1 /* C-compiler utilities for types and variables storage layout
2 Copyright (C) 1987, 88, 92, 93, 94, 95, 1996 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, 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
29 #define CEIL(x,y) (((x) + (y) - 1) / (y))
31 /* Data type for the expressions representing sizes of data types.
32 It is the first integer type laid out.
37 /* An integer constant with value 0 whose type is sizetype. */
41 /* An integer constant with value 1 whose type is sizetype. */
45 /* If nonzero, this is an upper limit on alignment of structure fields.
46 The value is measured in bits. */
47 int maximum_field_alignment;
49 /* If non-zero, the alignment of a bitstring or (power-)set value, in bits.
50 May be overridden by front-ends. */
51 int set_alignment = 0;
53 #define GET_MODE_ALIGNMENT(MODE) \
54 MIN (BIGGEST_ALIGNMENT, \
55 MAX (1, (GET_MODE_UNIT_SIZE (MODE) * BITS_PER_UNIT)))
57 static enum machine_mode smallest_mode_for_size PROTO((unsigned int,
59 static tree layout_record PROTO((tree));
60 static void layout_union PROTO((tree));
62 /* SAVE_EXPRs for sizes of types and decls, waiting to be expanded. */
64 static tree pending_sizes;
66 /* Nonzero means cannot safely call expand_expr now,
67 so put variable sizes onto `pending_sizes' instead. */
69 int immediate_size_expand;
74 tree chain = pending_sizes;
77 /* Put each SAVE_EXPR into the current function. */
78 for (t = chain; t; t = TREE_CHAIN (t))
79 SAVE_EXPR_CONTEXT (TREE_VALUE (t)) = current_function_decl;
85 put_pending_sizes (chain)
91 pending_sizes = chain;
94 /* Given a size SIZE that may not be a constant, return a SAVE_EXPR
95 to serve as the actual size-expression for a type or decl. */
101 /* If the language-processor is to take responsibility for variable-sized
102 items (e.g., languages which have elaboration procedures like Ada),
103 just return SIZE unchanged. Likewise for self-referential sizes. */
104 if (TREE_CONSTANT (size)
105 || global_bindings_p () < 0 || contains_placeholder_p (size))
108 size = save_expr (size);
110 if (global_bindings_p ())
112 if (TREE_CONSTANT (size))
113 error ("type size can't be explicitly evaluated");
115 error ("variable-size type declared outside of any function");
120 if (immediate_size_expand)
121 /* NULL_RTX is not defined; neither is the rtx type.
122 Also, we would like to pass const0_rtx here, but don't have it. */
123 expand_expr (size, expand_expr (integer_zero_node, NULL_PTR, VOIDmode, 0),
126 pending_sizes = tree_cons (NULL_TREE, size, pending_sizes);
131 #ifndef MAX_FIXED_MODE_SIZE
132 #define MAX_FIXED_MODE_SIZE GET_MODE_BITSIZE (DImode)
135 /* Return the machine mode to use for a nonscalar of SIZE bits.
136 The mode must be in class CLASS, and have exactly that many bits.
137 If LIMIT is nonzero, modes of wider than MAX_FIXED_MODE_SIZE will not
141 mode_for_size (size, class, limit)
143 enum mode_class class;
146 register enum machine_mode mode;
148 if (limit && size > MAX_FIXED_MODE_SIZE)
151 /* Get the first mode which has this size, in the specified class. */
152 for (mode = GET_CLASS_NARROWEST_MODE (class); mode != VOIDmode;
153 mode = GET_MODE_WIDER_MODE (mode))
154 if (GET_MODE_BITSIZE (mode) == size)
160 /* Similar, but never return BLKmode; return the narrowest mode that
161 contains at least the requested number of bits. */
163 static enum machine_mode
164 smallest_mode_for_size (size, class)
166 enum mode_class class;
168 register enum machine_mode mode;
170 /* Get the first mode which has at least this size, in the
172 for (mode = GET_CLASS_NARROWEST_MODE (class); mode != VOIDmode;
173 mode = GET_MODE_WIDER_MODE (mode))
174 if (GET_MODE_BITSIZE (mode) >= size)
180 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
183 round_up (value, divisor)
187 return size_binop (MULT_EXPR,
188 size_binop (CEIL_DIV_EXPR, value, size_int (divisor)),
192 /* Set the size, mode and alignment of a ..._DECL node.
193 TYPE_DECL does need this for C++.
194 Note that LABEL_DECL and CONST_DECL nodes do not need this,
195 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
196 Don't call layout_decl for them.
198 KNOWN_ALIGN is the amount of alignment we can assume this
199 decl has with no special effort. It is relevant only for FIELD_DECLs
200 and depends on the previous fields.
