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, 2001, 2002 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
34 #include "langhooks.h"
36 /* Set to one when set_sizetype has been called. */
37 static int sizetype_set;
39 /* List of types created before set_sizetype has been called. We do not
40 make this a GGC root since we want these nodes to be reclaimed. */
41 static tree early_type_list;
43 /* Data type for the expressions representing sizes of data types.
44 It is the first integer type laid out. */
45 tree sizetype_tab[(int) TYPE_KIND_LAST];
47 /* If nonzero, this is an upper limit on alignment of structure fields.
48 The value is measured in bits. */
49 unsigned int maximum_field_alignment;
51 /* If non-zero, the alignment of a bitstring or (power-)set value, in bits.
52 May be overridden by front-ends. */
53 unsigned int set_alignment = 0;
55 /* Nonzero if all REFERENCE_TYPEs are internal and hence should be
56 allocated in Pmode, not ptr_mode. Set only by internal_reference_types
57 called only by a front end. */
58 static int reference_types_internal = 0;
60 static void finalize_record_size PARAMS ((record_layout_info));
61 static void finalize_type_size PARAMS ((tree));
62 static void place_union_field PARAMS ((record_layout_info, tree));
63 extern void debug_rli PARAMS ((record_layout_info));
65 /* SAVE_EXPRs for sizes of types and decls, waiting to be expanded. */
67 static GTY(()) tree pending_sizes;
69 /* Nonzero means cannot safely call expand_expr now,
70 so put variable sizes onto `pending_sizes' instead. */
72 int immediate_size_expand;
74 /* Show that REFERENCE_TYPES are internal and should be Pmode. Called only
78 internal_reference_types ()
80 reference_types_internal = 1;
83 /* Get a list of all the objects put on the pending sizes list. */
88 tree chain = pending_sizes;
91 /* Put each SAVE_EXPR into the current function. */
92 for (t = chain; t; t = TREE_CHAIN (t))
93 SAVE_EXPR_CONTEXT (TREE_VALUE (t)) = current_function_decl;
99 /* Return non-zero if EXPR is present on the pending sizes list. */
102 is_pending_size (expr)
107 for (t = pending_sizes; t; t = TREE_CHAIN (t))
108 if (TREE_VALUE (t) == expr)
113 /* Add EXPR to the pending sizes list. */
116 put_pending_size (expr)
119 /* Strip any simple arithmetic from EXPR to see if it has an underlying
121 while (TREE_CODE_CLASS (TREE_CODE (expr)) == '1'
122 || (TREE_CODE_CLASS (TREE_CODE (expr)) == '2'
123 && TREE_CONSTANT (TREE_OPERAND (expr, 1))))
124 expr = TREE_OPERAND (expr, 0);
126 if (TREE_CODE (expr) == SAVE_EXPR)
127 pending_sizes = tree_cons (NULL_TREE, expr, pending_sizes);
130 /* Put a chain of objects into the pending sizes list, which must be
134 put_pending_sizes (chain)
140 pending_sizes = chain;
143 /* Given a size SIZE that may not be a constant, return a SAVE_EXPR
144 to serve as the actual size-expression for a type or decl. */
150 /* If the language-processor is to take responsibility for variable-sized
151 items (e.g., languages which have elaboration procedures like Ada),
152 just return SIZE unchanged. Likewise for self-referential sizes and
154 if (TREE_CONSTANT (size)
155 || (*lang_hooks.decls.global_bindings_p) () < 0
156 || contains_placeholder_p (size))
159 size = save_expr (size);
161 /* If an array with a variable number of elements is declared, and
162 the elements require destruction, we will emit a cleanup for the
163 array. That cleanup is run both on normal exit from the block
164 and in the exception-handler for the block. Normally, when code
165 is used in both ordinary code and in an exception handler it is
166 `unsaved', i.e., all SAVE_EXPRs are recalculated. However, we do
167 not wish to do that here; the array-size is the same in both
169 if (TREE_CODE (size) == SAVE_EXPR)
170 SAVE_EXPR_PERSISTENT_P (size) = 1;
172 if ((*lang_hooks.decls.global_bindings_p) ())
174 if (TREE_CONSTANT (size))
175 error ("type size can't be explicitly evaluated");
177 error ("variable-size type declared outside of any function");
179 return size_one_node;
182 if (immediate_size_expand)
183 /* NULL_RTX is not defined; neither is the rtx type.
184 Also, we would like to pass const0_rtx here, but don't have it. */
185 expand_expr (size, expand_expr (integer_zero_node, NULL_RTX, VOIDmode, 0),
187 else if (cfun != 0 && cfun->x_dont_save_pending_sizes_p)
188 /* The front-end doesn't want us to keep a list of the expressions
189 that determine sizes for variable size objects. */
192 put_pending_size (size);
197 #ifndef MAX_FIXED_MODE_SIZE
198 #define MAX_FIXED_MODE_SIZE GET_MODE_BITSIZE (DImode)
201 /* Return the machine mode to use for a nonscalar of SIZE bits.
202 The mode must be in class CLASS, and have exactly that many bits.
203 If LIMIT is nonzero, modes of wider than MAX_FIXED_MODE_SIZE will not
207 mode_for_size (size, class, limit)
209 enum mode_class class;
212 enum machine_mode mode;
214 if (limit && size > MAX_FIXED_MODE_SIZE)
217 /* Get the first mode which has this size, in the specified class. */
218 for (mode = GET_CLASS_NARROWEST_MODE (class); mode != VOIDmode;
219 mode = GET_MODE_WIDER_MODE (mode))
220 if (GET_MODE_BITSIZE (mode) == size)
226 /* Similar, except passed a tree node. */
229 mode_for_size_tree (size, class, limit)
231 enum mode_class class;
234 if (TREE_CODE (size) != INTEGER_CST
235 /* What we really want to say here is that the size can fit in a
236 host integer, but we know there's no way we'd find a mode for
237 this many bits, so there's no point in doing the precise test. */
238 || compare_tree_int (size, 1000) > 0)
241 return mode_for_size (TREE_INT_CST_LOW (size), class, limit);
244 /* Similar, but never return BLKmode; return the narrowest mode that
245 contains at least the requested number of bits. */
248 smallest_mode_for_size (size, class)
250 enum mode_class class;
252 enum machine_mode mode;
254 /* Get the first mode which has at least this size, in the
256 for (mode = GET_CLASS_NARROWEST_MODE (class); mode != VOIDmode;
257 mode = GET_MODE_WIDER_MODE (mode))
258 if (GET_MODE_BITSIZE (mode) >= size)
264 /* Find an integer mode of the exact same size, or BLKmode on failure. */
267 int_mode_for_mode (mode)
268 enum machine_mode mode;
270 switch (GET_MODE_CLASS (mode))
273 case MODE_PARTIAL_INT:
276 case MODE_COMPLEX_INT:
277 case MODE_COMPLEX_FLOAT:
279 case MODE_VECTOR_INT:
280 case MODE_VECTOR_FLOAT:
281 mode = mode_for_size (GET_MODE_BITSIZE (mode), MODE_INT, 0);
288 /* ... fall through ... */
298 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
299 This can only be applied to objects of a sizetype. */
302 round_up (value, divisor)
306 tree arg = size_int_type (divisor, TREE_TYPE (value));
308 return size_binop (MULT_EXPR, size_binop (CEIL_DIV_EXPR, value, arg), arg);
311 /* Likewise, but round down. */
314 round_down (value, divisor)
318 tree arg = size_int_type (divisor, TREE_TYPE (value));
320 return size_binop (MULT_EXPR, size_binop (FLOOR_DIV_EXPR, value, arg), arg);
323 /* Set the size, mode and alignment of a ..._DECL node.
324 TYPE_DECL does need this for C++.
325 Note that LABEL_DECL and CONST_DECL nodes do not need this,
326 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
327 Don't call layout_decl for them.
329 KNOWN_ALIGN is the amount of alignment we can assume this
330 decl has with no special effort. It is relevant only for FIELD_DECLs
331 and depends on the previous fields.
