0 <= nr && nr <= MAX_PROJ && "Wrong proj from LoadStore");
Michael Beck's avatar
Michael Beck committed
147

148
149
150
151
152
153
154
155
156
157
	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
158
159

/**
160
161
162
163
164
 * 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
165
 */
166
static unsigned update_exc(ldst_info_t *info, ir_node *block, int pos)
Michael Beck's avatar
Michael Beck committed
167
{
168
	assert(info->exc_block == NULL && "more than one exception block found");
Michael Beck's avatar
Michael Beck committed
169

170
171
172
173
	info->exc_block = block;
	info->exc_idx   = pos;
	return 0;
}  /* update_exc */
Michael Beck's avatar
Michael Beck committed
174

175
/** Return the number of uses of an address node */
Michael Beck's avatar
BugFix:    
Michael Beck committed
176
#define get_irn_n_uses(adr)     get_irn_n_edges(adr)
177

Michael Beck's avatar
Michael Beck committed
178
179
/**
 * walker, collects all Load/Store/Proj nodes
180
 *
181
 * walks from Start -> End
Michael Beck's avatar
Michael Beck committed
182
 */
Michael Beck's avatar
Michael Beck committed
183
static void collect_nodes(ir_node *node, void *env)
Michael Beck's avatar
Michael Beck committed
184
{
185
	ir_opcode   opcode = get_irn_opcode(node);
186
187
188
189
	ir_node     *pred, *blk, *pred_blk;
	ldst_info_t *ldst_info;
	walk_env_t  *wenv = env;

190
191
192
	if (opcode == iro_Proj) {
		pred   = get_Proj_pred(node);
		opcode = get_irn_opcode(pred);
193

194
		if (opcode == iro_Load || opcode == iro_Store || opcode == iro_Call) {
195
			ldst_info = get_ldst_info(pred, &wenv->obst);
196
197
198
199

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

			/*
200
201
202
203
204
			 * 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.
			 */
205
206
207
208
209
210
211
			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);
			}
		}
212
	} else if (opcode == iro_Block) {
213
214
215
		int i;

		for (i = get_Block_n_cfgpreds(node) - 1; i >= 0; --i) {
216
			ir_node      *pred_block, *proj;
217
			block_info_t *bl_info;
218
219
220
			int          is_exc = 0;

			pred = proj = get_Block_cfgpred(node, i);
221

222
223
224
225
			if (is_Proj(proj)) {
				pred   = get_Proj_pred(proj);
				is_exc = get_Proj_proj(proj) == pn_Generic_X_except;
			}
226
227
228
229
230
231

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

			pred_block = get_nodes_block(pred);
232
			bl_info    = get_block_info(pred_block, &wenv->obst);
233

234
			if (is_fragile_op(pred) && is_exc)
235
236
237
238
				bl_info->flags |= BLOCK_HAS_EXC;
			else if (is_irn_forking(pred))
				bl_info->flags |= BLOCK_HAS_COND;

239
240
			opcode = get_irn_opcode(pred);
			if (is_exc && (opcode == iro_Load || opcode == iro_Store || opcode == iro_Call)) {
241
				ldst_info = get_ldst_info(pred, &wenv->obst);
242
243
244
245
246
247

				wenv->changes |= update_exc(ldst_info, node, i);
			}
		}
	}
}  /* collect_nodes */
Michael Beck's avatar
Michael Beck committed
248

Michael Beck's avatar
Michael Beck committed
249
/**
250
 * Returns an entity if the address ptr points to a constant one.
251
252
253
254
 *
 * @param ptr  the address
 *
 * @return an entity or NULL
Michael Beck's avatar
Michael Beck committed
255
 */
256
static ir_entity *find_constant_entity(ir_node *ptr)
Michael Beck's avatar
Michael Beck committed
257
{
258
	for (;;) {
259
		if (is_SymConst(ptr) && get_SymConst_kind(ptr) == symconst_addr_ent) {
260
			return get_SymConst_entity(ptr);
261
		} else if (is_Sel(ptr)) {
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
			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) {
					ir_node *bound;
					tarval *tlower, *tupper;
					ir_node *index = get_Sel_index(ptr, i);
					tarval *tv     = computed_value(index);

