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 return MIN (BIGGEST_ALIGNMENT, MAX (1, mode_base_align[mode]*BITS_PER_UNIT));
304 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
305 This can only be applied to objects of a sizetype. */
308 round_up (tree value, int divisor)
310 tree arg = size_int_type (divisor, TREE_TYPE (value));
312 return size_binop (MULT_EXPR, size_binop (CEIL_DIV_EXPR, value, arg), arg);
315 /* Likewise, but round down. */
318 round_down (tree value, int divisor)
320 tree arg = size_int_type (divisor, TREE_TYPE (value));
322 return size_binop (MULT_EXPR, size_binop (FLOOR_DIV_EXPR, value, arg), arg);
325 /* Subroutine of layout_decl: Force alignment required for the data type.
326 But if the decl itself wants greater alignment, don't override that. */
329 do_type_align (tree type, tree decl)
331 if (TYPE_ALIGN (type) > DECL_ALIGN (decl))
333 DECL_ALIGN (decl) = TYPE_ALIGN (type);
334 if (TREE_CODE (decl) == FIELD_DECL)
335 DECL_USER_ALIGN (decl) = TYPE_USER_ALIGN (type);
339 /* Set the size, mode and alignment of a ..._DECL node.
340 TYPE_DECL does need this for C++.
341 Note that LABEL_DECL and CONST_DECL nodes do not need this,
342 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
343 Don't call layout_decl for them.
345 KNOWN_ALIGN is the amount of alignment we can assume this
346 decl has with no special effort. It is relevant only for FIELD_DECLs
347 and depends on the previous fields.
348 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
349 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
350 the record will be aligned to suit. */
353 layout_decl (tree decl, unsigned int known_align)
355 tree type = TREE_TYPE (decl);
356 enum tree_code code = TREE_CODE (decl);
359 if (code == CONST_DECL)
361 else if (code != VAR_DECL && code != PARM_DECL && code != RESULT_DECL
362 && code != TYPE_DECL && code != FIELD_DECL)
365 rtl = DECL_RTL_IF_SET (decl);
367 if (type == error_mark_node)
368 type = void_type_node;
370 /* Usually the size and mode come from the data type without change,
371 however, the front-end may set the explicit width of the field, so its
372 size may not be the same as the size of its type. This happens with
373 bitfields, of course (an `int' bitfield may be only 2 bits, say), but it
374 also happens with other fields. For example, the C++ front-end creates
375 zero-sized fields corresponding to empty base classes, and depends on
376 layout_type setting DECL_FIELD_BITPOS correctly for the field. Set the
377 size in bytes from the size in bits. If we have already set the mode,
378 don't set it again since we can be called twice for FIELD_DECLs. */
380 TREE_UNSIGNED (decl) = TREE_UNSIGNED (type);
381 if (DECL_MODE (decl) == VOIDmode)
382 DECL_MODE (decl) = TYPE_MODE (type);
384 if (DECL_SIZE (decl) == 0)
386 DECL_SIZE (decl) = TYPE_SIZE (type);
387 DECL_SIZE_UNIT (decl) = TYPE_SIZE_UNIT (type);
389 else if (DECL_SIZE_UNIT (decl) == 0)
390 DECL_SIZE_UNIT (decl)
391 = convert (sizetype, size_binop (CEIL_DIV_EXPR, DECL_SIZE (decl),
394 if (code != FIELD_DECL)
395 /* For non-fields, update the alignment from the type. */
396 do_type_align (type, decl);
398 /* For fields, it's a bit more complicated... */
400 if (DECL_BIT_FIELD (decl))
402 DECL_BIT_FIELD_TYPE (decl) = type;
404 /* A zero-length bit-field affects the alignment of the next
406 if (integer_zerop (DECL_SIZE (decl))
407 && ! DECL_PACKED (decl)
408 && ! (*targetm.ms_bitfield_layout_p) (DECL_FIELD_CONTEXT (decl)))
410 #ifdef PCC_BITFIELD_TYPE_MATTERS
411 if (PCC_BITFIELD_TYPE_MATTERS)
412 do_type_align (type, decl);
416 #ifdef EMPTY_FIELD_BOUNDARY
417 if (EMPTY_FIELD_BOUNDARY > DECL_ALIGN (decl))
419 DECL_ALIGN (decl) = EMPTY_FIELD_BOUNDARY;
420 DECL_USER_ALIGN (decl) = 0;
426 /* See if we can use an ordinary integer mode for a bit-field.
427 Conditions are: a fixed size that is correct for another mode
428 and occupying a complete byte or bytes on proper boundary. */
429 if (TYPE_SIZE (type) != 0
430 && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
431 && GET_MODE_CLASS (TYPE_MODE (type)) == MODE_INT)
433 enum machine_mode xmode
434 = mode_for_size_tree (DECL_SIZE (decl), MODE_INT, 1);
436 if (xmode != BLKmode && known_align >= GET_MODE_ALIGNMENT (xmode))
438 DECL_ALIGN (decl) = MAX (GET_MODE_ALIGNMENT (xmode),
440 DECL_MODE (decl) = xmode;
441 DECL_BIT_FIELD (decl) = 0;
445 /* Turn off DECL_BIT_FIELD if we won't need it set. */
446 if (TYPE_MODE (type) == BLKmode && DECL_MODE (decl) == BLKmode
447 && known_align >= TYPE_ALIGN (type)
448 && DECL_ALIGN (decl) >= TYPE_ALIGN (type))
449 DECL_BIT_FIELD (decl) = 0;
451 else if (DECL_PACKED (decl) && DECL_USER_ALIGN (decl))
452 /* Don't touch DECL_ALIGN. For other packed fields, go ahead and
453 round up; we'll reduce it again below. */;
455 do_type_align (type, decl);
457 /* If the field is of variable size, we can't misalign it since we
458 have no way to make a temporary to align the result. But this
459 isn't an issue if the decl is not addressable. Likewise if it
460 is of unknown size. */
461 if (DECL_PACKED (decl)
462 && !DECL_USER_ALIGN (decl)
463 && (DECL_NONADDRESSABLE_P (decl)
464 || DECL_SIZE_UNIT (decl) == 0
465 || TREE_CODE (DECL_SIZE_UNIT (decl)) == INTEGER_CST))
466 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), BITS_PER_UNIT);
468 /* Should this be controlled by DECL_USER_ALIGN, too? */
469 if (maximum_field_alignment != 0)
470 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), maximum_field_alignment);
471 if (! DECL_USER_ALIGN (decl))
473 /* Some targets (i.e. i386, VMS) limit struct field alignment
474 to a lower boundary than alignment of variables unless
475 it was overridden by attribute aligned. */
476 #ifdef BIGGEST_FIELD_ALIGNMENT
478 = MIN (DECL_ALIGN (decl), (unsigned) BIGGEST_FIELD_ALIGNMENT);
480 #ifdef ADJUST_FIELD_ALIGN
481 DECL_ALIGN (decl) = ADJUST_FIELD_ALIGN (decl, DECL_ALIGN (decl));
486 /* Evaluate nonconstant size only once, either now or as soon as safe. */
487 if (DECL_SIZE (decl) != 0 && TREE_CODE (DECL_SIZE (decl)) != INTEGER_CST)
488 DECL_SIZE (decl) = variable_size (DECL_SIZE (decl));
489 if (DECL_SIZE_UNIT (decl) != 0
490 && TREE_CODE (DECL_SIZE_UNIT (decl)) != INTEGER_CST)
491 DECL_SIZE_UNIT (decl) = variable_size (DECL_SIZE_UNIT (decl));
493 /* If requested, warn about definitions of large data objects. */
495 && (code == VAR_DECL || code == PARM_DECL)
496 && ! DECL_EXTERNAL (decl))
498 tree size = DECL_SIZE_UNIT (decl);
500 if (size != 0 && TREE_CODE (size) == INTEGER_CST
501 && compare_tree_int (size, larger_than_size) > 0)
503 int size_as_int = TREE_INT_CST_LOW (size);
505 if (compare_tree_int (size, size_as_int) == 0)
506 warning ("%Jsize of '%D' is %d bytes", decl, decl, size_as_int);
508 warning ("%Jsize of '%D' is larger than %d bytes",
509 decl, decl, larger_than_size);
513 /* If the RTL was already set, update its mode and mem attributes. */
516 PUT_MODE (rtl, DECL_MODE (decl));
517 SET_DECL_RTL (decl, 0);
518 set_mem_attributes (rtl, decl, 1);
519 SET_DECL_RTL (decl, rtl);
523 /* Hook for a front-end function that can modify the record layout as needed
524 immediately before it is finalized. */
526 void (*lang_adjust_rli) (record_layout_info) = 0;
529 set_lang_adjust_rli (void (*f) (record_layout_info))
534 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
535 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
536 is to be passed to all other layout functions for this record. It is the
537 responsibility of the caller to call `free' for the storage returned.
