1 /* C-compiler utilities for types and variables storage layout
2 Copyright (C) 1987, 88, 92-97, 1998 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.
36 tree sizetype_tab[2], sbitsizetype, ubitsizetype;
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 unsigned record_align = MAX (BITS_PER_UNIT, TYPE_ALIGN (rec));
310 /* These must be laid out *after* the record is. */
311 tree pending_statics = NULL_TREE;
312 /* Record size so far is CONST_SIZE + VAR_SIZE bits,
313 where CONST_SIZE is an integer
314 and VAR_SIZE is a tree expression.
315 If VAR_SIZE is null, the size is just CONST_SIZE.
316 Naturally we try to avoid using VAR_SIZE. */
317 register HOST_WIDE_INT const_size = 0;
318 register tree var_size = 0;
319 /* Once we start using VAR_SIZE, this is the maximum alignment
320 that we know VAR_SIZE has. */
321 register int var_align = BITS_PER_UNIT;
323 #ifdef STRUCTURE_SIZE_BOUNDARY
324 /* Packed structures don't need to have minimum size. */
325 if (! TYPE_PACKED (rec))
326 record_align = MAX (record_align, STRUCTURE_SIZE_BOUNDARY);
329 for (field = TYPE_FIELDS (rec); field; field = TREE_CHAIN (field))
331 register int known_align = var_size ? var_align : const_size;
332 register int desired_align;
334 /* If FIELD is static, then treat it like a separate variable,
335 not really like a structure field.
336 If it is a FUNCTION_DECL, it's a method.
337 In both cases, all we do is lay out the decl,
338 and we do it *after* the record is laid out. */
340 if (TREE_CODE (field) == VAR_DECL)
342 pending_statics = tree_cons (NULL_TREE, field, pending_statics);
345 /* Enumerators and enum types which are local to this class need not
346 be laid out. Likewise for initialized constant fields. */
347 if (TREE_CODE (field) != FIELD_DECL)
350 /* Lay out the field so we know what alignment it needs.
351 For a packed field, use the alignment as specified,
352 disregarding what the type would want. */
353 if (DECL_PACKED (field))
354 desired_align = DECL_ALIGN (field);
355 layout_decl (field, known_align);
356 if (! DECL_PACKED (field))
357 desired_align = DECL_ALIGN (field);
358 /* Some targets (i.e. VMS) limit struct field alignment
359 to a lower boundary than alignment of variables. */
360 #ifdef BIGGEST_FIELD_ALIGNMENT
361 desired_align = MIN (desired_align, BIGGEST_FIELD_ALIGNMENT);
363 #ifdef ADJUST_FIELD_ALIGN
364 desired_align = ADJUST_FIELD_ALIGN (field, desired_align);
367 /* Record must have at least as much alignment as any field.
368 Otherwise, the alignment of the field within the record
371 #ifndef PCC_BITFIELD_TYPE_MATTERS
372 record_align = MAX (record_align, desired_align);
374 if (PCC_BITFIELD_TYPE_MATTERS && TREE_TYPE (field) != error_mark_node
375 && DECL_BIT_FIELD_TYPE (field)
376 && ! integer_zerop (TYPE_SIZE (TREE_TYPE (field))))
378 /* For these machines, a zero-length field does not
379 affect the alignment of the structure as a whole.
380 It does, however, affect the alignment of the next field
381 within the structure. */
382 if (! integer_zerop (DECL_SIZE (field)))
383 record_align = MAX (record_align, desired_align);
384 else if (! DECL_PACKED (field))
385 desired_align = TYPE_ALIGN (TREE_TYPE (field));
386 /* A named bit field of declared type `int'
387 forces the entire structure to have `int' alignment. */
388 if (DECL_NAME (field) != 0)
390 int type_align = TYPE_ALIGN (TREE_TYPE (field));
391 if (maximum_field_alignment != 0)
392 type_align = MIN (type_align, maximum_field_alignment);
393 else if (DECL_PACKED (field))
394 type_align = MIN (type_align, BITS_PER_UNIT);
396 record_align = MAX (record_align, type_align);
400 record_align = MAX (record_align, desired_align);
403 /* Does this field automatically have alignment it needs
404 by virtue of the fields that precede it and the record's
407 if (const_size % desired_align != 0
408 || (var_align % desired_align != 0
411 /* No, we need to skip space before this field.
