lower_calls.c 23.4 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   Lowering of Calls with compound parameters and return types.
 * @author  Michael Beck
 * @version $Id$
25
26
27
28
29
30
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

31
#include "lowering.h"
32
33
34
35
36
37
38
#include "irprog_t.h"
#include "irnode_t.h"
#include "type_t.h"
#include "irmode_t.h"
#include "ircons.h"
#include "irgmod.h"
#include "irgwalk.h"
39
#include "irtools.h"
40
#include "iroptimize.h"
41
#include "array.h"
42
#include "pmap.h"
43
#include "xmalloc.h"
44
45
46
47
48
49
50
51
52
53

/** A type map for def_find_pointer_type. */
static pmap *type_map;

/**
 * Default implementation for finding a pointer type for a given element type.
 * Simple create a new one.
 */
static ir_type *def_find_pointer_type(ir_type *e_type, ir_mode *mode, int alignment)
{
54
55
56
57
58
59
60
61
62
63
64
65
66
67
	ir_type *res;
	pmap_entry *e;

	/* Mode and alignment are always identical in all calls to def_find_pointer_type(), so
	   we simply can use a map from the element type to the pointer type. */
	e = pmap_find(type_map, e_type);
	if (e)
		res = e->value;
	else {
		res = new_type_pointer(mangle_u(get_type_ident(e_type), new_id_from_chars("Ptr", 3)), e_type, mode);
		set_type_alignment_bytes(res, alignment);
		pmap_insert(type_map, e_type, res);
	}
	return res;
68
}
69
70
71
72

/**
 * Creates a new lowered type for a method type with compound
 * arguments. The new type is associated to the old one and returned.
73
74
75
76
77
 *
 * @param lp   parameter struct
 * @param mtp  the method type to lower
 *
 * The current implementation expects that a lowered type already
78
 * includes the necessary changes ...
79
80
81
 */
static ir_type *create_modified_mtd_type(const lower_params_t *lp, ir_type *mtp)
{
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
	ir_type *lowered, *ptr_tp;
	ir_type **params, **results, *res_tp;
	ir_mode *modes[MAX_REGISTER_RET_VAL];
	int n_ress, n_params, nn_ress, nn_params, i, first_variadic;
	ident *id;
	add_hidden hidden_params;
	int        changed = 0;
	variadicity var;

	if (is_lowered_type(mtp)) {
		/* the type is already lowered. Not handled yet. */
		assert(0 && "lowered types NYI");
	}

	lowered = get_associated_type(mtp);
	if (lowered)
		return lowered;

	n_ress   = get_method_n_ress(mtp);
	NEW_ARR_A(ir_type *, results, n_ress);

	n_params = get_method_n_params(mtp);
	NEW_ARR_A(ir_type *, params, n_params + n_ress);

	first_variadic = get_method_first_variadic_param_index(mtp);

	hidden_params = lp->hidden_params;
	if (hidden_params == ADD_HIDDEN_SMART &&
		get_method_variadicity(mtp) == variadicity_variadic)
		hidden_params = ADD_HIDDEN_ALWAYS_IN_FRONT;

	if (hidden_params == ADD_HIDDEN_ALWAYS_IN_FRONT) {
		/* add hidden in front */
		for (nn_ress = nn_params = i = 0; i < n_ress; ++i) {
			res_tp = get_method_res_type(mtp, i);

			if (is_compound_type(res_tp)) {
				int n_regs = 0;

				if (lp->flags & LF_SMALL_CMP_IN_REGS)
					n_regs = lp->ret_compound_in_regs(res_tp, modes);

				if (n_regs > 0) {
					/* this compound will be returned solely in registers */
					assert(0);
				}
				else {
					/* this compound will be allocated on callers stack and its
					   address will be transmitted as a hidden parameter. */
					ptr_tp = lp->find_pointer_type(res_tp, get_modeP_data(), lp->def_ptr_alignment);
					params[nn_params++] = ptr_tp;
					changed++;
					if (lp->flags & LF_RETURN_HIDDEN)
						results[nn_ress++] = ptr_tp;
				}
			}
			else
				results[nn_ress++] = res_tp;
		}

