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 if (!DECL_USER_ALIGN (decl
))
493 DECL_ALIGN (decl
) = 0;
494 SET_DECL_RTL (decl
, 0);
496 layout_decl (decl
, 0);
499 /* Hook for a front-end function that can modify the record layout as needed
500 immediately before it is finalized. */
502 static void (*lang_adjust_rli
) (record_layout_info
) = 0;
505 set_lang_adjust_rli (void (*f
) (record_layout_info
))
510 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
511 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
512 is to be passed to all other layout functions for this record. It is the
513 responsibility of the caller to call `free' for the storage returned.
514 Note that garbage collection is not permitted until we finish laying
518 start_record_layout (tree t
)
520 record_layout_info rli
= xmalloc (sizeof (struct record_layout_info_s
));
524 /* If the type has a minimum specified alignment (via an attribute
525 declaration, for example) use it -- otherwise, start with a
526 one-byte alignment. */
527 rli
->record_align
= MAX (BITS_PER_UNIT
, TYPE_ALIGN (t
));
528 rli
->unpacked_align
= rli
->record_align
;
529 rli
->offset_align
= MAX (rli
->record_align
, BIGGEST_ALIGNMENT
);
531 #ifdef STRUCTURE_SIZE_BOUNDARY
532 /* Packed structures don't need to have minimum size. */
533 if (! TYPE_PACKED (t
))
537 /* #pragma pack overrides STRUCTURE_SIZE_BOUNDARY. */
538 tmp
= (unsigned) STRUCTURE_SIZE_BOUNDARY
;
539 if (maximum_field_alignment
!= 0)
540 tmp
= MIN (tmp
, maximum_field_alignment
);
541 rli
->record_align
= MAX (rli
->record_align
, tmp
);
545 rli
->offset
= size_zero_node
;
546 rli
->bitpos
= bitsize_zero_node
;
548 rli
->pending_statics
= 0;
549 rli
->packed_maybe_necessary
= 0;
550 rli
->remaining_in_alignment
= 0;
555 /* These four routines perform computations that convert between
556 the offset/bitpos forms and byte and bit offsets. */
559 bit_from_pos (tree offset
, tree bitpos
)
561 return size_binop (PLUS_EXPR
, bitpos
,
562 size_binop (MULT_EXPR
,
563 fold_convert (bitsizetype
, offset
),
568 byte_from_pos (tree offset
, tree bitpos
)
570 return size_binop (PLUS_EXPR
, offset
,
571 fold_convert (sizetype
,
572 size_binop (TRUNC_DIV_EXPR
, bitpos
,
573 bitsize_unit_node
)));
577 pos_from_bit (tree
*poffset
, tree
*pbitpos
, unsigned int off_align
,
580 *poffset
= size_binop (MULT_EXPR
,
581 fold_convert (sizetype
,
582 size_binop (FLOOR_DIV_EXPR
, pos
,
583 bitsize_int (off_align
))),
584 size_int (off_align
/ BITS_PER_UNIT
));
585 *pbitpos
= size_binop (FLOOR_MOD_EXPR
, pos
, bitsize_int (off_align
));
588 /* Given a pointer to bit and byte offsets and an offset alignment,
589 normalize the offsets so they are within the alignment. */
592 normalize_offset (tree
*poffset
, tree
*pbitpos
, unsigned int off_align
)
594 /* If the bit position is now larger than it should be, adjust it
596 if (compare_tree_int (*pbitpos
, off_align
) >= 0)
598 tree extra_aligns
= size_binop (FLOOR_DIV_EXPR
, *pbitpos
,
599 bitsize_int (off_align
));
602 = size_binop (PLUS_EXPR
, *poffset
,
603 size_binop (MULT_EXPR
,
604 fold_convert (sizetype
, extra_aligns
),
605 size_int (off_align
/ BITS_PER_UNIT
)));
608 = size_binop (FLOOR_MOD_EXPR
, *pbitpos
, bitsize_int (off_align
));
612 /* Print debugging information about the information in RLI. */
615 debug_rli (record_layout_info rli
)
617 print_node_brief (stderr
, "type", rli
->t
, 0);
618 print_node_brief (stderr
, "\noffset", rli
->offset
, 0);
619 print_node_brief (stderr
, " bitpos", rli
->bitpos
, 0);
621 fprintf (stderr
, "\naligns: rec = %u, unpack = %u, off = %u\n",
622 rli
->record_align
, rli
->unpacked_align
,
625 /* The ms_struct code is the only that uses this. */
626 if (targetm
.ms_bitfield_layout_p (rli
->t
))
627 fprintf (stderr
, "remaining in alignment = %u\n", rli
->remaining_in_alignment
);
629 if (rli
->packed_maybe_necessary
)
630 fprintf (stderr
, "packed may be necessary\n");
632 if (rli
->pending_statics
)
634 fprintf (stderr
, "pending statics:\n");
635 debug_tree (rli
->pending_statics
);
639 /* Given an RLI with a possibly-incremented BITPOS, adjust OFFSET and
640 BITPOS if necessary to keep BITPOS below OFFSET_ALIGN. */
643 normalize_rli (record_layout_info rli
)
645 normalize_offset (&rli
->offset
, &rli
->bitpos
, rli
->offset_align
);
648 /* Returns the size in bytes allocated so far. */
651 rli_size_unit_so_far (record_layout_info rli
)
653 return byte_from_pos (rli
->offset
, rli
->bitpos
);
656 /* Returns the size in bits allocated so far. */
659 rli_size_so_far (record_layout_info rli
)
661 return bit_from_pos (rli
->offset
, rli
->bitpos
);
664 /* FIELD is about to be added to RLI->T. The alignment (in bits) of
665 the next available location within the record is given by KNOWN_ALIGN.
666 Update the variable alignment fields in RLI, and return the alignment
667 to give the FIELD. */
670 update_alignment_for_field (record_layout_info rli
, tree field
,
671 unsigned int known_align
)
673 /* The alignment required for FIELD. */
674 unsigned int desired_align
;
675 /* The type of this field. */
676 tree type
= TREE_TYPE (field
);
677 /* True if the field was explicitly aligned by the user. */
681 /* Do not attempt to align an ERROR_MARK node */
682 if (TREE_CODE (type
) == ERROR_MARK
)
685 /* Lay out the field so we know what alignment it needs. */
686 layout_decl (field
, known_align
);
687 desired_align
= DECL_ALIGN (field
);
688 user_align
= DECL_USER_ALIGN (field
);
690 is_bitfield
= (type
!= error_mark_node
691 && DECL_BIT_FIELD_TYPE (field
)
692 && ! integer_zerop (TYPE_SIZE (type
)));
694 /* Record must have at least as much alignment as any field.
