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, 2008, 2009, 2010
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 #include "tree-inline.h"
42 #include "tree-dump.h"
45 /* Data type for the expressions representing sizes of data types.
46 It is the first integer type laid out. */
47 tree sizetype_tab
[(int) TYPE_KIND_LAST
];
49 /* If nonzero, this is an upper limit on alignment of structure fields.
50 The value is measured in bits. */
51 unsigned int maximum_field_alignment
= TARGET_DEFAULT_PACK_STRUCT
* BITS_PER_UNIT
;
52 /* ... and its original value in bytes, specified via -fpack-struct=<value>. */
53 unsigned int initial_max_fld_align
= TARGET_DEFAULT_PACK_STRUCT
;
55 /* Nonzero if all REFERENCE_TYPEs are internal and hence should be allocated
56 in the address spaces' address_mode, not pointer_mode. Set only by
57 internal_reference_types called only by a front end. */
58 static int reference_types_internal
= 0;
60 static tree
self_referential_size (tree
);
61 static void finalize_record_size (record_layout_info
);
62 static void finalize_type_size (tree
);
63 static void place_union_field (record_layout_info
, tree
);
64 #if defined (PCC_BITFIELD_TYPE_MATTERS) || defined (BITFIELD_NBYTES_LIMITED)
65 static int excess_unit_span (HOST_WIDE_INT
, HOST_WIDE_INT
, HOST_WIDE_INT
,
68 extern void debug_rli (record_layout_info
);
70 /* SAVE_EXPRs for sizes of types and decls, waiting to be expanded. */
72 static GTY(()) VEC(tree
,gc
) *pending_sizes
;
74 /* Show that REFERENCE_TYPES are internal and should use address_mode.
75 Called only by front end. */
78 internal_reference_types (void)
80 reference_types_internal
= 1;
83 /* Get a VEC of all the objects put on the pending sizes list. */
86 get_pending_sizes (void)
88 VEC(tree
,gc
) *chain
= pending_sizes
;
94 /* Add EXPR to the pending sizes list. */
97 put_pending_size (tree expr
)
99 /* Strip any simple arithmetic from EXPR to see if it has an underlying
101 expr
= skip_simple_arithmetic (expr
);
103 if (TREE_CODE (expr
) == SAVE_EXPR
)
104 VEC_safe_push (tree
, gc
, pending_sizes
, expr
);
107 /* Put a chain of objects into the pending sizes list, which must be
111 put_pending_sizes (VEC(tree
,gc
) *chain
)
113 gcc_assert (!pending_sizes
);
114 pending_sizes
= chain
;
117 /* Given a size SIZE that may not be a constant, return a SAVE_EXPR
118 to serve as the actual size-expression for a type or decl. */
121 variable_size (tree size
)
126 if (TREE_CONSTANT (size
))
129 /* If the size is self-referential, we can't make a SAVE_EXPR (see
130 save_expr for the rationale). But we can do something else. */
131 if (CONTAINS_PLACEHOLDER_P (size
))
132 return self_referential_size (size
);
134 /* If the language-processor is to take responsibility for variable-sized
135 items (e.g., languages which have elaboration procedures like Ada),
136 just return SIZE unchanged. */
137 if (lang_hooks
.decls
.global_bindings_p () < 0)
140 size
= save_expr (size
);
142 /* If an array with a variable number of elements is declared, and
143 the elements require destruction, we will emit a cleanup for the
144 array. That cleanup is run both on normal exit from the block
145 and in the exception-handler for the block. Normally, when code
146 is used in both ordinary code and in an exception handler it is
147 `unsaved', i.e., all SAVE_EXPRs are recalculated. However, we do
148 not wish to do that here; the array-size is the same in both
150 save
= skip_simple_arithmetic (size
);
152 if (cfun
&& cfun
->dont_save_pending_sizes_p
)
153 /* The front-end doesn't want us to keep a list of the expressions
154 that determine sizes for variable size objects. Trust it. */
157 if (lang_hooks
.decls
.global_bindings_p ())
159 if (TREE_CONSTANT (size
))
160 error ("type size can%'t be explicitly evaluated");
162 error ("variable-size type declared outside of any function");
164 return size_one_node
;
167 put_pending_size (save
);
172 /* An array of functions used for self-referential size computation. */
173 static GTY(()) VEC (tree
, gc
) *size_functions
;
175 /* Similar to copy_tree_r but do not copy component references involving
176 PLACEHOLDER_EXPRs. These nodes are spotted in find_placeholder_in_expr
177 and substituted in substitute_in_expr. */
180 copy_self_referential_tree_r (tree
*tp
, int *walk_subtrees
, void *data
)
182 enum tree_code code
= TREE_CODE (*tp
);
184 /* Stop at types, decls, constants like copy_tree_r. */
185 if (TREE_CODE_CLASS (code
) == tcc_type
186 || TREE_CODE_CLASS (code
) == tcc_declaration
187 || TREE_CODE_CLASS (code
) == tcc_constant
)
193 /* This is the pattern built in ada/make_aligning_type. */
194 else if (code
== ADDR_EXPR
195 && TREE_CODE (TREE_OPERAND (*tp
, 0)) == PLACEHOLDER_EXPR
)
201 /* Default case: the component reference. */
202 else if (code
== COMPONENT_REF
)
205 for (inner
= TREE_OPERAND (*tp
, 0);
206 REFERENCE_CLASS_P (inner
);
207 inner
= TREE_OPERAND (inner
, 0))
210 if (TREE_CODE (inner
) == PLACEHOLDER_EXPR
)
217 /* We're not supposed to have them in self-referential size trees
218 because we wouldn't properly control when they are evaluated.
219 However, not creating superfluous SAVE_EXPRs requires accurate
220 tracking of readonly-ness all the way down to here, which we
221 cannot always guarantee in practice. So punt in this case. */
222 else if (code
== SAVE_EXPR
)
223 return error_mark_node
;
225 return copy_tree_r (tp
, walk_subtrees
, data
);
228 /* Given a SIZE expression that is self-referential, return an equivalent
229 expression to serve as the actual size expression for a type. */
232 self_referential_size (tree size
)
234 static unsigned HOST_WIDE_INT fnno
= 0;
235 VEC (tree
, heap
) *self_refs
= NULL
;
236 tree param_type_list
= NULL
, param_decl_list
= NULL
, arg_list
= NULL
;
237 tree t
, ref
, return_type
, fntype
, fnname
, fndecl
;
241 /* Do not factor out simple operations. */
242 t
= skip_simple_arithmetic (size
);
243 if (TREE_CODE (t
) == CALL_EXPR
)
246 /* Collect the list of self-references in the expression. */
247 find_placeholder_in_expr (size
, &self_refs
);
248 gcc_assert (VEC_length (tree
, self_refs
) > 0);
250 /* Obtain a private copy of the expression. */
252 if (walk_tree (&t
, copy_self_referential_tree_r
, NULL
, NULL
) != NULL_TREE
)
256 /* Build the parameter and argument lists in parallel; also
257 substitute the former for the latter in the expression. */
258 for (i
= 0; VEC_iterate (tree
, self_refs
, i
, ref
); i
++)
260 tree subst
, param_name
, param_type
, param_decl
;
264 /* We shouldn't have true variables here. */
265 gcc_assert (TREE_READONLY (ref
));
268 /* This is the pattern built in ada/make_aligning_type. */
269 else if (TREE_CODE (ref
) == ADDR_EXPR
)
271 /* Default case: the component reference. */
273 subst
= TREE_OPERAND (ref
, 1);
275 sprintf (buf
, "p%d", i
);
276 param_name
= get_identifier (buf
);
277 param_type
= TREE_TYPE (ref
);
279 = build_decl (input_location
, PARM_DECL
, param_name
, param_type
);
280 if (targetm
.calls
.promote_prototypes (NULL_TREE
)
281 && INTEGRAL_TYPE_P (param_type
)
282 && TYPE_PRECISION (param_type
) < TYPE_PRECISION (integer_type_node
))
283 DECL_ARG_TYPE (param_decl
) = integer_type_node
;
285 DECL_ARG_TYPE (param_decl
) = param_type
;
286 DECL_ARTIFICIAL (param_decl
) = 1;
287 TREE_READONLY (param_decl
) = 1;
289 size
= substitute_in_expr (size
, subst
, param_decl
);
291 param_type_list
= tree_cons (NULL_TREE
, param_type
, param_type_list
);
292 param_decl_list
= chainon (param_decl
, param_decl_list
);
293 arg_list
= tree_cons (NULL_TREE
, ref
, arg_list
);
296 VEC_free (tree
, heap
, self_refs
);
298 /* Append 'void' to indicate that the number of parameters is fixed. */
299 param_type_list
= tree_cons (NULL_TREE
, void_type_node
, param_type_list
);
301 /* The 3 lists have been created in reverse order. */
302 param_type_list
= nreverse (param_type_list
);
303 param_decl_list
= nreverse (param_decl_list
);
304 arg_list
= nreverse (arg_list
);
306 /* Build the function type. */
307 return_type
= TREE_TYPE (size
);
308 fntype
= build_function_type (return_type
, param_type_list
);
310 /* Build the function declaration. */
311 sprintf (buf
, "SZ"HOST_WIDE_INT_PRINT_UNSIGNED
, fnno
++);
312 fnname
= get_file_function_name (buf
);
313 fndecl
= build_decl (input_location
, FUNCTION_DECL
, fnname
, fntype
);
314 for (t
= param_decl_list
; t
; t
= TREE_CHAIN (t
))
315 DECL_CONTEXT (t
) = fndecl
;
316 DECL_ARGUMENTS (fndecl
) = param_decl_list
;
318 = build_decl (input_location
, RESULT_DECL
, 0, return_type
);
319 DECL_CONTEXT (DECL_RESULT (fndecl
)) = fndecl
;
321 /* The function has been created by the compiler and we don't
322 want to emit debug info for it. */
323 DECL_ARTIFICIAL (fndecl
) = 1;
324 DECL_IGNORED_P (fndecl
) = 1;
326 /* It is supposed to be "const" and never throw. */
327 TREE_READONLY (fndecl
) = 1;
328 TREE_NOTHROW (fndecl
) = 1;
330 /* We want it to be inlined when this is deemed profitable, as
331 well as discarded if every call has been integrated. */
332 DECL_DECLARED_INLINE_P (fndecl
) = 1;
334 /* It is made up of a unique return statement. */
335 DECL_INITIAL (fndecl
) = make_node (BLOCK
);
336 BLOCK_SUPERCONTEXT (DECL_INITIAL (fndecl
)) = fndecl
;
337 t
= build2 (MODIFY_EXPR
, return_type
, DECL_RESULT (fndecl
), size
);
338 DECL_SAVED_TREE (fndecl
) = build1 (RETURN_EXPR
, void_type_node
, t
);
339 TREE_STATIC (fndecl
) = 1;
341 /* Put it onto the list of size functions. */
342 VEC_safe_push (tree
, gc
, size_functions
, fndecl
);
344 /* Replace the original expression with a call to the size function. */
345 return build_function_call_expr (UNKNOWN_LOCATION
, fndecl
, arg_list
);
348 /* Take, queue and compile all the size functions. It is essential that
349 the size functions be gimplified at the very end of the compilation
350 in order to guarantee transparent handling of self-referential sizes.
