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 (record_layout_info);
63 static void finalize_type_size (tree);
64 static void place_union_field (record_layout_info, tree);
65 #if defined (PCC_BITFIELD_TYPE_MATTERS) || defined (BITFIELD_NBYTES_LIMITED)
66 static int excess_unit_span (HOST_WIDE_INT, HOST_WIDE_INT, HOST_WIDE_INT,
69 static unsigned int update_alignment_for_field (record_layout_info, tree,
71 extern void debug_rli (record_layout_info);
73 /* SAVE_EXPRs for sizes of types and decls, waiting to be expanded. */
75 static GTY(()) tree pending_sizes;
77 /* Nonzero means cannot safely call expand_expr now,
78 so put variable sizes onto `pending_sizes' instead. */
80 int immediate_size_expand;
82 /* Show that REFERENCE_TYPES are internal and should be Pmode. Called only
86 internal_reference_types (void)
88 reference_types_internal = 1;
91 /* Get a list of all the objects put on the pending sizes list. */
94 get_pending_sizes (void)
96 tree chain = pending_sizes;
99 /* Put each SAVE_EXPR into the current function. */
100 for (t = chain; t; t = TREE_CHAIN (t))
101 SAVE_EXPR_CONTEXT (TREE_VALUE (t)) = current_function_decl;
107 /* Return nonzero if EXPR is present on the pending sizes list. */
110 is_pending_size (tree expr)
114 for (t = pending_sizes; t; t = TREE_CHAIN (t))
115 if (TREE_VALUE (t) == expr)
120 /* Add EXPR to the pending sizes list. */
123 put_pending_size (tree expr)
125 /* Strip any simple arithmetic from EXPR to see if it has an underlying
127 expr = skip_simple_arithmetic (expr);
129 if (TREE_CODE (expr) == SAVE_EXPR)
130 pending_sizes = tree_cons (NULL_TREE, expr, pending_sizes);
133 /* Put a chain of objects into the pending sizes list, which must be
137 put_pending_sizes (tree chain)
142 pending_sizes = chain;
145 /* Given a size SIZE that may not be a constant, return a SAVE_EXPR
146 to serve as the actual size-expression for a type or decl. */
149 variable_size (tree size)
153 /* If the language-processor is to take responsibility for variable-sized
154 items (e.g., languages which have elaboration procedures like Ada),
155 just return SIZE unchanged. Likewise for self-referential sizes and
157 if (TREE_CONSTANT (size)
158 || (*lang_hooks.decls.global_bindings_p) () < 0
159 || CONTAINS_PLACEHOLDER_P (size))
162 if (TREE_CODE (size) == MINUS_EXPR && integer_onep (TREE_OPERAND (size, 1)))
163 /* If this is the upper bound of a C array, leave the minus 1 outside
164 the SAVE_EXPR so it can be folded away. */
165 TREE_OPERAND (size, 0) = save = save_expr (TREE_OPERAND (size, 0));
167 size = save = save_expr (size);
169 /* If an array with a variable number of elements is declared, and
170 the elements require destruction, we will emit a cleanup for the
171 array. That cleanup is run both on normal exit from the block
172 and in the exception-handler for the block. Normally, when code
173 is used in both ordinary code and in an exception handler it is
174 `unsaved', i.e., all SAVE_EXPRs are recalculated. However, we do
175 not wish to do that here; the array-size is the same in both
177 if (TREE_CODE (save) == SAVE_EXPR)
178 SAVE_EXPR_PERSISTENT_P (save) = 1;
180 if ((*lang_hooks.decls.global_bindings_p) ())
182 if (TREE_CONSTANT (size))
183 error ("type size can't be explicitly evaluated");
185 error ("variable-size type declared outside of any function");
187 return size_one_node;
190 if (immediate_size_expand)
191 expand_expr (save, const0_rtx, VOIDmode, 0);
192 else if (cfun != 0 && cfun->x_dont_save_pending_sizes_p)
193 /* The front-end doesn't want us to keep a list of the expressions
194 that determine sizes for variable size objects. */
197 put_pending_size (save);
202 #ifndef MAX_FIXED_MODE_SIZE
203 #define MAX_FIXED_MODE_SIZE GET_MODE_BITSIZE (DImode)
206 /* Return the machine mode to use for a nonscalar of SIZE bits.
207 The mode must be in class CLASS, and have exactly that many bits.
208 If LIMIT is nonzero, modes of wider than MAX_FIXED_MODE_SIZE will not
212 mode_for_size (unsigned int size, enum mode_class class, int limit)
214 enum machine_mode mode;
216 if (limit && size > MAX_FIXED_MODE_SIZE)
219 /* Get the first mode which has this size, in the specified class. */
220 for (mode = GET_CLASS_NARROWEST_MODE (class); mode != VOIDmode;
221 mode = GET_MODE_WIDER_MODE (mode))
222 if (GET_MODE_BITSIZE (mode) == size)
228 /* Similar, except passed a tree node. */
231 mode_for_size_tree (tree size, enum mode_class class, int limit)
233 if (TREE_CODE (size) != INTEGER_CST
234 || TREE_OVERFLOW (size)
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_low_cst (size, 1), 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 (unsigned int size, enum mode_class class)
250 enum machine_mode mode;
252 /* Get the first mode which has at least this size, in the
254 for (mode = GET_CLASS_NARROWEST_MODE (class); mode != VOIDmode;
255 mode = GET_MODE_WIDER_MODE (mode))
256 if (GET_MODE_BITSIZE (mode) >= size)
262 /* Find an integer mode of the exact same size, or BLKmode on failure. */
265 int_mode_for_mode (enum machine_mode mode)
267 switch (GET_MODE_CLASS (mode))
270 case MODE_PARTIAL_INT:
273 case MODE_COMPLEX_INT:
274 case MODE_COMPLEX_FLOAT:
276 case MODE_VECTOR_INT:
277 case MODE_VECTOR_FLOAT:
278 mode = mode_for_size (GET_MODE_BITSIZE (mode), MODE_INT, 0);
285 /* ... fall through ... */
295 /* Return the alignment of MODE. This will be bounded by 1 and
296 BIGGEST_ALIGNMENT. */
299 get_mode_alignment (enum machine_mode mode)
301 unsigned int alignment;
303 if (GET_MODE_CLASS (mode) == MODE_COMPLEX_FLOAT
304 || GET_MODE_CLASS (mode) == MODE_COMPLEX_INT)
305 alignment = GET_MODE_UNIT_SIZE (mode);
307 alignment = GET_MODE_SIZE (mode);
309 /* Extract the LSB of the size. */
310 alignment = alignment & -alignment;
311 alignment *= BITS_PER_UNIT;
313 alignment = MIN (BIGGEST_ALIGNMENT, MAX (1, alignment));
317 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
318 This can only be applied to objects of a sizetype. */
321 round_up (tree value, int divisor)
323 tree arg = size_int_type (divisor, TREE_TYPE (value));
325 return size_binop (MULT_EXPR, size_binop (CEIL_DIV_EXPR, value, arg), arg);
328 /* Likewise, but round down. */
331 round_down (tree value, int divisor)
333 tree arg = size_int_type (divisor, TREE_TYPE (value));
335 return size_binop (MULT_EXPR, size_binop (FLOOR_DIV_EXPR, value, arg), arg);
338 /* Subroutine of layout_decl: Force alignment required for the data type.
339 But if the decl itself wants greater alignment, don't override that. */
342 do_type_align (tree type, tree decl)
344 if (TYPE_ALIGN (type) > DECL_ALIGN (decl))
346 DECL_ALIGN (decl) = TYPE_ALIGN (type);
347 DECL_USER_ALIGN (decl) = TYPE_USER_ALIGN (type);
351 /* Set the size, mode and alignment of a ..._DECL node.
352 TYPE_DECL does need this for C++.
353 Note that LABEL_DECL and CONST_DECL nodes do not need this,
354 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
355 Don't call layout_decl for them.
357 KNOWN_ALIGN is the amount of alignment we can assume this
358 decl has with no special effort. It is relevant only for FIELD_DECLs
359 and depends on the previous fields.