695 Otherwise, the alignment of the field within the record is
697 if (targetm
.ms_bitfield_layout_p (rli
->t
))
699 /* Here, the alignment of the underlying type of a bitfield can
700 affect the alignment of a record; even a zero-sized field
701 can do this. The alignment should be to the alignment of
702 the type, except that for zero-size bitfields this only
703 applies if there was an immediately prior, nonzero-size
704 bitfield. (That's the way it is, experimentally.) */
705 if ((!is_bitfield
&& !DECL_PACKED (field
))
706 || (!integer_zerop (DECL_SIZE (field
))
707 ? !DECL_PACKED (field
)
709 && DECL_BIT_FIELD_TYPE (rli
->prev_field
)
710 && ! integer_zerop (DECL_SIZE (rli
->prev_field
)))))
712 unsigned int type_align
= TYPE_ALIGN (type
);
713 type_align
= MAX (type_align
, desired_align
);
714 if (maximum_field_alignment
!= 0)
715 type_align
= MIN (type_align
, maximum_field_alignment
);
716 rli
->record_align
= MAX (rli
->record_align
, type_align
);
717 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
720 #ifdef PCC_BITFIELD_TYPE_MATTERS
721 else if (is_bitfield
&& PCC_BITFIELD_TYPE_MATTERS
)
723 /* Named bit-fields cause the entire structure to have the
724 alignment implied by their type. Some targets also apply the same
725 rules to unnamed bitfields. */
726 if (DECL_NAME (field
) != 0
727 || targetm
.align_anon_bitfield ())
729 unsigned int type_align
= TYPE_ALIGN (type
);
731 #ifdef ADJUST_FIELD_ALIGN
732 if (! TYPE_USER_ALIGN (type
))
733 type_align
= ADJUST_FIELD_ALIGN (field
, type_align
);
736 /* Targets might chose to handle unnamed and hence possibly
737 zero-width bitfield. Those are not influenced by #pragmas
738 or packed attributes. */
739 if (integer_zerop (DECL_SIZE (field
)))
741 if (initial_max_fld_align
)
742 type_align
= MIN (type_align
,
743 initial_max_fld_align
* BITS_PER_UNIT
);
745 else if (maximum_field_alignment
!= 0)
746 type_align
= MIN (type_align
, maximum_field_alignment
);
747 else if (DECL_PACKED (field
))
748 type_align
= MIN (type_align
, BITS_PER_UNIT
);
750 /* The alignment of the record is increased to the maximum
751 of the current alignment, the alignment indicated on the
752 field (i.e., the alignment specified by an __aligned__
753 attribute), and the alignment indicated by the type of
755 rli
->record_align
= MAX (rli
->record_align
, desired_align
);
756 rli
->record_align
= MAX (rli
->record_align
, type_align
);
759 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
760 user_align
|= TYPE_USER_ALIGN (type
);
766 rli
->record_align
= MAX (rli
->record_align
, desired_align
);
767 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
770 TYPE_USER_ALIGN (rli
->t
) |= user_align
;
772 return desired_align
;
775 /* Called from place_field to handle unions. */
778 place_union_field (record_layout_info rli
, tree field
)
780 update_alignment_for_field (rli
, field
, /*known_align=*/0);
782 DECL_FIELD_OFFSET (field
) = size_zero_node
;
783 DECL_FIELD_BIT_OFFSET (field
) = bitsize_zero_node
;
784 SET_DECL_OFFSET_ALIGN (field
, BIGGEST_ALIGNMENT
);
786 /* If this is an ERROR_MARK return *after* having set the
787 field at the start of the union. This helps when parsing
789 if (TREE_CODE (TREE_TYPE (field
)) == ERROR_MARK
)
792 /* We assume the union's size will be a multiple of a byte so we don't
793 bother with BITPOS. */
794 if (TREE_CODE (rli
->t
) == UNION_TYPE
)
795 rli
->offset
= size_binop (MAX_EXPR
, rli
->offset
, DECL_SIZE_UNIT (field
));
796 else if (TREE_CODE (rli
->t
) == QUAL_UNION_TYPE
)
797 rli
->offset
= fold_build3 (COND_EXPR
, sizetype
,
798 DECL_QUALIFIER (field
),
799 DECL_SIZE_UNIT (field
), rli
->offset
);
802 #if defined (PCC_BITFIELD_TYPE_MATTERS) || defined (BITFIELD_NBYTES_LIMITED)
803 /* A bitfield of SIZE with a required access alignment of ALIGN is allocated
804 at BYTE_OFFSET / BIT_OFFSET. Return nonzero if the field would span more
805 units of alignment than the underlying TYPE. */
807 excess_unit_span (HOST_WIDE_INT byte_offset
, HOST_WIDE_INT bit_offset
,
808 HOST_WIDE_INT size
, HOST_WIDE_INT align
, tree type
)
810 /* Note that the calculation of OFFSET might overflow; we calculate it so
811 that we still get the right result as long as ALIGN is a power of two. */
812 unsigned HOST_WIDE_INT offset
= byte_offset
* BITS_PER_UNIT
+ bit_offset
;
814 offset
= offset
% align
;
815 return ((offset
+ size
+ align
- 1) / align
816 > ((unsigned HOST_WIDE_INT
) tree_low_cst (TYPE_SIZE (type
), 1)
821 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
822 is a FIELD_DECL to be added after those fields already present in
823 T. (FIELD is not actually added to the TYPE_FIELDS list here;
824 callers that desire that behavior must manually perform that step.) */
827 place_field (record_layout_info rli
, tree field
)
829 /* The alignment required for FIELD. */
830 unsigned int desired_align
;
831 /* The alignment FIELD would have if we just dropped it into the
832 record as it presently stands. */
833 unsigned int known_align
;
834 unsigned int actual_align
;
835 /* The type of this field. */
836 tree type
= TREE_TYPE (field
);
838 gcc_assert (TREE_CODE (field
) != ERROR_MARK
);
840 /* If FIELD is static, then treat it like a separate variable, not
841 really like a structure field. If it is a FUNCTION_DECL, it's a
842 method. In both cases, all we do is lay out the decl, and we do
843 it *after* the record is laid out. */
844 if (TREE_CODE (field
) == VAR_DECL
)
846 rli
->pending_statics
= tree_cons (NULL_TREE
, field
,
847 rli
->pending_statics
);
851 /* Enumerators and enum types which are local to this class need not
852 be laid out. Likewise for initialized constant fields. */
853 else if (TREE_CODE (field
) != FIELD_DECL
)
856 /* Unions are laid out very differently than records, so split
857 that code off to another function. */
858 else if (TREE_CODE (rli
->t
) != RECORD_TYPE
)
860 place_union_field (rli
, field
);
864 else if (TREE_CODE (type
) == ERROR_MARK
)
866 /* Place this field at the current allocation position, so we
867 maintain monotonicity. */
868 DECL_FIELD_OFFSET (field
) = rli
->offset
;
869 DECL_FIELD_BIT_OFFSET (field
) = rli
->bitpos
;
870 SET_DECL_OFFSET_ALIGN (field
, rli
->offset_align
);
874 /* Work out the known alignment so far. Note that A & (-A) is the
875 value of the least-significant bit in A that is one. */
876 if (! integer_zerop (rli
->bitpos
))
877 known_align
= (tree_low_cst (rli
->bitpos
, 1)
878 & - tree_low_cst (rli
->bitpos
, 1));
879 else if (integer_zerop (rli
->offset
))
881 else if (host_integerp (rli
->offset
, 1))
882 known_align
= (BITS_PER_UNIT
883 * (tree_low_cst (rli
->offset
, 1)
884 & - tree_low_cst (rli
->offset
, 1)));
886 known_align
= rli
->offset_align
;
888 desired_align
= update_alignment_for_field (rli
, field
, known_align
);
889 if (known_align
== 0)
890 known_align
= MAX (BIGGEST_ALIGNMENT
, rli
->record_align
);
892 if (warn_packed
&& DECL_PACKED (field
))
894 if (known_align
>= TYPE_ALIGN (type
))
896 if (TYPE_ALIGN (type
) > desired_align
)
898 if (STRICT_ALIGNMENT
)
899 warning (OPT_Wattributes
, "packed attribute causes "
900 "inefficient alignment for %q+D", field
);
902 warning (OPT_Wattributes
, "packed attribute is "
903 "unnecessary for %q+D", field
);
907 rli
->packed_maybe_necessary
= 1;
910 /* Does this field automatically have alignment it needs by virtue
911 of the fields that precede it and the record's own alignment?
912 We already align ms_struct fields, so don't re-align them. */
913 if (known_align
< desired_align
914 && !targetm
.ms_bitfield_layout_p (rli
->t
))
916 /* No, we need to skip space before this field.