351 Otherwise the GENERIC inliner would not be able to inline them back
352 at each of their call sites, thus creating artificial non-constant
353 size expressions which would trigger nasty problems later on. */
356 finalize_size_functions (void)
361 for (i
= 0; VEC_iterate(tree
, size_functions
, i
, fndecl
); i
++)
363 dump_function (TDI_original
, fndecl
);
364 gimplify_function_tree (fndecl
);
365 dump_function (TDI_generic
, fndecl
);
366 cgraph_finalize_function (fndecl
, false);
369 VEC_free (tree
, gc
, size_functions
);
372 /* Return the machine mode to use for a nonscalar of SIZE bits. The
373 mode must be in class MCLASS, and have exactly that many value bits;
374 it may have padding as well. If LIMIT is nonzero, modes of wider
375 than MAX_FIXED_MODE_SIZE will not be used. */
378 mode_for_size (unsigned int size
, enum mode_class mclass
, int limit
)
380 enum machine_mode mode
;
382 if (limit
&& size
> MAX_FIXED_MODE_SIZE
)
385 /* Get the first mode which has this size, in the specified class. */
386 for (mode
= GET_CLASS_NARROWEST_MODE (mclass
); mode
!= VOIDmode
;
387 mode
= GET_MODE_WIDER_MODE (mode
))
388 if (GET_MODE_PRECISION (mode
) == size
)
394 /* Similar, except passed a tree node. */
397 mode_for_size_tree (const_tree size
, enum mode_class mclass
, int limit
)
399 unsigned HOST_WIDE_INT uhwi
;
402 if (!host_integerp (size
, 1))
404 uhwi
= tree_low_cst (size
, 1);
408 return mode_for_size (ui
, mclass
, limit
);
411 /* Similar, but never return BLKmode; return the narrowest mode that
412 contains at least the requested number of value bits. */
415 smallest_mode_for_size (unsigned int size
, enum mode_class mclass
)
417 enum machine_mode mode
;
419 /* Get the first mode which has at least this size, in the
421 for (mode
= GET_CLASS_NARROWEST_MODE (mclass
); mode
!= VOIDmode
;
422 mode
= GET_MODE_WIDER_MODE (mode
))
423 if (GET_MODE_PRECISION (mode
) >= size
)
429 /* Find an integer mode of the exact same size, or BLKmode on failure. */
432 int_mode_for_mode (enum machine_mode mode
)
434 switch (GET_MODE_CLASS (mode
))
437 case MODE_PARTIAL_INT
:
440 case MODE_COMPLEX_INT
:
441 case MODE_COMPLEX_FLOAT
:
443 case MODE_DECIMAL_FLOAT
:
444 case MODE_VECTOR_INT
:
445 case MODE_VECTOR_FLOAT
:
450 case MODE_VECTOR_FRACT
:
451 case MODE_VECTOR_ACCUM
:
452 case MODE_VECTOR_UFRACT
:
453 case MODE_VECTOR_UACCUM
:
454 mode
= mode_for_size (GET_MODE_BITSIZE (mode
), MODE_INT
, 0);
461 /* ... fall through ... */
471 /* Return the alignment of MODE. This will be bounded by 1 and
472 BIGGEST_ALIGNMENT. */
475 get_mode_alignment (enum machine_mode mode
)
477 return MIN (BIGGEST_ALIGNMENT
, MAX (1, mode_base_align
[mode
]*BITS_PER_UNIT
));
481 /* Subroutine of layout_decl: Force alignment required for the data type.
482 But if the decl itself wants greater alignment, don't override that. */
485 do_type_align (tree type
, tree decl
)
487 if (TYPE_ALIGN (type
) > DECL_ALIGN (decl
))
489 DECL_ALIGN (decl
) = TYPE_ALIGN (type
);
490 if (TREE_CODE (decl
) == FIELD_DECL
)
491 DECL_USER_ALIGN (decl
) = TYPE_USER_ALIGN (type
);
495 /* Set the size, mode and alignment of a ..._DECL node.
496 TYPE_DECL does need this for C++.
497 Note that LABEL_DECL and CONST_DECL nodes do not need this,
498 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
499 Don't call layout_decl for them.
501 KNOWN_ALIGN is the amount of alignment we can assume this
502 decl has with no special effort. It is relevant only for FIELD_DECLs
503 and depends on the previous fields.
504 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
505 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
506 the record will be aligned to suit. */
509 layout_decl (tree decl
, unsigned int known_align
)
511 tree type
= TREE_TYPE (decl
);
512 enum tree_code code
= TREE_CODE (decl
);
514 location_t loc
= DECL_SOURCE_LOCATION (decl
);
516 if (code
== CONST_DECL
)
519 gcc_assert (code
== VAR_DECL
|| code
== PARM_DECL
|| code
== RESULT_DECL
520 || code
== TYPE_DECL
||code
== FIELD_DECL
);
522 rtl
= DECL_RTL_IF_SET (decl
);
524 if (type
== error_mark_node
)
525 type
= void_type_node
;
527 /* Usually the size and mode come from the data type without change,
528 however, the front-end may set the explicit width of the field, so its
529 size may not be the same as the size of its type. This happens with
530 bitfields, of course (an `int' bitfield may be only 2 bits, say), but it
531 also happens with other fields. For example, the C++ front-end creates
532 zero-sized fields corresponding to empty base classes, and depends on
533 layout_type setting DECL_FIELD_BITPOS correctly for the field. Set the
534 size in bytes from the size in bits. If we have already set the mode,
535 don't set it again since we can be called twice for FIELD_DECLs. */
537 DECL_UNSIGNED (decl
) = TYPE_UNSIGNED (type
);
538 if (DECL_MODE (decl
) == VOIDmode
)
539 DECL_MODE (decl
) = TYPE_MODE (type
);
541 if (DECL_SIZE (decl
) == 0)
543 DECL_SIZE (decl
) = TYPE_SIZE (type
);
544 DECL_SIZE_UNIT (decl
) = TYPE_SIZE_UNIT (type
);
546 else if (DECL_SIZE_UNIT (decl
) == 0)
547 DECL_SIZE_UNIT (decl
)
548 = fold_convert_loc (loc
, sizetype
,
549 size_binop_loc (loc
, CEIL_DIV_EXPR
, DECL_SIZE (decl
),
552 if (code
!= FIELD_DECL
)
553 /* For non-fields, update the alignment from the type. */
554 do_type_align (type
, decl
);
556 /* For fields, it's a bit more complicated... */
558 bool old_user_align
= DECL_USER_ALIGN (decl
);
559 bool zero_bitfield
= false;
560 bool packed_p
= DECL_PACKED (decl
);
563 if (DECL_BIT_FIELD (decl
))
565 DECL_BIT_FIELD_TYPE (decl
) = type
;
567 /* A zero-length bit-field affects the alignment of the next
568 field. In essence such bit-fields are not influenced by
569 any packing due to #pragma pack or attribute packed. */
570 if (integer_zerop (DECL_SIZE (decl
))
571 && ! targetm
.ms_bitfield_layout_p (DECL_FIELD_CONTEXT (decl
)))
573 zero_bitfield
= true;
575 #ifdef PCC_BITFIELD_TYPE_MATTERS
576 if (PCC_BITFIELD_TYPE_MATTERS
)
577 do_type_align (type
, decl
);
581 #ifdef EMPTY_FIELD_BOUNDARY
582 if (EMPTY_FIELD_BOUNDARY
> DECL_ALIGN (decl
))
584 DECL_ALIGN (decl
) = EMPTY_FIELD_BOUNDARY
;
585 DECL_USER_ALIGN (decl
) = 0;
591 /* See if we can use an ordinary integer mode for a bit-field.
592 Conditions are: a fixed size that is correct for another mode
593 and occupying a complete byte or bytes on proper boundary. */
594 if (TYPE_SIZE (type
) != 0
595 && TREE_CODE (TYPE_SIZE (type
)) == INTEGER_CST
596 && GET_MODE_CLASS (TYPE_MODE (type
)) == MODE_INT
)
598 enum machine_mode xmode
599 = mode_for_size_tree (DECL_SIZE (decl
), MODE_INT
, 1);
600 unsigned int xalign
= GET_MODE_ALIGNMENT (xmode
);
603 && !(xalign
> BITS_PER_UNIT
&& DECL_PACKED (decl
))
604 && (known_align
== 0 || known_align
>= xalign
))
606 DECL_ALIGN (decl
) = MAX (xalign
, DECL_ALIGN (decl
));
607 DECL_MODE (decl
) = xmode
;
608 DECL_BIT_FIELD (decl
) = 0;
612 /* Turn off DECL_BIT_FIELD if we won't need it set. */
613 if (TYPE_MODE (type
) == BLKmode
&& DECL_MODE (decl
) == BLKmode
614 && known_align
>= TYPE_ALIGN (type
)
615 && DECL_ALIGN (decl
) >= TYPE_ALIGN (type
))
616 DECL_BIT_FIELD (decl
) = 0;
618 else if (packed_p
&& DECL_USER_ALIGN (decl
))
619 /* Don't touch DECL_ALIGN. For other packed fields, go ahead and
620 round up; we'll reduce it again below. We want packing to
621 supersede USER_ALIGN inherited from the type, but defer to
622 alignment explicitly specified on the field decl. */;
624 do_type_align (type
, decl
);
626 /* If the field is packed and not explicitly aligned, give it the
627 minimum alignment. Note that do_type_align may set
628 DECL_USER_ALIGN, so we need to check old_user_align instead. */
631 DECL_ALIGN (decl
) = MIN (DECL_ALIGN (decl
), BITS_PER_UNIT
);
633 if (! packed_p
&& ! DECL_USER_ALIGN (decl
))
635 /* Some targets (i.e. i386, VMS) limit struct field alignment
636 to a lower boundary than alignment of variables unless
637 it was overridden by attribute aligned. */
638 #ifdef BIGGEST_FIELD_ALIGNMENT
640 = MIN (DECL_ALIGN (decl
), (unsigned) BIGGEST_FIELD_ALIGNMENT
);
642 #ifdef ADJUST_FIELD_ALIGN
643 DECL_ALIGN (decl
) = ADJUST_FIELD_ALIGN (decl
, DECL_ALIGN (decl
));
648 mfa
= initial_max_fld_align
* BITS_PER_UNIT
;
650 mfa
= maximum_field_alignment
;
651 /* Should this be controlled by DECL_USER_ALIGN, too? */
653 DECL_ALIGN (decl
) = MIN (DECL_ALIGN (decl
), mfa
);
656 /* Evaluate nonconstant size only once, either now or as soon as safe. */
657 if (DECL_SIZE (decl
) != 0 && TREE_CODE (DECL_SIZE (decl
)) != INTEGER_CST
)
658 DECL_SIZE (decl
) = variable_size (DECL_SIZE (decl
));
659 if (DECL_SIZE_UNIT (decl
) != 0
660 && TREE_CODE (DECL_SIZE_UNIT (decl
)) != INTEGER_CST
)
661 DECL_SIZE_UNIT (decl
) = variable_size (DECL_SIZE_UNIT (decl
));
663 /* If requested, warn about definitions of large data objects. */
665 && (code
== VAR_DECL
|| code
== PARM_DECL
)
666 && ! DECL_EXTERNAL (decl
))
668 tree size
= DECL_SIZE_UNIT (decl
);
670 if (size
!= 0 && TREE_CODE (size
) == INTEGER_CST
671 && compare_tree_int (size
, larger_than_size
) > 0)
673 int size_as_int
= TREE_INT_CST_LOW (size
);
675 if (compare_tree_int (size
, size_as_int
) == 0)
676 warning (OPT_Wlarger_than_eq
, "size of %q+D is %d bytes", decl
, size_as_int
);
678 warning (OPT_Wlarger_than_eq
, "size of %q+D is larger than %wd bytes",
679 decl
, larger_than_size
);
683 /* If the RTL was already set, update its mode and mem attributes. */
686 PUT_MODE (rtl
, DECL_MODE (decl
));
687 SET_DECL_RTL (decl
, 0);
688 set_mem_attributes (rtl
, decl
, 1);
689 SET_DECL_RTL (decl
, rtl
);
693 /* Given a VAR_DECL, PARM_DECL or RESULT_DECL, clears the results of
694 a previous call to layout_decl and calls it again. */
697 relayout_decl (tree decl
)
699 DECL_SIZE (decl
) = DECL_SIZE_UNIT (decl
) = 0;
700 DECL_MODE (decl
) = VOIDmode
;
701 if (!DECL_USER_ALIGN (decl
))
702 DECL_ALIGN (decl
) = 0;
703 SET_DECL_RTL (decl
, 0);
705 layout_decl (decl
, 0);
708 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
709 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
710 is to be passed to all other layout functions for this record. It is the
711 responsibility of the caller to call `free' for the storage returned.