412 Bump the cumulative size to multiple of field alignment. */
415 || var_align % desired_align == 0)
417 = CEIL (const_size, desired_align) * desired_align;
421 var_size = size_binop (PLUS_EXPR, var_size,
422 bitsize_int (const_size, 0L));
424 var_size = round_up (var_size, desired_align);
425 var_align = MIN (var_align, desired_align);
429 #ifdef PCC_BITFIELD_TYPE_MATTERS
430 if (PCC_BITFIELD_TYPE_MATTERS
431 && TREE_CODE (field) == FIELD_DECL
432 && TREE_TYPE (field) != error_mark_node
433 && DECL_BIT_FIELD_TYPE (field)
434 && !DECL_PACKED (field)
435 && maximum_field_alignment == 0
436 && !integer_zerop (DECL_SIZE (field)))
438 int type_align = TYPE_ALIGN (TREE_TYPE (field));
439 register tree dsize = DECL_SIZE (field);
440 int field_size = TREE_INT_CST_LOW (dsize);
442 /* A bit field may not span more units of alignment of its type
443 than its type itself. Advance to next boundary if necessary. */
444 if (((const_size + field_size + type_align - 1) / type_align
445 - const_size / type_align)
446 > TREE_INT_CST_LOW (TYPE_SIZE (TREE_TYPE (field))) / type_align)
447 const_size = CEIL (const_size, type_align) * type_align;
451 /* No existing machine description uses this parameter.
452 So I have made it in this aspect identical to PCC_BITFIELD_TYPE_MATTERS. */
453 #ifdef BITFIELD_NBYTES_LIMITED
454 if (BITFIELD_NBYTES_LIMITED
455 && TREE_CODE (field) == FIELD_DECL
456 && TREE_TYPE (field) != error_mark_node
457 && DECL_BIT_FIELD_TYPE (field)
458 && !DECL_PACKED (field)
459 && !integer_zerop (DECL_SIZE (field)))
461 int type_align = TYPE_ALIGN (TREE_TYPE (field));
462 register tree dsize = DECL_SIZE (field);
463 int field_size = TREE_INT_CST_LOW (dsize);
465 if (maximum_field_alignment != 0)
466 type_align = MIN (type_align, maximum_field_alignment);
467 /* ??? This test is opposite the test in the containing if
468 statement, so this code is unreachable currently. */
469 else if (DECL_PACKED (field))
470 type_align = MIN (type_align, BITS_PER_UNIT);
472 /* A bit field may not span the unit of alignment of its type.
473 Advance to next boundary if necessary. */
474 /* ??? This code should match the code above for the
475 PCC_BITFIELD_TYPE_MATTERS case. */
476 if (const_size / type_align
477 != (const_size + field_size - 1) / type_align)
478 const_size = CEIL (const_size, type_align) * type_align;
482 /* Size so far becomes the position of this field. */
484 if (var_size && const_size)
485 DECL_FIELD_BITPOS (field)
486 = size_binop (PLUS_EXPR, var_size, bitsize_int (const_size, 0L));
488 DECL_FIELD_BITPOS (field) = var_size;
491 DECL_FIELD_BITPOS (field) = size_int (const_size);
493 /* If this field ended up more aligned than we thought it
494 would be (we approximate this by seeing if its position
495 changed), lay out the field again; perhaps we can use an
496 integral mode for it now. */
497 if (known_align != const_size)
498 layout_decl (field, const_size);
501 /* Now add size of this field to the size of the record. */
504 register tree dsize = DECL_SIZE (field);
506 /* This can happen when we have an invalid nested struct definition,
507 such as struct j { struct j { int i; } }. The error message is
508 printed in finish_struct. */
511 else if (TREE_CODE (dsize) == INTEGER_CST
512 && ! TREE_CONSTANT_OVERFLOW (dsize)
513 && TREE_INT_CST_HIGH (dsize) == 0
514 && TREE_INT_CST_LOW (dsize) + const_size >= const_size)
515 /* Use const_size if there's no overflow. */
516 const_size += TREE_INT_CST_LOW (dsize);
522 var_size = size_binop (PLUS_EXPR, var_size, dsize);
527 /* Work out the total size and alignment of the record
528 as one expression and store in the record type.
