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
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(()) tree 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 list of all the objects put on the pending sizes list. */
86 get_pending_sizes (void)
88 tree 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 pending_sizes
= tree_cons (NULL_TREE
, expr
, pending_sizes
);
107 /* Put a chain of objects into the pending sizes list, which must be
111 put_pending_sizes (tree 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 (input_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 #ifndef MAX_FIXED_MODE_SIZE
373 #define MAX_FIXED_MODE_SIZE GET_MODE_BITSIZE (DImode)
376 /* Return the machine mode to use for a nonscalar of SIZE bits. The
377 mode must be in class MCLASS, and have exactly that many value bits;
378 it may have padding as well. If LIMIT is nonzero, modes of wider
379 than MAX_FIXED_MODE_SIZE will not be used. */
382 mode_for_size (unsigned int size
, enum mode_class mclass
, int limit
)
384 enum machine_mode mode
;
386 if (limit
&& size
> MAX_FIXED_MODE_SIZE
)
389 /* Get the first mode which has this size, in the specified class. */
390 for (mode
= GET_CLASS_NARROWEST_MODE (mclass
); mode
!= VOIDmode
;
391 mode
= GET_MODE_WIDER_MODE (mode
))
392 if (GET_MODE_PRECISION (mode
) == size
)
398 /* Similar, except passed a tree node. */
401 mode_for_size_tree (const_tree size
, enum mode_class mclass
, int limit
)
403 unsigned HOST_WIDE_INT uhwi
;
406 if (!host_integerp (size
, 1))
408 uhwi
= tree_low_cst (size
, 1);
412 return mode_for_size (ui
, mclass
, limit
);
415 /* Similar, but never return BLKmode; return the narrowest mode that
416 contains at least the requested number of value bits. */
419 smallest_mode_for_size (unsigned int size
, enum mode_class mclass
)
421 enum machine_mode mode
;
423 /* Get the first mode which has at least this size, in the
425 for (mode
= GET_CLASS_NARROWEST_MODE (mclass
); mode
!= VOIDmode
;
426 mode
= GET_MODE_WIDER_MODE (mode
))
427 if (GET_MODE_PRECISION (mode
) >= size
)
433 /* Find an integer mode of the exact same size, or BLKmode on failure. */
436 int_mode_for_mode (enum machine_mode mode
)
438 switch (GET_MODE_CLASS (mode
))
441 case MODE_PARTIAL_INT
:
444 case MODE_COMPLEX_INT
:
445 case MODE_COMPLEX_FLOAT
:
447 case MODE_DECIMAL_FLOAT
:
448 case MODE_VECTOR_INT
:
449 case MODE_VECTOR_FLOAT
:
454 case MODE_VECTOR_FRACT
:
455 case MODE_VECTOR_ACCUM
:
456 case MODE_VECTOR_UFRACT
:
457 case MODE_VECTOR_UACCUM
:
458 mode
= mode_for_size (GET_MODE_BITSIZE (mode
), MODE_INT
, 0);
465 /* ... fall through ... */
475 /* Return the alignment of MODE. This will be bounded by 1 and
476 BIGGEST_ALIGNMENT. */
479 get_mode_alignment (enum machine_mode mode
)
481 return MIN (BIGGEST_ALIGNMENT
, MAX (1, mode_base_align
[mode
]*BITS_PER_UNIT
));
485 /* Subroutine of layout_decl: Force alignment required for the data type.
486 But if the decl itself wants greater alignment, don't override that. */
489 do_type_align (tree type
, tree decl
)
491 if (TYPE_ALIGN (type
) > DECL_ALIGN (decl
))
493 DECL_ALIGN (decl
) = TYPE_ALIGN (type
);
494 if (TREE_CODE (decl
) == FIELD_DECL
)
495 DECL_USER_ALIGN (decl
) = TYPE_USER_ALIGN (type
);
499 /* Set the size, mode and alignment of a ..._DECL node.
500 TYPE_DECL does need this for C++.
501 Note that LABEL_DECL and CONST_DECL nodes do not need this,
502 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
503 Don't call layout_decl for them.
505 KNOWN_ALIGN is the amount of alignment we can assume this
506 decl has with no special effort. It is relevant only for FIELD_DECLs
507 and depends on the previous fields.
508 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
509 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
510 the record will be aligned to suit. */
513 layout_decl (tree decl
, unsigned int known_align
)
515 tree type
= TREE_TYPE (decl
);
516 enum tree_code code
= TREE_CODE (decl
);
518 location_t loc
= DECL_SOURCE_LOCATION (decl
);
520 if (code
== CONST_DECL
)
523 gcc_assert (code
== VAR_DECL
|| code
== PARM_DECL
|| code
== RESULT_DECL
524 || code
== TYPE_DECL
||code
== FIELD_DECL
);
526 rtl
= DECL_RTL_IF_SET (decl
);
528 if (type
== error_mark_node
)
529 type
= void_type_node
;
531 /* Usually the size and mode come from the data type without change,
532 however, the front-end may set the explicit width of the field, so its
533 size may not be the same as the size of its type. This happens with
534 bitfields, of course (an `int' bitfield may be only 2 bits, say), but it
535 also happens with other fields. For example, the C++ front-end creates
536 zero-sized fields corresponding to empty base classes, and depends on
537 layout_type setting DECL_FIELD_BITPOS correctly for the field. Set the
538 size in bytes from the size in bits. If we have already set the mode,
539 don't set it again since we can be called twice for FIELD_DECLs. */
541 DECL_UNSIGNED (decl
) = TYPE_UNSIGNED (type
);
542 if (DECL_MODE (decl
) == VOIDmode
)
543 DECL_MODE (decl
) = TYPE_MODE (type
);
545 if (DECL_SIZE (decl
) == 0)
547 DECL_SIZE (decl
) = TYPE_SIZE (type
);
548 DECL_SIZE_UNIT (decl
) = TYPE_SIZE_UNIT (type
);
550 else if (DECL_SIZE_UNIT (decl
) == 0)
551 DECL_SIZE_UNIT (decl
)
552 = fold_convert_loc (loc
, sizetype
,
553 size_binop_loc (loc
, CEIL_DIV_EXPR
, DECL_SIZE (decl
),
556 if (code
!= FIELD_DECL
)
557 /* For non-fields, update the alignment from the type. */
558 do_type_align (type
, decl
);
560 /* For fields, it's a bit more complicated... */
562 bool old_user_align
= DECL_USER_ALIGN (decl
);
563 bool zero_bitfield
= false;
564 bool packed_p
= DECL_PACKED (decl
);
567 if (DECL_BIT_FIELD (decl
))
569 DECL_BIT_FIELD_TYPE (decl
) = type
;
571 /* A zero-length bit-field affects the alignment of the next
572 field. In essence such bit-fields are not influenced by
573 any packing due to #pragma pack or attribute packed. */
574 if (integer_zerop (DECL_SIZE (decl
))
575 && ! targetm
.ms_bitfield_layout_p (DECL_FIELD_CONTEXT (decl
)))
577 zero_bitfield
= true;
579 #ifdef PCC_BITFIELD_TYPE_MATTERS
580 if (PCC_BITFIELD_TYPE_MATTERS
)
581 do_type_align (type
, decl
);
585 #ifdef EMPTY_FIELD_BOUNDARY
586 if (EMPTY_FIELD_BOUNDARY
> DECL_ALIGN (decl
))
588 DECL_ALIGN (decl
) = EMPTY_FIELD_BOUNDARY
;
589 DECL_USER_ALIGN (decl
) = 0;
595 /* See if we can use an ordinary integer mode for a bit-field.
596 Conditions are: a fixed size that is correct for another mode
597 and occupying a complete byte or bytes on proper boundary. */
598 if (TYPE_SIZE (type
) != 0
599 && TREE_CODE (TYPE_SIZE (type
)) == INTEGER_CST
600 && GET_MODE_CLASS (TYPE_MODE (type
)) == MODE_INT
)
602 enum machine_mode xmode
603 = mode_for_size_tree (DECL_SIZE (decl
), MODE_INT
, 1);
604 unsigned int xalign
= GET_MODE_ALIGNMENT (xmode
);
607 && !(xalign
> BITS_PER_UNIT
&& DECL_PACKED (decl
))
608 && (known_align
== 0 || known_align
>= xalign
))
610 DECL_ALIGN (decl
) = MAX (xalign
, DECL_ALIGN (decl
));
611 DECL_MODE (decl
) = xmode
;
612 DECL_BIT_FIELD (decl
) = 0;
616 /* Turn off DECL_BIT_FIELD if we won't need it set. */
617 if (TYPE_MODE (type
) == BLKmode
&& DECL_MODE (decl
) == BLKmode
618 && known_align
>= TYPE_ALIGN (type
)
619 && DECL_ALIGN (decl
) >= TYPE_ALIGN (type
))
620 DECL_BIT_FIELD (decl
) = 0;
622 else if (packed_p
&& DECL_USER_ALIGN (decl
))
623 /* Don't touch DECL_ALIGN. For other packed fields, go ahead and
624 round up; we'll reduce it again below. We want packing to
625 supersede USER_ALIGN inherited from the type, but defer to
626 alignment explicitly specified on the field decl. */;
628 do_type_align (type
, decl
);
630 /* If the field is packed and not explicitly aligned, give it the
631 minimum alignment. Note that do_type_align may set
632 DECL_USER_ALIGN, so we need to check old_user_align instead. */
635 DECL_ALIGN (decl
) = MIN (DECL_ALIGN (decl
), BITS_PER_UNIT
);
637 if (! packed_p
&& ! DECL_USER_ALIGN (decl
))
639 /* Some targets (i.e. i386, VMS) limit struct field alignment
640 to a lower boundary than alignment of variables unless
641 it was overridden by attribute aligned. */
642 #ifdef BIGGEST_FIELD_ALIGNMENT
644 = MIN (DECL_ALIGN (decl
), (unsigned) BIGGEST_FIELD_ALIGNMENT
);
646 #ifdef ADJUST_FIELD_ALIGN
647 DECL_ALIGN (decl
) = ADJUST_FIELD_ALIGN (decl
, DECL_ALIGN (decl
));
652 mfa
= initial_max_fld_align
* BITS_PER_UNIT
;
654 mfa
= maximum_field_alignment
;
655 /* Should this be controlled by DECL_USER_ALIGN, too? */
657 DECL_ALIGN (decl
) = MIN (DECL_ALIGN (decl
), mfa
);
660 /* Evaluate nonconstant size only once, either now or as soon as safe. */
661 if (DECL_SIZE (decl
) != 0 && TREE_CODE (DECL_SIZE (decl
)) != INTEGER_CST
)
662 DECL_SIZE (decl
) = variable_size (DECL_SIZE (decl
));
663 if (DECL_SIZE_UNIT (decl
) != 0
664 && TREE_CODE (DECL_SIZE_UNIT (decl
)) != INTEGER_CST
)
665 DECL_SIZE_UNIT (decl
) = variable_size (DECL_SIZE_UNIT (decl
));
667 /* If requested, warn about definitions of large data objects. */
669 && (code
== VAR_DECL
|| code
== PARM_DECL
)
670 && ! DECL_EXTERNAL (decl
))
672 tree size
= DECL_SIZE_UNIT (decl
);
674 if (size
!= 0 && TREE_CODE (size
) == INTEGER_CST
675 && compare_tree_int (size
, larger_than_size
) > 0)
677 int size_as_int
= TREE_INT_CST_LOW (size
);
679 if (compare_tree_int (size
, size_as_int
) == 0)
680 warning (OPT_Wlarger_than_eq
, "size of %q+D is %d bytes", decl
, size_as_int
);
682 warning (OPT_Wlarger_than_eq
, "size of %q+D is larger than %wd bytes",
683 decl
, larger_than_size
);
687 /* If the RTL was already set, update its mode and mem attributes. */
690 PUT_MODE (rtl
, DECL_MODE (decl
));
691 SET_DECL_RTL (decl
, 0);
692 set_mem_attributes (rtl
, decl
, 1);
693 SET_DECL_RTL (decl
, rtl
);
697 /* Given a VAR_DECL, PARM_DECL or RESULT_DECL, clears the results of
698 a previous call to layout_decl and calls it again. */
701 relayout_decl (tree decl
)
703 DECL_SIZE (decl
) = DECL_SIZE_UNIT (decl
) = 0;
704 DECL_MODE (decl
) = VOIDmode
;
705 if (!DECL_USER_ALIGN (decl
))
706 DECL_ALIGN (decl
) = 0;
707 SET_DECL_RTL (decl
, 0);
709 layout_decl (decl
, 0);
712 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
713 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
714 is to be passed to all other layout functions for this record. It is the
715 responsibility of the caller to call `free' for the storage returned.