712 Note that garbage collection is not permitted until we finish laying
716 start_record_layout (tree t
)
718 record_layout_info rli
= XNEW (struct record_layout_info_s
);
722 /* If the type has a minimum specified alignment (via an attribute
723 declaration, for example) use it -- otherwise, start with a
724 one-byte alignment. */
725 rli
->record_align
= MAX (BITS_PER_UNIT
, TYPE_ALIGN (t
));
726 rli
->unpacked_align
= rli
->record_align
;
727 rli
->offset_align
= MAX (rli
->record_align
, BIGGEST_ALIGNMENT
);
729 #ifdef STRUCTURE_SIZE_BOUNDARY
730 /* Packed structures don't need to have minimum size. */
731 if (! TYPE_PACKED (t
))
735 /* #pragma pack overrides STRUCTURE_SIZE_BOUNDARY. */
736 tmp
= (unsigned) STRUCTURE_SIZE_BOUNDARY
;
737 if (maximum_field_alignment
!= 0)
738 tmp
= MIN (tmp
, maximum_field_alignment
);
739 rli
->record_align
= MAX (rli
->record_align
, tmp
);
743 rli
->offset
= size_zero_node
;
744 rli
->bitpos
= bitsize_zero_node
;
746 rli
->pending_statics
= NULL
;
747 rli
->packed_maybe_necessary
= 0;
748 rli
->remaining_in_alignment
= 0;
753 /* These four routines perform computations that convert between
754 the offset/bitpos forms and byte and bit offsets. */
757 bit_from_pos (tree offset
, tree bitpos
)
759 return size_binop (PLUS_EXPR
, bitpos
,
760 size_binop (MULT_EXPR
,
761 fold_convert (bitsizetype
, offset
),
766 byte_from_pos (tree offset
, tree bitpos
)
768 return size_binop (PLUS_EXPR
, offset
,
769 fold_convert (sizetype
,
770 size_binop (TRUNC_DIV_EXPR
, bitpos
,
771 bitsize_unit_node
)));
775 pos_from_bit (tree
*poffset
, tree
*pbitpos
, unsigned int off_align
,
778 *poffset
= size_binop (MULT_EXPR
,
779 fold_convert (sizetype
,
780 size_binop (FLOOR_DIV_EXPR
, pos
,
781 bitsize_int (off_align
))),
782 size_int (off_align
/ BITS_PER_UNIT
));
783 *pbitpos
= size_binop (FLOOR_MOD_EXPR
, pos
, bitsize_int (off_align
));
786 /* Given a pointer to bit and byte offsets and an offset alignment,
787 normalize the offsets so they are within the alignment. */
790 normalize_offset (tree
*poffset
, tree
*pbitpos
, unsigned int off_align
)
792 /* If the bit position is now larger than it should be, adjust it
794 if (compare_tree_int (*pbitpos
, off_align
) >= 0)
796 tree extra_aligns
= size_binop (FLOOR_DIV_EXPR
, *pbitpos
,
797 bitsize_int (off_align
));
800 = size_binop (PLUS_EXPR
, *poffset
,
801 size_binop (MULT_EXPR
,
802 fold_convert (sizetype
, extra_aligns
),
803 size_int (off_align
/ BITS_PER_UNIT
)));
806 = size_binop (FLOOR_MOD_EXPR
, *pbitpos
, bitsize_int (off_align
));
810 /* Print debugging information about the information in RLI. */
813 debug_rli (record_layout_info rli
)
815 print_node_brief (stderr
, "type", rli
->t
, 0);
816 print_node_brief (stderr
, "\noffset", rli
->offset
, 0);
817 print_node_brief (stderr
, " bitpos", rli
->bitpos
, 0);
819 fprintf (stderr
, "\naligns: rec = %u, unpack = %u, off = %u\n",
820 rli
->record_align
, rli
->unpacked_align
,
823 /* The ms_struct code is the only that uses this. */
824 if (targetm
.ms_bitfield_layout_p (rli
->t
))
825 fprintf (stderr
, "remaining in alignment = %u\n", rli
->remaining_in_alignment
);
827 if (rli
->packed_maybe_necessary
)
828 fprintf (stderr
, "packed may be necessary\n");
830 if (!VEC_empty (tree
, rli
->pending_statics
))
832 fprintf (stderr
, "pending statics:\n");
833 debug_vec_tree (rli
->pending_statics
);
837 /* Given an RLI with a possibly-incremented BITPOS, adjust OFFSET and
838 BITPOS if necessary to keep BITPOS below OFFSET_ALIGN. */
841 normalize_rli (record_layout_info rli
)
843 normalize_offset (&rli
->offset
, &rli
->bitpos
, rli
->offset_align
);
846 /* Returns the size in bytes allocated so far. */
849 rli_size_unit_so_far (record_layout_info rli
)
851 return byte_from_pos (rli
->offset
, rli
->bitpos
);
854 /* Returns the size in bits allocated so far. */
857 rli_size_so_far (record_layout_info rli
)
859 return bit_from_pos (rli
->offset
, rli
->bitpos
);
862 /* FIELD is about to be added to RLI->T. The alignment (in bits) of
863 the next available location within the record is given by KNOWN_ALIGN.
864 Update the variable alignment fields in RLI, and return the alignment
865 to give the FIELD. */
868 update_alignment_for_field (record_layout_info rli
, tree field
,
869 unsigned int known_align
)
871 /* The alignment required for FIELD. */
872 unsigned int desired_align
;
873 /* The type of this field. */
874 tree type
= TREE_TYPE (field
);
875 /* True if the field was explicitly aligned by the user. */
879 /* Do not attempt to align an ERROR_MARK node */
880 if (TREE_CODE (type
) == ERROR_MARK
)
883 /* Lay out the field so we know what alignment it needs. */
884 layout_decl (field
, known_align
);
885 desired_align
= DECL_ALIGN (field
);
886 user_align
= DECL_USER_ALIGN (field
);
888 is_bitfield
= (type
!= error_mark_node
889 && DECL_BIT_FIELD_TYPE (field
)
890 && ! integer_zerop (TYPE_SIZE (type
)));
892 /* Record must have at least as much alignment as any field.
893 Otherwise, the alignment of the field within the record is
895 if (targetm
.ms_bitfield_layout_p (rli
->t
))
897 /* Here, the alignment of the underlying type of a bitfield can
898 affect the alignment of a record; even a zero-sized field
899 can do this. The alignment should be to the alignment of
900 the type, except that for zero-size bitfields this only
901 applies if there was an immediately prior, nonzero-size
902 bitfield. (That's the way it is, experimentally.) */
903 if ((!is_bitfield
&& !DECL_PACKED (field
))
904 || (!integer_zerop (DECL_SIZE (field
))
905 ? !DECL_PACKED (field
)
907 && DECL_BIT_FIELD_TYPE (rli
->prev_field
)
908 && ! integer_zerop (DECL_SIZE (rli
->prev_field
)))))
910 unsigned int type_align
= TYPE_ALIGN (type
);
911 type_align
= MAX (type_align
, desired_align
);
912 if (maximum_field_alignment
!= 0)
913 type_align
= MIN (type_align
, maximum_field_alignment
);
914 rli
->record_align
= MAX (rli
->record_align
, type_align
);
915 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
918 #ifdef PCC_BITFIELD_TYPE_MATTERS
919 else if (is_bitfield
&& PCC_BITFIELD_TYPE_MATTERS
)
921 /* Named bit-fields cause the entire structure to have the
922 alignment implied by their type. Some targets also apply the same
923 rules to unnamed bitfields. */
924 if (DECL_NAME (field
) != 0
925 || targetm
.align_anon_bitfield ())
927 unsigned int type_align
= TYPE_ALIGN (type
);
929 #ifdef ADJUST_FIELD_ALIGN
930 if (! TYPE_USER_ALIGN (type
))
931 type_align
= ADJUST_FIELD_ALIGN (field
, type_align
);
934 /* Targets might chose to handle unnamed and hence possibly
935 zero-width bitfield. Those are not influenced by #pragmas
936 or packed attributes. */
937 if (integer_zerop (DECL_SIZE (field
)))
939 if (initial_max_fld_align
)
940 type_align
= MIN (type_align
,
941 initial_max_fld_align
* BITS_PER_UNIT
);
943 else if (maximum_field_alignment
!= 0)
944 type_align
= MIN (type_align
, maximum_field_alignment
);
945 else if (DECL_PACKED (field
))
946 type_align
= MIN (type_align
, BITS_PER_UNIT
);
948 /* The alignment of the record is increased to the maximum
949 of the current alignment, the alignment indicated on the
950 field (i.e., the alignment specified by an __aligned__
951 attribute), and the alignment indicated by the type of
953 rli
->record_align
= MAX (rli
->record_align
, desired_align
);
954 rli
->record_align
= MAX (rli
->record_align
, type_align
);
957 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
958 user_align
|= TYPE_USER_ALIGN (type
);
964 rli
->record_align
= MAX (rli
->record_align
, desired_align
);
965 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
968 TYPE_USER_ALIGN (rli
->t
) |= user_align
;
970 return desired_align
;
973 /* Called from place_field to handle unions. */
976 place_union_field (record_layout_info rli
, tree field
)
978 update_alignment_for_field (rli
, field
, /*known_align=*/0);
980 DECL_FIELD_OFFSET (field
) = size_zero_node
;
981 DECL_FIELD_BIT_OFFSET (field
) = bitsize_zero_node
;
982 SET_DECL_OFFSET_ALIGN (field
, BIGGEST_ALIGNMENT
);
984 /* If this is an ERROR_MARK return *after* having set the
985 field at the start of the union. This helps when parsing
987 if (TREE_CODE (TREE_TYPE (field
)) == ERROR_MARK
)
990 /* We assume the union's size will be a multiple of a byte so we don't
991 bother with BITPOS. */
992 if (TREE_CODE (rli
->t
) == UNION_TYPE
)
993 rli
->offset
= size_binop (MAX_EXPR
, rli
->offset
, DECL_SIZE_UNIT (field
));
994 else if (TREE_CODE (rli
->t
) == QUAL_UNION_TYPE
)
995 rli
->offset
= fold_build3_loc (input_location
, COND_EXPR
, sizetype
,
996 DECL_QUALIFIER (field
),
997 DECL_SIZE_UNIT (field
), rli
->offset
);
1000 #if defined (PCC_BITFIELD_TYPE_MATTERS) || defined (BITFIELD_NBYTES_LIMITED)
1001 /* A bitfield of SIZE with a required access alignment of ALIGN is allocated
1002 at BYTE_OFFSET / BIT_OFFSET. Return nonzero if the field would span more
1003 units of alignment than the underlying TYPE. */
1005 excess_unit_span (HOST_WIDE_INT byte_offset
, HOST_WIDE_INT bit_offset
,
1006 HOST_WIDE_INT size
, HOST_WIDE_INT align
, tree type
)
1008 /* Note that the calculation of OFFSET might overflow; we calculate it so
1009 that we still get the right result as long as ALIGN is a power of two. */
1010 unsigned HOST_WIDE_INT offset
= byte_offset
* BITS_PER_UNIT
+ bit_offset
;
1012 offset
= offset
% align
;
1013 return ((offset
+ size
+ align
- 1) / align
1014 > ((unsigned HOST_WIDE_INT
) tree_low_cst (TYPE_SIZE (type
), 1)
1019 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
1020 is a FIELD_DECL to be added after those fields already present in
1021 T. (FIELD is not actually added to the TYPE_FIELDS list here;
1022 callers that desire that behavior must manually perform that step.) */
1025 place_field (record_layout_info rli
, tree field
)
1027 /* The alignment required for FIELD. */
1028 unsigned int desired_align
;
1029 /* The alignment FIELD would have if we just dropped it into the
1030 record as it presently stands. */
1031 unsigned int known_align
;
1032 unsigned int actual_align
;
1033 /* The type of this field. */
1034 tree type
= TREE_TYPE (field
);
1036 gcc_assert (TREE_CODE (field
) != ERROR_MARK
);
1038 /* If FIELD is static, then treat it like a separate variable, not
1039 really like a structure field. If it is a FUNCTION_DECL, it's a
1040 method. In both cases, all we do is lay out the decl, and we do
1041 it *after* the record is laid out. */
1042 if (TREE_CODE (field
) == VAR_DECL
)
1044 VEC_safe_push (tree
, gc
, rli
->pending_statics
, field
);
1048 /* Enumerators and enum types which are local to this class need not
1049 be laid out. Likewise for initialized constant fields. */
1050 else if (TREE_CODE (field
) != FIELD_DECL
)
1053 /* Unions are laid out very differently than records, so split
1054 that code off to another function. */
1055 else if (TREE_CODE (rli
->t
) != RECORD_TYPE
)
1057 place_union_field (rli
, field
);
1061 else if (TREE_CODE (type
) == ERROR_MARK
)
1063 /* Place this field at the current allocation position, so we
1064 maintain monotonicity. */
1065 DECL_FIELD_OFFSET (field
) = rli
->offset
;
1066 DECL_FIELD_BIT_OFFSET (field
) = rli
->bitpos
;
1067 SET_DECL_OFFSET_ALIGN (field
, rli
->offset_align
);
1071 /* Work out the known alignment so far. Note that A & (-A) is the
1072 value of the least-significant bit in A that is one. */
1073 if (! integer_zerop (rli
->bitpos
))
1074 known_align
= (tree_low_cst (rli
->bitpos
, 1)
1075 & - tree_low_cst (rli
->bitpos
, 1));
1076 else if (integer_zerop (rli
->offset
))
1078 else if (host_integerp (rli
->offset
, 1))
1079 known_align
= (BITS_PER_UNIT
1080 * (tree_low_cst (rli
->offset
, 1)
1081 & - tree_low_cst (rli
->offset
, 1)));
1083 known_align
= rli
->offset_align
;
1085 desired_align
= update_alignment_for_field (rli
, field
, known_align
);
1086 if (known_align
== 0)
1087 known_align
= MAX (BIGGEST_ALIGNMENT
, rli
->record_align
);
1089 if (warn_packed
&& DECL_PACKED (field
))
1091 if (known_align
>= TYPE_ALIGN (type
))
1093 if (TYPE_ALIGN (type
) > desired_align
)
1095 if (STRICT_ALIGNMENT
)
1096 warning (OPT_Wattributes
, "packed attribute causes "
1097 "inefficient alignment for %q+D", field
);
1098 /* Don't warn if DECL_PACKED was set by the type. */
1099 else if (!TYPE_PACKED (rli
->t
))
1100 warning (OPT_Wattributes
, "packed attribute is "
1101 "unnecessary for %q+D", field
);
1105 rli
->packed_maybe_necessary
= 1;
1108 /* Does this field automatically have alignment it needs by virtue
1109 of the fields that precede it and the record's own alignment?
