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. */
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 mode = mode_for_size (GET_MODE_BITSIZE (mode), MODE_INT, 0);
237 /* ... fall through ... */
247 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
248 This can only be applied to objects of a sizetype. */
251 round_up (value, divisor)
255 tree arg = size_int_type (divisor, TREE_TYPE (value));
257 return size_binop (MULT_EXPR, size_binop (CEIL_DIV_EXPR, value, arg), arg);
260 /* Likewise, but round down. */
263 round_down (value, divisor)
267 tree arg = size_int_type (divisor, TREE_TYPE (value));
269 return size_binop (MULT_EXPR, size_binop (FLOOR_DIV_EXPR, value, arg), arg);
272 /* Set the size, mode and alignment of a ..._DECL node.
273 TYPE_DECL does need this for C++.
274 Note that LABEL_DECL and CONST_DECL nodes do not need this,
275 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
276 Don't call layout_decl for them.
278 KNOWN_ALIGN is the amount of alignment we can assume this
279 decl has with no special effort. It is relevant only for FIELD_DECLs
280 and depends on the previous fields.
281 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
282 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
283 the record will be aligned to suit. */
286 layout_decl (decl, known_align)
288 unsigned int known_align;
290 register tree type = TREE_TYPE (decl);
291 register enum tree_code code = TREE_CODE (decl);
293 if (code == CONST_DECL)
295 else if (code != VAR_DECL && code != PARM_DECL && code != RESULT_DECL
296 && code != TYPE_DECL && code != FIELD_DECL)
299 if (type == error_mark_node)
300 type = void_type_node;
302 /* Usually the size and mode come from the data type without change,
303 however, the front-end may set the explicit width of the field, so its
304 size may not be the same as the size of its type. This happens with
305 bitfields, of course (an `int' bitfield may be only 2 bits, say), but it
306 also happens with other fields. For example, the C++ front-end creates
307 zero-sized fields corresponding to empty base classes, and depends on
308 layout_type setting DECL_FIELD_BITPOS correctly for the field. Set the
309 size in bytes from the size in bits. If we have already set the mode,
310 don't set it again since we can be called twice for FIELD_DECLs. */
312 TREE_UNSIGNED (decl) = TREE_UNSIGNED (type);
313 if (DECL_MODE (decl) == VOIDmode)
314 DECL_MODE (decl) = TYPE_MODE (type);
316 if (DECL_SIZE (decl) == 0)
318 DECL_SIZE (decl) = TYPE_SIZE (type);
319 DECL_SIZE_UNIT (decl) = TYPE_SIZE_UNIT (type);
322 DECL_SIZE_UNIT (decl)
323 = convert (sizetype, size_binop (CEIL_DIV_EXPR, DECL_SIZE (decl),
326 /* Force alignment required for the data type.
327 But if the decl itself wants greater alignment, don't override that.
328 Likewise, if the decl is packed, don't override it. */
329 if (! (code == FIELD_DECL && DECL_BIT_FIELD (decl))
330 && (DECL_ALIGN (decl) == 0
331 || (! (code == FIELD_DECL && DECL_PACKED (decl))
332 && TYPE_ALIGN (type) > DECL_ALIGN (decl))))
333 DECL_ALIGN (decl) = TYPE_ALIGN (type);
335 /* For fields, set the bit field type and update the alignment. */
336 if (code == FIELD_DECL)
338 DECL_BIT_FIELD_TYPE (decl) = DECL_BIT_FIELD (decl) ? type : 0;
339 if (maximum_field_alignment != 0)
340 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), maximum_field_alignment);
341 else if (DECL_PACKED (decl))
342 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), BITS_PER_UNIT);
345 /* See if we can use an ordinary integer mode for a bit-field.
346 Conditions are: a fixed size that is correct for another mode
347 and occupying a complete byte or bytes on proper boundary. */
348 if (code == FIELD_DECL && DECL_BIT_FIELD (decl)
349 && TYPE_SIZE (type) != 0
350 && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
351 && GET_MODE_CLASS (TYPE_MODE (type)) == MODE_INT)
353 register enum machine_mode xmode
354 = mode_for_size_tree (DECL_SIZE (decl), MODE_INT, 1);
356 if (xmode != BLKmode && known_align >= GET_MODE_ALIGNMENT (xmode))
358 DECL_ALIGN (decl) = MAX (GET_MODE_ALIGNMENT (xmode),
360 DECL_MODE (decl) = xmode;
361 DECL_BIT_FIELD (decl) = 0;
365 /* Turn off DECL_BIT_FIELD if we won't need it set. */
366 if (code == FIELD_DECL && DECL_BIT_FIELD (decl)
367 && TYPE_MODE (type) == BLKmode && DECL_MODE (decl) == BLKmode
368 && known_align >= TYPE_ALIGN (type)
369 && DECL_ALIGN (decl) >= TYPE_ALIGN (type)
370 && DECL_SIZE_UNIT (decl) != 0)
371 DECL_BIT_FIELD (decl) = 0;
373 /* Evaluate nonconstant size only once, either now or as soon as safe. */
374 if (DECL_SIZE (decl) != 0 && TREE_CODE (DECL_SIZE (decl)) != INTEGER_CST)
375 DECL_SIZE (decl) = variable_size (DECL_SIZE (decl));
376 if (DECL_SIZE_UNIT (decl) != 0
377 && TREE_CODE (DECL_SIZE_UNIT (decl)) != INTEGER_CST)
378 DECL_SIZE_UNIT (decl) = variable_size (DECL_SIZE_UNIT (decl));
380 /* If requested, warn about definitions of large data objects. */
382 && (code == VAR_DECL || code == PARM_DECL)
383 && ! DECL_EXTERNAL (decl))
385 tree size = DECL_SIZE_UNIT (decl);
387 if (size != 0 && TREE_CODE (size) == INTEGER_CST
388 && compare_tree_int (size, larger_than_size) > 0)
390 unsigned int size_as_int = TREE_INT_CST_LOW (size);
392 if (compare_tree_int (size, size_as_int) == 0)
393 warning_with_decl (decl, "size of `%s' is %d bytes", size_as_int);
395 warning_with_decl (decl, "size of `%s' is larger than %d bytes",
401 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
402 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
403 is to be passed to all other layout functions for this record. It is the
404 responsibility of the caller to call `free' for the storage returned.
