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"
40 /* Data type for the expressions representing sizes of data types.
41 It is the first integer type laid out. */
42 tree sizetype_tab[(int) TYPE_KIND_LAST];
44 /* If nonzero, this is an upper limit on alignment of structure fields.
45 The value is measured in bits. */
46 unsigned int maximum_field_alignment = TARGET_DEFAULT_PACK_STRUCT * BITS_PER_UNIT;
47 /* ... and its original value in bytes, specified via -fpack-struct=<value>. */
48 unsigned int initial_max_fld_align = TARGET_DEFAULT_PACK_STRUCT;
50 /* If nonzero, the alignment of a bitstring or (power-)set value, in bits.
51 May be overridden by front-ends. */
52 unsigned int set_alignment = 0;
54 /* Nonzero if all REFERENCE_TYPEs are internal and hence should be
55 allocated in Pmode, not ptr_mode. Set only by internal_reference_types
56 called only by a front end. */
57 static int reference_types_internal = 0;
59 static void finalize_record_size (record_layout_info);
60 static void finalize_type_size (tree);
61 static void place_union_field (record_layout_info, tree);
62 #if defined (PCC_BITFIELD_TYPE_MATTERS) || defined (BITFIELD_NBYTES_LIMITED)
63 static int excess_unit_span (HOST_WIDE_INT, HOST_WIDE_INT, HOST_WIDE_INT,
66 extern void debug_rli (record_layout_info);
68 /* SAVE_EXPRs for sizes of types and decls, waiting to be expanded. */
70 static GTY(()) tree pending_sizes;
72 /* Show that REFERENCE_TYPES are internal and should be Pmode. Called only
76 internal_reference_types (void)
78 reference_types_internal = 1;
81 /* Get a list of all the objects put on the pending sizes list. */
84 get_pending_sizes (void)
86 tree chain = pending_sizes;
92 /* Add EXPR to the pending sizes list. */
95 put_pending_size (tree expr)
97 /* Strip any simple arithmetic from EXPR to see if it has an underlying
99 expr = skip_simple_arithmetic (expr);
101 if (TREE_CODE (expr) == SAVE_EXPR)
102 pending_sizes = tree_cons (NULL_TREE, expr, pending_sizes);
105 /* Put a chain of objects into the pending sizes list, which must be
109 put_pending_sizes (tree chain)
114 pending_sizes = chain;
117 /* Given a size SIZE that may not be a constant, return a SAVE_EXPR
118 to serve as the actual size-expression for a type or decl. */
121 variable_size (tree size)
125 /* If the language-processor is to take responsibility for variable-sized
126 items (e.g., languages which have elaboration procedures like Ada),
127 just return SIZE unchanged. Likewise for self-referential sizes and
129 if (TREE_CONSTANT (size)
130 || lang_hooks.decls.global_bindings_p () < 0
131 || CONTAINS_PLACEHOLDER_P (size))
134 size = save_expr (size);
136 /* If an array with a variable number of elements is declared, and
137 the elements require destruction, we will emit a cleanup for the
138 array. That cleanup is run both on normal exit from the block
139 and in the exception-handler for the block. Normally, when code
140 is used in both ordinary code and in an exception handler it is
141 `unsaved', i.e., all SAVE_EXPRs are recalculated. However, we do
142 not wish to do that here; the array-size is the same in both
144 save = skip_simple_arithmetic (size);
146 if (cfun && cfun->x_dont_save_pending_sizes_p)
147 /* The front-end doesn't want us to keep a list of the expressions
148 that determine sizes for variable size objects. Trust it. */
151 if (lang_hooks.decls.global_bindings_p ())
153 if (TREE_CONSTANT (size))
154 error ("type size can't be explicitly evaluated");
156 error ("variable-size type declared outside of any function");
158 return size_one_node;
161 put_pending_size (save);
166 #ifndef MAX_FIXED_MODE_SIZE
167 #define MAX_FIXED_MODE_SIZE GET_MODE_BITSIZE (DImode)
170 /* Return the machine mode to use for a nonscalar of SIZE bits. The
171 mode must be in class CLASS, and have exactly that many value bits;
172 it may have padding as well. If LIMIT is nonzero, modes of wider
173 than MAX_FIXED_MODE_SIZE will not be used. */
176 mode_for_size (unsigned int size, enum mode_class class, int limit)
178 enum machine_mode mode;
180 if (limit && size > MAX_FIXED_MODE_SIZE)
183 /* Get the first mode which has this size, in the specified class. */
184 for (mode = GET_CLASS_NARROWEST_MODE (class); mode != VOIDmode;
185 mode = GET_MODE_WIDER_MODE (mode))
186 if (GET_MODE_PRECISION (mode) == size)
192 /* Similar, except passed a tree node. */
195 mode_for_size_tree (tree size, enum mode_class class, int limit)
197 if (TREE_CODE (size) != INTEGER_CST
198 || TREE_OVERFLOW (size)
199 /* What we really want to say here is that the size can fit in a
200 host integer, but we know there's no way we'd find a mode for
201 this many bits, so there's no point in doing the precise test. */
202 || compare_tree_int (size, 1000) > 0)
205 return mode_for_size (tree_low_cst (size, 1), class, limit);
208 /* Similar, but never return BLKmode; return the narrowest mode that
209 contains at least the requested number of value bits. */
212 smallest_mode_for_size (unsigned int size, enum mode_class class)
214 enum machine_mode mode;
216 /* Get the first mode which has at least this size, in the
218 for (mode = GET_CLASS_NARROWEST_MODE (class); mode != VOIDmode;
219 mode = GET_MODE_WIDER_MODE (mode))
220 if (GET_MODE_PRECISION (mode) >= size)
226 /* Find an integer mode of the exact same size, or BLKmode on failure. */
229 int_mode_for_mode (enum machine_mode mode)
231 switch (GET_MODE_CLASS (mode))
234 case MODE_PARTIAL_INT:
237 case MODE_COMPLEX_INT:
238 case MODE_COMPLEX_FLOAT:
240 case MODE_VECTOR_INT:
241 case MODE_VECTOR_FLOAT:
242 mode = mode_for_size (GET_MODE_BITSIZE (mode), MODE_INT, 0);
249 /* ... fall through ... */
259 /* Return the alignment of MODE. This will be bounded by 1 and
260 BIGGEST_ALIGNMENT. */
263 get_mode_alignment (enum machine_mode mode)
265 return MIN (BIGGEST_ALIGNMENT, MAX (1, mode_base_align[mode]*BITS_PER_UNIT));
269 /* Subroutine of layout_decl: Force alignment required for the data type.
270 But if the decl itself wants greater alignment, don't override that. */
273 do_type_align (tree type, tree decl)
275 if (TYPE_ALIGN (type) > DECL_ALIGN (decl))
277 DECL_ALIGN (decl) = TYPE_ALIGN (type);
278 if (TREE_CODE (decl) == FIELD_DECL)
279 DECL_USER_ALIGN (decl) = TYPE_USER_ALIGN (type);
283 /* Set the size, mode and alignment of a ..._DECL node.
284 TYPE_DECL does need this for C++.
285 Note that LABEL_DECL and CONST_DECL nodes do not need this,
286 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
287 Don't call layout_decl for them.
289 KNOWN_ALIGN is the amount of alignment we can assume this
290 decl has with no special effort. It is relevant only for FIELD_DECLs
291 and depends on the previous fields.
292 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
293 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
294 the record will be aligned to suit. */
297 layout_decl (tree decl, unsigned int known_align)
299 tree type = TREE_TYPE (decl);
300 enum tree_code code = TREE_CODE (decl);
303 if (code == CONST_DECL)
305 else if (code != VAR_DECL && code != PARM_DECL && code != RESULT_DECL
306 && code != TYPE_DECL && code != FIELD_DECL)
309 rtl = DECL_RTL_IF_SET (decl);
311 if (type == error_mark_node)
312 type = void_type_node;
314 /* Usually the size and mode come from the data type without change,
315 however, the front-end may set the explicit width of the field, so its
316 size may not be the same as the size of its type. This happens with
317 bitfields, of course (an `int' bitfield may be only 2 bits, say), but it
318 also happens with other fields. For example, the C++ front-end creates
319 zero-sized fields corresponding to empty base classes, and depends on
320 layout_type setting DECL_FIELD_BITPOS correctly for the field. Set the
321 size in bytes from the size in bits. If we have already set the mode,
322 don't set it again since we can be called twice for FIELD_DECLs. */
324 DECL_UNSIGNED (decl) = TYPE_UNSIGNED (type);
325 if (DECL_MODE (decl) == VOIDmode)
326 DECL_MODE (decl) = TYPE_MODE (type);
328 if (DECL_SIZE (decl) == 0)
330 DECL_SIZE (decl) = TYPE_SIZE (type);
331 DECL_SIZE_UNIT (decl) = TYPE_SIZE_UNIT (type);
333 else if (DECL_SIZE_UNIT (decl) == 0)
334 DECL_SIZE_UNIT (decl)
335 = convert (sizetype, size_binop (CEIL_DIV_EXPR, DECL_SIZE (decl),
338 if (code != FIELD_DECL)
339 /* For non-fields, update the alignment from the type. */
340 do_type_align (type, decl);
342 /* For fields, it's a bit more complicated... */
344 bool old_user_align = DECL_USER_ALIGN (decl);
346 if (DECL_BIT_FIELD (decl))
348 DECL_BIT_FIELD_TYPE (decl) = type;
350 /* A zero-length bit-field affects the alignment of the next
352 if (integer_zerop (DECL_SIZE (decl))
353 && ! DECL_PACKED (decl)
354 && ! targetm.ms_bitfield_layout_p (DECL_FIELD_CONTEXT (decl)))
356 #ifdef PCC_BITFIELD_TYPE_MATTERS
357 if (PCC_BITFIELD_TYPE_MATTERS)
358 do_type_align (type, decl);
362 #ifdef EMPTY_FIELD_BOUNDARY
363 if (EMPTY_FIELD_BOUNDARY > DECL_ALIGN (decl))
365 DECL_ALIGN (decl) = EMPTY_FIELD_BOUNDARY;
366 DECL_USER_ALIGN (decl) = 0;
372 /* See if we can use an ordinary integer mode for a bit-field.
