1 /* C-compiler utilities for types and variables storage layout
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1996, 1998,
3 1999, 2000 Free Software Foundation, Inc.
5 This file is part of GNU CC.
7 GNU CC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GNU CC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GNU CC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
34 /* Set to one when set_sizetype has been called. */
35 static int sizetype_set;
37 /* List of types created before set_sizetype has been called. We do not
38 make this a GGC root since we want these nodes to be reclaimed. */
39 static tree early_type_list;
41 /* Data type for the expressions representing sizes of data types.
42 It is the first integer type laid out. */
43 tree sizetype_tab[(int) TYPE_KIND_LAST];
45 /* If nonzero, this is an upper limit on alignment of structure fields.
46 The value is measured in bits. */
47 unsigned int maximum_field_alignment;
49 /* If non-zero, the alignment of a bitstring or (power-)set value, in bits.
50 May be overridden by front-ends. */
51 unsigned int set_alignment = 0;
53 static void finalize_record_size PARAMS ((record_layout_info));
54 static void finalize_type_size PARAMS ((tree));
55 static void place_union_field PARAMS ((record_layout_info, tree));
56 extern void debug_rli PARAMS ((record_layout_info));
58 /* SAVE_EXPRs for sizes of types and decls, waiting to be expanded. */
60 static tree pending_sizes;
62 /* Nonzero means cannot safely call expand_expr now,
63 so put variable sizes onto `pending_sizes' instead. */
65 int immediate_size_expand;
67 /* Get a list of all the objects put on the pending sizes list. */
72 tree chain = pending_sizes;
75 /* Put each SAVE_EXPR into the current function. */
76 for (t = chain; t; t = TREE_CHAIN (t))
77 SAVE_EXPR_CONTEXT (TREE_VALUE (t)) = current_function_decl;
83 /* Put a chain of objects into the pending sizes list, which must be
87 put_pending_sizes (chain)
93 pending_sizes = chain;
96 /* Given a size SIZE that may not be a constant, return a SAVE_EXPR
97 to serve as the actual size-expression for a type or decl. */
103 /* If the language-processor is to take responsibility for variable-sized
104 items (e.g., languages which have elaboration procedures like Ada),
105 just return SIZE unchanged. Likewise for self-referential sizes. */
106 if (TREE_CONSTANT (size)
107 || global_bindings_p () < 0 || contains_placeholder_p (size))
110 size = save_expr (size);
112 /* If an array with a variable number of elements is declared, and
113 the elements require destruction, we will emit a cleanup for the
114 array. That cleanup is run both on normal exit from the block
115 and in the exception-handler for the block. Normally, when code
116 is used in both ordinary code and in an exception handler it is
117 `unsaved', i.e., all SAVE_EXPRs are recalculated. However, we do
118 not wish to do that here; the array-size is the same in both
120 if (TREE_CODE (size) == SAVE_EXPR)
121 SAVE_EXPR_PERSISTENT_P (size) = 1;
123 if (global_bindings_p ())
125 if (TREE_CONSTANT (size))
126 error ("type size can't be explicitly evaluated");
128 error ("variable-size type declared outside of any function");
130 return size_one_node;
133 if (immediate_size_expand)
134 /* NULL_RTX is not defined; neither is the rtx type.
135 Also, we would like to pass const0_rtx here, but don't have it. */
136 expand_expr (size, expand_expr (integer_zero_node, NULL_PTR, VOIDmode, 0),
138 else if (cfun != 0 && cfun->x_dont_save_pending_sizes_p)
139 /* The front-end doesn't want us to keep a list of the expressions
140 that determine sizes for variable size objects. */
142 else if (TREE_CODE (size) == SAVE_EXPR)
143 pending_sizes = tree_cons (NULL_TREE, size, pending_sizes);
148 #ifndef MAX_FIXED_MODE_SIZE
149 #define MAX_FIXED_MODE_SIZE GET_MODE_BITSIZE (DImode)
152 /* Return the machine mode to use for a nonscalar of SIZE bits.
153 The mode must be in class CLASS, and have exactly that many bits.
154 If LIMIT is nonzero, modes of wider than MAX_FIXED_MODE_SIZE will not
158 mode_for_size (size, class, limit)
160 enum mode_class class;
163 register enum machine_mode mode;
165 if (limit && size > MAX_FIXED_MODE_SIZE)
168 /* Get the first mode which has this size, in the specified class. */
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 /* Similar, except passed a tree node. */
180 mode_for_size_tree (size, class, limit)
182 enum mode_class class;
185 if (TREE_CODE (size) != INTEGER_CST
186 /* What we really want to say here is that the size can fit in a
187 host integer, but we know there's no way we'd find a mode for
188 this many bits, so there's no point in doing the precise test. */
189 || compare_tree_int (size, 1000) > 0)
192 return mode_for_size (TREE_INT_CST_LOW (size), class, limit);
195 /* Similar, but never return BLKmode; return the narrowest mode that
196 contains at least the requested number of bits. */
199 smallest_mode_for_size (size, class)
201 enum mode_class class;
203 register enum machine_mode mode;
205 /* Get the first mode which has at least this size, in the
207 for (mode = GET_CLASS_NARROWEST_MODE (class); mode != VOIDmode;
208 mode = GET_MODE_WIDER_MODE (mode))
209 if (GET_MODE_BITSIZE (mode) >= size)
215 /* Find an integer mode of the exact same size, or BLKmode on failure. */
218 int_mode_for_mode (mode)
219 enum machine_mode mode;
221 switch (GET_MODE_CLASS (mode))
224 case MODE_PARTIAL_INT:
227 case MODE_COMPLEX_INT:
228 case MODE_COMPLEX_FLOAT:
230 case MODE_VECTOR_INT:
231 case MODE_VECTOR_FLOAT:
232 mode = mode_for_size (GET_MODE_BITSIZE (mode), MODE_INT, 0);
239 /* ... fall through ... */
249 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
250 This can only be applied to objects of a sizetype. */
253 round_up (value, divisor)
257 tree arg = size_int_type (divisor, TREE_TYPE (value));
259 return size_binop (MULT_EXPR, size_binop (CEIL_DIV_EXPR, value, arg), arg);
262 /* Likewise, but round down. */
265 round_down (value, divisor)
269 tree arg = size_int_type (divisor, TREE_TYPE (value));
271 return size_binop (MULT_EXPR, size_binop (FLOOR_DIV_EXPR, value, arg), arg);
274 /* Set the size, mode and alignment of a ..._DECL node.
275 TYPE_DECL does need this for C++.
276 Note that LABEL_DECL and CONST_DECL nodes do not need this,
277 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
278 Don't call layout_decl for them.
280 KNOWN_ALIGN is the amount of alignment we can assume this
281 decl has with no special effort. It is relevant only for FIELD_DECLs
282 and depends on the previous fields.
283 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
284 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
285 the record will be aligned to suit. */
288 layout_decl (decl, known_align)
290 unsigned int known_align;
292 register tree type = TREE_TYPE (decl);
293 register enum tree_code code = TREE_CODE (decl);
295 if (code == CONST_DECL)
297 else if (code != VAR_DECL && code != PARM_DECL && code != RESULT_DECL
298 && code != TYPE_DECL && code != FIELD_DECL)
301 if (type == error_mark_node)
302 type = void_type_node;
304 /* Usually the size and mode come from the data type without change,
305 however, the front-end may set the explicit width of the field, so its
306 size may not be the same as the size of its type. This happens with
307 bitfields, of course (an `int' bitfield may be only 2 bits, say), but it
308 also happens with other fields. For example, the C++ front-end creates
309 zero-sized fields corresponding to empty base classes, and depends on
310 layout_type setting DECL_FIELD_BITPOS correctly for the field. Set the
311 size in bytes from the size in bits. If we have already set the mode,
312 don't set it again since we can be called twice for FIELD_DECLs. */
314 TREE_UNSIGNED (decl) = TREE_UNSIGNED (type);
315 if (DECL_MODE (decl) == VOIDmode)
316 DECL_MODE (decl) = TYPE_MODE (type);
318 if (DECL_SIZE (decl) == 0)
320 DECL_SIZE (decl) = TYPE_SIZE (type);
321 DECL_SIZE_UNIT (decl) = TYPE_SIZE_UNIT (type);
324 DECL_SIZE_UNIT (decl)
325 = convert (sizetype, size_binop (CEIL_DIV_EXPR, DECL_SIZE (decl),
328 /* Force alignment required for the data type.