917 Bump the cumulative size to multiple of field alignment. */
919 warning (OPT_Wpadded
, "padding struct to align %q+D", field
);
921 /* If the alignment is still within offset_align, just align
923 if (desired_align
< rli
->offset_align
)
924 rli
->bitpos
= round_up (rli
->bitpos
, desired_align
);
927 /* First adjust OFFSET by the partial bits, then align. */
929 = size_binop (PLUS_EXPR
, rli
->offset
,
930 fold_convert (sizetype
,
931 size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
932 bitsize_unit_node
)));
933 rli
->bitpos
= bitsize_zero_node
;
935 rli
->offset
= round_up (rli
->offset
, desired_align
/ BITS_PER_UNIT
);
938 if (! TREE_CONSTANT (rli
->offset
))
939 rli
->offset_align
= desired_align
;
943 /* Handle compatibility with PCC. Note that if the record has any
944 variable-sized fields, we need not worry about compatibility. */
945 #ifdef PCC_BITFIELD_TYPE_MATTERS
946 if (PCC_BITFIELD_TYPE_MATTERS
947 && ! targetm
.ms_bitfield_layout_p (rli
->t
)
948 && TREE_CODE (field
) == FIELD_DECL
949 && type
!= error_mark_node
950 && DECL_BIT_FIELD (field
)
951 && ! DECL_PACKED (field
)
952 && maximum_field_alignment
== 0
953 && ! integer_zerop (DECL_SIZE (field
))
954 && host_integerp (DECL_SIZE (field
), 1)
955 && host_integerp (rli
->offset
, 1)
956 && host_integerp (TYPE_SIZE (type
), 1))
958 unsigned int type_align
= TYPE_ALIGN (type
);
959 tree dsize
= DECL_SIZE (field
);
960 HOST_WIDE_INT field_size
= tree_low_cst (dsize
, 1);
961 HOST_WIDE_INT offset
= tree_low_cst (rli
->offset
, 0);
962 HOST_WIDE_INT bit_offset
= tree_low_cst (rli
->bitpos
, 0);
964 #ifdef ADJUST_FIELD_ALIGN
965 if (! TYPE_USER_ALIGN (type
))
966 type_align
= ADJUST_FIELD_ALIGN (field
, type_align
);
969 /* A bit field may not span more units of alignment of its type
970 than its type itself. Advance to next boundary if necessary. */
971 if (excess_unit_span (offset
, bit_offset
, field_size
, type_align
, type
))
972 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
974 TYPE_USER_ALIGN (rli
->t
) |= TYPE_USER_ALIGN (type
);
978 #ifdef BITFIELD_NBYTES_LIMITED
979 if (BITFIELD_NBYTES_LIMITED
980 && ! targetm
.ms_bitfield_layout_p (rli
->t
)
981 && TREE_CODE (field
) == FIELD_DECL
982 && type
!= error_mark_node
983 && DECL_BIT_FIELD_TYPE (field
)
984 && ! DECL_PACKED (field
)
985 && ! integer_zerop (DECL_SIZE (field
))
986 && host_integerp (DECL_SIZE (field
), 1)
987 && host_integerp (rli
->offset
, 1)
988 && host_integerp (TYPE_SIZE (type
), 1))
990 unsigned int type_align
= TYPE_ALIGN (type
);
991 tree dsize
= DECL_SIZE (field
);
992 HOST_WIDE_INT field_size
= tree_low_cst (dsize
, 1);
993 HOST_WIDE_INT offset
= tree_low_cst (rli
->offset
, 0);
994 HOST_WIDE_INT bit_offset
= tree_low_cst (rli
->bitpos
, 0);
996 #ifdef ADJUST_FIELD_ALIGN
997 if (! TYPE_USER_ALIGN (type
))
998 type_align
= ADJUST_FIELD_ALIGN (field
, type_align
);
1001 if (maximum_field_alignment
!= 0)
1002 type_align
= MIN (type_align
, maximum_field_alignment
);
1003 /* ??? This test is opposite the test in the containing if
1004 statement, so this code is unreachable currently. */
1005 else if (DECL_PACKED (field
))
1006 type_align
= MIN (type_align
, BITS_PER_UNIT
);
1008 /* A bit field may not span the unit of alignment of its type.
1009 Advance to next boundary if necessary. */
1010 if (excess_unit_span (offset
, bit_offset
, field_size
, type_align
, type
))
1011 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1013 TYPE_USER_ALIGN (rli
->t
) |= TYPE_USER_ALIGN (type
);
1017 /* See the docs for TARGET_MS_BITFIELD_LAYOUT_P for details.
1019 When a bit field is inserted into a packed record, the whole
1020 size of the underlying type is used by one or more same-size
1021 adjacent bitfields. (That is, if its long:3, 32 bits is
1022 used in the record, and any additional adjacent long bitfields are
1023 packed into the same chunk of 32 bits. However, if the size
1024 changes, a new field of that size is allocated.) In an unpacked
1025 record, this is the same as using alignment, but not equivalent
1028 Note: for compatibility, we use the type size, not the type alignment
1029 to determine alignment, since that matches the documentation */
1031 if (targetm
.ms_bitfield_layout_p (rli
->t
))
1033 tree prev_saved
= rli
->prev_field
;
1034 tree prev_type
= prev_saved
? DECL_BIT_FIELD_TYPE (prev_saved
) : NULL
;
1036 /* This is a bitfield if it exists. */
1037 if (rli
->prev_field
)
1039 /* If both are bitfields, nonzero, and the same size, this is
1040 the middle of a run. Zero declared size fields are special
1041 and handled as "end of run". (Note: it's nonzero declared
1042 size, but equal type sizes!) (Since we know that both
1043 the current and previous fields are bitfields by the
1044 time we check it, DECL_SIZE must be present for both.) */
1045 if (DECL_BIT_FIELD_TYPE (field
)
1046 && !integer_zerop (DECL_SIZE (field
))
1047 && !integer_zerop (DECL_SIZE (rli
->prev_field
))
1048 && host_integerp (DECL_SIZE (rli
->prev_field
), 0)
1049 && host_integerp (TYPE_SIZE (type
), 0)
1050 && simple_cst_equal (TYPE_SIZE (type
), TYPE_SIZE (prev_type
)))
1052 /* We're in the middle of a run of equal type size fields; make
1053 sure we realign if we run out of bits. (Not decl size,
1055 HOST_WIDE_INT bitsize
= tree_low_cst (DECL_SIZE (field
), 1);
1057 if (rli
->remaining_in_alignment
< bitsize
)
1059 HOST_WIDE_INT typesize
= tree_low_cst (TYPE_SIZE (type
), 1);
1061 /* out of bits; bump up to next 'word'. */
1063 = size_binop (PLUS_EXPR
, rli
->bitpos
,
1064 bitsize_int (rli
->remaining_in_alignment
));
1065 rli
->prev_field
= field
;
1066 if (typesize
< bitsize
)
1067 rli
->remaining_in_alignment
= 0;
1069 rli
->remaining_in_alignment
= typesize
- bitsize
;
1072 rli
->remaining_in_alignment
-= bitsize
;
1076 /* End of a run: if leaving a run of bitfields of the same type
1077 size, we have to "use up" the rest of the bits of the type
1080 Compute the new position as the sum of the size for the prior
1081 type and where we first started working on that type.
1082 Note: since the beginning of the field was aligned then
1083 of course the end will be too. No round needed. */
1085 if (!integer_zerop (DECL_SIZE (rli
->prev_field
)))
1088 = size_binop (PLUS_EXPR
, rli
->bitpos
,
1089 bitsize_int (rli
->remaining_in_alignment
));
1092 /* We "use up" size zero fields; the code below should behave
1093 as if the prior field was not a bitfield. */
1096 /* Cause a new bitfield to be captured, either this time (if
1097 currently a bitfield) or next time we see one. */
1098 if (!DECL_BIT_FIELD_TYPE(field
)
1099 || integer_zerop (DECL_SIZE (field
)))
1100 rli
->prev_field
= NULL
;
1103 normalize_rli (rli
);
1106 /* If we're starting a new run of same size type bitfields
1107 (or a run of non-bitfields), set up the "first of the run"
1110 That is, if the current field is not a bitfield, or if there
1111 was a prior bitfield the type sizes differ, or if there wasn't
1112 a prior bitfield the size of the current field is nonzero.
1114 Note: we must be sure to test ONLY the type size if there was
1115 a prior bitfield and ONLY for the current field being zero if
1118 if (!DECL_BIT_FIELD_TYPE (field
)
1119 || (prev_saved
!= NULL
1120 ? !simple_cst_equal (TYPE_SIZE (type
), TYPE_SIZE (prev_type
))
1121 : !integer_zerop (DECL_SIZE (field
)) ))
1123 /* Never smaller than a byte for compatibility. */
1124 unsigned int type_align
= BITS_PER_UNIT
;
1126 /* (When not a bitfield), we could be seeing a flex array (with
1127 no DECL_SIZE). Since we won't be using remaining_in_alignment
1128 until we see a bitfield (and come by here again) we just skip
1130 if (DECL_SIZE (field
) != NULL
1131 && host_integerp (TYPE_SIZE (TREE_TYPE (field
)), 0)
1132 && host_integerp (DECL_SIZE (field
), 0))
1134 HOST_WIDE_INT bitsize
= tree_low_cst (DECL_SIZE (field
), 1);
1135 HOST_WIDE_INT typesize
1136 = tree_low_cst (TYPE_SIZE (TREE_TYPE (field
)), 1);
1138 if (typesize
< bitsize
)
1139 rli
->remaining_in_alignment
= 0;
1141 rli
->remaining_in_alignment
= typesize
- bitsize
;
1144 /* Now align (conventionally) for the new type. */
1145 type_align
= TYPE_ALIGN (TREE_TYPE (field
));
1147 if (maximum_field_alignment
!= 0)
1148 type_align
= MIN (type_align
, maximum_field_alignment
);
1150 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1152 /* If we really aligned, don't allow subsequent bitfields
1154 rli
->prev_field
= NULL
;
1158 /* Offset so far becomes the position of this field after normalizing. */
1159 normalize_rli (rli
);
1160 DECL_FIELD_OFFSET (field
) = rli
->offset
;
1161 DECL_FIELD_BIT_OFFSET (field
) = rli
->bitpos
;
1162 SET_DECL_OFFSET_ALIGN (field
, rli
->offset_align
);
1164 /* If this field ended up more aligned than we thought it would be (we
1165 approximate this by seeing if its position changed), lay out the field
1166 again; perhaps we can use an integral mode for it now. */
1167 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field
)))
1168 actual_align
= (tree_low_cst (DECL_FIELD_BIT_OFFSET (field
), 1)
1169 & - tree_low_cst (DECL_FIELD_BIT_OFFSET (field
), 1));
1170 else if (integer_zerop (DECL_FIELD_OFFSET (field
)))
1171 actual_align
= MAX (BIGGEST_ALIGNMENT
, rli
->record_align
);
1172 else if (host_integerp (DECL_FIELD_OFFSET (field
), 1))
1173 actual_align
= (BITS_PER_UNIT
1174 * (tree_low_cst (DECL_FIELD_OFFSET (field
), 1)
1175 & - tree_low_cst (DECL_FIELD_OFFSET (field
), 1)));
1177 actual_align
= DECL_OFFSET_ALIGN (field
);
1178 /* ACTUAL_ALIGN is still the actual alignment *within the record* .
