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, 2003 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
25 #include "coretypes.h"
36 #include "langhooks.h"
38 /* Set to one when set_sizetype has been called. */
39 static int sizetype_set;
41 /* List of types created before set_sizetype has been called. We do not
42 make this a GGC root since we want these nodes to be reclaimed. */
43 static tree early_type_list;
45 /* Data type for the expressions representing sizes of data types.
46 It is the first integer type laid out. */
47 tree sizetype_tab[(int) TYPE_KIND_LAST];
49 /* If nonzero, this is an upper limit on alignment of structure fields.
50 The value is measured in bits. */
51 unsigned int maximum_field_alignment;
53 /* If nonzero, the alignment of a bitstring or (power-)set value, in bits.
54 May be overridden by front-ends. */
55 unsigned int set_alignment = 0;
57 /* Nonzero if all REFERENCE_TYPEs are internal and hence should be
58 allocated in Pmode, not ptr_mode. Set only by internal_reference_types
59 called only by a front end. */
60 static int reference_types_internal = 0;
62 static void finalize_record_size PARAMS ((record_layout_info));
63 static void finalize_type_size PARAMS ((tree));
64 static void place_union_field PARAMS ((record_layout_info, tree));
65 #if defined (PCC_BITFIELD_TYPE_MATTERS) || defined (BITFIELD_NBYTES_LIMITED)
66 static int excess_unit_span PARAMS ((HOST_WIDE_INT, HOST_WIDE_INT,
67 HOST_WIDE_INT, HOST_WIDE_INT,
70 static unsigned int update_alignment_for_field
71 PARAMS ((record_layout_info, tree,
73 extern void debug_rli PARAMS ((record_layout_info));
75 /* SAVE_EXPRs for sizes of types and decls, waiting to be expanded. */
77 static GTY(()) tree pending_sizes;
79 /* Nonzero means cannot safely call expand_expr now,
80 so put variable sizes onto `pending_sizes' instead. */
82 int immediate_size_expand;
84 /* Show that REFERENCE_TYPES are internal and should be Pmode. Called only
88 internal_reference_types ()
90 reference_types_internal = 1;
93 /* Get a list of all the objects put on the pending sizes list. */
98 tree chain = pending_sizes;
101 /* Put each SAVE_EXPR into the current function. */
102 for (t = chain; t; t = TREE_CHAIN (t))
103 SAVE_EXPR_CONTEXT (TREE_VALUE (t)) = current_function_decl;
109 /* Return nonzero if EXPR is present on the pending sizes list. */
112 is_pending_size (expr)
117 for (t = pending_sizes; t; t = TREE_CHAIN (t))
118 if (TREE_VALUE (t) == expr)
123 /* Add EXPR to the pending sizes list. */
126 put_pending_size (expr)
129 /* Strip any simple arithmetic from EXPR to see if it has an underlying
131 while (TREE_CODE_CLASS (TREE_CODE (expr)) == '1'
132 || (TREE_CODE_CLASS (TREE_CODE (expr)) == '2'
133 && TREE_CONSTANT (TREE_OPERAND (expr, 1))))
134 expr = TREE_OPERAND (expr, 0);
136 if (TREE_CODE (expr) == SAVE_EXPR)
137 pending_sizes = tree_cons (NULL_TREE, expr, pending_sizes);
140 /* Put a chain of objects into the pending sizes list, which must be
144 put_pending_sizes (chain)
150 pending_sizes = chain;
153 /* Given a size SIZE that may not be a constant, return a SAVE_EXPR
154 to serve as the actual size-expression for a type or decl. */
160 /* If the language-processor is to take responsibility for variable-sized
161 items (e.g., languages which have elaboration procedures like Ada),
162 just return SIZE unchanged. Likewise for self-referential sizes and
164 if (TREE_CONSTANT (size)
165 || (*lang_hooks.decls.global_bindings_p) () < 0
166 || contains_placeholder_p (size))
169 size = save_expr (size);
171 /* If an array with a variable number of elements is declared, and
172 the elements require destruction, we will emit a cleanup for the
173 array. That cleanup is run both on normal exit from the block
174 and in the exception-handler for the block. Normally, when code
175 is used in both ordinary code and in an exception handler it is
176 `unsaved', i.e., all SAVE_EXPRs are recalculated. However, we do
177 not wish to do that here; the array-size is the same in both
179 if (TREE_CODE (size) == SAVE_EXPR)
180 SAVE_EXPR_PERSISTENT_P (size) = 1;
182 if ((*lang_hooks.decls.global_bindings_p) ())
184 if (TREE_CONSTANT (size))
185 error ("type size can't be explicitly evaluated");
187 error ("variable-size type declared outside of any function");
189 return size_one_node;
192 if (immediate_size_expand)
193 /* NULL_RTX is not defined; neither is the rtx type.
194 Also, we would like to pass const0_rtx here, but don't have it. */
195 expand_expr (size, expand_expr (integer_zero_node, NULL_RTX, VOIDmode, 0),
197 else if (cfun != 0 && cfun->x_dont_save_pending_sizes_p)
198 /* The front-end doesn't want us to keep a list of the expressions
199 that determine sizes for variable size objects. */
202 put_pending_size (size);
207 #ifndef MAX_FIXED_MODE_SIZE
208 #define MAX_FIXED_MODE_SIZE GET_MODE_BITSIZE (DImode)
211 /* Return the machine mode to use for a nonscalar of SIZE bits.
212 The mode must be in class CLASS, and have exactly that many bits.
213 If LIMIT is nonzero, modes of wider than MAX_FIXED_MODE_SIZE will not
217 mode_for_size (size, class, limit)
219 enum mode_class class;
222 enum machine_mode mode;
224 if (limit && size > MAX_FIXED_MODE_SIZE)
227 /* Get the first mode which has this size, in the specified class. */
228 for (mode = GET_CLASS_NARROWEST_MODE (class); mode != VOIDmode;
229 mode = GET_MODE_WIDER_MODE (mode))
230 if (GET_MODE_BITSIZE (mode) == size)
236 /* Similar, except passed a tree node. */
239 mode_for_size_tree (size, class, limit)
241 enum mode_class class;
244 if (TREE_CODE (size) != INTEGER_CST
245 /* What we really want to say here is that the size can fit in a
246 host integer, but we know there's no way we'd find a mode for
247 this many bits, so there's no point in doing the precise test. */
248 || compare_tree_int (size, 1000) > 0)
251 return mode_for_size (TREE_INT_CST_LOW (size), class, limit);
254 /* Similar, but never return BLKmode; return the narrowest mode that
255 contains at least the requested number of bits. */
258 smallest_mode_for_size (size, class)
260 enum mode_class class;
262 enum machine_mode mode;
264 /* Get the first mode which has at least this size, in the
266 for (mode = GET_CLASS_NARROWEST_MODE (class); mode != VOIDmode;
267 mode = GET_MODE_WIDER_MODE (mode))
268 if (GET_MODE_BITSIZE (mode) >= size)
274 /* Find an integer mode of the exact same size, or BLKmode on failure. */
277 int_mode_for_mode (mode)
278 enum machine_mode mode;
280 switch (GET_MODE_CLASS (mode))
283 case MODE_PARTIAL_INT:
286 case MODE_COMPLEX_INT:
287 case MODE_COMPLEX_FLOAT:
289 case MODE_VECTOR_INT:
290 case MODE_VECTOR_FLOAT:
291 mode = mode_for_size (GET_MODE_BITSIZE (mode), MODE_INT, 0);
298 /* ... fall through ... */
308 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
309 This can only be applied to objects of a sizetype. */
312 round_up (value, divisor)
316 tree arg = size_int_type (divisor, TREE_TYPE (value));
318 return size_binop (MULT_EXPR, size_binop (CEIL_DIV_EXPR, value, arg), arg);
321 /* Likewise, but round down. */
324 round_down (value, divisor)
328 tree arg = size_int_type (divisor, TREE_TYPE (value));
330 return size_binop (MULT_EXPR, size_binop (FLOOR_DIV_EXPR, value, arg), arg);
333 /* Set the size, mode and alignment of a ..._DECL node.
334 TYPE_DECL does need this for C++.
335 Note that LABEL_DECL and CONST_DECL nodes do not need this,
336 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
337 Don't call layout_decl for them.
339 KNOWN_ALIGN is the amount of alignment we can assume this
340 decl has with no special effort. It is relevant only for FIELD_DECLs
341 and depends on the previous fields.
342 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
343 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
344 the record will be aligned to suit. */
347 layout_decl (decl, known_align)
349 unsigned int known_align;
351 tree type = TREE_TYPE (decl);
352 enum tree_code code = TREE_CODE (decl);
354 if (code == CONST_DECL)
356 else if (code != VAR_DECL && code != PARM_DECL && code != RESULT_DECL
357 && code != TYPE_DECL && code != FIELD_DECL)
360 if (type == error_mark_node)
361 type = void_type_node;
363 /* Usually the size and mode come from the data type without change,
364 however, the front-end may set the explicit width of the field, so its
365 size may not be the same as the size of its type. This happens with
366 bitfields, of course (an `int' bitfield may be only 2 bits, say), but it
367 also happens with other fields. For example, the C++ front-end creates
368 zero-sized fields corresponding to empty base classes, and depends on
369 layout_type setting DECL_FIELD_BITPOS correctly for the field. Set the
370 size in bytes from the size in bits. If we have already set the mode,
371 don't set it again since we can be called twice for FIELD_DECLs. */
373 TREE_UNSIGNED (decl) = TREE_UNSIGNED (type);
374 if (DECL_MODE (decl) == VOIDmode)
375 DECL_MODE (decl) = TYPE_MODE (type);
377 if (DECL_SIZE (decl) == 0)
379 DECL_SIZE (decl) = TYPE_SIZE (type);
380 DECL_SIZE_UNIT (decl) = TYPE_SIZE_UNIT (type);
383 DECL_SIZE_UNIT (decl)
384 = convert (sizetype, size_binop (CEIL_DIV_EXPR, DECL_SIZE (decl),
387 /* Force alignment required for the data type.