716 Note that garbage collection is not permitted until we finish laying
720 start_record_layout (tree t
)
722 record_layout_info rli
= XNEW (struct record_layout_info_s
);
726 /* If the type has a minimum specified alignment (via an attribute
727 declaration, for example) use it -- otherwise, start with a
728 one-byte alignment. */
729 rli
->record_align
= MAX (BITS_PER_UNIT
, TYPE_ALIGN (t
));
730 rli
->unpacked_align
= rli
->record_align
;
731 rli
->offset_align
= MAX (rli
->record_align
, BIGGEST_ALIGNMENT
);
733 #ifdef STRUCTURE_SIZE_BOUNDARY
734 /* Packed structures don't need to have minimum size. */
735 if (! TYPE_PACKED (t
))
739 /* #pragma pack overrides STRUCTURE_SIZE_BOUNDARY. */
740 tmp
= (unsigned) STRUCTURE_SIZE_BOUNDARY
;
741 if (maximum_field_alignment
!= 0)
742 tmp
= MIN (tmp
, maximum_field_alignment
);
743 rli
->record_align
= MAX (rli
->record_align
, tmp
);
747 rli
->offset
= size_zero_node
;
748 rli
->bitpos
= bitsize_zero_node
;
750 rli
->pending_statics
= 0;
751 rli
->packed_maybe_necessary
= 0;
752 rli
->remaining_in_alignment
= 0;
757 /* These four routines perform computations that convert between
758 the offset/bitpos forms and byte and bit offsets. */
761 bit_from_pos (tree offset
, tree bitpos
)
763 return size_binop (PLUS_EXPR
, bitpos
,
764 size_binop (MULT_EXPR
,
765 fold_convert (bitsizetype
, offset
),
770 byte_from_pos (tree offset
, tree bitpos
)
772 return size_binop (PLUS_EXPR
, offset
,
773 fold_convert (sizetype
,
774 size_binop (TRUNC_DIV_EXPR
, bitpos
,
775 bitsize_unit_node
)));
779 pos_from_bit (tree
*poffset
, tree
*pbitpos
, unsigned int off_align
,
782 *poffset
= size_binop (MULT_EXPR
,
783 fold_convert (sizetype
,
784 size_binop (FLOOR_DIV_EXPR
, pos
,
785 bitsize_int (off_align
))),
786 size_int (off_align
/ BITS_PER_UNIT
));
787 *pbitpos
= size_binop (FLOOR_MOD_EXPR
, pos
, bitsize_int (off_align
));
790 /* Given a pointer to bit and byte offsets and an offset alignment,
791 normalize the offsets so they are within the alignment. */
794 normalize_offset (tree
*poffset
, tree
*pbitpos
, unsigned int off_align
)
796 /* If the bit position is now larger than it should be, adjust it
798 if (compare_tree_int (*pbitpos
, off_align
) >= 0)
800 tree extra_aligns
= size_binop (FLOOR_DIV_EXPR
, *pbitpos
,
801 bitsize_int (off_align
));
804 = size_binop (PLUS_EXPR
, *poffset
,
805 size_binop (MULT_EXPR
,
806 fold_convert (sizetype
, extra_aligns
),
807 size_int (off_align
/ BITS_PER_UNIT
)));
810 = size_binop (FLOOR_MOD_EXPR
, *pbitpos
, bitsize_int (off_align
));
814 /* Print debugging information about the information in RLI. */
817 debug_rli (record_layout_info rli
)
819 print_node_brief (stderr
, "type", rli
->t
, 0);
820 print_node_brief (stderr
, "\noffset", rli
->offset
, 0);
821 print_node_brief (stderr
, " bitpos", rli
->bitpos
, 0);
823 fprintf (stderr
, "\naligns: rec = %u, unpack = %u, off = %u\n",
824 rli
->record_align
, rli
->unpacked_align
,
827 /* The ms_struct code is the only that uses this. */
828 if (targetm
.ms_bitfield_layout_p (rli
->t
))
829 fprintf (stderr
, "remaining in alignment = %u\n", rli
->remaining_in_alignment
);
831 if (rli
->packed_maybe_necessary
)
832 fprintf (stderr
, "packed may be necessary\n");
834 if (rli
->pending_statics
)
836 fprintf (stderr
, "pending statics:\n");
837 debug_tree (rli
->pending_statics
);
841 /* Given an RLI with a possibly-incremented BITPOS, adjust OFFSET and
842 BITPOS if necessary to keep BITPOS below OFFSET_ALIGN. */
845 normalize_rli (record_layout_info rli
)
847 normalize_offset (&rli
->offset
, &rli
->bitpos
, rli
->offset_align
);
850 /* Returns the size in bytes allocated so far. */
853 rli_size_unit_so_far (record_layout_info rli
)
855 return byte_from_pos (rli
->offset
, rli
->bitpos
);
858 /* Returns the size in bits allocated so far. */
861 rli_size_so_far (record_layout_info rli
)
863 return bit_from_pos (rli
->offset
, rli
->bitpos
);
866 /* FIELD is about to be added to RLI->T. The alignment (in bits) of
867 the next available location within the record is given by KNOWN_ALIGN.
868 Update the variable alignment fields in RLI, and return the alignment
869 to give the FIELD. */
872 update_alignment_for_field (record_layout_info rli
, tree field
,
873 unsigned int known_align
)
875 /* The alignment required for FIELD. */
876 unsigned int desired_align
;
877 /* The type of this field. */
878 tree type
= TREE_TYPE (field
);
879 /* True if the field was explicitly aligned by the user. */
883 /* Do not attempt to align an ERROR_MARK node */
884 if (TREE_CODE (type
) == ERROR_MARK
)
887 /* Lay out the field so we know what alignment it needs. */
888 layout_decl (field
, known_align
);
889 desired_align
= DECL_ALIGN (field
);
890 user_align
= DECL_USER_ALIGN (field
);
892 is_bitfield
= (type
!= error_mark_node
893 && DECL_BIT_FIELD_TYPE (field
)
894 && ! integer_zerop (TYPE_SIZE (type
)));
896 /* Record must have at least as much alignment as any field.
