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 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
34 #include "langhooks.h"
36 /* Set to one when set_sizetype has been called. */
37 static int sizetype_set;
39 /* List of types created before set_sizetype has been called. We do not
40 make this a GGC root since we want these nodes to be reclaimed. */
41 static tree early_type_list;
43 /* Data type for the expressions representing sizes of data types.
44 It is the first integer type laid out. */
45 tree sizetype_tab[(int) TYPE_KIND_LAST];
47 /* If nonzero, this is an upper limit on alignment of structure fields.
48 The value is measured in bits. */
49 unsigned int maximum_field_alignment;
51 /* If non-zero, the alignment of a bitstring or (power-)set value, in bits.
52 May be overridden by front-ends. */
53 unsigned int set_alignment = 0;
55 /* Nonzero if all REFERENCE_TYPEs are internal and hence should be
56 allocated in Pmode, not ptr_mode. Set only by internal_reference_types
57 called only by a front end. */
58 static int reference_types_internal = 0;
60 static void finalize_record_size PARAMS ((record_layout_info));
61 static void finalize_type_size PARAMS ((tree));
62 static void place_union_field PARAMS ((record_layout_info, tree));
63 extern void debug_rli PARAMS ((record_layout_info));
65 /* SAVE_EXPRs for sizes of types and decls, waiting to be expanded. */
67 static tree pending_sizes;
69 /* Nonzero means cannot safely call expand_expr now,
70 so put variable sizes onto `pending_sizes' instead. */
72 int immediate_size_expand;
74 /* Show that REFERENCE_TYPES are internal and should be Pmode. Called only
78 internal_reference_types ()
80 reference_types_internal = 1;
83 /* Get a list of all the objects put on the pending sizes list. */
88 tree chain = pending_sizes;
91 /* Put each SAVE_EXPR into the current function. */
92 for (t = chain; t; t = TREE_CHAIN (t))
93 SAVE_EXPR_CONTEXT (TREE_VALUE (t)) = current_function_decl;
99 /* Return non-zero if EXPR is present on the pending sizes list. */
102 is_pending_size (expr)
107 for (t = pending_sizes; t; t = TREE_CHAIN (t))
108 if (TREE_VALUE (t) == expr)
113 /* Add EXPR to the pending sizes list. */
116 put_pending_size (expr)
119 /* Strip any simple arithmetic from EXPR to see if it has an underlying
121 while (TREE_CODE_CLASS (TREE_CODE (expr)) == '1'
122 || (TREE_CODE_CLASS (TREE_CODE (expr)) == '2'
123 && TREE_CONSTANT (TREE_OPERAND (expr, 1))))
124 expr = TREE_OPERAND (expr, 0);
126 if (TREE_CODE (expr) == SAVE_EXPR)
127 pending_sizes = tree_cons (NULL_TREE, expr, pending_sizes);
130 /* Put a chain of objects into the pending sizes list, which must be
134 put_pending_sizes (chain)
140 pending_sizes = chain;
143 /* Given a size SIZE that may not be a constant, return a SAVE_EXPR
144 to serve as the actual size-expression for a type or decl. */
150 /* If the language-processor is to take responsibility for variable-sized
151 items (e.g., languages which have elaboration procedures like Ada),
152 just return SIZE unchanged. Likewise for self-referential sizes and
154 if (TREE_CONSTANT (size)
155 || (*lang_hooks.decls.global_bindings_p) () < 0
156 || contains_placeholder_p (size))
159 size = save_expr (size);
161 /* If an array with a variable number of elements is declared, and
162 the elements require destruction, we will emit a cleanup for the
163 array. That cleanup is run both on normal exit from the block
164 and in the exception-handler for the block. Normally, when code
165 is used in both ordinary code and in an exception handler it is
166 `unsaved', i.e., all SAVE_EXPRs are recalculated. However, we do
167 not wish to do that here; the array-size is the same in both
169 if (TREE_CODE (size) == SAVE_EXPR)
170 SAVE_EXPR_PERSISTENT_P (size) = 1;
172 if ((*lang_hooks.decls.global_bindings_p) ())
174 if (TREE_CONSTANT (size))
175 error ("type size can't be explicitly evaluated");
177 error ("variable-size type declared outside of any function");
179 return size_one_node;
182 if (immediate_size_expand)
183 /* NULL_RTX is not defined; neither is the rtx type.
184 Also, we would like to pass const0_rtx here, but don't have it. */
185 expand_expr (size, expand_expr (integer_zero_node, NULL_RTX, VOIDmode, 0),
187 else if (cfun != 0 && cfun->x_dont_save_pending_sizes_p)
188 /* The front-end doesn't want us to keep a list of the expressions
189 that determine sizes for variable size objects. */
192 put_pending_size (size);
197 #ifndef MAX_FIXED_MODE_SIZE
198 #define MAX_FIXED_MODE_SIZE GET_MODE_BITSIZE (DImode)
201 /* Return the machine mode to use for a nonscalar of SIZE bits.
202 The mode must be in class CLASS, and have exactly that many bits.
203 If LIMIT is nonzero, modes of wider than MAX_FIXED_MODE_SIZE will not
207 mode_for_size (size, class, limit)
209 enum mode_class class;
212 enum machine_mode mode;
214 if (limit && size > MAX_FIXED_MODE_SIZE)
217 /* Get the first mode which has this size, in the specified class. */
218 for (mode = GET_CLASS_NARROWEST_MODE (class); mode != VOIDmode;
219 mode = GET_MODE_WIDER_MODE (mode))
220 if (GET_MODE_BITSIZE (mode) == size)
226 /* Similar, except passed a tree node. */
229 mode_for_size_tree (size, class, limit)
231 enum mode_class class;
234 if (TREE_CODE (size) != INTEGER_CST
235 /* What we really want to say here is that the size can fit in a
236 host integer, but we know there's no way we'd find a mode for
237 this many bits, so there's no point in doing the precise test. */
238 || compare_tree_int (size, 1000) > 0)
241 return mode_for_size (TREE_INT_CST_LOW (size), class, limit);
244 /* Similar, but never return BLKmode; return the narrowest mode that
245 contains at least the requested number of bits. */
248 smallest_mode_for_size (size, class)
250 enum mode_class class;
252 enum machine_mode mode;
254 /* Get the first mode which has at least this size, in the
256 for (mode = GET_CLASS_NARROWEST_MODE (class); mode != VOIDmode;
257 mode = GET_MODE_WIDER_MODE (mode))
258 if (GET_MODE_BITSIZE (mode) >= size)
264 /* Find an integer mode of the exact same size, or BLKmode on failure. */
267 int_mode_for_mode (mode)
268 enum machine_mode mode;
270 switch (GET_MODE_CLASS (mode))
273 case MODE_PARTIAL_INT:
276 case MODE_COMPLEX_INT:
277 case MODE_COMPLEX_FLOAT:
279 case MODE_VECTOR_INT:
280 case MODE_VECTOR_FLOAT:
281 mode = mode_for_size (GET_MODE_BITSIZE (mode), MODE_INT, 0);
288 /* ... fall through ... */
298 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
299 This can only be applied to objects of a sizetype. */
302 round_up (value, divisor)
306 tree arg = size_int_type (divisor, TREE_TYPE (value));
308 return size_binop (MULT_EXPR, size_binop (CEIL_DIV_EXPR, value, arg), arg);
311 /* Likewise, but round down. */
314 round_down (value, divisor)
318 tree arg = size_int_type (divisor, TREE_TYPE (value));
320 return size_binop (MULT_EXPR, size_binop (FLOOR_DIV_EXPR, value, arg), arg);
323 /* Set the size, mode and alignment of a ..._DECL node.
324 TYPE_DECL does need this for C++.
325 Note that LABEL_DECL and CONST_DECL nodes do not need this,
326 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
327 Don't call layout_decl for them.
329 KNOWN_ALIGN is the amount of alignment we can assume this
330 decl has with no special effort. It is relevant only for FIELD_DECLs
331 and depends on the previous fields.