405 Note that garbage collection is not permitted until we finish laying
409 start_record_layout (t)
412 record_layout_info rli
413 = (record_layout_info) xmalloc (sizeof (struct record_layout_info_s));
417 /* If the type has a minimum specified alignment (via an attribute
418 declaration, for example) use it -- otherwise, start with a
419 one-byte alignment. */
420 rli->record_align = MAX (BITS_PER_UNIT, TYPE_ALIGN (t));
421 rli->unpacked_align = rli->record_align;
422 rli->offset_align = MAX (rli->record_align, BIGGEST_ALIGNMENT);
424 #ifdef STRUCTURE_SIZE_BOUNDARY
425 /* Packed structures don't need to have minimum size. */
426 if (! TYPE_PACKED (t))
427 rli->record_align = MAX (rli->record_align, STRUCTURE_SIZE_BOUNDARY);
430 rli->offset = size_zero_node;
431 rli->bitpos = bitsize_zero_node;
432 rli->pending_statics = 0;
433 rli->packed_maybe_necessary = 0;
438 /* These four routines perform computations that convert between
439 the offset/bitpos forms and byte and bit offsets. */
442 bit_from_pos (offset, bitpos)
445 return size_binop (PLUS_EXPR, bitpos,
446 size_binop (MULT_EXPR, convert (bitsizetype, offset),
451 byte_from_pos (offset, bitpos)
454 return size_binop (PLUS_EXPR, offset,
456 size_binop (TRUNC_DIV_EXPR, bitpos,
457 bitsize_unit_node)));
461 pos_from_byte (poffset, pbitpos, off_align, pos)
462 tree *poffset, *pbitpos;
463 unsigned int off_align;
467 = size_binop (MULT_EXPR,
469 size_binop (FLOOR_DIV_EXPR, pos,
470 bitsize_int (off_align
472 size_int (off_align / BITS_PER_UNIT));
473 *pbitpos = size_binop (MULT_EXPR,
474 size_binop (FLOOR_MOD_EXPR, pos,
475 bitsize_int (off_align / BITS_PER_UNIT)),
480 pos_from_bit (poffset, pbitpos, off_align, pos)
481 tree *poffset, *pbitpos;
482 unsigned int off_align;
485 *poffset = size_binop (MULT_EXPR,
487 size_binop (FLOOR_DIV_EXPR, pos,
488 bitsize_int (off_align))),
489 size_int (off_align / BITS_PER_UNIT));
490 *pbitpos = size_binop (FLOOR_MOD_EXPR, pos, bitsize_int (off_align));
493 /* Given a pointer to bit and byte offsets and an offset alignment,
494 normalize the offsets so they are within the alignment. */
497 normalize_offset (poffset, pbitpos, off_align)
498 tree *poffset, *pbitpos;
499 unsigned int off_align;
501 /* If the bit position is now larger than it should be, adjust it
503 if (compare_tree_int (*pbitpos, off_align) >= 0)
505 tree extra_aligns = size_binop (FLOOR_DIV_EXPR, *pbitpos,
506 bitsize_int (off_align));
509 = size_binop (PLUS_EXPR, *poffset,
510 size_binop (MULT_EXPR, convert (sizetype, extra_aligns),
511 size_int (off_align / BITS_PER_UNIT)));
514 = size_binop (FLOOR_MOD_EXPR, *pbitpos, bitsize_int (off_align));
518 /* Print debugging information about the information in RLI. */
522 record_layout_info rli;
524 print_node_brief (stderr, "type", rli->t, 0);
525 print_node_brief (stderr, "\noffset", rli->offset, 0);
526 print_node_brief (stderr, " bitpos", rli->bitpos, 0);
528 fprintf (stderr, "\nrec_align = %u, unpack_align = %u, off_align = %u\n",
529 rli->record_align, rli->unpacked_align, rli->offset_align);
530 if (rli->packed_maybe_necessary)
531 fprintf (stderr, "packed may be necessary\n");
533 if (rli->pending_statics)
535 fprintf (stderr, "pending statics:\n");
536 debug_tree (rli->pending_statics);
540 /* Given an RLI with a possibly-incremented BITPOS, adjust OFFSET and
541 BITPOS if necessary to keep BITPOS below OFFSET_ALIGN. */
545 record_layout_info rli;
547 normalize_offset (&rli->offset, &rli->bitpos, rli->offset_align);
550 /* Returns the size in bytes allocated so far. */
553 rli_size_unit_so_far (rli)
554 record_layout_info rli;
556 return byte_from_pos (rli->offset, rli->bitpos);
559 /* Returns the size in bits allocated so far. */
562 rli_size_so_far (rli)
563 record_layout_info rli;
565 return bit_from_pos (rli->offset, rli->bitpos);
568 /* Called from place_field to handle unions. */
571 place_union_field (rli, field)
572 record_layout_info rli;
575 layout_decl (field, 0);
577 DECL_FIELD_OFFSET (field) = size_zero_node;
578 DECL_FIELD_BIT_OFFSET (field) = bitsize_zero_node;
579 DECL_OFFSET_ALIGN (field) = BIGGEST_ALIGNMENT;
581 /* Union must be at least as aligned as any field requires. */
582 rli->record_align = MAX (rli->record_align, DECL_ALIGN (field));
584 #ifdef PCC_BITFIELD_TYPE_MATTERS
585 /* On the m88000, a bit field of declare type `int' forces the
586 entire union to have `int' alignment. */
587 if (PCC_BITFIELD_TYPE_MATTERS && DECL_BIT_FIELD_TYPE (field))
588 rli->record_align = MAX (rli->record_align,
589 TYPE_ALIGN (TREE_TYPE (field)));
592 /* We assume the union's size will be a multiple of a byte so we don't
593 bother with BITPOS. */
594 if (TREE_CODE (rli->t) == UNION_TYPE)
595 rli->offset = size_binop (MAX_EXPR, rli->offset, DECL_SIZE_UNIT (field));
596 else if (TREE_CODE (rli->t) == QUAL_UNION_TYPE)
597 rli->offset = fold (build (COND_EXPR, sizetype,
598 DECL_QUALIFIER (field),
599 DECL_SIZE_UNIT (field), rli->offset));
602 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
603 is a FIELD_DECL to be added after those fields already present in
604 T. (FIELD is not actually added to the TYPE_FIELDS list here;
605 callers that desire that behavior must manually perform that step.) */
608 place_field (rli, field)
609 record_layout_info rli;
612 /* The alignment required for FIELD. */
613 unsigned int desired_align;
614 /* The alignment FIELD would have if we just dropped it into the
615 record as it presently stands. */
616 unsigned int known_align;
617 unsigned int actual_align;
618 /* The type of this field. */
619 tree type = TREE_TYPE (field);
621 /* If FIELD is static, then treat it like a separate variable, not
622 really like a structure field. If it is a FUNCTION_DECL, it's a
623 method. In both cases, all we do is lay out the decl, and we do
624 it *after* the record is laid out. */
625 if (TREE_CODE (field) == VAR_DECL)
627 rli->pending_statics = tree_cons (NULL_TREE, field,
628 rli->pending_statics);
632 /* Enumerators and enum types which are local to this class need not
633 be laid out. Likewise for initialized constant fields. */
634 else if (TREE_CODE (field) != FIELD_DECL)
637 /* Unions are laid out very differently than records, so split
638 that code off to another function. */
639 else if (TREE_CODE (rli->t) != RECORD_TYPE)
641 place_union_field (rli, field);
645 /* Work out the known alignment so far. Note that A & (-A) is the
646 value of the least-significant bit in A that is one. */
647 if (! integer_zerop (rli->bitpos))
648 known_align = (tree_low_cst (rli->bitpos, 1)
649 & - tree_low_cst (rli->bitpos, 1));
650 else if (integer_zerop (rli->offset))
651 known_align = BIGGEST_ALIGNMENT;
652 else if (host_integerp (rli->offset, 1))
653 known_align = (BITS_PER_UNIT
654 * (tree_low_cst (rli->offset, 1)
655 & - tree_low_cst (rli->offset, 1)));
657 known_align = rli->offset_align;
659 /* Lay out the field so we know what alignment it needs. For a
660 packed field, use the alignment as specified, disregarding what
661 the type would want. */
662 desired_align = DECL_ALIGN (field);
663 layout_decl (field, known_align);
664 if (! DECL_PACKED (field))
665 desired_align = DECL_ALIGN (field);
667 /* Some targets (i.e. VMS) limit struct field alignment
668 to a lower boundary than alignment of variables. */
669 #ifdef BIGGEST_FIELD_ALIGNMENT
670 desired_align = MIN (desired_align, (unsigned) BIGGEST_FIELD_ALIGNMENT);
672 #ifdef ADJUST_FIELD_ALIGN
673 desired_align = ADJUST_FIELD_ALIGN (field, desired_align);
676 /* Record must have at least as much alignment as any field.
