1 /* C-compiler utilities for types and variables storage layout
2 Copyright (C) 1987, 1988, 1992 Free Software Foundation, Inc.
4 This file is part of GNU CC.
6 GNU CC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
27 #define CEIL(x,y) (((x) + (y) - 1) / (y))
29 /* Data type for the expressions representing sizes of data types.
30 It is the first integer type laid out.
35 /* An integer constant with value 0 whose type is sizetype. */
39 /* An integer constant with value 1 whose type is sizetype. */
43 /* If nonzero, this is an upper limit on alignment of structure fields.
44 The value is measured in bits. */
45 int maximum_field_alignment;
47 #define GET_MODE_ALIGNMENT(MODE) \
48 MIN (BIGGEST_ALIGNMENT, \
49 MAX (1, (GET_MODE_UNIT_SIZE (MODE) * BITS_PER_UNIT)))
51 /* SAVE_EXPRs for sizes of types and decls, waiting to be expanded. */
53 static tree pending_sizes;
55 /* Nonzero means cannot safely call expand_expr now,
56 so put variable sizes onto `pending_sizes' instead. */
58 int immediate_size_expand;
63 tree chain = pending_sizes;
66 /* Put each SAVE_EXPR into the current function. */
67 for (t = chain; t; t = TREE_CHAIN (t))
68 SAVE_EXPR_CONTEXT (TREE_VALUE (t)) = current_function_decl;
73 /* Given a size SIZE that isn't constant, return a SAVE_EXPR
74 to serve as the actual size-expression for a type or decl. */
80 size = save_expr (size);
82 if (global_bindings_p ())
84 error ("variable-size type declared outside of any function");
88 if (immediate_size_expand)
89 /* NULL_RTX is not defined; neither is the rtx type. */
90 expand_expr (size, NULL_PTR, VOIDmode, 0);
92 pending_sizes = tree_cons (NULL_TREE, size, pending_sizes);
97 #ifndef MAX_FIXED_MODE_SIZE
98 #define MAX_FIXED_MODE_SIZE GET_MODE_BITSIZE (DImode)
101 /* Return the machine mode to use for a nonscalar of SIZE bits.
102 The mode must be in class CLASS, and have exactly that many bits.
103 If LIMIT is nonzero, modes of wider than MAX_FIXED_MODE_SIZE will not
107 mode_for_size (size, class, limit)
109 enum mode_class class;
112 register enum machine_mode mode;
114 if (limit && size > MAX_FIXED_MODE_SIZE)
117 /* Get the last mode which has this size, in the specified class. */
118 for (mode = GET_CLASS_NARROWEST_MODE (class); mode != VOIDmode;
119 mode = GET_MODE_WIDER_MODE (mode))
120 if (GET_MODE_BITSIZE (mode) == size)
126 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
129 round_up (value, divisor)
133 return size_binop (MULT_EXPR,
134 size_binop (CEIL_DIV_EXPR, value, size_int (divisor)),
138 /* Set the size, mode and alignment of a ..._DECL node.
139 TYPE_DECL does need this for C++.
140 Note that LABEL_DECL and CONST_DECL nodes do not need this,
141 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
142 Don't call layout_decl for them.
144 KNOWN_ALIGN is the amount of alignment we can assume this
145 decl has with no special effort. It is relevant only for FIELD_DECLs
146 and depends on the previous fields.
147 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
148 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
149 the record will be aligned to suit. */
152 layout_decl (decl, known_align)
154 unsigned known_align;
156 register tree type = TREE_TYPE (decl);
157 register enum tree_code code = TREE_CODE (decl);
158 int spec_size = DECL_FIELD_SIZE (decl);
160 if (code == CONST_DECL)
163 if (code != VAR_DECL && code != PARM_DECL && code != RESULT_DECL
164 && code != FIELD_DECL && code != TYPE_DECL)
167 if (type == error_mark_node)
169 type = void_type_node;
173 /* Usually the size and mode come from the data type without change. */
175 DECL_MODE (decl) = TYPE_MODE (type);
176 DECL_SIZE (decl) = TYPE_SIZE (type);
177 TREE_UNSIGNED (decl) = TREE_UNSIGNED (type);
179 if (code == FIELD_DECL && DECL_BIT_FIELD (decl))
181 /* This is a bit-field. We don't know how to handle
182 them except for integers and enums, and front end should
183 never generate them otherwise. */
185 if (! (TREE_CODE (type) == INTEGER_TYPE
186 || TREE_CODE (type) == ENUMERAL_TYPE))
189 if (spec_size == 0 && DECL_NAME (decl) != 0)
192 /* Size is specified number of bits. */
193 DECL_SIZE (decl) = size_int (spec_size);
195 /* Force alignment required for the data type.