332 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
333 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
334 the record will be aligned to suit. */
337 layout_decl (decl, known_align)
339 unsigned int known_align;
341 tree type = TREE_TYPE (decl);
342 enum tree_code code = TREE_CODE (decl);
344 if (code == CONST_DECL)
346 else if (code != VAR_DECL && code != PARM_DECL && code != RESULT_DECL
347 && code != TYPE_DECL && code != FIELD_DECL)
350 if (type == error_mark_node)
351 type = void_type_node;
353 /* Usually the size and mode come from the data type without change,
354 however, the front-end may set the explicit width of the field, so its
355 size may not be the same as the size of its type. This happens with
356 bitfields, of course (an `int' bitfield may be only 2 bits, say), but it
357 also happens with other fields. For example, the C++ front-end creates
358 zero-sized fields corresponding to empty base classes, and depends on
359 layout_type setting DECL_FIELD_BITPOS correctly for the field. Set the
360 size in bytes from the size in bits. If we have already set the mode,
361 don't set it again since we can be called twice for FIELD_DECLs. */
363 TREE_UNSIGNED (decl) = TREE_UNSIGNED (type);
364 if (DECL_MODE (decl) == VOIDmode)
365 DECL_MODE (decl) = TYPE_MODE (type);
367 if (DECL_SIZE (decl) == 0)
369 DECL_SIZE (decl) = TYPE_SIZE (type);
370 DECL_SIZE_UNIT (decl) = TYPE_SIZE_UNIT (type);
373 DECL_SIZE_UNIT (decl)
374 = convert (sizetype, size_binop (CEIL_DIV_EXPR, DECL_SIZE (decl),
377 /* Force alignment required for the data type.
378 But if the decl itself wants greater alignment, don't override that.
379 Likewise, if the decl is packed, don't override it. */
380 if (! (code == FIELD_DECL && DECL_BIT_FIELD (decl))
381 && (DECL_ALIGN (decl) == 0
382 || (! (code == FIELD_DECL && DECL_PACKED (decl))
383 && TYPE_ALIGN (type) > DECL_ALIGN (decl))))
385 DECL_ALIGN (decl) = TYPE_ALIGN (type);
386 DECL_USER_ALIGN (decl) = 0;
389 /* For fields, set the bit field type and update the alignment. */
390 if (code == FIELD_DECL)
392 DECL_BIT_FIELD_TYPE (decl) = DECL_BIT_FIELD (decl) ? type : 0;
393 if (maximum_field_alignment != 0)
394 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), maximum_field_alignment);
396 /* If the field is of variable size, we can't misalign it since we
397 have no way to make a temporary to align the result. But this
398 isn't an issue if the decl is not addressable. Likewise if it
399 is of unknown size. */
400 else if (DECL_PACKED (decl)
401 && (DECL_NONADDRESSABLE_P (decl)
402 || DECL_SIZE_UNIT (decl) == 0
403 || TREE_CODE (DECL_SIZE_UNIT (decl)) == INTEGER_CST))
405 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), BITS_PER_UNIT);
406 DECL_USER_ALIGN (decl) = 0;
410 /* See if we can use an ordinary integer mode for a bit-field.
411 Conditions are: a fixed size that is correct for another mode
412 and occupying a complete byte or bytes on proper boundary. */
413 if (code == FIELD_DECL && DECL_BIT_FIELD (decl)
414 && TYPE_SIZE (type) != 0
415 && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
416 && GET_MODE_CLASS (TYPE_MODE (type)) == MODE_INT)
418 enum machine_mode xmode
419 = mode_for_size_tree (DECL_SIZE (decl), MODE_INT, 1);
421 if (xmode != BLKmode && known_align >= GET_MODE_ALIGNMENT (xmode))
423 DECL_ALIGN (decl) = MAX (GET_MODE_ALIGNMENT (xmode),
425 DECL_MODE (decl) = xmode;
426 DECL_BIT_FIELD (decl) = 0;
430 /* Turn off DECL_BIT_FIELD if we won't need it set. */
431 if (code == FIELD_DECL && DECL_BIT_FIELD (decl)
432 && TYPE_MODE (type) == BLKmode && DECL_MODE (decl) == BLKmode
433 && known_align >= TYPE_ALIGN (type)
434 && DECL_ALIGN (decl) >= TYPE_ALIGN (type)
435 && DECL_SIZE_UNIT (decl) != 0)
436 DECL_BIT_FIELD (decl) = 0;
438 /* Evaluate nonconstant size only once, either now or as soon as safe. */
439 if (DECL_SIZE (decl) != 0 && TREE_CODE (DECL_SIZE (decl)) != INTEGER_CST)
440 DECL_SIZE (decl) = variable_size (DECL_SIZE (decl));
441 if (DECL_SIZE_UNIT (decl) != 0
442 && TREE_CODE (DECL_SIZE_UNIT (decl)) != INTEGER_CST)
443 DECL_SIZE_UNIT (decl) = variable_size (DECL_SIZE_UNIT (decl));
445 /* If requested, warn about definitions of large data objects. */
447 && (code == VAR_DECL || code == PARM_DECL)
448 && ! DECL_EXTERNAL (decl))
450 tree size = DECL_SIZE_UNIT (decl);
452 if (size != 0 && TREE_CODE (size) == INTEGER_CST
453 && compare_tree_int (size, larger_than_size) > 0)
455 unsigned int size_as_int = TREE_INT_CST_LOW (size);
457 if (compare_tree_int (size, size_as_int) == 0)
458 warning_with_decl (decl, "size of `%s' is %d bytes", size_as_int);
460 warning_with_decl (decl, "size of `%s' is larger than %d bytes",
465 /* If there was already RTL for this DECL, as for a variable with an
466 incomplete type whose type is completed later, update the RTL. */
467 if (DECL_RTL_SET_P (decl))
468 make_decl_rtl (decl, NULL);
471 /* Hook for a front-end function that can modify the record layout as needed
472 immediately before it is finalized. */
474 void (*lang_adjust_rli) PARAMS ((record_layout_info)) = 0;
477 set_lang_adjust_rli (f)
478 void (*f) PARAMS ((record_layout_info));
483 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
484 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
485 is to be passed to all other layout functions for this record. It is the
486 responsibility of the caller to call `free' for the storage returned.
487 Note that garbage collection is not permitted until we finish laying
491 start_record_layout (t)
494 record_layout_info rli
495 = (record_layout_info) xmalloc (sizeof (struct record_layout_info_s));
499 /* If the type has a minimum specified alignment (via an attribute
500 declaration, for example) use it -- otherwise, start with a
501 one-byte alignment. */
502 rli->record_align = MAX (BITS_PER_UNIT, TYPE_ALIGN (t));
503 rli->unpacked_align = rli->unpadded_align = rli->record_align;
504 rli->offset_align = MAX (rli->record_align, BIGGEST_ALIGNMENT);
506 #ifdef STRUCTURE_SIZE_BOUNDARY
507 /* Packed structures don't need to have minimum size. */
508 if (! TYPE_PACKED (t))
509 rli->record_align = MAX (rli->record_align, STRUCTURE_SIZE_BOUNDARY);
512 rli->offset = size_zero_node;
513 rli->bitpos = bitsize_zero_node;
515 rli->pending_statics = 0;
516 rli->packed_maybe_necessary = 0;
521 /* These four routines perform computations that convert between
522 the offset/bitpos forms and byte and bit offsets. */
525 bit_from_pos (offset, bitpos)
528 return size_binop (PLUS_EXPR, bitpos,
529 size_binop (MULT_EXPR, convert (bitsizetype, offset),
534 byte_from_pos (offset, bitpos)
537 return size_binop (PLUS_EXPR, offset,
539 size_binop (TRUNC_DIV_EXPR, bitpos,
540 bitsize_unit_node)));
544 pos_from_byte (poffset, pbitpos, off_align, pos)
545 tree *poffset, *pbitpos;
546 unsigned int off_align;
550 = size_binop (MULT_EXPR,
552 size_binop (FLOOR_DIV_EXPR, pos,
553 bitsize_int (off_align
555 size_int (off_align / BITS_PER_UNIT));
556 *pbitpos = size_binop (MULT_EXPR,
557 size_binop (FLOOR_MOD_EXPR, pos,
558 bitsize_int (off_align / BITS_PER_UNIT)),
563 pos_from_bit (poffset, pbitpos, off_align, pos)
564 tree *poffset, *pbitpos;
565 unsigned int off_align;
568 *poffset = size_binop (MULT_EXPR,
570 size_binop (FLOOR_DIV_EXPR, pos,
571 bitsize_int (off_align))),
572 size_int (off_align / BITS_PER_UNIT));