		/* move the index of the first variadic parameter */
		first_variadic += nn_params;

		for (i = 0; i < n_params; ++i)
			params[nn_params++] = get_method_param_type(mtp, i);
	}
	else {
		/* add hidden parameters last */
		assert(get_method_variadicity(mtp) == variadicity_non_variadic &&
			"Cannot add hidden parameters at end of variadic function");

		for (nn_params = 0; nn_params < n_params; ++nn_params)
			params[nn_params] = get_method_param_type(mtp, nn_params);

		for (nn_ress = i = 0; i < n_ress; ++i) {
			res_tp = get_method_res_type(mtp, i);

			if (is_compound_type(res_tp))
				params[nn_params++] = lp->find_pointer_type(res_tp, get_modeP_data(), lp->def_ptr_alignment);
			else
				results[nn_ress++] = res_tp;
		}
	}

	/* create the new type */
	id = mangle_u(new_id_from_chars("L", 1), get_type_ident(mtp));
	lowered = new_d_type_method(id, nn_params, nn_ress, get_type_dbg_info(mtp));

	/* fill it */
	for (i = 0; i < nn_params; ++i)
		set_method_param_type(lowered, i, params[i]);
	for (i = 0; i < nn_ress; ++i)
		set_method_res_type(lowered, i, results[i]);

	var = get_method_variadicity(mtp);
	set_method_variadicity(lowered, var);
	if (var == variadicity_variadic)
		set_method_first_variadic_param_index(lowered, first_variadic);

	/* associate the lowered type with the original one for easier access */
	if(changed) {
		set_method_calling_convention(lowered, get_method_calling_convention(mtp) | cc_compound_ret);
	}
	set_lowered_type(mtp, lowered);

	return lowered;
188
189
190
}

/**
191
192
193
194
 * A call list entry.
 */
typedef struct cl_entry cl_entry;
struct cl_entry {
195
196
197
	cl_entry *next;   /**< Pointer to the next entry. */
	ir_node  *call;   /**< Pointer to the Call node. */
	ir_node  *copyb;  /**< List of all CopyB nodes. */
198
199
200
201
};

/**
 * Walker environment for fix_args_and_collect_calls().
202
203
 */
typedef struct _wlk_env_t {
204
205
206
207
208
209
210
211
212
	int                  arg_shift;        /**< The Argument index shift for parameters. */
	int                  first_hidden;     /**< The index of the first hidden argument. */
	struct obstack       obst;             /**< An obstack to allocate the data on. */
	cl_entry             *cl_list;         /**< The call list. */
	pmap                 *dummy_map;       /**< A map for finding the dummy arguments. */
	unsigned             dnr;              /**< The dummy index number. */
	const lower_params_t *params;          /**< Lowering parameters. */
	unsigned             only_local_mem:1; /**< Set if only local memory access was found. */
	unsigned             changed:1;        /**< Set if the current graph was changed. */
213
214
215
} wlk_env;

/**
216
217
218
219
220
221
222
223
 * Return the call list entry of a call node.
 * If no entry exists yet, allocate one and enter the node into
 * the call list of the environment.
 *
 * @param call   A Call node.
 * @param env    The environment.
 */
static cl_entry *get_Call_entry(ir_node *call, wlk_env *env) {
224
225
226
227
228
229
230
231
232
233
	cl_entry *res = get_irn_link(call);
	if (res == NULL) {
		cl_entry *res = obstack_alloc(&env->obst, sizeof(*res));
		res->next  = env->cl_list;
		res->call  = call;
		res->copyb = NULL;
		set_irn_link(call, res);
		env->cl_list = res;
	}
	return res;
234
235
236
}

/**
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
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
 * Finds the base address of an address by skipping Sel's and address
 * calculation.
 *
 * @param adr   the address
 * @param pEnt  points to the base entity if any
 */
static ir_node *find_base_adr(ir_node *ptr, ir_entity **pEnt) {
	ir_entity *ent = NULL;
	assert(mode_is_reference(get_irn_mode(ptr)));

	for (;;) {
		if (is_Sel(ptr)) {
			ent = get_Sel_entity(ptr);
			ptr = get_Sel_ptr(ptr);
		}
		else if (is_Add(ptr)) {
			ir_node *left = get_Add_left(ptr);
			if (mode_is_reference(get_irn_mode(left)))
				ptr = left;
			else
				ptr = get_Add_right(ptr);
			ent = NULL;
		} else if (is_Sub(ptr)) {
			ptr = get_Sub_left(ptr);
			ent = NULL;
		} else {
			*pEnt = ent;
			return ptr;
		}
	}
}