					/* 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;

					if (tarval_cmp(tv, tlower) & pn_Cmp_Lt)
						return NULL;
					if (tarval_cmp(tupper, tv) & pn_Cmp_Lt)
						return NULL;

					/* ok, bounds check finished */
				}
			}

			if (variability_constant == get_entity_variability(ent))
				return ent;

			/* try next */
			ptr = get_Sel_ptr(ptr);
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
		} 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);

			if (get_irn_mode(l) == get_irn_mode(ptr) &&	is_Const(r))
				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;
332
333
334
335
		} else
			return NULL;
	}
}  /* find_constant_entity */
Michael Beck's avatar
Michael Beck committed
336

Michael Beck's avatar
Michael Beck committed
337
338
339
/**
 * Return the Selection index of a Sel node from dimension n
 */
340
static long get_Sel_array_index_long(ir_node *n, int dim) {
341
	ir_node *index = get_Sel_index(n, dim);
Michael Beck's avatar
Michael Beck committed
342
	assert(is_Const(index));
343
344
	return get_tarval_long(get_Const_tarval(index));
}  /* get_Sel_array_index_long */
345

Michael Beck's avatar
Michael Beck committed
346
347
348
349
350
351
352
353
/**
 * Returns the accessed component graph path for an
 * node computing an address.
 *
 * @param ptr    the node computing the address
 * @param depth  current depth in steps upward from the root
 *               of the address
 */
Götz Lindenmaier's avatar
bugfix    
Götz Lindenmaier committed
354
static compound_graph_path *rec_get_accessed_path(ir_node *ptr, int depth) {
355
	compound_graph_path *res = NULL;
356
357
358
359
	ir_entity           *root, *field, *ent;
	int                 path_len, pos, idx;
	tarval              *tv;
	ir_type             *tp;
360

361
	if (is_SymConst(ptr)) {
362
363
		/* a SymConst. If the depth is 0, this is an access to a global
		 * entity and we don't need a component path, else we know
Christoph Mallon's avatar
Christoph Mallon committed
364
		 * at least its length.
365
366
367
368
		 */
		assert(get_SymConst_kind(ptr) == symconst_addr_ent);
		root = get_SymConst_entity(ptr);
		res = (depth == 0) ? NULL : new_compound_graph_path(get_entity_type(root), depth);
369
	} else if (is_Sel(ptr)) {
370
371
		/* it's a Sel, go up until we find the root */
		res = rec_get_accessed_path(get_Sel_ptr(ptr), depth+1);
372
373
		if (res == NULL)
			return NULL;
374
375
376
377
378
379
380
381
382
383
384

		/* fill up the step in the path at the current position */
		field    = get_Sel_entity(ptr);
		path_len = get_compound_graph_path_length(res);
		pos      = path_len - depth - 1;
		set_compound_graph_path_node(res, pos, field);

		if (is_Array_type(get_entity_owner(field))) {
			assert(get_Sel_n_indexs(ptr) == 1 && "multi dim arrays not implemented");
			set_compound_graph_path_array_index(res, pos, get_Sel_array_index_long(ptr, 0));
		}
385
	} else if (is_Add(ptr)) {
Michael Beck's avatar
Michael Beck committed
386
387
388
389
		ir_node *l    = get_Add_left(ptr);
		ir_node *r    = get_Add_right(ptr);
		ir_mode *mode = get_irn_mode(ptr);
		tarval  *tmp;
390

Michael Beck's avatar
Michael Beck committed
391
		if (is_Const(r) && get_irn_mode(l) == mode) {
392
393
394
395
396
397
398
399
			ptr = l;
			tv  = get_Const_tarval(r);
		} else {
			ptr = r;
			tv  = get_Const_tarval(l);
		}
ptr_arith:
		mode = get_tarval_mode(tv);
Michael Beck's avatar
Michael Beck committed
400
		tmp  = tv;
401
402
403
404
405
406
407
408
409

		/* 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);
		}
		idx = 0;
		for (ent = field;;) {
410
411
412
413
			unsigned size;
			tarval   *sz, *tv_index, *tlower, *tupper;
			ir_node  *bound;