1110 We already align ms_struct fields, so don't re-align them. */
1111 if (known_align
< desired_align
1112 && !targetm
.ms_bitfield_layout_p (rli
->t
))
1114 /* No, we need to skip space before this field.
1115 Bump the cumulative size to multiple of field alignment. */
1117 if (DECL_SOURCE_LOCATION (field
) != BUILTINS_LOCATION
)
1118 warning (OPT_Wpadded
, "padding struct to align %q+D", field
);
1120 /* If the alignment is still within offset_align, just align
1121 the bit position. */
1122 if (desired_align
< rli
->offset_align
)
1123 rli
->bitpos
= round_up (rli
->bitpos
, desired_align
);
1126 /* First adjust OFFSET by the partial bits, then align. */
1128 = size_binop (PLUS_EXPR
, rli
->offset
,
1129 fold_convert (sizetype
,
1130 size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
1131 bitsize_unit_node
)));
1132 rli
->bitpos
= bitsize_zero_node
;
1134 rli
->offset
= round_up (rli
->offset
, desired_align
/ BITS_PER_UNIT
);
1137 if (! TREE_CONSTANT (rli
->offset
))
1138 rli
->offset_align
= desired_align
;
1142 /* Handle compatibility with PCC. Note that if the record has any
1143 variable-sized fields, we need not worry about compatibility. */
1144 #ifdef PCC_BITFIELD_TYPE_MATTERS
1145 if (PCC_BITFIELD_TYPE_MATTERS
1146 && ! targetm
.ms_bitfield_layout_p (rli
->t
)
1147 && TREE_CODE (field
) == FIELD_DECL
1148 && type
!= error_mark_node
1149 && DECL_BIT_FIELD (field
)
1150 && (! DECL_PACKED (field
)
1151 /* Enter for these packed fields only to issue a warning. */
1152 || TYPE_ALIGN (type
) <= BITS_PER_UNIT
)
1153 && maximum_field_alignment
== 0
1154 && ! integer_zerop (DECL_SIZE (field
))
1155 && host_integerp (DECL_SIZE (field
), 1)
1156 && host_integerp (rli
->offset
, 1)
1157 && host_integerp (TYPE_SIZE (type
), 1))
1159 unsigned int type_align
= TYPE_ALIGN (type
);
1160 tree dsize
= DECL_SIZE (field
);
1161 HOST_WIDE_INT field_size
= tree_low_cst (dsize
, 1);
1162 HOST_WIDE_INT offset
= tree_low_cst (rli
->offset
, 0);
1163 HOST_WIDE_INT bit_offset
= tree_low_cst (rli
->bitpos
, 0);
1165 #ifdef ADJUST_FIELD_ALIGN
1166 if (! TYPE_USER_ALIGN (type
))
1167 type_align
= ADJUST_FIELD_ALIGN (field
, type_align
);
1170 /* A bit field may not span more units of alignment of its type
1171 than its type itself. Advance to next boundary if necessary. */
1172 if (excess_unit_span (offset
, bit_offset
, field_size
, type_align
, type
))
1174 if (DECL_PACKED (field
))
1176 if (warn_packed_bitfield_compat
== 1)
1179 "Offset of packed bit-field %qD has changed in GCC 4.4",
1183 rli
->bitpos
= round_up_loc (input_location
, rli
->bitpos
, type_align
);
1186 if (! DECL_PACKED (field
))
1187 TYPE_USER_ALIGN (rli
->t
) |= TYPE_USER_ALIGN (type
);
1191 #ifdef BITFIELD_NBYTES_LIMITED
1192 if (BITFIELD_NBYTES_LIMITED
1193 && ! targetm
.ms_bitfield_layout_p (rli
->t
)
1194 && TREE_CODE (field
) == FIELD_DECL
1195 && type
!= error_mark_node
1196 && DECL_BIT_FIELD_TYPE (field
)
1197 && ! DECL_PACKED (field
)
1198 && ! integer_zerop (DECL_SIZE (field
))
1199 && host_integerp (DECL_SIZE (field
), 1)
1200 && host_integerp (rli
->offset
, 1)
1201 && host_integerp (TYPE_SIZE (type
), 1))
1203 unsigned int type_align
= TYPE_ALIGN (type
);
1204 tree dsize
= DECL_SIZE (field
);
1205 HOST_WIDE_INT field_size
= tree_low_cst (dsize
, 1);
1206 HOST_WIDE_INT offset
= tree_low_cst (rli
->offset
, 0);
1207 HOST_WIDE_INT bit_offset
= tree_low_cst (rli
->bitpos
, 0);
1209 #ifdef ADJUST_FIELD_ALIGN
1210 if (! TYPE_USER_ALIGN (type
))
1211 type_align
= ADJUST_FIELD_ALIGN (field
, type_align
);
1214 if (maximum_field_alignment
!= 0)
1215 type_align
= MIN (type_align
, maximum_field_alignment
);
1216 /* ??? This test is opposite the test in the containing if
1217 statement, so this code is unreachable currently. */
1218 else if (DECL_PACKED (field
))
1219 type_align
= MIN (type_align
, BITS_PER_UNIT
);
1221 /* A bit field may not span the unit of alignment of its type.
1222 Advance to next boundary if necessary. */
1223 if (excess_unit_span (offset
, bit_offset
, field_size
, type_align
, type
))
1224 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1226 TYPE_USER_ALIGN (rli
->t
) |= TYPE_USER_ALIGN (type
);
1230 /* See the docs for TARGET_MS_BITFIELD_LAYOUT_P for details.
1232 When a bit field is inserted into a packed record, the whole
1233 size of the underlying type is used by one or more same-size
1234 adjacent bitfields. (That is, if its long:3, 32 bits is
1235 used in the record, and any additional adjacent long bitfields are
1236 packed into the same chunk of 32 bits. However, if the size
1237 changes, a new field of that size is allocated.) In an unpacked
1238 record, this is the same as using alignment, but not equivalent
1241 Note: for compatibility, we use the type size, not the type alignment
1242 to determine alignment, since that matches the documentation */
1244 if (targetm
.ms_bitfield_layout_p (rli
->t
))
1246 tree prev_saved
= rli
->prev_field
;
1247 tree prev_type
= prev_saved
? DECL_BIT_FIELD_TYPE (prev_saved
) : NULL
;
1249 /* This is a bitfield if it exists. */
1250 if (rli
->prev_field
)
1252 /* If both are bitfields, nonzero, and the same size, this is
1253 the middle of a run. Zero declared size fields are special
1254 and handled as "end of run". (Note: it's nonzero declared
1255 size, but equal type sizes!) (Since we know that both
1256 the current and previous fields are bitfields by the
1257 time we check it, DECL_SIZE must be present for both.) */
1258 if (DECL_BIT_FIELD_TYPE (field
)
1259 && !integer_zerop (DECL_SIZE (field
))
1260 && !integer_zerop (DECL_SIZE (rli
->prev_field
))
1261 && host_integerp (DECL_SIZE (rli
->prev_field
), 0)
1262 && host_integerp (TYPE_SIZE (type
), 0)
1263 && simple_cst_equal (TYPE_SIZE (type
), TYPE_SIZE (prev_type
)))
1265 /* We're in the middle of a run of equal type size fields; make
1266 sure we realign if we run out of bits. (Not decl size,
1268 HOST_WIDE_INT bitsize
= tree_low_cst (DECL_SIZE (field
), 1);
1270 if (rli
->remaining_in_alignment
< bitsize
)
1272 HOST_WIDE_INT typesize
= tree_low_cst (TYPE_SIZE (type
), 1);
1274 /* out of bits; bump up to next 'word'. */
1276 = size_binop (PLUS_EXPR
, rli
->bitpos
,
1277 bitsize_int (rli
->remaining_in_alignment
));
1278 rli
->prev_field
= field
;
1279 if (typesize
< bitsize
)
1280 rli
->remaining_in_alignment
= 0;
1282 rli
->remaining_in_alignment
= typesize
- bitsize
;
1285 rli
->remaining_in_alignment
-= bitsize
;
1289 /* End of a run: if leaving a run of bitfields of the same type
1290 size, we have to "use up" the rest of the bits of the type
1293 Compute the new position as the sum of the size for the prior
1294 type and where we first started working on that type.
