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, 2004 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 extern void debug_rli (record_layout_info);
71 /* SAVE_EXPRs for sizes of types and decls, waiting to be expanded. */
73 static GTY(()) tree pending_sizes;
75 /* Show that REFERENCE_TYPES are internal and should be Pmode. Called only
79 internal_reference_types (void)
81 reference_types_internal = 1;
84 /* Get a list of all the objects put on the pending sizes list. */
87 get_pending_sizes (void)
89 tree chain = pending_sizes;
95 /* Add EXPR to the pending sizes list. */
98 put_pending_size (tree expr)
100 /* Strip any simple arithmetic from EXPR to see if it has an underlying
102 expr = skip_simple_arithmetic (expr);
104 if (TREE_CODE (expr) == SAVE_EXPR)
105 pending_sizes = tree_cons (NULL_TREE, expr, pending_sizes);
108 /* Put a chain of objects into the pending sizes list, which must be
112 put_pending_sizes (tree chain)
117 pending_sizes = chain;
120 /* Given a size SIZE that may not be a constant, return a SAVE_EXPR
121 to serve as the actual size-expression for a type or decl. */
124 variable_size (tree size)
128 /* If the language-processor is to take responsibility for variable-sized
129 items (e.g., languages which have elaboration procedures like Ada),
130 just return SIZE unchanged. Likewise for self-referential sizes and
132 if (TREE_CONSTANT (size)
133 || lang_hooks.decls.global_bindings_p () < 0
134 || CONTAINS_PLACEHOLDER_P (size))
137 size = save_expr (size);
139 /* If an array with a variable number of elements is declared, and
140 the elements require destruction, we will emit a cleanup for the
141 array. That cleanup is run both on normal exit from the block
142 and in the exception-handler for the block. Normally, when code
143 is used in both ordinary code and in an exception handler it is
144 `unsaved', i.e., all SAVE_EXPRs are recalculated. However, we do
145 not wish to do that here; the array-size is the same in both
147 save = skip_simple_arithmetic (size);
149 if (cfun && cfun->x_dont_save_pending_sizes_p)
150 /* The front-end doesn't want us to keep a list of the expressions
151 that determine sizes for variable size objects. Trust it. */
154 if (lang_hooks.decls.global_bindings_p ())
156 if (TREE_CONSTANT (size))
157 error ("type size can't be explicitly evaluated");
159 error ("variable-size type declared outside of any function");
161 return size_one_node;
164 put_pending_size (save);
169 #ifndef MAX_FIXED_MODE_SIZE
170 #define MAX_FIXED_MODE_SIZE GET_MODE_BITSIZE (DImode)
173 /* Return the machine mode to use for a nonscalar of SIZE bits. The
174 mode must be in class CLASS, and have exactly that many value bits;
175 it may have padding as well. If LIMIT is nonzero, modes of wider
176 than MAX_FIXED_MODE_SIZE will not be used. */
179 mode_for_size (unsigned int size, enum mode_class class, int limit)
181 enum machine_mode mode;
183 if (limit && size > MAX_FIXED_MODE_SIZE)
186 /* Get the first mode which has this size, in the specified class. */
187 for (mode = GET_CLASS_NARROWEST_MODE (class); mode != VOIDmode;
188 mode = GET_MODE_WIDER_MODE (mode))
189 if (GET_MODE_PRECISION (mode) == size)
195 /* Similar, except passed a tree node. */
198 mode_for_size_tree (tree size, enum mode_class class, int limit)
200 if (TREE_CODE (size) != INTEGER_CST
201 || TREE_OVERFLOW (size)
202 /* What we really want to say here is that the size can fit in a
203 host integer, but we know there's no way we'd find a mode for
204 this many bits, so there's no point in doing the precise test. */
205 || compare_tree_int (size, 1000) > 0)
208 return mode_for_size (tree_low_cst (size, 1), class, limit);
211 /* Similar, but never return BLKmode; return the narrowest mode that
212 contains at least the requested number of value bits. */
215 smallest_mode_for_size (unsigned int size, enum mode_class class)
217 enum machine_mode mode;
219 /* Get the first mode which has at least this size, in the
221 for (mode = GET_CLASS_NARROWEST_MODE (class); mode != VOIDmode;
222 mode = GET_MODE_WIDER_MODE (mode))
223 if (GET_MODE_PRECISION (mode) >= size)
229 /* Find an integer mode of the exact same size, or BLKmode on failure. */
232 int_mode_for_mode (enum machine_mode mode)
234 switch (GET_MODE_CLASS (mode))
237 case MODE_PARTIAL_INT:
240 case MODE_COMPLEX_INT:
241 case MODE_COMPLEX_FLOAT:
243 case MODE_VECTOR_INT:
244 case MODE_VECTOR_FLOAT:
245 mode = mode_for_size (GET_MODE_BITSIZE (mode), MODE_INT, 0);
252 /* ... fall through ... */
262 /* Return the alignment of MODE. This will be bounded by 1 and
263 BIGGEST_ALIGNMENT. */
266 get_mode_alignment (enum machine_mode mode)
268 return MIN (BIGGEST_ALIGNMENT, MAX (1, mode_base_align[mode]*BITS_PER_UNIT));
271 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
272 This can only be applied to objects of a sizetype. */
275 round_up (tree value, int divisor)
279 /* If divisor is a power of two, simplify this to bit manipulation. */
280 if (divisor == (divisor & -divisor))
282 t = size_int_type (divisor - 1, TREE_TYPE (value));
283 value = size_binop (PLUS_EXPR, value, t);
284 t = size_int_type (-divisor, TREE_TYPE (value));
285 value = size_binop (BIT_AND_EXPR, value, t);
289 t = size_int_type (divisor, TREE_TYPE (value));
290 value = size_binop (CEIL_DIV_EXPR, value, t);
291 value = size_binop (MULT_EXPR, value, t);
297 /* Likewise, but round down. */
300 round_down (tree value, int divisor)
304 /* If divisor is a power of two, simplify this to bit manipulation. */
305 if (divisor == (divisor & -divisor))
307 t = size_int_type (-divisor, TREE_TYPE (value));
308 value = size_binop (BIT_AND_EXPR, value, t);
312 t = size_int_type (divisor, TREE_TYPE (value));
313 value = size_binop (FLOOR_DIV_EXPR, value, t);
314 value = size_binop (MULT_EXPR, value, t);
320 /* Subroutine of layout_decl: Force alignment required for the data type.
321 But if the decl itself wants greater alignment, don't override that. */
324 do_type_align (tree type, tree decl)
326 if (TYPE_ALIGN (type) > DECL_ALIGN (decl))
328 DECL_ALIGN (decl) = TYPE_ALIGN (type);
329 if (TREE_CODE (decl) == FIELD_DECL)
330 DECL_USER_ALIGN (decl) = TYPE_USER_ALIGN (type);
334 /* Set the size, mode and alignment of a ..._DECL node.
335 TYPE_DECL does need this for C++.
336 Note that LABEL_DECL and CONST_DECL nodes do not need this,
337 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
338 Don't call layout_decl for them.
340 KNOWN_ALIGN is the amount of alignment we can assume this
341 decl has with no special effort. It is relevant only for FIELD_DECLs
342 and depends on the previous fields.
343 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
344 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
345 the record will be aligned to suit. */
348 layout_decl (tree decl, unsigned int known_align)
350 tree type = TREE_TYPE (decl);
351 enum tree_code code = TREE_CODE (decl);
354 if (code == CONST_DECL)
356 else if (code != VAR_DECL && code != PARM_DECL && code != RESULT_DECL
357 && code != TYPE_DECL && code != FIELD_DECL)
360 rtl = DECL_RTL_IF_SET (decl);
362 if (type == error_mark_node)
363 type = void_type_node;
365 /* Usually the size and mode come from the data type without change,
366 however, the front-end may set the explicit width of the field, so its
367 size may not be the same as the size of its type. This happens with
368 bitfields, of course (an `int' bitfield may be only 2 bits, say), but it
369 also happens with other fields. For example, the C++ front-end creates
370 zero-sized fields corresponding to empty base classes, and depends on
371 layout_type setting DECL_FIELD_BITPOS correctly for the field. Set the
372 size in bytes from the size in bits. If we have already set the mode,
373 don't set it again since we can be called twice for FIELD_DECLs. */
375 DECL_UNSIGNED (decl) = TYPE_UNSIGNED (type);
376 if (DECL_MODE (decl) == VOIDmode)
377 DECL_MODE (decl) = TYPE_MODE (type);
379 if (DECL_SIZE (decl) == 0)
381 DECL_SIZE (decl) = TYPE_SIZE (type);
382 DECL_SIZE_UNIT (decl) = TYPE_SIZE_UNIT (type);
384 else if (DECL_SIZE_UNIT (decl) == 0)
385 DECL_SIZE_UNIT (decl)
386 = convert (sizetype, size_binop (CEIL_DIV_EXPR, DECL_SIZE (decl),
389 if (code != FIELD_DECL)
390 /* For non-fields, update the alignment from the type. */
391 do_type_align (type, decl);
393 /* For fields, it's a bit more complicated... */
395 bool old_user_align = DECL_USER_ALIGN (decl);
397 if (DECL_BIT_FIELD (decl))
399 DECL_BIT_FIELD_TYPE (decl) = type;
401 /* A zero-length bit-field affects the alignment of the next
403 if (integer_zerop (DECL_SIZE (decl))
404 && ! DECL_PACKED (decl)
405 && ! targetm.ms_bitfield_layout_p (DECL_FIELD_CONTEXT (decl)))
407 #ifdef PCC_BITFIELD_TYPE_MATTERS
408 if (PCC_BITFIELD_TYPE_MATTERS)
409 do_type_align (type, decl);
413 #ifdef EMPTY_FIELD_BOUNDARY
414 if (EMPTY_FIELD_BOUNDARY > DECL_ALIGN (decl))
416 DECL_ALIGN (decl) = EMPTY_FIELD_BOUNDARY;
417 DECL_USER_ALIGN (decl) = 0;
423 /* See if we can use an ordinary integer mode for a bit-field.
