1 /* C-compiler utilities for types and variables storage layout
2 Copyright (C) 1987, 88, 92-96, 1997 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. */
30 #define CEIL(x,y) (((x) + (y) - 1) / (y))
32 /* Data type for the expressions representing sizes of data types.
33 It is the first integer type laid out.
38 /* An integer constant with value 0 whose type is sizetype. */
42 /* An integer constant with value 1 whose type is sizetype. */
46 /* If nonzero, this is an upper limit on alignment of structure fields.
47 The value is measured in bits. */
48 int maximum_field_alignment;
50 /* If non-zero, the alignment of a bitstring or (power-)set value, in bits.
51 May be overridden by front-ends. */
52 int set_alignment = 0;
54 static enum machine_mode smallest_mode_for_size PROTO((unsigned int,
56 static tree layout_record PROTO((tree));
57 static void layout_union PROTO((tree));
59 /* SAVE_EXPRs for sizes of types and decls, waiting to be expanded. */
61 static tree pending_sizes;
63 /* Nonzero means cannot safely call expand_expr now,
64 so put variable sizes onto `pending_sizes' instead. */
66 int immediate_size_expand;
71 tree chain = pending_sizes;
74 /* Put each SAVE_EXPR into the current function. */
75 for (t = chain; t; t = TREE_CHAIN (t))
76 SAVE_EXPR_CONTEXT (TREE_VALUE (t)) = current_function_decl;
82 put_pending_sizes (chain)
88 pending_sizes = chain;
91 /* Given a size SIZE that may not be a constant, return a SAVE_EXPR
92 to serve as the actual size-expression for a type or decl. */
98 /* If the language-processor is to take responsibility for variable-sized
99 items (e.g., languages which have elaboration procedures like Ada),
100 just return SIZE unchanged. Likewise for self-referential sizes. */
101 if (TREE_CONSTANT (size)
102 || global_bindings_p () < 0 || contains_placeholder_p (size))
105 size = save_expr (size);
107 if (global_bindings_p ())
109 if (TREE_CONSTANT (size))
110 error ("type size can't be explicitly evaluated");
112 error ("variable-size type declared outside of any function");
117 if (immediate_size_expand)
118 /* NULL_RTX is not defined; neither is the rtx type.
119 Also, we would like to pass const0_rtx here, but don't have it. */
120 expand_expr (size, expand_expr (integer_zero_node, NULL_PTR, VOIDmode, 0),
123 pending_sizes = tree_cons (NULL_TREE, size, pending_sizes);
128 #ifndef MAX_FIXED_MODE_SIZE
129 #define MAX_FIXED_MODE_SIZE GET_MODE_BITSIZE (DImode)
132 /* Return the machine mode to use for a nonscalar of SIZE bits.
133 The mode must be in class CLASS, and have exactly that many bits.
134 If LIMIT is nonzero, modes of wider than MAX_FIXED_MODE_SIZE will not
138 mode_for_size (size, class, limit)
140 enum mode_class class;
143 register enum machine_mode mode;
145 if (limit && size > MAX_FIXED_MODE_SIZE)
148 /* Get the first mode which has this size, in the specified class. */
149 for (mode = GET_CLASS_NARROWEST_MODE (class); mode != VOIDmode;
150 mode = GET_MODE_WIDER_MODE (mode))
151 if (GET_MODE_BITSIZE (mode) == size)
157 /* Similar, but never return BLKmode; return the narrowest mode that
158 contains at least the requested number of bits. */
160 static enum machine_mode
161 smallest_mode_for_size (size, class)
163 enum mode_class class;
165 register enum machine_mode mode;
167 /* Get the first mode which has at least this size, in the
169 for (mode = GET_CLASS_NARROWEST_MODE (class); mode != VOIDmode;
170 mode = GET_MODE_WIDER_MODE (mode))
171 if (GET_MODE_BITSIZE (mode) >= size)
177 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
180 round_up (value, divisor)
184 return size_binop (MULT_EXPR,
185 size_binop (CEIL_DIV_EXPR, value, size_int (divisor)),
189 /* Set the size, mode and alignment of a ..._DECL node.
190 TYPE_DECL does need this for C++.
191 Note that LABEL_DECL and CONST_DECL nodes do not need this,
192 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
193 Don't call layout_decl for them.
195 KNOWN_ALIGN is the amount of alignment we can assume this
196 decl has with no special effort. It is relevant only for FIELD_DECLs
197 and depends on the previous fields.
