1 /* C-compiler utilities for types and variables storage layout
2 Copyright (C) 1987-2017 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
23 #include "coretypes.h"
30 #include "stringpool.h"
34 #include "diagnostic-core.h"
35 #include "fold-const.h"
36 #include "stor-layout.h"
38 #include "print-tree.h"
39 #include "langhooks.h"
40 #include "tree-inline.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) stk_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
;
53 static tree
self_referential_size (tree
);
54 static void finalize_record_size (record_layout_info
);
55 static void finalize_type_size (tree
);
56 static void place_union_field (record_layout_info
, tree
);
57 static int excess_unit_span (HOST_WIDE_INT
, HOST_WIDE_INT
, HOST_WIDE_INT
,
59 extern void debug_rli (record_layout_info
);
61 /* Given a size SIZE that may not be a constant, return a SAVE_EXPR
62 to serve as the actual size-expression for a type or decl. */
65 variable_size (tree size
)
68 if (TREE_CONSTANT (size
))
71 /* If the size is self-referential, we can't make a SAVE_EXPR (see
72 save_expr for the rationale). But we can do something else. */
73 if (CONTAINS_PLACEHOLDER_P (size
))
74 return self_referential_size (size
);
76 /* If we are in the global binding level, we can't make a SAVE_EXPR
77 since it may end up being shared across functions, so it is up
78 to the front-end to deal with this case. */
79 if (lang_hooks
.decls
.global_bindings_p ())
82 return save_expr (size
);
85 /* An array of functions used for self-referential size computation. */
86 static GTY(()) vec
<tree
, va_gc
> *size_functions
;
88 /* Return true if T is a self-referential component reference. */
91 self_referential_component_ref_p (tree t
)
93 if (TREE_CODE (t
) != COMPONENT_REF
)
96 while (REFERENCE_CLASS_P (t
))
97 t
= TREE_OPERAND (t
, 0);
99 return (TREE_CODE (t
) == PLACEHOLDER_EXPR
);
102 /* Similar to copy_tree_r but do not copy component references involving
103 PLACEHOLDER_EXPRs. These nodes are spotted in find_placeholder_in_expr
104 and substituted in substitute_in_expr. */
107 copy_self_referential_tree_r (tree
*tp
, int *walk_subtrees
, void *data
)
109 enum tree_code code
= TREE_CODE (*tp
);
111 /* Stop at types, decls, constants like copy_tree_r. */
112 if (TREE_CODE_CLASS (code
) == tcc_type
113 || TREE_CODE_CLASS (code
) == tcc_declaration
114 || TREE_CODE_CLASS (code
) == tcc_constant
)
120 /* This is the pattern built in ada/make_aligning_type. */
121 else if (code
== ADDR_EXPR
122 && TREE_CODE (TREE_OPERAND (*tp
, 0)) == PLACEHOLDER_EXPR
)
128 /* Default case: the component reference. */
129 else if (self_referential_component_ref_p (*tp
))
135 /* We're not supposed to have them in self-referential size trees
136 because we wouldn't properly control when they are evaluated.
137 However, not creating superfluous SAVE_EXPRs requires accurate
138 tracking of readonly-ness all the way down to here, which we
139 cannot always guarantee in practice. So punt in this case. */
140 else if (code
== SAVE_EXPR
)
141 return error_mark_node
;
143 else if (code
== STATEMENT_LIST
)
146 return copy_tree_r (tp
, walk_subtrees
, data
);
149 /* Given a SIZE expression that is self-referential, return an equivalent
150 expression to serve as the actual size expression for a type. */
153 self_referential_size (tree size
)
155 static unsigned HOST_WIDE_INT fnno
= 0;
156 vec
<tree
> self_refs
= vNULL
;
157 tree param_type_list
= NULL
, param_decl_list
= NULL
;
158 tree t
, ref
, return_type
, fntype
, fnname
, fndecl
;
161 vec
<tree
, va_gc
> *args
= NULL
;
163 /* Do not factor out simple operations. */
164 t
= skip_simple_constant_arithmetic (size
);
165 if (TREE_CODE (t
) == CALL_EXPR
|| self_referential_component_ref_p (t
))
168 /* Collect the list of self-references in the expression. */
169 find_placeholder_in_expr (size
, &self_refs
);
170 gcc_assert (self_refs
.length () > 0);
172 /* Obtain a private copy of the expression. */
174 if (walk_tree (&t
, copy_self_referential_tree_r
, NULL
, NULL
) != NULL_TREE
)
178 /* Build the parameter and argument lists in parallel; also
179 substitute the former for the latter in the expression. */
180 vec_alloc (args
, self_refs
.length ());
181 FOR_EACH_VEC_ELT (self_refs
, i
, ref
)
183 tree subst
, param_name
, param_type
, param_decl
;
187 /* We shouldn't have true variables here. */
188 gcc_assert (TREE_READONLY (ref
));
191 /* This is the pattern built in ada/make_aligning_type. */
192 else if (TREE_CODE (ref
) == ADDR_EXPR
)
194 /* Default case: the component reference. */
196 subst
= TREE_OPERAND (ref
, 1);
198 sprintf (buf
, "p%d", i
);
199 param_name
= get_identifier (buf
);
200 param_type
= TREE_TYPE (ref
);
202 = build_decl (input_location
, PARM_DECL
, param_name
, param_type
);
203 DECL_ARG_TYPE (param_decl
) = param_type
;
204 DECL_ARTIFICIAL (param_decl
) = 1;
205 TREE_READONLY (param_decl
) = 1;
207 size
= substitute_in_expr (size
, subst
, param_decl
);
209 param_type_list
= tree_cons (NULL_TREE
, param_type
, param_type_list
);
210 param_decl_list
= chainon (param_decl
, param_decl_list
);
211 args
->quick_push (ref
);
214 self_refs
.release ();
216 /* Append 'void' to indicate that the number of parameters is fixed. */
217 param_type_list
= tree_cons (NULL_TREE
, void_type_node
, param_type_list
);
219 /* The 3 lists have been created in reverse order. */
220 param_type_list
= nreverse (param_type_list
);
221 param_decl_list
= nreverse (param_decl_list
);
223 /* Build the function type. */
224 return_type
= TREE_TYPE (size
);
225 fntype
= build_function_type (return_type
, param_type_list
);
227 /* Build the function declaration. */
228 sprintf (buf
, "SZ" HOST_WIDE_INT_PRINT_UNSIGNED
, fnno
++);
229 fnname
= get_file_function_name (buf
);
230 fndecl
= build_decl (input_location
, FUNCTION_DECL
, fnname
, fntype
);
231 for (t
= param_decl_list
; t
; t
= DECL_CHAIN (t
))
232 DECL_CONTEXT (t
) = fndecl
;
233 DECL_ARGUMENTS (fndecl
) = param_decl_list
;
235 = build_decl (input_location
, RESULT_DECL
, 0, return_type
);
236 DECL_CONTEXT (DECL_RESULT (fndecl
)) = fndecl
;
238 /* The function has been created by the compiler and we don't
239 want to emit debug info for it. */
240 DECL_ARTIFICIAL (fndecl
) = 1;
241 DECL_IGNORED_P (fndecl
) = 1;
243 /* It is supposed to be "const" and never throw. */
244 TREE_READONLY (fndecl
) = 1;
245 TREE_NOTHROW (fndecl
) = 1;
247 /* We want it to be inlined when this is deemed profitable, as
248 well as discarded if every call has been integrated. */
249 DECL_DECLARED_INLINE_P (fndecl
) = 1;
251 /* It is made up of a unique return statement. */
252 DECL_INITIAL (fndecl
) = make_node (BLOCK
);
253 BLOCK_SUPERCONTEXT (DECL_INITIAL (fndecl
)) = fndecl
;
254 t
= build2 (MODIFY_EXPR
, return_type
, DECL_RESULT (fndecl
), size
);
255 DECL_SAVED_TREE (fndecl
) = build1 (RETURN_EXPR
, void_type_node
, t
);
256 TREE_STATIC (fndecl
) = 1;
258 /* Put it onto the list of size functions. */
259 vec_safe_push (size_functions
, fndecl
);
261 /* Replace the original expression with a call to the size function. */
262 return build_call_expr_loc_vec (UNKNOWN_LOCATION
, fndecl
, args
);
265 /* Take, queue and compile all the size functions. It is essential that
266 the size functions be gimplified at the very end of the compilation
267 in order to guarantee transparent handling of self-referential sizes.