201 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
202 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
203 the record will be aligned to suit. */
206 layout_decl (decl, known_align)
208 unsigned known_align;
210 register tree type = TREE_TYPE (decl);
211 register enum tree_code code = TREE_CODE (decl);
212 int spec_size = DECL_FIELD_SIZE (decl);
214 if (code == CONST_DECL)
217 if (code != VAR_DECL && code != PARM_DECL && code != RESULT_DECL
218 && code != FIELD_DECL && code != TYPE_DECL)
221 if (type == error_mark_node)
223 type = void_type_node;
227 /* Usually the size and mode come from the data type without change. */
229 DECL_MODE (decl) = TYPE_MODE (type);
230 TREE_UNSIGNED (decl) = TREE_UNSIGNED (type);
231 if (DECL_SIZE (decl) == 0)
232 DECL_SIZE (decl) = TYPE_SIZE (type);
234 if (code == FIELD_DECL && DECL_BIT_FIELD (decl))
236 if (spec_size == 0 && DECL_NAME (decl) != 0)
239 /* Size is specified number of bits. */
240 DECL_SIZE (decl) = size_int (spec_size);
242 /* Force alignment required for the data type.
243 But if the decl itself wants greater alignment, don't override that.
244 Likewise, if the decl is packed, don't override it. */
245 else if (DECL_ALIGN (decl) == 0
246 || (! DECL_PACKED (decl) && TYPE_ALIGN (type) > DECL_ALIGN (decl)))
247 DECL_ALIGN (decl) = TYPE_ALIGN (type);
249 /* See if we can use an ordinary integer mode for a bit-field. */
250 /* Conditions are: a fixed size that is correct for another mode
251 and occupying a complete byte or bytes on proper boundary. */
252 if (code == FIELD_DECL)
254 DECL_BIT_FIELD_TYPE (decl) = DECL_BIT_FIELD (decl) ? type : 0;
255 if (maximum_field_alignment != 0)
256 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), maximum_field_alignment);
257 else if (flag_pack_struct)
258 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), BITS_PER_UNIT);
261 if (DECL_BIT_FIELD (decl)
262 && TYPE_SIZE (type) != 0
263 && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
264 && GET_MODE_CLASS (TYPE_MODE (type)) == MODE_INT)
266 register enum machine_mode xmode
267 = mode_for_size (TREE_INT_CST_LOW (DECL_SIZE (decl)), MODE_INT, 1);
270 && known_align % GET_MODE_ALIGNMENT (xmode) == 0)
272 DECL_ALIGN (decl) = MAX (GET_MODE_ALIGNMENT (xmode),
274 DECL_MODE (decl) = xmode;
275 DECL_SIZE (decl) = size_int (GET_MODE_BITSIZE (xmode));
276 /* This no longer needs to be accessed as a bit field. */
277 DECL_BIT_FIELD (decl) = 0;
281 /* Evaluate nonconstant size only once, either now or as soon as safe. */
282 if (DECL_SIZE (decl) != 0 && TREE_CODE (DECL_SIZE (decl)) != INTEGER_CST)
283 DECL_SIZE (decl) = variable_size (DECL_SIZE (decl));
286 /* Lay out a RECORD_TYPE type (a C struct).
287 This means laying out the fields, determining their positions,
288 and computing the overall size and required alignment of the record.
289 Note that if you set the TYPE_ALIGN before calling this
290 then the struct is aligned to at least that boundary.
292 If the type has basetypes, you must call layout_basetypes
293 before calling this function.
295 The return value is a list of static members of the record.
296 They still need to be laid out. */
303 #ifdef STRUCTURE_SIZE_BOUNDARY
304 unsigned record_align = MAX (STRUCTURE_SIZE_BOUNDARY, TYPE_ALIGN (rec));
306 unsigned record_align = MAX (BITS_PER_UNIT, TYPE_ALIGN (rec));
308 /* These must be laid out *after* the record is. */
309 tree pending_statics = NULL_TREE;
310 /* Record size so far is CONST_SIZE + VAR_SIZE bits,
311 where CONST_SIZE is an integer
312 and VAR_SIZE is a tree expression.
313 If VAR_SIZE is null, the size is just CONST_SIZE.
314 Naturally we try to avoid using VAR_SIZE. */
315 register int const_size = 0;
316 register tree var_size = 0;
317 /* Once we start using VAR_SIZE, this is the maximum alignment
318 that we know VAR_SIZE has. */
319 register int var_align = BITS_PER_UNIT;
322 for (field = TYPE_FIELDS (rec); field; field = TREE_CHAIN (field))
324 register int known_align = var_size ? var_align : const_size;
325 register int desired_align;
327 /* If FIELD is static, then treat it like a separate variable,
328 not really like a structure field.
329 If it is a FUNCTION_DECL, it's a method.
330 In both cases, all we do is lay out the decl,
331 and we do it *after* the record is laid out. */
333 if (TREE_STATIC (field))
335 pending_statics = tree_cons (NULL_TREE, field, pending_statics);
338 /* Enumerators and enum types which are local to this class need not
339 be laid out. Likewise for initialized constant fields. */
340 if (TREE_CODE (field) != FIELD_DECL)
343 /* Lay out the field so we know what alignment it needs.