198 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
199 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
200 the record will be aligned to suit. */
203 layout_decl (decl, known_align)
205 unsigned known_align;
207 register tree type = TREE_TYPE (decl);
208 register enum tree_code code = TREE_CODE (decl);
209 int spec_size = DECL_FIELD_SIZE (decl);
211 if (code == CONST_DECL)
214 if (code != VAR_DECL && code != PARM_DECL && code != RESULT_DECL
215 && code != FIELD_DECL && code != TYPE_DECL)
218 if (type == error_mark_node)
220 type = void_type_node;
224 /* Usually the size and mode come from the data type without change. */
226 DECL_MODE (decl) = TYPE_MODE (type);
227 TREE_UNSIGNED (decl) = TREE_UNSIGNED (type);
228 if (DECL_SIZE (decl) == 0)
229 DECL_SIZE (decl) = TYPE_SIZE (type);
231 if (code == FIELD_DECL && DECL_BIT_FIELD (decl))
233 if (spec_size == 0 && DECL_NAME (decl) != 0)
236 /* Size is specified number of bits. */
237 DECL_SIZE (decl) = size_int (spec_size);
239 /* Force alignment required for the data type.
240 But if the decl itself wants greater alignment, don't override that.
241 Likewise, if the decl is packed, don't override it. */
242 else if (DECL_ALIGN (decl) == 0
243 || (! DECL_PACKED (decl) && TYPE_ALIGN (type) > DECL_ALIGN (decl)))
244 DECL_ALIGN (decl) = TYPE_ALIGN (type);
246 /* See if we can use an ordinary integer mode for a bit-field. */
247 /* Conditions are: a fixed size that is correct for another mode
248 and occupying a complete byte or bytes on proper boundary. */
249 if (code == FIELD_DECL)
251 DECL_BIT_FIELD_TYPE (decl) = DECL_BIT_FIELD (decl) ? type : 0;
252 if (maximum_field_alignment != 0)
253 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), maximum_field_alignment);
254 else if (DECL_PACKED (decl))
255 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), BITS_PER_UNIT);
258 if (DECL_BIT_FIELD (decl)
259 && TYPE_SIZE (type) != 0
260 && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
261 && GET_MODE_CLASS (TYPE_MODE (type)) == MODE_INT)
263 register enum machine_mode xmode
264 = mode_for_size (TREE_INT_CST_LOW (DECL_SIZE (decl)), MODE_INT, 1);
267 && known_align % GET_MODE_ALIGNMENT (xmode) == 0)
269 DECL_ALIGN (decl) = MAX (GET_MODE_ALIGNMENT (xmode),
271 DECL_MODE (decl) = xmode;
272 DECL_SIZE (decl) = size_int (GET_MODE_BITSIZE (xmode));
273 /* This no longer needs to be accessed as a bit field. */
274 DECL_BIT_FIELD (decl) = 0;
278 /* Turn off DECL_BIT_FIELD if we won't need it set. */
279 if (DECL_BIT_FIELD (decl) && TYPE_MODE (type) == BLKmode
280 && known_align % TYPE_ALIGN (type) == 0
281 && DECL_SIZE (decl) != 0
282 && (TREE_CODE (DECL_SIZE (decl)) != INTEGER_CST
283 || (TREE_INT_CST_LOW (DECL_SIZE (decl)) % BITS_PER_UNIT) == 0)
284 && DECL_ALIGN (decl) >= TYPE_ALIGN (type))
285 DECL_BIT_FIELD (decl) = 0;
287 /* Evaluate nonconstant size only once, either now or as soon as safe. */
288 if (DECL_SIZE (decl) != 0 && TREE_CODE (DECL_SIZE (decl)) != INTEGER_CST)
289 DECL_SIZE (decl) = variable_size (DECL_SIZE (decl));
292 /* Lay out a RECORD_TYPE type (a C struct).
293 This means laying out the fields, determining their positions,
294 and computing the overall size and required alignment of the record.
295 Note that if you set the TYPE_ALIGN before calling this
296 then the struct is aligned to at least that boundary.
298 If the type has basetypes, you must call layout_basetypes
299 before calling this function.
301 The return value is a list of static members of the record.
302 They still need to be laid out. */
309 #ifdef STRUCTURE_SIZE_BOUNDARY
310 unsigned record_align = MAX (STRUCTURE_SIZE_BOUNDARY, TYPE_ALIGN (rec));
312 unsigned record_align = MAX (BITS_PER_UNIT, TYPE_ALIGN (rec));
314 /* These must be laid out *after* the record is. */
315 tree pending_statics = NULL_TREE;
316 /* Record size so far is CONST_SIZE + VAR_SIZE bits,
317 where CONST_SIZE is an integer
318 and VAR_SIZE is a tree expression.
319 If VAR_SIZE is null, the size is just CONST_SIZE.
320 Naturally we try to avoid using VAR_SIZE. */
321 register HOST_WIDE_INT const_size = 0;
322 register tree var_size = 0;
323 /* Once we start using VAR_SIZE, this is the maximum alignment
324 that we know VAR_SIZE has. */
325 register int var_align = BITS_PER_UNIT;
328 for (field = TYPE_FIELDS (rec); field; field = TREE_CHAIN (field))
330 register int known_align = var_size ? var_align : const_size;
331 register int desired_align;
333 /* If FIELD is static, then treat it like a separate variable,
334 not really like a structure field.
