1 /* C-compiler utilities for types and variables storage layout
2 Copyright (C) 1987, 88, 92, 93, 94, 1995 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. */
28 #define CEIL(x,y) (((x) + (y) - 1) / (y))
30 /* Data type for the expressions representing sizes of data types.
31 It is the first integer type laid out.
36 /* An integer constant with value 0 whose type is sizetype. */
40 /* An integer constant with value 1 whose type is sizetype. */
44 /* If nonzero, this is an upper limit on alignment of structure fields.
45 The value is measured in bits. */
46 int maximum_field_alignment;
48 /* If non-zero, the alignment of a bitsting or (power-)set value, in bits.
49 May be overridden by front-ends. */
50 int set_alignment = 0;
52 #define GET_MODE_ALIGNMENT(MODE) \
53 MIN (BIGGEST_ALIGNMENT, \
54 MAX (1, (GET_MODE_UNIT_SIZE (MODE) * BITS_PER_UNIT)))
56 static enum machine_mode smallest_mode_for_size PROTO((unsigned int,
58 static tree layout_record PROTO((tree));
59 static void layout_union PROTO((tree));
61 /* SAVE_EXPRs for sizes of types and decls, waiting to be expanded. */
63 static tree pending_sizes;
65 /* Nonzero means cannot safely call expand_expr now,
66 so put variable sizes onto `pending_sizes' instead. */
68 int immediate_size_expand;
73 tree chain = pending_sizes;
76 /* Put each SAVE_EXPR into the current function. */
77 for (t = chain; t; t = TREE_CHAIN (t))
78 SAVE_EXPR_CONTEXT (TREE_VALUE (t)) = current_function_decl;
83 /* Given a size SIZE that isn't constant, return a SAVE_EXPR
84 to serve as the actual size-expression for a type or decl. */
90 /* If the language-processor is to take responsibility for variable-sized
91 items (e.g., languages which have elaboration procedures like Ada),
92 just return SIZE unchanged. Likewise for self-referential sizes. */
93 if (global_bindings_p () < 0 || contains_placeholder_p (size))
96 size = save_expr (size);
98 if (global_bindings_p ())
100 if (TREE_CONSTANT (size))
101 error ("type size can't be explicitly evaluated");
103 error ("variable-size type declared outside of any function");
108 if (immediate_size_expand)
109 /* NULL_RTX is not defined; neither is the rtx type.
110 Also, we would like to pass const0_rtx here, but don't have it. */
111 expand_expr (size, expand_expr (integer_zero_node, NULL_PTR, VOIDmode, 0),
114 pending_sizes = tree_cons (NULL_TREE, size, pending_sizes);
119 #ifndef MAX_FIXED_MODE_SIZE
120 #define MAX_FIXED_MODE_SIZE GET_MODE_BITSIZE (DImode)
123 /* Return the machine mode to use for a nonscalar of SIZE bits.
124 The mode must be in class CLASS, and have exactly that many bits.
125 If LIMIT is nonzero, modes of wider than MAX_FIXED_MODE_SIZE will not
129 mode_for_size (size, class, limit)
131 enum mode_class class;
134 register enum machine_mode mode;
136 if (limit && size > MAX_FIXED_MODE_SIZE)
139 /* Get the first mode which has this size, in the specified class. */
140 for (mode = GET_CLASS_NARROWEST_MODE (class); mode != VOIDmode;
141 mode = GET_MODE_WIDER_MODE (mode))
142 if (GET_MODE_BITSIZE (mode) == size)
148 /* Similar, but never return BLKmode; return the narrowest mode that
149 contains at least the requested number of bits. */
151 static enum machine_mode
152 smallest_mode_for_size (size, class)
154 enum mode_class class;
156 register enum machine_mode mode;
158 /* Get the first mode which has at least this size, in the
160 for (mode = GET_CLASS_NARROWEST_MODE (class); mode != VOIDmode;
161 mode = GET_MODE_WIDER_MODE (mode))
162 if (GET_MODE_BITSIZE (mode) >= size)
168 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
171 round_up (value, divisor)
175 return size_binop (MULT_EXPR,
176 size_binop (CEIL_DIV_EXPR, value, size_int (divisor)),
180 /* Set the size, mode and alignment of a ..._DECL node.
181 TYPE_DECL does need this for C++.
182 Note that LABEL_DECL and CONST_DECL nodes do not need this,
183 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
184 Don't call layout_decl for them.
186 KNOWN_ALIGN is the amount of alignment we can assume this
187 decl has with no special effort. It is relevant only for FIELD_DECLs
188 and depends on the previous fields.