373 Conditions are: a fixed size that is correct for another mode
374 and occupying a complete byte or bytes on proper boundary. */
375 if (TYPE_SIZE (type) != 0
376 && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
377 && GET_MODE_CLASS (TYPE_MODE (type)) == MODE_INT)
379 enum machine_mode xmode
380 = mode_for_size_tree (DECL_SIZE (decl), MODE_INT, 1);
384 || known_align >= GET_MODE_ALIGNMENT (xmode)))
386 DECL_ALIGN (decl) = MAX (GET_MODE_ALIGNMENT (xmode),
388 DECL_MODE (decl) = xmode;
389 DECL_BIT_FIELD (decl) = 0;
393 /* Turn off DECL_BIT_FIELD if we won't need it set. */
394 if (TYPE_MODE (type) == BLKmode && DECL_MODE (decl) == BLKmode
395 && known_align >= TYPE_ALIGN (type)
396 && DECL_ALIGN (decl) >= TYPE_ALIGN (type))
397 DECL_BIT_FIELD (decl) = 0;
399 else if (DECL_PACKED (decl) && DECL_USER_ALIGN (decl))
400 /* Don't touch DECL_ALIGN. For other packed fields, go ahead and
401 round up; we'll reduce it again below. We want packing to
402 supersede USER_ALIGN inherited from the type, but defer to
403 alignment explicitly specified on the field decl. */;
405 do_type_align (type, decl);
407 /* If the field is of variable size, we can't misalign it since we
408 have no way to make a temporary to align the result. But this
409 isn't an issue if the decl is not addressable. Likewise if it
412 Note that do_type_align may set DECL_USER_ALIGN, so we need to
413 check old_user_align instead. */
414 if (DECL_PACKED (decl)
416 && (DECL_NONADDRESSABLE_P (decl)
417 || DECL_SIZE_UNIT (decl) == 0
418 || TREE_CODE (DECL_SIZE_UNIT (decl)) == INTEGER_CST))
419 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), BITS_PER_UNIT);
421 if (! DECL_USER_ALIGN (decl) && ! DECL_PACKED (decl))
423 /* Some targets (i.e. i386, VMS) limit struct field alignment
424 to a lower boundary than alignment of variables unless
425 it was overridden by attribute aligned. */
426 #ifdef BIGGEST_FIELD_ALIGNMENT
428 = MIN (DECL_ALIGN (decl), (unsigned) BIGGEST_FIELD_ALIGNMENT);
430 #ifdef ADJUST_FIELD_ALIGN
431 DECL_ALIGN (decl) = ADJUST_FIELD_ALIGN (decl, DECL_ALIGN (decl));
435 /* Should this be controlled by DECL_USER_ALIGN, too? */
436 if (maximum_field_alignment != 0)
437 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), maximum_field_alignment);
440 /* Evaluate nonconstant size only once, either now or as soon as safe. */
441 if (DECL_SIZE (decl) != 0 && TREE_CODE (DECL_SIZE (decl)) != INTEGER_CST)
442 DECL_SIZE (decl) = variable_size (DECL_SIZE (decl));
443 if (DECL_SIZE_UNIT (decl) != 0
444 && TREE_CODE (DECL_SIZE_UNIT (decl)) != INTEGER_CST)
445 DECL_SIZE_UNIT (decl) = variable_size (DECL_SIZE_UNIT (decl));
447 /* If requested, warn about definitions of large data objects. */
449 && (code == VAR_DECL || code == PARM_DECL)
450 && ! DECL_EXTERNAL (decl))
452 tree size = DECL_SIZE_UNIT (decl);
454 if (size != 0 && TREE_CODE (size) == INTEGER_CST
455 && compare_tree_int (size, larger_than_size) > 0)
457 int size_as_int = TREE_INT_CST_LOW (size);
459 if (compare_tree_int (size, size_as_int) == 0)
460 warning ("%Jsize of '%D' is %d bytes", decl, decl, size_as_int);
462 warning ("%Jsize of '%D' is larger than %d bytes",
463 decl, decl, larger_than_size);
467 /* If the RTL was already set, update its mode and mem attributes. */
470 PUT_MODE (rtl, DECL_MODE (decl));
471 SET_DECL_RTL (decl, 0);
472 set_mem_attributes (rtl, decl, 1);
473 SET_DECL_RTL (decl, rtl);
477 /* Given a VAR_DECL, PARM_DECL or RESULT_DECL, clears the results of
478 a previous call to layout_decl and calls it again. */
481 relayout_decl (tree decl)
483 DECL_SIZE (decl) = DECL_SIZE_UNIT (decl) = 0;
484 DECL_MODE (decl) = VOIDmode;
485 DECL_ALIGN (decl) = 0;
486 SET_DECL_RTL (decl, 0);
488 layout_decl (decl, 0);
491 /* Hook for a front-end function that can modify the record layout as needed
492 immediately before it is finalized. */
494 void (*lang_adjust_rli) (record_layout_info) = 0;
497 set_lang_adjust_rli (void (*f) (record_layout_info))
502 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
503 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
504 is to be passed to all other layout functions for this record. It is the
505 responsibility of the caller to call `free' for the storage returned.
506 Note that garbage collection is not permitted until we finish laying
510 start_record_layout (tree t)
512 record_layout_info rli = xmalloc (sizeof (struct record_layout_info_s));
516 /* If the type has a minimum specified alignment (via an attribute
517 declaration, for example) use it -- otherwise, start with a
518 one-byte alignment. */
519 rli->record_align = MAX (BITS_PER_UNIT, TYPE_ALIGN (t));
520 rli->unpacked_align = rli->record_align;
521 rli->offset_align = MAX (rli->record_align, BIGGEST_ALIGNMENT);
523 #ifdef STRUCTURE_SIZE_BOUNDARY
524 /* Packed structures don't need to have minimum size. */
525 if (! TYPE_PACKED (t))
526 rli->record_align = MAX (rli->record_align, (unsigned) STRUCTURE_SIZE_BOUNDARY);
529 rli->offset = size_zero_node;
530 rli->bitpos = bitsize_zero_node;
532 rli->pending_statics = 0;
533 rli->packed_maybe_necessary = 0;
538 /* These four routines perform computations that convert between
539 the offset/bitpos forms and byte and bit offsets. */
542 bit_from_pos (tree offset, tree bitpos)
544 return size_binop (PLUS_EXPR, bitpos,
545 size_binop (MULT_EXPR, convert (bitsizetype, offset),
550 byte_from_pos (tree offset, tree bitpos)
552 return size_binop (PLUS_EXPR, offset,
554 size_binop (TRUNC_DIV_EXPR, bitpos,
555 bitsize_unit_node)));
559 pos_from_bit (tree *poffset, tree *pbitpos, unsigned int off_align,
562 *poffset = size_binop (MULT_EXPR,
564 size_binop (FLOOR_DIV_EXPR, pos,
565 bitsize_int (off_align))),
566 size_int (off_align / BITS_PER_UNIT));
567 *pbitpos = size_binop (FLOOR_MOD_EXPR, pos, bitsize_int (off_align));
570 /* Given a pointer to bit and byte offsets and an offset alignment,
571 normalize the offsets so they are within the alignment. */
574 normalize_offset (tree *poffset, tree *pbitpos, unsigned int off_align)
576 /* If the bit position is now larger than it should be, adjust it
578 if (compare_tree_int (*pbitpos, off_align) >= 0)
580 tree extra_aligns = size_binop (FLOOR_DIV_EXPR, *pbitpos,
581 bitsize_int (off_align));
584 = size_binop (PLUS_EXPR, *poffset,
585 size_binop (MULT_EXPR, convert (sizetype, extra_aligns),
586 size_int (off_align / BITS_PER_UNIT)));
589 = size_binop (FLOOR_MOD_EXPR, *pbitpos, bitsize_int (off_align));
593 /* Print debugging information about the information in RLI. */
596 debug_rli (record_layout_info rli)
598 print_node_brief (stderr, "type", rli->t, 0);
599 print_node_brief (stderr, "\noffset", rli->offset, 0);
600 print_node_brief (stderr, " bitpos", rli->bitpos, 0);
602 fprintf (stderr, "\naligns: rec = %u, unpack = %u, off = %u\n",
603 rli->record_align, rli->unpacked_align,
605 if (rli->packed_maybe_necessary)
606 fprintf (stderr, "packed may be necessary\n");
608 if (rli->pending_statics)
610 fprintf (stderr, "pending statics:\n");
611 debug_tree (rli->pending_statics);
615 /* Given an RLI with a possibly-incremented BITPOS, adjust OFFSET and
616 BITPOS if necessary to keep BITPOS below OFFSET_ALIGN. */
619 normalize_rli (record_layout_info rli)
621 normalize_offset (&rli->offset, &rli->bitpos, rli->offset_align);
624 /* Returns the size in bytes allocated so far. */
627 rli_size_unit_so_far (record_layout_info rli)
629 return byte_from_pos (rli->offset, rli->bitpos);
632 /* Returns the size in bits allocated so far. */
635 rli_size_so_far (record_layout_info rli)
637 return bit_from_pos (rli->offset, rli->bitpos);
640 /* FIELD is about to be added to RLI->T. The alignment (in bits) of
641 the next available location is given by KNOWN_ALIGN. Update the
642 variable alignment fields in RLI, and return the alignment to give
646 update_alignment_for_field (record_layout_info rli, tree field,
647 unsigned int known_align)
649 /* The alignment required for FIELD. */
650 unsigned int desired_align;
651 /* The type of this field. */
652 tree type = TREE_TYPE (field);
653 /* True if the field was explicitly aligned by the user. */
657 /* Lay out the field so we know what alignment it needs. */
658 layout_decl (field, known_align);
659 desired_align = DECL_ALIGN (field);
660 user_align = DECL_USER_ALIGN (field);
662 is_bitfield = (type != error_mark_node
663 && DECL_BIT_FIELD_TYPE (field)
664 && ! integer_zerop (TYPE_SIZE (type)));
666 /* Record must have at least as much alignment as any field.
