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, 2007
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 3, 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 COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
25 #include "coretypes.h"
37 #include "langhooks.h"
41 /* Data type for the expressions representing sizes of data types.
42 It is the first integer type laid out. */
43 tree sizetype_tab
[(int) TYPE_KIND_LAST
];
45 /* If nonzero, this is an upper limit on alignment of structure fields.
46 The value is measured in bits. */
47 unsigned int maximum_field_alignment
= TARGET_DEFAULT_PACK_STRUCT
* BITS_PER_UNIT
;
48 /* ... and its original value in bytes, specified via -fpack-struct=<value>. */
49 unsigned int initial_max_fld_align
= TARGET_DEFAULT_PACK_STRUCT
;
51 /* Nonzero if all REFERENCE_TYPEs are internal and hence should be
52 allocated in Pmode, not ptr_mode. Set only by internal_reference_types
53 called only by a front end. */
54 static int reference_types_internal
= 0;
56 static void finalize_record_size (record_layout_info
);
57 static void finalize_type_size (tree
);
58 static void place_union_field (record_layout_info
, tree
);
59 #if defined (PCC_BITFIELD_TYPE_MATTERS) || defined (BITFIELD_NBYTES_LIMITED)
60 static int excess_unit_span (HOST_WIDE_INT
, HOST_WIDE_INT
, HOST_WIDE_INT
,
63 extern void debug_rli (record_layout_info
);
65 /* SAVE_EXPRs for sizes of types and decls, waiting to be expanded. */
67 static GTY(()) tree pending_sizes
;
69 /* Show that REFERENCE_TYPES are internal and should be Pmode. Called only
73 internal_reference_types (void)
75 reference_types_internal
= 1;
78 /* Get a list of all the objects put on the pending sizes list. */
81 get_pending_sizes (void)
83 tree chain
= pending_sizes
;
89 /* Add EXPR to the pending sizes list. */
92 put_pending_size (tree expr
)
94 /* Strip any simple arithmetic from EXPR to see if it has an underlying
96 expr
= skip_simple_arithmetic (expr
);
98 if (TREE_CODE (expr
) == SAVE_EXPR
)
99 pending_sizes
= tree_cons (NULL_TREE
, expr
, pending_sizes
);
102 /* Put a chain of objects into the pending sizes list, which must be
106 put_pending_sizes (tree chain
)
108 gcc_assert (!pending_sizes
);
109 pending_sizes
= chain
;
112 /* Given a size SIZE that may not be a constant, return a SAVE_EXPR
113 to serve as the actual size-expression for a type or decl. */
116 variable_size (tree size
)
120 /* If the language-processor is to take responsibility for variable-sized
121 items (e.g., languages which have elaboration procedures like Ada),
122 just return SIZE unchanged. Likewise for self-referential sizes and
124 if (TREE_CONSTANT (size
)
125 || lang_hooks
.decls
.global_bindings_p () < 0
126 || CONTAINS_PLACEHOLDER_P (size
))
129 size
= save_expr (size
);
131 /* If an array with a variable number of elements is declared, and
132 the elements require destruction, we will emit a cleanup for the
133 array. That cleanup is run both on normal exit from the block
134 and in the exception-handler for the block. Normally, when code
135 is used in both ordinary code and in an exception handler it is
136 `unsaved', i.e., all SAVE_EXPRs are recalculated. However, we do
137 not wish to do that here; the array-size is the same in both
139 save
= skip_simple_arithmetic (size
);
141 if (cfun
&& cfun
->x_dont_save_pending_sizes_p
)
142 /* The front-end doesn't want us to keep a list of the expressions
143 that determine sizes for variable size objects. Trust it. */
146 if (lang_hooks
.decls
.global_bindings_p ())
148 if (TREE_CONSTANT (size
))
149 error ("type size can%'t be explicitly evaluated");
151 error ("variable-size type declared outside of any function");
153 return size_one_node
;
156 put_pending_size (save
);
161 #ifndef MAX_FIXED_MODE_SIZE
162 #define MAX_FIXED_MODE_SIZE GET_MODE_BITSIZE (DImode)
165 /* Return the machine mode to use for a nonscalar of SIZE bits. The
166 mode must be in class CLASS, and have exactly that many value bits;
167 it may have padding as well. If LIMIT is nonzero, modes of wider
168 than MAX_FIXED_MODE_SIZE will not be used. */
171 mode_for_size (unsigned int size
, enum mode_class
class, int limit
)
173 enum machine_mode mode
;
175 if (limit
&& size
> MAX_FIXED_MODE_SIZE
)
178 /* Get the first mode which has this size, in the specified class. */
179 for (mode
= GET_CLASS_NARROWEST_MODE (class); mode
!= VOIDmode
;
180 mode
= GET_MODE_WIDER_MODE (mode
))
181 if (GET_MODE_PRECISION (mode
) == size
)
187 /* Similar, except passed a tree node. */
190 mode_for_size_tree (const_tree size
, enum mode_class
class, int limit
)
192 unsigned HOST_WIDE_INT uhwi
;
195 if (!host_integerp (size
, 1))
197 uhwi
= tree_low_cst (size
, 1);
201 return mode_for_size (ui
, class, limit
);
204 /* Similar, but never return BLKmode; return the narrowest mode that
205 contains at least the requested number of value bits. */
208 smallest_mode_for_size (unsigned int size
, enum mode_class
class)
210 enum machine_mode mode
;
212 /* Get the first mode which has at least this size, in the
214 for (mode
= GET_CLASS_NARROWEST_MODE (class); mode
!= VOIDmode
;
215 mode
= GET_MODE_WIDER_MODE (mode
))
216 if (GET_MODE_PRECISION (mode
) >= size
)
222 /* Find an integer mode of the exact same size, or BLKmode on failure. */
225 int_mode_for_mode (enum machine_mode mode
)
227 switch (GET_MODE_CLASS (mode
))
230 case MODE_PARTIAL_INT
:
233 case MODE_COMPLEX_INT
:
234 case MODE_COMPLEX_FLOAT
:
236 case MODE_DECIMAL_FLOAT
:
237 case MODE_VECTOR_INT
:
238 case MODE_VECTOR_FLOAT
:
243 case MODE_VECTOR_FRACT
:
244 case MODE_VECTOR_ACCUM
:
245 case MODE_VECTOR_UFRACT
:
246 case MODE_VECTOR_UACCUM
:
247 mode
= mode_for_size (GET_MODE_BITSIZE (mode
), MODE_INT
, 0);
254 /* ... fall through ... */
264 /* Return the alignment of MODE. This will be bounded by 1 and
265 BIGGEST_ALIGNMENT. */
268 get_mode_alignment (enum machine_mode mode
)
270 return MIN (BIGGEST_ALIGNMENT
, MAX (1, mode_base_align
[mode
]*BITS_PER_UNIT
));
274 /* Subroutine of layout_decl: Force alignment required for the data type.
275 But if the decl itself wants greater alignment, don't override that. */
278 do_type_align (tree type
, tree decl
)
280 if (TYPE_ALIGN (type
) > DECL_ALIGN (decl
))
282 DECL_ALIGN (decl
) = TYPE_ALIGN (type
);
283 if (TREE_CODE (decl
) == FIELD_DECL
)
284 DECL_USER_ALIGN (decl
) = TYPE_USER_ALIGN (type
);
288 /* Set the size, mode and alignment of a ..._DECL node.
289 TYPE_DECL does need this for C++.
290 Note that LABEL_DECL and CONST_DECL nodes do not need this,
291 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
292 Don't call layout_decl for them.
294 KNOWN_ALIGN is the amount of alignment we can assume this
295 decl has with no special effort. It is relevant only for FIELD_DECLs
296 and depends on the previous fields.
297 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
298 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
299 the record will be aligned to suit. */
302 layout_decl (tree decl
, unsigned int known_align
)
304 tree type
= TREE_TYPE (decl
);
305 enum tree_code code
= TREE_CODE (decl
);
308 if (code
== CONST_DECL
)
311 gcc_assert (code
== VAR_DECL
|| code
== PARM_DECL
|| code
== RESULT_DECL
312 || code
== TYPE_DECL
||code
== FIELD_DECL
);
314 rtl
= DECL_RTL_IF_SET (decl
);
316 if (type
== error_mark_node
)
317 type
= void_type_node
;
319 /* Usually the size and mode come from the data type without change,
320 however, the front-end may set the explicit width of the field, so its
321 size may not be the same as the size of its type. This happens with
322 bitfields, of course (an `int' bitfield may be only 2 bits, say), but it
323 also happens with other fields. For example, the C++ front-end creates
324 zero-sized fields corresponding to empty base classes, and depends on
325 layout_type setting DECL_FIELD_BITPOS correctly for the field. Set the
326 size in bytes from the size in bits. If we have already set the mode,
327 don't set it again since we can be called twice for FIELD_DECLs. */
329 DECL_UNSIGNED (decl
) = TYPE_UNSIGNED (type
);
330 if (DECL_MODE (decl
) == VOIDmode
)
331 DECL_MODE (decl
) = TYPE_MODE (type
);
333 if (DECL_SIZE (decl
) == 0)
335 DECL_SIZE (decl
) = TYPE_SIZE (type
);
336 DECL_SIZE_UNIT (decl
) = TYPE_SIZE_UNIT (type
);
338 else if (DECL_SIZE_UNIT (decl
) == 0)
339 DECL_SIZE_UNIT (decl
)
340 = fold_convert (sizetype
, size_binop (CEIL_DIV_EXPR
, DECL_SIZE (decl
),
343 if (code
!= FIELD_DECL
)
344 /* For non-fields, update the alignment from the type. */
345 do_type_align (type
, decl
);
347 /* For fields, it's a bit more complicated... */
349 bool old_user_align
= DECL_USER_ALIGN (decl
);
350 bool zero_bitfield
= false;
351 bool packed_p
= DECL_PACKED (decl
);
354 if (DECL_BIT_FIELD (decl
))
356 DECL_BIT_FIELD_TYPE (decl
) = type
;
358 /* A zero-length bit-field affects the alignment of the next
359 field. In essence such bit-fields are not influenced by
360 any packing due to #pragma pack or attribute packed. */
361 if (integer_zerop (DECL_SIZE (decl
))
362 && ! targetm
.ms_bitfield_layout_p (DECL_FIELD_CONTEXT (decl
)))
364 zero_bitfield
= true;
366 #ifdef PCC_BITFIELD_TYPE_MATTERS
367 if (PCC_BITFIELD_TYPE_MATTERS
)
368 do_type_align (type
, decl
);
372 #ifdef EMPTY_FIELD_BOUNDARY
373 if (EMPTY_FIELD_BOUNDARY
> DECL_ALIGN (decl
))
375 DECL_ALIGN (decl
) = EMPTY_FIELD_BOUNDARY
;
376 DECL_USER_ALIGN (decl
) = 0;
382 /* See if we can use an ordinary integer mode for a bit-field.