268 Otherwise the GENERIC inliner would not be able to inline them back
269 at each of their call sites, thus creating artificial non-constant
270 size expressions which would trigger nasty problems later on. */
273 finalize_size_functions (void)
278 for (i
= 0; size_functions
&& size_functions
->iterate (i
, &fndecl
); i
++)
280 allocate_struct_function (fndecl
, false);
282 dump_function (TDI_original
, fndecl
);
284 /* As these functions are used to describe the layout of variable-length
285 structures, debug info generation needs their implementation. */
286 debug_hooks
->size_function (fndecl
);
287 gimplify_function_tree (fndecl
);
288 cgraph_node::finalize_function (fndecl
, false);
291 vec_free (size_functions
);
294 /* Return the machine mode to use for a nonscalar of SIZE bits. The
295 mode must be in class MCLASS, and have exactly that many value bits;
296 it may have padding as well. If LIMIT is nonzero, modes of wider
297 than MAX_FIXED_MODE_SIZE will not be used. */
300 mode_for_size (unsigned int size
, enum mode_class mclass
, int limit
)
305 if (limit
&& size
> MAX_FIXED_MODE_SIZE
)
308 /* Get the first mode which has this size, in the specified class. */
309 FOR_EACH_MODE_IN_CLASS (mode
, mclass
)
310 if (GET_MODE_PRECISION (mode
) == size
)
313 if (mclass
== MODE_INT
|| mclass
== MODE_PARTIAL_INT
)
314 for (i
= 0; i
< NUM_INT_N_ENTS
; i
++)
315 if (int_n_data
[i
].bitsize
== size
316 && int_n_enabled_p
[i
])
317 return int_n_data
[i
].m
;
322 /* Similar, except passed a tree node. */
325 mode_for_size_tree (const_tree size
, enum mode_class mclass
, int limit
)
327 unsigned HOST_WIDE_INT uhwi
;
330 if (!tree_fits_uhwi_p (size
))
332 uhwi
= tree_to_uhwi (size
);
336 return mode_for_size (ui
, mclass
, limit
);
339 /* Similar, but never return BLKmode; return the narrowest mode that
340 contains at least the requested number of value bits. */
343 smallest_mode_for_size (unsigned int size
, enum mode_class mclass
)
345 machine_mode mode
= VOIDmode
;
348 /* Get the first mode which has at least this size, in the
350 FOR_EACH_MODE_IN_CLASS (mode
, mclass
)
351 if (GET_MODE_PRECISION (mode
) >= size
)
354 if (mclass
== MODE_INT
|| mclass
== MODE_PARTIAL_INT
)
355 for (i
= 0; i
< NUM_INT_N_ENTS
; i
++)
356 if (int_n_data
[i
].bitsize
>= size
357 && int_n_data
[i
].bitsize
< GET_MODE_PRECISION (mode
)
358 && int_n_enabled_p
[i
])
359 mode
= int_n_data
[i
].m
;
361 if (mode
== VOIDmode
)
367 /* Return an integer mode of exactly the same size as MODE, if one exists. */
370 int_mode_for_mode (machine_mode mode
)
372 switch (GET_MODE_CLASS (mode
))
375 case MODE_PARTIAL_INT
:
376 return as_a
<scalar_int_mode
> (mode
);
378 case MODE_COMPLEX_INT
:
379 case MODE_COMPLEX_FLOAT
:
381 case MODE_DECIMAL_FLOAT
:
382 case MODE_VECTOR_INT
:
383 case MODE_VECTOR_FLOAT
:
388 case MODE_VECTOR_FRACT
:
389 case MODE_VECTOR_ACCUM
:
390 case MODE_VECTOR_UFRACT
:
391 case MODE_VECTOR_UACCUM
:
392 case MODE_POINTER_BOUNDS
:
393 return int_mode_for_size (GET_MODE_BITSIZE (mode
), 0);
397 return opt_scalar_int_mode ();
407 /* Find a mode that can be used for efficient bitwise operations on MODE.
408 Return BLKmode if no such mode exists. */
411 bitwise_mode_for_mode (machine_mode mode
)
413 /* Quick exit if we already have a suitable mode. */
414 unsigned int bitsize
= GET_MODE_BITSIZE (mode
);
415 scalar_int_mode int_mode
;
416 if (is_a
<scalar_int_mode
> (mode
, &int_mode
)
417 && GET_MODE_BITSIZE (int_mode
) <= MAX_FIXED_MODE_SIZE
)
420 /* Reuse the sanity checks from int_mode_for_mode. */
421 gcc_checking_assert ((int_mode_for_mode (mode
), true));
423 /* Try to replace complex modes with complex modes. In general we
424 expect both components to be processed independently, so we only
425 care whether there is a register for the inner mode. */
426 if (COMPLEX_MODE_P (mode
))
428 machine_mode trial
= mode
;
429 if (GET_MODE_CLASS (mode
) != MODE_COMPLEX_INT
)
430 trial
= mode_for_size (bitsize
, MODE_COMPLEX_INT
, false);
432 && have_regs_of_mode
[GET_MODE_INNER (trial
)])
436 /* Try to replace vector modes with vector modes. Also try using vector
437 modes if an integer mode would be too big. */
438 if (VECTOR_MODE_P (mode
) || bitsize
> MAX_FIXED_MODE_SIZE
)
440 machine_mode trial
= mode
;
441 if (GET_MODE_CLASS (mode
) != MODE_VECTOR_INT
)
442 trial
= mode_for_size (bitsize
, MODE_VECTOR_INT
, 0);
444 && have_regs_of_mode
[trial
]
445 && targetm
.vector_mode_supported_p (trial
))
449 /* Otherwise fall back on integers while honoring MAX_FIXED_MODE_SIZE. */
450 return mode_for_size (bitsize
, MODE_INT
, true);
453 /* Find a type that can be used for efficient bitwise operations on MODE.