538 Note that garbage collection is not permitted until we finish laying
542 start_record_layout (tree t)
544 record_layout_info rli = xmalloc (sizeof (struct record_layout_info_s));
548 /* If the type has a minimum specified alignment (via an attribute
549 declaration, for example) use it -- otherwise, start with a
550 one-byte alignment. */
551 rli->record_align = MAX (BITS_PER_UNIT, TYPE_ALIGN (t));
552 rli->unpacked_align = rli->record_align;
553 rli->offset_align = MAX (rli->record_align, BIGGEST_ALIGNMENT);
555 #ifdef STRUCTURE_SIZE_BOUNDARY
556 /* Packed structures don't need to have minimum size. */
557 if (! TYPE_PACKED (t))
558 rli->record_align = MAX (rli->record_align, (unsigned) STRUCTURE_SIZE_BOUNDARY);
561 rli->offset = size_zero_node;
562 rli->bitpos = bitsize_zero_node;
564 rli->pending_statics = 0;
565 rli->packed_maybe_necessary = 0;
570 /* These four routines perform computations that convert between
571 the offset/bitpos forms and byte and bit offsets. */
574 bit_from_pos (tree offset, tree bitpos)
576 return size_binop (PLUS_EXPR, bitpos,
577 size_binop (MULT_EXPR, convert (bitsizetype, offset),
582 byte_from_pos (tree offset, tree bitpos)
584 return size_binop (PLUS_EXPR, offset,
586 size_binop (TRUNC_DIV_EXPR, bitpos,
587 bitsize_unit_node)));
591 pos_from_bit (tree *poffset, tree *pbitpos, unsigned int off_align,
594 *poffset = size_binop (MULT_EXPR,
596 size_binop (FLOOR_DIV_EXPR, pos,
597 bitsize_int (off_align))),
598 size_int (off_align / BITS_PER_UNIT));
599 *pbitpos = size_binop (FLOOR_MOD_EXPR, pos, bitsize_int (off_align));
602 /* Given a pointer to bit and byte offsets and an offset alignment,
603 normalize the offsets so they are within the alignment. */
606 normalize_offset (tree *poffset, tree *pbitpos, unsigned int off_align)
608 /* If the bit position is now larger than it should be, adjust it
610 if (compare_tree_int (*pbitpos, off_align) >= 0)
612 tree extra_aligns = size_binop (FLOOR_DIV_EXPR, *pbitpos,
613 bitsize_int (off_align));
616 = size_binop (PLUS_EXPR, *poffset,
617 size_binop (MULT_EXPR, convert (sizetype, extra_aligns),
618 size_int (off_align / BITS_PER_UNIT)));
621 = size_binop (FLOOR_MOD_EXPR, *pbitpos, bitsize_int (off_align));
625 /* Print debugging information about the information in RLI. */
628 debug_rli (record_layout_info rli)
630 print_node_brief (stderr, "type", rli->t, 0);
631 print_node_brief (stderr, "\noffset", rli->offset, 0);
632 print_node_brief (stderr, " bitpos", rli->bitpos, 0);
634 fprintf (stderr, "\naligns: rec = %u, unpack = %u, off = %u\n",
635 rli->record_align, rli->unpacked_align,
637 if (rli->packed_maybe_necessary)
638 fprintf (stderr, "packed may be necessary\n");
640 if (rli->pending_statics)
642 fprintf (stderr, "pending statics:\n");
643 debug_tree (rli->pending_statics);
647 /* Given an RLI with a possibly-incremented BITPOS, adjust OFFSET and
648 BITPOS if necessary to keep BITPOS below OFFSET_ALIGN. */
651 normalize_rli (record_layout_info rli)
653 normalize_offset (&rli->offset, &rli->bitpos, rli->offset_align);
656 /* Returns the size in bytes allocated so far. */
659 rli_size_unit_so_far (record_layout_info rli)
661 return byte_from_pos (rli->offset, rli->bitpos);
664 /* Returns the size in bits allocated so far. */
667 rli_size_so_far (record_layout_info rli)
669 return bit_from_pos (rli->offset, rli->bitpos);
672 /* FIELD is about to be added to RLI->T. The alignment (in bits) of
673 the next available location is given by KNOWN_ALIGN. Update the
674 variable alignment fields in RLI, and return the alignment to give
678 update_alignment_for_field (record_layout_info rli, tree field,
679 unsigned int known_align)
681 /* The alignment required for FIELD. */
682 unsigned int desired_align;
683 /* The type of this field. */
684 tree type = TREE_TYPE (field);
685 /* True if the field was explicitly aligned by the user. */
689 /* Lay out the field so we know what alignment it needs. */
690 layout_decl (field, known_align);
691 desired_align = DECL_ALIGN (field);
692 user_align = DECL_USER_ALIGN (field);
694 is_bitfield = (type != error_mark_node
695 && DECL_BIT_FIELD_TYPE (field)
696 && ! integer_zerop (TYPE_SIZE (type)));
698 /* Record must have at least as much alignment as any field.
699 Otherwise, the alignment of the field within the record is
701 if (is_bitfield && (* targetm.ms_bitfield_layout_p) (rli->t))
703 /* Here, the alignment of the underlying type of a bitfield can
704 affect the alignment of a record; even a zero-sized field
705 can do this. The alignment should be to the alignment of
706 the type, except that for zero-size bitfields this only
707 applies if there was an immediately prior, nonzero-size
708 bitfield. (That's the way it is, experimentally.) */
709 if (! integer_zerop (DECL_SIZE (field))
710 ? ! DECL_PACKED (field)
712 && DECL_BIT_FIELD_TYPE (rli->prev_field)
713 && ! integer_zerop (DECL_SIZE (rli->prev_field))))
715 unsigned int type_align = TYPE_ALIGN (type);
716 type_align = MAX (type_align, desired_align);
717 if (maximum_field_alignment != 0)
718 type_align = MIN (type_align, maximum_field_alignment);
719 rli->record_align = MAX (rli->record_align, type_align);
720 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
723 #ifdef PCC_BITFIELD_TYPE_MATTERS
724 else if (is_bitfield && PCC_BITFIELD_TYPE_MATTERS)
726 /* Named bit-fields cause the entire structure to have the
727 alignment implied by their type. */
728 if (DECL_NAME (field) != 0)
730 unsigned int type_align = TYPE_ALIGN (type);
732 #ifdef ADJUST_FIELD_ALIGN
733 if (! TYPE_USER_ALIGN (type))
734 type_align = ADJUST_FIELD_ALIGN (field, type_align);
737 if (maximum_field_alignment != 0)
738 type_align = MIN (type_align, maximum_field_alignment);
739 else if (DECL_PACKED (field))
740 type_align = MIN (type_align, BITS_PER_UNIT);
742 /* The alignment of the record is increased to the maximum
743 of the current alignment, the alignment indicated on the
744 field (i.e., the alignment specified by an __aligned__
745 attribute), and the alignment indicated by the type of
747 rli->record_align = MAX (rli->record_align, desired_align);
748 rli->record_align = MAX (rli->record_align, type_align);
751 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
752 user_align |= TYPE_USER_ALIGN (type);
758 rli->record_align = MAX (rli->record_align, desired_align);
759 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
762 TYPE_USER_ALIGN (rli->t) |= user_align;
764 return desired_align;
767 /* Called from place_field to handle unions. */
770 place_union_field (record_layout_info rli, tree field)
772 update_alignment_for_field (rli, field, /*known_align=*/0);
774 DECL_FIELD_OFFSET (field) = size_zero_node;
775 DECL_FIELD_BIT_OFFSET (field) = bitsize_zero_node;
776 SET_DECL_OFFSET_ALIGN (field, BIGGEST_ALIGNMENT);
778 /* We assume the union's size will be a multiple of a byte so we don't
779 bother with BITPOS. */
780 if (TREE_CODE (rli->t) == UNION_TYPE)
781 rli->offset = size_binop (MAX_EXPR, rli->offset, DECL_SIZE_UNIT (field));