335 If it is a FUNCTION_DECL, it's a method.
336 In both cases, all we do is lay out the decl,
337 and we do it *after* the record is laid out. */
339 if (TREE_CODE (field) == VAR_DECL)
341 pending_statics = tree_cons (NULL_TREE, field, pending_statics);
344 /* Enumerators and enum types which are local to this class need not
345 be laid out. Likewise for initialized constant fields. */
346 if (TREE_CODE (field) != FIELD_DECL)
349 /* Lay out the field so we know what alignment it needs.
350 For a packed field, use the alignment as specified,
351 disregarding what the type would want. */
352 if (DECL_PACKED (field))
353 desired_align = DECL_ALIGN (field);
354 layout_decl (field, known_align);
355 if (! DECL_PACKED (field))
356 desired_align = DECL_ALIGN (field);
357 /* Some targets (i.e. VMS) limit struct field alignment
358 to a lower boundary than alignment of variables. */
359 #ifdef BIGGEST_FIELD_ALIGNMENT
360 desired_align = MIN (desired_align, BIGGEST_FIELD_ALIGNMENT);
362 #ifdef ADJUST_FIELD_ALIGN
363 desired_align = ADJUST_FIELD_ALIGN (field, desired_align);
366 /* Record must have at least as much alignment as any field.
367 Otherwise, the alignment of the field within the record
370 #ifndef PCC_BITFIELD_TYPE_MATTERS
371 record_align = MAX (record_align, desired_align);
373 if (PCC_BITFIELD_TYPE_MATTERS && TREE_TYPE (field) != error_mark_node
374 && DECL_BIT_FIELD_TYPE (field)
375 && ! integer_zerop (TYPE_SIZE (TREE_TYPE (field))))
377 /* For these machines, a zero-length field does not
378 affect the alignment of the structure as a whole.
379 It does, however, affect the alignment of the next field
380 within the structure. */
381 if (! integer_zerop (DECL_SIZE (field)))
382 record_align = MAX (record_align, desired_align);
383 else if (! DECL_PACKED (field))
384 desired_align = TYPE_ALIGN (TREE_TYPE (field));
385 /* A named bit field of declared type `int'
386 forces the entire structure to have `int' alignment. */
387 if (DECL_NAME (field) != 0)
389 int type_align = TYPE_ALIGN (TREE_TYPE (field));
390 if (maximum_field_alignment != 0)
391 type_align = MIN (type_align, maximum_field_alignment);
392 else if (TYPE_PACKED (rec))
393 type_align = MIN (type_align, BITS_PER_UNIT);
395 record_align = MAX (record_align, type_align);
399 record_align = MAX (record_align, desired_align);
402 /* Does this field automatically have alignment it needs
403 by virtue of the fields that precede it and the record's
406 if (const_size % desired_align != 0
407 || (var_align % desired_align != 0
410 /* No, we need to skip space before this field.
411 Bump the cumulative size to multiple of field alignment. */
414 || var_align % desired_align == 0)
416 = CEIL (const_size, desired_align) * desired_align;
420 var_size = size_binop (PLUS_EXPR, var_size,
421 size_int (const_size));
423 var_size = round_up (var_size, desired_align);
424 var_align = MIN (var_align, desired_align);
428 #ifdef PCC_BITFIELD_TYPE_MATTERS
429 if (PCC_BITFIELD_TYPE_MATTERS
430 && TREE_CODE (field) == FIELD_DECL
431 && TREE_TYPE (field) != error_mark_node
432 && DECL_BIT_FIELD_TYPE (field)
433 && !DECL_PACKED (field)
434 && maximum_field_alignment == 0
435 && !integer_zerop (DECL_SIZE (field)))
437 int type_align = TYPE_ALIGN (TREE_TYPE (field));
438 register tree dsize = DECL_SIZE (field);
439 int field_size = TREE_INT_CST_LOW (dsize);
441 /* A bit field may not span more units of alignment of its type
442 than its type itself. Advance to next boundary if necessary. */
443 if (((const_size + field_size) / type_align - const_size / type_align)
444 > TREE_INT_CST_LOW (TYPE_SIZE (TREE_TYPE (field))) / 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 (TYPE_PACKED (rec))
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_CONSTANT_OVERFLOW (dsize)
507 && TREE_INT_CST_HIGH (dsize) == 0
508 && TREE_INT_CST_LOW (dsize) + const_size >= const_size)
509 /* Use const_size if there's no overflow. */
510 const_size += TREE_INT_CST_LOW (dsize);
516 var_size = size_binop (PLUS_EXPR, var_size, dsize);
521 /* Work out the total size and alignment of the record
522 as one expression and store in the record type.