454 Return null if no such mode exists. */
457 bitwise_type_for_mode (machine_mode mode
)
459 mode
= bitwise_mode_for_mode (mode
);
463 unsigned int inner_size
= GET_MODE_UNIT_BITSIZE (mode
);
464 tree inner_type
= build_nonstandard_integer_type (inner_size
, true);
466 if (VECTOR_MODE_P (mode
))
467 return build_vector_type_for_mode (inner_type
, mode
);
469 if (COMPLEX_MODE_P (mode
))
470 return build_complex_type (inner_type
);
472 gcc_checking_assert (GET_MODE_INNER (mode
) == mode
);
476 /* Find a mode that is suitable for representing a vector with
477 NUNITS elements of mode INNERMODE. Returns BLKmode if there
478 is no suitable mode. */
481 mode_for_vector (scalar_mode innermode
, unsigned nunits
)
485 /* First, look for a supported vector type. */
486 if (SCALAR_FLOAT_MODE_P (innermode
))
487 mode
= MIN_MODE_VECTOR_FLOAT
;
488 else if (SCALAR_FRACT_MODE_P (innermode
))
489 mode
= MIN_MODE_VECTOR_FRACT
;
490 else if (SCALAR_UFRACT_MODE_P (innermode
))
491 mode
= MIN_MODE_VECTOR_UFRACT
;
492 else if (SCALAR_ACCUM_MODE_P (innermode
))
493 mode
= MIN_MODE_VECTOR_ACCUM
;
494 else if (SCALAR_UACCUM_MODE_P (innermode
))
495 mode
= MIN_MODE_VECTOR_UACCUM
;
497 mode
= MIN_MODE_VECTOR_INT
;
499 /* Do not check vector_mode_supported_p here. We'll do that
500 later in vector_type_mode. */
501 FOR_EACH_MODE_FROM (mode
, mode
)
502 if (GET_MODE_NUNITS (mode
) == nunits
503 && GET_MODE_INNER (mode
) == innermode
)
506 /* For integers, try mapping it to a same-sized scalar mode. */
508 && GET_MODE_CLASS (innermode
) == MODE_INT
)
510 unsigned int nbits
= nunits
* GET_MODE_BITSIZE (innermode
);
511 mode
= int_mode_for_size (nbits
, 0).else_blk ();
515 || (GET_MODE_CLASS (mode
) == MODE_INT
516 && !have_regs_of_mode
[mode
]))
522 /* Return the alignment of MODE. This will be bounded by 1 and
523 BIGGEST_ALIGNMENT. */
526 get_mode_alignment (machine_mode mode
)
528 return MIN (BIGGEST_ALIGNMENT
, MAX (1, mode_base_align
[mode
]*BITS_PER_UNIT
));
531 /* Return the natural mode of an array, given that it is SIZE bytes in
532 total and has elements of type ELEM_TYPE. */
535 mode_for_array (tree elem_type
, tree size
)
538 unsigned HOST_WIDE_INT int_size
, int_elem_size
;
541 /* One-element arrays get the component type's mode. */
542 elem_size
= TYPE_SIZE (elem_type
);
543 if (simple_cst_equal (size
, elem_size
))
544 return TYPE_MODE (elem_type
);
547 if (tree_fits_uhwi_p (size
) && tree_fits_uhwi_p (elem_size
))
549 int_size
= tree_to_uhwi (size
);
550 int_elem_size
= tree_to_uhwi (elem_size
);
551 if (int_elem_size
> 0
552 && int_size
% int_elem_size
== 0
553 && targetm
.array_mode_supported_p (TYPE_MODE (elem_type
),
554 int_size
/ int_elem_size
))
557 return mode_for_size_tree (size
, MODE_INT
, limit_p
);
560 /* Subroutine of layout_decl: Force alignment required for the data type.
561 But if the decl itself wants greater alignment, don't override that. */
564 do_type_align (tree type
, tree decl
)
566 if (TYPE_ALIGN (type
) > DECL_ALIGN (decl
))
568 SET_DECL_ALIGN (decl
, TYPE_ALIGN (type
));
569 if (TREE_CODE (decl
) == FIELD_DECL
)
570 DECL_USER_ALIGN (decl
) = TYPE_USER_ALIGN (type
);
572 if (TYPE_WARN_IF_NOT_ALIGN (type
) > DECL_WARN_IF_NOT_ALIGN (decl
))
573 SET_DECL_WARN_IF_NOT_ALIGN (decl
, TYPE_WARN_IF_NOT_ALIGN (type
));
576 /* Set the size, mode and alignment of a ..._DECL node.
577 TYPE_DECL does need this for C++.
578 Note that LABEL_DECL and CONST_DECL nodes do not need this,
579 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
580 Don't call layout_decl for them.
582 KNOWN_ALIGN is the amount of alignment we can assume this
583 decl has with no special effort. It is relevant only for FIELD_DECLs
584 and depends on the previous fields.
585 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
586 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
587 the record will be aligned to suit. */
590 layout_decl (tree decl
, unsigned int known_align
)
592 tree type
= TREE_TYPE (decl
);
593 enum tree_code code
= TREE_CODE (decl
);
595 location_t loc
= DECL_SOURCE_LOCATION (decl
);
597 if (code
== CONST_DECL
)
600 gcc_assert (code
== VAR_DECL
|| code
== PARM_DECL
|| code
== RESULT_DECL
601 || code
== TYPE_DECL
|| code
== FIELD_DECL
);
603 rtl
= DECL_RTL_IF_SET (decl
);
605 if (type
== error_mark_node
)
606 type
= void_type_node
;
608 /* Usually the size and mode come from the data type without change,
609 however, the front-end may set the explicit width of the field, so its
610 size may not be the same as the size of its type. This happens with
611 bitfields, of course (an `int' bitfield may be only 2 bits, say), but it
612 also happens with other fields. For example, the C++ front-end creates
613 zero-sized fields corresponding to empty base classes, and depends on
614 layout_type setting DECL_FIELD_BITPOS correctly for the field. Set the
615 size in bytes from the size in bits. If we have already set the mode,
616 don't set it again since we can be called twice for FIELD_DECLs. */
618 DECL_UNSIGNED (decl
) = TYPE_UNSIGNED (type
);
619 if (DECL_MODE (decl
) == VOIDmode
)
620 SET_DECL_MODE (decl
, TYPE_MODE (type
));
622 if (DECL_SIZE (decl
) == 0)
624 DECL_SIZE (decl
) = TYPE_SIZE (type
);
625 DECL_SIZE_UNIT (decl
) = TYPE_SIZE_UNIT (type
);
627 else if (DECL_SIZE_UNIT (decl
) == 0)
628 DECL_SIZE_UNIT (decl
)
629 = fold_convert_loc (loc
, sizetype
,
630 size_binop_loc (loc
, CEIL_DIV_EXPR
, DECL_SIZE (decl
),
633 if (code
!= FIELD_DECL
)
634 /* For non-fields, update the alignment from the type. */
635 do_type_align (type
, decl
);
637 /* For fields, it's a bit more complicated... */
639 bool old_user_align
= DECL_USER_ALIGN (decl
);
640 bool zero_bitfield
= false;
641 bool packed_p
= DECL_PACKED (decl
);
644 if (DECL_BIT_FIELD (decl
))
646 DECL_BIT_FIELD_TYPE (decl
) = type
;
648 /* A zero-length bit-field affects the alignment of the next
649 field. In essence such bit-fields are not influenced by
650 any packing due to #pragma pack or attribute packed. */
651 if (integer_zerop (DECL_SIZE (decl
))
652 && ! targetm
.ms_bitfield_layout_p (DECL_FIELD_CONTEXT (decl
)))
654 zero_bitfield
= true;
656 if (PCC_BITFIELD_TYPE_MATTERS
)
657 do_type_align (type
, decl
);
660 #ifdef EMPTY_FIELD_BOUNDARY
661 if (EMPTY_FIELD_BOUNDARY
> DECL_ALIGN (decl
))
663 SET_DECL_ALIGN (decl
, EMPTY_FIELD_BOUNDARY
);
664 DECL_USER_ALIGN (decl
) = 0;
670 /* See if we can use an ordinary integer mode for a bit-field.