573 *pbitpos = size_binop (FLOOR_MOD_EXPR, pos, bitsize_int (off_align));
576 /* Given a pointer to bit and byte offsets and an offset alignment,
577 normalize the offsets so they are within the alignment. */
580 normalize_offset (poffset, pbitpos, off_align)
581 tree *poffset, *pbitpos;
582 unsigned int off_align;
584 /* If the bit position is now larger than it should be, adjust it
586 if (compare_tree_int (*pbitpos, off_align) >= 0)
588 tree extra_aligns = size_binop (FLOOR_DIV_EXPR, *pbitpos,
589 bitsize_int (off_align));
592 = size_binop (PLUS_EXPR, *poffset,
593 size_binop (MULT_EXPR, convert (sizetype, extra_aligns),
594 size_int (off_align / BITS_PER_UNIT)));
597 = size_binop (FLOOR_MOD_EXPR, *pbitpos, bitsize_int (off_align));
601 /* Print debugging information about the information in RLI. */
605 record_layout_info rli;
607 print_node_brief (stderr, "type", rli->t, 0);
608 print_node_brief (stderr, "\noffset", rli->offset, 0);
609 print_node_brief (stderr, " bitpos", rli->bitpos, 0);
611 fprintf (stderr, "\naligns: rec = %u, unpack = %u, unpad = %u, off = %u\n",
612 rli->record_align, rli->unpacked_align, rli->unpadded_align,
614 if (rli->packed_maybe_necessary)
615 fprintf (stderr, "packed may be necessary\n");
617 if (rli->pending_statics)
619 fprintf (stderr, "pending statics:\n");
620 debug_tree (rli->pending_statics);
624 /* Given an RLI with a possibly-incremented BITPOS, adjust OFFSET and
625 BITPOS if necessary to keep BITPOS below OFFSET_ALIGN. */
629 record_layout_info rli;
631 normalize_offset (&rli->offset, &rli->bitpos, rli->offset_align);
634 /* Returns the size in bytes allocated so far. */
637 rli_size_unit_so_far (rli)
638 record_layout_info rli;
640 return byte_from_pos (rli->offset, rli->bitpos);
643 /* Returns the size in bits allocated so far. */
646 rli_size_so_far (rli)
647 record_layout_info rli;
649 return bit_from_pos (rli->offset, rli->bitpos);
652 /* Called from place_field to handle unions. */
655 place_union_field (rli, field)
656 record_layout_info rli;
659 unsigned int desired_align;
661 layout_decl (field, 0);
663 DECL_FIELD_OFFSET (field) = size_zero_node;
664 DECL_FIELD_BIT_OFFSET (field) = bitsize_zero_node;
665 SET_DECL_OFFSET_ALIGN (field, BIGGEST_ALIGNMENT);
667 desired_align = DECL_ALIGN (field);
669 #ifdef BIGGEST_FIELD_ALIGNMENT
670 /* Some targets (i.e. i386) limit union field alignment
671 to a lower boundary than alignment of variables unless
672 it was overridden by attribute aligned. */
673 if (! DECL_USER_ALIGN (field))
675 MIN (desired_align, (unsigned) BIGGEST_FIELD_ALIGNMENT);
678 #ifdef ADJUST_FIELD_ALIGN
679 desired_align = ADJUST_FIELD_ALIGN (field, desired_align);
682 TYPE_USER_ALIGN (rli->t) |= DECL_USER_ALIGN (field);
684 /* Union must be at least as aligned as any field requires. */
685 rli->record_align = MAX (rli->record_align, desired_align);
686 rli->unpadded_align = MAX (rli->unpadded_align, desired_align);
688 #ifdef PCC_BITFIELD_TYPE_MATTERS
689 /* On the m88000, a bit field of declare type `int' forces the
690 entire union to have `int' alignment. */
691 if (PCC_BITFIELD_TYPE_MATTERS && DECL_BIT_FIELD_TYPE (field))
693 rli->record_align = MAX (rli->record_align,
694 TYPE_ALIGN (TREE_TYPE (field)));
695 rli->unpadded_align = MAX (rli->unpadded_align,
696 TYPE_ALIGN (TREE_TYPE (field)));
700 /* We assume the union's size will be a multiple of a byte so we don't
701 bother with BITPOS. */
702 if (TREE_CODE (rli->t) == UNION_TYPE)
703 rli->offset = size_binop (MAX_EXPR, rli->offset, DECL_SIZE_UNIT (field));
704 else if (TREE_CODE (rli->t) == QUAL_UNION_TYPE)
705 rli->offset = fold (build (COND_EXPR, sizetype,
706 DECL_QUALIFIER (field),
707 DECL_SIZE_UNIT (field), rli->offset));
710 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
711 is a FIELD_DECL to be added after those fields already present in
712 T. (FIELD is not actually added to the TYPE_FIELDS list here;
713 callers that desire that behavior must manually perform that step.) */
716 place_field (rli, field)
717 record_layout_info rli;
720 /* The alignment required for FIELD. */
721 unsigned int desired_align;
722 /* The alignment FIELD would have if we just dropped it into the
723 record as it presently stands. */
724 unsigned int known_align;
725 unsigned int actual_align;
726 unsigned int user_align;
727 /* The type of this field. */
728 tree type = TREE_TYPE (field);
730 if (TREE_CODE (field) == ERROR_MARK || TREE_CODE (type) == ERROR_MARK)
733 /* If FIELD is static, then treat it like a separate variable, not
734 really like a structure field. If it is a FUNCTION_DECL, it's a
735 method. In both cases, all we do is lay out the decl, and we do
736 it *after* the record is laid out. */
737 if (TREE_CODE (field) == VAR_DECL)
739 rli->pending_statics = tree_cons (NULL_TREE, field,
740 rli->pending_statics);
744 /* Enumerators and enum types which are local to this class need not
745 be laid out. Likewise for initialized constant fields. */
746 else if (TREE_CODE (field) != FIELD_DECL)
749 /* Unions are laid out very differently than records, so split
750 that code off to another function. */
751 else if (TREE_CODE (rli->t) != RECORD_TYPE)
753 place_union_field (rli, field);
757 /* Work out the known alignment so far. Note that A & (-A) is the
758 value of the least-significant bit in A that is one. */
759 if (! integer_zerop (rli->bitpos))
760 known_align = (tree_low_cst (rli->bitpos, 1)
761 & - tree_low_cst (rli->bitpos, 1));
762 else if (integer_zerop (rli->offset))
763 known_align = BIGGEST_ALIGNMENT;
764 else if (host_integerp (rli->offset, 1))
765 known_align = (BITS_PER_UNIT
766 * (tree_low_cst (rli->offset, 1)
767 & - tree_low_cst (rli->offset, 1)));
769 known_align = rli->offset_align;
771 /* Lay out the field so we know what alignment it needs. For a
772 packed field, use the alignment as specified, disregarding what
773 the type would want. */
774 desired_align = DECL_ALIGN (field);
775 user_align = DECL_USER_ALIGN (field);
776 layout_decl (field, known_align);
777 if (! DECL_PACKED (field))
779 desired_align = DECL_ALIGN (field);
780 user_align = DECL_USER_ALIGN (field);
783 /* Some targets (i.e. i386, VMS) limit struct field alignment
784 to a lower boundary than alignment of variables unless
785 it was overridden by attribute aligned. */
786 #ifdef BIGGEST_FIELD_ALIGNMENT
789 = MIN (desired_align, (unsigned) BIGGEST_FIELD_ALIGNMENT);
792 #ifdef ADJUST_FIELD_ALIGN
793 desired_align = ADJUST_FIELD_ALIGN (field, desired_align);
796 /* Record must have at least as much alignment as any field.
797 Otherwise, the alignment of the field within the record is
799 if ((* targetm.ms_bitfield_layout_p) (rli->t)
800 && type != error_mark_node
801 && DECL_BIT_FIELD_TYPE (field)
802 && ! integer_zerop (TYPE_SIZE (type))
803 && integer_zerop (DECL_SIZE (field)))
806 && DECL_BIT_FIELD_TYPE (rli->prev_field)
807 && ! integer_zerop (DECL_SIZE (rli->prev_field)))
809 rli->record_align = MAX (rli->record_align, desired_align);
810 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
816 #ifdef PCC_BITFIELD_TYPE_MATTERS
817 if (PCC_BITFIELD_TYPE_MATTERS && type != error_mark_node
818 && ! (* targetm.ms_bitfield_layout_p) (rli->t)
819 && DECL_BIT_FIELD_TYPE (field)
820 && ! integer_zerop (TYPE_SIZE (type)))
822 /* For these machines, a zero-length field does not
823 affect the alignment of the structure as a whole.
