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[/] [openrisc/] [trunk/] [gnu-old/] [gcc-4.2.2/] [gcc/] [tree-gimple.c] - Blame information for rev 823

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/* Functions to analyze and validate GIMPLE trees.
2
   Copyright (C) 2002, 2003, 2004, 2005, 2007 Free Software Foundation, Inc.
3
   Contributed by Diego Novillo <dnovillo@redhat.com>
4
   Rewritten by Jason Merrill <jason@redhat.com>
5
 
6
This file is part of GCC.
7
 
8
GCC is free software; you can redistribute it and/or modify
9
it under the terms of the GNU General Public License as published by
10
the Free Software Foundation; either version 3, or (at your option)
11
any later version.
12
 
13
GCC is distributed in the hope that it will be useful,
14
but WITHOUT ANY WARRANTY; without even the implied warranty of
15
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16
GNU General Public License for more details.
17
 
18
You should have received a copy of the GNU General Public License
19
along with GCC; see the file COPYING3.  If not see
20
<http://www.gnu.org/licenses/>.  */
21
 
22
#include "config.h"
23
#include "system.h"
24
#include "coretypes.h"
25
#include "ggc.h"
26
#include "tm.h"
27
#include "tree.h"
28
#include "tree-gimple.h"
29
#include "tree-flow.h"
30
#include "output.h"
31
#include "rtl.h"
32
#include "expr.h"
33
#include "bitmap.h"
34
 
35
/* For the definitive definition of GIMPLE, see doc/tree-ssa.texi.  */
36
 
37
/* Validation of GIMPLE expressions.  */
38
 
39
/* Return true if T is a GIMPLE RHS for an assignment to a temporary.  */
40
 
41
bool
42
is_gimple_formal_tmp_rhs (tree t)
43
{
44
  enum tree_code code = TREE_CODE (t);
45
 
46
  switch (TREE_CODE_CLASS (code))
47
    {
48
    case tcc_unary:
49
    case tcc_binary:
50
    case tcc_comparison:
51
      return true;
52
 
53
    default:
54
      break;
55
    }
56
 
57
  switch (code)
58
    {
59
    case TRUTH_NOT_EXPR:
60
    case TRUTH_AND_EXPR:
61
    case TRUTH_OR_EXPR:
62
    case TRUTH_XOR_EXPR:
63
    case ADDR_EXPR:
64
    case CALL_EXPR:
65
    case CONSTRUCTOR:
66
    case COMPLEX_EXPR:
67
    case INTEGER_CST:
68
    case REAL_CST:
69
    case STRING_CST:
70
    case COMPLEX_CST:
71
    case VECTOR_CST:
72
    case OBJ_TYPE_REF:
73
    case ASSERT_EXPR:
74
      return true;
75
 
76
    default:
77
      break;
78
    }
79
 
80
  return is_gimple_lvalue (t) || is_gimple_val (t);
81
}
82
 
83
/* Returns true iff T is a valid RHS for an assignment to a renamed
84
   user -- or front-end generated artificial -- variable.  */
85
 
86
bool
87
is_gimple_reg_rhs (tree t)
88
{
89
  /* If the RHS of the MODIFY_EXPR may throw or make a nonlocal goto
90
     and the LHS is a user variable, then we need to introduce a formal
91
     temporary.  This way the optimizers can determine that the user
92
     variable is only modified if evaluation of the RHS does not throw.
93
 
94
     Don't force a temp of a non-renamable type; the copy could be
95
     arbitrarily expensive.  Instead we will generate a V_MAY_DEF for
96
     the assignment.  */
97
 
98
  if (is_gimple_reg_type (TREE_TYPE (t))
99
      && ((TREE_CODE (t) == CALL_EXPR && TREE_SIDE_EFFECTS (t))
100
          || tree_could_throw_p (t)))
101
    return false;
102
 
103
  return is_gimple_formal_tmp_rhs (t);
104
}
105
 
106
/* Returns true iff T is a valid RHS for an assignment to an un-renamed
107
   LHS, or for a call argument.  */
108
 
109
bool
110
is_gimple_mem_rhs (tree t)
111
{
112
  /* If we're dealing with a renamable type, either source or dest must be
113
     a renamed variable.  Also force a temporary if the type doesn't need
114
     to be stored in memory, since it's cheap and prevents erroneous
115
     tailcalls (PR 17526).  */
116
  if (is_gimple_reg_type (TREE_TYPE (t))
117
      || (TYPE_MODE (TREE_TYPE (t)) != BLKmode
118
          && (TREE_CODE (t) != CALL_EXPR
119
              || ! aggregate_value_p (t, t))))
120
    return is_gimple_val (t);
121
  else
122
    return is_gimple_formal_tmp_rhs (t);
123
}
124
 