360 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
361 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
362 the record will be aligned to suit. */
365 layout_decl (tree decl, unsigned int known_align)
367 tree type = TREE_TYPE (decl);
368 enum tree_code code = TREE_CODE (decl);
371 if (code == CONST_DECL)
373 else if (code != VAR_DECL && code != PARM_DECL && code != RESULT_DECL
374 && code != TYPE_DECL && code != FIELD_DECL)
377 rtl = DECL_RTL_IF_SET (decl);
379 if (type == error_mark_node)
380 type = void_type_node;
382 /* Usually the size and mode come from the data type without change,
383 however, the front-end may set the explicit width of the field, so its
384 size may not be the same as the size of its type. This happens with
385 bitfields, of course (an `int' bitfield may be only 2 bits, say), but it
386 also happens with other fields. For example, the C++ front-end creates
387 zero-sized fields corresponding to empty base classes, and depends on
388 layout_type setting DECL_FIELD_BITPOS correctly for the field. Set the
389 size in bytes from the size in bits. If we have already set the mode,
390 don't set it again since we can be called twice for FIELD_DECLs. */
392 TREE_UNSIGNED (decl) = TREE_UNSIGNED (type);
393 if (DECL_MODE (decl) == VOIDmode)
394 DECL_MODE (decl) = TYPE_MODE (type);
396 if (DECL_SIZE (decl) == 0)
398 DECL_SIZE (decl) = TYPE_SIZE (type);
399 DECL_SIZE_UNIT (decl) = TYPE_SIZE_UNIT (type);
401 else if (DECL_SIZE_UNIT (decl) == 0)
402 DECL_SIZE_UNIT (decl)
403 = convert (sizetype, size_binop (CEIL_DIV_EXPR, DECL_SIZE (decl),
406 if (code != FIELD_DECL)
407 /* For non-fields, update the alignment from the type. */
408 do_type_align (type, decl);
410 /* For fields, it's a bit more complicated... */
412 if (DECL_BIT_FIELD (decl))
414 DECL_BIT_FIELD_TYPE (decl) = type;
416 /* A zero-length bit-field affects the alignment of the next
418 if (integer_zerop (DECL_SIZE (decl))
419 && ! DECL_PACKED (decl)
420 && ! (*targetm.ms_bitfield_layout_p) (DECL_FIELD_CONTEXT (decl)))
422 #ifdef PCC_BITFIELD_TYPE_MATTERS
423 if (PCC_BITFIELD_TYPE_MATTERS)
424 do_type_align (type, decl);
428 #ifdef EMPTY_FIELD_BOUNDARY
429 if (EMPTY_FIELD_BOUNDARY > DECL_ALIGN (decl))
431 DECL_ALIGN (decl) = EMPTY_FIELD_BOUNDARY;
432 DECL_USER_ALIGN (decl) = 0;
438 /* See if we can use an ordinary integer mode for a bit-field.
439 Conditions are: a fixed size that is correct for another mode
440 and occupying a complete byte or bytes on proper boundary. */
441 if (TYPE_SIZE (type) != 0
442 && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
443 && GET_MODE_CLASS (TYPE_MODE (type)) == MODE_INT)
445 enum machine_mode xmode
446 = mode_for_size_tree (DECL_SIZE (decl), MODE_INT, 1);
448 if (xmode != BLKmode && known_align >= GET_MODE_ALIGNMENT (xmode))
450 DECL_ALIGN (decl) = MAX (GET_MODE_ALIGNMENT (xmode),
452 DECL_MODE (decl) = xmode;
453 DECL_BIT_FIELD (decl) = 0;
457 /* Turn off DECL_BIT_FIELD if we won't need it set. */
458 if (TYPE_MODE (type) == BLKmode && DECL_MODE (decl) == BLKmode
459 && known_align >= TYPE_ALIGN (type)
460 && DECL_ALIGN (decl) >= TYPE_ALIGN (type))
461 DECL_BIT_FIELD (decl) = 0;
463 else if (DECL_PACKED (decl) && DECL_USER_ALIGN (decl))
464 /* Don't touch DECL_ALIGN. For other packed fields, go ahead and
465 round up; we'll reduce it again below. */;
467 do_type_align (type, decl);
469 /* If the field is of variable size, we can't misalign it since we
470 have no way to make a temporary to align the result. But this
471 isn't an issue if the decl is not addressable. Likewise if it
472 is of unknown size. */
473 if (DECL_PACKED (decl)
474 && !DECL_USER_ALIGN (decl)
475 && (DECL_NONADDRESSABLE_P (decl)
476 || DECL_SIZE_UNIT (decl) == 0
477 || TREE_CODE (DECL_SIZE_UNIT (decl)) == INTEGER_CST))
478 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), BITS_PER_UNIT);
480 /* Should this be controlled by DECL_USER_ALIGN, too? */
481 if (maximum_field_alignment != 0)
482 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), maximum_field_alignment);
483 if (! DECL_USER_ALIGN (decl))
485 /* Some targets (i.e. i386, VMS) limit struct field alignment
486 to a lower boundary than alignment of variables unless
487 it was overridden by attribute aligned. */
488 #ifdef BIGGEST_FIELD_ALIGNMENT
490 = MIN (DECL_ALIGN (decl), (unsigned) BIGGEST_FIELD_ALIGNMENT);
492 #ifdef ADJUST_FIELD_ALIGN
493 DECL_ALIGN (decl) = ADJUST_FIELD_ALIGN (decl, DECL_ALIGN (decl));
498 /* Evaluate nonconstant size only once, either now or as soon as safe. */
499 if (DECL_SIZE (decl) != 0 && TREE_CODE (DECL_SIZE (decl)) != INTEGER_CST)
500 DECL_SIZE (decl) = variable_size (DECL_SIZE (decl));
501 if (DECL_SIZE_UNIT (decl) != 0
502 && TREE_CODE (DECL_SIZE_UNIT (decl)) != INTEGER_CST)
503 DECL_SIZE_UNIT (decl) = variable_size (DECL_SIZE_UNIT (decl));
505 /* If requested, warn about definitions of large data objects. */
507 && (code == VAR_DECL || code == PARM_DECL)
508 && ! DECL_EXTERNAL (decl))
510 tree size = DECL_SIZE_UNIT (decl);
512 if (size != 0 && TREE_CODE (size) == INTEGER_CST
513 && compare_tree_int (size, larger_than_size) > 0)
515 int size_as_int = TREE_INT_CST_LOW (size);
517 if (compare_tree_int (size, size_as_int) == 0)
518 warning_with_decl (decl, "size of `%s' is %d bytes", size_as_int);
520 warning_with_decl (decl, "size of `%s' is larger than %d bytes",
525 /* If the RTL was already set, update its mode and mem attributes. */
528 PUT_MODE (rtl, DECL_MODE (decl));
529 SET_DECL_RTL (decl, 0);
530 set_mem_attributes (rtl, decl, 1);
531 SET_DECL_RTL (decl, rtl);
535 /* Hook for a front-end function that can modify the record layout as needed
536 immediately before it is finalized. */
538 void (*lang_adjust_rli) (record_layout_info) = 0;
541 set_lang_adjust_rli (void (*f) (record_layout_info))
546 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
547 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
548 is to be passed to all other layout functions for this record. It is the
549 responsibility of the caller to call `free' for the storage returned.
550 Note that garbage collection is not permitted until we finish laying
554 start_record_layout (tree t)
556 record_layout_info rli
557 = (record_layout_info) xmalloc (sizeof (struct record_layout_info_s));
561 /* If the type has a minimum specified alignment (via an attribute
562 declaration, for example) use it -- otherwise, start with a
563 one-byte alignment. */
564 rli->record_align = MAX (BITS_PER_UNIT, TYPE_ALIGN (t));
565 rli->unpacked_align = rli->record_align;
566 rli->offset_align = MAX (rli->record_align, BIGGEST_ALIGNMENT);
568 #ifdef STRUCTURE_SIZE_BOUNDARY
569 /* Packed structures don't need to have minimum size. */
570 if (! TYPE_PACKED (t))
571 rli->record_align = MAX (rli->record_align, (unsigned) STRUCTURE_SIZE_BOUNDARY);
574 rli->offset = size_zero_node;
575 rli->bitpos = bitsize_zero_node;
577 rli->pending_statics = 0;
578 rli->packed_maybe_necessary = 0;
583 /* These four routines perform computations that convert between
584 the offset/bitpos forms and byte and bit offsets. */
587 bit_from_pos (tree offset, tree bitpos)
589 return size_binop (PLUS_EXPR, bitpos,
590 size_binop (MULT_EXPR, convert (bitsizetype, offset),
595 byte_from_pos (tree offset, tree bitpos)
597 return size_binop (PLUS_EXPR, offset,
599 size_binop (TRUNC_DIV_EXPR, bitpos,
600 bitsize_unit_node)));
604 pos_from_bit (tree *poffset, tree *pbitpos, unsigned int off_align,
607 *poffset = size_binop (MULT_EXPR,
609 size_binop (FLOOR_DIV_EXPR, pos,
610 bitsize_int (off_align))),
611 size_int (off_align / BITS_PER_UNIT));
612 *pbitpos = size_binop (FLOOR_MOD_EXPR, pos, bitsize_int (off_align));
615 /* Given a pointer to bit and byte offsets and an offset alignment,
616 normalize the offsets so they are within the alignment. */
619 normalize_offset (tree *poffset, tree *pbitpos, unsigned int off_align)
621 /* If the bit position is now larger than it should be, adjust it
623 if (compare_tree_int (*pbitpos, off_align) >= 0)
625 tree extra_aligns = size_binop (FLOOR_DIV_EXPR, *pbitpos,
626 bitsize_int (off_align));
629 = size_binop (PLUS_EXPR, *poffset,
630 size_binop (MULT_EXPR, convert (sizetype, extra_aligns),
631 size_int (off_align / BITS_PER_UNIT)));
634 = size_binop (FLOOR_MOD_EXPR, *pbitpos, bitsize_int (off_align));
638 /* Print debugging information about the information in RLI. */
641 debug_rli (record_layout_info rli)
643 print_node_brief (stderr, "type", rli->t, 0);
644 print_node_brief (stderr, "\noffset", rli->offset, 0);
645 print_node_brief (stderr, " bitpos", rli->bitpos, 0);
647 fprintf (stderr, "\naligns: rec = %u, unpack = %u, off = %u\n",
648 rli->record_align, rli->unpacked_align,
650 if (rli->packed_maybe_necessary)
651 fprintf (stderr, "packed may be necessary\n");
653 if (rli->pending_statics)
655 fprintf (stderr, "pending statics:\n");
656 debug_tree (rli->pending_statics);
660 /* Given an RLI with a possibly-incremented BITPOS, adjust OFFSET and
661 BITPOS if necessary to keep BITPOS below OFFSET_ALIGN. */
664 normalize_rli (record_layout_info rli)
666 normalize_offset (&rli->offset, &rli->bitpos, rli->offset_align);
669 /* Returns the size in bytes allocated so far. */
672 rli_size_unit_so_far (record_layout_info rli)
674 return byte_from_pos (rli->offset, rli->bitpos);
677 /* Returns the size in bits allocated so far. */
680 rli_size_so_far (record_layout_info rli)
682 return bit_from_pos (rli->offset, rli->bitpos);
685 /* FIELD is about to be added to RLI->T. The alignment (in bits) of
686 the next available location is given by KNOWN_ALIGN. Update the
687 variable alignment fields in RLI, and return the alignment to give
691 update_alignment_for_field (record_layout_info rli, tree field,
692 unsigned int known_align)
694 /* The alignment required for FIELD. */
695 unsigned int desired_align;
696 /* The type of this field. */
697 tree type = TREE_TYPE (field);
698 /* True if the field was explicitly aligned by the user. */
702 /* Lay out the field so we know what alignment it needs. */
703 layout_decl (field, known_align);
704 desired_align = DECL_ALIGN (field);
705 user_align = DECL_USER_ALIGN (field);
707 is_bitfield = (type != error_mark_node
708 && DECL_BIT_FIELD_TYPE (field)
709 && ! integer_zerop (TYPE_SIZE (type)));
711 /* Record must have at least as much alignment as any field.
