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, 2005, 2006
4 Free Software Foundation, Inc.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 2, or (at your option) any later
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING. If not, write to the Free
20 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
26 #include "coretypes.h"
38 #include "langhooks.h"
42 /* Data type for the expressions representing sizes of data types.
43 It is the first integer type laid out. */
44 tree sizetype_tab
[(int) TYPE_KIND_LAST
];
46 /* If nonzero, this is an upper limit on alignment of structure fields.
47 The value is measured in bits. */
48 unsigned int maximum_field_alignment
= TARGET_DEFAULT_PACK_STRUCT
* BITS_PER_UNIT
;
49 /* ... and its original value in bytes, specified via -fpack-struct=<value>. */
50 unsigned int initial_max_fld_align
= TARGET_DEFAULT_PACK_STRUCT
;
52 /* Nonzero if all REFERENCE_TYPEs are internal and hence should be
53 allocated in Pmode, not ptr_mode. Set only by internal_reference_types
54 called only by a front end. */
55 static int reference_types_internal
= 0;
57 static void finalize_record_size (record_layout_info
);
58 static void finalize_type_size (tree
);
59 static void place_union_field (record_layout_info
, tree
);
60 #if defined (PCC_BITFIELD_TYPE_MATTERS) || defined (BITFIELD_NBYTES_LIMITED)
61 static int excess_unit_span (HOST_WIDE_INT
, HOST_WIDE_INT
, HOST_WIDE_INT
,
64 extern void debug_rli (record_layout_info
);
66 /* SAVE_EXPRs for sizes of types and decls, waiting to be expanded. */
68 static GTY(()) tree pending_sizes
;
70 /* Show that REFERENCE_TYPES are internal and should be Pmode. Called only
74 internal_reference_types (void)
76 reference_types_internal
= 1;
79 /* Get a list of all the objects put on the pending sizes list. */
82 get_pending_sizes (void)
84 tree chain
= pending_sizes
;
90 /* Add EXPR to the pending sizes list. */
93 put_pending_size (tree expr
)
95 /* Strip any simple arithmetic from EXPR to see if it has an underlying
97 expr
= skip_simple_arithmetic (expr
);
99 if (TREE_CODE (expr
) == SAVE_EXPR
)
100 pending_sizes
= tree_cons (NULL_TREE
, expr
, pending_sizes
);
103 /* Put a chain of objects into the pending sizes list, which must be
107 put_pending_sizes (tree chain
)
109 gcc_assert (!pending_sizes
);
110 pending_sizes
= chain
;
113 /* Given a size SIZE that may not be a constant, return a SAVE_EXPR
114 to serve as the actual size-expression for a type or decl. */
117 variable_size (tree size
)
121 /* If the language-processor is to take responsibility for variable-sized
122 items (e.g., languages which have elaboration procedures like Ada),
123 just return SIZE unchanged. Likewise for self-referential sizes and
125 if (TREE_CONSTANT (size
)
126 || lang_hooks
.decls
.global_bindings_p () < 0
127 || CONTAINS_PLACEHOLDER_P (size
))
130 size
= save_expr (size
);
132 /* If an array with a variable number of elements is declared, and
133 the elements require destruction, we will emit a cleanup for the
134 array. That cleanup is run both on normal exit from the block
135 and in the exception-handler for the block. Normally, when code
136 is used in both ordinary code and in an exception handler it is
137 `unsaved', i.e., all SAVE_EXPRs are recalculated. However, we do
138 not wish to do that here; the array-size is the same in both
140 save
= skip_simple_arithmetic (size
);
142 if (cfun
&& cfun
->x_dont_save_pending_sizes_p
)
143 /* The front-end doesn't want us to keep a list of the expressions
144 that determine sizes for variable size objects. Trust it. */
147 if (lang_hooks
.decls
.global_bindings_p ())
149 if (TREE_CONSTANT (size
))
150 error ("type size can%'t be explicitly evaluated");
152 error ("variable-size type declared outside of any function");
154 return size_one_node
;
157 put_pending_size (save
);
162 #ifndef MAX_FIXED_MODE_SIZE
163 #define MAX_FIXED_MODE_SIZE GET_MODE_BITSIZE (DImode)
166 /* Return the machine mode to use for a nonscalar of SIZE bits. The
167 mode must be in class CLASS, and have exactly that many value bits;
168 it may have padding as well. If LIMIT is nonzero, modes of wider
169 than MAX_FIXED_MODE_SIZE will not be used. */
172 mode_for_size (unsigned int size
, enum mode_class
class, int limit
)
174 enum machine_mode mode
;
176 if (limit
&& size
> MAX_FIXED_MODE_SIZE
)
179 /* Get the first mode which has this size, in the specified class. */
180 for (mode
= GET_CLASS_NARROWEST_MODE (class); mode
!= VOIDmode
;
181 mode
= GET_MODE_WIDER_MODE (mode
))
182 if (GET_MODE_PRECISION (mode
) == size
)
188 /* Similar, except passed a tree node. */
191 mode_for_size_tree (tree size
, enum mode_class
class, int limit
)
193 unsigned HOST_WIDE_INT uhwi
;
196 if (!host_integerp (size
, 1))
198 uhwi
= tree_low_cst (size
, 1);
202 return mode_for_size (ui
, class, limit
);
205 /* Similar, but never return BLKmode; return the narrowest mode that
206 contains at least the requested number of value bits. */
209 smallest_mode_for_size (unsigned int size
, enum mode_class
class)
211 enum machine_mode mode
;
213 /* Get the first mode which has at least this size, in the
215 for (mode
= GET_CLASS_NARROWEST_MODE (class); mode
!= VOIDmode
;
216 mode
= GET_MODE_WIDER_MODE (mode
))
217 if (GET_MODE_PRECISION (mode
) >= size
)
223 /* Find an integer mode of the exact same size, or BLKmode on failure. */
226 int_mode_for_mode (enum machine_mode mode
)
228 switch (GET_MODE_CLASS (mode
))
231 case MODE_PARTIAL_INT
:
234 case MODE_COMPLEX_INT
:
235 case MODE_COMPLEX_FLOAT
:
237 case MODE_DECIMAL_FLOAT
:
238 case MODE_VECTOR_INT
:
239 case MODE_VECTOR_FLOAT
:
240 mode
= mode_for_size (GET_MODE_BITSIZE (mode
), MODE_INT
, 0);
247 /* ... fall through ... */
257 /* Return the alignment of MODE. This will be bounded by 1 and
258 BIGGEST_ALIGNMENT. */
261 get_mode_alignment (enum machine_mode mode
)
263 return MIN (BIGGEST_ALIGNMENT
, MAX (1, mode_base_align
[mode
]*BITS_PER_UNIT
));
267 /* Subroutine of layout_decl: Force alignment required for the data type.
268 But if the decl itself wants greater alignment, don't override that. */
271 do_type_align (tree type
, tree decl
)
273 if (TYPE_ALIGN (type
) > DECL_ALIGN (decl
))
275 DECL_ALIGN (decl
) = TYPE_ALIGN (type
);
276 if (TREE_CODE (decl
) == FIELD_DECL
)
277 DECL_USER_ALIGN (decl
) = TYPE_USER_ALIGN (type
);
281 /* Set the size, mode and alignment of a ..._DECL node.
282 TYPE_DECL does need this for C++.
283 Note that LABEL_DECL and CONST_DECL nodes do not need this,
284 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
285 Don't call layout_decl for them.
287 KNOWN_ALIGN is the amount of alignment we can assume this
288 decl has with no special effort. It is relevant only for FIELD_DECLs
289 and depends on the previous fields.
290 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
291 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
292 the record will be aligned to suit. */
295 layout_decl (tree decl
, unsigned int known_align
)
297 tree type
= TREE_TYPE (decl
);
298 enum tree_code code
= TREE_CODE (decl
);
301 if (code
== CONST_DECL
)
304 gcc_assert (code
== VAR_DECL
|| code
== PARM_DECL
|| code
== RESULT_DECL
305 || code
== TYPE_DECL
||code
== FIELD_DECL
);
307 rtl
= DECL_RTL_IF_SET (decl
);
309 if (type
== error_mark_node
)
310 type
= void_type_node
;
312 /* Usually the size and mode come from the data type without change,
313 however, the front-end may set the explicit width of the field, so its
314 size may not be the same as the size of its type. This happens with
315 bitfields, of course (an `int' bitfield may be only 2 bits, say), but it
316 also happens with other fields. For example, the C++ front-end creates
317 zero-sized fields corresponding to empty base classes, and depends on
318 layout_type setting DECL_FIELD_BITPOS correctly for the field. Set the
319 size in bytes from the size in bits. If we have already set the mode,
320 don't set it again since we can be called twice for FIELD_DECLs. */
322 DECL_UNSIGNED (decl
) = TYPE_UNSIGNED (type
);
323 if (DECL_MODE (decl
) == VOIDmode
)
324 DECL_MODE (decl
) = TYPE_MODE (type
);
326 if (DECL_SIZE (decl
) == 0)
328 DECL_SIZE (decl
) = TYPE_SIZE (type
);
329 DECL_SIZE_UNIT (decl
) = TYPE_SIZE_UNIT (type
);
331 else if (DECL_SIZE_UNIT (decl
) == 0)
332 DECL_SIZE_UNIT (decl
)
333 = fold_convert (sizetype
, size_binop (CEIL_DIV_EXPR
, DECL_SIZE (decl
),
336 if (code
!= FIELD_DECL
)
337 /* For non-fields, update the alignment from the type. */
338 do_type_align (type
, decl
);
340 /* For fields, it's a bit more complicated... */
342 bool old_user_align
= DECL_USER_ALIGN (decl
);
343 bool zero_bitfield
= false;
344 bool packed_p
= DECL_PACKED (decl
);
347 if (DECL_BIT_FIELD (decl
))
349 DECL_BIT_FIELD_TYPE (decl
) = type
;
351 /* A zero-length bit-field affects the alignment of the next
352 field. In essence such bit-fields are not influenced by
353 any packing due to #pragma pack or attribute packed. */
354 if (integer_zerop (DECL_SIZE (decl
))
355 && ! targetm
.ms_bitfield_layout_p (DECL_FIELD_CONTEXT (decl
)))
357 zero_bitfield
= true;
359 #ifdef PCC_BITFIELD_TYPE_MATTERS
360 if (PCC_BITFIELD_TYPE_MATTERS
)
361 do_type_align (type
, decl
);
365 #ifdef EMPTY_FIELD_BOUNDARY
366 if (EMPTY_FIELD_BOUNDARY
> DECL_ALIGN (decl
))
368 DECL_ALIGN (decl
) = EMPTY_FIELD_BOUNDARY
;
369 DECL_USER_ALIGN (decl
) = 0;
375 /* See if we can use an ordinary integer mode for a bit-field.