529 Round it up to a multiple of the record's alignment. */
533 TYPE_SIZE (rec) = size_int (const_size);
539 = size_binop (PLUS_EXPR, var_size, bitsize_int (const_size, 0L));
540 TYPE_SIZE (rec) = var_size;
543 /* Determine the desired alignment. */
544 #ifdef ROUND_TYPE_ALIGN
545 TYPE_ALIGN (rec) = ROUND_TYPE_ALIGN (rec, TYPE_ALIGN (rec), record_align);
547 TYPE_ALIGN (rec) = MAX (TYPE_ALIGN (rec), record_align);
550 #ifdef ROUND_TYPE_SIZE
551 TYPE_SIZE (rec) = ROUND_TYPE_SIZE (rec, TYPE_SIZE (rec), TYPE_ALIGN (rec));
553 /* Round the size up to be a multiple of the required alignment */
554 TYPE_SIZE (rec) = round_up (TYPE_SIZE (rec), TYPE_ALIGN (rec));
557 return pending_statics;
560 /* Lay out a UNION_TYPE or QUAL_UNION_TYPE type.
561 Lay out all the fields, set their positions to zero,
562 and compute the size and alignment of the union (maximum of any field).
563 Note that if you set the TYPE_ALIGN before calling this
564 then the union align is aligned to at least that boundary. */
571 unsigned union_align = BITS_PER_UNIT;
573 /* The size of the union, based on the fields scanned so far,
574 is max (CONST_SIZE, VAR_SIZE).
575 VAR_SIZE may be null; then CONST_SIZE by itself is the size. */
576 register int const_size = 0;
577 register tree var_size = 0;
579 #ifdef STRUCTURE_SIZE_BOUNDARY
580 /* Packed structures don't need to have minimum size. */
581 if (! TYPE_PACKED (rec))
582 union_align = STRUCTURE_SIZE_BOUNDARY;
585 /* If this is a QUAL_UNION_TYPE, we want to process the fields in
586 the reverse order in building the COND_EXPR that denotes its
587 size. We reverse them again later. */
588 if (TREE_CODE (rec) == QUAL_UNION_TYPE)
589 TYPE_FIELDS (rec) = nreverse (TYPE_FIELDS (rec));
591 for (field = TYPE_FIELDS (rec); field; field = TREE_CHAIN (field))
593 /* Enums which are local to this class need not be laid out. */
594 if (TREE_CODE (field) == CONST_DECL || TREE_CODE (field) == TYPE_DECL)
597 layout_decl (field, 0);
598 DECL_FIELD_BITPOS (field) = bitsize_int (0L, 0L);
600 /* Union must be at least as aligned as any field requires. */
602 union_align = MAX (union_align, DECL_ALIGN (field));
604 #ifdef PCC_BITFIELD_TYPE_MATTERS
605 /* On the m88000, a bit field of declare type `int'
606 forces the entire union to have `int' alignment. */
607 if (PCC_BITFIELD_TYPE_MATTERS && DECL_BIT_FIELD_TYPE (field))
608 union_align = MAX (union_align, TYPE_ALIGN (TREE_TYPE (field)));
611 if (TREE_CODE (rec) == UNION_TYPE)
613 /* Set union_size to max (decl_size, union_size).
614 There are more and less general ways to do this.
615 Use only CONST_SIZE unless forced to use VAR_SIZE. */
617 if (TREE_CODE (DECL_SIZE (field)) == INTEGER_CST)
619 = MAX (const_size, TREE_INT_CST_LOW (DECL_SIZE (field)));
620 else if (var_size == 0)
621 var_size = DECL_SIZE (field);
623 var_size = size_binop (MAX_EXPR, var_size, DECL_SIZE (field));
625 else if (TREE_CODE (rec) == QUAL_UNION_TYPE)
626 var_size = fold (build (COND_EXPR, sizetype, DECL_QUALIFIER (field),
628 var_size ? var_size : bitsize_int (0L, 0L)));
631 if (TREE_CODE (rec) == QUAL_UNION_TYPE)
632 TYPE_FIELDS (rec) = nreverse (TYPE_FIELDS (rec));
634 /* Determine the ultimate size of the union (in bytes). */
635 if (NULL == var_size)
636 TYPE_SIZE (rec) = bitsize_int (CEIL (const_size, BITS_PER_UNIT)
637 * BITS_PER_UNIT, 0L);
638 else if (const_size == 0)
639 TYPE_SIZE (rec) = var_size;
641 TYPE_SIZE (rec) = size_binop (MAX_EXPR, var_size,
642 round_up (bitsize_int (const_size, 0L),
645 /* Determine the desired alignment. */
646 #ifdef ROUND_TYPE_ALIGN
647 TYPE_ALIGN (rec) = ROUND_TYPE_ALIGN (rec, TYPE_ALIGN (rec), union_align);
649 TYPE_ALIGN (rec) = MAX (TYPE_ALIGN (rec), union_align);
652 #ifdef ROUND_TYPE_SIZE
653 TYPE_SIZE (rec) = ROUND_TYPE_SIZE (rec, TYPE_SIZE (rec), TYPE_ALIGN (rec));
655 /* Round the size up to be a multiple of the required alignment */
656 TYPE_SIZE (rec) = round_up (TYPE_SIZE (rec), TYPE_ALIGN (rec));
660 /* Calculate the mode, size, and alignment for TYPE.