667 Otherwise, the alignment of the field within the record is
669 if (is_bitfield && targetm.ms_bitfield_layout_p (rli->t))
671 /* Here, the alignment of the underlying type of a bitfield can
672 affect the alignment of a record; even a zero-sized field
673 can do this. The alignment should be to the alignment of
674 the type, except that for zero-size bitfields this only
675 applies if there was an immediately prior, nonzero-size
676 bitfield. (That's the way it is, experimentally.) */
677 if (! integer_zerop (DECL_SIZE (field))
678 ? ! DECL_PACKED (field)
680 && DECL_BIT_FIELD_TYPE (rli->prev_field)
681 && ! integer_zerop (DECL_SIZE (rli->prev_field))))
683 unsigned int type_align = TYPE_ALIGN (type);
684 type_align = MAX (type_align, desired_align);
685 if (maximum_field_alignment != 0)
686 type_align = MIN (type_align, maximum_field_alignment);
687 rli->record_align = MAX (rli->record_align, type_align);
688 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
691 #ifdef PCC_BITFIELD_TYPE_MATTERS
692 else if (is_bitfield && PCC_BITFIELD_TYPE_MATTERS)
694 /* Named bit-fields cause the entire structure to have the
695 alignment implied by their type. Some targets also apply the same
696 rules to unnamed bitfields. */
697 if (DECL_NAME (field) != 0
698 || targetm.align_anon_bitfield ())
700 unsigned int type_align = TYPE_ALIGN (type);
702 #ifdef ADJUST_FIELD_ALIGN
703 if (! TYPE_USER_ALIGN (type))
704 type_align = ADJUST_FIELD_ALIGN (field, type_align);
707 if (maximum_field_alignment != 0)
708 type_align = MIN (type_align, maximum_field_alignment);
709 else if (DECL_PACKED (field))
710 type_align = MIN (type_align, BITS_PER_UNIT);
712 /* The alignment of the record is increased to the maximum
713 of the current alignment, the alignment indicated on the
714 field (i.e., the alignment specified by an __aligned__
715 attribute), and the alignment indicated by the type of
717 rli->record_align = MAX (rli->record_align, desired_align);
718 rli->record_align = MAX (rli->record_align, type_align);
721 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
722 user_align |= TYPE_USER_ALIGN (type);
728 rli->record_align = MAX (rli->record_align, desired_align);
729 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
732 TYPE_USER_ALIGN (rli->t) |= user_align;
734 return desired_align;
737 /* Called from place_field to handle unions. */
740 place_union_field (record_layout_info rli, tree field)
742 update_alignment_for_field (rli, field, /*known_align=*/0);
744 DECL_FIELD_OFFSET (field) = size_zero_node;
745 DECL_FIELD_BIT_OFFSET (field) = bitsize_zero_node;
746 SET_DECL_OFFSET_ALIGN (field, BIGGEST_ALIGNMENT);
748 /* We assume the union's size will be a multiple of a byte so we don't
749 bother with BITPOS. */
750 if (TREE_CODE (rli->t) == UNION_TYPE)
751 rli->offset = size_binop (MAX_EXPR, rli->offset, DECL_SIZE_UNIT (field));
752 else if (TREE_CODE (rli->t) == QUAL_UNION_TYPE)
753 rli->offset = fold (build3 (COND_EXPR, sizetype,
754 DECL_QUALIFIER (field),
755 DECL_SIZE_UNIT (field), rli->offset));
758 #if defined (PCC_BITFIELD_TYPE_MATTERS) || defined (BITFIELD_NBYTES_LIMITED)
759 /* A bitfield of SIZE with a required access alignment of ALIGN is allocated
760 at BYTE_OFFSET / BIT_OFFSET. Return nonzero if the field would span more
761 units of alignment than the underlying TYPE. */
763 excess_unit_span (HOST_WIDE_INT byte_offset, HOST_WIDE_INT bit_offset,
764 HOST_WIDE_INT size, HOST_WIDE_INT align, tree type)
766 /* Note that the calculation of OFFSET might overflow; we calculate it so
767 that we still get the right result as long as ALIGN is a power of two. */
768 unsigned HOST_WIDE_INT offset = byte_offset * BITS_PER_UNIT + bit_offset;
770 offset = offset % align;
771 return ((offset + size + align - 1) / align
772 > ((unsigned HOST_WIDE_INT) tree_low_cst (TYPE_SIZE (type), 1)
777 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
778 is a FIELD_DECL to be added after those fields already present in
779 T. (FIELD is not actually added to the TYPE_FIELDS list here;
780 callers that desire that behavior must manually perform that step.) */
783 place_field (record_layout_info rli, tree field)
785 /* The alignment required for FIELD. */
786 unsigned int desired_align;
787 /* The alignment FIELD would have if we just dropped it into the
788 record as it presently stands. */
789 unsigned int known_align;
790 unsigned int actual_align;
791 /* The type of this field. */
792 tree type = TREE_TYPE (field);
794 if (TREE_CODE (field) == ERROR_MARK || TREE_CODE (type) == ERROR_MARK)
797 /* If FIELD is static, then treat it like a separate variable, not
798 really like a structure field. If it is a FUNCTION_DECL, it's a
799 method. In both cases, all we do is lay out the decl, and we do
800 it *after* the record is laid out. */
801 if (TREE_CODE (field) == VAR_DECL)
803 rli->pending_statics = tree_cons (NULL_TREE, field,
804 rli->pending_statics);
808 /* Enumerators and enum types which are local to this class need not
809 be laid out. Likewise for initialized constant fields. */
810 else if (TREE_CODE (field) != FIELD_DECL)
813 /* Unions are laid out very differently than records, so split
814 that code off to another function. */
815 else if (TREE_CODE (rli->t) != RECORD_TYPE)
817 place_union_field (rli, field);
821 /* Work out the known alignment so far. Note that A & (-A) is the
822 value of the least-significant bit in A that is one. */
823 if (! integer_zerop (rli->bitpos))
824 known_align = (tree_low_cst (rli->bitpos, 1)
825 & - tree_low_cst (rli->bitpos, 1));
826 else if (integer_zerop (rli->offset))
827 known_align = BIGGEST_ALIGNMENT;
828 else if (host_integerp (rli->offset, 1))
829 known_align = (BITS_PER_UNIT
830 * (tree_low_cst (rli->offset, 1)
831 & - tree_low_cst (rli->offset, 1)));
833 known_align = rli->offset_align;
835 desired_align = update_alignment_for_field (rli, field, known_align);
837 if (warn_packed && DECL_PACKED (field))
839 if (known_align >= TYPE_ALIGN (type))
841 if (TYPE_ALIGN (type) > desired_align)
843 if (STRICT_ALIGNMENT)
844 warning ("%Jpacked attribute causes inefficient alignment "
845 "for '%D'", field, field);
847 warning ("%Jpacked attribute is unnecessary for '%D'",
852 rli->packed_maybe_necessary = 1;
855 /* Does this field automatically have alignment it needs by virtue
856 of the fields that precede it and the record's own alignment? */
857 if (known_align < desired_align)
859 /* No, we need to skip space before this field.