424 Conditions are: a fixed size that is correct for another mode
425 and occupying a complete byte or bytes on proper boundary. */
426 if (TYPE_SIZE (type) != 0
427 && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
428 && GET_MODE_CLASS (TYPE_MODE (type)) == MODE_INT)
430 enum machine_mode xmode
431 = mode_for_size_tree (DECL_SIZE (decl), MODE_INT, 1);
435 || known_align >= GET_MODE_ALIGNMENT (xmode)))
437 DECL_ALIGN (decl) = MAX (GET_MODE_ALIGNMENT (xmode),
439 DECL_MODE (decl) = xmode;
440 DECL_BIT_FIELD (decl) = 0;
444 /* Turn off DECL_BIT_FIELD if we won't need it set. */
445 if (TYPE_MODE (type) == BLKmode && DECL_MODE (decl) == BLKmode
446 && known_align >= TYPE_ALIGN (type)
447 && DECL_ALIGN (decl) >= TYPE_ALIGN (type))
448 DECL_BIT_FIELD (decl) = 0;
450 else if (DECL_PACKED (decl) && DECL_USER_ALIGN (decl))
451 /* Don't touch DECL_ALIGN. For other packed fields, go ahead and
452 round up; we'll reduce it again below. We want packing to
453 supersede USER_ALIGN inherited from the type, but defer to
454 alignment explicitly specified on the field decl. */;
456 do_type_align (type, decl);
458 /* If the field is of variable size, we can't misalign it since we
459 have no way to make a temporary to align the result. But this
460 isn't an issue if the decl is not addressable. Likewise if it
463 Note that do_type_align may set DECL_USER_ALIGN, so we need to
464 check old_user_align instead. */
465 if (DECL_PACKED (decl)
467 && (DECL_NONADDRESSABLE_P (decl)
468 || DECL_SIZE_UNIT (decl) == 0
469 || TREE_CODE (DECL_SIZE_UNIT (decl)) == INTEGER_CST))
470 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), BITS_PER_UNIT);
472 if (! DECL_USER_ALIGN (decl) && ! DECL_PACKED (decl))
474 /* Some targets (i.e. i386, VMS) limit struct field alignment
475 to a lower boundary than alignment of variables unless
476 it was overridden by attribute aligned. */
477 #ifdef BIGGEST_FIELD_ALIGNMENT
479 = MIN (DECL_ALIGN (decl), (unsigned) BIGGEST_FIELD_ALIGNMENT);
481 #ifdef ADJUST_FIELD_ALIGN
482 DECL_ALIGN (decl) = ADJUST_FIELD_ALIGN (decl, DECL_ALIGN (decl));
486 /* Should this be controlled by DECL_USER_ALIGN, too? */
487 if (maximum_field_alignment != 0)
488 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), maximum_field_alignment);
491 /* Evaluate nonconstant size only once, either now or as soon as safe. */
492 if (DECL_SIZE (decl) != 0 && TREE_CODE (DECL_SIZE (decl)) != INTEGER_CST)
493 DECL_SIZE (decl) = variable_size (DECL_SIZE (decl));
494 if (DECL_SIZE_UNIT (decl) != 0
495 && TREE_CODE (DECL_SIZE_UNIT (decl)) != INTEGER_CST)
496 DECL_SIZE_UNIT (decl) = variable_size (DECL_SIZE_UNIT (decl));
498 /* If requested, warn about definitions of large data objects. */
500 && (code == VAR_DECL || code == PARM_DECL)
501 && ! DECL_EXTERNAL (decl))
503 tree size = DECL_SIZE_UNIT (decl);
505 if (size != 0 && TREE_CODE (size) == INTEGER_CST
506 && compare_tree_int (size, larger_than_size) > 0)
508 int size_as_int = TREE_INT_CST_LOW (size);
510 if (compare_tree_int (size, size_as_int) == 0)
511 warning ("%Jsize of '%D' is %d bytes", decl, decl, size_as_int);
513 warning ("%Jsize of '%D' is larger than %d bytes",
514 decl, decl, larger_than_size);
518 /* If the RTL was already set, update its mode and mem attributes. */
521 PUT_MODE (rtl, DECL_MODE (decl));
522 SET_DECL_RTL (decl, 0);
523 set_mem_attributes (rtl, decl, 1);
524 SET_DECL_RTL (decl, rtl);
528 /* Hook for a front-end function that can modify the record layout as needed
529 immediately before it is finalized. */
531 void (*lang_adjust_rli) (record_layout_info) = 0;
534 set_lang_adjust_rli (void (*f) (record_layout_info))
539 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
540 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
541 is to be passed to all other layout functions for this record. It is the
542 responsibility of the caller to call `free' for the storage returned.
543 Note that garbage collection is not permitted until we finish laying
547 start_record_layout (tree t)
549 record_layout_info rli = xmalloc (sizeof (struct record_layout_info_s));
553 /* If the type has a minimum specified alignment (via an attribute
554 declaration, for example) use it -- otherwise, start with a
555 one-byte alignment. */
556 rli->record_align = MAX (BITS_PER_UNIT, TYPE_ALIGN (t));
557 rli->unpacked_align = rli->record_align;
558 rli->offset_align = MAX (rli->record_align, BIGGEST_ALIGNMENT);
560 #ifdef STRUCTURE_SIZE_BOUNDARY
561 /* Packed structures don't need to have minimum size. */
562 if (! TYPE_PACKED (t))
563 rli->record_align = MAX (rli->record_align, (unsigned) STRUCTURE_SIZE_BOUNDARY);
566 rli->offset = size_zero_node;
567 rli->bitpos = bitsize_zero_node;
569 rli->pending_statics = 0;
570 rli->packed_maybe_necessary = 0;
575 /* These four routines perform computations that convert between
576 the offset/bitpos forms and byte and bit offsets. */
579 bit_from_pos (tree offset, tree bitpos)
581 return size_binop (PLUS_EXPR, bitpos,
582 size_binop (MULT_EXPR, convert (bitsizetype, offset),
587 byte_from_pos (tree offset, tree bitpos)
589 return size_binop (PLUS_EXPR, offset,
591 size_binop (TRUNC_DIV_EXPR, bitpos,
592 bitsize_unit_node)));
596 pos_from_bit (tree *poffset, tree *pbitpos, unsigned int off_align,
599 *poffset = size_binop (MULT_EXPR,
601 size_binop (FLOOR_DIV_EXPR, pos,
602 bitsize_int (off_align))),
603 size_int (off_align / BITS_PER_UNIT));
604 *pbitpos = size_binop (FLOOR_MOD_EXPR, pos, bitsize_int (off_align));
607 /* Given a pointer to bit and byte offsets and an offset alignment,
608 normalize the offsets so they are within the alignment. */
611 normalize_offset (tree *poffset, tree *pbitpos, unsigned int off_align)
613 /* If the bit position is now larger than it should be, adjust it
615 if (compare_tree_int (*pbitpos, off_align) >= 0)
617 tree extra_aligns = size_binop (FLOOR_DIV_EXPR, *pbitpos,
618 bitsize_int (off_align));
621 = size_binop (PLUS_EXPR, *poffset,
622 size_binop (MULT_EXPR, convert (sizetype, extra_aligns),
623 size_int (off_align / BITS_PER_UNIT)));
626 = size_binop (FLOOR_MOD_EXPR, *pbitpos, bitsize_int (off_align));
630 /* Print debugging information about the information in RLI. */
633 debug_rli (record_layout_info rli)
635 print_node_brief (stderr, "type", rli->t, 0);
636 print_node_brief (stderr, "\noffset", rli->offset, 0);
637 print_node_brief (stderr, " bitpos", rli->bitpos, 0);
639 fprintf (stderr, "\naligns: rec = %u, unpack = %u, off = %u\n",
640 rli->record_align, rli->unpacked_align,
642 if (rli->packed_maybe_necessary)
643 fprintf (stderr, "packed may be necessary\n");
645 if (rli->pending_statics)
647 fprintf (stderr, "pending statics:\n");
648 debug_tree (rli->pending_statics);
652 /* Given an RLI with a possibly-incremented BITPOS, adjust OFFSET and
653 BITPOS if necessary to keep BITPOS below OFFSET_ALIGN. */
656 normalize_rli (record_layout_info rli)
658 normalize_offset (&rli->offset, &rli->bitpos, rli->offset_align);
661 /* Returns the size in bytes allocated so far. */
664 rli_size_unit_so_far (record_layout_info rli)
666 return byte_from_pos (rli->offset, rli->bitpos);
669 /* Returns the size in bits allocated so far. */
672 rli_size_so_far (record_layout_info rli)
674 return bit_from_pos (rli->offset, rli->bitpos);
677 /* FIELD is about to be added to RLI->T. The alignment (in bits) of
678 the next available location is given by KNOWN_ALIGN. Update the
679 variable alignment fields in RLI, and return the alignment to give
683 update_alignment_for_field (record_layout_info rli, tree field,
684 unsigned int known_align)
686 /* The alignment required for FIELD. */
687 unsigned int desired_align;
688 /* The type of this field. */
689 tree type = TREE_TYPE (field);
690 /* True if the field was explicitly aligned by the user. */
694 /* Lay out the field so we know what alignment it needs. */
695 layout_decl (field, known_align);
696 desired_align = DECL_ALIGN (field);
697 user_align = DECL_USER_ALIGN (field);
699 is_bitfield = (type != error_mark_node
700 && DECL_BIT_FIELD_TYPE (field)
701 && ! integer_zerop (TYPE_SIZE (type)));
703 /* Record must have at least as much alignment as any field.