661 For an array type, calculate the element separation as well.
662 Record TYPE on the chain of permanent or temporary types
663 so that dbxout will find out about it.
665 TYPE_SIZE of a type is nonzero if the type has been laid out already.
666 layout_type does nothing on such a type.
668 If the type is incomplete, its TYPE_SIZE remains zero. */
675 tree pending_statics;
680 /* Do nothing if type has been laid out before. */
681 if (TYPE_SIZE (type))
684 /* Make sure all nodes we allocate are not momentary;
685 they must last past the current statement. */
686 old = suspend_momentary ();
688 /* Put all our nodes into the same obstack as the type. Also,
689 make expressions saveable (this is a no-op for permanent types). */
691 push_obstacks (TYPE_OBSTACK (type), TYPE_OBSTACK (type));
692 saveable_allocation ();
694 switch (TREE_CODE (type))
697 /* This kind of type is the responsibility
698 of the language-specific code. */
701 case BOOLEAN_TYPE: /* Used for Java, Pascal, and Chill. */
702 if (TYPE_PRECISION (type) == 0)
703 TYPE_PRECISION (type) = 1; /* default to one byte/boolean. */
704 /* ... fall through ... */
709 if (TREE_CODE (TYPE_MIN_VALUE (type)) == INTEGER_CST
710 && tree_int_cst_sgn (TYPE_MIN_VALUE (type)) >= 0)
711 TREE_UNSIGNED (type) = 1;
713 TYPE_MODE (type) = smallest_mode_for_size (TYPE_PRECISION (type),
715 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)), 0L);
719 TYPE_MODE (type) = mode_for_size (TYPE_PRECISION (type), MODE_FLOAT, 0);
720 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)), 0L);
724 TREE_UNSIGNED (type) = TREE_UNSIGNED (TREE_TYPE (type));
726 = mode_for_size (2 * TYPE_PRECISION (TREE_TYPE (type)),
727 (TREE_CODE (TREE_TYPE (type)) == INTEGER_TYPE
728 ? MODE_COMPLEX_INT : MODE_COMPLEX_FLOAT),
730 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)), 0L);
734 TYPE_SIZE (type) = size_zero_node;
735 TYPE_ALIGN (type) = 1;
736 TYPE_MODE (type) = VOIDmode;
740 TYPE_SIZE (type) = bitsize_int (POINTER_SIZE, 0L);
741 TYPE_MODE (type) = ptr_mode;
746 TYPE_MODE (type) = mode_for_size (2 * POINTER_SIZE, MODE_INT, 0);
747 TYPE_SIZE (type) = size_int (2 * POINTER_SIZE);
752 TYPE_MODE (type) = ptr_mode;
753 TYPE_SIZE (type) = bitsize_int (POINTER_SIZE, 0L);
754 TREE_UNSIGNED (type) = 1;
755 TYPE_PRECISION (type) = POINTER_SIZE;
760 register tree index = TYPE_DOMAIN (type);
761 register tree element = TREE_TYPE (type);
763 build_pointer_type (element);
765 /* We need to know both bounds in order to compute the size. */
766 if (index && TYPE_MAX_VALUE (index) && TYPE_MIN_VALUE (index)
767 && TYPE_SIZE (element))
769 tree ub = TYPE_MAX_VALUE (index);