189 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
190 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
191 the record will be aligned to suit. */
194 layout_decl (decl, known_align)
196 unsigned known_align;
198 register tree type = TREE_TYPE (decl);
199 register enum tree_code code = TREE_CODE (decl);
200 int spec_size = DECL_FIELD_SIZE (decl);
202 if (code == CONST_DECL)
205 if (code != VAR_DECL && code != PARM_DECL && code != RESULT_DECL
206 && code != FIELD_DECL && code != TYPE_DECL)
209 if (type == error_mark_node)
211 type = void_type_node;
215 /* Usually the size and mode come from the data type without change. */
217 DECL_MODE (decl) = TYPE_MODE (type);
218 TREE_UNSIGNED (decl) = TREE_UNSIGNED (type);
219 if (DECL_SIZE (decl) == 0)
220 DECL_SIZE (decl) = TYPE_SIZE (type);
222 if (code == FIELD_DECL && DECL_BIT_FIELD (decl))
224 if (spec_size == 0 && DECL_NAME (decl) != 0)
227 /* Size is specified number of bits. */
228 DECL_SIZE (decl) = size_int (spec_size);
230 /* Force alignment required for the data type.
231 But if the decl itself wants greater alignment, don't override that.
232 Likewise, if the decl is packed, don't override it. */
233 else if (DECL_ALIGN (decl) == 0
234 || (! DECL_PACKED (decl) && TYPE_ALIGN (type) > DECL_ALIGN (decl)))
235 DECL_ALIGN (decl) = TYPE_ALIGN (type);
237 /* See if we can use an ordinary integer mode for a bit-field. */
238 /* Conditions are: a fixed size that is correct for another mode
239 and occupying a complete byte or bytes on proper boundary. */
240 if (code == FIELD_DECL)
242 DECL_BIT_FIELD_TYPE (decl) = DECL_BIT_FIELD (decl) ? type : 0;
243 if (maximum_field_alignment != 0)
244 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), maximum_field_alignment);
245 else if (flag_pack_struct)
246 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), BITS_PER_UNIT);
249 if (DECL_BIT_FIELD (decl)
250 && TYPE_SIZE (type) != 0
251 && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST)
253 register enum machine_mode xmode
254 = mode_for_size (TREE_INT_CST_LOW (DECL_SIZE (decl)), MODE_INT, 1);
257 && known_align % GET_MODE_ALIGNMENT (xmode) == 0)
259 DECL_ALIGN (decl) = MAX (GET_MODE_ALIGNMENT (xmode),
261 DECL_MODE (decl) = xmode;
262 DECL_SIZE (decl) = size_int (GET_MODE_BITSIZE (xmode));
263 /* This no longer needs to be accessed as a bit field. */
264 DECL_BIT_FIELD (decl) = 0;
268 /* Evaluate nonconstant size only once, either now or as soon as safe. */
269 if (DECL_SIZE (decl) != 0 && TREE_CODE (DECL_SIZE (decl)) != INTEGER_CST)
270 DECL_SIZE (decl) = variable_size (DECL_SIZE (decl));
273 /* Lay out a RECORD_TYPE type (a C struct).
274 This means laying out the fields, determining their positions,
275 and computing the overall size and required alignment of the record.
276 Note that if you set the TYPE_ALIGN before calling this
277 then the struct is aligned to at least that boundary.
279 If the type has basetypes, you must call layout_basetypes
280 before calling this function.
282 The return value is a list of static members of the record.
283 They still need to be laid out. */
290 #ifdef STRUCTURE_SIZE_BOUNDARY
291 unsigned record_align = MAX (STRUCTURE_SIZE_BOUNDARY, TYPE_ALIGN (rec));
293 unsigned record_align = MAX (BITS_PER_UNIT, TYPE_ALIGN (rec));
295 /* These must be laid out *after* the record is. */
296 tree pending_statics = NULL_TREE;
297 /* Record size so far is CONST_SIZE + VAR_SIZE bits,
298 where CONST_SIZE is an integer
299 and VAR_SIZE is a tree expression.
300 If VAR_SIZE is null, the size is just CONST_SIZE.
301 Naturally we try to avoid using VAR_SIZE. */
302 register int const_size = 0;
303 register tree var_size = 0;
304 /* Once we start using VAR_SIZE, this is the maximum alignment
305 that we know VAR_SIZE has. */
306 register int var_align = BITS_PER_UNIT;
309 for (field = TYPE_FIELDS (rec); field; field = TREE_CHAIN (field))
311 register int known_align = var_size ? var_align : const_size;
312 register int desired_align;
314 /* If FIELD is static, then treat it like a separate variable,
315 not really like a structure field.
316 If it is a FUNCTION_DECL, it's a method.
317 In both cases, all we do is lay out the decl,
318 and we do it *after* the record is laid out. */
320 if (TREE_STATIC (field))
322 pending_statics = tree_cons (NULL_TREE, field, pending_statics);
325 /* Enumerators and enum types which are local to this class need not
326 be laid out. Likewise for initialized constant fields. */
327 if (TREE_CODE (field) != FIELD_DECL)
330 /* Lay out the field so we know what alignment it needs.