196 But if the decl itself wants greater alignment, don't override that.
197 Likewise, if the decl is packed, don't override it. */
198 else if (DECL_ALIGN (decl) == 0
199 || (! DECL_PACKED (decl) && TYPE_ALIGN (type) > DECL_ALIGN (decl)))
200 DECL_ALIGN (decl) = TYPE_ALIGN (type);
202 /* See if we can use an ordinary integer mode for a bit-field. */
203 /* Conditions are: a fixed size that is correct for another mode
204 and occupying a complete byte or bytes on proper boundary. */
205 if (code == FIELD_DECL)
207 DECL_BIT_FIELD_TYPE (decl) = DECL_BIT_FIELD (decl) ? type : 0;
208 if (maximum_field_alignment != 0)
209 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), maximum_field_alignment);
212 if (DECL_BIT_FIELD (decl)
213 && TYPE_SIZE (type) != 0
214 && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST)
216 register enum machine_mode xmode
217 = mode_for_size (TREE_INT_CST_LOW (DECL_SIZE (decl)), MODE_INT, 1);
220 && known_align % GET_MODE_ALIGNMENT (xmode) == 0)
222 DECL_ALIGN (decl) = MAX (GET_MODE_ALIGNMENT (xmode),
224 DECL_MODE (decl) = xmode;
225 DECL_SIZE (decl) = size_int (GET_MODE_BITSIZE (xmode));
226 /* This no longer needs to be accessed as a bit field. */
227 DECL_BIT_FIELD (decl) = 0;
231 /* Evaluate nonconstant size only once, either now or as soon as safe. */
232 if (DECL_SIZE (decl) != 0 && TREE_CODE (DECL_SIZE (decl)) != INTEGER_CST)
233 DECL_SIZE (decl) = variable_size (DECL_SIZE (decl));
236 /* Lay out a RECORD_TYPE type (a C struct).
237 This means laying out the fields, determining their positions,
238 and computing the overall size and required alignment of the record.
239 Note that if you set the TYPE_ALIGN before calling this
240 then the struct is aligned to at least that boundary.
242 If the type has basetypes, you must call layout_basetypes
243 before calling this function.
245 The return value is a list of static members of the record.
246 They still need to be laid out. */
253 #ifdef STRUCTURE_SIZE_BOUNDARY
254 unsigned record_align = MAX (STRUCTURE_SIZE_BOUNDARY, TYPE_ALIGN (rec));
256 unsigned record_align = MAX (BITS_PER_UNIT, TYPE_ALIGN (rec));
258 /* These must be laid out *after* the record is. */
259 tree pending_statics = NULL_TREE;
260 /* Record size so far is CONST_SIZE + VAR_SIZE bits,
261 where CONST_SIZE is an integer
262 and VAR_SIZE is a tree expression.
263 If VAR_SIZE is null, the size is just CONST_SIZE.
264 Naturally we try to avoid using VAR_SIZE. */
265 register int const_size = 0;
266 register tree var_size = 0;
267 /* Once we start using VAR_SIZE, this is the maximum alignment
268 that we know VAR_SIZE has. */
269 register int var_align = BITS_PER_UNIT;
272 for (field = TYPE_FIELDS (rec); field; field = TREE_CHAIN (field))
274 register int desired_align;
276 /* If FIELD is static, then treat it like a separate variable,
277 not really like a structure field.
278 If it is a FUNCTION_DECL, it's a method.
279 In both cases, all we do is lay out the decl,
280 and we do it *after* the record is laid out. */
282 if (TREE_STATIC (field))
284 pending_statics = tree_cons (NULL_TREE, field, pending_statics);
287 /* Enumerators and enum types which are local to this class need not
288 be laid out. Likewise for initialized constant fields. */
289 if (TREE_CODE (field) != FIELD_DECL)
292 /* Lay out the field so we know what alignment it needs.