770 tree lb = TYPE_MIN_VALUE (index);
773 /* If UB is max (lb - 1, x), remove the MAX_EXPR since the
774 test for negative below covers it. */
775 if (TREE_CODE (ub) == MAX_EXPR
776 && TREE_CODE (TREE_OPERAND (ub, 0)) == MINUS_EXPR
777 && integer_onep (TREE_OPERAND (TREE_OPERAND (ub, 0), 1))
778 && operand_equal_p (TREE_OPERAND (TREE_OPERAND (ub, 0), 0),
780 ub = TREE_OPERAND (ub, 1);
781 else if (TREE_CODE (ub) == MAX_EXPR
782 && TREE_CODE (TREE_OPERAND (ub, 1)) == MINUS_EXPR
783 && integer_onep (TREE_OPERAND (TREE_OPERAND (ub, 1), 1))
784 && operand_equal_p (TREE_OPERAND (TREE_OPERAND (ub, 1),
787 ub = TREE_OPERAND (ub, 0);
789 /* The initial subtraction should happen in the original type so
790 that (possible) negative values are handled appropriately. */
791 length = size_binop (PLUS_EXPR, size_one_node,
792 fold (build (MINUS_EXPR, TREE_TYPE (lb),
795 /* If neither bound is a constant and sizetype is signed, make
796 sure the size is never negative. We should really do this
797 if *either* bound is non-constant, but this is the best
798 compromise between C and Ada. */
799 if (! TREE_UNSIGNED (sizetype)
800 && TREE_CODE (TYPE_MIN_VALUE (index)) != INTEGER_CST
801 && TREE_CODE (TYPE_MAX_VALUE (index)) != INTEGER_CST)
802 length = size_binop (MAX_EXPR, length, size_zero_node);
804 TYPE_SIZE (type) = size_binop (MULT_EXPR, TYPE_SIZE (element),
808 /* Now round the alignment and size,
809 using machine-dependent criteria if any. */
811 #ifdef ROUND_TYPE_ALIGN
813 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (element), BITS_PER_UNIT);
815 TYPE_ALIGN (type) = MAX (TYPE_ALIGN (element), BITS_PER_UNIT);
818 #ifdef ROUND_TYPE_SIZE
819 if (TYPE_SIZE (type) != 0)
821 = ROUND_TYPE_SIZE (type, TYPE_SIZE (type), TYPE_ALIGN (type));
824 TYPE_MODE (type) = BLKmode;
825 if (TYPE_SIZE (type) != 0
826 && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
827 /* BLKmode elements force BLKmode aggregate;
828 else extract/store fields may lose. */
829 && (TYPE_MODE (TREE_TYPE (type)) != BLKmode
830 || TYPE_NO_FORCE_BLK (TREE_TYPE (type))))
833 = mode_for_size (TREE_INT_CST_LOW (TYPE_SIZE (type)),
836 if (STRICT_ALIGNMENT && TYPE_ALIGN (type) < BIGGEST_ALIGNMENT
837 && TYPE_ALIGN (type) < TREE_INT_CST_LOW (TYPE_SIZE (type))
838 && TYPE_MODE (type) != BLKmode)
840 TYPE_NO_FORCE_BLK (type) = 1;
841 TYPE_MODE (type) = BLKmode;
848 pending_statics = layout_record (type);
849 TYPE_MODE (type) = BLKmode;
850 if (TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST)
853 enum machine_mode mode = VOIDmode;
855 /* A record which has any BLKmode members must itself be BLKmode;
856 it can't go in a register.