523 Round it up to a multiple of the record's alignment. */
527 TYPE_SIZE (rec) = size_int (const_size);
533 = size_binop (PLUS_EXPR, var_size, size_int (const_size));
534 TYPE_SIZE (rec) = var_size;
537 /* Determine the desired alignment. */
538 #ifdef ROUND_TYPE_ALIGN
539 TYPE_ALIGN (rec) = ROUND_TYPE_ALIGN (rec, TYPE_ALIGN (rec), record_align);
541 TYPE_ALIGN (rec) = MAX (TYPE_ALIGN (rec), record_align);
544 #ifdef ROUND_TYPE_SIZE
545 TYPE_SIZE (rec) = ROUND_TYPE_SIZE (rec, TYPE_SIZE (rec), TYPE_ALIGN (rec));
547 /* Round the size up to be a multiple of the required alignment */
548 TYPE_SIZE (rec) = round_up (TYPE_SIZE (rec), TYPE_ALIGN (rec));
551 return pending_statics;
554 /* Lay out a UNION_TYPE or QUAL_UNION_TYPE type.
555 Lay out all the fields, set their positions to zero,
556 and compute the size and alignment of the union (maximum of any field).
557 Note that if you set the TYPE_ALIGN before calling this
558 then the union align is aligned to at least that boundary. */
565 #ifdef STRUCTURE_SIZE_BOUNDARY
566 unsigned union_align = STRUCTURE_SIZE_BOUNDARY;
568 unsigned union_align = BITS_PER_UNIT;
571 /* The size of the union, based on the fields scanned so far,
572 is max (CONST_SIZE, VAR_SIZE).
573 VAR_SIZE may be null; then CONST_SIZE by itself is the size. */
574 register int const_size = 0;
575 register tree var_size = 0;
577 /* If this is a QUAL_UNION_TYPE, we want to process the fields in
578 the reverse order in building the COND_EXPR that denotes its
579 size. We reverse them again later. */
580 if (TREE_CODE (rec) == QUAL_UNION_TYPE)
581 TYPE_FIELDS (rec) = nreverse (TYPE_FIELDS (rec));
583 for (field = TYPE_FIELDS (rec); field; field = TREE_CHAIN (field))
585 /* Enums which are local to this class need not be laid out. */
586 if (TREE_CODE (field) == CONST_DECL || TREE_CODE (field) == TYPE_DECL)
589 layout_decl (field, 0);
590 DECL_FIELD_BITPOS (field) = size_int (0);
592 /* Union must be at least as aligned as any field requires. */
594 union_align = MAX (union_align, DECL_ALIGN (field));
596 #ifdef PCC_BITFIELD_TYPE_MATTERS
597 /* On the m88000, a bit field of declare type `int'
598 forces the entire union to have `int' alignment. */
599 if (PCC_BITFIELD_TYPE_MATTERS && DECL_BIT_FIELD_TYPE (field))
600 union_align = MAX (union_align, TYPE_ALIGN (TREE_TYPE (field)));
603 if (TREE_CODE (rec) == UNION_TYPE)
605 /* Set union_size to max (decl_size, union_size).
606 There are more and less general ways to do this.
607 Use only CONST_SIZE unless forced to use VAR_SIZE. */
609 if (TREE_CODE (DECL_SIZE (field)) == INTEGER_CST)
611 = MAX (const_size, TREE_INT_CST_LOW (DECL_SIZE (field)));
612 else if (var_size == 0)
613 var_size = DECL_SIZE (field);
615 var_size = size_binop (MAX_EXPR, var_size, DECL_SIZE (field));
617 else if (TREE_CODE (rec) == QUAL_UNION_TYPE)
618 var_size = fold (build (COND_EXPR, sizetype, DECL_QUALIFIER (field),
620 var_size ? var_size : integer_zero_node));
623 if (TREE_CODE (rec) == QUAL_UNION_TYPE)
624 TYPE_FIELDS (rec) = nreverse (TYPE_FIELDS (rec));
626 /* Determine the ultimate size of the union (in bytes). */
627 if (NULL == var_size)
628 TYPE_SIZE (rec) = size_int (CEIL (const_size, BITS_PER_UNIT)
630 else if (const_size == 0)
631 TYPE_SIZE (rec) = var_size;
633 TYPE_SIZE (rec) = size_binop (MAX_EXPR, var_size,
634 round_up (size_int (const_size),
637 /* Determine the desired alignment. */
638 #ifdef ROUND_TYPE_ALIGN
639 TYPE_ALIGN (rec) = ROUND_TYPE_ALIGN (rec, TYPE_ALIGN (rec), union_align);
641 TYPE_ALIGN (rec) = MAX (TYPE_ALIGN (rec), union_align);
644 #ifdef ROUND_TYPE_SIZE
645 TYPE_SIZE (rec) = ROUND_TYPE_SIZE (rec, TYPE_SIZE (rec), TYPE_ALIGN (rec));
647 /* Round the size up to be a multiple of the required alignment */
648 TYPE_SIZE (rec) = round_up (TYPE_SIZE (rec), TYPE_ALIGN (rec));
652 /* Calculate the mode, size, and alignment for TYPE.