332 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
333 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
334 the record will be aligned to suit. */
337 layout_decl (decl, known_align)
339 unsigned int known_align;
341 tree type = TREE_TYPE (decl);
342 enum tree_code code = TREE_CODE (decl);
344 if (code == CONST_DECL)
346 else if (code != VAR_DECL && code != PARM_DECL && code != RESULT_DECL
347 && code != TYPE_DECL && code != FIELD_DECL)
350 if (type == error_mark_node)
351 type = void_type_node;
353 /* Usually the size and mode come from the data type without change,
354 however, the front-end may set the explicit width of the field, so its
355 size may not be the same as the size of its type. This happens with
356 bitfields, of course (an `int' bitfield may be only 2 bits, say), but it
357 also happens with other fields. For example, the C++ front-end creates
358 zero-sized fields corresponding to empty base classes, and depends on
359 layout_type setting DECL_FIELD_BITPOS correctly for the field. Set the
360 size in bytes from the size in bits. If we have already set the mode,
361 don't set it again since we can be called twice for FIELD_DECLs. */
363 TREE_UNSIGNED (decl) = TREE_UNSIGNED (type);
364 if (DECL_MODE (decl) == VOIDmode)
365 DECL_MODE (decl) = TYPE_MODE (type);
367 if (DECL_SIZE (decl) == 0)
369 DECL_SIZE (decl) = TYPE_SIZE (type);
370 DECL_SIZE_UNIT (decl) = TYPE_SIZE_UNIT (type);
373 DECL_SIZE_UNIT (decl)
374 = convert (sizetype, size_binop (CEIL_DIV_EXPR, DECL_SIZE (decl),
377 /* Force alignment required for the data type.
378 But if the decl itself wants greater alignment, don't override that.
379 Likewise, if the decl is packed, don't override it. */
380 if (! (code == FIELD_DECL && DECL_BIT_FIELD (decl))
381 && (DECL_ALIGN (decl) == 0
382 || (! (code == FIELD_DECL && DECL_PACKED (decl))
383 && TYPE_ALIGN (type) > DECL_ALIGN (decl))))
385 DECL_ALIGN (decl) = TYPE_ALIGN (type);
386 DECL_USER_ALIGN (decl) = 0;
389 /* For fields, set the bit field type and update the alignment. */
390 if (code == FIELD_DECL)
392 DECL_BIT_FIELD_TYPE (decl) = DECL_BIT_FIELD (decl) ? type : 0;
393 if (maximum_field_alignment != 0)
394 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), maximum_field_alignment);
396 /* If the field is of variable size, we can't misalign it since we
397 have no way to make a temporary to align the result. But this
398 isn't an issue if the decl is not addressable. Likewise if it
399 is of unknown size. */
400 else if (DECL_PACKED (decl)
401 && (DECL_NONADDRESSABLE_P (decl)
402 || DECL_SIZE_UNIT (decl) == 0
403 || TREE_CODE (DECL_SIZE_UNIT (decl)) == INTEGER_CST))
405 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), BITS_PER_UNIT);
406 DECL_USER_ALIGN (decl) = 0;
410 /* See if we can use an ordinary integer mode for a bit-field.
411 Conditions are: a fixed size that is correct for another mode
412 and occupying a complete byte or bytes on proper boundary. */
413 if (code == FIELD_DECL && DECL_BIT_FIELD (decl)
414 && TYPE_SIZE (type) != 0
415 && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
416 && GET_MODE_CLASS (TYPE_MODE (type)) == MODE_INT)
418 enum machine_mode xmode
419 = mode_for_size_tree (DECL_SIZE (decl), MODE_INT, 1);
421 if (xmode != BLKmode && known_align >= GET_MODE_ALIGNMENT (xmode))
423 DECL_ALIGN (decl) = MAX (GET_MODE_ALIGNMENT (xmode),
425 DECL_MODE (decl) = xmode;
426 DECL_BIT_FIELD (decl) = 0;
430 /* Turn off DECL_BIT_FIELD if we won't need it set. */
431 if (code == FIELD_DECL && DECL_BIT_FIELD (decl)
432 && TYPE_MODE (type) == BLKmode && DECL_MODE (decl) == BLKmode
433 && known_align >= TYPE_ALIGN (type)
434 && DECL_ALIGN (decl) >= TYPE_ALIGN (type)
435 && DECL_SIZE_UNIT (decl) != 0)
436 DECL_BIT_FIELD (decl) = 0;
438 /* Evaluate nonconstant size only once, either now or as soon as safe. */
439 if (DECL_SIZE (decl) != 0 && TREE_CODE (DECL_SIZE (decl)) != INTEGER_CST)
440 DECL_SIZE (decl) = variable_size (DECL_SIZE (decl));
441 if (DECL_SIZE_UNIT (decl) != 0
442 && TREE_CODE (DECL_SIZE_UNIT (decl)) != INTEGER_CST)
443 DECL_SIZE_UNIT (decl) = variable_size (DECL_SIZE_UNIT (decl));
445 /* If requested, warn about definitions of large data objects. */
447 && (code == VAR_DECL || code == PARM_DECL)
448 && ! DECL_EXTERNAL (decl))
450 tree size = DECL_SIZE_UNIT (decl);
452 if (size != 0 && TREE_CODE (size) == INTEGER_CST
453 && compare_tree_int (size, larger_than_size) > 0)
455 unsigned int size_as_int = TREE_INT_CST_LOW (size);
457 if (compare_tree_int (size, size_as_int) == 0)
458 warning_with_decl (decl, "size of `%s' is %d bytes", size_as_int);
460 warning_with_decl (decl, "size of `%s' is larger than %d bytes",
466 /* Hook for a front-end function that can modify the record layout as needed
467 immediately before it is finalized. */
469 void (*lang_adjust_rli) PARAMS ((record_layout_info)) = 0;
472 set_lang_adjust_rli (f)
473 void (*f) PARAMS ((record_layout_info));
478 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
479 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
480 is to be passed to all other layout functions for this record. It is the
481 responsibility of the caller to call `free' for the storage returned.
482 Note that garbage collection is not permitted until we finish laying
486 start_record_layout (t)
489 record_layout_info rli
490 = (record_layout_info) xmalloc (sizeof (struct record_layout_info_s));
494 /* If the type has a minimum specified alignment (via an attribute
495 declaration, for example) use it -- otherwise, start with a
496 one-byte alignment. */
497 rli->record_align = MAX (BITS_PER_UNIT, TYPE_ALIGN (t));
498 rli->unpacked_align = rli->unpadded_align = rli->record_align;
499 rli->offset_align = MAX (rli->record_align, BIGGEST_ALIGNMENT);
501 #ifdef STRUCTURE_SIZE_BOUNDARY
502 /* Packed structures don't need to have minimum size. */
503 if (! TYPE_PACKED (t))
504 rli->record_align = MAX (rli->record_align, STRUCTURE_SIZE_BOUNDARY);
507 rli->offset = size_zero_node;
508 rli->bitpos = bitsize_zero_node;
510 rli->pending_statics = 0;
511 rli->packed_maybe_necessary = 0;
516 /* These four routines perform computations that convert between
517 the offset/bitpos forms and byte and bit offsets. */
520 bit_from_pos (offset, bitpos)
523 return size_binop (PLUS_EXPR, bitpos,
524 size_binop (MULT_EXPR, convert (bitsizetype, offset),
529 byte_from_pos (offset, bitpos)
532 return size_binop (PLUS_EXPR, offset,
534 size_binop (TRUNC_DIV_EXPR, bitpos,
535 bitsize_unit_node)));
539 pos_from_byte (poffset, pbitpos, off_align, pos)
540 tree *poffset, *pbitpos;
541 unsigned int off_align;
545 = size_binop (MULT_EXPR,
547 size_binop (FLOOR_DIV_EXPR, pos,
548 bitsize_int (off_align
550 size_int (off_align / BITS_PER_UNIT));
551 *pbitpos = size_binop (MULT_EXPR,
552 size_binop (FLOOR_MOD_EXPR, pos,
553 bitsize_int (off_align / BITS_PER_UNIT)),
558 pos_from_bit (poffset, pbitpos, off_align, pos)
559 tree *poffset, *pbitpos;
560 unsigned int off_align;
563 *poffset = size_binop (MULT_EXPR,
565 size_binop (FLOOR_DIV_EXPR, pos,
566 bitsize_int (off_align))),
567 size_int (off_align / BITS_PER_UNIT));
568 *pbitpos = size_binop (FLOOR_MOD_EXPR, pos, bitsize_int (off_align));
571 /* Given a pointer to bit and byte offsets and an offset alignment,
572 normalize the offsets so they are within the alignment. */