/**
 * Check if a given pointer represents non-local memory.
 */
static void check_ptr(ir_node *ptr, wlk_env *env) {
	ir_storage_class_class_t sc;
	ir_entity                *ent;

	/* still alias free */
	ptr = find_base_adr(ptr, &ent);
	sc  = classify_pointer(current_ir_graph, ptr, ent);
	if (sc != ir_sc_localvar && sc != ir_sc_malloced) {
		/* non-local memory access */
		env->only_local_mem = 0;
	}
}

/**
 * Post walker: shift all parameter indexes
287
 * and collect Calls with compound returns in the call list.
288
289
 * If a non-alias free memory access is found, reset the alias free
 * flag.
290
 */
291
static void fix_args_and_collect_calls(ir_node *n, void *ctx) {
292
	wlk_env *env = ctx;
293
	int      i;
294
	ir_type *ctp;
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
	ir_node *ptr;

	switch (get_irn_opcode(n)) {
	case iro_Load:
	case iro_Store:
		if (env->only_local_mem) {
			ptr = get_irn_n(n, 1);
			check_ptr(ptr, env);
		}
		break;
	case iro_Proj:
		if (env->arg_shift > 0) {
			ir_node *pred = get_Proj_pred(n);

			/* Fix the argument numbers */
			if (pred == get_irg_args(current_ir_graph)) {
				long pnr = get_Proj_proj(n);
				set_Proj_proj(n, pnr + env->arg_shift);
				env->changed = 1;
			}
		}
		break;
	case iro_Call:
		if (! is_self_recursive_Call(n)) {
			/* any non self recursive call might access global memory */
			env->only_local_mem = 0;
321
		}
322

323
324
325
326
327
328
329
330
331
332
333
334
335
336
		ctp = get_Call_type(n);
		if (env->params->flags & LF_COMPOUND_RETURN) {
			/* check for compound returns */
			for (i = get_method_n_ress(ctp) -1; i >= 0; --i) {
				if (is_compound_type(get_method_res_type(ctp, i))) {
					/*
					 * This is a call with a compound return. As the result
					 * might be ignored, we must put it in the list.
					 */
					(void)get_Call_entry(n, env);
					break;
				}
			}
		}
337
338
339
340
341
342
343
344
345
346
347
348
349
350
		break;
	case iro_CopyB:
		if (env->only_local_mem) {
			check_ptr(get_CopyB_src(n), env);
			if (env->only_local_mem)
				check_ptr(get_CopyB_dst(n), env);
		}
		if (env->params->flags & LF_COMPOUND_RETURN) {
			/* check for compound returns */
			ir_node *src = get_CopyB_src(n);
			/* older scheme using value_res_ent */
			if (is_Sel(src)) {
				ir_node *proj = get_Sel_ptr(src);
				if (is_Proj(proj) && get_Proj_proj(proj) == pn_Call_P_value_res_base) {
351
352
					ir_node *call = get_Proj_pred(proj);
					if (is_Call(call)) {
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
						/* found a CopyB from compound Call result */
						cl_entry *e = get_Call_entry(call, env);
						set_irn_link(n, e->copyb);
						e->copyb = n;
					}
				}
			} else {
				/* new scheme: compound results are determined by the call type only */
				if (is_Proj(src)) {
					ir_node *proj = get_Proj_pred(src);
					if (is_Proj(proj) && get_Proj_proj(proj) == pn_Call_T_result) {
						ir_node *call = get_Proj_pred(proj);
						if (is_Call(call)) {
							ctp = get_Call_type(call);
							if (is_compound_type(get_method_res_type(ctp, get_Proj_proj(src)))) {
								/* found a CopyB from compound Call result */
								cl_entry *e = get_Call_entry(call, env);
								set_irn_link(n, e->copyb);
								e->copyb = n;
							}
373
374
375
376
						}
					}
				}
			}
377
		}
378
379
380
381
		break;
	default:
		/* do nothing */
		break;
382
	}
383
384
385
}