376 Conditions are: a fixed size that is correct for another mode
377 and occupying a complete byte or bytes on proper boundary. */
378 if (TYPE_SIZE (type
) != 0
379 && TREE_CODE (TYPE_SIZE (type
)) == INTEGER_CST
380 && GET_MODE_CLASS (TYPE_MODE (type
)) == MODE_INT
)
382 enum machine_mode xmode
383 = mode_for_size_tree (DECL_SIZE (decl
), MODE_INT
, 1);
387 || known_align
>= GET_MODE_ALIGNMENT (xmode
)))
389 DECL_ALIGN (decl
) = MAX (GET_MODE_ALIGNMENT (xmode
),
391 DECL_MODE (decl
) = xmode
;
392 DECL_BIT_FIELD (decl
) = 0;
396 /* Turn off DECL_BIT_FIELD if we won't need it set. */
397 if (TYPE_MODE (type
) == BLKmode
&& DECL_MODE (decl
) == BLKmode
398 && known_align
>= TYPE_ALIGN (type
)
399 && DECL_ALIGN (decl
) >= TYPE_ALIGN (type
))
400 DECL_BIT_FIELD (decl
) = 0;
402 else if (packed_p
&& DECL_USER_ALIGN (decl
))
403 /* Don't touch DECL_ALIGN. For other packed fields, go ahead and
404 round up; we'll reduce it again below. We want packing to
405 supersede USER_ALIGN inherited from the type, but defer to
406 alignment explicitly specified on the field decl. */;
408 do_type_align (type
, decl
);
410 /* If the field is of variable size, we can't misalign it since we
411 have no way to make a temporary to align the result. But this
412 isn't an issue if the decl is not addressable. Likewise if it
415 Note that do_type_align may set DECL_USER_ALIGN, so we need to
416 check old_user_align instead. */
419 && (DECL_NONADDRESSABLE_P (decl
)
420 || DECL_SIZE_UNIT (decl
) == 0
421 || TREE_CODE (DECL_SIZE_UNIT (decl
)) == INTEGER_CST
))
422 DECL_ALIGN (decl
) = MIN (DECL_ALIGN (decl
), BITS_PER_UNIT
);
424 if (! packed_p
&& ! DECL_USER_ALIGN (decl
))
426 /* Some targets (i.e. i386, VMS) limit struct field alignment
427 to a lower boundary than alignment of variables unless
428 it was overridden by attribute aligned. */
429 #ifdef BIGGEST_FIELD_ALIGNMENT
431 = MIN (DECL_ALIGN (decl
), (unsigned) BIGGEST_FIELD_ALIGNMENT
);
433 #ifdef ADJUST_FIELD_ALIGN
434 DECL_ALIGN (decl
) = ADJUST_FIELD_ALIGN (decl
, DECL_ALIGN (decl
));
439 mfa
= initial_max_fld_align
* BITS_PER_UNIT
;
441 mfa
= maximum_field_alignment
;
442 /* Should this be controlled by DECL_USER_ALIGN, too? */
444 DECL_ALIGN (decl
) = MIN (DECL_ALIGN (decl
), mfa
);
447 /* Evaluate nonconstant size only once, either now or as soon as safe. */
448 if (DECL_SIZE (decl
) != 0 && TREE_CODE (DECL_SIZE (decl
)) != INTEGER_CST
)
449 DECL_SIZE (decl
) = variable_size (DECL_SIZE (decl
));
450 if (DECL_SIZE_UNIT (decl
) != 0
451 && TREE_CODE (DECL_SIZE_UNIT (decl
)) != INTEGER_CST
)
452 DECL_SIZE_UNIT (decl
) = variable_size (DECL_SIZE_UNIT (decl
));
454 /* If requested, warn about definitions of large data objects. */
456 && (code
== VAR_DECL
|| code
== PARM_DECL
)
457 && ! DECL_EXTERNAL (decl
))
459 tree size
= DECL_SIZE_UNIT (decl
);
461 if (size
!= 0 && TREE_CODE (size
) == INTEGER_CST
462 && compare_tree_int (size
, larger_than_size
) > 0)
464 int size_as_int
= TREE_INT_CST_LOW (size
);
466 if (compare_tree_int (size
, size_as_int
) == 0)
467 warning (0, "size of %q+D is %d bytes", decl
, size_as_int
);
469 warning (0, "size of %q+D is larger than %wd bytes",
470 decl
, larger_than_size
);
474 /* If the RTL was already set, update its mode and mem attributes. */
477 PUT_MODE (rtl
, DECL_MODE (decl
));
478 SET_DECL_RTL (decl
, 0);
479 set_mem_attributes (rtl
, decl
, 1);
480 SET_DECL_RTL (decl
, rtl
);
484 /* Given a VAR_DECL, PARM_DECL or RESULT_DECL, clears the results of
485 a previous call to layout_decl and calls it again. */
488 relayout_decl (tree decl
)
490 DECL_SIZE (decl
) = DECL_SIZE_UNIT (decl
) = 0;
491 DECL_MODE (decl
) = VOIDmode
;
492 DECL_ALIGN (decl
) = 0;
493 SET_DECL_RTL (decl
, 0);
495 layout_decl (decl
, 0);
498 /* Hook for a front-end function that can modify the record layout as needed
499 immediately before it is finalized. */
501 static void (*lang_adjust_rli
) (record_layout_info
) = 0;
504 set_lang_adjust_rli (void (*f
) (record_layout_info
))
509 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
510 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
511 is to be passed to all other layout functions for this record. It is the
512 responsibility of the caller to call `free' for the storage returned.
513 Note that garbage collection is not permitted until we finish laying
517 start_record_layout (tree t
)
519 record_layout_info rli
= xmalloc (sizeof (struct record_layout_info_s
));
523 /* If the type has a minimum specified alignment (via an attribute
524 declaration, for example) use it -- otherwise, start with a
525 one-byte alignment. */
526 rli
->record_align
= MAX (BITS_PER_UNIT
, TYPE_ALIGN (t
));
527 rli
->unpacked_align
= rli
->record_align
;
528 rli
->offset_align
= MAX (rli
->record_align
, BIGGEST_ALIGNMENT
);
530 #ifdef STRUCTURE_SIZE_BOUNDARY
531 /* Packed structures don't need to have minimum size. */
532 if (! TYPE_PACKED (t
))
533 rli
->record_align
= MAX (rli
->record_align
, (unsigned) STRUCTURE_SIZE_BOUNDARY
);
536 rli
->offset
= size_zero_node
;
537 rli
->bitpos
= bitsize_zero_node
;
539 rli
->pending_statics
= 0;
540 rli
->packed_maybe_necessary
= 0;
545 /* These four routines perform computations that convert between
546 the offset/bitpos forms and byte and bit offsets. */
549 bit_from_pos (tree offset
, tree bitpos
)
551 return size_binop (PLUS_EXPR
, bitpos
,
552 size_binop (MULT_EXPR
,
553 fold_convert (bitsizetype
, offset
),
558 byte_from_pos (tree offset
, tree bitpos
)
560 return size_binop (PLUS_EXPR
, offset
,
561 fold_convert (sizetype
,
562 size_binop (TRUNC_DIV_EXPR
, bitpos
,
563 bitsize_unit_node
)));
567 pos_from_bit (tree
*poffset
, tree
*pbitpos
, unsigned int off_align
,
570 *poffset
= size_binop (MULT_EXPR
,
571 fold_convert (sizetype
,
572 size_binop (FLOOR_DIV_EXPR
, pos
,
573 bitsize_int (off_align
))),
574 size_int (off_align
/ BITS_PER_UNIT
));
575 *pbitpos
= size_binop (FLOOR_MOD_EXPR
, pos
, bitsize_int (off_align
));
578 /* Given a pointer to bit and byte offsets and an offset alignment,
579 normalize the offsets so they are within the alignment. */
582 normalize_offset (tree
*poffset
, tree
*pbitpos
, 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
,
594 fold_convert (sizetype
, extra_aligns
),
595 size_int (off_align
/ BITS_PER_UNIT
)));
598 = size_binop (FLOOR_MOD_EXPR
, *pbitpos
, bitsize_int (off_align
));
602 /* Print debugging information about the information in RLI. */
605 debug_rli (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, off = %u\n",
612 rli
->record_align
, rli
->unpacked_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. */
628 normalize_rli (record_layout_info rli
)
630 normalize_offset (&rli
->offset
, &rli
->bitpos
, rli
->offset_align
);
633 /* Returns the size in bytes allocated so far. */
636 rli_size_unit_so_far (record_layout_info rli
)
638 return byte_from_pos (rli
->offset
, rli
->bitpos
);
641 /* Returns the size in bits allocated so far. */
644 rli_size_so_far (record_layout_info rli
)
646 return bit_from_pos (rli
->offset
, rli
->bitpos
);
649 /* FIELD is about to be added to RLI->T. The alignment (in bits) of
650 the next available location within the record is given by KNOWN_ALIGN.
651 Update the variable alignment fields in RLI, and return the alignment
652 to give the FIELD. */
655 update_alignment_for_field (record_layout_info rli
, tree field
,
656 unsigned int known_align
)
658 /* The alignment required for FIELD. */
659 unsigned int desired_align
;
660 /* The type of this field. */
661 tree type
= TREE_TYPE (field
);
662 /* True if the field was explicitly aligned by the user. */
666 /* Lay out the field so we know what alignment it needs. */
667 layout_decl (field
, known_align
);
668 desired_align
= DECL_ALIGN (field
);
669 user_align
= DECL_USER_ALIGN (field
);
671 is_bitfield
= (type
!= error_mark_node
672 && DECL_BIT_FIELD_TYPE (field
)
673 && ! integer_zerop (TYPE_SIZE (type
)));
675 /* Record must have at least as much alignment as any field.