125
/* Returns the appropriate RHS predicate for this LHS.  */
126
 
127
gimple_predicate
128
rhs_predicate_for (tree lhs)
129
{
130
  if (is_gimple_formal_tmp_var (lhs))
131
    return is_gimple_formal_tmp_rhs;
132
  else if (is_gimple_reg (lhs))
133
    return is_gimple_reg_rhs;
134
  else
135
    return is_gimple_mem_rhs;
136
}
137
 
138
/*  Return true if T is a valid LHS for a GIMPLE assignment expression.  */
139
 
140
bool
141
is_gimple_lvalue (tree t)
142
{
143
  return (is_gimple_addressable (t)
144
          || TREE_CODE (t) == WITH_SIZE_EXPR
145
          /* These are complex lvalues, but don't have addresses, so they
146
             go here.  */
147
          || TREE_CODE (t) == BIT_FIELD_REF);
148
}
149
 
150
/*  Return true if T is a GIMPLE condition.  */
151
 
152
bool
153
is_gimple_condexpr (tree t)
154
{
155
  return (is_gimple_val (t) || COMPARISON_CLASS_P (t));
156
}
157
 
158
/*  Return true if T is something whose address can be taken.  */
159
 
160
bool
161
is_gimple_addressable (tree t)
162
{
163
  return (is_gimple_id (t) || handled_component_p (t)
164
          || INDIRECT_REF_P (t));
165
}
166
 
167
/* Return true if T is function invariant.  Or rather a restricted
168
   form of function invariant.  */
169
 
170
bool
171
is_gimple_min_invariant (tree t)
172
{
173
  switch (TREE_CODE (t))
174
    {
175
    case ADDR_EXPR:
176
      return TREE_INVARIANT (t);
177
 
178
    case INTEGER_CST:
179
    case REAL_CST:
180
    case STRING_CST:
181
    case COMPLEX_CST:
182
    case VECTOR_CST:
183
      return true;
184
 
185
    default:
186
      return false;
187
    }
188
}
189
 
190
/* Return true if T looks like a valid GIMPLE statement.  */
191
 
192
bool
193
is_gimple_stmt (tree t)
194
{
195
  enum tree_code code = TREE_CODE (t);
196
 
197
  switch (code)
198
    {
199
    case NOP_EXPR:
200
      /* The only valid NOP_EXPR is the empty statement.  */
201
      return IS_EMPTY_STMT (t);
202
 
203
    case BIND_EXPR:
204
    case COND_EXPR:
205
      /* These are only valid if they're void.  */
206
      return TREE_TYPE (t) == NULL || VOID_TYPE_P (TREE_TYPE (t));
207
 
208
    case SWITCH_EXPR:
209
    case GOTO_EXPR:
210
    case RETURN_EXPR:
211
    case LABEL_EXPR:
212
    case CASE_LABEL_EXPR:
213
    case TRY_CATCH_EXPR:
214
    case TRY_FINALLY_EXPR:
215
    case EH_FILTER_EXPR:
216
    case CATCH_EXPR:
217
    case ASM_EXPR:
218
    case RESX_EXPR:
219
    case PHI_NODE:
220
    case STATEMENT_LIST:
221
    case OMP_PARALLEL:
222
    case OMP_FOR:
223
    case OMP_SECTIONS:
224
    case OMP_SECTION:
225
    case OMP_SINGLE:
226
    case OMP_MASTER:
227
    case OMP_ORDERED:
228
    case OMP_CRITICAL:
229
    case OMP_RETURN:
230
    case OMP_CONTINUE:
231
      /* These are always void.  */
232
      return true;
233
 
234
    case CALL_EXPR:
235
    case MODIFY_EXPR:
236
      /* These are valid regardless of their type.  */
237
      return true;
238
 
239
    default:
240
      return false;
241
    }
242
}
243
 
244
/* Return true if T is a variable.  */
245
 
246
bool
247
is_gimple_variable (tree t)
248
{
249
  return (TREE_CODE (t) == VAR_DECL
250
          || TREE_CODE (t) == PARM_DECL
251
          || TREE_CODE (t) == RESULT_DECL
252
          || TREE_CODE (t) == SSA_NAME);
253
}
254
 
255
/*  Return true if T is a GIMPLE identifier (something with an address).  */
256
 
