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comparison gcc/stor-layout.c @ 0:a06113de4d67

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author kent <kent@cr.ie.u-ryukyu.ac.jp>
date Fri, 17 Jul 2009 14:47:48 +0900
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-1:000000000000 0:a06113de4d67
1 /* C-compiler utilities for types and variables storage layout
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1996, 1998,
3 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
4 Free Software Foundation, Inc.
5
6 This file is part of GCC.
7
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
11 version.
12
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 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
23 #include "config.h"
24 #include "system.h"
25 #include "coretypes.h"
26 #include "tm.h"
27 #include "tree.h"
28 #include "rtl.h"
29 #include "tm_p.h"
30 #include "flags.h"
31 #include "function.h"
32 #include "expr.h"
33 #include "output.h"
34 #include "toplev.h"
35 #include "ggc.h"
36 #include "target.h"
37 #include "langhooks.h"
38 #include "regs.h"
39 #include "params.h"
40
41 /* Data type for the expressions representing sizes of data types.
42 It is the first integer type laid out. */
43 tree sizetype_tab[(int) TYPE_KIND_LAST];
44
45 /* If nonzero, this is an upper limit on alignment of structure fields.
46 The value is measured in bits. */
47 unsigned int maximum_field_alignment = TARGET_DEFAULT_PACK_STRUCT * BITS_PER_UNIT;
48 /* ... and its original value in bytes, specified via -fpack-struct=<value>. */
49 unsigned int initial_max_fld_align = TARGET_DEFAULT_PACK_STRUCT;
50
51 /* Nonzero if all REFERENCE_TYPEs are internal and hence should be
52 allocated in Pmode, not ptr_mode. Set only by internal_reference_types
53 called only by a front end. */
54 static int reference_types_internal = 0;
55
56 static void finalize_record_size (record_layout_info);
57 static void finalize_type_size (tree);
58 static void place_union_field (record_layout_info, tree);
59 #if defined (PCC_BITFIELD_TYPE_MATTERS) || defined (BITFIELD_NBYTES_LIMITED)
60 static int excess_unit_span (HOST_WIDE_INT, HOST_WIDE_INT, HOST_WIDE_INT,
61 HOST_WIDE_INT, tree);
62 #endif
63 extern void debug_rli (record_layout_info);
64
65 /* SAVE_EXPRs for sizes of types and decls, waiting to be expanded. */
66
67 static GTY(()) tree pending_sizes;
68
69 /* Show that REFERENCE_TYPES are internal and should be Pmode. Called only
70 by front end. */
71
72 void
73 internal_reference_types (void)
74 {
75 reference_types_internal = 1;
76 }
77
78 /* Get a list of all the objects put on the pending sizes list. */
79
80 tree
81 get_pending_sizes (void)
82 {
83 tree chain = pending_sizes;
84
85 pending_sizes = 0;
86 return chain;
87 }
88
89 /* Add EXPR to the pending sizes list. */
90
91 void
92 put_pending_size (tree expr)
93 {
94 /* Strip any simple arithmetic from EXPR to see if it has an underlying
95 SAVE_EXPR. */
96 expr = skip_simple_arithmetic (expr);
97
98 if (TREE_CODE (expr) == SAVE_EXPR)
99 pending_sizes = tree_cons (NULL_TREE, expr, pending_sizes);
100 }
101
102 /* Put a chain of objects into the pending sizes list, which must be
103 empty. */
104
105 void
106 put_pending_sizes (tree chain)
107 {
108 gcc_assert (!pending_sizes);
109 pending_sizes = chain;
110 }
111
112 /* Given a size SIZE that may not be a constant, return a SAVE_EXPR
113 to serve as the actual size-expression for a type or decl. */
114
115 tree
116 variable_size (tree size)
117 {
118 tree save;
119
120 /* If the language-processor is to take responsibility for variable-sized
121 items (e.g., languages which have elaboration procedures like Ada),
122 just return SIZE unchanged. Likewise for self-referential sizes and
123 constant sizes. */
124 if (TREE_CONSTANT (size)
125 || lang_hooks.decls.global_bindings_p () < 0
126 || CONTAINS_PLACEHOLDER_P (size))
127 return size;
128
129 size = save_expr (size);
130
131 /* If an array with a variable number of elements is declared, and
132 the elements require destruction, we will emit a cleanup for the
133 array. That cleanup is run both on normal exit from the block
134 and in the exception-handler for the block. Normally, when code
135 is used in both ordinary code and in an exception handler it is
136 `unsaved', i.e., all SAVE_EXPRs are recalculated. However, we do
137 not wish to do that here; the array-size is the same in both
138 places. */
139 save = skip_simple_arithmetic (size);
140
141 if (cfun && cfun->dont_save_pending_sizes_p)
142 /* The front-end doesn't want us to keep a list of the expressions
143 that determine sizes for variable size objects. Trust it. */
144 return size;
145
146 if (lang_hooks.decls.global_bindings_p ())
147 {
148 if (TREE_CONSTANT (size))
149 error ("type size can%'t be explicitly evaluated");
150 else
151 error ("variable-size type declared outside of any function");
152
153 return size_one_node;
154 }
155
156 put_pending_size (save);
157
158 return size;
159 }
160
161 #ifndef MAX_FIXED_MODE_SIZE
162 #define MAX_FIXED_MODE_SIZE GET_MODE_BITSIZE (DImode)
163 #endif
164
165 /* Return the machine mode to use for a nonscalar of SIZE bits. The
166 mode must be in class MCLASS, and have exactly that many value bits;
167 it may have padding as well. If LIMIT is nonzero, modes of wider
168 than MAX_FIXED_MODE_SIZE will not be used. */
169
170 enum machine_mode
171 mode_for_size (unsigned int size, enum mode_class mclass, int limit)
172 {
173 enum machine_mode mode;
174
175 if (limit && size > MAX_FIXED_MODE_SIZE)
176 return BLKmode;
177
178 /* Get the first mode which has this size, in the specified class. */
179 for (mode = GET_CLASS_NARROWEST_MODE (mclass); mode != VOIDmode;
180 mode = GET_MODE_WIDER_MODE (mode))
181 if (GET_MODE_PRECISION (mode) == size)
182 return mode;
183
184 return BLKmode;
185 }
186
187 /* Similar, except passed a tree node. */
188
189 enum machine_mode
190 mode_for_size_tree (const_tree size, enum mode_class mclass, int limit)
191 {
192 unsigned HOST_WIDE_INT uhwi;
193 unsigned int ui;
194
195 if (!host_integerp (size, 1))
196 return BLKmode;
197 uhwi = tree_low_cst (size, 1);
198 ui = uhwi;
199 if (uhwi != ui)
200 return BLKmode;
201 return mode_for_size (ui, mclass, limit);
202 }
203
204 /* Similar, but never return BLKmode; return the narrowest mode that
205 contains at least the requested number of value bits. */
206
207 enum machine_mode
208 smallest_mode_for_size (unsigned int size, enum mode_class mclass)
209 {
210 enum machine_mode mode;
211
212 /* Get the first mode which has at least this size, in the
213 specified class. */
214 for (mode = GET_CLASS_NARROWEST_MODE (mclass); mode != VOIDmode;
215 mode = GET_MODE_WIDER_MODE (mode))
216 if (GET_MODE_PRECISION (mode) >= size)
217 return mode;
218
219 gcc_unreachable ();
220 }
221
222 /* Find an integer mode of the exact same size, or BLKmode on failure. */
223
224 enum machine_mode
225 int_mode_for_mode (enum machine_mode mode)
226 {
227 switch (GET_MODE_CLASS (mode))
228 {
229 case MODE_INT:
230 case MODE_PARTIAL_INT:
231 break;
232
233 case MODE_COMPLEX_INT:
234 case MODE_COMPLEX_FLOAT:
235 case MODE_FLOAT:
236 case MODE_DECIMAL_FLOAT:
237 case MODE_VECTOR_INT:
238 case MODE_VECTOR_FLOAT:
239 case MODE_FRACT:
240 case MODE_ACCUM:
241 case MODE_UFRACT:
242 case MODE_UACCUM:
243 case MODE_VECTOR_FRACT:
244 case MODE_VECTOR_ACCUM:
245 case MODE_VECTOR_UFRACT:
246 case MODE_VECTOR_UACCUM:
247 mode = mode_for_size (GET_MODE_BITSIZE (mode), MODE_INT, 0);
248 break;
249
250 case MODE_RANDOM:
251 if (mode == BLKmode)
252 break;
253
254 /* ... fall through ... */
255
256 case MODE_CC:
257 default:
258 gcc_unreachable ();
259 }
260
261 return mode;
262 }
263
264 /* Return the alignment of MODE. This will be bounded by 1 and
265 BIGGEST_ALIGNMENT. */
266
267 unsigned int
268 get_mode_alignment (enum machine_mode mode)
269 {
270 return MIN (BIGGEST_ALIGNMENT, MAX (1, mode_base_align[mode]*BITS_PER_UNIT));
271 }
272
273
274 /* Subroutine of layout_decl: Force alignment required for the data type.
275 But if the decl itself wants greater alignment, don't override that. */
276
277 static inline void
278 do_type_align (tree type, tree decl)
279 {
280 if (TYPE_ALIGN (type) > DECL_ALIGN (decl))
281 {
282 DECL_ALIGN (decl) = TYPE_ALIGN (type);
283 if (TREE_CODE (decl) == FIELD_DECL)
284 DECL_USER_ALIGN (decl) = TYPE_USER_ALIGN (type);
285 }
286 }
287
288 /* Set the size, mode and alignment of a ..._DECL node.
289 TYPE_DECL does need this for C++.
290 Note that LABEL_DECL and CONST_DECL nodes do not need this,
291 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
292 Don't call layout_decl for them.
293
294 KNOWN_ALIGN is the amount of alignment we can assume this
295 decl has with no special effort. It is relevant only for FIELD_DECLs
296 and depends on the previous fields.
297 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
298 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
299 the record will be aligned to suit. */
300
301 void
302 layout_decl (tree decl, unsigned int known_align)
303 {
304 tree type = TREE_TYPE (decl);
305 enum tree_code code = TREE_CODE (decl);
306 rtx rtl = NULL_RTX;
307
308 if (code == CONST_DECL)
309 return;
310
311 gcc_assert (code == VAR_DECL || code == PARM_DECL || code == RESULT_DECL
312 || code == TYPE_DECL ||code == FIELD_DECL);
313
314 rtl = DECL_RTL_IF_SET (decl);
315
316 if (type == error_mark_node)
317 type = void_type_node;
318
319 /* Usually the size and mode come from the data type without change,
320 however, the front-end may set the explicit width of the field, so its
321 size may not be the same as the size of its type. This happens with
322 bitfields, of course (an `int' bitfield may be only 2 bits, say), but it
323 also happens with other fields. For example, the C++ front-end creates
324 zero-sized fields corresponding to empty base classes, and depends on
325 layout_type setting DECL_FIELD_BITPOS correctly for the field. Set the
326 size in bytes from the size in bits. If we have already set the mode,
327 don't set it again since we can be called twice for FIELD_DECLs. */
328
329 DECL_UNSIGNED (decl) = TYPE_UNSIGNED (type);
330 if (DECL_MODE (decl) == VOIDmode)
331 DECL_MODE (decl) = TYPE_MODE (type);
332
333 if (DECL_SIZE (decl) == 0)
334 {
335 DECL_SIZE (decl) = TYPE_SIZE (type);
336 DECL_SIZE_UNIT (decl) = TYPE_SIZE_UNIT (type);
337 }
338 else if (DECL_SIZE_UNIT (decl) == 0)
339 DECL_SIZE_UNIT (decl)
340 = fold_convert (sizetype, size_binop (CEIL_DIV_EXPR, DECL_SIZE (decl),
341 bitsize_unit_node));
342
343 if (code != FIELD_DECL)
344 /* For non-fields, update the alignment from the type. */
345 do_type_align (type, decl);
346 else
347 /* For fields, it's a bit more complicated... */
348 {
349 bool old_user_align = DECL_USER_ALIGN (decl);
350 bool zero_bitfield = false;
351 bool packed_p = DECL_PACKED (decl);
352 unsigned int mfa;
353
354 if (DECL_BIT_FIELD (decl))
355 {
356 DECL_BIT_FIELD_TYPE (decl) = type;
357
358 /* A zero-length bit-field affects the alignment of the next
359 field. In essence such bit-fields are not influenced by
360 any packing due to #pragma pack or attribute packed. */
361 if (integer_zerop (DECL_SIZE (decl))
362 && ! targetm.ms_bitfield_layout_p (DECL_FIELD_CONTEXT (decl)))
363 {
364 zero_bitfield = true;
365 packed_p = false;
366 #ifdef PCC_BITFIELD_TYPE_MATTERS
367 if (PCC_BITFIELD_TYPE_MATTERS)
368 do_type_align (type, decl);
369 else
370 #endif
371 {
372 #ifdef EMPTY_FIELD_BOUNDARY
373 if (EMPTY_FIELD_BOUNDARY > DECL_ALIGN (decl))
374 {
375 DECL_ALIGN (decl) = EMPTY_FIELD_BOUNDARY;
376 DECL_USER_ALIGN (decl) = 0;
377 }
378 #endif
379 }
380 }
381
382 /* See if we can use an ordinary integer mode for a bit-field.