671 Conditions are: a fixed size that is correct for another mode,
672 occupying a complete byte or bytes on proper boundary. */
673 if (TYPE_SIZE (type
) != 0
674 && TREE_CODE (TYPE_SIZE (type
)) == INTEGER_CST
675 && GET_MODE_CLASS (TYPE_MODE (type
)) == MODE_INT
)
678 = mode_for_size_tree (DECL_SIZE (decl
), MODE_INT
, 1);
679 unsigned int xalign
= GET_MODE_ALIGNMENT (xmode
);
682 && !(xalign
> BITS_PER_UNIT
&& DECL_PACKED (decl
))
683 && (known_align
== 0 || known_align
>= xalign
))
685 SET_DECL_ALIGN (decl
, MAX (xalign
, DECL_ALIGN (decl
)));
686 SET_DECL_MODE (decl
, xmode
);
687 DECL_BIT_FIELD (decl
) = 0;
691 /* Turn off DECL_BIT_FIELD if we won't need it set. */
692 if (TYPE_MODE (type
) == BLKmode
&& DECL_MODE (decl
) == BLKmode
693 && known_align
>= TYPE_ALIGN (type
)
694 && DECL_ALIGN (decl
) >= TYPE_ALIGN (type
))
695 DECL_BIT_FIELD (decl
) = 0;
697 else if (packed_p
&& DECL_USER_ALIGN (decl
))
698 /* Don't touch DECL_ALIGN. For other packed fields, go ahead and
699 round up; we'll reduce it again below. We want packing to
700 supersede USER_ALIGN inherited from the type, but defer to
701 alignment explicitly specified on the field decl. */;
703 do_type_align (type
, decl
);
705 /* If the field is packed and not explicitly aligned, give it the
706 minimum alignment. Note that do_type_align may set
707 DECL_USER_ALIGN, so we need to check old_user_align instead. */
710 SET_DECL_ALIGN (decl
, MIN (DECL_ALIGN (decl
), BITS_PER_UNIT
));
712 if (! packed_p
&& ! DECL_USER_ALIGN (decl
))
714 /* Some targets (i.e. i386, VMS) limit struct field alignment
715 to a lower boundary than alignment of variables unless
716 it was overridden by attribute aligned. */
717 #ifdef BIGGEST_FIELD_ALIGNMENT
718 SET_DECL_ALIGN (decl
, MIN (DECL_ALIGN (decl
),
719 (unsigned) BIGGEST_FIELD_ALIGNMENT
));
721 #ifdef ADJUST_FIELD_ALIGN
722 SET_DECL_ALIGN (decl
, ADJUST_FIELD_ALIGN (decl
, TREE_TYPE (decl
),
728 mfa
= initial_max_fld_align
* BITS_PER_UNIT
;
730 mfa
= maximum_field_alignment
;
731 /* Should this be controlled by DECL_USER_ALIGN, too? */
733 SET_DECL_ALIGN (decl
, MIN (DECL_ALIGN (decl
), mfa
));
736 /* Evaluate nonconstant size only once, either now or as soon as safe. */
737 if (DECL_SIZE (decl
) != 0 && TREE_CODE (DECL_SIZE (decl
)) != INTEGER_CST
)
738 DECL_SIZE (decl
) = variable_size (DECL_SIZE (decl
));
739 if (DECL_SIZE_UNIT (decl
) != 0
740 && TREE_CODE (DECL_SIZE_UNIT (decl
)) != INTEGER_CST
)
741 DECL_SIZE_UNIT (decl
) = variable_size (DECL_SIZE_UNIT (decl
));
743 /* If requested, warn about definitions of large data objects. */
745 && (code
== VAR_DECL
|| code
== PARM_DECL
)
746 && ! DECL_EXTERNAL (decl
))
748 tree size
= DECL_SIZE_UNIT (decl
);
750 if (size
!= 0 && TREE_CODE (size
) == INTEGER_CST
751 && compare_tree_int (size
, larger_than_size
) > 0)
753 int size_as_int
= TREE_INT_CST_LOW (size
);
755 if (compare_tree_int (size
, size_as_int
) == 0)
756 warning (OPT_Wlarger_than_
, "size of %q+D is %d bytes", decl
, size_as_int
);
758 warning (OPT_Wlarger_than_
, "size of %q+D is larger than %wd bytes",
759 decl
, larger_than_size
);
763 /* If the RTL was already set, update its mode and mem attributes. */
766 PUT_MODE (rtl
, DECL_MODE (decl
));
767 SET_DECL_RTL (decl
, 0);
769 set_mem_attributes (rtl
, decl
, 1);
770 SET_DECL_RTL (decl
, rtl
);
774 /* Given a VAR_DECL, PARM_DECL, RESULT_DECL, or FIELD_DECL, clears the
775 results of a previous call to layout_decl and calls it again. */
778 relayout_decl (tree decl
)
780 DECL_SIZE (decl
) = DECL_SIZE_UNIT (decl
) = 0;
781 SET_DECL_MODE (decl
, VOIDmode
);
782 if (!DECL_USER_ALIGN (decl
))
783 SET_DECL_ALIGN (decl
, 0);
784 if (DECL_RTL_SET_P (decl
))
785 SET_DECL_RTL (decl
, 0);
787 layout_decl (decl
, 0);
790 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
791 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
792 is to be passed to all other layout functions for this record. It is the
793 responsibility of the caller to call `free' for the storage returned.
794 Note that garbage collection is not permitted until we finish laying
798 start_record_layout (tree t
)
800 record_layout_info rli
= XNEW (struct record_layout_info_s
);
804 /* If the type has a minimum specified alignment (via an attribute
805 declaration, for example) use it -- otherwise, start with a
806 one-byte alignment. */
807 rli
->record_align
= MAX (BITS_PER_UNIT
, TYPE_ALIGN (t
));
808 rli
->unpacked_align
= rli
->record_align
;
809 rli
->offset_align
= MAX (rli
->record_align
, BIGGEST_ALIGNMENT
);
811 #ifdef STRUCTURE_SIZE_BOUNDARY
812 /* Packed structures don't need to have minimum size. */
813 if (! TYPE_PACKED (t
))
817 /* #pragma pack overrides STRUCTURE_SIZE_BOUNDARY. */
818 tmp
= (unsigned) STRUCTURE_SIZE_BOUNDARY
;
819 if (maximum_field_alignment
!= 0)
820 tmp
= MIN (tmp
, maximum_field_alignment
);
821 rli
->record_align
= MAX (rli
->record_align
, tmp
);
825 rli
->offset
= size_zero_node
;
826 rli
->bitpos
= bitsize_zero_node
;
828 rli
->pending_statics
= 0;
829 rli
->packed_maybe_necessary
= 0;
830 rli
->remaining_in_alignment
= 0;
835 /* Return the combined bit position for the byte offset OFFSET and the
838 These functions operate on byte and bit positions present in FIELD_DECLs
839 and assume that these expressions result in no (intermediate) overflow.