1179 store / extract bit field operations will check the alignment of the
1180 record against the mode of bit fields. */
1182 if (known_align
!= actual_align
)
1183 layout_decl (field
, actual_align
);
1185 if (rli
->prev_field
== NULL
&& DECL_BIT_FIELD_TYPE (field
))
1186 rli
->prev_field
= field
;
1188 /* Now add size of this field to the size of the record. If the size is
1189 not constant, treat the field as being a multiple of bytes and just
1190 adjust the offset, resetting the bit position. Otherwise, apportion the
1191 size amongst the bit position and offset. First handle the case of an
1192 unspecified size, which can happen when we have an invalid nested struct
1193 definition, such as struct j { struct j { int i; } }. The error message
1194 is printed in finish_struct. */
1195 if (DECL_SIZE (field
) == 0)
1197 else if (TREE_CODE (DECL_SIZE (field
)) != INTEGER_CST
1198 || TREE_CONSTANT_OVERFLOW (DECL_SIZE (field
)))
1201 = size_binop (PLUS_EXPR
, rli
->offset
,
1202 fold_convert (sizetype
,
1203 size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
1204 bitsize_unit_node
)));
1206 = size_binop (PLUS_EXPR
, rli
->offset
, DECL_SIZE_UNIT (field
));
1207 rli
->bitpos
= bitsize_zero_node
;
1208 rli
->offset_align
= MIN (rli
->offset_align
, desired_align
);
1210 else if (targetm
.ms_bitfield_layout_p (rli
->t
))
1212 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
, DECL_SIZE (field
));
1214 /* If we ended a bitfield before the full length of the type then
1215 pad the struct out to the full length of the last type. */
1216 if ((TREE_CHAIN (field
) == NULL
1217 || TREE_CODE (TREE_CHAIN (field
)) != FIELD_DECL
)
1218 && DECL_BIT_FIELD_TYPE (field
)
1219 && !integer_zerop (DECL_SIZE (field
)))
1220 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
,
1221 bitsize_int (rli
->remaining_in_alignment
));
1223 normalize_rli (rli
);
1227 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
, DECL_SIZE (field
));
1228 normalize_rli (rli
);
1232 /* Assuming that all the fields have been laid out, this function uses
1233 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
1234 indicated by RLI. */
1237 finalize_record_size (record_layout_info rli
)
1239 tree unpadded_size
, unpadded_size_unit
;
1241 /* Now we want just byte and bit offsets, so set the offset alignment
1242 to be a byte and then normalize. */
1243 rli
->offset_align
= BITS_PER_UNIT
;
1244 normalize_rli (rli
);
1246 /* Determine the desired alignment. */
1247 #ifdef ROUND_TYPE_ALIGN
1248 TYPE_ALIGN (rli
->t
) = ROUND_TYPE_ALIGN (rli
->t
, TYPE_ALIGN (rli
->t
),
1251 TYPE_ALIGN (rli
->t
) = MAX (TYPE_ALIGN (rli
->t
), rli
->record_align
);
1254 /* Compute the size so far. Be sure to allow for extra bits in the
1255 size in bytes. We have guaranteed above that it will be no more
1256 than a single byte. */
1257 unpadded_size
= rli_size_so_far (rli
);
1258 unpadded_size_unit
= rli_size_unit_so_far (rli
);
1259 if (! integer_zerop (rli
->bitpos
))
1261 = size_binop (PLUS_EXPR
, unpadded_size_unit
, size_one_node
);
1263 /* Round the size up to be a multiple of the required alignment. */
1264 TYPE_SIZE (rli
->t
) = round_up (unpadded_size
, TYPE_ALIGN (rli
->t
));
1265 TYPE_SIZE_UNIT (rli
->t
)
1266 = round_up (unpadded_size_unit
, TYPE_ALIGN_UNIT (rli
->t
));
1268 if (TREE_CONSTANT (unpadded_size
)
1269 && simple_cst_equal (unpadded_size
, TYPE_SIZE (rli
->t
)) == 0)
1270 warning (OPT_Wpadded
, "padding struct size to alignment boundary");
1272 if (warn_packed
&& TREE_CODE (rli
->t
) == RECORD_TYPE
1273 && TYPE_PACKED (rli
->t
) && ! rli
->packed_maybe_necessary
1274 && TREE_CONSTANT (unpadded_size
))
1278 #ifdef ROUND_TYPE_ALIGN
1280 = ROUND_TYPE_ALIGN (rli
->t
, TYPE_ALIGN (rli
->t
), rli
->unpacked_align
);
1282 rli
->unpacked_align
= MAX (TYPE_ALIGN (rli
->t
), rli
->unpacked_align
);
1285 unpacked_size
= round_up (TYPE_SIZE (rli
->t
), rli
->unpacked_align
);
1286 if (simple_cst_equal (unpacked_size
, TYPE_SIZE (rli
->t
)))
1288 TYPE_PACKED (rli
->t
) = 0;
1290 if (TYPE_NAME (rli
->t
))
1294 if (TREE_CODE (TYPE_NAME (rli
->t
)) == IDENTIFIER_NODE
)
1295 name
= IDENTIFIER_POINTER (TYPE_NAME (rli
->t
));
1297 name
= IDENTIFIER_POINTER (DECL_NAME (TYPE_NAME (rli
->t
)));
1299 if (STRICT_ALIGNMENT
)
1300 warning (OPT_Wpacked
, "packed attribute causes inefficient "
1301 "alignment for %qs", name
);
1303 warning (OPT_Wpacked
,
1304 "packed attribute is unnecessary for %qs", name
);
1308 if (STRICT_ALIGNMENT
)
1309 warning (OPT_Wpacked
,
1310 "packed attribute causes inefficient alignment");
1312 warning (OPT_Wpacked
, "packed attribute is unnecessary");
1318 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
1321 compute_record_mode (tree type
)
1324 enum machine_mode mode
= VOIDmode
;
1326 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
1327 However, if possible, we use a mode that fits in a register
1328 instead, in order to allow for better optimization down the
1330 TYPE_MODE (type
) = BLKmode
;
1332 if (! host_integerp (TYPE_SIZE (type
), 1))
1335 /* A record which has any BLKmode members must itself be
1336 BLKmode; it can't go in a register. Unless the member is
1337 BLKmode only because it isn't aligned. */
1338 for (field
= TYPE_FIELDS (type
); field
; field
= TREE_CHAIN (field
))
1340 if (TREE_CODE (field
) != FIELD_DECL
)
1343 if (TREE_CODE (TREE_TYPE (field
)) == ERROR_MARK
1344 || (TYPE_MODE (TREE_TYPE (field
)) == BLKmode
1345 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field
))
1346 && !(TYPE_SIZE (TREE_TYPE (field
)) != 0
1347 && integer_zerop (TYPE_SIZE (TREE_TYPE (field
)))))
1348 || ! host_integerp (bit_position (field
), 1)
1349 || DECL_SIZE (field
) == 0
1350 || ! host_integerp (DECL_SIZE (field
), 1))
1353 /* If this field is the whole struct, remember its mode so
1354 that, say, we can put a double in a class into a DF
1355 register instead of forcing it to live in the stack. */
1356 if (simple_cst_equal (TYPE_SIZE (type
), DECL_SIZE (field
)))
1357 mode
= DECL_MODE (field
);
1359 #ifdef MEMBER_TYPE_FORCES_BLK
1360 /* With some targets, eg. c4x, it is sub-optimal
1361 to access an aligned BLKmode structure as a scalar. */
1363 if (MEMBER_TYPE_FORCES_BLK (field
, mode
))
1365 #endif /* MEMBER_TYPE_FORCES_BLK */
1368 /* If we only have one real field; use its mode if that mode's size
1369 matches the type's size. This only applies to RECORD_TYPE. This
1370 does not apply to unions. */
1371 if (TREE_CODE (type
) == RECORD_TYPE
&& mode
!= VOIDmode
1372 && host_integerp (TYPE_SIZE (type
), 1)
1373 && GET_MODE_BITSIZE (mode
) == TREE_INT_CST_LOW (TYPE_SIZE (type
)))
1374 TYPE_MODE (type
) = mode
;
1376 TYPE_MODE (type
) = mode_for_size_tree (TYPE_SIZE (type
), MODE_INT
, 1);
1378 /* If structure's known alignment is less than what the scalar
1379 mode would need, and it matters, then stick with BLKmode. */
1380 if (TYPE_MODE (type
) != BLKmode
1382 && ! (TYPE_ALIGN (type
) >= BIGGEST_ALIGNMENT
1383 || TYPE_ALIGN (type
) >= GET_MODE_ALIGNMENT (TYPE_MODE (type
))))
1385 /* If this is the only reason this type is BLKmode, then
1386 don't force containing types to be BLKmode. */
1387 TYPE_NO_FORCE_BLK (type
) = 1;
1388 TYPE_MODE (type
) = BLKmode
;
1392 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1396 finalize_type_size (tree type
)
1398 /* Normally, use the alignment corresponding to the mode chosen.