897 Otherwise, the alignment of the field within the record is
899 if (targetm
.ms_bitfield_layout_p (rli
->t
))
901 /* Here, the alignment of the underlying type of a bitfield can
902 affect the alignment of a record; even a zero-sized field
903 can do this. The alignment should be to the alignment of
904 the type, except that for zero-size bitfields this only
905 applies if there was an immediately prior, nonzero-size
906 bitfield. (That's the way it is, experimentally.) */
907 if ((!is_bitfield
&& !DECL_PACKED (field
))
908 || (!integer_zerop (DECL_SIZE (field
))
909 ? !DECL_PACKED (field
)
911 && DECL_BIT_FIELD_TYPE (rli
->prev_field
)
912 && ! integer_zerop (DECL_SIZE (rli
->prev_field
)))))
914 unsigned int type_align
= TYPE_ALIGN (type
);
915 type_align
= MAX (type_align
, desired_align
);
916 if (maximum_field_alignment
!= 0)
917 type_align
= MIN (type_align
, maximum_field_alignment
);
918 rli
->record_align
= MAX (rli
->record_align
, type_align
);
919 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
922 #ifdef PCC_BITFIELD_TYPE_MATTERS
923 else if (is_bitfield
&& PCC_BITFIELD_TYPE_MATTERS
)
925 /* Named bit-fields cause the entire structure to have the
926 alignment implied by their type. Some targets also apply the same
927 rules to unnamed bitfields. */
928 if (DECL_NAME (field
) != 0
929 || targetm
.align_anon_bitfield ())
931 unsigned int type_align
= TYPE_ALIGN (type
);
933 #ifdef ADJUST_FIELD_ALIGN
934 if (! TYPE_USER_ALIGN (type
))
935 type_align
= ADJUST_FIELD_ALIGN (field
, type_align
);
938 /* Targets might chose to handle unnamed and hence possibly
939 zero-width bitfield. Those are not influenced by #pragmas
940 or packed attributes. */
941 if (integer_zerop (DECL_SIZE (field
)))
943 if (initial_max_fld_align
)
944 type_align
= MIN (type_align
,
945 initial_max_fld_align
* BITS_PER_UNIT
);
947 else if (maximum_field_alignment
!= 0)
948 type_align
= MIN (type_align
, maximum_field_alignment
);
949 else if (DECL_PACKED (field
))
950 type_align
= MIN (type_align
, BITS_PER_UNIT
);
952 /* The alignment of the record is increased to the maximum
953 of the current alignment, the alignment indicated on the
954 field (i.e., the alignment specified by an __aligned__
955 attribute), and the alignment indicated by the type of
957 rli
->record_align
= MAX (rli
->record_align
, desired_align
);
958 rli
->record_align
= MAX (rli
->record_align
, type_align
);
961 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
962 user_align
|= TYPE_USER_ALIGN (type
);
968 rli
->record_align
= MAX (rli
->record_align
, desired_align
);
969 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
972 TYPE_USER_ALIGN (rli
->t
) |= user_align
;
974 return desired_align
;
977 /* Called from place_field to handle unions. */
980 place_union_field (record_layout_info rli
, tree field
)
982 update_alignment_for_field (rli
, field
, /*known_align=*/0);
984 DECL_FIELD_OFFSET (field
) = size_zero_node
;
985 DECL_FIELD_BIT_OFFSET (field
) = bitsize_zero_node
;
986 SET_DECL_OFFSET_ALIGN (field
, BIGGEST_ALIGNMENT
);
988 /* If this is an ERROR_MARK return *after* having set the
989 field at the start of the union. This helps when parsing
991 if (TREE_CODE (TREE_TYPE (field
)) == ERROR_MARK
)
994 /* We assume the union's size will be a multiple of a byte so we don't
995 bother with BITPOS. */
996 if (TREE_CODE (rli
->t
) == UNION_TYPE
)
997 rli
->offset
= size_binop (MAX_EXPR
, rli
->offset
, DECL_SIZE_UNIT (field
));
998 else if (TREE_CODE (rli
->t
) == QUAL_UNION_TYPE
)
999 rli
->offset
= fold_build3_loc (input_location
, COND_EXPR
, sizetype
,
1000 DECL_QUALIFIER (field
),
1001 DECL_SIZE_UNIT (field
), rli
->offset
);
1004 #if defined (PCC_BITFIELD_TYPE_MATTERS) || defined (BITFIELD_NBYTES_LIMITED)
1005 /* A bitfield of SIZE with a required access alignment of ALIGN is allocated
1006 at BYTE_OFFSET / BIT_OFFSET. Return nonzero if the field would span more
1007 units of alignment than the underlying TYPE. */
1009 excess_unit_span (HOST_WIDE_INT byte_offset
, HOST_WIDE_INT bit_offset
,
1010 HOST_WIDE_INT size
, HOST_WIDE_INT align
, tree type
)
1012 /* Note that the calculation of OFFSET might overflow; we calculate it so
1013 that we still get the right result as long as ALIGN is a power of two. */
1014 unsigned HOST_WIDE_INT offset
= byte_offset
* BITS_PER_UNIT
+ bit_offset
;
1016 offset
= offset
% align
;
1017 return ((offset
+ size
+ align
- 1) / align
1018 > ((unsigned HOST_WIDE_INT
) tree_low_cst (TYPE_SIZE (type
), 1)
1023 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
1024 is a FIELD_DECL to be added after those fields already present in
1025 T. (FIELD is not actually added to the TYPE_FIELDS list here;
1026 callers that desire that behavior must manually perform that step.) */
1029 place_field (record_layout_info rli
, tree field
)
1031 /* The alignment required for FIELD. */
1032 unsigned int desired_align
;
1033 /* The alignment FIELD would have if we just dropped it into the
1034 record as it presently stands. */
1035 unsigned int known_align
;
1036 unsigned int actual_align
;
1037 /* The type of this field. */
1038 tree type
= TREE_TYPE (field
);
1040 gcc_assert (TREE_CODE (field
) != ERROR_MARK
);
1042 /* If FIELD is static, then treat it like a separate variable, not
1043 really like a structure field. If it is a FUNCTION_DECL, it's a
1044 method. In both cases, all we do is lay out the decl, and we do
1045 it *after* the record is laid out. */
1046 if (TREE_CODE (field
) == VAR_DECL
)
1048 rli
->pending_statics
= tree_cons (NULL_TREE
, field
,
1049 rli
->pending_statics
);
1053 /* Enumerators and enum types which are local to this class need not
1054 be laid out. Likewise for initialized constant fields. */
1055 else if (TREE_CODE (field
) != FIELD_DECL
)
1058 /* Unions are laid out very differently than records, so split
1059 that code off to another function. */
1060 else if (TREE_CODE (rli
->t
) != RECORD_TYPE
)
1062 place_union_field (rli
, field
);
1066 else if (TREE_CODE (type
) == ERROR_MARK
)
1068 /* Place this field at the current allocation position, so we
1069 maintain monotonicity. */
1070 DECL_FIELD_OFFSET (field
) = rli
->offset
;
1071 DECL_FIELD_BIT_OFFSET (field
) = rli
->bitpos
;
1072 SET_DECL_OFFSET_ALIGN (field
, rli
->offset_align
);
1076 /* Work out the known alignment so far. Note that A & (-A) is the
1077 value of the least-significant bit in A that is one. */
1078 if (! integer_zerop (rli
->bitpos
))
1079 known_align
= (tree_low_cst (rli
->bitpos
, 1)
1080 & - tree_low_cst (rli
->bitpos
, 1));
1081 else if (integer_zerop (rli
->offset
))
1083 else if (host_integerp (rli
->offset
, 1))
1084 known_align
= (BITS_PER_UNIT
1085 * (tree_low_cst (rli
->offset
, 1)
1086 & - tree_low_cst (rli
->offset
, 1)));
1088 known_align
= rli
->offset_align
;
1090 desired_align
= update_alignment_for_field (rli
, field
, known_align
);
1091 if (known_align
== 0)
1092 known_align
= MAX (BIGGEST_ALIGNMENT
, rli
->record_align
);
1094 if (warn_packed
&& DECL_PACKED (field
))
1096 if (known_align
>= TYPE_ALIGN (type
))
1098 if (TYPE_ALIGN (type
) > desired_align
)
1100 if (STRICT_ALIGNMENT
)
1101 warning (OPT_Wattributes
, "packed attribute causes "
1102 "inefficient alignment for %q+D", field
);
1103 /* Don't warn if DECL_PACKED was set by the type. */
1104 else if (!TYPE_PACKED (rli
->t
))
1105 warning (OPT_Wattributes
, "packed attribute is "
1106 "unnecessary for %q+D", field
);
1110 rli
->packed_maybe_necessary
= 1;
1113 /* Does this field automatically have alignment it needs by virtue
1114 of the fields that precede it and the record's own alignment?
1115 We already align ms_struct fields, so don't re-align them. */
1116 if (known_align
< desired_align
1117 && !targetm
.ms_bitfield_layout_p (rli
->t
))
1119 /* No, we need to skip space before this field.
1120 Bump the cumulative size to multiple of field alignment. */
1122 if (DECL_SOURCE_LOCATION (field
) != BUILTINS_LOCATION
)
1123 warning (OPT_Wpadded
, "padding struct to align %q+D", field
);
1125 /* If the alignment is still within offset_align, just align
1126 the bit position. */
1127 if (desired_align
< rli
->offset_align
)
1128 rli
->bitpos
= round_up (rli
->bitpos
, desired_align
);
1131 /* First adjust OFFSET by the partial bits, then align. */
1133 = size_binop (PLUS_EXPR
, rli
->offset
,
1134 fold_convert (sizetype
,
1135 size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
1136 bitsize_unit_node
)));
1137 rli
->bitpos
= bitsize_zero_node
;
1139 rli
->offset
= round_up (rli
->offset
, desired_align
/ BITS_PER_UNIT
);
1142 if (! TREE_CONSTANT (rli
->offset
))
1143 rli
->offset_align
= desired_align
;
1147 /* Handle compatibility with PCC. Note that if the record has any
1148 variable-sized fields, we need not worry about compatibility. */
1149 #ifdef PCC_BITFIELD_TYPE_MATTERS
1150 if (PCC_BITFIELD_TYPE_MATTERS
1151 && ! targetm
.ms_bitfield_layout_p (rli
->t
)
1152 && TREE_CODE (field
) == FIELD_DECL
1153 && type
!= error_mark_node
1154 && DECL_BIT_FIELD (field
)
1155 && (! DECL_PACKED (field
)
1156 /* Enter for these packed fields only to issue a warning. */
1157 || TYPE_ALIGN (type
) <= BITS_PER_UNIT
)
1158 && maximum_field_alignment
== 0
1159 && ! integer_zerop (DECL_SIZE (field
))
1160 && host_integerp (DECL_SIZE (field
), 1)
1161 && host_integerp (rli
->offset
, 1)
1162 && host_integerp (TYPE_SIZE (type
), 1))
1164 unsigned int type_align
= TYPE_ALIGN (type
);
1165 tree dsize
= DECL_SIZE (field
);
1166 HOST_WIDE_INT field_size
= tree_low_cst (dsize
, 1);
1167 HOST_WIDE_INT offset
= tree_low_cst (rli
->offset
, 0);
1168 HOST_WIDE_INT bit_offset
= tree_low_cst (rli
->bitpos
, 0);
1170 #ifdef ADJUST_FIELD_ALIGN
1171 if (! TYPE_USER_ALIGN (type
))
1172 type_align
= ADJUST_FIELD_ALIGN (field
, type_align
);
1175 /* A bit field may not span more units of alignment of its type
1176 than its type itself. Advance to next boundary if necessary. */
1177 if (excess_unit_span (offset
, bit_offset
, field_size
, type_align
, type
))
1179 if (DECL_PACKED (field
))
1181 if (warn_packed_bitfield_compat
== 1)
1184 "Offset of packed bit-field %qD has changed in GCC 4.4",
1188 rli
->bitpos
= round_up_loc (input_location
, rli
->bitpos
, type_align
);
1191 if (! DECL_PACKED (field
))
1192 TYPE_USER_ALIGN (rli
->t
) |= TYPE_USER_ALIGN (type
);
1196 #ifdef BITFIELD_NBYTES_LIMITED
1197 if (BITFIELD_NBYTES_LIMITED
1198 && ! targetm
.ms_bitfield_layout_p (rli
->t
)
1199 && TREE_CODE (field
) == FIELD_DECL
1200 && type
!= error_mark_node
1201 && DECL_BIT_FIELD_TYPE (field
)
1202 && ! DECL_PACKED (field
)
1203 && ! integer_zerop (DECL_SIZE (field
))
1204 && host_integerp (DECL_SIZE (field
), 1)
1205 && host_integerp (rli
->offset
, 1)
1206 && host_integerp (TYPE_SIZE (type
), 1))
1208 unsigned int type_align
= TYPE_ALIGN (type
);
1209 tree dsize
= DECL_SIZE (field
);
1210 HOST_WIDE_INT field_size
= tree_low_cst (dsize
, 1);
1211 HOST_WIDE_INT offset
= tree_low_cst (rli
->offset
, 0);
1212 HOST_WIDE_INT bit_offset
= tree_low_cst (rli
->bitpos
, 0);
1214 #ifdef ADJUST_FIELD_ALIGN
1215 if (! TYPE_USER_ALIGN (type
))
1216 type_align
= ADJUST_FIELD_ALIGN (field
, type_align
);
1219 if (maximum_field_alignment
!= 0)
1220 type_align
= MIN (type_align
, maximum_field_alignment
);
1221 /* ??? This test is opposite the test in the containing if
1222 statement, so this code is unreachable currently. */
1223 else if (DECL_PACKED (field
))
1224 type_align
= MIN (type_align
, BITS_PER_UNIT
);
1226 /* A bit field may not span the unit of alignment of its type.