860 Bump the cumulative size to multiple of field alignment. */
863 warning ("%Jpadding struct to align '%D'", field, field);
865 /* If the alignment is still within offset_align, just align
867 if (desired_align < rli->offset_align)
868 rli->bitpos = round_up (rli->bitpos, desired_align);
871 /* First adjust OFFSET by the partial bits, then align. */
873 = size_binop (PLUS_EXPR, rli->offset,
875 size_binop (CEIL_DIV_EXPR, rli->bitpos,
876 bitsize_unit_node)));
877 rli->bitpos = bitsize_zero_node;
879 rli->offset = round_up (rli->offset, desired_align / BITS_PER_UNIT);
882 if (! TREE_CONSTANT (rli->offset))
883 rli->offset_align = desired_align;
887 /* Handle compatibility with PCC. Note that if the record has any
888 variable-sized fields, we need not worry about compatibility. */
889 #ifdef PCC_BITFIELD_TYPE_MATTERS
890 if (PCC_BITFIELD_TYPE_MATTERS
891 && ! targetm.ms_bitfield_layout_p (rli->t)
892 && TREE_CODE (field) == FIELD_DECL
893 && type != error_mark_node
894 && DECL_BIT_FIELD (field)
895 && ! DECL_PACKED (field)
896 && maximum_field_alignment == 0
897 && ! integer_zerop (DECL_SIZE (field))
898 && host_integerp (DECL_SIZE (field), 1)
899 && host_integerp (rli->offset, 1)
900 && host_integerp (TYPE_SIZE (type), 1))
902 unsigned int type_align = TYPE_ALIGN (type);
903 tree dsize = DECL_SIZE (field);
904 HOST_WIDE_INT field_size = tree_low_cst (dsize, 1);
905 HOST_WIDE_INT offset = tree_low_cst (rli->offset, 0);
906 HOST_WIDE_INT bit_offset = tree_low_cst (rli->bitpos, 0);
908 #ifdef ADJUST_FIELD_ALIGN
909 if (! TYPE_USER_ALIGN (type))
910 type_align = ADJUST_FIELD_ALIGN (field, type_align);
913 /* A bit field may not span more units of alignment of its type
914 than its type itself. Advance to next boundary if necessary. */
915 if (excess_unit_span (offset, bit_offset, field_size, type_align, type))
916 rli->bitpos = round_up (rli->bitpos, type_align);
918 TYPE_USER_ALIGN (rli->t) |= TYPE_USER_ALIGN (type);
922 #ifdef BITFIELD_NBYTES_LIMITED
923 if (BITFIELD_NBYTES_LIMITED
924 && ! targetm.ms_bitfield_layout_p (rli->t)
925 && TREE_CODE (field) == FIELD_DECL
926 && type != error_mark_node
927 && DECL_BIT_FIELD_TYPE (field)
928 && ! DECL_PACKED (field)
929 && ! integer_zerop (DECL_SIZE (field))
930 && host_integerp (DECL_SIZE (field), 1)
931 && host_integerp (rli->offset, 1)
932 && host_integerp (TYPE_SIZE (type), 1))
934 unsigned int type_align = TYPE_ALIGN (type);
935 tree dsize = DECL_SIZE (field);
936 HOST_WIDE_INT field_size = tree_low_cst (dsize, 1);
937 HOST_WIDE_INT offset = tree_low_cst (rli->offset, 0);
938 HOST_WIDE_INT bit_offset = tree_low_cst (rli->bitpos, 0);
940 #ifdef ADJUST_FIELD_ALIGN
941 if (! TYPE_USER_ALIGN (type))
942 type_align = ADJUST_FIELD_ALIGN (field, type_align);
945 if (maximum_field_alignment != 0)
946 type_align = MIN (type_align, maximum_field_alignment);
947 /* ??? This test is opposite the test in the containing if
948 statement, so this code is unreachable currently. */
949 else if (DECL_PACKED (field))
950 type_align = MIN (type_align, BITS_PER_UNIT);
952 /* A bit field may not span the unit of alignment of its type.
953 Advance to next boundary if necessary. */
954 if (excess_unit_span (offset, bit_offset, field_size, type_align, type))
955 rli->bitpos = round_up (rli->bitpos, type_align);
957 TYPE_USER_ALIGN (rli->t) |= TYPE_USER_ALIGN (type);
961 /* See the docs for TARGET_MS_BITFIELD_LAYOUT_P for details.
963 When a bit field is inserted into a packed record, the whole
964 size of the underlying type is used by one or more same-size
965 adjacent bitfields. (That is, if its long:3, 32 bits is
966 used in the record, and any additional adjacent long bitfields are
967 packed into the same chunk of 32 bits. However, if the size
968 changes, a new field of that size is allocated.) In an unpacked
969 record, this is the same as using alignment, but not equivalent
972 Note: for compatibility, we use the type size, not the type alignment
973 to determine alignment, since that matches the documentation */
975 if (targetm.ms_bitfield_layout_p (rli->t)
976 && ((DECL_BIT_FIELD_TYPE (field) && ! DECL_PACKED (field))
977 || (rli->prev_field && ! DECL_PACKED (rli->prev_field))))
979 /* At this point, either the prior or current are bitfields,
980 (possibly both), and we're dealing with MS packing. */
981 tree prev_saved = rli->prev_field;
983 /* Is the prior field a bitfield? If so, handle "runs" of same
985 if (rli->prev_field /* necessarily a bitfield if it exists. */)
987 /* If both are bitfields, nonzero, and the same size, this is
988 the middle of a run. Zero declared size fields are special
989 and handled as "end of run". (Note: it's nonzero declared
990 size, but equal type sizes!) (Since we know that both
991 the current and previous fields are bitfields by the
992 time we check it, DECL_SIZE must be present for both.) */
993 if (DECL_BIT_FIELD_TYPE (field)
994 && !integer_zerop (DECL_SIZE (field))
995 && !integer_zerop (DECL_SIZE (rli->prev_field))
996 && host_integerp (DECL_SIZE (rli->prev_field), 0)
997 && host_integerp (TYPE_SIZE (type), 0)
998 && simple_cst_equal (TYPE_SIZE (type),
999 TYPE_SIZE (TREE_TYPE (rli->prev_field))))
1001 /* We're in the middle of a run of equal type size fields; make
1002 sure we realign if we run out of bits. (Not decl size,
1004 HOST_WIDE_INT bitsize = tree_low_cst (DECL_SIZE (field), 0);
1006 if (rli->remaining_in_alignment < bitsize)
1008 /* out of bits; bump up to next 'word'. */
1009 rli->offset = DECL_FIELD_OFFSET (rli->prev_field);
1011 = size_binop (PLUS_EXPR, TYPE_SIZE (type),
1012 DECL_FIELD_BIT_OFFSET (rli->prev_field));
1013 rli->prev_field = field;
1014 rli->remaining_in_alignment
1015 = tree_low_cst (TYPE_SIZE (type), 0);
1018 rli->remaining_in_alignment -= bitsize;
1022 /* End of a run: if leaving a run of bitfields of the same type
1023 size, we have to "use up" the rest of the bits of the type
1026 Compute the new position as the sum of the size for the prior
1027 type and where we first started working on that type.
1028 Note: since the beginning of the field was aligned then
1029 of course the end will be too. No round needed. */
1031 if (!integer_zerop (DECL_SIZE (rli->prev_field)))
1033 tree type_size = TYPE_SIZE (TREE_TYPE (rli->prev_field));
1036 = size_binop (PLUS_EXPR, type_size,
1037 DECL_FIELD_BIT_OFFSET (rli->prev_field));
1040 /* We "use up" size zero fields; the code below should behave
1041 as if the prior field was not a bitfield. */
1044 /* Cause a new bitfield to be captured, either this time (if
1045 currently a bitfield) or next time we see one. */
1046 if (!DECL_BIT_FIELD_TYPE(field)
1047 || integer_zerop (DECL_SIZE (field)))
1048 rli->prev_field = NULL;
1051 normalize_rli (rli);
1054 /* If we're starting a new run of same size type bitfields
1055 (or a run of non-bitfields), set up the "first of the run"
1058 That is, if the current field is not a bitfield, or if there
1059 was a prior bitfield the type sizes differ, or if there wasn't
1060 a prior bitfield the size of the current field is nonzero.