331 For a packed field, use the alignment as specified,
332 disregarding what the type would want. */
333 if (DECL_PACKED (field))
334 desired_align = DECL_ALIGN (field);
335 layout_decl (field, known_align);
336 if (! DECL_PACKED (field))
337 desired_align = DECL_ALIGN (field);
338 /* Some targets (i.e. VMS) limit struct field alignment
339 to a lower boundary than alignment of variables. */
340 #ifdef BIGGEST_FIELD_ALIGNMENT
341 desired_align = MIN (desired_align, BIGGEST_FIELD_ALIGNMENT);
344 /* Record must have at least as much alignment as any field.
345 Otherwise, the alignment of the field within the record
348 #ifndef PCC_BITFIELD_TYPE_MATTERS
349 record_align = MAX (record_align, desired_align);
351 if (PCC_BITFIELD_TYPE_MATTERS && TREE_TYPE (field) != error_mark_node
352 && DECL_BIT_FIELD_TYPE (field)
353 && ! integer_zerop (TYPE_SIZE (TREE_TYPE (field))))
355 /* For these machines, a zero-length field does not
356 affect the alignment of the structure as a whole.
357 It does, however, affect the alignment of the next field
358 within the structure. */
359 if (! integer_zerop (DECL_SIZE (field)))
360 record_align = MAX (record_align, desired_align);
361 else if (! DECL_PACKED (field))
362 desired_align = TYPE_ALIGN (TREE_TYPE (field));
363 /* A named bit field of declared type `int'
364 forces the entire structure to have `int' alignment. */
365 if (DECL_NAME (field) != 0)
367 int type_align = TYPE_ALIGN (TREE_TYPE (field));
368 if (maximum_field_alignment != 0)
369 type_align = MIN (type_align, maximum_field_alignment);
370 else if (flag_pack_struct)
371 type_align = MIN (type_align, BITS_PER_UNIT);
373 record_align = MAX (record_align, type_align);
377 record_align = MAX (record_align, desired_align);
380 /* Does this field automatically have alignment it needs
381 by virtue of the fields that precede it and the record's
384 if (const_size % desired_align != 0
385 || (var_align % desired_align != 0
388 /* No, we need to skip space before this field.
389 Bump the cumulative size to multiple of field alignment. */
392 || var_align % desired_align == 0)
394 = CEIL (const_size, desired_align) * desired_align;
398 var_size = size_binop (PLUS_EXPR, var_size,
399 size_int (const_size));
401 var_size = round_up (var_size, desired_align);
402 var_align = MIN (var_align, desired_align);
406 #ifdef PCC_BITFIELD_TYPE_MATTERS
407 if (PCC_BITFIELD_TYPE_MATTERS
408 && TREE_CODE (field) == FIELD_DECL
409 && TREE_TYPE (field) != error_mark_node
410 && DECL_BIT_FIELD_TYPE (field)
411 && !DECL_PACKED (field)
412 /* If #pragma pack is in effect, turn off this feature. */
413 && maximum_field_alignment == 0
415 && !integer_zerop (DECL_SIZE (field)))
417 int type_align = TYPE_ALIGN (TREE_TYPE (field));
418 register tree dsize = DECL_SIZE (field);
419 int field_size = TREE_INT_CST_LOW (dsize);
421 /* A bit field may not span the unit of alignment of its type.
422 Advance to next boundary if necessary. */
423 /* ??? There is some uncertainty here as to what
424 should be done if type_align is less than the width of the type.
425 That can happen because the width exceeds BIGGEST_ALIGNMENT
426 or because it exceeds maximum_field_alignment. */
427 if (const_size / type_align
428 != (const_size + field_size - 1) / type_align)
429 const_size = CEIL (const_size, type_align) * type_align;
433 /* No existing machine description uses this parameter.
434 So I have made it in this aspect identical to PCC_BITFIELD_TYPE_MATTERS. */
435 #ifdef BITFIELD_NBYTES_LIMITED
436 if (BITFIELD_NBYTES_LIMITED
437 && TREE_CODE (field) == FIELD_DECL
438 && TREE_TYPE (field) != error_mark_node
439 && DECL_BIT_FIELD_TYPE (field)
440 && !DECL_PACKED (field)
441 && !integer_zerop (DECL_SIZE (field)))
443 int type_align = TYPE_ALIGN (TREE_TYPE (field));
444 register tree dsize = DECL_SIZE (field);
445 int field_size = TREE_INT_CST_LOW (dsize);
447 if (maximum_field_alignment != 0)
448 type_align = MIN (type_align, maximum_field_alignment);
449 else if (flag_pack_struct)
450 type_align = MIN (type_align, BITS_PER_UNIT);
452 /* A bit field may not span the unit of alignment of its type.