383 Conditions are: a fixed size that is correct for another mode
384 and occupying a complete byte or bytes on proper boundary. */
385 if (TYPE_SIZE (type
) != 0
386 && TREE_CODE (TYPE_SIZE (type
)) == INTEGER_CST
387 && GET_MODE_CLASS (TYPE_MODE (type
)) == MODE_INT
)
389 enum machine_mode xmode
390 = mode_for_size_tree (DECL_SIZE (decl
), MODE_INT
, 1);
394 || known_align
>= GET_MODE_ALIGNMENT (xmode
)))
396 DECL_ALIGN (decl
) = MAX (GET_MODE_ALIGNMENT (xmode
),
398 DECL_MODE (decl
) = xmode
;
399 DECL_BIT_FIELD (decl
) = 0;
403 /* Turn off DECL_BIT_FIELD if we won't need it set. */
404 if (TYPE_MODE (type
) == BLKmode
&& DECL_MODE (decl
) == BLKmode
405 && known_align
>= TYPE_ALIGN (type
)
406 && DECL_ALIGN (decl
) >= TYPE_ALIGN (type
))
407 DECL_BIT_FIELD (decl
) = 0;
409 else if (packed_p
&& DECL_USER_ALIGN (decl
))
410 /* Don't touch DECL_ALIGN. For other packed fields, go ahead and
411 round up; we'll reduce it again below. We want packing to
412 supersede USER_ALIGN inherited from the type, but defer to
413 alignment explicitly specified on the field decl. */;
415 do_type_align (type
, decl
);
417 /* If the field is of variable size, we can't misalign it since we
418 have no way to make a temporary to align the result. But this
419 isn't an issue if the decl is not addressable. Likewise if it
422 Note that do_type_align may set DECL_USER_ALIGN, so we need to
423 check old_user_align instead. */
426 && (DECL_NONADDRESSABLE_P (decl
)
427 || DECL_SIZE_UNIT (decl
) == 0
428 || TREE_CODE (DECL_SIZE_UNIT (decl
)) == INTEGER_CST
))
429 DECL_ALIGN (decl
) = MIN (DECL_ALIGN (decl
), BITS_PER_UNIT
);
431 if (! packed_p
&& ! DECL_USER_ALIGN (decl
))
433 /* Some targets (i.e. i386, VMS) limit struct field alignment
434 to a lower boundary than alignment of variables unless
435 it was overridden by attribute aligned. */
436 #ifdef BIGGEST_FIELD_ALIGNMENT
438 = MIN (DECL_ALIGN (decl
), (unsigned) BIGGEST_FIELD_ALIGNMENT
);
440 #ifdef ADJUST_FIELD_ALIGN
441 DECL_ALIGN (decl
) = ADJUST_FIELD_ALIGN (decl
, DECL_ALIGN (decl
));
446 mfa
= initial_max_fld_align
* BITS_PER_UNIT
;
448 mfa
= maximum_field_alignment
;
449 /* Should this be controlled by DECL_USER_ALIGN, too? */
451 DECL_ALIGN (decl
) = MIN (DECL_ALIGN (decl
), mfa
);
454 /* Evaluate nonconstant size only once, either now or as soon as safe. */
455 if (DECL_SIZE (decl
) != 0 && TREE_CODE (DECL_SIZE (decl
)) != INTEGER_CST
)
456 DECL_SIZE (decl
) = variable_size (DECL_SIZE (decl
));
457 if (DECL_SIZE_UNIT (decl
) != 0
458 && TREE_CODE (DECL_SIZE_UNIT (decl
)) != INTEGER_CST
)
459 DECL_SIZE_UNIT (decl
) = variable_size (DECL_SIZE_UNIT (decl
));
461 /* If requested, warn about definitions of large data objects. */
463 && (code
== VAR_DECL
|| code
== PARM_DECL
)
464 && ! DECL_EXTERNAL (decl
))
466 tree size
= DECL_SIZE_UNIT (decl
);
468 if (size
!= 0 && TREE_CODE (size
) == INTEGER_CST
469 && compare_tree_int (size
, larger_than_size
) > 0)
471 int size_as_int
= TREE_INT_CST_LOW (size
);
473 if (compare_tree_int (size
, size_as_int
) == 0)
474 warning (0, "size of %q+D is %d bytes", decl
, size_as_int
);
476 warning (0, "size of %q+D is larger than %wd bytes",
477 decl
, larger_than_size
);
481 /* If the RTL was already set, update its mode and mem attributes. */
484 PUT_MODE (rtl
, DECL_MODE (decl
));
485 SET_DECL_RTL (decl
, 0);
486 set_mem_attributes (rtl
, decl
, 1);
487 SET_DECL_RTL (decl
, rtl
);
491 /* Given a VAR_DECL, PARM_DECL or RESULT_DECL, clears the results of
492 a previous call to layout_decl and calls it again. */
495 relayout_decl (tree decl
)
497 DECL_SIZE (decl
) = DECL_SIZE_UNIT (decl
) = 0;
498 DECL_MODE (decl
) = VOIDmode
;
499 if (!DECL_USER_ALIGN (decl
))
500 DECL_ALIGN (decl
) = 0;
501 SET_DECL_RTL (decl
, 0);
503 layout_decl (decl
, 0);
506 /* Hook for a front-end function that can modify the record layout as needed
507 immediately before it is finalized. */
509 static void (*lang_adjust_rli
) (record_layout_info
) = 0;
512 set_lang_adjust_rli (void (*f
) (record_layout_info
))
517 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
518 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
519 is to be passed to all other layout functions for this record. It is the
520 responsibility of the caller to call `free' for the storage returned.
521 Note that garbage collection is not permitted until we finish laying
525 start_record_layout (tree t
)
527 record_layout_info rli
= xmalloc (sizeof (struct record_layout_info_s
));
531 /* If the type has a minimum specified alignment (via an attribute
532 declaration, for example) use it -- otherwise, start with a
533 one-byte alignment. */
534 rli
->record_align
= MAX (BITS_PER_UNIT
, TYPE_ALIGN (t
));
535 rli
->unpacked_align
= rli
->record_align
;
536 rli
->offset_align
= MAX (rli
->record_align
, BIGGEST_ALIGNMENT
);
538 #ifdef STRUCTURE_SIZE_BOUNDARY
539 /* Packed structures don't need to have minimum size. */
540 if (! TYPE_PACKED (t
))
544 /* #pragma pack overrides STRUCTURE_SIZE_BOUNDARY. */
545 tmp
= (unsigned) STRUCTURE_SIZE_BOUNDARY
;
546 if (maximum_field_alignment
!= 0)
547 tmp
= MIN (tmp
, maximum_field_alignment
);
548 rli
->record_align
= MAX (rli
->record_align
, tmp
);
552 rli
->offset
= size_zero_node
;
553 rli
->bitpos
= bitsize_zero_node
;
555 rli
->pending_statics
= 0;
556 rli
->packed_maybe_necessary
= 0;
557 rli
->remaining_in_alignment
= 0;
562 /* These four routines perform computations that convert between
563 the offset/bitpos forms and byte and bit offsets. */
566 bit_from_pos (tree offset
, tree bitpos
)
568 return size_binop (PLUS_EXPR
, bitpos
,
569 size_binop (MULT_EXPR
,
570 fold_convert (bitsizetype
, offset
),
575 byte_from_pos (tree offset
, tree bitpos
)
577 return size_binop (PLUS_EXPR
, offset
,
578 fold_convert (sizetype
,
579 size_binop (TRUNC_DIV_EXPR
, bitpos
,
580 bitsize_unit_node
)));
584 pos_from_bit (tree
*poffset
, tree
*pbitpos
, unsigned int off_align
,
587 *poffset
= size_binop (MULT_EXPR
,
588 fold_convert (sizetype
,
589 size_binop (FLOOR_DIV_EXPR
, pos
,
590 bitsize_int (off_align
))),
591 size_int (off_align
/ BITS_PER_UNIT
));
592 *pbitpos
= size_binop (FLOOR_MOD_EXPR
, pos
, bitsize_int (off_align
));
595 /* Given a pointer to bit and byte offsets and an offset alignment,
596 normalize the offsets so they are within the alignment. */
599 normalize_offset (tree
*poffset
, tree
*pbitpos
, unsigned int off_align
)
601 /* If the bit position is now larger than it should be, adjust it
603 if (compare_tree_int (*pbitpos
, off_align
) >= 0)
605 tree extra_aligns
= size_binop (FLOOR_DIV_EXPR
, *pbitpos
,
606 bitsize_int (off_align
));
609 = size_binop (PLUS_EXPR
, *poffset
,
610 size_binop (MULT_EXPR
,
611 fold_convert (sizetype
, extra_aligns
),
612 size_int (off_align
/ BITS_PER_UNIT
)));
615 = size_binop (FLOOR_MOD_EXPR
, *pbitpos
, bitsize_int (off_align
));
619 /* Print debugging information about the information in RLI. */
622 debug_rli (record_layout_info rli
)
624 print_node_brief (stderr
, "type", rli
->t
, 0);
625 print_node_brief (stderr
, "\noffset", rli
->offset
, 0);
626 print_node_brief (stderr
, " bitpos", rli
->bitpos
, 0);
628 fprintf (stderr
, "\naligns: rec = %u, unpack = %u, off = %u\n",
629 rli
->record_align
, rli
->unpacked_align
,
632 /* The ms_struct code is the only that uses this. */
633 if (targetm
.ms_bitfield_layout_p (rli
->t
))
634 fprintf (stderr
, "remaining in alignment = %u\n", rli
->remaining_in_alignment
);
636 if (rli
->packed_maybe_necessary
)
637 fprintf (stderr
, "packed may be necessary\n");
639 if (rli
->pending_statics
)
641 fprintf (stderr
, "pending statics:\n");
642 debug_tree (rli
->pending_statics
);
646 /* Given an RLI with a possibly-incremented BITPOS, adjust OFFSET and
647 BITPOS if necessary to keep BITPOS below OFFSET_ALIGN. */
650 normalize_rli (record_layout_info rli
)
652 normalize_offset (&rli
->offset
, &rli
->bitpos
, rli
->offset_align
);
655 /* Returns the size in bytes allocated so far. */
658 rli_size_unit_so_far (record_layout_info rli
)
660 return byte_from_pos (rli
->offset
, rli
->bitpos
);
663 /* Returns the size in bits allocated so far. */
666 rli_size_so_far (record_layout_info rli
)
668 return bit_from_pos (rli
->offset
, rli
->bitpos
);
671 /* FIELD is about to be added to RLI->T. The alignment (in bits) of
672 the next available location within the record is given by KNOWN_ALIGN.