1399 However, where strict alignment is not required, avoid
1400 over-aligning structures, since most compilers do not do this
1403 if (TYPE_MODE (type
) != BLKmode
&& TYPE_MODE (type
) != VOIDmode
1404 && (STRICT_ALIGNMENT
1405 || (TREE_CODE (type
) != RECORD_TYPE
&& TREE_CODE (type
) != UNION_TYPE
1406 && TREE_CODE (type
) != QUAL_UNION_TYPE
1407 && TREE_CODE (type
) != ARRAY_TYPE
)))
1409 unsigned mode_align
= GET_MODE_ALIGNMENT (TYPE_MODE (type
));
1411 /* Don't override a larger alignment requirement coming from a user
1412 alignment of one of the fields. */
1413 if (mode_align
>= TYPE_ALIGN (type
))
1415 TYPE_ALIGN (type
) = mode_align
;
1416 TYPE_USER_ALIGN (type
) = 0;
1420 /* Do machine-dependent extra alignment. */
1421 #ifdef ROUND_TYPE_ALIGN
1423 = ROUND_TYPE_ALIGN (type
, TYPE_ALIGN (type
), BITS_PER_UNIT
);
1426 /* If we failed to find a simple way to calculate the unit size
1427 of the type, find it by division. */
1428 if (TYPE_SIZE_UNIT (type
) == 0 && TYPE_SIZE (type
) != 0)
1429 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1430 result will fit in sizetype. We will get more efficient code using
1431 sizetype, so we force a conversion. */
1432 TYPE_SIZE_UNIT (type
)
1433 = fold_convert (sizetype
,
1434 size_binop (FLOOR_DIV_EXPR
, TYPE_SIZE (type
),
1435 bitsize_unit_node
));
1437 if (TYPE_SIZE (type
) != 0)
1439 TYPE_SIZE (type
) = round_up (TYPE_SIZE (type
), TYPE_ALIGN (type
));
1440 TYPE_SIZE_UNIT (type
) = round_up (TYPE_SIZE_UNIT (type
),
1441 TYPE_ALIGN_UNIT (type
));
1444 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1445 if (TYPE_SIZE (type
) != 0 && TREE_CODE (TYPE_SIZE (type
)) != INTEGER_CST
)
1446 TYPE_SIZE (type
) = variable_size (TYPE_SIZE (type
));
1447 if (TYPE_SIZE_UNIT (type
) != 0
1448 && TREE_CODE (TYPE_SIZE_UNIT (type
)) != INTEGER_CST
)
1449 TYPE_SIZE_UNIT (type
) = variable_size (TYPE_SIZE_UNIT (type
));
1451 /* Also layout any other variants of the type. */
1452 if (TYPE_NEXT_VARIANT (type
)
1453 || type
!= TYPE_MAIN_VARIANT (type
))
1456 /* Record layout info of this variant. */
1457 tree size
= TYPE_SIZE (type
);
1458 tree size_unit
= TYPE_SIZE_UNIT (type
);
1459 unsigned int align
= TYPE_ALIGN (type
);
1460 unsigned int user_align
= TYPE_USER_ALIGN (type
);
1461 enum machine_mode mode
= TYPE_MODE (type
);
1463 /* Copy it into all variants. */
1464 for (variant
= TYPE_MAIN_VARIANT (type
);
1466 variant
= TYPE_NEXT_VARIANT (variant
))
1468 TYPE_SIZE (variant
) = size
;
1469 TYPE_SIZE_UNIT (variant
) = size_unit
;
1470 TYPE_ALIGN (variant
) = align
;
1471 TYPE_USER_ALIGN (variant
) = user_align
;
1472 TYPE_MODE (variant
) = mode
;
1477 /* Do all of the work required to layout the type indicated by RLI,
1478 once the fields have been laid out. This function will call `free'
1479 for RLI, unless FREE_P is false. Passing a value other than false
1480 for FREE_P is bad practice; this option only exists to support the
1484 finish_record_layout (record_layout_info rli
, int free_p
)
1488 /* Compute the final size. */
1489 finalize_record_size (rli
);
1491 /* Compute the TYPE_MODE for the record. */
1492 compute_record_mode (rli
->t
);
1494 /* Perform any last tweaks to the TYPE_SIZE, etc. */
1495 finalize_type_size (rli
->t
);
1497 /* Propagate TYPE_PACKED to variants. With C++ templates,
1498 handle_packed_attribute is too early to do this. */
1499 for (variant
= TYPE_NEXT_VARIANT (rli
->t
); variant
;
1500 variant
= TYPE_NEXT_VARIANT (variant
))
1501 TYPE_PACKED (variant
) = TYPE_PACKED (rli
->t
);
1503 /* Lay out any static members. This is done now because their type
1504 may use the record's type. */
1505 while (rli
->pending_statics
)
1507 layout_decl (TREE_VALUE (rli
->pending_statics
), 0);
1508 rli
->pending_statics
= TREE_CHAIN (rli
->pending_statics
);
1517 /* Finish processing a builtin RECORD_TYPE type TYPE. It's name is
1518 NAME, its fields are chained in reverse on FIELDS.
1520 If ALIGN_TYPE is non-null, it is given the same alignment as
1524 finish_builtin_struct (tree type
, const char *name
, tree fields
,
1529 for (tail
= NULL_TREE
; fields
; tail
= fields
, fields
= next
)
1531 DECL_FIELD_CONTEXT (fields
) = type
;
1532 next
= TREE_CHAIN (fields
);
1533 TREE_CHAIN (fields
) = tail
;
1535 TYPE_FIELDS (type
) = tail
;
1539 TYPE_ALIGN (type
) = TYPE_ALIGN (align_type
);
1540 TYPE_USER_ALIGN (type
) = TYPE_USER_ALIGN (align_type
);
1544 #if 0 /* not yet, should get fixed properly later */
1545 TYPE_NAME (type
) = make_type_decl (get_identifier (name
), type
);
1547 TYPE_NAME (type
) = build_decl (TYPE_DECL
, get_identifier (name
), type
);
1549 TYPE_STUB_DECL (type
) = TYPE_NAME (type
);
1550 layout_decl (TYPE_NAME (type
), 0);
1553 /* Calculate the mode, size, and alignment for TYPE.
1554 For an array type, calculate the element separation as well.
1555 Record TYPE on the chain of permanent or temporary types
1556 so that dbxout will find out about it.
1558 TYPE_SIZE of a type is nonzero if the type has been laid out already.
1559 layout_type does nothing on such a type.