383 Conditions are: a fixed size that is correct for another mode
384 and occupying a complete byte or bytes on proper boundary. */
385 if (TYPE_SIZE (type) != 0
386 && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
387 && GET_MODE_CLASS (TYPE_MODE (type)) == MODE_INT)
388 {
389 enum machine_mode xmode
390 = mode_for_size_tree (DECL_SIZE (decl), MODE_INT, 1);
391 unsigned int xalign = GET_MODE_ALIGNMENT (xmode);
392
393 if (xmode != BLKmode
394 && !(xalign > BITS_PER_UNIT && DECL_PACKED (decl))
395 && (known_align == 0 || known_align >= xalign))
396 {
397 DECL_ALIGN (decl) = MAX (xalign, DECL_ALIGN (decl));
398 DECL_MODE (decl) = xmode;
399 DECL_BIT_FIELD (decl) = 0;
400 }
401 }
402
403 /* Turn off DECL_BIT_FIELD if we won't need it set. */
404 if (TYPE_MODE (type) == BLKmode && DECL_MODE (decl) == BLKmode
405 && known_align >= TYPE_ALIGN (type)
406 && DECL_ALIGN (decl) >= TYPE_ALIGN (type))
407 DECL_BIT_FIELD (decl) = 0;
408 }
409 else if (packed_p && DECL_USER_ALIGN (decl))
410 /* Don't touch DECL_ALIGN. For other packed fields, go ahead and
411 round up; we'll reduce it again below. We want packing to
412 supersede USER_ALIGN inherited from the type, but defer to
413 alignment explicitly specified on the field decl. */;
414 else
415 do_type_align (type, decl);
416
417 /* If the field is packed and not explicitly aligned, give it the
418 minimum alignment. Note that do_type_align may set
419 DECL_USER_ALIGN, so we need to check old_user_align instead. */
420 if (packed_p
421 && !old_user_align)
422 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), BITS_PER_UNIT);
423
424 if (! packed_p && ! DECL_USER_ALIGN (decl))
425 {
426 /* Some targets (i.e. i386, VMS) limit struct field alignment
427 to a lower boundary than alignment of variables unless
428 it was overridden by attribute aligned. */
429 #ifdef BIGGEST_FIELD_ALIGNMENT
430 DECL_ALIGN (decl)
431 = MIN (DECL_ALIGN (decl), (unsigned) BIGGEST_FIELD_ALIGNMENT);
432 #endif
433 #ifdef ADJUST_FIELD_ALIGN
434 DECL_ALIGN (decl) = ADJUST_FIELD_ALIGN (decl, DECL_ALIGN (decl));
435 #endif
436 }
437
438 if (zero_bitfield)
439 mfa = initial_max_fld_align * BITS_PER_UNIT;
440 else
441 mfa = maximum_field_alignment;
442 /* Should this be controlled by DECL_USER_ALIGN, too? */
443 if (mfa != 0)
444 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), mfa);
445 }
446
447 /* Evaluate nonconstant size only once, either now or as soon as safe. */
448 if (DECL_SIZE (decl) != 0 && TREE_CODE (DECL_SIZE (decl)) != INTEGER_CST)
449 DECL_SIZE (decl) = variable_size (DECL_SIZE (decl));
450 if (DECL_SIZE_UNIT (decl) != 0
451 && TREE_CODE (DECL_SIZE_UNIT (decl)) != INTEGER_CST)
452 DECL_SIZE_UNIT (decl) = variable_size (DECL_SIZE_UNIT (decl));
453
454 /* If requested, warn about definitions of large data objects. */
455 if (warn_larger_than
456 && (code == VAR_DECL || code == PARM_DECL)
457 && ! DECL_EXTERNAL (decl))
458 {
459 tree size = DECL_SIZE_UNIT (decl);
460
461 if (size != 0 && TREE_CODE (size) == INTEGER_CST
462 && compare_tree_int (size, larger_than_size) > 0)
463 {
464 int size_as_int = TREE_INT_CST_LOW (size);
465
466 if (compare_tree_int (size, size_as_int) == 0)
467 warning (OPT_Wlarger_than_eq, "size of %q+D is %d bytes", decl, size_as_int);
468 else
469 warning (OPT_Wlarger_than_eq, "size of %q+D is larger than %wd bytes",
470 decl, larger_than_size);
471 }
472 }
473
474 /* If the RTL was already set, update its mode and mem attributes. */
475 if (rtl)
476 {
477 PUT_MODE (rtl, DECL_MODE (decl));
478 SET_DECL_RTL (decl, 0);
479 set_mem_attributes (rtl, decl, 1);
480 SET_DECL_RTL (decl, rtl);
481 }
482 }
483
484 /* Given a VAR_DECL, PARM_DECL or RESULT_DECL, clears the results of
485 a previous call to layout_decl and calls it again. */
486
487 void
488 relayout_decl (tree decl)
489 {
490 DECL_SIZE (decl) = DECL_SIZE_UNIT (decl) = 0;
491 DECL_MODE (decl) = VOIDmode;
492 if (!DECL_USER_ALIGN (decl))
493 DECL_ALIGN (decl) = 0;
494 SET_DECL_RTL (decl, 0);
495
496 layout_decl (decl, 0);
497 }
498
499 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
500 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
501 is to be passed to all other layout functions for this record. It is the
502 responsibility of the caller to call `free' for the storage returned.
503 Note that garbage collection is not permitted until we finish laying
504 out the record. */
505
506 record_layout_info
507 start_record_layout (tree t)
508 {
509 record_layout_info rli = XNEW (struct record_layout_info_s);
510
511 rli->t = t;
512
513 /* If the type has a minimum specified alignment (via an attribute
514 declaration, for example) use it -- otherwise, start with a
515 one-byte alignment. */
516 rli->record_align = MAX (BITS_PER_UNIT, TYPE_ALIGN (t));
517 rli->unpacked_align = rli->record_align;
518 rli->offset_align = MAX (rli->record_align, BIGGEST_ALIGNMENT);
519
520 #ifdef STRUCTURE_SIZE_BOUNDARY
521 /* Packed structures don't need to have minimum size. */
522 if (! TYPE_PACKED (t))
523 {
524 unsigned tmp;
525
526 /* #pragma pack overrides STRUCTURE_SIZE_BOUNDARY. */
527 tmp = (unsigned) STRUCTURE_SIZE_BOUNDARY;
528 if (maximum_field_alignment != 0)
529 tmp = MIN (tmp, maximum_field_alignment);
530 rli->record_align = MAX (rli->record_align, tmp);
531 }
532 #endif
533
534 rli->offset = size_zero_node;
535 rli->bitpos = bitsize_zero_node;
536 rli->prev_field = 0;
537 rli->pending_statics = 0;
538 rli->packed_maybe_necessary = 0;
539 rli->remaining_in_alignment = 0;
540
541 return rli;
542 }
543
544 /* These four routines perform computations that convert between
545 the offset/bitpos forms and byte and bit offsets. */
546
547 tree
548 bit_from_pos (tree offset, tree bitpos)
549 {
550 return size_binop (PLUS_EXPR, bitpos,
551 size_binop (MULT_EXPR,
552 fold_convert (bitsizetype, offset),
553 bitsize_unit_node));
554 }
555
556 tree
557 byte_from_pos (tree offset, tree bitpos)
558 {
559 return size_binop (PLUS_EXPR, offset,
560 fold_convert (sizetype,
561 size_binop (TRUNC_DIV_EXPR, bitpos,
562 bitsize_unit_node)));
563 }
564
565 void
566 pos_from_bit (tree *poffset, tree *pbitpos, unsigned int off_align,
567 tree pos)
568 {
569 *poffset = size_binop (MULT_EXPR,
570 fold_convert (sizetype,
571 size_binop (FLOOR_DIV_EXPR, pos,
572 bitsize_int (off_align))),
573 size_int (off_align / BITS_PER_UNIT));
574 *pbitpos = size_binop (FLOOR_MOD_EXPR, pos, bitsize_int (off_align));
575 }
576
577 /* Given a pointer to bit and byte offsets and an offset alignment,
578 normalize the offsets so they are within the alignment. */
579
580 void
581 normalize_offset (tree *poffset, tree *pbitpos, unsigned int off_align)
582 {
583 /* If the bit position is now larger than it should be, adjust it
584 downwards. */
585 if (compare_tree_int (*pbitpos, off_align) >= 0)
586 {
587 tree extra_aligns = size_binop (FLOOR_DIV_EXPR, *pbitpos,
588 bitsize_int (off_align));
589
590 *poffset
591 = size_binop (PLUS_EXPR, *poffset,
592 size_binop (MULT_EXPR,
593 fold_convert (sizetype, extra_aligns),
594 size_int (off_align / BITS_PER_UNIT)));
595
596 *pbitpos
597 = size_binop (FLOOR_MOD_EXPR, *pbitpos, bitsize_int (off_align));
598 }
599 }
600
601 /* Print debugging information about the information in RLI. */
602
603 void
604 debug_rli (record_layout_info rli)
605 {
606 print_node_brief (stderr, "type", rli->t, 0);
607 print_node_brief (stderr, "\noffset", rli->offset, 0);
608 print_node_brief (stderr, " bitpos", rli->bitpos, 0);
609
610 fprintf (stderr, "\naligns: rec = %u, unpack = %u, off = %u\n",
611 rli->record_align, rli->unpacked_align,
612 rli->offset_align);
613
614 /* The ms_struct code is the only that uses this. */
615 if (targetm.ms_bitfield_layout_p (rli->t))
616 fprintf (stderr, "remaining in alignment = %u\n", rli->remaining_in_alignment);
617
618 if (rli->packed_maybe_necessary)
619 fprintf (stderr, "packed may be necessary\n");
620
621 if (rli->pending_statics)
622 {
623 fprintf (stderr, "pending statics:\n");
624 debug_tree (rli->pending_statics);
625 }
626 }
627
628 /* Given an RLI with a possibly-incremented BITPOS, adjust OFFSET and
629 BITPOS if necessary to keep BITPOS below OFFSET_ALIGN. */
630
631 void
632 normalize_rli (record_layout_info rli)
633 {
634 normalize_offset (&rli->offset, &rli->bitpos, rli->offset_align);
635 }
636
637 /* Returns the size in bytes allocated so far. */
638
639 tree
640 rli_size_unit_so_far (record_layout_info rli)
641 {
642 return byte_from_pos (rli->offset, rli->bitpos);
643 }
644
645 /* Returns the size in bits allocated so far. */
646
647 tree
648 rli_size_so_far (record_layout_info rli)
649 {
650 return bit_from_pos (rli->offset, rli->bitpos);
651 }
652
653 /* FIELD is about to be added to RLI->T. The alignment (in bits) of
654 the next available location within the record is given by KNOWN_ALIGN.