575 normalize_offset (poffset, pbitpos, off_align)
576 tree *poffset, *pbitpos;
577 unsigned int off_align;
579 /* If the bit position is now larger than it should be, adjust it
581 if (compare_tree_int (*pbitpos, off_align) >= 0)
583 tree extra_aligns = size_binop (FLOOR_DIV_EXPR, *pbitpos,
584 bitsize_int (off_align));
587 = size_binop (PLUS_EXPR, *poffset,
588 size_binop (MULT_EXPR, convert (sizetype, extra_aligns),
589 size_int (off_align / BITS_PER_UNIT)));
592 = size_binop (FLOOR_MOD_EXPR, *pbitpos, bitsize_int (off_align));
596 /* Print debugging information about the information in RLI. */
600 record_layout_info rli;
602 print_node_brief (stderr, "type", rli->t, 0);
603 print_node_brief (stderr, "\noffset", rli->offset, 0);
604 print_node_brief (stderr, " bitpos", rli->bitpos, 0);
606 fprintf (stderr, "\naligns: rec = %u, unpack = %u, unpad = %u, off = %u\n",
607 rli->record_align, rli->unpacked_align, rli->unpadded_align,
609 if (rli->packed_maybe_necessary)
610 fprintf (stderr, "packed may be necessary\n");
612 if (rli->pending_statics)
614 fprintf (stderr, "pending statics:\n");
615 debug_tree (rli->pending_statics);
619 /* Given an RLI with a possibly-incremented BITPOS, adjust OFFSET and
620 BITPOS if necessary to keep BITPOS below OFFSET_ALIGN. */
624 record_layout_info rli;
626 normalize_offset (&rli->offset, &rli->bitpos, rli->offset_align);
629 /* Returns the size in bytes allocated so far. */
632 rli_size_unit_so_far (rli)
633 record_layout_info rli;
635 return byte_from_pos (rli->offset, rli->bitpos);
638 /* Returns the size in bits allocated so far. */
641 rli_size_so_far (rli)
642 record_layout_info rli;
644 return bit_from_pos (rli->offset, rli->bitpos);
647 /* Called from place_field to handle unions. */
650 place_union_field (rli, field)
651 record_layout_info rli;
654 unsigned int desired_align;
656 layout_decl (field, 0);
658 DECL_FIELD_OFFSET (field) = size_zero_node;
659 DECL_FIELD_BIT_OFFSET (field) = bitsize_zero_node;
660 SET_DECL_OFFSET_ALIGN (field, BIGGEST_ALIGNMENT);
662 desired_align = DECL_ALIGN (field);
664 #ifdef BIGGEST_FIELD_ALIGNMENT
665 /* Some targets (i.e. i386) limit union field alignment
666 to a lower boundary than alignment of variables unless
667 it was overridden by attribute aligned. */
668 if (! DECL_USER_ALIGN (field))
670 MIN (desired_align, (unsigned) BIGGEST_FIELD_ALIGNMENT);
673 #ifdef ADJUST_FIELD_ALIGN
674 if (! DECL_USER_ALIGN (field))
675 desired_align = ADJUST_FIELD_ALIGN (field, desired_align);
678 TYPE_USER_ALIGN (rli->t) |= DECL_USER_ALIGN (field);
680 /* Union must be at least as aligned as any field requires. */
681 rli->record_align = MAX (rli->record_align, desired_align);
682 rli->unpadded_align = MAX (rli->unpadded_align, desired_align);
684 #ifdef PCC_BITFIELD_TYPE_MATTERS
685 /* On the m88000, a bit field of declare type `int' forces the
686 entire union to have `int' alignment. */
687 if (PCC_BITFIELD_TYPE_MATTERS && DECL_BIT_FIELD_TYPE (field))
689 unsigned int type_align = TYPE_ALIGN (TREE_TYPE (field));
691 #ifdef ADJUST_FIELD_ALIGN
692 if (! TYPE_USER_ALIGN (TREE_TYPE (field)))
693 type_align = ADJUST_FIELD_ALIGN (field, type_align);
695 rli->record_align = MAX (rli->record_align, type_align);
696 rli->unpadded_align = MAX (rli->unpadded_align, type_align);
700 /* We assume the union's size will be a multiple of a byte so we don't
701 bother with BITPOS. */
702 if (TREE_CODE (rli->t) == UNION_TYPE)
703 rli->offset = size_binop (MAX_EXPR, rli->offset, DECL_SIZE_UNIT (field));
704 else if (TREE_CODE (rli->t) == QUAL_UNION_TYPE)
705 rli->offset = fold (build (COND_EXPR, sizetype,
706 DECL_QUALIFIER (field),
707 DECL_SIZE_UNIT (field), rli->offset));
710 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
711 is a FIELD_DECL to be added after those fields already present in
712 T. (FIELD is not actually added to the TYPE_FIELDS list here;
713 callers that desire that behavior must manually perform that step.) */
716 place_field (rli, field)
717 record_layout_info rli;
720 /* The alignment required for FIELD. */
721 unsigned int desired_align;
722 /* The alignment FIELD would have if we just dropped it into the
723 record as it presently stands. */
724 unsigned int known_align;
725 unsigned int actual_align;
726 unsigned int user_align;
727 /* The type of this field. */
728 tree type = TREE_TYPE (field);
730 if (TREE_CODE (field) == ERROR_MARK || TREE_CODE (type) == ERROR_MARK)
733 /* If FIELD is static, then treat it like a separate variable, not
734 really like a structure field. If it is a FUNCTION_DECL, it's a
735 method. In both cases, all we do is lay out the decl, and we do
736 it *after* the record is laid out. */
737 if (TREE_CODE (field) == VAR_DECL)
739 rli->pending_statics = tree_cons (NULL_TREE, field,
740 rli->pending_statics);
744 /* Enumerators and enum types which are local to this class need not
745 be laid out. Likewise for initialized constant fields. */
746 else if (TREE_CODE (field) != FIELD_DECL)
749 /* Unions are laid out very differently than records, so split
750 that code off to another function. */
751 else if (TREE_CODE (rli->t) != RECORD_TYPE)
753 place_union_field (rli, field);
757 /* Work out the known alignment so far. Note that A & (-A) is the
758 value of the least-significant bit in A that is one. */
759 if (! integer_zerop (rli->bitpos))
760 known_align = (tree_low_cst (rli->bitpos, 1)
761 & - tree_low_cst (rli->bitpos, 1));
762 else if (integer_zerop (rli->offset))
763 known_align = BIGGEST_ALIGNMENT;
764 else if (host_integerp (rli->offset, 1))
765 known_align = (BITS_PER_UNIT
766 * (tree_low_cst (rli->offset, 1)
767 & - tree_low_cst (rli->offset, 1)));
769 known_align = rli->offset_align;
771 /* Lay out the field so we know what alignment it needs. For a
772 packed field, use the alignment as specified, disregarding what
773 the type would want. */
774 desired_align = DECL_ALIGN (field);
775 user_align = DECL_USER_ALIGN (field);
776 layout_decl (field, known_align);
777 if (! DECL_PACKED (field))
779 desired_align = DECL_ALIGN (field);
780 user_align = DECL_USER_ALIGN (field);
783 /* Some targets (i.e. i386, VMS) limit struct field alignment
784 to a lower boundary than alignment of variables unless
785 it was overridden by attribute aligned. */
786 #ifdef BIGGEST_FIELD_ALIGNMENT
789 = MIN (desired_align, (unsigned) BIGGEST_FIELD_ALIGNMENT);
792 #ifdef ADJUST_FIELD_ALIGN
794 desired_align = ADJUST_FIELD_ALIGN (field, desired_align);
797 /* Record must have at least as much alignment as any field.
798 Otherwise, the alignment of the field within the record is
800 if ((* targetm.ms_bitfield_layout_p) (rli->t)
801 && type != error_mark_node
802 && DECL_BIT_FIELD_TYPE (field)
803 && ! integer_zerop (TYPE_SIZE (type))
804 && integer_zerop (DECL_SIZE (field)))
807 && DECL_BIT_FIELD_TYPE (rli->prev_field)
808 && ! integer_zerop (DECL_SIZE (rli->prev_field)))
810 rli->record_align = MAX (rli->record_align, desired_align);
811 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
817 #ifdef PCC_BITFIELD_TYPE_MATTERS
818 if (PCC_BITFIELD_TYPE_MATTERS && type != error_mark_node
819 && ! (* targetm.ms_bitfield_layout_p) (rli->t)
820 && DECL_BIT_FIELD_TYPE (field)
821 && ! integer_zerop (TYPE_SIZE (type)))
823 /* For these machines, a zero-length field does not
824 affect the alignment of the structure as a whole.