1062 Note: we must be sure to test ONLY the type size if there was
1063 a prior bitfield and ONLY for the current field being zero if
1066 if (!DECL_BIT_FIELD_TYPE (field)
1067 || ( prev_saved != NULL
1068 ? !simple_cst_equal (TYPE_SIZE (type),
1069 TYPE_SIZE (TREE_TYPE (prev_saved)))
1070 : !integer_zerop (DECL_SIZE (field)) ))
1072 /* Never smaller than a byte for compatibility. */
1073 unsigned int type_align = BITS_PER_UNIT;
1075 /* (When not a bitfield), we could be seeing a flex array (with
1076 no DECL_SIZE). Since we won't be using remaining_in_alignment
1077 until we see a bitfield (and come by here again) we just skip
1079 if (DECL_SIZE (field) != NULL
1080 && host_integerp (TYPE_SIZE (TREE_TYPE (field)), 0)
1081 && host_integerp (DECL_SIZE (field), 0))
1082 rli->remaining_in_alignment
1083 = tree_low_cst (TYPE_SIZE (TREE_TYPE(field)), 0)
1084 - tree_low_cst (DECL_SIZE (field), 0);
1086 /* Now align (conventionally) for the new type. */
1087 if (!DECL_PACKED(field))
1088 type_align = MAX(TYPE_ALIGN (type), type_align);
1091 && DECL_BIT_FIELD_TYPE (prev_saved)
1092 /* If the previous bit-field is zero-sized, we've already
1093 accounted for its alignment needs (or ignored it, if
1094 appropriate) while placing it. */
1095 && ! integer_zerop (DECL_SIZE (prev_saved)))
1096 type_align = MAX (type_align,
1097 TYPE_ALIGN (TREE_TYPE (prev_saved)));
1099 if (maximum_field_alignment != 0)
1100 type_align = MIN (type_align, maximum_field_alignment);
1102 rli->bitpos = round_up (rli->bitpos, type_align);
1104 /* If we really aligned, don't allow subsequent bitfields
1106 rli->prev_field = NULL;
1110 /* Offset so far becomes the position of this field after normalizing. */
1111 normalize_rli (rli);
1112 DECL_FIELD_OFFSET (field) = rli->offset;
1113 DECL_FIELD_BIT_OFFSET (field) = rli->bitpos;
1114 SET_DECL_OFFSET_ALIGN (field, rli->offset_align);
1116 /* If this field ended up more aligned than we thought it would be (we
1117 approximate this by seeing if its position changed), lay out the field
1118 again; perhaps we can use an integral mode for it now. */
1119 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field)))
1120 actual_align = (tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1)
1121 & - tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1));
1122 else if (integer_zerop (DECL_FIELD_OFFSET (field)))
1123 actual_align = BIGGEST_ALIGNMENT;
1124 else if (host_integerp (DECL_FIELD_OFFSET (field), 1))
1125 actual_align = (BITS_PER_UNIT
1126 * (tree_low_cst (DECL_FIELD_OFFSET (field), 1)
1127 & - tree_low_cst (DECL_FIELD_OFFSET (field), 1)));
1129 actual_align = DECL_OFFSET_ALIGN (field);
1131 if (known_align != actual_align)
1132 layout_decl (field, actual_align);
1134 /* Only the MS bitfields use this. */
1135 if (rli->prev_field == NULL && DECL_BIT_FIELD_TYPE(field))
1136 rli->prev_field = field;
1138 /* Now add size of this field to the size of the record. If the size is
1139 not constant, treat the field as being a multiple of bytes and just
1140 adjust the offset, resetting the bit position. Otherwise, apportion the
1141 size amongst the bit position and offset. First handle the case of an
1142 unspecified size, which can happen when we have an invalid nested struct
1143 definition, such as struct j { struct j { int i; } }. The error message
1144 is printed in finish_struct. */
1145 if (DECL_SIZE (field) == 0)
1147 else if (TREE_CODE (DECL_SIZE_UNIT (field)) != INTEGER_CST
1148 || TREE_CONSTANT_OVERFLOW (DECL_SIZE_UNIT (field)))
1151 = size_binop (PLUS_EXPR, rli->offset,
1153 size_binop (CEIL_DIV_EXPR, rli->bitpos,
1154 bitsize_unit_node)));
1156 = size_binop (PLUS_EXPR, rli->offset, DECL_SIZE_UNIT (field));
1157 rli->bitpos = bitsize_zero_node;
1158 rli->offset_align = MIN (rli->offset_align, desired_align);
1162 rli->bitpos = size_binop (PLUS_EXPR, rli->bitpos, DECL_SIZE (field));
1163 normalize_rli (rli);
1167 /* Assuming that all the fields have been laid out, this function uses
1168 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
1169 indicated by RLI. */
1172 finalize_record_size (record_layout_info rli)
1174 tree unpadded_size, unpadded_size_unit;
1176 /* Now we want just byte and bit offsets, so set the offset alignment
1177 to be a byte and then normalize. */
1178 rli->offset_align = BITS_PER_UNIT;
1179 normalize_rli (rli);
1181 /* Determine the desired alignment. */
1182 #ifdef ROUND_TYPE_ALIGN
1183 TYPE_ALIGN (rli->t) = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t),
1186 TYPE_ALIGN (rli->t) = MAX (TYPE_ALIGN (rli->t), rli->record_align);
1189 /* Compute the size so far. Be sure to allow for extra bits in the
1190 size in bytes. We have guaranteed above that it will be no more
1191 than a single byte. */
1192 unpadded_size = rli_size_so_far (rli);
1193 unpadded_size_unit = rli_size_unit_so_far (rli);
1194 if (! integer_zerop (rli->bitpos))
1196 = size_binop (PLUS_EXPR, unpadded_size_unit, size_one_node);
1198 /* Round the size up to be a multiple of the required alignment. */
1199 TYPE_SIZE (rli->t) = round_up (unpadded_size, TYPE_ALIGN (rli->t));
1200 TYPE_SIZE_UNIT (rli->t)
1201 = round_up (unpadded_size_unit, TYPE_ALIGN_UNIT (rli->t));
1203 if (warn_padded && TREE_CONSTANT (unpadded_size)
1204 && simple_cst_equal (unpadded_size, TYPE_SIZE (rli->t)) == 0)
1205 warning ("padding struct size to alignment boundary");
1207 if (warn_packed && TREE_CODE (rli->t) == RECORD_TYPE
1208 && TYPE_PACKED (rli->t) && ! rli->packed_maybe_necessary
1209 && TREE_CONSTANT (unpadded_size))
1213 #ifdef ROUND_TYPE_ALIGN
1215 = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t), rli->unpacked_align);
1217 rli->unpacked_align = MAX (TYPE_ALIGN (rli->t), rli->unpacked_align);
1220 unpacked_size = round_up (TYPE_SIZE (rli->t), rli->unpacked_align);
1221 if (simple_cst_equal (unpacked_size, TYPE_SIZE (rli->t)))
1223 TYPE_PACKED (rli->t) = 0;
1225 if (TYPE_NAME (rli->t))
1229 if (TREE_CODE (TYPE_NAME (rli->t)) == IDENTIFIER_NODE)
1230 name = IDENTIFIER_POINTER (TYPE_NAME (rli->t));
1232 name = IDENTIFIER_POINTER (DECL_NAME (TYPE_NAME (rli->t)));
1234 if (STRICT_ALIGNMENT)
1235 warning ("packed attribute causes inefficient alignment for `%s'", name);
1237 warning ("packed attribute is unnecessary for `%s'", name);
1241 if (STRICT_ALIGNMENT)
1242 warning ("packed attribute causes inefficient alignment");
1244 warning ("packed attribute is unnecessary");
1250 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
1253 compute_record_mode (tree type)
1256 enum machine_mode mode = VOIDmode;
1258 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
1259 However, if possible, we use a mode that fits in a register
1260 instead, in order to allow for better optimization down the
1262 TYPE_MODE (type) = BLKmode;
1264 if (! host_integerp (TYPE_SIZE (type), 1))
1267 /* A record which has any BLKmode members must itself be
1268 BLKmode; it can't go in a register. Unless the member is
1269 BLKmode only because it isn't aligned. */
1270 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1272 if (TREE_CODE (field) != FIELD_DECL)
1275 if (TREE_CODE (TREE_TYPE (field)) == ERROR_MARK
1276 || (TYPE_MODE (TREE_TYPE (field)) == BLKmode
1277 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field))
1278 && !(TYPE_SIZE (TREE_TYPE (field)) != 0
1279 && integer_zerop (TYPE_SIZE (TREE_TYPE (field)))))
1280 || ! host_integerp (bit_position (field), 1)
1281 || DECL_SIZE (field) == 0
1282 || ! host_integerp (DECL_SIZE (field), 1))
1285 /* If this field is the whole struct, remember its mode so
1286 that, say, we can put a double in a class into a DF
1287 register instead of forcing it to live in the stack. */
1288 if (simple_cst_equal (TYPE_SIZE (type), DECL_SIZE (field)))
1289 mode = DECL_MODE (field);
1291 #ifdef MEMBER_TYPE_FORCES_BLK
1292 /* With some targets, eg. c4x, it is sub-optimal
1293 to access an aligned BLKmode structure as a scalar. */
1295 if (MEMBER_TYPE_FORCES_BLK (field, mode))
1297 #endif /* MEMBER_TYPE_FORCES_BLK */
1300 /* If we only have one real field; use its mode. This only applies to
1301 RECORD_TYPE. This does not apply to unions. */
1302 if (TREE_CODE (type) == RECORD_TYPE && mode != VOIDmode)
1303 TYPE_MODE (type) = mode;
1305 TYPE_MODE (type) = mode_for_size_tree (TYPE_SIZE (type), MODE_INT, 1);
1307 /* If structure's known alignment is less than what the scalar
1308 mode would need, and it matters, then stick with BLKmode. */
1309 if (TYPE_MODE (type) != BLKmode
1311 && ! (TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT
1312 || TYPE_ALIGN (type) >= GET_MODE_ALIGNMENT (TYPE_MODE (type))))
1314 /* If this is the only reason this type is BLKmode, then
1315 don't force containing types to be BLKmode. */
1316 TYPE_NO_FORCE_BLK (type) = 1;
1317 TYPE_MODE (type) = BLKmode;
1321 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1325 finalize_type_size (tree type)
1327 /* Normally, use the alignment corresponding to the mode chosen.