1561 If the type is incomplete, its TYPE_SIZE remains zero. */
1564 layout_type (tree type
)
1568 if (type
== error_mark_node
)
1571 /* Do nothing if type has been laid out before. */
1572 if (TYPE_SIZE (type
))
1575 switch (TREE_CODE (type
))
1578 /* This kind of type is the responsibility
1579 of the language-specific code. */
1582 case BOOLEAN_TYPE
: /* Used for Java, Pascal, and Chill. */
1583 if (TYPE_PRECISION (type
) == 0)
1584 TYPE_PRECISION (type
) = 1; /* default to one byte/boolean. */
1586 /* ... fall through ... */
1590 if (TREE_CODE (TYPE_MIN_VALUE (type
)) == INTEGER_CST
1591 && tree_int_cst_sgn (TYPE_MIN_VALUE (type
)) >= 0)
1592 TYPE_UNSIGNED (type
) = 1;
1594 TYPE_MODE (type
) = smallest_mode_for_size (TYPE_PRECISION (type
),
1596 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
1597 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
1601 TYPE_MODE (type
) = mode_for_size (TYPE_PRECISION (type
), MODE_FLOAT
, 0);
1602 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
1603 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
1607 TYPE_UNSIGNED (type
) = TYPE_UNSIGNED (TREE_TYPE (type
));
1609 = mode_for_size (2 * TYPE_PRECISION (TREE_TYPE (type
)),
1610 (TREE_CODE (TREE_TYPE (type
)) == REAL_TYPE
1611 ? MODE_COMPLEX_FLOAT
: MODE_COMPLEX_INT
),
1613 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
1614 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
1619 int nunits
= TYPE_VECTOR_SUBPARTS (type
);
1620 tree innertype
= TREE_TYPE (type
);
1622 gcc_assert (!(nunits
& (nunits
- 1)));
1624 /* Find an appropriate mode for the vector type. */
1625 if (TYPE_MODE (type
) == VOIDmode
)
1627 enum machine_mode innermode
= TYPE_MODE (innertype
);
1628 enum machine_mode mode
;
1630 /* First, look for a supported vector type. */
1631 if (SCALAR_FLOAT_MODE_P (innermode
))
1632 mode
= MIN_MODE_VECTOR_FLOAT
;
1634 mode
= MIN_MODE_VECTOR_INT
;
1636 for (; mode
!= VOIDmode
; mode
= GET_MODE_WIDER_MODE (mode
))
1637 if (GET_MODE_NUNITS (mode
) == nunits
1638 && GET_MODE_INNER (mode
) == innermode
1639 && targetm
.vector_mode_supported_p (mode
))
1642 /* For integers, try mapping it to a same-sized scalar mode. */
1643 if (mode
== VOIDmode
1644 && GET_MODE_CLASS (innermode
) == MODE_INT
)
1645 mode
= mode_for_size (nunits
* GET_MODE_BITSIZE (innermode
),
1648 if (mode
== VOIDmode
|| !have_regs_of_mode
[mode
])
1649 TYPE_MODE (type
) = BLKmode
;
1651 TYPE_MODE (type
) = mode
;
1654 TYPE_UNSIGNED (type
) = TYPE_UNSIGNED (TREE_TYPE (type
));
1655 TYPE_SIZE_UNIT (type
) = int_const_binop (MULT_EXPR
,
1656 TYPE_SIZE_UNIT (innertype
),
1657 size_int (nunits
), 0);
1658 TYPE_SIZE (type
) = int_const_binop (MULT_EXPR
, TYPE_SIZE (innertype
),
1659 bitsize_int (nunits
), 0);
1661 /* Always naturally align vectors. This prevents ABI changes
1662 depending on whether or not native vector modes are supported. */
1663 TYPE_ALIGN (type
) = tree_low_cst (TYPE_SIZE (type
), 0);
1668 /* This is an incomplete type and so doesn't have a size. */
1669 TYPE_ALIGN (type
) = 1;
1670 TYPE_USER_ALIGN (type
) = 0;
1671 TYPE_MODE (type
) = VOIDmode
;
1675 TYPE_SIZE (type
) = bitsize_int (POINTER_SIZE
);
1676 TYPE_SIZE_UNIT (type
) = size_int (POINTER_SIZE
/ BITS_PER_UNIT
);
1677 /* A pointer might be MODE_PARTIAL_INT,
1678 but ptrdiff_t must be integral. */
1679 TYPE_MODE (type
) = mode_for_size (POINTER_SIZE
, MODE_INT
, 0);
1684 /* It's hard to see what the mode and size of a function ought to
1685 be, but we do know the alignment is FUNCTION_BOUNDARY, so
1686 make it consistent with that. */
1687 TYPE_MODE (type
) = mode_for_size (FUNCTION_BOUNDARY
, MODE_INT
, 0);
1688 TYPE_SIZE (type
) = bitsize_int (FUNCTION_BOUNDARY
);
1689 TYPE_SIZE_UNIT (type
) = size_int (FUNCTION_BOUNDARY
/ BITS_PER_UNIT
);
1693 case REFERENCE_TYPE
:
1696 enum machine_mode mode
= ((TREE_CODE (type
) == REFERENCE_TYPE
1697 && reference_types_internal
)
1698 ? Pmode
: TYPE_MODE (type
));
1700 int nbits
= GET_MODE_BITSIZE (mode
);
1702 TYPE_SIZE (type
) = bitsize_int (nbits
);
1703 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
1704 TYPE_UNSIGNED (type
) = 1;
1705 TYPE_PRECISION (type
) = nbits
;
1711 tree index
= TYPE_DOMAIN (type
);
1712 tree element
= TREE_TYPE (type
);
1714 build_pointer_type (element
);
1716 /* We need to know both bounds in order to compute the size. */
1717 if (index
&& TYPE_MAX_VALUE (index
) && TYPE_MIN_VALUE (index
)
1718 && TYPE_SIZE (element
))
1720 tree ub
= TYPE_MAX_VALUE (index
);
1721 tree lb
= TYPE_MIN_VALUE (index
);
1725 /* The initial subtraction should happen in the original type so
1726 that (possible) negative values are handled appropriately. */
1727 length
= size_binop (PLUS_EXPR
, size_one_node
,
1728 fold_convert (sizetype
,
1729 fold_build2 (MINUS_EXPR
,
1733 /* Special handling for arrays of bits (for Chill). */
1734 element_size
= TYPE_SIZE (element
);
1735 if (TYPE_PACKED (type
) && INTEGRAL_TYPE_P (element
)
1736 && (integer_zerop (TYPE_MAX_VALUE (element
))
1737 || integer_onep (TYPE_MAX_VALUE (element
)))
1738 && host_integerp (TYPE_MIN_VALUE (element
), 1))
1740 HOST_WIDE_INT maxvalue
1741 = tree_low_cst (TYPE_MAX_VALUE (element
), 1);
1742 HOST_WIDE_INT minvalue
1743 = tree_low_cst (TYPE_MIN_VALUE (element
), 1);
1745 if (maxvalue
- minvalue
== 1
1746 && (maxvalue
== 1 || maxvalue
== 0))
1747 element_size
= integer_one_node
;
1750 /* If neither bound is a constant and sizetype is signed, make
1751 sure the size is never negative. We should really do this
1752 if *either* bound is non-constant, but this is the best
1753 compromise between C and Ada. */
1754 if (!TYPE_UNSIGNED (sizetype
)
1755 && TREE_CODE (TYPE_MIN_VALUE (index
)) != INTEGER_CST
1756 && TREE_CODE (TYPE_MAX_VALUE (index
)) != INTEGER_CST
)
1757 length
= size_binop (MAX_EXPR
, length
, size_zero_node
);
1759 TYPE_SIZE (type
) = size_binop (MULT_EXPR
, element_size
,
1760 fold_convert (bitsizetype
,
1763 /* If we know the size of the element, calculate the total
1764 size directly, rather than do some division thing below.