1295 Note: since the beginning of the field was aligned then
1296 of course the end will be too. No round needed. */
1298 if (!integer_zerop (DECL_SIZE (rli
->prev_field
)))
1301 = size_binop (PLUS_EXPR
, rli
->bitpos
,
1302 bitsize_int (rli
->remaining_in_alignment
));
1305 /* We "use up" size zero fields; the code below should behave
1306 as if the prior field was not a bitfield. */
1309 /* Cause a new bitfield to be captured, either this time (if
1310 currently a bitfield) or next time we see one. */
1311 if (!DECL_BIT_FIELD_TYPE(field
)
1312 || integer_zerop (DECL_SIZE (field
)))
1313 rli
->prev_field
= NULL
;
1316 normalize_rli (rli
);
1319 /* If we're starting a new run of same size type bitfields
1320 (or a run of non-bitfields), set up the "first of the run"
1323 That is, if the current field is not a bitfield, or if there
1324 was a prior bitfield the type sizes differ, or if there wasn't
1325 a prior bitfield the size of the current field is nonzero.
1327 Note: we must be sure to test ONLY the type size if there was
1328 a prior bitfield and ONLY for the current field being zero if
1331 if (!DECL_BIT_FIELD_TYPE (field
)
1332 || (prev_saved
!= NULL
1333 ? !simple_cst_equal (TYPE_SIZE (type
), TYPE_SIZE (prev_type
))
1334 : !integer_zerop (DECL_SIZE (field
)) ))
1336 /* Never smaller than a byte for compatibility. */
1337 unsigned int type_align
= BITS_PER_UNIT
;
1339 /* (When not a bitfield), we could be seeing a flex array (with
1340 no DECL_SIZE). Since we won't be using remaining_in_alignment
1341 until we see a bitfield (and come by here again) we just skip
1343 if (DECL_SIZE (field
) != NULL
1344 && host_integerp (TYPE_SIZE (TREE_TYPE (field
)), 1)
1345 && host_integerp (DECL_SIZE (field
), 1))
1347 unsigned HOST_WIDE_INT bitsize
1348 = tree_low_cst (DECL_SIZE (field
), 1);
1349 unsigned HOST_WIDE_INT typesize
1350 = tree_low_cst (TYPE_SIZE (TREE_TYPE (field
)), 1);
1352 if (typesize
< bitsize
)
1353 rli
->remaining_in_alignment
= 0;
1355 rli
->remaining_in_alignment
= typesize
- bitsize
;
1358 /* Now align (conventionally) for the new type. */
1359 type_align
= TYPE_ALIGN (TREE_TYPE (field
));
1361 if (maximum_field_alignment
!= 0)
1362 type_align
= MIN (type_align
, maximum_field_alignment
);
1364 rli
->bitpos
= round_up_loc (input_location
, rli
->bitpos
, type_align
);
1366 /* If we really aligned, don't allow subsequent bitfields
1368 rli
->prev_field
= NULL
;
1372 /* Offset so far becomes the position of this field after normalizing. */
1373 normalize_rli (rli
);
1374 DECL_FIELD_OFFSET (field
) = rli
->offset
;
1375 DECL_FIELD_BIT_OFFSET (field
) = rli
->bitpos
;
1376 SET_DECL_OFFSET_ALIGN (field
, rli
->offset_align
);
1378 /* If this field ended up more aligned than we thought it would be (we
1379 approximate this by seeing if its position changed), lay out the field
1380 again; perhaps we can use an integral mode for it now. */
1381 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field
)))
1382 actual_align
= (tree_low_cst (DECL_FIELD_BIT_OFFSET (field
), 1)
1383 & - tree_low_cst (DECL_FIELD_BIT_OFFSET (field
), 1));
1384 else if (integer_zerop (DECL_FIELD_OFFSET (field
)))
1385 actual_align
= MAX (BIGGEST_ALIGNMENT
, rli
->record_align
);
1386 else if (host_integerp (DECL_FIELD_OFFSET (field
), 1))
1387 actual_align
= (BITS_PER_UNIT
1388 * (tree_low_cst (DECL_FIELD_OFFSET (field
), 1)
1389 & - tree_low_cst (DECL_FIELD_OFFSET (field
), 1)));
1391 actual_align
= DECL_OFFSET_ALIGN (field
);
1392 /* ACTUAL_ALIGN is still the actual alignment *within the record* .
1393 store / extract bit field operations will check the alignment of the
1394 record against the mode of bit fields. */
1396 if (known_align
!= actual_align
)
1397 layout_decl (field
, actual_align
);
1399 if (rli
->prev_field
== NULL
&& DECL_BIT_FIELD_TYPE (field
))
1400 rli
->prev_field
= field
;
1402 /* Now add size of this field to the size of the record. If the size is
1403 not constant, treat the field as being a multiple of bytes and just
1404 adjust the offset, resetting the bit position. Otherwise, apportion the
1405 size amongst the bit position and offset. First handle the case of an
1406 unspecified size, which can happen when we have an invalid nested struct
1407 definition, such as struct j { struct j { int i; } }. The error message
1408 is printed in finish_struct. */
1409 if (DECL_SIZE (field
) == 0)
1411 else if (TREE_CODE (DECL_SIZE (field
)) != INTEGER_CST
1412 || TREE_OVERFLOW (DECL_SIZE (field
)))
1415 = size_binop (PLUS_EXPR
, rli
->offset
,
1416 fold_convert (sizetype
,
1417 size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
1418 bitsize_unit_node
)));
1420 = size_binop (PLUS_EXPR
, rli
->offset
, DECL_SIZE_UNIT (field
));
1421 rli
->bitpos
= bitsize_zero_node
;
1422 rli
->offset_align
= MIN (rli
->offset_align
, desired_align
);
1424 else if (targetm
.ms_bitfield_layout_p (rli
->t
))
1426 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
, DECL_SIZE (field
));
1428 /* If we ended a bitfield before the full length of the type then
1429 pad the struct out to the full length of the last type. */
1430 if ((TREE_CHAIN (field
) == NULL
1431 || TREE_CODE (TREE_CHAIN (field
)) != FIELD_DECL
)
1432 && DECL_BIT_FIELD_TYPE (field
)
1433 && !integer_zerop (DECL_SIZE (field
)))
1434 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
,
1435 bitsize_int (rli
->remaining_in_alignment
));
1437 normalize_rli (rli
);
1441 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
, DECL_SIZE (field
));
1442 normalize_rli (rli
);
1446 /* Assuming that all the fields have been laid out, this function uses
1447 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
1448 indicated by RLI. */
1451 finalize_record_size (record_layout_info rli
)
1453 tree unpadded_size
, unpadded_size_unit
;
1455 /* Now we want just byte and bit offsets, so set the offset alignment
1456 to be a byte and then normalize. */
1457 rli
->offset_align
= BITS_PER_UNIT
;
1458 normalize_rli (rli
);
1460 /* Determine the desired alignment. */
1461 #ifdef ROUND_TYPE_ALIGN
1462 TYPE_ALIGN (rli
->t
) = ROUND_TYPE_ALIGN (rli
->t
, TYPE_ALIGN (rli
->t
),
1465 TYPE_ALIGN (rli
->t
) = MAX (TYPE_ALIGN (rli
->t
), rli
->record_align
);
1468 /* Compute the size so far. Be sure to allow for extra bits in the
1469 size in bytes. We have guaranteed above that it will be no more
1470 than a single byte. */
1471 unpadded_size
= rli_size_so_far (rli
);
1472 unpadded_size_unit
= rli_size_unit_so_far (rli
);
1473 if (! integer_zerop (rli
->bitpos
))
1475 = size_binop (PLUS_EXPR
, unpadded_size_unit
, size_one_node
);
1477 /* Round the size up to be a multiple of the required alignment. */
1478 TYPE_SIZE (rli
->t
) = round_up_loc (input_location
, unpadded_size
,
1479 TYPE_ALIGN (rli
->t
));
1480 TYPE_SIZE_UNIT (rli
->t
)
1481 = round_up_loc (input_location
, unpadded_size_unit
, TYPE_ALIGN_UNIT (rli
->t
));
1483 if (TREE_CONSTANT (unpadded_size
)
1484 && simple_cst_equal (unpadded_size
, TYPE_SIZE (rli
->t
)) == 0
1485 && input_location
!= BUILTINS_LOCATION
)
1486 warning (OPT_Wpadded
, "padding struct size to alignment boundary");
1488 if (warn_packed
&& TREE_CODE (rli
->t
) == RECORD_TYPE
1489 && TYPE_PACKED (rli
->t
) && ! rli
->packed_maybe_necessary
1490 && TREE_CONSTANT (unpadded_size
))
1494 #ifdef ROUND_TYPE_ALIGN
1496 = ROUND_TYPE_ALIGN (rli
->t
, TYPE_ALIGN (rli
->t
), rli
->unpacked_align
);
1498 rli
->unpacked_align
= MAX (TYPE_ALIGN (rli
->t
), rli
->unpacked_align
);
1501 unpacked_size
= round_up_loc (input_location
, TYPE_SIZE (rli
->t
), rli
->unpacked_align
);
1502 if (simple_cst_equal (unpacked_size
, TYPE_SIZE (rli
->t
)))
1504 if (TYPE_NAME (rli
->t
))
1508 if (TREE_CODE (TYPE_NAME (rli
->t
)) == IDENTIFIER_NODE
)
1509 name
= TYPE_NAME (rli
->t
);
1511 name
= DECL_NAME (TYPE_NAME (rli
->t
));
1513 if (STRICT_ALIGNMENT
)
1514 warning (OPT_Wpacked
, "packed attribute causes inefficient "
1515 "alignment for %qE", name
);
1517 warning (OPT_Wpacked
,
1518 "packed attribute is unnecessary for %qE", name
);
1522 if (STRICT_ALIGNMENT
)
1523 warning (OPT_Wpacked
,
1524 "packed attribute causes inefficient alignment");
1526 warning (OPT_Wpacked
, "packed attribute is unnecessary");
1532 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
1535 compute_record_mode (tree type
)
1538 enum machine_mode mode
= VOIDmode
;
1540 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
1541 However, if possible, we use a mode that fits in a register
1542 instead, in order to allow for better optimization down the
1544 SET_TYPE_MODE (type
, BLKmode
);
1546 if (! host_integerp (TYPE_SIZE (type
), 1))
1549 /* A record which has any BLKmode members must itself be
1550 BLKmode; it can't go in a register. Unless the member is
1551 BLKmode only because it isn't aligned. */
1552 for (field
= TYPE_FIELDS (type
); field
; field
= TREE_CHAIN (field
))
1554 if (TREE_CODE (field
) != FIELD_DECL
)
1557 if (TREE_CODE (TREE_TYPE (field
)) == ERROR_MARK
1558 || (TYPE_MODE (TREE_TYPE (field
)) == BLKmode
1559 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field
))
1560 && !(TYPE_SIZE (TREE_TYPE (field
)) != 0
1561 && integer_zerop (TYPE_SIZE (TREE_TYPE (field
)))))
1562 || ! host_integerp (bit_position (field
), 1)
1563 || DECL_SIZE (field
) == 0
1564 || ! host_integerp (DECL_SIZE (field
), 1))
1567 /* If this field is the whole struct, remember its mode so
1568 that, say, we can put a double in a class into a DF
1569 register instead of forcing it to live in the stack. */
1570 if (simple_cst_equal (TYPE_SIZE (type
), DECL_SIZE (field
)))
1571 mode
= DECL_MODE (field
);
1573 #ifdef MEMBER_TYPE_FORCES_BLK
1574 /* With some targets, eg. c4x, it is sub-optimal
1575 to access an aligned BLKmode structure as a scalar. */
1577 if (MEMBER_TYPE_FORCES_BLK (field
, mode
))
1579 #endif /* MEMBER_TYPE_FORCES_BLK */
1582 /* If we only have one real field; use its mode if that mode's size
1583 matches the type's size. This only applies to RECORD_TYPE. This
1584 does not apply to unions. */
1585 if (TREE_CODE (type
) == RECORD_TYPE
&& mode
!= VOIDmode
1586 && host_integerp (TYPE_SIZE (type
), 1)
1587 && GET_MODE_BITSIZE (mode
) == TREE_INT_CST_LOW (TYPE_SIZE (type
)))
1588 SET_TYPE_MODE (type
, mode
);
1590 SET_TYPE_MODE (type
, mode_for_size_tree (TYPE_SIZE (type
), MODE_INT
, 1));
1592 /* If structure's known alignment is less than what the scalar
1593 mode would need, and it matters, then stick with BLKmode. */
1594 if (TYPE_MODE (type
) != BLKmode
1596 && ! (TYPE_ALIGN (type
) >= BIGGEST_ALIGNMENT
1597 || TYPE_ALIGN (type
) >= GET_MODE_ALIGNMENT (TYPE_MODE (type
))))
1599 /* If this is the only reason this type is BLKmode, then
1600 don't force containing types to be BLKmode. */
1601 TYPE_NO_FORCE_BLK (type
) = 1;
1602 SET_TYPE_MODE (type
, BLKmode
);
1606 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1610 finalize_type_size (tree type
)
1612 /* Normally, use the alignment corresponding to the mode chosen.