1328 However, where strict alignment is not required, avoid
1329 over-aligning structures, since most compilers do not do this
1332 if (TYPE_MODE (type) != BLKmode && TYPE_MODE (type) != VOIDmode
1333 && (STRICT_ALIGNMENT
1334 || (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE
1335 && TREE_CODE (type) != QUAL_UNION_TYPE
1336 && TREE_CODE (type) != ARRAY_TYPE)))
1338 TYPE_ALIGN (type) = GET_MODE_ALIGNMENT (TYPE_MODE (type));
1339 TYPE_USER_ALIGN (type) = 0;
1342 /* Do machine-dependent extra alignment. */
1343 #ifdef ROUND_TYPE_ALIGN
1345 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (type), BITS_PER_UNIT);
1348 /* If we failed to find a simple way to calculate the unit size
1349 of the type, find it by division. */
1350 if (TYPE_SIZE_UNIT (type) == 0 && TYPE_SIZE (type) != 0)
1351 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1352 result will fit in sizetype. We will get more efficient code using
1353 sizetype, so we force a conversion. */
1354 TYPE_SIZE_UNIT (type)
1355 = convert (sizetype,
1356 size_binop (FLOOR_DIV_EXPR, TYPE_SIZE (type),
1357 bitsize_unit_node));
1359 if (TYPE_SIZE (type) != 0)
1361 TYPE_SIZE (type) = round_up (TYPE_SIZE (type), TYPE_ALIGN (type));
1362 TYPE_SIZE_UNIT (type) = round_up (TYPE_SIZE_UNIT (type),
1363 TYPE_ALIGN_UNIT (type));
1366 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1367 if (TYPE_SIZE (type) != 0 && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
1368 TYPE_SIZE (type) = variable_size (TYPE_SIZE (type));
1369 if (TYPE_SIZE_UNIT (type) != 0
1370 && TREE_CODE (TYPE_SIZE_UNIT (type)) != INTEGER_CST)
1371 TYPE_SIZE_UNIT (type) = variable_size (TYPE_SIZE_UNIT (type));
1373 /* Also layout any other variants of the type. */
1374 if (TYPE_NEXT_VARIANT (type)
1375 || type != TYPE_MAIN_VARIANT (type))
1378 /* Record layout info of this variant. */
1379 tree size = TYPE_SIZE (type);
1380 tree size_unit = TYPE_SIZE_UNIT (type);
1381 unsigned int align = TYPE_ALIGN (type);
1382 unsigned int user_align = TYPE_USER_ALIGN (type);
1383 enum machine_mode mode = TYPE_MODE (type);
1385 /* Copy it into all variants. */
1386 for (variant = TYPE_MAIN_VARIANT (type);
1388 variant = TYPE_NEXT_VARIANT (variant))
1390 TYPE_SIZE (variant) = size;
1391 TYPE_SIZE_UNIT (variant) = size_unit;
1392 TYPE_ALIGN (variant) = align;
1393 TYPE_USER_ALIGN (variant) = user_align;
1394 TYPE_MODE (variant) = mode;
1399 /* Do all of the work required to layout the type indicated by RLI,
1400 once the fields have been laid out. This function will call `free'
1401 for RLI, unless FREE_P is false. Passing a value other than false
1402 for FREE_P is bad practice; this option only exists to support the
1406 finish_record_layout (record_layout_info rli, int free_p)
1408 /* Compute the final size. */
1409 finalize_record_size (rli);
1411 /* Compute the TYPE_MODE for the record. */
1412 compute_record_mode (rli->t);
1414 /* Perform any last tweaks to the TYPE_SIZE, etc. */
1415 finalize_type_size (rli->t);
1417 /* Lay out any static members. This is done now because their type
1418 may use the record's type. */
1419 while (rli->pending_statics)
1421 layout_decl (TREE_VALUE (rli->pending_statics), 0);
1422 rli->pending_statics = TREE_CHAIN (rli->pending_statics);
1431 /* Finish processing a builtin RECORD_TYPE type TYPE. It's name is
1432 NAME, its fields are chained in reverse on FIELDS.
1434 If ALIGN_TYPE is non-null, it is given the same alignment as
1438 finish_builtin_struct (tree type, const char *name, tree fields,
1443 for (tail = NULL_TREE; fields; tail = fields, fields = next)
1445 DECL_FIELD_CONTEXT (fields) = type;
1446 next = TREE_CHAIN (fields);
1447 TREE_CHAIN (fields) = tail;
1449 TYPE_FIELDS (type) = tail;
1453 TYPE_ALIGN (type) = TYPE_ALIGN (align_type);
1454 TYPE_USER_ALIGN (type) = TYPE_USER_ALIGN (align_type);
1458 #if 0 /* not yet, should get fixed properly later */
1459 TYPE_NAME (type) = make_type_decl (get_identifier (name), type);
1461 TYPE_NAME (type) = build_decl (TYPE_DECL, get_identifier (name), type);
1463 TYPE_STUB_DECL (type) = TYPE_NAME (type);
1464 layout_decl (TYPE_NAME (type), 0);
1467 /* Calculate the mode, size, and alignment for TYPE.
1468 For an array type, calculate the element separation as well.
1469 Record TYPE on the chain of permanent or temporary types
1470 so that dbxout will find out about it.
1472 TYPE_SIZE of a type is nonzero if the type has been laid out already.
1473 layout_type does nothing on such a type.
1475 If the type is incomplete, its TYPE_SIZE remains zero. */
1478 layout_type (tree type)
1483 if (type == error_mark_node)
1486 /* Do nothing if type has been laid out before. */
1487 if (TYPE_SIZE (type))
1490 switch (TREE_CODE (type))
1493 /* This kind of type is the responsibility
1494 of the language-specific code. */
1497 case BOOLEAN_TYPE: /* Used for Java, Pascal, and Chill. */
1498 if (TYPE_PRECISION (type) == 0)
1499 TYPE_PRECISION (type) = 1; /* default to one byte/boolean. */
1501 /* ... fall through ... */
1506 if (TREE_CODE (TYPE_MIN_VALUE (type)) == INTEGER_CST
1507 && tree_int_cst_sgn (TYPE_MIN_VALUE (type)) >= 0)
1508 TYPE_UNSIGNED (type) = 1;
1510 TYPE_MODE (type) = smallest_mode_for_size (TYPE_PRECISION (type),
1512 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1513 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1517 TYPE_MODE (type) = mode_for_size (TYPE_PRECISION (type), MODE_FLOAT, 0);
1518 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1519 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1523 TYPE_UNSIGNED (type) = TYPE_UNSIGNED (TREE_TYPE (type));
1525 = mode_for_size (2 * TYPE_PRECISION (TREE_TYPE (type)),
1526 (TREE_CODE (TREE_TYPE (type)) == REAL_TYPE
1527 ? MODE_COMPLEX_FLOAT : MODE_COMPLEX_INT),
1529 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1530 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1535 int nunits = TYPE_VECTOR_SUBPARTS (type);
1536 tree nunits_tree = build_int_cst (NULL_TREE, nunits);
1537 tree innertype = TREE_TYPE (type);
1539 if (nunits & (nunits - 1))
1542 /* Find an appropriate mode for the vector type. */
1543 if (TYPE_MODE (type) == VOIDmode)
1545 enum machine_mode innermode = TYPE_MODE (innertype);
1546 enum machine_mode mode;
1548 /* First, look for a supported vector type. */
1549 if (GET_MODE_CLASS (innermode) == MODE_FLOAT)
1550 mode = MIN_MODE_VECTOR_FLOAT;
1552 mode = MIN_MODE_VECTOR_INT;
1554 for (; mode != VOIDmode ; mode = GET_MODE_WIDER_MODE (mode))
1555 if (GET_MODE_NUNITS (mode) == nunits
1556 && GET_MODE_INNER (mode) == innermode
1557 && targetm.vector_mode_supported_p (mode))
1560 /* For integers, try mapping it to a same-sized scalar mode. */
1561 if (mode == VOIDmode
1562 && GET_MODE_CLASS (innermode) == MODE_INT)
1563 mode = mode_for_size (nunits * GET_MODE_BITSIZE (innermode),
1566 if (mode == VOIDmode || !have_regs_of_mode[mode])
1567 TYPE_MODE (type) = BLKmode;
1569 TYPE_MODE (type) = mode;
1572 TYPE_UNSIGNED (type) = TYPE_UNSIGNED (TREE_TYPE (type));
1573 TYPE_SIZE_UNIT (type) = int_const_binop (MULT_EXPR,
1574 TYPE_SIZE_UNIT (innertype),
1576 TYPE_SIZE (type) = int_const_binop (MULT_EXPR, TYPE_SIZE (innertype),
1582 /* This is an incomplete type and so doesn't have a size. */
1583 TYPE_ALIGN (type) = 1;
1584 TYPE_USER_ALIGN (type) = 0;
1585 TYPE_MODE (type) = VOIDmode;
1589 TYPE_SIZE (type) = bitsize_int (POINTER_SIZE);
1590 TYPE_SIZE_UNIT (type) = size_int (POINTER_SIZE / BITS_PER_UNIT);
1591 /* A pointer might be MODE_PARTIAL_INT,
1592 but ptrdiff_t must be integral. */
1593 TYPE_MODE (type) = mode_for_size (POINTER_SIZE, MODE_INT, 0);
1598 /* It's hard to see what the mode and size of a function ought to
1599 be, but we do know the alignment is FUNCTION_BOUNDARY, so
1600 make it consistent with that. */
1601 TYPE_MODE (type) = mode_for_size (FUNCTION_BOUNDARY, MODE_INT, 0);
1602 TYPE_SIZE (type) = bitsize_int (FUNCTION_BOUNDARY);
1603 TYPE_SIZE_UNIT (type) = size_int (FUNCTION_BOUNDARY / BITS_PER_UNIT);
1607 case REFERENCE_TYPE:
1610 enum machine_mode mode = ((TREE_CODE (type) == REFERENCE_TYPE
1611 && reference_types_internal)
1612 ? Pmode : TYPE_MODE (type));
1614 int nbits = GET_MODE_BITSIZE (mode);
1616 TYPE_SIZE (type) = bitsize_int (nbits);
1617 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (mode));
1618 TYPE_UNSIGNED (type) = 1;
1619 TYPE_PRECISION (type) = nbits;
1625 tree index = TYPE_DOMAIN (type);
1626 tree element = TREE_TYPE (type);
1628 build_pointer_type (element);
1630 /* We need to know both bounds in order to compute the size. */
1631 if (index && TYPE_MAX_VALUE (index) && TYPE_MIN_VALUE (index)
1632 && TYPE_SIZE (element))
1634 tree ub = TYPE_MAX_VALUE (index);
1635 tree lb = TYPE_MIN_VALUE (index);
1639 /* The initial subtraction should happen in the original type so
1640 that (possible) negative values are handled appropriately. */
1641 length = size_binop (PLUS_EXPR, size_one_node,
1643 fold (build2 (MINUS_EXPR,
1647 /* Special handling for arrays of bits (for Chill). */
1648 element_size = TYPE_SIZE (element);
1649 if (TYPE_PACKED (type) && INTEGRAL_TYPE_P (element)
1650 && (integer_zerop (TYPE_MAX_VALUE (element))
1651 || integer_onep (TYPE_MAX_VALUE (element)))
1652 && host_integerp (TYPE_MIN_VALUE (element), 1))
1654 HOST_WIDE_INT maxvalue
1655 = tree_low_cst (TYPE_MAX_VALUE (element), 1);
1656 HOST_WIDE_INT minvalue
1657 = tree_low_cst (TYPE_MIN_VALUE (element), 1);
1659 if (maxvalue - minvalue == 1
1660 && (maxvalue == 1 || maxvalue == 0))
1661 element_size = integer_one_node;
1664 /* If neither bound is a constant and sizetype is signed, make
1665 sure the size is never negative. We should really do this
1666 if *either* bound is non-constant, but this is the best
1667 compromise between C and Ada. */
1668 if (!TYPE_UNSIGNED (sizetype)
1669 && TREE_CODE (TYPE_MIN_VALUE (index)) != INTEGER_CST
1670 && TREE_CODE (TYPE_MAX_VALUE (index)) != INTEGER_CST)
1671 length = size_binop (MAX_EXPR, length, size_zero_node);
1673 TYPE_SIZE (type) = size_binop (MULT_EXPR, element_size,
1674 convert (bitsizetype, length));
1676 /* If we know the size of the element, calculate the total
1677 size directly, rather than do some division thing below.