388 But if the decl itself wants greater alignment, don't override that.
389 Likewise, if the decl is packed, don't override it. */
390 if (! (code == FIELD_DECL && DECL_BIT_FIELD (decl))
391 && (DECL_ALIGN (decl) == 0
392 || (! (code == FIELD_DECL && DECL_PACKED (decl))
393 && TYPE_ALIGN (type) > DECL_ALIGN (decl))))
395 DECL_ALIGN (decl) = TYPE_ALIGN (type);
396 DECL_USER_ALIGN (decl) = 0;
399 /* For fields, set the bit field type and update the alignment. */
400 if (code == FIELD_DECL)
402 DECL_BIT_FIELD_TYPE (decl) = DECL_BIT_FIELD (decl) ? type : 0;
403 if (maximum_field_alignment != 0)
404 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), maximum_field_alignment);
406 /* If the field is of variable size, we can't misalign it since we
407 have no way to make a temporary to align the result. But this
408 isn't an issue if the decl is not addressable. Likewise if it
409 is of unknown size. */
410 else if (DECL_PACKED (decl)
411 && (DECL_NONADDRESSABLE_P (decl)
412 || DECL_SIZE_UNIT (decl) == 0
413 || TREE_CODE (DECL_SIZE_UNIT (decl)) == INTEGER_CST))
415 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), BITS_PER_UNIT);
416 DECL_USER_ALIGN (decl) = 0;
420 /* See if we can use an ordinary integer mode for a bit-field.
421 Conditions are: a fixed size that is correct for another mode
422 and occupying a complete byte or bytes on proper boundary. */
423 if (code == FIELD_DECL && DECL_BIT_FIELD (decl)
424 && TYPE_SIZE (type) != 0
425 && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
426 && GET_MODE_CLASS (TYPE_MODE (type)) == MODE_INT)
428 enum machine_mode xmode
429 = mode_for_size_tree (DECL_SIZE (decl), MODE_INT, 1);
431 if (xmode != BLKmode && known_align >= GET_MODE_ALIGNMENT (xmode))
433 DECL_ALIGN (decl) = MAX (GET_MODE_ALIGNMENT (xmode),
435 DECL_MODE (decl) = xmode;
436 DECL_BIT_FIELD (decl) = 0;
440 /* Turn off DECL_BIT_FIELD if we won't need it set. */
441 if (code == FIELD_DECL && DECL_BIT_FIELD (decl)
442 && TYPE_MODE (type) == BLKmode && DECL_MODE (decl) == BLKmode
443 && known_align >= TYPE_ALIGN (type)
444 && DECL_ALIGN (decl) >= TYPE_ALIGN (type)
445 && DECL_SIZE_UNIT (decl) != 0)
446 DECL_BIT_FIELD (decl) = 0;
448 /* Evaluate nonconstant size only once, either now or as soon as safe. */
449 if (DECL_SIZE (decl) != 0 && TREE_CODE (DECL_SIZE (decl)) != INTEGER_CST)
450 DECL_SIZE (decl) = variable_size (DECL_SIZE (decl));
451 if (DECL_SIZE_UNIT (decl) != 0
452 && TREE_CODE (DECL_SIZE_UNIT (decl)) != INTEGER_CST)
453 DECL_SIZE_UNIT (decl) = variable_size (DECL_SIZE_UNIT (decl));
455 /* If requested, warn about definitions of large data objects. */
457 && (code == VAR_DECL || code == PARM_DECL)
458 && ! DECL_EXTERNAL (decl))
460 tree size = DECL_SIZE_UNIT (decl);
462 if (size != 0 && TREE_CODE (size) == INTEGER_CST
463 && compare_tree_int (size, larger_than_size) > 0)
465 unsigned int size_as_int = TREE_INT_CST_LOW (size);
467 if (compare_tree_int (size, size_as_int) == 0)
468 warning_with_decl (decl, "size of `%s' is %d bytes", size_as_int);
470 warning_with_decl (decl, "size of `%s' is larger than %d bytes",
476 /* Hook for a front-end function that can modify the record layout as needed
477 immediately before it is finalized. */
479 void (*lang_adjust_rli) PARAMS ((record_layout_info)) = 0;
482 set_lang_adjust_rli (f)
483 void (*f) PARAMS ((record_layout_info));
488 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
489 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
490 is to be passed to all other layout functions for this record. It is the
491 responsibility of the caller to call `free' for the storage returned.
492 Note that garbage collection is not permitted until we finish laying
496 start_record_layout (t)
499 record_layout_info rli
500 = (record_layout_info) xmalloc (sizeof (struct record_layout_info_s));
504 /* If the type has a minimum specified alignment (via an attribute
505 declaration, for example) use it -- otherwise, start with a
506 one-byte alignment. */
507 rli->record_align = MAX (BITS_PER_UNIT, TYPE_ALIGN (t));
508 rli->unpacked_align = rli->unpadded_align = rli->record_align;
509 rli->offset_align = MAX (rli->record_align, BIGGEST_ALIGNMENT);
511 #ifdef STRUCTURE_SIZE_BOUNDARY
512 /* Packed structures don't need to have minimum size. */
513 if (! TYPE_PACKED (t))
514 rli->record_align = MAX (rli->record_align, (unsigned) STRUCTURE_SIZE_BOUNDARY);
517 rli->offset = size_zero_node;
518 rli->bitpos = bitsize_zero_node;
520 rli->pending_statics = 0;
521 rli->packed_maybe_necessary = 0;
526 /* These four routines perform computations that convert between
527 the offset/bitpos forms and byte and bit offsets. */
530 bit_from_pos (offset, bitpos)
533 return size_binop (PLUS_EXPR, bitpos,
534 size_binop (MULT_EXPR, convert (bitsizetype, offset),
539 byte_from_pos (offset, bitpos)
542 return size_binop (PLUS_EXPR, offset,
544 size_binop (TRUNC_DIV_EXPR, bitpos,
545 bitsize_unit_node)));
549 pos_from_bit (poffset, pbitpos, off_align, pos)
550 tree *poffset, *pbitpos;
551 unsigned int off_align;
554 *poffset = size_binop (MULT_EXPR,
556 size_binop (FLOOR_DIV_EXPR, pos,
557 bitsize_int (off_align))),
558 size_int (off_align / BITS_PER_UNIT));
559 *pbitpos = size_binop (FLOOR_MOD_EXPR, pos, bitsize_int (off_align));
562 /* Given a pointer to bit and byte offsets and an offset alignment,
563 normalize the offsets so they are within the alignment. */
566 normalize_offset (poffset, pbitpos, off_align)
567 tree *poffset, *pbitpos;
568 unsigned int off_align;
570 /* If the bit position is now larger than it should be, adjust it
572 if (compare_tree_int (*pbitpos, off_align) >= 0)
574 tree extra_aligns = size_binop (FLOOR_DIV_EXPR, *pbitpos,
575 bitsize_int (off_align));
578 = size_binop (PLUS_EXPR, *poffset,
579 size_binop (MULT_EXPR, convert (sizetype, extra_aligns),
580 size_int (off_align / BITS_PER_UNIT)));
583 = size_binop (FLOOR_MOD_EXPR, *pbitpos, bitsize_int (off_align));
587 /* Print debugging information about the information in RLI. */
591 record_layout_info rli;
593 print_node_brief (stderr, "type", rli->t, 0);
594 print_node_brief (stderr, "\noffset", rli->offset, 0);
595 print_node_brief (stderr, " bitpos", rli->bitpos, 0);
597 fprintf (stderr, "\naligns: rec = %u, unpack = %u, unpad = %u, off = %u\n",
598 rli->record_align, rli->unpacked_align, rli->unpadded_align,
600 if (rli->packed_maybe_necessary)
601 fprintf (stderr, "packed may be necessary\n");
603 if (rli->pending_statics)
605 fprintf (stderr, "pending statics:\n");
606 debug_tree (rli->pending_statics);
610 /* Given an RLI with a possibly-incremented BITPOS, adjust OFFSET and
611 BITPOS if necessary to keep BITPOS below OFFSET_ALIGN. */
615 record_layout_info rli;
617 normalize_offset (&rli->offset, &rli->bitpos, rli->offset_align);
620 /* Returns the size in bytes allocated so far. */
623 rli_size_unit_so_far (rli)
624 record_layout_info rli;
626 return byte_from_pos (rli->offset, rli->bitpos);
629 /* Returns the size in bits allocated so far. */
632 rli_size_so_far (rli)
633 record_layout_info rli;
635 return bit_from_pos (rli->offset, rli->bitpos);
638 /* FIELD is about to be added to RLI->T. The alignment (in bits) of
639 the next available location is given by KNOWN_ALIGN. Update the
640 variable alignment fields in RLI, and return the alignment to give
644 update_alignment_for_field (rli, field, known_align)
645 record_layout_info rli;
647 unsigned int known_align;
649 /* The alignment required for FIELD. */
650 unsigned int desired_align;
651 /* The type of this field. */
652 tree type = TREE_TYPE (field);
653 /* True if the field was explicitly aligned by the user. */
656 /* Lay out the field so we know what alignment it needs. For a
657 packed field, use the alignment as specified, disregarding what
658 the type would want. */
659 desired_align = DECL_ALIGN (field);
660 user_align = DECL_USER_ALIGN (field);
661 layout_decl (field, known_align);
662 if (! DECL_PACKED (field))
664 desired_align = DECL_ALIGN (field);
665 user_align = DECL_USER_ALIGN (field);
668 /* Some targets (i.e. i386, VMS) limit struct field alignment
669 to a lower boundary than alignment of variables unless
670 it was overridden by attribute aligned. */
671 #ifdef BIGGEST_FIELD_ALIGNMENT
674 = MIN (desired_align, (unsigned) BIGGEST_FIELD_ALIGNMENT);
677 #ifdef ADJUST_FIELD_ALIGN
679 desired_align = ADJUST_FIELD_ALIGN (field, desired_align);
682 /* Record must have at least as much alignment as any field.