857 Unless the member is BLKmode only because it isn't aligned. */
858 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
862 if (TREE_CODE (field) != FIELD_DECL)
865 if (TYPE_MODE (TREE_TYPE (field)) == BLKmode
866 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field)))
869 if (TREE_CODE (DECL_FIELD_BITPOS (field)) != INTEGER_CST)
872 bitpos = TREE_INT_CST_LOW (DECL_FIELD_BITPOS (field));
874 /* Must be BLKmode if any field crosses a word boundary,
875 since extract_bit_field can't handle that in registers. */
876 if (bitpos / BITS_PER_WORD
877 != ((TREE_INT_CST_LOW (DECL_SIZE (field)) + bitpos - 1)
879 /* But there is no problem if the field is entire words. */
880 && TREE_INT_CST_LOW (DECL_SIZE (field)) % BITS_PER_WORD != 0)
883 /* If this field is the whole struct, remember its mode so
884 that, say, we can put a double in a class into a DF
885 register instead of forcing it to live in the stack. */
886 if (simple_cst_equal (TYPE_SIZE (type), DECL_SIZE (field)))
887 mode = DECL_MODE (field);
890 if (mode != VOIDmode)
891 /* We only have one real field; use its mode. */
892 TYPE_MODE (type) = mode;
895 = mode_for_size (TREE_INT_CST_LOW (TYPE_SIZE (type)),
898 /* If structure's known alignment is less than
899 what the scalar mode would need, and it matters,
900 then stick with BLKmode. */
902 && ! (TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT
903 || (TYPE_ALIGN (type)
904 >= TREE_INT_CST_LOW (TYPE_SIZE (type)))))
906 if (TYPE_MODE (type) != BLKmode)
907 /* If this is the only reason this type is BLKmode,
908 then don't force containing types to be BLKmode. */
909 TYPE_NO_FORCE_BLK (type) = 1;
910 TYPE_MODE (type) = BLKmode;
916 /* Lay out any static members. This is done now
917 because their type may use the record's type. */
918 while (pending_statics)
920 layout_decl (TREE_VALUE (pending_statics), 0);
921 pending_statics = TREE_CHAIN (pending_statics);
926 case QUAL_UNION_TYPE:
928 TYPE_MODE (type) = BLKmode;
929 if (TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
930 /* If structure's known alignment is less than
931 what the scalar mode would need, and it matters,
932 then stick with BLKmode. */
933 && (! STRICT_ALIGNMENT
934 || TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT
935 || TYPE_ALIGN (type) >= TREE_INT_CST_LOW (TYPE_SIZE (type))))
938 /* A union which has any BLKmode members must itself be BLKmode;
939 it can't go in a register.
940 Unless the member is BLKmode only because it isn't aligned. */
941 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
943 if (TREE_CODE (field) != FIELD_DECL)
946 if (TYPE_MODE (TREE_TYPE (field)) == BLKmode
947 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field)))
952 = mode_for_size (TREE_INT_CST_LOW (TYPE_SIZE (type)),
959 case SET_TYPE: /* Used by Chill and Pascal. */
960 if (TREE_CODE (TYPE_MAX_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST
961 || TREE_CODE (TYPE_MIN_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST)
965 #ifndef SET_WORD_SIZE
966 #define SET_WORD_SIZE BITS_PER_WORD
968 int alignment = set_alignment ? set_alignment : SET_WORD_SIZE;
970 = (TREE_INT_CST_LOW (TYPE_MAX_VALUE (TYPE_DOMAIN (type)))
971 - TREE_INT_CST_LOW (TYPE_MIN_VALUE (TYPE_DOMAIN (type))) + 1);
973 = ((size_in_bits + alignment - 1) / alignment) * alignment;
974 if (rounded_size > alignment)
975 TYPE_MODE (type) = BLKmode;
977 TYPE_MODE (type) = mode_for_size (alignment, MODE_INT, 1);
978 TYPE_SIZE (type) = bitsize_int (rounded_size, 0L);
979 TYPE_ALIGN (type) = alignment;
980 TYPE_PRECISION (type) = size_in_bits;
985 /* The size may vary in different languages, so the language front end
986 should fill in the size. */
987 TYPE_ALIGN (type) = BIGGEST_ALIGNMENT;
988 TYPE_MODE (type) = BLKmode;
995 /* Normally, use the alignment corresponding to the mode chosen.