824 It does, however, affect the alignment of the next field
825 within the structure. */
826 if (! integer_zerop (DECL_SIZE (field)))
827 rli->record_align = MAX (rli->record_align, desired_align);
828 else if (! DECL_PACKED (field))
829 desired_align = TYPE_ALIGN (type);
831 /* A named bit field of declared type `int'
832 forces the entire structure to have `int' alignment. */
833 if (DECL_NAME (field) != 0)
835 unsigned int type_align = TYPE_ALIGN (type);
837 if (maximum_field_alignment != 0)
838 type_align = MIN (type_align, maximum_field_alignment);
839 else if (DECL_PACKED (field))
840 type_align = MIN (type_align, BITS_PER_UNIT);
842 rli->record_align = MAX (rli->record_align, type_align);
843 rli->unpadded_align = MAX (rli->unpadded_align, DECL_ALIGN (field));
845 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
851 rli->record_align = MAX (rli->record_align, desired_align);
852 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
853 rli->unpadded_align = MAX (rli->unpadded_align, DECL_ALIGN (field));
856 if (warn_packed && DECL_PACKED (field))
858 if (known_align > TYPE_ALIGN (type))
860 if (TYPE_ALIGN (type) > desired_align)
862 if (STRICT_ALIGNMENT)
863 warning_with_decl (field, "packed attribute causes inefficient alignment for `%s'");
865 warning_with_decl (field, "packed attribute is unnecessary for `%s'");
869 rli->packed_maybe_necessary = 1;
872 /* Does this field automatically have alignment it needs by virtue
873 of the fields that precede it and the record's own alignment? */
874 if (known_align < desired_align)
876 /* No, we need to skip space before this field.
877 Bump the cumulative size to multiple of field alignment. */
880 warning_with_decl (field, "padding struct to align `%s'");
882 /* If the alignment is still within offset_align, just align
884 if (desired_align < rli->offset_align)
885 rli->bitpos = round_up (rli->bitpos, desired_align);
888 /* First adjust OFFSET by the partial bits, then align. */
890 = size_binop (PLUS_EXPR, rli->offset,
892 size_binop (CEIL_DIV_EXPR, rli->bitpos,
893 bitsize_unit_node)));
894 rli->bitpos = bitsize_zero_node;
896 rli->offset = round_up (rli->offset, desired_align / BITS_PER_UNIT);
899 if (! TREE_CONSTANT (rli->offset))
900 rli->offset_align = desired_align;
904 /* Handle compatibility with PCC. Note that if the record has any
905 variable-sized fields, we need not worry about compatibility. */
906 #ifdef PCC_BITFIELD_TYPE_MATTERS
907 if (PCC_BITFIELD_TYPE_MATTERS
908 && ! (* targetm.ms_bitfield_layout_p) (rli->t)
909 && TREE_CODE (field) == FIELD_DECL
910 && type != error_mark_node
911 && DECL_BIT_FIELD (field)
912 && ! DECL_PACKED (field)
913 && maximum_field_alignment == 0
914 && ! integer_zerop (DECL_SIZE (field))
915 && host_integerp (DECL_SIZE (field), 1)
916 && host_integerp (rli->offset, 1)
917 && host_integerp (TYPE_SIZE (type), 1))
919 unsigned int type_align = TYPE_ALIGN (type);
920 tree dsize = DECL_SIZE (field);
921 HOST_WIDE_INT field_size = tree_low_cst (dsize, 1);
922 HOST_WIDE_INT offset = tree_low_cst (rli->offset, 0);
923 HOST_WIDE_INT bit_offset = tree_low_cst (rli->bitpos, 0);
925 /* A bit field may not span more units of alignment of its type
926 than its type itself. Advance to next boundary if necessary. */
927 if ((((offset * BITS_PER_UNIT + bit_offset + field_size +
930 - (offset * BITS_PER_UNIT + bit_offset) / type_align)
931 > tree_low_cst (TYPE_SIZE (type), 1) / type_align)
932 rli->bitpos = round_up (rli->bitpos, type_align);
936 #ifdef BITFIELD_NBYTES_LIMITED
937 if (BITFIELD_NBYTES_LIMITED
938 && ! (* targetm.ms_bitfield_layout_p) (rli->t)
939 && TREE_CODE (field) == FIELD_DECL
940 && type != error_mark_node
941 && DECL_BIT_FIELD_TYPE (field)
942 && ! DECL_PACKED (field)
943 && ! integer_zerop (DECL_SIZE (field))
944 && host_integerp (DECL_SIZE (field), 1)
945 && host_integerp (rli->offset, 1)
946 && host_integerp (TYPE_SIZE (type), 1))
948 unsigned int type_align = TYPE_ALIGN (type);
949 tree dsize = DECL_SIZE (field);
950 HOST_WIDE_INT field_size = tree_low_cst (dsize, 1);
951 HOST_WIDE_INT offset = tree_low_cst (rli->offset, 0);
952 HOST_WIDE_INT bit_offset = tree_low_cst (rli->bitpos, 0);
954 if (maximum_field_alignment != 0)
955 type_align = MIN (type_align, maximum_field_alignment);
956 /* ??? This test is opposite the test in the containing if
957 statement, so this code is unreachable currently. */
958 else if (DECL_PACKED (field))
959 type_align = MIN (type_align, BITS_PER_UNIT);
961 /* A bit field may not span the unit of alignment of its type.
962 Advance to next boundary if necessary. */
963 /* ??? This code should match the code above for the
964 PCC_BITFIELD_TYPE_MATTERS case. */
965 if ((offset * BITS_PER_UNIT + bit_offset) / type_align
966 != ((offset * BITS_PER_UNIT + bit_offset + field_size - 1)
968 rli->bitpos = round_up (rli->bitpos, type_align);
972 /* See the docs for TARGET_MS_BITFIELD_LAYOUT_P for details. */
973 if ((* targetm.ms_bitfield_layout_p) (rli->t)
974 && TREE_CODE (field) == FIELD_DECL
975 && type != error_mark_node
976 && ! DECL_PACKED (field)
979 && host_integerp (DECL_SIZE (field), 1)
980 && DECL_SIZE (rli->prev_field)
981 && host_integerp (DECL_SIZE (rli->prev_field), 1)
982 && host_integerp (rli->offset, 1)
983 && host_integerp (TYPE_SIZE (type), 1)
984 && host_integerp (TYPE_SIZE (TREE_TYPE (rli->prev_field)), 1)
985 && ((DECL_BIT_FIELD_TYPE (rli->prev_field)
986 && ! integer_zerop (DECL_SIZE (rli->prev_field)))
987 || (DECL_BIT_FIELD_TYPE (field)
988 && ! integer_zerop (DECL_SIZE (field))))
989 && (! simple_cst_equal (TYPE_SIZE (type),
990 TYPE_SIZE (TREE_TYPE (rli->prev_field)))
991 /* If the previous field was a zero-sized bit-field, either
992 it was ignored, in which case we must ensure the proper
993 alignment of this field here, or it already forced the
994 alignment of this field, in which case forcing the
995 alignment again is harmless. So, do it in both cases. */
996 || (DECL_BIT_FIELD_TYPE (rli->prev_field)
997 && integer_zerop (DECL_SIZE (rli->prev_field)))))
999 unsigned int type_align = TYPE_ALIGN (type);
1002 && DECL_BIT_FIELD_TYPE (rli->prev_field)
1003 /* If the previous bit-field is zero-sized, we've already
1004 accounted for its alignment needs (or ignored it, if
1005 appropriate) while placing it. */
1006 && ! integer_zerop (DECL_SIZE (rli->prev_field)))
1007 type_align = MAX (type_align,
1008 TYPE_ALIGN (TREE_TYPE (rli->prev_field)));
1010 if (maximum_field_alignment != 0)
1011 type_align = MIN (type_align, maximum_field_alignment);
1013 rli->bitpos = round_up (rli->bitpos, type_align);
1016 /* Offset so far becomes the position of this field after normalizing. */
1017 normalize_rli (rli);
1018 DECL_FIELD_OFFSET (field) = rli->offset;
1019 DECL_FIELD_BIT_OFFSET (field) = rli->bitpos;
1020 SET_DECL_OFFSET_ALIGN (field, rli->offset_align);
1022 TYPE_USER_ALIGN (rli->t) |= user_align;
1024 /* If this field ended up more aligned than we thought it would be (we
1025 approximate this by seeing if its position changed), lay out the field
1026 again; perhaps we can use an integral mode for it now. */
1027 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field)))
1028 actual_align = (tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1)
1029 & - tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1));
1030 else if (integer_zerop (DECL_FIELD_OFFSET (field)))
1031 actual_align = BIGGEST_ALIGNMENT;
1032 else if (host_integerp (DECL_FIELD_OFFSET (field), 1))
1033 actual_align = (BITS_PER_UNIT
1034 * (tree_low_cst (DECL_FIELD_OFFSET (field), 1)
1035 & - tree_low_cst (DECL_FIELD_OFFSET (field), 1)));
1037 actual_align = DECL_OFFSET_ALIGN (field);
1039 if (known_align != actual_align)