677 Otherwise, the alignment of the field within the record is
679 #ifdef PCC_BITFIELD_TYPE_MATTERS
680 if (PCC_BITFIELD_TYPE_MATTERS && type != error_mark_node
681 && DECL_BIT_FIELD_TYPE (field)
682 && ! integer_zerop (TYPE_SIZE (type)))
684 /* For these machines, a zero-length field does not
685 affect the alignment of the structure as a whole.
686 It does, however, affect the alignment of the next field
687 within the structure. */
688 if (! integer_zerop (DECL_SIZE (field)))
689 rli->record_align = MAX (rli->record_align, desired_align);
690 else if (! DECL_PACKED (field))
691 desired_align = TYPE_ALIGN (type);
693 /* A named bit field of declared type `int'
694 forces the entire structure to have `int' alignment. */
695 if (DECL_NAME (field) != 0)
697 unsigned int type_align = TYPE_ALIGN (type);
699 if (maximum_field_alignment != 0)
700 type_align = MIN (type_align, maximum_field_alignment);
701 else if (DECL_PACKED (field))
702 type_align = MIN (type_align, BITS_PER_UNIT);
704 rli->record_align = MAX (rli->record_align, type_align);
706 rli->unpacked_align = MAX (rli->unpacked_align,
713 rli->record_align = MAX (rli->record_align, desired_align);
714 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
717 if (warn_packed && DECL_PACKED (field))
719 if (known_align > TYPE_ALIGN (type))
721 if (TYPE_ALIGN (type) > desired_align)
723 if (STRICT_ALIGNMENT)
724 warning_with_decl (field, "packed attribute causes inefficient alignment for `%s'");
726 warning_with_decl (field, "packed attribute is unnecessary for `%s'");
730 rli->packed_maybe_necessary = 1;
733 /* Does this field automatically have alignment it needs by virtue
734 of the fields that precede it and the record's own alignment? */
735 if (known_align < desired_align)
737 /* No, we need to skip space before this field.
738 Bump the cumulative size to multiple of field alignment. */
741 warning_with_decl (field, "padding struct to align `%s'");
743 /* If the alignment is still within offset_align, just align
745 if (desired_align < rli->offset_align)
746 rli->bitpos = round_up (rli->bitpos, desired_align);
749 /* First adjust OFFSET by the partial bits, then align. */
751 = size_binop (PLUS_EXPR, rli->offset,
753 size_binop (CEIL_DIV_EXPR, rli->bitpos,
754 bitsize_unit_node)));
755 rli->bitpos = bitsize_zero_node;
757 rli->offset = round_up (rli->offset, desired_align / BITS_PER_UNIT);
760 if (! TREE_CONSTANT (rli->offset))
761 rli->offset_align = desired_align;
765 /* Handle compatibility with PCC. Note that if the record has any
766 variable-sized fields, we need not worry about compatibility. */
767 #ifdef PCC_BITFIELD_TYPE_MATTERS
768 if (PCC_BITFIELD_TYPE_MATTERS
769 && TREE_CODE (field) == FIELD_DECL
770 && type != error_mark_node
771 && DECL_BIT_FIELD (field)
772 && ! DECL_PACKED (field)
773 && maximum_field_alignment == 0
774 && ! integer_zerop (DECL_SIZE (field))
775 && host_integerp (DECL_SIZE (field), 1)
776 && host_integerp (rli->offset, 1)
777 && host_integerp (TYPE_SIZE (type), 1))
779 unsigned int type_align = TYPE_ALIGN (type);
780 tree dsize = DECL_SIZE (field);
781 HOST_WIDE_INT field_size = tree_low_cst (dsize, 1);
782 HOST_WIDE_INT offset = tree_low_cst (rli->offset, 0);
783 HOST_WIDE_INT bit_offset = tree_low_cst (rli->bitpos, 0);
785 /* A bit field may not span more units of alignment of its type
786 than its type itself. Advance to next boundary if necessary. */
787 if ((((offset * BITS_PER_UNIT + bit_offset + field_size +
790 - (offset * BITS_PER_UNIT + bit_offset) / type_align)
791 > tree_low_cst (TYPE_SIZE (type), 1) / type_align)
792 rli->bitpos = round_up (rli->bitpos, type_align);
796 #ifdef BITFIELD_NBYTES_LIMITED
797 if (BITFIELD_NBYTES_LIMITED
798 && TREE_CODE (field) == FIELD_DECL
799 && type != error_mark_node
800 && DECL_BIT_FIELD_TYPE (field)
801 && ! DECL_PACKED (field)
802 && ! integer_zerop (DECL_SIZE (field))
803 && host_integerp (DECL_SIZE (field), 1)
804 && host_integerp (rli->offset, 1)
805 && host_integerp (TYPE_SIZE (type), 1))
807 unsigned int type_align = TYPE_ALIGN (type);
808 tree dsize = DECL_SIZE (field);
809 HOST_WIDE_INT field_size = tree_low_cst (dsize, 1);
810 HOST_WIDE_INT offset = tree_low_cst (rli->offset, 0);
811 HOST_WIDE_INT bit_offset = tree_low_cst (rli->bitpos, 0);
813 if (maximum_field_alignment != 0)
814 type_align = MIN (type_align, maximum_field_alignment);
815 /* ??? This test is opposite the test in the containing if
816 statement, so this code is unreachable currently. */
817 else if (DECL_PACKED (field))
818 type_align = MIN (type_align, BITS_PER_UNIT);
820 /* A bit field may not span the unit of alignment of its type.