1613 However, where strict alignment is not required, avoid
1614 over-aligning structures, since most compilers do not do this
1617 if (TYPE_MODE (type
) != BLKmode
&& TYPE_MODE (type
) != VOIDmode
1618 && (STRICT_ALIGNMENT
1619 || (TREE_CODE (type
) != RECORD_TYPE
&& TREE_CODE (type
) != UNION_TYPE
1620 && TREE_CODE (type
) != QUAL_UNION_TYPE
1621 && TREE_CODE (type
) != ARRAY_TYPE
)))
1623 unsigned mode_align
= GET_MODE_ALIGNMENT (TYPE_MODE (type
));
1625 /* Don't override a larger alignment requirement coming from a user
1626 alignment of one of the fields. */
1627 if (mode_align
>= TYPE_ALIGN (type
))
1629 TYPE_ALIGN (type
) = mode_align
;
1630 TYPE_USER_ALIGN (type
) = 0;
1634 /* Do machine-dependent extra alignment. */
1635 #ifdef ROUND_TYPE_ALIGN
1637 = ROUND_TYPE_ALIGN (type
, TYPE_ALIGN (type
), BITS_PER_UNIT
);
1640 /* If we failed to find a simple way to calculate the unit size
1641 of the type, find it by division. */
1642 if (TYPE_SIZE_UNIT (type
) == 0 && TYPE_SIZE (type
) != 0)
1643 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1644 result will fit in sizetype. We will get more efficient code using
1645 sizetype, so we force a conversion. */
1646 TYPE_SIZE_UNIT (type
)
1647 = fold_convert (sizetype
,
1648 size_binop (FLOOR_DIV_EXPR
, TYPE_SIZE (type
),
1649 bitsize_unit_node
));
1651 if (TYPE_SIZE (type
) != 0)
1653 TYPE_SIZE (type
) = round_up_loc (input_location
,
1654 TYPE_SIZE (type
), TYPE_ALIGN (type
));
1655 TYPE_SIZE_UNIT (type
) = round_up_loc (input_location
, TYPE_SIZE_UNIT (type
),
1656 TYPE_ALIGN_UNIT (type
));
1659 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1660 if (TYPE_SIZE (type
) != 0 && TREE_CODE (TYPE_SIZE (type
)) != INTEGER_CST
)
1661 TYPE_SIZE (type
) = variable_size (TYPE_SIZE (type
));
1662 if (TYPE_SIZE_UNIT (type
) != 0
1663 && TREE_CODE (TYPE_SIZE_UNIT (type
)) != INTEGER_CST
)
1664 TYPE_SIZE_UNIT (type
) = variable_size (TYPE_SIZE_UNIT (type
));
1666 /* Also layout any other variants of the type. */
1667 if (TYPE_NEXT_VARIANT (type
)
1668 || type
!= TYPE_MAIN_VARIANT (type
))
1671 /* Record layout info of this variant. */
1672 tree size
= TYPE_SIZE (type
);
1673 tree size_unit
= TYPE_SIZE_UNIT (type
);
1674 unsigned int align
= TYPE_ALIGN (type
);
1675 unsigned int user_align
= TYPE_USER_ALIGN (type
);
1676 enum machine_mode mode
= TYPE_MODE (type
);
1678 /* Copy it into all variants. */
1679 for (variant
= TYPE_MAIN_VARIANT (type
);
1681 variant
= TYPE_NEXT_VARIANT (variant
))
1683 TYPE_SIZE (variant
) = size
;
1684 TYPE_SIZE_UNIT (variant
) = size_unit
;
1685 TYPE_ALIGN (variant
) = align
;
1686 TYPE_USER_ALIGN (variant
) = user_align
;
1687 SET_TYPE_MODE (variant
, mode
);
1692 /* Do all of the work required to layout the type indicated by RLI,
1693 once the fields have been laid out. This function will call `free'
1694 for RLI, unless FREE_P is false. Passing a value other than false
1695 for FREE_P is bad practice; this option only exists to support the
1699 finish_record_layout (record_layout_info rli
, int free_p
)
1703 /* Compute the final size. */
1704 finalize_record_size (rli
);
1706 /* Compute the TYPE_MODE for the record. */
1707 compute_record_mode (rli
->t
);
1709 /* Perform any last tweaks to the TYPE_SIZE, etc. */
1710 finalize_type_size (rli
->t
);
1712 /* Propagate TYPE_PACKED to variants. With C++ templates,
1713 handle_packed_attribute is too early to do this. */
1714 for (variant
= TYPE_NEXT_VARIANT (rli
->t
); variant
;
1715 variant
= TYPE_NEXT_VARIANT (variant
))
1716 TYPE_PACKED (variant
) = TYPE_PACKED (rli
->t
);
1718 /* Lay out any static members. This is done now because their type
1719 may use the record's type. */
1720 while (!VEC_empty (tree
, rli
->pending_statics
))
1721 layout_decl (VEC_pop (tree
, rli
->pending_statics
), 0);
1726 VEC_free (tree
, gc
, rli
->pending_statics
);
1732 /* Finish processing a builtin RECORD_TYPE type TYPE. It's name is
1733 NAME, its fields are chained in reverse on FIELDS.
1735 If ALIGN_TYPE is non-null, it is given the same alignment as
1739 finish_builtin_struct (tree type
, const char *name
, tree fields
,
1744 for (tail
= NULL_TREE
; fields
; tail
= fields
, fields
= next
)
1746 DECL_FIELD_CONTEXT (fields
) = type
;
1747 next
= TREE_CHAIN (fields
);
1748 TREE_CHAIN (fields
) = tail
;
1750 TYPE_FIELDS (type
) = tail
;
1754 TYPE_ALIGN (type
) = TYPE_ALIGN (align_type
);
1755 TYPE_USER_ALIGN (type
) = TYPE_USER_ALIGN (align_type
);
1759 #if 0 /* not yet, should get fixed properly later */
1760 TYPE_NAME (type
) = make_type_decl (get_identifier (name
), type
);
1762 TYPE_NAME (type
) = build_decl (BUILTINS_LOCATION
,
1763 TYPE_DECL
, get_identifier (name
), type
);
1765 TYPE_STUB_DECL (type
) = TYPE_NAME (type
);
1766 layout_decl (TYPE_NAME (type
), 0);
1769 /* Calculate the mode, size, and alignment for TYPE.
1770 For an array type, calculate the element separation as well.
1771 Record TYPE on the chain of permanent or temporary types
1772 so that dbxout will find out about it.
1774 TYPE_SIZE of a type is nonzero if the type has been laid out already.
1775 layout_type does nothing on such a type.
1777 If the type is incomplete, its TYPE_SIZE remains zero. */
1780 layout_type (tree type
)
1784 if (type
== error_mark_node
)
1787 /* Do nothing if type has been laid out before. */
1788 if (TYPE_SIZE (type
))
1791 switch (TREE_CODE (type
))
1794 /* This kind of type is the responsibility
1795 of the language-specific code. */
1798 case BOOLEAN_TYPE
: /* Used for Java, Pascal, and Chill. */
1799 if (TYPE_PRECISION (type
) == 0)
1800 TYPE_PRECISION (type
) = 1; /* default to one byte/boolean. */
1802 /* ... fall through ... */
1806 if (TREE_CODE (TYPE_MIN_VALUE (type
)) == INTEGER_CST
1807 && tree_int_cst_sgn (TYPE_MIN_VALUE (type
)) >= 0)
1808 TYPE_UNSIGNED (type
) = 1;
1810 SET_TYPE_MODE (type
,
1811 smallest_mode_for_size (TYPE_PRECISION (type
), MODE_INT
));
1812 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
1813 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
1817 SET_TYPE_MODE (type
,
1818 mode_for_size (TYPE_PRECISION (type
), MODE_FLOAT
, 0));
1819 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
1820 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
1823 case FIXED_POINT_TYPE
:
1824 /* TYPE_MODE (type) has been set already. */
1825 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
1826 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
1830 TYPE_UNSIGNED (type
) = TYPE_UNSIGNED (TREE_TYPE (type
));
1831 SET_TYPE_MODE (type
,
1832 mode_for_size (2 * TYPE_PRECISION (TREE_TYPE (type
)),
1833 (TREE_CODE (TREE_TYPE (type
)) == REAL_TYPE
1834 ? MODE_COMPLEX_FLOAT
: MODE_COMPLEX_INT
),
1836 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
1837 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
1842 int nunits
= TYPE_VECTOR_SUBPARTS (type
);
1843 tree innertype
= TREE_TYPE (type
);
1845 gcc_assert (!(nunits
& (nunits
- 1)));
1847 /* Find an appropriate mode for the vector type. */
1848 if (TYPE_MODE (type
) == VOIDmode
)
1850 enum machine_mode innermode
= TYPE_MODE (innertype
);
1851 enum machine_mode mode
;
1853 /* First, look for a supported vector type. */
1854 if (SCALAR_FLOAT_MODE_P (innermode
))
1855 mode
= MIN_MODE_VECTOR_FLOAT
;
1856 else if (SCALAR_FRACT_MODE_P (innermode
))
1857 mode
= MIN_MODE_VECTOR_FRACT
;
1858 else if (SCALAR_UFRACT_MODE_P (innermode
))
1859 mode
= MIN_MODE_VECTOR_UFRACT
;
1860 else if (SCALAR_ACCUM_MODE_P (innermode
))
1861 mode
= MIN_MODE_VECTOR_ACCUM
;
1862 else if (SCALAR_UACCUM_MODE_P (innermode
))
1863 mode
= MIN_MODE_VECTOR_UACCUM
;
1865 mode
= MIN_MODE_VECTOR_INT
;
1867 /* Do not check vector_mode_supported_p here. We'll do that
1868 later in vector_type_mode. */
1869 for (; mode
!= VOIDmode
; mode
= GET_MODE_WIDER_MODE (mode
))
1870 if (GET_MODE_NUNITS (mode
) == nunits
1871 && GET_MODE_INNER (mode
) == innermode
)
1874 /* For integers, try mapping it to a same-sized scalar mode. */
1875 if (mode
== VOIDmode
1876 && GET_MODE_CLASS (innermode
) == MODE_INT
)
1877 mode
= mode_for_size (nunits
* GET_MODE_BITSIZE (innermode
),
1880 if (mode
== VOIDmode
||
1881 (GET_MODE_CLASS (mode
) == MODE_INT
1882 && !have_regs_of_mode
[mode
]))
1883 SET_TYPE_MODE (type
, BLKmode
);
1885 SET_TYPE_MODE (type
, mode
);
1888 TYPE_SATURATING (type
) = TYPE_SATURATING (TREE_TYPE (type
));
1889 TYPE_UNSIGNED (type
) = TYPE_UNSIGNED (TREE_TYPE (type
));
1890 TYPE_SIZE_UNIT (type
) = int_const_binop (MULT_EXPR
,
1891 TYPE_SIZE_UNIT (innertype
),
1892 size_int (nunits
), 0);
1893 TYPE_SIZE (type
) = int_const_binop (MULT_EXPR
, TYPE_SIZE (innertype
),
1894 bitsize_int (nunits
), 0);
1896 /* Always naturally align vectors. This prevents ABI changes
1897 depending on whether or not native vector modes are supported. */
1898 TYPE_ALIGN (type
) = tree_low_cst (TYPE_SIZE (type
), 0);
1903 /* This is an incomplete type and so doesn't have a size. */
1904 TYPE_ALIGN (type
) = 1;
1905 TYPE_USER_ALIGN (type
) = 0;
1906 SET_TYPE_MODE (type
, VOIDmode
);
1910 TYPE_SIZE (type
) = bitsize_int (POINTER_SIZE
);
1911 TYPE_SIZE_UNIT (type