840 This assumption is necessary to fold the expressions as much as possible,
841 so as to avoid creating artificially variable-sized types in languages
842 supporting variable-sized types like Ada. */
845 bit_from_pos (tree offset
, tree bitpos
)
847 if (TREE_CODE (offset
) == PLUS_EXPR
)
848 offset
= size_binop (PLUS_EXPR
,
849 fold_convert (bitsizetype
, TREE_OPERAND (offset
, 0)),
850 fold_convert (bitsizetype
, TREE_OPERAND (offset
, 1)));
852 offset
= fold_convert (bitsizetype
, offset
);
853 return size_binop (PLUS_EXPR
, bitpos
,
854 size_binop (MULT_EXPR
, offset
, bitsize_unit_node
));
857 /* Return the combined truncated byte position for the byte offset OFFSET and
858 the bit position BITPOS. */
861 byte_from_pos (tree offset
, tree bitpos
)
864 if (TREE_CODE (bitpos
) == MULT_EXPR
865 && tree_int_cst_equal (TREE_OPERAND (bitpos
, 1), bitsize_unit_node
))
866 bytepos
= TREE_OPERAND (bitpos
, 0);
868 bytepos
= size_binop (TRUNC_DIV_EXPR
, bitpos
, bitsize_unit_node
);
869 return size_binop (PLUS_EXPR
, offset
, fold_convert (sizetype
, bytepos
));
872 /* Split the bit position POS into a byte offset *POFFSET and a bit
873 position *PBITPOS with the byte offset aligned to OFF_ALIGN bits. */
876 pos_from_bit (tree
*poffset
, tree
*pbitpos
, unsigned int off_align
,
879 tree toff_align
= bitsize_int (off_align
);
880 if (TREE_CODE (pos
) == MULT_EXPR
881 && tree_int_cst_equal (TREE_OPERAND (pos
, 1), toff_align
))
883 *poffset
= size_binop (MULT_EXPR
,
884 fold_convert (sizetype
, TREE_OPERAND (pos
, 0)),
885 size_int (off_align
/ BITS_PER_UNIT
));
886 *pbitpos
= bitsize_zero_node
;
890 *poffset
= size_binop (MULT_EXPR
,
891 fold_convert (sizetype
,
892 size_binop (FLOOR_DIV_EXPR
, pos
,
894 size_int (off_align
/ BITS_PER_UNIT
));
895 *pbitpos
= size_binop (FLOOR_MOD_EXPR
, pos
, toff_align
);
899 /* Given a pointer to bit and byte offsets and an offset alignment,
900 normalize the offsets so they are within the alignment. */
903 normalize_offset (tree
*poffset
, tree
*pbitpos
, unsigned int off_align
)
905 /* If the bit position is now larger than it should be, adjust it
907 if (compare_tree_int (*pbitpos
, off_align
) >= 0)
910 pos_from_bit (&offset
, &bitpos
, off_align
, *pbitpos
);
911 *poffset
= size_binop (PLUS_EXPR
, *poffset
, offset
);
916 /* Print debugging information about the information in RLI. */
919 debug_rli (record_layout_info rli
)
921 print_node_brief (stderr
, "type", rli
->t
, 0);
922 print_node_brief (stderr
, "\noffset", rli
->offset
, 0);
923 print_node_brief (stderr
, " bitpos", rli
->bitpos
, 0);
925 fprintf (stderr
, "\naligns: rec = %u, unpack = %u, off = %u\n",
926 rli
->record_align
, rli
->unpacked_align
,
929 /* The ms_struct code is the only that uses this. */
930 if (targetm
.ms_bitfield_layout_p (rli
->t
))
931 fprintf (stderr
, "remaining in alignment = %u\n", rli
->remaining_in_alignment
);
933 if (rli
->packed_maybe_necessary
)
934 fprintf (stderr
, "packed may be necessary\n");
936 if (!vec_safe_is_empty (rli
->pending_statics
))
938 fprintf (stderr
, "pending statics:\n");
939 debug_vec_tree (rli
->pending_statics
);
943 /* Given an RLI with a possibly-incremented BITPOS, adjust OFFSET and
944 BITPOS if necessary to keep BITPOS below OFFSET_ALIGN. */
947 normalize_rli (record_layout_info rli
)
949 normalize_offset (&rli
->offset
, &rli
->bitpos
, rli
->offset_align
);
952 /* Returns the size in bytes allocated so far. */
955 rli_size_unit_so_far (record_layout_info rli
)
957 return byte_from_pos (rli
->offset
, rli
->bitpos
);
960 /* Returns the size in bits allocated so far. */
963 rli_size_so_far (record_layout_info rli
)
965 return bit_from_pos (rli
->offset
, rli
->bitpos
);
968 /* FIELD is about to be added to RLI->T. The alignment (in bits) of
969 the next available location within the record is given by KNOWN_ALIGN.
970 Update the variable alignment fields in RLI, and return the alignment
971 to give the FIELD. */
974 update_alignment_for_field (record_layout_info rli
, tree field
,
975 unsigned int known_align
)
977 /* The alignment required for FIELD. */
978 unsigned int desired_align
;
979 /* The type of this field. */
980 tree type
= TREE_TYPE (field
);
981 /* True if the field was explicitly aligned by the user. */
985 /* Do not attempt to align an ERROR_MARK node */
986 if (TREE_CODE (type
) == ERROR_MARK
)
989 /* Lay out the field so we know what alignment it needs. */
990 layout_decl (field
, known_align
);
991 desired_align
= DECL_ALIGN (field
);
992 user_align
= DECL_USER_ALIGN (field
);
994 is_bitfield
= (type
!= error_mark_node
995 && DECL_BIT_FIELD_TYPE (field
)
996 && ! integer_zerop (TYPE_SIZE (type
)));
998 /* Record must have at least as much alignment as any field.