453 Advance to next boundary if necessary. */
454 if (const_size / type_align
455 != (const_size + field_size - 1) / type_align)
456 const_size = CEIL (const_size, type_align) * type_align;
460 /* Size so far becomes the position of this field. */
462 if (var_size && const_size)
463 DECL_FIELD_BITPOS (field)
464 = size_binop (PLUS_EXPR, var_size, size_int (const_size));
466 DECL_FIELD_BITPOS (field) = var_size;
469 DECL_FIELD_BITPOS (field) = size_int (const_size);
471 /* If this field ended up more aligned than we thought it
472 would be (we approximate this by seeing if its position
473 changed), lay out the field again; perhaps we can use an
474 integral mode for it now. */
475 if (known_align != const_size)
476 layout_decl (field, const_size);
479 /* Now add size of this field to the size of the record. */
482 register tree dsize = DECL_SIZE (field);
484 /* This can happen when we have an invalid nested struct definition,
485 such as struct j { struct j { int i; } }. The error message is
486 printed in finish_struct. */
489 else if (TREE_CODE (dsize) == INTEGER_CST
490 && TREE_INT_CST_HIGH (dsize) == 0
491 && TREE_INT_CST_LOW (dsize) + const_size > const_size)
492 /* Use const_size if there's no overflow. */
493 const_size += TREE_INT_CST_LOW (dsize);
499 var_size = size_binop (PLUS_EXPR, var_size, dsize);
504 /* Work out the total size and alignment of the record
505 as one expression and store in the record type.
506 Round it up to a multiple of the record's alignment. */
510 TYPE_SIZE (rec) = size_int (const_size);
516 = size_binop (PLUS_EXPR, var_size, size_int (const_size));
517 TYPE_SIZE (rec) = var_size;
520 /* Determine the desired alignment. */
521 #ifdef ROUND_TYPE_ALIGN
522 TYPE_ALIGN (rec) = ROUND_TYPE_ALIGN (rec, TYPE_ALIGN (rec), record_align);
524 TYPE_ALIGN (rec) = MAX (TYPE_ALIGN (rec), record_align);
527 #ifdef ROUND_TYPE_SIZE
528 TYPE_SIZE (rec) = ROUND_TYPE_SIZE (rec, TYPE_SIZE (rec), TYPE_ALIGN (rec));
530 /* Round the size up to be a multiple of the required alignment */
531 TYPE_SIZE (rec) = round_up (TYPE_SIZE (rec), TYPE_ALIGN (rec));
534 return pending_statics;
537 /* Lay out a UNION_TYPE or QUAL_UNION_TYPE type.
538 Lay out all the fields, set their positions to zero,
539 and compute the size and alignment of the union (maximum of any field).
540 Note that if you set the TYPE_ALIGN before calling this
541 then the union align is aligned to at least that boundary. */
548 #ifdef STRUCTURE_SIZE_BOUNDARY
549 unsigned union_align = STRUCTURE_SIZE_BOUNDARY;
551 unsigned union_align = BITS_PER_UNIT;
554 /* The size of the union, based on the fields scanned so far,
555 is max (CONST_SIZE, VAR_SIZE).
556 VAR_SIZE may be null; then CONST_SIZE by itself is the size. */
557 register int const_size = 0;
558 register tree var_size = 0;
560 /* If this is a QUAL_UNION_TYPE, we want to process the fields in
561 the reverse order in building the COND_EXPR that denotes its
562 size. We reverse them again later. */
563 if (TREE_CODE (rec) == QUAL_UNION_TYPE)
564 TYPE_FIELDS (rec) = nreverse (TYPE_FIELDS (rec));
566 for (field = TYPE_FIELDS (rec); field; field = TREE_CHAIN (field))
568 /* Enums which are local to this class need not be laid out. */
569 if (TREE_CODE (field) == CONST_DECL || TREE_CODE (field) == TYPE_DECL)
572 layout_decl (field, 0);
573 DECL_FIELD_BITPOS (field) = size_int (0);
575 /* Union must be at least as aligned as any field requires. */
577 union_align = MAX (union_align, DECL_ALIGN (field));
579 #ifdef PCC_BITFIELD_TYPE_MATTERS
580 /* On the m88000, a bit field of declare type `int'
581 forces the entire union to have `int' alignment. */
582 if (PCC_BITFIELD_TYPE_MATTERS && DECL_BIT_FIELD_TYPE (field))
583 union_align = MAX (union_align, TYPE_ALIGN (TREE_TYPE (field)));
586 if (TREE_CODE (rec) == UNION_TYPE)
588 /* Set union_size to max (decl_size, union_size).