655 Update the variable alignment fields in RLI, and return the alignment
656 to give the FIELD. */
657
658 unsigned int
659 update_alignment_for_field (record_layout_info rli, tree field,
660 unsigned int known_align)
661 {
662 /* The alignment required for FIELD. */
663 unsigned int desired_align;
664 /* The type of this field. */
665 tree type = TREE_TYPE (field);
666 /* True if the field was explicitly aligned by the user. */
667 bool user_align;
668 bool is_bitfield;
669
670 /* Do not attempt to align an ERROR_MARK node */
671 if (TREE_CODE (type) == ERROR_MARK)
672 return 0;
673
674 /* Lay out the field so we know what alignment it needs. */
675 layout_decl (field, known_align);
676 desired_align = DECL_ALIGN (field);
677 user_align = DECL_USER_ALIGN (field);
678
679 is_bitfield = (type != error_mark_node
680 && DECL_BIT_FIELD_TYPE (field)
681 && ! integer_zerop (TYPE_SIZE (type)));
682
683 /* Record must have at least as much alignment as any field.
684 Otherwise, the alignment of the field within the record is
685 meaningless. */
686 if (targetm.ms_bitfield_layout_p (rli->t))
687 {
688 /* Here, the alignment of the underlying type of a bitfield can
689 affect the alignment of a record; even a zero-sized field
690 can do this. The alignment should be to the alignment of
691 the type, except that for zero-size bitfields this only
692 applies if there was an immediately prior, nonzero-size
693 bitfield. (That's the way it is, experimentally.) */
694 if ((!is_bitfield && !DECL_PACKED (field))
695 || (!integer_zerop (DECL_SIZE (field))
696 ? !DECL_PACKED (field)
697 : (rli->prev_field
698 && DECL_BIT_FIELD_TYPE (rli->prev_field)
699 && ! integer_zerop (DECL_SIZE (rli->prev_field)))))
700 {
701 unsigned int type_align = TYPE_ALIGN (type);
702 type_align = MAX (type_align, desired_align);
703 if (maximum_field_alignment != 0)
704 type_align = MIN (type_align, maximum_field_alignment);
705 rli->record_align = MAX (rli->record_align, type_align);
706 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
707 }
708 }
709 #ifdef PCC_BITFIELD_TYPE_MATTERS
710 else if (is_bitfield && PCC_BITFIELD_TYPE_MATTERS)
711 {
712 /* Named bit-fields cause the entire structure to have the
713 alignment implied by their type. Some targets also apply the same
714 rules to unnamed bitfields. */
715 if (DECL_NAME (field) != 0
716 || targetm.align_anon_bitfield ())
717 {
718 unsigned int type_align = TYPE_ALIGN (type);
719
720 #ifdef ADJUST_FIELD_ALIGN
721 if (! TYPE_USER_ALIGN (type))
722 type_align = ADJUST_FIELD_ALIGN (field, type_align);
723 #endif
724
725 /* Targets might chose to handle unnamed and hence possibly
726 zero-width bitfield. Those are not influenced by #pragmas
727 or packed attributes. */
728 if (integer_zerop (DECL_SIZE (field)))
729 {
730 if (initial_max_fld_align)
731 type_align = MIN (type_align,
732 initial_max_fld_align * BITS_PER_UNIT);
733 }
734 else if (maximum_field_alignment != 0)
735 type_align = MIN (type_align, maximum_field_alignment);
736 else if (DECL_PACKED (field))
737 type_align = MIN (type_align, BITS_PER_UNIT);
738
739 /* The alignment of the record is increased to the maximum
740 of the current alignment, the alignment indicated on the
741 field (i.e., the alignment specified by an __aligned__
742 attribute), and the alignment indicated by the type of
743 the field. */
744 rli->record_align = MAX (rli->record_align, desired_align);
745 rli->record_align = MAX (rli->record_align, type_align);
746
747 if (warn_packed)
748 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
749 user_align |= TYPE_USER_ALIGN (type);
750 }
751 }
752 #endif
753 else
754 {
755 rli->record_align = MAX (rli->record_align, desired_align);
756 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
757 }
758
759 TYPE_USER_ALIGN (rli->t) |= user_align;
760
761 return desired_align;
762 }
763
764 /* Called from place_field to handle unions. */
765
766 static void
767 place_union_field (record_layout_info rli, tree field)
768 {
769 update_alignment_for_field (rli, field, /*known_align=*/0);
770
771 DECL_FIELD_OFFSET (field) = size_zero_node;
772 DECL_FIELD_BIT_OFFSET (field) = bitsize_zero_node;
773 SET_DECL_OFFSET_ALIGN (field, BIGGEST_ALIGNMENT);
774
775 /* If this is an ERROR_MARK return *after* having set the
776 field at the start of the union. This helps when parsing
777 invalid fields. */
778 if (TREE_CODE (TREE_TYPE (field)) == ERROR_MARK)
779 return;
780
781 /* We assume the union's size will be a multiple of a byte so we don't
782 bother with BITPOS. */
783 if (TREE_CODE (rli->t) == UNION_TYPE)
784 rli->offset = size_binop (MAX_EXPR, rli->offset, DECL_SIZE_UNIT (field));
785 else if (TREE_CODE (rli->t) == QUAL_UNION_TYPE)
786 rli->offset = fold_build3 (COND_EXPR, sizetype,
787 DECL_QUALIFIER (field),
788 DECL_SIZE_UNIT (field), rli->offset);
789 }
790
791 #if defined (PCC_BITFIELD_TYPE_MATTERS) || defined (BITFIELD_NBYTES_LIMITED)
792 /* A bitfield of SIZE with a required access alignment of ALIGN is allocated
793 at BYTE_OFFSET / BIT_OFFSET. Return nonzero if the field would span more
794 units of alignment than the underlying TYPE. */
795 static int
796 excess_unit_span (HOST_WIDE_INT byte_offset, HOST_WIDE_INT bit_offset,
797 HOST_WIDE_INT size, HOST_WIDE_INT align, tree type)
798 {
799 /* Note that the calculation of OFFSET might overflow; we calculate it so
800 that we still get the right result as long as ALIGN is a power of two. */
801 unsigned HOST_WIDE_INT offset = byte_offset * BITS_PER_UNIT + bit_offset;
802
803 offset = offset % align;
804 return ((offset + size + align - 1) / align
805 > ((unsigned HOST_WIDE_INT) tree_low_cst (TYPE_SIZE (type), 1)
806 / align));
807 }
808 #endif
809
810 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
811 is a FIELD_DECL to be added after those fields already present in
812 T. (FIELD is not actually added to the TYPE_FIELDS list here;
813 callers that desire that behavior must manually perform that step.) */
814
815 void
816 place_field (record_layout_info rli, tree field)
817 {
818 /* The alignment required for FIELD. */
819 unsigned int desired_align;
820 /* The alignment FIELD would have if we just dropped it into the
821 record as it presently stands. */
822 unsigned int known_align;
823 unsigned int actual_align;
824 /* The type of this field. */
825 tree type = TREE_TYPE (field);
826
827 gcc_assert (TREE_CODE (field) != ERROR_MARK);
828
829 /* If FIELD is static, then treat it like a separate variable, not
830 really like a structure field. If it is a FUNCTION_DECL, it's a
831 method. In both cases, all we do is lay out the decl, and we do
832 it *after* the record is laid out. */
833 if (TREE_CODE (field) == VAR_DECL)
834 {
835 rli->pending_statics = tree_cons (NULL_TREE, field,
836 rli->pending_statics);
837 return;
838 }
839
840 /* Enumerators and enum types which are local to this class need not
841 be laid out. Likewise for initialized constant fields. */
842 else if (TREE_CODE (field) != FIELD_DECL)
843 return;
844
845 /* Unions are laid out very differently than records, so split
846 that code off to another function. */
847 else if (TREE_CODE (rli->t) != RECORD_TYPE)
848 {
849 place_union_field (rli, field);
850 return;
851 }
852
853 else if (TREE_CODE (type) == ERROR_MARK)
854 {
855 /* Place this field at the current allocation position, so we
856 maintain monotonicity. */
857 DECL_FIELD_OFFSET (field) = rli->offset;
858 DECL_FIELD_BIT_OFFSET (field) = rli->bitpos;
859 SET_DECL_OFFSET_ALIGN (field, rli->offset_align);
860 return;
861 }
862
863 /* Work out the known alignment so far. Note that A & (-A) is the
864 value of the least-significant bit in A that is one. */
865 if (! integer_zerop (rli->bitpos))
866 known_align = (tree_low_cst (rli->bitpos, 1)
867 & - tree_low_cst (rli->bitpos, 1));
868 else if (integer_zerop (rli->offset))
869 known_align = 0;
870 else if (host_integerp (rli->offset, 1))
871 known_align = (BITS_PER_UNIT
872 * (tree_low_cst (rli->offset, 1)
873 & - tree_low_cst (rli->offset, 1)));
874 else
875 known_align = rli->offset_align;
876
877 desired_align = update_alignment_for_field (rli, field, known_align);
878 if (known_align == 0)
879 known_align = MAX (BIGGEST_ALIGNMENT, rli->record_align);
880
881 if (warn_packed && DECL_PACKED (field))
882 {
883 if (known_align >= TYPE_ALIGN (type))
884 {
885 if (TYPE_ALIGN (type) > desired_align)
886 {
887 if (STRICT_ALIGNMENT)
888 warning (OPT_Wattributes, "packed attribute causes "
889 "inefficient alignment for %q+D", field);
890 else
891 warning (OPT_Wattributes, "packed attribute is "
892 "unnecessary for %q+D", field);
893 }
894 }
895 else
896 rli->packed_maybe_necessary = 1;
897 }
898
899 /* Does this field automatically have alignment it needs by virtue
900 of the fields that precede it and the record's own alignment?
901 We already align ms_struct fields, so don't re-align them. */
902 if (known_align < desired_align
903 && !targetm.ms_bitfield_layout_p (rli->t))
904 {
905 /* No, we need to skip space before this field.