676 Otherwise, the alignment of the field within the record is
678 if (is_bitfield
&& targetm
.ms_bitfield_layout_p (rli
->t
))
680 /* Here, the alignment of the underlying type of a bitfield can
681 affect the alignment of a record; even a zero-sized field
682 can do this. The alignment should be to the alignment of
683 the type, except that for zero-size bitfields this only
684 applies if there was an immediately prior, nonzero-size
685 bitfield. (That's the way it is, experimentally.) */
686 if (! integer_zerop (DECL_SIZE (field
))
687 ? ! DECL_PACKED (field
)
689 && DECL_BIT_FIELD_TYPE (rli
->prev_field
)
690 && ! integer_zerop (DECL_SIZE (rli
->prev_field
))))
692 unsigned int type_align
= TYPE_ALIGN (type
);
693 type_align
= MAX (type_align
, desired_align
);
694 if (maximum_field_alignment
!= 0)
695 type_align
= MIN (type_align
, maximum_field_alignment
);
696 rli
->record_align
= MAX (rli
->record_align
, type_align
);
697 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
698 /* If we start a new run, make sure we start it properly aligned. */
699 if ((!rli
->prev_field
700 || integer_zerop (DECL_SIZE (field
))
701 || integer_zerop (DECL_SIZE (rli
->prev_field
))
702 || !host_integerp (DECL_SIZE (rli
->prev_field
), 0)
703 || !host_integerp (TYPE_SIZE (type
), 0)
704 || !simple_cst_equal (TYPE_SIZE (type
),
705 TYPE_SIZE (TREE_TYPE (rli
->prev_field
)))
706 || (rli
->remaining_in_alignment
707 < tree_low_cst (DECL_SIZE (field
), 0)))
708 && desired_align
< type_align
)
709 desired_align
= type_align
;
712 #ifdef PCC_BITFIELD_TYPE_MATTERS
713 else if (is_bitfield
&& PCC_BITFIELD_TYPE_MATTERS
)
715 /* Named bit-fields cause the entire structure to have the
716 alignment implied by their type. Some targets also apply the same
717 rules to unnamed bitfields. */
718 if (DECL_NAME (field
) != 0
719 || targetm
.align_anon_bitfield ())
721 unsigned int type_align
= TYPE_ALIGN (type
);
723 #ifdef ADJUST_FIELD_ALIGN
724 if (! TYPE_USER_ALIGN (type
))
725 type_align
= ADJUST_FIELD_ALIGN (field
, type_align
);
728 /* Targets might chose to handle unnamed and hence possibly
729 zero-width bitfield. Those are not influenced by #pragmas
730 or packed attributes. */
731 if (integer_zerop (DECL_SIZE (field
)))
733 if (initial_max_fld_align
)
734 type_align
= MIN (type_align
,
735 initial_max_fld_align
* BITS_PER_UNIT
);
737 else if (maximum_field_alignment
!= 0)
738 type_align
= MIN (type_align
, maximum_field_alignment
);
739 else if (DECL_PACKED (field
))
740 type_align
= MIN (type_align
, BITS_PER_UNIT
);
742 /* The alignment of the record is increased to the maximum
743 of the current alignment, the alignment indicated on the
744 field (i.e., the alignment specified by an __aligned__
745 attribute), and the alignment indicated by the type of
747 rli
->record_align
= MAX (rli
->record_align
, desired_align
);
748 rli
->record_align
= MAX (rli
->record_align
, type_align
);
751 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
752 user_align
|= TYPE_USER_ALIGN (type
);
758 rli
->record_align
= MAX (rli
->record_align
, desired_align
);
759 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
762 TYPE_USER_ALIGN (rli
->t
) |= user_align
;
764 return desired_align
;
767 /* Called from place_field to handle unions. */
770 place_union_field (record_layout_info rli
, tree field
)
772 update_alignment_for_field (rli
, field
, /*known_align=*/0);
774 DECL_FIELD_OFFSET (field
) = size_zero_node
;
775 DECL_FIELD_BIT_OFFSET (field
) = bitsize_zero_node
;
776 SET_DECL_OFFSET_ALIGN (field
, BIGGEST_ALIGNMENT
);
778 /* We assume the union's size will be a multiple of a byte so we don't
779 bother with BITPOS. */
780 if (TREE_CODE (rli
->t
) == UNION_TYPE
)
781 rli
->offset
= size_binop (MAX_EXPR
, rli
->offset
, DECL_SIZE_UNIT (field
));
782 else if (TREE_CODE (rli
->t
) == QUAL_UNION_TYPE
)
783 rli
->offset
= fold_build3 (COND_EXPR
, sizetype
,
784 DECL_QUALIFIER (field
),
785 DECL_SIZE_UNIT (field
), rli
->offset
);
788 #if defined (PCC_BITFIELD_TYPE_MATTERS) || defined (BITFIELD_NBYTES_LIMITED)
789 /* A bitfield of SIZE with a required access alignment of ALIGN is allocated
790 at BYTE_OFFSET / BIT_OFFSET. Return nonzero if the field would span more
791 units of alignment than the underlying TYPE. */
793 excess_unit_span (HOST_WIDE_INT byte_offset
, HOST_WIDE_INT bit_offset
,
794 HOST_WIDE_INT size
, HOST_WIDE_INT align
, tree type
)
796 /* Note that the calculation of OFFSET might overflow; we calculate it so
797 that we still get the right result as long as ALIGN is a power of two. */
798 unsigned HOST_WIDE_INT offset
= byte_offset
* BITS_PER_UNIT
+ bit_offset
;
800 offset
= offset
% align
;
801 return ((offset
+ size
+ align
- 1) / align
802 > ((unsigned HOST_WIDE_INT
) tree_low_cst (TYPE_SIZE (type
), 1)
807 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
808 is a FIELD_DECL to be added after those fields already present in
809 T. (FIELD is not actually added to the TYPE_FIELDS list here;
810 callers that desire that behavior must manually perform that step.) */
813 place_field (record_layout_info rli
, tree field
)
815 /* The alignment required for FIELD. */
816 unsigned int desired_align
;
817 /* The alignment FIELD would have if we just dropped it into the
818 record as it presently stands. */
819 unsigned int known_align
;
820 unsigned int actual_align
;
821 /* The type of this field. */
822 tree type
= TREE_TYPE (field
);
824 gcc_assert (TREE_CODE (field
) != ERROR_MARK
);
826 if (TREE_CODE (type
) == ERROR_MARK
)
828 if (TREE_CODE (field
) == FIELD_DECL
)
830 DECL_FIELD_OFFSET (field
) = size_int (0);
831 DECL_FIELD_BIT_OFFSET (field
) = bitsize_int (0);
837 /* If FIELD is static, then treat it like a separate variable, not
838 really like a structure field. If it is a FUNCTION_DECL, it's a
839 method. In both cases, all we do is lay out the decl, and we do
840 it *after* the record is laid out. */
841 if (TREE_CODE (field
) == VAR_DECL
)
843 rli
->pending_statics
= tree_cons (NULL_TREE
, field
,
844 rli
->pending_statics
);
848 /* Enumerators and enum types which are local to this class need not
849 be laid out. Likewise for initialized constant fields. */
850 else if (TREE_CODE (field
) != FIELD_DECL
)
853 /* Unions are laid out very differently than records, so split
854 that code off to another function. */
855 else if (TREE_CODE (rli
->t
) != RECORD_TYPE
)
857 place_union_field (rli
, field
);
861 /* Work out the known alignment so far. Note that A & (-A) is the
862 value of the least-significant bit in A that is one. */
863 if (! integer_zerop (rli
->bitpos
))
864 known_align
= (tree_low_cst (rli
->bitpos
, 1)
865 & - tree_low_cst (rli
->bitpos
, 1));
866 else if (integer_zerop (rli
->offset
))
868 else if (host_integerp (rli
->offset
, 1))
869 known_align
= (BITS_PER_UNIT
870 * (tree_low_cst (rli
->offset
, 1)
871 & - tree_low_cst (rli
->offset
, 1)));
873 known_align
= rli
->offset_align
;
875 desired_align
= update_alignment_for_field (rli
, field
, known_align
);
876 if (known_align
== 0)
877 known_align
= MAX (BIGGEST_ALIGNMENT
, rli
->record_align
);
879 if (warn_packed
&& DECL_PACKED (field
))
881 if (known_align
>= TYPE_ALIGN (type
))
883 if (TYPE_ALIGN (type
) > desired_align
)
885 if (STRICT_ALIGNMENT
)
886 warning (OPT_Wattributes
, "packed attribute causes "
887 "inefficient alignment for %q+D", field
);
889 warning (OPT_Wattributes
, "packed attribute is "
890 "unnecessary for %q+D", field
);
894 rli
->packed_maybe_necessary
= 1;
897 /* Does this field automatically have alignment it needs by virtue
898 of the fields that precede it and the record's own alignment? */
899 if (known_align
< desired_align
)
901 /* No, we need to skip space before this field.
902 Bump the cumulative size to multiple of field alignment. */
904 warning (OPT_Wpadded
, "padding struct to align %q+D", field
);
906 /* If the alignment is still within offset_align, just align
908 if (desired_align
< rli
->offset_align
)
909 rli
->bitpos
= round_up (rli
->bitpos
, desired_align
);
912 /* First adjust OFFSET by the partial bits, then align. */
914 = size_binop (PLUS_EXPR
, rli
->offset
,
915 fold_convert (sizetype
,
916 size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
917 bitsize_unit_node
)));
918 rli
->bitpos
= bitsize_zero_node
;
920 rli
->offset
= round_up (rli
->offset
, desired_align
/ BITS_PER_UNIT
);
923 if (! TREE_CONSTANT (rli
->offset
))
924 rli
->offset_align
= desired_align
;
928 /* Handle compatibility with PCC. Note that if the record has any
929 variable-sized fields, we need not worry about compatibility. */
930 #ifdef PCC_BITFIELD_TYPE_MATTERS
931 if (PCC_BITFIELD_TYPE_MATTERS
932 && ! targetm
.ms_bitfield_layout_p (rli
->t
)
933 && TREE_CODE (field
) == FIELD_DECL
934 && type
!= error_mark_node
935 && DECL_BIT_FIELD (field
)
936 && ! DECL_PACKED (field
)
937 && maximum_field_alignment
== 0
938 && ! integer_zerop (DECL_SIZE (field
))
939 && host_integerp (DECL_SIZE (field
), 1)
940 && host_integerp (rli
->offset
, 1)
941 && host_integerp (TYPE_SIZE (type
), 1))
943 unsigned int type_align
= TYPE_ALIGN (type
);
944 tree dsize
= DECL_SIZE (field
);
945 HOST_WIDE_INT field_size
= tree_low_cst (dsize
, 1);
946 HOST_WIDE_INT offset
= tree_low_cst (rli
->offset
, 0);
947 HOST_WIDE_INT bit_offset
= tree_low_cst (rli
->bitpos
, 0);
949 #ifdef ADJUST_FIELD_ALIGN
950 if (! TYPE_USER_ALIGN (type
))
951 type_align
= ADJUST_FIELD_ALIGN (field
, type_align
);
954 /* A bit field may not span more units of alignment of its type
955 than its type itself. Advance to next boundary if necessary. */
956 if (excess_unit_span (offset
, bit_offset
, field_size
, type_align
, type
))
957 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
959 TYPE_USER_ALIGN (rli
->t
) |= TYPE_USER_ALIGN (type
);
963 #ifdef BITFIELD_NBYTES_LIMITED
964 if (BITFIELD_NBYTES_LIMITED
965 && ! targetm
.ms_bitfield_layout_p (rli
->t
)
966 && TREE_CODE (field
) == FIELD_DECL
967 && type
!= error_mark_node
968 && DECL_BIT_FIELD_TYPE (field
)
969 && ! DECL_PACKED (field
)
970 && ! integer_zerop (DECL_SIZE (field
))
971 && host_integerp (DECL_SIZE (field
), 1)
972 && host_integerp (rli
->offset
, 1)
973 && host_integerp (TYPE_SIZE (type
), 1))
975 unsigned int type_align
= TYPE_ALIGN (type
);
976 tree dsize
= DECL_SIZE (field
);
977 HOST_WIDE_INT field_size
= tree_low_cst (dsize
, 1);
978 HOST_WIDE_INT offset
= tree_low_cst (rli
->offset
, 0);
979 HOST_WIDE_INT bit_offset
= tree_low_cst (rli
->bitpos
, 0);
981 #ifdef ADJUST_FIELD_ALIGN
982 if (! TYPE_USER_ALIGN (type
))
983 type_align
= ADJUST_FIELD_ALIGN (field
, type_align
);
986 if (maximum_field_alignment
!= 0)
987 type_align
= MIN (type_align
, maximum_field_alignment
);
988 /* ??? This test is opposite the test in the containing if
989 statement, so this code is unreachable currently. */
990 else if (DECL_PACKED (field
))
991 type_align
= MIN (type_align
, BITS_PER_UNIT
);
993 /* A bit field may not span the unit of alignment of its type.