1765 This optimization helps Fortran assumed-size arrays
1766 (where the size of the array is determined at runtime)
1768 Note that we can't do this in the case where the size of
1769 the elements is one bit since TYPE_SIZE_UNIT cannot be
1770 set correctly in that case. */
1771 if (TYPE_SIZE_UNIT (element
) != 0 && ! integer_onep (element_size
))
1772 TYPE_SIZE_UNIT (type
)
1773 = size_binop (MULT_EXPR
, TYPE_SIZE_UNIT (element
), length
);
1776 /* Now round the alignment and size,
1777 using machine-dependent criteria if any. */
1779 #ifdef ROUND_TYPE_ALIGN
1781 = ROUND_TYPE_ALIGN (type
, TYPE_ALIGN (element
), BITS_PER_UNIT
);
1783 TYPE_ALIGN (type
) = MAX (TYPE_ALIGN (element
), BITS_PER_UNIT
);
1785 TYPE_USER_ALIGN (type
) = TYPE_USER_ALIGN (element
);
1786 TYPE_MODE (type
) = BLKmode
;
1787 if (TYPE_SIZE (type
) != 0
1788 #ifdef MEMBER_TYPE_FORCES_BLK
1789 && ! MEMBER_TYPE_FORCES_BLK (type
, VOIDmode
)
1791 /* BLKmode elements force BLKmode aggregate;
1792 else extract/store fields may lose. */
1793 && (TYPE_MODE (TREE_TYPE (type
)) != BLKmode
1794 || TYPE_NO_FORCE_BLK (TREE_TYPE (type
))))
1796 /* One-element arrays get the component type's mode. */
1797 if (simple_cst_equal (TYPE_SIZE (type
),
1798 TYPE_SIZE (TREE_TYPE (type
))))
1799 TYPE_MODE (type
) = TYPE_MODE (TREE_TYPE (type
));
1802 = mode_for_size_tree (TYPE_SIZE (type
), MODE_INT
, 1);
1804 if (TYPE_MODE (type
) != BLKmode
1805 && STRICT_ALIGNMENT
&& TYPE_ALIGN (type
) < BIGGEST_ALIGNMENT
1806 && TYPE_ALIGN (type
) < GET_MODE_ALIGNMENT (TYPE_MODE (type
))
1807 && TYPE_MODE (type
) != BLKmode
)
1809 TYPE_NO_FORCE_BLK (type
) = 1;
1810 TYPE_MODE (type
) = BLKmode
;
1813 /* When the element size is constant, check that it is at least as
1814 large as the element alignment. */
1815 if (TYPE_SIZE_UNIT (element
)
1816 && TREE_CODE (TYPE_SIZE_UNIT (element
)) == INTEGER_CST
1817 /* If TYPE_SIZE_UNIT overflowed, then it is certainly larger than
1819 && !TREE_CONSTANT_OVERFLOW (TYPE_SIZE_UNIT (element
))
1820 && !integer_zerop (TYPE_SIZE_UNIT (element
))
1821 && compare_tree_int (TYPE_SIZE_UNIT (element
),
1822 TYPE_ALIGN_UNIT (element
)) < 0)
1823 error ("alignment of array elements is greater than element size");
1829 case QUAL_UNION_TYPE
:
1832 record_layout_info rli
;
1834 /* Initialize the layout information. */
1835 rli
= start_record_layout (type
);
1837 /* If this is a QUAL_UNION_TYPE, we want to process the fields
1838 in the reverse order in building the COND_EXPR that denotes
1839 its size. We reverse them again later. */
1840 if (TREE_CODE (type
) == QUAL_UNION_TYPE
)
1841 TYPE_FIELDS (type
) = nreverse (TYPE_FIELDS (type
));
1843 /* Place all the fields. */
1844 for (field
= TYPE_FIELDS (type
); field
; field
= TREE_CHAIN (field
))
1845 place_field (rli
, field
);
1847 if (TREE_CODE (type
) == QUAL_UNION_TYPE
)
1848 TYPE_FIELDS (type
) = nreverse (TYPE_FIELDS (type
));
1850 if (lang_adjust_rli
)
1851 (*lang_adjust_rli
) (rli
);
1853 /* Finish laying out the record. */
1854 finish_record_layout (rli
, /*free_p=*/true);
1862 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
1863 records and unions, finish_record_layout already called this
1865 if (TREE_CODE (type
) != RECORD_TYPE
1866 && TREE_CODE (type
) != UNION_TYPE
1867 && TREE_CODE (type
) != QUAL_UNION_TYPE
)
1868 finalize_type_size (type
);
1870 /* If an alias set has been set for this aggregate when it was incomplete,
1871 force it into alias set 0.
1872 This is too conservative, but we cannot call record_component_aliases
1873 here because some frontends still change the aggregates after
1875 if (AGGREGATE_TYPE_P (type
) && TYPE_ALIAS_SET_KNOWN_P (type
))
1876 TYPE_ALIAS_SET (type
) = 0;
1879 /* Create and return a type for signed integers of PRECISION bits. */
1882 make_signed_type (int precision
)
1884 tree type
= make_node (INTEGER_TYPE
);
1886 TYPE_PRECISION (type
) = precision
;
1888 fixup_signed_type (type
);
1892 /* Create and return a type for unsigned integers of PRECISION bits. */
1895 make_unsigned_type (int precision
)
1897 tree type
= make_node (INTEGER_TYPE
);
1899 TYPE_PRECISION (type
) = precision
;
1901 fixup_unsigned_type (type
);
1905 /* Initialize sizetype and bitsizetype to a reasonable and temporary
1906 value to enable integer types to be created. */
1909 initialize_sizetypes (bool signed_p
)
1911 tree t
= make_node (INTEGER_TYPE
);
1912 int precision
= GET_MODE_BITSIZE (SImode
);
1914 TYPE_MODE (t
) = SImode
;
1915 TYPE_ALIGN (t
) = GET_MODE_ALIGNMENT (SImode
);
1916 TYPE_USER_ALIGN (t
) = 0;
1917 TYPE_IS_SIZETYPE (t
) = 1;
1918 TYPE_UNSIGNED (t
) = !signed_p
;
1919 TYPE_SIZE (t
) = build_int_cst (t
, precision
);
1920 TYPE_SIZE_UNIT (t
) = build_int_cst (t
, GET_MODE_SIZE (SImode
));
1921 TYPE_PRECISION (t
) = precision
;
1923 /* Set TYPE_MIN_VALUE and TYPE_MAX_VALUE. */
1924 set_min_and_max_values_for_integral_type (t
, precision
, !signed_p
);
1927 bitsizetype
= build_distinct_type_copy (t
);
1930 /* Make sizetype a version of TYPE, and initialize *sizetype
1931 accordingly. We do this by overwriting the stub sizetype and
1932 bitsizetype nodes created by initialize_sizetypes. This makes sure
1933 that (a) anything stubby about them no longer exists, (b) any
1934 INTEGER_CSTs created with such a type, remain valid. */
1937 set_sizetype (tree type
)
1939 int oprecision
= TYPE_PRECISION (type
);
1940 /* The *bitsizetype types use a precision that avoids overflows when
1941 calculating signed sizes / offsets in bits. However, when
1942 cross-compiling from a 32 bit to a 64 bit host, we are limited to 64 bit
1944 int precision
= MIN (oprecision
+ BITS_PER_UNIT_LOG
+ 1,
1945 2 * HOST_BITS_PER_WIDE_INT
);
1948 gcc_assert (TYPE_UNSIGNED (type
) == TYPE_UNSIGNED (sizetype
));
1950 t
= build_distinct_type_copy (type
);
1951 /* We do want to use sizetype's cache, as we will be replacing that
1953 TYPE_CACHED_VALUES (t
) = TYPE_CACHED_VALUES (sizetype
);
1954 TYPE_CACHED_VALUES_P (t
) = TYPE_CACHED_VALUES_P (sizetype
);
1955 TREE_TYPE (TYPE_CACHED_VALUES (t
)) = type
;
1956 TYPE_UID (t
) = TYPE_UID (sizetype
);
1957 TYPE_IS_SIZETYPE (t
) = 1;
1959 /* Replace our original stub sizetype. */
1960 memcpy (sizetype
, t
, tree_size (sizetype
));
1961 TYPE_MAIN_VARIANT (sizetype
) = sizetype
;
1963 t
= make_node (INTEGER_TYPE
);
1964 TYPE_NAME (t
) = get_identifier ("bit_size_type");
1965 /* We do want to use bitsizetype's cache, as we will be replacing that
1967 TYPE_CACHED_VALUES (t
) = TYPE_CACHED_VALUES (bitsizetype
);
1968 TYPE_CACHED_VALUES_P (t
) = TYPE_CACHED_VALUES_P (bitsizetype
);
1969 TYPE_PRECISION (t
) = precision
;
1970 TYPE_UID (t
) = TYPE_UID (bitsizetype
);
1971 TYPE_IS_SIZETYPE (t
) = 1;
1973 /* Replace our original stub bitsizetype. */
1974 memcpy (bitsizetype
, t
, tree_size (bitsizetype
));
1975 TYPE_MAIN_VARIANT (bitsizetype
) = bitsizetype
;
1977 if (TYPE_UNSIGNED (type
))