/**
386
387
 * Returns non-zero if a node is a compound address
 * of a frame-type entity.
388
389
390
391
392
393
 *
 * @param ft   the frame type
 * @param adr  the node
 */
static int is_compound_address(ir_type *ft, ir_node *adr)
{
394
395
396
397
398
399
400
401
	ir_entity *ent;

	if (! is_Sel(adr))
		return 0;
	if (get_Sel_n_indexs(adr) != 0)
		return 0;
	ent = get_Sel_entity(adr);
	return get_entity_owner(ent) == ft;
402
403
}

404
/** A pair for the copy-return-optimization. */
405
typedef struct cr_pair {
406
407
	ir_entity *ent; /**< the entity than can be removed from the frame */
	ir_node *arg;   /**< the argument that replaces the entities address */
408
409
410
411
412
413
} cr_pair;

/**
 * Post walker: fixes all entities addresses for the copy-return
 * optimization.
 *
414
415
416
 * Note: We expect the length of the cr_pair array (ie number of compound
 * return values) to be 1 (C, C++) in almost all cases, so ignore the
 * linear search complexity here.
417
418
 */
static void do_copy_return_opt(ir_node *n, void *ctx) {
419
420
421
422
423
424
425
426
427
428
429
430
431
	cr_pair *arr = ctx;
	int i;

	if (is_Sel(n)) {
		ir_entity *ent = get_Sel_entity(n);

		for (i = ARR_LEN(arr) - 1; i >= 0; --i) {
			if (ent == arr[i].ent) {
				exchange(n, arr[i].arg);
				break;
			}
		}
	}
432
433
434
}

/**
435
436
437
438
439
440
441
442
443
444
445
446
447
 * Return a Sel node that selects a dummy argument of type tp.
 * Dummy arguments are only needed once and we use a map
 * to store them.
 * We could even assign all dummy arguments the same offset
 * in the frame type ...
 *
 * @param irg    the graph
 * @param block  the block where a newly create Sel should be placed
 * @param tp     the type of the dummy entity that should be create
 * @param env    the environment
 */
static ir_node *get_dummy_sel(ir_graph *irg, ir_node *block, ir_type *tp, wlk_env *env)
{
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
	ir_entity *ent;
	pmap_entry *e;

	/* use a map the check if we already create such an entity */
	e = pmap_find(env->dummy_map, tp);
	if (e)
		ent = e->value;
	else {
		ir_type *ft = get_irg_frame_type(irg);
		char buf[16];

		snprintf(buf, sizeof(buf), "dummy.%u", env->dnr++);
		ent = new_entity(ft, new_id_from_str(buf), tp);
		pmap_insert(env->dummy_map, tp, ent);

		if (get_type_state(ft) == layout_fixed) {
			/* Fix the layout again */
			assert(0 && "Fixed layout not implemented");
		}
	}
	return new_r_simpleSel(
		irg,
		block,
		get_irg_no_mem(irg),
		get_irg_frame(irg),
		ent);
474
475
476
477
478
479
480
481
482
483
484
485
486
}

/**
 * Add the hidden parameter from the CopyB node to the Call node.
 *
 * @param irg    the graph
 * @param n_com  number of compound results (will be number of hidden parameters)
 * @param ins    in array to store the hidden parameters into
 * @param entry  the call list
 * @param env    the environment
 */
static void add_hidden_param(ir_graph *irg, int n_com, ir_node **ins, cl_entry *entry, wlk_env *env)
{
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
	ir_node *p, *n, *src, *mem, *blk;
	ir_entity *ent;
	ir_type *owner;
	int idx, n_args;

	n_args = 0;
	for (p = entry->copyb; p; p = n) {
		n   = get_irn_link(p);
		src = get_CopyB_src(p);

		/* old scheme using value_res_ent */
		if (is_Sel(src)) {
			ent = get_Sel_entity(src);
			owner = get_entity_owner(ent);

			/* find the hidden parameter index */
			for (idx = 0; idx < get_struct_n_members(owner); ++idx)
				if (get_struct_member(owner, idx) == ent)
					break;
			assert(idx < get_struct_n_members(owner));
507
		} else {
508
509
			/* new scheme: compound returns are determined by the call type and are Proj's */
			idx = get_Proj_proj(src);
510
		}
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541

		ins[idx] = get_CopyB_dst(p);
		mem      = get_CopyB_mem(p);
		blk      = get_nodes_block(p);