825 It does, however, affect the alignment of the next field
826 within the structure. */
827 if (! integer_zerop (DECL_SIZE (field)))
828 rli->record_align = MAX (rli->record_align, desired_align);
829 else if (! DECL_PACKED (field))
830 desired_align = TYPE_ALIGN (type);
832 /* A named bit field of declared type `int'
833 forces the entire structure to have `int' alignment. */
834 if (DECL_NAME (field) != 0)
836 unsigned int type_align = TYPE_ALIGN (type);
838 #ifdef ADJUST_FIELD_ALIGN
839 if (! TYPE_USER_ALIGN (type))
840 type_align = ADJUST_FIELD_ALIGN (field, type_align);
843 if (maximum_field_alignment != 0)
844 type_align = MIN (type_align, maximum_field_alignment);
845 else if (DECL_PACKED (field))
846 type_align = MIN (type_align, BITS_PER_UNIT);
848 rli->record_align = MAX (rli->record_align, type_align);
849 rli->unpadded_align = MAX (rli->unpadded_align, DECL_ALIGN (field));
851 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
857 rli->record_align = MAX (rli->record_align, desired_align);
858 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
859 rli->unpadded_align = MAX (rli->unpadded_align, DECL_ALIGN (field));
862 if (warn_packed && DECL_PACKED (field))
864 if (known_align > TYPE_ALIGN (type))
866 if (TYPE_ALIGN (type) > desired_align)
868 if (STRICT_ALIGNMENT)
869 warning_with_decl (field, "packed attribute causes inefficient alignment for `%s'");
871 warning_with_decl (field, "packed attribute is unnecessary for `%s'");
875 rli->packed_maybe_necessary = 1;
878 /* Does this field automatically have alignment it needs by virtue
879 of the fields that precede it and the record's own alignment? */
880 if (known_align < desired_align)
882 /* No, we need to skip space before this field.
883 Bump the cumulative size to multiple of field alignment. */
886 warning_with_decl (field, "padding struct to align `%s'");
888 /* If the alignment is still within offset_align, just align
890 if (desired_align < rli->offset_align)
891 rli->bitpos = round_up (rli->bitpos, desired_align);
894 /* First adjust OFFSET by the partial bits, then align. */
896 = size_binop (PLUS_EXPR, rli->offset,
898 size_binop (CEIL_DIV_EXPR, rli->bitpos,
899 bitsize_unit_node)));
900 rli->bitpos = bitsize_zero_node;
902 rli->offset = round_up (rli->offset, desired_align / BITS_PER_UNIT);
905 if (! TREE_CONSTANT (rli->offset))
906 rli->offset_align = desired_align;
910 /* Handle compatibility with PCC. Note that if the record has any
911 variable-sized fields, we need not worry about compatibility. */
912 #ifdef PCC_BITFIELD_TYPE_MATTERS
913 if (PCC_BITFIELD_TYPE_MATTERS
914 && ! (* targetm.ms_bitfield_layout_p) (rli->t)
915 && TREE_CODE (field) == FIELD_DECL
916 && type != error_mark_node
917 && DECL_BIT_FIELD (field)
918 && ! DECL_PACKED (field)
919 && maximum_field_alignment == 0
920 && ! integer_zerop (DECL_SIZE (field))
921 && host_integerp (DECL_SIZE (field), 1)
922 && host_integerp (rli->offset, 1)
923 && host_integerp (TYPE_SIZE (type), 1))
925 unsigned int type_align = TYPE_ALIGN (type);
926 tree dsize = DECL_SIZE (field);
927 HOST_WIDE_INT field_size = tree_low_cst (dsize, 1);
928 HOST_WIDE_INT offset = tree_low_cst (rli->offset, 0);
929 HOST_WIDE_INT bit_offset = tree_low_cst (rli->bitpos, 0);
931 #ifdef ADJUST_FIELD_ALIGN
932 if (! TYPE_USER_ALIGN (type))
933 type_align = ADJUST_FIELD_ALIGN (field, type_align);
936 /* A bit field may not span more units of alignment of its type
937 than its type itself. Advance to next boundary if necessary. */
938 if ((((offset * BITS_PER_UNIT + bit_offset + field_size +
941 - (offset * BITS_PER_UNIT + bit_offset) / type_align)
942 > tree_low_cst (TYPE_SIZE (type), 1) / type_align)
943 rli->bitpos = round_up (rli->bitpos, type_align);
947 #ifdef BITFIELD_NBYTES_LIMITED
948 if (BITFIELD_NBYTES_LIMITED
949 && ! (* targetm.ms_bitfield_layout_p) (rli->t)
950 && TREE_CODE (field) == FIELD_DECL
951 && type != error_mark_node
952 && DECL_BIT_FIELD_TYPE (field)
953 && ! DECL_PACKED (field)
954 && ! integer_zerop (DECL_SIZE (field))
955 && host_integerp (DECL_SIZE (field), 1)
956 && host_integerp (rli->offset, 1)
957 && host_integerp (TYPE_SIZE (type), 1))
959 unsigned int type_align = TYPE_ALIGN (type);
960 tree dsize = DECL_SIZE (field);
961 HOST_WIDE_INT field_size = tree_low_cst (dsize, 1);
962 HOST_WIDE_INT offset = tree_low_cst (rli->offset, 0);
963 HOST_WIDE_INT bit_offset = tree_low_cst (rli->bitpos, 0);
965 #ifdef ADJUST_FIELD_ALIGN
966 if (! TYPE_USER_ALIGN (type))
967 type_align = ADJUST_FIELD_ALIGN (field, type_align);
970 if (maximum_field_alignment != 0)
971 type_align = MIN (type_align, maximum_field_alignment);
972 /* ??? This test is opposite the test in the containing if
973 statement, so this code is unreachable currently. */
974 else if (DECL_PACKED (field))
975 type_align = MIN (type_align, BITS_PER_UNIT);
977 /* A bit field may not span the unit of alignment of its type.
978 Advance to next boundary if necessary. */
979 /* ??? This code should match the code above for the
980 PCC_BITFIELD_TYPE_MATTERS case. */
981 if ((offset * BITS_PER_UNIT + bit_offset) / type_align
982 != ((offset * BITS_PER_UNIT + bit_offset + field_size - 1)
984 rli->bitpos = round_up (rli->bitpos, type_align);
988 /* See the docs for TARGET_MS_BITFIELD_LAYOUT_P for details. */
989 if ((* targetm.ms_bitfield_layout_p) (rli->t)
990 && TREE_CODE (field) == FIELD_DECL
991 && type != error_mark_node
992 && ! DECL_PACKED (field)
995 && host_integerp (DECL_SIZE (field), 1)
996 && DECL_SIZE (rli->prev_field)
997 && host_integerp (DECL_SIZE (rli->prev_field), 1)
998 && host_integerp (rli->offset, 1)
999 && host_integerp (TYPE_SIZE (type), 1)
1000 && host_integerp (TYPE_SIZE (TREE_TYPE (rli->prev_field)), 1)
1001 && ((DECL_BIT_FIELD_TYPE (rli->prev_field)
1002 && ! integer_zerop (DECL_SIZE (rli->prev_field)))
1003 || (DECL_BIT_FIELD_TYPE (field)
1004 && ! integer_zerop (DECL_SIZE (field))))
1005 && (! simple_cst_equal (TYPE_SIZE (type),
1006 TYPE_SIZE (TREE_TYPE (rli->prev_field)))
1007 /* If the previous field was a zero-sized bit-field, either
1008 it was ignored, in which case we must ensure the proper
1009 alignment of this field here, or it already forced the
1010 alignment of this field, in which case forcing the
1011 alignment again is harmless. So, do it in both cases. */
1012 || (DECL_BIT_FIELD_TYPE (rli->prev_field)
1013 && integer_zerop (DECL_SIZE (rli->prev_field)))))
1015 unsigned int type_align = TYPE_ALIGN (type);
1018 && DECL_BIT_FIELD_TYPE (rli->prev_field)
1019 /* If the previous bit-field is zero-sized, we've already
1020 accounted for its alignment needs (or ignored it, if
1021 appropriate) while placing it. */
1022 && ! integer_zerop (DECL_SIZE (rli->prev_field)))
1023 type_align = MAX (type_align,
1024 TYPE_ALIGN (TREE_TYPE (rli->prev_field)));
1026 if (maximum_field_alignment != 0)
1027 type_align = MIN (type_align, maximum_field_alignment);
1029 rli->bitpos = round_up (rli->bitpos, type_align);
1032 /* Offset so far becomes the position of this field after normalizing. */
1033 normalize_rli (rli);
1034 DECL_FIELD_OFFSET (field) = rli->offset;
1035 DECL_FIELD_BIT_OFFSET (field) = rli->bitpos;
1036 SET_DECL_OFFSET_ALIGN (field, rli->offset_align);
1038 TYPE_USER_ALIGN (rli->t) |= user_align;
1040 /* If this field ended up more aligned than we thought it would be (we
1041 approximate this by seeing if its position changed), lay out the field
1042 again; perhaps we can use an integral mode for it now. */
1043 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field)))
1044 actual_align = (tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1)