712 Otherwise, the alignment of the field within the record is
714 if (is_bitfield && (* targetm.ms_bitfield_layout_p) (rli->t))
716 /* Here, the alignment of the underlying type of a bitfield can
717 affect the alignment of a record; even a zero-sized field
718 can do this. The alignment should be to the alignment of
719 the type, except that for zero-size bitfields this only
720 applies if there was an immediately prior, nonzero-size
721 bitfield. (That's the way it is, experimentally.) */
722 if (! integer_zerop (DECL_SIZE (field))
723 ? ! DECL_PACKED (field)
725 && DECL_BIT_FIELD_TYPE (rli->prev_field)
726 && ! integer_zerop (DECL_SIZE (rli->prev_field))))
728 unsigned int type_align = TYPE_ALIGN (type);
729 type_align = MAX (type_align, desired_align);
730 if (maximum_field_alignment != 0)
731 type_align = MIN (type_align, maximum_field_alignment);
732 rli->record_align = MAX (rli->record_align, type_align);
733 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
736 #ifdef PCC_BITFIELD_TYPE_MATTERS
737 else if (is_bitfield && PCC_BITFIELD_TYPE_MATTERS)
739 /* Named bit-fields cause the entire structure to have the
740 alignment implied by their type. */
741 if (DECL_NAME (field) != 0)
743 unsigned int type_align = TYPE_ALIGN (type);
745 #ifdef ADJUST_FIELD_ALIGN
746 if (! TYPE_USER_ALIGN (type))
747 type_align = ADJUST_FIELD_ALIGN (field, type_align);
750 if (maximum_field_alignment != 0)
751 type_align = MIN (type_align, maximum_field_alignment);
752 else if (DECL_PACKED (field))
753 type_align = MIN (type_align, BITS_PER_UNIT);
755 /* The alignment of the record is increased to the maximum
756 of the current alignment, the alignment indicated on the
757 field (i.e., the alignment specified by an __aligned__
758 attribute), and the alignment indicated by the type of
760 rli->record_align = MAX (rli->record_align, desired_align);
761 rli->record_align = MAX (rli->record_align, type_align);
764 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
765 user_align |= TYPE_USER_ALIGN (type);
771 rli->record_align = MAX (rli->record_align, desired_align);
772 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
775 TYPE_USER_ALIGN (rli->t) |= user_align;
777 return desired_align;
780 /* Called from place_field to handle unions. */
783 place_union_field (record_layout_info rli, tree field)
785 update_alignment_for_field (rli, field, /*known_align=*/0);
787 DECL_FIELD_OFFSET (field) = size_zero_node;
788 DECL_FIELD_BIT_OFFSET (field) = bitsize_zero_node;
789 SET_DECL_OFFSET_ALIGN (field, BIGGEST_ALIGNMENT);
791 /* We assume the union's size will be a multiple of a byte so we don't
792 bother with BITPOS. */
793 if (TREE_CODE (rli->t) == UNION_TYPE)
794 rli->offset = size_binop (MAX_EXPR, rli->offset, DECL_SIZE_UNIT (field));
795 else if (TREE_CODE (rli->t) == QUAL_UNION_TYPE)
796 rli->offset = fold (build (COND_EXPR, sizetype,
797 DECL_QUALIFIER (field),
798 DECL_SIZE_UNIT (field), rli->offset));
801 #if defined (PCC_BITFIELD_TYPE_MATTERS) || defined (BITFIELD_NBYTES_LIMITED)
802 /* A bitfield of SIZE with a required access alignment of ALIGN is allocated
803 at BYTE_OFFSET / BIT_OFFSET. Return nonzero if the field would span more
804 units of alignment than the underlying TYPE. */
806 excess_unit_span (HOST_WIDE_INT byte_offset, HOST_WIDE_INT bit_offset,
807 HOST_WIDE_INT size, HOST_WIDE_INT align, tree type)
809 /* Note that the calculation of OFFSET might overflow; we calculate it so
810 that we still get the right result as long as ALIGN is a power of two. */
811 unsigned HOST_WIDE_INT offset = byte_offset * BITS_PER_UNIT + bit_offset;
813 offset = offset % align;
814 return ((offset + size + align - 1) / align
815 > ((unsigned HOST_WIDE_INT) tree_low_cst (TYPE_SIZE (type), 1)
820 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
821 is a FIELD_DECL to be added after those fields already present in
822 T. (FIELD is not actually added to the TYPE_FIELDS list here;
823 callers that desire that behavior must manually perform that step.) */
826 place_field (record_layout_info rli, tree field)
828 /* The alignment required for FIELD. */
829 unsigned int desired_align;
830 /* The alignment FIELD would have if we just dropped it into the
831 record as it presently stands. */
832 unsigned int known_align;
833 unsigned int actual_align;
834 /* The type of this field. */
835 tree type = TREE_TYPE (field);
837 if (TREE_CODE (field) == ERROR_MARK || TREE_CODE (type) == ERROR_MARK)
840 /* If FIELD is static, then treat it like a separate variable, not
841 really like a structure field. If it is a FUNCTION_DECL, it's a
842 method. In both cases, all we do is lay out the decl, and we do
843 it *after* the record is laid out. */
844 if (TREE_CODE (field) == VAR_DECL)
846 rli->pending_statics = tree_cons (NULL_TREE, field,
847 rli->pending_statics);
851 /* Enumerators and enum types which are local to this class need not
852 be laid out. Likewise for initialized constant fields. */
853 else if (TREE_CODE (field) != FIELD_DECL)
856 /* Unions are laid out very differently than records, so split
857 that code off to another function. */
858 else if (TREE_CODE (rli->t) != RECORD_TYPE)
860 place_union_field (rli, field);
864 /* Work out the known alignment so far. Note that A & (-A) is the
865 value of the least-significant bit in A that is one. */
866 if (! integer_zerop (rli->bitpos))
867 known_align = (tree_low_cst (rli->bitpos, 1)
868 & - tree_low_cst (rli->bitpos, 1));
869 else if (integer_zerop (rli->offset))
870 known_align = BIGGEST_ALIGNMENT;
871 else if (host_integerp (rli->offset, 1))
872 known_align = (BITS_PER_UNIT
873 * (tree_low_cst (rli->offset, 1)
874 & - tree_low_cst (rli->offset, 1)));
876 known_align = rli->offset_align;
878 desired_align = update_alignment_for_field (rli, field, known_align);
880 if (warn_packed && DECL_PACKED (field))
882 if (known_align >= TYPE_ALIGN (type))
884 if (TYPE_ALIGN (type) > desired_align)
886 if (STRICT_ALIGNMENT)
887 warning_with_decl (field, "packed attribute causes inefficient alignment for `%s'");
889 warning_with_decl (field, "packed attribute is unnecessary for `%s'");
893 rli->packed_maybe_necessary = 1;
896 /* Does this field automatically have alignment it needs by virtue
897 of the fields that precede it and the record's own alignment? */
898 if (known_align < desired_align)
900 /* No, we need to skip space before this field.