		/* get rid of the CopyB */
		turn_into_tuple(p, pn_CopyB_max);
		set_Tuple_pred(p, pn_CopyB_M_regular, mem);
		set_Tuple_pred(p, pn_CopyB_M_except,  get_irg_bad(irg));
		set_Tuple_pred(p, pn_CopyB_X_regular, new_r_Jmp(irg, blk));
		set_Tuple_pred(p, pn_CopyB_X_except,  get_irg_bad(irg));
		++n_args;
	}

	/* now create dummy entities for function with ignored return value */
	if (n_args < n_com) {
		ir_type *ctp = get_Call_type(entry->call);
		int i, j;

		if (is_lowered_type(ctp))
			ctp = get_associated_type(ctp);

		for (j = i = 0; i < get_method_n_ress(ctp); ++i) {
			ir_type *rtp = get_method_res_type(ctp, i);
			if (is_compound_type(rtp)) {
				if (ins[j] == NULL)
					ins[j] = get_dummy_sel(irg, get_nodes_block(entry->call), rtp, env);
				++j;
			}
		}
	}
542
543
544
545
}

/**
 * Fix all calls on a call list by adding hidden parameters.
546
 *
547
548
549
 * @param irg  the graph
 * @param env  the environment
 */
550
static void fix_call_list(ir_graph *irg, wlk_env *env) {
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
	const lower_params_t *lp = env->params;
	cl_entry *p;
	ir_node *call, **new_in;
	ir_type *ctp, *lowered_mtp;
	add_hidden hidden_params;
	int i, n_params, n_com, pos;

	new_in = NEW_ARR_F(ir_node *, 0);
	for (p = env->cl_list; p; p = p->next) {
		call = p->call;
		ctp = get_Call_type(call);
		lowered_mtp = create_modified_mtd_type(lp, ctp);
		set_Call_type(call, lowered_mtp);

		hidden_params = lp->hidden_params;
		if (hidden_params == ADD_HIDDEN_SMART &&
			get_method_variadicity(ctp) == variadicity_variadic)
			hidden_params = ADD_HIDDEN_ALWAYS_IN_FRONT;

		n_params = get_Call_n_params(call);

		n_com = 0;
		for (i = get_method_n_ress(ctp) - 1; i >= 0; --i) {
			if (is_compound_type(get_method_res_type(ctp, i)))
				++n_com;
		}
		pos = 2;
		ARR_RESIZE(ir_node *, new_in, n_params + n_com + pos);
		memset(new_in, 0, sizeof(*new_in) * (n_params + n_com + pos));
		if (hidden_params == ADD_HIDDEN_ALWAYS_IN_FRONT) {
			add_hidden_param(irg, n_com, &new_in[pos], p, env);
			pos += n_com;
		}
		/* copy all other parameters */
		for (i = 0; i < n_params; ++i)
			new_in[pos++] = get_Call_param(call, i);
		if (hidden_params == ADD_HIDDEN_ALWAYS_LAST) {
			add_hidden_param(irg, n_com, &new_in[pos], p, env);
			pos += n_com;
		}
		new_in[0] = get_Call_mem(call);
		new_in[1] = get_Call_ptr(call);

		set_irn_in(call, n_params + n_com + 2, new_in);
	}
596
597
598
599
600
601
602
603
604
}

/**
 * Transform a graph. If it has compound parameter returns,
 * remove them and use the hidden parameter instead.
 * If it calls methods with compound parameter returns, add hidden
 * parameters.
 *
 * @param lp   parameter struct
605
606
607
608
 * @param irg  the graph to transform
 */
static void transform_irg(const lower_params_t *lp, ir_graph *irg)
{
609
610
611
612
613
614
615
	ir_graph   * rem = current_ir_graph;
	ir_entity  *ent = get_irg_entity(irg);
	ir_type    *mtp, *lowered_mtp, *tp, *ft;
	int        i, j, k, n_ress = 0, n_ret_com = 0, n_cr_opt;
	ir_node    **new_in, *ret, *endbl, *bl, *mem, *copy;
	cr_pair    *cr_opt;
	wlk_env    env;
616
617
	add_hidden hidden_params;

618
619
	current_ir_graph = irg;