653 For an array type, calculate the element separation as well.
654 Record TYPE on the chain of permanent or temporary types
655 so that dbxout will find out about it.
657 TYPE_SIZE of a type is nonzero if the type has been laid out already.
658 layout_type does nothing on such a type.
660 If the type is incomplete, its TYPE_SIZE remains zero. */
667 tree pending_statics;
672 /* Do nothing if type has been laid out before. */
673 if (TYPE_SIZE (type))
676 /* Make sure all nodes we allocate are not momentary;
677 they must last past the current statement. */
678 old = suspend_momentary ();
680 /* Put all our nodes into the same obstack as the type. Also,
681 make expressions saveable (this is a no-op for permanent types). */
683 push_obstacks (TYPE_OBSTACK (type), TYPE_OBSTACK (type));
684 saveable_allocation ();
686 switch (TREE_CODE (type))
689 /* This kind of type is the responsibility
690 of the language-specific code. */
696 if (TREE_CODE (TYPE_MIN_VALUE (type)) == INTEGER_CST
697 && tree_int_cst_sgn (TYPE_MIN_VALUE (type)) >= 0)
698 TREE_UNSIGNED (type) = 1;
700 TYPE_MODE (type) = smallest_mode_for_size (TYPE_PRECISION (type),
702 TYPE_SIZE (type) = size_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
706 TYPE_MODE (type) = mode_for_size (TYPE_PRECISION (type), MODE_FLOAT, 0);
707 TYPE_SIZE (type) = size_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
711 TREE_UNSIGNED (type) = TREE_UNSIGNED (TREE_TYPE (type));
713 = mode_for_size (2 * TYPE_PRECISION (TREE_TYPE (type)),
714 (TREE_CODE (TREE_TYPE (type)) == INTEGER_TYPE
715 ? MODE_COMPLEX_INT : MODE_COMPLEX_FLOAT),
717 TYPE_SIZE (type) = size_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
721 TYPE_SIZE (type) = size_zero_node;
722 TYPE_ALIGN (type) = 1;
723 TYPE_MODE (type) = VOIDmode;
727 TYPE_SIZE (type) = size_int (POINTER_SIZE);
728 TYPE_MODE (type) = ptr_mode;
733 TYPE_MODE (type) = mode_for_size (2 * POINTER_SIZE, MODE_INT, 0);
734 TYPE_SIZE (type) = size_int (2 * POINTER_SIZE);
739 TYPE_MODE (type) = ptr_mode;
740 TYPE_SIZE (type) = size_int (POINTER_SIZE);
741 TREE_UNSIGNED (type) = 1;
742 TYPE_PRECISION (type) = POINTER_SIZE;
747 register tree index = TYPE_DOMAIN (type);
748 register tree element = TREE_TYPE (type);
750 build_pointer_type (element);
752 /* We need to know both bounds in order to compute the size. */
753 if (index && TYPE_MAX_VALUE (index) && TYPE_MIN_VALUE (index)
754 && TYPE_SIZE (element))
756 tree ub = TYPE_MAX_VALUE (index);
757 tree lb = TYPE_MIN_VALUE (index);
760 /* If UB is max (lb - 1, x), remove the MAX_EXPR since the
761 test for negative below covers it. */
762 if (TREE_CODE (ub) == MAX_EXPR
763 && TREE_CODE (TREE_OPERAND (ub, 0)) == MINUS_EXPR
764 && integer_onep (TREE_OPERAND (TREE_OPERAND (ub, 0), 1))
765 && operand_equal_p (TREE_OPERAND (TREE_OPERAND (ub, 0), 0),
767 ub = TREE_OPERAND (ub, 1);
768 else if (TREE_CODE (ub) == MAX_EXPR
769 && TREE_CODE (TREE_OPERAND (ub, 1)) == MINUS_EXPR
770 && integer_onep (TREE_OPERAND (TREE_OPERAND (ub, 1), 1))
771 && operand_equal_p (TREE_OPERAND (TREE_OPERAND (ub, 1),
774 ub = TREE_OPERAND (ub, 0);
776 length = size_binop (PLUS_EXPR, size_one_node,
777 size_binop (MINUS_EXPR, ub, lb));
779 /* If neither bound is a constant and sizetype is signed, make
780 sure the size is never negative. We should really do this
781 if *either* bound is non-constant, but this is the best
782 compromise between C and Ada. */
783 if (! TREE_UNSIGNED (sizetype)
784 && TREE_CODE (TYPE_MIN_VALUE (index)) != INTEGER_CST