344 For a packed field, use the alignment as specified,
345 disregarding what the type would want. */
346 if (DECL_PACKED (field))
347 desired_align = DECL_ALIGN (field);
348 layout_decl (field, known_align);
349 if (! DECL_PACKED (field))
350 desired_align = DECL_ALIGN (field);
351 /* Some targets (i.e. VMS) limit struct field alignment
352 to a lower boundary than alignment of variables. */
353 #ifdef BIGGEST_FIELD_ALIGNMENT
354 desired_align = MIN (desired_align, BIGGEST_FIELD_ALIGNMENT);
356 #ifdef ADJUST_FIELD_ALIGN
357 desired_align = ADJUST_FIELD_ALIGN (field, desired_align);
360 /* Record must have at least as much alignment as any field.
361 Otherwise, the alignment of the field within the record
364 #ifndef PCC_BITFIELD_TYPE_MATTERS
365 record_align = MAX (record_align, desired_align);
367 if (PCC_BITFIELD_TYPE_MATTERS && TREE_TYPE (field) != error_mark_node
368 && DECL_BIT_FIELD_TYPE (field)
369 && ! integer_zerop (TYPE_SIZE (TREE_TYPE (field))))
371 /* For these machines, a zero-length field does not
372 affect the alignment of the structure as a whole.
373 It does, however, affect the alignment of the next field
374 within the structure. */
375 if (! integer_zerop (DECL_SIZE (field)))
376 record_align = MAX (record_align, desired_align);
377 else if (! DECL_PACKED (field))
378 desired_align = TYPE_ALIGN (TREE_TYPE (field));
379 /* A named bit field of declared type `int'
380 forces the entire structure to have `int' alignment. */
381 if (DECL_NAME (field) != 0)
383 int type_align = TYPE_ALIGN (TREE_TYPE (field));
384 if (maximum_field_alignment != 0)
385 type_align = MIN (type_align, maximum_field_alignment);
386 else if (flag_pack_struct)
387 type_align = MIN (type_align, BITS_PER_UNIT);
389 record_align = MAX (record_align, type_align);
393 record_align = MAX (record_align, desired_align);
396 /* Does this field automatically have alignment it needs
397 by virtue of the fields that precede it and the record's
400 if (const_size % desired_align != 0
401 || (var_align % desired_align != 0
404 /* No, we need to skip space before this field.
405 Bump the cumulative size to multiple of field alignment. */
408 || var_align % desired_align == 0)
410 = CEIL (const_size, desired_align) * desired_align;
414 var_size = size_binop (PLUS_EXPR, var_size,
415 size_int (const_size));
417 var_size = round_up (var_size, desired_align);
418 var_align = MIN (var_align, desired_align);
422 #ifdef PCC_BITFIELD_TYPE_MATTERS
423 if (PCC_BITFIELD_TYPE_MATTERS
424 && TREE_CODE (field) == FIELD_DECL
425 && TREE_TYPE (field) != error_mark_node
426 && DECL_BIT_FIELD_TYPE (field)
427 && !DECL_PACKED (field)
428 /* If #pragma pack is in effect, turn off this feature. */
429 && maximum_field_alignment == 0
431 && !integer_zerop (DECL_SIZE (field)))
433 int type_align = TYPE_ALIGN (TREE_TYPE (field));
434 register tree dsize = DECL_SIZE (field);
435 int field_size = TREE_INT_CST_LOW (dsize);
437 /* A bit field may not span the unit of alignment of its type.
438 Advance to next boundary if necessary. */
439 /* ??? There is some uncertainty here as to what
440 should be done if type_align is less than the width of the type.
441 That can happen because the width exceeds BIGGEST_ALIGNMENT
442 or because it exceeds maximum_field_alignment. */
443 if (const_size / type_align
444 != (const_size + (field_size % type_align) - 1) / type_align)
445 const_size = CEIL (const_size, type_align) * type_align;
449 /* No existing machine description uses this parameter.
450 So I have made it in this aspect identical to PCC_BITFIELD_TYPE_MATTERS. */
451 #ifdef BITFIELD_NBYTES_LIMITED
452 if (BITFIELD_NBYTES_LIMITED
453 && TREE_CODE (field) == FIELD_DECL
454 && TREE_TYPE (field) != error_mark_node
455 && DECL_BIT_FIELD_TYPE (field)
456 && !DECL_PACKED (field)
457 && !integer_zerop (DECL_SIZE (field)))
459 int type_align = TYPE_ALIGN (TREE_TYPE (field));
460 register tree dsize = DECL_SIZE (field);
461 int field_size = TREE_INT_CST_LOW (dsize);
463 if (maximum_field_alignment != 0)
464 type_align = MIN (type_align, maximum_field_alignment);
465 else if (flag_pack_struct)
466 type_align = MIN (type_align, BITS_PER_UNIT);
468 /* A bit field may not span the unit of alignment of its type.