1227 Advance to next boundary if necessary. */
1228 if (excess_unit_span (offset
, bit_offset
, field_size
, type_align
, type
))
1229 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1231 TYPE_USER_ALIGN (rli
->t
) |= TYPE_USER_ALIGN (type
);
1235 /* See the docs for TARGET_MS_BITFIELD_LAYOUT_P for details.
1237 When a bit field is inserted into a packed record, the whole
1238 size of the underlying type is used by one or more same-size
1239 adjacent bitfields. (That is, if its long:3, 32 bits is
1240 used in the record, and any additional adjacent long bitfields are
1241 packed into the same chunk of 32 bits. However, if the size
1242 changes, a new field of that size is allocated.) In an unpacked
1243 record, this is the same as using alignment, but not equivalent
1246 Note: for compatibility, we use the type size, not the type alignment
1247 to determine alignment, since that matches the documentation */
1249 if (targetm
.ms_bitfield_layout_p (rli
->t
))
1251 tree prev_saved
= rli
->prev_field
;
1252 tree prev_type
= prev_saved
? DECL_BIT_FIELD_TYPE (prev_saved
) : NULL
;
1254 /* This is a bitfield if it exists. */
1255 if (rli
->prev_field
)
1257 /* If both are bitfields, nonzero, and the same size, this is
1258 the middle of a run. Zero declared size fields are special
1259 and handled as "end of run". (Note: it's nonzero declared
1260 size, but equal type sizes!) (Since we know that both
1261 the current and previous fields are bitfields by the
1262 time we check it, DECL_SIZE must be present for both.) */
1263 if (DECL_BIT_FIELD_TYPE (field
)
1264 && !integer_zerop (DECL_SIZE (field
))
1265 && !integer_zerop (DECL_SIZE (rli
->prev_field
))
1266 && host_integerp (DECL_SIZE (rli
->prev_field
), 0)
1267 && host_integerp (TYPE_SIZE (type
), 0)
1268 && simple_cst_equal (TYPE_SIZE (type
), TYPE_SIZE (prev_type
)))
1270 /* We're in the middle of a run of equal type size fields; make
1271 sure we realign if we run out of bits. (Not decl size,
1273 HOST_WIDE_INT bitsize
= tree_low_cst (DECL_SIZE (field
), 1);
1275 if (rli
->remaining_in_alignment
< bitsize
)
1277 HOST_WIDE_INT typesize
= tree_low_cst (TYPE_SIZE (type
), 1);
1279 /* out of bits; bump up to next 'word'. */
1281 = size_binop (PLUS_EXPR
, rli
->bitpos
,
1282 bitsize_int (rli
->remaining_in_alignment
));
1283 rli
->prev_field
= field
;
1284 if (typesize
< bitsize
)
1285 rli
->remaining_in_alignment
= 0;
1287 rli
->remaining_in_alignment
= typesize
- bitsize
;
1290 rli
->remaining_in_alignment
-= bitsize
;
1294 /* End of a run: if leaving a run of bitfields of the same type
1295 size, we have to "use up" the rest of the bits of the type
1298 Compute the new position as the sum of the size for the prior
1299 type and where we first started working on that type.
1300 Note: since the beginning of the field was aligned then
1301 of course the end will be too. No round needed. */
1303 if (!integer_zerop (DECL_SIZE (rli
->prev_field
)))
1306 = size_binop (PLUS_EXPR
, rli
->bitpos
,
1307 bitsize_int (rli
->remaining_in_alignment
));
1310 /* We "use up" size zero fields; the code below should behave
1311 as if the prior field was not a bitfield. */
1314 /* Cause a new bitfield to be captured, either this time (if
1315 currently a bitfield) or next time we see one. */
1316 if (!DECL_BIT_FIELD_TYPE(field
)
1317 || integer_zerop (DECL_SIZE (field
)))
1318 rli
->prev_field
= NULL
;
1321 normalize_rli (rli
);
1324 /* If we're starting a new run of same size type bitfields
1325 (or a run of non-bitfields), set up the "first of the run"
1328 That is, if the current field is not a bitfield, or if there
1329 was a prior bitfield the type sizes differ, or if there wasn't
1330 a prior bitfield the size of the current field is nonzero.
1332 Note: we must be sure to test ONLY the type size if there was
1333 a prior bitfield and ONLY for the current field being zero if
1336 if (!DECL_BIT_FIELD_TYPE (field
)
1337 || (prev_saved
!= NULL
1338 ? !simple_cst_equal (TYPE_SIZE (type
), TYPE_SIZE (prev_type
))
1339 : !integer_zerop (DECL_SIZE (field
)) ))
1341 /* Never smaller than a byte for compatibility. */
1342 unsigned int type_align
= BITS_PER_UNIT
;
1344 /* (When not a bitfield), we could be seeing a flex array (with
1345 no DECL_SIZE). Since we won't be using remaining_in_alignment
1346 until we see a bitfield (and come by here again) we just skip
1348 if (DECL_SIZE (field
) != NULL
1349 && host_integerp (TYPE_SIZE (TREE_TYPE (field
)), 1)
1350 && host_integerp (DECL_SIZE (field
), 1))
1352 unsigned HOST_WIDE_INT bitsize
1353 = tree_low_cst (DECL_SIZE (field
), 1);
1354 unsigned HOST_WIDE_INT typesize
1355 = tree_low_cst (TYPE_SIZE (TREE_TYPE (field
)), 1);
1357 if (typesize
< bitsize
)
1358 rli
->remaining_in_alignment
= 0;
1360 rli
->remaining_in_alignment
= typesize
- bitsize
;
1363 /* Now align (conventionally) for the new type. */
1364 type_align
= TYPE_ALIGN (TREE_TYPE (field
));
1366 if (maximum_field_alignment
!= 0)
1367 type_align
= MIN (type_align
, maximum_field_alignment
);
1369 rli
->bitpos
= round_up_loc (input_location
, rli
->bitpos
, type_align
);
1371 /* If we really aligned, don't allow subsequent bitfields
1373 rli
->prev_field
= NULL
;
1377 /* Offset so far becomes the position of this field after normalizing. */
1378 normalize_rli (rli
);
1379 DECL_FIELD_OFFSET (field
) = rli
->offset
;
1380 DECL_FIELD_BIT_OFFSET (field
) = rli
->bitpos
;
1381 SET_DECL_OFFSET_ALIGN (field
, rli
->offset_align
);
1383 /* If this field ended up more aligned than we thought it would be (we
1384 approximate this by seeing if its position changed), lay out the field
1385 again; perhaps we can use an integral mode for it now. */
1386 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field
)))
1387 actual_align
= (tree_low_cst (DECL_FIELD_BIT_OFFSET (field
), 1)
1388 & - tree_low_cst (DECL_FIELD_BIT_OFFSET (field
), 1));
1389 else if (integer_zerop (DECL_FIELD_OFFSET (field
)))
1390 actual_align
= MAX (BIGGEST_ALIGNMENT
, rli
->record_align
);
1391 else if (host_integerp (DECL_FIELD_OFFSET (field
), 1))
1392 actual_align
= (BITS_PER_UNIT
1393 * (tree_low_cst (DECL_FIELD_OFFSET (field
), 1)
1394 & - tree_low_cst (DECL_FIELD_OFFSET (field
), 1)));
1396 actual_align
= DECL_OFFSET_ALIGN (field
);
1397 /* ACTUAL_ALIGN is still the actual alignment *within the record* .