620
	assert(ent && "Cannot transform graph without an entity");
621
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
	assert(get_irg_phase_state(irg) == phase_high && "call lowering must be done in phase high");

	mtp = get_entity_type(ent);

	if (lp->flags & LF_COMPOUND_RETURN) {
		/* calculate the number of compound returns */
		n_ress = get_method_n_ress(mtp);
		for (n_ret_com = i = 0; i < n_ress; ++i) {
			tp = get_method_res_type(mtp, i);

			if (is_compound_type(tp))
				++n_ret_com;
		}
	}

	if (n_ret_com) {
		/* much easier if we have only one return */
		normalize_one_return(irg);

		/* This graph has a compound argument. Create a new type */
		lowered_mtp = create_modified_mtd_type(lp, mtp);
		set_entity_type(ent, lowered_mtp);

		hidden_params = lp->hidden_params;
		if (hidden_params == ADD_HIDDEN_SMART &&
			get_method_variadicity(mtp) == variadicity_variadic)
			hidden_params = ADD_HIDDEN_ALWAYS_IN_FRONT;

		if (hidden_params == ADD_HIDDEN_ALWAYS_IN_FRONT) {
			/* hidden arguments are added first */
			env.arg_shift    = n_ret_com;
			env.first_hidden = 0;
653
		} else {
654
655
656
657
658
659
660
661
662
			/* hidden arguments are added last */
			env.arg_shift    = 0;
			env.first_hidden = get_method_n_params(mtp);
		}
	} else {
		/* we must only search for calls */
		env.arg_shift = 0;
	}
	obstack_init(&env.obst);
663
664
665
666
667
668
	env.cl_list        = NULL;
	env.dummy_map      = pmap_create_ex(8);
	env.dnr            = 0;
	env.params         = lp;
	env.only_local_mem = 1;
	env.changed        = 0;
669
670
671
672
673
674
675
676
677
678
679
680

	/* scan the code, fix argument numbers and collect calls. */
	irg_walk_graph(irg, firm_clear_link, fix_args_and_collect_calls, &env);

	/* fix all calls */
	if (env.cl_list) {
		fix_call_list(irg, &env);
		env.changed = 1;
	}

	if (n_ret_com) {
		/*
681
682
		 * Now fix the Return node of the current graph.
		 */
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
		env.changed = 1;

		/* STEP 1: find the return. This is simple, we have normalized the graph. */
		endbl = get_irg_end_block(irg);
		ret = NULL;
		for (i = get_Block_n_cfgpreds(endbl) - 1; i >= 0; --i) {
			ir_node *pred = get_Block_cfgpred(endbl, i);

			if (is_Return(pred)) {
				ret = pred;
				break;
			}
		}
		/* there should always be a return */
		assert(ret);

		/*
		 * STEP 2: fix it. For all compound return values add a CopyB,
		 * all others are copied.
		 */
		NEW_ARR_A(ir_node *, new_in, n_ress + 1);

		bl  = get_nodes_block(ret);
		mem = get_Return_mem(ret);

		ft = get_irg_frame_type(irg);
		NEW_ARR_A(cr_pair, cr_opt, n_ret_com);
		n_cr_opt = 0;
		for (j = 1, i = k = 0; i < n_ress; ++i) {
			ir_node *pred = get_Return_res(ret, i);
			tp = get_method_res_type(mtp, i);

			if (is_compound_type(tp)) {
				ir_node *arg = get_irg_args(irg);
				arg = new_r_Proj(irg, get_nodes_block(arg), arg, mode_P_data, env.first_hidden + k);
				++k;

720
721
722
723
				if (is_Unknown(pred)) {
					/* The Return(Unknown) is the Firm construct for a missing return.
					   Do nothing. */
				} else {
724
725
726
727
728
729
730
					/**
					 * Sorrily detecting that copy-return is possible isn't that simple.
					 * We must check, that the hidden address is alias free during the whole
					 * function.
					 * A simple heuristic: all Loads/Stores inside
					 * the function access only local frame.
					 */
731
					if (env.only_local_mem && is_compound_address(ft, pred)) {
732
733
734
735
736
737
738
739
740
741
742
743
744
745
						/* we can do the copy-return optimization here */
						cr_opt[n_cr_opt].ent = get_Sel_entity(pred);
						cr_opt[n_cr_opt].arg = arg;
						++n_cr_opt;
					} else { /* copy-return optimization is impossible, do the copy. */
						copy = new_r_CopyB(
							irg, bl,
							mem,
							arg,
							pred,
							tp
							);
						mem = new_r_Proj(irg, bl, copy, mode_M, pn_CopyB_M_regular);
					}
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
				}
				if (lp->flags & LF_RETURN_HIDDEN) {
					new_in[j] = arg;
					++j;
				}
			} else { /* scalar return value */
				new_in[j] = pred;
				++j;
			}
		}
		/* replace the in of the Return */
		new_in[0] = mem;
		set_irn_in(ret, j, new_in);