257
bool
258
is_gimple_id (tree t)
259
{
260
  return (is_gimple_variable (t)
261
          || TREE_CODE (t) == FUNCTION_DECL
262
          || TREE_CODE (t) == LABEL_DECL
263
          || TREE_CODE (t) == CONST_DECL
264
          /* Allow string constants, since they are addressable.  */
265
          || TREE_CODE (t) == STRING_CST);
266
}
267
 
268
/* Return true if TYPE is a suitable type for a scalar register variable.  */
269
 
270
bool
271
is_gimple_reg_type (tree type)
272
{
273
  return !AGGREGATE_TYPE_P (type);
274
}
275
 
276
/* Return true if T is a non-aggregate register variable.  */
277
 
278
bool
279
is_gimple_reg (tree t)
280
{
281
  if (TREE_CODE (t) == SSA_NAME)
282
    t = SSA_NAME_VAR (t);
283
 
284
  if (MTAG_P (t))
285
    return false;
286
 
287
  if (!is_gimple_variable (t))
288
    return false;
289
 
290
  if (!is_gimple_reg_type (TREE_TYPE (t)))
291
    return false;
292
 
293
  /* A volatile decl is not acceptable because we can't reuse it as
294
     needed.  We need to copy it into a temp first.  */
295
  if (TREE_THIS_VOLATILE (t))
296
    return false;
297
 
298
  /* We define "registers" as things that can be renamed as needed,
299
     which with our infrastructure does not apply to memory.  */
300
  if (needs_to_live_in_memory (t))
301
    return false;
302
 
303
  /* Hard register variables are an interesting case.  For those that
304
     are call-clobbered, we don't know where all the calls are, since
305
     we don't (want to) take into account which operations will turn
306
     into libcalls at the rtl level.  For those that are call-saved,
307
     we don't currently model the fact that calls may in fact change
308
     global hard registers, nor do we examine ASM_CLOBBERS at the tree
309
     level, and so miss variable changes that might imply.  All around,
310
     it seems safest to not do too much optimization with these at the
311
     tree level at all.  We'll have to rely on the rtl optimizers to
312
     clean this up, as there we've got all the appropriate bits exposed.  */
313
  if (TREE_CODE (t) == VAR_DECL && DECL_HARD_REGISTER (t))
314
    return false;
315
 
316
  /* Complex values must have been put into ssa form.  That is, no
317
     assignments to the individual components.  */
318
  if (TREE_CODE (TREE_TYPE (t)) == COMPLEX_TYPE)
319
    return DECL_COMPLEX_GIMPLE_REG_P (t);
320
 
321
  return true;
322
}
323
 
324
 
325
/* Returns true if T is a GIMPLE formal temporary variable.  */
326
 
327
bool
328
is_gimple_formal_tmp_var (tree t)
329
{
330
  if (TREE_CODE (t) == SSA_NAME)
331
    return true;
332
 
333
  return TREE_CODE (t) == VAR_DECL && DECL_GIMPLE_FORMAL_TEMP_P (t);
334
}
335
 
336
/* Returns true if T is a GIMPLE formal temporary register variable.  */
337
 
338
bool
339
is_gimple_formal_tmp_reg (tree t)
340
{
341
  /* The intent of this is to get hold of a value that won't change.
342
     An SSA_NAME qualifies no matter if its of a user variable or not.  */
343
  if (TREE_CODE (t) == SSA_NAME)
344
    return true;
345
 
346
  /* We don't know the lifetime characteristics of user variables.  */
347
  if (!is_gimple_formal_tmp_var (t))
348
    return false;
349
 
350
  /* Finally, it must be capable of being placed in a register.  */
351
  return is_gimple_reg (t);
352
}
353
 
354
/* Return true if T is a GIMPLE variable whose address is not needed.  */
355
 
356
bool
357
is_gimple_non_addressable (tree t)
358
{
359
  if (TREE_CODE (t) == SSA_NAME)
360
    t = SSA_NAME_VAR (t);
361
 
362
  return (is_gimple_variable (t) && ! needs_to_live_in_memory (t));
363
}
364
 
365
/* Return true if T is a GIMPLE rvalue, i.e. an identifier or a constant.  */
366
 
367
bool
368
is_gimple_val (tree t)
369
{
370
  /* Make loads from volatiles and memory vars explicit.  */
371
  if (is_gimple_variable (t)
372
      && is_gimple_reg_type (TREE_TYPE (t))
373
      && !is_gimple_reg (t))
374
    return false;
375
 
376
  /* FIXME make these decls.  That can happen only when we expose the
377
     entire landing-pad construct at the tree level.  */
378
  if (TREE_CODE (t) == EXC_PTR_EXPR || TREE_CODE (t) == FILTER_EXPR)
379
    return 1;
380
 