469 Advance to next boundary if necessary. */
470 if (const_size / type_align
471 != (const_size + field_size - 1) / type_align)
472 const_size = CEIL (const_size, type_align) * type_align;
476 /* Size so far becomes the position of this field. */
478 if (var_size && const_size)
479 DECL_FIELD_BITPOS (field)
480 = size_binop (PLUS_EXPR, var_size, size_int (const_size));
482 DECL_FIELD_BITPOS (field) = var_size;
485 DECL_FIELD_BITPOS (field) = size_int (const_size);
487 /* If this field ended up more aligned than we thought it
488 would be (we approximate this by seeing if its position
489 changed), lay out the field again; perhaps we can use an
490 integral mode for it now. */
491 if (known_align != const_size)
492 layout_decl (field, const_size);
495 /* Now add size of this field to the size of the record. */
498 register tree dsize = DECL_SIZE (field);
500 /* This can happen when we have an invalid nested struct definition,
501 such as struct j { struct j { int i; } }. The error message is
502 printed in finish_struct. */
505 else if (TREE_CODE (dsize) == INTEGER_CST
506 && TREE_INT_CST_HIGH (dsize) == 0
507 && TREE_INT_CST_LOW (dsize) + const_size > const_size)
508 /* Use const_size if there's no overflow. */
509 const_size += TREE_INT_CST_LOW (dsize);
515 var_size = size_binop (PLUS_EXPR, var_size, dsize);
520 /* Work out the total size and alignment of the record
521 as one expression and store in the record type.
522 Round it up to a multiple of the record's alignment. */
526 TYPE_SIZE (rec) = size_int (const_size);
532 = size_binop (PLUS_EXPR, var_size, size_int (const_size));
533 TYPE_SIZE (rec) = var_size;
536 /* Determine the desired alignment. */
537 #ifdef ROUND_TYPE_ALIGN
538 TYPE_ALIGN (rec) = ROUND_TYPE_ALIGN (rec, TYPE_ALIGN (rec), record_align);
540 TYPE_ALIGN (rec) = MAX (TYPE_ALIGN (rec), record_align);
543 #ifdef ROUND_TYPE_SIZE
544 TYPE_SIZE (rec) = ROUND_TYPE_SIZE (rec, TYPE_SIZE (rec), TYPE_ALIGN (rec));
546 /* Round the size up to be a multiple of the required alignment */
547 TYPE_SIZE (rec) = round_up (TYPE_SIZE (rec), TYPE_ALIGN (rec));
550 return pending_statics;
553 /* Lay out a UNION_TYPE or QUAL_UNION_TYPE type.
554 Lay out all the fields, set their positions to zero,
555 and compute the size and alignment of the union (maximum of any field).
556 Note that if you set the TYPE_ALIGN before calling this
557 then the union align is aligned to at least that boundary. */
564 #ifdef STRUCTURE_SIZE_BOUNDARY
565 unsigned union_align = STRUCTURE_SIZE_BOUNDARY;
567 unsigned union_align = BITS_PER_UNIT;
570 /* The size of the union, based on the fields scanned so far,
571 is max (CONST_SIZE, VAR_SIZE).
572 VAR_SIZE may be null; then CONST_SIZE by itself is the size. */
573 register int const_size = 0;
574 register tree var_size = 0;
576 /* If this is a QUAL_UNION_TYPE, we want to process the fields in
577 the reverse order in building the COND_EXPR that denotes its
578 size. We reverse them again later. */
579 if (TREE_CODE (rec) == QUAL_UNION_TYPE)
580 TYPE_FIELDS (rec) = nreverse (TYPE_FIELDS (rec));
582 for (field = TYPE_FIELDS (rec); field; field = TREE_CHAIN (field))
584 /* Enums which are local to this class need not be laid out. */
585 if (TREE_CODE (field) == CONST_DECL || TREE_CODE (field) == TYPE_DECL)
588 layout_decl (field, 0);
589 DECL_FIELD_BITPOS (field) = size_int (0);
591 /* Union must be at least as aligned as any field requires. */
593 union_align = MAX (union_align, DECL_ALIGN (field));
595 #ifdef PCC_BITFIELD_TYPE_MATTERS
596 /* On the m88000, a bit field of declare type `int'
597 forces the entire union to have `int' alignment. */
598 if (PCC_BITFIELD_TYPE_MATTERS && DECL_BIT_FIELD_TYPE (field))
599 union_align = MAX (union_align, TYPE_ALIGN (TREE_TYPE (field)));
602 if (TREE_CODE (rec) == UNION_TYPE)
604 /* Set union_size to max (decl_size, union_size).