996 However, where strict alignment is not required, avoid
997 over-aligning structures, since most compilers do not do this
1000 if (TYPE_MODE (type) != BLKmode && TYPE_MODE (type) != VOIDmode
1001 && (STRICT_ALIGNMENT
1002 || (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE
1003 && TREE_CODE (type) != QUAL_UNION_TYPE
1004 && TREE_CODE (type) != ARRAY_TYPE)))
1005 TYPE_ALIGN (type) = GET_MODE_ALIGNMENT (TYPE_MODE (type));
1007 /* Evaluate nonconstant size only once, either now or as soon as safe. */
1008 if (TYPE_SIZE (type) != 0 && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
1009 TYPE_SIZE (type) = variable_size (TYPE_SIZE (type));
1011 /* Also layout any other variants of the type. */
1012 if (TYPE_NEXT_VARIANT (type)
1013 || type != TYPE_MAIN_VARIANT (type))
1016 /* Record layout info of this variant. */
1017 tree size = TYPE_SIZE (type);
1018 int align = TYPE_ALIGN (type);
1019 enum machine_mode mode = TYPE_MODE (type);
1021 /* Copy it into all variants. */
1022 for (variant = TYPE_MAIN_VARIANT (type);
1024 variant = TYPE_NEXT_VARIANT (variant))
1026 TYPE_SIZE (variant) = size;
1027 TYPE_ALIGN (variant) = align;
1028 TYPE_MODE (variant) = mode;
1033 resume_momentary (old);
1036 /* Create and return a type for signed integers of PRECISION bits. */
1039 make_signed_type (precision)
1042 register tree type = make_node (INTEGER_TYPE);
1044 TYPE_PRECISION (type) = precision;
1046 /* Create the extreme values based on the number of bits. */
1048 TYPE_MIN_VALUE (type)
1049 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1050 ? 0 : (HOST_WIDE_INT) (-1) << (precision - 1)),
1051 (((HOST_WIDE_INT) (-1)
1052 << (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1053 ? precision - HOST_BITS_PER_WIDE_INT - 1
1055 TYPE_MAX_VALUE (type)
1056 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1057 ? -1 : ((HOST_WIDE_INT) 1 << (precision - 1)) - 1),
1058 (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1059 ? (((HOST_WIDE_INT) 1
1060 << (precision - HOST_BITS_PER_WIDE_INT - 1))) - 1
1063 /* Give this type's extreme values this type as their type. */
1065 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
1066 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
1068 /* The first type made with this or `make_unsigned_type'
1069 is the type for size values. */
1072 set_sizetype (type);
1074 /* Lay out the type: set its alignment, size, etc. */
1081 /* Create and return a type for unsigned integers of PRECISION bits. */
1084 make_unsigned_type (precision)
1087 register tree type = make_node (INTEGER_TYPE);
1089 TYPE_PRECISION (type) = precision;
1091 /* The first type made with this or `make_signed_type'
1092 is the type for size values. */
1096 TREE_UNSIGNED (type) = 1;
1097 set_sizetype (type);
1100 fixup_unsigned_type (type);
1104 /* Set sizetype to TYPE, and initialize *bitsizetype accordingly.
1105 Also update the type of any standard type's sizes made so far. */
1111 int precision = TYPE_PRECISION (type);
1115 /* The *bitsizetype types use a precision that avoids overflows when
1116 calculating signed sizes / offsets in bits.
1118 We are allocating bitsizetype once and change it in place when
1119 we decide later that we want to change it. This way, we avoid the
1120 hassle of changing all the TYPE_SIZE (TREE_TYPE (sometype))
1121 individually in each front end. */
1123 bitsizetype = make_node (INTEGER_TYPE);
1125 precision += BITS_PER_UNIT_LOG + 1;
1126 /* However, when cross-compiling from a 32 bit to a 64 bit host,
1127 we are limited to 64 bit precision. */
1128 if (precision > 2 * HOST_BITS_PER_WIDE_INT)
1129 precision = 2 * HOST_BITS_PER_WIDE_INT;
1130 TYPE_PRECISION (bitsizetype) = precision;
1131 (TREE_UNSIGNED (type) ? fixup_unsigned_type : fixup_signed_type)
1133 layout_type (bitsizetype);
1135 sbitsizetype = make_signed_type (precision);
1136 ubitsizetype = make_unsigned_type (precision);
1139 /* Set the extreme values of TYPE based on its precision in bits,
1140 then lay it out. Used when make_signed_type won't do
1141 because the tree code is not INTEGER_TYPE.