329 But if the decl itself wants greater alignment, don't override that.
330 Likewise, if the decl is packed, don't override it. */
331 if (! (code == FIELD_DECL && DECL_BIT_FIELD (decl))
332 && (DECL_ALIGN (decl) == 0
333 || (! (code == FIELD_DECL && DECL_PACKED (decl))
334 && TYPE_ALIGN (type) > DECL_ALIGN (decl))))
336 DECL_ALIGN (decl) = TYPE_ALIGN (type);
337 DECL_USER_ALIGN (decl) = TYPE_USER_ALIGN (type);
340 /* For fields, set the bit field type and update the alignment. */
341 if (code == FIELD_DECL)
343 DECL_BIT_FIELD_TYPE (decl) = DECL_BIT_FIELD (decl) ? type : 0;
344 if (maximum_field_alignment != 0)
345 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), maximum_field_alignment);
346 else if (DECL_PACKED (decl))
348 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), BITS_PER_UNIT);
349 DECL_USER_ALIGN (decl) = 0;
353 /* See if we can use an ordinary integer mode for a bit-field.
354 Conditions are: a fixed size that is correct for another mode
355 and occupying a complete byte or bytes on proper boundary. */
356 if (code == FIELD_DECL && DECL_BIT_FIELD (decl)
357 && TYPE_SIZE (type) != 0
358 && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
359 && GET_MODE_CLASS (TYPE_MODE (type)) == MODE_INT)
361 register enum machine_mode xmode
362 = mode_for_size_tree (DECL_SIZE (decl), MODE_INT, 1);
364 if (xmode != BLKmode && known_align >= GET_MODE_ALIGNMENT (xmode))
366 DECL_ALIGN (decl) = MAX (GET_MODE_ALIGNMENT (xmode),
368 DECL_MODE (decl) = xmode;
369 DECL_BIT_FIELD (decl) = 0;
373 /* Turn off DECL_BIT_FIELD if we won't need it set. */
374 if (code == FIELD_DECL && DECL_BIT_FIELD (decl)
375 && TYPE_MODE (type) == BLKmode && DECL_MODE (decl) == BLKmode
376 && known_align >= TYPE_ALIGN (type)
377 && DECL_ALIGN (decl) >= TYPE_ALIGN (type)
378 && DECL_SIZE_UNIT (decl) != 0)
379 DECL_BIT_FIELD (decl) = 0;
381 /* Evaluate nonconstant size only once, either now or as soon as safe. */
382 if (DECL_SIZE (decl) != 0 && TREE_CODE (DECL_SIZE (decl)) != INTEGER_CST)
383 DECL_SIZE (decl) = variable_size (DECL_SIZE (decl));
384 if (DECL_SIZE_UNIT (decl) != 0
385 && TREE_CODE (DECL_SIZE_UNIT (decl)) != INTEGER_CST)
386 DECL_SIZE_UNIT (decl) = variable_size (DECL_SIZE_UNIT (decl));
388 /* If requested, warn about definitions of large data objects. */
390 && (code == VAR_DECL || code == PARM_DECL)
391 && ! DECL_EXTERNAL (decl))
393 tree size = DECL_SIZE_UNIT (decl);
395 if (size != 0 && TREE_CODE (size) == INTEGER_CST
396 && compare_tree_int (size, larger_than_size) > 0)
398 unsigned int size_as_int = TREE_INT_CST_LOW (size);
400 if (compare_tree_int (size, size_as_int) == 0)
401 warning_with_decl (decl, "size of `%s' is %d bytes", size_as_int);
403 warning_with_decl (decl, "size of `%s' is larger than %d bytes",
409 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
410 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
411 is to be passed to all other layout functions for this record. It is the
412 responsibility of the caller to call `free' for the storage returned.
413 Note that garbage collection is not permitted until we finish laying
417 start_record_layout (t)
420 record_layout_info rli
421 = (record_layout_info) xmalloc (sizeof (struct record_layout_info_s));
425 /* If the type has a minimum specified alignment (via an attribute
426 declaration, for example) use it -- otherwise, start with a
427 one-byte alignment. */
428 rli->record_align = MAX (BITS_PER_UNIT, TYPE_ALIGN (t));
429 rli->unpacked_align = rli->record_align;
430 rli->offset_align = MAX (rli->record_align, BIGGEST_ALIGNMENT);
432 #ifdef STRUCTURE_SIZE_BOUNDARY
433 /* Packed structures don't need to have minimum size. */
434 if (! TYPE_PACKED (t))
435 rli->record_align = MAX (rli->record_align, STRUCTURE_SIZE_BOUNDARY);
438 rli->offset = size_zero_node;
439 rli->bitpos = bitsize_zero_node;
440 rli->pending_statics = 0;
441 rli->packed_maybe_necessary = 0;
446 /* These four routines perform computations that convert between
447 the offset/bitpos forms and byte and bit offsets. */
450 bit_from_pos (offset, bitpos)
453 return size_binop (PLUS_EXPR, bitpos,
454 size_binop (MULT_EXPR, convert (bitsizetype, offset),
459 byte_from_pos (offset, bitpos)
462 return size_binop (PLUS_EXPR, offset,
464 size_binop (TRUNC_DIV_EXPR, bitpos,
465 bitsize_unit_node)));
469 pos_from_byte (poffset, pbitpos, off_align, pos)
470 tree *poffset, *pbitpos;
471 unsigned int off_align;
475 = size_binop (MULT_EXPR,
477 size_binop (FLOOR_DIV_EXPR, pos,
478 bitsize_int (off_align
480 size_int (off_align / BITS_PER_UNIT));
481 *pbitpos = size_binop (MULT_EXPR,
482 size_binop (FLOOR_MOD_EXPR, pos,
483 bitsize_int (off_align / BITS_PER_UNIT)),
488 pos_from_bit (poffset, pbitpos, off_align, pos)
489 tree *poffset, *pbitpos;
490 unsigned int off_align;
493 *poffset = size_binop (MULT_EXPR,
495 size_binop (FLOOR_DIV_EXPR, pos,
496 bitsize_int (off_align))),
497 size_int (off_align / BITS_PER_UNIT));
498 *pbitpos = size_binop (FLOOR_MOD_EXPR, pos, bitsize_int (off_align));
501 /* Given a pointer to bit and byte offsets and an offset alignment,
502 normalize the offsets so they are within the alignment. */
505 normalize_offset (poffset, pbitpos, off_align)
506 tree *poffset, *pbitpos;
507 unsigned int off_align;
509 /* If the bit position is now larger than it should be, adjust it
511 if (compare_tree_int (*pbitpos, off_align) >= 0)
513 tree extra_aligns = size_binop (FLOOR_DIV_EXPR, *pbitpos,
514 bitsize_int (off_align));
517 = size_binop (PLUS_EXPR, *poffset,
518 size_binop (MULT_EXPR, convert (sizetype, extra_aligns),
519 size_int (off_align / BITS_PER_UNIT)));
522 = size_binop (FLOOR_MOD_EXPR, *pbitpos, bitsize_int (off_align));
526 /* Print debugging information about the information in RLI. */
530 record_layout_info rli;
532 print_node_brief (stderr, "type", rli->t, 0);
533 print_node_brief (stderr, "\noffset", rli->offset, 0);
534 print_node_brief (stderr, " bitpos", rli->bitpos, 0);
536 fprintf (stderr, "\nrec_align = %u, unpack_align = %u, off_align = %u\n",
537 rli->record_align, rli->unpacked_align, rli->offset_align);
538 if (rli->packed_maybe_necessary)
539 fprintf (stderr, "packed may be necessary\n");
541 if (rli->pending_statics)
543 fprintf (stderr, "pending statics:\n");
544 debug_tree (rli->pending_statics);
548 /* Given an RLI with a possibly-incremented BITPOS, adjust OFFSET and
549 BITPOS if necessary to keep BITPOS below OFFSET_ALIGN. */
553 record_layout_info rli;
555 normalize_offset (&rli->offset, &rli->bitpos, rli->offset_align);