1045 & - tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1));
1046 else if (integer_zerop (DECL_FIELD_OFFSET (field)))
1047 actual_align = BIGGEST_ALIGNMENT;
1048 else if (host_integerp (DECL_FIELD_OFFSET (field), 1))
1049 actual_align = (BITS_PER_UNIT
1050 * (tree_low_cst (DECL_FIELD_OFFSET (field), 1)
1051 & - tree_low_cst (DECL_FIELD_OFFSET (field), 1)));
1053 actual_align = DECL_OFFSET_ALIGN (field);
1055 if (known_align != actual_align)
1056 layout_decl (field, actual_align);
1058 rli->prev_field = field;
1060 /* Now add size of this field to the size of the record. If the size is
1061 not constant, treat the field as being a multiple of bytes and just
1062 adjust the offset, resetting the bit position. Otherwise, apportion the
1063 size amongst the bit position and offset. First handle the case of an
1064 unspecified size, which can happen when we have an invalid nested struct
1065 definition, such as struct j { struct j { int i; } }. The error message
1066 is printed in finish_struct. */
1067 if (DECL_SIZE (field) == 0)
1069 else if (TREE_CODE (DECL_SIZE_UNIT (field)) != INTEGER_CST
1070 || TREE_CONSTANT_OVERFLOW (DECL_SIZE_UNIT (field)))
1073 = size_binop (PLUS_EXPR, rli->offset,
1075 size_binop (CEIL_DIV_EXPR, rli->bitpos,
1076 bitsize_unit_node)));
1078 = size_binop (PLUS_EXPR, rli->offset, DECL_SIZE_UNIT (field));
1079 rli->bitpos = bitsize_zero_node;
1080 rli->offset_align = MIN (rli->offset_align, DECL_ALIGN (field));
1084 rli->bitpos = size_binop (PLUS_EXPR, rli->bitpos, DECL_SIZE (field));
1085 normalize_rli (rli);
1089 /* Assuming that all the fields have been laid out, this function uses
1090 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
1091 inidicated by RLI. */
1094 finalize_record_size (rli)
1095 record_layout_info rli;
1097 tree unpadded_size, unpadded_size_unit;
1099 /* Now we want just byte and bit offsets, so set the offset alignment
1100 to be a byte and then normalize. */
1101 rli->offset_align = BITS_PER_UNIT;
1102 normalize_rli (rli);
1104 /* Determine the desired alignment. */
1105 #ifdef ROUND_TYPE_ALIGN
1106 TYPE_ALIGN (rli->t) = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t),
1109 TYPE_ALIGN (rli->t) = MAX (TYPE_ALIGN (rli->t), rli->record_align);
1112 /* Compute the size so far. Be sure to allow for extra bits in the
1113 size in bytes. We have guaranteed above that it will be no more
1114 than a single byte. */
1115 unpadded_size = rli_size_so_far (rli);
1116 unpadded_size_unit = rli_size_unit_so_far (rli);
1117 if (! integer_zerop (rli->bitpos))
1119 = size_binop (PLUS_EXPR, unpadded_size_unit, size_one_node);
1121 /* Record the un-rounded size in the binfo node. But first we check
1122 the size of TYPE_BINFO to make sure that BINFO_SIZE is available. */
1123 if (TYPE_BINFO (rli->t) && TREE_VEC_LENGTH (TYPE_BINFO (rli->t)) > 6)
1125 TYPE_BINFO_SIZE (rli->t) = unpadded_size;
1126 TYPE_BINFO_SIZE_UNIT (rli->t) = unpadded_size_unit;
1129 /* Round the size up to be a multiple of the required alignment */
1130 #ifdef ROUND_TYPE_SIZE
1131 TYPE_SIZE (rli->t) = ROUND_TYPE_SIZE (rli->t, unpadded_size,
1132 TYPE_ALIGN (rli->t));
1133 TYPE_SIZE_UNIT (rli->t)
1134 = ROUND_TYPE_SIZE_UNIT (rli->t, unpadded_size_unit,
1135 TYPE_ALIGN (rli->t) / BITS_PER_UNIT);
1137 TYPE_SIZE (rli->t) = round_up (unpadded_size, TYPE_ALIGN (rli->t));
1138 TYPE_SIZE_UNIT (rli->t) = round_up (unpadded_size_unit,
1139 TYPE_ALIGN (rli->t) / BITS_PER_UNIT);
1142 if (warn_padded && TREE_CONSTANT (unpadded_size)
1143 && simple_cst_equal (unpadded_size, TYPE_SIZE (rli->t)) == 0)
1144 warning ("padding struct size to alignment boundary");
1146 if (warn_packed && TREE_CODE (rli->t) == RECORD_TYPE
1147 && TYPE_PACKED (rli->t) && ! rli->packed_maybe_necessary
1148 && TREE_CONSTANT (unpadded_size))
1152 #ifdef ROUND_TYPE_ALIGN
1154 = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t), rli->unpacked_align);
1156 rli->unpacked_align = MAX (TYPE_ALIGN (rli->t), rli->unpacked_align);
1159 #ifdef ROUND_TYPE_SIZE
1160 unpacked_size = ROUND_TYPE_SIZE (rli->t, TYPE_SIZE (rli->t),
1161 rli->unpacked_align);
1163 unpacked_size = round_up (TYPE_SIZE (rli->t), rli->unpacked_align);
1166 if (simple_cst_equal (unpacked_size, TYPE_SIZE (rli->t)))
1168 TYPE_PACKED (rli->t) = 0;
1170 if (TYPE_NAME (rli->t))
1174 if (TREE_CODE (TYPE_NAME (rli->t)) == IDENTIFIER_NODE)
1175 name = IDENTIFIER_POINTER (TYPE_NAME (rli->t));
1177 name = IDENTIFIER_POINTER (DECL_NAME (TYPE_NAME (rli->t)));
1179 if (STRICT_ALIGNMENT)
1180 warning ("packed attribute causes inefficient alignment for `%s'", name);
1182 warning ("packed attribute is unnecessary for `%s'", name);
1186 if (STRICT_ALIGNMENT)
1187 warning ("packed attribute causes inefficient alignment");
1189 warning ("packed attribute is unnecessary");
1195 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
1198 compute_record_mode (type)
1202 enum machine_mode mode = VOIDmode;
1204 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
1205 However, if possible, we use a mode that fits in a register
1206 instead, in order to allow for better optimization down the
1208 TYPE_MODE (type) = BLKmode;
1210 if (! host_integerp (TYPE_SIZE (type), 1))
1213 /* A record which has any BLKmode members must itself be
1214 BLKmode; it can't go in a register. Unless the member is
1215 BLKmode only because it isn't aligned. */
1216 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1218 unsigned HOST_WIDE_INT bitpos;
1220 if (TREE_CODE (field) != FIELD_DECL)
1223 if (TREE_CODE (TREE_TYPE (field)) == ERROR_MARK
1224 || (TYPE_MODE (TREE_TYPE (field)) == BLKmode
1225 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field)))
1226 || ! host_integerp (bit_position (field), 1)
1227 || DECL_SIZE (field) == 0
1228 || ! host_integerp (DECL_SIZE (field), 1))
1231 bitpos = int_bit_position (field);
1233 /* Must be BLKmode if any field crosses a word boundary,
1234 since extract_bit_field can't handle that in registers. */
1235 if (bitpos / BITS_PER_WORD
1236 != ((tree_low_cst (DECL_SIZE (field), 1) + bitpos - 1)
1238 /* But there is no problem if the field is entire words. */
1239 && tree_low_cst (DECL_SIZE (field), 1) % BITS_PER_WORD != 0)
1242 /* If this field is the whole struct, remember its mode so
1243 that, say, we can put a double in a class into a DF
1244 register instead of forcing it to live in the stack. */
1245 if (simple_cst_equal (TYPE_SIZE (type), DECL_SIZE (field)))
1246 mode = DECL_MODE (field);
1248 #ifdef MEMBER_TYPE_FORCES_BLK
1249 /* With some targets, eg. c4x, it is sub-optimal
1250 to access an aligned BLKmode structure as a scalar. */
1252 if (MEMBER_TYPE_FORCES_BLK (field, mode))
1254 #endif /* MEMBER_TYPE_FORCES_BLK */
1257 /* If we only have one real field; use its mode. This only applies to
1258 RECORD_TYPE. This does not apply to unions. */
1259 if (TREE_CODE (type) == RECORD_TYPE && mode != VOIDmode)
1260 TYPE_MODE (type) = mode;
1262 TYPE_MODE (type) = mode_for_size_tree (TYPE_SIZE (type), MODE_INT, 1);
1264 /* If structure's known alignment is less than what the scalar
1265 mode would need, and it matters, then stick with BLKmode. */
1266 if (TYPE_MODE (type) != BLKmode
1268 && ! (TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT
1269 || TYPE_ALIGN (type) >= GET_MODE_ALIGNMENT (TYPE_MODE (type))))
1271 /* If this is the only reason this type is BLKmode, then
1272 don't force containing types to be BLKmode. */
1273 TYPE_NO_FORCE_BLK (type) = 1;
1274 TYPE_MODE (type) = BLKmode;
1278 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1282 finalize_type_size (type)
1285 /* Normally, use the alignment corresponding to the mode chosen.