673 Update the variable alignment fields in RLI, and return the alignment
674 to give the FIELD. */
677 update_alignment_for_field (record_layout_info rli
, tree field
,
678 unsigned int known_align
)
680 /* The alignment required for FIELD. */
681 unsigned int desired_align
;
682 /* The type of this field. */
683 tree type
= TREE_TYPE (field
);
684 /* True if the field was explicitly aligned by the user. */
688 /* Do not attempt to align an ERROR_MARK node */
689 if (TREE_CODE (type
) == ERROR_MARK
)
692 /* Lay out the field so we know what alignment it needs. */
693 layout_decl (field
, known_align
);
694 desired_align
= DECL_ALIGN (field
);
695 user_align
= DECL_USER_ALIGN (field
);
697 is_bitfield
= (type
!= error_mark_node
698 && DECL_BIT_FIELD_TYPE (field
)
699 && ! integer_zerop (TYPE_SIZE (type
)));
701 /* Record must have at least as much alignment as any field.
702 Otherwise, the alignment of the field within the record is
704 if (targetm
.ms_bitfield_layout_p (rli
->t
))
706 /* Here, the alignment of the underlying type of a bitfield can
707 affect the alignment of a record; even a zero-sized field
708 can do this. The alignment should be to the alignment of
709 the type, except that for zero-size bitfields this only
710 applies if there was an immediately prior, nonzero-size
711 bitfield. (That's the way it is, experimentally.) */
712 if ((!is_bitfield
&& !DECL_PACKED (field
))
713 || (!integer_zerop (DECL_SIZE (field
))
714 ? !DECL_PACKED (field
)
716 && DECL_BIT_FIELD_TYPE (rli
->prev_field
)
717 && ! integer_zerop (DECL_SIZE (rli
->prev_field
)))))
719 unsigned int type_align
= TYPE_ALIGN (type
);
720 type_align
= MAX (type_align
, desired_align
);
721 if (maximum_field_alignment
!= 0)
722 type_align
= MIN (type_align
, maximum_field_alignment
);
723 rli
->record_align
= MAX (rli
->record_align
, type_align
);
724 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
727 #ifdef PCC_BITFIELD_TYPE_MATTERS
728 else if (is_bitfield
&& PCC_BITFIELD_TYPE_MATTERS
)
730 /* Named bit-fields cause the entire structure to have the
731 alignment implied by their type. Some targets also apply the same
732 rules to unnamed bitfields. */
733 if (DECL_NAME (field
) != 0
734 || targetm
.align_anon_bitfield ())
736 unsigned int type_align
= TYPE_ALIGN (type
);
738 #ifdef ADJUST_FIELD_ALIGN
739 if (! TYPE_USER_ALIGN (type
))
740 type_align
= ADJUST_FIELD_ALIGN (field
, type_align
);
743 /* Targets might chose to handle unnamed and hence possibly
744 zero-width bitfield. Those are not influenced by #pragmas
745 or packed attributes. */
746 if (integer_zerop (DECL_SIZE (field
)))
748 if (initial_max_fld_align
)
749 type_align
= MIN (type_align
,
750 initial_max_fld_align
* BITS_PER_UNIT
);
752 else if (maximum_field_alignment
!= 0)
753 type_align
= MIN (type_align
, maximum_field_alignment
);
754 else if (DECL_PACKED (field
))
755 type_align
= MIN (type_align
, BITS_PER_UNIT
);
757 /* The alignment of the record is increased to the maximum
758 of the current alignment, the alignment indicated on the
759 field (i.e., the alignment specified by an __aligned__
760 attribute), and the alignment indicated by the type of
762 rli
->record_align
= MAX (rli
->record_align
, desired_align
);
763 rli
->record_align
= MAX (rli
->record_align
, type_align
);
766 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
767 user_align
|= TYPE_USER_ALIGN (type
);
773 rli
->record_align
= MAX (rli
->record_align
, desired_align
);
774 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
777 TYPE_USER_ALIGN (rli
->t
) |= user_align
;
779 return desired_align
;
782 /* Called from place_field to handle unions. */
785 place_union_field (record_layout_info rli
, tree field
)
787 update_alignment_for_field (rli
, field
, /*known_align=*/0);
789 DECL_FIELD_OFFSET (field
) = size_zero_node
;
790 DECL_FIELD_BIT_OFFSET (field
) = bitsize_zero_node
;
791 SET_DECL_OFFSET_ALIGN (field
, BIGGEST_ALIGNMENT
);
793 /* If this is an ERROR_MARK return *after* having set the
794 field at the start of the union. This helps when parsing
796 if (TREE_CODE (TREE_TYPE (field
)) == ERROR_MARK
)
799 /* We assume the union's size will be a multiple of a byte so we don't
800 bother with BITPOS. */
801 if (TREE_CODE (rli
->t
) == UNION_TYPE
)
802 rli
->offset
= size_binop (MAX_EXPR
, rli
->offset
, DECL_SIZE_UNIT (field
));
803 else if (TREE_CODE (rli
->t
) == QUAL_UNION_TYPE
)
804 rli
->offset
= fold_build3 (COND_EXPR
, sizetype
,
805 DECL_QUALIFIER (field
),
806 DECL_SIZE_UNIT (field
), rli
->offset
);
809 #if defined (PCC_BITFIELD_TYPE_MATTERS) || defined (BITFIELD_NBYTES_LIMITED)
810 /* A bitfield of SIZE with a required access alignment of ALIGN is allocated
811 at BYTE_OFFSET / BIT_OFFSET. Return nonzero if the field would span more
812 units of alignment than the underlying TYPE. */
814 excess_unit_span (HOST_WIDE_INT byte_offset
, HOST_WIDE_INT bit_offset
,
815 HOST_WIDE_INT size
, HOST_WIDE_INT align
, tree type
)
817 /* Note that the calculation of OFFSET might overflow; we calculate it so
818 that we still get the right result as long as ALIGN is a power of two. */
819 unsigned HOST_WIDE_INT offset
= byte_offset
* BITS_PER_UNIT
+ bit_offset
;
821 offset
= offset
% align
;
822 return ((offset
+ size
+ align
- 1) / align
823 > ((unsigned HOST_WIDE_INT
) tree_low_cst (TYPE_SIZE (type
), 1)
828 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
829 is a FIELD_DECL to be added after those fields already present in
830 T. (FIELD is not actually added to the TYPE_FIELDS list here;
831 callers that desire that behavior must manually perform that step.) */
834 place_field (record_layout_info rli
, tree field
)
836 /* The alignment required for FIELD. */
837 unsigned int desired_align
;
838 /* The alignment FIELD would have if we just dropped it into the
839 record as it presently stands. */
840 unsigned int known_align
;
841 unsigned int actual_align
;
842 /* The type of this field. */
843 tree type
= TREE_TYPE (field
);
845 gcc_assert (TREE_CODE (field
) != ERROR_MARK
);
847 /* If FIELD is static, then treat it like a separate variable, not
848 really like a structure field. If it is a FUNCTION_DECL, it's a
849 method. In both cases, all we do is lay out the decl, and we do
850 it *after* the record is laid out. */
851 if (TREE_CODE (field
) == VAR_DECL
)
853 rli
->pending_statics
= tree_cons (NULL_TREE
, field
,
854 rli
->pending_statics
);
858 /* Enumerators and enum types which are local to this class need not
859 be laid out. Likewise for initialized constant fields. */
860 else if (TREE_CODE (field
) != FIELD_DECL
)
863 /* Unions are laid out very differently than records, so split
864 that code off to another function. */
865 else if (TREE_CODE (rli
->t
) != RECORD_TYPE
)
867 place_union_field (rli
, field
);
871 else if (TREE_CODE (type
) == ERROR_MARK
)
873 /* Place this field at the current allocation position, so we
874 maintain monotonicity. */
875 DECL_FIELD_OFFSET (field
) = rli
->offset
;
876 DECL_FIELD_BIT_OFFSET (field
) = rli
->bitpos
;
877 SET_DECL_OFFSET_ALIGN (field
, rli
->offset_align
);
881 /* Work out the known alignment so far. Note that A & (-A) is the
882 value of the least-significant bit in A that is one. */
883 if (! integer_zerop (rli
->bitpos
))
884 known_align
= (tree_low_cst (rli
->bitpos
, 1)
885 & - tree_low_cst (rli
->bitpos
, 1));
886 else if (integer_zerop (rli
->offset
))
888 else if (host_integerp (rli
->offset
, 1))
889 known_align
= (BITS_PER_UNIT
890 * (tree_low_cst (rli
->offset
, 1)
891 & - tree_low_cst (rli
->offset
, 1)));
893 known_align
= rli
->offset_align
;
895 desired_align
= update_alignment_for_field (rli
, field
, known_align
);
896 if (known_align
== 0)
897 known_align
= MAX (BIGGEST_ALIGNMENT
, rli
->record_align
);
899 if (warn_packed
&& DECL_PACKED (field
))
901 if (known_align
>= TYPE_ALIGN (type
))
903 if (TYPE_ALIGN (type
) > desired_align
)
905 if (STRICT_ALIGNMENT
)
906 warning (OPT_Wattributes
, "packed attribute causes "
907 "inefficient alignment for %q+D", field
);
909 warning (OPT_Wattributes
, "packed attribute is "
910 "unnecessary for %q+D", field
);
914 rli
->packed_maybe_necessary
= 1;
917 /* Does this field automatically have alignment it needs by virtue
918 of the fields that precede it and the record's own alignment?
919 We already align ms_struct fields, so don't re-align them. */
920 if (known_align
< desired_align
921 && !targetm
.ms_bitfield_layout_p (rli
->t
))
923 /* No, we need to skip space before this field.