785 && TREE_CODE (TYPE_MAX_VALUE (index)) != INTEGER_CST)
786 length = size_binop (MAX_EXPR, length, size_zero_node);
788 TYPE_SIZE (type) = size_binop (MULT_EXPR, length,
789 TYPE_SIZE (element));
792 /* Now round the alignment and size,
793 using machine-dependent criteria if any. */
795 #ifdef ROUND_TYPE_ALIGN
797 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (element), BITS_PER_UNIT);
799 TYPE_ALIGN (type) = MAX (TYPE_ALIGN (element), BITS_PER_UNIT);
802 #ifdef ROUND_TYPE_SIZE
803 if (TYPE_SIZE (type) != 0)
805 = ROUND_TYPE_SIZE (type, TYPE_SIZE (type), TYPE_ALIGN (type));
808 TYPE_MODE (type) = BLKmode;
809 if (TYPE_SIZE (type) != 0
810 && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
811 /* BLKmode elements force BLKmode aggregate;
812 else extract/store fields may lose. */
813 && (TYPE_MODE (TREE_TYPE (type)) != BLKmode
814 || TYPE_NO_FORCE_BLK (TREE_TYPE (type))))
817 = mode_for_size (TREE_INT_CST_LOW (TYPE_SIZE (type)),
820 if (STRICT_ALIGNMENT && TYPE_ALIGN (type) < BIGGEST_ALIGNMENT
821 && TYPE_ALIGN (type) < TREE_INT_CST_LOW (TYPE_SIZE (type))
822 && TYPE_MODE (type) != BLKmode)
824 TYPE_NO_FORCE_BLK (type) = 1;
825 TYPE_MODE (type) = BLKmode;
832 pending_statics = layout_record (type);
833 TYPE_MODE (type) = BLKmode;
834 if (TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST)
837 /* A record which has any BLKmode members must itself be BLKmode;
838 it can't go in a register.
839 Unless the member is BLKmode only because it isn't aligned. */
840 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
844 if (TREE_CODE (field) != FIELD_DECL)
847 if (TYPE_MODE (TREE_TYPE (field)) == BLKmode
848 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field)))
851 if (TREE_CODE (DECL_FIELD_BITPOS (field)) != INTEGER_CST)
854 bitpos = TREE_INT_CST_LOW (DECL_FIELD_BITPOS (field));
856 /* Must be BLKmode if any field crosses a word boundary,
857 since extract_bit_field can't handle that in registers. */
858 if (bitpos / BITS_PER_WORD
859 != ((TREE_INT_CST_LOW (DECL_SIZE (field)) + bitpos - 1)
861 /* But there is no problem if the field is entire words. */
862 && TREE_INT_CST_LOW (DECL_SIZE (field)) % BITS_PER_WORD == 0)
867 = mode_for_size (TREE_INT_CST_LOW (TYPE_SIZE (type)),
870 /* If structure's known alignment is less than
871 what the scalar mode would need, and it matters,
872 then stick with BLKmode. */
874 && ! (TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT
875 || (TYPE_ALIGN (type)
876 >= TREE_INT_CST_LOW (TYPE_SIZE (type)))))
878 if (TYPE_MODE (type) != BLKmode)
879 /* If this is the only reason this type is BLKmode,
880 then don't force containing types to be BLKmode. */
881 TYPE_NO_FORCE_BLK (type) = 1;
882 TYPE_MODE (type) = BLKmode;
888 /* Lay out any static members. This is done now
889 because their type may use the record's type. */
890 while (pending_statics)
892 layout_decl (TREE_VALUE (pending_statics), 0);
893 pending_statics = TREE_CHAIN (pending_statics);
898 case QUAL_UNION_TYPE:
900 TYPE_MODE (type) = BLKmode;
901 if (TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
902 /* If structure's known alignment is less than
903 what the scalar mode would need, and it matters,
904 then stick with BLKmode. */
905 && (! STRICT_ALIGNMENT
906 || TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT
907 || TYPE_ALIGN (type) >= TREE_INT_CST_LOW (TYPE_SIZE (type))))
910 /* A union which has any BLKmode members must itself be BLKmode;
911 it can't go in a register.