901 Bump the cumulative size to multiple of field alignment. */
904 warning_with_decl (field, "padding struct to align `%s'");
906 /* If the alignment is still within offset_align, just align
908 if (desired_align < rli->offset_align)
909 rli->bitpos = round_up (rli->bitpos, desired_align);
912 /* First adjust OFFSET by the partial bits, then align. */
914 = size_binop (PLUS_EXPR, rli->offset,
916 size_binop (CEIL_DIV_EXPR, rli->bitpos,
917 bitsize_unit_node)));
918 rli->bitpos = bitsize_zero_node;
920 rli->offset = round_up (rli->offset, desired_align / BITS_PER_UNIT);
923 if (! TREE_CONSTANT (rli->offset))
924 rli->offset_align = desired_align;
928 /* Handle compatibility with PCC. Note that if the record has any
929 variable-sized fields, we need not worry about compatibility. */
930 #ifdef PCC_BITFIELD_TYPE_MATTERS
931 if (PCC_BITFIELD_TYPE_MATTERS
932 && ! (* targetm.ms_bitfield_layout_p) (rli->t)
933 && TREE_CODE (field) == FIELD_DECL
934 && type != error_mark_node
935 && DECL_BIT_FIELD (field)
936 && ! DECL_PACKED (field)
937 && maximum_field_alignment == 0
938 && ! integer_zerop (DECL_SIZE (field))
939 && host_integerp (DECL_SIZE (field), 1)
940 && host_integerp (rli->offset, 1)
941 && host_integerp (TYPE_SIZE (type), 1))
943 unsigned int type_align = TYPE_ALIGN (type);
944 tree dsize = DECL_SIZE (field);
945 HOST_WIDE_INT field_size = tree_low_cst (dsize, 1);
946 HOST_WIDE_INT offset = tree_low_cst (rli->offset, 0);
947 HOST_WIDE_INT bit_offset = tree_low_cst (rli->bitpos, 0);
949 #ifdef ADJUST_FIELD_ALIGN
950 if (! TYPE_USER_ALIGN (type))
951 type_align = ADJUST_FIELD_ALIGN (field, type_align);
954 /* A bit field may not span more units of alignment of its type
955 than its type itself. Advance to next boundary if necessary. */
956 if (excess_unit_span (offset, bit_offset, field_size, type_align, type))
957 rli->bitpos = round_up (rli->bitpos, type_align);
959 TYPE_USER_ALIGN (rli->t) |= TYPE_USER_ALIGN (type);
963 #ifdef BITFIELD_NBYTES_LIMITED
964 if (BITFIELD_NBYTES_LIMITED
965 && ! (* targetm.ms_bitfield_layout_p) (rli->t)
966 && TREE_CODE (field) == FIELD_DECL
967 && type != error_mark_node
968 && DECL_BIT_FIELD_TYPE (field)
969 && ! DECL_PACKED (field)
970 && ! integer_zerop (DECL_SIZE (field))
971 && host_integerp (DECL_SIZE (field), 1)
972 && host_integerp (rli->offset, 1)
973 && host_integerp (TYPE_SIZE (type), 1))
975 unsigned int type_align = TYPE_ALIGN (type);
976 tree dsize = DECL_SIZE (field);
977 HOST_WIDE_INT field_size = tree_low_cst (dsize, 1);
978 HOST_WIDE_INT offset = tree_low_cst (rli->offset, 0);
979 HOST_WIDE_INT bit_offset = tree_low_cst (rli->bitpos, 0);
981 #ifdef ADJUST_FIELD_ALIGN
982 if (! TYPE_USER_ALIGN (type))
983 type_align = ADJUST_FIELD_ALIGN (field, type_align);
986 if (maximum_field_alignment != 0)
987 type_align = MIN (type_align, maximum_field_alignment);
988 /* ??? This test is opposite the test in the containing if
989 statement, so this code is unreachable currently. */
990 else if (DECL_PACKED (field))
991 type_align = MIN (type_align, BITS_PER_UNIT);
993 /* A bit field may not span the unit of alignment of its type.
994 Advance to next boundary if necessary. */
995 if (excess_unit_span (offset, bit_offset, field_size, type_align, type))
996 rli->bitpos = round_up (rli->bitpos, type_align);
998 TYPE_USER_ALIGN (rli->t) |= TYPE_USER_ALIGN (type);
1002 /* See the docs for TARGET_MS_BITFIELD_LAYOUT_P for details.
1004 When a bit field is inserted into a packed record, the whole
1005 size of the underlying type is used by one or more same-size
1006 adjacent bitfields. (That is, if its long:3, 32 bits is
1007 used in the record, and any additional adjacent long bitfields are
1008 packed into the same chunk of 32 bits. However, if the size
1009 changes, a new field of that size is allocated.) In an unpacked
1010 record, this is the same as using alignment, but not equivalent
1013 Note: for compatibility, we use the type size, not the type alignment
1014 to determine alignment, since that matches the documentation */
1016 if ((* targetm.ms_bitfield_layout_p) (rli->t)
1017 && ((DECL_BIT_FIELD_TYPE (field) && ! DECL_PACKED (field))
1018 || (rli->prev_field && ! DECL_PACKED (rli->prev_field))))
1020 /* At this point, either the prior or current are bitfields,
1021 (possibly both), and we're dealing with MS packing. */
1022 tree prev_saved = rli->prev_field;
1024 /* Is the prior field a bitfield? If so, handle "runs" of same
1025 type size fields. */
1026 if (rli->prev_field /* necessarily a bitfield if it exists. */)
1028 /* If both are bitfields, nonzero, and the same size, this is
1029 the middle of a run. Zero declared size fields are special
1030 and handled as "end of run". (Note: it's nonzero declared
1031 size, but equal type sizes!) (Since we know that both
1032 the current and previous fields are bitfields by the
1033 time we check it, DECL_SIZE must be present for both.) */
1034 if (DECL_BIT_FIELD_TYPE (field)
1035 && !integer_zerop (DECL_SIZE (field))
1036 && !integer_zerop (DECL_SIZE (rli->prev_field))
1037 && host_integerp (DECL_SIZE (rli->prev_field), 0)
1038 && host_integerp (TYPE_SIZE (type), 0)
1039 && simple_cst_equal (TYPE_SIZE (type),
1040 TYPE_SIZE (TREE_TYPE (rli->prev_field))))
1042 /* We're in the middle of a run of equal type size fields; make
1043 sure we realign if we run out of bits. (Not decl size,
1045 HOST_WIDE_INT bitsize = tree_low_cst (DECL_SIZE (field), 0);
1047 if (rli->remaining_in_alignment < bitsize)
1049 /* out of bits; bump up to next 'word'. */
1050 rli->offset = DECL_FIELD_OFFSET (rli->prev_field);
1052 = size_binop (PLUS_EXPR, TYPE_SIZE (type),
1053 DECL_FIELD_BIT_OFFSET (rli->prev_field));
1054 rli->prev_field = field;
1055 rli->remaining_in_alignment
1056 = tree_low_cst (TYPE_SIZE (type), 0);
1059 rli->remaining_in_alignment -= bitsize;
1063 /* End of a run: if leaving a run of bitfields of the same type
1064 size, we have to "use up" the rest of the bits of the type
1067 Compute the new position as the sum of the size for the prior
1068 type and where we first started working on that type.
1069 Note: since the beginning of the field was aligned then
1070 of course the end will be too. No round needed. */
1072 if (!integer_zerop (DECL_SIZE (rli->prev_field)))
1074 tree type_size = TYPE_SIZE (TREE_TYPE (rli->prev_field));
1077 = size_binop (PLUS_EXPR, type_size,
1078 DECL_FIELD_BIT_OFFSET (rli->prev_field));
1081 /* We "use up" size zero fields; the code below should behave
1082 as if the prior field was not a bitfield. */
1085 /* Cause a new bitfield to be captured, either this time (if
1086 currently a bitfield) or next time we see one. */
1087 if (!DECL_BIT_FIELD_TYPE(field)
1088 || integer_zerop (DECL_SIZE (field)))
1089 rli->prev_field = NULL;
1092 normalize_rli (rli);
1095 /* If we're starting a new run of same size type bitfields
1096 (or a run of non-bitfields), set up the "first of the run"
1099 That is, if the current field is not a bitfield, or if there
1100 was a prior bitfield the type sizes differ, or if there wasn't
1101 a prior bitfield the size of the current field is nonzero.