924 Bump the cumulative size to multiple of field alignment. */
926 warning (OPT_Wpadded
, "padding struct to align %q+D", field
);
928 /* If the alignment is still within offset_align, just align
930 if (desired_align
< rli
->offset_align
)
931 rli
->bitpos
= round_up (rli
->bitpos
, desired_align
);
934 /* First adjust OFFSET by the partial bits, then align. */
936 = size_binop (PLUS_EXPR
, rli
->offset
,
937 fold_convert (sizetype
,
938 size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
939 bitsize_unit_node
)));
940 rli
->bitpos
= bitsize_zero_node
;
942 rli
->offset
= round_up (rli
->offset
, desired_align
/ BITS_PER_UNIT
);
945 if (! TREE_CONSTANT (rli
->offset
))
946 rli
->offset_align
= desired_align
;
950 /* Handle compatibility with PCC. Note that if the record has any
951 variable-sized fields, we need not worry about compatibility. */
952 #ifdef PCC_BITFIELD_TYPE_MATTERS
953 if (PCC_BITFIELD_TYPE_MATTERS
954 && ! targetm
.ms_bitfield_layout_p (rli
->t
)
955 && TREE_CODE (field
) == FIELD_DECL
956 && type
!= error_mark_node
957 && DECL_BIT_FIELD (field
)
958 && ! DECL_PACKED (field
)
959 && maximum_field_alignment
== 0
960 && ! integer_zerop (DECL_SIZE (field
))
961 && host_integerp (DECL_SIZE (field
), 1)
962 && host_integerp (rli
->offset
, 1)
963 && host_integerp (TYPE_SIZE (type
), 1))
965 unsigned int type_align
= TYPE_ALIGN (type
);
966 tree dsize
= DECL_SIZE (field
);
967 HOST_WIDE_INT field_size
= tree_low_cst (dsize
, 1);
968 HOST_WIDE_INT offset
= tree_low_cst (rli
->offset
, 0);
969 HOST_WIDE_INT bit_offset
= tree_low_cst (rli
->bitpos
, 0);
971 #ifdef ADJUST_FIELD_ALIGN
972 if (! TYPE_USER_ALIGN (type
))
973 type_align
= ADJUST_FIELD_ALIGN (field
, type_align
);
976 /* A bit field may not span more units of alignment of its type
977 than its type itself. Advance to next boundary if necessary. */
978 if (excess_unit_span (offset
, bit_offset
, field_size
, type_align
, type
))
979 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
981 TYPE_USER_ALIGN (rli
->t
) |= TYPE_USER_ALIGN (type
);
985 #ifdef BITFIELD_NBYTES_LIMITED
986 if (BITFIELD_NBYTES_LIMITED
987 && ! targetm
.ms_bitfield_layout_p (rli
->t
)
988 && TREE_CODE (field
) == FIELD_DECL
989 && type
!= error_mark_node
990 && DECL_BIT_FIELD_TYPE (field
)
991 && ! DECL_PACKED (field
)
992 && ! integer_zerop (DECL_SIZE (field
))
993 && host_integerp (DECL_SIZE (field
), 1)
994 && host_integerp (rli
->offset
, 1)
995 && host_integerp (TYPE_SIZE (type
), 1))
997 unsigned int type_align
= TYPE_ALIGN (type
);
998 tree dsize
= DECL_SIZE (field
);
999 HOST_WIDE_INT field_size
= tree_low_cst (dsize
, 1);
1000 HOST_WIDE_INT offset
= tree_low_cst (rli
->offset
, 0);
1001 HOST_WIDE_INT bit_offset
= tree_low_cst (rli
->bitpos
, 0);
1003 #ifdef ADJUST_FIELD_ALIGN
1004 if (! TYPE_USER_ALIGN (type
))
1005 type_align
= ADJUST_FIELD_ALIGN (field
, type_align
);
1008 if (maximum_field_alignment
!= 0)
1009 type_align
= MIN (type_align
, maximum_field_alignment
);
1010 /* ??? This test is opposite the test in the containing if
1011 statement, so this code is unreachable currently. */
1012 else if (DECL_PACKED (field
))
1013 type_align
= MIN (type_align
, BITS_PER_UNIT
);
1015 /* A bit field may not span the unit of alignment of its type.
1016 Advance to next boundary if necessary. */
1017 if (excess_unit_span (offset
, bit_offset
, field_size
, type_align
, type
))
1018 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1020 TYPE_USER_ALIGN (rli
->t
) |= TYPE_USER_ALIGN (type
);
1024 /* See the docs for TARGET_MS_BITFIELD_LAYOUT_P for details.
1026 When a bit field is inserted into a packed record, the whole
1027 size of the underlying type is used by one or more same-size
1028 adjacent bitfields. (That is, if its long:3, 32 bits is
1029 used in the record, and any additional adjacent long bitfields are
1030 packed into the same chunk of 32 bits. However, if the size
1031 changes, a new field of that size is allocated.) In an unpacked
1032 record, this is the same as using alignment, but not equivalent
1035 Note: for compatibility, we use the type size, not the type alignment
1036 to determine alignment, since that matches the documentation */
1038 if (targetm
.ms_bitfield_layout_p (rli
->t
))
1040 tree prev_saved
= rli
->prev_field
;
1041 tree prev_type
= prev_saved
? DECL_BIT_FIELD_TYPE (prev_saved
) : NULL
;
1043 /* This is a bitfield if it exists. */
1044 if (rli
->prev_field
)
1046 /* If both are bitfields, nonzero, and the same size, this is
1047 the middle of a run. Zero declared size fields are special
1048 and handled as "end of run". (Note: it's nonzero declared
1049 size, but equal type sizes!) (Since we know that both
1050 the current and previous fields are bitfields by the
1051 time we check it, DECL_SIZE must be present for both.) */
1052 if (DECL_BIT_FIELD_TYPE (field
)
1053 && !integer_zerop (DECL_SIZE (field
))
1054 && !integer_zerop (DECL_SIZE (rli
->prev_field
))
1055 && host_integerp (DECL_SIZE (rli
->prev_field
), 0)
1056 && host_integerp (TYPE_SIZE (type
), 0)
1057 && simple_cst_equal (TYPE_SIZE (type
), TYPE_SIZE (prev_type
)))
1059 /* We're in the middle of a run of equal type size fields; make
1060 sure we realign if we run out of bits. (Not decl size,
1062 HOST_WIDE_INT bitsize
= tree_low_cst (DECL_SIZE (field
), 1);
1064 if (rli
->remaining_in_alignment
< bitsize
)
1066 HOST_WIDE_INT typesize
= tree_low_cst (TYPE_SIZE (type
), 1);
1068 /* out of bits; bump up to next 'word'. */
1070 = size_binop (PLUS_EXPR
, rli
->bitpos
,
1071 bitsize_int (rli
->remaining_in_alignment
));
1072 rli
->prev_field
= field
;
1073 if (typesize
< bitsize
)
1074 rli
->remaining_in_alignment
= 0;
1076 rli
->remaining_in_alignment
= typesize
- bitsize
;
1079 rli
->remaining_in_alignment
-= bitsize
;
1083 /* End of a run: if leaving a run of bitfields of the same type
1084 size, we have to "use up" the rest of the bits of the type
1087 Compute the new position as the sum of the size for the prior
1088 type and where we first started working on that type.
1089 Note: since the beginning of the field was aligned then
1090 of course the end will be too. No round needed. */
1092 if (!integer_zerop (DECL_SIZE (rli
->prev_field
)))
1095 = size_binop (PLUS_EXPR
, rli
->bitpos
,
1096 bitsize_int (rli
->remaining_in_alignment
));
1099 /* We "use up" size zero fields; the code below should behave
1100 as if the prior field was not a bitfield. */
1103 /* Cause a new bitfield to be captured, either this time (if
1104 currently a bitfield) or next time we see one. */
1105 if (!DECL_BIT_FIELD_TYPE(field
)
1106 || integer_zerop (DECL_SIZE (field
)))
1107 rli
->prev_field
= NULL
;
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
), TYPE_SIZE (prev_type
))
1128 : !integer_zerop (DECL_SIZE (field
)) ))
1130 /* Never smaller than a byte for compatibility. */
1131 unsigned int type_align
= BITS_PER_UNIT
;
1133 /* (When not a bitfield), we could be seeing a flex array (with
1134 no DECL_SIZE). Since we won't be using remaining_in_alignment
1135 until we see a bitfield (and come by here again) we just skip
1137 if (DECL_SIZE (field
) != NULL
1138 && host_integerp (TYPE_SIZE (TREE_TYPE (field
)), 0)
1139 && host_integerp (DECL_SIZE (field
), 0))
1141 HOST_WIDE_INT bitsize
= tree_low_cst (DECL_SIZE (field
), 1);
1142 HOST_WIDE_INT typesize
1143 = tree_low_cst (TYPE_SIZE (TREE_TYPE (field
)), 1);
1145 if (typesize
< bitsize
)
1146 rli
->remaining_in_alignment
= 0;
1148 rli
->remaining_in_alignment
= typesize
- bitsize
;
1151 /* Now align (conventionally) for the new type. */
1152 type_align
= TYPE_ALIGN (TREE_TYPE (field
));
1154 if (maximum_field_alignment
!= 0)
1155 type_align
= MIN (type_align
, maximum_field_alignment
);
1157 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1159 /* If we really aligned, don't allow subsequent bitfields
1161 rli
->prev_field
= NULL
;
1165 /* Offset so far becomes the position of this field after normalizing. */
1166 normalize_rli (rli
);
1167 DECL_FIELD_OFFSET (field
) = rli
->offset
;
1168 DECL_FIELD_BIT_OFFSET (field
) = rli
->bitpos
;
1169 SET_DECL_OFFSET_ALIGN (field
, rli
->offset_align
);
1171 /* If this field ended up more aligned than we thought it would be (we
1172 approximate this by seeing if its position changed), lay out the field
1173 again; perhaps we can use an integral mode for it now. */
1174 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field
)))
1175 actual_align
= (tree_low_cst (DECL_FIELD_BIT_OFFSET (field
), 1)
1176 & - tree_low_cst (DECL_FIELD_BIT_OFFSET (field
), 1));
1177 else if (integer_zerop (DECL_FIELD_OFFSET (field
)))
1178 actual_align
= MAX (BIGGEST_ALIGNMENT
, rli
->record_align
);
1179 else if (host_integerp (DECL_FIELD_OFFSET (field
), 1))
1180 actual_align
= (BITS_PER_UNIT
1181 * (tree_low_cst (DECL_FIELD_OFFSET (field
), 1)
1182 & - tree_low_cst (DECL_FIELD_OFFSET (field
), 1)));
1184 actual_align
= DECL_OFFSET_ALIGN (field
);
1185 /* ACTUAL_ALIGN is still the actual alignment *within the record* .