683 Otherwise, the alignment of the field within the record is
685 if ((* targetm.ms_bitfield_layout_p) (rli->t)
686 && type != error_mark_node
687 && DECL_BIT_FIELD_TYPE (field)
688 && ! integer_zerop (TYPE_SIZE (type)))
690 /* Here, the alignment of the underlying type of a bitfield can
691 affect the alignment of a record; even a zero-sized field
692 can do this. The alignment should be to the alignment of
693 the type, except that for zero-size bitfields this only
694 applies if there was an immediately prior, nonzero-size
695 bitfield. (That's the way it is, experimentally.) */
696 if (! integer_zerop (DECL_SIZE (field))
697 ? ! DECL_PACKED (field)
699 && DECL_BIT_FIELD_TYPE (rli->prev_field)
700 && ! integer_zerop (DECL_SIZE (rli->prev_field))))
702 unsigned int type_align = TYPE_ALIGN (type);
703 type_align = MAX (type_align, desired_align);
704 if (maximum_field_alignment != 0)
705 type_align = MIN (type_align, maximum_field_alignment);
706 rli->record_align = MAX (rli->record_align, type_align);
707 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
708 rli->unpadded_align = MAX (rli->unpadded_align, DECL_ALIGN (field));
714 #ifdef PCC_BITFIELD_TYPE_MATTERS
715 if (PCC_BITFIELD_TYPE_MATTERS && type != error_mark_node
716 && ! (* targetm.ms_bitfield_layout_p) (rli->t)
717 && DECL_BIT_FIELD_TYPE (field)
718 && ! integer_zerop (TYPE_SIZE (type)))
720 /* A zero-length bit-field affects the alignment of the next
722 if (!DECL_PACKED (field) && integer_zerop (DECL_SIZE (field)))
724 desired_align = TYPE_ALIGN (type);
725 #ifdef ADJUST_FIELD_ALIGN
726 desired_align = ADJUST_FIELD_ALIGN (field, desired_align);
730 /* Named bit-fields cause the entire structure to have the
731 alignment implied by their type. */
732 if (DECL_NAME (field) != 0)
734 unsigned int type_align = TYPE_ALIGN (type);
736 #ifdef ADJUST_FIELD_ALIGN
737 if (! TYPE_USER_ALIGN (type))
738 type_align = ADJUST_FIELD_ALIGN (field, type_align);
741 if (maximum_field_alignment != 0)
742 type_align = MIN (type_align, maximum_field_alignment);
743 else if (DECL_PACKED (field))
744 type_align = MIN (type_align, BITS_PER_UNIT);
746 /* The alignment of the record is increased to the maximum
747 of the current alignment, the alignment indicated on the
748 field (i.e., the alignment specified by an __aligned__
749 attribute), and the alignment indicated by the type of
751 rli->record_align = MAX (rli->record_align, desired_align);
752 rli->record_align = MAX (rli->record_align, type_align);
754 rli->unpadded_align = MAX (rli->unpadded_align, DECL_ALIGN (field));
756 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
757 user_align |= TYPE_USER_ALIGN (type);
763 rli->record_align = MAX (rli->record_align, desired_align);
764 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
765 rli->unpadded_align = MAX (rli->unpadded_align, DECL_ALIGN (field));
768 TYPE_USER_ALIGN (rli->t) |= user_align;
770 return desired_align;
773 /* Called from place_field to handle unions. */
776 place_union_field (rli, field)
777 record_layout_info rli;
780 update_alignment_for_field (rli, field, /*known_align=*/0);
782 DECL_FIELD_OFFSET (field) = size_zero_node;
783 DECL_FIELD_BIT_OFFSET (field) = bitsize_zero_node;
784 SET_DECL_OFFSET_ALIGN (field, BIGGEST_ALIGNMENT);
786 /* We assume the union's size will be a multiple of a byte so we don't
787 bother with BITPOS. */
788 if (TREE_CODE (rli->t) == UNION_TYPE)
789 rli->offset = size_binop (MAX_EXPR, rli->offset, DECL_SIZE_UNIT (field));
790 else if (TREE_CODE (rli->t) == QUAL_UNION_TYPE)
791 rli->offset = fold (build (COND_EXPR, sizetype,
792 DECL_QUALIFIER (field),
793 DECL_SIZE_UNIT (field), rli->offset));
796 #if defined (PCC_BITFIELD_TYPE_MATTERS) || defined (BITFIELD_NBYTES_LIMITED)
797 /* A bitfield of SIZE with a required access alignment of ALIGN is allocated
798 at BYTE_OFFSET / BIT_OFFSET. Return nonzero if the field would span more
799 units of alignment than the underlying TYPE. */
801 excess_unit_span (byte_offset, bit_offset, size, align, type)
802 HOST_WIDE_INT byte_offset, bit_offset, size, align;
805 /* Note that the calculation of OFFSET might overflow; we calculate it so
806 that we still get the right result as long as ALIGN is a power of two. */
807 unsigned HOST_WIDE_INT offset = byte_offset * BITS_PER_UNIT + bit_offset;
809 offset = offset % align;
810 return ((offset + size + align - 1) / align
811 > ((unsigned HOST_WIDE_INT) tree_low_cst (TYPE_SIZE (type), 1)
816 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
817 is a FIELD_DECL to be added after those fields already present in
818 T. (FIELD is not actually added to the TYPE_FIELDS list here;
819 callers that desire that behavior must manually perform that step.) */
822 place_field (rli, field)
823 record_layout_info rli;
826 /* The alignment required for FIELD. */
827 unsigned int desired_align;
828 /* The alignment FIELD would have if we just dropped it into the
829 record as it presently stands. */
830 unsigned int known_align;
831 unsigned int actual_align;
832 /* The type of this field. */
833 tree type = TREE_TYPE (field);
835 if (TREE_CODE (field) == ERROR_MARK || TREE_CODE (type) == ERROR_MARK)
838 /* If FIELD is static, then treat it like a separate variable, not
839 really like a structure field. If it is a FUNCTION_DECL, it's a
840 method. In both cases, all we do is lay out the decl, and we do
841 it *after* the record is laid out. */
842 if (TREE_CODE (field) == VAR_DECL)
844 rli->pending_statics = tree_cons (NULL_TREE, field,
845 rli->pending_statics);
849 /* Enumerators and enum types which are local to this class need not
850 be laid out. Likewise for initialized constant fields. */
851 else if (TREE_CODE (field) != FIELD_DECL)
854 /* Unions are laid out very differently than records, so split
855 that code off to another function. */
856 else if (TREE_CODE (rli->t) != RECORD_TYPE)
858 place_union_field (rli, field);
862 /* Work out the known alignment so far. Note that A & (-A) is the
863 value of the least-significant bit in A that is one. */
864 if (! integer_zerop (rli->bitpos))
865 known_align = (tree_low_cst (rli->bitpos, 1)
866 & - tree_low_cst (rli->bitpos, 1));
867 else if (integer_zerop (rli->offset))
868 known_align = BIGGEST_ALIGNMENT;
869 else if (host_integerp (rli->offset, 1))
870 known_align = (BITS_PER_UNIT
871 * (tree_low_cst (rli->offset, 1)
872 & - tree_low_cst (rli->offset, 1)));
874 known_align = rli->offset_align;
876 desired_align = update_alignment_for_field (rli, field, known_align);
878 if (warn_packed && DECL_PACKED (field))
880 if (known_align > TYPE_ALIGN (type))
882 if (TYPE_ALIGN (type) > desired_align)
884 if (STRICT_ALIGNMENT)
885 warning_with_decl (field, "packed attribute causes inefficient alignment for `%s'");
887 warning_with_decl (field, "packed attribute is unnecessary for `%s'");
891 rli->packed_maybe_necessary = 1;
894 /* Does this field automatically have alignment it needs by virtue
895 of the fields that precede it and the record's own alignment? */
896 if (known_align < desired_align)
898 /* No, we need to skip space before this field.