293 For KNOWN_ALIGN, pass the number of bits from start of record
294 or some divisor of it. */
296 /* For a packed field, use the alignment as specified,
297 disregarding what the type would want. */
298 if (DECL_PACKED (field))
299 desired_align = DECL_ALIGN (field);
300 layout_decl (field, var_size ? var_align : const_size);
301 if (! DECL_PACKED (field))
302 desired_align = DECL_ALIGN (field);
303 /* Some targets (i.e. VMS) limit struct field alignment
304 to a lower boundary than alignment of variables. */
305 #ifdef BIGGEST_FIELD_ALIGNMENT
306 desired_align = MIN (desired_align, BIGGEST_FIELD_ALIGNMENT);
309 /* Record must have at least as much alignment as any field.
310 Otherwise, the alignment of the field within the record
313 #ifndef PCC_BITFIELD_TYPE_MATTERS
314 record_align = MAX (record_align, desired_align);
316 if (PCC_BITFIELD_TYPE_MATTERS && TREE_TYPE (field) != error_mark_node
317 && DECL_BIT_FIELD_TYPE (field)
318 && ! integer_zerop (TYPE_SIZE (TREE_TYPE (field))))
320 /* For these machines, a zero-length field does not
321 affect the alignment of the structure as a whole.
322 It does, however, affect the alignment of the next field
323 within the structure. */
324 if (! integer_zerop (DECL_SIZE (field)))
325 record_align = MAX (record_align, desired_align);
326 else if (! DECL_PACKED (field))
327 desired_align = TYPE_ALIGN (TREE_TYPE (field));
328 /* A named bit field of declared type `int'
329 forces the entire structure to have `int' alignment. */
330 if (DECL_NAME (field) != 0)
332 int type_align = TYPE_ALIGN (TREE_TYPE (field));
333 if (maximum_field_alignment != 0)
334 type_align = MIN (type_align, maximum_field_alignment);
336 record_align = MAX (record_align, type_align);
340 record_align = MAX (record_align, desired_align);
343 /* Does this field automatically have alignment it needs
344 by virtue of the fields that precede it and the record's
347 if (const_size % desired_align != 0
348 || (var_align % desired_align != 0
351 /* No, we need to skip space before this field.
352 Bump the cumulative size to multiple of field alignment. */
355 || var_align % desired_align == 0)
357 = CEIL (const_size, desired_align) * desired_align;
361 var_size = size_binop (PLUS_EXPR, var_size,
362 size_int (const_size));
364 var_size = round_up (var_size, desired_align);
365 var_align = MIN (var_align, desired_align);
369 #ifdef PCC_BITFIELD_TYPE_MATTERS
370 if (PCC_BITFIELD_TYPE_MATTERS
371 && TREE_CODE (field) == FIELD_DECL
372 && TREE_TYPE (field) != error_mark_node
373 && DECL_BIT_FIELD_TYPE (field)
374 && !DECL_PACKED (field)
375 && !integer_zerop (DECL_SIZE (field)))
377 int type_align = TYPE_ALIGN (TREE_TYPE (field));
378 register tree dsize = DECL_SIZE (field);
379 int field_size = TREE_INT_CST_LOW (dsize);
381 if (maximum_field_alignment != 0)
382 type_align = MIN (type_align, maximum_field_alignment);
384 /* A bit field may not span the unit of alignment of its type.
385 Advance to next boundary if necessary. */
386 /* ??? There is some uncertainty here as to what
387 should be done if type_align is less than the width of the type.
388 That can happen because the width exceeds BIGGEST_ALIGNMENT
389 or because it exceeds maximum_field_alignment. */
390 if (const_size / type_align
391 != (const_size + field_size - 1) / type_align)
392 const_size = CEIL (const_size, type_align) * type_align;
396 /* No existing machine description uses this parameter.
397 So I have made it in this aspect identical to PCC_BITFIELD_TYPE_MATTERS. */
398 #ifdef BITFIELD_NBYTES_LIMITED
399 if (BITFIELD_NBYTES_LIMITED
400 && TREE_CODE (field) == FIELD_DECL
401 && TREE_TYPE (field) != error_mark_node
402 && DECL_BIT_FIELD_TYPE (field)
403 && !DECL_PACKED (field)
404 && !integer_zerop (DECL_SIZE (field)))
406 int type_align = TYPE_ALIGN (TREE_TYPE (field));
407 register tree dsize = DECL_SIZE (field);
408 int field_size = TREE_INT_CST_LOW (dsize);
410 if (maximum_field_alignment != 0)
411 type_align = MIN (type_align, maximum_field_alignment);
413 /* A bit field may not span the unit of alignment of its type.