1186 store / extract bit field operations will check the alignment of the
1187 record against the mode of bit fields. */
1189 if (known_align
!= actual_align
)
1190 layout_decl (field
, actual_align
);
1192 if (rli
->prev_field
== NULL
&& DECL_BIT_FIELD_TYPE (field
))
1193 rli
->prev_field
= field
;
1195 /* Now add size of this field to the size of the record. If the size is
1196 not constant, treat the field as being a multiple of bytes and just
1197 adjust the offset, resetting the bit position. Otherwise, apportion the
1198 size amongst the bit position and offset. First handle the case of an
1199 unspecified size, which can happen when we have an invalid nested struct
1200 definition, such as struct j { struct j { int i; } }. The error message
1201 is printed in finish_struct. */
1202 if (DECL_SIZE (field
) == 0)
1204 else if (TREE_CODE (DECL_SIZE (field
)) != INTEGER_CST
1205 || TREE_OVERFLOW (DECL_SIZE (field
)))
1208 = size_binop (PLUS_EXPR
, rli
->offset
,
1209 fold_convert (sizetype
,
1210 size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
1211 bitsize_unit_node
)));
1213 = size_binop (PLUS_EXPR
, rli
->offset
, DECL_SIZE_UNIT (field
));
1214 rli
->bitpos
= bitsize_zero_node
;
1215 rli
->offset_align
= MIN (rli
->offset_align
, desired_align
);
1217 else if (targetm
.ms_bitfield_layout_p (rli
->t
))
1219 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
, DECL_SIZE (field
));
1221 /* If we ended a bitfield before the full length of the type then
1222 pad the struct out to the full length of the last type. */
1223 if ((TREE_CHAIN (field
) == NULL
1224 || TREE_CODE (TREE_CHAIN (field
)) != FIELD_DECL
)
1225 && DECL_BIT_FIELD_TYPE (field
)
1226 && !integer_zerop (DECL_SIZE (field
)))
1227 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
,
1228 bitsize_int (rli
->remaining_in_alignment
));
1230 normalize_rli (rli
);
1234 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
, DECL_SIZE (field
));
1235 normalize_rli (rli
);
1239 /* Assuming that all the fields have been laid out, this function uses
1240 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
1241 indicated by RLI. */
1244 finalize_record_size (record_layout_info rli
)
1246 tree unpadded_size
, unpadded_size_unit
;
1248 /* Now we want just byte and bit offsets, so set the offset alignment
1249 to be a byte and then normalize. */
1250 rli
->offset_align
= BITS_PER_UNIT
;
1251 normalize_rli (rli
);
1253 /* Determine the desired alignment. */
1254 #ifdef ROUND_TYPE_ALIGN
1255 TYPE_ALIGN (rli
->t
) = ROUND_TYPE_ALIGN (rli
->t
, TYPE_ALIGN (rli
->t
),
1258 TYPE_ALIGN (rli
->t
) = MAX (TYPE_ALIGN (rli
->t
), rli
->record_align
);
1261 /* Compute the size so far. Be sure to allow for extra bits in the
1262 size in bytes. We have guaranteed above that it will be no more
1263 than a single byte. */
1264 unpadded_size
= rli_size_so_far (rli
);
1265 unpadded_size_unit
= rli_size_unit_so_far (rli
);
1266 if (! integer_zerop (rli
->bitpos
))
1268 = size_binop (PLUS_EXPR
, unpadded_size_unit
, size_one_node
);
1270 /* Round the size up to be a multiple of the required alignment. */
1271 TYPE_SIZE (rli
->t
) = round_up (unpadded_size
, TYPE_ALIGN (rli
->t
));
1272 TYPE_SIZE_UNIT (rli
->t
)
1273 = round_up (unpadded_size_unit
, TYPE_ALIGN_UNIT (rli
->t
));
1275 if (TREE_CONSTANT (unpadded_size
)
1276 && simple_cst_equal (unpadded_size
, TYPE_SIZE (rli
->t
)) == 0)
1277 warning (OPT_Wpadded
, "padding struct size to alignment boundary");
1279 if (warn_packed
&& TREE_CODE (rli
->t
) == RECORD_TYPE
1280 && TYPE_PACKED (rli
->t
) && ! rli
->packed_maybe_necessary
1281 && TREE_CONSTANT (unpadded_size
))
1285 #ifdef ROUND_TYPE_ALIGN
1287 = ROUND_TYPE_ALIGN (rli
->t
, TYPE_ALIGN (rli
->t
), rli
->unpacked_align
);
1289 rli
->unpacked_align
= MAX (TYPE_ALIGN (rli
->t
), rli
->unpacked_align
);
1292 unpacked_size
= round_up (TYPE_SIZE (rli
->t
), rli
->unpacked_align
);
1293 if (simple_cst_equal (unpacked_size
, TYPE_SIZE (rli
->t
)))
1295 TYPE_PACKED (rli
->t
) = 0;
1297 if (TYPE_NAME (rli
->t
))
1301 if (TREE_CODE (TYPE_NAME (rli
->t
)) == IDENTIFIER_NODE
)
1302 name
= IDENTIFIER_POINTER (TYPE_NAME (rli
->t
));
1304 name
= IDENTIFIER_POINTER (DECL_NAME (TYPE_NAME (rli
->t
)));
1306 if (STRICT_ALIGNMENT
)
1307 warning (OPT_Wpacked
, "packed attribute causes inefficient "
1308 "alignment for %qs", name
);
1310 warning (OPT_Wpacked
,
1311 "packed attribute is unnecessary for %qs", name
);
1315 if (STRICT_ALIGNMENT
)
1316 warning (OPT_Wpacked
,
1317 "packed attribute causes inefficient alignment");
1319 warning (OPT_Wpacked
, "packed attribute is unnecessary");
1325 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
1328 compute_record_mode (tree type
)
1331 enum machine_mode mode
= VOIDmode
;
1333 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
1334 However, if possible, we use a mode that fits in a register
1335 instead, in order to allow for better optimization down the
1337 TYPE_MODE (type
) = BLKmode
;
1339 if (! host_integerp (TYPE_SIZE (type
), 1))
1342 /* A record which has any BLKmode members must itself be
1343 BLKmode; it can't go in a register. Unless the member is
1344 BLKmode only because it isn't aligned. */
1345 for (field
= TYPE_FIELDS (type
); field
; field
= TREE_CHAIN (field
))
1347 if (TREE_CODE (field
) != FIELD_DECL
)
1350 if (TREE_CODE (TREE_TYPE (field
)) == ERROR_MARK
1351 || (TYPE_MODE (TREE_TYPE (field
)) == BLKmode
1352 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field
))
1353 && !(TYPE_SIZE (TREE_TYPE (field
)) != 0
1354 && integer_zerop (TYPE_SIZE (TREE_TYPE (field
)))))
1355 || ! host_integerp (bit_position (field
), 1)
1356 || DECL_SIZE (field
) == 0
1357 || ! host_integerp (DECL_SIZE (field
), 1))
1360 /* If this field is the whole struct, remember its mode so
1361 that, say, we can put a double in a class into a DF
1362 register instead of forcing it to live in the stack. */
1363 if (simple_cst_equal (TYPE_SIZE (type
), DECL_SIZE (field
)))
1364 mode
= DECL_MODE (field
);
1366 #ifdef MEMBER_TYPE_FORCES_BLK
1367 /* With some targets, eg. c4x, it is sub-optimal
1368 to access an aligned BLKmode structure as a scalar. */
1370 if (MEMBER_TYPE_FORCES_BLK (field
, mode
))
1372 #endif /* MEMBER_TYPE_FORCES_BLK */
1375 /* If we only have one real field; use its mode if that mode's size
1376 matches the type's size. This only applies to RECORD_TYPE. This
1377 does not apply to unions. */
1378 if (TREE_CODE (type
) == RECORD_TYPE
&& mode
!= VOIDmode
1379 && host_integerp (TYPE_SIZE (type
), 1)
1380 && GET_MODE_BITSIZE (mode
) == TREE_INT_CST_LOW (TYPE_SIZE (type
)))
1381 TYPE_MODE (type
) = mode
;
1383 TYPE_MODE (type
) = mode_for_size_tree (TYPE_SIZE (type
), MODE_INT
, 1);
1385 /* If structure's known alignment is less than what the scalar
1386 mode would need, and it matters, then stick with BLKmode. */
1387 if (TYPE_MODE (type
) != BLKmode
1389 && ! (TYPE_ALIGN (type
) >= BIGGEST_ALIGNMENT
1390 || TYPE_ALIGN (type
) >= GET_MODE_ALIGNMENT (TYPE_MODE (type
))))
1392 /* If this is the only reason this type is BLKmode, then
1393 don't force containing types to be BLKmode. */
1394 TYPE_NO_FORCE_BLK (type
) = 1;
1395 TYPE_MODE (type
) = BLKmode
;
1399 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1403 finalize_type_size (tree type
)
1405 /* Normally, use the alignment corresponding to the mode chosen.
1406 However, where strict alignment is not required, avoid
1407 over-aligning structures, since most compilers do not do this
1410 if (TYPE_MODE (type
) != BLKmode
&& TYPE_MODE (type
) != VOIDmode
1411 && (STRICT_ALIGNMENT
1412 || (TREE_CODE (type
) != RECORD_TYPE
&& TREE_CODE (type
) != UNION_TYPE
1413 && TREE_CODE (type
) != QUAL_UNION_TYPE
1414 && TREE_CODE (type
) != ARRAY_TYPE
)))
1416 unsigned mode_align
= GET_MODE_ALIGNMENT (TYPE_MODE (type
));
1418 /* Don't override a larger alignment requirement coming from a user
1419 alignment of one of the fields. */
1420 if (mode_align
>= TYPE_ALIGN (type
))
1422 TYPE_ALIGN (type
) = mode_align
;
1423 TYPE_USER_ALIGN (type
) = 0;
1427 /* Do machine-dependent extra alignment. */
1428 #ifdef ROUND_TYPE_ALIGN
1430 = ROUND_TYPE_ALIGN (type
, TYPE_ALIGN (type
), BITS_PER_UNIT
);
1433 /* If we failed to find a simple way to calculate the unit size
1434 of the type, find it by division. */
1435 if (TYPE_SIZE_UNIT (type
) == 0 && TYPE_SIZE (type
) != 0)
1436 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1437 result will fit in sizetype. We will get more efficient code using
1438 sizetype, so we force a conversion. */
1439 TYPE_SIZE_UNIT (type
)
1440 = fold_convert (sizetype
,
1441 size_binop (FLOOR_DIV_EXPR
, TYPE_SIZE (type
),
1442 bitsize_unit_node
));
1444 if (TYPE_SIZE (type
) != 0)
1446 TYPE_SIZE (type
) = round_up (TYPE_SIZE (type
), TYPE_ALIGN (type
));
1447 TYPE_SIZE_UNIT (type
) = round_up (TYPE_SIZE_UNIT (type
),
1448 TYPE_ALIGN_UNIT (type
));
1451 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1452 if (TYPE_SIZE (type
) != 0 && TREE_CODE (TYPE_SIZE (type
)) != INTEGER_CST
)
1453 TYPE_SIZE (type
) = variable_size (TYPE_SIZE (type
));
1454 if (TYPE_SIZE_UNIT (type
) != 0
1455 && TREE_CODE (TYPE_SIZE_UNIT (type
)) != INTEGER_CST
)
1456 TYPE_SIZE_UNIT (type
) = variable_size (TYPE_SIZE_UNIT (type
));
1458 /* Also layout any other variants of the type. */
1459 if (TYPE_NEXT_VARIANT (type
)
1460 || type
!= TYPE_MAIN_VARIANT (type
))
1463 /* Record layout info of this variant. */
1464 tree size
= TYPE_SIZE (type
);
1465 tree size_unit
= TYPE_SIZE_UNIT (type
);
1466 unsigned int align
= TYPE_ALIGN (type
);
1467 unsigned int user_align
= TYPE_USER_ALIGN (type
);
1468 enum machine_mode mode
= TYPE_MODE (type
);
1470 /* Copy it into all variants. */
1471 for (variant
= TYPE_MAIN_VARIANT (type
);
1473 variant
= TYPE_NEXT_VARIANT (variant
))
1475 TYPE_SIZE (variant
) = size
;
1476 TYPE_SIZE_UNIT (variant
) = size_unit
;
1477 TYPE_ALIGN (variant
) = align
;
1478 TYPE_USER_ALIGN (variant
) = user_align
;
1479 TYPE_MODE (variant
) = mode
;
1484 /* Do all of the work required to layout the type indicated by RLI,
1485 once the fields have been laid out. This function will call `free'
1486 for RLI, unless FREE_P is false. Passing a value other than false
1487 for FREE_P is bad practice; this option only exists to support the
1491 finish_record_layout (record_layout_info rli
, int free_p
)
1495 /* Compute the final size. */
1496 finalize_record_size (rli
);
1498 /* Compute the TYPE_MODE for the record. */
1499 compute_record_mode (rli
->t
);
1501 /* Perform any last tweaks to the TYPE_SIZE, etc. */
1502 finalize_type_size (rli
->t
);
1504 /* Propagate TYPE_PACKED to variants. With C++ templates,
1505 handle_packed_attribute is too early to do this. */
1506 for (variant
= TYPE_NEXT_VARIANT (rli
->t
); variant
;
1507 variant
= TYPE_NEXT_VARIANT (variant
))
1508 TYPE_PACKED (variant
) = TYPE_PACKED (rli
->t
);
1510 /* Lay out any static members. This is done now because their type
1511 may use the record's type. */
1512 while (rli
->pending_statics
)
1514 layout_decl (TREE_VALUE (rli
->pending_statics
), 0);
1515 rli
->pending_statics
= TREE_CHAIN (rli
->pending_statics
);