414
415
416
417
			tp = get_entity_type(ent);
			if (! is_Array_type(tp))
				break;
			ent = get_array_element_entity(tp);
418
419
420
			size = get_type_size_bytes(get_entity_type(ent));
			sz   = new_tarval_from_long(size, mode);

Michael Beck's avatar
Michael Beck committed
421
422
			tv_index = tarval_div(tmp, sz);
			tmp      = tarval_mod(tmp, sz);
423

Michael Beck's avatar
Michael Beck committed
424
			if (tv_index == tarval_bad || tmp == tarval_bad)
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
				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;

			if (tarval_cmp(tv_index, tlower) & pn_Cmp_Lt)
				return NULL;
			if (tarval_cmp(tupper, tv_index) & pn_Cmp_Lt)
				return NULL;

			/* ok, bounds check finished */
442
443
			++idx;
		}
Michael Beck's avatar
Michael Beck committed
444
		if (! tarval_is_null(tmp)) {
445
446
447
448
			/* access to some struct/union member */
			return NULL;
		}

449
450
451
452
453
454
455
456
457
458
459
460
461
		/* should be at least ONE array */
		if (idx == 0)
			return NULL;

		res = rec_get_accessed_path(ptr, depth + idx);
		if (res == NULL)
			return NULL;

		path_len = get_compound_graph_path_length(res);
		pos      = path_len - depth - idx;

		for (ent = field;;) {
			unsigned size;
462
			tarval   *sz, *tv_index;
463
464
465
466
467
468
469
470
471
472
473
474
475
476
			long     index;

			tp = get_entity_type(ent);
			if (! is_Array_type(tp))
				break;
			ent = get_array_element_entity(tp);
			set_compound_graph_path_node(res, pos, ent);

			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);

Michael Beck's avatar
Michael Beck committed
477
478
			/* worked above, should work again */
			assert(tv_index != tarval_bad && tv != tarval_bad);
479

480
			/* bounds already checked above */
481
482
483
484
485
486
487
488
489
490
491
492
			index = get_tarval_long(tv_index);
			set_compound_graph_path_array_index(res, pos, index);
			++pos;
		}
	} else if (is_Sub(ptr)) {
		ir_node *l = get_Sub_left(ptr);
		ir_node *r = get_Sub_right(ptr);

		ptr = l;
		tv  = get_Const_tarval(r);
		tv  = tarval_neg(tv);
		goto ptr_arith;
493
494
495
	}
	return res;
}  /* rec_get_accessed_path */
496

497
498
499
/**
 * Returns an access path or NULL.  The access path is only
 * valid, if the graph is in phase_high and _no_ address computation is used.
Michael Beck's avatar
Michael Beck committed
500
 */
Götz Lindenmaier's avatar
bugfix    
Götz Lindenmaier committed
501
static compound_graph_path *get_accessed_path(ir_node *ptr) {
Michael Beck's avatar
Michael Beck committed
502
503
	compound_graph_path *gr = rec_get_accessed_path(ptr, 0);
	return gr;
504
}  /* get_accessed_path */
505

506
507
508
509
510
511
512
513
typedef struct path_entry {
	ir_entity         *ent;
	struct path_entry *next;
	long              index;
} path_entry;

static ir_node *rec_find_compound_ent_value(ir_node *ptr, path_entry *next) {
	path_entry       entry, *p;
514
	ir_entity        *ent, *field;
515
	ir_initializer_t *initializer;
516
517
	tarval           *tv;
	ir_type          *tp;
518
	unsigned         n;
519

520
	entry.next = next;
521
522
	if (is_SymConst(ptr)) {
		/* found the root */
523
		ent         = get_SymConst_entity(ptr);
524
		initializer = get_entity_initializer(ent);
525
		for (p = next; p != NULL;) {
526
527
			if (initializer->kind != IR_INITIALIZER_COMPOUND)
				return NULL;
528
529
			n  = get_initializer_compound_n_entries(initializer);
			tp = get_entity_type(ent);
530

531
532
533
534
535
536
537
538
539
540
			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;
				}
			}
541
			if (p->index >= (int) n)
542
543
				return NULL;
			initializer = get_initializer_compound_value(initializer, p->index);
544
545
546
547
548
549
550
551
552
553
554
555
556