1103 Note: we must be sure to test ONLY the type size if there was
1104 a prior bitfield and ONLY for the current field being zero if
1107 if (!DECL_BIT_FIELD_TYPE (field)
1108 || ( prev_saved != NULL
1109 ? !simple_cst_equal (TYPE_SIZE (type),
1110 TYPE_SIZE (TREE_TYPE (prev_saved)))
1111 : !integer_zerop (DECL_SIZE (field)) ))
1113 /* Never smaller than a byte for compatibility. */
1114 unsigned int type_align = BITS_PER_UNIT;
1116 /* (When not a bitfield), we could be seeing a flex array (with
1117 no DECL_SIZE). Since we won't be using remaining_in_alignment
1118 until we see a bitfield (and come by here again) we just skip
1120 if (DECL_SIZE (field) != NULL
1121 && host_integerp (TYPE_SIZE (TREE_TYPE (field)), 0)
1122 && host_integerp (DECL_SIZE (field), 0))
1123 rli->remaining_in_alignment
1124 = tree_low_cst (TYPE_SIZE (TREE_TYPE(field)), 0)
1125 - tree_low_cst (DECL_SIZE (field), 0);
1127 /* Now align (conventionally) for the new type. */
1128 if (!DECL_PACKED(field))
1129 type_align = MAX(TYPE_ALIGN (type), type_align);
1132 && DECL_BIT_FIELD_TYPE (prev_saved)
1133 /* If the previous bit-field is zero-sized, we've already
1134 accounted for its alignment needs (or ignored it, if
1135 appropriate) while placing it. */
1136 && ! integer_zerop (DECL_SIZE (prev_saved)))
1137 type_align = MAX (type_align,
1138 TYPE_ALIGN (TREE_TYPE (prev_saved)));
1140 if (maximum_field_alignment != 0)
1141 type_align = MIN (type_align, maximum_field_alignment);
1143 rli->bitpos = round_up (rli->bitpos, type_align);
1145 /* If we really aligned, don't allow subsequent bitfields
1147 rli->prev_field = NULL;
1151 /* Offset so far becomes the position of this field after normalizing. */
1152 normalize_rli (rli);
1153 DECL_FIELD_OFFSET (field) = rli->offset;
1154 DECL_FIELD_BIT_OFFSET (field) = rli->bitpos;
1155 SET_DECL_OFFSET_ALIGN (field, rli->offset_align);
1157 /* If this field ended up more aligned than we thought it would be (we
1158 approximate this by seeing if its position changed), lay out the field
1159 again; perhaps we can use an integral mode for it now. */
1160 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field)))
1161 actual_align = (tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1)
1162 & - tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1));
1163 else if (integer_zerop (DECL_FIELD_OFFSET (field)))
1164 actual_align = BIGGEST_ALIGNMENT;
1165 else if (host_integerp (DECL_FIELD_OFFSET (field), 1))
1166 actual_align = (BITS_PER_UNIT
1167 * (tree_low_cst (DECL_FIELD_OFFSET (field), 1)
1168 & - tree_low_cst (DECL_FIELD_OFFSET (field), 1)));
1170 actual_align = DECL_OFFSET_ALIGN (field);
1172 if (known_align != actual_align)
1173 layout_decl (field, actual_align);
1175 /* Only the MS bitfields use this. */
1176 if (rli->prev_field == NULL && DECL_BIT_FIELD_TYPE(field))
1177 rli->prev_field = field;
1179 /* Now add size of this field to the size of the record. If the size is
1180 not constant, treat the field as being a multiple of bytes and just
1181 adjust the offset, resetting the bit position. Otherwise, apportion the
1182 size amongst the bit position and offset. First handle the case of an
1183 unspecified size, which can happen when we have an invalid nested struct
1184 definition, such as struct j { struct j { int i; } }. The error message
1185 is printed in finish_struct. */
1186 if (DECL_SIZE (field) == 0)
1188 else if (TREE_CODE (DECL_SIZE_UNIT (field)) != INTEGER_CST
1189 || TREE_CONSTANT_OVERFLOW (DECL_SIZE_UNIT (field)))
1192 = size_binop (PLUS_EXPR, rli->offset,
1194 size_binop (CEIL_DIV_EXPR, rli->bitpos,
1195 bitsize_unit_node)));
1197 = size_binop (PLUS_EXPR, rli->offset, DECL_SIZE_UNIT (field));
1198 rli->bitpos = bitsize_zero_node;
1199 rli->offset_align = MIN (rli->offset_align, desired_align);
1203 rli->bitpos = size_binop (PLUS_EXPR, rli->bitpos, DECL_SIZE (field));
1204 normalize_rli (rli);
1208 /* Assuming that all the fields have been laid out, this function uses
1209 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
1210 indicated by RLI. */
1213 finalize_record_size (record_layout_info rli)
1215 tree unpadded_size, unpadded_size_unit;
1217 /* Now we want just byte and bit offsets, so set the offset alignment
1218 to be a byte and then normalize. */
1219 rli->offset_align = BITS_PER_UNIT;
1220 normalize_rli (rli);
1222 /* Determine the desired alignment. */
1223 #ifdef ROUND_TYPE_ALIGN
1224 TYPE_ALIGN (rli->t) = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t),
1227 TYPE_ALIGN (rli->t) = MAX (TYPE_ALIGN (rli->t), rli->record_align);
1230 /* Compute the size so far. Be sure to allow for extra bits in the
1231 size in bytes. We have guaranteed above that it will be no more
1232 than a single byte. */
1233 unpadded_size = rli_size_so_far (rli);
1234 unpadded_size_unit = rli_size_unit_so_far (rli);
1235 if (! integer_zerop (rli->bitpos))
1237 = size_binop (PLUS_EXPR, unpadded_size_unit, size_one_node);
1239 /* Round the size up to be a multiple of the required alignment. */
1240 TYPE_SIZE (rli->t) = round_up (unpadded_size, TYPE_ALIGN (rli->t));
1241 TYPE_SIZE_UNIT (rli->t) = round_up (unpadded_size_unit,
1242 TYPE_ALIGN (rli->t) / BITS_PER_UNIT);
1244 if (warn_padded && TREE_CONSTANT (unpadded_size)
1245 && simple_cst_equal (unpadded_size, TYPE_SIZE (rli->t)) == 0)
1246 warning ("padding struct size to alignment boundary");
1248 if (warn_packed && TREE_CODE (rli->t) == RECORD_TYPE
1249 && TYPE_PACKED (rli->t) && ! rli->packed_maybe_necessary
1250 && TREE_CONSTANT (unpadded_size))
1254 #ifdef ROUND_TYPE_ALIGN
1256 = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t), rli->unpacked_align);
1258 rli->unpacked_align = MAX (TYPE_ALIGN (rli->t), rli->unpacked_align);
1261 unpacked_size = round_up (TYPE_SIZE (rli->t), rli->unpacked_align);
1262 if (simple_cst_equal (unpacked_size, TYPE_SIZE (rli->t)))
1264 TYPE_PACKED (rli->t) = 0;
1266 if (TYPE_NAME (rli->t))
1270 if (TREE_CODE (TYPE_NAME (rli->t)) == IDENTIFIER_NODE)
1271 name = IDENTIFIER_POINTER (TYPE_NAME (rli->t));
1273 name = IDENTIFIER_POINTER (DECL_NAME (TYPE_NAME (rli->t)));
1275 if (STRICT_ALIGNMENT)
1276 warning ("packed attribute causes inefficient alignment for `%s'", name);
1278 warning ("packed attribute is unnecessary for `%s'", name);
1282 if (STRICT_ALIGNMENT)
1283 warning ("packed attribute causes inefficient alignment");
1285 warning ("packed attribute is unnecessary");
1291 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
1294 compute_record_mode (tree type)
1297 enum machine_mode mode = VOIDmode;
1299 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
1300 However, if possible, we use a mode that fits in a register
1301 instead, in order to allow for better optimization down the
1303 TYPE_MODE (type) = BLKmode;
1305 if (! host_integerp (TYPE_SIZE (type), 1))
1308 /* A record which has any BLKmode members must itself be
1309 BLKmode; it can't go in a register. Unless the member is
1310 BLKmode only because it isn't aligned. */
1311 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1313 unsigned HOST_WIDE_INT bitpos;
1315 if (TREE_CODE (field) != FIELD_DECL)
1318 if (TREE_CODE (TREE_TYPE (field)) == ERROR_MARK
1319 || (TYPE_MODE (TREE_TYPE (field)) == BLKmode
1320 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field)))
1321 || ! host_integerp (bit_position (field), 1)
1322 || DECL_SIZE (field) == 0
1323 || ! host_integerp (DECL_SIZE (field), 1))
1326 bitpos = int_bit_position (field);
1328 /* Must be BLKmode if any field crosses a word boundary,
1329 since extract_bit_field can't handle that in registers. */
1330 if (bitpos / BITS_PER_WORD
1331 != ((tree_low_cst (DECL_SIZE (field), 1) + bitpos - 1)
1333 /* But there is no problem if the field is entire words
1334 or bigger than a word. */
1335 && ! (tree_low_cst (DECL_SIZE (field), 1) % BITS_PER_WORD == 0
1336 || compare_tree_int (DECL_SIZE (field), BITS_PER_WORD) > 0))
1339 /* If this field is the whole struct, remember its mode so
1340 that, say, we can put a double in a class into a DF
1341 register instead of forcing it to live in the stack. */
1342 if (simple_cst_equal (TYPE_SIZE (type), DECL_SIZE (field)))
1343 mode = DECL_MODE (field);
1345 #ifdef MEMBER_TYPE_FORCES_BLK
1346 /* With some targets, eg. c4x, it is sub-optimal
1347 to access an aligned BLKmode structure as a scalar. */
1349 if (MEMBER_TYPE_FORCES_BLK (field, mode))
1351 #endif /* MEMBER_TYPE_FORCES_BLK */
1354 /* If we only have one real field; use its mode. This only applies to
1355 RECORD_TYPE. This does not apply to unions. */
1356 if (TREE_CODE (type) == RECORD_TYPE && mode != VOIDmode)
1357 TYPE_MODE (type) = mode;
1359 TYPE_MODE (type) = mode_for_size_tree (TYPE_SIZE (type), MODE_INT, 1);
1361 /* If structure's known alignment is less than what the scalar
1362 mode would need, and it matters, then stick with BLKmode. */
1363 if (TYPE_MODE (type) != BLKmode
1365 && ! (TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT
1366 || TYPE_ALIGN (type) >= GET_MODE_ALIGNMENT (TYPE_MODE (type))))
1368 /* If this is the only reason this type is BLKmode, then
1369 don't force containing types to be BLKmode. */
1370 TYPE_NO_FORCE_BLK (type) = 1;
1371 TYPE_MODE (type) = BLKmode;
1375 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1379 finalize_type_size (tree type)
1381 /* Normally, use the alignment corresponding to the mode chosen.