899 Bump the cumulative size to multiple of field alignment. */
902 warning_with_decl (field, "padding struct to align `%s'");
904 /* If the alignment is still within offset_align, just align
906 if (desired_align < rli->offset_align)
907 rli->bitpos = round_up (rli->bitpos, desired_align);
910 /* First adjust OFFSET by the partial bits, then align. */
912 = size_binop (PLUS_EXPR, rli->offset,
914 size_binop (CEIL_DIV_EXPR, rli->bitpos,
915 bitsize_unit_node)));
916 rli->bitpos = bitsize_zero_node;
918 rli->offset = round_up (rli->offset, desired_align / BITS_PER_UNIT);
921 if (! TREE_CONSTANT (rli->offset))
922 rli->offset_align = desired_align;
926 /* Handle compatibility with PCC. Note that if the record has any
927 variable-sized fields, we need not worry about compatibility. */
928 #ifdef PCC_BITFIELD_TYPE_MATTERS
929 if (PCC_BITFIELD_TYPE_MATTERS
930 && ! (* targetm.ms_bitfield_layout_p) (rli->t)
931 && TREE_CODE (field) == FIELD_DECL
932 && type != error_mark_node
933 && DECL_BIT_FIELD (field)
934 && ! DECL_PACKED (field)
935 && maximum_field_alignment == 0
936 && ! integer_zerop (DECL_SIZE (field))
937 && host_integerp (DECL_SIZE (field), 1)
938 && host_integerp (rli->offset, 1)
939 && host_integerp (TYPE_SIZE (type), 1))
941 unsigned int type_align = TYPE_ALIGN (type);
942 tree dsize = DECL_SIZE (field);
943 HOST_WIDE_INT field_size = tree_low_cst (dsize, 1);
944 HOST_WIDE_INT offset = tree_low_cst (rli->offset, 0);
945 HOST_WIDE_INT bit_offset = tree_low_cst (rli->bitpos, 0);
947 #ifdef ADJUST_FIELD_ALIGN
948 if (! TYPE_USER_ALIGN (type))
949 type_align = ADJUST_FIELD_ALIGN (field, type_align);
952 /* A bit field may not span more units of alignment of its type
953 than its type itself. Advance to next boundary if necessary. */
954 if (excess_unit_span (offset, bit_offset, field_size, type_align, type))
955 rli->bitpos = round_up (rli->bitpos, type_align);
957 TYPE_USER_ALIGN (rli->t) |= TYPE_USER_ALIGN (type);
961 #ifdef BITFIELD_NBYTES_LIMITED
962 if (BITFIELD_NBYTES_LIMITED
963 && ! (* targetm.ms_bitfield_layout_p) (rli->t)
964 && TREE_CODE (field) == FIELD_DECL
965 && type != error_mark_node
966 && DECL_BIT_FIELD_TYPE (field)
967 && ! DECL_PACKED (field)
968 && ! integer_zerop (DECL_SIZE (field))
969 && host_integerp (DECL_SIZE (field), 1)
970 && host_integerp (rli->offset, 1)
971 && host_integerp (TYPE_SIZE (type), 1))
973 unsigned int type_align = TYPE_ALIGN (type);
974 tree dsize = DECL_SIZE (field);
975 HOST_WIDE_INT field_size = tree_low_cst (dsize, 1);
976 HOST_WIDE_INT offset = tree_low_cst (rli->offset, 0);
977 HOST_WIDE_INT bit_offset = tree_low_cst (rli->bitpos, 0);
979 #ifdef ADJUST_FIELD_ALIGN
980 if (! TYPE_USER_ALIGN (type))
981 type_align = ADJUST_FIELD_ALIGN (field, type_align);
984 if (maximum_field_alignment != 0)
985 type_align = MIN (type_align, maximum_field_alignment);
986 /* ??? This test is opposite the test in the containing if
987 statement, so this code is unreachable currently. */
988 else if (DECL_PACKED (field))
989 type_align = MIN (type_align, BITS_PER_UNIT);
991 /* A bit field may not span the unit of alignment of its type.
992 Advance to next boundary if necessary. */
993 if (excess_unit_span (offset, bit_offset, field_size, type_align, type))
994 rli->bitpos = round_up (rli->bitpos, type_align);
996 TYPE_USER_ALIGN (rli->t) |= TYPE_USER_ALIGN (type);
1000 /* See the docs for TARGET_MS_BITFIELD_LAYOUT_P for details.
1002 When a bit field is inserted into a packed record, the whole
1003 size of the underlying type is used by one or more same-size
1004 adjacent bitfields. (That is, if its long:3, 32 bits is
1005 used in the record, and any additional adjacent long bitfields are
1006 packed into the same chunk of 32 bits. However, if the size
1007 changes, a new field of that size is allocated.) In an unpacked
1008 record, this is the same as using alignment, but not equivalent
1011 Note: for compatibility, we use the type size, not the type alignment
1012 to determine alignment, since that matches the documentation */
1014 if ((* targetm.ms_bitfield_layout_p) (rli->t)
1015 && ((DECL_BIT_FIELD_TYPE (field) && ! DECL_PACKED (field))
1016 || (rli->prev_field && ! DECL_PACKED (rli->prev_field))))
1018 /* At this point, either the prior or current are bitfields,
1019 (possibly both), and we're dealing with MS packing. */
1020 tree prev_saved = rli->prev_field;
1022 /* Is the prior field a bitfield? If so, handle "runs" of same
1023 type size fields. */
1024 if (rli->prev_field /* necessarily a bitfield if it exists. */)
1026 /* If both are bitfields, nonzero, and the same size, this is
1027 the middle of a run. Zero declared size fields are special
1028 and handled as "end of run". (Note: it's nonzero declared
1029 size, but equal type sizes!) (Since we know that both
1030 the current and previous fields are bitfields by the
1031 time we check it, DECL_SIZE must be present for both.) */
1032 if (DECL_BIT_FIELD_TYPE (field)
1033 && !integer_zerop (DECL_SIZE (field))
1034 && !integer_zerop (DECL_SIZE (rli->prev_field))
1035 && simple_cst_equal (TYPE_SIZE (type),
1036 TYPE_SIZE (TREE_TYPE (rli->prev_field))) )
1038 /* We're in the middle of a run of equal type size fields; make
1039 sure we realign if we run out of bits. (Not decl size,
1041 int bitsize = TREE_INT_CST_LOW (DECL_SIZE (field));
1042 tree type_size = TYPE_SIZE(TREE_TYPE(rli->prev_field));
1044 if (rli->remaining_in_alignment < bitsize)
1046 /* out of bits; bump up to next 'word'. */
1047 rli->offset = DECL_FIELD_OFFSET (rli->prev_field);
1048 rli->bitpos = size_binop (PLUS_EXPR,
1050 DECL_FIELD_BIT_OFFSET(rli->prev_field));
1051 rli->prev_field = field;
1052 rli->remaining_in_alignment = TREE_INT_CST_LOW (type_size);
1054 rli->remaining_in_alignment -= bitsize;
1058 /* End of a run: if leaving a run of bitfields of the same type
1059 size, we have to "use up" the rest of the bits of the type
1062 Compute the new position as the sum of the size for the prior
1063 type and where we first started working on that type.
1064 Note: since the beginning of the field was aligned then
1065 of course the end will be too. No round needed. */
1067 if (!integer_zerop (DECL_SIZE (rli->prev_field)))
1069 tree type_size = TYPE_SIZE(TREE_TYPE(rli->prev_field));
1070 rli->bitpos = size_binop (PLUS_EXPR,
1072 DECL_FIELD_BIT_OFFSET(rli->prev_field));
1076 /* We "use up" size zero fields; the code below should behave
1077 as if the prior field was not a bitfield. */
1081 /* Cause a new bitfield to be captured, either this time (if
1082 currently a bitfield) or next time we see one. */
1083 if (!DECL_BIT_FIELD_TYPE(field)
1084 || integer_zerop (DECL_SIZE (field)))
1086 rli->prev_field = NULL;
1089 normalize_rli (rli);
1092 /* If we're starting a new run of same size type bitfields
1093 (or a run of non-bitfields), set up the "first of the run"
1096 That is, if the current field is not a bitfield, or if there
1097 was a prior bitfield the type sizes differ, or if there wasn't
1098 a prior bitfield the size of the current field is nonzero.