			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);
557
		}
558

559
560
561
562
563
564
565
566
567
		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)) {
568
569
570
571
		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");
572
			entry.index = get_Sel_array_index_long(ptr, 0) - get_array_lower_bound_int(tp, 0);
573
574
575
576
577
578
579
580
581
582
583
584
585
		} else {
			int i, n_members = get_compound_n_members(tp);
			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);
586
587
588
589
590
	}  else if (is_Add(ptr)) {
		ir_node  *l = get_Add_left(ptr);
		ir_node  *r = get_Add_right(ptr);
		ir_mode  *mode;
		unsigned pos;
591

592
593
594
595
596
597
598
599
600
		if (is_Const(r)) {
			ptr = l;
			tv  = get_Const_tarval(r);
		} else {
			ptr = r;
			tv  = get_Const_tarval(l);
		}
ptr_arith:
		mode = get_tarval_mode(tv);
601

602
603
604
605
606
607
		/* 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);
		}
608

609
610
611
612
613
614
615
616
617
618
619
		/* 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)
620
621
			return NULL;

622
623
624
625
626
627
628
629
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
		/* allocate the right number of entries */
		NEW_ARR_A(path_entry, p, pos);

		/* fill them up */
		pos = 0;
		for (ent = field;;) {
			unsigned size;
			tarval   *sz, *tv_index, *tlower, *tupper;
			long     index;
			ir_node  *bound;

			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;

			if (tarval_cmp(tv_index, tlower) & pn_Cmp_Lt)
				return NULL;
			if (tarval_cmp(tupper, tv_index) & pn_Cmp_Lt)
				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 */
670
			return NULL;
671
672
673
674
675
676
		}
		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);
677

678
679
680
681
		ptr = l;
		tv  = get_Const_tarval(r);
		tv  = tarval_neg(tv);
		goto ptr_arith;
682
	}
683
	return NULL;
684
685
686
687
688
689
}

static ir_node *find_compound_ent_value(ir_node *ptr) {
	return rec_find_compound_ent_value(ptr, NULL);
}

690
691
692
693
/* forward */
static void reduce_adr_usage(ir_node *ptr);

/**
Christoph Mallon's avatar
Christoph Mallon committed
694
 * Update a Load that may have lost its users.
695
696
 */
static void handle_load_update(ir_node *load) {
697
	ldst_info_t *info = get_irn_link(load);
698

699
700
701
	/* do NOT touch volatile loads for now */
	if (get_Load_volatility(load) == volatility_is_volatile)
		return;
702

703
704
705
	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);
706

Christoph Mallon's avatar
Christoph Mallon committed
707
		/* a Load whose value is neither used nor exception checked, remove it */
708
		exchange(info->projs[pn_Load_M], mem);
709
710
		if (info->projs[pn_Load_X_regular])
			exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
711
		kill_node(load);
712
713
714
		reduce_adr_usage(ptr);
	}
}  /* handle_load_update */
715
716

/**
Christoph Mallon's avatar
Christoph Mallon committed
717
 * A use of an address node has vanished. Check if this was a Proj
718
719
720
 * node and update the counters.
 */
static void reduce_adr_usage(ir_node *ptr) {
721
722
723
724
725
726
727
728
729
	if (is_Proj(ptr)) {
		if (get_irn_n_edges(ptr) <= 0) {
			/* this Proj is dead now */
			ir_node *pred = get_Proj_pred(ptr);

			if (is_Load(pred)) {
				ldst_info_t *info = get_irn_link(pred);
				info->projs[get_Proj_proj(ptr)] = NULL;

Christoph Mallon's avatar
Christoph Mallon committed
730
				/* this node lost its result proj, handle that */
731
732
733
734
735
				handle_load_update(pred);
			}
		}
	}
}  /* reduce_adr_usage */
736

737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
/**
 * Check, if an already existing value of mode old_mode can be converted
 * into the needed one new_mode without loss.
 */
static int can_use_stored_value(ir_mode *old_mode, ir_mode *new_mode) {
	if (old_mode == new_mode)
		return 1;

	/* if both modes are two-complement ones, we can always convert the
	   Stored value into the needed one. */
	if (get_mode_size_bits(old_mode) >= get_mode_size_bits(new_mode) &&
		  get_mode_arithmetic(old_mode) == irma_twos_complement &&
		  get_mode_arithmetic(new_mode) == irma_twos_complement)
		return 1;
	return 0;
}  /* can_use_stored_value */