1142 E.g. for Pascal, when the -fsigned-char option is given. */
1145 fixup_signed_type (type)
1148 register int precision = TYPE_PRECISION (type);
1150 TYPE_MIN_VALUE (type)
1151 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1152 ? 0 : (HOST_WIDE_INT) (-1) << (precision - 1)),
1153 (((HOST_WIDE_INT) (-1)
1154 << (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1155 ? precision - HOST_BITS_PER_WIDE_INT - 1
1157 TYPE_MAX_VALUE (type)
1158 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1159 ? -1 : ((HOST_WIDE_INT) 1 << (precision - 1)) - 1),
1160 (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1161 ? (((HOST_WIDE_INT) 1
1162 << (precision - HOST_BITS_PER_WIDE_INT - 1))) - 1
1165 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
1166 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
1168 /* Lay out the type: set its alignment, size, etc. */
1173 /* Set the extreme values of TYPE based on its precision in bits,
1174 then lay it out. This is used both in `make_unsigned_type'
1175 and for enumeral types. */
1178 fixup_unsigned_type (type)
1181 register int precision = TYPE_PRECISION (type);
1183 TYPE_MIN_VALUE (type) = build_int_2 (0, 0);
1184 TYPE_MAX_VALUE (type)
1185 = build_int_2 (precision - HOST_BITS_PER_WIDE_INT >= 0
1186 ? -1 : ((HOST_WIDE_INT) 1 << precision) - 1,
1187 precision - HOST_BITS_PER_WIDE_INT > 0
1188 ? ((unsigned HOST_WIDE_INT) ~0
1189 >> (HOST_BITS_PER_WIDE_INT
1190 - (precision - HOST_BITS_PER_WIDE_INT)))
1192 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
1193 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
1195 /* Lay out the type: set its alignment, size, etc. */
1200 /* Find the best machine mode to use when referencing a bit field of length
1201 BITSIZE bits starting at BITPOS.
1203 The underlying object is known to be aligned to a boundary of ALIGN bits.
1204 If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
1205 larger than LARGEST_MODE (usually SImode).
1207 If no mode meets all these conditions, we return VOIDmode. Otherwise, if
1208 VOLATILEP is true or SLOW_BYTE_ACCESS is false, we return the smallest
1209 mode meeting these conditions.
1211 Otherwise (VOLATILEP is false and SLOW_BYTE_ACCESS is true), we return
1212 the largest mode (but a mode no wider than UNITS_PER_WORD) that meets
1213 all the conditions. */
1216 get_best_mode (bitsize, bitpos, align, largest_mode, volatilep)
1217 int bitsize, bitpos;
1219 enum machine_mode largest_mode;
1222 enum machine_mode mode;
1225 /* Find the narrowest integer mode that contains the bit field. */
1226 for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
1227 mode = GET_MODE_WIDER_MODE (mode))
1229 unit = GET_MODE_BITSIZE (mode);
1230 if ((bitpos % unit) + bitsize <= unit)
1234 if (mode == MAX_MACHINE_MODE
1235 /* It is tempting to omit the following line
1236 if STRICT_ALIGNMENT is true.
1237 But that is incorrect, since if the bitfield uses part of 3 bytes
1238 and we use a 4-byte mode, we could get a spurious segv
1239 if the extra 4th byte is past the end of memory.
1240 (Though at least one Unix compiler ignores this problem:
1241 that on the Sequent 386 machine. */
1242 || MIN (unit, BIGGEST_ALIGNMENT) > align
1243 || (largest_mode != VOIDmode && unit > GET_MODE_BITSIZE (largest_mode)))
1246 if (SLOW_BYTE_ACCESS && ! volatilep)
1248 enum machine_mode wide_mode = VOIDmode, tmode;
1250 for (tmode = GET_CLASS_NARROWEST_MODE (MODE_INT); tmode != VOIDmode;
1251 tmode = GET_MODE_WIDER_MODE (tmode))
1253 unit = GET_MODE_BITSIZE (tmode);
1254 if (bitpos / unit == (bitpos + bitsize - 1) / unit
1255 && unit <= BITS_PER_WORD
1256 && unit <= MIN (align, BIGGEST_ALIGNMENT)
1257 && (largest_mode == VOIDmode
1258 || unit <= GET_MODE_BITSIZE (largest_mode)))
1262 if (wide_mode != VOIDmode)
1269 /* Save all variables describing the current status into the structure *P.
1270 This is used before starting a nested function. */
1273 save_storage_status (p)
1276 #if 0 /* Need not save, since always 0 and non0 (resp.) within a function. */
1277 p->pending_sizes = pending_sizes;
1278 p->immediate_size_expand = immediate_size_expand;
1282 /* Restore all variables describing the current status from the structure *P.
1283 This is used after a nested function. */
1286 restore_storage_status (p)
1290 pending_sizes = p->pending_sizes;
1291 immediate_size_expand = p->immediate_size_expand;