558 /* Returns the size in bytes allocated so far. */
561 rli_size_unit_so_far (rli)
562 record_layout_info rli;
564 return byte_from_pos (rli->offset, rli->bitpos);
567 /* Returns the size in bits allocated so far. */
570 rli_size_so_far (rli)
571 record_layout_info rli;
573 return bit_from_pos (rli->offset, rli->bitpos);
576 /* Called from place_field to handle unions. */
579 place_union_field (rli, field)
580 record_layout_info rli;
583 unsigned int desired_align;
585 layout_decl (field, 0);
587 DECL_FIELD_OFFSET (field) = size_zero_node;
588 DECL_FIELD_BIT_OFFSET (field) = bitsize_zero_node;
589 SET_DECL_OFFSET_ALIGN (field, BIGGEST_ALIGNMENT);
591 desired_align = DECL_ALIGN (field);
593 #ifdef BIGGEST_FIELD_ALIGNMENT
594 /* Some targets (i.e. i386) limit union field alignment
595 to a lower boundary than alignment of variables unless
596 it was overridden by attribute aligned. */
597 if (! DECL_USER_ALIGN (field))
599 MIN (desired_align, (unsigned) BIGGEST_FIELD_ALIGNMENT);
602 /* Union must be at least as aligned as any field requires. */
603 rli->record_align = MAX (rli->record_align, desired_align);
605 #ifdef PCC_BITFIELD_TYPE_MATTERS
606 /* On the m88000, a bit field of declare type `int' forces the
607 entire union to have `int' alignment. */
608 if (PCC_BITFIELD_TYPE_MATTERS && DECL_BIT_FIELD_TYPE (field))
609 rli->record_align = MAX (rli->record_align,
610 TYPE_ALIGN (TREE_TYPE (field)));
613 /* We assume the union's size will be a multiple of a byte so we don't
614 bother with BITPOS. */
615 if (TREE_CODE (rli->t) == UNION_TYPE)
616 rli->offset = size_binop (MAX_EXPR, rli->offset, DECL_SIZE_UNIT (field));
617 else if (TREE_CODE (rli->t) == QUAL_UNION_TYPE)
618 rli->offset = fold (build (COND_EXPR, sizetype,
619 DECL_QUALIFIER (field),
620 DECL_SIZE_UNIT (field), rli->offset));
623 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
624 is a FIELD_DECL to be added after those fields already present in
625 T. (FIELD is not actually added to the TYPE_FIELDS list here;
626 callers that desire that behavior must manually perform that step.) */
629 place_field (rli, field)
630 record_layout_info rli;
633 /* The alignment required for FIELD. */
634 unsigned int desired_align;
635 /* The alignment FIELD would have if we just dropped it into the
636 record as it presently stands. */
637 unsigned int known_align;
638 unsigned int actual_align;
639 unsigned int user_align;
640 /* The type of this field. */
641 tree type = TREE_TYPE (field);
643 if (TREE_CODE (field) == ERROR_MARK || TREE_CODE (type) == ERROR_MARK)
646 /* If FIELD is static, then treat it like a separate variable, not
647 really like a structure field. If it is a FUNCTION_DECL, it's a
648 method. In both cases, all we do is lay out the decl, and we do
649 it *after* the record is laid out. */
650 if (TREE_CODE (field) == VAR_DECL)
652 rli->pending_statics = tree_cons (NULL_TREE, field,
653 rli->pending_statics);
657 /* Enumerators and enum types which are local to this class need not
658 be laid out. Likewise for initialized constant fields. */
659 else if (TREE_CODE (field) != FIELD_DECL)
662 /* Unions are laid out very differently than records, so split
663 that code off to another function. */
664 else if (TREE_CODE (rli->t) != RECORD_TYPE)
666 place_union_field (rli, field);
670 /* Work out the known alignment so far. Note that A & (-A) is the
671 value of the least-significant bit in A that is one. */
672 if (! integer_zerop (rli->bitpos))
673 known_align = (tree_low_cst (rli->bitpos, 1)
674 & - tree_low_cst (rli->bitpos, 1));
675 else if (integer_zerop (rli->offset))
676 known_align = BIGGEST_ALIGNMENT;
677 else if (host_integerp (rli->offset, 1))
678 known_align = (BITS_PER_UNIT
679 * (tree_low_cst (rli->offset, 1)
680 & - tree_low_cst (rli->offset, 1)));
682 known_align = rli->offset_align;
684 /* Lay out the field so we know what alignment it needs. For a
685 packed field, use the alignment as specified, disregarding what
686 the type would want. */
687 desired_align = DECL_ALIGN (field);
688 user_align = DECL_USER_ALIGN (field);
689 layout_decl (field, known_align);
690 if (! DECL_PACKED (field))
692 desired_align = DECL_ALIGN (field);
693 user_align = DECL_USER_ALIGN (field);
696 /* Some targets (i.e. i386, VMS) limit struct field alignment
697 to a lower boundary than alignment of variables unless
698 it was overridden by attribute aligned. */
699 #ifdef BIGGEST_FIELD_ALIGNMENT
702 = MIN (desired_align, (unsigned) BIGGEST_FIELD_ALIGNMENT);
705 #ifdef ADJUST_FIELD_ALIGN
706 desired_align = ADJUST_FIELD_ALIGN (field, desired_align);
709 /* Record must have at least as much alignment as any field.
710 Otherwise, the alignment of the field within the record is
712 #ifdef PCC_BITFIELD_TYPE_MATTERS
713 if (PCC_BITFIELD_TYPE_MATTERS && type != error_mark_node
714 && DECL_BIT_FIELD_TYPE (field)
715 && ! integer_zerop (TYPE_SIZE (type)))
717 /* For these machines, a zero-length field does not
718 affect the alignment of the structure as a whole.
719 It does, however, affect the alignment of the next field
720 within the structure. */
721 if (! integer_zerop (DECL_SIZE (field)))
722 rli->record_align = MAX (rli->record_align, desired_align);
723 else if (! DECL_PACKED (field))
724 desired_align = TYPE_ALIGN (type);
726 /* A named bit field of declared type `int'
727 forces the entire structure to have `int' alignment. */
728 if (DECL_NAME (field) != 0)
730 unsigned int type_align = TYPE_ALIGN (type);
732 if (maximum_field_alignment != 0)
733 type_align = MIN (type_align, maximum_field_alignment);
734 else if (DECL_PACKED (field))
735 type_align = MIN (type_align, BITS_PER_UNIT);
737 rli->record_align = MAX (rli->record_align, type_align);
739 rli->unpacked_align = MAX (rli->unpacked_align,
746 rli->record_align = MAX (rli->record_align, desired_align);
747 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
750 if (warn_packed && DECL_PACKED (field))
752 if (known_align > TYPE_ALIGN (type))
754 if (TYPE_ALIGN (type) > desired_align)
756 if (STRICT_ALIGNMENT)
757 warning_with_decl (field, "packed attribute causes inefficient alignment for `%s'");
759 warning_with_decl (field, "packed attribute is unnecessary for `%s'");
763 rli->packed_maybe_necessary = 1;
766 /* Does this field automatically have alignment it needs by virtue
767 of the fields that precede it and the record's own alignment? */
768 if (known_align < desired_align)
770 /* No, we need to skip space before this field.