821 Advance to next boundary if necessary. */
822 /* ??? This code should match the code above for the
823 PCC_BITFIELD_TYPE_MATTERS case. */
824 if ((offset * BITS_PER_UNIT + bit_offset) / type_align
825 != ((offset * BITS_PER_UNIT + bit_offset + field_size - 1)
827 rli->bitpos = round_up (rli->bitpos, type_align);
831 /* Offset so far becomes the position of this field after normalizing. */
833 DECL_FIELD_OFFSET (field) = rli->offset;
834 DECL_FIELD_BIT_OFFSET (field) = rli->bitpos;
835 DECL_OFFSET_ALIGN (field) = rli->offset_align;
837 /* If this field ended up more aligned than we thought it would be (we
838 approximate this by seeing if its position changed), lay out the field
839 again; perhaps we can use an integral mode for it now. */
840 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field)))
841 actual_align = (tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1)
842 & - tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1));
843 else if (integer_zerop (DECL_FIELD_OFFSET (field)))
844 actual_align = BIGGEST_ALIGNMENT;
845 else if (host_integerp (DECL_FIELD_OFFSET (field), 1))
846 actual_align = (BITS_PER_UNIT
847 * (tree_low_cst (DECL_FIELD_OFFSET (field), 1)
848 & - tree_low_cst (DECL_FIELD_OFFSET (field), 1)));
850 actual_align = DECL_OFFSET_ALIGN (field);
852 if (known_align != actual_align)
853 layout_decl (field, actual_align);
855 /* Now add size of this field to the size of the record. If the size is
856 not constant, treat the field as being a multiple of bytes and just
857 adjust the offset, resetting the bit position. Otherwise, apportion the
858 size amongst the bit position and offset. First handle the case of an
859 unspecified size, which can happen when we have an invalid nested struct
860 definition, such as struct j { struct j { int i; } }. The error message
861 is printed in finish_struct. */
862 if (DECL_SIZE (field) == 0)
864 else if (! TREE_CONSTANT (DECL_SIZE_UNIT (field)))
867 = size_binop (PLUS_EXPR, rli->offset,
869 size_binop (CEIL_DIV_EXPR, rli->bitpos,
870 bitsize_unit_node)));
872 = size_binop (PLUS_EXPR, rli->offset, DECL_SIZE_UNIT (field));
873 rli->bitpos = bitsize_zero_node;
874 rli->offset_align = MIN (rli->offset_align, DECL_ALIGN (field));
878 rli->bitpos = size_binop (PLUS_EXPR, rli->bitpos, DECL_SIZE (field));
883 /* Assuming that all the fields have been laid out, this function uses
884 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
885 inidicated by RLI. */
888 finalize_record_size (rli)
889 record_layout_info rli;
891 tree unpadded_size, unpadded_size_unit;
893 /* Now we want just byte and bit offsets, so set the offset alignment
894 to be a byte and then normalize. */
895 rli->offset_align = BITS_PER_UNIT;
898 /* Determine the desired alignment. */
899 #ifdef ROUND_TYPE_ALIGN
900 TYPE_ALIGN (rli->t) = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t),
903 TYPE_ALIGN (rli->t) = MAX (TYPE_ALIGN (rli->t), rli->record_align);
906 /* Compute the size so far. Be sure to allow for extra bits in the
907 size in bytes. We have guaranteed above that it will be no more
908 than a single byte. */
909 unpadded_size = rli_size_so_far (rli);
910 unpadded_size_unit = rli_size_unit_so_far (rli);
911 if (! integer_zerop (rli->bitpos))
913 = size_binop (PLUS_EXPR, unpadded_size_unit, size_one_node);
915 /* Record the un-rounded size in the binfo node. But first we check
916 the size of TYPE_BINFO to make sure that BINFO_SIZE is available. */
917 if (TYPE_BINFO (rli->t) && TREE_VEC_LENGTH (TYPE_BINFO (rli->t)) > 6)
919 TYPE_BINFO_SIZE (rli->t) = unpadded_size;
920 TYPE_BINFO_SIZE_UNIT (rli->t) = unpadded_size_unit;
923 /* Round the size up to be a multiple of the required alignment */
924 #ifdef ROUND_TYPE_SIZE
925 TYPE_SIZE (rli->t) = ROUND_TYPE_SIZE (rli->t, unpadded_size,
926 TYPE_ALIGN (rli->t));
927 TYPE_SIZE_UNIT (rli->t)
928 = ROUND_TYPE_SIZE_UNIT (rli->t, unpadded_size_unit,
929 TYPE_ALIGN (rli->t) / BITS_PER_UNIT);
931 TYPE_SIZE (rli->t) = round_up (unpadded_size, TYPE_ALIGN (rli->t));
932 TYPE_SIZE_UNIT (rli->t) = round_up (unpadded_size_unit,
933 TYPE_ALIGN (rli->t) / BITS_PER_UNIT);
936 if (warn_padded && TREE_CONSTANT (unpadded_size)
937 && simple_cst_equal (unpadded_size, TYPE_SIZE (rli->t)) == 0)
938 warning ("padding struct size to alignment boundary");
940 if (warn_packed && TREE_CODE (rli->t) == RECORD_TYPE
941 && TYPE_PACKED (rli->t) && ! rli->packed_maybe_necessary
942 && TREE_CONSTANT (unpadded_size))
946 #ifdef ROUND_TYPE_ALIGN
948 = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t), rli->unpacked_align);
950 rli->unpacked_align = MAX (TYPE_ALIGN (rli->t), rli->unpacked_align);
953 #ifdef ROUND_TYPE_SIZE
954 unpacked_size = ROUND_TYPE_SIZE (rli->t, TYPE_SIZE (rli->t),
955 rli->unpacked_align);
957 unpacked_size = round_up (TYPE_SIZE (rli->t), rli->unpacked_align);
960 if (simple_cst_equal (unpacked_size, TYPE_SIZE (rli->t)))
962 TYPE_PACKED (rli->t) = 0;
964 if (TYPE_NAME (rli->t))
968 if (TREE_CODE (TYPE_NAME (rli->t)) == IDENTIFIER_NODE)
969 name = IDENTIFIER_POINTER (TYPE_NAME (rli->t));
971 name = IDENTIFIER_POINTER (DECL_NAME (TYPE_NAME (rli->t)));
973 if (STRICT_ALIGNMENT)
974 warning ("packed attribute causes inefficient alignment for `%s'", name);
976 warning ("packed attribute is unnecessary for `%s'", name);
980 if (STRICT_ALIGNMENT)
981 warning ("packed attribute causes inefficient alignment");
983 warning ("packed attribute is unnecessary");
989 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
992 compute_record_mode (type)
996 enum machine_mode mode = VOIDmode;
998 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
999 However, if possible, we use a mode that fits in a register
1000 instead, in order to allow for better optimization down the
1002 TYPE_MODE (type) = BLKmode;
1004 if (! host_integerp (TYPE_SIZE (type), 1))