999 Otherwise, the alignment of the field within the record is
1001 if (targetm
.ms_bitfield_layout_p (rli
->t
))
1003 /* Here, the alignment of the underlying type of a bitfield can
1004 affect the alignment of a record; even a zero-sized field
1005 can do this. The alignment should be to the alignment of
1006 the type, except that for zero-size bitfields this only
1007 applies if there was an immediately prior, nonzero-size
1008 bitfield. (That's the way it is, experimentally.) */
1009 if ((!is_bitfield
&& !DECL_PACKED (field
))
1010 || ((DECL_SIZE (field
) == NULL_TREE
1011 || !integer_zerop (DECL_SIZE (field
)))
1012 ? !DECL_PACKED (field
)
1014 && DECL_BIT_FIELD_TYPE (rli
->prev_field
)
1015 && ! integer_zerop (DECL_SIZE (rli
->prev_field
)))))
1017 unsigned int type_align
= TYPE_ALIGN (type
);
1018 type_align
= MAX (type_align
, desired_align
);
1019 if (maximum_field_alignment
!= 0)
1020 type_align
= MIN (type_align
, maximum_field_alignment
);
1021 rli
->record_align
= MAX (rli
->record_align
, type_align
);
1022 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
1025 else if (is_bitfield
&& PCC_BITFIELD_TYPE_MATTERS
)
1027 /* Named bit-fields cause the entire structure to have the
1028 alignment implied by their type. Some targets also apply the same
1029 rules to unnamed bitfields. */
1030 if (DECL_NAME (field
) != 0
1031 || targetm
.align_anon_bitfield ())
1033 unsigned int type_align
= TYPE_ALIGN (type
);
1035 #ifdef ADJUST_FIELD_ALIGN
1036 if (! TYPE_USER_ALIGN (type
))
1037 type_align
= ADJUST_FIELD_ALIGN (field
, type
, type_align
);
1040 /* Targets might chose to handle unnamed and hence possibly
1041 zero-width bitfield. Those are not influenced by #pragmas
1042 or packed attributes. */
1043 if (integer_zerop (DECL_SIZE (field
)))
1045 if (initial_max_fld_align
)
1046 type_align
= MIN (type_align
,
1047 initial_max_fld_align
* BITS_PER_UNIT
);
1049 else if (maximum_field_alignment
!= 0)
1050 type_align
= MIN (type_align
, maximum_field_alignment
);
1051 else if (DECL_PACKED (field
))
1052 type_align
= MIN (type_align
, BITS_PER_UNIT
);
1054 /* The alignment of the record is increased to the maximum
1055 of the current alignment, the alignment indicated on the
1056 field (i.e., the alignment specified by an __aligned__
1057 attribute), and the alignment indicated by the type of
1059 rli
->record_align
= MAX (rli
->record_align
, desired_align
);
1060 rli
->record_align
= MAX (rli
->record_align
, type_align
);
1063 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
1064 user_align
|= TYPE_USER_ALIGN (type
);
1069 rli
->record_align
= MAX (rli
->record_align
, desired_align
);
1070 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
1073 TYPE_USER_ALIGN (rli
->t
) |= user_align
;
1075 return desired_align
;
1078 /* Issue a warning if the record alignment, RECORD_ALIGN, is less than
1079 the field alignment of FIELD or FIELD isn't aligned. */
1082 handle_warn_if_not_align (tree field
, unsigned int record_align
)
1084 tree type
= TREE_TYPE (field
);
1086 if (type
== error_mark_node
)
1089 unsigned int warn_if_not_align
= 0;
1093 if (warn_if_not_aligned
)
1095 warn_if_not_align
= DECL_WARN_IF_NOT_ALIGN (field
);
1096 if (!warn_if_not_align
)
1097 warn_if_not_align
= TYPE_WARN_IF_NOT_ALIGN (type
);
1098 if (warn_if_not_align
)
1099 opt_w
= OPT_Wif_not_aligned
;
1102 if (!warn_if_not_align
1103 && warn_packed_not_aligned
1104 && TYPE_USER_ALIGN (type
))
1106 warn_if_not_align
= TYPE_ALIGN (type
);
1107 opt_w
= OPT_Wpacked_not_aligned
;
1110 if (!warn_if_not_align
)
1113 tree context
= DECL_CONTEXT (field
);
1115 warn_if_not_align
/= BITS_PER_UNIT
;
1116 record_align
/= BITS_PER_UNIT
;
1117 if ((record_align
% warn_if_not_align
) != 0)
1118 warning (opt_w
, "alignment %u of %qT is less than %u",
1119 record_align
, context
, warn_if_not_align
);
1121 unsigned HOST_WIDE_INT off
1122 = (tree_to_uhwi (DECL_FIELD_OFFSET (field
))
1123 + tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field
)) / BITS_PER_UNIT
);
1124 if ((off
% warn_if_not_align
) != 0)
1125 warning (opt_w
, "%q+D offset %wu in %qT isn't aligned to %u",
1126 field
, off
, context
, warn_if_not_align
);
1129 /* Called from place_field to handle unions. */
1132 place_union_field (record_layout_info rli
, tree field
)
1134 update_alignment_for_field (rli
, field
, /*known_align=*/0);
1136 DECL_FIELD_OFFSET (field
) = size_zero_node
;
1137 DECL_FIELD_BIT_OFFSET (field
) = bitsize_zero_node
;
1138 SET_DECL_OFFSET_ALIGN (field
, BIGGEST_ALIGNMENT
);
1139 handle_warn_if_not_align (field
, rli
->record_align
);
1141 /* If this is an ERROR_MARK return *after* having set the
1142 field at the start of the union. This helps when parsing
1144 if (TREE_CODE (TREE_TYPE (field
)) == ERROR_MARK
)
1147 if (AGGREGATE_TYPE_P (TREE_TYPE (field
))
1148 && TYPE_TYPELESS_STORAGE (TREE_TYPE (field
)))
1149 TYPE_TYPELESS_STORAGE (rli
->t
) = 1;
1151 /* We assume the union's size will be a multiple of a byte so we don't
1152 bother with BITPOS. */
1153 if (TREE_CODE (rli
->t
) == UNION_TYPE
)
1154 rli
->offset
= size_binop (MAX_EXPR
, rli
->offset
, DECL_SIZE_UNIT (field
));
1155 else if (TREE_CODE (rli
->t
) == QUAL_UNION_TYPE
)
1156 rli
->offset
= fold_build3 (COND_EXPR
, sizetype
, DECL_QUALIFIER (field
),
1157 DECL_SIZE_UNIT (field
), rli
->offset
);
1160 /* A bitfield of SIZE with a required access alignment of ALIGN is allocated
1161 at BYTE_OFFSET / BIT_OFFSET. Return nonzero if the field would span more
1162 units of alignment than the underlying TYPE. */
1164 excess_unit_span (HOST_WIDE_INT byte_offset
, HOST_WIDE_INT bit_offset
,
1165 HOST_WIDE_INT size
, HOST_WIDE_INT align
, tree type
)
1167 /* Note that the calculation of OFFSET might overflow; we calculate it so
1168 that we still get the right result as long as ALIGN is a power of two. */
1169 unsigned HOST_WIDE_INT offset
= byte_offset
* BITS_PER_UNIT
+ bit_offset
;
1171 offset
= offset
% align
;
1172 return ((offset
+ size
+ align
- 1) / align
1173 > tree_to_uhwi (TYPE_SIZE (type
)) / align
);
1176 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
1177 is a FIELD_DECL to be added after those fields already present in
1178 T. (FIELD is not actually added to the TYPE_FIELDS list here;
1179 callers that desire that behavior must manually perform that step.) */
1182 place_field (record_layout_info rli
, tree field
)
1184 /* The alignment required for FIELD. */
1185 unsigned int desired_align
;
1186 /* The alignment FIELD would have if we just dropped it into the
1187 record as it presently stands. */
1188 unsigned int known_align
;
1189 unsigned int actual_align
;
1190 /* The type of this field. */
1191 tree type
= TREE_TYPE (field
);
1193 gcc_assert (TREE_CODE (field
) != ERROR_MARK
);
1195 /* If FIELD is static, then treat it like a separate variable, not
1196 really like a structure field. If it is a FUNCTION_DECL, it's a
1197 method. In both cases, all we do is lay out the decl, and we do
1198 it *after* the record is laid out. */
1201 vec_safe_push (rli
->pending_statics
, field
);
1205 /* Enumerators and enum types which are local to this class need not
1206 be laid out. Likewise for initialized constant fields. */
1207 else if (TREE_CODE (field
) != FIELD_DECL
)
1210 /* Unions are laid out very differently than records, so split
1211 that code off to another function. */
1212 else if (TREE_CODE (rli
->t
) != RECORD_TYPE
)
1214 place_union_field (rli
, field
);
1218 else if (TREE_CODE (type
) == ERROR_MARK
)
1220 /* Place this field at the current allocation position, so we
1221 maintain monotonicity. */
1222 DECL_FIELD_OFFSET (field
) = rli
->offset
;
1223 DECL_FIELD_BIT_OFFSET (field
) = rli
->bitpos
;
1224 SET_DECL_OFFSET_ALIGN (field
, rli
->offset_align
);
1225 handle_warn_if_not_align (field
, rli
->record_align
);
1229 if (AGGREGATE_TYPE_P (type
)
1230 && TYPE_TYPELESS_STORAGE (type
))
1231 TYPE_TYPELESS_STORAGE (rli
->t
) = 1;
1233 /* Work out the known alignment so far. Note that A & (-A) is the
1234 value of the least-significant bit in A that is one. */
1235 if (! integer_zerop (rli
->bitpos
))
1236 known_align
= least_bit_hwi (tree_to_uhwi (rli
->bitpos
));
1237 else if (integer_zerop (rli
->offset
))
1239 else if (tree_fits_uhwi_p (rli
->offset
))
1240 known_align
= (BITS_PER_UNIT
1241 * least_bit_hwi (tree_to_uhwi (rli
->offset
)));
1243 known_align
= rli
->offset_align
;
1245 desired_align
= update_alignment_for_field (rli
, field
, known_align
);
1246 if (known_align
== 0)
1247 known_align
= MAX (BIGGEST_ALIGNMENT
, rli
->record_align
);
1249 if (warn_packed
&& DECL_PACKED (field
))
1251 if (known_align
>= TYPE_ALIGN (type
))
1253 if (TYPE_ALIGN (type
) > desired_align
)
1255 if (STRICT_ALIGNMENT
)
1256 warning (OPT_Wattributes
, "packed attribute causes "
1257 "inefficient alignment for %q+D", field
);
1258 /* Don't warn if DECL_PACKED was set by the type. */
1259 else if (!TYPE_PACKED (rli
->t
))
1260 warning (OPT_Wattributes
, "packed attribute is "
1261 "unnecessary for %q+D", field
);
1265 rli
->packed_maybe_necessary
= 1;
1268 /* Does this field automatically have alignment it needs by virtue
1269 of the fields that precede it and the record's own alignment? */
1270 if (known_align
< desired_align
)
1272 /* No, we need to skip space before this field.