771 Bump the cumulative size to multiple of field alignment. */
774 warning_with_decl (field, "padding struct to align `%s'");
776 /* If the alignment is still within offset_align, just align
778 if (desired_align < rli->offset_align)
779 rli->bitpos = round_up (rli->bitpos, desired_align);
782 /* First adjust OFFSET by the partial bits, then align. */
784 = size_binop (PLUS_EXPR, rli->offset,
786 size_binop (CEIL_DIV_EXPR, rli->bitpos,
787 bitsize_unit_node)));
788 rli->bitpos = bitsize_zero_node;
790 rli->offset = round_up (rli->offset, desired_align / BITS_PER_UNIT);
793 if (! TREE_CONSTANT (rli->offset))
794 rli->offset_align = desired_align;
798 /* Handle compatibility with PCC. Note that if the record has any
799 variable-sized fields, we need not worry about compatibility. */
800 #ifdef PCC_BITFIELD_TYPE_MATTERS
801 if (PCC_BITFIELD_TYPE_MATTERS
802 && TREE_CODE (field) == FIELD_DECL
803 && type != error_mark_node
804 && DECL_BIT_FIELD (field)
805 && ! DECL_PACKED (field)
806 && maximum_field_alignment == 0
807 && ! integer_zerop (DECL_SIZE (field))
808 && host_integerp (DECL_SIZE (field), 1)
809 && host_integerp (rli->offset, 1)
810 && host_integerp (TYPE_SIZE (type), 1))
812 unsigned int type_align = TYPE_ALIGN (type);
813 tree dsize = DECL_SIZE (field);
814 HOST_WIDE_INT field_size = tree_low_cst (dsize, 1);
815 HOST_WIDE_INT offset = tree_low_cst (rli->offset, 0);
816 HOST_WIDE_INT bit_offset = tree_low_cst (rli->bitpos, 0);
818 /* A bit field may not span more units of alignment of its type
819 than its type itself. Advance to next boundary if necessary. */
820 if ((((offset * BITS_PER_UNIT + bit_offset + field_size +
823 - (offset * BITS_PER_UNIT + bit_offset) / type_align)
824 > tree_low_cst (TYPE_SIZE (type), 1) / type_align)
825 rli->bitpos = round_up (rli->bitpos, type_align);
829 #ifdef BITFIELD_NBYTES_LIMITED
830 if (BITFIELD_NBYTES_LIMITED
831 && TREE_CODE (field) == FIELD_DECL
832 && type != error_mark_node
833 && DECL_BIT_FIELD_TYPE (field)
834 && ! DECL_PACKED (field)
835 && ! integer_zerop (DECL_SIZE (field))
836 && host_integerp (DECL_SIZE (field), 1)
837 && host_integerp (rli->offset, 1)
838 && host_integerp (TYPE_SIZE (type), 1))
840 unsigned int type_align = TYPE_ALIGN (type);
841 tree dsize = DECL_SIZE (field);
842 HOST_WIDE_INT field_size = tree_low_cst (dsize, 1);
843 HOST_WIDE_INT offset = tree_low_cst (rli->offset, 0);
844 HOST_WIDE_INT bit_offset = tree_low_cst (rli->bitpos, 0);
846 if (maximum_field_alignment != 0)
847 type_align = MIN (type_align, maximum_field_alignment);
848 /* ??? This test is opposite the test in the containing if
849 statement, so this code is unreachable currently. */
850 else if (DECL_PACKED (field))
851 type_align = MIN (type_align, BITS_PER_UNIT);
853 /* A bit field may not span the unit of alignment of its type.
854 Advance to next boundary if necessary. */
855 /* ??? This code should match the code above for the
856 PCC_BITFIELD_TYPE_MATTERS case. */
857 if ((offset * BITS_PER_UNIT + bit_offset) / type_align
858 != ((offset * BITS_PER_UNIT + bit_offset + field_size - 1)
860 rli->bitpos = round_up (rli->bitpos, type_align);
864 /* Offset so far becomes the position of this field after normalizing. */
866 DECL_FIELD_OFFSET (field) = rli->offset;
867 DECL_FIELD_BIT_OFFSET (field) = rli->bitpos;
868 SET_DECL_OFFSET_ALIGN (field, rli->offset_align);
870 /* If this field ended up more aligned than we thought it would be (we
871 approximate this by seeing if its position changed), lay out the field
872 again; perhaps we can use an integral mode for it now. */
873 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field)))
874 actual_align = (tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1)
875 & - tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1));
876 else if (integer_zerop (DECL_FIELD_OFFSET (field)))
877 actual_align = BIGGEST_ALIGNMENT;
878 else if (host_integerp (DECL_FIELD_OFFSET (field), 1))
879 actual_align = (BITS_PER_UNIT
880 * (tree_low_cst (DECL_FIELD_OFFSET (field), 1)
881 & - tree_low_cst (DECL_FIELD_OFFSET (field), 1)));
883 actual_align = DECL_OFFSET_ALIGN (field);
885 if (known_align != actual_align)
886 layout_decl (field, actual_align);
888 /* Now add size of this field to the size of the record. If the size is
889 not constant, treat the field as being a multiple of bytes and just
890 adjust the offset, resetting the bit position. Otherwise, apportion the
891 size amongst the bit position and offset. First handle the case of an
892 unspecified size, which can happen when we have an invalid nested struct
893 definition, such as struct j { struct j { int i; } }. The error message
894 is printed in finish_struct. */
895 if (DECL_SIZE (field) == 0)
897 else if (TREE_CODE (DECL_SIZE_UNIT (field)) != INTEGER_CST
898 || TREE_CONSTANT_OVERFLOW (DECL_SIZE_UNIT (field)))
901 = size_binop (PLUS_EXPR, rli->offset,
903 size_binop (CEIL_DIV_EXPR, rli->bitpos,
904 bitsize_unit_node)));
906 = size_binop (PLUS_EXPR, rli->offset, DECL_SIZE_UNIT (field));
907 rli->bitpos = bitsize_zero_node;
908 rli->offset_align = MIN (rli->offset_align, DECL_ALIGN (field));
912 rli->bitpos = size_binop (PLUS_EXPR, rli->bitpos, DECL_SIZE (field));
917 /* Assuming that all the fields have been laid out, this function uses
918 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
919 inidicated by RLI. */
922 finalize_record_size (rli)
923 record_layout_info rli;
925 tree unpadded_size, unpadded_size_unit;
927 /* Now we want just byte and bit offsets, so set the offset alignment
928 to be a byte and then normalize. */