782 else if (TREE_CODE (rli->t) == QUAL_UNION_TYPE)
783 rli->offset = fold (build (COND_EXPR, sizetype,
784 DECL_QUALIFIER (field),
785 DECL_SIZE_UNIT (field), rli->offset));
788 #if defined (PCC_BITFIELD_TYPE_MATTERS) || defined (BITFIELD_NBYTES_LIMITED)
789 /* A bitfield of SIZE with a required access alignment of ALIGN is allocated
790 at BYTE_OFFSET / BIT_OFFSET. Return nonzero if the field would span more
791 units of alignment than the underlying TYPE. */
793 excess_unit_span (HOST_WIDE_INT byte_offset, HOST_WIDE_INT bit_offset,
794 HOST_WIDE_INT size, HOST_WIDE_INT align, tree type)
796 /* Note that the calculation of OFFSET might overflow; we calculate it so
797 that we still get the right result as long as ALIGN is a power of two. */
798 unsigned HOST_WIDE_INT offset = byte_offset * BITS_PER_UNIT + bit_offset;
800 offset = offset % align;
801 return ((offset + size + align - 1) / align
802 > ((unsigned HOST_WIDE_INT) tree_low_cst (TYPE_SIZE (type), 1)
807 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
808 is a FIELD_DECL to be added after those fields already present in
809 T. (FIELD is not actually added to the TYPE_FIELDS list here;
810 callers that desire that behavior must manually perform that step.) */
813 place_field (record_layout_info rli, tree field)
815 /* The alignment required for FIELD. */
816 unsigned int desired_align;
817 /* The alignment FIELD would have if we just dropped it into the
818 record as it presently stands. */
819 unsigned int known_align;
820 unsigned int actual_align;
821 /* The type of this field. */
822 tree type = TREE_TYPE (field);
824 if (TREE_CODE (field) == ERROR_MARK || TREE_CODE (type) == ERROR_MARK)
827 /* If FIELD is static, then treat it like a separate variable, not
828 really like a structure field. If it is a FUNCTION_DECL, it's a
829 method. In both cases, all we do is lay out the decl, and we do
830 it *after* the record is laid out. */
831 if (TREE_CODE (field) == VAR_DECL)
833 rli->pending_statics = tree_cons (NULL_TREE, field,
834 rli->pending_statics);
838 /* Enumerators and enum types which are local to this class need not
839 be laid out. Likewise for initialized constant fields. */
840 else if (TREE_CODE (field) != FIELD_DECL)
843 /* Unions are laid out very differently than records, so split
844 that code off to another function. */
845 else if (TREE_CODE (rli->t) != RECORD_TYPE)
847 place_union_field (rli, field);
851 /* Work out the known alignment so far. Note that A & (-A) is the
852 value of the least-significant bit in A that is one. */
853 if (! integer_zerop (rli->bitpos))
854 known_align = (tree_low_cst (rli->bitpos, 1)
855 & - tree_low_cst (rli->bitpos, 1));
856 else if (integer_zerop (rli->offset))
857 known_align = BIGGEST_ALIGNMENT;
858 else if (host_integerp (rli->offset, 1))
859 known_align = (BITS_PER_UNIT
860 * (tree_low_cst (rli->offset, 1)
861 & - tree_low_cst (rli->offset, 1)));
863 known_align = rli->offset_align;
865 desired_align = update_alignment_for_field (rli, field, known_align);
867 if (warn_packed && DECL_PACKED (field))
869 if (known_align >= TYPE_ALIGN (type))
871 if (TYPE_ALIGN (type) > desired_align)
873 if (STRICT_ALIGNMENT)
874 warning ("%Jpacked attribute causes inefficient alignment "
875 "for '%D'", field, field);
877 warning ("%Jpacked attribute is unnecessary for '%D'",
882 rli->packed_maybe_necessary = 1;
885 /* Does this field automatically have alignment it needs by virtue
886 of the fields that precede it and the record's own alignment? */
887 if (known_align < desired_align)
889 /* No, we need to skip space before this field.
890 Bump the cumulative size to multiple of field alignment. */
893 warning ("%Jpadding struct to align '%D'", field, field);
895 /* If the alignment is still within offset_align, just align
897 if (desired_align < rli->offset_align)
898 rli->bitpos = round_up (rli->bitpos, desired_align);
901 /* First adjust OFFSET by the partial bits, then align. */
903 = size_binop (PLUS_EXPR, rli->offset,
905 size_binop (CEIL_DIV_EXPR, rli->bitpos,
906 bitsize_unit_node)));
907 rli->bitpos = bitsize_zero_node;
909 rli->offset = round_up (rli->offset, desired_align / BITS_PER_UNIT);
912 if (! TREE_CONSTANT (rli->offset))
913 rli->offset_align = desired_align;
917 /* Handle compatibility with PCC. Note that if the record has any
918 variable-sized fields, we need not worry about compatibility. */
919 #ifdef PCC_BITFIELD_TYPE_MATTERS
920 if (PCC_BITFIELD_TYPE_MATTERS
921 && ! (* targetm.ms_bitfield_layout_p) (rli->t)
922 && TREE_CODE (field) == FIELD_DECL
923 && type != error_mark_node
924 && DECL_BIT_FIELD (field)
925 && ! DECL_PACKED (field)
926 && maximum_field_alignment == 0
927 && ! integer_zerop (DECL_SIZE (field))
928 && host_integerp (DECL_SIZE (field), 1)
929 && host_integerp (rli->offset, 1)
930 && host_integerp (TYPE_SIZE (type), 1))
932 unsigned int type_align = TYPE_ALIGN (type);
933 tree dsize = DECL_SIZE (field);
934 HOST_WIDE_INT field_size = tree_low_cst (dsize, 1);
935 HOST_WIDE_INT offset = tree_low_cst (rli->offset, 0);
936 HOST_WIDE_INT bit_offset = tree_low_cst (rli->bitpos, 0);
938 #ifdef ADJUST_FIELD_ALIGN
939 if (! TYPE_USER_ALIGN (type))
940 type_align = ADJUST_FIELD_ALIGN (field, type_align);
943 /* A bit field may not span more units of alignment of its type
944 than its type itself. Advance to next boundary if necessary. */
945 if (excess_unit_span (offset, bit_offset, field_size, type_align, type))
946 rli->bitpos = round_up (rli->bitpos, type_align);
948 TYPE_USER_ALIGN (rli->t) |= TYPE_USER_ALIGN (type);
952 #ifdef BITFIELD_NBYTES_LIMITED
953 if (BITFIELD_NBYTES_LIMITED
954 && ! (* targetm.ms_bitfield_layout_p) (rli->t)
955 && TREE_CODE (field) == FIELD_DECL
956 && type != error_mark_node
957 && DECL_BIT_FIELD_TYPE (field)
958 && ! DECL_PACKED (field)
959 && ! integer_zerop (DECL_SIZE (field))
960 && host_integerp (DECL_SIZE (field), 1)
961 && host_integerp (rli->offset, 1)
962 && host_integerp (TYPE_SIZE (type), 1))
964 unsigned int type_align = TYPE_ALIGN (type);
965 tree dsize = DECL_SIZE (field);
966 HOST_WIDE_INT field_size = tree_low_cst (dsize, 1);
967 HOST_WIDE_INT offset = tree_low_cst (rli->offset, 0);
968 HOST_WIDE_INT bit_offset = tree_low_cst (rli->bitpos, 0);
970 #ifdef ADJUST_FIELD_ALIGN
971 if (! TYPE_USER_ALIGN (type))
972 type_align = ADJUST_FIELD_ALIGN (field, type_align);
975 if (maximum_field_alignment != 0)
976 type_align = MIN (type_align, maximum_field_alignment);
977 /* ??? This test is opposite the test in the containing if
978 statement, so this code is unreachable currently. */
979 else if (DECL_PACKED (field))
980 type_align = MIN (type_align, BITS_PER_UNIT);
982 /* A bit field may not span the unit of alignment of its type.
983 Advance to next boundary if necessary. */
984 if (excess_unit_span (offset, bit_offset, field_size, type_align, type))
985 rli->bitpos = round_up (rli->bitpos, type_align);
987 TYPE_USER_ALIGN (rli->t) |= TYPE_USER_ALIGN (type);
991 /* See the docs for TARGET_MS_BITFIELD_LAYOUT_P for details.