1007 /* A record which has any BLKmode members must itself be
1008 BLKmode; it can't go in a register. Unless the member is
1009 BLKmode only because it isn't aligned. */
1010 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1012 unsigned HOST_WIDE_INT bitpos;
1014 if (TREE_CODE (field) != FIELD_DECL)
1017 if (TREE_CODE (TREE_TYPE (field)) == ERROR_MARK
1018 || (TYPE_MODE (TREE_TYPE (field)) == BLKmode
1019 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field)))
1020 || ! host_integerp (bit_position (field), 1)
1021 || ! host_integerp (DECL_SIZE (field), 1))
1024 bitpos = int_bit_position (field);
1026 /* Must be BLKmode if any field crosses a word boundary,
1027 since extract_bit_field can't handle that in registers. */
1028 if (bitpos / BITS_PER_WORD
1029 != ((TREE_INT_CST_LOW (DECL_SIZE (field)) + bitpos - 1)
1031 /* But there is no problem if the field is entire words. */
1032 && tree_low_cst (DECL_SIZE (field), 1) % BITS_PER_WORD != 0)
1035 /* If this field is the whole struct, remember its mode so
1036 that, say, we can put a double in a class into a DF
1037 register instead of forcing it to live in the stack. */
1038 if (field == TYPE_FIELDS (type) && TREE_CHAIN (field) == 0)
1039 mode = DECL_MODE (field);
1041 #ifdef STRUCT_FORCE_BLK
1042 /* With some targets, eg. c4x, it is sub-optimal
1043 to access an aligned BLKmode structure as a scalar. */
1044 if (mode == VOIDmode && STRUCT_FORCE_BLK (field))
1046 #endif /* STRUCT_FORCE_BLK */
1049 if (mode != VOIDmode)
1050 /* We only have one real field; use its mode. */
1051 TYPE_MODE (type) = mode;
1053 TYPE_MODE (type) = mode_for_size_tree (TYPE_SIZE (type), MODE_INT, 1);
1055 /* If structure's known alignment is less than what the scalar
1056 mode would need, and it matters, then stick with BLKmode. */
1057 if (TYPE_MODE (type) != BLKmode
1059 && ! (TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT
1060 || TYPE_ALIGN (type) >= GET_MODE_ALIGNMENT (TYPE_MODE (type))))
1062 /* If this is the only reason this type is BLKmode, then
1063 don't force containing types to be BLKmode. */
1064 TYPE_NO_FORCE_BLK (type) = 1;
1065 TYPE_MODE (type) = BLKmode;
1069 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1073 finalize_type_size (type)
1076 /* Normally, use the alignment corresponding to the mode chosen.
1077 However, where strict alignment is not required, avoid
1078 over-aligning structures, since most compilers do not do this
1081 if (TYPE_MODE (type) != BLKmode && TYPE_MODE (type) != VOIDmode
1082 && (STRICT_ALIGNMENT
1083 || (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE
1084 && TREE_CODE (type) != QUAL_UNION_TYPE
1085 && TREE_CODE (type) != ARRAY_TYPE)))
1086 TYPE_ALIGN (type) = GET_MODE_ALIGNMENT (TYPE_MODE (type));
1088 /* Do machine-dependent extra alignment. */
1089 #ifdef ROUND_TYPE_ALIGN
1091 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (type), BITS_PER_UNIT);
1094 /* If we failed to find a simple way to calculate the unit size
1095 of the type, find it by division. */
1096 if (TYPE_SIZE_UNIT (type) == 0 && TYPE_SIZE (type) != 0)
1097 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1098 result will fit in sizetype. We will get more efficient code using
1099 sizetype, so we force a conversion. */
1100 TYPE_SIZE_UNIT (type)
1101 = convert (sizetype,
1102 size_binop (FLOOR_DIV_EXPR, TYPE_SIZE (type),
1103 bitsize_unit_node));
1105 if (TYPE_SIZE (type) != 0)
1107 #ifdef ROUND_TYPE_SIZE
1109 = ROUND_TYPE_SIZE (type, TYPE_SIZE (type), TYPE_ALIGN (type));
1110 TYPE_SIZE_UNIT (type)
1111 = ROUND_TYPE_SIZE_UNIT (type, TYPE_SIZE_UNIT (type),
1112 TYPE_ALIGN (type) / BITS_PER_UNIT);
1114 TYPE_SIZE (type) = round_up (TYPE_SIZE (type), TYPE_ALIGN (type));
1115 TYPE_SIZE_UNIT (type)
1116 = round_up (TYPE_SIZE_UNIT (type), TYPE_ALIGN (type) / BITS_PER_UNIT);
1120 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1121 if (TYPE_SIZE (type) != 0 && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
1122 TYPE_SIZE (type) = variable_size (TYPE_SIZE (type));
1123 if (TYPE_SIZE_UNIT (type) != 0
1124 && TREE_CODE (TYPE_SIZE_UNIT (type)) != INTEGER_CST)
1125 TYPE_SIZE_UNIT (type) = variable_size (TYPE_SIZE_UNIT (type));
1127 /* Also layout any other variants of the type. */
1128 if (TYPE_NEXT_VARIANT (type)
1129 || type != TYPE_MAIN_VARIANT (type))
1132 /* Record layout info of this variant. */
1133 tree size = TYPE_SIZE (type);
1134 tree size_unit = TYPE_SIZE_UNIT (type);
1135 unsigned int align = TYPE_ALIGN (type);
1136 enum machine_mode mode = TYPE_MODE (type);
1138 /* Copy it into all variants. */
1139 for (variant = TYPE_MAIN_VARIANT (type);
1141 variant = TYPE_NEXT_VARIANT (variant))
1143 TYPE_SIZE (variant) = size;
1144 TYPE_SIZE_UNIT (variant) = size_unit;
1145 TYPE_ALIGN (variant) = align;
1146 TYPE_MODE (variant) = mode;
1151 /* Do all of the work required to layout the type indicated by RLI,
1152 once the fields have been laid out. This function will call `free'
1156 finish_record_layout (rli)
1157 record_layout_info rli;
1159 /* Compute the final size. */
1160 finalize_record_size (rli);
1162 /* Compute the TYPE_MODE for the record. */
1163 compute_record_mode (rli->t);
1165 /* Perform any last tweaks to the TYPE_SIZE, etc. */
1166 finalize_type_size (rli->t);
1168 /* Lay out any static members. This is done now because their type
1169 may use the record's type. */
1170 while (rli->pending_statics)
1172 layout_decl (TREE_VALUE (rli->pending_statics), 0);
1173 rli->pending_statics = TREE_CHAIN (rli->pending_statics);
1180 /* Calculate the mode, size, and alignment for TYPE.
1181 For an array type, calculate the element separation as well.
1182 Record TYPE on the chain of permanent or temporary types
1183 so that dbxout will find out about it.
1185 TYPE_SIZE of a type is nonzero if the type has been laid out already.
1186 layout_type does nothing on such a type.