589 There are more and less general ways to do this.
590 Use only CONST_SIZE unless forced to use VAR_SIZE. */
592 if (TREE_CODE (DECL_SIZE (field)) == INTEGER_CST)
594 = MAX (const_size, TREE_INT_CST_LOW (DECL_SIZE (field)));
595 else if (var_size == 0)
596 var_size = DECL_SIZE (field);
598 var_size = size_binop (MAX_EXPR, var_size, DECL_SIZE (field));
600 else if (TREE_CODE (rec) == QUAL_UNION_TYPE)
601 var_size = fold (build (COND_EXPR, sizetype, DECL_QUALIFIER (field),
603 var_size ? var_size : integer_zero_node));
606 if (TREE_CODE (rec) == QUAL_UNION_TYPE)
607 TYPE_FIELDS (rec) = nreverse (TYPE_FIELDS (rec));
609 /* Determine the ultimate size of the union (in bytes). */
610 if (NULL == var_size)
611 TYPE_SIZE (rec) = size_int (CEIL (const_size, BITS_PER_UNIT)
613 else if (const_size == 0)
614 TYPE_SIZE (rec) = var_size;
616 TYPE_SIZE (rec) = size_binop (MAX_EXPR, var_size,
617 round_up (size_int (const_size),
620 /* Determine the desired alignment. */
621 #ifdef ROUND_TYPE_ALIGN
622 TYPE_ALIGN (rec) = ROUND_TYPE_ALIGN (rec, TYPE_ALIGN (rec), union_align);
624 TYPE_ALIGN (rec) = MAX (TYPE_ALIGN (rec), union_align);
627 #ifdef ROUND_TYPE_SIZE
628 TYPE_SIZE (rec) = ROUND_TYPE_SIZE (rec, TYPE_SIZE (rec), TYPE_ALIGN (rec));
630 /* Round the size up to be a multiple of the required alignment */
631 TYPE_SIZE (rec) = round_up (TYPE_SIZE (rec), TYPE_ALIGN (rec));
635 /* Calculate the mode, size, and alignment for TYPE.
636 For an array type, calculate the element separation as well.
637 Record TYPE on the chain of permanent or temporary types
638 so that dbxout will find out about it.
640 TYPE_SIZE of a type is nonzero if the type has been laid out already.
641 layout_type does nothing on such a type.
643 If the type is incomplete, its TYPE_SIZE remains zero. */
650 tree pending_statics;
655 /* Do nothing if type has been laid out before. */
656 if (TYPE_SIZE (type))
659 /* Make sure all nodes we allocate are not momentary;
660 they must last past the current statement. */
661 old = suspend_momentary ();
663 /* Put all our nodes into the same obstack as the type. Also,
664 make expressions saveable (this is a no-op for permanent types). */
666 push_obstacks (TYPE_OBSTACK (type), TYPE_OBSTACK (type));
667 saveable_allocation ();
669 switch (TREE_CODE (type))
672 /* This kind of type is the responsibility
673 of the languge-specific code. */
678 if (TREE_CODE (TYPE_MIN_VALUE (type)) == INTEGER_CST
679 && tree_int_cst_sgn (TYPE_MIN_VALUE (type)) >= 0)
680 TREE_UNSIGNED (type) = 1;
682 TYPE_MODE (type) = smallest_mode_for_size (TYPE_PRECISION (type),
684 TYPE_SIZE (type) = size_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
688 TYPE_MODE (type) = mode_for_size (TYPE_PRECISION (type), MODE_FLOAT, 0);
689 TYPE_SIZE (type) = size_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
693 TREE_UNSIGNED (type) = TREE_UNSIGNED (TREE_TYPE (type));
695 = mode_for_size (2 * TYPE_PRECISION (TREE_TYPE (type)),
696 (TREE_CODE (TREE_TYPE (type)) == INTEGER_TYPE
697 ? MODE_COMPLEX_INT : MODE_COMPLEX_FLOAT),
699 TYPE_SIZE (type) = size_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
703 TYPE_SIZE (type) = size_zero_node;
704 TYPE_ALIGN (type) = 1;
705 TYPE_MODE (type) = VOIDmode;
709 TYPE_SIZE (type) = size_int (POINTER_SIZE);
710 TYPE_MODE (type) = ptr_mode;
715 TYPE_MODE (type) = mode_for_size (2 * POINTER_SIZE, MODE_INT, 0);
716 TYPE_SIZE (type) = size_int (2 * POINTER_SIZE);
721 TYPE_MODE (type) = ptr_mode;
722 TYPE_SIZE (type) = size_int (POINTER_SIZE);
723 TREE_UNSIGNED (type) = 1;
724 TYPE_PRECISION (type) = POINTER_SIZE;
729 register tree index = TYPE_DOMAIN (type);
730 register tree element = TREE_TYPE (type);
732 build_pointer_type (element);
734 /* We need to know both bounds in order to compute the size. */
735 if (index && TYPE_MAX_VALUE (index) && TYPE_MIN_VALUE (index)
736 && TYPE_SIZE (element))