1040 layout_decl (field, actual_align);
1042 rli->prev_field = field;
1044 /* Now add size of this field to the size of the record. If the size is
1045 not constant, treat the field as being a multiple of bytes and just
1046 adjust the offset, resetting the bit position. Otherwise, apportion the
1047 size amongst the bit position and offset. First handle the case of an
1048 unspecified size, which can happen when we have an invalid nested struct
1049 definition, such as struct j { struct j { int i; } }. The error message
1050 is printed in finish_struct. */
1051 if (DECL_SIZE (field) == 0)
1053 else if (TREE_CODE (DECL_SIZE_UNIT (field)) != INTEGER_CST
1054 || TREE_CONSTANT_OVERFLOW (DECL_SIZE_UNIT (field)))
1057 = size_binop (PLUS_EXPR, rli->offset,
1059 size_binop (CEIL_DIV_EXPR, rli->bitpos,
1060 bitsize_unit_node)));
1062 = size_binop (PLUS_EXPR, rli->offset, DECL_SIZE_UNIT (field));
1063 rli->bitpos = bitsize_zero_node;
1064 rli->offset_align = MIN (rli->offset_align, DECL_ALIGN (field));
1068 rli->bitpos = size_binop (PLUS_EXPR, rli->bitpos, DECL_SIZE (field));
1069 normalize_rli (rli);
1073 /* Assuming that all the fields have been laid out, this function uses
1074 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
1075 inidicated by RLI. */
1078 finalize_record_size (rli)
1079 record_layout_info rli;
1081 tree unpadded_size, unpadded_size_unit;
1083 /* Now we want just byte and bit offsets, so set the offset alignment
1084 to be a byte and then normalize. */
1085 rli->offset_align = BITS_PER_UNIT;
1086 normalize_rli (rli);
1088 /* Determine the desired alignment. */
1089 #ifdef ROUND_TYPE_ALIGN
1090 TYPE_ALIGN (rli->t) = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t),
1093 TYPE_ALIGN (rli->t) = MAX (TYPE_ALIGN (rli->t), rli->record_align);
1096 /* Compute the size so far. Be sure to allow for extra bits in the
1097 size in bytes. We have guaranteed above that it will be no more
1098 than a single byte. */
1099 unpadded_size = rli_size_so_far (rli);
1100 unpadded_size_unit = rli_size_unit_so_far (rli);
1101 if (! integer_zerop (rli->bitpos))
1103 = size_binop (PLUS_EXPR, unpadded_size_unit, size_one_node);
1105 /* Record the un-rounded size in the binfo node. But first we check
1106 the size of TYPE_BINFO to make sure that BINFO_SIZE is available. */
1107 if (TYPE_BINFO (rli->t) && TREE_VEC_LENGTH (TYPE_BINFO (rli->t)) > 6)
1109 TYPE_BINFO_SIZE (rli->t) = unpadded_size;
1110 TYPE_BINFO_SIZE_UNIT (rli->t) = unpadded_size_unit;
1113 /* Round the size up to be a multiple of the required alignment */
1114 #ifdef ROUND_TYPE_SIZE
1115 TYPE_SIZE (rli->t) = ROUND_TYPE_SIZE (rli->t, unpadded_size,
1116 TYPE_ALIGN (rli->t));
1117 TYPE_SIZE_UNIT (rli->t)
1118 = ROUND_TYPE_SIZE_UNIT (rli->t, unpadded_size_unit,
1119 TYPE_ALIGN (rli->t) / BITS_PER_UNIT);
1121 TYPE_SIZE (rli->t) = round_up (unpadded_size, TYPE_ALIGN (rli->t));
1122 TYPE_SIZE_UNIT (rli->t) = round_up (unpadded_size_unit,
1123 TYPE_ALIGN (rli->t) / BITS_PER_UNIT);
1126 if (warn_padded && TREE_CONSTANT (unpadded_size)
1127 && simple_cst_equal (unpadded_size, TYPE_SIZE (rli->t)) == 0)
1128 warning ("padding struct size to alignment boundary");
1130 if (warn_packed && TREE_CODE (rli->t) == RECORD_TYPE
1131 && TYPE_PACKED (rli->t) && ! rli->packed_maybe_necessary
1132 && TREE_CONSTANT (unpadded_size))
1136 #ifdef ROUND_TYPE_ALIGN
1138 = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t), rli->unpacked_align);
1140 rli->unpacked_align = MAX (TYPE_ALIGN (rli->t), rli->unpacked_align);
1143 #ifdef ROUND_TYPE_SIZE
1144 unpacked_size = ROUND_TYPE_SIZE (rli->t, TYPE_SIZE (rli->t),
1145 rli->unpacked_align);
1147 unpacked_size = round_up (TYPE_SIZE (rli->t), rli->unpacked_align);
1150 if (simple_cst_equal (unpacked_size, TYPE_SIZE (rli->t)))
1152 TYPE_PACKED (rli->t) = 0;
1154 if (TYPE_NAME (rli->t))
1158 if (TREE_CODE (TYPE_NAME (rli->t)) == IDENTIFIER_NODE)
1159 name = IDENTIFIER_POINTER (TYPE_NAME (rli->t));
1161 name = IDENTIFIER_POINTER (DECL_NAME (TYPE_NAME (rli->t)));
1163 if (STRICT_ALIGNMENT)
1164 warning ("packed attribute causes inefficient alignment for `%s'", name);
1166 warning ("packed attribute is unnecessary for `%s'", name);
1170 if (STRICT_ALIGNMENT)
1171 warning ("packed attribute causes inefficient alignment");
1173 warning ("packed attribute is unnecessary");
1179 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
1182 compute_record_mode (type)
1186 enum machine_mode mode = VOIDmode;
1188 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
1189 However, if possible, we use a mode that fits in a register
1190 instead, in order to allow for better optimization down the
1192 TYPE_MODE (type) = BLKmode;
1194 if (! host_integerp (TYPE_SIZE (type), 1))
1197 /* A record which has any BLKmode members must itself be
1198 BLKmode; it can't go in a register. Unless the member is
1199 BLKmode only because it isn't aligned. */
1200 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1202 unsigned HOST_WIDE_INT bitpos;
1204 if (TREE_CODE (field) != FIELD_DECL)
1207 if (TREE_CODE (TREE_TYPE (field)) == ERROR_MARK
1208 || (TYPE_MODE (TREE_TYPE (field)) == BLKmode
1209 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field)))
1210 || ! host_integerp (bit_position (field), 1)
1211 || DECL_SIZE (field) == 0
1212 || ! host_integerp (DECL_SIZE (field), 1))
1215 bitpos = int_bit_position (field);
1217 /* Must be BLKmode if any field crosses a word boundary,
1218 since extract_bit_field can't handle that in registers. */
1219 if (bitpos / BITS_PER_WORD
1220 != ((tree_low_cst (DECL_SIZE (field), 1) + bitpos - 1)
1222 /* But there is no problem if the field is entire words. */
1223 && tree_low_cst (DECL_SIZE (field), 1) % BITS_PER_WORD != 0)
1226 /* If this field is the whole struct, remember its mode so
1227 that, say, we can put a double in a class into a DF
1228 register instead of forcing it to live in the stack. */
1229 if (simple_cst_equal (TYPE_SIZE (type), DECL_SIZE (field)))
1230 mode = DECL_MODE (field);
1232 #ifdef MEMBER_TYPE_FORCES_BLK
1233 /* With some targets, eg. c4x, it is sub-optimal
1234 to access an aligned BLKmode structure as a scalar. */
1236 /* On ia64-*-hpux we need to ensure that we don't change the
1237 mode of a structure containing a single field or else we
1238 will pass it incorrectly. Since a structure with a single
1239 field causes mode to get set above we can't allow the
1240 check for mode == VOIDmode in this case. Perhaps
1241 MEMBER_TYPE_FORCES_BLK should be extended to include mode
1242 as an argument and the check could be put in there for c4x. */
1244 if ((mode == VOIDmode || FUNCTION_ARG_REG_LITTLE_ENDIAN)
1245 && MEMBER_TYPE_FORCES_BLK (field))
1247 #endif /* MEMBER_TYPE_FORCES_BLK */
1250 /* If we only have one real field; use its mode. This only applies to
1251 RECORD_TYPE. This does not apply to unions. */
1252 if (TREE_CODE (type) == RECORD_TYPE && mode != VOIDmode)
1253 TYPE_MODE (type) = mode;
1255 TYPE_MODE (type) = mode_for_size_tree (TYPE_SIZE (type), MODE_INT, 1);
1257 /* If structure's known alignment is less than what the scalar
1258 mode would need, and it matters, then stick with BLKmode. */
1259 if (TYPE_MODE (type) != BLKmode
1261 && ! (TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT
1262 || TYPE_ALIGN (type) >= GET_MODE_ALIGNMENT (TYPE_MODE (type))))
1264 /* If this is the only reason this type is BLKmode, then
1265 don't force containing types to be BLKmode. */
1266 TYPE_NO_FORCE_BLK (type) = 1;
1267 TYPE_MODE (type) = BLKmode;
1271 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1275 finalize_type_size (type)
1278 /* Normally, use the alignment corresponding to the mode chosen.