1188 If the type is incomplete, its TYPE_SIZE remains zero. */
1199 /* Do nothing if type has been laid out before. */
1200 if (TYPE_SIZE (type))
1203 /* Make sure all nodes we allocate are not momentary; they must last
1204 past the current statement. */
1205 old = suspend_momentary ();
1207 /* Put all our nodes into the same obstack as the type. Also,
1208 make expressions saveable (this is a no-op for permanent types). */
1210 push_obstacks (TYPE_OBSTACK (type), TYPE_OBSTACK (type));
1211 saveable_allocation ();
1213 switch (TREE_CODE (type))
1216 /* This kind of type is the responsibility
1217 of the language-specific code. */
1220 case BOOLEAN_TYPE: /* Used for Java, Pascal, and Chill. */
1221 if (TYPE_PRECISION (type) == 0)
1222 TYPE_PRECISION (type) = 1; /* default to one byte/boolean. */
1224 /* ... fall through ... */
1229 if (TREE_CODE (TYPE_MIN_VALUE (type)) == INTEGER_CST
1230 && tree_int_cst_sgn (TYPE_MIN_VALUE (type)) >= 0)
1231 TREE_UNSIGNED (type) = 1;
1233 TYPE_MODE (type) = smallest_mode_for_size (TYPE_PRECISION (type),
1235 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1236 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1240 TYPE_MODE (type) = mode_for_size (TYPE_PRECISION (type), MODE_FLOAT, 0);
1241 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1242 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1246 TREE_UNSIGNED (type) = TREE_UNSIGNED (TREE_TYPE (type));
1248 = mode_for_size (2 * TYPE_PRECISION (TREE_TYPE (type)),
1249 (TREE_CODE (TREE_TYPE (type)) == INTEGER_TYPE
1250 ? MODE_COMPLEX_INT : MODE_COMPLEX_FLOAT),
1252 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1253 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1257 /* This is an incomplete type and so doesn't have a size. */
1258 TYPE_ALIGN (type) = 1;
1259 TYPE_MODE (type) = VOIDmode;
1263 TYPE_SIZE (type) = bitsize_int (POINTER_SIZE);
1264 TYPE_SIZE_UNIT (type) = size_int (POINTER_SIZE / BITS_PER_UNIT);
1265 TYPE_MODE (type) = ptr_mode;
1270 TYPE_MODE (type) = mode_for_size (2 * POINTER_SIZE, MODE_INT, 0);
1271 TYPE_SIZE (type) = bitsize_int (2 * POINTER_SIZE);
1272 TYPE_SIZE_UNIT (type) = size_int ((2 * POINTER_SIZE) / BITS_PER_UNIT);
1276 case REFERENCE_TYPE:
1277 TYPE_MODE (type) = ptr_mode;
1278 TYPE_SIZE (type) = bitsize_int (POINTER_SIZE);
1279 TYPE_SIZE_UNIT (type) = size_int (POINTER_SIZE / BITS_PER_UNIT);
1280 TREE_UNSIGNED (type) = 1;
1281 TYPE_PRECISION (type) = POINTER_SIZE;
1286 register tree index = TYPE_DOMAIN (type);
1287 register tree element = TREE_TYPE (type);
1289 build_pointer_type (element);
1291 /* We need to know both bounds in order to compute the size. */
1292 if (index && TYPE_MAX_VALUE (index) && TYPE_MIN_VALUE (index)
1293 && TYPE_SIZE (element))
1295 tree ub = TYPE_MAX_VALUE (index);
1296 tree lb = TYPE_MIN_VALUE (index);
1300 /* If UB is max (lb - 1, x), remove the MAX_EXPR since the
1301 test for negative below covers it. */
1302 if (TREE_CODE (ub) == MAX_EXPR
1303 && TREE_CODE (TREE_OPERAND (ub, 0)) == MINUS_EXPR
1304 && integer_onep (TREE_OPERAND (TREE_OPERAND (ub, 0), 1))
1305 && operand_equal_p (TREE_OPERAND (TREE_OPERAND (ub, 0), 0),
1307 ub = TREE_OPERAND (ub, 1);
1308 else if (TREE_CODE (ub) == MAX_EXPR
1309 && TREE_CODE (TREE_OPERAND (ub, 1)) == MINUS_EXPR
1310 && integer_onep (TREE_OPERAND (TREE_OPERAND (ub, 1), 1))
1311 && operand_equal_p (TREE_OPERAND (TREE_OPERAND (ub, 1),
1314 ub = TREE_OPERAND (ub, 0);
1316 /* The initial subtraction should happen in the original type so
1317 that (possible) negative values are handled appropriately. */
1318 length = size_binop (PLUS_EXPR, size_one_node,
1320 fold (build (MINUS_EXPR,
1324 /* If neither bound is a constant and sizetype is signed, make
1325 sure the size is never negative. We should really do this
1326 if *either* bound is non-constant, but this is the best
1327 compromise between C and Ada. */
1328 if (! TREE_UNSIGNED (sizetype)
1329 && TREE_CODE (TYPE_MIN_VALUE (index)) != INTEGER_CST
1330 && TREE_CODE (TYPE_MAX_VALUE (index)) != INTEGER_CST)
1331 length = size_binop (MAX_EXPR, length, size_zero_node);
1333 /* Special handling for arrays of bits (for Chill). */
1334 element_size = TYPE_SIZE (element);
1335 if (TYPE_PACKED (type) && INTEGRAL_TYPE_P (element))
1337 HOST_WIDE_INT maxvalue
1338 = TREE_INT_CST_LOW (TYPE_MAX_VALUE (element));
1339 HOST_WIDE_INT minvalue
1340 = TREE_INT_CST_LOW (TYPE_MIN_VALUE (element));
1342 if (maxvalue - minvalue == 1
1343 && (maxvalue == 1 || maxvalue == 0))
1344 element_size = integer_one_node;
1347 TYPE_SIZE (type) = size_binop (MULT_EXPR, element_size,
1348 convert (bitsizetype, length));
1350 /* If we know the size of the element, calculate the total
1351 size directly, rather than do some division thing below.