704 Otherwise, the alignment of the field within the record is
706 if (is_bitfield && targetm.ms_bitfield_layout_p (rli->t))
708 /* Here, the alignment of the underlying type of a bitfield can
709 affect the alignment of a record; even a zero-sized field
710 can do this. The alignment should be to the alignment of
711 the type, except that for zero-size bitfields this only
712 applies if there was an immediately prior, nonzero-size
713 bitfield. (That's the way it is, experimentally.) */
714 if (! integer_zerop (DECL_SIZE (field))
715 ? ! DECL_PACKED (field)
717 && DECL_BIT_FIELD_TYPE (rli->prev_field)
718 && ! integer_zerop (DECL_SIZE (rli->prev_field))))
720 unsigned int type_align = TYPE_ALIGN (type);
721 type_align = MAX (type_align, desired_align);
722 if (maximum_field_alignment != 0)
723 type_align = MIN (type_align, maximum_field_alignment);
724 rli->record_align = MAX (rli->record_align, type_align);
725 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
728 #ifdef PCC_BITFIELD_TYPE_MATTERS
729 else if (is_bitfield && PCC_BITFIELD_TYPE_MATTERS)
731 /* Named bit-fields cause the entire structure to have the
732 alignment implied by their type. Some targets also apply the same
733 rules to unnamed bitfields. */
734 if (DECL_NAME (field) != 0
735 || targetm.align_anon_bitfield ())
737 unsigned int type_align = TYPE_ALIGN (type);
739 #ifdef ADJUST_FIELD_ALIGN
740 if (! TYPE_USER_ALIGN (type))
741 type_align = ADJUST_FIELD_ALIGN (field, type_align);
744 if (maximum_field_alignment != 0)
745 type_align = MIN (type_align, maximum_field_alignment);
746 else if (DECL_PACKED (field))
747 type_align = MIN (type_align, BITS_PER_UNIT);
749 /* The alignment of the record is increased to the maximum
750 of the current alignment, the alignment indicated on the
751 field (i.e., the alignment specified by an __aligned__
752 attribute), and the alignment indicated by the type of
754 rli->record_align = MAX (rli->record_align, desired_align);
755 rli->record_align = MAX (rli->record_align, type_align);
758 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
759 user_align |= TYPE_USER_ALIGN (type);
765 rli->record_align = MAX (rli->record_align, desired_align);
766 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
769 TYPE_USER_ALIGN (rli->t) |= user_align;
771 return desired_align;
774 /* Called from place_field to handle unions. */
777 place_union_field (record_layout_info rli, tree field)
779 update_alignment_for_field (rli, field, /*known_align=*/0);
781 DECL_FIELD_OFFSET (field) = size_zero_node;
782 DECL_FIELD_BIT_OFFSET (field) = bitsize_zero_node;
783 SET_DECL_OFFSET_ALIGN (field, BIGGEST_ALIGNMENT);
785 /* We assume the union's size will be a multiple of a byte so we don't
786 bother with BITPOS. */
787 if (TREE_CODE (rli->t) == UNION_TYPE)
788 rli->offset = size_binop (MAX_EXPR, rli->offset, DECL_SIZE_UNIT (field));
789 else if (TREE_CODE (rli->t) == QUAL_UNION_TYPE)
790 rli->offset = fold (build (COND_EXPR, sizetype,
791 DECL_QUALIFIER (field),
792 DECL_SIZE_UNIT (field), rli->offset));
795 #if defined (PCC_BITFIELD_TYPE_MATTERS) || defined (BITFIELD_NBYTES_LIMITED)
796 /* A bitfield of SIZE with a required access alignment of ALIGN is allocated
797 at BYTE_OFFSET / BIT_OFFSET. Return nonzero if the field would span more
798 units of alignment than the underlying TYPE. */
800 excess_unit_span (HOST_WIDE_INT byte_offset, HOST_WIDE_INT bit_offset,
801 HOST_WIDE_INT size, HOST_WIDE_INT align, tree type)
803 /* Note that the calculation of OFFSET might overflow; we calculate it so
804 that we still get the right result as long as ALIGN is a power of two. */
805 unsigned HOST_WIDE_INT offset = byte_offset * BITS_PER_UNIT + bit_offset;
807 offset = offset % align;
808 return ((offset + size + align - 1) / align
809 > ((unsigned HOST_WIDE_INT) tree_low_cst (TYPE_SIZE (type), 1)
814 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
815 is a FIELD_DECL to be added after those fields already present in
816 T. (FIELD is not actually added to the TYPE_FIELDS list here;
817 callers that desire that behavior must manually perform that step.) */
820 place_field (record_layout_info rli, tree field)
822 /* The alignment required for FIELD. */
823 unsigned int desired_align;
824 /* The alignment FIELD would have if we just dropped it into the
825 record as it presently stands. */
826 unsigned int known_align;
827 unsigned int actual_align;
828 /* The type of this field. */
829 tree type = TREE_TYPE (field);
831 if (TREE_CODE (field) == ERROR_MARK || TREE_CODE (type) == ERROR_MARK)
834 /* If FIELD is static, then treat it like a separate variable, not
835 really like a structure field. If it is a FUNCTION_DECL, it's a
836 method. In both cases, all we do is lay out the decl, and we do
837 it *after* the record is laid out. */
838 if (TREE_CODE (field) == VAR_DECL)
840 rli->pending_statics = tree_cons (NULL_TREE, field,
841 rli->pending_statics);
845 /* Enumerators and enum types which are local to this class need not
846 be laid out. Likewise for initialized constant fields. */
847 else if (TREE_CODE (field) != FIELD_DECL)
850 /* Unions are laid out very differently than records, so split
851 that code off to another function. */
852 else if (TREE_CODE (rli->t) != RECORD_TYPE)
854 place_union_field (rli, field);
858 /* Work out the known alignment so far. Note that A & (-A) is the
859 value of the least-significant bit in A that is one. */
860 if (! integer_zerop (rli->bitpos))
861 known_align = (tree_low_cst (rli->bitpos, 1)
862 & - tree_low_cst (rli->bitpos, 1));
863 else if (integer_zerop (rli->offset))
864 known_align = BIGGEST_ALIGNMENT;
865 else if (host_integerp (rli->offset, 1))
866 known_align = (BITS_PER_UNIT
867 * (tree_low_cst (rli->offset, 1)
868 & - tree_low_cst (rli->offset, 1)));
870 known_align = rli->offset_align;
872 desired_align = update_alignment_for_field (rli, field, known_align);
874 if (warn_packed && DECL_PACKED (field))
876 if (known_align >= TYPE_ALIGN (type))
878 if (TYPE_ALIGN (type) > desired_align)
880 if (STRICT_ALIGNMENT)
881 warning ("%Jpacked attribute causes inefficient alignment "
882 "for '%D'", field, field);
884 warning ("%Jpacked attribute is unnecessary for '%D'",
889 rli->packed_maybe_necessary = 1;
892 /* Does this field automatically have alignment it needs by virtue
893 of the fields that precede it and the record's own alignment? */
894 if (known_align < desired_align)
896 /* No, we need to skip space before this field.