1286 However, where strict alignment is not required, avoid
1287 over-aligning structures, since most compilers do not do this
1290 if (TYPE_MODE (type) != BLKmode && TYPE_MODE (type) != VOIDmode
1291 && (STRICT_ALIGNMENT
1292 || (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE
1293 && TREE_CODE (type) != QUAL_UNION_TYPE
1294 && TREE_CODE (type) != ARRAY_TYPE)))
1296 TYPE_ALIGN (type) = GET_MODE_ALIGNMENT (TYPE_MODE (type));
1297 TYPE_USER_ALIGN (type) = 0;
1300 /* Do machine-dependent extra alignment. */
1301 #ifdef ROUND_TYPE_ALIGN
1303 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (type), BITS_PER_UNIT);
1306 /* If we failed to find a simple way to calculate the unit size
1307 of the type, find it by division. */
1308 if (TYPE_SIZE_UNIT (type) == 0 && TYPE_SIZE (type) != 0)
1309 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1310 result will fit in sizetype. We will get more efficient code using
1311 sizetype, so we force a conversion. */
1312 TYPE_SIZE_UNIT (type)
1313 = convert (sizetype,
1314 size_binop (FLOOR_DIV_EXPR, TYPE_SIZE (type),
1315 bitsize_unit_node));
1317 if (TYPE_SIZE (type) != 0)
1319 #ifdef ROUND_TYPE_SIZE
1321 = ROUND_TYPE_SIZE (type, TYPE_SIZE (type), TYPE_ALIGN (type));
1322 TYPE_SIZE_UNIT (type)
1323 = ROUND_TYPE_SIZE_UNIT (type, TYPE_SIZE_UNIT (type),
1324 TYPE_ALIGN (type) / BITS_PER_UNIT);
1326 TYPE_SIZE (type) = round_up (TYPE_SIZE (type), TYPE_ALIGN (type));
1327 TYPE_SIZE_UNIT (type)
1328 = round_up (TYPE_SIZE_UNIT (type), TYPE_ALIGN (type) / BITS_PER_UNIT);
1332 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1333 if (TYPE_SIZE (type) != 0 && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
1334 TYPE_SIZE (type) = variable_size (TYPE_SIZE (type));
1335 if (TYPE_SIZE_UNIT (type) != 0
1336 && TREE_CODE (TYPE_SIZE_UNIT (type)) != INTEGER_CST)
1337 TYPE_SIZE_UNIT (type) = variable_size (TYPE_SIZE_UNIT (type));
1339 /* Also layout any other variants of the type. */
1340 if (TYPE_NEXT_VARIANT (type)
1341 || type != TYPE_MAIN_VARIANT (type))
1344 /* Record layout info of this variant. */
1345 tree size = TYPE_SIZE (type);
1346 tree size_unit = TYPE_SIZE_UNIT (type);
1347 unsigned int align = TYPE_ALIGN (type);
1348 unsigned int user_align = TYPE_USER_ALIGN (type);
1349 enum machine_mode mode = TYPE_MODE (type);
1351 /* Copy it into all variants. */
1352 for (variant = TYPE_MAIN_VARIANT (type);
1354 variant = TYPE_NEXT_VARIANT (variant))
1356 TYPE_SIZE (variant) = size;
1357 TYPE_SIZE_UNIT (variant) = size_unit;
1358 TYPE_ALIGN (variant) = align;
1359 TYPE_USER_ALIGN (variant) = user_align;
1360 TYPE_MODE (variant) = mode;
1365 /* Do all of the work required to layout the type indicated by RLI,
1366 once the fields have been laid out. This function will call `free'
1370 finish_record_layout (rli)
1371 record_layout_info rli;
1373 /* Compute the final size. */
1374 finalize_record_size (rli);
1376 /* Compute the TYPE_MODE for the record. */
1377 compute_record_mode (rli->t);
1379 /* Perform any last tweaks to the TYPE_SIZE, etc. */
1380 finalize_type_size (rli->t);
1382 /* Lay out any static members. This is done now because their type
1383 may use the record's type. */
1384 while (rli->pending_statics)
1386 layout_decl (TREE_VALUE (rli->pending_statics), 0);
1387 rli->pending_statics = TREE_CHAIN (rli->pending_statics);
1394 /* Calculate the mode, size, and alignment for TYPE.
1395 For an array type, calculate the element separation as well.
1396 Record TYPE on the chain of permanent or temporary types
1397 so that dbxout will find out about it.
1399 TYPE_SIZE of a type is nonzero if the type has been laid out already.
1400 layout_type does nothing on such a type.
1402 If the type is incomplete, its TYPE_SIZE remains zero. */
1411 /* Do nothing if type has been laid out before. */
1412 if (TYPE_SIZE (type))
1415 switch (TREE_CODE (type))
1418 /* This kind of type is the responsibility
1419 of the language-specific code. */
1422 case BOOLEAN_TYPE: /* Used for Java, Pascal, and Chill. */
1423 if (TYPE_PRECISION (type) == 0)
1424 TYPE_PRECISION (type) = 1; /* default to one byte/boolean. */
1426 /* ... fall through ... */
1431 if (TREE_CODE (TYPE_MIN_VALUE (type)) == INTEGER_CST
1432 && tree_int_cst_sgn (TYPE_MIN_VALUE (type)) >= 0)
1433 TREE_UNSIGNED (type) = 1;
1435 TYPE_MODE (type) = smallest_mode_for_size (TYPE_PRECISION (type),
1437 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1438 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1442 TYPE_MODE (type) = mode_for_size (TYPE_PRECISION (type), MODE_FLOAT, 0);
1443 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1444 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1448 TREE_UNSIGNED (type) = TREE_UNSIGNED (TREE_TYPE (type));
1450 = mode_for_size (2 * TYPE_PRECISION (TREE_TYPE (type)),
1451 (TREE_CODE (TREE_TYPE (type)) == INTEGER_TYPE
1452 ? MODE_COMPLEX_INT : MODE_COMPLEX_FLOAT),
1454 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1455 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1462 subtype = TREE_TYPE (type);
1463 TREE_UNSIGNED (type) = TREE_UNSIGNED (subtype);
1464 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1465 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1470 /* This is an incomplete type and so doesn't have a size. */
1471 TYPE_ALIGN (type) = 1;
1472 TYPE_USER_ALIGN (type) = 0;
1473 TYPE_MODE (type) = VOIDmode;
1477 TYPE_SIZE (type) = bitsize_int (POINTER_SIZE);
1478 TYPE_SIZE_UNIT (type) = size_int (POINTER_SIZE / BITS_PER_UNIT);
1479 /* A pointer might be MODE_PARTIAL_INT,
1480 but ptrdiff_t must be integral. */
1481 TYPE_MODE (type) = mode_for_size (POINTER_SIZE, MODE_INT, 0);
1486 TYPE_MODE (type) = mode_for_size (2 * POINTER_SIZE, MODE_INT, 0);
1487 TYPE_SIZE (type) = bitsize_int (2 * POINTER_SIZE);
1488 TYPE_SIZE_UNIT (type) = size_int ((2 * POINTER_SIZE) / BITS_PER_UNIT);
1492 case REFERENCE_TYPE:
1494 int nbits = ((TREE_CODE (type) == REFERENCE_TYPE
1495 && reference_types_internal)
1496 ? GET_MODE_BITSIZE (Pmode) : POINTER_SIZE);
1498 TYPE_MODE (type) = nbits == POINTER_SIZE ? ptr_mode : Pmode;
1499 TYPE_SIZE (type) = bitsize_int (nbits);
1500 TYPE_SIZE_UNIT (type) = size_int (nbits / BITS_PER_UNIT);
1501 TREE_UNSIGNED (type) = 1;
1502 TYPE_PRECISION (type) = nbits;
1508 tree index = TYPE_DOMAIN (type);
1509 tree element = TREE_TYPE (type);
1511 build_pointer_type (element);
1513 /* We need to know both bounds in order to compute the size. */
1514 if (index && TYPE_MAX_VALUE (index) && TYPE_MIN_VALUE (index)
1515 && TYPE_SIZE (element))
1517 tree ub = TYPE_MAX_VALUE (index);
1518 tree lb = TYPE_MIN_VALUE (index);
1522 /* The initial subtraction should happen in the original type so
1523 that (possible) negative values are handled appropriately. */
1524 length = size_binop (PLUS_EXPR, size_one_node,
1526 fold (build (MINUS_EXPR,
1530 /* Special handling for arrays of bits (for Chill). */
1531 element_size = TYPE_SIZE (element);
1532 if (TYPE_PACKED (type) && INTEGRAL_TYPE_P (element)
1533 && (integer_zerop (TYPE_MAX_VALUE (element))
1534 || integer_onep (TYPE_MAX_VALUE (element)))
1535 && host_integerp (TYPE_MIN_VALUE (element), 1))
1537 HOST_WIDE_INT maxvalue
1538 = tree_low_cst (TYPE_MAX_VALUE (element), 1);
1539 HOST_WIDE_INT minvalue
1540 = tree_low_cst (TYPE_MIN_VALUE (element), 1);
1542 if (maxvalue - minvalue == 1
1543 && (maxvalue == 1 || maxvalue == 0))
1544 element_size = integer_one_node;
1547 TYPE_SIZE (type) = size_binop (MULT_EXPR, element_size,
1548 convert (bitsizetype, length));
1550 /* If we know the size of the element, calculate the total
1551 size directly, rather than do some division thing below.