912 Unless the member is BLKmode only because it isn't aligned. */
913 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
915 if (TREE_CODE (field) != FIELD_DECL)
918 if (TYPE_MODE (TREE_TYPE (field)) == BLKmode
919 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field)))
924 = mode_for_size (TREE_INT_CST_LOW (TYPE_SIZE (type)),
931 /* Pascal and Chill types */
932 case BOOLEAN_TYPE: /* store one byte/boolean for now. */
933 TYPE_MODE (type) = QImode;
934 TYPE_SIZE (type) = size_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
935 TYPE_PRECISION (type) = 1;
936 TYPE_ALIGN (type) = GET_MODE_ALIGNMENT (TYPE_MODE (type));
937 if (TREE_CODE (TYPE_MIN_VALUE (type)) == INTEGER_CST
938 && tree_int_cst_sgn (TYPE_MIN_VALUE (type)) >= 0)
939 TREE_UNSIGNED (type) = 1;
943 if (TREE_CODE (TYPE_MAX_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST
944 || TREE_CODE (TYPE_MIN_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST)
948 #ifndef SET_WORD_SIZE
949 #define SET_WORD_SIZE BITS_PER_WORD
951 int alignment = set_alignment ? set_alignment : SET_WORD_SIZE;
953 TREE_INT_CST_LOW (TYPE_MAX_VALUE (TYPE_DOMAIN (type)))
954 - TREE_INT_CST_LOW (TYPE_MIN_VALUE (TYPE_DOMAIN (type))) + 1;
956 = ((size_in_bits + alignment - 1) / alignment) * alignment;
957 if (rounded_size > alignment)
958 TYPE_MODE (type) = BLKmode;
960 TYPE_MODE (type) = mode_for_size (alignment, MODE_INT, 1);
961 TYPE_SIZE (type) = size_int (rounded_size);
962 TYPE_ALIGN (type) = alignment;
963 TYPE_PRECISION (type) = size_in_bits;
968 /* The size may vary in different languages, so the language front end
969 should fill in the size. */
970 TYPE_ALIGN (type) = BIGGEST_ALIGNMENT;
971 TYPE_MODE (type) = BLKmode;
978 /* Normally, use the alignment corresponding to the mode chosen.
979 However, where strict alignment is not required, avoid
980 over-aligning structures, since most compilers do not do this
983 if (TYPE_MODE (type) != BLKmode && TYPE_MODE (type) != VOIDmode
985 || (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE
986 && TREE_CODE (type) != QUAL_UNION_TYPE
987 && TREE_CODE (type) != ARRAY_TYPE)))
988 TYPE_ALIGN (type) = GET_MODE_ALIGNMENT (TYPE_MODE (type));
990 /* Evaluate nonconstant size only once, either now or as soon as safe. */
991 if (TYPE_SIZE (type) != 0 && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
992 TYPE_SIZE (type) = variable_size (TYPE_SIZE (type));
994 /* Also layout any other variants of the type. */
995 if (TYPE_NEXT_VARIANT (type)
996 || type != TYPE_MAIN_VARIANT (type))
999 /* Record layout info of this variant. */
1000 tree size = TYPE_SIZE (type);
1001 int align = TYPE_ALIGN (type);
1002 enum machine_mode mode = TYPE_MODE (type);
1004 /* Copy it into all variants. */
1005 for (variant = TYPE_MAIN_VARIANT (type);
1007 variant = TYPE_NEXT_VARIANT (variant))
1009 TYPE_SIZE (variant) = size;
1010 TYPE_ALIGN (variant) = align;
1011 TYPE_MODE (variant) = mode;
1016 resume_momentary (old);
1019 /* Create and return a type for signed integers of PRECISION bits. */
1022 make_signed_type (precision)
1025 register tree type = make_node (INTEGER_TYPE);
1027 TYPE_PRECISION (type) = precision;
1029 /* Create the extreme values based on the number of bits. */
1031 TYPE_MIN_VALUE (type)
1032 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1033 ? 0 : (HOST_WIDE_INT) (-1) << (precision - 1)),
1034 (((HOST_WIDE_INT) (-1)
1035 << (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1036 ? precision - HOST_BITS_PER_WIDE_INT - 1
1038 TYPE_MAX_VALUE (type)
1039 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1040 ? -1 : ((HOST_WIDE_INT) 1 << (precision - 1)) - 1),
1041 (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1042 ? (((HOST_WIDE_INT) 1
1043 << (precision - HOST_BITS_PER_WIDE_INT - 1))) - 1
1046 /* Give this type's extreme values this type as their type. */
1048 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
1049 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
1051 /* The first type made with this or `make_unsigned_type'
1052 is the type for size values. */
1059 /* Lay out the type: set its alignment, size, etc. */
1066 /* Create and return a type for unsigned integers of PRECISION bits. */
1069 make_unsigned_type (precision)
1072 register tree type = make_node (INTEGER_TYPE);
1074 TYPE_PRECISION (type) = precision;
1076 /* The first type made with this or `make_signed_type'
1077 is the type for size values. */
1084 fixup_unsigned_type (type);
1088 /* Set the extreme values of TYPE based on its precision in bits,
1089 then lay it out. Used when make_signed_type won't do
1090 because the tree code is not INTEGER_TYPE.