993 When a bit field is inserted into a packed record, the whole
994 size of the underlying type is used by one or more same-size
995 adjacent bitfields. (That is, if its long:3, 32 bits is
996 used in the record, and any additional adjacent long bitfields are
997 packed into the same chunk of 32 bits. However, if the size
998 changes, a new field of that size is allocated.) In an unpacked
999 record, this is the same as using alignment, but not equivalent
1002 Note: for compatibility, we use the type size, not the type alignment
1003 to determine alignment, since that matches the documentation */
1005 if ((* targetm.ms_bitfield_layout_p) (rli->t)
1006 && ((DECL_BIT_FIELD_TYPE (field) && ! DECL_PACKED (field))
1007 || (rli->prev_field && ! DECL_PACKED (rli->prev_field))))
1009 /* At this point, either the prior or current are bitfields,
1010 (possibly both), and we're dealing with MS packing. */
1011 tree prev_saved = rli->prev_field;
1013 /* Is the prior field a bitfield? If so, handle "runs" of same
1014 type size fields. */
1015 if (rli->prev_field /* necessarily a bitfield if it exists. */)
1017 /* If both are bitfields, nonzero, and the same size, this is
1018 the middle of a run. Zero declared size fields are special
1019 and handled as "end of run". (Note: it's nonzero declared
1020 size, but equal type sizes!) (Since we know that both
1021 the current and previous fields are bitfields by the
1022 time we check it, DECL_SIZE must be present for both.) */
1023 if (DECL_BIT_FIELD_TYPE (field)
1024 && !integer_zerop (DECL_SIZE (field))
1025 && !integer_zerop (DECL_SIZE (rli->prev_field))
1026 && host_integerp (DECL_SIZE (rli->prev_field), 0)
1027 && host_integerp (TYPE_SIZE (type), 0)
1028 && simple_cst_equal (TYPE_SIZE (type),
1029 TYPE_SIZE (TREE_TYPE (rli->prev_field))))
1031 /* We're in the middle of a run of equal type size fields; make
1032 sure we realign if we run out of bits. (Not decl size,
1034 HOST_WIDE_INT bitsize = tree_low_cst (DECL_SIZE (field), 0);
1036 if (rli->remaining_in_alignment < bitsize)
1038 /* out of bits; bump up to next 'word'. */
1039 rli->offset = DECL_FIELD_OFFSET (rli->prev_field);
1041 = size_binop (PLUS_EXPR, TYPE_SIZE (type),
1042 DECL_FIELD_BIT_OFFSET (rli->prev_field));
1043 rli->prev_field = field;
1044 rli->remaining_in_alignment
1045 = tree_low_cst (TYPE_SIZE (type), 0);
1048 rli->remaining_in_alignment -= bitsize;
1052 /* End of a run: if leaving a run of bitfields of the same type
1053 size, we have to "use up" the rest of the bits of the type
1056 Compute the new position as the sum of the size for the prior
1057 type and where we first started working on that type.
1058 Note: since the beginning of the field was aligned then
1059 of course the end will be too. No round needed. */
1061 if (!integer_zerop (DECL_SIZE (rli->prev_field)))
1063 tree type_size = TYPE_SIZE (TREE_TYPE (rli->prev_field));
1066 = size_binop (PLUS_EXPR, type_size,
1067 DECL_FIELD_BIT_OFFSET (rli->prev_field));
1070 /* We "use up" size zero fields; the code below should behave
1071 as if the prior field was not a bitfield. */
1074 /* Cause a new bitfield to be captured, either this time (if
1075 currently a bitfield) or next time we see one. */
1076 if (!DECL_BIT_FIELD_TYPE(field)
1077 || integer_zerop (DECL_SIZE (field)))
1078 rli->prev_field = NULL;
1081 rli->offset_align = tree_low_cst (TYPE_SIZE (type), 0);
1082 normalize_rli (rli);
1085 /* If we're starting a new run of same size type bitfields
1086 (or a run of non-bitfields), set up the "first of the run"
1089 That is, if the current field is not a bitfield, or if there
1090 was a prior bitfield the type sizes differ, or if there wasn't
1091 a prior bitfield the size of the current field is nonzero.
1093 Note: we must be sure to test ONLY the type size if there was
1094 a prior bitfield and ONLY for the current field being zero if
1097 if (!DECL_BIT_FIELD_TYPE (field)
1098 || ( prev_saved != NULL
1099 ? !simple_cst_equal (TYPE_SIZE (type),
1100 TYPE_SIZE (TREE_TYPE (prev_saved)))
1101 : !integer_zerop (DECL_SIZE (field)) ))
1103 /* Never smaller than a byte for compatibility. */
1104 unsigned int type_align = BITS_PER_UNIT;
1106 /* (When not a bitfield), we could be seeing a flex array (with
1107 no DECL_SIZE). Since we won't be using remaining_in_alignment
1108 until we see a bitfield (and come by here again) we just skip
1110 if (DECL_SIZE (field) != NULL
1111 && host_integerp (TYPE_SIZE (TREE_TYPE (field)), 0)
1112 && host_integerp (DECL_SIZE (field), 0))
1113 rli->remaining_in_alignment
1114 = tree_low_cst (TYPE_SIZE (TREE_TYPE(field)), 0)
1115 - tree_low_cst (DECL_SIZE (field), 0);
1117 /* Now align (conventionally) for the new type. */
1118 if (!DECL_PACKED(field))
1119 type_align = MAX(TYPE_ALIGN (type), type_align);
1122 && DECL_BIT_FIELD_TYPE (prev_saved)
1123 /* If the previous bit-field is zero-sized, we've already
1124 accounted for its alignment needs (or ignored it, if
1125 appropriate) while placing it. */
1126 && ! integer_zerop (DECL_SIZE (prev_saved)))
1127 type_align = MAX (type_align,
1128 TYPE_ALIGN (TREE_TYPE (prev_saved)));
1130 if (maximum_field_alignment != 0)
1131 type_align = MIN (type_align, maximum_field_alignment);
1133 rli->bitpos = round_up (rli->bitpos, type_align);
1135 /* If we really aligned, don't allow subsequent bitfields
1137 rli->prev_field = NULL;
1141 /* Offset so far becomes the position of this field after normalizing. */
1142 normalize_rli (rli);
1143 DECL_FIELD_OFFSET (field) = rli->offset;
1144 DECL_FIELD_BIT_OFFSET (field) = rli->bitpos;
1145 SET_DECL_OFFSET_ALIGN (field, rli->offset_align);
1147 /* If this field ended up more aligned than we thought it would be (we
1148 approximate this by seeing if its position changed), lay out the field
1149 again; perhaps we can use an integral mode for it now. */
1150 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field)))
1151 actual_align = (tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1)
1152 & - tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1));
1153 else if (integer_zerop (DECL_FIELD_OFFSET (field)))
1154 actual_align = BIGGEST_ALIGNMENT;
1155 else if (host_integerp (DECL_FIELD_OFFSET (field), 1))
1156 actual_align = (BITS_PER_UNIT
1157 * (tree_low_cst (DECL_FIELD_OFFSET (field), 1)
1158 & - tree_low_cst (DECL_FIELD_OFFSET (field), 1)));
1160 actual_align = DECL_OFFSET_ALIGN (field);
1162 if (known_align != actual_align)
1163 layout_decl (field, actual_align);
1165 /* Only the MS bitfields use this. */
1166 if (rli->prev_field == NULL && DECL_BIT_FIELD_TYPE(field))
1167 rli->prev_field = field;
1169 /* Now add size of this field to the size of the record. If the size is
1170 not constant, treat the field as being a multiple of bytes and just
1171 adjust the offset, resetting the bit position. Otherwise, apportion the
1172 size amongst the bit position and offset. First handle the case of an
1173 unspecified size, which can happen when we have an invalid nested struct
1174 definition, such as struct j { struct j { int i; } }. The error message
1175 is printed in finish_struct. */
1176 if (DECL_SIZE (field) == 0)
1178 else if (TREE_CODE (DECL_SIZE_UNIT (field)) != INTEGER_CST
1179 || TREE_CONSTANT_OVERFLOW (DECL_SIZE_UNIT (field)))
1182 = size_binop (PLUS_EXPR, rli->offset,
1184 size_binop (CEIL_DIV_EXPR, rli->bitpos,
1185 bitsize_unit_node)));
1187 = size_binop (PLUS_EXPR, rli->offset, DECL_SIZE_UNIT (field));
1188 rli->bitpos = bitsize_zero_node;
1189 rli->offset_align = MIN (rli->offset_align, desired_align);
1193 rli->bitpos = size_binop (PLUS_EXPR, rli->bitpos, DECL_SIZE (field));
1194 normalize_rli (rli);
1198 /* Assuming that all the fields have been laid out, this function uses
1199 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
1200 indicated by RLI. */
1203 finalize_record_size (record_layout_info rli)
1205 tree unpadded_size, unpadded_size_unit;
1207 /* Now we want just byte and bit offsets, so set the offset alignment