994 Advance to next boundary if necessary. */
995 if (excess_unit_span (offset
, bit_offset
, field_size
, type_align
, type
))
996 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
998 TYPE_USER_ALIGN (rli
->t
) |= TYPE_USER_ALIGN (type
);
1002 /* See the docs for TARGET_MS_BITFIELD_LAYOUT_P for details.
1004 When a bit field is inserted into a packed record, the whole
1005 size of the underlying type is used by one or more same-size
1006 adjacent bitfields. (That is, if its long:3, 32 bits is
1007 used in the record, and any additional adjacent long bitfields are
1008 packed into the same chunk of 32 bits. However, if the size
1009 changes, a new field of that size is allocated.) In an unpacked
1010 record, this is the same as using alignment, but not equivalent
1013 Note: for compatibility, we use the type size, not the type alignment
1014 to determine alignment, since that matches the documentation */
1016 if (targetm
.ms_bitfield_layout_p (rli
->t
)
1017 && ((DECL_BIT_FIELD_TYPE (field
) && ! DECL_PACKED (field
))
1018 || (rli
->prev_field
&& ! DECL_PACKED (rli
->prev_field
))))
1020 /* At this point, either the prior or current are bitfields,
1021 (possibly both), and we're dealing with MS packing. */
1022 tree prev_saved
= rli
->prev_field
;
1024 /* Is the prior field a bitfield? If so, handle "runs" of same
1025 type size fields. */
1026 if (rli
->prev_field
/* necessarily a bitfield if it exists. */)
1028 /* If both are bitfields, nonzero, and the same size, this is
1029 the middle of a run. Zero declared size fields are special
1030 and handled as "end of run". (Note: it's nonzero declared
1031 size, but equal type sizes!) (Since we know that both
1032 the current and previous fields are bitfields by the
1033 time we check it, DECL_SIZE must be present for both.) */
1034 if (DECL_BIT_FIELD_TYPE (field
)
1035 && !integer_zerop (DECL_SIZE (field
))
1036 && !integer_zerop (DECL_SIZE (rli
->prev_field
))
1037 && host_integerp (DECL_SIZE (rli
->prev_field
), 0)
1038 && host_integerp (TYPE_SIZE (type
), 0)
1039 && simple_cst_equal (TYPE_SIZE (type
),
1040 TYPE_SIZE (TREE_TYPE (rli
->prev_field
))))
1042 /* We're in the middle of a run of equal type size fields; make
1043 sure we realign if we run out of bits. (Not decl size,
1045 HOST_WIDE_INT bitsize
= tree_low_cst (DECL_SIZE (field
), 0);
1047 if (rli
->remaining_in_alignment
< bitsize
)
1049 /* If PREV_FIELD is packed, and we haven't lumped
1050 non-packed bitfields with it, treat this as if PREV_FIELD
1051 was not a bitfield. This avoids anomalies where a packed
1052 bitfield with long long base type can take up more
1053 space than a same-size bitfield with base type short. */
1054 if (rli
->prev_packed
)
1055 rli
->prev_field
= prev_saved
= NULL
;
1058 /* out of bits; bump up to next 'word'. */
1059 rli
->offset
= DECL_FIELD_OFFSET (rli
->prev_field
);
1061 = size_binop (PLUS_EXPR
, TYPE_SIZE (type
),
1062 DECL_FIELD_BIT_OFFSET (rli
->prev_field
));
1063 rli
->prev_field
= field
;
1064 rli
->remaining_in_alignment
1065 = tree_low_cst (TYPE_SIZE (type
), 0) - bitsize
;
1069 rli
->remaining_in_alignment
-= bitsize
;
1071 else if (rli
->prev_packed
)
1072 rli
->prev_field
= prev_saved
= NULL
;
1075 /* End of a run: if leaving a run of bitfields of the same type
1076 size, we have to "use up" the rest of the bits of the type
1079 Compute the new position as the sum of the size for the prior
1080 type and where we first started working on that type.
1081 Note: since the beginning of the field was aligned then
1082 of course the end will be too. No round needed. */
1084 if (!integer_zerop (DECL_SIZE (rli
->prev_field
)))
1086 tree type_size
= TYPE_SIZE (TREE_TYPE (rli
->prev_field
));
1088 /* If the desired alignment is greater or equal to TYPE_SIZE,
1089 we have already adjusted rli->bitpos / rli->offset above.
1091 if ((unsigned HOST_WIDE_INT
) tree_low_cst (type_size
, 0)
1094 = size_binop (PLUS_EXPR
, type_size
,
1095 DECL_FIELD_BIT_OFFSET (rli
->prev_field
));
1098 /* We "use up" size zero fields; the code below should behave
1099 as if the prior field was not a bitfield. */
1102 /* Cause a new bitfield to be captured, either this time (if
1103 currently a bitfield) or next time we see one. */
1104 if (!DECL_BIT_FIELD_TYPE(field
)
1105 || integer_zerop (DECL_SIZE (field
)))
1106 rli
->prev_field
= NULL
;
1109 rli
->prev_packed
= 0;
1110 normalize_rli (rli
);
1113 /* If we're starting a new run of same size type bitfields
1114 (or a run of non-bitfields), set up the "first of the run"
1117 That is, if the current field is not a bitfield, or if there
1118 was a prior bitfield the type sizes differ, or if there wasn't
1119 a prior bitfield the size of the current field is nonzero.
1121 Note: we must be sure to test ONLY the type size if there was
1122 a prior bitfield and ONLY for the current field being zero if
1125 if (!DECL_BIT_FIELD_TYPE (field
)
1126 || ( prev_saved
!= NULL
1127 ? !simple_cst_equal (TYPE_SIZE (type
),
1128 TYPE_SIZE (TREE_TYPE (prev_saved
)))
1129 : !integer_zerop (DECL_SIZE (field
)) ))
1131 /* Never smaller than a byte for compatibility. */
1132 unsigned int type_align
= BITS_PER_UNIT
;
1134 /* (When not a bitfield), we could be seeing a flex array (with
1135 no DECL_SIZE). Since we won't be using remaining_in_alignment
1136 until we see a bitfield (and come by here again) we just skip
1138 if (DECL_SIZE (field
) != NULL
1139 && host_integerp (TYPE_SIZE (TREE_TYPE (field
)), 0)
1140 && host_integerp (DECL_SIZE (field
), 0))
1141 rli
->remaining_in_alignment
1142 = tree_low_cst (TYPE_SIZE (TREE_TYPE(field
)), 0)
1143 - tree_low_cst (DECL_SIZE (field
), 0);
1145 /* Now align (conventionally) for the new type. */
1146 if (!DECL_PACKED(field
))
1147 type_align
= MAX(TYPE_ALIGN (type
), type_align
);
1150 && DECL_BIT_FIELD_TYPE (prev_saved
)
1151 /* If the previous bit-field is zero-sized, we've already
1152 accounted for its alignment needs (or ignored it, if
1153 appropriate) while placing it. */
1154 && ! integer_zerop (DECL_SIZE (prev_saved
)))
1155 type_align
= MAX (type_align
,
1156 TYPE_ALIGN (TREE_TYPE (prev_saved
)));
1158 if (maximum_field_alignment
!= 0)
1159 type_align
= MIN (type_align
, maximum_field_alignment
);
1161 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1163 /* If we really aligned, don't allow subsequent bitfields
1165 rli
->prev_field
= NULL
;
1169 /* Offset so far becomes the position of this field after normalizing. */
1170 normalize_rli (rli
);
1171 DECL_FIELD_OFFSET (field
) = rli
->offset
;
1172 DECL_FIELD_BIT_OFFSET (field
) = rli
->bitpos
;
1173 SET_DECL_OFFSET_ALIGN (field
, rli
->offset_align
);
1175 /* If this field ended up more aligned than we thought it would be (we
1176 approximate this by seeing if its position changed), lay out the field
1177 again; perhaps we can use an integral mode for it now. */
1178 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field
)))
1179 actual_align
= (tree_low_cst (DECL_FIELD_BIT_OFFSET (field
), 1)
1180 & - tree_low_cst (DECL_FIELD_BIT_OFFSET (field
), 1));
1181 else if (integer_zerop (DECL_FIELD_OFFSET (field
)))
1182 actual_align
= MAX (BIGGEST_ALIGNMENT
, rli
->record_align
);
1183 else if (host_integerp (DECL_FIELD_OFFSET (field
), 1))
1184 actual_align
= (BITS_PER_UNIT
1185 * (tree_low_cst (DECL_FIELD_OFFSET (field
), 1)
1186 & - tree_low_cst (DECL_FIELD_OFFSET (field
), 1)));
1188 actual_align
= DECL_OFFSET_ALIGN (field
);
1189 /* ACTUAL_ALIGN is still the actual alignment *within the record* .