414 Advance to next boundary if necessary. */
415 if (const_size / type_align
416 != (const_size + field_size - 1) / type_align)
417 const_size = CEIL (const_size, type_align) * type_align;
421 /* Size so far becomes the position of this field. */
423 if (var_size && const_size)
424 DECL_FIELD_BITPOS (field)
425 = size_binop (PLUS_EXPR, var_size, size_int (const_size));
427 DECL_FIELD_BITPOS (field) = var_size;
429 DECL_FIELD_BITPOS (field) = size_int (const_size);
431 /* If this field is an anonymous union,
432 give each union-member the same position as the union has. */
434 if (DECL_NAME (field) == 0
435 && TREE_CODE (TREE_TYPE (field)) == UNION_TYPE)
437 tree uelt = TYPE_FIELDS (TREE_TYPE (field));
438 for (; uelt; uelt = TREE_CHAIN (uelt))
440 DECL_FIELD_CONTEXT (uelt) = DECL_FIELD_CONTEXT (field);
441 DECL_FIELD_BITPOS (uelt) = DECL_FIELD_BITPOS (field);
445 /* Now add size of this field to the size of the record. */
448 register tree dsize = DECL_SIZE (field);
450 /* This can happen when we have an invalid nested struct definition,
451 such as struct j { struct j { int i; } }. The error message is
452 printed in finish_struct. */
455 else if (TREE_CODE (dsize) == INTEGER_CST
456 && TREE_INT_CST_HIGH (dsize) == 0
457 && TREE_INT_CST_LOW (dsize) + const_size > const_size)
458 /* Use const_size if there's no overflow. */
459 const_size += TREE_INT_CST_LOW (dsize);
465 var_size = size_binop (PLUS_EXPR, var_size, dsize);
470 /* Work out the total size and alignment of the record
471 as one expression and store in the record type.
472 Round it up to a multiple of the record's alignment. */
476 TYPE_SIZE (rec) = size_int (const_size);
482 = size_binop (PLUS_EXPR, var_size, size_int (const_size));
483 TYPE_SIZE (rec) = var_size;
486 /* Determine the desired alignment. */
487 #ifdef ROUND_TYPE_ALIGN
488 TYPE_ALIGN (rec) = ROUND_TYPE_ALIGN (rec, TYPE_ALIGN (rec), record_align);
490 TYPE_ALIGN (rec) = MAX (TYPE_ALIGN (rec), record_align);
493 #ifdef ROUND_TYPE_SIZE
494 TYPE_SIZE (rec) = ROUND_TYPE_SIZE (rec, TYPE_SIZE (rec), TYPE_ALIGN (rec));
496 /* Round the size up to be a multiple of the required alignment */
497 TYPE_SIZE (rec) = round_up (TYPE_SIZE (rec), TYPE_ALIGN (rec));
500 return pending_statics;
503 /* Lay out a UNION_TYPE type.
504 Lay out all the fields, set their positions to zero,
505 and compute the size and alignment of the union (maximum of any field).
506 Note that if you set the TYPE_ALIGN before calling this
507 then the union align is aligned to at least that boundary. */
514 #ifdef STRUCTURE_SIZE_BOUNDARY
515 unsigned union_align = STRUCTURE_SIZE_BOUNDARY;
517 unsigned union_align = BITS_PER_UNIT;
520 /* The size of the union, based on the fields scanned so far,
521 is max (CONST_SIZE, VAR_SIZE).
522 VAR_SIZE may be null; then CONST_SIZE by itself is the size. */
523 register int const_size = 0;
524 register tree var_size = 0;
526 for (field = TYPE_FIELDS (rec); field; field = TREE_CHAIN (field))
528 /* Enums which are local to this class need not be laid out. */
529 if (TREE_CODE (field) == CONST_DECL || TREE_CODE (field) == TYPE_DECL)
532 layout_decl (field, 0);
533 DECL_FIELD_BITPOS (field) = size_int (0);
535 /* Union must be at least as aligned as any field requires. */
537 union_align = MAX (union_align, DECL_ALIGN (field));
539 #ifdef PCC_BITFIELD_TYPE_MATTERS
540 /* On the m88000, a bit field of declare type `int'
541 forces the entire union to have `int' alignment. */
542 if (PCC_BITFIELD_TYPE_MATTERS && DECL_BIT_FIELD_TYPE (field))
543 union_align = MAX (union_align, TYPE_ALIGN (TREE_TYPE (field)));
546 /* Set union_size to max (decl_size, union_size).