906 Bump the cumulative size to multiple of field alignment. */
907
908 warning (OPT_Wpadded, "padding struct to align %q+D", field);
909
910 /* If the alignment is still within offset_align, just align
911 the bit position. */
912 if (desired_align < rli->offset_align)
913 rli->bitpos = round_up (rli->bitpos, desired_align);
914 else
915 {
916 /* First adjust OFFSET by the partial bits, then align. */
917 rli->offset
918 = size_binop (PLUS_EXPR, rli->offset,
919 fold_convert (sizetype,
920 size_binop (CEIL_DIV_EXPR, rli->bitpos,
921 bitsize_unit_node)));
922 rli->bitpos = bitsize_zero_node;
923
924 rli->offset = round_up (rli->offset, desired_align / BITS_PER_UNIT);
925 }
926
927 if (! TREE_CONSTANT (rli->offset))
928 rli->offset_align = desired_align;
929
930 }
931
932 /* Handle compatibility with PCC. Note that if the record has any
933 variable-sized fields, we need not worry about compatibility. */
934 #ifdef PCC_BITFIELD_TYPE_MATTERS
935 if (PCC_BITFIELD_TYPE_MATTERS
936 && ! targetm.ms_bitfield_layout_p (rli->t)
937 && TREE_CODE (field) == FIELD_DECL
938 && type != error_mark_node
939 && DECL_BIT_FIELD (field)
940 && (! DECL_PACKED (field)
941 /* Enter for these packed fields only to issue a warning. */
942 || TYPE_ALIGN (type) <= BITS_PER_UNIT)
943 && maximum_field_alignment == 0
944 && ! integer_zerop (DECL_SIZE (field))
945 && host_integerp (DECL_SIZE (field), 1)
946 && host_integerp (rli->offset, 1)
947 && host_integerp (TYPE_SIZE (type), 1))
948 {
949 unsigned int type_align = TYPE_ALIGN (type);
950 tree dsize = DECL_SIZE (field);
951 HOST_WIDE_INT field_size = tree_low_cst (dsize, 1);
952 HOST_WIDE_INT offset = tree_low_cst (rli->offset, 0);
953 HOST_WIDE_INT bit_offset = tree_low_cst (rli->bitpos, 0);
954
955 #ifdef ADJUST_FIELD_ALIGN
956 if (! TYPE_USER_ALIGN (type))
957 type_align = ADJUST_FIELD_ALIGN (field, type_align);
958 #endif
959
960 /* A bit field may not span more units of alignment of its type
961 than its type itself. Advance to next boundary if necessary. */
962 if (excess_unit_span (offset, bit_offset, field_size, type_align, type))
963 {
964 if (DECL_PACKED (field))
965 {
966 if (warn_packed_bitfield_compat == 1)
967 inform
968 (input_location,
969 "Offset of packed bit-field %qD has changed in GCC 4.4",
970 field);
971 }
972 else
973 rli->bitpos = round_up (rli->bitpos, type_align);
974 }
975
976 if (! DECL_PACKED (field))
977 TYPE_USER_ALIGN (rli->t) |= TYPE_USER_ALIGN (type);
978 }
979 #endif
980
981 #ifdef BITFIELD_NBYTES_LIMITED
982 if (BITFIELD_NBYTES_LIMITED
983 && ! targetm.ms_bitfield_layout_p (rli->t)
984 && TREE_CODE (field) == FIELD_DECL
985 && type != error_mark_node
986 && DECL_BIT_FIELD_TYPE (field)
987 && ! DECL_PACKED (field)
988 && ! integer_zerop (DECL_SIZE (field))
989 && host_integerp (DECL_SIZE (field), 1)
990 && host_integerp (rli->offset, 1)
991 && host_integerp (TYPE_SIZE (type), 1))
992 {
993 unsigned int type_align = TYPE_ALIGN (type);
994 tree dsize = DECL_SIZE (field);
995 HOST_WIDE_INT field_size = tree_low_cst (dsize, 1);
996 HOST_WIDE_INT offset = tree_low_cst (rli->offset, 0);
997 HOST_WIDE_INT bit_offset = tree_low_cst (rli->bitpos, 0);
998
999 #ifdef ADJUST_FIELD_ALIGN
1000 if (! TYPE_USER_ALIGN (type))
1001 type_align = ADJUST_FIELD_ALIGN (field, type_align);
1002 #endif
1003
1004 if (maximum_field_alignment != 0)
1005 type_align = MIN (type_align, maximum_field_alignment);
1006 /* ??? This test is opposite the test in the containing if
1007 statement, so this code is unreachable currently. */
1008 else if (DECL_PACKED (field))
1009 type_align = MIN (type_align, BITS_PER_UNIT);
1010
1011 /* A bit field may not span the unit of alignment of its type.
1012 Advance to next boundary if necessary. */
1013 if (excess_unit_span (offset, bit_offset, field_size, type_align, type))
1014 rli->bitpos = round_up (rli->bitpos, type_align);
1015
1016 TYPE_USER_ALIGN (rli->t) |= TYPE_USER_ALIGN (type);
1017 }
1018 #endif
1019
1020 /* See the docs for TARGET_MS_BITFIELD_LAYOUT_P for details.
1021 A subtlety:
1022 When a bit field is inserted into a packed record, the whole
1023 size of the underlying type is used by one or more same-size
1024 adjacent bitfields. (That is, if its long:3, 32 bits is
1025 used in the record, and any additional adjacent long bitfields are
1026 packed into the same chunk of 32 bits. However, if the size
1027 changes, a new field of that size is allocated.) In an unpacked
1028 record, this is the same as using alignment, but not equivalent
1029 when packing.
1030
1031 Note: for compatibility, we use the type size, not the type alignment
1032 to determine alignment, since that matches the documentation */
1033
1034 if (targetm.ms_bitfield_layout_p (rli->t))
1035 {
1036 tree prev_saved = rli->prev_field;
1037 tree prev_type = prev_saved ? DECL_BIT_FIELD_TYPE (prev_saved) : NULL;
1038
1039 /* This is a bitfield if it exists. */
1040 if (rli->prev_field)
1041 {
1042 /* If both are bitfields, nonzero, and the same size, this is
1043 the middle of a run. Zero declared size fields are special
1044 and handled as "end of run". (Note: it's nonzero declared
1045 size, but equal type sizes!) (Since we know that both
1046 the current and previous fields are bitfields by the
1047 time we check it, DECL_SIZE must be present for both.) */
1048 if (DECL_BIT_FIELD_TYPE (field)
1049 && !integer_zerop (DECL_SIZE (field))
1050 && !integer_zerop (DECL_SIZE (rli->prev_field))
1051 && host_integerp (DECL_SIZE (rli->prev_field), 0)
1052 && host_integerp (TYPE_SIZE (type), 0)
1053 && simple_cst_equal (TYPE_SIZE (type), TYPE_SIZE (prev_type)))
1054 {
1055 /* We're in the middle of a run of equal type size fields; make
1056 sure we realign if we run out of bits. (Not decl size,
1057 type size!) */
1058 HOST_WIDE_INT bitsize = tree_low_cst (DECL_SIZE (field), 1);
1059
1060 if (rli->remaining_in_alignment < bitsize)
1061 {
1062 HOST_WIDE_INT typesize = tree_low_cst (TYPE_SIZE (type), 1);
1063
1064 /* out of bits; bump up to next 'word'. */
1065 rli->bitpos
1066 = size_binop (PLUS_EXPR, rli->bitpos,
1067 bitsize_int (rli->remaining_in_alignment));
1068 rli->prev_field = field;
1069 if (typesize < bitsize)
1070 rli->remaining_in_alignment = 0;
1071 else
1072 rli->remaining_in_alignment = typesize - bitsize;
1073 }
1074 else
1075 rli->remaining_in_alignment -= bitsize;
1076 }
1077 else
1078 {
1079 /* End of a run: if leaving a run of bitfields of the same type
1080 size, we have to "use up" the rest of the bits of the type
1081 size.
1082
1083 Compute the new position as the sum of the size for the prior
1084 type and where we first started working on that type.
1085 Note: since the beginning of the field was aligned then
1086 of course the end will be too. No round needed. */
1087
1088 if (!integer_zerop (DECL_SIZE (rli->prev_field)))
1089 {
1090 rli->bitpos
1091 = size_binop (PLUS_EXPR, rli->bitpos,
1092 bitsize_int (rli->remaining_in_alignment));
1093 }
1094 else
1095 /* We "use up" size zero fields; the code below should behave
1096 as if the prior field was not a bitfield. */
1097 prev_saved = NULL;
1098
1099 /* Cause a new bitfield to be captured, either this time (if
1100 currently a bitfield) or next time we see one. */
1101 if (!DECL_BIT_FIELD_TYPE(field)
1102 || integer_zerop (DECL_SIZE (field)))
1103 rli->prev_field = NULL;
1104 }
1105
1106 normalize_rli (rli);
1107 }
1108
1109 /* If we're starting a new run of same size type bitfields
1110 (or a run of non-bitfields), set up the "first of the run"
1111 fields.
1112
1113 That is, if the current field is not a bitfield, or if there
1114 was a prior bitfield the type sizes differ, or if there wasn't
1115 a prior bitfield the size of the current field is nonzero.
1116
1117 Note: we must be sure to test ONLY the type size if there was
1118 a prior bitfield and ONLY for the current field being zero if
1119 there wasn't. */
1120
1121 if (!DECL_BIT_FIELD_TYPE (field)
1122 || (prev_saved != NULL
1123 ? !simple_cst_equal (TYPE_SIZE (type), TYPE_SIZE (prev_type))
1124 : !integer_zerop (DECL_SIZE (field)) ))
1125 {
1126 /* Never smaller than a byte for compatibility. */
1127 unsigned int type_align = BITS_PER_UNIT;
1128
1129 /* (When not a bitfield), we could be seeing a flex array (with
1130 no DECL_SIZE). Since we won't be using remaining_in_alignment
1131 until we see a bitfield (and come by here again) we just skip
1132 calculating it. */
1133 if (DECL_SIZE (field) != NULL
1134 && host_integerp (TYPE_SIZE (TREE_TYPE (field)), 0)
1135 && host_integerp (DECL_SIZE (field), 0))
1136 {
1137 HOST_WIDE_INT bitsize = tree_low_cst (DECL_SIZE (field), 1);
1138 HOST_WIDE_INT typesize
1139 = tree_low_cst (TYPE_SIZE (TREE_TYPE (field)), 1);
1140
1141 if (typesize < bitsize)
1142 rli->remaining_in_alignment = 0;
1143 else
1144 rli->remaining_in_alignment = typesize - bitsize;
1145 }
1146
1147 /* Now align (conventionally) for the new type. */
1148 type_align = TYPE_ALIGN (TREE_TYPE (field));
1149
1150 if (maximum_field_alignment != 0)
1151 type_align = MIN (type_align, maximum_field_alignment);
1152
1153 rli->bitpos = round_up (rli->bitpos, type_align);
1154
1155 /* If we really aligned, don't allow subsequent bitfields
1156 to undo that. */
1157 rli->prev_field = NULL;
1158 }
1159 }
1160
1161 /* Offset so far becomes the position of this field after normalizing. */
1162 normalize_rli (rli);
1163 DECL_FIELD_OFFSET (field) = rli->offset;
1164 DECL_FIELD_BIT_OFFSET (field) = rli->bitpos;
1165 SET_DECL_OFFSET_ALIGN (field, rli->offset_align);
1166
1167 /* If this field ended up more aligned than we thought it would be (we
1168 approximate this by seeing if its position changed), lay out the field
1169 again; perhaps we can use an integral mode for it now. */
1170 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field)))
1171 actual_align = (tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1)
1172 & - tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1));
1173 else if (integer_zerop (DECL_FIELD_OFFSET (field)))
1174 actual_align = MAX (BIGGEST_ALIGNMENT, rli->record_align);
1175 else if (host_integerp (DECL_FIELD_OFFSET (field), 1))
1176 actual_align = (BITS_PER_UNIT
1177 * (tree_low_cst (DECL_FIELD_OFFSET (field), 1)
1178 & - tree_low_cst (DECL_FIELD_OFFSET (field), 1)));
1179 else
1180 actual_align = DECL_OFFSET_ALIGN (field);
1181 /* ACTUAL_ALIGN is still the actual alignment *within the record* .