1552 This optimization helps Fortran assumed-size arrays
1553 (where the size of the array is determined at runtime)
1555 Note that we can't do this in the case where the size of
1556 the elements is one bit since TYPE_SIZE_UNIT cannot be
1557 set correctly in that case. */
1558 if (TYPE_SIZE_UNIT (element) != 0 && ! integer_onep (element_size))
1559 TYPE_SIZE_UNIT (type)
1560 = size_binop (MULT_EXPR, TYPE_SIZE_UNIT (element), length);
1563 /* Now round the alignment and size,
1564 using machine-dependent criteria if any. */
1566 #ifdef ROUND_TYPE_ALIGN
1568 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (element), BITS_PER_UNIT);
1570 TYPE_ALIGN (type) = MAX (TYPE_ALIGN (element), BITS_PER_UNIT);
1572 TYPE_USER_ALIGN (type) = TYPE_USER_ALIGN (element);
1574 #ifdef ROUND_TYPE_SIZE
1575 if (TYPE_SIZE (type) != 0)
1578 = ROUND_TYPE_SIZE (type, TYPE_SIZE (type), TYPE_ALIGN (type));
1580 /* If the rounding changed the size of the type, remove any
1581 pre-calculated TYPE_SIZE_UNIT. */
1582 if (simple_cst_equal (TYPE_SIZE (type), tmp) != 1)
1583 TYPE_SIZE_UNIT (type) = NULL;
1585 TYPE_SIZE (type) = tmp;
1589 TYPE_MODE (type) = BLKmode;
1590 if (TYPE_SIZE (type) != 0
1591 #ifdef MEMBER_TYPE_FORCES_BLK
1592 && ! MEMBER_TYPE_FORCES_BLK (type, VOIDmode)
1594 /* BLKmode elements force BLKmode aggregate;
1595 else extract/store fields may lose. */
1596 && (TYPE_MODE (TREE_TYPE (type)) != BLKmode
1597 || TYPE_NO_FORCE_BLK (TREE_TYPE (type))))
1599 /* One-element arrays get the component type's mode. */
1600 if (simple_cst_equal (TYPE_SIZE (type),
1601 TYPE_SIZE (TREE_TYPE (type))))
1602 TYPE_MODE (type) = TYPE_MODE (TREE_TYPE (type));
1605 = mode_for_size_tree (TYPE_SIZE (type), MODE_INT, 1);
1607 if (TYPE_MODE (type) != BLKmode
1608 && STRICT_ALIGNMENT && TYPE_ALIGN (type) < BIGGEST_ALIGNMENT
1609 && TYPE_ALIGN (type) < GET_MODE_ALIGNMENT (TYPE_MODE (type))
1610 && TYPE_MODE (type) != BLKmode)
1612 TYPE_NO_FORCE_BLK (type) = 1;
1613 TYPE_MODE (type) = BLKmode;
1621 case QUAL_UNION_TYPE:
1624 record_layout_info rli;
1626 /* Initialize the layout information. */
1627 rli = start_record_layout (type);
1629 /* If this is a QUAL_UNION_TYPE, we want to process the fields
1630 in the reverse order in building the COND_EXPR that denotes
1631 its size. We reverse them again later. */
1632 if (TREE_CODE (type) == QUAL_UNION_TYPE)
1633 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
1635 /* Place all the fields. */
1636 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1637 place_field (rli, field);
1639 if (TREE_CODE (type) == QUAL_UNION_TYPE)
1640 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
1642 if (lang_adjust_rli)
1643 (*lang_adjust_rli) (rli);
1645 /* Finish laying out the record. */
1646 finish_record_layout (rli);
1650 case SET_TYPE: /* Used by Chill and Pascal. */
1651 if (TREE_CODE (TYPE_MAX_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST
1652 || TREE_CODE (TYPE_MIN_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST)
1656 #ifndef SET_WORD_SIZE
1657 #define SET_WORD_SIZE BITS_PER_WORD
1659 unsigned int alignment
1660 = set_alignment ? set_alignment : SET_WORD_SIZE;
1662 = (TREE_INT_CST_LOW (TYPE_MAX_VALUE (TYPE_DOMAIN (type)))
1663 - TREE_INT_CST_LOW (TYPE_MIN_VALUE (TYPE_DOMAIN (type))) + 1);
1665 = ((size_in_bits + alignment - 1) / alignment) * alignment;
1667 if (rounded_size > (int) alignment)
1668 TYPE_MODE (type) = BLKmode;
1670 TYPE_MODE (type) = mode_for_size (alignment, MODE_INT, 1);
1672 TYPE_SIZE (type) = bitsize_int (rounded_size);
1673 TYPE_SIZE_UNIT (type) = size_int (rounded_size / BITS_PER_UNIT);
1674 TYPE_ALIGN (type) = alignment;
1675 TYPE_USER_ALIGN (type) = 0;
1676 TYPE_PRECISION (type) = size_in_bits;
1681 /* The size may vary in different languages, so the language front end
1682 should fill in the size. */
1683 TYPE_ALIGN (type) = BIGGEST_ALIGNMENT;
1684 TYPE_USER_ALIGN (type) = 0;
1685 TYPE_MODE (type) = BLKmode;
1692 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
1693 records and unions, finish_record_layout already called this
1695 if (TREE_CODE (type) != RECORD_TYPE
1696 && TREE_CODE (type) != UNION_TYPE
1697 && TREE_CODE (type) != QUAL_UNION_TYPE)
1698 finalize_type_size (type);
1700 /* If this type is created before sizetype has been permanently set,
1701 record it so set_sizetype can fix it up. */
1703 early_type_list = tree_cons (NULL_TREE, type, early_type_list);
1705 /* If an alias set has been set for this aggregate when it was incomplete,
1706 force it into alias set 0.
1707 This is too conservative, but we cannot call record_component_aliases
1708 here because some frontends still change the aggregates after
1710 if (AGGREGATE_TYPE_P (type) && TYPE_ALIAS_SET_KNOWN_P (type))
1711 TYPE_ALIAS_SET (type) = 0;
1714 /* Create and return a type for signed integers of PRECISION bits. */
1717 make_signed_type (precision)
1720 tree type = make_node (INTEGER_TYPE);
1722 TYPE_PRECISION (type) = precision;
1724 fixup_signed_type (type);
1728 /* Create and return a type for unsigned integers of PRECISION bits. */
1731 make_unsigned_type (precision)
1734 tree type = make_node (INTEGER_TYPE);
1736 TYPE_PRECISION (type) = precision;
1738 fixup_unsigned_type (type);
1742 /* Initialize sizetype and bitsizetype to a reasonable and temporary
1743 value to enable integer types to be created. */
1746 initialize_sizetypes ()
1748 tree t = make_node (INTEGER_TYPE);
1750 /* Set this so we do something reasonable for the build_int_2 calls
1752 integer_type_node = t;
1754 TYPE_MODE (t) = SImode;
1755 TYPE_ALIGN (t) = GET_MODE_ALIGNMENT (SImode);
1756 TYPE_USER_ALIGN (t) = 0;
1757 TYPE_SIZE (t) = build_int_2 (GET_MODE_BITSIZE (SImode), 0);
1758 TYPE_SIZE_UNIT (t) = build_int_2 (GET_MODE_SIZE (SImode), 0);
1759 TREE_UNSIGNED (t) = 1;
1760 TYPE_PRECISION (t) = GET_MODE_BITSIZE (SImode);
1761 TYPE_MIN_VALUE (t) = build_int_2 (0, 0);
1762 TYPE_IS_SIZETYPE (t) = 1;
1764 /* 1000 avoids problems with possible overflow and is certainly
1765 larger than any size value we'd want to be storing. */
1766 TYPE_MAX_VALUE (t) = build_int_2 (1000, 0);
1768 /* These two must be different nodes because of the caching done in
1771 bitsizetype = copy_node (t);
1772 integer_type_node = 0;
1775 /* Set sizetype to TYPE, and initialize *sizetype accordingly.