547 There are more and less general ways to do this.
548 Use only CONST_SIZE unless forced to use VAR_SIZE. */
550 if (TREE_CODE (DECL_SIZE (field)) == INTEGER_CST)
551 const_size = MAX (const_size, TREE_INT_CST_LOW (DECL_SIZE (field)));
552 else if (var_size == 0)
553 var_size = DECL_SIZE (field);
555 var_size = size_binop (MAX_EXPR, var_size, DECL_SIZE (field));
558 /* Determine the ultimate size of the union (in bytes). */
559 if (NULL == var_size)
560 TYPE_SIZE (rec) = size_int (CEIL (const_size, BITS_PER_UNIT)
562 else if (const_size == 0)
563 TYPE_SIZE (rec) = var_size;
565 TYPE_SIZE (rec) = size_binop (MAX_EXPR, var_size,
566 round_up (size_int (const_size),
569 /* Determine the desired alignment. */
570 #ifdef ROUND_TYPE_ALIGN
571 TYPE_ALIGN (rec) = ROUND_TYPE_ALIGN (rec, TYPE_ALIGN (rec), union_align);
573 TYPE_ALIGN (rec) = MAX (TYPE_ALIGN (rec), union_align);
576 #ifdef ROUND_TYPE_SIZE
577 TYPE_SIZE (rec) = ROUND_TYPE_SIZE (rec, TYPE_SIZE (rec), TYPE_ALIGN (rec));
579 /* Round the size up to be a multiple of the required alignment */
580 TYPE_SIZE (rec) = round_up (TYPE_SIZE (rec), TYPE_ALIGN (rec));
584 /* Calculate the mode, size, and alignment for TYPE.
585 For an array type, calculate the element separation as well.
586 Record TYPE on the chain of permanent or temporary types
587 so that dbxout will find out about it.
589 TYPE_SIZE of a type is nonzero if the type has been laid out already.
590 layout_type does nothing on such a type.
592 If the type is incomplete, its TYPE_SIZE remains zero. */
599 tree pending_statics;
604 /* Do nothing if type has been laid out before. */
605 if (TYPE_SIZE (type))
608 /* Make sure all nodes we allocate are not momentary;
609 they must last past the current statement. */
610 old = suspend_momentary ();
612 /* If we are processing a permanent type, make nodes permanent.
613 If processing a temporary type, make it saveable, since the
614 type node itself is. This is important if the function is inline,
615 since its decls will get copied later. */
616 push_obstacks_nochange ();
617 if (allocation_temporary_p ())
619 if (TREE_PERMANENT (type))
620 end_temporary_allocation ();
622 saveable_allocation ();
625 switch (TREE_CODE (type))
628 /* This kind of type is the responsibility
629 of the languge-specific code. */
634 if (TREE_INT_CST_HIGH (TYPE_MIN_VALUE (type)) >= 0)
635 TREE_UNSIGNED (type) = 1;
637 /* We pass 0 for the last arg of mode_for_size because otherwise
638 on the Apollo using long long causes a crash.
639 It seems better to use integer modes than to try to support
640 integer types with BLKmode. */
641 TYPE_MODE (type) = mode_for_size (TYPE_PRECISION (type), MODE_INT, 0);
642 TYPE_SIZE (type) = size_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
646 TYPE_MODE (type) = mode_for_size (TYPE_PRECISION (type), MODE_FLOAT, 0);
647 TYPE_SIZE (type) = size_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
651 TREE_UNSIGNED (type) = TREE_UNSIGNED (TREE_TYPE (type));
653 = mode_for_size (2 * TYPE_PRECISION (TREE_TYPE (type)),
654 (TREE_CODE (TREE_TYPE (type)) == INTEGER_TYPE
655 ? MODE_COMPLEX_INT : MODE_COMPLEX_FLOAT),
657 TYPE_SIZE (type) = size_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
661 TYPE_SIZE (type) = size_zero_node;
662 TYPE_ALIGN (type) = 1;
663 TYPE_MODE (type) = VOIDmode;
667 TYPE_SIZE (type) = size_int (GET_MODE_BITSIZE (Pmode));
668 TYPE_MODE (type) = Pmode;
673 TYPE_MODE (type) = mode_for_size (2 * GET_MODE_BITSIZE (Pmode),
675 TYPE_SIZE (type) = size_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
680 TYPE_MODE (type) = Pmode;
681 TYPE_SIZE (type) = size_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
682 TREE_UNSIGNED (type) = 1;
683 TYPE_PRECISION (type) = GET_MODE_BITSIZE (TYPE_MODE (type));