381
  return (is_gimple_variable (t) || is_gimple_min_invariant (t));
382
}
383
 
384
/* Similarly, but accept hard registers as inputs to asm statements.  */
385
 
386
bool
387
is_gimple_asm_val (tree t)
388
{
389
  if (TREE_CODE (t) == VAR_DECL && DECL_HARD_REGISTER (t))
390
    return true;
391
 
392
  return is_gimple_val (t);
393
}
394
 
395
/* Return true if T is a GIMPLE minimal lvalue.  */
396
 
397
bool
398
is_gimple_min_lval (tree t)
399
{
400
  return (is_gimple_id (t)
401
          || TREE_CODE (t) == INDIRECT_REF);
402
}
403
 
404
/* Return true if T is a typecast operation.  */
405
 
406
bool
407
is_gimple_cast (tree t)
408
{
409
  return (TREE_CODE (t) == NOP_EXPR
410
          || TREE_CODE (t) == CONVERT_EXPR
411
          || TREE_CODE (t) == FIX_TRUNC_EXPR
412
          || TREE_CODE (t) == FIX_CEIL_EXPR
413
          || TREE_CODE (t) == FIX_FLOOR_EXPR
414
          || TREE_CODE (t) == FIX_ROUND_EXPR);
415
}
416
 
417
/* Return true if T is a valid op0 of a CALL_EXPR.  */
418
 
419
bool
420
is_gimple_call_addr (tree t)
421
{
422
  return (TREE_CODE (t) == OBJ_TYPE_REF
423
          || is_gimple_val (t));
424
}
425
 
426
/* If T makes a function call, return the corresponding CALL_EXPR operand.
427
   Otherwise, return NULL_TREE.  */
428
 
429
tree
430
get_call_expr_in (tree t)
431
{
432
  if (TREE_CODE (t) == MODIFY_EXPR)
433
    t = TREE_OPERAND (t, 1);
434
  if (TREE_CODE (t) == WITH_SIZE_EXPR)
435
    t = TREE_OPERAND (t, 0);
436
  if (TREE_CODE (t) == CALL_EXPR)
437
    return t;
438
  return NULL_TREE;
439
}
440
 
441
/* Given a memory reference expression T, return its base address.
442
   The base address of a memory reference expression is the main
443
   object being referenced.  For instance, the base address for
444
   'array[i].fld[j]' is 'array'.  You can think of this as stripping
445
   away the offset part from a memory address.
446
 
447
   This function calls handled_component_p to strip away all the inner
448
   parts of the memory reference until it reaches the base object.  */
449
 
450
tree
451
get_base_address (tree t)
452
{
453
  while (handled_component_p (t))
454
    t = TREE_OPERAND (t, 0);
455
 
456
  if (SSA_VAR_P (t)
457
      || TREE_CODE (t) == STRING_CST
458
      || TREE_CODE (t) == CONSTRUCTOR
459
      || INDIRECT_REF_P (t))
460
    return t;
461
  else
462
    return NULL_TREE;
463
}
464
 
465
void
466
recalculate_side_effects (tree t)
467
{
468
  enum tree_code code = TREE_CODE (t);
469
  int len = TREE_CODE_LENGTH (code);
470
  int i;
471
 
472
  switch (TREE_CODE_CLASS (code))
473
    {
474
    case tcc_expression:
475
      switch (code)
476
        {
477
        case INIT_EXPR:
478
        case MODIFY_EXPR:
479
        case VA_ARG_EXPR:
480
        case PREDECREMENT_EXPR:
481
        case PREINCREMENT_EXPR:
482
        case POSTDECREMENT_EXPR:
483
        case POSTINCREMENT_EXPR:
484
          /* All of these have side-effects, no matter what their
485
             operands are.  */
486
          return;
487
 
488
        default:
489
          break;
490
        }
491
      /* Fall through.  */
492
 
493
    case tcc_comparison:  /* a comparison expression */
494
    case tcc_unary:       /* a unary arithmetic expression */
495
    case tcc_binary:      /* a binary arithmetic expression */
496
    case tcc_reference:   /* a reference */
497
      TREE_SIDE_EFFECTS (t) = TREE_THIS_VOLATILE (t);
498
      for (i = 0; i < len; ++i)
499
        {
500
          tree op = TREE_OPERAND (t, i);
501
          if (op && TREE_SIDE_EFFECTS (op))
502
            TREE_SIDE_EFFECTS (t) = 1;
503
        }
504
      break;
505
 
506
    default:
507
      /* Can never be used with non-expressions.  */
508
      gcc_unreachable ();
509
   }
510
}

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