1190 store / extract bit field operations will check the alignment of the
1191 record against the mode of bit fields. */
1193 if (known_align
!= actual_align
)
1194 layout_decl (field
, actual_align
);
1196 if (DECL_BIT_FIELD_TYPE (field
))
1198 unsigned int type_align
= TYPE_ALIGN (type
);
1199 unsigned int mfa
= maximum_field_alignment
;
1201 if (integer_zerop (DECL_SIZE (field
)))
1202 mfa
= initial_max_fld_align
* BITS_PER_UNIT
;
1204 /* Only the MS bitfields use this. We used to also put any kind of
1205 packed bit fields into prev_field, but that makes no sense, because
1206 an 8 bit packed bit field shouldn't impose more restriction on
1207 following fields than a char field, and the alignment requirements
1208 are also not fulfilled.
1209 There is no sane value to set rli->remaining_in_alignment to when
1210 a packed bitfield in prev_field is unaligned. */
1212 type_align
= MIN (type_align
, mfa
);
1213 gcc_assert (rli
->prev_field
1214 || actual_align
>= type_align
|| DECL_PACKED (field
)
1215 || integer_zerop (DECL_SIZE (field
))
1216 || !targetm
.ms_bitfield_layout_p (rli
->t
));
1217 if (rli
->prev_field
== NULL
&& actual_align
>= type_align
1218 && !integer_zerop (DECL_SIZE (field
)))
1220 rli
->prev_field
= field
;
1221 /* rli->remaining_in_alignment has not been set if the bitfield
1222 has size zero, or if it is a packed bitfield. */
1223 rli
->remaining_in_alignment
1224 = (tree_low_cst (TYPE_SIZE (TREE_TYPE (field
)), 0)
1225 - tree_low_cst (DECL_SIZE (field
), 0));
1226 rli
->prev_packed
= DECL_PACKED (field
);
1229 else if (rli
->prev_field
&& DECL_PACKED (field
))
1231 HOST_WIDE_INT bitsize
= tree_low_cst (DECL_SIZE (field
), 0);
1233 if (rli
->remaining_in_alignment
< bitsize
)
1234 rli
->prev_field
= NULL
;
1236 rli
->remaining_in_alignment
-= bitsize
;
1240 /* Now add size of this field to the size of the record. If the size is
1241 not constant, treat the field as being a multiple of bytes and just
1242 adjust the offset, resetting the bit position. Otherwise, apportion the
1243 size amongst the bit position and offset. First handle the case of an
1244 unspecified size, which can happen when we have an invalid nested struct
1245 definition, such as struct j { struct j { int i; } }. The error message
1246 is printed in finish_struct. */
1247 if (DECL_SIZE (field
) == 0)
1249 else if (TREE_CODE (DECL_SIZE (field
)) != INTEGER_CST
1250 || TREE_CONSTANT_OVERFLOW (DECL_SIZE (field
)))
1253 = size_binop (PLUS_EXPR
, rli
->offset
,
1254 fold_convert (sizetype
,
1255 size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
1256 bitsize_unit_node
)));
1258 = size_binop (PLUS_EXPR
, rli
->offset
, DECL_SIZE_UNIT (field
));
1259 rli
->bitpos
= bitsize_zero_node
;
1260 rli
->offset_align
= MIN (rli
->offset_align
, desired_align
);
1264 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
, DECL_SIZE (field
));
1265 normalize_rli (rli
);
1269 /* Assuming that all the fields have been laid out, this function uses
1270 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
1271 indicated by RLI. */
1274 finalize_record_size (record_layout_info rli
)
1276 tree unpadded_size
, unpadded_size_unit
;
1278 /* Now we want just byte and bit offsets, so set the offset alignment
1279 to be a byte and then normalize. */
1280 rli
->offset_align
= BITS_PER_UNIT
;
1281 normalize_rli (rli
);
1283 /* Determine the desired alignment. */
1284 #ifdef ROUND_TYPE_ALIGN
1285 TYPE_ALIGN (rli
->t
) = ROUND_TYPE_ALIGN (rli
->t
, TYPE_ALIGN (rli
->t
),
1288 TYPE_ALIGN (rli
->t
) = MAX (TYPE_ALIGN (rli
->t
), rli
->record_align
);
1291 /* Compute the size so far. Be sure to allow for extra bits in the
1292 size in bytes. We have guaranteed above that it will be no more
1293 than a single byte. */
1294 unpadded_size
= rli_size_so_far (rli
);
1295 unpadded_size_unit
= rli_size_unit_so_far (rli
);
1296 if (! integer_zerop (rli
->bitpos
))
1298 = size_binop (PLUS_EXPR
, unpadded_size_unit
, size_one_node
);
1300 /* Round the size up to be a multiple of the required alignment. */
1301 TYPE_SIZE (rli
->t
) = round_up (unpadded_size
, TYPE_ALIGN (rli
->t
));
1302 TYPE_SIZE_UNIT (rli
->t
)
1303 = round_up (unpadded_size_unit
, TYPE_ALIGN_UNIT (rli
->t
));
1305 if (TREE_CONSTANT (unpadded_size
)
1306 && simple_cst_equal (unpadded_size
, TYPE_SIZE (rli
->t
)) == 0)
1307 warning (OPT_Wpadded
, "padding struct size to alignment boundary");
1309 if (warn_packed
&& TREE_CODE (rli
->t
) == RECORD_TYPE
1310 && TYPE_PACKED (rli
->t
) && ! rli
->packed_maybe_necessary
1311 && TREE_CONSTANT (unpadded_size
))
1315 #ifdef ROUND_TYPE_ALIGN
1317 = ROUND_TYPE_ALIGN (rli
->t
, TYPE_ALIGN (rli
->t
), rli
->unpacked_align
);
1319 rli
->unpacked_align
= MAX (TYPE_ALIGN (rli
->t
), rli
->unpacked_align
);
1322 unpacked_size
= round_up (TYPE_SIZE (rli
->t
), rli
->unpacked_align
);
1323 if (simple_cst_equal (unpacked_size
, TYPE_SIZE (rli
->t
)))
1325 TYPE_PACKED (rli
->t
) = 0;
1327 if (TYPE_NAME (rli
->t
))
1331 if (TREE_CODE (TYPE_NAME (rli
->t
)) == IDENTIFIER_NODE
)
1332 name
= IDENTIFIER_POINTER (TYPE_NAME (rli
->t
));
1334 name
= IDENTIFIER_POINTER (DECL_NAME (TYPE_NAME (rli
->t
)));
1336 if (STRICT_ALIGNMENT
)
1337 warning (OPT_Wpacked
, "packed attribute causes inefficient "
1338 "alignment for %qs", name
);
1340 warning (OPT_Wpacked
,
1341 "packed attribute is unnecessary for %qs", name
);
1345 if (STRICT_ALIGNMENT
)
1346 warning (OPT_Wpacked
,
1347 "packed attribute causes inefficient alignment");
1349 warning (OPT_Wpacked
, "packed attribute is unnecessary");
1355 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
1358 compute_record_mode (tree type
)
1361 enum machine_mode mode
= VOIDmode
;
1363 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
1364 However, if possible, we use a mode that fits in a register
1365 instead, in order to allow for better optimization down the
1367 TYPE_MODE (type
) = BLKmode
;
1369 if (! host_integerp (TYPE_SIZE (type
), 1))
1372 /* A record which has any BLKmode members must itself be
1373 BLKmode; it can't go in a register. Unless the member is
1374 BLKmode only because it isn't aligned. */
1375 for (field
= TYPE_FIELDS (type
); field
; field
= TREE_CHAIN (field
))
1377 if (TREE_CODE (field
) != FIELD_DECL
)
1380 if (TREE_CODE (TREE_TYPE (field
)) == ERROR_MARK
1381 || (TYPE_MODE (TREE_TYPE (field
)) == BLKmode
1382 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field
))
1383 && !(TYPE_SIZE (TREE_TYPE (field
)) != 0
1384 && integer_zerop (TYPE_SIZE (TREE_TYPE (field
)))))
1385 || ! host_integerp (bit_position (field
), 1)
1386 || DECL_SIZE (field
) == 0
1387 || ! host_integerp (DECL_SIZE (field
), 1))
1390 /* If this field is the whole struct, remember its mode so
1391 that, say, we can put a double in a class into a DF
1392 register instead of forcing it to live in the stack. */
1393 if (simple_cst_equal (TYPE_SIZE (type
), DECL_SIZE (field
)))
1394 mode
= DECL_MODE (field
);
1396 #ifdef MEMBER_TYPE_FORCES_BLK
1397 /* With some targets, eg. c4x, it is sub-optimal
1398 to access an aligned BLKmode structure as a scalar. */
1400 if (MEMBER_TYPE_FORCES_BLK (field
, mode
))
1402 #endif /* MEMBER_TYPE_FORCES_BLK */
1405 /* If we only have one real field; use its mode if that mode's size
1406 matches the type's size. This only applies to RECORD_TYPE. This
1407 does not apply to unions. */
1408 if (TREE_CODE (type
) == RECORD_TYPE
&& mode
!= VOIDmode
1409 && host_integerp (TYPE_SIZE (type
), 1)
1410 && GET_MODE_BITSIZE (mode
) == TREE_INT_CST_LOW (TYPE_SIZE (type
)))
1411 TYPE_MODE (type
) = mode
;
1413 TYPE_MODE (type
) = mode_for_size_tree (TYPE_SIZE (type
), MODE_INT
, 1);
1415 /* If structure's known alignment is less than what the scalar
1416 mode would need, and it matters, then stick with BLKmode. */
1417 if (TYPE_MODE (type
) != BLKmode
1419 && ! (TYPE_ALIGN (type
) >= BIGGEST_ALIGNMENT
1420 || TYPE_ALIGN (type
) >= GET_MODE_ALIGNMENT (TYPE_MODE (type
))))
1422 /* If this is the only reason this type is BLKmode, then
1423 don't force containing types to be BLKmode. */
1424 TYPE_NO_FORCE_BLK (type
) = 1;
1425 TYPE_MODE (type
) = BLKmode
;
1429 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1433 finalize_type_size (tree type
)
1435 /* Normally, use the alignment corresponding to the mode chosen.