605 There are more and less general ways to do this.
606 Use only CONST_SIZE unless forced to use VAR_SIZE. */
608 if (TREE_CODE (DECL_SIZE (field)) == INTEGER_CST)
610 = MAX (const_size, TREE_INT_CST_LOW (DECL_SIZE (field)));
611 else if (var_size == 0)
612 var_size = DECL_SIZE (field);
614 var_size = size_binop (MAX_EXPR, var_size, DECL_SIZE (field));
616 else if (TREE_CODE (rec) == QUAL_UNION_TYPE)
617 var_size = fold (build (COND_EXPR, sizetype, DECL_QUALIFIER (field),
619 var_size ? var_size : integer_zero_node));
622 if (TREE_CODE (rec) == QUAL_UNION_TYPE)
623 TYPE_FIELDS (rec) = nreverse (TYPE_FIELDS (rec));
625 /* Determine the ultimate size of the union (in bytes). */
626 if (NULL == var_size)
627 TYPE_SIZE (rec) = size_int (CEIL (const_size, BITS_PER_UNIT)
629 else if (const_size == 0)
630 TYPE_SIZE (rec) = var_size;
632 TYPE_SIZE (rec) = size_binop (MAX_EXPR, var_size,
633 round_up (size_int (const_size),
636 /* Determine the desired alignment. */
637 #ifdef ROUND_TYPE_ALIGN
638 TYPE_ALIGN (rec) = ROUND_TYPE_ALIGN (rec, TYPE_ALIGN (rec), union_align);
640 TYPE_ALIGN (rec) = MAX (TYPE_ALIGN (rec), union_align);
643 #ifdef ROUND_TYPE_SIZE
644 TYPE_SIZE (rec) = ROUND_TYPE_SIZE (rec, TYPE_SIZE (rec), TYPE_ALIGN (rec));
646 /* Round the size up to be a multiple of the required alignment */
647 TYPE_SIZE (rec) = round_up (TYPE_SIZE (rec), TYPE_ALIGN (rec));
651 /* Calculate the mode, size, and alignment for TYPE.
652 For an array type, calculate the element separation as well.
653 Record TYPE on the chain of permanent or temporary types
654 so that dbxout will find out about it.
656 TYPE_SIZE of a type is nonzero if the type has been laid out already.
657 layout_type does nothing on such a type.
659 If the type is incomplete, its TYPE_SIZE remains zero. */
666 tree pending_statics;
671 /* Do nothing if type has been laid out before. */
672 if (TYPE_SIZE (type))
675 /* Make sure all nodes we allocate are not momentary;
676 they must last past the current statement. */
677 old = suspend_momentary ();
679 /* Put all our nodes into the same obstack as the type. Also,
680 make expressions saveable (this is a no-op for permanent types). */
682 push_obstacks (TYPE_OBSTACK (type), TYPE_OBSTACK (type));
683 saveable_allocation ();
685 switch (TREE_CODE (type))
688 /* This kind of type is the responsibility
689 of the language-specific code. */
695 if (TREE_CODE (TYPE_MIN_VALUE (type)) == INTEGER_CST
696 && tree_int_cst_sgn (TYPE_MIN_VALUE (type)) >= 0)
697 TREE_UNSIGNED (type) = 1;
699 TYPE_MODE (type) = smallest_mode_for_size (TYPE_PRECISION (type),
701 TYPE_SIZE (type) = size_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
705 TYPE_MODE (type) = mode_for_size (TYPE_PRECISION (type), MODE_FLOAT, 0);
706 TYPE_SIZE (type) = size_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
710 TREE_UNSIGNED (type) = TREE_UNSIGNED (TREE_TYPE (type));
712 = mode_for_size (2 * TYPE_PRECISION (TREE_TYPE (type)),
713 (TREE_CODE (TREE_TYPE (type)) == INTEGER_TYPE
714 ? MODE_COMPLEX_INT : MODE_COMPLEX_FLOAT),
716 TYPE_SIZE (type) = size_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
720 TYPE_SIZE (type) = size_zero_node;
721 TYPE_ALIGN (type) = 1;
722 TYPE_MODE (type) = VOIDmode;
726 TYPE_SIZE (type) = size_int (POINTER_SIZE);
727 TYPE_MODE (type) = ptr_mode;
732 TYPE_MODE (type) = mode_for_size (2 * POINTER_SIZE, MODE_INT, 0);
733 TYPE_SIZE (type) = size_int (2 * POINTER_SIZE);
738 TYPE_MODE (type) = ptr_mode;
739 TYPE_SIZE (type) = size_int (POINTER_SIZE);
740 TREE_UNSIGNED (type) = 1;
741 TYPE_PRECISION (type) = POINTER_SIZE;
746 register tree index = TYPE_DOMAIN (type);
747 register tree element = TREE_TYPE (type);
749 build_pointer_type (element);
751 /* We need to know both bounds in order to compute the size. */
752 if (index && TYPE_MAX_VALUE (index) && TYPE_MIN_VALUE (index)
753 && TYPE_SIZE (element))
755 tree ub = TYPE_MAX_VALUE (index);
756 tree lb = TYPE_MIN_VALUE (index);
759 /* If UB is max (lb - 1, x), remove the MAX_EXPR since the
760 test for negative below covers it. */
761 if (TREE_CODE (ub) == MAX_EXPR
762 && TREE_CODE (TREE_OPERAND (ub, 0)) == MINUS_EXPR
763 && integer_onep (TREE_OPERAND (TREE_OPERAND (ub, 0), 1))