) = size_int (POINTER_SIZE
/ BITS_PER_UNIT
);
1912 /* A pointer might be MODE_PARTIAL_INT,
1913 but ptrdiff_t must be integral. */
1914 SET_TYPE_MODE (type
, mode_for_size (POINTER_SIZE
, MODE_INT
, 0));
1915 TYPE_PRECISION (type
) = POINTER_SIZE
;
1920 /* It's hard to see what the mode and size of a function ought to
1921 be, but we do know the alignment is FUNCTION_BOUNDARY, so
1922 make it consistent with that. */
1923 SET_TYPE_MODE (type
, mode_for_size (FUNCTION_BOUNDARY
, MODE_INT
, 0));
1924 TYPE_SIZE (type
) = bitsize_int (FUNCTION_BOUNDARY
);
1925 TYPE_SIZE_UNIT (type
) = size_int (FUNCTION_BOUNDARY
/ BITS_PER_UNIT
);
1929 case REFERENCE_TYPE
:
1931 enum machine_mode mode
= TYPE_MODE (type
);
1932 if (TREE_CODE (type
) == REFERENCE_TYPE
&& reference_types_internal
)
1934 addr_space_t as
= TYPE_ADDR_SPACE (TREE_TYPE (type
));
1935 mode
= targetm
.addr_space
.address_mode (as
);
1938 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
1939 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
1940 TYPE_UNSIGNED (type
) = 1;
1941 TYPE_PRECISION (type
) = GET_MODE_BITSIZE (mode
);
1947 tree index
= TYPE_DOMAIN (type
);
1948 tree element
= TREE_TYPE (type
);
1950 build_pointer_type (element
);
1952 /* We need to know both bounds in order to compute the size. */
1953 if (index
&& TYPE_MAX_VALUE (index
) && TYPE_MIN_VALUE (index
)
1954 && TYPE_SIZE (element
))
1956 tree ub
= TYPE_MAX_VALUE (index
);
1957 tree lb
= TYPE_MIN_VALUE (index
);
1958 tree element_size
= TYPE_SIZE (element
);
1961 /* Make sure that an array of zero-sized element is zero-sized
1962 regardless of its extent. */
1963 if (integer_zerop (element_size
))
1964 length
= size_zero_node
;
1966 /* The initial subtraction should happen in the original type so
1967 that (possible) negative values are handled appropriately. */
1970 = size_binop (PLUS_EXPR
, size_one_node
,
1971 fold_convert (sizetype
,
1972 fold_build2_loc (input_location
,
1977 TYPE_SIZE (type
) = size_binop (MULT_EXPR
, element_size
,
1978 fold_convert (bitsizetype
,
1981 /* If we know the size of the element, calculate the total size
1982 directly, rather than do some division thing below. This
1983 optimization helps Fortran assumed-size arrays (where the
1984 size of the array is determined at runtime) substantially. */
1985 if (TYPE_SIZE_UNIT (element
))
1986 TYPE_SIZE_UNIT (type
)
1987 = size_binop (MULT_EXPR
, TYPE_SIZE_UNIT (element
), length
);
1990 /* Now round the alignment and size,
1991 using machine-dependent criteria if any. */
1993 #ifdef ROUND_TYPE_ALIGN
1995 = ROUND_TYPE_ALIGN (type
, TYPE_ALIGN (element
), BITS_PER_UNIT
);
1997 TYPE_ALIGN (type
) = MAX (TYPE_ALIGN (element
), BITS_PER_UNIT
);
1999 if (!TYPE_SIZE (element
))
2000 /* We don't know the size of the underlying element type, so
2001 our alignment calculations will be wrong, forcing us to
2002 fall back on structural equality. */
2003 SET_TYPE_STRUCTURAL_EQUALITY (type
);
2004 TYPE_USER_ALIGN (type
) = TYPE_USER_ALIGN (element
);
2005 SET_TYPE_MODE (type
, BLKmode
);
2006 if (TYPE_SIZE (type
) != 0
2007 #ifdef MEMBER_TYPE_FORCES_BLK
2008 && ! MEMBER_TYPE_FORCES_BLK (type
, VOIDmode
)
2010 /* BLKmode elements force BLKmode aggregate;
2011 else extract/store fields may lose. */
2012 && (TYPE_MODE (TREE_TYPE (type
)) != BLKmode
2013 || TYPE_NO_FORCE_BLK (TREE_TYPE (type
))))
2015 /* One-element arrays get the component type's mode. */
2016 if (simple_cst_equal (TYPE_SIZE (type
),
2017 TYPE_SIZE (TREE_TYPE (type
))))
2018 SET_TYPE_MODE (type
, TYPE_MODE (TREE_TYPE (type
)));
2020 SET_TYPE_MODE (type
, mode_for_size_tree (TYPE_SIZE (type
),
2023 if (TYPE_MODE (type
) != BLKmode
2024 && STRICT_ALIGNMENT
&& TYPE_ALIGN (type
) < BIGGEST_ALIGNMENT
2025 && TYPE_ALIGN (type
) < GET_MODE_ALIGNMENT (TYPE_MODE (type
)))
2027 TYPE_NO_FORCE_BLK (type
) = 1;
2028 SET_TYPE_MODE (type
, BLKmode
);
2031 /* When the element size is constant, check that it is at least as
2032 large as the element alignment. */
2033 if (TYPE_SIZE_UNIT (element
)
2034 && TREE_CODE (TYPE_SIZE_UNIT (element
)) == INTEGER_CST
2035 /* If TYPE_SIZE_UNIT overflowed, then it is certainly larger than
2037 && !TREE_OVERFLOW (TYPE_SIZE_UNIT (element
))
2038 && !integer_zerop (TYPE_SIZE_UNIT (element
))
2039 && compare_tree_int (TYPE_SIZE_UNIT (element
),
2040 TYPE_ALIGN_UNIT (element
)) < 0)
2041 error ("alignment of array elements is greater than element size");
2047 case QUAL_UNION_TYPE
:
2050 record_layout_info rli
;
2052 /* Initialize the layout information. */
2053 rli
= start_record_layout (type
);
2055 /* If this is a QUAL_UNION_TYPE, we want to process the fields
2056 in the reverse order in building the COND_EXPR that denotes
2057 its size. We reverse them again later. */
2058 if (TREE_CODE (type
) == QUAL_UNION_TYPE
)
2059 TYPE_FIELDS (type
) = nreverse (TYPE_FIELDS (type
));
2061 /* Place all the fields. */
2062 for (field
= TYPE_FIELDS (type
); field
; field
= TREE_CHAIN (field
))
2063 place_field (rli
, field
);
2065 if (TREE_CODE (type
) == QUAL_UNION_TYPE
)
2066 TYPE_FIELDS (type
) = nreverse (TYPE_FIELDS (type
));
2068 /* Finish laying out the record. */
2069 finish_record_layout (rli
, /*free_p=*/true);
2077 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
2078 records and unions, finish_record_layout already called this
2080 if (TREE_CODE (type
) != RECORD_TYPE
2081 && TREE_CODE (type
) != UNION_TYPE
2082 && TREE_CODE (type
) != QUAL_UNION_TYPE
)
2083 finalize_type_size (type
);
2085 /* We should never see alias sets on incomplete aggregates. And we
2086 should not call layout_type on not incomplete aggregates. */
2087 if (AGGREGATE_TYPE_P (type
))
2088 gcc_assert (!TYPE_ALIAS_SET_KNOWN_P (type
));
2091 /* Vector types need to re-check the target flags each time we report
2092 the machine mode. We need to do this because attribute target can
2093 change the result of vector_mode_supported_p and have_regs_of_mode
2094 on a per-function basis. Thus the TYPE_MODE of a VECTOR_TYPE can
2095 change on a per-function basis. */
2096 /* ??? Possibly a better solution is to run through all the types
2097 referenced by a function and re-compute the TYPE_MODE once, rather
2098 than make the TYPE_MODE macro call a function. */
2101 vector_type_mode (const_tree t
)
2103 enum machine_mode mode
;
2105 gcc_assert (TREE_CODE (t
) == VECTOR_TYPE
);
2107 mode
= t
->type
.mode
;
2108 if (VECTOR_MODE_P (mode
)
2109 && (!targetm
.vector_mode_supported_p (mode
)
2110 || !have_regs_of_mode
[mode
]))
2112 enum machine_mode innermode
= TREE_TYPE (t
)->type
.mode
;
2114 /* For integers, try mapping it to a same-sized scalar mode. */
2115 if (GET_MODE_CLASS (innermode
) == MODE_INT
)
2117 mode
= mode_for_size (TYPE_VECTOR_SUBPARTS (t
)
2118 * GET_MODE_BITSIZE (innermode
), MODE_INT
, 0);
2120 if (mode
!= VOIDmode
&& have_regs_of_mode
[mode
])
2130 /* Create and return a type for signed integers of PRECISION bits. */
2133 make_signed_type (int precision
)
2135 tree type
= make_node (INTEGER_TYPE
);
2137 TYPE_PRECISION (type
) = precision
;
2139 fixup_signed_type (type
);
2143 /* Create and return a type for unsigned integers of PRECISION bits. */
2146 make_unsigned_type (int precision
)
2148 tree type
= make_node (INTEGER_TYPE
);
2150 TYPE_PRECISION (type
) = precision
;
2152 fixup_unsigned_type (type
);
2156 /* Create and return a type for fract of PRECISION bits, UNSIGNEDP,
2160 make_fract_type (int precision
, int unsignedp
, int satp
)
2162 tree type
= make_node (FIXED_POINT_TYPE
);
2164 TYPE_PRECISION (type
) = precision
;
2167 TYPE_SATURATING (type
) = 1;
2169 /* Lay out the type: set its alignment, size, etc. */
2172 TYPE_UNSIGNED (type
) = 1;
2173 SET_TYPE_MODE (type
, mode_for_size (precision
, MODE_UFRACT
, 0));
2176 SET_TYPE_MODE (type
, mode_for_size (precision
, MODE_FRACT
, 0));
2182 /* Create and return a type for accum of PRECISION bits, UNSIGNEDP,
2186 make_accum_type (int precision
, int unsignedp
, int satp
)
2188 tree type
= make_node (FIXED_POINT_TYPE
);
2190 TYPE_PRECISION (type
) = precision
;
2193 TYPE_SATURATING (type
) = 1;
2195 /* Lay out the type: set its alignment, size, etc. */
2198 TYPE_UNSIGNED (type
) = 1;
2199 SET_TYPE_MODE (type
, mode_for_size (precision
, MODE_UACCUM
, 0));
2202 SET_TYPE_MODE (type
, mode_for_size (precision
, MODE_ACCUM
, 0));
2208 /* Initialize sizetype and bitsizetype to a reasonable and temporary
2209 value to enable integer types to be created. */
2212 initialize_sizetypes (void)
2214 tree t
= make_node (INTEGER_TYPE
);
2215 int precision
= GET_MODE_BITSIZE (SImode
);
2217 SET_TYPE_MODE (t
, SImode
);
2218 TYPE_ALIGN (t
) = GET_MODE_ALIGNMENT (SImode
);
2219 TYPE_IS_SIZETYPE (t
) = 1;
2220 TYPE_UNSIGNED (t
) = 1;
2221 TYPE_SIZE (t
) = build_int_cst (t
, precision
);
2222 TYPE_SIZE_UNIT (t
) = build_int_cst (t
, GET_MODE_SIZE (SImode
));
2223 TYPE_PRECISION (t
) = precision
;
2225 set_min_and_max_values_for_integral_type (t
, precision
, true);
2228 bitsizetype
= build_distinct_type_copy (t
);
2231 /* Make sizetype a version of TYPE, and initialize *sizetype accordingly.