1182 store / extract bit field operations will check the alignment of the
1183 record against the mode of bit fields. */
1184
1185 if (known_align != actual_align)
1186 layout_decl (field, actual_align);
1187
1188 if (rli->prev_field == NULL && DECL_BIT_FIELD_TYPE (field))
1189 rli->prev_field = field;
1190
1191 /* Now add size of this field to the size of the record. If the size is
1192 not constant, treat the field as being a multiple of bytes and just
1193 adjust the offset, resetting the bit position. Otherwise, apportion the
1194 size amongst the bit position and offset. First handle the case of an
1195 unspecified size, which can happen when we have an invalid nested struct
1196 definition, such as struct j { struct j { int i; } }. The error message
1197 is printed in finish_struct. */
1198 if (DECL_SIZE (field) == 0)
1199 /* Do nothing. */;
1200 else if (TREE_CODE (DECL_SIZE (field)) != INTEGER_CST
1201 || TREE_OVERFLOW (DECL_SIZE (field)))
1202 {
1203 rli->offset
1204 = size_binop (PLUS_EXPR, rli->offset,
1205 fold_convert (sizetype,
1206 size_binop (CEIL_DIV_EXPR, rli->bitpos,
1207 bitsize_unit_node)));
1208 rli->offset
1209 = size_binop (PLUS_EXPR, rli->offset, DECL_SIZE_UNIT (field));
1210 rli->bitpos = bitsize_zero_node;
1211 rli->offset_align = MIN (rli->offset_align, desired_align);
1212 }
1213 else if (targetm.ms_bitfield_layout_p (rli->t))
1214 {
1215 rli->bitpos = size_binop (PLUS_EXPR, rli->bitpos, DECL_SIZE (field));
1216
1217 /* If we ended a bitfield before the full length of the type then
1218 pad the struct out to the full length of the last type. */
1219 if ((TREE_CHAIN (field) == NULL
1220 || TREE_CODE (TREE_CHAIN (field)) != FIELD_DECL)
1221 && DECL_BIT_FIELD_TYPE (field)
1222 && !integer_zerop (DECL_SIZE (field)))
1223 rli->bitpos = size_binop (PLUS_EXPR, rli->bitpos,
1224 bitsize_int (rli->remaining_in_alignment));
1225
1226 normalize_rli (rli);
1227 }
1228 else
1229 {
1230 rli->bitpos = size_binop (PLUS_EXPR, rli->bitpos, DECL_SIZE (field));
1231 normalize_rli (rli);
1232 }
1233 }
1234
1235 /* Assuming that all the fields have been laid out, this function uses
1236 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
1237 indicated by RLI. */
1238
1239 static void
1240 finalize_record_size (record_layout_info rli)
1241 {
1242 tree unpadded_size, unpadded_size_unit;
1243
1244 /* Now we want just byte and bit offsets, so set the offset alignment
1245 to be a byte and then normalize. */
1246 rli->offset_align = BITS_PER_UNIT;
1247 normalize_rli (rli);
1248
1249 /* Determine the desired alignment. */
1250 #ifdef ROUND_TYPE_ALIGN
1251 TYPE_ALIGN (rli->t) = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t),
1252 rli->record_align);
1253 #else
1254 TYPE_ALIGN (rli->t) = MAX (TYPE_ALIGN (rli->t), rli->record_align);
1255 #endif
1256
1257 /* Compute the size so far. Be sure to allow for extra bits in the
1258 size in bytes. We have guaranteed above that it will be no more
1259 than a single byte. */
1260 unpadded_size = rli_size_so_far (rli);
1261 unpadded_size_unit = rli_size_unit_so_far (rli);
1262 if (! integer_zerop (rli->bitpos))
1263 unpadded_size_unit
1264 = size_binop (PLUS_EXPR, unpadded_size_unit, size_one_node);
1265
1266 /* Round the size up to be a multiple of the required alignment. */
1267 TYPE_SIZE (rli->t) = round_up (unpadded_size, TYPE_ALIGN (rli->t));
1268 TYPE_SIZE_UNIT (rli->t)
1269 = round_up (unpadded_size_unit, TYPE_ALIGN_UNIT (rli->t));
1270
1271 if (TREE_CONSTANT (unpadded_size)
1272 && simple_cst_equal (unpadded_size, TYPE_SIZE (rli->t)) == 0)
1273 warning (OPT_Wpadded, "padding struct size to alignment boundary");
1274
1275 if (warn_packed && TREE_CODE (rli->t) == RECORD_TYPE
1276 && TYPE_PACKED (rli->t) && ! rli->packed_maybe_necessary
1277 && TREE_CONSTANT (unpadded_size))
1278 {
1279 tree unpacked_size;
1280
1281 #ifdef ROUND_TYPE_ALIGN
1282 rli->unpacked_align
1283 = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t), rli->unpacked_align);
1284 #else
1285 rli->unpacked_align = MAX (TYPE_ALIGN (rli->t), rli->unpacked_align);
1286 #endif
1287
1288 unpacked_size = round_up (TYPE_SIZE (rli->t), rli->unpacked_align);
1289 if (simple_cst_equal (unpacked_size, TYPE_SIZE (rli->t)))
1290 {
1291 TYPE_PACKED (rli->t) = 0;
1292
1293 if (TYPE_NAME (rli->t))
1294 {
1295 const char *name;
1296
1297 if (TREE_CODE (TYPE_NAME (rli->t)) == IDENTIFIER_NODE)
1298 name = IDENTIFIER_POINTER (TYPE_NAME (rli->t));
1299 else
1300 name = IDENTIFIER_POINTER (DECL_NAME (TYPE_NAME (rli->t)));
1301
1302 if (STRICT_ALIGNMENT)
1303 warning (OPT_Wpacked, "packed attribute causes inefficient "
1304 "alignment for %qs", name);
1305 else
1306 warning (OPT_Wpacked,
1307 "packed attribute is unnecessary for %qs", name);
1308 }
1309 else
1310 {
1311 if (STRICT_ALIGNMENT)
1312 warning (OPT_Wpacked,
1313 "packed attribute causes inefficient alignment");
1314 else
1315 warning (OPT_Wpacked, "packed attribute is unnecessary");
1316 }
1317 }
1318 }
1319 }
1320
1321 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
1322
1323 void
1324 compute_record_mode (tree type)
1325 {
1326 tree field;
1327 enum machine_mode mode = VOIDmode;
1328
1329 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
1330 However, if possible, we use a mode that fits in a register
1331 instead, in order to allow for better optimization down the
1332 line. */
1333 SET_TYPE_MODE (type, BLKmode);
1334
1335 if (! host_integerp (TYPE_SIZE (type), 1))
1336 return;
1337
1338 /* A record which has any BLKmode members must itself be
1339 BLKmode; it can't go in a register. Unless the member is
1340 BLKmode only because it isn't aligned. */
1341 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1342 {
1343 if (TREE_CODE (field) != FIELD_DECL)
1344 continue;
1345
1346 if (TREE_CODE (TREE_TYPE (field)) == ERROR_MARK
1347 || (TYPE_MODE (TREE_TYPE (field)) == BLKmode
1348 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field))
1349 && !(TYPE_SIZE (TREE_TYPE (field)) != 0
1350 && integer_zerop (TYPE_SIZE (TREE_TYPE (field)))))
1351 || ! host_integerp (bit_position (field), 1)
1352 || DECL_SIZE (field) == 0
1353 || ! host_integerp (DECL_SIZE (field), 1))
1354 return;
1355
1356 /* If this field is the whole struct, remember its mode so
1357 that, say, we can put a double in a class into a DF
1358 register instead of forcing it to live in the stack. */
1359 if (simple_cst_equal (TYPE_SIZE (type), DECL_SIZE (field)))
1360 mode = DECL_MODE (field);
1361
1362 #ifdef MEMBER_TYPE_FORCES_BLK
1363 /* With some targets, eg. c4x, it is sub-optimal
1364 to access an aligned BLKmode structure as a scalar. */
1365
1366 if (MEMBER_TYPE_FORCES_BLK (field, mode))
1367 return;
1368 #endif /* MEMBER_TYPE_FORCES_BLK */
1369 }
1370
1371 /* If we only have one real field; use its mode if that mode's size
1372 matches the type's size. This only applies to RECORD_TYPE. This
1373 does not apply to unions. */
1374 if (TREE_CODE (type) == RECORD_TYPE && mode != VOIDmode
1375 && host_integerp (TYPE_SIZE (type), 1)
1376 && GET_MODE_BITSIZE (mode) == TREE_INT_CST_LOW (TYPE_SIZE (type)))
1377 SET_TYPE_MODE (type, mode);
1378 else
1379 SET_TYPE_MODE (type, mode_for_size_tree (TYPE_SIZE (type), MODE_INT, 1));
1380
1381 /* If structure's known alignment is less than what the scalar
1382 mode would need, and it matters, then stick with BLKmode. */
1383 if (TYPE_MODE (type) != BLKmode
1384 && STRICT_ALIGNMENT
1385 && ! (TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT
1386 || TYPE_ALIGN (type) >= GET_MODE_ALIGNMENT (TYPE_MODE (type))))
1387 {
1388 /* If this is the only reason this type is BLKmode, then
1389 don't force containing types to be BLKmode. */
1390 TYPE_NO_FORCE_BLK (type) = 1;
1391 SET_TYPE_MODE (type, BLKmode);
1392 }
1393 }
1394
1395 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1396 out. */
1397
1398 static void
1399 finalize_type_size (tree type)
1400 {
1401 /* Normally, use the alignment corresponding to the mode chosen.
1402 However, where strict alignment is not required, avoid
1403 over-aligning structures, since most compilers do not do this
1404 alignment. */
1405
1406 if (TYPE_MODE (type) != BLKmode && TYPE_MODE (type) != VOIDmode
1407 && (STRICT_ALIGNMENT
1408 || (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE
1409 && TREE_CODE (type) != QUAL_UNION_TYPE
1410 && TREE_CODE (type) != ARRAY_TYPE)))
1411 {
1412 unsigned mode_align = GET_MODE_ALIGNMENT (TYPE_MODE (type));
1413
1414 /* Don't override a larger alignment requirement coming from a user
1415 alignment of one of the fields. */
1416 if (mode_align >= TYPE_ALIGN (type))
1417 {
1418 TYPE_ALIGN (type) = mode_align;
1419 TYPE_USER_ALIGN (type) = 0;
1420 }
1421 }
1422
1423 /* Do machine-dependent extra alignment. */
1424 #ifdef ROUND_TYPE_ALIGN
1425 TYPE_ALIGN (type)
1426 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (type), BITS_PER_UNIT);
1427 #endif
1428
1429 /* If we failed to find a simple way to calculate the unit size
1430 of the type, find it by division. */
1431 if (TYPE_SIZE_UNIT (type) == 0 && TYPE_SIZE (type) != 0)
1432 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1433 result will fit in sizetype. We will get more efficient code using
1434 sizetype, so we force a conversion. */
1435 TYPE_SIZE_UNIT (type)
1436 = fold_convert (sizetype,
1437 size_binop (FLOOR_DIV_EXPR, TYPE_SIZE (type),
1438 bitsize_unit_node));
1439
1440 if (TYPE_SIZE (type) != 0)
1441 {
1442 TYPE_SIZE (type) = round_up (TYPE_SIZE (type), TYPE_ALIGN (type));
1443 TYPE_SIZE_UNIT (type) = round_up (TYPE_SIZE_UNIT (type),
1444 TYPE_ALIGN_UNIT (type));
1445 }
1446
1447 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1448 if (TYPE_SIZE (type) != 0 && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
1449 TYPE_SIZE (type) = variable_size (TYPE_SIZE (type));
1450 if (TYPE_SIZE_UNIT (type) != 0
1451 && TREE_CODE (TYPE_SIZE_UNIT (type)) != INTEGER_CST)
1452 TYPE_SIZE_UNIT (type) = variable_size (TYPE_SIZE_UNIT (type));
1453
1454 /* Also layout any other variants of the type. */
1455 if (TYPE_NEXT_VARIANT (type)
1456 || type != TYPE_MAIN_VARIANT (type))
1457 {
1458 tree variant;
1459 /* Record layout info of this variant. */
1460 tree size = TYPE_SIZE (type);
1461 tree size_unit = TYPE_SIZE_UNIT (type);
1462 unsigned int align = TYPE_ALIGN (type);
1463 unsigned int user_align = TYPE_USER_ALIGN (type);
1464 enum machine_mode mode = TYPE_MODE (type);
1465
1466 /* Copy it into all variants. */
1467 for (variant = TYPE_MAIN_VARIANT (type);
1468 variant != 0;
1469 variant = TYPE_NEXT_VARIANT (variant))
1470 {
1471 TYPE_SIZE (variant) = size;
1472 TYPE_SIZE_UNIT (variant) = size_unit;
1473 TYPE_ALIGN (variant) = align;
1474 TYPE_USER_ALIGN (variant) = user_align;
1475 SET_TYPE_MODE (variant, mode);
1476 }
1477 }
1478 }
1479
1480 /* Do all of the work required to layout the type indicated by RLI,
1481 once the fields have been laid out. This function will call `free'
1482 for RLI, unless FREE_P is false. Passing a value other than false
1483 for FREE_P is bad practice; this option only exists to support the
1484 G++ 3.2 ABI. */
1485
1486 void
1487 finish_record_layout (record_layout_info rli, int free_p)
1488 {
1489 tree variant;
1490
1491 /* Compute the final size. */
1492 finalize_record_size (rli);
1493
1494 /* Compute the TYPE_MODE for the record. */
1495 compute_record_mode (rli->t);
1496
1497 /* Perform any last tweaks to the TYPE_SIZE, etc. */
1498 finalize_type_size (rli->t);
1499
1500 /* Propagate TYPE_PACKED to variants. With C++ templates,
1501 handle_packed_attribute is too early to do this. */
1502 for (variant = TYPE_NEXT_VARIANT (rli->t); variant;
1503 variant = TYPE_NEXT_VARIANT (variant))
1504 TYPE_PACKED (variant) = TYPE_PACKED (rli->t);
1505
1506 /* Lay out any static members. This is done now because their type
1507 may use the record's type. */
1508 while (rli->pending_statics)
1509 {
1510 layout_decl (TREE_VALUE (rli->pending_statics), 0);
1511 rli->pending_statics = TREE_CHAIN (rli->pending_statics);
1512 }
1513
1514 /* Clean up. */
1515 if (free_p)
1516 free (rli);