1100 Note: we must be sure to test ONLY the type size if there was
1101 a prior bitfield and ONLY for the current field being zero if
1104 if (!DECL_BIT_FIELD_TYPE (field)
1105 || ( prev_saved != NULL
1106 ? !simple_cst_equal (TYPE_SIZE (type),
1107 TYPE_SIZE (TREE_TYPE (prev_saved)))
1108 : !integer_zerop (DECL_SIZE (field)) ))
1110 unsigned int type_align = 8; /* Never below 8 for compatibility */
1112 /* (When not a bitfield), we could be seeing a flex array (with
1113 no DECL_SIZE). Since we won't be using remaining_in_alignment
1114 until we see a bitfield (and come by here again) we just skip
1117 if (DECL_SIZE (field) != NULL)
1118 rli->remaining_in_alignment
1119 = TREE_INT_CST_LOW (TYPE_SIZE(TREE_TYPE(field)))
1120 - TREE_INT_CST_LOW (DECL_SIZE (field));
1122 /* Now align (conventionally) for the new type. */
1123 if (!DECL_PACKED(field))
1124 type_align = MAX(TYPE_ALIGN (type), type_align);
1127 && DECL_BIT_FIELD_TYPE (prev_saved)
1128 /* If the previous bit-field is zero-sized, we've already
1129 accounted for its alignment needs (or ignored it, if
1130 appropriate) while placing it. */
1131 && ! integer_zerop (DECL_SIZE (prev_saved)))
1132 type_align = MAX (type_align,
1133 TYPE_ALIGN (TREE_TYPE (prev_saved)));
1135 if (maximum_field_alignment != 0)
1136 type_align = MIN (type_align, maximum_field_alignment);
1138 rli->bitpos = round_up (rli->bitpos, type_align);
1139 /* If we really aligned, don't allow subsequent bitfields
1141 rli->prev_field = NULL;
1145 /* Offset so far becomes the position of this field after normalizing. */
1146 normalize_rli (rli);
1147 DECL_FIELD_OFFSET (field) = rli->offset;
1148 DECL_FIELD_BIT_OFFSET (field) = rli->bitpos;
1149 SET_DECL_OFFSET_ALIGN (field, rli->offset_align);
1151 /* If this field ended up more aligned than we thought it would be (we
1152 approximate this by seeing if its position changed), lay out the field
1153 again; perhaps we can use an integral mode for it now. */
1154 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field)))
1155 actual_align = (tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1)
1156 & - tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1));
1157 else if (integer_zerop (DECL_FIELD_OFFSET (field)))
1158 actual_align = BIGGEST_ALIGNMENT;
1159 else if (host_integerp (DECL_FIELD_OFFSET (field), 1))
1160 actual_align = (BITS_PER_UNIT
1161 * (tree_low_cst (DECL_FIELD_OFFSET (field), 1)
1162 & - tree_low_cst (DECL_FIELD_OFFSET (field), 1)));
1164 actual_align = DECL_OFFSET_ALIGN (field);
1166 if (known_align != actual_align)
1167 layout_decl (field, actual_align);
1169 /* Only the MS bitfields use this. */
1170 if (rli->prev_field == NULL && DECL_BIT_FIELD_TYPE(field))
1171 rli->prev_field = field;
1173 /* Now add size of this field to the size of the record. If the size is
1174 not constant, treat the field as being a multiple of bytes and just
1175 adjust the offset, resetting the bit position. Otherwise, apportion the
1176 size amongst the bit position and offset. First handle the case of an
1177 unspecified size, which can happen when we have an invalid nested struct
1178 definition, such as struct j { struct j { int i; } }. The error message
1179 is printed in finish_struct. */
1180 if (DECL_SIZE (field) == 0)
1182 else if (TREE_CODE (DECL_SIZE_UNIT (field)) != INTEGER_CST
1183 || TREE_CONSTANT_OVERFLOW (DECL_SIZE_UNIT (field)))
1186 = size_binop (PLUS_EXPR, rli->offset,
1188 size_binop (CEIL_DIV_EXPR, rli->bitpos,
1189 bitsize_unit_node)));
1191 = size_binop (PLUS_EXPR, rli->offset, DECL_SIZE_UNIT (field));
1192 rli->bitpos = bitsize_zero_node;
1193 rli->offset_align = MIN (rli->offset_align, DECL_ALIGN (field));
1197 rli->bitpos = size_binop (PLUS_EXPR, rli->bitpos, DECL_SIZE (field));
1198 normalize_rli (rli);
1202 /* Assuming that all the fields have been laid out, this function uses
1203 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
1204 indicated by RLI. */
1207 finalize_record_size (rli)
1208 record_layout_info rli;
1210 tree unpadded_size, unpadded_size_unit;
1212 /* Now we want just byte and bit offsets, so set the offset alignment
1213 to be a byte and then normalize. */
1214 rli->offset_align = BITS_PER_UNIT;
1215 normalize_rli (rli);
1217 /* Determine the desired alignment. */
1218 #ifdef ROUND_TYPE_ALIGN
1219 TYPE_ALIGN (rli->t) = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t),
1222 TYPE_ALIGN (rli->t) = MAX (TYPE_ALIGN (rli->t), rli->record_align);
1225 /* Compute the size so far. Be sure to allow for extra bits in the
1226 size in bytes. We have guaranteed above that it will be no more
1227 than a single byte. */
1228 unpadded_size = rli_size_so_far (rli);
1229 unpadded_size_unit = rli_size_unit_so_far (rli);
1230 if (! integer_zerop (rli->bitpos))
1232 = size_binop (PLUS_EXPR, unpadded_size_unit, size_one_node);
1234 /* Record the un-rounded size in the binfo node. But first we check
1235 the size of TYPE_BINFO to make sure that BINFO_SIZE is available. */
1236 if (TYPE_BINFO (rli->t) && TREE_VEC_LENGTH (TYPE_BINFO (rli->t)) > 6)
1238 TYPE_BINFO_SIZE (rli->t) = unpadded_size;
1239 TYPE_BINFO_SIZE_UNIT (rli->t) = unpadded_size_unit;
1242 /* Round the size up to be a multiple of the required alignment */
1243 #ifdef ROUND_TYPE_SIZE
1244 TYPE_SIZE (rli->t) = ROUND_TYPE_SIZE (rli->t, unpadded_size,
1245 TYPE_ALIGN (rli->t));
1246 TYPE_SIZE_UNIT (rli->t)
1247 = ROUND_TYPE_SIZE_UNIT (rli->t, unpadded_size_unit,
1248 TYPE_ALIGN (rli->t) / BITS_PER_UNIT);
1250 TYPE_SIZE (rli->t) = round_up (unpadded_size, TYPE_ALIGN (rli->t));
1251 TYPE_SIZE_UNIT (rli->t) = round_up (unpadded_size_unit,
1252 TYPE_ALIGN (rli->t) / BITS_PER_UNIT);
1255 if (warn_padded && TREE_CONSTANT (unpadded_size)
1256 && simple_cst_equal (unpadded_size, TYPE_SIZE (rli->t)) == 0)
1257 warning ("padding struct size to alignment boundary");
1259 if (warn_packed && TREE_CODE (rli->t) == RECORD_TYPE
1260 && TYPE_PACKED (rli->t) && ! rli->packed_maybe_necessary
1261 && TREE_CONSTANT (unpadded_size))
1265 #ifdef ROUND_TYPE_ALIGN
1267 = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t), rli->unpacked_align);
1269 rli->unpacked_align = MAX (TYPE_ALIGN (rli->t), rli->unpacked_align);
1272 #ifdef ROUND_TYPE_SIZE
1273 unpacked_size = ROUND_TYPE_SIZE (rli->t, TYPE_SIZE (rli->t),
1274 rli->unpacked_align);
1276 unpacked_size = round_up (TYPE_SIZE (rli->t), rli->unpacked_align);
1279 if (simple_cst_equal (unpacked_size, TYPE_SIZE (rli->t)))
1281 TYPE_PACKED (rli->t) = 0;
1283 if (TYPE_NAME (rli->t))
1287 if (TREE_CODE (TYPE_NAME (rli->t)) == IDENTIFIER_NODE)
1288 name = IDENTIFIER_POINTER (TYPE_NAME (rli->t));
1290 name = IDENTIFIER_POINTER (DECL_NAME (TYPE_NAME (rli->t)));
1292 if (STRICT_ALIGNMENT)
1293 warning ("packed attribute causes inefficient alignment for `%s'", name);
1295 warning ("packed attribute is unnecessary for `%s'", name);
1299 if (STRICT_ALIGNMENT)
1300 warning ("packed attribute causes inefficient alignment");
1302 warning ("packed attribute is unnecessary");
1308 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
1311 compute_record_mode (type)
1315 enum machine_mode mode = VOIDmode;
1317 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
1318 However, if possible, we use a mode that fits in a register
1319 instead, in order to allow for better optimization down the
1321 TYPE_MODE (type) = BLKmode;
1323 if (! host_integerp (TYPE_SIZE (type), 1))
1326 /* A record which has any BLKmode members must itself be
1327 BLKmode; it can't go in a register. Unless the member is
1328 BLKmode only because it isn't aligned. */
1329 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1331 unsigned HOST_WIDE_INT bitpos;
1333 if (TREE_CODE (field) != FIELD_DECL)
1336 if (TREE_CODE (TREE_TYPE (field)) == ERROR_MARK
1337 || (TYPE_MODE (TREE_TYPE (field)) == BLKmode
1338 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field)))
1339 || ! host_integerp (bit_position (field), 1)
1340 || DECL_SIZE (field) == 0
1341 || ! host_integerp (DECL_SIZE (field), 1))
1344 bitpos = int_bit_position (field);
1346 /* Must be BLKmode if any field crosses a word boundary,
1347 since extract_bit_field can't handle that in registers. */
1348 if (bitpos / BITS_PER_WORD
1349 != ((tree_low_cst (DECL_SIZE (field), 1) + bitpos - 1)
1351 /* But there is no problem if the field is entire words. */
1352 && tree_low_cst (DECL_SIZE (field), 1) % BITS_PER_WORD != 0)
1355 /* If this field is the whole struct, remember its mode so
1356 that, say, we can put a double in a class into a DF
1357 register instead of forcing it to live in the stack. */
1358 if (simple_cst_equal (TYPE_SIZE (type), DECL_SIZE (field)))
1359 mode = DECL_MODE (field);
1361 #ifdef MEMBER_TYPE_FORCES_BLK
1362 /* With some targets, eg. c4x, it is sub-optimal
1363 to access an aligned BLKmode structure as a scalar. */
1365 if (MEMBER_TYPE_FORCES_BLK (field, mode))
1367 #endif /* MEMBER_TYPE_FORCES_BLK */
1370 /* If we only have one real field; use its mode. This only applies to
1371 RECORD_TYPE. This does not apply to unions. */
1372 if (TREE_CODE (type) == RECORD_TYPE && mode != VOIDmode)
1373 TYPE_MODE (type) = mode;
1375 TYPE_MODE (type) = mode_for_size_tree (TYPE_SIZE (type), MODE_INT, 1);
1377 /* If structure's known alignment is less than what the scalar
1378 mode would need, and it matters, then stick with BLKmode. */
1379 if (TYPE_MODE (type) != BLKmode
1381 && ! (TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT
1382 || TYPE_ALIGN (type) >= GET_MODE_ALIGNMENT (TYPE_MODE (type))))
1384 /* If this is the only reason this type is BLKmode, then
1385 don't force containing types to be BLKmode. */
1386 TYPE_NO_FORCE_BLK (type) = 1;
1387 TYPE_MODE (type) = BLKmode;
1391 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1395 finalize_type_size (type)
1398 /* Normally, use the alignment corresponding to the mode chosen.