897 Bump the cumulative size to multiple of field alignment. */
900 warning ("%Jpadding struct to align '%D'", field, field);
902 /* If the alignment is still within offset_align, just align
904 if (desired_align < rli->offset_align)
905 rli->bitpos = round_up (rli->bitpos, desired_align);
908 /* First adjust OFFSET by the partial bits, then align. */
910 = size_binop (PLUS_EXPR, rli->offset,
912 size_binop (CEIL_DIV_EXPR, rli->bitpos,
913 bitsize_unit_node)));
914 rli->bitpos = bitsize_zero_node;
916 rli->offset = round_up (rli->offset, desired_align / BITS_PER_UNIT);
919 if (! TREE_CONSTANT (rli->offset))
920 rli->offset_align = desired_align;
924 /* Handle compatibility with PCC. Note that if the record has any
925 variable-sized fields, we need not worry about compatibility. */
926 #ifdef PCC_BITFIELD_TYPE_MATTERS
927 if (PCC_BITFIELD_TYPE_MATTERS
928 && ! targetm.ms_bitfield_layout_p (rli->t)
929 && TREE_CODE (field) == FIELD_DECL
930 && type != error_mark_node
931 && DECL_BIT_FIELD (field)
932 && ! DECL_PACKED (field)
933 && maximum_field_alignment == 0
934 && ! integer_zerop (DECL_SIZE (field))
935 && host_integerp (DECL_SIZE (field), 1)
936 && host_integerp (rli->offset, 1)
937 && host_integerp (TYPE_SIZE (type), 1))
939 unsigned int type_align = TYPE_ALIGN (type);
940 tree dsize = DECL_SIZE (field);
941 HOST_WIDE_INT field_size = tree_low_cst (dsize, 1);
942 HOST_WIDE_INT offset = tree_low_cst (rli->offset, 0);
943 HOST_WIDE_INT bit_offset = tree_low_cst (rli->bitpos, 0);
945 #ifdef ADJUST_FIELD_ALIGN
946 if (! TYPE_USER_ALIGN (type))
947 type_align = ADJUST_FIELD_ALIGN (field, type_align);
950 /* A bit field may not span more units of alignment of its type
951 than its type itself. Advance to next boundary if necessary. */
952 if (excess_unit_span (offset, bit_offset, field_size, type_align, type))
953 rli->bitpos = round_up (rli->bitpos, type_align);
955 TYPE_USER_ALIGN (rli->t) |= TYPE_USER_ALIGN (type);
959 #ifdef BITFIELD_NBYTES_LIMITED
960 if (BITFIELD_NBYTES_LIMITED
961 && ! targetm.ms_bitfield_layout_p (rli->t)
962 && TREE_CODE (field) == FIELD_DECL
963 && type != error_mark_node
964 && DECL_BIT_FIELD_TYPE (field)
965 && ! DECL_PACKED (field)
966 && ! integer_zerop (DECL_SIZE (field))
967 && host_integerp (DECL_SIZE (field), 1)
968 && host_integerp (rli->offset, 1)
969 && host_integerp (TYPE_SIZE (type), 1))
971 unsigned int type_align = TYPE_ALIGN (type);
972 tree dsize = DECL_SIZE (field);
973 HOST_WIDE_INT field_size = tree_low_cst (dsize, 1);
974 HOST_WIDE_INT offset = tree_low_cst (rli->offset, 0);
975 HOST_WIDE_INT bit_offset = tree_low_cst (rli->bitpos, 0);
977 #ifdef ADJUST_FIELD_ALIGN
978 if (! TYPE_USER_ALIGN (type))
979 type_align = ADJUST_FIELD_ALIGN (field, type_align);
982 if (maximum_field_alignment != 0)
983 type_align = MIN (type_align, maximum_field_alignment);
984 /* ??? This test is opposite the test in the containing if
985 statement, so this code is unreachable currently. */
986 else if (DECL_PACKED (field))
987 type_align = MIN (type_align, BITS_PER_UNIT);
989 /* A bit field may not span the unit of alignment of its type.
990 Advance to next boundary if necessary. */
991 if (excess_unit_span (offset, bit_offset, field_size, type_align, type))
992 rli->bitpos = round_up (rli->bitpos, type_align);
994 TYPE_USER_ALIGN (rli->t) |= TYPE_USER_ALIGN (type);
998 /* See the docs for TARGET_MS_BITFIELD_LAYOUT_P for details.
1000 When a bit field is inserted into a packed record, the whole
1001 size of the underlying type is used by one or more same-size
1002 adjacent bitfields. (That is, if its long:3, 32 bits is
1003 used in the record, and any additional adjacent long bitfields are
1004 packed into the same chunk of 32 bits. However, if the size
1005 changes, a new field of that size is allocated.) In an unpacked
1006 record, this is the same as using alignment, but not equivalent
1009 Note: for compatibility, we use the type size, not the type alignment
1010 to determine alignment, since that matches the documentation */
1012 if (targetm.ms_bitfield_layout_p (rli->t)
1013 && ((DECL_BIT_FIELD_TYPE (field) && ! DECL_PACKED (field))
1014 || (rli->prev_field && ! DECL_PACKED (rli->prev_field))))
1016 /* At this point, either the prior or current are bitfields,
1017 (possibly both), and we're dealing with MS packing. */
1018 tree prev_saved = rli->prev_field;
1020 /* Is the prior field a bitfield? If so, handle "runs" of same
1021 type size fields. */
1022 if (rli->prev_field /* necessarily a bitfield if it exists. */)
1024 /* If both are bitfields, nonzero, and the same size, this is
1025 the middle of a run. Zero declared size fields are special
1026 and handled as "end of run". (Note: it's nonzero declared
1027 size, but equal type sizes!) (Since we know that both
1028 the current and previous fields are bitfields by the
1029 time we check it, DECL_SIZE must be present for both.) */
1030 if (DECL_BIT_FIELD_TYPE (field)
1031 && !integer_zerop (DECL_SIZE (field))
1032 && !integer_zerop (DECL_SIZE (rli->prev_field))
1033 && host_integerp (DECL_SIZE (rli->prev_field), 0)
1034 && host_integerp (TYPE_SIZE (type), 0)
1035 && simple_cst_equal (TYPE_SIZE (type),
1036 TYPE_SIZE (TREE_TYPE (rli->prev_field))))
1038 /* We're in the middle of a run of equal type size fields; make
1039 sure we realign if we run out of bits. (Not decl size,
1041 HOST_WIDE_INT bitsize = tree_low_cst (DECL_SIZE (field), 0);
1043 if (rli->remaining_in_alignment < bitsize)
1045 /* out of bits; bump up to next 'word'. */
1046 rli->offset = DECL_FIELD_OFFSET (rli->prev_field);
1048 = size_binop (PLUS_EXPR, TYPE_SIZE (type),
1049 DECL_FIELD_BIT_OFFSET (rli->prev_field));
1050 rli->prev_field = field;
1051 rli->remaining_in_alignment
1052 = tree_low_cst (TYPE_SIZE (type), 0);
1055 rli->remaining_in_alignment -= bitsize;
1059 /* End of a run: if leaving a run of bitfields of the same type
1060 size, we have to "use up" the rest of the bits of the type
1063 Compute the new position as the sum of the size for the prior
1064 type and where we first started working on that type.
1065 Note: since the beginning of the field was aligned then
1066 of course the end will be too. No round needed. */
1068 if (!integer_zerop (DECL_SIZE (rli->prev_field)))
1070 tree type_size = TYPE_SIZE (TREE_TYPE (rli->prev_field));
1073 = size_binop (PLUS_EXPR, type_size,
1074 DECL_FIELD_BIT_OFFSET (rli->prev_field));
1077 /* We "use up" size zero fields; the code below should behave
1078 as if the prior field was not a bitfield. */
1081 /* Cause a new bitfield to be captured, either this time (if
1082 currently a bitfield) or next time we see one. */
1083 if (!DECL_BIT_FIELD_TYPE(field)
1084 || integer_zerop (DECL_SIZE (field)))
1085 rli->prev_field = NULL;
1088 normalize_rli (rli);
1091 /* If we're starting a new run of same size type bitfields
1092 (or a run of non-bitfields), set up the "first of the run"
1095 That is, if the current field is not a bitfield, or if there
1096 was a prior bitfield the type sizes differ, or if there wasn't
1097 a prior bitfield the size of the current field is nonzero.