1091 E.g. for Pascal, when the -fsigned-char option is given. */
1094 fixup_signed_type (type)
1097 register int precision = TYPE_PRECISION (type);
1099 TYPE_MIN_VALUE (type)
1100 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1101 ? 0 : (HOST_WIDE_INT) (-1) << (precision - 1)),
1102 (((HOST_WIDE_INT) (-1)
1103 << (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1104 ? precision - HOST_BITS_PER_WIDE_INT - 1
1106 TYPE_MAX_VALUE (type)
1107 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1108 ? -1 : ((HOST_WIDE_INT) 1 << (precision - 1)) - 1),
1109 (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1110 ? (((HOST_WIDE_INT) 1
1111 << (precision - HOST_BITS_PER_WIDE_INT - 1))) - 1
1114 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
1115 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
1117 /* Lay out the type: set its alignment, size, etc. */
1122 /* Set the extreme values of TYPE based on its precision in bits,
1123 then lay it out. This is used both in `make_unsigned_type'
1124 and for enumeral types. */
1127 fixup_unsigned_type (type)
1130 register int precision = TYPE_PRECISION (type);
1132 TYPE_MIN_VALUE (type) = build_int_2 (0, 0);
1133 TYPE_MAX_VALUE (type)
1134 = build_int_2 (precision - HOST_BITS_PER_WIDE_INT >= 0
1135 ? -1 : ((HOST_WIDE_INT) 1 << precision) - 1,
1136 precision - HOST_BITS_PER_WIDE_INT > 0
1137 ? ((unsigned HOST_WIDE_INT) ~0
1138 >> (HOST_BITS_PER_WIDE_INT
1139 - (precision - HOST_BITS_PER_WIDE_INT)))
1141 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
1142 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
1144 /* Lay out the type: set its alignment, size, etc. */
1149 /* Find the best machine mode to use when referencing a bit field of length
1150 BITSIZE bits starting at BITPOS.
1152 The underlying object is known to be aligned to a boundary of ALIGN bits.
1153 If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
1154 larger than LARGEST_MODE (usually SImode).
1156 If no mode meets all these conditions, we return VOIDmode. Otherwise, if
1157 VOLATILEP is true or SLOW_BYTE_ACCESS is false, we return the smallest
1158 mode meeting these conditions.
1160 Otherwise (VOLATILEP is false and SLOW_BYTE_ACCESS is true), we return
1161 the largest mode (but a mode no wider than UNITS_PER_WORD) that meets
1162 all the conditions. */
1165 get_best_mode (bitsize, bitpos, align, largest_mode, volatilep)
1166 int bitsize, bitpos;
1168 enum machine_mode largest_mode;
1171 enum machine_mode mode;
1174 /* Find the narrowest integer mode that contains the bit field. */
1175 for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
1176 mode = GET_MODE_WIDER_MODE (mode))
1178 unit = GET_MODE_BITSIZE (mode);
1179 if (bitpos / unit == (bitpos + bitsize - 1) / unit)
1183 if (mode == MAX_MACHINE_MODE
1184 /* It is tempting to omit the following line
1185 if STRICT_ALIGNMENT is true.
1186 But that is incorrect, since if the bitfield uses part of 3 bytes
1187 and we use a 4-byte mode, we could get a spurious segv
1188 if the extra 4th byte is past the end of memory.
1189 (Though at least one Unix compiler ignores this problem:
1190 that on the Sequent 386 machine. */
1191 || MIN (unit, BIGGEST_ALIGNMENT) > align
1192 || (largest_mode != VOIDmode && unit > GET_MODE_BITSIZE (largest_mode)))
1195 if (SLOW_BYTE_ACCESS && ! volatilep)
1197 enum machine_mode wide_mode = VOIDmode, tmode;
1199 for (tmode = GET_CLASS_NARROWEST_MODE (MODE_INT); tmode != VOIDmode;
1200 tmode = GET_MODE_WIDER_MODE (tmode))
1202 unit = GET_MODE_BITSIZE (tmode);
1203 if (bitpos / unit == (bitpos + bitsize - 1) / unit
1204 && unit <= BITS_PER_WORD
1205 && unit <= MIN (align, BIGGEST_ALIGNMENT)
1206 && (largest_mode == VOIDmode
1207 || unit <= GET_MODE_BITSIZE (largest_mode)))
1211 if (wide_mode != VOIDmode)
1218 /* Save all variables describing the current status into the structure *P.
1219 This is used before starting a nested function. */
1222 save_storage_status (p)
1225 #if 0 /* Need not save, since always 0 and non0 (resp.) within a function. */
1226 p->pending_sizes = pending_sizes;
1227 p->immediate_size_expand = immediate_size_expand;
1231 /* Restore all variables describing the current status from the structure *P.
1232 This is used after a nested function. */
1235 restore_storage_status (p)
1239 pending_sizes = p->pending_sizes;
1240 immediate_size_expand = p->immediate_size_expand;