1776 Also update the type of any standard type's sizes made so far. */
1782 int oprecision = TYPE_PRECISION (type);
1783 /* The *bitsizetype types use a precision that avoids overflows when
1784 calculating signed sizes / offsets in bits. However, when
1785 cross-compiling from a 32 bit to a 64 bit host, we are limited to 64 bit
1787 int precision = MIN (oprecision + BITS_PER_UNIT_LOG + 1,
1788 2 * HOST_BITS_PER_WIDE_INT);
1795 /* Make copies of nodes since we'll be setting TYPE_IS_SIZETYPE. */
1796 sizetype = copy_node (type);
1797 TYPE_DOMAIN (sizetype) = type;
1798 TYPE_IS_SIZETYPE (sizetype) = 1;
1799 bitsizetype = make_node (INTEGER_TYPE);
1800 TYPE_NAME (bitsizetype) = TYPE_NAME (type);
1801 TYPE_PRECISION (bitsizetype) = precision;
1802 TYPE_IS_SIZETYPE (bitsizetype) = 1;
1804 if (TREE_UNSIGNED (type))
1805 fixup_unsigned_type (bitsizetype);
1807 fixup_signed_type (bitsizetype);
1809 layout_type (bitsizetype);
1811 if (TREE_UNSIGNED (type))
1813 usizetype = sizetype;
1814 ubitsizetype = bitsizetype;
1815 ssizetype = copy_node (make_signed_type (oprecision));
1816 sbitsizetype = copy_node (make_signed_type (precision));
1820 ssizetype = sizetype;
1821 sbitsizetype = bitsizetype;
1822 usizetype = copy_node (make_unsigned_type (oprecision));
1823 ubitsizetype = copy_node (make_unsigned_type (precision));
1826 TYPE_NAME (bitsizetype) = get_identifier ("bit_size_type");
1828 /* Show is a sizetype, is a main type, and has no pointers to it. */
1829 for (i = 0; i < ARRAY_SIZE (sizetype_tab); i++)
1831 TYPE_IS_SIZETYPE (sizetype_tab[i]) = 1;
1832 TYPE_MAIN_VARIANT (sizetype_tab[i]) = sizetype_tab[i];
1833 TYPE_NEXT_VARIANT (sizetype_tab[i]) = 0;
1834 TYPE_POINTER_TO (sizetype_tab[i]) = 0;
1835 TYPE_REFERENCE_TO (sizetype_tab[i]) = 0;
1838 /* Go down each of the types we already made and set the proper type
1839 for the sizes in them. */
1840 for (t = early_type_list; t != 0; t = TREE_CHAIN (t))
1842 if (TREE_CODE (TREE_VALUE (t)) != INTEGER_TYPE)
1845 TREE_TYPE (TYPE_SIZE (TREE_VALUE (t))) = bitsizetype;
1846 TREE_TYPE (TYPE_SIZE_UNIT (TREE_VALUE (t))) = sizetype;
1849 early_type_list = 0;
1853 /* Set the extreme values of TYPE based on its precision in bits,
1854 then lay it out. Used when make_signed_type won't do
1855 because the tree code is not INTEGER_TYPE.
1856 E.g. for Pascal, when the -fsigned-char option is given. */
1859 fixup_signed_type (type)
1862 int precision = TYPE_PRECISION (type);
1864 /* We can not represent properly constants greater then
1865 2 * HOST_BITS_PER_WIDE_INT, still we need the types
1866 as they are used by i386 vector extensions and friends. */
1867 if (precision > HOST_BITS_PER_WIDE_INT * 2)
1868 precision = HOST_BITS_PER_WIDE_INT * 2;
1870 TYPE_MIN_VALUE (type)
1871 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1872 ? 0 : (HOST_WIDE_INT) (-1) << (precision - 1)),
1873 (((HOST_WIDE_INT) (-1)
1874 << (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1875 ? precision - HOST_BITS_PER_WIDE_INT - 1
1877 TYPE_MAX_VALUE (type)
1878 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1879 ? -1 : ((HOST_WIDE_INT) 1 << (precision - 1)) - 1),
1880 (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1881 ? (((HOST_WIDE_INT) 1
1882 << (precision - HOST_BITS_PER_WIDE_INT - 1))) - 1
1885 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
1886 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
1888 /* Lay out the type: set its alignment, size, etc. */
1892 /* Set the extreme values of TYPE based on its precision in bits,
1893 then lay it out. This is used both in `make_unsigned_type'
1894 and for enumeral types. */
1897 fixup_unsigned_type (type)
1900 int precision = TYPE_PRECISION (type);
1902 /* We can not represent properly constants greater then
1903 2 * HOST_BITS_PER_WIDE_INT, still we need the types
1904 as they are used by i386 vector extensions and friends. */
1905 if (precision > HOST_BITS_PER_WIDE_INT * 2)
1906 precision = HOST_BITS_PER_WIDE_INT * 2;
1908 TYPE_MIN_VALUE (type) = build_int_2 (0, 0);
1909 TYPE_MAX_VALUE (type)
1910 = build_int_2 (precision - HOST_BITS_PER_WIDE_INT >= 0
1911 ? -1 : ((HOST_WIDE_INT) 1 << precision) - 1,
1912 precision - HOST_BITS_PER_WIDE_INT > 0
1913 ? ((unsigned HOST_WIDE_INT) ~0
1914 >> (HOST_BITS_PER_WIDE_INT
1915 - (precision - HOST_BITS_PER_WIDE_INT)))
1917 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
1918 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
1920 /* Lay out the type: set its alignment, size, etc. */
1924 /* Find the best machine mode to use when referencing a bit field of length
1925 BITSIZE bits starting at BITPOS.
1927 The underlying object is known to be aligned to a boundary of ALIGN bits.
1928 If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
1929 larger than LARGEST_MODE (usually SImode).
1931 If no mode meets all these conditions, we return VOIDmode. Otherwise, if
1932 VOLATILEP is true or SLOW_BYTE_ACCESS is false, we return the smallest
1933 mode meeting these conditions.
1935 Otherwise (VOLATILEP is false and SLOW_BYTE_ACCESS is true), we return
1936 the largest mode (but a mode no wider than UNITS_PER_WORD) that meets
1937 all the conditions. */
1940 get_best_mode (bitsize, bitpos, align, largest_mode, volatilep)
1941 int bitsize, bitpos;
1943 enum machine_mode largest_mode;
1946 enum machine_mode mode;
1947 unsigned int unit = 0;
1949 /* Find the narrowest integer mode that contains the bit field. */
1950 for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
1951 mode = GET_MODE_WIDER_MODE (mode))
1953 unit = GET_MODE_BITSIZE (mode);
1954 if ((bitpos % unit) + bitsize <= unit)
1958 if (mode == VOIDmode
1959 /* It is tempting to omit the following line
1960 if STRICT_ALIGNMENT is true.
1961 But that is incorrect, since if the bitfield uses part of 3 bytes
1962 and we use a 4-byte mode, we could get a spurious segv
1963 if the extra 4th byte is past the end of memory.
1964 (Though at least one Unix compiler ignores this problem:
1965 that on the Sequent 386 machine. */
1966 || MIN (unit, BIGGEST_ALIGNMENT) > align
1967 || (largest_mode != VOIDmode && unit > GET_MODE_BITSIZE (largest_mode)))
1970 if (SLOW_BYTE_ACCESS && ! volatilep)
1972 enum machine_mode wide_mode = VOIDmode, tmode;
1974 for (tmode = GET_CLASS_NARROWEST_MODE (MODE_INT); tmode != VOIDmode;
1975 tmode = GET_MODE_WIDER_MODE (tmode))
1977 unit = GET_MODE_BITSIZE (tmode);
1978 if (bitpos / unit == (bitpos + bitsize - 1) / unit
1979 && unit <= BITS_PER_WORD
1980 && unit <= MIN (align, BIGGEST_ALIGNMENT)
1981 && (largest_mode == VOIDmode
1982 || unit <= GET_MODE_BITSIZE (largest_mode)))
1986 if (wide_mode != VOIDmode)
1993 #include "gt-stor-layout.h"