Michael Beck's avatar
Michael Beck committed
754
/**
755
756
757
758
759
760
761
762
763
764
765
 * Check whether a Call is at least pure, ie. does only read memory.
 */
static unsigned is_Call_pure(ir_node *call) {
	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);

766
767
		if (is_Global(ptr)) {
			ir_entity *ent = get_Global_entity(ptr);
768
769
770
771
772
773
774

			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
775
static ir_node *get_base_and_offset(ir_node *ptr, long *pOffset)
776
{
Michael Beck's avatar
Michael Beck committed
777
778
	ir_mode *mode  = get_irn_mode(ptr);
	long    offset = 0;
779
780

	/* TODO: long might not be enough, we should probably use some tarval thingy... */
Michael Beck's avatar
Michael Beck committed
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
	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
828
829
830
			break;
	}

Michael Beck's avatar
Michael Beck committed
831
832
	*pOffset = offset;
	return ptr;
833
834
}

Michael Beck's avatar
Michael Beck committed
835
static int try_load_after_store(ir_node *load,
836
837
838
839
		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
840
841
	long     store_offset;
	ir_node *store_base_ptr = get_base_and_offset(store_ptr, &store_offset);
842
843
844
845
846
847
848
849
850
851
852
853
	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
854
855
	load_mode      = get_Load_mode(load);
	load_mode_len  = get_mode_size_bytes(load_mode);
856
857
	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
858
859
	delta          = load_offset - store_offset;
	if (delta < 0 || delta + load_mode_len > store_mode_len)
860
861
		return 0;

Michael Beck's avatar
Michael Beck committed
862
863
	if (get_mode_arithmetic(store_mode) != irma_twos_complement ||
	    get_mode_arithmetic(load_mode)  != irma_twos_complement)
864
865
866
867
868
869
		return 0;

	store_value = get_Store_value(store);

	/* produce a shift to adjust offset delta */
	if (delta > 0) {
Michael Beck's avatar
Michael Beck committed
870
871
872
873
		ir_node *cnst;

		/* FIXME: only true for little endian */
		cnst        = new_Const_long(mode_Iu, delta * 8);
874
875
876
877
878
879
880
881
882
883
		store_value = new_r_Shr(current_ir_graph, get_nodes_block(load),
		                        store_value, cnst, store_mode);
	}

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

Michael Beck's avatar
Michael Beck committed
884
885
	DBG_OPT_RAW(load, store_value);

886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
	info = get_irn_link(load);
	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]) {
		exchange( info->projs[pn_Load_X_except], new_Bad());
		res |= CF_CHANGED;
	}
	if (info->projs[pn_Load_X_regular]) {
		exchange( info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
		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;
}

910
911
912
913
/**
 * 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
914
915
916
917
918
919
 * 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
 */
920
static unsigned follow_Mem_chain(ir_node *load, ir_node *curr) {
Michael Beck's avatar
Michael Beck committed
921
	unsigned    res = 0;
922
	ldst_info_t *info = get_irn_link(load);
Michael Beck's avatar
Michael Beck committed
923
924
925
926
	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);
927
928
929
930
931

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

		/*
932
933
934
935
936
937
938
939
940
941
942
		 * a Load immediately after a Store -- a read after write.
		 * We may remove the Load, if both Load & Store does not have an
		 * exception handler OR they are in the same MacroBlock. In the latter
		 * 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
		 * the load MacroBlock :-(
		 * We could make it a little bit better if we would know that the
		 * exception handler of the Store jumps directly to the end...
943
		 */
944
945
946
947
		if (is_Store(pred) && ((pred_info->projs[pn_Store_X_except] == NULL
				&& info->projs[pn_Load_X_except] == NULL)
				|| get_nodes_MacroBlock(load) == get_nodes_MacroBlock(pred)))
		{
Michael Beck's avatar
Michael Beck committed
948
949
950
951
952
			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)
953
				return res | changes;
954
		} else if (is_Load(pred) && get_Load_ptr(pred) == ptr &&
955
		           can_use_stored_value(get_Load_mode(pred), load_mode)) {
956
957
958
			/*
			 * a Load after a Load -- a read after read.
			 * We may remove the second Load, if it does not have an exception handler
959
			 * OR they are in the same MacroBlock. In the later case the Load cannot
960
961
962
963
964
			 * throw an exception when the previous Load was quiet.
			 *
			 * Here, there is no need to check if the previous Load has an exception
			 * hander because they would have exact the same exception...
			 */
965
			if (info->projs[pn_Load_X_except] == NULL || get_nodes_MacroBlock(load) == get_nodes_MacroBlock(pred)) {
966
967
				ir_node *value;