1279 However, where strict alignment is not required, avoid
1280 over-aligning structures, since most compilers do not do this
1283 if (TYPE_MODE (type) != BLKmode && TYPE_MODE (type) != VOIDmode
1284 && (STRICT_ALIGNMENT
1285 || (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE
1286 && TREE_CODE (type) != QUAL_UNION_TYPE
1287 && TREE_CODE (type) != ARRAY_TYPE)))
1289 TYPE_ALIGN (type) = GET_MODE_ALIGNMENT (TYPE_MODE (type));
1290 TYPE_USER_ALIGN (type) = 0;
1293 /* Do machine-dependent extra alignment. */
1294 #ifdef ROUND_TYPE_ALIGN
1296 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (type), BITS_PER_UNIT);
1299 /* If we failed to find a simple way to calculate the unit size
1300 of the type, find it by division. */
1301 if (TYPE_SIZE_UNIT (type) == 0 && TYPE_SIZE (type) != 0)
1302 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1303 result will fit in sizetype. We will get more efficient code using
1304 sizetype, so we force a conversion. */
1305 TYPE_SIZE_UNIT (type)
1306 = convert (sizetype,
1307 size_binop (FLOOR_DIV_EXPR, TYPE_SIZE (type),
1308 bitsize_unit_node));
1310 if (TYPE_SIZE (type) != 0)
1312 #ifdef ROUND_TYPE_SIZE
1314 = ROUND_TYPE_SIZE (type, TYPE_SIZE (type), TYPE_ALIGN (type));
1315 TYPE_SIZE_UNIT (type)
1316 = ROUND_TYPE_SIZE_UNIT (type, TYPE_SIZE_UNIT (type),
1317 TYPE_ALIGN (type) / BITS_PER_UNIT);
1319 TYPE_SIZE (type) = round_up (TYPE_SIZE (type), TYPE_ALIGN (type));
1320 TYPE_SIZE_UNIT (type)
1321 = round_up (TYPE_SIZE_UNIT (type), TYPE_ALIGN (type) / BITS_PER_UNIT);
1325 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1326 if (TYPE_SIZE (type) != 0 && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
1327 TYPE_SIZE (type) = variable_size (TYPE_SIZE (type));
1328 if (TYPE_SIZE_UNIT (type) != 0
1329 && TREE_CODE (TYPE_SIZE_UNIT (type)) != INTEGER_CST)
1330 TYPE_SIZE_UNIT (type) = variable_size (TYPE_SIZE_UNIT (type));
1332 /* Also layout any other variants of the type. */
1333 if (TYPE_NEXT_VARIANT (type)
1334 || type != TYPE_MAIN_VARIANT (type))
1337 /* Record layout info of this variant. */
1338 tree size = TYPE_SIZE (type);
1339 tree size_unit = TYPE_SIZE_UNIT (type);
1340 unsigned int align = TYPE_ALIGN (type);
1341 unsigned int user_align = TYPE_USER_ALIGN (type);
1342 enum machine_mode mode = TYPE_MODE (type);
1344 /* Copy it into all variants. */
1345 for (variant = TYPE_MAIN_VARIANT (type);
1347 variant = TYPE_NEXT_VARIANT (variant))
1349 TYPE_SIZE (variant) = size;
1350 TYPE_SIZE_UNIT (variant) = size_unit;
1351 TYPE_ALIGN (variant) = align;
1352 TYPE_USER_ALIGN (variant) = user_align;
1353 TYPE_MODE (variant) = mode;
1358 /* Do all of the work required to layout the type indicated by RLI,
1359 once the fields have been laid out. This function will call `free'
1363 finish_record_layout (rli)
1364 record_layout_info rli;
1366 /* Compute the final size. */
1367 finalize_record_size (rli);
1369 /* Compute the TYPE_MODE for the record. */
1370 compute_record_mode (rli->t);
1372 /* Perform any last tweaks to the TYPE_SIZE, etc. */
1373 finalize_type_size (rli->t);
1375 /* Lay out any static members. This is done now because their type
1376 may use the record's type. */
1377 while (rli->pending_statics)
1379 layout_decl (TREE_VALUE (rli->pending_statics), 0);
1380 rli->pending_statics = TREE_CHAIN (rli->pending_statics);
1387 /* Calculate the mode, size, and alignment for TYPE.
1388 For an array type, calculate the element separation as well.
1389 Record TYPE on the chain of permanent or temporary types
1390 so that dbxout will find out about it.
1392 TYPE_SIZE of a type is nonzero if the type has been laid out already.
1393 layout_type does nothing on such a type.
1395 If the type is incomplete, its TYPE_SIZE remains zero. */
1404 /* Do nothing if type has been laid out before. */
1405 if (TYPE_SIZE (type))
1408 switch (TREE_CODE (type))
1411 /* This kind of type is the responsibility
1412 of the language-specific code. */
1415 case BOOLEAN_TYPE: /* Used for Java, Pascal, and Chill. */
1416 if (TYPE_PRECISION (type) == 0)
1417 TYPE_PRECISION (type) = 1; /* default to one byte/boolean. */
1419 /* ... fall through ... */
1424 if (TREE_CODE (TYPE_MIN_VALUE (type)) == INTEGER_CST
1425 && tree_int_cst_sgn (TYPE_MIN_VALUE (type)) >= 0)
1426 TREE_UNSIGNED (type) = 1;
1428 TYPE_MODE (type) = smallest_mode_for_size (TYPE_PRECISION (type),
1430 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1431 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1435 TYPE_MODE (type) = mode_for_size (TYPE_PRECISION (type), MODE_FLOAT, 0);
1436 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1437 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1441 TREE_UNSIGNED (type) = TREE_UNSIGNED (TREE_TYPE (type));
1443 = mode_for_size (2 * TYPE_PRECISION (TREE_TYPE (type)),
1444 (TREE_CODE (TREE_TYPE (type)) == INTEGER_TYPE
1445 ? MODE_COMPLEX_INT : MODE_COMPLEX_FLOAT),
1447 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1448 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1455 subtype = TREE_TYPE (type);
1456 TREE_UNSIGNED (type) = TREE_UNSIGNED (subtype);
1457 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1458 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1463 /* This is an incomplete type and so doesn't have a size. */
1464 TYPE_ALIGN (type) = 1;
1465 TYPE_USER_ALIGN (type) = 0;
1466 TYPE_MODE (type) = VOIDmode;
1470 TYPE_SIZE (type) = bitsize_int (POINTER_SIZE);
1471 TYPE_SIZE_UNIT (type) = size_int (POINTER_SIZE / BITS_PER_UNIT);
1472 /* A pointer might be MODE_PARTIAL_INT,
1473 but ptrdiff_t must be integral. */
1474 TYPE_MODE (type) = mode_for_size (POINTER_SIZE, MODE_INT, 0);
1479 TYPE_MODE (type) = mode_for_size (2 * POINTER_SIZE, MODE_INT, 0);
1480 TYPE_SIZE (type) = bitsize_int (2 * POINTER_SIZE);
1481 TYPE_SIZE_UNIT (type) = size_int ((2 * POINTER_SIZE) / BITS_PER_UNIT);
1485 case REFERENCE_TYPE:
1487 int nbits = ((TREE_CODE (type) == REFERENCE_TYPE
1488 && reference_types_internal)
1489 ? GET_MODE_BITSIZE (Pmode) : POINTER_SIZE);
1491 TYPE_MODE (type) = nbits == POINTER_SIZE ? ptr_mode : Pmode;
1492 TYPE_SIZE (type) = bitsize_int (nbits);
1493 TYPE_SIZE_UNIT (type) = size_int (nbits / BITS_PER_UNIT);
1494 TREE_UNSIGNED (type) = 1;
1495 TYPE_PRECISION (type) = nbits;
1501 tree index = TYPE_DOMAIN (type);
1502 tree element = TREE_TYPE (type);
1504 build_pointer_type (element);
1506 /* We need to know both bounds in order to compute the size. */
1507 if (index && TYPE_MAX_VALUE (index) && TYPE_MIN_VALUE (index)
1508 && TYPE_SIZE (element))
1510 tree ub = TYPE_MAX_VALUE (index);
1511 tree lb = TYPE_MIN_VALUE (index);
1515 /* The initial subtraction should happen in the original type so
1516 that (possible) negative values are handled appropriately. */
1517 length = size_binop (PLUS_EXPR, size_one_node,
1519 fold (build (MINUS_EXPR,
1523 /* Special handling for arrays of bits (for Chill). */
1524 element_size = TYPE_SIZE (element);
1525 if (TYPE_PACKED (type) && INTEGRAL_TYPE_P (element)
1526 && (integer_zerop (TYPE_MAX_VALUE (element))
1527 || integer_onep (TYPE_MAX_VALUE (element)))
1528 && host_integerp (TYPE_MIN_VALUE (element), 1))
1530 HOST_WIDE_INT maxvalue
1531 = tree_low_cst (TYPE_MAX_VALUE (element), 1);
1532 HOST_WIDE_INT minvalue
1533 = tree_low_cst (TYPE_MIN_VALUE (element), 1);
1535 if (maxvalue - minvalue == 1
1536 && (maxvalue == 1 || maxvalue == 0))
1537 element_size = integer_one_node;
1540 TYPE_SIZE (type) = size_binop (MULT_EXPR, element_size,
1541 convert (bitsizetype, length));
1543 /* If we know the size of the element, calculate the total
1544 size directly, rather than do some division thing below.