1099 Note: we must be sure to test ONLY the type size if there was
1100 a prior bitfield and ONLY for the current field being zero if
1103 if (!DECL_BIT_FIELD_TYPE (field)
1104 || ( prev_saved != NULL
1105 ? !simple_cst_equal (TYPE_SIZE (type),
1106 TYPE_SIZE (TREE_TYPE (prev_saved)))
1107 : !integer_zerop (DECL_SIZE (field)) ))
1109 /* Never smaller than a byte for compatibility. */
1110 unsigned int type_align = BITS_PER_UNIT;
1112 /* (When not a bitfield), we could be seeing a flex array (with
1113 no DECL_SIZE). Since we won't be using remaining_in_alignment
1114 until we see a bitfield (and come by here again) we just skip
1116 if (DECL_SIZE (field) != NULL
1117 && host_integerp (TYPE_SIZE (TREE_TYPE (field)), 0)
1118 && host_integerp (DECL_SIZE (field), 0))
1119 rli->remaining_in_alignment
1120 = tree_low_cst (TYPE_SIZE (TREE_TYPE(field)), 0)
1121 - tree_low_cst (DECL_SIZE (field), 0);
1123 /* Now align (conventionally) for the new type. */
1124 if (!DECL_PACKED(field))
1125 type_align = MAX(TYPE_ALIGN (type), type_align);
1128 && DECL_BIT_FIELD_TYPE (prev_saved)
1129 /* If the previous bit-field is zero-sized, we've already
1130 accounted for its alignment needs (or ignored it, if
1131 appropriate) while placing it. */
1132 && ! integer_zerop (DECL_SIZE (prev_saved)))
1133 type_align = MAX (type_align,
1134 TYPE_ALIGN (TREE_TYPE (prev_saved)));
1136 if (maximum_field_alignment != 0)
1137 type_align = MIN (type_align, maximum_field_alignment);
1139 rli->bitpos = round_up (rli->bitpos, type_align);
1141 /* If we really aligned, don't allow subsequent bitfields
1143 rli->prev_field = NULL;
1147 /* Offset so far becomes the position of this field after normalizing. */
1148 normalize_rli (rli);
1149 DECL_FIELD_OFFSET (field) = rli->offset;
1150 DECL_FIELD_BIT_OFFSET (field) = rli->bitpos;
1151 SET_DECL_OFFSET_ALIGN (field, rli->offset_align);
1153 /* If this field ended up more aligned than we thought it would be (we
1154 approximate this by seeing if its position changed), lay out the field
1155 again; perhaps we can use an integral mode for it now. */
1156 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field)))
1157 actual_align = (tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1)
1158 & - tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1));
1159 else if (integer_zerop (DECL_FIELD_OFFSET (field)))
1160 actual_align = BIGGEST_ALIGNMENT;
1161 else if (host_integerp (DECL_FIELD_OFFSET (field), 1))
1162 actual_align = (BITS_PER_UNIT
1163 * (tree_low_cst (DECL_FIELD_OFFSET (field), 1)
1164 & - tree_low_cst (DECL_FIELD_OFFSET (field), 1)));
1166 actual_align = DECL_OFFSET_ALIGN (field);
1168 if (known_align != actual_align)
1169 layout_decl (field, actual_align);
1171 /* Only the MS bitfields use this. */
1172 if (rli->prev_field == NULL && DECL_BIT_FIELD_TYPE(field))
1173 rli->prev_field = field;
1175 /* Now add size of this field to the size of the record. If the size is
1176 not constant, treat the field as being a multiple of bytes and just
1177 adjust the offset, resetting the bit position. Otherwise, apportion the
1178 size amongst the bit position and offset. First handle the case of an
1179 unspecified size, which can happen when we have an invalid nested struct
1180 definition, such as struct j { struct j { int i; } }. The error message
1181 is printed in finish_struct. */
1182 if (DECL_SIZE (field) == 0)
1184 else if (TREE_CODE (DECL_SIZE_UNIT (field)) != INTEGER_CST
1185 || TREE_CONSTANT_OVERFLOW (DECL_SIZE_UNIT (field)))
1188 = size_binop (PLUS_EXPR, rli->offset,
1190 size_binop (CEIL_DIV_EXPR, rli->bitpos,
1191 bitsize_unit_node)));
1193 = size_binop (PLUS_EXPR, rli->offset, DECL_SIZE_UNIT (field));
1194 rli->bitpos = bitsize_zero_node;
1195 rli->offset_align = MIN (rli->offset_align, desired_align);
1199 rli->bitpos = size_binop (PLUS_EXPR, rli->bitpos, DECL_SIZE (field));
1200 normalize_rli (rli);
1204 /* Assuming that all the fields have been laid out, this function uses
1205 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
1206 indicated by RLI. */
1209 finalize_record_size (record_layout_info rli)
1211 tree unpadded_size, unpadded_size_unit;
1213 /* Now we want just byte and bit offsets, so set the offset alignment
1214 to be a byte and then normalize. */
1215 rli->offset_align = BITS_PER_UNIT;
1216 normalize_rli (rli);
1218 /* Determine the desired alignment. */
1219 #ifdef ROUND_TYPE_ALIGN
1220 TYPE_ALIGN (rli->t) = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t),
1223 TYPE_ALIGN (rli->t) = MAX (TYPE_ALIGN (rli->t), rli->record_align);
1226 /* Compute the size so far. Be sure to allow for extra bits in the
1227 size in bytes. We have guaranteed above that it will be no more
1228 than a single byte. */
1229 unpadded_size = rli_size_so_far (rli);
1230 unpadded_size_unit = rli_size_unit_so_far (rli);
1231 if (! integer_zerop (rli->bitpos))
1233 = size_binop (PLUS_EXPR, unpadded_size_unit, size_one_node);
1235 /* Round the size up to be a multiple of the required alignment. */
1236 TYPE_SIZE (rli->t) = round_up (unpadded_size, TYPE_ALIGN (rli->t));
1237 TYPE_SIZE_UNIT (rli->t) = round_up (unpadded_size_unit,
1238 TYPE_ALIGN (rli->t) / BITS_PER_UNIT);
1240 if (warn_padded && TREE_CONSTANT (unpadded_size)
1241 && simple_cst_equal (unpadded_size, TYPE_SIZE (rli->t)) == 0)
1242 warning ("padding struct size to alignment boundary");
1244 if (warn_packed && TREE_CODE (rli->t) == RECORD_TYPE
1245 && TYPE_PACKED (rli->t) && ! rli->packed_maybe_necessary
1246 && TREE_CONSTANT (unpadded_size))
1250 #ifdef ROUND_TYPE_ALIGN
1252 = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t), rli->unpacked_align);
1254 rli->unpacked_align = MAX (TYPE_ALIGN (rli->t), rli->unpacked_align);
1257 unpacked_size = round_up (TYPE_SIZE (rli->t), rli->unpacked_align);
1258 if (simple_cst_equal (unpacked_size, TYPE_SIZE (rli->t)))
1260 TYPE_PACKED (rli->t) = 0;
1262 if (TYPE_NAME (rli->t))
1266 if (TREE_CODE (TYPE_NAME (rli->t)) == IDENTIFIER_NODE)
1267 name = IDENTIFIER_POINTER (TYPE_NAME (rli->t));
1269 name = IDENTIFIER_POINTER (DECL_NAME (TYPE_NAME (rli->t)));
1271 if (STRICT_ALIGNMENT)
1272 warning ("packed attribute causes inefficient alignment for `%s'", name);
1274 warning ("packed attribute is unnecessary for `%s'", name);
1278 if (STRICT_ALIGNMENT)
1279 warning ("packed attribute causes inefficient alignment");
1281 warning ("packed attribute is unnecessary");
1287 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
1290 compute_record_mode (tree type)
1293 enum machine_mode mode = VOIDmode;
1295 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
1296 However, if possible, we use a mode that fits in a register
1297 instead, in order to allow for better optimization down the
1299 TYPE_MODE (type) = BLKmode;
1301 if (! host_integerp (TYPE_SIZE (type), 1))
1304 /* A record which has any BLKmode members must itself be
1305 BLKmode; it can't go in a register. Unless the member is
1306 BLKmode only because it isn't aligned. */
1307 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1309 if (TREE_CODE (field) != FIELD_DECL)
1312 if (TREE_CODE (TREE_TYPE (field)) == ERROR_MARK
1313 || (TYPE_MODE (TREE_TYPE (field)) == BLKmode
1314 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field))
1315 && !(TYPE_SIZE (TREE_TYPE (field)) != 0
1316 && integer_zerop (TYPE_SIZE (TREE_TYPE (field)))))
1317 || ! host_integerp (bit_position (field), 1)
1318 || DECL_SIZE (field) == 0
1319 || ! host_integerp (DECL_SIZE (field), 1))
1322 /* If this field is the whole struct, remember its mode so
1323 that, say, we can put a double in a class into a DF
1324 register instead of forcing it to live in the stack. */
1325 if (simple_cst_equal (TYPE_SIZE (type), DECL_SIZE (field)))
1326 mode = DECL_MODE (field);
1328 #ifdef MEMBER_TYPE_FORCES_BLK
1329 /* With some targets, eg. c4x, it is sub-optimal
1330 to access an aligned BLKmode structure as a scalar. */
1332 if (MEMBER_TYPE_FORCES_BLK (field, mode))
1334 #endif /* MEMBER_TYPE_FORCES_BLK */
1337 /* If we only have one real field; use its mode. This only applies to
1338 RECORD_TYPE. This does not apply to unions. */
1339 if (TREE_CODE (type) == RECORD_TYPE && mode != VOIDmode)
1340 TYPE_MODE (type) = mode;
1342 TYPE_MODE (type) = mode_for_size_tree (TYPE_SIZE (type), MODE_INT, 1);
1344 /* If structure's known alignment is less than what the scalar
1345 mode would need, and it matters, then stick with BLKmode. */
1346 if (TYPE_MODE (type) != BLKmode
1348 && ! (TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT
1349 || TYPE_ALIGN (type) >= GET_MODE_ALIGNMENT (TYPE_MODE (type))))
1351 /* If this is the only reason this type is BLKmode, then
1352 don't force containing types to be BLKmode. */
1353 TYPE_NO_FORCE_BLK (type) = 1;
1354 TYPE_MODE (type) = BLKmode;
1358 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1362 finalize_type_size (tree type)
1364 /* Normally, use the alignment corresponding to the mode chosen.