1273 Bump the cumulative size to multiple of field alignment. */
1275 if (!targetm
.ms_bitfield_layout_p (rli
->t
)
1276 && DECL_SOURCE_LOCATION (field
) != BUILTINS_LOCATION
)
1277 warning (OPT_Wpadded
, "padding struct to align %q+D", field
);
1279 /* If the alignment is still within offset_align, just align
1280 the bit position. */
1281 if (desired_align
< rli
->offset_align
)
1282 rli
->bitpos
= round_up (rli
->bitpos
, desired_align
);
1285 /* First adjust OFFSET by the partial bits, then align. */
1287 = size_binop (PLUS_EXPR
, rli
->offset
,
1288 fold_convert (sizetype
,
1289 size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
1290 bitsize_unit_node
)));
1291 rli
->bitpos
= bitsize_zero_node
;
1293 rli
->offset
= round_up (rli
->offset
, desired_align
/ BITS_PER_UNIT
);
1296 if (! TREE_CONSTANT (rli
->offset
))
1297 rli
->offset_align
= desired_align
;
1298 if (targetm
.ms_bitfield_layout_p (rli
->t
))
1299 rli
->prev_field
= NULL
;
1302 /* Handle compatibility with PCC. Note that if the record has any
1303 variable-sized fields, we need not worry about compatibility. */
1304 if (PCC_BITFIELD_TYPE_MATTERS
1305 && ! targetm
.ms_bitfield_layout_p (rli
->t
)
1306 && TREE_CODE (field
) == FIELD_DECL
1307 && type
!= error_mark_node
1308 && DECL_BIT_FIELD (field
)
1309 && (! DECL_PACKED (field
)
1310 /* Enter for these packed fields only to issue a warning. */
1311 || TYPE_ALIGN (type
) <= BITS_PER_UNIT
)
1312 && maximum_field_alignment
== 0
1313 && ! integer_zerop (DECL_SIZE (field
))
1314 && tree_fits_uhwi_p (DECL_SIZE (field
))
1315 && tree_fits_uhwi_p (rli
->offset
)
1316 && tree_fits_uhwi_p (TYPE_SIZE (type
)))
1318 unsigned int type_align
= TYPE_ALIGN (type
);
1319 tree dsize
= DECL_SIZE (field
);
1320 HOST_WIDE_INT field_size
= tree_to_uhwi (dsize
);
1321 HOST_WIDE_INT offset
= tree_to_uhwi (rli
->offset
);
1322 HOST_WIDE_INT bit_offset
= tree_to_shwi (rli
->bitpos
);
1324 #ifdef ADJUST_FIELD_ALIGN
1325 if (! TYPE_USER_ALIGN (type
))
1326 type_align
= ADJUST_FIELD_ALIGN (field
, type
, type_align
);
1329 /* A bit field may not span more units of alignment of its type
1330 than its type itself. Advance to next boundary if necessary. */
1331 if (excess_unit_span (offset
, bit_offset
, field_size
, type_align
, type
))
1333 if (DECL_PACKED (field
))
1335 if (warn_packed_bitfield_compat
== 1)
1338 "offset of packed bit-field %qD has changed in GCC 4.4",
1342 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1345 if (! DECL_PACKED (field
))
1346 TYPE_USER_ALIGN (rli
->t
) |= TYPE_USER_ALIGN (type
);
1348 SET_TYPE_WARN_IF_NOT_ALIGN (rli
->t
,
1349 TYPE_WARN_IF_NOT_ALIGN (type
));
1352 #ifdef BITFIELD_NBYTES_LIMITED
1353 if (BITFIELD_NBYTES_LIMITED
1354 && ! targetm
.ms_bitfield_layout_p (rli
->t
)
1355 && TREE_CODE (field
) == FIELD_DECL
1356 && type
!= error_mark_node
1357 && DECL_BIT_FIELD_TYPE (field
)
1358 && ! DECL_PACKED (field
)
1359 && ! integer_zerop (DECL_SIZE (field
))
1360 && tree_fits_uhwi_p (DECL_SIZE (field
))
1361 && tree_fits_uhwi_p (rli
->offset
)
1362 && tree_fits_uhwi_p (TYPE_SIZE (type
)))
1364 unsigned int type_align
= TYPE_ALIGN (type
);
1365 tree dsize
= DECL_SIZE (field
);
1366 HOST_WIDE_INT field_size
= tree_to_uhwi (dsize
);
1367 HOST_WIDE_INT offset
= tree_to_uhwi (rli
->offset
);
1368 HOST_WIDE_INT bit_offset
= tree_to_shwi (rli
->bitpos
);
1370 #ifdef ADJUST_FIELD_ALIGN
1371 if (! TYPE_USER_ALIGN (type
))
1372 type_align
= ADJUST_FIELD_ALIGN (field
, type
, type_align
);
1375 if (maximum_field_alignment
!= 0)
1376 type_align
= MIN (type_align
, maximum_field_alignment
);
1377 /* ??? This test is opposite the test in the containing if
1378 statement, so this code is unreachable currently. */
1379 else if (DECL_PACKED (field
))
1380 type_align
= MIN (type_align
, BITS_PER_UNIT
);
1382 /* A bit field may not span the unit of alignment of its type.