688 register tree index = TYPE_DOMAIN (type);
689 register tree element = TREE_TYPE (type);
691 build_pointer_type (element);
693 /* We need to know both bounds in order to compute the size. */
694 if (index && TYPE_MAX_VALUE (index) && TYPE_MIN_VALUE (index)
695 && TYPE_SIZE (element))
698 = size_binop (PLUS_EXPR, size_one_node,
699 size_binop (MINUS_EXPR, TYPE_MAX_VALUE (index),
700 TYPE_MIN_VALUE (index)));
702 TYPE_SIZE (type) = size_binop (MULT_EXPR, length,
703 TYPE_SIZE (element));
706 /* Now round the alignment and size,
707 using machine-dependent criteria if any. */
709 #ifdef ROUND_TYPE_ALIGN
711 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (element), BITS_PER_UNIT);
713 TYPE_ALIGN (type) = MAX (TYPE_ALIGN (element), BITS_PER_UNIT);
716 #ifdef ROUND_TYPE_SIZE
717 if (TYPE_SIZE (type) != 0)
719 = ROUND_TYPE_SIZE (type, TYPE_SIZE (type), TYPE_ALIGN (type));
722 TYPE_MODE (type) = BLKmode;
723 if (TYPE_SIZE (type) != 0
724 && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
725 /* BLKmode elements force BLKmode aggregate;
726 else extract/store fields may lose. */
727 && (TYPE_MODE (TREE_TYPE (type)) != BLKmode
728 || TYPE_NO_FORCE_BLK (TREE_TYPE (type))))
731 = mode_for_size (TREE_INT_CST_LOW (TYPE_SIZE (type)),
734 if (STRICT_ALIGNMENT && TYPE_ALIGN (type) < BIGGEST_ALIGNMENT
735 && TYPE_ALIGN (type) < TREE_INT_CST_LOW (TYPE_SIZE (type))
736 && TYPE_MODE (type) != BLKmode)
738 TYPE_NO_FORCE_BLK (type) = 1;
739 TYPE_MODE (type) = BLKmode;
746 pending_statics = layout_record (type);
747 TYPE_MODE (type) = BLKmode;
748 if (TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST)
751 /* A record which has any BLKmode members must itself be BLKmode;
752 it can't go in a register.
753 Unless the member is BLKmode only because it isn't aligned. */
754 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
758 if (TREE_CODE (field) != FIELD_DECL)
761 if (TYPE_MODE (TREE_TYPE (field)) == BLKmode
762 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field)))
765 if (TREE_CODE (DECL_FIELD_BITPOS (field)) != INTEGER_CST)
768 bitpos = TREE_INT_CST_LOW (DECL_FIELD_BITPOS (field));
770 /* Must be BLKmode if any field crosses a word boundary,
771 since extract_bit_field can't handle that in registers. */
772 if (bitpos / BITS_PER_WORD
773 != ((TREE_INT_CST_LOW (DECL_SIZE (field)) + bitpos - 1)
775 /* But there is no problem if the field is entire words. */
776 && TREE_INT_CST_LOW (DECL_SIZE (field)) % BITS_PER_WORD == 0)
781 = mode_for_size (TREE_INT_CST_LOW (TYPE_SIZE (type)),
784 /* If structure's known alignment is less than
785 what the scalar mode would need, and it matters,
786 then stick with BLKmode. */
788 && ! (TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT
789 || (TYPE_ALIGN (type)
790 >= TREE_INT_CST_LOW (TYPE_SIZE (type)))))
792 if (TYPE_MODE (type) != BLKmode)
793 /* If this is the only reason this type is BLKmode,
794 then don't force containing types to be BLKmode. */
795 TYPE_NO_FORCE_BLK (type) = 1;
796 TYPE_MODE (type) = BLKmode;
802 /* Lay out any static members. This is done now
803 because their type may use the record's type. */
804 while (pending_statics)
806 layout_decl (TREE_VALUE (pending_statics), 0);
807 pending_statics = TREE_CHAIN (pending_statics);
813 TYPE_MODE (type) = BLKmode;
814 if (TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
815 /* If structure's known alignment is less than
816 what the scalar mode would need, and it matters,
817 then stick with BLKmode. */
818 && (! STRICT_ALIGNMENT
819 || TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT
820 || TYPE_ALIGN (type) >= TREE_INT_CST_LOW (TYPE_SIZE (type))))
823 /* A union which has any BLKmode members must itself be BLKmode;
824 it can't go in a register.