929 rli->offset_align = BITS_PER_UNIT;
932 /* Determine the desired alignment. */
933 #ifdef ROUND_TYPE_ALIGN
934 TYPE_ALIGN (rli->t) = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t),
937 TYPE_ALIGN (rli->t) = MAX (TYPE_ALIGN (rli->t), rli->record_align);
939 TYPE_USER_ALIGN (rli->t) = 1;
941 /* Compute the size so far. Be sure to allow for extra bits in the
942 size in bytes. We have guaranteed above that it will be no more
943 than a single byte. */
944 unpadded_size = rli_size_so_far (rli);
945 unpadded_size_unit = rli_size_unit_so_far (rli);
946 if (! integer_zerop (rli->bitpos))
948 = size_binop (PLUS_EXPR, unpadded_size_unit, size_one_node);
950 /* Record the un-rounded size in the binfo node. But first we check
951 the size of TYPE_BINFO to make sure that BINFO_SIZE is available. */
952 if (TYPE_BINFO (rli->t) && TREE_VEC_LENGTH (TYPE_BINFO (rli->t)) > 6)
954 TYPE_BINFO_SIZE (rli->t) = unpadded_size;
955 TYPE_BINFO_SIZE_UNIT (rli->t) = unpadded_size_unit;
958 /* Round the size up to be a multiple of the required alignment */
959 #ifdef ROUND_TYPE_SIZE
960 TYPE_SIZE (rli->t) = ROUND_TYPE_SIZE (rli->t, unpadded_size,
961 TYPE_ALIGN (rli->t));
962 TYPE_SIZE_UNIT (rli->t)
963 = ROUND_TYPE_SIZE_UNIT (rli->t, unpadded_size_unit,
964 TYPE_ALIGN (rli->t) / BITS_PER_UNIT);
966 TYPE_SIZE (rli->t) = round_up (unpadded_size, TYPE_ALIGN (rli->t));
967 TYPE_SIZE_UNIT (rli->t) = round_up (unpadded_size_unit,
968 TYPE_ALIGN (rli->t) / BITS_PER_UNIT);
971 if (warn_padded && TREE_CONSTANT (unpadded_size)
972 && simple_cst_equal (unpadded_size, TYPE_SIZE (rli->t)) == 0)
973 warning ("padding struct size to alignment boundary");
975 if (warn_packed && TREE_CODE (rli->t) == RECORD_TYPE
976 && TYPE_PACKED (rli->t) && ! rli->packed_maybe_necessary
977 && TREE_CONSTANT (unpadded_size))
981 #ifdef ROUND_TYPE_ALIGN
983 = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t), rli->unpacked_align);
985 rli->unpacked_align = MAX (TYPE_ALIGN (rli->t), rli->unpacked_align);
988 #ifdef ROUND_TYPE_SIZE
989 unpacked_size = ROUND_TYPE_SIZE (rli->t, TYPE_SIZE (rli->t),
990 rli->unpacked_align);
992 unpacked_size = round_up (TYPE_SIZE (rli->t), rli->unpacked_align);
995 if (simple_cst_equal (unpacked_size, TYPE_SIZE (rli->t)))
997 TYPE_PACKED (rli->t) = 0;
999 if (TYPE_NAME (rli->t))
1003 if (TREE_CODE (TYPE_NAME (rli->t)) == IDENTIFIER_NODE)
1004 name = IDENTIFIER_POINTER (TYPE_NAME (rli->t));
1006 name = IDENTIFIER_POINTER (DECL_NAME (TYPE_NAME (rli->t)));
1008 if (STRICT_ALIGNMENT)
1009 warning ("packed attribute causes inefficient alignment for `%s'", name);
1011 warning ("packed attribute is unnecessary for `%s'", name);
1015 if (STRICT_ALIGNMENT)
1016 warning ("packed attribute causes inefficient alignment");
1018 warning ("packed attribute is unnecessary");
1024 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
1027 compute_record_mode (type)
1031 enum machine_mode mode = VOIDmode;
1033 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
1034 However, if possible, we use a mode that fits in a register
1035 instead, in order to allow for better optimization down the
1037 TYPE_MODE (type) = BLKmode;
1039 if (! host_integerp (TYPE_SIZE (type), 1))
1042 /* A record which has any BLKmode members must itself be
1043 BLKmode; it can't go in a register. Unless the member is
1044 BLKmode only because it isn't aligned. */
1045 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1047 unsigned HOST_WIDE_INT bitpos;
1049 if (TREE_CODE (field) != FIELD_DECL)
1052 if (TREE_CODE (TREE_TYPE (field)) == ERROR_MARK
1053 || (TYPE_MODE (TREE_TYPE (field)) == BLKmode
1054 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field)))
1055 || ! host_integerp (bit_position (field), 1)
1056 || ! host_integerp (DECL_SIZE (field), 1))
1059 bitpos = int_bit_position (field);
1061 /* Must be BLKmode if any field crosses a word boundary,
1062 since extract_bit_field can't handle that in registers. */
1063 if (bitpos / BITS_PER_WORD
1064 != ((tree_low_cst (DECL_SIZE (field), 1) + bitpos - 1)
1066 /* But there is no problem if the field is entire words. */
1067 && tree_low_cst (DECL_SIZE (field), 1) % BITS_PER_WORD != 0)
1070 /* If this field is the whole struct, remember its mode so
1071 that, say, we can put a double in a class into a DF
1072 register instead of forcing it to live in the stack. */
1073 if (simple_cst_equal (TYPE_SIZE (type), DECL_SIZE (field)))
1074 mode = DECL_MODE (field);
1076 #ifdef STRUCT_FORCE_BLK
1077 /* With some targets, eg. c4x, it is sub-optimal
1078 to access an aligned BLKmode structure as a scalar. */
1079 if (mode == VOIDmode && STRUCT_FORCE_BLK (field))
1081 #endif /* STRUCT_FORCE_BLK */
1084 /* If we only have one real field; use its mode. This only applies to
1085 RECORD_TYPE. This does not apply to unions. */
1086 if (TREE_CODE (type) == RECORD_TYPE && mode != VOIDmode)
1087 TYPE_MODE (type) = mode;
1089 TYPE_MODE (type) = mode_for_size_tree (TYPE_SIZE (type), MODE_INT, 1);
1091 /* If structure's known alignment is less than what the scalar
1092 mode would need, and it matters, then stick with BLKmode. */
1093 if (TYPE_MODE (type) != BLKmode
1095 && ! (TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT
1096 || TYPE_ALIGN (type) >= GET_MODE_ALIGNMENT (TYPE_MODE (type))))
1098 /* If this is the only reason this type is BLKmode, then
1099 don't force containing types to be BLKmode. */
1100 TYPE_NO_FORCE_BLK (type) = 1;
1101 TYPE_MODE (type) = BLKmode;
1105 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1109 finalize_type_size (type)
1112 /* Normally, use the alignment corresponding to the mode chosen.