1436 However, where strict alignment is not required, avoid
1437 over-aligning structures, since most compilers do not do this
1440 if (TYPE_MODE (type
) != BLKmode
&& TYPE_MODE (type
) != VOIDmode
1441 && (STRICT_ALIGNMENT
1442 || (TREE_CODE (type
) != RECORD_TYPE
&& TREE_CODE (type
) != UNION_TYPE
1443 && TREE_CODE (type
) != QUAL_UNION_TYPE
1444 && TREE_CODE (type
) != ARRAY_TYPE
)))
1446 unsigned mode_align
= GET_MODE_ALIGNMENT (TYPE_MODE (type
));
1448 /* Don't override a larger alignment requirement coming from a user
1449 alignment of one of the fields. */
1450 if (mode_align
>= TYPE_ALIGN (type
))
1452 TYPE_ALIGN (type
) = mode_align
;
1453 TYPE_USER_ALIGN (type
) = 0;
1457 /* Do machine-dependent extra alignment. */
1458 #ifdef ROUND_TYPE_ALIGN
1460 = ROUND_TYPE_ALIGN (type
, TYPE_ALIGN (type
), BITS_PER_UNIT
);
1463 /* If we failed to find a simple way to calculate the unit size
1464 of the type, find it by division. */
1465 if (TYPE_SIZE_UNIT (type
) == 0 && TYPE_SIZE (type
) != 0)
1466 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1467 result will fit in sizetype. We will get more efficient code using
1468 sizetype, so we force a conversion. */
1469 TYPE_SIZE_UNIT (type
)
1470 = fold_convert (sizetype
,
1471 size_binop (FLOOR_DIV_EXPR
, TYPE_SIZE (type
),
1472 bitsize_unit_node
));
1474 if (TYPE_SIZE (type
) != 0)
1476 TYPE_SIZE (type
) = round_up (TYPE_SIZE (type
), TYPE_ALIGN (type
));
1477 TYPE_SIZE_UNIT (type
) = round_up (TYPE_SIZE_UNIT (type
),
1478 TYPE_ALIGN_UNIT (type
));
1481 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1482 if (TYPE_SIZE (type
) != 0 && TREE_CODE (TYPE_SIZE (type
)) != INTEGER_CST
)
1483 TYPE_SIZE (type
) = variable_size (TYPE_SIZE (type
));
1484 if (TYPE_SIZE_UNIT (type
) != 0
1485 && TREE_CODE (TYPE_SIZE_UNIT (type
)) != INTEGER_CST
)
1486 TYPE_SIZE_UNIT (type
) = variable_size (TYPE_SIZE_UNIT (type
));
1488 /* Also layout any other variants of the type. */
1489 if (TYPE_NEXT_VARIANT (type
)
1490 || type
!= TYPE_MAIN_VARIANT (type
))
1493 /* Record layout info of this variant. */
1494 tree size
= TYPE_SIZE (type
);
1495 tree size_unit
= TYPE_SIZE_UNIT (type
);
1496 unsigned int align
= TYPE_ALIGN (type
);
1497 unsigned int user_align
= TYPE_USER_ALIGN (type
);
1498 enum machine_mode mode
= TYPE_MODE (type
);
1500 /* Copy it into all variants. */
1501 for (variant
= TYPE_MAIN_VARIANT (type
);
1503 variant
= TYPE_NEXT_VARIANT (variant
))
1505 TYPE_SIZE (variant
) = size
;
1506 TYPE_SIZE_UNIT (variant
) = size_unit
;
1507 TYPE_ALIGN (variant
) = align
;
1508 TYPE_USER_ALIGN (variant
) = user_align
;
1509 TYPE_MODE (variant
) = mode
;
1514 /* Do all of the work required to layout the type indicated by RLI,
1515 once the fields have been laid out. This function will call `free'
1516 for RLI, unless FREE_P is false. Passing a value other than false
1517 for FREE_P is bad practice; this option only exists to support the
1521 finish_record_layout (record_layout_info rli
, int free_p
)
1523 /* Compute the final size. */
1524 finalize_record_size (rli
);
1526 /* Compute the TYPE_MODE for the record. */
1527 compute_record_mode (rli
->t
);
1529 /* Perform any last tweaks to the TYPE_SIZE, etc. */
1530 finalize_type_size (rli
->t
);
1532 /* Lay out any static members. This is done now because their type
1533 may use the record's type. */
1534 while (rli
->pending_statics
)
1536 layout_decl (TREE_VALUE (rli
->pending_statics
), 0);
1537 rli
->pending_statics
= TREE_CHAIN (rli
->pending_statics
);
1546 /* Finish processing a builtin RECORD_TYPE type TYPE. It's name is
1547 NAME, its fields are chained in reverse on FIELDS.
1549 If ALIGN_TYPE is non-null, it is given the same alignment as
1553 finish_builtin_struct (tree type
, const char *name
, tree fields
,
1558 for (tail
= NULL_TREE
; fields
; tail
= fields
, fields
= next
)
1560 DECL_FIELD_CONTEXT (fields
) = type
;
1561 next
= TREE_CHAIN (fields
);
1562 TREE_CHAIN (fields
) = tail
;
1564 TYPE_FIELDS (type
) = tail
;
1568 TYPE_ALIGN (type
) = TYPE_ALIGN (align_type
);
1569 TYPE_USER_ALIGN (type
) = TYPE_USER_ALIGN (align_type
);
1573 #if 0 /* not yet, should get fixed properly later */
1574 TYPE_NAME (type
) = make_type_decl (get_identifier (name
), type
);
1576 TYPE_NAME (type
) = build_decl (TYPE_DECL
, get_identifier (name
), type
);
1578 TYPE_STUB_DECL (type
) = TYPE_NAME (type
);
1579 layout_decl (TYPE_NAME (type
), 0);
1582 /* Calculate the mode, size, and alignment for TYPE.
1583 For an array type, calculate the element separation as well.
1584 Record TYPE on the chain of permanent or temporary types
1585 so that dbxout will find out about it.
1587 TYPE_SIZE of a type is nonzero if the type has been laid out already.
1588 layout_type does nothing on such a type.
1590 If the type is incomplete, its TYPE_SIZE remains zero. */
1593 layout_type (tree type
)
1597 if (type
== error_mark_node
)
1600 /* Do nothing if type has been laid out before. */
1601 if (TYPE_SIZE (type
))
1604 switch (TREE_CODE (type
))
1607 /* This kind of type is the responsibility
1608 of the language-specific code. */
1611 case BOOLEAN_TYPE
: /* Used for Java, Pascal, and Chill. */
1612 if (TYPE_PRECISION (type
) == 0)
1613 TYPE_PRECISION (type
) = 1; /* default to one byte/boolean. */
1615 /* ... fall through ... */
1619 if (TREE_CODE (TYPE_MIN_VALUE (type
)) == INTEGER_CST
1620 && tree_int_cst_sgn (TYPE_MIN_VALUE (type
)) >= 0)
1621 TYPE_UNSIGNED (type
) = 1;
1623 TYPE_MODE (type
) = smallest_mode_for_size (TYPE_PRECISION (type
),
1625 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
1626 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
1630 TYPE_MODE (type
) = mode_for_size (TYPE_PRECISION (type
), MODE_FLOAT
, 0);
1631 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
1632 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
1636 TYPE_UNSIGNED (type
) = TYPE_UNSIGNED (TREE_TYPE (type
));
1638 = mode_for_size (2 * TYPE_PRECISION (TREE_TYPE (type
)),
1639 (TREE_CODE (TREE_TYPE (type
)) == REAL_TYPE
1640 ? MODE_COMPLEX_FLOAT
: MODE_COMPLEX_INT
),
1642 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
1643 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
1648 int nunits
= TYPE_VECTOR_SUBPARTS (type
);
1649 tree nunits_tree
= build_int_cst (NULL_TREE
, nunits
);
1650 tree innertype
= TREE_TYPE (type
);
1652 gcc_assert (!(nunits
& (nunits
- 1)));
1654 /* Find an appropriate mode for the vector type. */
1655 if (TYPE_MODE (type
) == VOIDmode
)
1657 enum machine_mode innermode
= TYPE_MODE (innertype
);
1658 enum machine_mode mode
;
1660 /* First, look for a supported vector type. */
1661 if (SCALAR_FLOAT_MODE_P (innermode
))
1662 mode
= MIN_MODE_VECTOR_FLOAT
;
1664 mode
= MIN_MODE_VECTOR_INT
;
1666 for (; mode
!= VOIDmode
; mode
= GET_MODE_WIDER_MODE (mode
))
1667 if (GET_MODE_NUNITS (mode
) == nunits
1668 && GET_MODE_INNER (mode
) == innermode
1669 && targetm
.vector_mode_supported_p (mode
))
1672 /* For integers, try mapping it to a same-sized scalar mode. */
1673 if (mode
== VOIDmode
1674 && GET_MODE_CLASS (innermode
) == MODE_INT
)
1675 mode
= mode_for_size (nunits
* GET_MODE_BITSIZE (innermode
),
1678 if (mode
== VOIDmode
|| !have_regs_of_mode
[mode
])
1679 TYPE_MODE (type
) = BLKmode
;
1681 TYPE_MODE (type
) = mode
;
1684 TYPE_UNSIGNED (type
) = TYPE_UNSIGNED (TREE_TYPE (type
));
1685 TYPE_SIZE_UNIT (type
) = int_const_binop (MULT_EXPR
,
1686 TYPE_SIZE_UNIT (innertype
),
1688 TYPE_SIZE (type
) = int_const_binop (MULT_EXPR
, TYPE_SIZE (innertype
),
1691 /* Always naturally align vectors. This prevents ABI changes
1692 depending on whether or not native vector modes are supported. */
1693 TYPE_ALIGN (type
) = tree_low_cst (TYPE_SIZE (type
), 0);
1698 /* This is an incomplete type and so doesn't have a size. */
1699 TYPE_ALIGN (type
) = 1;
1700 TYPE_USER_ALIGN (type
) = 0;
1701 TYPE_MODE (type
) = VOIDmode
;
1705 TYPE_SIZE (type
) = bitsize_int (POINTER_SIZE
);
1706 TYPE_SIZE_UNIT (type
) = size_int (POINTER_SIZE
/ BITS_PER_UNIT
);
1707 /* A pointer might be MODE_PARTIAL_INT,
1708 but ptrdiff_t must be integral. */
1709 TYPE_MODE (type
) = mode_for_size (POINTER_SIZE
, MODE_INT
, 0);
1714 /* It's hard to see what the mode and size of a function ought to
1715 be, but we do know the alignment is FUNCTION_BOUNDARY, so
1716 make it consistent with that. */
1717 TYPE_MODE (type
) = mode_for_size (FUNCTION_BOUNDARY
, MODE_INT
, 0);
1718 TYPE_SIZE (type
) = bitsize_int (FUNCTION_BOUNDARY
);
1719 TYPE_SIZE_UNIT (type
) = size_int (FUNCTION_BOUNDARY
/ BITS_PER_UNIT
);
1723 case REFERENCE_TYPE
:
1726 enum machine_mode mode
= ((TREE_CODE (type
) == REFERENCE_TYPE
1727 && reference_types_internal
)
1728 ? Pmode
: TYPE_MODE (type
));
1730 int nbits
= GET_MODE_BITSIZE (mode
);
1732 TYPE_SIZE (type
) = bitsize_int (nbits
);
1733 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
1734 TYPE_UNSIGNED (type
) = 1;
1735 TYPE_PRECISION (type
) = nbits
;
1741 tree index
= TYPE_DOMAIN (type
);
1742 tree element
= TREE_TYPE (type
);
1744 build_pointer_type (element
);
1746 /* We need to know both bounds in order to compute the size. */
1747 if (index
&& TYPE_MAX_VALUE (index
) && TYPE_MIN_VALUE (index
)
1748 && TYPE_SIZE (element
))
1750 tree ub
= TYPE_MAX_VALUE (index
);
1751 tree lb
= TYPE_MIN_VALUE (index
);
1755 /* The initial subtraction should happen in the original type so
1756 that (possible) negative values are handled appropriately. */
1757 length
= size_binop (PLUS_EXPR
, size_one_node
,
1758 fold_convert (sizetype
,
1759 fold_build2 (MINUS_EXPR
,
1763 /* Special handling for arrays of bits (for Chill). */
1764 element_size
= TYPE_SIZE (element
);
1765 if (TYPE_PACKED (type
) && INTEGRAL_TYPE_P (element
)
1766 && (integer_zerop (TYPE_MAX_VALUE (element
))
1767 || integer_onep (TYPE_MAX_VALUE (element
)))
1768 && host_integerp (TYPE_MIN_VALUE (element
), 1))
1770 HOST_WIDE_INT maxvalue
1771 = tree_low_cst (TYPE_MAX_VALUE (element
), 1);
1772 HOST_WIDE_INT minvalue
1773 = tree_low_cst (TYPE_MIN_VALUE (element
), 1);
1775 if (maxvalue
- minvalue
== 1
1776 && (maxvalue
== 1 || maxvalue
== 0))
1777 element_size
= integer_one_node
;
1780 /* If neither bound is a constant and sizetype is signed, make
1781 sure the size is never negative. We should really do this
1782 if *either* bound is non-constant, but this is the best
1783 compromise between C and Ada. */
1784 if (!TYPE_UNSIGNED (sizetype
)
1785 && TREE_CODE (TYPE_MIN_VALUE (index
)) != INTEGER_CST
1786 && TREE_CODE (TYPE_MAX_VALUE (index
)) != INTEGER_CST
)
1787 length
= size_binop (MAX_EXPR
, length
, size_zero_node
);
1789 TYPE_SIZE (type
) = size_binop (MULT_EXPR
, element_size
,
1790 fold_convert (bitsizetype
,
1793 /* If we know the size of the element, calculate the total
1794 size directly, rather than do some division thing below.