1524 /* Finish processing a builtin RECORD_TYPE type TYPE. It's name is
1525 NAME, its fields are chained in reverse on FIELDS.
1527 If ALIGN_TYPE is non-null, it is given the same alignment as
1531 finish_builtin_struct (tree type
, const char *name
, tree fields
,
1536 for (tail
= NULL_TREE
; fields
; tail
= fields
, fields
= next
)
1538 DECL_FIELD_CONTEXT (fields
) = type
;
1539 next
= TREE_CHAIN (fields
);
1540 TREE_CHAIN (fields
) = tail
;
1542 TYPE_FIELDS (type
) = tail
;
1546 TYPE_ALIGN (type
) = TYPE_ALIGN (align_type
);
1547 TYPE_USER_ALIGN (type
) = TYPE_USER_ALIGN (align_type
);
1551 #if 0 /* not yet, should get fixed properly later */
1552 TYPE_NAME (type
) = make_type_decl (get_identifier (name
), type
);
1554 TYPE_NAME (type
) = build_decl (TYPE_DECL
, get_identifier (name
), type
);
1556 TYPE_STUB_DECL (type
) = TYPE_NAME (type
);
1557 layout_decl (TYPE_NAME (type
), 0);
1560 /* Calculate the mode, size, and alignment for TYPE.
1561 For an array type, calculate the element separation as well.
1562 Record TYPE on the chain of permanent or temporary types
1563 so that dbxout will find out about it.
1565 TYPE_SIZE of a type is nonzero if the type has been laid out already.
1566 layout_type does nothing on such a type.
1568 If the type is incomplete, its TYPE_SIZE remains zero. */
1571 layout_type (tree type
)
1575 if (type
== error_mark_node
)
1578 /* Do nothing if type has been laid out before. */
1579 if (TYPE_SIZE (type
))
1582 switch (TREE_CODE (type
))
1585 /* This kind of type is the responsibility
1586 of the language-specific code. */
1589 case BOOLEAN_TYPE
: /* Used for Java, Pascal, and Chill. */
1590 if (TYPE_PRECISION (type
) == 0)
1591 TYPE_PRECISION (type
) = 1; /* default to one byte/boolean. */
1593 /* ... fall through ... */
1597 if (TREE_CODE (TYPE_MIN_VALUE (type
)) == INTEGER_CST
1598 && tree_int_cst_sgn (TYPE_MIN_VALUE (type
)) >= 0)
1599 TYPE_UNSIGNED (type
) = 1;
1601 TYPE_MODE (type
) = smallest_mode_for_size (TYPE_PRECISION (type
),
1603 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
1604 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
1608 TYPE_MODE (type
) = mode_for_size (TYPE_PRECISION (type
), MODE_FLOAT
, 0);
1609 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
1610 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
1613 case FIXED_POINT_TYPE
:
1614 /* TYPE_MODE (type) has been set already. */
1615 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
1616 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
1620 TYPE_UNSIGNED (type
) = TYPE_UNSIGNED (TREE_TYPE (type
));
1622 = mode_for_size (2 * TYPE_PRECISION (TREE_TYPE (type
)),
1623 (TREE_CODE (TREE_TYPE (type
)) == REAL_TYPE
1624 ? MODE_COMPLEX_FLOAT
: MODE_COMPLEX_INT
),
1626 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
1627 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
1632 int nunits
= TYPE_VECTOR_SUBPARTS (type
);
1633 tree innertype
= TREE_TYPE (type
);
1635 gcc_assert (!(nunits
& (nunits
- 1)));
1637 /* Find an appropriate mode for the vector type. */
1638 if (TYPE_MODE (type
) == VOIDmode
)
1640 enum machine_mode innermode
= TYPE_MODE (innertype
);
1641 enum machine_mode mode
;
1643 /* First, look for a supported vector type. */
1644 if (SCALAR_FLOAT_MODE_P (innermode
))
1645 mode
= MIN_MODE_VECTOR_FLOAT
;
1646 else if (SCALAR_FRACT_MODE_P (innermode
))
1647 mode
= MIN_MODE_VECTOR_FRACT
;
1648 else if (SCALAR_UFRACT_MODE_P (innermode
))
1649 mode
= MIN_MODE_VECTOR_UFRACT
;
1650 else if (SCALAR_ACCUM_MODE_P (innermode
))
1651 mode
= MIN_MODE_VECTOR_ACCUM
;
1652 else if (SCALAR_UACCUM_MODE_P (innermode
))
1653 mode
= MIN_MODE_VECTOR_UACCUM
;
1655 mode
= MIN_MODE_VECTOR_INT
;
1657 for (; mode
!= VOIDmode
; mode
= GET_MODE_WIDER_MODE (mode
))
1658 if (GET_MODE_NUNITS (mode
) == nunits
1659 && GET_MODE_INNER (mode
) == innermode
1660 && targetm
.vector_mode_supported_p (mode
))
1663 /* For integers, try mapping it to a same-sized scalar mode. */
1664 if (mode
== VOIDmode
1665 && GET_MODE_CLASS (innermode
) == MODE_INT
)
1666 mode
= mode_for_size (nunits
* GET_MODE_BITSIZE (innermode
),
1669 if (mode
== VOIDmode
|| !have_regs_of_mode
[mode
])
1670 TYPE_MODE (type
) = BLKmode
;
1672 TYPE_MODE (type
) = mode
;
1675 TYPE_SATURATING (type
) = TYPE_SATURATING (TREE_TYPE (type
));
1676 TYPE_UNSIGNED (type
) = TYPE_UNSIGNED (TREE_TYPE (type
));
1677 TYPE_SIZE_UNIT (type
) = int_const_binop (MULT_EXPR
,
1678 TYPE_SIZE_UNIT (innertype
),
1679 size_int (nunits
), 0);
1680 TYPE_SIZE (type
) = int_const_binop (MULT_EXPR
, TYPE_SIZE (innertype
),
1681 bitsize_int (nunits
), 0);
1683 /* Always naturally align vectors. This prevents ABI changes
1684 depending on whether or not native vector modes are supported. */
1685 TYPE_ALIGN (type
) = tree_low_cst (TYPE_SIZE (type
), 0);
1690 /* This is an incomplete type and so doesn't have a size. */
1691 TYPE_ALIGN (type
) = 1;
1692 TYPE_USER_ALIGN (type
) = 0;
1693 TYPE_MODE (type
) = VOIDmode
;
1697 TYPE_SIZE (type
) = bitsize_int (POINTER_SIZE
);
1698 TYPE_SIZE_UNIT (type
) = size_int (POINTER_SIZE
/ BITS_PER_UNIT
);
1699 /* A pointer might be MODE_PARTIAL_INT,
1700 but ptrdiff_t must be integral. */
1701 TYPE_MODE (type
) = mode_for_size (POINTER_SIZE
, MODE_INT
, 0);
1706 /* It's hard to see what the mode and size of a function ought to
1707 be, but we do know the alignment is FUNCTION_BOUNDARY, so
1708 make it consistent with that. */
1709 TYPE_MODE (type
) = mode_for_size (FUNCTION_BOUNDARY
, MODE_INT
, 0);
1710 TYPE_SIZE (type
) = bitsize_int (FUNCTION_BOUNDARY
);
1711 TYPE_SIZE_UNIT (type
) = size_int (FUNCTION_BOUNDARY
/ BITS_PER_UNIT
);
1715 case REFERENCE_TYPE
:
1718 enum machine_mode mode
= ((TREE_CODE (type
) == REFERENCE_TYPE
1719 && reference_types_internal
)
1720 ? Pmode
: TYPE_MODE (type
));
1722 int nbits
= GET_MODE_BITSIZE (mode
);
1724 TYPE_SIZE (type
) = bitsize_int (nbits
);
1725 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
1726 TYPE_UNSIGNED (type
) = 1;
1727 TYPE_PRECISION (type
) = nbits
;
1733 tree index
= TYPE_DOMAIN (type
);
1734 tree element
= TREE_TYPE (type
);
1736 build_pointer_type (element
);
1738 /* We need to know both bounds in order to compute the size. */
1739 if (index
&& TYPE_MAX_VALUE (index
) && TYPE_MIN_VALUE (index
)
1740 && TYPE_SIZE (element
))
1742 tree ub
= TYPE_MAX_VALUE (index
);
1743 tree lb
= TYPE_MIN_VALUE (index
);
1747 /* The initial subtraction should happen in the original type so
1748 that (possible) negative values are handled appropriately. */
1749 length
= size_binop (PLUS_EXPR
, size_one_node
,
1750 fold_convert (sizetype
,
1751 fold_build2 (MINUS_EXPR
,
1755 /* Special handling for arrays of bits (for Chill). */
1756 element_size
= TYPE_SIZE (element
);
1757 if (TYPE_PACKED (type
) && INTEGRAL_TYPE_P (element
)
1758 && (integer_zerop (TYPE_MAX_VALUE (element
))
1759 || integer_onep (TYPE_MAX_VALUE (element
)))
1760 && host_integerp (TYPE_MIN_VALUE (element
), 1))
1762 HOST_WIDE_INT maxvalue
1763 = tree_low_cst (TYPE_MAX_VALUE (element
), 1);
1764 HOST_WIDE_INT minvalue
1765 = tree_low_cst (TYPE_MIN_VALUE (element
), 1);
1767 if (maxvalue
- minvalue
== 1
1768 && (maxvalue
== 1 || maxvalue
== 0))
1769 element_size
= integer_one_node
;
1772 /* If neither bound is a constant and sizetype is signed, make
1773 sure the size is never negative. We should really do this
1774 if *either* bound is non-constant, but this is the best
1775 compromise between C and Ada. */
1776 if (!TYPE_UNSIGNED (sizetype
)
1777 && TREE_CODE (TYPE_MIN_VALUE (index
)) != INTEGER_CST
1778 && TREE_CODE (TYPE_MAX_VALUE (index
)) != INTEGER_CST
)
1779 length
= size_binop (MAX_EXPR
, length
, size_zero_node
);
1781 TYPE_SIZE (type
) = size_binop (MULT_EXPR
, element_size
,
1782 fold_convert (bitsizetype
,
1785 /* If we know the size of the element, calculate the total
1786 size directly, rather than do some division thing below.