1398 store / extract bit field operations will check the alignment of the
1399 record against the mode of bit fields. */
1401 if (known_align
!= actual_align
)
1402 layout_decl (field
, actual_align
);
1404 if (rli
->prev_field
== NULL
&& DECL_BIT_FIELD_TYPE (field
))
1405 rli
->prev_field
= field
;
1407 /* Now add size of this field to the size of the record. If the size is
1408 not constant, treat the field as being a multiple of bytes and just
1409 adjust the offset, resetting the bit position. Otherwise, apportion the
1410 size amongst the bit position and offset. First handle the case of an
1411 unspecified size, which can happen when we have an invalid nested struct
1412 definition, such as struct j { struct j { int i; } }. The error message
1413 is printed in finish_struct. */
1414 if (DECL_SIZE (field
) == 0)
1416 else if (TREE_CODE (DECL_SIZE (field
)) != INTEGER_CST
1417 || TREE_OVERFLOW (DECL_SIZE (field
)))
1420 = size_binop (PLUS_EXPR
, rli
->offset
,
1421 fold_convert (sizetype
,
1422 size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
1423 bitsize_unit_node
)));
1425 = size_binop (PLUS_EXPR
, rli
->offset
, DECL_SIZE_UNIT (field
));
1426 rli
->bitpos
= bitsize_zero_node
;
1427 rli
->offset_align
= MIN (rli
->offset_align
, desired_align
);
1429 else if (targetm
.ms_bitfield_layout_p (rli
->t
))
1431 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
, DECL_SIZE (field
));
1433 /* If we ended a bitfield before the full length of the type then
1434 pad the struct out to the full length of the last type. */
1435 if ((TREE_CHAIN (field
) == NULL
1436 || TREE_CODE (TREE_CHAIN (field
)) != FIELD_DECL
)
1437 && DECL_BIT_FIELD_TYPE (field
)
1438 && !integer_zerop (DECL_SIZE (field
)))
1439 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
,
1440 bitsize_int (rli
->remaining_in_alignment
));
1442 normalize_rli (rli
);
1446 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
, DECL_SIZE (field
));
1447 normalize_rli (rli
);
1451 /* Assuming that all the fields have been laid out, this function uses
1452 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
1453 indicated by RLI. */
1456 finalize_record_size (record_layout_info rli
)
1458 tree unpadded_size
, unpadded_size_unit
;
1460 /* Now we want just byte and bit offsets, so set the offset alignment
1461 to be a byte and then normalize. */
1462 rli
->offset_align
= BITS_PER_UNIT
;
1463 normalize_rli (rli
);
1465 /* Determine the desired alignment. */
1466 #ifdef ROUND_TYPE_ALIGN
1467 TYPE_ALIGN (rli
->t
) = ROUND_TYPE_ALIGN (rli
->t
, TYPE_ALIGN (rli
->t
),
1470 TYPE_ALIGN (rli
->t
) = MAX (TYPE_ALIGN (rli
->t
), rli
->record_align
);
1473 /* Compute the size so far. Be sure to allow for extra bits in the
1474 size in bytes. We have guaranteed above that it will be no more
1475 than a single byte. */
1476 unpadded_size
= rli_size_so_far (rli
);
1477 unpadded_size_unit
= rli_size_unit_so_far (rli
);
1478 if (! integer_zerop (rli
->bitpos
))
1480 = size_binop (PLUS_EXPR
, unpadded_size_unit
, size_one_node
);
1482 /* Round the size up to be a multiple of the required alignment. */
1483 TYPE_SIZE (rli
->t
) = round_up_loc (input_location
, unpadded_size
,
1484 TYPE_ALIGN (rli
->t
));
1485 TYPE_SIZE_UNIT (rli
->t
)
1486 = round_up_loc (input_location
, unpadded_size_unit
, TYPE_ALIGN_UNIT (rli
->t
));
1488 if (TREE_CONSTANT (unpadded_size
)
1489 && simple_cst_equal (unpadded_size
, TYPE_SIZE (rli
->t
)) == 0
1490 && input_location
!= BUILTINS_LOCATION
)
1491 warning (OPT_Wpadded
, "padding struct size to alignment boundary");
1493 if (warn_packed
&& TREE_CODE (rli
->t
) == RECORD_TYPE
1494 && TYPE_PACKED (rli
->t
) && ! rli
->packed_maybe_necessary
1495 && TREE_CONSTANT (unpadded_size
))
1499 #ifdef ROUND_TYPE_ALIGN
1501 = ROUND_TYPE_ALIGN (rli
->t
, TYPE_ALIGN (rli
->t
), rli
->unpacked_align
);
1503 rli
->unpacked_align
= MAX (TYPE_ALIGN (rli
->t
), rli
->unpacked_align
);
1506 unpacked_size
= round_up_loc (input_location
, TYPE_SIZE (rli
->t
), rli
->unpacked_align
);
1507 if (simple_cst_equal (unpacked_size
, TYPE_SIZE (rli
->t
)))
1509 TYPE_PACKED (rli
->t
) = 0;
1511 if (TYPE_NAME (rli
->t
))
1515 if (TREE_CODE (TYPE_NAME (rli
->t
)) == IDENTIFIER_NODE
)
1516 name
= TYPE_NAME (rli
->t
);
1518 name
= DECL_NAME (TYPE_NAME (rli
->t
));
1520 if (STRICT_ALIGNMENT
)
1521 warning (OPT_Wpacked
, "packed attribute causes inefficient "
1522 "alignment for %qE", name
);
1524 warning (OPT_Wpacked
,
1525 "packed attribute is unnecessary for %qE", name
);
1529 if (STRICT_ALIGNMENT
)
1530 warning (OPT_Wpacked
,
1531 "packed attribute causes inefficient alignment");
1533 warning (OPT_Wpacked
, "packed attribute is unnecessary");
1539 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
1542 compute_record_mode (tree type
)
1545 enum machine_mode mode
= VOIDmode
;
1547 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
1548 However, if possible, we use a mode that fits in a register
1549 instead, in order to allow for better optimization down the
1551 SET_TYPE_MODE (type
, BLKmode
);
1553 if (! host_integerp (TYPE_SIZE (type
), 1))
1556 /* A record which has any BLKmode members must itself be
1557 BLKmode; it can't go in a register. Unless the member is
1558 BLKmode only because it isn't aligned. */
1559 for (field
= TYPE_FIELDS (type
); field
; field
= TREE_CHAIN (field
))
1561 if (TREE_CODE (field
) != FIELD_DECL
)
1564 if (TREE_CODE (TREE_TYPE (field
)) == ERROR_MARK
1565 || (TYPE_MODE (TREE_TYPE (field
)) == BLKmode
1566 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field
))
1567 && !(TYPE_SIZE (TREE_TYPE (field
)) != 0
1568 && integer_zerop (TYPE_SIZE (TREE_TYPE (field
)))))
1569 || ! host_integerp (bit_position (field
), 1)
1570 || DECL_SIZE (field
) == 0
1571 || ! host_integerp (DECL_SIZE (field
), 1))
1574 /* If this field is the whole struct, remember its mode so
1575 that, say, we can put a double in a class into a DF
1576 register instead of forcing it to live in the stack. */
1577 if (simple_cst_equal (TYPE_SIZE (type
), DECL_SIZE (field
)))
1578 mode
= DECL_MODE (field
);
1580 #ifdef MEMBER_TYPE_FORCES_BLK
1581 /* With some targets, eg. c4x, it is sub-optimal
1582 to access an aligned BLKmode structure as a scalar. */
1584 if (MEMBER_TYPE_FORCES_BLK (field
, mode
))
1586 #endif /* MEMBER_TYPE_FORCES_BLK */
1589 /* If we only have one real field; use its mode if that mode's size
1590 matches the type's size. This only applies to RECORD_TYPE. This
1591 does not apply to unions. */
1592 if (TREE_CODE (type
) == RECORD_TYPE
&& mode
!= VOIDmode
1593 && host_integerp (TYPE_SIZE (type
), 1)
1594 && GET_MODE_BITSIZE (mode
) == TREE_INT_CST_LOW (TYPE_SIZE (type
)))
1595 SET_TYPE_MODE (type
, mode
);
1597 SET_TYPE_MODE (type
, mode_for_size_tree (TYPE_SIZE (type
), MODE_INT
, 1));
1599 /* If structure's known alignment is less than what the scalar
1600 mode would need, and it matters, then stick with BLKmode. */
1601 if (TYPE_MODE (type
) != BLKmode
1603 && ! (TYPE_ALIGN (type
) >= BIGGEST_ALIGNMENT
1604 || TYPE_ALIGN (type
) >= GET_MODE_ALIGNMENT (TYPE_MODE (type
))))
1606 /* If this is the only reason this type is BLKmode, then
1607 don't force containing types to be BLKmode. */
1608 TYPE_NO_FORCE_BLK (type
) = 1;
1609 SET_TYPE_MODE (type
, BLKmode
);
1613 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1617 finalize_type_size (tree type
)
1619 /* Normally, use the alignment corresponding to the mode chosen.
1620 However, where strict alignment is not required, avoid
1621 over-aligning structures, since most compilers do not do this
1624 if (TYPE_MODE (type
) != BLKmode
&& TYPE_MODE (type
) != VOIDmode
1625 && (STRICT_ALIGNMENT
1626 || (TREE_CODE (type
) != RECORD_TYPE
&& TREE_CODE (type
) != UNION_TYPE
1627 && TREE_CODE (type
) != QUAL_UNION_TYPE
1628 && TREE_CODE (type
) != ARRAY_TYPE
)))
1630 unsigned mode_align
= GET_MODE_ALIGNMENT (TYPE_MODE (type
));
1632 /* Don't override a larger alignment requirement coming from a user
1633 alignment of one of the fields. */
1634 if (mode_align
>= TYPE_ALIGN (type
))
1636 TYPE_ALIGN (type
) = mode_align
;
1637 TYPE_USER_ALIGN (type
) = 0;
1641 /* Do machine-dependent extra alignment. */
1642 #ifdef ROUND_TYPE_ALIGN
1644 = ROUND_TYPE_ALIGN (type
, TYPE_ALIGN (type
), BITS_PER_UNIT
);
1647 /* If we failed to find a simple way to calculate the unit size
1648 of the type, find it by division. */
1649 if (TYPE_SIZE_UNIT (type
) == 0 && TYPE_SIZE (type
) != 0)
1650 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1651 result will fit in sizetype. We will get more efficient code using
1652 sizetype, so we force a conversion. */
1653 TYPE_SIZE_UNIT (type
)
1654 = fold_convert (sizetype
,
1655 size_binop (FLOOR_DIV_EXPR
, TYPE_SIZE (type
),
1656 bitsize_unit_node
));
1658 if (TYPE_SIZE (type
) != 0)
1660 TYPE_SIZE (type
) = round_up_loc (input_location
,
1661 TYPE_SIZE (type
), TYPE_ALIGN (type
));
1662 TYPE_SIZE_UNIT (type
) = round_up_loc (input_location
, TYPE_SIZE_UNIT (type
),
1663 TYPE_ALIGN_UNIT (type
));
1666 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1667 if (TYPE_SIZE (type
) != 0 && TREE_CODE (TYPE_SIZE (type
)) != INTEGER_CST
)
1668 TYPE_SIZE (type
) = variable_size (TYPE_SIZE (type
));
1669 if (TYPE_SIZE_UNIT (type
) != 0
1670 && TREE_CODE (TYPE_SIZE_UNIT (type
)) != INTEGER_CST
)
1671 TYPE_SIZE_UNIT (type
) = variable_size (TYPE_SIZE_UNIT (type
));
1673 /* Also layout any other variants of the type. */
1674 if (TYPE_NEXT_VARIANT (type
)
1675 || type
!= TYPE_MAIN_VARIANT (type
))
1678 /* Record layout info of this variant. */
1679 tree size
= TYPE_SIZE (type
);
1680 tree size_unit
= TYPE_SIZE_UNIT (type
);
1681 unsigned int align
= TYPE_ALIGN (type
);
1682 unsigned int user_align
= TYPE_USER_ALIGN (type
);
1683 enum machine_mode mode
= TYPE_MODE (type
);
1685 /* Copy it into all variants. */
1686 for (variant
= TYPE_MAIN_VARIANT (type
);
1688 variant
= TYPE_NEXT_VARIANT (variant
))
1690 TYPE_SIZE (variant
) = size
;
1691 TYPE_SIZE_UNIT (variant
) = size_unit
;
1692 TYPE_ALIGN (variant
) = align
;
1693 TYPE_USER_ALIGN (variant
) = user_align
;
1694 SET_TYPE_MODE (variant
, mode
);
1699 /* Do all of the work required to layout the type indicated by RLI,
1700 once the fields have been laid out. This function will call `free'
1701 for RLI, unless FREE_P is false. Passing a value other than false
1702 for FREE_P is bad practice; this option only exists to support the
1706 finish_record_layout (record_layout_info rli
, int free_p
)
1710 /* Compute the final size. */
1711 finalize_record_size (rli
);
1713 /* Compute the TYPE_MODE for the record. */
1714 compute_record_mode (rli
->t
);
1716 /* Perform any last tweaks to the TYPE_SIZE, etc. */
1717 finalize_type_size (rli
->t
);
1719 /* Propagate TYPE_PACKED to variants. With C++ templates,
1720 handle_packed_attribute is too early to do this. */
1721 for (variant
= TYPE_NEXT_VARIANT (rli
->t
); variant
;
1722 variant
= TYPE_NEXT_VARIANT (variant
))
1723 TYPE_PACKED (variant
) = TYPE_PACKED (rli
->t
);
1725 /* Lay out any static members. This is done now because their type
1726 may use the record's type. */
1727 while (rli
->pending_statics
)
1729 layout_decl (TREE_VALUE (rli
->pending_statics
), 0);
1730 rli
->pending_statics
= TREE_CHAIN (rli
->pending_statics
);