1382 However, where strict alignment is not required, avoid
1383 over-aligning structures, since most compilers do not do this
1386 if (TYPE_MODE (type) != BLKmode && TYPE_MODE (type) != VOIDmode
1387 && (STRICT_ALIGNMENT
1388 || (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE
1389 && TREE_CODE (type) != QUAL_UNION_TYPE
1390 && TREE_CODE (type) != ARRAY_TYPE)))
1392 TYPE_ALIGN (type) = GET_MODE_ALIGNMENT (TYPE_MODE (type));
1393 TYPE_USER_ALIGN (type) = 0;
1396 /* Do machine-dependent extra alignment. */
1397 #ifdef ROUND_TYPE_ALIGN
1399 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (type), BITS_PER_UNIT);
1402 /* If we failed to find a simple way to calculate the unit size
1403 of the type, find it by division. */
1404 if (TYPE_SIZE_UNIT (type) == 0 && TYPE_SIZE (type) != 0)
1405 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1406 result will fit in sizetype. We will get more efficient code using
1407 sizetype, so we force a conversion. */
1408 TYPE_SIZE_UNIT (type)
1409 = convert (sizetype,
1410 size_binop (FLOOR_DIV_EXPR, TYPE_SIZE (type),
1411 bitsize_unit_node));
1413 if (TYPE_SIZE (type) != 0)
1415 TYPE_SIZE (type) = round_up (TYPE_SIZE (type), TYPE_ALIGN (type));
1416 TYPE_SIZE_UNIT (type)
1417 = round_up (TYPE_SIZE_UNIT (type), TYPE_ALIGN (type) / BITS_PER_UNIT);
1420 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1421 if (TYPE_SIZE (type) != 0 && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
1422 TYPE_SIZE (type) = variable_size (TYPE_SIZE (type));
1423 if (TYPE_SIZE_UNIT (type) != 0
1424 && TREE_CODE (TYPE_SIZE_UNIT (type)) != INTEGER_CST)
1425 TYPE_SIZE_UNIT (type) = variable_size (TYPE_SIZE_UNIT (type));
1427 /* Also layout any other variants of the type. */
1428 if (TYPE_NEXT_VARIANT (type)
1429 || type != TYPE_MAIN_VARIANT (type))
1432 /* Record layout info of this variant. */
1433 tree size = TYPE_SIZE (type);
1434 tree size_unit = TYPE_SIZE_UNIT (type);
1435 unsigned int align = TYPE_ALIGN (type);
1436 unsigned int user_align = TYPE_USER_ALIGN (type);
1437 enum machine_mode mode = TYPE_MODE (type);
1439 /* Copy it into all variants. */
1440 for (variant = TYPE_MAIN_VARIANT (type);
1442 variant = TYPE_NEXT_VARIANT (variant))
1444 TYPE_SIZE (variant) = size;
1445 TYPE_SIZE_UNIT (variant) = size_unit;
1446 TYPE_ALIGN (variant) = align;
1447 TYPE_USER_ALIGN (variant) = user_align;
1448 TYPE_MODE (variant) = mode;
1453 /* Do all of the work required to layout the type indicated by RLI,
1454 once the fields have been laid out. This function will call `free'
1455 for RLI, unless FREE_P is false. Passing a value other than false
1456 for FREE_P is bad practice; this option only exists to support the
1460 finish_record_layout (record_layout_info rli, int free_p)
1462 /* Compute the final size. */
1463 finalize_record_size (rli);
1465 /* Compute the TYPE_MODE for the record. */
1466 compute_record_mode (rli->t);
1468 /* Perform any last tweaks to the TYPE_SIZE, etc. */
1469 finalize_type_size (rli->t);
1471 /* Lay out any static members. This is done now because their type
1472 may use the record's type. */
1473 while (rli->pending_statics)
1475 layout_decl (TREE_VALUE (rli->pending_statics), 0);
1476 rli->pending_statics = TREE_CHAIN (rli->pending_statics);
1485 /* Finish processing a builtin RECORD_TYPE type TYPE. It's name is
1486 NAME, its fields are chained in reverse on FIELDS.
1488 If ALIGN_TYPE is non-null, it is given the same alignment as
1492 finish_builtin_struct (tree type, const char *name, tree fields,
1497 for (tail = NULL_TREE; fields; tail = fields, fields = next)
1499 DECL_FIELD_CONTEXT (fields) = type;
1500 next = TREE_CHAIN (fields);
1501 TREE_CHAIN (fields) = tail;
1503 TYPE_FIELDS (type) = tail;
1507 TYPE_ALIGN (type) = TYPE_ALIGN (align_type);
1508 TYPE_USER_ALIGN (type) = TYPE_USER_ALIGN (align_type);
1512 #if 0 /* not yet, should get fixed properly later */
1513 TYPE_NAME (type) = make_type_decl (get_identifier (name), type);
1515 TYPE_NAME (type) = build_decl (TYPE_DECL, get_identifier (name), type);
1517 TYPE_STUB_DECL (type) = TYPE_NAME (type);
1518 layout_decl (TYPE_NAME (type), 0);
1521 /* Calculate the mode, size, and alignment for TYPE.
1522 For an array type, calculate the element separation as well.
1523 Record TYPE on the chain of permanent or temporary types
1524 so that dbxout will find out about it.
1526 TYPE_SIZE of a type is nonzero if the type has been laid out already.
1527 layout_type does nothing on such a type.
1529 If the type is incomplete, its TYPE_SIZE remains zero. */
1532 layout_type (tree type)
1537 /* Do nothing if type has been laid out before. */
1538 if (TYPE_SIZE (type))
1541 switch (TREE_CODE (type))
1544 /* This kind of type is the responsibility
1545 of the language-specific code. */
1548 case BOOLEAN_TYPE: /* Used for Java, Pascal, and Chill. */
1549 if (TYPE_PRECISION (type) == 0)
1550 TYPE_PRECISION (type) = 1; /* default to one byte/boolean. */
1552 /* ... fall through ... */
1557 if (TREE_CODE (TYPE_MIN_VALUE (type)) == INTEGER_CST
1558 && tree_int_cst_sgn (TYPE_MIN_VALUE (type)) >= 0)
1559 TREE_UNSIGNED (type) = 1;
1561 TYPE_MODE (type) = smallest_mode_for_size (TYPE_PRECISION (type),
1563 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1564 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1568 TYPE_MODE (type) = mode_for_size (TYPE_PRECISION (type), MODE_FLOAT, 0);
1569 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1570 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1574 TREE_UNSIGNED (type) = TREE_UNSIGNED (TREE_TYPE (type));
1576 = mode_for_size (2 * TYPE_PRECISION (TREE_TYPE (type)),
1577 (TREE_CODE (TREE_TYPE (type)) == INTEGER_TYPE
1578 ? MODE_COMPLEX_INT : MODE_COMPLEX_FLOAT),
1580 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1581 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1588 subtype = TREE_TYPE (type);
1589 TREE_UNSIGNED (type) = TREE_UNSIGNED (subtype);
1590 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1591 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1596 /* This is an incomplete type and so doesn't have a size. */
1597 TYPE_ALIGN (type) = 1;
1598 TYPE_USER_ALIGN (type) = 0;
1599 TYPE_MODE (type) = VOIDmode;
1603 TYPE_SIZE (type) = bitsize_int (POINTER_SIZE);
1604 TYPE_SIZE_UNIT (type) = size_int (POINTER_SIZE / BITS_PER_UNIT);
1605 /* A pointer might be MODE_PARTIAL_INT,
1606 but ptrdiff_t must be integral. */
1607 TYPE_MODE (type) = mode_for_size (POINTER_SIZE, MODE_INT, 0);
1612 TYPE_MODE (type) = mode_for_size (2 * POINTER_SIZE, MODE_INT, 0);
1613 TYPE_SIZE (type) = bitsize_int (2 * POINTER_SIZE);
1614 TYPE_SIZE_UNIT (type) = size_int ((2 * POINTER_SIZE) / BITS_PER_UNIT);
1618 case REFERENCE_TYPE:
1621 enum machine_mode mode = ((TREE_CODE (type) == REFERENCE_TYPE
1622 && reference_types_internal)
1623 ? Pmode : TYPE_MODE (type));
1625 int nbits = GET_MODE_BITSIZE (mode);
1627 TYPE_SIZE (type) = bitsize_int (nbits);
1628 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (mode));
1629 TREE_UNSIGNED (type) = 1;
1630 TYPE_PRECISION (type) = nbits;
1636 tree index = TYPE_DOMAIN (type);
1637 tree element = TREE_TYPE (type);
1639 build_pointer_type (element);
1641 /* We need to know both bounds in order to compute the size. */
1642 if (index && TYPE_MAX_VALUE (index) && TYPE_MIN_VALUE (index)
1643 && TYPE_SIZE (element))
1645 tree ub = TYPE_MAX_VALUE (index);
1646 tree lb = TYPE_MIN_VALUE (index);
1650 /* The initial subtraction should happen in the original type so
1651 that (possible) negative values are handled appropriately. */
1652 length = size_binop (PLUS_EXPR, size_one_node,
1654 fold (build (MINUS_EXPR,
1658 /* Special handling for arrays of bits (for Chill). */
1659 element_size = TYPE_SIZE (element);
1660 if (TYPE_PACKED (type) && INTEGRAL_TYPE_P (element)
1661 && (integer_zerop (TYPE_MAX_VALUE (element))
1662 || integer_onep (TYPE_MAX_VALUE (element)))
1663 && host_integerp (TYPE_MIN_VALUE (element), 1))
1665 HOST_WIDE_INT maxvalue
1666 = tree_low_cst (TYPE_MAX_VALUE (element), 1);
1667 HOST_WIDE_INT minvalue
1668 = tree_low_cst (TYPE_MIN_VALUE (element), 1);
1670 if (maxvalue - minvalue == 1
1671 && (maxvalue == 1 || maxvalue == 0))
1672 element_size = integer_one_node;
1675 /* If neither bound is a constant and sizetype is signed, make
1676 sure the size is never negative. We should really do this
1677 if *either* bound is non-constant, but this is the best
1678 compromise between C and Ada. */
1679 if (! TREE_UNSIGNED (sizetype)
1680 && TREE_CODE (TYPE_MIN_VALUE (index)) != INTEGER_CST
1681 && TREE_CODE (TYPE_MAX_VALUE (index)) != INTEGER_CST)
1682 length = size_binop (MAX_EXPR, length, size_zero_node);
1684 TYPE_SIZE (type) = size_binop (MULT_EXPR, element_size,
1685 convert (bitsizetype, length));
1687 /* If we know the size of the element, calculate the total
1688 size directly, rather than do some division thing below.