1545 This optimization helps Fortran assumed-size arrays
1546 (where the size of the array is determined at runtime)
1548 Note that we can't do this in the case where the size of
1549 the elements is one bit since TYPE_SIZE_UNIT cannot be
1550 set correctly in that case. */
1551 if (TYPE_SIZE_UNIT (element) != 0 && ! integer_onep (element_size))
1552 TYPE_SIZE_UNIT (type)
1553 = size_binop (MULT_EXPR, TYPE_SIZE_UNIT (element), length);
1556 /* Now round the alignment and size,
1557 using machine-dependent criteria if any. */
1559 #ifdef ROUND_TYPE_ALIGN
1561 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (element), BITS_PER_UNIT);
1563 TYPE_ALIGN (type) = MAX (TYPE_ALIGN (element), BITS_PER_UNIT);
1565 TYPE_USER_ALIGN (type) = TYPE_USER_ALIGN (element);
1567 #ifdef ROUND_TYPE_SIZE
1568 if (TYPE_SIZE (type) != 0)
1571 = ROUND_TYPE_SIZE (type, TYPE_SIZE (type), TYPE_ALIGN (type));
1573 /* If the rounding changed the size of the type, remove any
1574 pre-calculated TYPE_SIZE_UNIT. */
1575 if (simple_cst_equal (TYPE_SIZE (type), tmp) != 1)
1576 TYPE_SIZE_UNIT (type) = NULL;
1578 TYPE_SIZE (type) = tmp;
1582 TYPE_MODE (type) = BLKmode;
1583 if (TYPE_SIZE (type) != 0
1584 #ifdef MEMBER_TYPE_FORCES_BLK
1585 && ! MEMBER_TYPE_FORCES_BLK (type)
1587 /* BLKmode elements force BLKmode aggregate;
1588 else extract/store fields may lose. */
1589 && (TYPE_MODE (TREE_TYPE (type)) != BLKmode
1590 || TYPE_NO_FORCE_BLK (TREE_TYPE (type))))
1592 /* One-element arrays get the component type's mode. */
1593 if (simple_cst_equal (TYPE_SIZE (type),
1594 TYPE_SIZE (TREE_TYPE (type))))
1595 TYPE_MODE (type) = TYPE_MODE (TREE_TYPE (type));
1598 = mode_for_size_tree (TYPE_SIZE (type), MODE_INT, 1);
1600 if (TYPE_MODE (type) != BLKmode
1601 && STRICT_ALIGNMENT && TYPE_ALIGN (type) < BIGGEST_ALIGNMENT
1602 && TYPE_ALIGN (type) < GET_MODE_ALIGNMENT (TYPE_MODE (type))
1603 && TYPE_MODE (type) != BLKmode)
1605 TYPE_NO_FORCE_BLK (type) = 1;
1606 TYPE_MODE (type) = BLKmode;
1614 case QUAL_UNION_TYPE:
1617 record_layout_info rli;
1619 /* Initialize the layout information. */
1620 rli = start_record_layout (type);
1622 /* If this is a QUAL_UNION_TYPE, we want to process the fields
1623 in the reverse order in building the COND_EXPR that denotes
1624 its size. We reverse them again later. */
1625 if (TREE_CODE (type) == QUAL_UNION_TYPE)
1626 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
1628 /* Place all the fields. */
1629 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1630 place_field (rli, field);
1632 if (TREE_CODE (type) == QUAL_UNION_TYPE)
1633 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
1635 if (lang_adjust_rli)
1636 (*lang_adjust_rli) (rli);
1638 /* Finish laying out the record. */
1639 finish_record_layout (rli);
1643 case SET_TYPE: /* Used by Chill and Pascal. */
1644 if (TREE_CODE (TYPE_MAX_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST
1645 || TREE_CODE (TYPE_MIN_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST)
1649 #ifndef SET_WORD_SIZE
1650 #define SET_WORD_SIZE BITS_PER_WORD
1652 unsigned int alignment
1653 = set_alignment ? set_alignment : SET_WORD_SIZE;
1655 = (TREE_INT_CST_LOW (TYPE_MAX_VALUE (TYPE_DOMAIN (type)))
1656 - TREE_INT_CST_LOW (TYPE_MIN_VALUE (TYPE_DOMAIN (type))) + 1);
1658 = ((size_in_bits + alignment - 1) / alignment) * alignment;
1660 if (rounded_size > (int) alignment)
1661 TYPE_MODE (type) = BLKmode;
1663 TYPE_MODE (type) = mode_for_size (alignment, MODE_INT, 1);
1665 TYPE_SIZE (type) = bitsize_int (rounded_size);
1666 TYPE_SIZE_UNIT (type) = size_int (rounded_size / BITS_PER_UNIT);
1667 TYPE_ALIGN (type) = alignment;
1668 TYPE_USER_ALIGN (type) = 0;
1669 TYPE_PRECISION (type) = size_in_bits;
1674 /* The size may vary in different languages, so the language front end
1675 should fill in the size. */
1676 TYPE_ALIGN (type) = BIGGEST_ALIGNMENT;
1677 TYPE_USER_ALIGN (type) = 0;
1678 TYPE_MODE (type) = BLKmode;
1685 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
1686 records and unions, finish_record_layout already called this
1688 if (TREE_CODE (type) != RECORD_TYPE
1689 && TREE_CODE (type) != UNION_TYPE
1690 && TREE_CODE (type) != QUAL_UNION_TYPE)
1691 finalize_type_size (type);
1693 /* If this type is created before sizetype has been permanently set,
1694 record it so set_sizetype can fix it up. */
1696 early_type_list = tree_cons (NULL_TREE, type, early_type_list);
1698 /* If an alias set has been set for this aggregate when it was incomplete,
1699 force it into alias set 0.
1700 This is too conservative, but we cannot call record_component_aliases
1701 here because some frontends still change the aggregates after
1703 if (AGGREGATE_TYPE_P (type) && TYPE_ALIAS_SET_KNOWN_P (type))
1704 TYPE_ALIAS_SET (type) = 0;
1707 /* Create and return a type for signed integers of PRECISION bits. */
1710 make_signed_type (precision)
1713 tree type = make_node (INTEGER_TYPE);
1715 TYPE_PRECISION (type) = precision;
1717 fixup_signed_type (type);
1721 /* Create and return a type for unsigned integers of PRECISION bits. */
1724 make_unsigned_type (precision)
1727 tree type = make_node (INTEGER_TYPE);
1729 TYPE_PRECISION (type) = precision;
1731 fixup_unsigned_type (type);
1735 /* Initialize sizetype and bitsizetype to a reasonable and temporary
1736 value to enable integer types to be created. */
1739 initialize_sizetypes ()
1741 tree t = make_node (INTEGER_TYPE);
1743 /* Set this so we do something reasonable for the build_int_2 calls
1745 integer_type_node = t;
1747 TYPE_MODE (t) = SImode;
1748 TYPE_ALIGN (t) = GET_MODE_ALIGNMENT (SImode);
1749 TYPE_USER_ALIGN (t) = 0;
1750 TYPE_SIZE (t) = build_int_2 (GET_MODE_BITSIZE (SImode), 0);
1751 TYPE_SIZE_UNIT (t) = build_int_2 (GET_MODE_SIZE (SImode), 0);
1752 TREE_UNSIGNED (t) = 1;
1753 TYPE_PRECISION (t) = GET_MODE_BITSIZE (SImode);
1754 TYPE_MIN_VALUE (t) = build_int_2 (0, 0);
1755 TYPE_IS_SIZETYPE (t) = 1;
1757 /* 1000 avoids problems with possible overflow and is certainly
1758 larger than any size value we'd want to be storing. */
1759 TYPE_MAX_VALUE (t) = build_int_2 (1000, 0);
1761 /* These two must be different nodes because of the caching done in
1764 bitsizetype = copy_node (t);
1765 integer_type_node = 0;
1768 /* Set sizetype to TYPE, and initialize *sizetype accordingly.