1739 /* Finish processing a builtin RECORD_TYPE type TYPE. It's name is
1740 NAME, its fields are chained in reverse on FIELDS.
1742 If ALIGN_TYPE is non-null, it is given the same alignment as
1746 finish_builtin_struct (tree type
, const char *name
, tree fields
,
1751 for (tail
= NULL_TREE
; fields
; tail
= fields
, fields
= next
)
1753 DECL_FIELD_CONTEXT (fields
) = type
;
1754 next
= TREE_CHAIN (fields
);
1755 TREE_CHAIN (fields
) = tail
;
1757 TYPE_FIELDS (type
) = tail
;
1761 TYPE_ALIGN (type
) = TYPE_ALIGN (align_type
);
1762 TYPE_USER_ALIGN (type
) = TYPE_USER_ALIGN (align_type
);
1766 #if 0 /* not yet, should get fixed properly later */
1767 TYPE_NAME (type
) = make_type_decl (get_identifier (name
), type
);
1769 TYPE_NAME (type
) = build_decl (BUILTINS_LOCATION
,
1770 TYPE_DECL
, get_identifier (name
), type
);
1772 TYPE_STUB_DECL (type
) = TYPE_NAME (type
);
1773 layout_decl (TYPE_NAME (type
), 0);
1776 /* Calculate the mode, size, and alignment for TYPE.
1777 For an array type, calculate the element separation as well.
1778 Record TYPE on the chain of permanent or temporary types
1779 so that dbxout will find out about it.
1781 TYPE_SIZE of a type is nonzero if the type has been laid out already.
1782 layout_type does nothing on such a type.
1784 If the type is incomplete, its TYPE_SIZE remains zero. */
1787 layout_type (tree type
)
1791 if (type
== error_mark_node
)
1794 /* Do nothing if type has been laid out before. */
1795 if (TYPE_SIZE (type
))
1798 switch (TREE_CODE (type
))
1801 /* This kind of type is the responsibility
1802 of the language-specific code. */
1805 case BOOLEAN_TYPE
: /* Used for Java, Pascal, and Chill. */
1806 if (TYPE_PRECISION (type
) == 0)
1807 TYPE_PRECISION (type
) = 1; /* default to one byte/boolean. */
1809 /* ... fall through ... */
1813 if (TREE_CODE (TYPE_MIN_VALUE (type
)) == INTEGER_CST
1814 && tree_int_cst_sgn (TYPE_MIN_VALUE (type
)) >= 0)
1815 TYPE_UNSIGNED (type
) = 1;
1817 SET_TYPE_MODE (type
,
1818 smallest_mode_for_size (TYPE_PRECISION (type
), MODE_INT
));
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
)));
1824 SET_TYPE_MODE (type
,
1825 mode_for_size (TYPE_PRECISION (type
), MODE_FLOAT
, 0));
1826 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
1827 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
1830 case FIXED_POINT_TYPE
:
1831 /* TYPE_MODE (type) has been set already. */
1832 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
1833 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
1837 TYPE_UNSIGNED (type
) = TYPE_UNSIGNED (TREE_TYPE (type
));
1838 SET_TYPE_MODE (type
,
1839 mode_for_size (2 * TYPE_PRECISION (TREE_TYPE (type
)),
1840 (TREE_CODE (TREE_TYPE (type
)) == REAL_TYPE
1841 ? MODE_COMPLEX_FLOAT
: MODE_COMPLEX_INT
),
1843 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
1844 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
1849 int nunits
= TYPE_VECTOR_SUBPARTS (type
);
1850 tree innertype
= TREE_TYPE (type
);
1852 gcc_assert (!(nunits
& (nunits
- 1)));
1854 /* Find an appropriate mode for the vector type. */
1855 if (TYPE_MODE (type
) == VOIDmode
)
1857 enum machine_mode innermode
= TYPE_MODE (innertype
);
1858 enum machine_mode mode
;
1860 /* First, look for a supported vector type. */
1861 if (SCALAR_FLOAT_MODE_P (innermode
))
1862 mode
= MIN_MODE_VECTOR_FLOAT
;
1863 else if (SCALAR_FRACT_MODE_P (innermode
))
1864 mode
= MIN_MODE_VECTOR_FRACT
;
1865 else if (SCALAR_UFRACT_MODE_P (innermode
))
1866 mode
= MIN_MODE_VECTOR_UFRACT
;
1867 else if (SCALAR_ACCUM_MODE_P (innermode
))
1868 mode
= MIN_MODE_VECTOR_ACCUM
;
1869 else if (SCALAR_UACCUM_MODE_P (innermode
))
1870 mode
= MIN_MODE_VECTOR_UACCUM
;
1872 mode
= MIN_MODE_VECTOR_INT
;
1874 /* Do not check vector_mode_supported_p here. We'll do that
1875 later in vector_type_mode. */
1876 for (; mode
!= VOIDmode
; mode
= GET_MODE_WIDER_MODE (mode
))
1877 if (GET_MODE_NUNITS (mode
) == nunits
1878 && GET_MODE_INNER (mode
) == innermode
)
1881 /* For integers, try mapping it to a same-sized scalar mode. */
1882 if (mode
== VOIDmode
1883 && GET_MODE_CLASS (innermode
) == MODE_INT
)
1884 mode
= mode_for_size (nunits
* GET_MODE_BITSIZE (innermode
),
1887 if (mode
== VOIDmode
||
1888 (GET_MODE_CLASS (mode
) == MODE_INT
1889 && !have_regs_of_mode
[mode
]))
1890 SET_TYPE_MODE (type
, BLKmode
);
1892 SET_TYPE_MODE (type
, mode
);
1895 TYPE_SATURATING (type
) = TYPE_SATURATING (TREE_TYPE (type
));
1896 TYPE_UNSIGNED (type
) = TYPE_UNSIGNED (TREE_TYPE (type
));
1897 TYPE_SIZE_UNIT (type
) = int_const_binop (MULT_EXPR
,
1898 TYPE_SIZE_UNIT (innertype
),
1899 size_int (nunits
), 0);
1900 TYPE_SIZE (type
) = int_const_binop (MULT_EXPR
, TYPE_SIZE (innertype
),
1901 bitsize_int (nunits
), 0);
1903 /* Always naturally align vectors. This prevents ABI changes
1904 depending on whether or not native vector modes are supported. */
1905 TYPE_ALIGN (type
) = tree_low_cst (TYPE_SIZE (type
), 0);
1910 /* This is an incomplete type and so doesn't have a size. */
1911 TYPE_ALIGN (type
) = 1;
1912 TYPE_USER_ALIGN (type
) = 0;
1913 SET_TYPE_MODE (type
, VOIDmode
);
1917 TYPE_SIZE (type
) = bitsize_int (POINTER_SIZE
);
1918 TYPE_SIZE_UNIT (type
) = size_int (POINTER_SIZE
/ BITS_PER_UNIT
);
1919 /* A pointer might be MODE_PARTIAL_INT,
1920 but ptrdiff_t must be integral. */
1921 SET_TYPE_MODE (type
, mode_for_size (POINTER_SIZE
, MODE_INT
, 0));
1922 TYPE_PRECISION (type
) = POINTER_SIZE
;
1927 /* It's hard to see what the mode and size of a function ought to
1928 be, but we do know the alignment is FUNCTION_BOUNDARY, so
1929 make it consistent with that. */
1930 SET_TYPE_MODE (type
, mode_for_size (FUNCTION_BOUNDARY
, MODE_INT
, 0));
1931 TYPE_SIZE (type
) = bitsize_int (FUNCTION_BOUNDARY
);
1932 TYPE_SIZE_UNIT (type
) = size_int (FUNCTION_BOUNDARY
/ BITS_PER_UNIT
);
1936 case REFERENCE_TYPE
:
1938 enum machine_mode mode
= TYPE_MODE (type
);
1939 if (TREE_CODE (type
) == REFERENCE_TYPE
&& reference_types_internal
)
1941 addr_space_t as
= TYPE_ADDR_SPACE (TREE_TYPE (type
));
1942 mode
= targetm
.addr_space
.address_mode (as
);
1945 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
1946 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
1947 TYPE_UNSIGNED (type
) = 1;
1948 TYPE_PRECISION (type
) = GET_MODE_BITSIZE (mode
);
1954 tree index
= TYPE_DOMAIN (type
);
1955 tree element
= TREE_TYPE (type
);
1957 build_pointer_type (element
);
1959 /* We need to know both bounds in order to compute the size. */
1960 if (index
&& TYPE_MAX_VALUE (index
) && TYPE_MIN_VALUE (index
)
1961 && TYPE_SIZE (element
))
1963 tree ub
= TYPE_MAX_VALUE (index
);
1964 tree lb
= TYPE_MIN_VALUE (index
);
1965 tree element_size
= TYPE_SIZE (element
);
1968 /* Make sure that an array of zero-sized element is zero-sized
1969 regardless of its extent. */
1970 if (integer_zerop (element_size
))
1971 length
= size_zero_node
;
1973 /* The initial subtraction should happen in the original type so
1974 that (possible) negative values are handled appropriately. */
1977 = size_binop (PLUS_EXPR
, size_one_node
,
1978 fold_convert (sizetype
,
1979 fold_build2_loc (input_location
,
1984 TYPE_SIZE (type
) = size_binop (MULT_EXPR
, element_size
,
1985 fold_convert (bitsizetype
,
1988 /* If we know the size of the element, calculate the total size
1989 directly, rather than do some division thing below. This
1990 optimization helps Fortran assumed-size arrays (where the
1991 size of the array is determined at runtime) substantially. */
1992 if (TYPE_SIZE_UNIT (element
))
1993 TYPE_SIZE_UNIT (type
)
1994 = size_binop (MULT_EXPR
, TYPE_SIZE_UNIT (element
), length
);
1997 /* Now round the alignment and size,
1998 using machine-dependent criteria if any. */
2000 #ifdef ROUND_TYPE_ALIGN
2002 = ROUND_TYPE_ALIGN (type
, TYPE_ALIGN (element
), BITS_PER_UNIT
);
2004 TYPE_ALIGN (type
) = MAX (TYPE_ALIGN (element
), BITS_PER_UNIT
);
2006 if (!TYPE_SIZE (element
))
2007 /* We don't know the size of the underlying element type, so
2008 our alignment calculations will be wrong, forcing us to
2009 fall back on structural equality. */
2010 SET_TYPE_STRUCTURAL_EQUALITY (type
);
2011 TYPE_USER_ALIGN (type
) = TYPE_USER_ALIGN (element
);
2012 SET_TYPE_MODE (type
, BLKmode
);
2013 if (TYPE_SIZE (type
) != 0
2014 #ifdef MEMBER_TYPE_FORCES_BLK
2015 && ! MEMBER_TYPE_FORCES_BLK (type
, VOIDmode
)
2017 /* BLKmode elements force BLKmode aggregate;
2018 else extract/store fields may lose. */
2019 && (TYPE_MODE (TREE_TYPE (type
)) != BLKmode
2020 || TYPE_NO_FORCE_BLK (TREE_TYPE (type
))))