825 Unless the member is BLKmode only because it isn't aligned. */
826 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
828 if (TREE_CODE (field) != FIELD_DECL)
831 if (TYPE_MODE (TREE_TYPE (field)) == BLKmode
832 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field)))
837 = mode_for_size (TREE_INT_CST_LOW (TYPE_SIZE (type)),
845 case BOOLEAN_TYPE: /* store one byte/boolean for now. */
846 TYPE_MODE (type) = QImode;
847 TYPE_SIZE (type) = size_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
848 TYPE_PRECISION (type) = 1;
849 TYPE_ALIGN (type) = GET_MODE_ALIGNMENT (TYPE_MODE (type));
853 TYPE_MODE (type) = QImode;
854 TYPE_SIZE (type) = size_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
855 TYPE_PRECISION (type) = GET_MODE_BITSIZE (TYPE_MODE (type));
856 TYPE_ALIGN (type) = GET_MODE_ALIGNMENT (TYPE_MODE (type));
860 /* The size may vary in different languages, so the language front end
861 should fill in the size. */
862 TYPE_ALIGN (type) = BIGGEST_ALIGNMENT;
863 TYPE_MODE (type) = BLKmode;
870 /* Normally, use the alignment corresponding to the mode chosen.
871 However, where strict alignment is not required, avoid
872 over-aligning structures, since most compilers do not do this
875 if (TYPE_MODE (type) != BLKmode && TYPE_MODE (type) != VOIDmode
877 || (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE
878 && TREE_CODE (type) != ARRAY_TYPE)))
879 TYPE_ALIGN (type) = GET_MODE_ALIGNMENT (TYPE_MODE (type));
881 /* Evaluate nonconstant size only once, either now or as soon as safe. */
882 if (TYPE_SIZE (type) != 0 && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
883 TYPE_SIZE (type) = variable_size (TYPE_SIZE (type));
885 /* Also layout any other variants of the type. */
886 if (TYPE_NEXT_VARIANT (type)
887 || type != TYPE_MAIN_VARIANT (type))
890 /* Record layout info of this variant. */
891 tree size = TYPE_SIZE (type);
892 int align = TYPE_ALIGN (type);
893 enum machine_mode mode = TYPE_MODE (type);
895 /* Copy it into all variants. */
896 for (variant = TYPE_MAIN_VARIANT (type);
898 variant = TYPE_NEXT_VARIANT (variant))
900 TYPE_SIZE (variant) = size;
901 TYPE_ALIGN (variant) = align;
902 TYPE_MODE (variant) = mode;
907 resume_momentary (old);
910 /* Create and return a type for signed integers of PRECISION bits. */
913 make_signed_type (precision)
916 register tree type = make_node (INTEGER_TYPE);
918 TYPE_PRECISION (type) = precision;
920 /* Create the extreme values based on the number of bits. */
922 TYPE_MIN_VALUE (type)
923 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
924 ? 0 : (HOST_WIDE_INT) (-1) << (precision - 1)),
925 (((HOST_WIDE_INT) (-1)
926 << (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
927 ? precision - HOST_BITS_PER_WIDE_INT - 1
929 TYPE_MAX_VALUE (type)
930 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
931 ? -1 : ((HOST_WIDE_INT) 1 << (precision - 1)) - 1),
932 (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
933 ? (((HOST_WIDE_INT) 1
934 << (precision - HOST_BITS_PER_WIDE_INT - 1))) - 1
937 /* Give this type's extreme values this type as their type. */
939 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
940 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
942 /* The first type made with this or `make_unsigned_type'
943 is the type for size values. */
950 /* Lay out the type: set its alignment, size, etc. */
957 /* Create and return a type for unsigned integers of PRECISION bits. */
960 make_unsigned_type (precision)
963 register tree type = make_node (INTEGER_TYPE);
965 TYPE_PRECISION (type) = precision;
967 /* The first type made with this or `make_signed_type'
968 is the type for size values. */
975 fixup_unsigned_type (type);
979 /* Set the extreme values of TYPE based on its precision in bits,
980 then lay it out. Used when make_signed_type won't do
981 because the tree code is not INTEGER_TYPE.