764 && operand_equal_p (TREE_OPERAND (TREE_OPERAND (ub, 0), 0),
766 ub = TREE_OPERAND (ub, 1);
767 else if (TREE_CODE (ub) == MAX_EXPR
768 && TREE_CODE (TREE_OPERAND (ub, 1)) == MINUS_EXPR
769 && integer_onep (TREE_OPERAND (TREE_OPERAND (ub, 1), 1))
770 && operand_equal_p (TREE_OPERAND (TREE_OPERAND (ub, 1),
773 ub = TREE_OPERAND (ub, 0);
775 length = size_binop (PLUS_EXPR, size_one_node,
776 size_binop (MINUS_EXPR, ub, lb));
778 /* If neither bound is a constant and sizetype is signed, make
779 sure the size is never negative. We should really do this
780 if *either* bound is non-constant, but this is the best
781 compromise between C and Ada. */
782 if (! TREE_UNSIGNED (sizetype)
783 && TREE_CODE (TYPE_MIN_VALUE (index)) != INTEGER_CST
784 && TREE_CODE (TYPE_MAX_VALUE (index)) != INTEGER_CST)
785 length = size_binop (MAX_EXPR, length, size_zero_node);
787 TYPE_SIZE (type) = size_binop (MULT_EXPR, length,
788 TYPE_SIZE (element));
791 /* Now round the alignment and size,
792 using machine-dependent criteria if any. */
794 #ifdef ROUND_TYPE_ALIGN
796 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (element), BITS_PER_UNIT);
798 TYPE_ALIGN (type) = MAX (TYPE_ALIGN (element), BITS_PER_UNIT);
801 #ifdef ROUND_TYPE_SIZE
802 if (TYPE_SIZE (type) != 0)
804 = ROUND_TYPE_SIZE (type, TYPE_SIZE (type), TYPE_ALIGN (type));
807 TYPE_MODE (type) = BLKmode;
808 if (TYPE_SIZE (type) != 0
809 && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
810 /* BLKmode elements force BLKmode aggregate;
811 else extract/store fields may lose. */
812 && (TYPE_MODE (TREE_TYPE (type)) != BLKmode
813 || TYPE_NO_FORCE_BLK (TREE_TYPE (type))))
816 = mode_for_size (TREE_INT_CST_LOW (TYPE_SIZE (type)),
819 if (STRICT_ALIGNMENT && TYPE_ALIGN (type) < BIGGEST_ALIGNMENT
820 && TYPE_ALIGN (type) < TREE_INT_CST_LOW (TYPE_SIZE (type))
821 && TYPE_MODE (type) != BLKmode)
823 TYPE_NO_FORCE_BLK (type) = 1;
824 TYPE_MODE (type) = BLKmode;
831 pending_statics = layout_record (type);
832 TYPE_MODE (type) = BLKmode;
833 if (TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST)
836 /* A record which has any BLKmode members must itself be BLKmode;
837 it can't go in a register.
838 Unless the member is BLKmode only because it isn't aligned. */
839 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
843 if (TREE_CODE (field) != FIELD_DECL)
846 if (TYPE_MODE (TREE_TYPE (field)) == BLKmode
847 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field)))
850 if (TREE_CODE (DECL_FIELD_BITPOS (field)) != INTEGER_CST)
853 bitpos = TREE_INT_CST_LOW (DECL_FIELD_BITPOS (field));
855 /* Must be BLKmode if any field crosses a word boundary,
856 since extract_bit_field can't handle that in registers. */
857 if (bitpos / BITS_PER_WORD
858 != ((TREE_INT_CST_LOW (DECL_SIZE (field)) + bitpos - 1)
860 /* But there is no problem if the field is entire words. */
861 && TREE_INT_CST_LOW (DECL_SIZE (field)) % BITS_PER_WORD == 0)
866 = mode_for_size (TREE_INT_CST_LOW (TYPE_SIZE (type)),
869 /* If structure's known alignment is less than
870 what the scalar mode would need, and it matters,
871 then stick with BLKmode. */
873 && ! (TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT
874 || (TYPE_ALIGN (type)
875 >= TREE_INT_CST_LOW (TYPE_SIZE (type)))))
877 if (TYPE_MODE (type) != BLKmode)
878 /* If this is the only reason this type is BLKmode,
879 then don't force containing types to be BLKmode. */
880 TYPE_NO_FORCE_BLK (type) = 1;
881 TYPE_MODE (type) = BLKmode;
887 /* Lay out any static members. This is done now
888 because their type may use the record's type. */
889 while (pending_statics)
891 layout_decl (TREE_VALUE (pending_statics), 0);
892 pending_statics = TREE_CHAIN (pending_statics);
897 case QUAL_UNION_TYPE:
899 TYPE_MODE (type) = BLKmode;
900 if (TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
901 /* If structure's known alignment is less than
902 what the scalar mode would need, and it matters,
903 then stick with BLKmode. */
904 && (! STRICT_ALIGNMENT
905 || TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT
906 || TYPE_ALIGN (type) >= TREE_INT_CST_LOW (TYPE_SIZE (type))))
909 /* A union which has any BLKmode members must itself be BLKmode;
910 it can't go in a register.