1795 This optimization helps Fortran assumed-size arrays
1796 (where the size of the array is determined at runtime)
1798 Note that we can't do this in the case where the size of
1799 the elements is one bit since TYPE_SIZE_UNIT cannot be
1800 set correctly in that case. */
1801 if (TYPE_SIZE_UNIT (element
) != 0 && ! integer_onep (element_size
))
1802 TYPE_SIZE_UNIT (type
)
1803 = size_binop (MULT_EXPR
, TYPE_SIZE_UNIT (element
), length
);
1806 /* Now round the alignment and size,
1807 using machine-dependent criteria if any. */
1809 #ifdef ROUND_TYPE_ALIGN
1811 = ROUND_TYPE_ALIGN (type
, TYPE_ALIGN (element
), BITS_PER_UNIT
);
1813 TYPE_ALIGN (type
) = MAX (TYPE_ALIGN (element
), BITS_PER_UNIT
);
1815 TYPE_USER_ALIGN (type
) = TYPE_USER_ALIGN (element
);
1816 TYPE_MODE (type
) = BLKmode
;
1817 if (TYPE_SIZE (type
) != 0
1818 #ifdef MEMBER_TYPE_FORCES_BLK
1819 && ! MEMBER_TYPE_FORCES_BLK (type
, VOIDmode
)
1821 /* BLKmode elements force BLKmode aggregate;
1822 else extract/store fields may lose. */
1823 && (TYPE_MODE (TREE_TYPE (type
)) != BLKmode
1824 || TYPE_NO_FORCE_BLK (TREE_TYPE (type
))))
1826 /* One-element arrays get the component type's mode. */
1827 if (simple_cst_equal (TYPE_SIZE (type
),
1828 TYPE_SIZE (TREE_TYPE (type
))))
1829 TYPE_MODE (type
) = TYPE_MODE (TREE_TYPE (type
));
1832 = mode_for_size_tree (TYPE_SIZE (type
), MODE_INT
, 1);
1834 if (TYPE_MODE (type
) != BLKmode
1835 && STRICT_ALIGNMENT
&& TYPE_ALIGN (type
) < BIGGEST_ALIGNMENT
1836 && TYPE_ALIGN (type
) < GET_MODE_ALIGNMENT (TYPE_MODE (type
))
1837 && TYPE_MODE (type
) != BLKmode
)
1839 TYPE_NO_FORCE_BLK (type
) = 1;
1840 TYPE_MODE (type
) = BLKmode
;
1843 /* When the element size is constant, check that it is at least as
1844 large as the element alignment. */
1845 if (TYPE_SIZE_UNIT (element
)
1846 && TREE_CODE (TYPE_SIZE_UNIT (element
)) == INTEGER_CST
1847 /* If TYPE_SIZE_UNIT overflowed, then it is certainly larger than
1849 && !TREE_CONSTANT_OVERFLOW (TYPE_SIZE_UNIT (element
))
1850 && !integer_zerop (TYPE_SIZE_UNIT (element
))
1851 && compare_tree_int (TYPE_SIZE_UNIT (element
),
1852 TYPE_ALIGN_UNIT (element
)) < 0)
1853 error ("alignment of array elements is greater than element size");
1859 case QUAL_UNION_TYPE
:
1862 record_layout_info rli
;
1864 /* Initialize the layout information. */
1865 rli
= start_record_layout (type
);
1867 /* If this is a QUAL_UNION_TYPE, we want to process the fields
1868 in the reverse order in building the COND_EXPR that denotes
1869 its size. We reverse them again later. */
1870 if (TREE_CODE (type
) == QUAL_UNION_TYPE
)
1871 TYPE_FIELDS (type
) = nreverse (TYPE_FIELDS (type
));
1873 /* Place all the fields. */
1874 for (field
= TYPE_FIELDS (type
); field
; field
= TREE_CHAIN (field
))
1875 place_field (rli
, field
);
1877 if (TREE_CODE (type
) == QUAL_UNION_TYPE
)
1878 TYPE_FIELDS (type
) = nreverse (TYPE_FIELDS (type
));
1880 if (lang_adjust_rli
)
1881 (*lang_adjust_rli
) (rli
);
1883 /* Finish laying out the record. */
1884 finish_record_layout (rli
, /*free_p=*/true);
1892 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
1893 records and unions, finish_record_layout already called this
1895 if (TREE_CODE (type
) != RECORD_TYPE
1896 && TREE_CODE (type
) != UNION_TYPE
1897 && TREE_CODE (type
) != QUAL_UNION_TYPE
)
1898 finalize_type_size (type
);
1900 /* If an alias set has been set for this aggregate when it was incomplete,
1901 force it into alias set 0.