2232 We do this by overwriting the stub sizetype and bitsizetype nodes created
2233 by initialize_sizetypes. This makes sure that (a) anything stubby about
2234 them no longer exists and (b) any INTEGER_CSTs created with such a type,
2238 set_sizetype (tree type
)
2241 int oprecision
= TYPE_PRECISION (type
);
2242 /* The *bitsizetype types use a precision that avoids overflows when
2243 calculating signed sizes / offsets in bits. However, when
2244 cross-compiling from a 32 bit to a 64 bit host, we are limited to 64 bit
2247 = MIN (oprecision
+ BITS_PER_UNIT_LOG
+ 1, MAX_FIXED_MODE_SIZE
);
2249 = GET_MODE_PRECISION (smallest_mode_for_size (precision
, MODE_INT
));
2250 if (precision
> HOST_BITS_PER_WIDE_INT
* 2)
2251 precision
= HOST_BITS_PER_WIDE_INT
* 2;
2253 /* sizetype must be an unsigned type. */
2254 gcc_assert (TYPE_UNSIGNED (type
));
2256 t
= build_distinct_type_copy (type
);
2257 /* We want to use sizetype's cache, as we will be replacing that type. */
2258 TYPE_CACHED_VALUES (t
) = TYPE_CACHED_VALUES (sizetype
);
2259 TYPE_CACHED_VALUES_P (t
) = TYPE_CACHED_VALUES_P (sizetype
);
2260 TREE_TYPE (TYPE_CACHED_VALUES (t
)) = type
;
2261 TYPE_UID (t
) = TYPE_UID (sizetype
);
2262 TYPE_IS_SIZETYPE (t
) = 1;
2264 /* Replace our original stub sizetype. */
2265 memcpy (sizetype
, t
, tree_size (sizetype
));
2266 TYPE_MAIN_VARIANT (sizetype
) = sizetype
;
2267 TYPE_CANONICAL (sizetype
) = sizetype
;
2269 /* sizetype is unsigned but we need to fix TYPE_MAX_VALUE so that it is
2270 sign-extended in a way consistent with force_fit_type. */
2271 max
= TYPE_MAX_VALUE (sizetype
);
2272 TYPE_MAX_VALUE (sizetype
)
2273 = double_int_to_tree (sizetype
, tree_to_double_int (max
));
2275 t
= make_node (INTEGER_TYPE
);
2276 TYPE_NAME (t
) = get_identifier ("bit_size_type");
2277 /* We want to use bitsizetype's cache, as we will be replacing that type. */
2278 TYPE_CACHED_VALUES (t
) = TYPE_CACHED_VALUES (bitsizetype
);
2279 TYPE_CACHED_VALUES_P (t
) = TYPE_CACHED_VALUES_P (bitsizetype
);
2280 TYPE_PRECISION (t
) = precision
;
2281 TYPE_UID (t
) = TYPE_UID (bitsizetype
);
2282 TYPE_IS_SIZETYPE (t
) = 1;
2284 /* Replace our original stub bitsizetype. */
2285 memcpy (bitsizetype
, t
, tree_size (bitsizetype
));
2286 TYPE_MAIN_VARIANT (bitsizetype
) = bitsizetype
;
2287 TYPE_CANONICAL (bitsizetype
) = bitsizetype
;
2289 fixup_unsigned_type (bitsizetype
);
2291 /* Create the signed variants of *sizetype. */
2292 ssizetype
= make_signed_type (oprecision
);
2293 TYPE_IS_SIZETYPE (ssizetype
) = 1;
2294 sbitsizetype
= make_signed_type (precision
);
2295 TYPE_IS_SIZETYPE (sbitsizetype
) = 1;
2298 /* TYPE is an integral type, i.e., an INTEGRAL_TYPE, ENUMERAL_TYPE
2299 or BOOLEAN_TYPE. Set TYPE_MIN_VALUE and TYPE_MAX_VALUE
2300 for TYPE, based on the PRECISION and whether or not the TYPE
2301 IS_UNSIGNED. PRECISION need not correspond to a width supported
2302 natively by the hardware; for example, on a machine with 8-bit,
2303 16-bit, and 32-bit register modes, PRECISION might be 7, 23, or
2307 set_min_and_max_values_for_integral_type (tree type
,
2316 min_value
= build_int_cst (type
, 0);
2318 = build_int_cst_wide (type
, precision
- HOST_BITS_PER_WIDE_INT
>= 0
2320 : ((HOST_WIDE_INT
) 1 << precision
) - 1,
2321 precision
- HOST_BITS_PER_WIDE_INT
> 0
2322 ? ((unsigned HOST_WIDE_INT
) ~0
2323 >> (HOST_BITS_PER_WIDE_INT
2324 - (precision
- HOST_BITS_PER_WIDE_INT
)))
2330 = build_int_cst_wide (type
,
2331 (precision
- HOST_BITS_PER_WIDE_INT
> 0
2333 : (HOST_WIDE_INT
) (-1) << (precision
- 1)),
2334 (((HOST_WIDE_INT
) (-1)
2335 << (precision
- HOST_BITS_PER_WIDE_INT
- 1 > 0
2336 ? precision
- HOST_BITS_PER_WIDE_INT
- 1
2339 = build_int_cst_wide (type
,
2340 (precision
- HOST_BITS_PER_WIDE_INT
> 0
2342 : ((HOST_WIDE_INT
) 1 << (precision
- 1)) - 1),
2343 (precision
- HOST_BITS_PER_WIDE_INT
- 1 > 0
2344 ? (((HOST_WIDE_INT
) 1
2345 << (precision
- HOST_BITS_PER_WIDE_INT
- 1))) - 1
2349 TYPE_MIN_VALUE (type
) = min_value
;
2350 TYPE_MAX_VALUE (type
) = max_value
;
2353 /* Set the extreme values of TYPE based on its precision in bits,
2354 then lay it out. Used when make_signed_type won't do
2355 because the tree code is not INTEGER_TYPE.
2356 E.g. for Pascal, when the -fsigned-char option is given. */
2359 fixup_signed_type (tree type
)
2361 int precision
= TYPE_PRECISION (type
);
2363 /* We can not represent properly constants greater then
2364 2 * HOST_BITS_PER_WIDE_INT, still we need the types
2365 as they are used by i386 vector extensions and friends. */
2366 if (precision
> HOST_BITS_PER_WIDE_INT
* 2)
2367 precision
= HOST_BITS_PER_WIDE_INT
* 2;
2369 set_min_and_max_values_for_integral_type (type
, precision
,
2370 /*is_unsigned=*/false);
2372 /* Lay out the type: set its alignment, size, etc. */
2376 /* Set the extreme values of TYPE based on its precision in bits,
2377 then lay it out. This is used both in `make_unsigned_type'
2378 and for enumeral types. */
2381 fixup_unsigned_type (tree type
)
2383 int precision
= TYPE_PRECISION (type
);
2385 /* We can not represent properly constants greater then
2386 2 * HOST_BITS_PER_WIDE_INT, still we need the types
2387 as they are used by i386 vector extensions and friends. */
2388 if (precision
> HOST_BITS_PER_WIDE_INT
* 2)
2389 precision
= HOST_BITS_PER_WIDE_INT
* 2;
2391 TYPE_UNSIGNED (type
) = 1;
2393 set_min_and_max_values_for_integral_type (type
, precision
,
2394 /*is_unsigned=*/true);
2396 /* Lay out the type: set its alignment, size, etc. */
2400 /* Find the best machine mode to use when referencing a bit field of length
2401 BITSIZE bits starting at BITPOS.
2403 The underlying object is known to be aligned to a boundary of ALIGN bits.
2404 If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
2405 larger than LARGEST_MODE (usually SImode).
2407 If no mode meets all these conditions, we return VOIDmode.
2409 If VOLATILEP is false and SLOW_BYTE_ACCESS is false, we return the
2410 smallest mode meeting these conditions.
2412 If VOLATILEP is false and SLOW_BYTE_ACCESS is true, we return the
2413 largest mode (but a mode no wider than UNITS_PER_WORD) that meets
2416 If VOLATILEP is true the narrow_volatile_bitfields target hook is used to
2417 decide which of the above modes should be used. */
2420 get_best_mode (int bitsize
, int bitpos
, unsigned int align
,
2421 enum machine_mode largest_mode
, int volatilep
)
2423 enum machine_mode mode
;
2424 unsigned int unit
= 0;
2426 /* Find the narrowest integer mode that contains the bit field. */
2427 for (mode
= GET_CLASS_NARROWEST_MODE (MODE_INT
); mode
!= VOIDmode
;
2428 mode
= GET_MODE_WIDER_MODE (mode
))
2430 unit
= GET_MODE_BITSIZE (mode
);
2431 if ((bitpos
% unit
) + bitsize
<= unit
)
2435 if (mode
== VOIDmode
2436 /* It is tempting to omit the following line
2437 if STRICT_ALIGNMENT is true.
2438 But that is incorrect, since if the bitfield uses part of 3 bytes
2439 and we use a 4-byte mode, we could get a spurious segv
2440 if the extra 4th byte is past the end of memory.
2441 (Though at least one Unix compiler ignores this problem:
2442 that on the Sequent 386 machine. */
2443 || MIN (unit
, BIGGEST_ALIGNMENT
) > align
2444 || (largest_mode
!= VOIDmode
&& unit
> GET_MODE_BITSIZE (largest_mode
)))
2447 if ((SLOW_BYTE_ACCESS
&& ! volatilep
)
2448 || (volatilep
&& !targetm
.narrow_volatile_bitfield ()))
2450 enum machine_mode wide_mode
= VOIDmode
, tmode
;
2452 for (tmode
= GET_CLASS_NARROWEST_MODE (MODE_INT
); tmode
!= VOIDmode
;
2453 tmode
= GET_MODE_WIDER_MODE (tmode
))
2455 unit
= GET_MODE_BITSIZE (tmode
);
2456 if (bitpos
/ unit
== (bitpos
+ bitsize
- 1) / unit
2457 && unit
<= BITS_PER_WORD
2458 && unit
<= MIN (align
, BIGGEST_ALIGNMENT
)
2459 && (largest_mode
== VOIDmode
2460 || unit
<= GET_MODE_BITSIZE (largest_mode
)))
2464 if (wide_mode
!= VOIDmode
)
2471 /* Gets minimal and maximal values for MODE (signed or unsigned depending on
2472 SIGN). The returned constants are made to be usable in TARGET_MODE. */
2475 get_mode_bounds (enum machine_mode mode
, int sign
,
2476 enum machine_mode target_mode
,
2477 rtx
*mmin
, rtx
*mmax
)
2479 unsigned size
= GET_MODE_BITSIZE (mode
);
2480 unsigned HOST_WIDE_INT min_val
, max_val
;
2482 gcc_assert (size
<= HOST_BITS_PER_WIDE_INT
);
2486 min_val
= -((unsigned HOST_WIDE_INT
) 1 << (size
- 1));
2487 max_val
= ((unsigned HOST_WIDE_INT
) 1 << (size
- 1)) - 1;
2492 max_val
= ((unsigned HOST_WIDE_INT
) 1 << (size
- 1) << 1) - 1;
2495 *mmin
= gen_int_mode (min_val
, target_mode
);
2496 *mmax
= gen_int_mode (max_val
, target_mode
);
2499 #include "gt-stor-layout.h"