2022 /* One-element arrays get the component type's mode. */
2023 if (simple_cst_equal (TYPE_SIZE (type
),
2024 TYPE_SIZE (TREE_TYPE (type
))))
2025 SET_TYPE_MODE (type
, TYPE_MODE (TREE_TYPE (type
)));
2027 SET_TYPE_MODE (type
, mode_for_size_tree (TYPE_SIZE (type
),
2030 if (TYPE_MODE (type
) != BLKmode
2031 && STRICT_ALIGNMENT
&& TYPE_ALIGN (type
) < BIGGEST_ALIGNMENT
2032 && TYPE_ALIGN (type
) < GET_MODE_ALIGNMENT (TYPE_MODE (type
)))
2034 TYPE_NO_FORCE_BLK (type
) = 1;
2035 SET_TYPE_MODE (type
, BLKmode
);
2038 /* When the element size is constant, check that it is at least as
2039 large as the element alignment. */
2040 if (TYPE_SIZE_UNIT (element
)
2041 && TREE_CODE (TYPE_SIZE_UNIT (element
)) == INTEGER_CST
2042 /* If TYPE_SIZE_UNIT overflowed, then it is certainly larger than
2044 && !TREE_OVERFLOW (TYPE_SIZE_UNIT (element
))
2045 && !integer_zerop (TYPE_SIZE_UNIT (element
))
2046 && compare_tree_int (TYPE_SIZE_UNIT (element
),
2047 TYPE_ALIGN_UNIT (element
)) < 0)
2048 error ("alignment of array elements is greater than element size");
2054 case QUAL_UNION_TYPE
:
2057 record_layout_info rli
;
2059 /* Initialize the layout information. */
2060 rli
= start_record_layout (type
);
2062 /* If this is a QUAL_UNION_TYPE, we want to process the fields
2063 in the reverse order in building the COND_EXPR that denotes
2064 its size. We reverse them again later. */
2065 if (TREE_CODE (type
) == QUAL_UNION_TYPE
)
2066 TYPE_FIELDS (type
) = nreverse (TYPE_FIELDS (type
));
2068 /* Place all the fields. */
2069 for (field
= TYPE_FIELDS (type
); field
; field
= TREE_CHAIN (field
))
2070 place_field (rli
, field
);
2072 if (TREE_CODE (type
) == QUAL_UNION_TYPE
)
2073 TYPE_FIELDS (type
) = nreverse (TYPE_FIELDS (type
));
2075 /* Finish laying out the record. */
2076 finish_record_layout (rli
, /*free_p=*/true);
2084 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
2085 records and unions, finish_record_layout already called this
2087 if (TREE_CODE (type
) != RECORD_TYPE
2088 && TREE_CODE (type
) != UNION_TYPE
2089 && TREE_CODE (type
) != QUAL_UNION_TYPE
)
2090 finalize_type_size (type
);
2092 /* We should never see alias sets on incomplete aggregates. And we
2093 should not call layout_type on not incomplete aggregates. */
2094 if (AGGREGATE_TYPE_P (type
))
2095 gcc_assert (!TYPE_ALIAS_SET_KNOWN_P (type
));
2098 /* Vector types need to re-check the target flags each time we report
2099 the machine mode. We need to do this because attribute target can
2100 change the result of vector_mode_supported_p and have_regs_of_mode
2101 on a per-function basis. Thus the TYPE_MODE of a VECTOR_TYPE can
2102 change on a per-function basis. */
2103 /* ??? Possibly a better solution is to run through all the types
2104 referenced by a function and re-compute the TYPE_MODE once, rather
2105 than make the TYPE_MODE macro call a function. */
2108 vector_type_mode (const_tree t
)
2110 enum machine_mode mode
;
2112 gcc_assert (TREE_CODE (t
) == VECTOR_TYPE
);
2114 mode
= t
->type
.mode
;
2115 if (VECTOR_MODE_P (mode
)
2116 && (!targetm
.vector_mode_supported_p (mode
)
2117 || !have_regs_of_mode
[mode
]))
2119 enum machine_mode innermode
= TREE_TYPE (t
)->type
.mode
;
2121 /* For integers, try mapping it to a same-sized scalar mode. */
2122 if (GET_MODE_CLASS (innermode
) == MODE_INT
)
2124 mode
= mode_for_size (TYPE_VECTOR_SUBPARTS (t
)
2125 * GET_MODE_BITSIZE (innermode
), MODE_INT
, 0);
2127 if (mode
!= VOIDmode
&& have_regs_of_mode
[mode
])
2137 /* Create and return a type for signed integers of PRECISION bits. */
2140 make_signed_type (int precision
)
2142 tree type
= make_node (INTEGER_TYPE
);
2144 TYPE_PRECISION (type
) = precision
;
2146 fixup_signed_type (type
);
2150 /* Create and return a type for unsigned integers of PRECISION bits. */
2153 make_unsigned_type (int precision
)
2155 tree type
= make_node (INTEGER_TYPE
);
2157 TYPE_PRECISION (type
) = precision
;
2159 fixup_unsigned_type (type
);
2163 /* Create and return a type for fract of PRECISION bits, UNSIGNEDP,
2167 make_fract_type (int precision
, int unsignedp
, int satp
)
2169 tree type
= make_node (FIXED_POINT_TYPE
);
2171 TYPE_PRECISION (type
) = precision
;
2174 TYPE_SATURATING (type
) = 1;
2176 /* Lay out the type: set its alignment, size, etc. */
2179 TYPE_UNSIGNED (type
) = 1;
2180 SET_TYPE_MODE (type
, mode_for_size (precision
, MODE_UFRACT
, 0));
2183 SET_TYPE_MODE (type
, mode_for_size (precision
, MODE_FRACT
, 0));
2189 /* Create and return a type for accum of PRECISION bits, UNSIGNEDP,
2193 make_accum_type (int precision
, int unsignedp
, int satp
)
2195 tree type
= make_node (FIXED_POINT_TYPE
);
2197 TYPE_PRECISION (type
) = precision
;
2200 TYPE_SATURATING (type
) = 1;
2202 /* Lay out the type: set its alignment, size, etc. */
2205 TYPE_UNSIGNED (type
) = 1;
2206 SET_TYPE_MODE (type
, mode_for_size (precision
, MODE_UACCUM
, 0));
2209 SET_TYPE_MODE (type
, mode_for_size (precision
, MODE_ACCUM
, 0));
2215 /* Initialize sizetype and bitsizetype to a reasonable and temporary
2216 value to enable integer types to be created. */
2219 initialize_sizetypes (bool signed_p
)
2221 tree t
= make_node (INTEGER_TYPE
);
2222 int precision
= GET_MODE_BITSIZE (SImode
);
2224 SET_TYPE_MODE (t
, SImode
);
2225 TYPE_ALIGN (t
) = GET_MODE_ALIGNMENT (SImode
);
2226 TYPE_USER_ALIGN (t
) = 0;
2227 TYPE_IS_SIZETYPE (t
) = 1;
2228 TYPE_UNSIGNED (t
) = !signed_p
;
2229 TYPE_SIZE (t
) = build_int_cst (t
, precision
);
2230 TYPE_SIZE_UNIT (t
) = build_int_cst (t
, GET_MODE_SIZE (SImode
));
2231 TYPE_PRECISION (t
) = precision
;
2233 /* Set TYPE_MIN_VALUE and TYPE_MAX_VALUE. */
2234 set_min_and_max_values_for_integral_type (t
, precision
, !signed_p
);
2237 bitsizetype
= build_distinct_type_copy (t
);
2240 /* Make sizetype a version of TYPE, and initialize *sizetype
2241 accordingly. We do this by overwriting the stub sizetype and
2242 bitsizetype nodes created by initialize_sizetypes. This makes sure
2243 that (a) anything stubby about them no longer exists, (b) any
2244 INTEGER_CSTs created with such a type, remain valid. */
2247 set_sizetype (tree type
)
2250 int oprecision
= TYPE_PRECISION (type
);
2251 /* The *bitsizetype types use a precision that avoids overflows when
2252 calculating signed sizes / offsets in bits. However, when
2253 cross-compiling from a 32 bit to a 64 bit host, we are limited to 64 bit
2256 = MIN (oprecision
+ BITS_PER_UNIT_LOG
+ 1, MAX_FIXED_MODE_SIZE
);
2258 = GET_MODE_PRECISION (smallest_mode_for_size (precision
, MODE_INT
));
2259 if (precision
> HOST_BITS_PER_WIDE_INT
* 2)
2260 precision
= HOST_BITS_PER_WIDE_INT
* 2;
2262 gcc_assert (TYPE_UNSIGNED (type
) == TYPE_UNSIGNED (sizetype
));
2264 t
= build_distinct_type_copy (type
);
2265 /* We do want to use sizetype's cache, as we will be replacing that
2267 TYPE_CACHED_VALUES (t
) = TYPE_CACHED_VALUES (sizetype
);
2268 TYPE_CACHED_VALUES_P (t
) = TYPE_CACHED_VALUES_P (sizetype
);
2269 TREE_TYPE (TYPE_CACHED_VALUES (t
)) = type
;
2270 TYPE_UID (t
) = TYPE_UID (sizetype
);
2271 TYPE_IS_SIZETYPE (t
) = 1;
2273 /* Replace our original stub sizetype. */
2274 memcpy (sizetype
, t
, tree_size (sizetype
));
2275 TYPE_MAIN_VARIANT (sizetype
) = sizetype
;
2276 TYPE_CANONICAL (sizetype
) = sizetype
;
2278 t
= make_node (INTEGER_TYPE
);
2279 TYPE_NAME (t
) = get_identifier ("bit_size_type");
2280 /* We do want to use bitsizetype's cache, as we will be replacing that
2282 TYPE_CACHED_VALUES (t
) = TYPE_CACHED_VALUES (bitsizetype
);
2283 TYPE_CACHED_VALUES_P (t
) = TYPE_CACHED_VALUES_P (bitsizetype
);
2284 TYPE_PRECISION (t
) = precision
;
2285 TYPE_UID (t
) = TYPE_UID (bitsizetype
);
2286 TYPE_IS_SIZETYPE (t
) = 1;
2288 /* Replace our original stub bitsizetype. */
2289 memcpy (bitsizetype
, t
, tree_size (bitsizetype
));
2290 TYPE_MAIN_VARIANT (bitsizetype
) = bitsizetype
;
2291 TYPE_CANONICAL (bitsizetype
) = bitsizetype
;
2293 if (TYPE_UNSIGNED (type
))
2295 fixup_unsigned_type (bitsizetype
);
2296 ssizetype
= make_signed_type (oprecision
);
2297 TYPE_IS_SIZETYPE (ssizetype
) = 1;
2298 sbitsizetype
= make_signed_type (precision
);
2299 TYPE_IS_SIZETYPE (sbitsizetype
) = 1;
2303 fixup_signed_type (bitsizetype
);
2304 ssizetype
= sizetype
;
2305 sbitsizetype
= bitsizetype
;
2308 /* If SIZETYPE is unsigned, we need to fix TYPE_MAX_VALUE so that
2309 it is sign extended in a way consistent with force_fit_type. */
2310 if (TYPE_UNSIGNED (type
))
2312 tree orig_max
, new_max
;
2314 orig_max
= TYPE_MAX_VALUE (sizetype
);
2316 /* Build a new node with the same values, but a different type.