1979 fixup_unsigned_type (bitsizetype
);
1980 ssizetype
= build_distinct_type_copy (make_signed_type (oprecision
));
1981 TYPE_IS_SIZETYPE (ssizetype
) = 1;
1982 sbitsizetype
= build_distinct_type_copy (make_signed_type (precision
));
1983 TYPE_IS_SIZETYPE (sbitsizetype
) = 1;
1987 fixup_signed_type (bitsizetype
);
1988 ssizetype
= sizetype
;
1989 sbitsizetype
= bitsizetype
;
1992 /* If SIZETYPE is unsigned, we need to fix TYPE_MAX_VALUE so that
1993 it is sign extended in a way consistent with force_fit_type. */
1994 if (TYPE_UNSIGNED (type
))
1996 tree orig_max
, new_max
;
1998 orig_max
= TYPE_MAX_VALUE (sizetype
);
2000 /* Build a new node with the same values, but a different type. */
2001 new_max
= build_int_cst_wide (sizetype
,
2002 TREE_INT_CST_LOW (orig_max
),
2003 TREE_INT_CST_HIGH (orig_max
));
2005 /* Now sign extend it using force_fit_type to ensure
2007 new_max
= force_fit_type (new_max
, 0, 0, 0);
2008 TYPE_MAX_VALUE (sizetype
) = new_max
;
2012 /* TYPE is an integral type, i.e., an INTEGRAL_TYPE, ENUMERAL_TYPE
2013 or BOOLEAN_TYPE. Set TYPE_MIN_VALUE and TYPE_MAX_VALUE
2014 for TYPE, based on the PRECISION and whether or not the TYPE
2015 IS_UNSIGNED. PRECISION need not correspond to a width supported
2016 natively by the hardware; for example, on a machine with 8-bit,
2017 16-bit, and 32-bit register modes, PRECISION might be 7, 23, or
2021 set_min_and_max_values_for_integral_type (tree type
,
2030 min_value
= build_int_cst (type
, 0);
2032 = build_int_cst_wide (type
, precision
- HOST_BITS_PER_WIDE_INT
>= 0
2034 : ((HOST_WIDE_INT
) 1 << precision
) - 1,
2035 precision
- HOST_BITS_PER_WIDE_INT
> 0
2036 ? ((unsigned HOST_WIDE_INT
) ~0
2037 >> (HOST_BITS_PER_WIDE_INT
2038 - (precision
- HOST_BITS_PER_WIDE_INT
)))
2044 = build_int_cst_wide (type
,
2045 (precision
- HOST_BITS_PER_WIDE_INT
> 0
2047 : (HOST_WIDE_INT
) (-1) << (precision
- 1)),
2048 (((HOST_WIDE_INT
) (-1)
2049 << (precision
- HOST_BITS_PER_WIDE_INT
- 1 > 0
2050 ? precision
- HOST_BITS_PER_WIDE_INT
- 1
2053 = build_int_cst_wide (type
,
2054 (precision
- HOST_BITS_PER_WIDE_INT
> 0
2056 : ((HOST_WIDE_INT
) 1 << (precision
- 1)) - 1),
2057 (precision
- HOST_BITS_PER_WIDE_INT
- 1 > 0
2058 ? (((HOST_WIDE_INT
) 1
2059 << (precision
- HOST_BITS_PER_WIDE_INT
- 1))) - 1
2063 TYPE_MIN_VALUE (type
) = min_value
;
2064 TYPE_MAX_VALUE (type
) = max_value
;
2067 /* Set the extreme values of TYPE based on its precision in bits,
2068 then lay it out. Used when make_signed_type won't do
2069 because the tree code is not INTEGER_TYPE.
2070 E.g. for Pascal, when the -fsigned-char option is given. */
2073 fixup_signed_type (tree type
)
2075 int precision
= TYPE_PRECISION (type
);
2077 /* We can not represent properly constants greater then
2078 2 * HOST_BITS_PER_WIDE_INT, still we need the types
2079 as they are used by i386 vector extensions and friends. */
2080 if (precision
> HOST_BITS_PER_WIDE_INT
* 2)
2081 precision
= HOST_BITS_PER_WIDE_INT
* 2;
2083 set_min_and_max_values_for_integral_type (type
, precision
,
2084 /*is_unsigned=*/false);
2086 /* Lay out the type: set its alignment, size, etc. */
2090 /* Set the extreme values of TYPE based on its precision in bits,
2091 then lay it out. This is used both in `make_unsigned_type'
2092 and for enumeral types. */
2095 fixup_unsigned_type (tree type
)
2097 int precision
= TYPE_PRECISION (type
);
2099 /* We can not represent properly constants greater then
2100 2 * HOST_BITS_PER_WIDE_INT, still we need the types
2101 as they are used by i386 vector extensions and friends. */
2102 if (precision
> HOST_BITS_PER_WIDE_INT
* 2)
2103 precision
= HOST_BITS_PER_WIDE_INT
* 2;
2105 TYPE_UNSIGNED (type
) = 1;
2107 set_min_and_max_values_for_integral_type (type
, precision
,
2108 /*is_unsigned=*/true);
2110 /* Lay out the type: set its alignment, size, etc. */
2114 /* Find the best machine mode to use when referencing a bit field of length
2115 BITSIZE bits starting at BITPOS.
2117 The underlying object is known to be aligned to a boundary of ALIGN bits.
2118 If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
2119 larger than LARGEST_MODE (usually SImode).
2121 If no mode meets all these conditions, we return VOIDmode.
2123 If VOLATILEP is false and SLOW_BYTE_ACCESS is false, we return the
2124 smallest mode meeting these conditions.
2126 If VOLATILEP is false and SLOW_BYTE_ACCESS is true, we return the
2127 largest mode (but a mode no wider than UNITS_PER_WORD) that meets
2130 If VOLATILEP is true the narrow_volatile_bitfields target hook is used to
2131 decide which of the above modes should be used. */
2134 get_best_mode (int bitsize
, int bitpos
, unsigned int align
,
2135 enum machine_mode largest_mode
, int volatilep
)
2137 enum machine_mode mode
;
2138 unsigned int unit
= 0;
2140 /* Find the narrowest integer mode that contains the bit field. */
2141 for (mode
= GET_CLASS_NARROWEST_MODE (MODE_INT
); mode
!= VOIDmode
;
2142 mode
= GET_MODE_WIDER_MODE (mode
))
2144 unit
= GET_MODE_BITSIZE (mode
);
2145 if ((bitpos
% unit
) + bitsize
<= unit
)
2149 if (mode
== VOIDmode
2150 /* It is tempting to omit the following line
2151 if STRICT_ALIGNMENT is true.
2152 But that is incorrect, since if the bitfield uses part of 3 bytes
2153 and we use a 4-byte mode, we could get a spurious segv
2154 if the extra 4th byte is past the end of memory.
2155 (Though at least one Unix compiler ignores this problem:
2156 that on the Sequent 386 machine. */
2157 || MIN (unit
, BIGGEST_ALIGNMENT
) > align
2158 || (largest_mode
!= VOIDmode
&& unit
> GET_MODE_BITSIZE (largest_mode
)))
2161 if ((SLOW_BYTE_ACCESS
&& ! volatilep
)
2162 || (volatilep
&& !targetm
.narrow_volatile_bitfield()))
2164 enum machine_mode wide_mode
= VOIDmode
, tmode
;
2166 for (tmode
= GET_CLASS_NARROWEST_MODE (MODE_INT
); tmode
!= VOIDmode
;
2167 tmode
= GET_MODE_WIDER_MODE (tmode
))
2169 unit
= GET_MODE_BITSIZE (tmode
);
2170 if (bitpos
/ unit
== (bitpos
+ bitsize
- 1) / unit
2171 && unit
<= BITS_PER_WORD
2172 && unit
<= MIN (align
, BIGGEST_ALIGNMENT
)
2173 && (largest_mode
== VOIDmode
2174 || unit
<= GET_MODE_BITSIZE (largest_mode
)))
2178 if (wide_mode
!= VOIDmode
)
2185 /* Gets minimal and maximal values for MODE (signed or unsigned depending on
2186 SIGN). The returned constants are made to be usable in TARGET_MODE. */
2189 get_mode_bounds (enum machine_mode mode
, int sign
,
2190 enum machine_mode target_mode
,
2191 rtx
*mmin
, rtx
*mmax
)
2193 unsigned size
= GET_MODE_BITSIZE (mode
);
2194 unsigned HOST_WIDE_INT min_val
, max_val
;
2196 gcc_assert (size
<= HOST_BITS_PER_WIDE_INT
);
2200 min_val
= -((unsigned HOST_WIDE_INT
) 1 << (size
- 1));
2201 max_val
= ((unsigned HOST_WIDE_INT
) 1 << (size
- 1)) - 1;
2206 max_val
= ((unsigned HOST_WIDE_INT
) 1 << (size
- 1) << 1) - 1;
2209 *mmin
= gen_int_mode (min_val
, target_mode
);
2210 *mmax
= gen_int_mode (max_val
, target_mode
);
2213 #include "gt-stor-layout.h"