968
969
				DBG_OPT_RAR(load, pred);

970
971
972
973
974
975
976
				/* the result is used */
				if (info->projs[pn_Load_res]) {
					if (pred_info->projs[pn_Load_res] == NULL) {
						/* create a new Proj again */
						pred_info->projs[pn_Load_res] = new_r_Proj(current_ir_graph, get_nodes_block(pred), pred, get_Load_mode(pred), pn_Load_res);
					}
					value = pred_info->projs[pn_Load_res];
977
978
979
980
981
982

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

983
					exchange(info->projs[pn_Load_res], value);
984
985
				}

986
987
988
				if (info->projs[pn_Load_M])
					exchange(info->projs[pn_Load_M], mem);

989
990
991
992
993
				/* no exception */
				if (info->projs[pn_Load_X_except]) {
					exchange(info->projs[pn_Load_X_except], new_Bad());
					res |= CF_CHANGED;
				}
994
995
996
997
				if (info->projs[pn_Load_X_regular]) {
					exchange( info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
					res |= CF_CHANGED;
				}
998

999
				kill_node(load);
1000
1001
1002
1003
1004
				reduce_adr_usage(ptr);
				return res |= DF_CHANGED;
			}
		}

1005
		if (is_Store(pred)) {
1006
			/* check if we can pass through this store */
1007
1008
1009
1010
			ir_alias_relation rel = get_alias_relation(
				current_ir_graph,
				get_Store_ptr(pred),
				get_irn_mode(get_Store_value(pred)),
1011
				ptr, load_mode);
1012
			/* if the might be an alias, we cannot pass this Store */
Michael Beck's avatar
Michael Beck committed
1013
			if (rel != ir_no_alias)
1014
1015
				break;
			pred = skip_Proj(get_Store_mem(pred));
1016
		} else if (is_Load(pred)) {
1017
			pred = skip_Proj(get_Load_mem(pred));
1018
1019
1020
1021
1022
1023
1024
1025
1026
		} 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;
			}
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
		} else {
			/* follow only Load chains */
			break;
		}

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

1038
	if (is_Sync(pred)) {
1039
1040
1041
1042
1043
1044
		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)
1045
				return res;
1046
1047
1048
1049
1050
		}
	}

	return res;
}  /* follow_Mem_chain */
Michael Beck's avatar
Michael Beck committed
1051

Michael Beck's avatar
Michael Beck committed
1052
/*
1053
1054
1055
 * Check if we can replace the load by a given const from
 * the const code irg.
 */
Michael Beck's avatar
Michael Beck committed
1056
ir_node *can_replace_load_by_const(const ir_node *load, ir_node *c) {
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
	ir_mode *c_mode = get_irn_mode(c);
	ir_mode *l_mode = get_Load_mode(load);
	ir_node *res    = NULL;

	if (c_mode != l_mode) {
		/* check, if the mode matches OR can be easily converted info */
		if (is_reinterpret_cast(c_mode, l_mode)) {
			/* we can safely cast */
			dbg_info *dbg   = get_irn_dbg_info(load);
			ir_node  *block = get_nodes_block(load);

			/* copy the value from the const code irg and cast it */
			res = copy_const_value(dbg, c);
			res = new_rd_Conv(dbg, current_ir_graph, block, res, l_mode);
		}
	} else {
		/* copy the value from the const code irg */
		res = copy_const_value(get_irn_dbg_info(load), c);
	}
	return res;
}  /* can_replace_load_by_const */