1902 This is too conservative, but we cannot call record_component_aliases
1903 here because some frontends still change the aggregates after
1905 if (AGGREGATE_TYPE_P (type
) && TYPE_ALIAS_SET_KNOWN_P (type
))
1906 TYPE_ALIAS_SET (type
) = 0;
1909 /* Create and return a type for signed integers of PRECISION bits. */
1912 make_signed_type (int precision
)
1914 tree type
= make_node (INTEGER_TYPE
);
1916 TYPE_PRECISION (type
) = precision
;
1918 fixup_signed_type (type
);
1922 /* Create and return a type for unsigned integers of PRECISION bits. */
1925 make_unsigned_type (int precision
)
1927 tree type
= make_node (INTEGER_TYPE
);
1929 TYPE_PRECISION (type
) = precision
;
1931 fixup_unsigned_type (type
);
1935 /* Initialize sizetype and bitsizetype to a reasonable and temporary
1936 value to enable integer types to be created. */
1939 initialize_sizetypes (bool signed_p
)
1941 tree t
= make_node (INTEGER_TYPE
);
1942 int precision
= GET_MODE_BITSIZE (SImode
);
1944 TYPE_MODE (t
) = SImode
;
1945 TYPE_ALIGN (t
) = GET_MODE_ALIGNMENT (SImode
);
1946 TYPE_USER_ALIGN (t
) = 0;
1947 TYPE_IS_SIZETYPE (t
) = 1;
1948 TYPE_UNSIGNED (t
) = !signed_p
;
1949 TYPE_SIZE (t
) = build_int_cst (t
, precision
);
1950 TYPE_SIZE_UNIT (t
) = build_int_cst (t
, GET_MODE_SIZE (SImode
));
1951 TYPE_PRECISION (t
) = precision
;
1953 /* Set TYPE_MIN_VALUE and TYPE_MAX_VALUE. */
1954 set_min_and_max_values_for_integral_type (t
, precision
, !signed_p
);
1957 bitsizetype
= build_distinct_type_copy (t
);
1960 /* Make sizetype a version of TYPE, and initialize *sizetype
1961 accordingly. We do this by overwriting the stub sizetype and
1962 bitsizetype nodes created by initialize_sizetypes. This makes sure
1963 that (a) anything stubby about them no longer exists, (b) any
1964 INTEGER_CSTs created with such a type, remain valid. */
1967 set_sizetype (tree type
)
1969 int oprecision
= TYPE_PRECISION (type
);
1970 /* The *bitsizetype types use a precision that avoids overflows when
1971 calculating signed sizes / offsets in bits. However, when
1972 cross-compiling from a 32 bit to a 64 bit host, we are limited to 64 bit
1974 int precision
= MIN (oprecision
+ BITS_PER_UNIT_LOG
+ 1,
1975 2 * HOST_BITS_PER_WIDE_INT
);
1978 gcc_assert (TYPE_UNSIGNED (type
) == TYPE_UNSIGNED (sizetype
));
1980 t
= build_distinct_type_copy (type
);
1981 /* We do want to use sizetype's cache, as we will be replacing that
1983 TYPE_CACHED_VALUES (t
) = TYPE_CACHED_VALUES (sizetype
);
1984 TYPE_CACHED_VALUES_P (t
) = TYPE_CACHED_VALUES_P (sizetype
);
1985 TREE_TYPE (TYPE_CACHED_VALUES (t
)) = type
;
1986 TYPE_UID (t
) = TYPE_UID (sizetype
);
1987 TYPE_IS_SIZETYPE (t
) = 1;
1989 /* Replace our original stub sizetype. */
1990 memcpy (sizetype
, t
, tree_size (sizetype
));
1991 TYPE_MAIN_VARIANT (sizetype
) = sizetype
;
1993 t
= make_node (INTEGER_TYPE
);
1994 TYPE_NAME (t
) = get_identifier ("bit_size_type");
1995 /* We do want to use bitsizetype's cache, as we will be replacing that
1997 TYPE_CACHED_VALUES (t
) = TYPE_CACHED_VALUES (bitsizetype
);
1998 TYPE_CACHED_VALUES_P (t
) = TYPE_CACHED_VALUES_P (bitsizetype
);
1999 TYPE_PRECISION (t
) = precision
;
2000 TYPE_UID (t
) = TYPE_UID (bitsizetype
);
2001 TYPE_IS_SIZETYPE (t
) = 1;
2003 /* Replace our original stub bitsizetype. */
2004 memcpy (bitsizetype
, t
, tree_size (bitsizetype
));
2005 TYPE_MAIN_VARIANT (bitsizetype
) = bitsizetype
;
2007 if (TYPE_UNSIGNED (type
))
2009 fixup_unsigned_type (bitsizetype
);
2010 ssizetype
= build_distinct_type_copy (make_signed_type (oprecision
));
2011 TYPE_IS_SIZETYPE (ssizetype
) = 1;
2012 sbitsizetype
= build_distinct_type_copy (make_signed_type (precision
));
2013 TYPE_IS_SIZETYPE (sbitsizetype
) = 1;
2017 fixup_signed_type (bitsizetype
);
2018 ssizetype
= sizetype
;
2019 sbitsizetype
= bitsizetype
;
2022 /* If SIZETYPE is unsigned, we need to fix TYPE_MAX_VALUE so that
2023 it is sign extended in a way consistent with force_fit_type. */
2024 if (TYPE_UNSIGNED (type
))
2026 tree orig_max
, new_max
;
2028 orig_max
= TYPE_MAX_VALUE (sizetype
);
2030 /* Build a new node with the same values, but a different type. */
2031 new_max
= build_int_cst_wide (sizetype
,
2032 TREE_INT_CST_LOW (orig_max
),
2033 TREE_INT_CST_HIGH (orig_max
));
2035 /* Now sign extend it using force_fit_type to ensure
2037 new_max
= force_fit_type (new_max
, 0, 0, 0);
2038 TYPE_MAX_VALUE (sizetype
) = new_max
;
2042 /* TYPE is an integral type, i.e., an INTEGRAL_TYPE, ENUMERAL_TYPE
2043 or BOOLEAN_TYPE. Set TYPE_MIN_VALUE and TYPE_MAX_VALUE
2044 for TYPE, based on the PRECISION and whether or not the TYPE
2045 IS_UNSIGNED. PRECISION need not correspond to a width supported
2046 natively by the hardware; for example, on a machine with 8-bit,
2047 16-bit, and 32-bit register modes, PRECISION might be 7, 23, or
2051 set_min_and_max_values_for_integral_type (tree type
,
2060 min_value
= build_int_cst (type
, 0);
2062 = build_int_cst_wide (type
, precision
- HOST_BITS_PER_WIDE_INT
>= 0
2064 : ((HOST_WIDE_INT
) 1 << precision
) - 1,
2065 precision
- HOST_BITS_PER_WIDE_INT
> 0
2066 ? ((unsigned HOST_WIDE_INT
) ~0
2067 >> (HOST_BITS_PER_WIDE_INT
2068 - (precision
- HOST_BITS_PER_WIDE_INT
)))
2074 = build_int_cst_wide (type
,
2075 (precision
- HOST_BITS_PER_WIDE_INT
> 0
2077 : (HOST_WIDE_INT
) (-1) << (precision
- 1)),
2078 (((HOST_WIDE_INT
) (-1)
2079 << (precision
- HOST_BITS_PER_WIDE_INT
- 1 > 0
2080 ? precision
- HOST_BITS_PER_WIDE_INT
- 1
2083 = build_int_cst_wide (type
,
2084 (precision
- HOST_BITS_PER_WIDE_INT
> 0
2086 : ((HOST_WIDE_INT
) 1 << (precision
- 1)) - 1),
2087 (precision
- HOST_BITS_PER_WIDE_INT
- 1 > 0
2088 ? (((HOST_WIDE_INT
) 1
2089 << (precision
- HOST_BITS_PER_WIDE_INT
- 1))) - 1
2093 TYPE_MIN_VALUE (type
) = min_value
;
2094 TYPE_MAX_VALUE (type
) = max_value
;
2097 /* Set the extreme values of TYPE based on its precision in bits,
2098 then lay it out. Used when make_signed_type won't do
2099 because the tree code is not INTEGER_TYPE.
2100 E.g. for Pascal, when the -fsigned-char option is given. */
2103 fixup_signed_type (tree type
)
2105 int precision
= TYPE_PRECISION (type
);
2107 /* We can not represent properly constants greater then
2108 2 * HOST_BITS_PER_WIDE_INT, still we need the types
2109 as they are used by i386 vector extensions and friends. */
2110 if (precision
> HOST_BITS_PER_WIDE_INT
* 2)
2111 precision
= HOST_BITS_PER_WIDE_INT
* 2;
2113 set_min_and_max_values_for_integral_type (type
, precision
,
2114 /*is_unsigned=*/false);
2116 /* Lay out the type: set its alignment, size, etc. */
2120 /* Set the extreme values of TYPE based on its precision in bits,
2121 then lay it out. This is used both in `make_unsigned_type'
2122 and for enumeral types. */
2125 fixup_unsigned_type (tree type
)
2127 int precision
= TYPE_PRECISION (type
);
2129 /* We can not represent properly constants greater then
2130 2 * HOST_BITS_PER_WIDE_INT, still we need the types
2131 as they are used by i386 vector extensions and friends. */
2132 if (precision
> HOST_BITS_PER_WIDE_INT
* 2)
2133 precision
= HOST_BITS_PER_WIDE_INT
* 2;
2135 TYPE_UNSIGNED (type
) = 1;
2137 set_min_and_max_values_for_integral_type (type
, precision
,
2138 /*is_unsigned=*/true);
2140 /* Lay out the type: set its alignment, size, etc. */
2144 /* Find the best machine mode to use when referencing a bit field of length
2145 BITSIZE bits starting at BITPOS.
2147 The underlying object is known to be aligned to a boundary of ALIGN bits.
2148 If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
2149 larger than LARGEST_MODE (usually SImode).
2151 If no mode meets all these conditions, we return VOIDmode.
2153 If VOLATILEP is false and SLOW_BYTE_ACCESS is false, we return the
2154 smallest mode meeting these conditions.
2156 If VOLATILEP is false and SLOW_BYTE_ACCESS is true, we return the
2157 largest mode (but a mode no wider than UNITS_PER_WORD) that meets
2160 If VOLATILEP is true the narrow_volatile_bitfields target hook is used to
2161 decide which of the above modes should be used. */
2164 get_best_mode (int bitsize
, int bitpos
, unsigned int align
,
2165 enum machine_mode largest_mode
, int volatilep
)
2167 enum machine_mode mode
;
2168 unsigned int unit
= 0;
2170 /* Find the narrowest integer mode that contains the bit field. */
2171 for (mode
= GET_CLASS_NARROWEST_MODE (MODE_INT
); mode
!= VOIDmode
;
2172 mode
= GET_MODE_WIDER_MODE (mode
))
2174 unit
= GET_MODE_BITSIZE (mode
);
2175 if ((bitpos
% unit
) + bitsize
<= unit
)
2179 if (mode
== VOIDmode
2180 /* It is tempting to omit the following line
2181 if STRICT_ALIGNMENT is true.
2182 But that is incorrect, since if the bitfield uses part of 3 bytes
2183 and we use a 4-byte mode, we could get a spurious segv
2184 if the extra 4th byte is past the end of memory.
2185 (Though at least one Unix compiler ignores this problem:
2186 that on the Sequent 386 machine. */
2187 || MIN (unit
, BIGGEST_ALIGNMENT
) > align
2188 || (largest_mode
!= VOIDmode
&& unit
> GET_MODE_BITSIZE (largest_mode
)))
2191 if ((SLOW_BYTE_ACCESS
&& ! volatilep
)
2192 || (volatilep
&& !targetm
.narrow_volatile_bitfield()))
2194 enum machine_mode wide_mode
= VOIDmode
, tmode
;
2196 for (tmode
= GET_CLASS_NARROWEST_MODE (MODE_INT
); tmode
!= VOIDmode
;
2197 tmode
= GET_MODE_WIDER_MODE (tmode
))
2199 unit
= GET_MODE_BITSIZE (tmode
);
2200 if (bitpos
/ unit
== (bitpos
+ bitsize
- 1) / unit
2201 && unit
<= BITS_PER_WORD
2202 && unit
<= MIN (align
, BIGGEST_ALIGNMENT
)
2203 && (largest_mode
== VOIDmode
2204 || unit
<= GET_MODE_BITSIZE (largest_mode
)))
2208 if (wide_mode
!= VOIDmode
)
2215 /* Gets minimal and maximal values for MODE (signed or unsigned depending on
2216 SIGN). The returned constants are made to be usable in TARGET_MODE. */
2219 get_mode_bounds (enum machine_mode mode
, int sign
,
2220 enum machine_mode target_mode
,
2221 rtx
*mmin
, rtx
*mmax
)
2223 unsigned size
= GET_MODE_BITSIZE (mode
);
2224 unsigned HOST_WIDE_INT min_val
, max_val
;
2226 gcc_assert (size
<= HOST_BITS_PER_WIDE_INT
);
2230 min_val
= -((unsigned HOST_WIDE_INT
) 1 << (size
- 1));
2231 max_val
= ((unsigned HOST_WIDE_INT
) 1 << (size
- 1)) - 1;
2236 max_val
= ((unsigned HOST_WIDE_INT
) 1 << (size
- 1) << 1) - 1;
2239 *mmin
= gen_int_mode (min_val
, target_mode
);
2240 *mmax
= gen_int_mode (max_val
, target_mode
);
2243 #include "gt-stor-layout.h"