1399 However, where strict alignment is not required, avoid
1400 over-aligning structures, since most compilers do not do this
1403 if (TYPE_MODE (type) != BLKmode && TYPE_MODE (type) != VOIDmode
1404 && (STRICT_ALIGNMENT
1405 || (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE
1406 && TREE_CODE (type) != QUAL_UNION_TYPE
1407 && TREE_CODE (type) != ARRAY_TYPE)))
1409 TYPE_ALIGN (type) = GET_MODE_ALIGNMENT (TYPE_MODE (type));
1410 TYPE_USER_ALIGN (type) = 0;
1413 /* Do machine-dependent extra alignment. */
1414 #ifdef ROUND_TYPE_ALIGN
1416 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (type), BITS_PER_UNIT);
1419 /* If we failed to find a simple way to calculate the unit size
1420 of the type, find it by division. */
1421 if (TYPE_SIZE_UNIT (type) == 0 && TYPE_SIZE (type) != 0)
1422 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1423 result will fit in sizetype. We will get more efficient code using
1424 sizetype, so we force a conversion. */
1425 TYPE_SIZE_UNIT (type)
1426 = convert (sizetype,
1427 size_binop (FLOOR_DIV_EXPR, TYPE_SIZE (type),
1428 bitsize_unit_node));
1430 if (TYPE_SIZE (type) != 0)
1432 #ifdef ROUND_TYPE_SIZE
1434 = ROUND_TYPE_SIZE (type, TYPE_SIZE (type), TYPE_ALIGN (type));
1435 TYPE_SIZE_UNIT (type)
1436 = ROUND_TYPE_SIZE_UNIT (type, TYPE_SIZE_UNIT (type),
1437 TYPE_ALIGN (type) / BITS_PER_UNIT);
1439 TYPE_SIZE (type) = round_up (TYPE_SIZE (type), TYPE_ALIGN (type));
1440 TYPE_SIZE_UNIT (type)
1441 = round_up (TYPE_SIZE_UNIT (type), TYPE_ALIGN (type) / BITS_PER_UNIT);
1445 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1446 if (TYPE_SIZE (type) != 0 && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
1447 TYPE_SIZE (type) = variable_size (TYPE_SIZE (type));
1448 if (TYPE_SIZE_UNIT (type) != 0
1449 && TREE_CODE (TYPE_SIZE_UNIT (type)) != INTEGER_CST)
1450 TYPE_SIZE_UNIT (type) = variable_size (TYPE_SIZE_UNIT (type));
1452 /* Also layout any other variants of the type. */
1453 if (TYPE_NEXT_VARIANT (type)
1454 || type != TYPE_MAIN_VARIANT (type))
1457 /* Record layout info of this variant. */
1458 tree size = TYPE_SIZE (type);
1459 tree size_unit = TYPE_SIZE_UNIT (type);
1460 unsigned int align = TYPE_ALIGN (type);
1461 unsigned int user_align = TYPE_USER_ALIGN (type);
1462 enum machine_mode mode = TYPE_MODE (type);
1464 /* Copy it into all variants. */
1465 for (variant = TYPE_MAIN_VARIANT (type);
1467 variant = TYPE_NEXT_VARIANT (variant))
1469 TYPE_SIZE (variant) = size;
1470 TYPE_SIZE_UNIT (variant) = size_unit;
1471 TYPE_ALIGN (variant) = align;
1472 TYPE_USER_ALIGN (variant) = user_align;
1473 TYPE_MODE (variant) = mode;
1478 /* Do all of the work required to layout the type indicated by RLI,
1479 once the fields have been laid out. This function will call `free'
1480 for RLI, unless FREE_P is false. Passing a value other than false
1481 for FREE_P is bad practice; this option only exists to support the
1485 finish_record_layout (rli, free_p)
1486 record_layout_info rli;
1489 /* Compute the final size. */
1490 finalize_record_size (rli);
1492 /* Compute the TYPE_MODE for the record. */
1493 compute_record_mode (rli->t);
1495 /* Perform any last tweaks to the TYPE_SIZE, etc. */
1496 finalize_type_size (rli->t);
1498 /* Lay out any static members. This is done now because their type
1499 may use the record's type. */
1500 while (rli->pending_statics)
1502 layout_decl (TREE_VALUE (rli->pending_statics), 0);
1503 rli->pending_statics = TREE_CHAIN (rli->pending_statics);
1512 /* Finish processing a builtin RECORD_TYPE type TYPE. It's name is
1513 NAME, its fields are chained in reverse on FIELDS.
1515 If ALIGN_TYPE is non-null, it is given the same alignment as
1519 finish_builtin_struct (type, name, fields, align_type)
1527 for (tail = NULL_TREE; fields; tail = fields, fields = next)
1529 DECL_FIELD_CONTEXT (fields) = type;
1530 next = TREE_CHAIN (fields);
1531 TREE_CHAIN (fields) = tail;
1533 TYPE_FIELDS (type) = tail;
1537 TYPE_ALIGN (type) = TYPE_ALIGN (align_type);
1538 TYPE_USER_ALIGN (type) = TYPE_USER_ALIGN (align_type);
1542 #if 0 /* not yet, should get fixed properly later */
1543 TYPE_NAME (type) = make_type_decl (get_identifier (name), type);
1545 TYPE_NAME (type) = build_decl (TYPE_DECL, get_identifier (name), type);
1547 TYPE_STUB_DECL (type) = TYPE_NAME (type);
1548 layout_decl (TYPE_NAME (type), 0);
1551 /* Calculate the mode, size, and alignment for TYPE.
1552 For an array type, calculate the element separation as well.
1553 Record TYPE on the chain of permanent or temporary types
1554 so that dbxout will find out about it.
1556 TYPE_SIZE of a type is nonzero if the type has been laid out already.
1557 layout_type does nothing on such a type.