911 Unless the member is BLKmode only because it isn't aligned. */
912 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
914 if (TREE_CODE (field) != FIELD_DECL)
917 if (TYPE_MODE (TREE_TYPE (field)) == BLKmode
918 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field)))
923 = mode_for_size (TREE_INT_CST_LOW (TYPE_SIZE (type)),
930 /* Pascal and Chill types */
931 case BOOLEAN_TYPE: /* store one byte/boolean for now. */
932 TYPE_MODE (type) = QImode;
933 TYPE_SIZE (type) = size_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
934 TYPE_PRECISION (type) = 1;
935 TYPE_ALIGN (type) = GET_MODE_ALIGNMENT (TYPE_MODE (type));
936 if (TREE_CODE (TYPE_MIN_VALUE (type)) == INTEGER_CST
937 && tree_int_cst_sgn (TYPE_MIN_VALUE (type)) >= 0)
938 TREE_UNSIGNED (type) = 1;
942 if (TREE_CODE (TYPE_MAX_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST
943 || TREE_CODE (TYPE_MIN_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST)
947 #ifndef SET_WORD_SIZE
948 #define SET_WORD_SIZE BITS_PER_WORD
950 int alignment = set_alignment ? set_alignment : SET_WORD_SIZE;
952 TREE_INT_CST_LOW (TYPE_MAX_VALUE (TYPE_DOMAIN (type)))
953 - TREE_INT_CST_LOW (TYPE_MIN_VALUE (TYPE_DOMAIN (type))) + 1;
955 = ((size_in_bits + alignment - 1) / alignment) * alignment;
956 if (rounded_size > alignment)
957 TYPE_MODE (type) = BLKmode;
959 TYPE_MODE (type) = mode_for_size (alignment, MODE_INT, 1);
960 TYPE_SIZE (type) = size_int (rounded_size);
961 TYPE_ALIGN (type) = alignment;
962 TYPE_PRECISION (type) = size_in_bits;
967 /* The size may vary in different languages, so the language front end
968 should fill in the size. */
969 TYPE_ALIGN (type) = BIGGEST_ALIGNMENT;
970 TYPE_MODE (type) = BLKmode;
977 /* Normally, use the alignment corresponding to the mode chosen.
978 However, where strict alignment is not required, avoid
979 over-aligning structures, since most compilers do not do this
982 if (TYPE_MODE (type) != BLKmode && TYPE_MODE (type) != VOIDmode
984 || (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE
985 && TREE_CODE (type) != QUAL_UNION_TYPE
986 && TREE_CODE (type) != ARRAY_TYPE)))
987 TYPE_ALIGN (type) = GET_MODE_ALIGNMENT (TYPE_MODE (type));
989 /* Evaluate nonconstant size only once, either now or as soon as safe. */
990 if (TYPE_SIZE (type) != 0 && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
991 TYPE_SIZE (type) = variable_size (TYPE_SIZE (type));
993 /* Also layout any other variants of the type. */
994 if (TYPE_NEXT_VARIANT (type)
995 || type != TYPE_MAIN_VARIANT (type))
998 /* Record layout info of this variant. */
999 tree size = TYPE_SIZE (type);
1000 int align = TYPE_ALIGN (type);
1001 enum machine_mode mode = TYPE_MODE (type);
1003 /* Copy it into all variants. */
1004 for (variant = TYPE_MAIN_VARIANT (type);
1006 variant = TYPE_NEXT_VARIANT (variant))
1008 TYPE_SIZE (variant) = size;
1009 TYPE_ALIGN (variant) = align;
1010 TYPE_MODE (variant) = mode;
1015 resume_momentary (old);
1018 /* Create and return a type for signed integers of PRECISION bits. */
1021 make_signed_type (precision)
1024 register tree type = make_node (INTEGER_TYPE);
1026 TYPE_PRECISION (type) = precision;
1028 /* Create the extreme values based on the number of bits. */
1030 TYPE_MIN_VALUE (type)
1031 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1032 ? 0 : (HOST_WIDE_INT) (-1) << (precision - 1)),
1033 (((HOST_WIDE_INT) (-1)
1034 << (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1035 ? precision - HOST_BITS_PER_WIDE_INT - 1
1037 TYPE_MAX_VALUE (type)
1038 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1039 ? -1 : ((HOST_WIDE_INT) 1 << (precision - 1)) - 1),
1040 (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1041 ? (((HOST_WIDE_INT) 1
1042 << (precision - HOST_BITS_PER_WIDE_INT - 1))) - 1
1045 /* Give this type's extreme values this type as their type. */
1047 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
1048 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
1050 /* The first type made with this or `make_unsigned_type'
1051 is the type for size values. */
1058 /* Lay out the type: set its alignment, size, etc. */
1065 /* Create and return a type for unsigned integers of PRECISION bits. */
1068 make_unsigned_type (precision)
1071 register tree type = make_node (INTEGER_TYPE);
1073 TYPE_PRECISION (type) = precision;
1075 /* The first type made with this or `make_signed_type'
1076 is the type for size values. */
1083 fixup_unsigned_type (type);
1087 /* Set the extreme values of TYPE based on its precision in bits,
1088 then lay it out. Used when make_signed_type won't do
1089 because the tree code is not INTEGER_TYPE.