1352 This optimization helps Fortran assumed-size arrays
1353 (where the size of the array is determined at runtime)
1355 Note that we can't do this in the case where the size of
1356 the elements is one bit since TYPE_SIZE_UNIT cannot be
1357 set correctly in that case. */
1358 if (TYPE_SIZE_UNIT (element) != 0 && ! integer_onep (element_size))
1359 TYPE_SIZE_UNIT (type)
1360 = size_binop (MULT_EXPR, TYPE_SIZE_UNIT (element), length);
1363 /* Now round the alignment and size,
1364 using machine-dependent criteria if any. */
1366 #ifdef ROUND_TYPE_ALIGN
1368 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (element), BITS_PER_UNIT);
1370 TYPE_ALIGN (type) = MAX (TYPE_ALIGN (element), BITS_PER_UNIT);
1373 #ifdef ROUND_TYPE_SIZE
1374 if (TYPE_SIZE (type) != 0)
1377 = ROUND_TYPE_SIZE (type, TYPE_SIZE (type), TYPE_ALIGN (type));
1379 /* If the rounding changed the size of the type, remove any
1380 pre-calculated TYPE_SIZE_UNIT. */
1381 if (simple_cst_equal (TYPE_SIZE (type), tmp) != 1)
1382 TYPE_SIZE_UNIT (type) = NULL;
1384 TYPE_SIZE (type) = tmp;
1388 TYPE_MODE (type) = BLKmode;
1389 if (TYPE_SIZE (type) != 0
1390 /* BLKmode elements force BLKmode aggregate;
1391 else extract/store fields may lose. */
1392 && (TYPE_MODE (TREE_TYPE (type)) != BLKmode
1393 || TYPE_NO_FORCE_BLK (TREE_TYPE (type))))
1396 = mode_for_size_tree (TYPE_SIZE (type), MODE_INT, 1);
1398 if (TYPE_MODE (type) != BLKmode
1399 && STRICT_ALIGNMENT && TYPE_ALIGN (type) < BIGGEST_ALIGNMENT
1400 && TYPE_ALIGN (type) < GET_MODE_ALIGNMENT (TYPE_MODE (type))
1401 && TYPE_MODE (type) != BLKmode)
1403 TYPE_NO_FORCE_BLK (type) = 1;
1404 TYPE_MODE (type) = BLKmode;
1412 case QUAL_UNION_TYPE:
1415 record_layout_info rli;
1417 /* Initialize the layout information. */
1418 rli = start_record_layout (type);
1420 /* If this is a QUAL_UNION_TYPE, we want to process the fields
1421 in the reverse order in building the COND_EXPR that denotes
1422 its size. We reverse them again later. */
1423 if (TREE_CODE (type) == QUAL_UNION_TYPE)
1424 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
1426 /* Place all the fields. */
1427 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1428 place_field (rli, field);
1430 if (TREE_CODE (type) == QUAL_UNION_TYPE)
1431 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
1433 /* Finish laying out the record. */
1434 finish_record_layout (rli);
1438 case SET_TYPE: /* Used by Chill and Pascal. */
1439 if (TREE_CODE (TYPE_MAX_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST
1440 || TREE_CODE (TYPE_MIN_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST)
1444 #ifndef SET_WORD_SIZE
1445 #define SET_WORD_SIZE BITS_PER_WORD
1447 unsigned int alignment
1448 = set_alignment ? set_alignment : SET_WORD_SIZE;
1450 = (TREE_INT_CST_LOW (TYPE_MAX_VALUE (TYPE_DOMAIN (type)))
1451 - TREE_INT_CST_LOW (TYPE_MIN_VALUE (TYPE_DOMAIN (type))) + 1);
1453 = ((size_in_bits + alignment - 1) / alignment) * alignment;
1455 if (rounded_size > (int) alignment)
1456 TYPE_MODE (type) = BLKmode;
1458 TYPE_MODE (type) = mode_for_size (alignment, MODE_INT, 1);
1460 TYPE_SIZE (type) = bitsize_int (rounded_size);
1461 TYPE_SIZE_UNIT (type) = size_int (rounded_size / BITS_PER_UNIT);
1462 TYPE_ALIGN (type) = alignment;
1463 TYPE_PRECISION (type) = size_in_bits;
1468 /* The size may vary in different languages, so the language front end
1469 should fill in the size. */
1470 TYPE_ALIGN (type) = BIGGEST_ALIGNMENT;
1471 TYPE_MODE (type) = BLKmode;
1478 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
1479 records and unions, finish_record_layout already called this
1481 if (TREE_CODE (type) != RECORD_TYPE
1482 && TREE_CODE (type) != UNION_TYPE
1483 && TREE_CODE (type) != QUAL_UNION_TYPE)
1484 finalize_type_size (type);
1487 resume_momentary (old);
1489 /* If this type is created before sizetype has been permanently set,
1490 record it so set_sizetype can fix it up. */
1492 early_type_list = tree_cons (NULL_TREE, type, early_type_list);
1495 /* Create and return a type for signed integers of PRECISION bits. */
1498 make_signed_type (precision)
1501 register tree type = make_node (INTEGER_TYPE);
1503 TYPE_PRECISION (type) = precision;
1505 fixup_signed_type (type);
1509 /* Create and return a type for unsigned integers of PRECISION bits. */
1512 make_unsigned_type (precision)
1515 register tree type = make_node (INTEGER_TYPE);
1517 TYPE_PRECISION (type) = precision;
1519 fixup_unsigned_type (type);
1523 /* Initialize sizetype and bitsizetype to a reasonable and temporary
1524 value to enable integer types to be created. */
1527 initialize_sizetypes ()
1529 tree t = make_node (INTEGER_TYPE);
1531 /* Set this so we do something reasonable for the build_int_2 calls
1533 integer_type_node = t;
1535 TYPE_MODE (t) = SImode;
1536 TYPE_ALIGN (t) = GET_MODE_ALIGNMENT (SImode);
1537 TYPE_SIZE (t) = build_int_2 (GET_MODE_BITSIZE (SImode), 0);
1538 TYPE_SIZE_UNIT (t) = build_int_2 (GET_MODE_SIZE (SImode), 0);
1539 TREE_UNSIGNED (t) = 1;
1540 TYPE_PRECISION (t) = GET_MODE_BITSIZE (SImode);
1541 TYPE_MIN_VALUE (t) = build_int_2 (0, 0);
1542 TYPE_IS_SIZETYPE (t) = 1;
1544 /* 1000 avoids problems with possible overflow and is certainly
1545 larger than any size value we'd want to be storing. */
1546 TYPE_MAX_VALUE (t) = build_int_2 (1000, 0);
1548 /* These two must be different nodes because of the caching done in
1551 bitsizetype = copy_node (t);
1552 integer_type_node = 0;
1555 /* Set sizetype to TYPE, and initialize *sizetype accordingly.