1559 If the type is incomplete, its TYPE_SIZE remains zero. */
1568 /* Do nothing if type has been laid out before. */
1569 if (TYPE_SIZE (type))
1572 switch (TREE_CODE (type))
1575 /* This kind of type is the responsibility
1576 of the language-specific code. */
1579 case BOOLEAN_TYPE: /* Used for Java, Pascal, and Chill. */
1580 if (TYPE_PRECISION (type) == 0)
1581 TYPE_PRECISION (type) = 1; /* default to one byte/boolean. */
1583 /* ... fall through ... */
1588 if (TREE_CODE (TYPE_MIN_VALUE (type)) == INTEGER_CST
1589 && tree_int_cst_sgn (TYPE_MIN_VALUE (type)) >= 0)
1590 TREE_UNSIGNED (type) = 1;
1592 TYPE_MODE (type) = smallest_mode_for_size (TYPE_PRECISION (type),
1594 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1595 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1599 TYPE_MODE (type) = mode_for_size (TYPE_PRECISION (type), MODE_FLOAT, 0);
1600 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1601 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1605 TREE_UNSIGNED (type) = TREE_UNSIGNED (TREE_TYPE (type));
1607 = mode_for_size (2 * TYPE_PRECISION (TREE_TYPE (type)),
1608 (TREE_CODE (TREE_TYPE (type)) == INTEGER_TYPE
1609 ? MODE_COMPLEX_INT : MODE_COMPLEX_FLOAT),
1611 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1612 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1619 subtype = TREE_TYPE (type);
1620 TREE_UNSIGNED (type) = TREE_UNSIGNED (subtype);
1621 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1622 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1627 /* This is an incomplete type and so doesn't have a size. */
1628 TYPE_ALIGN (type) = 1;
1629 TYPE_USER_ALIGN (type) = 0;
1630 TYPE_MODE (type) = VOIDmode;
1634 TYPE_SIZE (type) = bitsize_int (POINTER_SIZE);
1635 TYPE_SIZE_UNIT (type) = size_int (POINTER_SIZE / BITS_PER_UNIT);
1636 /* A pointer might be MODE_PARTIAL_INT,
1637 but ptrdiff_t must be integral. */
1638 TYPE_MODE (type) = mode_for_size (POINTER_SIZE, MODE_INT, 0);
1643 TYPE_MODE (type) = mode_for_size (2 * POINTER_SIZE, MODE_INT, 0);
1644 TYPE_SIZE (type) = bitsize_int (2 * POINTER_SIZE);
1645 TYPE_SIZE_UNIT (type) = size_int ((2 * POINTER_SIZE) / BITS_PER_UNIT);
1649 case REFERENCE_TYPE:
1652 enum machine_mode mode = ((TREE_CODE (type) == REFERENCE_TYPE
1653 && reference_types_internal)
1654 ? Pmode : TYPE_MODE (type));
1656 int nbits = GET_MODE_BITSIZE (mode);
1658 TYPE_SIZE (type) = bitsize_int (nbits);
1659 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (mode));
1660 TREE_UNSIGNED (type) = 1;
1661 TYPE_PRECISION (type) = nbits;
1667 tree index = TYPE_DOMAIN (type);
1668 tree element = TREE_TYPE (type);
1670 build_pointer_type (element);
1672 /* We need to know both bounds in order to compute the size. */
1673 if (index && TYPE_MAX_VALUE (index) && TYPE_MIN_VALUE (index)
1674 && TYPE_SIZE (element))
1676 tree ub = TYPE_MAX_VALUE (index);
1677 tree lb = TYPE_MIN_VALUE (index);
1681 /* The initial subtraction should happen in the original type so
1682 that (possible) negative values are handled appropriately. */
1683 length = size_binop (PLUS_EXPR, size_one_node,
1685 fold (build (MINUS_EXPR,
1689 /* Special handling for arrays of bits (for Chill). */
1690 element_size = TYPE_SIZE (element);
1691 if (TYPE_PACKED (type) && INTEGRAL_TYPE_P (element)
1692 && (integer_zerop (TYPE_MAX_VALUE (element))
1693 || integer_onep (TYPE_MAX_VALUE (element)))
1694 && host_integerp (TYPE_MIN_VALUE (element), 1))
1696 HOST_WIDE_INT maxvalue
1697 = tree_low_cst (TYPE_MAX_VALUE (element), 1);
1698 HOST_WIDE_INT minvalue
1699 = tree_low_cst (TYPE_MIN_VALUE (element), 1);
1701 if (maxvalue - minvalue == 1
1702 && (maxvalue == 1 || maxvalue == 0))
1703 element_size = integer_one_node;
1706 TYPE_SIZE (type) = size_binop (MULT_EXPR, element_size,
1707 convert (bitsizetype, length));
1709 /* If we know the size of the element, calculate the total
1710 size directly, rather than do some division thing below.
1711 This optimization helps Fortran assumed-size arrays
1712 (where the size of the array is determined at runtime)
1714 Note that we can't do this in the case where the size of
1715 the elements is one bit since TYPE_SIZE_UNIT cannot be
1716 set correctly in that case. */
1717 if (TYPE_SIZE_UNIT (element) != 0 && ! integer_onep (element_size))
1718 TYPE_SIZE_UNIT (type)
1719 = size_binop (MULT_EXPR, TYPE_SIZE_UNIT (element), length);
1722 /* Now round the alignment and size,
1723 using machine-dependent criteria if any. */
1725 #ifdef ROUND_TYPE_ALIGN
1727 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (element), BITS_PER_UNIT);
1729 TYPE_ALIGN (type) = MAX (TYPE_ALIGN (element), BITS_PER_UNIT);
1731 TYPE_USER_ALIGN (type) = TYPE_USER_ALIGN (element);
1733 #ifdef ROUND_TYPE_SIZE
1734 if (TYPE_SIZE (type) != 0)
1737 = ROUND_TYPE_SIZE (type, TYPE_SIZE (type), TYPE_ALIGN (type));
1739 /* If the rounding changed the size of the type, remove any
1740 pre-calculated TYPE_SIZE_UNIT. */
1741 if (simple_cst_equal (TYPE_SIZE (type), tmp) != 1)
1742 TYPE_SIZE_UNIT (type) = NULL;
1744 TYPE_SIZE (type) = tmp;
1748 TYPE_MODE (type) = BLKmode;
1749 if (TYPE_SIZE (type) != 0
1750 #ifdef MEMBER_TYPE_FORCES_BLK
1751 && ! MEMBER_TYPE_FORCES_BLK (type, VOIDmode)
1753 /* BLKmode elements force BLKmode aggregate;
1754 else extract/store fields may lose. */
1755 && (TYPE_MODE (TREE_TYPE (type)) != BLKmode
1756 || TYPE_NO_FORCE_BLK (TREE_TYPE (type))))
1758 /* One-element arrays get the component type's mode. */
1759 if (simple_cst_equal (TYPE_SIZE (type),
1760 TYPE_SIZE (TREE_TYPE (type))))
1761 TYPE_MODE (type) = TYPE_MODE (TREE_TYPE (type));
1764 = mode_for_size_tree (TYPE_SIZE (type), MODE_INT, 1);
1766 if (TYPE_MODE (type) != BLKmode
1767 && STRICT_ALIGNMENT && TYPE_ALIGN (type) < BIGGEST_ALIGNMENT
1768 && TYPE_ALIGN (type) < GET_MODE_ALIGNMENT (TYPE_MODE (type))
1769 && TYPE_MODE (type) != BLKmode)
1771 TYPE_NO_FORCE_BLK (type) = 1;
1772 TYPE_MODE (type) = BLKmode;
1780 case QUAL_UNION_TYPE:
1783 record_layout_info rli;
1785 /* Initialize the layout information. */
1786 rli = start_record_layout (type);
1788 /* If this is a QUAL_UNION_TYPE, we want to process the fields
1789 in the reverse order in building the COND_EXPR that denotes
1790 its size. We reverse them again later. */
1791 if (TREE_CODE (type) == QUAL_UNION_TYPE)
1792 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
1794 /* Place all the fields. */
1795 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1796 place_field (rli, field);
1798 if (TREE_CODE (type) == QUAL_UNION_TYPE)
1799 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
1801 if (lang_adjust_rli)
1802 (*lang_adjust_rli) (rli);
1804 /* Finish laying out the record. */
1805 finish_record_layout (rli, /*free_p=*/true);
1809 case SET_TYPE: /* Used by Chill and Pascal. */
1810 if (TREE_CODE (TYPE_MAX_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST
1811 || TREE_CODE (TYPE_MIN_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST)
1815 #ifndef SET_WORD_SIZE
1816 #define SET_WORD_SIZE BITS_PER_WORD
1818 unsigned int alignment
1819 = set_alignment ? set_alignment : SET_WORD_SIZE;
1821 = (TREE_INT_CST_LOW (TYPE_MAX_VALUE (TYPE_DOMAIN (type)))
1822 - TREE_INT_CST_LOW (TYPE_MIN_VALUE (TYPE_DOMAIN (type))) + 1);
1824 = ((size_in_bits + alignment - 1) / alignment) * alignment;
1826 if (rounded_size > (int) alignment)
1827 TYPE_MODE (type) = BLKmode;
1829 TYPE_MODE (type) = mode_for_size (alignment, MODE_INT, 1);
1831 TYPE_SIZE (type) = bitsize_int (rounded_size);
1832 TYPE_SIZE_UNIT (type) = size_int (rounded_size / BITS_PER_UNIT);
1833 TYPE_ALIGN (type) = alignment;
1834 TYPE_USER_ALIGN (type) = 0;
1835 TYPE_PRECISION (type) = size_in_bits;
1840 /* The size may vary in different languages, so the language front end
1841 should fill in the size. */
1842 TYPE_ALIGN (type) = BIGGEST_ALIGNMENT;
1843 TYPE_USER_ALIGN (type) = 0;
1844 TYPE_MODE (type) = BLKmode;
1851 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
1852 records and unions, finish_record_layout already called this
1854 if (TREE_CODE (type) != RECORD_TYPE
1855 && TREE_CODE (type) != UNION_TYPE
1856 && TREE_CODE (type) != QUAL_UNION_TYPE)
1857 finalize_type_size (type);
1859 /* If this type is created before sizetype has been permanently set,
1860 record it so set_sizetype can fix it up. */
1862 early_type_list = tree_cons (NULL_TREE, type, early_type_list);
1864 /* If an alias set has been set for this aggregate when it was incomplete,
1865 force it into alias set 0.