1689 This optimization helps Fortran assumed-size arrays
1690 (where the size of the array is determined at runtime)
1692 Note that we can't do this in the case where the size of
1693 the elements is one bit since TYPE_SIZE_UNIT cannot be
1694 set correctly in that case. */
1695 if (TYPE_SIZE_UNIT (element) != 0 && ! integer_onep (element_size))
1696 TYPE_SIZE_UNIT (type)
1697 = size_binop (MULT_EXPR, TYPE_SIZE_UNIT (element), length);
1700 /* Now round the alignment and size,
1701 using machine-dependent criteria if any. */
1703 #ifdef ROUND_TYPE_ALIGN
1705 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (element), BITS_PER_UNIT);
1707 TYPE_ALIGN (type) = MAX (TYPE_ALIGN (element), BITS_PER_UNIT);
1709 TYPE_USER_ALIGN (type) = TYPE_USER_ALIGN (element);
1710 TYPE_MODE (type) = BLKmode;
1711 if (TYPE_SIZE (type) != 0
1712 #ifdef MEMBER_TYPE_FORCES_BLK
1713 && ! MEMBER_TYPE_FORCES_BLK (type, VOIDmode)
1715 /* BLKmode elements force BLKmode aggregate;
1716 else extract/store fields may lose. */
1717 && (TYPE_MODE (TREE_TYPE (type)) != BLKmode
1718 || TYPE_NO_FORCE_BLK (TREE_TYPE (type))))
1720 /* One-element arrays get the component type's mode. */
1721 if (simple_cst_equal (TYPE_SIZE (type),
1722 TYPE_SIZE (TREE_TYPE (type))))
1723 TYPE_MODE (type) = TYPE_MODE (TREE_TYPE (type));
1726 = mode_for_size_tree (TYPE_SIZE (type), MODE_INT, 1);
1728 if (TYPE_MODE (type) != BLKmode
1729 && STRICT_ALIGNMENT && TYPE_ALIGN (type) < BIGGEST_ALIGNMENT
1730 && TYPE_ALIGN (type) < GET_MODE_ALIGNMENT (TYPE_MODE (type))
1731 && TYPE_MODE (type) != BLKmode)
1733 TYPE_NO_FORCE_BLK (type) = 1;
1734 TYPE_MODE (type) = BLKmode;
1742 case QUAL_UNION_TYPE:
1745 record_layout_info rli;
1747 /* Initialize the layout information. */
1748 rli = start_record_layout (type);
1750 /* If this is a QUAL_UNION_TYPE, we want to process the fields
1751 in the reverse order in building the COND_EXPR that denotes
1752 its size. We reverse them again later. */
1753 if (TREE_CODE (type) == QUAL_UNION_TYPE)
1754 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
1756 /* Place all the fields. */
1757 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1758 place_field (rli, field);
1760 if (TREE_CODE (type) == QUAL_UNION_TYPE)
1761 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
1763 if (lang_adjust_rli)
1764 (*lang_adjust_rli) (rli);
1766 /* Finish laying out the record. */
1767 finish_record_layout (rli, /*free_p=*/true);
1771 case SET_TYPE: /* Used by Chill and Pascal. */
1772 if (TREE_CODE (TYPE_MAX_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST
1773 || TREE_CODE (TYPE_MIN_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST)
1777 #ifndef SET_WORD_SIZE
1778 #define SET_WORD_SIZE BITS_PER_WORD
1780 unsigned int alignment
1781 = set_alignment ? set_alignment : SET_WORD_SIZE;
1782 HOST_WIDE_INT size_in_bits
1783 = (tree_low_cst (TYPE_MAX_VALUE (TYPE_DOMAIN (type)), 0)
1784 - tree_low_cst (TYPE_MIN_VALUE (TYPE_DOMAIN (type)), 0) + 1);
1785 HOST_WIDE_INT rounded_size
1786 = ((size_in_bits + alignment - 1) / alignment) * alignment;
1788 if (rounded_size > (int) alignment)
1789 TYPE_MODE (type) = BLKmode;
1791 TYPE_MODE (type) = mode_for_size (alignment, MODE_INT, 1);
1793 TYPE_SIZE (type) = bitsize_int (rounded_size);
1794 TYPE_SIZE_UNIT (type) = size_int (rounded_size / BITS_PER_UNIT);
1795 TYPE_ALIGN (type) = alignment;
1796 TYPE_USER_ALIGN (type) = 0;
1797 TYPE_PRECISION (type) = size_in_bits;
1802 /* The size may vary in different languages, so the language front end
1803 should fill in the size. */
1804 TYPE_ALIGN (type) = BIGGEST_ALIGNMENT;
1805 TYPE_USER_ALIGN (type) = 0;
1806 TYPE_MODE (type) = BLKmode;
1813 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
1814 records and unions, finish_record_layout already called this
1816 if (TREE_CODE (type) != RECORD_TYPE
1817 && TREE_CODE (type) != UNION_TYPE
1818 && TREE_CODE (type) != QUAL_UNION_TYPE)
1819 finalize_type_size (type);
1821 /* If this type is created before sizetype has been permanently set,
1822 record it so set_sizetype can fix it up. */
1824 early_type_list = tree_cons (NULL_TREE, type, early_type_list);
1826 /* If an alias set has been set for this aggregate when it was incomplete,
1827 force it into alias set 0.
1828 This is too conservative, but we cannot call record_component_aliases
1829 here because some frontends still change the aggregates after
1831 if (AGGREGATE_TYPE_P (type) && TYPE_ALIAS_SET_KNOWN_P (type))
1832 TYPE_ALIAS_SET (type) = 0;
1835 /* Create and return a type for signed integers of PRECISION bits. */
1838 make_signed_type (int precision)
1840 tree type = make_node (INTEGER_TYPE);
1842 TYPE_PRECISION (type) = precision;
1844 fixup_signed_type (type);
1848 /* Create and return a type for unsigned integers of PRECISION bits. */
1851 make_unsigned_type (int precision)
1853 tree type = make_node (INTEGER_TYPE);
1855 TYPE_PRECISION (type) = precision;
1857 fixup_unsigned_type (type);
1861 /* Initialize sizetype and bitsizetype to a reasonable and temporary
1862 value to enable integer types to be created. */
1865 initialize_sizetypes (void)
1867 tree t = make_node (INTEGER_TYPE);
1869 /* Set this so we do something reasonable for the build_int_2 calls
1871 integer_type_node = t;
1873 TYPE_MODE (t) = SImode;
1874 TYPE_ALIGN (t) = GET_MODE_ALIGNMENT (SImode);
1875 TYPE_USER_ALIGN (t) = 0;
1876 TYPE_SIZE (t) = build_int_2 (GET_MODE_BITSIZE (SImode), 0);
1877 TYPE_SIZE_UNIT (t) = build_int_2 (GET_MODE_SIZE (SImode), 0);
1878 TREE_UNSIGNED (t) = 1;
1879 TYPE_PRECISION (t) = GET_MODE_BITSIZE (SImode);
1880 TYPE_MIN_VALUE (t) = build_int_2 (0, 0);
1881 TYPE_IS_SIZETYPE (t) = 1;
1883 /* 1000 avoids problems with possible overflow and is certainly
1884 larger than any size value we'd want to be storing. */
1885 TYPE_MAX_VALUE (t) = build_int_2 (1000, 0);
1887 /* These two must be different nodes because of the caching done in
1890 bitsizetype = copy_node (t);
1891 integer_type_node = 0;
1894 /* Set sizetype to TYPE, and initialize *sizetype accordingly.