1208 to be a byte and then normalize. */
1209 rli->offset_align = BITS_PER_UNIT;
1210 normalize_rli (rli);
1212 /* Determine the desired alignment. */
1213 #ifdef ROUND_TYPE_ALIGN
1214 TYPE_ALIGN (rli->t) = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t),
1217 TYPE_ALIGN (rli->t) = MAX (TYPE_ALIGN (rli->t), rli->record_align);
1220 /* Compute the size so far. Be sure to allow for extra bits in the
1221 size in bytes. We have guaranteed above that it will be no more
1222 than a single byte. */
1223 unpadded_size = rli_size_so_far (rli);
1224 unpadded_size_unit = rli_size_unit_so_far (rli);
1225 if (! integer_zerop (rli->bitpos))
1227 = size_binop (PLUS_EXPR, unpadded_size_unit, size_one_node);
1229 /* Round the size up to be a multiple of the required alignment. */
1230 TYPE_SIZE (rli->t) = round_up (unpadded_size, TYPE_ALIGN (rli->t));
1231 TYPE_SIZE_UNIT (rli->t) = round_up (unpadded_size_unit,
1232 TYPE_ALIGN (rli->t) / BITS_PER_UNIT);
1234 if (warn_padded && TREE_CONSTANT (unpadded_size)
1235 && simple_cst_equal (unpadded_size, TYPE_SIZE (rli->t)) == 0)
1236 warning ("padding struct size to alignment boundary");
1238 if (warn_packed && TREE_CODE (rli->t) == RECORD_TYPE
1239 && TYPE_PACKED (rli->t) && ! rli->packed_maybe_necessary
1240 && TREE_CONSTANT (unpadded_size))
1244 #ifdef ROUND_TYPE_ALIGN
1246 = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t), rli->unpacked_align);
1248 rli->unpacked_align = MAX (TYPE_ALIGN (rli->t), rli->unpacked_align);
1251 unpacked_size = round_up (TYPE_SIZE (rli->t), rli->unpacked_align);
1252 if (simple_cst_equal (unpacked_size, TYPE_SIZE (rli->t)))
1254 TYPE_PACKED (rli->t) = 0;
1256 if (TYPE_NAME (rli->t))
1260 if (TREE_CODE (TYPE_NAME (rli->t)) == IDENTIFIER_NODE)
1261 name = IDENTIFIER_POINTER (TYPE_NAME (rli->t));
1263 name = IDENTIFIER_POINTER (DECL_NAME (TYPE_NAME (rli->t)));
1265 if (STRICT_ALIGNMENT)
1266 warning ("packed attribute causes inefficient alignment for `%s'", name);
1268 warning ("packed attribute is unnecessary for `%s'", name);
1272 if (STRICT_ALIGNMENT)
1273 warning ("packed attribute causes inefficient alignment");
1275 warning ("packed attribute is unnecessary");
1281 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
1284 compute_record_mode (tree type)
1287 enum machine_mode mode = VOIDmode;
1289 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
1290 However, if possible, we use a mode that fits in a register
1291 instead, in order to allow for better optimization down the
1293 TYPE_MODE (type) = BLKmode;
1295 if (! host_integerp (TYPE_SIZE (type), 1))
1298 /* A record which has any BLKmode members must itself be
1299 BLKmode; it can't go in a register. Unless the member is
1300 BLKmode only because it isn't aligned. */
1301 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1303 if (TREE_CODE (field) != FIELD_DECL)
1306 if (TREE_CODE (TREE_TYPE (field)) == ERROR_MARK
1307 || (TYPE_MODE (TREE_TYPE (field)) == BLKmode
1308 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field))
1309 && !(TYPE_SIZE (TREE_TYPE (field)) != 0
1310 && integer_zerop (TYPE_SIZE (TREE_TYPE (field)))))
1311 || ! host_integerp (bit_position (field), 1)
1312 || DECL_SIZE (field) == 0
1313 || ! host_integerp (DECL_SIZE (field), 1))
1316 /* If this field is the whole struct, remember its mode so
1317 that, say, we can put a double in a class into a DF
1318 register instead of forcing it to live in the stack. */
1319 if (simple_cst_equal (TYPE_SIZE (type), DECL_SIZE (field)))
1320 mode = DECL_MODE (field);
1322 #ifdef MEMBER_TYPE_FORCES_BLK
1323 /* With some targets, eg. c4x, it is sub-optimal
1324 to access an aligned BLKmode structure as a scalar. */
1326 if (MEMBER_TYPE_FORCES_BLK (field, mode))
1328 #endif /* MEMBER_TYPE_FORCES_BLK */
1331 /* If we only have one real field; use its mode. This only applies to
1332 RECORD_TYPE. This does not apply to unions. */
1333 if (TREE_CODE (type) == RECORD_TYPE && mode != VOIDmode)
1334 TYPE_MODE (type) = mode;
1336 TYPE_MODE (type) = mode_for_size_tree (TYPE_SIZE (type), MODE_INT, 1);
1338 /* If structure's known alignment is less than what the scalar
1339 mode would need, and it matters, then stick with BLKmode. */
1340 if (TYPE_MODE (type) != BLKmode
1342 && ! (TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT
1343 || TYPE_ALIGN (type) >= GET_MODE_ALIGNMENT (TYPE_MODE (type))))
1345 /* If this is the only reason this type is BLKmode, then
1346 don't force containing types to be BLKmode. */
1347 TYPE_NO_FORCE_BLK (type) = 1;
1348 TYPE_MODE (type) = BLKmode;
1352 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1356 finalize_type_size (tree type)
1358 /* Normally, use the alignment corresponding to the mode chosen.
1359 However, where strict alignment is not required, avoid
1360 over-aligning structures, since most compilers do not do this
1363 if (TYPE_MODE (type) != BLKmode && TYPE_MODE (type) != VOIDmode
1364 && (STRICT_ALIGNMENT
1365 || (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE
1366 && TREE_CODE (type) != QUAL_UNION_TYPE
1367 && TREE_CODE (type) != ARRAY_TYPE)))
1369 TYPE_ALIGN (type) = GET_MODE_ALIGNMENT (TYPE_MODE (type));
1370 TYPE_USER_ALIGN (type) = 0;
1373 /* Do machine-dependent extra alignment. */
1374 #ifdef ROUND_TYPE_ALIGN
1376 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (type), BITS_PER_UNIT);
1379 /* If we failed to find a simple way to calculate the unit size
1380 of the type, find it by division. */
1381 if (TYPE_SIZE_UNIT (type) == 0 && TYPE_SIZE (type) != 0)
1382 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1383 result will fit in sizetype. We will get more efficient code using
1384 sizetype, so we force a conversion. */
1385 TYPE_SIZE_UNIT (type)
1386 = convert (sizetype,
1387 size_binop (FLOOR_DIV_EXPR, TYPE_SIZE (type),
1388 bitsize_unit_node));
1390 if (TYPE_SIZE (type) != 0)
1392 TYPE_SIZE (type) = round_up (TYPE_SIZE (type), TYPE_ALIGN (type));
1393 TYPE_SIZE_UNIT (type)
1394 = round_up (TYPE_SIZE_UNIT (type), TYPE_ALIGN (type) / BITS_PER_UNIT);
1397 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1398 if (TYPE_SIZE (type) != 0 && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
1399 TYPE_SIZE (type) = variable_size (TYPE_SIZE (type));
1400 if (TYPE_SIZE_UNIT (type) != 0
1401 && TREE_CODE (TYPE_SIZE_UNIT (type)) != INTEGER_CST)
1402 TYPE_SIZE_UNIT (type) = variable_size (TYPE_SIZE_UNIT (type));
1404 /* Also layout any other variants of the type. */
1405 if (TYPE_NEXT_VARIANT (type)
1406 || type != TYPE_MAIN_VARIANT (type))
1409 /* Record layout info of this variant. */
1410 tree size = TYPE_SIZE (type);
1411 tree size_unit = TYPE_SIZE_UNIT (type);
1412 unsigned int align = TYPE_ALIGN (type);
1413 unsigned int user_align = TYPE_USER_ALIGN (type);
1414 enum machine_mode mode = TYPE_MODE (type);
1416 /* Copy it into all variants. */
1417 for (variant = TYPE_MAIN_VARIANT (type);
1419 variant = TYPE_NEXT_VARIANT (variant))
1421 TYPE_SIZE (variant) = size;
1422 TYPE_SIZE_UNIT (variant) = size_unit;
1423 TYPE_ALIGN (variant) = align;
1424 TYPE_USER_ALIGN (variant) = user_align;
1425 TYPE_MODE (variant) = mode;
1430 /* Do all of the work required to layout the type indicated by RLI,
1431 once the fields have been laid out. This function will call `free'
1432 for RLI, unless FREE_P is false. Passing a value other than false
1433 for FREE_P is bad practice; this option only exists to support the
1437 finish_record_layout (record_layout_info rli, int free_p)
1439 /* Compute the final size. */
1440 finalize_record_size (rli);
1442 /* Compute the TYPE_MODE for the record. */
1443 compute_record_mode (rli->t);
1445 /* Perform any last tweaks to the TYPE_SIZE, etc. */
1446 finalize_type_size (rli->t);
1448 /* Lay out any static members. This is done now because their type
1449 may use the record's type. */
1450 while (rli->pending_statics)
1452 layout_decl (TREE_VALUE (rli->pending_statics), 0);
1453 rli->pending_statics = TREE_CHAIN (rli->pending_statics);