Michael Beck's avatar
Michael Beck committed
1079
1080
/**
 * optimize a Load
1081
1082
 *
 * @param load  the Load node
Michael Beck's avatar
Michael Beck committed
1083
 */
1084
static unsigned optimize_load(ir_node *load)
Michael Beck's avatar
Michael Beck committed
1085
{
1086
	ldst_info_t *info = get_irn_link(load);
Michael Beck's avatar
Michael Beck committed
1087
1088
1089
1090
	ir_node     *mem, *ptr, *value;
	ir_entity   *ent;
	long        dummy;
	unsigned    res = 0;
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107

	/* 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);

	/*
	 * Check if we can remove the exception from a Load:
	 * This can be done, if the address is from an Sel(Alloc) and
	 * the Sel type is a subtype of the allocated type.
	 *
	 * This optimizes some often used OO constructs,
	 * like x = new O; x->t;
	 */
	if (info->projs[pn_Load_X_except]) {
Michael Beck's avatar
Michael Beck committed
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
		ir_node *addr = ptr;

		/* find base address */
		while (is_Sel(addr))
			addr = get_Sel_ptr(addr);
		if (is_Alloc(skip_Proj(skip_Cast(addr)))) {
			/* simple case: a direct load after an Alloc. Firm Alloc throw
			 * an exception in case of out-of-memory. So, there is no way for an
			 * exception in this load.
			 * This code is constructed by the "exception lowering" in the Jack compiler.
			 */
			exchange(info->projs[pn_Load_X_except], new_Bad());
			info->projs[pn_Load_X_except] = NULL;
			exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
			info->projs[pn_Load_X_regular] = NULL;
			res |= CF_CHANGED;
1124
1125
1126
1127
		}
	}

	/* The mem of the Load. Must still be returned after optimization. */
Christoph Mallon's avatar
Christoph Mallon committed
1128
	mem = get_Load_mem(load);
1129
1130
1131
1132
1133

	if (! info->projs[pn_Load_res] && ! info->projs[pn_Load_X_except]) {
		/* a Load which value is neither used nor exception checked, remove it */
		exchange(info->projs[pn_Load_M], mem);

1134
1135
1136
1137
1138
		if (info->projs[pn_Load_X_regular]) {
			/* should not happen, but if it does, remove it */
			exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
			res |= CF_CHANGED;
		}
1139
		kill_node(load);
1140
1141
1142
1143
1144
1145
		reduce_adr_usage(ptr);
		return res | DF_CHANGED;
	}

	/* Load from a constant polymorphic field, where we can resolve
	   polymorphism. */
Michael Beck's avatar
Michael Beck committed
1146
	value = transform_polymorph_Load(load);
1147
1148
	if (value == load) {
		value = NULL;
Michael Beck's avatar
Michael Beck committed
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
		/* check if we can determine the entity that will be loaded */
		ent = find_constant_entity(ptr);
		if (ent != NULL) {
			if ((allocation_static == get_entity_allocation(ent)) &&
				(visibility_external_allocated != get_entity_visibility(ent))) {
				/* a static allocation that is not external: there should be NO exception
				 * when loading even if we cannot replace the load itself. */

				/* no exception, clear the info field as it might be checked later again */
				if (info->projs[pn_Load_X_except]) {
					exchange(info->projs[pn_Load_X_except], new_Bad());
					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(current_ir_graph, get_nodes_block(load)));
					info->projs[pn_Load_X_regular] = NULL;
					res |= CF_CHANGED;
				}

				if (variability_constant == get_entity_variability(ent)) {
					if (is_atomic_entity(ent)) {
						/* Might not be atomic after
						   lowering of Sels.  In this
						   case we could also load, but
						   it's more complicated. */
						/* more simpler case: we load the content of a constant value:
						 * replace it by the constant itself
						 */
						value = get_atomic_ent_value(ent);
					} else {
						if (ent->has_initializer) {
							/* new style initializer */
							value = find_compound_ent_value(ptr);
						} else {
							/* old style initializer */
							compound_graph_path *path = get_accessed_path(ptr);

							if (path != NULL) {
								assert(is_proper_compound_graph_path(path, get_compound_graph_path_length(path)-1));