1895 Also update the type of any standard type's sizes made so far. */
1898 set_sizetype (tree type)
1900 int oprecision = TYPE_PRECISION (type);
1901 /* The *bitsizetype types use a precision that avoids overflows when
1902 calculating signed sizes / offsets in bits. However, when
1903 cross-compiling from a 32 bit to a 64 bit host, we are limited to 64 bit
1905 int precision = MIN (oprecision + BITS_PER_UNIT_LOG + 1,
1906 2 * HOST_BITS_PER_WIDE_INT);
1913 /* Make copies of nodes since we'll be setting TYPE_IS_SIZETYPE. */
1914 sizetype = copy_node (type);
1915 TYPE_DOMAIN (sizetype) = type;
1916 TYPE_IS_SIZETYPE (sizetype) = 1;
1917 bitsizetype = make_node (INTEGER_TYPE);
1918 TYPE_NAME (bitsizetype) = TYPE_NAME (type);
1919 TYPE_PRECISION (bitsizetype) = precision;
1920 TYPE_IS_SIZETYPE (bitsizetype) = 1;
1922 if (TREE_UNSIGNED (type))
1923 fixup_unsigned_type (bitsizetype);
1925 fixup_signed_type (bitsizetype);
1927 layout_type (bitsizetype);
1929 if (TREE_UNSIGNED (type))
1931 usizetype = sizetype;
1932 ubitsizetype = bitsizetype;
1933 ssizetype = copy_node (make_signed_type (oprecision));
1934 sbitsizetype = copy_node (make_signed_type (precision));
1938 ssizetype = sizetype;
1939 sbitsizetype = bitsizetype;
1940 usizetype = copy_node (make_unsigned_type (oprecision));
1941 ubitsizetype = copy_node (make_unsigned_type (precision));
1944 TYPE_NAME (bitsizetype) = get_identifier ("bit_size_type");
1946 /* Show is a sizetype, is a main type, and has no pointers to it. */
1947 for (i = 0; i < ARRAY_SIZE (sizetype_tab); i++)
1949 TYPE_IS_SIZETYPE (sizetype_tab[i]) = 1;
1950 TYPE_MAIN_VARIANT (sizetype_tab[i]) = sizetype_tab[i];
1951 TYPE_NEXT_VARIANT (sizetype_tab[i]) = 0;
1952 TYPE_POINTER_TO (sizetype_tab[i]) = 0;
1953 TYPE_REFERENCE_TO (sizetype_tab[i]) = 0;
1956 /* Go down each of the types we already made and set the proper type
1957 for the sizes in them. */
1958 for (t = early_type_list; t != 0; t = TREE_CHAIN (t))
1960 if (TREE_CODE (TREE_VALUE (t)) != INTEGER_TYPE)
1963 TREE_TYPE (TYPE_SIZE (TREE_VALUE (t))) = bitsizetype;
1964 TREE_TYPE (TYPE_SIZE_UNIT (TREE_VALUE (t))) = sizetype;
1967 early_type_list = 0;
1971 /* Set the extreme values of TYPE based on its precision in bits,
1972 then lay it out. Used when make_signed_type won't do
1973 because the tree code is not INTEGER_TYPE.
1974 E.g. for Pascal, when the -fsigned-char option is given. */
1977 fixup_signed_type (tree type)
1979 int precision = TYPE_PRECISION (type);
1981 /* We can not represent properly constants greater then
1982 2 * HOST_BITS_PER_WIDE_INT, still we need the types
1983 as they are used by i386 vector extensions and friends. */
1984 if (precision > HOST_BITS_PER_WIDE_INT * 2)
1985 precision = HOST_BITS_PER_WIDE_INT * 2;
1987 TYPE_MIN_VALUE (type)
1988 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1989 ? 0 : (HOST_WIDE_INT) (-1) << (precision - 1)),
1990 (((HOST_WIDE_INT) (-1)
1991 << (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1992 ? precision - HOST_BITS_PER_WIDE_INT - 1
1994 TYPE_MAX_VALUE (type)
1995 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1996 ? -1 : ((HOST_WIDE_INT) 1 << (precision - 1)) - 1),
1997 (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1998 ? (((HOST_WIDE_INT) 1
1999 << (precision - HOST_BITS_PER_WIDE_INT - 1))) - 1
2002 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
2003 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
2005 /* Lay out the type: set its alignment, size, etc. */
2009 /* Set the extreme values of TYPE based on its precision in bits,
2010 then lay it out. This is used both in `make_unsigned_type'
2011 and for enumeral types. */
2014 fixup_unsigned_type (tree type)
2016 int precision = TYPE_PRECISION (type);
2018 /* We can not represent properly constants greater then
2019 2 * HOST_BITS_PER_WIDE_INT, still we need the types
2020 as they are used by i386 vector extensions and friends. */
2021 if (precision > HOST_BITS_PER_WIDE_INT * 2)
2022 precision = HOST_BITS_PER_WIDE_INT * 2;
2024 TYPE_MIN_VALUE (type) = build_int_2 (0, 0);
2025 TYPE_MAX_VALUE (type)
2026 = build_int_2 (precision - HOST_BITS_PER_WIDE_INT >= 0
2027 ? -1 : ((HOST_WIDE_INT) 1 << precision) - 1,
2028 precision - HOST_BITS_PER_WIDE_INT > 0
2029 ? ((unsigned HOST_WIDE_INT) ~0
2030 >> (HOST_BITS_PER_WIDE_INT
2031 - (precision - HOST_BITS_PER_WIDE_INT)))
2033 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
2034 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
2036 /* Lay out the type: set its alignment, size, etc. */
2040 /* Find the best machine mode to use when referencing a bit field of length
2041 BITSIZE bits starting at BITPOS.
2043 The underlying object is known to be aligned to a boundary of ALIGN bits.
2044 If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
2045 larger than LARGEST_MODE (usually SImode).
2047 If no mode meets all these conditions, we return VOIDmode. Otherwise, if
2048 VOLATILEP is true or SLOW_BYTE_ACCESS is false, we return the smallest
2049 mode meeting these conditions.
2051 Otherwise (VOLATILEP is false and SLOW_BYTE_ACCESS is true), we return
2052 the largest mode (but a mode no wider than UNITS_PER_WORD) that meets
2053 all the conditions. */
2056 get_best_mode (int bitsize, int bitpos, unsigned int align,
2057 enum machine_mode largest_mode, int volatilep)
2059 enum machine_mode mode;
2060 unsigned int unit = 0;
2062 /* Find the narrowest integer mode that contains the bit field. */
2063 for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
2064 mode = GET_MODE_WIDER_MODE (mode))
2066 unit = GET_MODE_BITSIZE (mode);
2067 if ((bitpos % unit) + bitsize <= unit)
2071 if (mode == VOIDmode
2072 /* It is tempting to omit the following line
2073 if STRICT_ALIGNMENT is true.
2074 But that is incorrect, since if the bitfield uses part of 3 bytes
2075 and we use a 4-byte mode, we could get a spurious segv
2076 if the extra 4th byte is past the end of memory.
2077 (Though at least one Unix compiler ignores this problem:
2078 that on the Sequent 386 machine. */
2079 || MIN (unit, BIGGEST_ALIGNMENT) > align
2080 || (largest_mode != VOIDmode && unit > GET_MODE_BITSIZE (largest_mode)))
2083 if (SLOW_BYTE_ACCESS && ! volatilep)
2085 enum machine_mode wide_mode = VOIDmode, tmode;
2087 for (tmode = GET_CLASS_NARROWEST_MODE (MODE_INT); tmode != VOIDmode;
2088 tmode = GET_MODE_WIDER_MODE (tmode))
2090 unit = GET_MODE_BITSIZE (tmode);
2091 if (bitpos / unit == (bitpos + bitsize - 1) / unit
2092 && unit <= BITS_PER_WORD
2093 && unit <= MIN (align, BIGGEST_ALIGNMENT)
2094 && (largest_mode == VOIDmode
2095 || unit <= GET_MODE_BITSIZE (largest_mode)))
2099 if (wide_mode != VOIDmode)
2106 #include "gt-stor-layout.h"