1090 E.g. for Pascal, when the -fsigned-char option is given. */
1093 fixup_signed_type (type)
1096 register int precision = TYPE_PRECISION (type);
1098 TYPE_MIN_VALUE (type)
1099 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1100 ? 0 : (HOST_WIDE_INT) (-1) << (precision - 1)),
1101 (((HOST_WIDE_INT) (-1)
1102 << (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1103 ? precision - HOST_BITS_PER_WIDE_INT - 1
1105 TYPE_MAX_VALUE (type)
1106 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1107 ? -1 : ((HOST_WIDE_INT) 1 << (precision - 1)) - 1),
1108 (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1109 ? (((HOST_WIDE_INT) 1
1110 << (precision - HOST_BITS_PER_WIDE_INT - 1))) - 1
1113 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
1114 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
1116 /* Lay out the type: set its alignment, size, etc. */
1121 /* Set the extreme values of TYPE based on its precision in bits,
1122 then lay it out. This is used both in `make_unsigned_type'
1123 and for enumeral types. */
1126 fixup_unsigned_type (type)
1129 register int precision = TYPE_PRECISION (type);
1131 TYPE_MIN_VALUE (type) = build_int_2 (0, 0);
1132 TYPE_MAX_VALUE (type)
1133 = build_int_2 (precision - HOST_BITS_PER_WIDE_INT >= 0
1134 ? -1 : ((HOST_WIDE_INT) 1 << precision) - 1,
1135 precision - HOST_BITS_PER_WIDE_INT > 0
1136 ? ((unsigned HOST_WIDE_INT) ~0
1137 >> (HOST_BITS_PER_WIDE_INT
1138 - (precision - HOST_BITS_PER_WIDE_INT)))
1140 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
1141 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
1143 /* Lay out the type: set its alignment, size, etc. */
1148 /* Find the best machine mode to use when referencing a bit field of length
1149 BITSIZE bits starting at BITPOS.
1151 The underlying object is known to be aligned to a boundary of ALIGN bits.
1152 If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
1153 larger than LARGEST_MODE (usually SImode).
1155 If no mode meets all these conditions, we return VOIDmode. Otherwise, if
1156 VOLATILEP is true or SLOW_BYTE_ACCESS is false, we return the smallest
1157 mode meeting these conditions.
1159 Otherwise (VOLATILEP is false and SLOW_BYTE_ACCESS is true), we return
1160 the largest mode (but a mode no wider than UNITS_PER_WORD) that meets
1161 all the conditions. */
1164 get_best_mode (bitsize, bitpos, align, largest_mode, volatilep)
1165 int bitsize, bitpos;
1167 enum machine_mode largest_mode;
1170 enum machine_mode mode;
1173 /* Find the narrowest integer mode that contains the bit field. */
1174 for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
1175 mode = GET_MODE_WIDER_MODE (mode))
1177 unit = GET_MODE_BITSIZE (mode);
1178 if (bitpos / unit == (bitpos + bitsize - 1) / unit)
1182 if (mode == MAX_MACHINE_MODE
1183 /* It is tempting to omit the following line
1184 if STRICT_ALIGNMENT is true.
1185 But that is incorrect, since if the bitfield uses part of 3 bytes
1186 and we use a 4-byte mode, we could get a spurious segv
1187 if the extra 4th byte is past the end of memory.
1188 (Though at least one Unix compiler ignores this problem:
1189 that on the Sequent 386 machine. */
1190 || MIN (unit, BIGGEST_ALIGNMENT) > align
1191 || (largest_mode != VOIDmode && unit > GET_MODE_BITSIZE (largest_mode)))
1194 if (SLOW_BYTE_ACCESS && ! volatilep)
1196 enum machine_mode wide_mode = VOIDmode, tmode;
1198 for (tmode = GET_CLASS_NARROWEST_MODE (MODE_INT); tmode != VOIDmode;
1199 tmode = GET_MODE_WIDER_MODE (tmode))
1201 unit = GET_MODE_BITSIZE (tmode);
1202 if (bitpos / unit == (bitpos + bitsize - 1) / unit
1203 && unit <= BITS_PER_WORD
1204 && unit <= MIN (align, BIGGEST_ALIGNMENT)
1205 && (largest_mode == VOIDmode
1206 || unit <= GET_MODE_BITSIZE (largest_mode)))
1210 if (wide_mode != VOIDmode)
1217 /* Save all variables describing the current status into the structure *P.
1218 This is used before starting a nested function. */
1221 save_storage_status (p)
1224 #if 0 /* Need not save, since always 0 and non0 (resp.) within a function. */
1225 p->pending_sizes = pending_sizes;
1226 p->immediate_size_expand = immediate_size_expand;
1230 /* Restore all variables describing the current status from the structure *P.
1231 This is used after a nested function. */
1234 restore_storage_status (p)
1238 pending_sizes = p->pending_sizes;
1239 immediate_size_expand = p->immediate_size_expand;