1113 However, where strict alignment is not required, avoid
1114 over-aligning structures, since most compilers do not do this
1117 if (TYPE_MODE (type) != BLKmode && TYPE_MODE (type) != VOIDmode
1118 && (STRICT_ALIGNMENT
1119 || (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE
1120 && TREE_CODE (type) != QUAL_UNION_TYPE
1121 && TREE_CODE (type) != ARRAY_TYPE)))
1123 TYPE_ALIGN (type) = GET_MODE_ALIGNMENT (TYPE_MODE (type));
1124 TYPE_USER_ALIGN (type) = 0;
1127 /* Do machine-dependent extra alignment. */
1128 #ifdef ROUND_TYPE_ALIGN
1130 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (type), BITS_PER_UNIT);
1133 /* If we failed to find a simple way to calculate the unit size
1134 of the type, find it by division. */
1135 if (TYPE_SIZE_UNIT (type) == 0 && TYPE_SIZE (type) != 0)
1136 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1137 result will fit in sizetype. We will get more efficient code using
1138 sizetype, so we force a conversion. */
1139 TYPE_SIZE_UNIT (type)
1140 = convert (sizetype,
1141 size_binop (FLOOR_DIV_EXPR, TYPE_SIZE (type),
1142 bitsize_unit_node));
1144 if (TYPE_SIZE (type) != 0)
1146 #ifdef ROUND_TYPE_SIZE
1148 = ROUND_TYPE_SIZE (type, TYPE_SIZE (type), TYPE_ALIGN (type));
1149 TYPE_SIZE_UNIT (type)
1150 = ROUND_TYPE_SIZE_UNIT (type, TYPE_SIZE_UNIT (type),
1151 TYPE_ALIGN (type) / BITS_PER_UNIT);
1153 TYPE_SIZE (type) = round_up (TYPE_SIZE (type), TYPE_ALIGN (type));
1154 TYPE_SIZE_UNIT (type)
1155 = round_up (TYPE_SIZE_UNIT (type), TYPE_ALIGN (type) / BITS_PER_UNIT);
1159 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1160 if (TYPE_SIZE (type) != 0 && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
1161 TYPE_SIZE (type) = variable_size (TYPE_SIZE (type));
1162 if (TYPE_SIZE_UNIT (type) != 0
1163 && TREE_CODE (TYPE_SIZE_UNIT (type)) != INTEGER_CST)
1164 TYPE_SIZE_UNIT (type) = variable_size (TYPE_SIZE_UNIT (type));
1166 /* Also layout any other variants of the type. */
1167 if (TYPE_NEXT_VARIANT (type)
1168 || type != TYPE_MAIN_VARIANT (type))
1171 /* Record layout info of this variant. */
1172 tree size = TYPE_SIZE (type);
1173 tree size_unit = TYPE_SIZE_UNIT (type);
1174 unsigned int align = TYPE_ALIGN (type);
1175 unsigned int user_align = TYPE_USER_ALIGN (type);
1176 enum machine_mode mode = TYPE_MODE (type);
1178 /* Copy it into all variants. */
1179 for (variant = TYPE_MAIN_VARIANT (type);
1181 variant = TYPE_NEXT_VARIANT (variant))
1183 TYPE_SIZE (variant) = size;
1184 TYPE_SIZE_UNIT (variant) = size_unit;
1185 TYPE_ALIGN (variant) = align;
1186 TYPE_USER_ALIGN (variant) = user_align;
1187 TYPE_MODE (variant) = mode;
1192 /* Do all of the work required to layout the type indicated by RLI,
1193 once the fields have been laid out. This function will call `free'
1197 finish_record_layout (rli)
1198 record_layout_info rli;
1200 /* Compute the final size. */
1201 finalize_record_size (rli);
1203 /* Compute the TYPE_MODE for the record. */
1204 compute_record_mode (rli->t);
1206 /* Perform any last tweaks to the TYPE_SIZE, etc. */
1207 finalize_type_size (rli->t);
1209 /* Lay out any static members. This is done now because their type
1210 may use the record's type. */
1211 while (rli->pending_statics)
1213 layout_decl (TREE_VALUE (rli->pending_statics), 0);
1214 rli->pending_statics = TREE_CHAIN (rli->pending_statics);
1221 /* Calculate the mode, size, and alignment for TYPE.
1222 For an array type, calculate the element separation as well.
1223 Record TYPE on the chain of permanent or temporary types
1224 so that dbxout will find out about it.
1226 TYPE_SIZE of a type is nonzero if the type has been laid out already.
1227 layout_type does nothing on such a type.
1229 If the type is incomplete, its TYPE_SIZE remains zero. */
1238 /* Do nothing if type has been laid out before. */
1239 if (TYPE_SIZE (type))
1242 switch (TREE_CODE (type))
1245 /* This kind of type is the responsibility
1246 of the language-specific code. */
1249 case BOOLEAN_TYPE: /* Used for Java, Pascal, and Chill. */
1250 if (TYPE_PRECISION (type) == 0)
1251 TYPE_PRECISION (type) = 1; /* default to one byte/boolean. */
1253 /* ... fall through ... */
1258 if (TREE_CODE (TYPE_MIN_VALUE (type)) == INTEGER_CST
1259 && tree_int_cst_sgn (TYPE_MIN_VALUE (type)) >= 0)
1260 TREE_UNSIGNED (type) = 1;
1262 TYPE_MODE (type) = smallest_mode_for_size (TYPE_PRECISION (type),
1264 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1265 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1269 TYPE_MODE (type) = mode_for_size (TYPE_PRECISION (type), MODE_FLOAT, 0);
1270 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1271 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1275 TREE_UNSIGNED (type) = TREE_UNSIGNED (TREE_TYPE (type));
1277 = mode_for_size (2 * TYPE_PRECISION (TREE_TYPE (type)),
1278 (TREE_CODE (TREE_TYPE (type)) == INTEGER_TYPE
1279 ? MODE_COMPLEX_INT : MODE_COMPLEX_FLOAT),
1281 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1282 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1289 subtype = TREE_TYPE (type);
1290 TREE_UNSIGNED (type) = TREE_UNSIGNED (subtype);
1291 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1292 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1297 /* This is an incomplete type and so doesn't have a size. */
1298 TYPE_ALIGN (type) = 1;
1299 TYPE_USER_ALIGN (type) = 0;
1300 TYPE_MODE (type) = VOIDmode;
1304 TYPE_SIZE (type) = bitsize_int (POINTER_SIZE);
1305 TYPE_SIZE_UNIT (type) = size_int (POINTER_SIZE / BITS_PER_UNIT);
1306 TYPE_MODE (type) = ptr_mode;
1311 TYPE_MODE (type) = mode_for_size (2 * POINTER_SIZE, MODE_INT, 0);
1312 TYPE_SIZE (type) = bitsize_int (2 * POINTER_SIZE);
1313 TYPE_SIZE_UNIT (type) = size_int ((2 * POINTER_SIZE) / BITS_PER_UNIT);
1317 case REFERENCE_TYPE:
1318 TYPE_MODE (type) = ptr_mode;
1319 TYPE_SIZE (type) = bitsize_int (POINTER_SIZE);
1320 TYPE_SIZE_UNIT (type) = size_int (POINTER_SIZE / BITS_PER_UNIT);
1321 TREE_UNSIGNED (type) = 1;
1322 TYPE_PRECISION (type) = POINTER_SIZE;
1327 register tree index = TYPE_DOMAIN (type);
1328 register tree element = TREE_TYPE (type);
1330 build_pointer_type (element);
1332 /* We need to know both bounds in order to compute the size. */
1333 if (index && TYPE_MAX_VALUE (index) && TYPE_MIN_VALUE (index)
1334 && TYPE_SIZE (element))
1336 tree ub = TYPE_MAX_VALUE (index);
1337 tree lb = TYPE_MIN_VALUE (index);
1341 /* The initial subtraction should happen in the original type so
1342 that (possible) negative values are handled appropriately. */
1343 length = size_binop (PLUS_EXPR, size_one_node,
1345 fold (build (MINUS_EXPR,
1349 /* Special handling for arrays of bits (for Chill). */
1350 element_size = TYPE_SIZE (element);
1351 if (TYPE_PACKED (type) && INTEGRAL_TYPE_P (element)
1352 && (integer_zerop (TYPE_MAX_VALUE (element))
1353 || integer_onep (TYPE_MAX_VALUE (element)))
1354 && host_integerp (TYPE_MIN_VALUE (element), 1))
1356 HOST_WIDE_INT maxvalue
1357 = tree_low_cst (TYPE_MAX_VALUE (element), 1);
1358 HOST_WIDE_INT minvalue
1359 = tree_low_cst (TYPE_MIN_VALUE (element), 1);
1361 if (maxvalue - minvalue == 1
1362 && (maxvalue == 1 || maxvalue == 0))
1363 element_size = integer_one_node;
1366 TYPE_SIZE (type) = size_binop (MULT_EXPR, element_size,
1367 convert (bitsizetype, length));
1369 /* If we know the size of the element, calculate the total
1370 size directly, rather than do some division thing below.