								value = get_compound_ent_value_by_path(ent, path);
Michael Beck's avatar
Michael Beck committed
1191
								DB((dbg, LEVEL_1, "  Constant access at %F%F resulted in %+F\n", ent, path, value));
Michael Beck's avatar
Michael Beck committed
1192
1193
1194
1195
1196
1197
1198
1199
								free_compound_graph_path(path);
							}
						}
					}
					if (value != NULL)
						value = can_replace_load_by_const(load, value);
				}
			}
1200
		}
Michael Beck's avatar
Michael Beck committed
1201
1202
1203
	}
	if (value != NULL) {
		/* we completely replace the load by this value */
1204
1205
1206
		if (info->projs[pn_Load_X_except]) {
			exchange(info->projs[pn_Load_X_except], new_Bad());
			info->projs[pn_Load_X_except] = NULL;
1207
1208
1209
1210
1211
1212
			res |= CF_CHANGED;
		}
		if (info->projs[pn_Load_X_regular]) {
			exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
			info->projs[pn_Load_X_regular] = NULL;
			res |= CF_CHANGED;
1213
		}
Michael Beck's avatar
Michael Beck committed
1214
1215
1216
1217
1218
1219
1220
1221
		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;
		}
1222
		kill_node(load);
1223
		reduce_adr_usage(ptr);
Michael Beck's avatar
Michael Beck committed
1224
		return res;
1225
1226
1227
	}

	/* Check, if the address of this load is used more than once.
Michael Beck's avatar
Michael Beck committed
1228
1229
	 * If not, more load cannot be removed in any case. */
	if (get_irn_n_uses(ptr) <= 1 && get_irn_n_uses(get_base_and_offset(ptr, &dummy)) <= 1)
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
		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
1243

1244
1245
1246
1247
1248
1249
1250
1251
1252
/**
 * 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 */

Michael Beck's avatar
Michael Beck committed
1253
/**
1254
 * follow the memory chain as long as there are only Loads and alias free Stores.
Michael Beck's avatar
Michael Beck committed
1255
1256
1257
 *
 * INC_MASTER() must be called before dive into
 */
1258
1259
1260
1261
1262
1263
1264
1265
1266
static unsigned follow_Mem_chain_for_Store(ir_node *store, ir_node *curr) {
	unsigned res = 0;
	ldst_info_t *info = get_irn_link(store);
	ir_node *pred;
	ir_node *ptr = get_Store_ptr(store);
	ir_node *mem = get_Store_mem(store);
	ir_node *value = get_Store_value(store);
	ir_mode *mode  = get_irn_mode(value);
	ir_node *block = get_nodes_block(store);
1267
	ir_node *mblk  = get_Block_MacroBlock(block);
1268
1269
1270
1271
1272
1273
1274
1275
1276

	for (pred = curr; pred != store;) {
		ldst_info_t *pred_info = get_irn_link(pred);

		/*
		 * BEWARE: one might think that checking the modes is useless, because
		 * if the pointers are identical, they refer to the same object.
		 * This is only true in strong typed languages, not is C were the following
		 * is possible *(ir_type1 *)p = a; *(ir_type2 *)p = b ...
1277
1278
		 * However, if the mode that is written have a bigger  or equal size the the old
		 * one, the old value is completely overwritten and can be killed ...
1279
		 */
1280
1281
		if (is_Store(pred) && get_Store_ptr(pred) == ptr &&
		    get_nodes_MacroBlock(pred) == mblk &&
1282
		    is_completely_overwritten(get_irn_mode(get_Store_value(pred)), mode)) {
1283
			/*
Michael Beck's avatar
Michael Beck committed
1284
			 * a Store after a Store in the same MacroBlock -- a write after write.
1285
1286
1287
1288
1289
1290
			 * We may remove the first Store, if it does not have an exception handler.
			 *
			 * TODO: What, if both have the same exception handler ???
			 */
			if (get_Store_volatility(pred) != volatility_is_volatile && !pred_info->projs[pn_Store_X_except]) {
				DBG_OPT_WAW(pred, store);
1291
				exchange(pred_info->projs[pn_Store_M], get_Store_mem(pred));
1292
				kill_node(pred);
1293
1294
1295
				reduce_adr_usage(ptr);
				return DF_CHANGED;
			}
1296
		} else if (is_Load(pred) && get_Load_ptr(pred) == ptr &&