739 = size_binop (PLUS_EXPR, size_one_node,
740 size_binop (MINUS_EXPR, TYPE_MAX_VALUE (index),
741 TYPE_MIN_VALUE (index)));
743 /* If neither bound is a constant and sizetype is signed, make
744 sure the size is never negative. We should really do this
745 if *either* bound is non-constant, but this is the best
746 compromise between C and Ada. */
747 if (! TREE_UNSIGNED (sizetype)
748 && TREE_CODE (TYPE_MIN_VALUE (index)) != INTEGER_CST
749 && TREE_CODE (TYPE_MAX_VALUE (index)) != INTEGER_CST)
750 length = size_binop (MAX_EXPR, length, size_zero_node);
752 TYPE_SIZE (type) = size_binop (MULT_EXPR, length,
753 TYPE_SIZE (element));
756 /* Now round the alignment and size,
757 using machine-dependent criteria if any. */
759 #ifdef ROUND_TYPE_ALIGN
761 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (element), BITS_PER_UNIT);
763 TYPE_ALIGN (type) = MAX (TYPE_ALIGN (element), BITS_PER_UNIT);
766 #ifdef ROUND_TYPE_SIZE
767 if (TYPE_SIZE (type) != 0)
769 = ROUND_TYPE_SIZE (type, TYPE_SIZE (type), TYPE_ALIGN (type));
772 TYPE_MODE (type) = BLKmode;
773 if (TYPE_SIZE (type) != 0
774 && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
775 /* BLKmode elements force BLKmode aggregate;
776 else extract/store fields may lose. */
777 && (TYPE_MODE (TREE_TYPE (type)) != BLKmode
778 || TYPE_NO_FORCE_BLK (TREE_TYPE (type))))
781 = mode_for_size (TREE_INT_CST_LOW (TYPE_SIZE (type)),
784 if (STRICT_ALIGNMENT && TYPE_ALIGN (type) < BIGGEST_ALIGNMENT
785 && TYPE_ALIGN (type) < TREE_INT_CST_LOW (TYPE_SIZE (type))
786 && TYPE_MODE (type) != BLKmode)
788 TYPE_NO_FORCE_BLK (type) = 1;
789 TYPE_MODE (type) = BLKmode;
796 pending_statics = layout_record (type);
797 TYPE_MODE (type) = BLKmode;
798 if (TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST)
801 /* A record which has any BLKmode members must itself be BLKmode;
802 it can't go in a register.
803 Unless the member is BLKmode only because it isn't aligned. */
804 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
808 if (TREE_CODE (field) != FIELD_DECL)
811 if (TYPE_MODE (TREE_TYPE (field)) == BLKmode
812 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field)))
815 if (TREE_CODE (DECL_FIELD_BITPOS (field)) != INTEGER_CST)
818 bitpos = TREE_INT_CST_LOW (DECL_FIELD_BITPOS (field));
820 /* Must be BLKmode if any field crosses a word boundary,
821 since extract_bit_field can't handle that in registers. */
822 if (bitpos / BITS_PER_WORD
823 != ((TREE_INT_CST_LOW (DECL_SIZE (field)) + bitpos - 1)
825 /* But there is no problem if the field is entire words. */
826 && TREE_INT_CST_LOW (DECL_SIZE (field)) % BITS_PER_WORD == 0)
831 = mode_for_size (TREE_INT_CST_LOW (TYPE_SIZE (type)),
834 /* If structure's known alignment is less than
835 what the scalar mode would need, and it matters,
836 then stick with BLKmode. */
838 && ! (TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT
839 || (TYPE_ALIGN (type)
840 >= TREE_INT_CST_LOW (TYPE_SIZE (type)))))
842 if (TYPE_MODE (type) != BLKmode)
843 /* If this is the only reason this type is BLKmode,
844 then don't force containing types to be BLKmode. */
845 TYPE_NO_FORCE_BLK (type) = 1;
846 TYPE_MODE (type) = BLKmode;
852 /* Lay out any static members. This is done now
853 because their type may use the record's type. */
854 while (pending_statics)
856 layout_decl (TREE_VALUE (pending_statics), 0);
857 pending_statics = TREE_CHAIN (pending_statics);
862 case QUAL_UNION_TYPE:
864 TYPE_MODE (type) = BLKmode;
865 if (TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
866 /* If structure's known alignment is less than
867 what the scalar mode would need, and it matters,
868 then stick with BLKmode. */
869 && (! STRICT_ALIGNMENT
870 || TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT
871 || TYPE_ALIGN (type) >= TREE_INT_CST_LOW (TYPE_SIZE (type))))
874 /* A union which has any BLKmode members must itself be BLKmode;
875 it can't go in a register.