2317 Sign extend it to ensure consistency. */
2318 new_max
= build_int_cst_wide_type (sizetype
,
2319 TREE_INT_CST_LOW (orig_max
),
2320 TREE_INT_CST_HIGH (orig_max
));
2321 TYPE_MAX_VALUE (sizetype
) = new_max
;
2325 /* TYPE is an integral type, i.e., an INTEGRAL_TYPE, ENUMERAL_TYPE
2326 or BOOLEAN_TYPE. Set TYPE_MIN_VALUE and TYPE_MAX_VALUE
2327 for TYPE, based on the PRECISION and whether or not the TYPE
2328 IS_UNSIGNED. PRECISION need not correspond to a width supported
2329 natively by the hardware; for example, on a machine with 8-bit,
2330 16-bit, and 32-bit register modes, PRECISION might be 7, 23, or
2334 set_min_and_max_values_for_integral_type (tree type
,
2343 min_value
= build_int_cst (type
, 0);
2345 = build_int_cst_wide (type
, precision
- HOST_BITS_PER_WIDE_INT
>= 0
2347 : ((HOST_WIDE_INT
) 1 << precision
) - 1,
2348 precision
- HOST_BITS_PER_WIDE_INT
> 0
2349 ? ((unsigned HOST_WIDE_INT
) ~0
2350 >> (HOST_BITS_PER_WIDE_INT
2351 - (precision
- HOST_BITS_PER_WIDE_INT
)))
2357 = build_int_cst_wide (type
,
2358 (precision
- HOST_BITS_PER_WIDE_INT
> 0
2360 : (HOST_WIDE_INT
) (-1) << (precision
- 1)),
2361 (((HOST_WIDE_INT
) (-1)
2362 << (precision
- HOST_BITS_PER_WIDE_INT
- 1 > 0
2363 ? precision
- HOST_BITS_PER_WIDE_INT
- 1
2366 = build_int_cst_wide (type
,
2367 (precision
- HOST_BITS_PER_WIDE_INT
> 0
2369 : ((HOST_WIDE_INT
) 1 << (precision
- 1)) - 1),
2370 (precision
- HOST_BITS_PER_WIDE_INT
- 1 > 0
2371 ? (((HOST_WIDE_INT
) 1
2372 << (precision
- HOST_BITS_PER_WIDE_INT
- 1))) - 1
2376 TYPE_MIN_VALUE (type
) = min_value
;
2377 TYPE_MAX_VALUE (type
) = max_value
;
2380 /* Set the extreme values of TYPE based on its precision in bits,
2381 then lay it out. Used when make_signed_type won't do
2382 because the tree code is not INTEGER_TYPE.
2383 E.g. for Pascal, when the -fsigned-char option is given. */
2386 fixup_signed_type (tree type
)
2388 int precision
= TYPE_PRECISION (type
);
2390 /* We can not represent properly constants greater then
2391 2 * HOST_BITS_PER_WIDE_INT, still we need the types
2392 as they are used by i386 vector extensions and friends. */
2393 if (precision
> HOST_BITS_PER_WIDE_INT
* 2)
2394 precision
= HOST_BITS_PER_WIDE_INT
* 2;
2396 set_min_and_max_values_for_integral_type (type
, precision
,
2397 /*is_unsigned=*/false);
2399 /* Lay out the type: set its alignment, size, etc. */
2403 /* Set the extreme values of TYPE based on its precision in bits,
2404 then lay it out. This is used both in `make_unsigned_type'
2405 and for enumeral types. */
2408 fixup_unsigned_type (tree type
)
2410 int precision
= TYPE_PRECISION (type
);
2412 /* We can not represent properly constants greater then
2413 2 * HOST_BITS_PER_WIDE_INT, still we need the types
2414 as they are used by i386 vector extensions and friends. */
2415 if (precision
> HOST_BITS_PER_WIDE_INT
* 2)
2416 precision
= HOST_BITS_PER_WIDE_INT
* 2;
2418 TYPE_UNSIGNED (type
) = 1;
2420 set_min_and_max_values_for_integral_type (type
, precision
,
2421 /*is_unsigned=*/true);
2423 /* Lay out the type: set its alignment, size, etc. */
2427 /* Find the best machine mode to use when referencing a bit field of length
2428 BITSIZE bits starting at BITPOS.
2430 The underlying object is known to be aligned to a boundary of ALIGN bits.
2431 If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
2432 larger than LARGEST_MODE (usually SImode).
2434 If no mode meets all these conditions, we return VOIDmode.
2436 If VOLATILEP is false and SLOW_BYTE_ACCESS is false, we return the
2437 smallest mode meeting these conditions.
2439 If VOLATILEP is false and SLOW_BYTE_ACCESS is true, we return the
2440 largest mode (but a mode no wider than UNITS_PER_WORD) that meets
2443 If VOLATILEP is true the narrow_volatile_bitfields target hook is used to
2444 decide which of the above modes should be used. */
2447 get_best_mode (int bitsize
, int bitpos
, unsigned int align
,
2448 enum machine_mode largest_mode
, int volatilep
)
2450 enum machine_mode mode
;
2451 unsigned int unit
= 0;
2453 /* Find the narrowest integer mode that contains the bit field. */
2454 for (mode
= GET_CLASS_NARROWEST_MODE (MODE_INT
); mode
!= VOIDmode
;
2455 mode
= GET_MODE_WIDER_MODE (mode
))
2457 unit
= GET_MODE_BITSIZE (mode
);
2458 if ((bitpos
% unit
) + bitsize
<= unit
)
2462 if (mode
== VOIDmode
2463 /* It is tempting to omit the following line
2464 if STRICT_ALIGNMENT is true.
2465 But that is incorrect, since if the bitfield uses part of 3 bytes
2466 and we use a 4-byte mode, we could get a spurious segv
2467 if the extra 4th byte is past the end of memory.
2468 (Though at least one Unix compiler ignores this problem:
2469 that on the Sequent 386 machine. */
2470 || MIN (unit
, BIGGEST_ALIGNMENT
) > align
2471 || (largest_mode
!= VOIDmode
&& unit
> GET_MODE_BITSIZE (largest_mode
)))
2474 if ((SLOW_BYTE_ACCESS
&& ! volatilep
)
2475 || (volatilep
&& !targetm
.narrow_volatile_bitfield ()))
2477 enum machine_mode wide_mode
= VOIDmode
, tmode
;
2479 for (tmode
= GET_CLASS_NARROWEST_MODE (MODE_INT
); tmode
!= VOIDmode
;
2480 tmode
= GET_MODE_WIDER_MODE (tmode
))
2482 unit
= GET_MODE_BITSIZE (tmode
);
2483 if (bitpos
/ unit
== (bitpos
+ bitsize
- 1) / unit
2484 && unit
<= BITS_PER_WORD
2485 && unit
<= MIN (align
, BIGGEST_ALIGNMENT
)
2486 && (largest_mode
== VOIDmode
2487 || unit
<= GET_MODE_BITSIZE (largest_mode
)))
2491 if (wide_mode
!= VOIDmode
)
2498 /* Gets minimal and maximal values for MODE (signed or unsigned depending on
2499 SIGN). The returned constants are made to be usable in TARGET_MODE. */
2502 get_mode_bounds (enum machine_mode mode
, int sign
,
2503 enum machine_mode target_mode
,
2504 rtx
*mmin
, rtx
*mmax
)
2506 unsigned size
= GET_MODE_BITSIZE (mode
);
2507 unsigned HOST_WIDE_INT min_val
, max_val
;
2509 gcc_assert (size
<= HOST_BITS_PER_WIDE_INT
);
2513 min_val
= -((unsigned HOST_WIDE_INT
) 1 << (size
- 1));
2514 max_val
= ((unsigned HOST_WIDE_INT
) 1 << (size
- 1)) - 1;
2519 max_val
= ((unsigned HOST_WIDE_INT
) 1 << (size
- 1) << 1) - 1;
2522 *mmin
= gen_int_mode (min_val
, target_mode
);
2523 *mmax
= gen_int_mode (max_val
, target_mode
);
2526 #include "gt-stor-layout.h"