1556 Also update the type of any standard type's sizes made so far. */
1562 int oprecision = TYPE_PRECISION (type);
1563 /* The *bitsizetype types use a precision that avoids overflows when
1564 calculating signed sizes / offsets in bits. However, when
1565 cross-compiling from a 32 bit to a 64 bit host, we are limited to 64 bit
1567 int precision = MIN (oprecision + BITS_PER_UNIT_LOG + 1,
1568 2 * HOST_BITS_PER_WIDE_INT);
1575 /* Make copies of nodes since we'll be setting TYPE_IS_SIZETYPE. */
1576 sizetype = copy_node (type);
1577 TYPE_DOMAIN (sizetype) = type;
1578 TYPE_IS_SIZETYPE (sizetype) = 1;
1579 bitsizetype = make_node (INTEGER_TYPE);
1580 TYPE_NAME (bitsizetype) = TYPE_NAME (type);
1581 TYPE_PRECISION (bitsizetype) = precision;
1582 TYPE_IS_SIZETYPE (bitsizetype) = 1;
1584 if (TREE_UNSIGNED (type))
1585 fixup_unsigned_type (bitsizetype);
1587 fixup_signed_type (bitsizetype);
1589 layout_type (bitsizetype);
1591 if (TREE_UNSIGNED (type))
1593 usizetype = sizetype;
1594 ubitsizetype = bitsizetype;
1595 ssizetype = copy_node (make_signed_type (oprecision));
1596 sbitsizetype = copy_node (make_signed_type (precision));
1600 ssizetype = sizetype;
1601 sbitsizetype = bitsizetype;
1602 usizetype = copy_node (make_unsigned_type (oprecision));
1603 ubitsizetype = copy_node (make_unsigned_type (precision));
1606 TYPE_NAME (bitsizetype) = get_identifier ("bit_size_type");
1608 /* Show is a sizetype, is a main type, and has no pointers to it. */
1609 for (i = 0; i < sizeof sizetype_tab / sizeof sizetype_tab[0]; i++)
1611 TYPE_IS_SIZETYPE (sizetype_tab[i]) = 1;
1612 TYPE_MAIN_VARIANT (sizetype_tab[i]) = sizetype_tab[i];
1613 TYPE_NEXT_VARIANT (sizetype_tab[i]) = 0;
1614 TYPE_POINTER_TO (sizetype_tab[i]) = 0;
1615 TYPE_REFERENCE_TO (sizetype_tab[i]) = 0;
1618 ggc_add_tree_root ((tree *) &sizetype_tab,
1619 sizeof sizetype_tab / sizeof (tree));
1621 /* Go down each of the types we already made and set the proper type
1622 for the sizes in them. */
1623 for (t = early_type_list; t != 0; t = TREE_CHAIN (t))
1625 if (TREE_CODE (TREE_VALUE (t)) != INTEGER_TYPE)
1628 TREE_TYPE (TYPE_SIZE (TREE_VALUE (t))) = bitsizetype;
1629 TREE_TYPE (TYPE_SIZE_UNIT (TREE_VALUE (t))) = sizetype;
1632 early_type_list = 0;
1636 /* Set the extreme values of TYPE based on its precision in bits,
1637 then lay it out. Used when make_signed_type won't do
1638 because the tree code is not INTEGER_TYPE.
1639 E.g. for Pascal, when the -fsigned-char option is given. */
1642 fixup_signed_type (type)
1645 register int precision = TYPE_PRECISION (type);
1647 TYPE_MIN_VALUE (type)
1648 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1649 ? 0 : (HOST_WIDE_INT) (-1) << (precision - 1)),
1650 (((HOST_WIDE_INT) (-1)
1651 << (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1652 ? precision - HOST_BITS_PER_WIDE_INT - 1
1654 TYPE_MAX_VALUE (type)
1655 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1656 ? -1 : ((HOST_WIDE_INT) 1 << (precision - 1)) - 1),
1657 (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1658 ? (((HOST_WIDE_INT) 1
1659 << (precision - HOST_BITS_PER_WIDE_INT - 1))) - 1
1662 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
1663 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
1665 /* Lay out the type: set its alignment, size, etc. */
1669 /* Set the extreme values of TYPE based on its precision in bits,
1670 then lay it out. This is used both in `make_unsigned_type'
1671 and for enumeral types. */
1674 fixup_unsigned_type (type)
1677 register int precision = TYPE_PRECISION (type);
1679 TYPE_MIN_VALUE (type) = build_int_2 (0, 0);
1680 TYPE_MAX_VALUE (type)
1681 = build_int_2 (precision - HOST_BITS_PER_WIDE_INT >= 0
1682 ? -1 : ((HOST_WIDE_INT) 1 << precision) - 1,
1683 precision - HOST_BITS_PER_WIDE_INT > 0
1684 ? ((unsigned HOST_WIDE_INT) ~0
1685 >> (HOST_BITS_PER_WIDE_INT
1686 - (precision - HOST_BITS_PER_WIDE_INT)))
1688 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
1689 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
1691 /* Lay out the type: set its alignment, size, etc. */
1695 /* Find the best machine mode to use when referencing a bit field of length
1696 BITSIZE bits starting at BITPOS.
1698 The underlying object is known to be aligned to a boundary of ALIGN bits.
1699 If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
1700 larger than LARGEST_MODE (usually SImode).
1702 If no mode meets all these conditions, we return VOIDmode. Otherwise, if
1703 VOLATILEP is true or SLOW_BYTE_ACCESS is false, we return the smallest
1704 mode meeting these conditions.
1706 Otherwise (VOLATILEP is false and SLOW_BYTE_ACCESS is true), we return
1707 the largest mode (but a mode no wider than UNITS_PER_WORD) that meets
1708 all the conditions. */
1711 get_best_mode (bitsize, bitpos, align, largest_mode, volatilep)
1712 int bitsize, bitpos;
1714 enum machine_mode largest_mode;
1717 enum machine_mode mode;
1718 unsigned int unit = 0;
1720 /* Find the narrowest integer mode that contains the bit field. */
1721 for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
1722 mode = GET_MODE_WIDER_MODE (mode))
1724 unit = GET_MODE_BITSIZE (mode);
1725 if ((bitpos % unit) + bitsize <= unit)
1729 if (mode == VOIDmode
1730 /* It is tempting to omit the following line
1731 if STRICT_ALIGNMENT is true.
1732 But that is incorrect, since if the bitfield uses part of 3 bytes
1733 and we use a 4-byte mode, we could get a spurious segv
1734 if the extra 4th byte is past the end of memory.
1735 (Though at least one Unix compiler ignores this problem:
1736 that on the Sequent 386 machine. */
1737 || MIN (unit, BIGGEST_ALIGNMENT) > align
1738 || (largest_mode != VOIDmode && unit > GET_MODE_BITSIZE (largest_mode)))
1741 if (SLOW_BYTE_ACCESS && ! volatilep)
1743 enum machine_mode wide_mode = VOIDmode, tmode;
1745 for (tmode = GET_CLASS_NARROWEST_MODE (MODE_INT); tmode != VOIDmode;
1746 tmode = GET_MODE_WIDER_MODE (tmode))
1748 unit = GET_MODE_BITSIZE (tmode);
1749 if (bitpos / unit == (bitpos + bitsize - 1) / unit
1750 && unit <= BITS_PER_WORD
1751 && unit <= MIN (align, BIGGEST_ALIGNMENT)
1752 && (largest_mode == VOIDmode
1753 || unit <= GET_MODE_BITSIZE (largest_mode)))
1757 if (wide_mode != VOIDmode)
1764 /* Return the alignment of MODE. This will be bounded by 1 and
1765 BIGGEST_ALIGNMENT. */
1768 get_mode_alignment (mode)
1769 enum machine_mode mode;
1771 unsigned int alignment = GET_MODE_UNIT_SIZE (mode) * BITS_PER_UNIT;
1773 /* Extract the LSB of the size. */
1774 alignment = alignment & -alignment;
1776 alignment = MIN (BIGGEST_ALIGNMENT, MAX (1, alignment));
1780 /* This function is run once to initialize stor-layout.c. */
1783 init_stor_layout_once ()
1785 ggc_add_tree_root (&pending_sizes, 1);