1371 This optimization helps Fortran assumed-size arrays
1372 (where the size of the array is determined at runtime)
1374 Note that we can't do this in the case where the size of
1375 the elements is one bit since TYPE_SIZE_UNIT cannot be
1376 set correctly in that case. */
1377 if (TYPE_SIZE_UNIT (element) != 0 && ! integer_onep (element_size))
1378 TYPE_SIZE_UNIT (type)
1379 = size_binop (MULT_EXPR, TYPE_SIZE_UNIT (element), length);
1382 /* Now round the alignment and size,
1383 using machine-dependent criteria if any. */
1385 #ifdef ROUND_TYPE_ALIGN
1387 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (element), BITS_PER_UNIT);
1389 TYPE_ALIGN (type) = MAX (TYPE_ALIGN (element), BITS_PER_UNIT);
1392 #ifdef ROUND_TYPE_SIZE
1393 if (TYPE_SIZE (type) != 0)
1396 = ROUND_TYPE_SIZE (type, TYPE_SIZE (type), TYPE_ALIGN (type));
1398 /* If the rounding changed the size of the type, remove any
1399 pre-calculated TYPE_SIZE_UNIT. */
1400 if (simple_cst_equal (TYPE_SIZE (type), tmp) != 1)
1401 TYPE_SIZE_UNIT (type) = NULL;
1403 TYPE_SIZE (type) = tmp;
1407 TYPE_MODE (type) = BLKmode;
1408 if (TYPE_SIZE (type) != 0
1409 /* BLKmode elements force BLKmode aggregate;
1410 else extract/store fields may lose. */
1411 && (TYPE_MODE (TREE_TYPE (type)) != BLKmode
1412 || TYPE_NO_FORCE_BLK (TREE_TYPE (type))))
1415 = mode_for_size_tree (TYPE_SIZE (type), MODE_INT, 1);
1417 if (TYPE_MODE (type) != BLKmode
1418 && STRICT_ALIGNMENT && TYPE_ALIGN (type) < BIGGEST_ALIGNMENT
1419 && TYPE_ALIGN (type) < GET_MODE_ALIGNMENT (TYPE_MODE (type))
1420 && TYPE_MODE (type) != BLKmode)
1422 TYPE_NO_FORCE_BLK (type) = 1;
1423 TYPE_MODE (type) = BLKmode;
1431 case QUAL_UNION_TYPE:
1434 record_layout_info rli;
1436 /* Initialize the layout information. */
1437 rli = start_record_layout (type);
1439 /* If this is a QUAL_UNION_TYPE, we want to process the fields
1440 in the reverse order in building the COND_EXPR that denotes
1441 its size. We reverse them again later. */
1442 if (TREE_CODE (type) == QUAL_UNION_TYPE)
1443 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
1445 /* Place all the fields. */
1446 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1447 place_field (rli, field);
1449 if (TREE_CODE (type) == QUAL_UNION_TYPE)
1450 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
1452 /* Finish laying out the record. */
1453 finish_record_layout (rli);
1457 case SET_TYPE: /* Used by Chill and Pascal. */
1458 if (TREE_CODE (TYPE_MAX_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST
1459 || TREE_CODE (TYPE_MIN_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST)
1463 #ifndef SET_WORD_SIZE
1464 #define SET_WORD_SIZE BITS_PER_WORD
1466 unsigned int alignment
1467 = set_alignment ? set_alignment : SET_WORD_SIZE;
1469 = (TREE_INT_CST_LOW (TYPE_MAX_VALUE (TYPE_DOMAIN (type)))
1470 - TREE_INT_CST_LOW (TYPE_MIN_VALUE (TYPE_DOMAIN (type))) + 1);
1472 = ((size_in_bits + alignment - 1) / alignment) * alignment;
1474 if (rounded_size > (int) alignment)
1475 TYPE_MODE (type) = BLKmode;
1477 TYPE_MODE (type) = mode_for_size (alignment, MODE_INT, 1);
1479 TYPE_SIZE (type) = bitsize_int (rounded_size);
1480 TYPE_SIZE_UNIT (type) = size_int (rounded_size / BITS_PER_UNIT);
1481 TYPE_ALIGN (type) = alignment;
1482 TYPE_USER_ALIGN (type) = 0;
1483 TYPE_PRECISION (type) = size_in_bits;
1488 /* The size may vary in different languages, so the language front end
1489 should fill in the size. */
1490 TYPE_ALIGN (type) = BIGGEST_ALIGNMENT;
1491 TYPE_USER_ALIGN (type) = 0;
1492 TYPE_MODE (type) = BLKmode;
1499 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
1500 records and unions, finish_record_layout already called this
1502 if (TREE_CODE (type) != RECORD_TYPE
1503 && TREE_CODE (type) != UNION_TYPE
1504 && TREE_CODE (type) != QUAL_UNION_TYPE)
1505 finalize_type_size (type);
1507 /* If this type is created before sizetype has been permanently set,
1508 record it so set_sizetype can fix it up. */
1510 early_type_list = tree_cons (NULL_TREE, type, early_type_list);
1512 /* If an alias set has been set for this aggregate when it was incomplete,
1513 force it into alias set 0.
1514 This is too conservative, but we cannot call record_component_aliases
1515 here because some frontends still change the aggregates after
1517 if (AGGREGATE_TYPE_P (type) && TYPE_ALIAS_SET_KNOWN_P (type))
1518 TYPE_ALIAS_SET (type) = 0;
1521 /* Create and return a type for signed integers of PRECISION bits. */
1524 make_signed_type (precision)
1527 register tree type = make_node (INTEGER_TYPE);
1529 TYPE_PRECISION (type) = precision;
1531 fixup_signed_type (type);
1535 /* Create and return a type for unsigned integers of PRECISION bits. */
1538 make_unsigned_type (precision)
1541 register tree type = make_node (INTEGER_TYPE);
1543 TYPE_PRECISION (type) = precision;
1545 fixup_unsigned_type (type);
1549 /* Initialize sizetype and bitsizetype to a reasonable and temporary
1550 value to enable integer types to be created. */
1553 initialize_sizetypes ()
1555 tree t = make_node (INTEGER_TYPE);
1557 /* Set this so we do something reasonable for the build_int_2 calls
1559 integer_type_node = t;
1561 TYPE_MODE (t) = SImode;
1562 TYPE_ALIGN (t) = GET_MODE_ALIGNMENT (SImode);
1563 TYPE_USER_ALIGN (t) = 0;
1564 TYPE_SIZE (t) = build_int_2 (GET_MODE_BITSIZE (SImode), 0);
1565 TYPE_SIZE_UNIT (t) = build_int_2 (GET_MODE_SIZE (SImode), 0);
1566 TREE_UNSIGNED (t) = 1;
1567 TYPE_PRECISION (t) = GET_MODE_BITSIZE (SImode);
1568 TYPE_MIN_VALUE (t) = build_int_2 (0, 0);
1569 TYPE_IS_SIZETYPE (t) = 1;
1571 /* 1000 avoids problems with possible overflow and is certainly
1572 larger than any size value we'd want to be storing. */
1573 TYPE_MAX_VALUE (t) = build_int_2 (1000, 0);
1575 /* These two must be different nodes because of the caching done in
1578 bitsizetype = copy_node (t);
1579 integer_type_node = 0;
1582 /* Set sizetype to TYPE, and initialize *sizetype accordingly.