1462 /* Finish processing a builtin RECORD_TYPE type TYPE. It's name is
1463 NAME, its fields are chained in reverse on FIELDS.
1465 If ALIGN_TYPE is non-null, it is given the same alignment as
1469 finish_builtin_struct (tree type, const char *name, tree fields,
1474 for (tail = NULL_TREE; fields; tail = fields, fields = next)
1476 DECL_FIELD_CONTEXT (fields) = type;
1477 next = TREE_CHAIN (fields);
1478 TREE_CHAIN (fields) = tail;
1480 TYPE_FIELDS (type) = tail;
1484 TYPE_ALIGN (type) = TYPE_ALIGN (align_type);
1485 TYPE_USER_ALIGN (type) = TYPE_USER_ALIGN (align_type);
1489 #if 0 /* not yet, should get fixed properly later */
1490 TYPE_NAME (type) = make_type_decl (get_identifier (name), type);
1492 TYPE_NAME (type) = build_decl (TYPE_DECL, get_identifier (name), type);
1494 TYPE_STUB_DECL (type) = TYPE_NAME (type);
1495 layout_decl (TYPE_NAME (type), 0);
1498 /* Calculate the mode, size, and alignment for TYPE.
1499 For an array type, calculate the element separation as well.
1500 Record TYPE on the chain of permanent or temporary types
1501 so that dbxout will find out about it.
1503 TYPE_SIZE of a type is nonzero if the type has been laid out already.
1504 layout_type does nothing on such a type.
1506 If the type is incomplete, its TYPE_SIZE remains zero. */
1509 layout_type (tree type)
1514 /* Do nothing if type has been laid out before. */
1515 if (TYPE_SIZE (type))
1518 switch (TREE_CODE (type))
1521 /* This kind of type is the responsibility
1522 of the language-specific code. */
1525 case BOOLEAN_TYPE: /* Used for Java, Pascal, and Chill. */
1526 if (TYPE_PRECISION (type) == 0)
1527 TYPE_PRECISION (type) = 1; /* default to one byte/boolean. */
1529 /* ... fall through ... */
1534 if (TREE_CODE (TYPE_MIN_VALUE (type)) == INTEGER_CST
1535 && tree_int_cst_sgn (TYPE_MIN_VALUE (type)) >= 0)
1536 TREE_UNSIGNED (type) = 1;
1538 TYPE_MODE (type) = smallest_mode_for_size (TYPE_PRECISION (type),
1540 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1541 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1545 TYPE_MODE (type) = mode_for_size (TYPE_PRECISION (type), MODE_FLOAT, 0);
1546 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1547 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1551 TREE_UNSIGNED (type) = TREE_UNSIGNED (TREE_TYPE (type));
1553 = mode_for_size (2 * TYPE_PRECISION (TREE_TYPE (type)),
1554 (TREE_CODE (TREE_TYPE (type)) == INTEGER_TYPE
1555 ? MODE_COMPLEX_INT : MODE_COMPLEX_FLOAT),
1557 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1558 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1565 subtype = TREE_TYPE (type);
1566 TREE_UNSIGNED (type) = TREE_UNSIGNED (subtype);
1567 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1568 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1573 /* This is an incomplete type and so doesn't have a size. */
1574 TYPE_ALIGN (type) = 1;
1575 TYPE_USER_ALIGN (type) = 0;
1576 TYPE_MODE (type) = VOIDmode;
1580 TYPE_SIZE (type) = bitsize_int (POINTER_SIZE);
1581 TYPE_SIZE_UNIT (type) = size_int (POINTER_SIZE / BITS_PER_UNIT);
1582 /* A pointer might be MODE_PARTIAL_INT,
1583 but ptrdiff_t must be integral. */
1584 TYPE_MODE (type) = mode_for_size (POINTER_SIZE, MODE_INT, 0);
1589 TYPE_MODE (type) = mode_for_size (2 * POINTER_SIZE, MODE_INT, 0);
1590 TYPE_SIZE (type) = bitsize_int (2 * POINTER_SIZE);
1591 TYPE_SIZE_UNIT (type) = size_int ((2 * POINTER_SIZE) / BITS_PER_UNIT);
1595 case REFERENCE_TYPE:
1598 enum machine_mode mode = ((TREE_CODE (type) == REFERENCE_TYPE
1599 && reference_types_internal)
1600 ? Pmode : TYPE_MODE (type));
1602 int nbits = GET_MODE_BITSIZE (mode);
1604 TYPE_SIZE (type) = bitsize_int (nbits);
1605 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (mode));
1606 TREE_UNSIGNED (type) = 1;
1607 TYPE_PRECISION (type) = nbits;
1613 tree index = TYPE_DOMAIN (type);
1614 tree element = TREE_TYPE (type);
1616 build_pointer_type (element);
1618 /* We need to know both bounds in order to compute the size. */
1619 if (index && TYPE_MAX_VALUE (index) && TYPE_MIN_VALUE (index)
1620 && TYPE_SIZE (element))
1622 tree ub = TYPE_MAX_VALUE (index);
1623 tree lb = TYPE_MIN_VALUE (index);
1627 /* The initial subtraction should happen in the original type so
1628 that (possible) negative values are handled appropriately. */
1629 length = size_binop (PLUS_EXPR, size_one_node,
1631 fold (build (MINUS_EXPR,
1635 /* Special handling for arrays of bits (for Chill). */
1636 element_size = TYPE_SIZE (element);
1637 if (TYPE_PACKED (type) && INTEGRAL_TYPE_P (element)
1638 && (integer_zerop (TYPE_MAX_VALUE (element))
1639 || integer_onep (TYPE_MAX_VALUE (element)))
1640 && host_integerp (TYPE_MIN_VALUE (element), 1))
1642 HOST_WIDE_INT maxvalue
1643 = tree_low_cst (TYPE_MAX_VALUE (element), 1);
1644 HOST_WIDE_INT minvalue
1645 = tree_low_cst (TYPE_MIN_VALUE (element), 1);
1647 if (maxvalue - minvalue == 1
1648 && (maxvalue == 1 || maxvalue == 0))
1649 element_size = integer_one_node;
1652 /* If neither bound is a constant and sizetype is signed, make
1653 sure the size is never negative. We should really do this
1654 if *either* bound is non-constant, but this is the best
1655 compromise between C and Ada. */
1656 if (! TREE_UNSIGNED (sizetype)
1657 && TREE_CODE (TYPE_MIN_VALUE (index)) != INTEGER_CST
1658 && TREE_CODE (TYPE_MAX_VALUE (index)) != INTEGER_CST)
1659 length = size_binop (MAX_EXPR, length, size_zero_node);
1661 TYPE_SIZE (type) = size_binop (MULT_EXPR, element_size,
1662 convert (bitsizetype, length));
1664 /* If we know the size of the element, calculate the total
1665 size directly, rather than do some division thing below.