876 Unless the member is BLKmode only because it isn't aligned. */
877 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
879 if (TREE_CODE (field) != FIELD_DECL)
882 if (TYPE_MODE (TREE_TYPE (field)) == BLKmode
883 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field)))
888 = mode_for_size (TREE_INT_CST_LOW (TYPE_SIZE (type)),
895 /* Pascal and Chill types */
896 case BOOLEAN_TYPE: /* store one byte/boolean for now. */
897 TYPE_MODE (type) = QImode;
898 TYPE_SIZE (type) = size_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
899 TYPE_PRECISION (type) = 1;
900 TYPE_ALIGN (type) = GET_MODE_ALIGNMENT (TYPE_MODE (type));
901 if (TREE_CODE (TYPE_MIN_VALUE (type)) == INTEGER_CST
902 && tree_int_cst_sgn (TYPE_MIN_VALUE (type)) >= 0)
903 TREE_UNSIGNED (type) = 1;
907 TYPE_MODE (type) = QImode;
908 TYPE_SIZE (type) = size_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
909 TYPE_PRECISION (type) = GET_MODE_BITSIZE (TYPE_MODE (type));
910 TYPE_ALIGN (type) = GET_MODE_ALIGNMENT (TYPE_MODE (type));
914 if (TREE_CODE (TYPE_MAX_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST
915 || TREE_CODE (TYPE_MIN_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST)
919 #ifndef SET_WORD_SIZE
920 #define SET_WORD_SIZE BITS_PER_WORD
922 int alignment = set_alignment ? set_alignment : SET_WORD_SIZE;
924 TREE_INT_CST_LOW (TYPE_MAX_VALUE (TYPE_DOMAIN (type)))
925 - TREE_INT_CST_LOW (TYPE_MIN_VALUE (TYPE_DOMAIN (type))) + 1;
927 = ((size_in_bits + alignment - 1) / alignment) * alignment;
928 if (rounded_size > alignment)
929 TYPE_MODE (type) = BLKmode;
931 TYPE_MODE (type) = mode_for_size (alignment, MODE_INT, 1);
932 TYPE_SIZE (type) = size_int (rounded_size);
933 TYPE_ALIGN (type) = alignment;
934 TYPE_PRECISION (type) = size_in_bits;
939 /* The size may vary in different languages, so the language front end
940 should fill in the size. */
941 TYPE_ALIGN (type) = BIGGEST_ALIGNMENT;
942 TYPE_MODE (type) = BLKmode;
949 /* Normally, use the alignment corresponding to the mode chosen.
950 However, where strict alignment is not required, avoid
951 over-aligning structures, since most compilers do not do this
954 if (TYPE_MODE (type) != BLKmode && TYPE_MODE (type) != VOIDmode
956 || (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE
957 && TREE_CODE (type) != QUAL_UNION_TYPE
958 && TREE_CODE (type) != ARRAY_TYPE)))
959 TYPE_ALIGN (type) = GET_MODE_ALIGNMENT (TYPE_MODE (type));
961 /* Evaluate nonconstant size only once, either now or as soon as safe. */
962 if (TYPE_SIZE (type) != 0 && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
963 TYPE_SIZE (type) = variable_size (TYPE_SIZE (type));
965 /* Also layout any other variants of the type. */
966 if (TYPE_NEXT_VARIANT (type)
967 || type != TYPE_MAIN_VARIANT (type))
970 /* Record layout info of this variant. */
971 tree size = TYPE_SIZE (type);
972 int align = TYPE_ALIGN (type);
973 enum machine_mode mode = TYPE_MODE (type);
975 /* Copy it into all variants. */
976 for (variant = TYPE_MAIN_VARIANT (type);
978 variant = TYPE_NEXT_VARIANT (variant))
980 TYPE_SIZE (variant) = size;
981 TYPE_ALIGN (variant) = align;
982 TYPE_MODE (variant) = mode;
987 resume_momentary (old);
990 /* Create and return a type for signed integers of PRECISION bits. */
993 make_signed_type (precision)
996 register tree type = make_node (INTEGER_TYPE);
998 TYPE_PRECISION (type) = precision;
1000 /* Create the extreme values based on the number of bits. */
1002 TYPE_MIN_VALUE (type)
1003 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1004 ? 0 : (HOST_WIDE_INT) (-1) << (precision - 1)),
1005 (((HOST_WIDE_INT) (-1)
1006 << (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1007 ? precision - HOST_BITS_PER_WIDE_INT - 1
1009 TYPE_MAX_VALUE (type)
1010 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1011 ? -1 : ((HOST_WIDE_INT) 1 << (precision - 1)) - 1),
1012 (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1013 ? (((HOST_WIDE_INT) 1
1014 << (precision - HOST_BITS_PER_WIDE_INT - 1))) - 1
1017 /* Give this type's extreme values this type as their type. */
1019 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
1020 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
1022 /* The first type made with this or `make_unsigned_type'
1023 is the type for size values. */
1030 /* Lay out the type: set its alignment, size, etc. */
1037 /* Create and return a type for unsigned integers of PRECISION bits. */
1040 make_unsigned_type (precision)
1043 register tree type = make_node (INTEGER_TYPE);
1045 TYPE_PRECISION (type) = precision;
1047 /* The first type made with this or `make_signed_type'
1048 is the type for size values. */
1055 fixup_unsigned_type (type);
1059 /* Set the extreme values of TYPE based on its precision in bits,
1060 then lay it out. Used when make_signed_type won't do
1061 because the tree code is not INTEGER_TYPE.