1517 }
1518
1519
1520 /* Finish processing a builtin RECORD_TYPE type TYPE. It's name is
1521 NAME, its fields are chained in reverse on FIELDS.
1522
1523 If ALIGN_TYPE is non-null, it is given the same alignment as
1524 ALIGN_TYPE. */
1525
1526 void
1527 finish_builtin_struct (tree type, const char *name, tree fields,
1528 tree align_type)
1529 {
1530 tree tail, next;
1531
1532 for (tail = NULL_TREE; fields; tail = fields, fields = next)
1533 {
1534 DECL_FIELD_CONTEXT (fields) = type;
1535 next = TREE_CHAIN (fields);
1536 TREE_CHAIN (fields) = tail;
1537 }
1538 TYPE_FIELDS (type) = tail;
1539
1540 if (align_type)
1541 {
1542 TYPE_ALIGN (type) = TYPE_ALIGN (align_type);
1543 TYPE_USER_ALIGN (type) = TYPE_USER_ALIGN (align_type);
1544 }
1545
1546 layout_type (type);
1547 #if 0 /* not yet, should get fixed properly later */
1548 TYPE_NAME (type) = make_type_decl (get_identifier (name), type);
1549 #else
1550 TYPE_NAME (type) = build_decl (TYPE_DECL, get_identifier (name), type);
1551 #endif
1552 TYPE_STUB_DECL (type) = TYPE_NAME (type);
1553 layout_decl (TYPE_NAME (type), 0);
1554 }
1555
1556 /* Calculate the mode, size, and alignment for TYPE.
1557 For an array type, calculate the element separation as well.
1558 Record TYPE on the chain of permanent or temporary types
1559 so that dbxout will find out about it.
1560
1561 TYPE_SIZE of a type is nonzero if the type has been laid out already.
1562 layout_type does nothing on such a type.
1563
1564 If the type is incomplete, its TYPE_SIZE remains zero. */
1565
1566 void
1567 layout_type (tree type)
1568 {
1569 gcc_assert (type);
1570
1571 if (type == error_mark_node)
1572 return;
1573
1574 /* Do nothing if type has been laid out before. */
1575 if (TYPE_SIZE (type))
1576 return;
1577
1578 switch (TREE_CODE (type))
1579 {
1580 case LANG_TYPE:
1581 /* This kind of type is the responsibility
1582 of the language-specific code. */
1583 gcc_unreachable ();
1584
1585 case BOOLEAN_TYPE: /* Used for Java, Pascal, and Chill. */
1586 if (TYPE_PRECISION (type) == 0)
1587 TYPE_PRECISION (type) = 1; /* default to one byte/boolean. */
1588
1589 /* ... fall through ... */
1590
1591 case INTEGER_TYPE:
1592 case ENUMERAL_TYPE:
1593 if (TREE_CODE (TYPE_MIN_VALUE (type)) == INTEGER_CST
1594 && tree_int_cst_sgn (TYPE_MIN_VALUE (type)) >= 0)
1595 TYPE_UNSIGNED (type) = 1;
1596
1597 SET_TYPE_MODE (type,
1598 smallest_mode_for_size (TYPE_PRECISION (type), MODE_INT));
1599 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1600 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1601 break;
1602
1603 case REAL_TYPE:
1604 SET_TYPE_MODE (type,
1605 mode_for_size (TYPE_PRECISION (type), MODE_FLOAT, 0));
1606 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1607 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1608 break;
1609
1610 case FIXED_POINT_TYPE:
1611 /* TYPE_MODE (type) has been set already. */
1612 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1613 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1614 break;
1615
1616 case COMPLEX_TYPE:
1617 TYPE_UNSIGNED (type) = TYPE_UNSIGNED (TREE_TYPE (type));
1618 SET_TYPE_MODE (type,
1619 mode_for_size (2 * TYPE_PRECISION (TREE_TYPE (type)),
1620 (TREE_CODE (TREE_TYPE (type)) == REAL_TYPE
1621 ? MODE_COMPLEX_FLOAT : MODE_COMPLEX_INT),
1622 0));
1623 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1624 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1625 break;
1626
1627 case VECTOR_TYPE:
1628 {
1629 int nunits = TYPE_VECTOR_SUBPARTS (type);
1630 tree innertype = TREE_TYPE (type);
1631
1632 gcc_assert (!(nunits & (nunits - 1)));
1633
1634 /* Find an appropriate mode for the vector type. */
1635 if (TYPE_MODE (type) == VOIDmode)
1636 {
1637 enum machine_mode innermode = TYPE_MODE (innertype);
1638 enum machine_mode mode;
1639
1640 /* First, look for a supported vector type. */
1641 if (SCALAR_FLOAT_MODE_P (innermode))
1642 mode = MIN_MODE_VECTOR_FLOAT;
1643 else if (SCALAR_FRACT_MODE_P (innermode))
1644 mode = MIN_MODE_VECTOR_FRACT;
1645 else if (SCALAR_UFRACT_MODE_P (innermode))
1646 mode = MIN_MODE_VECTOR_UFRACT;
1647 else if (SCALAR_ACCUM_MODE_P (innermode))
1648 mode = MIN_MODE_VECTOR_ACCUM;
1649 else if (SCALAR_UACCUM_MODE_P (innermode))
1650 mode = MIN_MODE_VECTOR_UACCUM;
1651 else
1652 mode = MIN_MODE_VECTOR_INT;
1653
1654 /* Do not check vector_mode_supported_p here. We'll do that
1655 later in vector_type_mode. */
1656 for (; mode != VOIDmode ; mode = GET_MODE_WIDER_MODE (mode))
1657 if (GET_MODE_NUNITS (mode) == nunits
1658 && GET_MODE_INNER (mode) == innermode)
1659 break;
1660
1661 /* For integers, try mapping it to a same-sized scalar mode. */
1662 if (mode == VOIDmode
1663 && GET_MODE_CLASS (innermode) == MODE_INT)
1664 mode = mode_for_size (nunits * GET_MODE_BITSIZE (innermode),
1665 MODE_INT, 0);
1666
1667 if (mode == VOIDmode ||
1668 (GET_MODE_CLASS (mode) == MODE_INT
1669 && !have_regs_of_mode[mode]))
1670 SET_TYPE_MODE (type, BLKmode);
1671 else
1672 SET_TYPE_MODE (type, mode);
1673 }
1674
1675 TYPE_SATURATING (type) = TYPE_SATURATING (TREE_TYPE (type));
1676 TYPE_UNSIGNED (type) = TYPE_UNSIGNED (TREE_TYPE (type));
1677 TYPE_SIZE_UNIT (type) = int_const_binop (MULT_EXPR,
1678 TYPE_SIZE_UNIT (innertype),
1679 size_int (nunits), 0);
1680 TYPE_SIZE (type) = int_const_binop (MULT_EXPR, TYPE_SIZE (innertype),
1681 bitsize_int (nunits), 0);
1682
1683 /* Always naturally align vectors. This prevents ABI changes
1684 depending on whether or not native vector modes are supported. */
1685 TYPE_ALIGN (type) = tree_low_cst (TYPE_SIZE (type), 0);
1686 break;
1687 }
1688
1689 case VOID_TYPE:
1690 /* This is an incomplete type and so doesn't have a size. */
1691 TYPE_ALIGN (type) = 1;
1692 TYPE_USER_ALIGN (type) = 0;
1693 SET_TYPE_MODE (type, VOIDmode);
1694 break;
1695
1696 case OFFSET_TYPE:
1697 TYPE_SIZE (type) = bitsize_int (POINTER_SIZE);
1698 TYPE_SIZE_UNIT (type) = size_int (POINTER_SIZE / BITS_PER_UNIT);
1699 /* A pointer might be MODE_PARTIAL_INT,
1700 but ptrdiff_t must be integral. */
1701 SET_TYPE_MODE (type, mode_for_size (POINTER_SIZE, MODE_INT, 0));
1702 break;
1703
1704 case FUNCTION_TYPE:
1705 case METHOD_TYPE:
1706 /* It's hard to see what the mode and size of a function ought to
1707 be, but we do know the alignment is FUNCTION_BOUNDARY, so
1708 make it consistent with that. */
1709 SET_TYPE_MODE (type, mode_for_size (FUNCTION_BOUNDARY, MODE_INT, 0));
1710 TYPE_SIZE (type) = bitsize_int (FUNCTION_BOUNDARY);
1711 TYPE_SIZE_UNIT (type) = size_int (FUNCTION_BOUNDARY / BITS_PER_UNIT);
1712 break;
1713
1714 case POINTER_TYPE:
1715 case REFERENCE_TYPE:
1716 {
1717 enum machine_mode mode = ((TREE_CODE (type) == REFERENCE_TYPE
1718 && reference_types_internal)
1719 ? Pmode : TYPE_MODE (type));
1720
1721 int nbits = GET_MODE_BITSIZE (mode);
1722
1723 TYPE_SIZE (type) = bitsize_int (nbits);
1724 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (mode));
1725 TYPE_UNSIGNED (type) = 1;
1726 TYPE_PRECISION (type) = nbits;
1727 }
1728 break;
1729
1730 case ARRAY_TYPE:
1731 {
1732 tree index = TYPE_DOMAIN (type);
1733 tree element = TREE_TYPE (type);
1734
1735 build_pointer_type (element);
1736
1737 /* We need to know both bounds in order to compute the size. */
1738 if (index && TYPE_MAX_VALUE (index) && TYPE_MIN_VALUE (index)
1739 && TYPE_SIZE (element))
1740 {
1741 tree ub = TYPE_MAX_VALUE (index);
1742 tree lb = TYPE_MIN_VALUE (index);
1743 tree length;
1744 tree element_size;
1745
1746 /* The initial subtraction should happen in the original type so
1747 that (possible) negative values are handled appropriately. */
1748 length = size_binop (PLUS_EXPR, size_one_node,
1749 fold_convert (sizetype,
1750 fold_build2 (MINUS_EXPR,
1751 TREE_TYPE (lb),
1752 ub, lb)));
1753
1754 /* Special handling for arrays of bits (for Chill). */
1755 element_size = TYPE_SIZE (element);
1756 if (TYPE_PACKED (type) && INTEGRAL_TYPE_P (element)
1757 && (integer_zerop (TYPE_MAX_VALUE (element))
1758 || integer_onep (TYPE_MAX_VALUE (element)))
1759 && host_integerp (TYPE_MIN_VALUE (element), 1))
1760 {
1761 HOST_WIDE_INT maxvalue
1762 = tree_low_cst (TYPE_MAX_VALUE (element), 1);
1763 HOST_WIDE_INT minvalue
1764 = tree_low_cst (TYPE_MIN_VALUE (element), 1);
1765
1766 if (maxvalue - minvalue == 1
1767 && (maxvalue == 1 || maxvalue == 0))
1768 element_size = integer_one_node;
1769 }
1770
1771 /* If neither bound is a constant and sizetype is signed, make
1772 sure the size is never negative. We should really do this
1773 if *either* bound is non-constant, but this is the best
1774 compromise between C and Ada. */
1775 if (!TYPE_UNSIGNED (sizetype)
1776 && TREE_CODE (TYPE_MIN_VALUE (index)) != INTEGER_CST
1777 && TREE_CODE (TYPE_MAX_VALUE (index)) != INTEGER_CST)
1778 length = size_binop (MAX_EXPR, length, size_zero_node);
1779
1780 TYPE_SIZE (type) = size_binop (MULT_EXPR, element_size,
1781 fold_convert (bitsizetype,
1782 length));
1783
1784 /* If we know the size of the element, calculate the total
1785 size directly, rather than do some division thing below.