1365 However, where strict alignment is not required, avoid
1366 over-aligning structures, since most compilers do not do this
1369 if (TYPE_MODE (type) != BLKmode && TYPE_MODE (type) != VOIDmode
1370 && (STRICT_ALIGNMENT
1371 || (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE
1372 && TREE_CODE (type) != QUAL_UNION_TYPE
1373 && TREE_CODE (type) != ARRAY_TYPE)))
1375 TYPE_ALIGN (type) = GET_MODE_ALIGNMENT (TYPE_MODE (type));
1376 TYPE_USER_ALIGN (type) = 0;
1379 /* Do machine-dependent extra alignment. */
1380 #ifdef ROUND_TYPE_ALIGN
1382 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (type), BITS_PER_UNIT);
1385 /* If we failed to find a simple way to calculate the unit size
1386 of the type, find it by division. */
1387 if (TYPE_SIZE_UNIT (type) == 0 && TYPE_SIZE (type) != 0)
1388 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1389 result will fit in sizetype. We will get more efficient code using
1390 sizetype, so we force a conversion. */
1391 TYPE_SIZE_UNIT (type)
1392 = convert (sizetype,
1393 size_binop (FLOOR_DIV_EXPR, TYPE_SIZE (type),
1394 bitsize_unit_node));
1396 if (TYPE_SIZE (type) != 0)
1398 TYPE_SIZE (type) = round_up (TYPE_SIZE (type), TYPE_ALIGN (type));
1399 TYPE_SIZE_UNIT (type)
1400 = round_up (TYPE_SIZE_UNIT (type), TYPE_ALIGN (type) / BITS_PER_UNIT);
1403 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1404 if (TYPE_SIZE (type) != 0 && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
1405 TYPE_SIZE (type) = variable_size (TYPE_SIZE (type));
1406 if (TYPE_SIZE_UNIT (type) != 0
1407 && TREE_CODE (TYPE_SIZE_UNIT (type)) != INTEGER_CST)
1408 TYPE_SIZE_UNIT (type) = variable_size (TYPE_SIZE_UNIT (type));
1410 /* Also layout any other variants of the type. */
1411 if (TYPE_NEXT_VARIANT (type)
1412 || type != TYPE_MAIN_VARIANT (type))
1415 /* Record layout info of this variant. */
1416 tree size = TYPE_SIZE (type);
1417 tree size_unit = TYPE_SIZE_UNIT (type);
1418 unsigned int align = TYPE_ALIGN (type);
1419 unsigned int user_align = TYPE_USER_ALIGN (type);
1420 enum machine_mode mode = TYPE_MODE (type);
1422 /* Copy it into all variants. */
1423 for (variant = TYPE_MAIN_VARIANT (type);
1425 variant = TYPE_NEXT_VARIANT (variant))
1427 TYPE_SIZE (variant) = size;
1428 TYPE_SIZE_UNIT (variant) = size_unit;
1429 TYPE_ALIGN (variant) = align;
1430 TYPE_USER_ALIGN (variant) = user_align;
1431 TYPE_MODE (variant) = mode;
1436 /* Do all of the work required to layout the type indicated by RLI,
1437 once the fields have been laid out. This function will call `free'
1438 for RLI, unless FREE_P is false. Passing a value other than false
1439 for FREE_P is bad practice; this option only exists to support the
1443 finish_record_layout (record_layout_info rli, int free_p)
1445 /* Compute the final size. */
1446 finalize_record_size (rli);
1448 /* Compute the TYPE_MODE for the record. */
1449 compute_record_mode (rli->t);
1451 /* Perform any last tweaks to the TYPE_SIZE, etc. */
1452 finalize_type_size (rli->t);
1454 /* Lay out any static members. This is done now because their type
1455 may use the record's type. */
1456 while (rli->pending_statics)
1458 layout_decl (TREE_VALUE (rli->pending_statics), 0);
1459 rli->pending_statics = TREE_CHAIN (rli->pending_statics);
1468 /* Finish processing a builtin RECORD_TYPE type TYPE. It's name is
1469 NAME, its fields are chained in reverse on FIELDS.
1471 If ALIGN_TYPE is non-null, it is given the same alignment as
1475 finish_builtin_struct (tree type, const char *name, tree fields,
1480 for (tail = NULL_TREE; fields; tail = fields, fields = next)
1482 DECL_FIELD_CONTEXT (fields) = type;
1483 next = TREE_CHAIN (fields);
1484 TREE_CHAIN (fields) = tail;
1486 TYPE_FIELDS (type) = tail;
1490 TYPE_ALIGN (type) = TYPE_ALIGN (align_type);
1491 TYPE_USER_ALIGN (type) = TYPE_USER_ALIGN (align_type);
1495 #if 0 /* not yet, should get fixed properly later */
1496 TYPE_NAME (type) = make_type_decl (get_identifier (name), type);
1498 TYPE_NAME (type) = build_decl (TYPE_DECL, get_identifier (name), type);
1500 TYPE_STUB_DECL (type) = TYPE_NAME (type);
1501 layout_decl (TYPE_NAME (type), 0);
1504 /* Calculate the mode, size, and alignment for TYPE.
1505 For an array type, calculate the element separation as well.
1506 Record TYPE on the chain of permanent or temporary types
1507 so that dbxout will find out about it.
1509 TYPE_SIZE of a type is nonzero if the type has been laid out already.
1510 layout_type does nothing on such a type.
1512 If the type is incomplete, its TYPE_SIZE remains zero. */
1515 layout_type (tree type)
1520 if (type == error_mark_node)
1523 /* Do nothing if type has been laid out before. */
1524 if (TYPE_SIZE (type))
1527 switch (TREE_CODE (type))
1530 /* This kind of type is the responsibility
1531 of the language-specific code. */
1534 case BOOLEAN_TYPE: /* Used for Java, Pascal, and Chill. */
1535 if (TYPE_PRECISION (type) == 0)
1536 TYPE_PRECISION (type) = 1; /* default to one byte/boolean. */
1538 /* ... fall through ... */
1543 if (TREE_CODE (TYPE_MIN_VALUE (type)) == INTEGER_CST
1544 && tree_int_cst_sgn (TYPE_MIN_VALUE (type)) >= 0)
1545 TYPE_UNSIGNED (type) = 1;
1547 TYPE_MODE (type) = smallest_mode_for_size (TYPE_PRECISION (type),
1549 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1550 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1554 TYPE_MODE (type) = mode_for_size (TYPE_PRECISION (type), MODE_FLOAT, 0);
1555 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1556 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1560 TYPE_UNSIGNED (type) = TYPE_UNSIGNED (TREE_TYPE (type));
1562 = mode_for_size (2 * TYPE_PRECISION (TREE_TYPE (type)),
1563 (TREE_CODE (TREE_TYPE (type)) == REAL_TYPE
1564 ? MODE_COMPLEX_FLOAT : MODE_COMPLEX_INT),
1566 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1567 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1571 TYPE_UNSIGNED (type) = TYPE_UNSIGNED (TREE_TYPE (type));
1572 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1573 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1577 /* This is an incomplete type and so doesn't have a size. */
1578 TYPE_ALIGN (type) = 1;
1579 TYPE_USER_ALIGN (type) = 0;
1580 TYPE_MODE (type) = VOIDmode;
1584 TYPE_SIZE (type) = bitsize_int (POINTER_SIZE);
1585 TYPE_SIZE_UNIT (type) = size_int (POINTER_SIZE / BITS_PER_UNIT);
1586 /* A pointer might be MODE_PARTIAL_INT,
1587 but ptrdiff_t must be integral. */
1588 TYPE_MODE (type) = mode_for_size (POINTER_SIZE, MODE_INT, 0);
1593 /* It's hard to see what the mode and size of a function ought to
1594 be, but we do know the alignment is FUNCTION_BOUNDARY, so
1595 make it consistent with that. */
1596 TYPE_MODE (type) = mode_for_size (FUNCTION_BOUNDARY, MODE_INT, 0);
1597 TYPE_SIZE (type) = bitsize_int (FUNCTION_BOUNDARY);
1598 TYPE_SIZE_UNIT (type) = size_int (FUNCTION_BOUNDARY / BITS_PER_UNIT);
1602 case REFERENCE_TYPE:
1605 enum machine_mode mode = ((TREE_CODE (type) == REFERENCE_TYPE
1606 && reference_types_internal)
1607 ? Pmode : TYPE_MODE (type));
1609 int nbits = GET_MODE_BITSIZE (mode);
1611 TYPE_SIZE (type) = bitsize_int (nbits);
1612 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (mode));
1613 TYPE_UNSIGNED (type) = 1;
1614 TYPE_PRECISION (type) = nbits;
1620 tree index = TYPE_DOMAIN (type);
1621 tree element = TREE_TYPE (type);
1623 build_pointer_type (element);
1625 /* We need to know both bounds in order to compute the size. */
1626 if (index && TYPE_MAX_VALUE (index) && TYPE_MIN_VALUE (index)
1627 && TYPE_SIZE (element))
1629 tree ub = TYPE_MAX_VALUE (index);
1630 tree lb = TYPE_MIN_VALUE (index);
1634 /* The initial subtraction should happen in the original type so
1635 that (possible) negative values are handled appropriately. */
1636 length = size_binop (PLUS_EXPR, size_one_node,
1638 fold (build (MINUS_EXPR,
1642 /* Special handling for arrays of bits (for Chill). */
1643 element_size = TYPE_SIZE (element);
1644 if (TYPE_PACKED (type) && INTEGRAL_TYPE_P (element)
1645 && (integer_zerop (TYPE_MAX_VALUE (element))
1646 || integer_onep (TYPE_MAX_VALUE (element)))
1647 && host_integerp (TYPE_MIN_VALUE (element), 1))
1649 HOST_WIDE_INT maxvalue
1650 = tree_low_cst (TYPE_MAX_VALUE (element), 1);
1651 HOST_WIDE_INT minvalue
1652 = tree_low_cst (TYPE_MIN_VALUE (element), 1);
1654 if (maxvalue - minvalue == 1
1655 && (maxvalue == 1 || maxvalue == 0))
1656 element_size = integer_one_node;
1659 /* If neither bound is a constant and sizetype is signed, make
1660 sure the size is never negative. We should really do this
1661 if *either* bound is non-constant, but this is the best
1662 compromise between C and Ada. */
1663 if (!TYPE_UNSIGNED (sizetype)
1664 && TREE_CODE (TYPE_MIN_VALUE (index)) != INTEGER_CST
1665 && TREE_CODE (TYPE_MAX_VALUE (index)) != INTEGER_CST)
1666 length = size_binop (MAX_EXPR, length, size_zero_node);
1668 TYPE_SIZE (type) = size_binop (MULT_EXPR, element_size,
1669 convert (bitsizetype, length));
1671 /* If we know the size of the element, calculate the total
1672 size directly, rather than do some division thing below.