1062 E.g. for Pascal, when the -fsigned-char option is given. */
1065 fixup_signed_type (type)
1068 register int precision = TYPE_PRECISION (type);
1070 TYPE_MIN_VALUE (type)
1071 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1072 ? 0 : (HOST_WIDE_INT) (-1) << (precision - 1)),
1073 (((HOST_WIDE_INT) (-1)
1074 << (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1075 ? precision - HOST_BITS_PER_WIDE_INT - 1
1077 TYPE_MAX_VALUE (type)
1078 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1079 ? -1 : ((HOST_WIDE_INT) 1 << (precision - 1)) - 1),
1080 (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1081 ? (((HOST_WIDE_INT) 1
1082 << (precision - HOST_BITS_PER_WIDE_INT - 1))) - 1
1085 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
1086 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
1088 /* Lay out the type: set its alignment, size, etc. */
1093 /* Set the extreme values of TYPE based on its precision in bits,
1094 then lay it out. This is used both in `make_unsigned_type'
1095 and for enumeral types. */
1098 fixup_unsigned_type (type)
1101 register int precision = TYPE_PRECISION (type);
1103 TYPE_MIN_VALUE (type) = build_int_2 (0, 0);
1104 TYPE_MAX_VALUE (type)
1105 = build_int_2 (precision - HOST_BITS_PER_WIDE_INT >= 0
1106 ? -1 : ((HOST_WIDE_INT) 1 << precision) - 1,
1107 precision - HOST_BITS_PER_WIDE_INT > 0
1108 ? ((unsigned HOST_WIDE_INT) ~0
1109 >> (HOST_BITS_PER_WIDE_INT
1110 - (precision - HOST_BITS_PER_WIDE_INT)))
1112 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
1113 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
1115 /* Lay out the type: set its alignment, size, etc. */
1120 /* Find the best machine mode to use when referencing a bit field of length
1121 BITSIZE bits starting at BITPOS.
1123 The underlying object is known to be aligned to a boundary of ALIGN bits.
1124 If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
1125 larger than LARGEST_MODE (usually SImode).
1127 If no mode meets all these conditions, we return VOIDmode. Otherwise, if
1128 VOLATILEP is true or SLOW_BYTE_ACCESS is false, we return the smallest
1129 mode meeting these conditions.
1131 Otherwise (VOLATILEP is false and SLOW_BYTE_ACCESS is true), we return
1132 the largest mode (but a mode no wider than UNITS_PER_WORD) that meets
1133 all the conditions. */
1136 get_best_mode (bitsize, bitpos, align, largest_mode, volatilep)
1137 int bitsize, bitpos;
1139 enum machine_mode largest_mode;
1142 enum machine_mode mode;
1145 /* Find the narrowest integer mode that contains the bit field. */
1146 for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
1147 mode = GET_MODE_WIDER_MODE (mode))
1149 unit = GET_MODE_BITSIZE (mode);
1150 if (bitpos / unit == (bitpos + bitsize - 1) / unit)
1154 if (mode == MAX_MACHINE_MODE
1155 /* It is tempting to omit the following line
1156 if STRICT_ALIGNMENT is true.
1157 But that is incorrect, since if the bitfield uses part of 3 bytes
1158 and we use a 4-byte mode, we could get a spurious segv
1159 if the extra 4th byte is past the end of memory.
1160 (Though at least one Unix compiler ignores this problem:
1161 that on the Sequent 386 machine. */
1162 || MIN (unit, BIGGEST_ALIGNMENT) > align
1163 || (largest_mode != VOIDmode && unit > GET_MODE_BITSIZE (largest_mode)))
1166 if (SLOW_BYTE_ACCESS && ! volatilep)
1168 enum machine_mode wide_mode = VOIDmode, tmode;
1170 for (tmode = GET_CLASS_NARROWEST_MODE (MODE_INT); tmode != VOIDmode;
1171 tmode = GET_MODE_WIDER_MODE (tmode))
1173 unit = GET_MODE_BITSIZE (tmode);
1174 if (bitpos / unit == (bitpos + bitsize - 1) / unit
1175 && unit <= BITS_PER_WORD
1176 && unit <= MIN (align, BIGGEST_ALIGNMENT)
1177 && (largest_mode == VOIDmode
1178 || unit <= GET_MODE_BITSIZE (largest_mode)))
1182 if (wide_mode != VOIDmode)
1189 /* Save all variables describing the current status into the structure *P.
1190 This is used before starting a nested function. */
1193 save_storage_status (p)
1196 #if 0 /* Need not save, since always 0 and non0 (resp.) within a function. */
1197 p->pending_sizes = pending_sizes;
1198 p->immediate_size_expand = immediate_size_expand;
1202 /* Restore all variables describing the current status from the structure *P.
1203 This is used after a nested function. */
1206 restore_storage_status (p)
1210 pending_sizes = p->pending_sizes;
1211 immediate_size_expand = p->immediate_size_expand;