1786 This optimization helps Fortran assumed-size arrays
1787 (where the size of the array is determined at runtime)
1788 substantially.
1789 Note that we can't do this in the case where the size of
1790 the elements is one bit since TYPE_SIZE_UNIT cannot be
1791 set correctly in that case. */
1792 if (TYPE_SIZE_UNIT (element) != 0 && ! integer_onep (element_size))
1793 TYPE_SIZE_UNIT (type)
1794 = size_binop (MULT_EXPR, TYPE_SIZE_UNIT (element), length);
1795 }
1796
1797 /* Now round the alignment and size,
1798 using machine-dependent criteria if any. */
1799
1800 #ifdef ROUND_TYPE_ALIGN
1801 TYPE_ALIGN (type)
1802 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (element), BITS_PER_UNIT);
1803 #else
1804 TYPE_ALIGN (type) = MAX (TYPE_ALIGN (element), BITS_PER_UNIT);
1805 #endif
1806 if (!TYPE_SIZE (element))
1807 /* We don't know the size of the underlying element type, so
1808 our alignment calculations will be wrong, forcing us to
1809 fall back on structural equality. */
1810 SET_TYPE_STRUCTURAL_EQUALITY (type);
1811 TYPE_USER_ALIGN (type) = TYPE_USER_ALIGN (element);
1812 SET_TYPE_MODE (type, BLKmode);
1813 if (TYPE_SIZE (type) != 0
1814 #ifdef MEMBER_TYPE_FORCES_BLK
1815 && ! MEMBER_TYPE_FORCES_BLK (type, VOIDmode)
1816 #endif
1817 /* BLKmode elements force BLKmode aggregate;
1818 else extract/store fields may lose. */
1819 && (TYPE_MODE (TREE_TYPE (type)) != BLKmode
1820 || TYPE_NO_FORCE_BLK (TREE_TYPE (type))))
1821 {
1822 /* One-element arrays get the component type's mode. */
1823 if (simple_cst_equal (TYPE_SIZE (type),
1824 TYPE_SIZE (TREE_TYPE (type))))
1825 SET_TYPE_MODE (type, TYPE_MODE (TREE_TYPE (type)));
1826 else
1827 SET_TYPE_MODE (type, mode_for_size_tree (TYPE_SIZE (type),
1828 MODE_INT, 1));
1829
1830 if (TYPE_MODE (type) != BLKmode
1831 && STRICT_ALIGNMENT && TYPE_ALIGN (type) < BIGGEST_ALIGNMENT
1832 && TYPE_ALIGN (type) < GET_MODE_ALIGNMENT (TYPE_MODE (type)))
1833 {
1834 TYPE_NO_FORCE_BLK (type) = 1;
1835 SET_TYPE_MODE (type, BLKmode);
1836 }
1837 }
1838 /* When the element size is constant, check that it is at least as
1839 large as the element alignment. */
1840 if (TYPE_SIZE_UNIT (element)
1841 && TREE_CODE (TYPE_SIZE_UNIT (element)) == INTEGER_CST
1842 /* If TYPE_SIZE_UNIT overflowed, then it is certainly larger than
1843 TYPE_ALIGN_UNIT. */
1844 && !TREE_OVERFLOW (TYPE_SIZE_UNIT (element))
1845 && !integer_zerop (TYPE_SIZE_UNIT (element))
1846 && compare_tree_int (TYPE_SIZE_UNIT (element),
1847 TYPE_ALIGN_UNIT (element)) < 0)
1848 error ("alignment of array elements is greater than element size");
1849 break;
1850 }
1851
1852 case RECORD_TYPE:
1853 case UNION_TYPE:
1854 case QUAL_UNION_TYPE:
1855 {
1856 tree field;
1857 record_layout_info rli;
1858
1859 /* Initialize the layout information. */
1860 rli = start_record_layout (type);
1861
1862 /* If this is a QUAL_UNION_TYPE, we want to process the fields
1863 in the reverse order in building the COND_EXPR that denotes
1864 its size. We reverse them again later. */
1865 if (TREE_CODE (type) == QUAL_UNION_TYPE)
1866 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
1867
1868 /* Place all the fields. */
1869 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1870 place_field (rli, field);
1871
1872 if (TREE_CODE (type) == QUAL_UNION_TYPE)
1873 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
1874
1875 /* Finish laying out the record. */
1876 finish_record_layout (rli, /*free_p=*/true);
1877 }
1878 break;
1879
1880 default:
1881 gcc_unreachable ();
1882 }
1883
1884 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
1885 records and unions, finish_record_layout already called this
1886 function. */
1887 if (TREE_CODE (type) != RECORD_TYPE
1888 && TREE_CODE (type) != UNION_TYPE
1889 && TREE_CODE (type) != QUAL_UNION_TYPE)
1890 finalize_type_size (type);
1891
1892 /* We should never see alias sets on incomplete aggregates. And we
1893 should not call layout_type on not incomplete aggregates. */
1894 if (AGGREGATE_TYPE_P (type))
1895 gcc_assert (!TYPE_ALIAS_SET_KNOWN_P (type));
1896 }
1897
1898 /* Vector types need to re-check the target flags each time we report
1899 the machine mode. We need to do this because attribute target can
1900 change the result of vector_mode_supported_p and have_regs_of_mode
1901 on a per-function basis. Thus the TYPE_MODE of a VECTOR_TYPE can
1902 change on a per-function basis. */
1903 /* ??? Possibly a better solution is to run through all the types
1904 referenced by a function and re-compute the TYPE_MODE once, rather
1905 than make the TYPE_MODE macro call a function. */
1906
1907 enum machine_mode
1908 vector_type_mode (const_tree t)
1909 {
1910 enum machine_mode mode;
1911
1912 gcc_assert (TREE_CODE (t) == VECTOR_TYPE);
1913
1914 mode = t->type.mode;
1915 if (VECTOR_MODE_P (mode)
1916 && (!targetm.vector_mode_supported_p (mode)
1917 || !have_regs_of_mode[mode]))
1918 {
1919 enum machine_mode innermode = TREE_TYPE (t)->type.mode;
1920
1921 /* For integers, try mapping it to a same-sized scalar mode. */
1922 if (GET_MODE_CLASS (innermode) == MODE_INT)
1923 {
1924 mode = mode_for_size (TYPE_VECTOR_SUBPARTS (t)
1925 * GET_MODE_BITSIZE (innermode), MODE_INT, 0);
1926
1927 if (mode != VOIDmode && have_regs_of_mode[mode])
1928 return mode;
1929 }
1930
1931 return BLKmode;
1932 }
1933
1934 return mode;
1935 }
1936
1937 /* Create and return a type for signed integers of PRECISION bits. */
1938
1939 tree
1940 make_signed_type (int precision)
1941 {
1942 tree type = make_node (INTEGER_TYPE);
1943
1944 TYPE_PRECISION (type) = precision;
1945
1946 fixup_signed_type (type);
1947 return type;
1948 }
1949
1950 /* Create and return a type for unsigned integers of PRECISION bits. */
1951
1952 tree
1953 make_unsigned_type (int precision)
1954 {
1955 tree type = make_node (INTEGER_TYPE);
1956
1957 TYPE_PRECISION (type) = precision;
1958
1959 fixup_unsigned_type (type);
1960 return type;
1961 }
1962
1963 /* Create and return a type for fract of PRECISION bits, UNSIGNEDP,
1964 and SATP. */
1965
1966 tree
1967 make_fract_type (int precision, int unsignedp, int satp)
1968 {
1969 tree type = make_node (FIXED_POINT_TYPE);
1970
1971 TYPE_PRECISION (type) = precision;
1972
1973 if (satp)
1974 TYPE_SATURATING (type) = 1;
1975
1976 /* Lay out the type: set its alignment, size, etc. */
1977 if (unsignedp)
1978 {
1979 TYPE_UNSIGNED (type) = 1;
1980 SET_TYPE_MODE (type, mode_for_size (precision, MODE_UFRACT, 0));
1981 }
1982 else
1983 SET_TYPE_MODE (type, mode_for_size (precision, MODE_FRACT, 0));
1984 layout_type (type);
1985
1986 return type;
1987 }
1988
1989 /* Create and return a type for accum of PRECISION bits, UNSIGNEDP,
1990 and SATP. */
1991
1992 tree
1993 make_accum_type (int precision, int unsignedp, int satp)
1994 {
1995 tree type = make_node (FIXED_POINT_TYPE);
1996
1997 TYPE_PRECISION (type) = precision;
1998
1999 if (satp)
2000 TYPE_SATURATING (type) = 1;
2001
2002 /* Lay out the type: set its alignment, size, etc. */
2003 if (unsignedp)
2004 {
2005 TYPE_UNSIGNED (type) = 1;
2006 SET_TYPE_MODE (type, mode_for_size (precision, MODE_UACCUM, 0));
2007 }
2008 else
2009 SET_TYPE_MODE (type, mode_for_size (precision, MODE_ACCUM, 0));
2010 layout_type (type);
2011
2012 return type;
2013 }
2014
2015 /* Initialize sizetype and bitsizetype to a reasonable and temporary
2016 value to enable integer types to be created. */
2017
2018 void
2019 initialize_sizetypes (bool signed_p)
2020 {
2021 tree t = make_node (INTEGER_TYPE);
2022 int precision = GET_MODE_BITSIZE (SImode);
2023
2024 SET_TYPE_MODE (t, SImode);
2025 TYPE_ALIGN (t) = GET_MODE_ALIGNMENT (SImode);
2026 TYPE_USER_ALIGN (t) = 0;
2027 TYPE_IS_SIZETYPE (t) = 1;
2028 TYPE_UNSIGNED (t) = !signed_p;
2029 TYPE_SIZE (t) = build_int_cst (t, precision);
2030 TYPE_SIZE_UNIT (t) = build_int_cst (t, GET_MODE_SIZE (SImode));
2031 TYPE_PRECISION (t) = precision;
2032
2033 /* Set TYPE_MIN_VALUE and TYPE_MAX_VALUE. */
2034 set_min_and_max_values_for_integral_type (t, precision, !signed_p);
2035
2036 sizetype = t;
2037 bitsizetype = build_distinct_type_copy (t);
2038 }
2039
2040 /* Make sizetype a version of TYPE, and initialize *sizetype
2041 accordingly. We do this by overwriting the stub sizetype and
2042 bitsizetype nodes created by initialize_sizetypes. This makes sure
2043 that (a) anything stubby about them no longer exists, (b) any
2044 INTEGER_CSTs created with such a type, remain valid. */
2045
2046 void
2047 set_sizetype (tree type)
2048 {
2049 int oprecision = TYPE_PRECISION (type);
2050 /* The *bitsizetype types use a precision that avoids overflows when
2051 calculating signed sizes / offsets in bits. However, when
2052 cross-compiling from a 32 bit to a 64 bit host, we are limited to 64 bit
2053 precision. */
2054 int precision = MIN (MIN (oprecision + BITS_PER_UNIT_LOG + 1,
2055 MAX_FIXED_MODE_SIZE),
2056 2 * HOST_BITS_PER_WIDE_INT);
2057 tree t;
2058
2059 gcc_assert (TYPE_UNSIGNED (type) == TYPE_UNSIGNED (sizetype));
2060
2061 t = build_distinct_type_copy (type);
2062 /* We do want to use sizetype's cache, as we will be replacing that
2063 type. */
2064 TYPE_CACHED_VALUES (t) = TYPE_CACHED_VALUES (sizetype);
2065 TYPE_CACHED_VALUES_P (t) = TYPE_CACHED_VALUES_P (sizetype);
2066 TREE_TYPE (TYPE_CACHED_VALUES (t)) = type;
2067 TYPE_UID (t) = TYPE_UID (sizetype);
2068 TYPE_IS_SIZETYPE (t) = 1;
2069
2070 /* Replace our original stub sizetype. */
2071 memcpy (sizetype, t, tree_size (sizetype));
2072 TYPE_MAIN_VARIANT (sizetype) = sizetype;
2073
2074 t = make_node (INTEGER_TYPE);
2075 TYPE_NAME (t) = get_identifier ("bit_size_type");
2076 /* We do want to use bitsizetype's cache, as we will be replacing that
2077 type. */
2078 TYPE_CACHED_VALUES (t) = TYPE_CACHED_VALUES (bitsizetype);
2079 TYPE_CACHED_VALUES_P (t) = TYPE_CACHED_VALUES_P (bitsizetype);
2080 TYPE_PRECISION (t) = precision;
2081 TYPE_UID (t) = TYPE_UID (bitsizetype);
2082 TYPE_IS_SIZETYPE (t) = 1;
2083
2084 /* Replace our original stub bitsizetype. */
2085 memcpy (bitsizetype, t, tree_size (bitsizetype));
2086 TYPE_MAIN_VARIANT (bitsizetype) = bitsizetype;
2087
2088 if (TYPE_UNSIGNED (type))
2089 {
2090 fixup_unsigned_type (bitsizetype);
2091 ssizetype = build_distinct_type_copy (make_signed_type (oprecision));
2092 TYPE_IS_SIZETYPE (ssizetype) = 1;
2093 sbitsizetype = build_distinct_type_copy (make_signed_type (precision));
2094 TYPE_IS_SIZETYPE (sbitsizetype) = 1;
2095 }
2096 else
2097 {
2098 fixup_signed_type (bitsizetype);
2099 ssizetype = sizetype;
2100 sbitsizetype = bitsizetype;
2101 }
2102
2103 /* If SIZETYPE is unsigned, we need to fix TYPE_MAX_VALUE so that
2104 it is sign extended in a way consistent with force_fit_type. */
2105 if (TYPE_UNSIGNED (type))
2106 {
2107 tree orig_max, new_max;
2108
2109 orig_max = TYPE_MAX_VALUE (sizetype);
2110
2111 /* Build a new node with the same values, but a different type.