1678 This optimization helps Fortran assumed-size arrays
1679 (where the size of the array is determined at runtime)
1681 Note that we can't do this in the case where the size of
1682 the elements is one bit since TYPE_SIZE_UNIT cannot be
1683 set correctly in that case. */
1684 if (TYPE_SIZE_UNIT (element) != 0 && ! integer_onep (element_size))
1685 TYPE_SIZE_UNIT (type)
1686 = size_binop (MULT_EXPR, TYPE_SIZE_UNIT (element), length);
1689 /* Now round the alignment and size,
1690 using machine-dependent criteria if any. */
1692 #ifdef ROUND_TYPE_ALIGN
1694 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (element), BITS_PER_UNIT);
1696 TYPE_ALIGN (type) = MAX (TYPE_ALIGN (element), BITS_PER_UNIT);
1698 TYPE_USER_ALIGN (type) = TYPE_USER_ALIGN (element);
1699 TYPE_MODE (type) = BLKmode;
1700 if (TYPE_SIZE (type) != 0
1701 #ifdef MEMBER_TYPE_FORCES_BLK
1702 && ! MEMBER_TYPE_FORCES_BLK (type, VOIDmode)
1704 /* BLKmode elements force BLKmode aggregate;
1705 else extract/store fields may lose. */
1706 && (TYPE_MODE (TREE_TYPE (type)) != BLKmode
1707 || TYPE_NO_FORCE_BLK (TREE_TYPE (type))))
1709 /* One-element arrays get the component type's mode. */
1710 if (simple_cst_equal (TYPE_SIZE (type),
1711 TYPE_SIZE (TREE_TYPE (type))))
1712 TYPE_MODE (type) = TYPE_MODE (TREE_TYPE (type));
1715 = mode_for_size_tree (TYPE_SIZE (type), MODE_INT, 1);
1717 if (TYPE_MODE (type) != BLKmode
1718 && STRICT_ALIGNMENT && TYPE_ALIGN (type) < BIGGEST_ALIGNMENT
1719 && TYPE_ALIGN (type) < GET_MODE_ALIGNMENT (TYPE_MODE (type))
1720 && TYPE_MODE (type) != BLKmode)
1722 TYPE_NO_FORCE_BLK (type) = 1;
1723 TYPE_MODE (type) = BLKmode;
1731 case QUAL_UNION_TYPE:
1734 record_layout_info rli;
1736 /* Initialize the layout information. */
1737 rli = start_record_layout (type);
1739 /* If this is a QUAL_UNION_TYPE, we want to process the fields
1740 in the reverse order in building the COND_EXPR that denotes
1741 its size. We reverse them again later. */
1742 if (TREE_CODE (type) == QUAL_UNION_TYPE)
1743 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
1745 /* Place all the fields. */
1746 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1747 place_field (rli, field);
1749 if (TREE_CODE (type) == QUAL_UNION_TYPE)
1750 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
1752 if (lang_adjust_rli)
1753 (*lang_adjust_rli) (rli);
1755 /* Finish laying out the record. */
1756 finish_record_layout (rli, /*free_p=*/true);
1760 case SET_TYPE: /* Used by Chill and Pascal. */
1761 if (TREE_CODE (TYPE_MAX_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST
1762 || TREE_CODE (TYPE_MIN_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST)
1766 #ifndef SET_WORD_SIZE
1767 #define SET_WORD_SIZE BITS_PER_WORD
1769 unsigned int alignment
1770 = set_alignment ? set_alignment : SET_WORD_SIZE;
1771 HOST_WIDE_INT size_in_bits
1772 = (tree_low_cst (TYPE_MAX_VALUE (TYPE_DOMAIN (type)), 0)
1773 - tree_low_cst (TYPE_MIN_VALUE (TYPE_DOMAIN (type)), 0) + 1);
1774 HOST_WIDE_INT rounded_size
1775 = ((size_in_bits + alignment - 1) / alignment) * alignment;
1777 if (rounded_size > (int) alignment)
1778 TYPE_MODE (type) = BLKmode;
1780 TYPE_MODE (type) = mode_for_size (alignment, MODE_INT, 1);
1782 TYPE_SIZE (type) = bitsize_int (rounded_size);
1783 TYPE_SIZE_UNIT (type) = size_int (rounded_size / BITS_PER_UNIT);
1784 TYPE_ALIGN (type) = alignment;
1785 TYPE_USER_ALIGN (type) = 0;
1786 TYPE_PRECISION (type) = size_in_bits;
1791 /* The size may vary in different languages, so the language front end
1792 should fill in the size. */
1793 TYPE_ALIGN (type) = BIGGEST_ALIGNMENT;
1794 TYPE_USER_ALIGN (type) = 0;
1795 TYPE_MODE (type) = BLKmode;
1802 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
1803 records and unions, finish_record_layout already called this
1805 if (TREE_CODE (type) != RECORD_TYPE
1806 && TREE_CODE (type) != UNION_TYPE
1807 && TREE_CODE (type) != QUAL_UNION_TYPE)
1808 finalize_type_size (type);
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 (bool signed_p)
1851 tree t = make_node (INTEGER_TYPE);
1853 TYPE_MODE (t) = SImode;
1854 TYPE_ALIGN (t) = GET_MODE_ALIGNMENT (SImode);
1855 TYPE_USER_ALIGN (t) = 0;
1856 TYPE_IS_SIZETYPE (t) = 1;
1857 TYPE_UNSIGNED (t) = !signed_p;
1858 TYPE_SIZE (t) = build_int_cst (t, GET_MODE_BITSIZE (SImode));
1859 TYPE_SIZE_UNIT (t) = build_int_cst (t, GET_MODE_SIZE (SImode));
1860 TYPE_PRECISION (t) = GET_MODE_BITSIZE (SImode);
1861 TYPE_MIN_VALUE (t) = build_int_cst (t, 0);
1863 /* 1000 avoids problems with possible overflow and is certainly
1864 larger than any size value we'd want to be storing. */
1865 TYPE_MAX_VALUE (t) = build_int_cst (t, 1000);
1868 bitsizetype = build_distinct_type_copy (t);
1871 /* Make sizetype a version of TYPE, and initialize *sizetype
1872 accordingly. We do this by overwriting the stub sizetype and
1873 bitsizetype nodes created by initialize_sizetypes. This makes sure
1874 that (a) anything stubby about them no longer exists, (b) any
1875 INTEGER_CSTs created with such a type, remain valid. */
1878 set_sizetype (tree type)
1880 int oprecision = TYPE_PRECISION (type);
1881 /* The *bitsizetype types use a precision that avoids overflows when
1882 calculating signed sizes / offsets in bits. However, when
1883 cross-compiling from a 32 bit to a 64 bit host, we are limited to 64 bit
1885 int precision = MIN (oprecision + BITS_PER_UNIT_LOG + 1,
1886 2 * HOST_BITS_PER_WIDE_INT);
1889 if (TYPE_UNSIGNED (type) != TYPE_UNSIGNED (sizetype))
1892 t = build_distinct_type_copy (type);
1893 /* We do want to use sizetype's cache, as we will be replacing that
1895 TYPE_CACHED_VALUES (t) = TYPE_CACHED_VALUES (sizetype);
1896 TYPE_CACHED_VALUES_P (t) = TYPE_CACHED_VALUES_P (sizetype);
1897 TREE_TYPE (TYPE_CACHED_VALUES (t)) = type;
1898 TYPE_UID (t) = TYPE_UID (sizetype);
1899 TYPE_IS_SIZETYPE (t) = 1;
1901 /* Replace our original stub sizetype. */
1902 memcpy (sizetype, t, tree_size (sizetype));
1903 TYPE_MAIN_VARIANT (sizetype) = sizetype;
1905 t = make_node (INTEGER_TYPE);
1906 TYPE_NAME (t) = get_identifier ("bit_size_type");
1907 /* We do want to use bitsizetype's cache, as we will be replacing that
1909 TYPE_CACHED_VALUES (t) = TYPE_CACHED_VALUES (bitsizetype);
1910 TYPE_CACHED_VALUES_P (t) = TYPE_CACHED_VALUES_P (bitsizetype);
1911 TYPE_PRECISION (t) = precision;