1666 This optimization helps Fortran assumed-size arrays
1667 (where the size of the array is determined at runtime)
1669 Note that we can't do this in the case where the size of
1670 the elements is one bit since TYPE_SIZE_UNIT cannot be
1671 set correctly in that case. */
1672 if (TYPE_SIZE_UNIT (element) != 0 && ! integer_onep (element_size))
1673 TYPE_SIZE_UNIT (type)
1674 = size_binop (MULT_EXPR, TYPE_SIZE_UNIT (element), length);
1677 /* Now round the alignment and size,
1678 using machine-dependent criteria if any. */
1680 #ifdef ROUND_TYPE_ALIGN
1682 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (element), BITS_PER_UNIT);
1684 TYPE_ALIGN (type) = MAX (TYPE_ALIGN (element), BITS_PER_UNIT);
1686 TYPE_USER_ALIGN (type) = TYPE_USER_ALIGN (element);
1687 TYPE_MODE (type) = BLKmode;
1688 if (TYPE_SIZE (type) != 0
1689 #ifdef MEMBER_TYPE_FORCES_BLK
1690 && ! MEMBER_TYPE_FORCES_BLK (type, VOIDmode)
1692 /* BLKmode elements force BLKmode aggregate;
1693 else extract/store fields may lose. */
1694 && (TYPE_MODE (TREE_TYPE (type)) != BLKmode
1695 || TYPE_NO_FORCE_BLK (TREE_TYPE (type))))
1697 /* One-element arrays get the component type's mode. */
1698 if (simple_cst_equal (TYPE_SIZE (type),
1699 TYPE_SIZE (TREE_TYPE (type))))
1700 TYPE_MODE (type) = TYPE_MODE (TREE_TYPE (type));
1703 = mode_for_size_tree (TYPE_SIZE (type), MODE_INT, 1);
1705 if (TYPE_MODE (type) != BLKmode
1706 && STRICT_ALIGNMENT && TYPE_ALIGN (type) < BIGGEST_ALIGNMENT
1707 && TYPE_ALIGN (type) < GET_MODE_ALIGNMENT (TYPE_MODE (type))
1708 && TYPE_MODE (type) != BLKmode)
1710 TYPE_NO_FORCE_BLK (type) = 1;
1711 TYPE_MODE (type) = BLKmode;
1719 case QUAL_UNION_TYPE:
1722 record_layout_info rli;
1724 /* Initialize the layout information. */
1725 rli = start_record_layout (type);
1727 /* If this is a QUAL_UNION_TYPE, we want to process the fields
1728 in the reverse order in building the COND_EXPR that denotes
1729 its size. We reverse them again later. */
1730 if (TREE_CODE (type) == QUAL_UNION_TYPE)
1731 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
1733 /* Place all the fields. */
1734 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1735 place_field (rli, field);
1737 if (TREE_CODE (type) == QUAL_UNION_TYPE)
1738 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
1740 if (lang_adjust_rli)
1741 (*lang_adjust_rli) (rli);
1743 /* Finish laying out the record. */
1744 finish_record_layout (rli, /*free_p=*/true);
1748 case SET_TYPE: /* Used by Chill and Pascal. */
1749 if (TREE_CODE (TYPE_MAX_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST
1750 || TREE_CODE (TYPE_MIN_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST)
1754 #ifndef SET_WORD_SIZE
1755 #define SET_WORD_SIZE BITS_PER_WORD
1757 unsigned int alignment
1758 = set_alignment ? set_alignment : SET_WORD_SIZE;
1759 HOST_WIDE_INT size_in_bits
1760 = (tree_low_cst (TYPE_MAX_VALUE (TYPE_DOMAIN (type)), 0)
1761 - tree_low_cst (TYPE_MIN_VALUE (TYPE_DOMAIN (type)), 0) + 1);
1762 HOST_WIDE_INT rounded_size
1763 = ((size_in_bits + alignment - 1) / alignment) * alignment;
1765 if (rounded_size > (int) alignment)
1766 TYPE_MODE (type) = BLKmode;
1768 TYPE_MODE (type) = mode_for_size (alignment, MODE_INT, 1);
1770 TYPE_SIZE (type) = bitsize_int (rounded_size);
1771 TYPE_SIZE_UNIT (type) = size_int (rounded_size / BITS_PER_UNIT);
1772 TYPE_ALIGN (type) = alignment;
1773 TYPE_USER_ALIGN (type) = 0;
1774 TYPE_PRECISION (type) = size_in_bits;
1779 /* The size may vary in different languages, so the language front end
1780 should fill in the size. */
1781 TYPE_ALIGN (type) = BIGGEST_ALIGNMENT;
1782 TYPE_USER_ALIGN (type) = 0;
1783 TYPE_MODE (type) = BLKmode;
1790 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
1791 records and unions, finish_record_layout already called this
1793 if (TREE_CODE (type) != RECORD_TYPE
1794 && TREE_CODE (type) != UNION_TYPE
1795 && TREE_CODE (type) != QUAL_UNION_TYPE)
1796 finalize_type_size (type);
1798 /* If this type is created before sizetype has been permanently set,
1799 record it so set_sizetype can fix it up. */
1801 early_type_list = tree_cons (NULL_TREE, type, early_type_list);
1803 /* If an alias set has been set for this aggregate when it was incomplete,
1804 force it into alias set 0.
1805 This is too conservative, but we cannot call record_component_aliases
1806 here because some frontends still change the aggregates after
1808 if (AGGREGATE_TYPE_P (type) && TYPE_ALIAS_SET_KNOWN_P (type))
1809 TYPE_ALIAS_SET (type) = 0;
1812 /* Create and return a type for signed integers of PRECISION bits. */
1815 make_signed_type (int precision)
1817 tree type = make_node (INTEGER_TYPE);
1819 TYPE_PRECISION (type) = precision;
1821 fixup_signed_type (type);
1825 /* Create and return a type for unsigned integers of PRECISION bits. */
1828 make_unsigned_type (int precision)
1830 tree type = make_node (INTEGER_TYPE);
1832 TYPE_PRECISION (type) = precision;
1834 fixup_unsigned_type (type);
1838 /* Initialize sizetype and bitsizetype to a reasonable and temporary
1839 value to enable integer types to be created. */
1842 initialize_sizetypes (void)
1844 tree t = make_node (INTEGER_TYPE);
1846 /* Set this so we do something reasonable for the build_int_2 calls
1848 integer_type_node = t;
1850 TYPE_MODE (t) = SImode;
1851 TYPE_ALIGN (t) = GET_MODE_ALIGNMENT (SImode);
1852 TYPE_USER_ALIGN (t) = 0;
1853 TYPE_SIZE (t) = build_int_2 (GET_MODE_BITSIZE (SImode), 0);
1854 TYPE_SIZE_UNIT (t) = build_int_2 (GET_MODE_SIZE (SImode), 0);
1855 TREE_UNSIGNED (t) = 1;
1856 TYPE_PRECISION (t) = GET_MODE_BITSIZE (SImode);
1857 TYPE_MIN_VALUE (t) = build_int_2 (0, 0);
1858 TYPE_IS_SIZETYPE (t) = 1;
1860 /* 1000 avoids problems with possible overflow and is certainly
1861 larger than any size value we'd want to be storing. */
1862 TYPE_MAX_VALUE (t) = build_int_2 (1000, 0);
1864 /* These two must be different nodes because of the caching done in
1867 bitsizetype = copy_node (t);
1868 integer_type_node = 0;
1871 /* Set sizetype to TYPE, and initialize *sizetype accordingly.