1787 This optimization helps Fortran assumed-size arrays
1788 (where the size of the array is determined at runtime)
1790 Note that we can't do this in the case where the size of
1791 the elements is one bit since TYPE_SIZE_UNIT cannot be
1792 set correctly in that case. */
1793 if (TYPE_SIZE_UNIT (element
) != 0 && ! integer_onep (element_size
))
1794 TYPE_SIZE_UNIT (type
)
1795 = size_binop (MULT_EXPR
, TYPE_SIZE_UNIT (element
), length
);
1798 /* Now round the alignment and size,
1799 using machine-dependent criteria if any. */
1801 #ifdef ROUND_TYPE_ALIGN
1803 = ROUND_TYPE_ALIGN (type
, TYPE_ALIGN (element
), BITS_PER_UNIT
);
1805 TYPE_ALIGN (type
) = MAX (TYPE_ALIGN (element
), BITS_PER_UNIT
);
1807 if (!TYPE_SIZE (element
))
1808 /* We don't know the size of the underlying element type, so
1809 our alignment calculations will be wrong, forcing us to
1810 fall back on structural equality. */
1811 SET_TYPE_STRUCTURAL_EQUALITY (type
);
1812 TYPE_USER_ALIGN (type
) = TYPE_USER_ALIGN (element
);
1813 TYPE_MODE (type
) = BLKmode
;
1814 if (TYPE_SIZE (type
) != 0
1815 #ifdef MEMBER_TYPE_FORCES_BLK
1816 && ! MEMBER_TYPE_FORCES_BLK (type
, VOIDmode
)
1818 /* BLKmode elements force BLKmode aggregate;
1819 else extract/store fields may lose. */
1820 && (TYPE_MODE (TREE_TYPE (type
)) != BLKmode
1821 || TYPE_NO_FORCE_BLK (TREE_TYPE (type
))))
1823 /* One-element arrays get the component type's mode. */
1824 if (simple_cst_equal (TYPE_SIZE (type
),
1825 TYPE_SIZE (TREE_TYPE (type
))))
1826 TYPE_MODE (type
) = TYPE_MODE (TREE_TYPE (type
));
1829 = mode_for_size_tree (TYPE_SIZE (type
), MODE_INT
, 1);
1831 if (TYPE_MODE (type
) != BLKmode
1832 && STRICT_ALIGNMENT
&& TYPE_ALIGN (type
) < BIGGEST_ALIGNMENT
1833 && TYPE_ALIGN (type
) < GET_MODE_ALIGNMENT (TYPE_MODE (type
)))
1835 TYPE_NO_FORCE_BLK (type
) = 1;
1836 TYPE_MODE (type
) = BLKmode
;
1839 /* When the element size is constant, check that it is at least as
1840 large as the element alignment. */
1841 if (TYPE_SIZE_UNIT (element
)
1842 && TREE_CODE (TYPE_SIZE_UNIT (element
)) == INTEGER_CST
1843 /* If TYPE_SIZE_UNIT overflowed, then it is certainly larger than
1845 && !TREE_OVERFLOW (TYPE_SIZE_UNIT (element
))
1846 && !integer_zerop (TYPE_SIZE_UNIT (element
))
1847 && compare_tree_int (TYPE_SIZE_UNIT (element
),
1848 TYPE_ALIGN_UNIT (element
)) < 0)
1849 error ("alignment of array elements is greater than element size");
1855 case QUAL_UNION_TYPE
:
1858 record_layout_info rli
;
1860 /* Initialize the layout information. */
1861 rli
= start_record_layout (type
);
1863 /* If this is a QUAL_UNION_TYPE, we want to process the fields
1864 in the reverse order in building the COND_EXPR that denotes
1865 its size. We reverse them again later. */
1866 if (TREE_CODE (type
) == QUAL_UNION_TYPE
)
1867 TYPE_FIELDS (type
) = nreverse (TYPE_FIELDS (type
));
1869 /* Place all the fields. */
1870 for (field
= TYPE_FIELDS (type
); field
; field
= TREE_CHAIN (field
))
1871 place_field (rli
, field
);
1873 if (TREE_CODE (type
) == QUAL_UNION_TYPE
)
1874 TYPE_FIELDS (type
) = nreverse (TYPE_FIELDS (type
));
1876 if (lang_adjust_rli
)
1877 (*lang_adjust_rli
) (rli
);
1879 /* Finish laying out the record. */
1880 finish_record_layout (rli
, /*free_p=*/true);
1888 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
1889 records and unions, finish_record_layout already called this
1891 if (TREE_CODE (type
) != RECORD_TYPE
1892 && TREE_CODE (type
) != UNION_TYPE
1893 && TREE_CODE (type
) != QUAL_UNION_TYPE
)
1894 finalize_type_size (type
);
1896 /* If an alias set has been set for this aggregate when it was incomplete,
1897 force it into alias set 0.
1898 This is too conservative, but we cannot call record_component_aliases
1899 here because some frontends still change the aggregates after
1901 if (AGGREGATE_TYPE_P (type
) && TYPE_ALIAS_SET_KNOWN_P (type
))
1902 TYPE_ALIAS_SET (type
) = 0;
1905 /* Create and return a type for signed integers of PRECISION bits. */
1908 make_signed_type (int precision
)
1910 tree type
= make_node (INTEGER_TYPE
);
1912 TYPE_PRECISION (type
) = precision
;
1914 fixup_signed_type (type
);
1918 /* Create and return a type for unsigned integers of PRECISION bits. */
1921 make_unsigned_type (int precision
)
1923 tree type
= make_node (INTEGER_TYPE
);
1925 TYPE_PRECISION (type
) = precision
;
1927 fixup_unsigned_type (type
);
1931 /* Create and return a type for fract of PRECISION bits, UNSIGNEDP,
1935 make_fract_type (int precision
, int unsignedp
, int satp
)
1937 tree type
= make_node (FIXED_POINT_TYPE
);
1939 TYPE_PRECISION (type
) = precision
;
1942 TYPE_SATURATING (type
) = 1;
1944 /* Lay out the type: set its alignment, size, etc. */
1947 TYPE_UNSIGNED (type
) = 1;
1948 TYPE_MODE (type
) = mode_for_size (precision
, MODE_UFRACT
, 0);
1951 TYPE_MODE (type
) = mode_for_size (precision
, MODE_FRACT
, 0);
1957 /* Create and return a type for accum of PRECISION bits, UNSIGNEDP,
1961 make_accum_type (int precision
, int unsignedp
, int satp
)
1963 tree type
= make_node (FIXED_POINT_TYPE
);
1965 TYPE_PRECISION (type
) = precision
;
1968 TYPE_SATURATING (type
) = 1;
1970 /* Lay out the type: set its alignment, size, etc. */
1973 TYPE_UNSIGNED (type
) = 1;
1974 TYPE_MODE (type
) = mode_for_size (precision
, MODE_UACCUM
, 0);
1977 TYPE_MODE (type
) = mode_for_size (precision
, MODE_ACCUM
, 0);
1983 /* Initialize sizetype and bitsizetype to a reasonable and temporary
1984 value to enable integer types to be created. */
1987 initialize_sizetypes (bool signed_p
)
1989 tree t
= make_node (INTEGER_TYPE
);
1990 int precision
= GET_MODE_BITSIZE (SImode
);
1992 TYPE_MODE (t
) = SImode
;
1993 TYPE_ALIGN (t
) = GET_MODE_ALIGNMENT (SImode
);
1994 TYPE_USER_ALIGN (t
) = 0;
1995 TYPE_IS_SIZETYPE (t
) = 1;
1996 TYPE_UNSIGNED (t
) = !signed_p
;
1997 TYPE_SIZE (t
) = build_int_cst (t
, precision
);
1998 TYPE_SIZE_UNIT (t
) = build_int_cst (t
, GET_MODE_SIZE (SImode
));
1999 TYPE_PRECISION (t
) = precision
;
2001 /* Set TYPE_MIN_VALUE and TYPE_MAX_VALUE. */
2002 set_min_and_max_values_for_integral_type (t
, precision
, !signed_p
);
2005 bitsizetype
= build_distinct_type_copy (t
);
2008 /* Make sizetype a version of TYPE, and initialize *sizetype
2009 accordingly. We do this by overwriting the stub sizetype and
2010 bitsizetype nodes created by initialize_sizetypes. This makes sure
2011 that (a) anything stubby about them no longer exists, (b) any
2012 INTEGER_CSTs created with such a type, remain valid. */
2015 set_sizetype (tree type
)
2017 int oprecision
= TYPE_PRECISION (type
);
2018 /* The *bitsizetype types use a precision that avoids overflows when
2019 calculating signed sizes / offsets in bits. However, when
2020 cross-compiling from a 32 bit to a 64 bit host, we are limited to 64 bit
2022 int precision
= MIN (MIN (oprecision
+ BITS_PER_UNIT_LOG
+ 1,
2023 MAX_FIXED_MODE_SIZE
),
2024 2 * HOST_BITS_PER_WIDE_INT
);
2027 gcc_assert (TYPE_UNSIGNED (type
) == TYPE_UNSIGNED (sizetype
));
2029 t
= build_distinct_type_copy (type
);
2030 /* We do want to use sizetype's cache, as we will be replacing that
2032 TYPE_CACHED_VALUES (t
) = TYPE_CACHED_VALUES (sizetype
);
2033 TYPE_CACHED_VALUES_P (t
) = TYPE_CACHED_VALUES_P (sizetype
);
2034 TREE_TYPE (TYPE_CACHED_VALUES (t
)) = type
;
2035 TYPE_UID (t
) = TYPE_UID (sizetype
);
2036 TYPE_IS_SIZETYPE (t
) = 1;
2038 /* Replace our original stub sizetype. */
2039 memcpy (sizetype
, t
, tree_size (sizetype
));
2040 TYPE_MAIN_VARIANT (sizetype
) = sizetype
;
2042 t
= make_node (INTEGER_TYPE
);
2043 TYPE_NAME (t
) = get_identifier ("bit_size_type");
2044 /* We do want to use bitsizetype's cache, as we will be replacing that
2046 TYPE_CACHED_VALUES (t
) = TYPE_CACHED_VALUES (bitsizetype
);
2047 TYPE_CACHED_VALUES_P (t
) = TYPE_CACHED_VALUES_P (bitsizetype
);
2048 TYPE_PRECISION (t
) = precision
;
2049 TYPE_UID (t
) = TYPE_UID (bitsizetype
);
2050 TYPE_IS_SIZETYPE (t
) = 1;
2052 /* Replace our original stub bitsizetype. */
2053 memcpy (bitsizetype
, t
, tree_size (bitsizetype
));
2054 TYPE_MAIN_VARIANT (bitsizetype
) = bitsizetype
;
2056 if (TYPE_UNSIGNED (type
))
2058 fixup_unsigned_type (bitsizetype
);
2059 ssizetype
= build_distinct_type_copy (make_signed_type (oprecision
));
2060 TYPE_IS_SIZETYPE (ssizetype
) = 1;
2061 sbitsizetype
= build_distinct_type_copy (make_signed_type (precision
));
2062 TYPE_IS_SIZETYPE (sbitsizetype
) = 1;
2066 fixup_signed_type (bitsizetype
);
2067 ssizetype
= sizetype
;
2068 sbitsizetype
= bitsizetype
;
2071 /* If SIZETYPE is unsigned, we need to fix TYPE_MAX_VALUE so that
2072 it is sign extended in a way consistent with force_fit_type. */
2073 if (TYPE_UNSIGNED (type
))
2075 tree orig_max
, new_max
;
2077 orig_max
= TYPE_MAX_VALUE (sizetype
);
2079 /* Build a new node with the same values, but a different type.