1583 Also update the type of any standard type's sizes made so far. */
1589 int oprecision = TYPE_PRECISION (type);
1590 /* The *bitsizetype types use a precision that avoids overflows when
1591 calculating signed sizes / offsets in bits. However, when
1592 cross-compiling from a 32 bit to a 64 bit host, we are limited to 64 bit
1594 int precision = MIN (oprecision + BITS_PER_UNIT_LOG + 1,
1595 2 * HOST_BITS_PER_WIDE_INT);
1602 /* Make copies of nodes since we'll be setting TYPE_IS_SIZETYPE. */
1603 sizetype = copy_node (type);
1604 TYPE_DOMAIN (sizetype) = type;
1605 TYPE_IS_SIZETYPE (sizetype) = 1;
1606 bitsizetype = make_node (INTEGER_TYPE);
1607 TYPE_NAME (bitsizetype) = TYPE_NAME (type);
1608 TYPE_PRECISION (bitsizetype) = precision;
1609 TYPE_IS_SIZETYPE (bitsizetype) = 1;
1611 if (TREE_UNSIGNED (type))
1612 fixup_unsigned_type (bitsizetype);
1614 fixup_signed_type (bitsizetype);
1616 layout_type (bitsizetype);
1618 if (TREE_UNSIGNED (type))
1620 usizetype = sizetype;
1621 ubitsizetype = bitsizetype;
1622 ssizetype = copy_node (make_signed_type (oprecision));
1623 sbitsizetype = copy_node (make_signed_type (precision));
1627 ssizetype = sizetype;
1628 sbitsizetype = bitsizetype;
1629 usizetype = copy_node (make_unsigned_type (oprecision));
1630 ubitsizetype = copy_node (make_unsigned_type (precision));
1633 TYPE_NAME (bitsizetype) = get_identifier ("bit_size_type");
1635 /* Show is a sizetype, is a main type, and has no pointers to it. */
1636 for (i = 0; i < ARRAY_SIZE (sizetype_tab); i++)
1638 TYPE_IS_SIZETYPE (sizetype_tab[i]) = 1;
1639 TYPE_MAIN_VARIANT (sizetype_tab[i]) = sizetype_tab[i];
1640 TYPE_NEXT_VARIANT (sizetype_tab[i]) = 0;
1641 TYPE_POINTER_TO (sizetype_tab[i]) = 0;
1642 TYPE_REFERENCE_TO (sizetype_tab[i]) = 0;
1645 ggc_add_tree_root ((tree *) &sizetype_tab,
1646 sizeof sizetype_tab / sizeof (tree));
1648 /* Go down each of the types we already made and set the proper type
1649 for the sizes in them. */
1650 for (t = early_type_list; t != 0; t = TREE_CHAIN (t))
1652 if (TREE_CODE (TREE_VALUE (t)) != INTEGER_TYPE)
1655 TREE_TYPE (TYPE_SIZE (TREE_VALUE (t))) = bitsizetype;
1656 TREE_TYPE (TYPE_SIZE_UNIT (TREE_VALUE (t))) = sizetype;
1659 early_type_list = 0;
1663 /* Set the extreme values of TYPE based on its precision in bits,
1664 then lay it out. Used when make_signed_type won't do
1665 because the tree code is not INTEGER_TYPE.
1666 E.g. for Pascal, when the -fsigned-char option is given. */
1669 fixup_signed_type (type)
1672 register int precision = TYPE_PRECISION (type);
1674 TYPE_MIN_VALUE (type)
1675 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1676 ? 0 : (HOST_WIDE_INT) (-1) << (precision - 1)),
1677 (((HOST_WIDE_INT) (-1)
1678 << (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1679 ? precision - HOST_BITS_PER_WIDE_INT - 1
1681 TYPE_MAX_VALUE (type)
1682 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1683 ? -1 : ((HOST_WIDE_INT) 1 << (precision - 1)) - 1),
1684 (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1685 ? (((HOST_WIDE_INT) 1
1686 << (precision - HOST_BITS_PER_WIDE_INT - 1))) - 1
1689 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
1690 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
1692 /* Lay out the type: set its alignment, size, etc. */
1696 /* Set the extreme values of TYPE based on its precision in bits,
1697 then lay it out. This is used both in `make_unsigned_type'
1698 and for enumeral types. */
1701 fixup_unsigned_type (type)
1704 register int precision = TYPE_PRECISION (type);
1706 TYPE_MIN_VALUE (type) = build_int_2 (0, 0);
1707 TYPE_MAX_VALUE (type)
1708 = build_int_2 (precision - HOST_BITS_PER_WIDE_INT >= 0
1709 ? -1 : ((HOST_WIDE_INT) 1 << precision) - 1,
1710 precision - HOST_BITS_PER_WIDE_INT > 0
1711 ? ((unsigned HOST_WIDE_INT) ~0
1712 >> (HOST_BITS_PER_WIDE_INT
1713 - (precision - HOST_BITS_PER_WIDE_INT)))
1715 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
1716 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
1718 /* Lay out the type: set its alignment, size, etc. */
1722 /* Find the best machine mode to use when referencing a bit field of length
1723 BITSIZE bits starting at BITPOS.
1725 The underlying object is known to be aligned to a boundary of ALIGN bits.
1726 If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
1727 larger than LARGEST_MODE (usually SImode).
1729 If no mode meets all these conditions, we return VOIDmode. Otherwise, if
1730 VOLATILEP is true or SLOW_BYTE_ACCESS is false, we return the smallest
1731 mode meeting these conditions.
1733 Otherwise (VOLATILEP is false and SLOW_BYTE_ACCESS is true), we return
1734 the largest mode (but a mode no wider than UNITS_PER_WORD) that meets
1735 all the conditions. */
1738 get_best_mode (bitsize, bitpos, align, largest_mode, volatilep)
1739 int bitsize, bitpos;
1741 enum machine_mode largest_mode;
1744 enum machine_mode mode;
1745 unsigned int unit = 0;
1747 /* Find the narrowest integer mode that contains the bit field. */
1748 for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
1749 mode = GET_MODE_WIDER_MODE (mode))
1751 unit = GET_MODE_BITSIZE (mode);
1752 if ((bitpos % unit) + bitsize <= unit)
1756 if (mode == VOIDmode
1757 /* It is tempting to omit the following line
1758 if STRICT_ALIGNMENT is true.
1759 But that is incorrect, since if the bitfield uses part of 3 bytes
1760 and we use a 4-byte mode, we could get a spurious segv
1761 if the extra 4th byte is past the end of memory.
1762 (Though at least one Unix compiler ignores this problem:
1763 that on the Sequent 386 machine. */
1764 || MIN (unit, BIGGEST_ALIGNMENT) > align
1765 || (largest_mode != VOIDmode && unit > GET_MODE_BITSIZE (largest_mode)))
1768 if (SLOW_BYTE_ACCESS && ! volatilep)
1770 enum machine_mode wide_mode = VOIDmode, tmode;
1772 for (tmode = GET_CLASS_NARROWEST_MODE (MODE_INT); tmode != VOIDmode;
1773 tmode = GET_MODE_WIDER_MODE (tmode))
1775 unit = GET_MODE_BITSIZE (tmode);
1776 if (bitpos / unit == (bitpos + bitsize - 1) / unit
1777 && unit <= BITS_PER_WORD
1778 && unit <= MIN (align, BIGGEST_ALIGNMENT)
1779 && (largest_mode == VOIDmode
1780 || unit <= GET_MODE_BITSIZE (largest_mode)))
1784 if (wide_mode != VOIDmode)
1791 /* Return the alignment of MODE. This will be bounded by 1 and
1792 BIGGEST_ALIGNMENT. */
1795 get_mode_alignment (mode)
1796 enum machine_mode mode;
1798 unsigned int alignment = GET_MODE_UNIT_SIZE (mode) * BITS_PER_UNIT;
1800 /* Extract the LSB of the size. */
1801 alignment = alignment & -alignment;
1803 alignment = MIN (BIGGEST_ALIGNMENT, MAX (1, alignment));
1807 /* This function is run once to initialize stor-layout.c. */
1810 init_stor_layout_once ()
1812 ggc_add_tree_root (&pending_sizes, 1);