1872 Also update the type of any standard type's sizes made so far. */
1875 set_sizetype (tree type)
1877 int oprecision = TYPE_PRECISION (type);
1878 /* The *bitsizetype types use a precision that avoids overflows when
1879 calculating signed sizes / offsets in bits. However, when
1880 cross-compiling from a 32 bit to a 64 bit host, we are limited to 64 bit
1882 int precision = MIN (oprecision + BITS_PER_UNIT_LOG + 1,
1883 2 * HOST_BITS_PER_WIDE_INT);
1890 /* Make copies of nodes since we'll be setting TYPE_IS_SIZETYPE. */
1891 sizetype = copy_node (type);
1892 TYPE_DOMAIN (sizetype) = type;
1893 TYPE_IS_SIZETYPE (sizetype) = 1;
1894 bitsizetype = make_node (INTEGER_TYPE);
1895 TYPE_NAME (bitsizetype) = TYPE_NAME (type);
1896 TYPE_PRECISION (bitsizetype) = precision;
1897 TYPE_IS_SIZETYPE (bitsizetype) = 1;
1899 if (TREE_UNSIGNED (type))
1900 fixup_unsigned_type (bitsizetype);
1902 fixup_signed_type (bitsizetype);
1904 layout_type (bitsizetype);
1906 if (TREE_UNSIGNED (type))
1908 usizetype = sizetype;
1909 ubitsizetype = bitsizetype;
1910 ssizetype = copy_node (make_signed_type (oprecision));
1911 sbitsizetype = copy_node (make_signed_type (precision));
1915 ssizetype = sizetype;
1916 sbitsizetype = bitsizetype;
1917 usizetype = copy_node (make_unsigned_type (oprecision));
1918 ubitsizetype = copy_node (make_unsigned_type (precision));
1921 TYPE_NAME (bitsizetype) = get_identifier ("bit_size_type");
1923 /* Show is a sizetype, is a main type, and has no pointers to it. */
1924 for (i = 0; i < ARRAY_SIZE (sizetype_tab); i++)
1926 TYPE_IS_SIZETYPE (sizetype_tab[i]) = 1;
1927 TYPE_MAIN_VARIANT (sizetype_tab[i]) = sizetype_tab[i];
1928 TYPE_NEXT_VARIANT (sizetype_tab[i]) = 0;
1929 TYPE_POINTER_TO (sizetype_tab[i]) = 0;
1930 TYPE_REFERENCE_TO (sizetype_tab[i]) = 0;
1933 /* Go down each of the types we already made and set the proper type
1934 for the sizes in them. */
1935 for (t = early_type_list; t != 0; t = TREE_CHAIN (t))
1937 if (TREE_CODE (TREE_VALUE (t)) != INTEGER_TYPE
1938 && TREE_CODE (TREE_VALUE (t)) != BOOLEAN_TYPE)
1941 TREE_TYPE (TYPE_SIZE (TREE_VALUE (t))) = bitsizetype;
1942 TREE_TYPE (TYPE_SIZE_UNIT (TREE_VALUE (t))) = sizetype;
1945 early_type_list = 0;
1949 /* TYPE is an integral type, i.e., an INTEGRAL_TYPE, ENUMERAL_TYPE,
1950 BOOLEAN_TYPE, or CHAR_TYPE. Set TYPE_MIN_VALUE and TYPE_MAX_VALUE
1951 for TYPE, based on the PRECISION and whether or not the TYPE
1952 IS_UNSIGNED. PRECISION need not correspond to a width supported
1953 natively by the hardware; for example, on a machine with 8-bit,
1954 16-bit, and 32-bit register modes, PRECISION might be 7, 23, or
1958 set_min_and_max_values_for_integral_type (tree type,
1967 min_value = build_int_2 (0, 0);
1969 = build_int_2 (precision - HOST_BITS_PER_WIDE_INT >= 0
1970 ? -1 : ((HOST_WIDE_INT) 1 << precision) - 1,
1971 precision - HOST_BITS_PER_WIDE_INT > 0
1972 ? ((unsigned HOST_WIDE_INT) ~0
1973 >> (HOST_BITS_PER_WIDE_INT
1974 - (precision - HOST_BITS_PER_WIDE_INT)))
1980 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1981 ? 0 : (HOST_WIDE_INT) (-1) << (precision - 1)),
1982 (((HOST_WIDE_INT) (-1)
1983 << (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1984 ? precision - HOST_BITS_PER_WIDE_INT - 1
1987 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1988 ? -1 : ((HOST_WIDE_INT) 1 << (precision - 1)) - 1),
1989 (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1990 ? (((HOST_WIDE_INT) 1
1991 << (precision - HOST_BITS_PER_WIDE_INT - 1))) - 1
1995 TREE_TYPE (min_value) = type;
1996 TREE_TYPE (max_value) = type;
1997 TYPE_MIN_VALUE (type) = min_value;
1998 TYPE_MAX_VALUE (type) = max_value;
2001 /* Set the extreme values of TYPE based on its precision in bits,
2002 then lay it out. Used when make_signed_type won't do
2003 because the tree code is not INTEGER_TYPE.
2004 E.g. for Pascal, when the -fsigned-char option is given. */
2007 fixup_signed_type (tree type)
2009 int precision = TYPE_PRECISION (type);
2011 /* We can not represent properly constants greater then
2012 2 * HOST_BITS_PER_WIDE_INT, still we need the types
2013 as they are used by i386 vector extensions and friends. */
2014 if (precision > HOST_BITS_PER_WIDE_INT * 2)
2015 precision = HOST_BITS_PER_WIDE_INT * 2;
2017 set_min_and_max_values_for_integral_type (type, precision,
2018 /*is_unsigned=*/false);
2020 /* Lay out the type: set its alignment, size, etc. */
2024 /* Set the extreme values of TYPE based on its precision in bits,
2025 then lay it out. This is used both in `make_unsigned_type'
2026 and for enumeral types. */
2029 fixup_unsigned_type (tree type)
2031 int precision = TYPE_PRECISION (type);
2033 /* We can not represent properly constants greater then
2034 2 * HOST_BITS_PER_WIDE_INT, still we need the types
2035 as they are used by i386 vector extensions and friends. */
2036 if (precision > HOST_BITS_PER_WIDE_INT * 2)
2037 precision = HOST_BITS_PER_WIDE_INT * 2;
2039 set_min_and_max_values_for_integral_type (type, precision,
2040 /*is_unsigned=*/true);
2042 /* Lay out the type: set its alignment, size, etc. */
2046 /* Find the best machine mode to use when referencing a bit field of length
2047 BITSIZE bits starting at BITPOS.
2049 The underlying object is known to be aligned to a boundary of ALIGN bits.
2050 If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
2051 larger than LARGEST_MODE (usually SImode).
2053 If no mode meets all these conditions, we return VOIDmode. Otherwise, if
2054 VOLATILEP is true or SLOW_BYTE_ACCESS is false, we return the smallest
2055 mode meeting these conditions.
2057 Otherwise (VOLATILEP is false and SLOW_BYTE_ACCESS is true), we return
2058 the largest mode (but a mode no wider than UNITS_PER_WORD) that meets
2059 all the conditions. */
2062 get_best_mode (int bitsize, int bitpos, unsigned int align,
2063 enum machine_mode largest_mode, int volatilep)
2065 enum machine_mode mode;
2066 unsigned int unit = 0;
2068 /* Find the narrowest integer mode that contains the bit field. */
2069 for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
2070 mode = GET_MODE_WIDER_MODE (mode))
2072 unit = GET_MODE_BITSIZE (mode);
2073 if ((bitpos % unit) + bitsize <= unit)
2077 if (mode == VOIDmode
2078 /* It is tempting to omit the following line
2079 if STRICT_ALIGNMENT is true.
2080 But that is incorrect, since if the bitfield uses part of 3 bytes
2081 and we use a 4-byte mode, we could get a spurious segv
2082 if the extra 4th byte is past the end of memory.
2083 (Though at least one Unix compiler ignores this problem:
2084 that on the Sequent 386 machine. */
2085 || MIN (unit, BIGGEST_ALIGNMENT) > align
2086 || (largest_mode != VOIDmode && unit > GET_MODE_BITSIZE (largest_mode)))
2089 if (SLOW_BYTE_ACCESS && ! volatilep)
2091 enum machine_mode wide_mode = VOIDmode, tmode;
2093 for (tmode = GET_CLASS_NARROWEST_MODE (MODE_INT); tmode != VOIDmode;
2094 tmode = GET_MODE_WIDER_MODE (tmode))
2096 unit = GET_MODE_BITSIZE (tmode);
2097 if (bitpos / unit == (bitpos + bitsize - 1) / unit
2098 && unit <= BITS_PER_WORD
2099 && unit <= MIN (align, BIGGEST_ALIGNMENT)
2100 && (largest_mode == VOIDmode
2101 || unit <= GET_MODE_BITSIZE (largest_mode)))
2105 if (wide_mode != VOIDmode)
2112 #include "gt-stor-layout.h"