1866 This is too conservative, but we cannot call record_component_aliases
1867 here because some frontends still change the aggregates after
1869 if (AGGREGATE_TYPE_P (type) && TYPE_ALIAS_SET_KNOWN_P (type))
1870 TYPE_ALIAS_SET (type) = 0;
1873 /* Create and return a type for signed integers of PRECISION bits. */
1876 make_signed_type (precision)
1879 tree type = make_node (INTEGER_TYPE);
1881 TYPE_PRECISION (type) = precision;
1883 fixup_signed_type (type);
1887 /* Create and return a type for unsigned integers of PRECISION bits. */
1890 make_unsigned_type (precision)
1893 tree type = make_node (INTEGER_TYPE);
1895 TYPE_PRECISION (type) = precision;
1897 fixup_unsigned_type (type);
1901 /* Initialize sizetype and bitsizetype to a reasonable and temporary
1902 value to enable integer types to be created. */
1905 initialize_sizetypes ()
1907 tree t = make_node (INTEGER_TYPE);
1909 /* Set this so we do something reasonable for the build_int_2 calls
1911 integer_type_node = t;
1913 TYPE_MODE (t) = SImode;
1914 TYPE_ALIGN (t) = GET_MODE_ALIGNMENT (SImode);
1915 TYPE_USER_ALIGN (t) = 0;
1916 TYPE_SIZE (t) = build_int_2 (GET_MODE_BITSIZE (SImode), 0);
1917 TYPE_SIZE_UNIT (t) = build_int_2 (GET_MODE_SIZE (SImode), 0);
1918 TREE_UNSIGNED (t) = 1;
1919 TYPE_PRECISION (t) = GET_MODE_BITSIZE (SImode);
1920 TYPE_MIN_VALUE (t) = build_int_2 (0, 0);
1921 TYPE_IS_SIZETYPE (t) = 1;
1923 /* 1000 avoids problems with possible overflow and is certainly
1924 larger than any size value we'd want to be storing. */
1925 TYPE_MAX_VALUE (t) = build_int_2 (1000, 0);
1927 /* These two must be different nodes because of the caching done in
1930 bitsizetype = copy_node (t);
1931 integer_type_node = 0;
1934 /* Set sizetype to TYPE, and initialize *sizetype accordingly.
1935 Also update the type of any standard type's sizes made so far. */
1941 int oprecision = TYPE_PRECISION (type);
1942 /* The *bitsizetype types use a precision that avoids overflows when
1943 calculating signed sizes / offsets in bits. However, when
1944 cross-compiling from a 32 bit to a 64 bit host, we are limited to 64 bit
1946 int precision = MIN (oprecision + BITS_PER_UNIT_LOG + 1,
1947 2 * HOST_BITS_PER_WIDE_INT);
1954 /* Make copies of nodes since we'll be setting TYPE_IS_SIZETYPE. */
1955 sizetype = copy_node (type);
1956 TYPE_DOMAIN (sizetype) = type;
1957 TYPE_IS_SIZETYPE (sizetype) = 1;
1958 bitsizetype = make_node (INTEGER_TYPE);
1959 TYPE_NAME (bitsizetype) = TYPE_NAME (type);
1960 TYPE_PRECISION (bitsizetype) = precision;
1961 TYPE_IS_SIZETYPE (bitsizetype) = 1;
1963 if (TREE_UNSIGNED (type))
1964 fixup_unsigned_type (bitsizetype);
1966 fixup_signed_type (bitsizetype);
1968 layout_type (bitsizetype);
1970 if (TREE_UNSIGNED (type))
1972 usizetype = sizetype;
1973 ubitsizetype = bitsizetype;
1974 ssizetype = copy_node (make_signed_type (oprecision));
1975 sbitsizetype = copy_node (make_signed_type (precision));
1979 ssizetype = sizetype;
1980 sbitsizetype = bitsizetype;
1981 usizetype = copy_node (make_unsigned_type (oprecision));
1982 ubitsizetype = copy_node (make_unsigned_type (precision));
1985 TYPE_NAME (bitsizetype) = get_identifier ("bit_size_type");
1987 /* Show is a sizetype, is a main type, and has no pointers to it. */
1988 for (i = 0; i < ARRAY_SIZE (sizetype_tab); i++)
1990 TYPE_IS_SIZETYPE (sizetype_tab[i]) = 1;
1991 TYPE_MAIN_VARIANT (sizetype_tab[i]) = sizetype_tab[i];
1992 TYPE_NEXT_VARIANT (sizetype_tab[i]) = 0;
1993 TYPE_POINTER_TO (sizetype_tab[i]) = 0;
1994 TYPE_REFERENCE_TO (sizetype_tab[i]) = 0;
1997 /* Go down each of the types we already made and set the proper type
1998 for the sizes in them. */
1999 for (t = early_type_list; t != 0; t = TREE_CHAIN (t))
2001 if (TREE_CODE (TREE_VALUE (t)) != INTEGER_TYPE)
2004 TREE_TYPE (TYPE_SIZE (TREE_VALUE (t))) = bitsizetype;
2005 TREE_TYPE (TYPE_SIZE_UNIT (TREE_VALUE (t))) = sizetype;
2008 early_type_list = 0;
2012 /* Set the extreme values of TYPE based on its precision in bits,
2013 then lay it out. Used when make_signed_type won't do
2014 because the tree code is not INTEGER_TYPE.
2015 E.g. for Pascal, when the -fsigned-char option is given. */
2018 fixup_signed_type (type)
2021 int precision = TYPE_PRECISION (type);
2023 /* We can not represent properly constants greater then
2024 2 * HOST_BITS_PER_WIDE_INT, still we need the types
2025 as they are used by i386 vector extensions and friends. */
2026 if (precision > HOST_BITS_PER_WIDE_INT * 2)
2027 precision = HOST_BITS_PER_WIDE_INT * 2;
2029 TYPE_MIN_VALUE (type)
2030 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
2031 ? 0 : (HOST_WIDE_INT) (-1) << (precision - 1)),
2032 (((HOST_WIDE_INT) (-1)
2033 << (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
2034 ? precision - HOST_BITS_PER_WIDE_INT - 1
2036 TYPE_MAX_VALUE (type)
2037 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
2038 ? -1 : ((HOST_WIDE_INT) 1 << (precision - 1)) - 1),
2039 (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
2040 ? (((HOST_WIDE_INT) 1
2041 << (precision - HOST_BITS_PER_WIDE_INT - 1))) - 1
2044 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
2045 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
2047 /* Lay out the type: set its alignment, size, etc. */
2051 /* Set the extreme values of TYPE based on its precision in bits,
2052 then lay it out. This is used both in `make_unsigned_type'
2053 and for enumeral types. */
2056 fixup_unsigned_type (type)
2059 int precision = TYPE_PRECISION (type);
2061 /* We can not represent properly constants greater then
2062 2 * HOST_BITS_PER_WIDE_INT, still we need the types
2063 as they are used by i386 vector extensions and friends. */
2064 if (precision > HOST_BITS_PER_WIDE_INT * 2)
2065 precision = HOST_BITS_PER_WIDE_INT * 2;
2067 TYPE_MIN_VALUE (type) = build_int_2 (0, 0);
2068 TYPE_MAX_VALUE (type)
2069 = build_int_2 (precision - HOST_BITS_PER_WIDE_INT >= 0
2070 ? -1 : ((HOST_WIDE_INT) 1 << precision) - 1,
2071 precision - HOST_BITS_PER_WIDE_INT > 0
2072 ? ((unsigned HOST_WIDE_INT) ~0
2073 >> (HOST_BITS_PER_WIDE_INT
2074 - (precision - HOST_BITS_PER_WIDE_INT)))
2076 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
2077 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
2079 /* Lay out the type: set its alignment, size, etc. */
2083 /* Find the best machine mode to use when referencing a bit field of length
2084 BITSIZE bits starting at BITPOS.
2086 The underlying object is known to be aligned to a boundary of ALIGN bits.
2087 If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
2088 larger than LARGEST_MODE (usually SImode).
2090 If no mode meets all these conditions, we return VOIDmode. Otherwise, if
2091 VOLATILEP is true or SLOW_BYTE_ACCESS is false, we return the smallest
2092 mode meeting these conditions.
2094 Otherwise (VOLATILEP is false and SLOW_BYTE_ACCESS is true), we return
2095 the largest mode (but a mode no wider than UNITS_PER_WORD) that meets
2096 all the conditions. */
2099 get_best_mode (bitsize, bitpos, align, largest_mode, volatilep)
2100 int bitsize, bitpos;
2102 enum machine_mode largest_mode;
2105 enum machine_mode mode;
2106 unsigned int unit = 0;
2108 /* Find the narrowest integer mode that contains the bit field. */
2109 for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
2110 mode = GET_MODE_WIDER_MODE (mode))
2112 unit = GET_MODE_BITSIZE (mode);
2113 if ((bitpos % unit) + bitsize <= unit)
2117 if (mode == VOIDmode
2118 /* It is tempting to omit the following line
2119 if STRICT_ALIGNMENT is true.
2120 But that is incorrect, since if the bitfield uses part of 3 bytes
2121 and we use a 4-byte mode, we could get a spurious segv
2122 if the extra 4th byte is past the end of memory.
2123 (Though at least one Unix compiler ignores this problem:
2124 that on the Sequent 386 machine. */
2125 || MIN (unit, BIGGEST_ALIGNMENT) > align
2126 || (largest_mode != VOIDmode && unit > GET_MODE_BITSIZE (largest_mode)))
2129 if (SLOW_BYTE_ACCESS && ! volatilep)
2131 enum machine_mode wide_mode = VOIDmode, tmode;
2133 for (tmode = GET_CLASS_NARROWEST_MODE (MODE_INT); tmode != VOIDmode;
2134 tmode = GET_MODE_WIDER_MODE (tmode))
2136 unit = GET_MODE_BITSIZE (tmode);
2137 if (bitpos / unit == (bitpos + bitsize - 1) / unit
2138 && unit <= BITS_PER_WORD
2139 && unit <= MIN (align, BIGGEST_ALIGNMENT)
2140 && (largest_mode == VOIDmode
2141 || unit <= GET_MODE_BITSIZE (largest_mode)))
2145 if (wide_mode != VOIDmode)
2152 #include "gt-stor-layout.h"