1769 Also update the type of any standard type's sizes made so far. */
1775 int oprecision = TYPE_PRECISION (type);
1776 /* The *bitsizetype types use a precision that avoids overflows when
1777 calculating signed sizes / offsets in bits. However, when
1778 cross-compiling from a 32 bit to a 64 bit host, we are limited to 64 bit
1780 int precision = MIN (oprecision + BITS_PER_UNIT_LOG + 1,
1781 2 * HOST_BITS_PER_WIDE_INT);
1788 /* Make copies of nodes since we'll be setting TYPE_IS_SIZETYPE. */
1789 sizetype = copy_node (type);
1790 TYPE_DOMAIN (sizetype) = type;
1791 TYPE_IS_SIZETYPE (sizetype) = 1;
1792 bitsizetype = make_node (INTEGER_TYPE);
1793 TYPE_NAME (bitsizetype) = TYPE_NAME (type);
1794 TYPE_PRECISION (bitsizetype) = precision;
1795 TYPE_IS_SIZETYPE (bitsizetype) = 1;
1797 if (TREE_UNSIGNED (type))
1798 fixup_unsigned_type (bitsizetype);
1800 fixup_signed_type (bitsizetype);
1802 layout_type (bitsizetype);
1804 if (TREE_UNSIGNED (type))
1806 usizetype = sizetype;
1807 ubitsizetype = bitsizetype;
1808 ssizetype = copy_node (make_signed_type (oprecision));
1809 sbitsizetype = copy_node (make_signed_type (precision));
1813 ssizetype = sizetype;
1814 sbitsizetype = bitsizetype;
1815 usizetype = copy_node (make_unsigned_type (oprecision));
1816 ubitsizetype = copy_node (make_unsigned_type (precision));
1819 TYPE_NAME (bitsizetype) = get_identifier ("bit_size_type");
1821 /* Show is a sizetype, is a main type, and has no pointers to it. */
1822 for (i = 0; i < ARRAY_SIZE (sizetype_tab); i++)
1824 TYPE_IS_SIZETYPE (sizetype_tab[i]) = 1;
1825 TYPE_MAIN_VARIANT (sizetype_tab[i]) = sizetype_tab[i];
1826 TYPE_NEXT_VARIANT (sizetype_tab[i]) = 0;
1827 TYPE_POINTER_TO (sizetype_tab[i]) = 0;
1828 TYPE_REFERENCE_TO (sizetype_tab[i]) = 0;
1831 ggc_add_tree_root ((tree *) &sizetype_tab, ARRAY_SIZE (sizetype_tab));
1833 /* Go down each of the types we already made and set the proper type
1834 for the sizes in them. */
1835 for (t = early_type_list; t != 0; t = TREE_CHAIN (t))
1837 if (TREE_CODE (TREE_VALUE (t)) != INTEGER_TYPE)
1840 TREE_TYPE (TYPE_SIZE (TREE_VALUE (t))) = bitsizetype;
1841 TREE_TYPE (TYPE_SIZE_UNIT (TREE_VALUE (t))) = sizetype;
1844 early_type_list = 0;
1848 /* Set the extreme values of TYPE based on its precision in bits,
1849 then lay it out. Used when make_signed_type won't do
1850 because the tree code is not INTEGER_TYPE.
1851 E.g. for Pascal, when the -fsigned-char option is given. */
1854 fixup_signed_type (type)
1857 int precision = TYPE_PRECISION (type);
1859 /* We can not represent properly constants greater then
1860 2 * HOST_BITS_PER_WIDE_INT, still we need the types
1861 as they are used by i386 vector extensions and friends. */
1862 if (precision > HOST_BITS_PER_WIDE_INT * 2)
1863 precision = HOST_BITS_PER_WIDE_INT * 2;
1865 TYPE_MIN_VALUE (type)
1866 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1867 ? 0 : (HOST_WIDE_INT) (-1) << (precision - 1)),
1868 (((HOST_WIDE_INT) (-1)
1869 << (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1870 ? precision - HOST_BITS_PER_WIDE_INT - 1
1872 TYPE_MAX_VALUE (type)
1873 = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
1874 ? -1 : ((HOST_WIDE_INT) 1 << (precision - 1)) - 1),
1875 (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
1876 ? (((HOST_WIDE_INT) 1
1877 << (precision - HOST_BITS_PER_WIDE_INT - 1))) - 1
1880 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
1881 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
1883 /* Lay out the type: set its alignment, size, etc. */
1887 /* Set the extreme values of TYPE based on its precision in bits,
1888 then lay it out. This is used both in `make_unsigned_type'
1889 and for enumeral types. */
1892 fixup_unsigned_type (type)
1895 int precision = TYPE_PRECISION (type);
1897 /* We can not represent properly constants greater then
1898 2 * HOST_BITS_PER_WIDE_INT, still we need the types
1899 as they are used by i386 vector extensions and friends. */
1900 if (precision > HOST_BITS_PER_WIDE_INT * 2)
1901 precision = HOST_BITS_PER_WIDE_INT * 2;
1903 TYPE_MIN_VALUE (type) = build_int_2 (0, 0);
1904 TYPE_MAX_VALUE (type)
1905 = build_int_2 (precision - HOST_BITS_PER_WIDE_INT >= 0
1906 ? -1 : ((HOST_WIDE_INT) 1 << precision) - 1,
1907 precision - HOST_BITS_PER_WIDE_INT > 0
1908 ? ((unsigned HOST_WIDE_INT) ~0
1909 >> (HOST_BITS_PER_WIDE_INT
1910 - (precision - HOST_BITS_PER_WIDE_INT)))
1912 TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
1913 TREE_TYPE (TYPE_MAX_VALUE (type)) = type;
1915 /* Lay out the type: set its alignment, size, etc. */
1919 /* Find the best machine mode to use when referencing a bit field of length
1920 BITSIZE bits starting at BITPOS.
1922 The underlying object is known to be aligned to a boundary of ALIGN bits.
1923 If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
1924 larger than LARGEST_MODE (usually SImode).
1926 If no mode meets all these conditions, we return VOIDmode. Otherwise, if
1927 VOLATILEP is true or SLOW_BYTE_ACCESS is false, we return the smallest
1928 mode meeting these conditions.
1930 Otherwise (VOLATILEP is false and SLOW_BYTE_ACCESS is true), we return
1931 the largest mode (but a mode no wider than UNITS_PER_WORD) that meets
1932 all the conditions. */
1935 get_best_mode (bitsize, bitpos, align, largest_mode, volatilep)
1936 int bitsize, bitpos;
1938 enum machine_mode largest_mode;
1941 enum machine_mode mode;
1942 unsigned int unit = 0;
1944 /* Find the narrowest integer mode that contains the bit field. */
1945 for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
1946 mode = GET_MODE_WIDER_MODE (mode))
1948 unit = GET_MODE_BITSIZE (mode);
1949 if ((bitpos % unit) + bitsize <= unit)
1953 if (mode == VOIDmode
1954 /* It is tempting to omit the following line
1955 if STRICT_ALIGNMENT is true.
1956 But that is incorrect, since if the bitfield uses part of 3 bytes
1957 and we use a 4-byte mode, we could get a spurious segv
1958 if the extra 4th byte is past the end of memory.
1959 (Though at least one Unix compiler ignores this problem:
1960 that on the Sequent 386 machine. */
1961 || MIN (unit, BIGGEST_ALIGNMENT) > align
1962 || (largest_mode != VOIDmode && unit > GET_MODE_BITSIZE (largest_mode)))
1965 if (SLOW_BYTE_ACCESS && ! volatilep)
1967 enum machine_mode wide_mode = VOIDmode, tmode;
1969 for (tmode = GET_CLASS_NARROWEST_MODE (MODE_INT); tmode != VOIDmode;
1970 tmode = GET_MODE_WIDER_MODE (tmode))
1972 unit = GET_MODE_BITSIZE (tmode);
1973 if (bitpos / unit == (bitpos + bitsize - 1) / unit
1974 && unit <= BITS_PER_WORD
1975 && unit <= MIN (align, BIGGEST_ALIGNMENT)
1976 && (largest_mode == VOIDmode
1977 || unit <= GET_MODE_BITSIZE (largest_mode)))
1981 if (wide_mode != VOIDmode)
1988 /* This function is run once to initialize stor-layout.c. */
1991 init_stor_layout_once ()
1993 ggc_add_tree_root (&pending_sizes, 1);