1673 This optimization helps Fortran assumed-size arrays
1674 (where the size of the array is determined at runtime)
1676 Note that we can't do this in the case where the size of
1677 the elements is one bit since TYPE_SIZE_UNIT cannot be
1678 set correctly in that case. */
1679 if (TYPE_SIZE_UNIT (element) != 0 && ! integer_onep (element_size))
1680 TYPE_SIZE_UNIT (type)
1681 = size_binop (MULT_EXPR, TYPE_SIZE_UNIT (element), length);
1684 /* Now round the alignment and size,
1685 using machine-dependent criteria if any. */
1687 #ifdef ROUND_TYPE_ALIGN
1689 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (element), BITS_PER_UNIT);
1691 TYPE_ALIGN (type) = MAX (TYPE_ALIGN (element), BITS_PER_UNIT);
1693 TYPE_USER_ALIGN (type) = TYPE_USER_ALIGN (element);
1694 TYPE_MODE (type) = BLKmode;
1695 if (TYPE_SIZE (type) != 0
1696 #ifdef MEMBER_TYPE_FORCES_BLK
1697 && ! MEMBER_TYPE_FORCES_BLK (type, VOIDmode)
1699 /* BLKmode elements force BLKmode aggregate;
1700 else extract/store fields may lose. */
1701 && (TYPE_MODE (TREE_TYPE (type)) != BLKmode
1702 || TYPE_NO_FORCE_BLK (TREE_TYPE (type))))
1704 /* One-element arrays get the component type's mode. */
1705 if (simple_cst_equal (TYPE_SIZE (type),
1706 TYPE_SIZE (TREE_TYPE (type))))
1707 TYPE_MODE (type) = TYPE_MODE (TREE_TYPE (type));
1710 = mode_for_size_tree (TYPE_SIZE (type), MODE_INT, 1);
1712 if (TYPE_MODE (type) != BLKmode
1713 && STRICT_ALIGNMENT && TYPE_ALIGN (type) < BIGGEST_ALIGNMENT
1714 && TYPE_ALIGN (type) < GET_MODE_ALIGNMENT (TYPE_MODE (type))
1715 && TYPE_MODE (type) != BLKmode)
1717 TYPE_NO_FORCE_BLK (type) = 1;
1718 TYPE_MODE (type) = BLKmode;
1726 case QUAL_UNION_TYPE:
1729 record_layout_info rli;
1731 /* Initialize the layout information. */
1732 rli = start_record_layout (type);
1734 /* If this is a QUAL_UNION_TYPE, we want to process the fields
1735 in the reverse order in building the COND_EXPR that denotes
1736 its size. We reverse them again later. */
1737 if (TREE_CODE (type) == QUAL_UNION_TYPE)
1738 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
1740 /* Place all the fields. */
1741 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1742 place_field (rli, field);
1744 if (TREE_CODE (type) == QUAL_UNION_TYPE)
1745 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
1747 if (lang_adjust_rli)
1748 (*lang_adjust_rli) (rli);
1750 /* Finish laying out the record. */
1751 finish_record_layout (rli, /*free_p=*/true);
1755 case SET_TYPE: /* Used by Chill and Pascal. */
1756 if (TREE_CODE (TYPE_MAX_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST
1757 || TREE_CODE (TYPE_MIN_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST)
1761 #ifndef SET_WORD_SIZE
1762 #define SET_WORD_SIZE BITS_PER_WORD
1764 unsigned int alignment
1765 = set_alignment ? set_alignment : SET_WORD_SIZE;
1766 HOST_WIDE_INT size_in_bits
1767 = (tree_low_cst (TYPE_MAX_VALUE (TYPE_DOMAIN (type)), 0)
1768 - tree_low_cst (TYPE_MIN_VALUE (TYPE_DOMAIN (type)), 0) + 1);
1769 HOST_WIDE_INT rounded_size
1770 = ((size_in_bits + alignment - 1) / alignment) * alignment;
1772 if (rounded_size > (int) alignment)
1773 TYPE_MODE (type) = BLKmode;
1775 TYPE_MODE (type) = mode_for_size (alignment, MODE_INT, 1);
1777 TYPE_SIZE (type) = bitsize_int (rounded_size);
1778 TYPE_SIZE_UNIT (type) = size_int (rounded_size / BITS_PER_UNIT);
1779 TYPE_ALIGN (type) = alignment;
1780 TYPE_USER_ALIGN (type) = 0;
1781 TYPE_PRECISION (type) = size_in_bits;
1786 /* The size may vary in different languages, so the language front end
1787 should fill in the size. */
1788 TYPE_ALIGN (type) = BIGGEST_ALIGNMENT;
1789 TYPE_USER_ALIGN (type) = 0;
1790 TYPE_MODE (type) = BLKmode;
1797 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
1798 records and unions, finish_record_layout already called this
1800 if (TREE_CODE (type) != RECORD_TYPE
1801 && TREE_CODE (type) != UNION_TYPE
1802 && TREE_CODE (type) != QUAL_UNION_TYPE)
1803 finalize_type_size (type);
1805 /* If this type is created before sizetype has been permanently set,
1806 record it so set_sizetype can fix it up. */
1808 early_type_list = tree_cons (NULL_TREE, type, early_type_list);
1810 /* If an alias set has been set for this aggregate when it was incomplete,
1811 force it into alias set 0.
1812 This is too conservative, but we cannot call record_component_aliases
1813 here because some frontends still change the aggregates after
1815 if (AGGREGATE_TYPE_P (type) && TYPE_ALIAS_SET_KNOWN_P (type))
1816 TYPE_ALIAS_SET (type) = 0;
1819 /* Create and return a type for signed integers of PRECISION bits. */
1822 make_signed_type (int precision)
1824 tree type = make_node (INTEGER_TYPE);
1826 TYPE_PRECISION (type) = precision;
1828 fixup_signed_type (type);
1832 /* Create and return a type for unsigned integers of PRECISION bits. */
1835 make_unsigned_type (int precision)
1837 tree type = make_node (INTEGER_TYPE);
1839 TYPE_PRECISION (type) = precision;
1841 fixup_unsigned_type (type);
1845 /* Initialize sizetype and bitsizetype to a reasonable and temporary
1846 value to enable integer types to be created. */
1849 initialize_sizetypes (void)
1851 tree t = make_node (INTEGER_TYPE);
1853 /* Set this so we do something reasonable for the build_int_2 calls
1855 integer_type_node = t;
1857 TYPE_MODE (t) = SImode;
1858 TYPE_ALIGN (t) = GET_MODE_ALIGNMENT (SImode);
1859 TYPE_USER_ALIGN (t) = 0;
1860 TYPE_SIZE (t) = build_int_2 (GET_MODE_BITSIZE (SImode), 0);
1861 TYPE_SIZE_UNIT (t) = build_int_2 (GET_MODE_SIZE (SImode), 0);
1862 TYPE_UNSIGNED (t) = 1;
1863 TYPE_PRECISION (t) = GET_MODE_BITSIZE (SImode);
1864 TYPE_MIN_VALUE (t) = build_int_2 (0, 0);
1865 TYPE_IS_SIZETYPE (t) = 1;
1867 /* 1000 avoids problems with possible overflow and is certainly
1868 larger than any size value we'd want to be storing. */
1869 TYPE_MAX_VALUE (t) = build_int_2 (1000, 0);
1871 /* These two must be different nodes because of the caching done in
1874 bitsizetype = copy_node (t);
1875 integer_type_node = 0;
1878 /* Set sizetype to TYPE, and initialize *sizetype accordingly.