982 E.g. for Pascal, when the -fsigned-char option is given. */
985 fixup_signed_type (type)
988 register int precision = TYPE_PRECISION (type);
990 TYPE_MIN_VALUE (type)
991 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
992 ? 0 : (HOST_WIDE_INT) (-1) << (precision - 1)),
993 (((HOST_WIDE_INT) (-1)
994 << (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
995 ? precision - HOST_BITS_PER_WIDE_INT - 1
997 TYPE_MAX_VALUE (type)
998 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
999 ? -1 : ((HOST_WIDE_INT) 1 << (precision - 1)) - 1),
1000 (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1001 ? (((HOST_WIDE_INT) 1
1002 << (precision - HOST_BITS_PER_WIDE_INT - 1))) - 1
1005 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
1006 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
1008 /* Lay out the type: set its alignment, size, etc. */
1013 /* Set the extreme values of TYPE based on its precision in bits,
1014 then lay it out. This is used both in `make_unsigned_type'
1015 and for enumeral types. */
1018 fixup_unsigned_type (type)
1021 register int precision = TYPE_PRECISION (type);
1023 TYPE_MIN_VALUE (type) = build_int_2 (0, 0);
1024 TYPE_MAX_VALUE (type)
1025 = build_int_2 (precision - HOST_BITS_PER_WIDE_INT >= 0
1026 ? -1 : ((HOST_WIDE_INT) 1 << precision) - 1,
1027 precision - HOST_BITS_PER_WIDE_INT > 0
1028 ? ((unsigned HOST_WIDE_INT) ~0
1029 >> (HOST_BITS_PER_WIDE_INT
1030 - (precision - HOST_BITS_PER_WIDE_INT)))
1032 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
1033 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
1035 /* Lay out the type: set its alignment, size, etc. */
1040 /* Find the best machine mode to use when referencing a bit field of length
1041 BITSIZE bits starting at BITPOS.
1043 The underlying object is known to be aligned to a boundary of ALIGN bits.
1044 If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
1045 larger than LARGEST_MODE (usually SImode).
1047 If no mode meets all these conditions, we return VOIDmode. Otherwise, if
1048 VOLATILEP is true or SLOW_BYTE_ACCESS is false, we return the smallest
1049 mode meeting these conditions.
1051 Otherwise (VOLATILEP is false and SLOW_BYTE_ACCESS is true), we return
1052 the largest mode (but a mode no wider than UNITS_PER_WORD) that meets
1053 all the conditions. */
1056 get_best_mode (bitsize, bitpos, align, largest_mode, volatilep)
1057 int bitsize, bitpos;
1059 enum machine_mode largest_mode;
1062 enum machine_mode mode;
1065 /* Find the narrowest integer mode that contains the bit field. */
1066 for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
1067 mode = GET_MODE_WIDER_MODE (mode))
1069 unit = GET_MODE_BITSIZE (mode);
1070 if (bitpos / unit == (bitpos + bitsize - 1) / unit)
1074 if (mode == MAX_MACHINE_MODE
1075 /* It is tempting to omit the following line
1076 if STRICT_ALIGNMENT is true.
1077 But that is incorrect, since if the bitfield uses part of 3 bytes
1078 and we use a 4-byte mode, we could get a spurious segv
1079 if the extra 4th byte is past the end of memory.
1080 (Though at least one Unix compiler ignores this problem:
1081 that on the Sequent 386 machine. */
1082 || MIN (unit, BIGGEST_ALIGNMENT) > align
1083 || (largest_mode != VOIDmode && unit > GET_MODE_BITSIZE (largest_mode)))
1086 if (SLOW_BYTE_ACCESS && ! volatilep)
1088 enum machine_mode wide_mode = VOIDmode, tmode;
1090 for (tmode = GET_CLASS_NARROWEST_MODE (MODE_INT); tmode != VOIDmode;
1091 tmode = GET_MODE_WIDER_MODE (tmode))
1093 unit = GET_MODE_BITSIZE (tmode);
1094 if (bitpos / unit == (bitpos + bitsize - 1) / unit
1095 && unit <= BITS_PER_WORD
1096 && unit <= MIN (align, BIGGEST_ALIGNMENT)
1097 && (largest_mode == VOIDmode
1098 || unit <= GET_MODE_BITSIZE (largest_mode)))
1102 if (wide_mode != VOIDmode)
1109 /* Save all variables describing the current status into the structure *P.
1110 This is used before starting a nested function. */
1113 save_storage_status (p)
1116 #if 0 /* Need not save, since always 0 and non0 (resp.) within a function. */
1117 p->pending_sizes = pending_sizes;
1118 p->immediate_size_expand = immediate_size_expand;
1122 /* Restore all variables describing the current status from the structure *P.
1123 This is used after a nested function. */
1126 restore_storage_status (p)
1130 pending_sizes = p->pending_sizes;
1131 immediate_size_expand = p->immediate_size_expand;