1912 TYPE_UID (t) = TYPE_UID (bitsizetype);
1913 TYPE_IS_SIZETYPE (t) = 1;
1914 /* Replace our original stub bitsizetype. */
1915 memcpy (bitsizetype, t, tree_size (bitsizetype));
1917 if (TYPE_UNSIGNED (type))
1919 fixup_unsigned_type (bitsizetype);
1920 ssizetype = build_distinct_type_copy (make_signed_type (oprecision));
1921 TYPE_IS_SIZETYPE (ssizetype) = 1;
1922 sbitsizetype = build_distinct_type_copy (make_signed_type (precision));
1923 TYPE_IS_SIZETYPE (sbitsizetype) = 1;
1927 fixup_signed_type (bitsizetype);
1928 ssizetype = sizetype;
1929 sbitsizetype = bitsizetype;
1933 /* TYPE is an integral type, i.e., an INTEGRAL_TYPE, ENUMERAL_TYPE,
1934 BOOLEAN_TYPE, or CHAR_TYPE. Set TYPE_MIN_VALUE and TYPE_MAX_VALUE
1935 for TYPE, based on the PRECISION and whether or not the TYPE
1936 IS_UNSIGNED. PRECISION need not correspond to a width supported
1937 natively by the hardware; for example, on a machine with 8-bit,
1938 16-bit, and 32-bit register modes, PRECISION might be 7, 23, or
1942 set_min_and_max_values_for_integral_type (tree type,
1951 min_value = build_int_cst (type, 0);
1953 = build_int_cst_wide (type, precision - HOST_BITS_PER_WIDE_INT >= 0
1955 : ((HOST_WIDE_INT) 1 << precision) - 1,
1956 precision - HOST_BITS_PER_WIDE_INT > 0
1957 ? ((unsigned HOST_WIDE_INT) ~0
1958 >> (HOST_BITS_PER_WIDE_INT
1959 - (precision - HOST_BITS_PER_WIDE_INT)))
1965 = build_int_cst_wide (type,
1966 (precision - HOST_BITS_PER_WIDE_INT > 0
1968 : (HOST_WIDE_INT) (-1) << (precision - 1)),
1969 (((HOST_WIDE_INT) (-1)
1970 << (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1971 ? precision - HOST_BITS_PER_WIDE_INT - 1
1974 = build_int_cst_wide (type,
1975 (precision - HOST_BITS_PER_WIDE_INT > 0
1977 : ((HOST_WIDE_INT) 1 << (precision - 1)) - 1),
1978 (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1979 ? (((HOST_WIDE_INT) 1
1980 << (precision - HOST_BITS_PER_WIDE_INT - 1))) - 1
1984 TYPE_MIN_VALUE (type) = min_value;
1985 TYPE_MAX_VALUE (type) = max_value;
1988 /* Set the extreme values of TYPE based on its precision in bits,
1989 then lay it out. Used when make_signed_type won't do
1990 because the tree code is not INTEGER_TYPE.
1991 E.g. for Pascal, when the -fsigned-char option is given. */
1994 fixup_signed_type (tree type)
1996 int precision = TYPE_PRECISION (type);
1998 /* We can not represent properly constants greater then
1999 2 * HOST_BITS_PER_WIDE_INT, still we need the types
2000 as they are used by i386 vector extensions and friends. */
2001 if (precision > HOST_BITS_PER_WIDE_INT * 2)
2002 precision = HOST_BITS_PER_WIDE_INT * 2;
2004 set_min_and_max_values_for_integral_type (type, precision,
2005 /*is_unsigned=*/false);
2007 /* Lay out the type: set its alignment, size, etc. */
2011 /* Set the extreme values of TYPE based on its precision in bits,
2012 then lay it out. This is used both in `make_unsigned_type'
2013 and for enumeral types. */
2016 fixup_unsigned_type (tree type)
2018 int precision = TYPE_PRECISION (type);
2020 /* We can not represent properly constants greater then
2021 2 * HOST_BITS_PER_WIDE_INT, still we need the types
2022 as they are used by i386 vector extensions and friends. */
2023 if (precision > HOST_BITS_PER_WIDE_INT * 2)
2024 precision = HOST_BITS_PER_WIDE_INT * 2;
2026 TYPE_UNSIGNED (type) = 1;
2028 set_min_and_max_values_for_integral_type (type, precision,
2029 /*is_unsigned=*/true);
2031 /* Lay out the type: set its alignment, size, etc. */
2035 /* Find the best machine mode to use when referencing a bit field of length
2036 BITSIZE bits starting at BITPOS.
2038 The underlying object is known to be aligned to a boundary of ALIGN bits.
2039 If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
2040 larger than LARGEST_MODE (usually SImode).
2042 If no mode meets all these conditions, we return VOIDmode. Otherwise, if
2043 VOLATILEP is true or SLOW_BYTE_ACCESS is false, we return the smallest
2044 mode meeting these conditions.
2046 Otherwise (VOLATILEP is false and SLOW_BYTE_ACCESS is true), we return
2047 the largest mode (but a mode no wider than UNITS_PER_WORD) that meets
2048 all the conditions. */
2051 get_best_mode (int bitsize, int bitpos, unsigned int align,
2052 enum machine_mode largest_mode, int volatilep)
2054 enum machine_mode mode;
2055 unsigned int unit = 0;
2057 /* Find the narrowest integer mode that contains the bit field. */
2058 for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
2059 mode = GET_MODE_WIDER_MODE (mode))
2061 unit = GET_MODE_BITSIZE (mode);
2062 if ((bitpos % unit) + bitsize <= unit)
2066 if (mode == VOIDmode
2067 /* It is tempting to omit the following line
2068 if STRICT_ALIGNMENT is true.
2069 But that is incorrect, since if the bitfield uses part of 3 bytes
2070 and we use a 4-byte mode, we could get a spurious segv
2071 if the extra 4th byte is past the end of memory.
2072 (Though at least one Unix compiler ignores this problem:
2073 that on the Sequent 386 machine. */
2074 || MIN (unit, BIGGEST_ALIGNMENT) > align
2075 || (largest_mode != VOIDmode && unit > GET_MODE_BITSIZE (largest_mode)))
2078 if (SLOW_BYTE_ACCESS && ! volatilep)
2080 enum machine_mode wide_mode = VOIDmode, tmode;
2082 for (tmode = GET_CLASS_NARROWEST_MODE (MODE_INT); tmode != VOIDmode;
2083 tmode = GET_MODE_WIDER_MODE (tmode))
2085 unit = GET_MODE_BITSIZE (tmode);
2086 if (bitpos / unit == (bitpos + bitsize - 1) / unit
2087 && unit <= BITS_PER_WORD
2088 && unit <= MIN (align, BIGGEST_ALIGNMENT)
2089 && (largest_mode == VOIDmode
2090 || unit <= GET_MODE_BITSIZE (largest_mode)))
2094 if (wide_mode != VOIDmode)
2101 /* Gets minimal and maximal values for MODE (signed or unsigned depending on
2102 SIGN). The returned constants are made to be usable in TARGET_MODE. */
2105 get_mode_bounds (enum machine_mode mode, int sign,
2106 enum machine_mode target_mode,
2107 rtx *mmin, rtx *mmax)
2109 unsigned size = GET_MODE_BITSIZE (mode);
2110 unsigned HOST_WIDE_INT min_val, max_val;
2112 if (size > HOST_BITS_PER_WIDE_INT)
2117 min_val = -((unsigned HOST_WIDE_INT) 1 << (size - 1));
2118 max_val = ((unsigned HOST_WIDE_INT) 1 << (size - 1)) - 1;
2123 max_val = ((unsigned HOST_WIDE_INT) 1 << (size - 1) << 1) - 1;
2126 *mmin = GEN_INT (trunc_int_for_mode (min_val, target_mode));
2127 *mmax = GEN_INT (trunc_int_for_mode (max_val, target_mode));
2130 #include "gt-stor-layout.h"