1879 Also update the type of any standard type's sizes made so far. */
1882 set_sizetype (tree type)
1884 int oprecision = TYPE_PRECISION (type);
1885 /* The *bitsizetype types use a precision that avoids overflows when
1886 calculating signed sizes / offsets in bits. However, when
1887 cross-compiling from a 32 bit to a 64 bit host, we are limited to 64 bit
1889 int precision = MIN (oprecision + BITS_PER_UNIT_LOG + 1,
1890 2 * HOST_BITS_PER_WIDE_INT);
1897 /* Make copies of nodes since we'll be setting TYPE_IS_SIZETYPE. */
1898 sizetype = copy_node (type);
1899 TYPE_ORIG_SIZE_TYPE (sizetype) = type;
1900 TYPE_IS_SIZETYPE (sizetype) = 1;
1901 bitsizetype = make_node (INTEGER_TYPE);
1902 TYPE_NAME (bitsizetype) = TYPE_NAME (type);
1903 TYPE_PRECISION (bitsizetype) = precision;
1904 TYPE_IS_SIZETYPE (bitsizetype) = 1;
1906 if (TYPE_UNSIGNED (type))
1907 fixup_unsigned_type (bitsizetype);
1909 fixup_signed_type (bitsizetype);
1911 layout_type (bitsizetype);
1913 if (TYPE_UNSIGNED (type))
1915 usizetype = sizetype;
1916 ubitsizetype = bitsizetype;
1917 ssizetype = copy_node (make_signed_type (oprecision));
1918 sbitsizetype = copy_node (make_signed_type (precision));
1922 ssizetype = sizetype;
1923 sbitsizetype = bitsizetype;
1924 usizetype = copy_node (make_unsigned_type (oprecision));
1925 ubitsizetype = copy_node (make_unsigned_type (precision));
1928 TYPE_NAME (bitsizetype) = get_identifier ("bit_size_type");
1930 /* Show is a sizetype, is a main type, and has no pointers to it. */
1931 for (i = 0; i < ARRAY_SIZE (sizetype_tab); i++)
1933 TYPE_IS_SIZETYPE (sizetype_tab[i]) = 1;
1934 TYPE_MAIN_VARIANT (sizetype_tab[i]) = sizetype_tab[i];
1935 TYPE_NEXT_VARIANT (sizetype_tab[i]) = 0;
1936 TYPE_POINTER_TO (sizetype_tab[i]) = 0;
1937 TYPE_REFERENCE_TO (sizetype_tab[i]) = 0;
1940 /* Go down each of the types we already made and set the proper type
1941 for the sizes in them. */
1942 for (t = early_type_list; t != 0; t = TREE_CHAIN (t))
1944 if (TREE_CODE (TREE_VALUE (t)) != INTEGER_TYPE
1945 && TREE_CODE (TREE_VALUE (t)) != BOOLEAN_TYPE)
1948 TREE_TYPE (TYPE_SIZE (TREE_VALUE (t))) = bitsizetype;
1949 TREE_TYPE (TYPE_SIZE_UNIT (TREE_VALUE (t))) = sizetype;
1952 early_type_list = 0;
1956 /* TYPE is an integral type, i.e., an INTEGRAL_TYPE, ENUMERAL_TYPE,
1957 BOOLEAN_TYPE, or CHAR_TYPE. Set TYPE_MIN_VALUE and TYPE_MAX_VALUE
1958 for TYPE, based on the PRECISION and whether or not the TYPE
1959 IS_UNSIGNED. PRECISION need not correspond to a width supported
1960 natively by the hardware; for example, on a machine with 8-bit,
1961 16-bit, and 32-bit register modes, PRECISION might be 7, 23, or
1965 set_min_and_max_values_for_integral_type (tree type,
1974 min_value = build_int_2 (0, 0);
1976 = build_int_2 (precision - HOST_BITS_PER_WIDE_INT >= 0
1977 ? -1 : ((HOST_WIDE_INT) 1 << precision) - 1,
1978 precision - HOST_BITS_PER_WIDE_INT > 0
1979 ? ((unsigned HOST_WIDE_INT) ~0
1980 >> (HOST_BITS_PER_WIDE_INT
1981 - (precision - HOST_BITS_PER_WIDE_INT)))
1987 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1988 ? 0 : (HOST_WIDE_INT) (-1) << (precision - 1)),
1989 (((HOST_WIDE_INT) (-1)
1990 << (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1991 ? precision - HOST_BITS_PER_WIDE_INT - 1
1994 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1995 ? -1 : ((HOST_WIDE_INT) 1 << (precision - 1)) - 1),
1996 (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1997 ? (((HOST_WIDE_INT) 1
1998 << (precision - HOST_BITS_PER_WIDE_INT - 1))) - 1
2002 TREE_TYPE (min_value) = type;
2003 TREE_TYPE (max_value) = type;
2004 TYPE_MIN_VALUE (type) = min_value;
2005 TYPE_MAX_VALUE (type) = max_value;
2008 /* Set the extreme values of TYPE based on its precision in bits,
2009 then lay it out. Used when make_signed_type won't do
2010 because the tree code is not INTEGER_TYPE.
2011 E.g. for Pascal, when the -fsigned-char option is given. */
2014 fixup_signed_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 set_min_and_max_values_for_integral_type (type, precision,
2025 /*is_unsigned=*/false);
2027 /* Lay out the type: set its alignment, size, etc. */
2031 /* Set the extreme values of TYPE based on its precision in bits,
2032 then lay it out. This is used both in `make_unsigned_type'
2033 and for enumeral types. */
2036 fixup_unsigned_type (tree type)
2038 int precision = TYPE_PRECISION (type);
2040 /* We can not represent properly constants greater then
2041 2 * HOST_BITS_PER_WIDE_INT, still we need the types
2042 as they are used by i386 vector extensions and friends. */
2043 if (precision > HOST_BITS_PER_WIDE_INT * 2)
2044 precision = HOST_BITS_PER_WIDE_INT * 2;
2046 set_min_and_max_values_for_integral_type (type, precision,
2047 /*is_unsigned=*/true);
2049 /* Lay out the type: set its alignment, size, etc. */
2053 /* Find the best machine mode to use when referencing a bit field of length
2054 BITSIZE bits starting at BITPOS.
2056 The underlying object is known to be aligned to a boundary of ALIGN bits.
2057 If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
2058 larger than LARGEST_MODE (usually SImode).
2060 If no mode meets all these conditions, we return VOIDmode. Otherwise, if
2061 VOLATILEP is true or SLOW_BYTE_ACCESS is false, we return the smallest
2062 mode meeting these conditions.
2064 Otherwise (VOLATILEP is false and SLOW_BYTE_ACCESS is true), we return
2065 the largest mode (but a mode no wider than UNITS_PER_WORD) that meets
2066 all the conditions. */
2069 get_best_mode (int bitsize, int bitpos, unsigned int align,
2070 enum machine_mode largest_mode, int volatilep)
2072 enum machine_mode mode;
2073 unsigned int unit = 0;
2075 /* Find the narrowest integer mode that contains the bit field. */
2076 for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
2077 mode = GET_MODE_WIDER_MODE (mode))
2079 unit = GET_MODE_BITSIZE (mode);
2080 if ((bitpos % unit) + bitsize <= unit)
2084 if (mode == VOIDmode
2085 /* It is tempting to omit the following line
2086 if STRICT_ALIGNMENT is true.
2087 But that is incorrect, since if the bitfield uses part of 3 bytes
2088 and we use a 4-byte mode, we could get a spurious segv
2089 if the extra 4th byte is past the end of memory.
2090 (Though at least one Unix compiler ignores this problem:
2091 that on the Sequent 386 machine. */
2092 || MIN (unit, BIGGEST_ALIGNMENT) > align
2093 || (largest_mode != VOIDmode && unit > GET_MODE_BITSIZE (largest_mode)))
2096 if (SLOW_BYTE_ACCESS && ! volatilep)
2098 enum machine_mode wide_mode = VOIDmode, tmode;
2100 for (tmode = GET_CLASS_NARROWEST_MODE (MODE_INT); tmode != VOIDmode;
2101 tmode = GET_MODE_WIDER_MODE (tmode))
2103 unit = GET_MODE_BITSIZE (tmode);
2104 if (bitpos / unit == (bitpos + bitsize - 1) / unit
2105 && unit <= BITS_PER_WORD
2106 && unit <= MIN (align, BIGGEST_ALIGNMENT)
2107 && (largest_mode == VOIDmode
2108 || unit <= GET_MODE_BITSIZE (largest_mode)))
2112 if (wide_mode != VOIDmode)
2119 /* Gets minimal and maximal values for MODE (signed or unsigned depending on
2120 SIGN). The returned constants are made to be usable in TARGET_MODE. */
2123 get_mode_bounds (enum machine_mode mode, int sign,
2124 enum machine_mode target_mode,
2125 rtx *mmin, rtx *mmax)
2127 unsigned size = GET_MODE_BITSIZE (mode);
2128 unsigned HOST_WIDE_INT min_val, max_val;
2130 if (size > HOST_BITS_PER_WIDE_INT)
2135 min_val = -((unsigned HOST_WIDE_INT) 1 << (size - 1));
2136 max_val = ((unsigned HOST_WIDE_INT) 1 << (size - 1)) - 1;
2141 max_val = ((unsigned HOST_WIDE_INT) 1 << (size - 1) << 1) - 1;
2144 *mmin = GEN_INT (trunc_int_for_mode (min_val, target_mode));
2145 *mmax = GEN_INT (trunc_int_for_mode (max_val, target_mode));
2148 #include "gt-stor-layout.h"