2080 Sign extend it to ensure consistency. */
2081 new_max
= build_int_cst_wide_type (sizetype
,
2082 TREE_INT_CST_LOW (orig_max
),
2083 TREE_INT_CST_HIGH (orig_max
));
2084 TYPE_MAX_VALUE (sizetype
) = new_max
;
2088 /* TYPE is an integral type, i.e., an INTEGRAL_TYPE, ENUMERAL_TYPE
2089 or BOOLEAN_TYPE. Set TYPE_MIN_VALUE and TYPE_MAX_VALUE
2090 for TYPE, based on the PRECISION and whether or not the TYPE
2091 IS_UNSIGNED. PRECISION need not correspond to a width supported
2092 natively by the hardware; for example, on a machine with 8-bit,
2093 16-bit, and 32-bit register modes, PRECISION might be 7, 23, or
2097 set_min_and_max_values_for_integral_type (tree type
,
2106 min_value
= build_int_cst (type
, 0);
2108 = build_int_cst_wide (type
, precision
- HOST_BITS_PER_WIDE_INT
>= 0
2110 : ((HOST_WIDE_INT
) 1 << precision
) - 1,
2111 precision
- HOST_BITS_PER_WIDE_INT
> 0
2112 ? ((unsigned HOST_WIDE_INT
) ~0
2113 >> (HOST_BITS_PER_WIDE_INT
2114 - (precision
- HOST_BITS_PER_WIDE_INT
)))
2120 = build_int_cst_wide (type
,
2121 (precision
- HOST_BITS_PER_WIDE_INT
> 0
2123 : (HOST_WIDE_INT
) (-1) << (precision
- 1)),
2124 (((HOST_WIDE_INT
) (-1)
2125 << (precision
- HOST_BITS_PER_WIDE_INT
- 1 > 0
2126 ? precision
- HOST_BITS_PER_WIDE_INT
- 1
2129 = build_int_cst_wide (type
,
2130 (precision
- HOST_BITS_PER_WIDE_INT
> 0
2132 : ((HOST_WIDE_INT
) 1 << (precision
- 1)) - 1),
2133 (precision
- HOST_BITS_PER_WIDE_INT
- 1 > 0
2134 ? (((HOST_WIDE_INT
) 1
2135 << (precision
- HOST_BITS_PER_WIDE_INT
- 1))) - 1
2139 TYPE_MIN_VALUE (type
) = min_value
;
2140 TYPE_MAX_VALUE (type
) = max_value
;
2143 /* Set the extreme values of TYPE based on its precision in bits,
2144 then lay it out. Used when make_signed_type won't do
2145 because the tree code is not INTEGER_TYPE.
2146 E.g. for Pascal, when the -fsigned-char option is given. */
2149 fixup_signed_type (tree type
)
2151 int precision
= TYPE_PRECISION (type
);
2153 /* We can not represent properly constants greater then
2154 2 * HOST_BITS_PER_WIDE_INT, still we need the types
2155 as they are used by i386 vector extensions and friends. */
2156 if (precision
> HOST_BITS_PER_WIDE_INT
* 2)
2157 precision
= HOST_BITS_PER_WIDE_INT
* 2;
2159 set_min_and_max_values_for_integral_type (type
, precision
,
2160 /*is_unsigned=*/false);
2162 /* Lay out the type: set its alignment, size, etc. */
2166 /* Set the extreme values of TYPE based on its precision in bits,
2167 then lay it out. This is used both in `make_unsigned_type'
2168 and for enumeral types. */
2171 fixup_unsigned_type (tree type
)
2173 int precision
= TYPE_PRECISION (type
);
2175 /* We can not represent properly constants greater then
2176 2 * HOST_BITS_PER_WIDE_INT, still we need the types
2177 as they are used by i386 vector extensions and friends. */
2178 if (precision
> HOST_BITS_PER_WIDE_INT
* 2)
2179 precision
= HOST_BITS_PER_WIDE_INT
* 2;
2181 TYPE_UNSIGNED (type
) = 1;
2183 set_min_and_max_values_for_integral_type (type
, precision
,
2184 /*is_unsigned=*/true);
2186 /* Lay out the type: set its alignment, size, etc. */
2190 /* Find the best machine mode to use when referencing a bit field of length
2191 BITSIZE bits starting at BITPOS.
2193 The underlying object is known to be aligned to a boundary of ALIGN bits.
2194 If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
2195 larger than LARGEST_MODE (usually SImode).
2197 If no mode meets all these conditions, we return VOIDmode.
2199 If VOLATILEP is false and SLOW_BYTE_ACCESS is false, we return the
2200 smallest mode meeting these conditions.
2202 If VOLATILEP is false and SLOW_BYTE_ACCESS is true, we return the
2203 largest mode (but a mode no wider than UNITS_PER_WORD) that meets
2206 If VOLATILEP is true the narrow_volatile_bitfields target hook is used to
2207 decide which of the above modes should be used. */
2210 get_best_mode (int bitsize
, int bitpos
, unsigned int align
,
2211 enum machine_mode largest_mode
, int volatilep
)
2213 enum machine_mode mode
;
2214 unsigned int unit
= 0;
2216 /* Find the narrowest integer mode that contains the bit field. */
2217 for (mode
= GET_CLASS_NARROWEST_MODE (MODE_INT
); mode
!= VOIDmode
;
2218 mode
= GET_MODE_WIDER_MODE (mode
))
2220 unit
= GET_MODE_BITSIZE (mode
);
2221 if ((bitpos
% unit
) + bitsize
<= unit
)
2225 if (mode
== VOIDmode
2226 /* It is tempting to omit the following line
2227 if STRICT_ALIGNMENT is true.
2228 But that is incorrect, since if the bitfield uses part of 3 bytes
2229 and we use a 4-byte mode, we could get a spurious segv
2230 if the extra 4th byte is past the end of memory.
2231 (Though at least one Unix compiler ignores this problem:
2232 that on the Sequent 386 machine. */
2233 || MIN (unit
, BIGGEST_ALIGNMENT
) > align
2234 || (largest_mode
!= VOIDmode
&& unit
> GET_MODE_BITSIZE (largest_mode
)))
2237 if ((SLOW_BYTE_ACCESS
&& ! volatilep
)
2238 || (volatilep
&& !targetm
.narrow_volatile_bitfield ()))
2240 enum machine_mode wide_mode
= VOIDmode
, tmode
;
2242 for (tmode
= GET_CLASS_NARROWEST_MODE (MODE_INT
); tmode
!= VOIDmode
;
2243 tmode
= GET_MODE_WIDER_MODE (tmode
))
2245 unit
= GET_MODE_BITSIZE (tmode
);
2246 if (bitpos
/ unit
== (bitpos
+ bitsize
- 1) / unit
2247 && unit
<= BITS_PER_WORD
2248 && unit
<= MIN (align
, BIGGEST_ALIGNMENT
)
2249 && (largest_mode
== VOIDmode
2250 || unit
<= GET_MODE_BITSIZE (largest_mode
)))
2254 if (wide_mode
!= VOIDmode
)
2261 /* Gets minimal and maximal values for MODE (signed or unsigned depending on
2262 SIGN). The returned constants are made to be usable in TARGET_MODE. */
2265 get_mode_bounds (enum machine_mode mode
, int sign
,
2266 enum machine_mode target_mode
,
2267 rtx
*mmin
, rtx
*mmax
)
2269 unsigned size
= GET_MODE_BITSIZE (mode
);
2270 unsigned HOST_WIDE_INT min_val
, max_val
;
2272 gcc_assert (size
<= HOST_BITS_PER_WIDE_INT
);
2276 min_val
= -((unsigned HOST_WIDE_INT
) 1 << (size
- 1));
2277 max_val
= ((unsigned HOST_WIDE_INT
) 1 << (size
- 1)) - 1;
2282 max_val
= ((unsigned HOST_WIDE_INT
) 1 << (size
- 1) << 1) - 1;
2285 *mmin
= gen_int_mode (min_val
, target_mode
);
2286 *mmax
= gen_int_mode (max_val
, target_mode
);
2289 #include "gt-stor-layout.h"