		if (n_cr_opt > 0) {
			irg_walk_graph(irg, NULL, do_copy_return_opt, cr_opt);

			for (i = ARR_LEN(cr_opt) - 1; i >= 0; --i) {
				remove_class_member(ft, cr_opt[i].ent);
			}
		}
	} /* if (n_ret_com) */

	pmap_destroy(env.dummy_map);
	obstack_free(&env.obst, NULL);

	if (env.changed) {
		/* invalidate the analysis info */
		set_irg_outs_inconsistent(irg);
		set_irg_loopinfo_state(irg, loopinfo_inconsistent);
	}
777
	current_ir_graph = rem;
778
779
780
781
782
783
}

/**
 * Returns non-zero if the given type is a method
 * type that must be lowered.
 *
784
 * @param lp  lowering parameters
785
786
 * @param tp  The type.
 */
787
static int must_be_lowered(const lower_params_t *lp, ir_type *tp) {
788
789
790
791
  int i, n_ress;
  ir_type *res_tp;

  if (is_Method_type(tp)) {
792
793
794
795
796
797
798
799
800
    if (lp->flags & LF_COMPOUND_RETURN) {
      /* check for compound returns */
      n_ress = get_method_n_ress(tp);
      for (i = 0; i < n_ress; ++i) {
        res_tp = get_method_res_type(tp, i);

        if (is_compound_type(res_tp))
          return 1;
      }
801
802
    }
  }
803
804
  return 0;
}
805

806
807
808
809
810
811
/**
 * type-walker: lower all method types of entities
 * and points-to types.
 */
static void lower_method_types(type_or_ent *tore, void *env)
{
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
	const lower_params_t *lp = env;
	ir_type *tp;

	/* fix method entities */
	if (is_entity(tore)) {
		ir_entity *ent = (ir_entity *)tore;
		tp = get_entity_type(ent);

		if (must_be_lowered(lp, tp)) {
			tp = create_modified_mtd_type(lp, tp);
			set_entity_type(ent, tp);
		}
	} else {
		tp = (ir_type *)tore;

		/* fix pointer to methods */
		if (is_Pointer_type(tp)) {
			ir_type *etp = get_pointer_points_to_type(tp);
			if (must_be_lowered(lp, etp)) {
				etp = create_modified_mtd_type(lp, etp);
				set_pointer_points_to_type(tp, etp);
			}
		}
	}
836
837
838
}

/*
839
 * Lower calls with compound parameters and return types.
840
841
842
843
844
845
846
847
848
849
850
851
852
 * This function does the following transformations:
 *
 * - Adds a new (hidden) pointer parameter for
 *   any return compound type.
 *
 * - Use of the hidden parameters in the function code.
 *
 * - Change all calls to functions with compound return
 *   by providing space for the hidden parameter on the callers
 *   stack.
 *
 * - Replace a possible block copy after the function call.
 */
853
void lower_calls_with_compounds(const lower_params_t *params)
854
{
855
856
857
	int i;
	ir_graph *irg;
	lower_params_t param = *params;
858

859
860
861
	if (param.find_pointer_type == NULL) {
		param.find_pointer_type = def_find_pointer_type;
		type_map = pmap_create_ex(8);
862
	} else
863
		type_map = NULL;
864

865
866
867
	/* first step: Transform all graphs */
	for (i = get_irp_n_irgs() - 1; i >= 0; --i) {
		irg = get_irp_irg(i);
868

869
870
		if (irg == get_const_code_irg())
			continue;
871

872
873
		transform_irg(&param, irg);
	}
874

875
876
	/* second step: Lower all method types of visible entities */
	type_walk(NULL, lower_method_types, &param);
877

878
879
	if (type_map)
		pmap_destroy(type_map);
880
}