2112 Sign extend it to ensure consistency. */
2113 new_max = build_int_cst_wide_type (sizetype,
2114 TREE_INT_CST_LOW (orig_max),
2115 TREE_INT_CST_HIGH (orig_max));
2116 TYPE_MAX_VALUE (sizetype) = new_max;
2117 }
2118 }
2119
2120 /* TYPE is an integral type, i.e., an INTEGRAL_TYPE, ENUMERAL_TYPE
2121 or BOOLEAN_TYPE. Set TYPE_MIN_VALUE and TYPE_MAX_VALUE
2122 for TYPE, based on the PRECISION and whether or not the TYPE
2123 IS_UNSIGNED. PRECISION need not correspond to a width supported
2124 natively by the hardware; for example, on a machine with 8-bit,
2125 16-bit, and 32-bit register modes, PRECISION might be 7, 23, or
2126 61. */
2127
2128 void
2129 set_min_and_max_values_for_integral_type (tree type,
2130 int precision,
2131 bool is_unsigned)
2132 {
2133 tree min_value;
2134 tree max_value;
2135
2136 if (is_unsigned)
2137 {
2138 min_value = build_int_cst (type, 0);
2139 max_value
2140 = build_int_cst_wide (type, precision - HOST_BITS_PER_WIDE_INT >= 0
2141 ? -1
2142 : ((HOST_WIDE_INT) 1 << precision) - 1,
2143 precision - HOST_BITS_PER_WIDE_INT > 0
2144 ? ((unsigned HOST_WIDE_INT) ~0
2145 >> (HOST_BITS_PER_WIDE_INT
2146 - (precision - HOST_BITS_PER_WIDE_INT)))
2147 : 0);
2148 }
2149 else
2150 {
2151 min_value
2152 = build_int_cst_wide (type,
2153 (precision - HOST_BITS_PER_WIDE_INT > 0
2154 ? 0
2155 : (HOST_WIDE_INT) (-1) << (precision - 1)),
2156 (((HOST_WIDE_INT) (-1)
2157 << (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
2158 ? precision - HOST_BITS_PER_WIDE_INT - 1
2159 : 0))));
2160 max_value
2161 = build_int_cst_wide (type,
2162 (precision - HOST_BITS_PER_WIDE_INT > 0
2163 ? -1
2164 : ((HOST_WIDE_INT) 1 << (precision - 1)) - 1),
2165 (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
2166 ? (((HOST_WIDE_INT) 1
2167 << (precision - HOST_BITS_PER_WIDE_INT - 1))) - 1
2168 : 0));
2169 }
2170
2171 TYPE_MIN_VALUE (type) = min_value;
2172 TYPE_MAX_VALUE (type) = max_value;
2173 }
2174
2175 /* Set the extreme values of TYPE based on its precision in bits,
2176 then lay it out. Used when make_signed_type won't do
2177 because the tree code is not INTEGER_TYPE.
2178 E.g. for Pascal, when the -fsigned-char option is given. */
2179
2180 void
2181 fixup_signed_type (tree type)
2182 {
2183 int precision = TYPE_PRECISION (type);
2184
2185 /* We can not represent properly constants greater then
2186 2 * HOST_BITS_PER_WIDE_INT, still we need the types
2187 as they are used by i386 vector extensions and friends. */
2188 if (precision > HOST_BITS_PER_WIDE_INT * 2)
2189 precision = HOST_BITS_PER_WIDE_INT * 2;
2190
2191 set_min_and_max_values_for_integral_type (type, precision,
2192 /*is_unsigned=*/false);
2193
2194 /* Lay out the type: set its alignment, size, etc. */
2195 layout_type (type);
2196 }
2197
2198 /* Set the extreme values of TYPE based on its precision in bits,
2199 then lay it out. This is used both in `make_unsigned_type'
2200 and for enumeral types. */
2201
2202 void
2203 fixup_unsigned_type (tree type)
2204 {
2205 int precision = TYPE_PRECISION (type);
2206
2207 /* We can not represent properly constants greater then
2208 2 * HOST_BITS_PER_WIDE_INT, still we need the types
2209 as they are used by i386 vector extensions and friends. */
2210 if (precision > HOST_BITS_PER_WIDE_INT * 2)
2211 precision = HOST_BITS_PER_WIDE_INT * 2;
2212
2213 TYPE_UNSIGNED (type) = 1;
2214
2215 set_min_and_max_values_for_integral_type (type, precision,
2216 /*is_unsigned=*/true);
2217
2218 /* Lay out the type: set its alignment, size, etc. */
2219 layout_type (type);
2220 }
2221
2222 /* Find the best machine mode to use when referencing a bit field of length
2223 BITSIZE bits starting at BITPOS.
2224
2225 The underlying object is known to be aligned to a boundary of ALIGN bits.
2226 If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
2227 larger than LARGEST_MODE (usually SImode).
2228
2229 If no mode meets all these conditions, we return VOIDmode.
2230
2231 If VOLATILEP is false and SLOW_BYTE_ACCESS is false, we return the
2232 smallest mode meeting these conditions.
2233
2234 If VOLATILEP is false and SLOW_BYTE_ACCESS is true, we return the
2235 largest mode (but a mode no wider than UNITS_PER_WORD) that meets
2236 all the conditions.
2237
2238 If VOLATILEP is true the narrow_volatile_bitfields target hook is used to
2239 decide which of the above modes should be used. */
2240
2241 enum machine_mode
2242 get_best_mode (int bitsize, int bitpos, unsigned int align,
2243 enum machine_mode largest_mode, int volatilep)
2244 {
2245 enum machine_mode mode;
2246 unsigned int unit = 0;
2247
2248 /* Find the narrowest integer mode that contains the bit field. */
2249 for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
2250 mode = GET_MODE_WIDER_MODE (mode))
2251 {
2252 unit = GET_MODE_BITSIZE (mode);
2253 if ((bitpos % unit) + bitsize <= unit)
2254 break;
2255 }
2256
2257 if (mode == VOIDmode
2258 /* It is tempting to omit the following line
2259 if STRICT_ALIGNMENT is true.
2260 But that is incorrect, since if the bitfield uses part of 3 bytes
2261 and we use a 4-byte mode, we could get a spurious segv
2262 if the extra 4th byte is past the end of memory.
2263 (Though at least one Unix compiler ignores this problem:
2264 that on the Sequent 386 machine. */
2265 || MIN (unit, BIGGEST_ALIGNMENT) > align
2266 || (largest_mode != VOIDmode && unit > GET_MODE_BITSIZE (largest_mode)))
2267 return VOIDmode;
2268
2269 if ((SLOW_BYTE_ACCESS && ! volatilep)
2270 || (volatilep && !targetm.narrow_volatile_bitfield ()))
2271 {
2272 enum machine_mode wide_mode = VOIDmode, tmode;
2273
2274 for (tmode = GET_CLASS_NARROWEST_MODE (MODE_INT); tmode != VOIDmode;
2275 tmode = GET_MODE_WIDER_MODE (tmode))
2276 {
2277 unit = GET_MODE_BITSIZE (tmode);
2278 if (bitpos / unit == (bitpos + bitsize - 1) / unit
2279 && unit <= BITS_PER_WORD
2280 && unit <= MIN (align, BIGGEST_ALIGNMENT)
2281 && (largest_mode == VOIDmode
2282 || unit <= GET_MODE_BITSIZE (largest_mode)))
2283 wide_mode = tmode;
2284 }
2285
2286 if (wide_mode != VOIDmode)
2287 return wide_mode;
2288 }
2289
2290 return mode;
2291 }
2292
2293 /* Gets minimal and maximal values for MODE (signed or unsigned depending on
2294 SIGN). The returned constants are made to be usable in TARGET_MODE. */
2295
2296 void
2297 get_mode_bounds (enum machine_mode mode, int sign,
2298 enum machine_mode target_mode,
2299 rtx *mmin, rtx *mmax)
2300 {
2301 unsigned size = GET_MODE_BITSIZE (mode);
2302 unsigned HOST_WIDE_INT min_val, max_val;
2303
2304 gcc_assert (size <= HOST_BITS_PER_WIDE_INT);
2305
2306 if (sign)
2307 {
2308 min_val = -((unsigned HOST_WIDE_INT) 1 << (size - 1));
2309 max_val = ((unsigned HOST_WIDE_INT) 1 << (size - 1)) - 1;
2310 }
2311 else
2312 {
2313 min_val = 0;
2314 max_val = ((unsigned HOST_WIDE_INT) 1 << (size - 1) << 1) - 1;
2315 }
2316
2317 *mmin = gen_int_mode (min_val, target_mode);
2318 *mmax = gen_int_mode (max_val, target_mode);
2319 }
2320
2321 #include "gt-stor-layout.h"