1383 Advance to next boundary if necessary. */
1384 if (excess_unit_span (offset
, bit_offset
, field_size
, type_align
, type
))
1385 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1387 TYPE_USER_ALIGN (rli
->t
) |= TYPE_USER_ALIGN (type
);
1388 SET_TYPE_WARN_IF_NOT_ALIGN (rli
->t
,
1389 TYPE_WARN_IF_NOT_ALIGN (type
));
1393 /* See the docs for TARGET_MS_BITFIELD_LAYOUT_P for details.
1395 When a bit field is inserted into a packed record, the whole
1396 size of the underlying type is used by one or more same-size
1397 adjacent bitfields. (That is, if its long:3, 32 bits is
1398 used in the record, and any additional adjacent long bitfields are
1399 packed into the same chunk of 32 bits. However, if the size
1400 changes, a new field of that size is allocated.) In an unpacked
1401 record, this is the same as using alignment, but not equivalent
1404 Note: for compatibility, we use the type size, not the type alignment
1405 to determine alignment, since that matches the documentation */
1407 if (targetm
.ms_bitfield_layout_p (rli
->t
))
1409 tree prev_saved
= rli
->prev_field
;
1410 tree prev_type
= prev_saved
? DECL_BIT_FIELD_TYPE (prev_saved
) : NULL
;
1412 /* This is a bitfield if it exists. */
1413 if (rli
->prev_field
)
1415 /* If both are bitfields, nonzero, and the same size, this is
1416 the middle of a run. Zero declared size fields are special
1417 and handled as "end of run". (Note: it's nonzero declared
1418 size, but equal type sizes!) (Since we know that both
1419 the current and previous fields are bitfields by the
1420 time we check it, DECL_SIZE must be present for both.) */
1421 if (DECL_BIT_FIELD_TYPE (field
)
1422 && !integer_zerop (DECL_SIZE (field
))
1423 && !integer_zerop (DECL_SIZE (rli
->prev_field
))
1424 && tree_fits_shwi_p (DECL_SIZE (rli
->prev_field
))
1425 && tree_fits_uhwi_p (TYPE_SIZE (type
))
1426 && simple_cst_equal (TYPE_SIZE (type
), TYPE_SIZE (prev_type
)))
1428 /* We're in the middle of a run of equal type size fields; make
1429 sure we realign if we run out of bits. (Not decl size,
1431 HOST_WIDE_INT bitsize
= tree_to_uhwi (DECL_SIZE (field
));
1433 if (rli
->remaining_in_alignment
< bitsize
)
1435 HOST_WIDE_INT typesize
= tree_to_uhwi (TYPE_SIZE (type
));
1437 /* out of bits; bump up to next 'word'. */
1439 = size_binop (PLUS_EXPR
, rli
->bitpos
,
1440 bitsize_int (rli
->remaining_in_alignment
));
1441 rli
->prev_field
= field
;
1442 if (typesize
< bitsize
)
1443 rli
->remaining_in_alignment
= 0;
1445 rli
->remaining_in_alignment
= typesize
- bitsize
;
1448 rli
->remaining_in_alignment
-= bitsize
;
1452 /* End of a run: if leaving a run of bitfields of the same type
1453 size, we have to "use up" the rest of the bits of the type
1456 Compute the new position as the sum of the size for the prior
1457 type and where we first started working on that type.
1458 Note: since the beginning of the field was aligned then
1459 of course the end will be too. No round needed. */
1461 if (!integer_zerop (DECL_SIZE (rli
->prev_field
)))
1464 = size_binop (PLUS_EXPR
, rli
->bitpos
,
1465 bitsize_int (rli
->remaining_in_alignment
));
1468 /* We "use up" size zero fields; the code below should behave
1469 as if the prior field was not a bitfield. */
1472 /* Cause a new bitfield to be captured, either this time (if
1473 currently a bitfield) or next time we see one. */
1474 if (!DECL_BIT_FIELD_TYPE (field
)
1475 || integer_zerop (DECL_SIZE (field
)))
1476 rli
->prev_field
= NULL
;
1479 normalize_rli (rli
);
1482 /* If we're starting a new run of same type size bitfields
1483 (or a run of non-bitfields), set up the "first of the run"
1486 That is, if the current field is not a bitfield, or if there
1487 was a prior bitfield the type sizes differ, or if there wasn't
1488 a prior bitfield the size of the current field is nonzero.
1490 Note: we must be sure to test ONLY the type size if there was
1491 a prior bitfield and ONLY for the current field being zero if
1494 if (!DECL_BIT_FIELD_TYPE (field
)
1495 || (prev_saved
!= NULL
1496 ? !simple_cst_equal (TYPE_SIZE (type
), TYPE_SIZE (prev_type
))
1497 : !integer_zerop (DECL_SIZE (field
)) ))
1499 /* Never smaller than a byte for compatibility. */
1500 unsigned int type_align
= BITS_PER_UNIT
;
1502 /* (When not a bitfield), we could be seeing a flex array (with
1503 no DECL_SIZE). Since we won't be using remaining_in_alignment
1504 until we see a bitfield (and come by here again) we just skip
1506 if (DECL_SIZE (field
) != NULL
1507 && tree_fits_uhwi_p (TYPE_SIZE (TREE_TYPE (field
)))
1508 && tree_fits_uhwi_p (DECL_SIZE (field
)))
1510 unsigned HOST_WIDE_INT bitsize
1511 = tree_to_uhwi (DECL_SIZE (field
));
1512 unsigned HOST_WIDE_INT typesize
1513 = tree_to_uhwi (TYPE_SIZE (TREE_TYPE (field
)));
1515 if (typesize
< bitsize
)
1516 rli
->remaining_in_alignment
= 0;
1518 rli
->remaining_in_alignment
= typesize
- bitsize
;
1521 /* Now align (conventionally) for the new type. */
1522 type_align
= TYPE_ALIGN (TREE_TYPE (field
));
1524 if (maximum_field_alignment
!= 0)
1525 type_align
= MIN (type_align
, maximum_field_alignment
);
1527 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1529 /* If we really aligned, don't allow subsequent bitfields
1531 rli
->prev_field
= NULL
;
1535 /* Offset so far becomes the position of this field after normalizing. */
1536 normalize_rli (rli
);
1537 DECL_FIELD_OFFSET (field
) = rli
->offset
;
1538 DECL_FIELD_BIT_OFFSET (field
) = rli
->bitpos
;
1539 SET_DECL_OFFSET_ALIGN (field
, rli
->offset_align
);
1540 handle_warn_if_not_align (field
, rli
->record_align
);
1542 /* Evaluate nonconstant offsets only once, either now or as soon as safe. */
1543 if (TREE_CODE (DECL_FIELD_OFFSET (field
)) != INTEGER_CST
)
1544 DECL_FIELD_OFFSET (field
) = variable_size (DECL_FIELD_OFFSET (field
));
1546 /* If this field ended up more aligned than we thought it would be (we
1547 approximate this by seeing if its position changed), lay out the field
1548 again; perhaps we can use an integral mode for it now. */
1549 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field
)))
1550 actual_align
= least_bit_hwi (tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field
)));
1551 else if (integer_zerop (DECL_FIELD_OFFSET (field
)))
1552 actual_align
= MAX (BIGGEST_ALIGNMENT
, rli
->record_align
);
1553 else if (tree_fits_uhwi_p (DECL_FIELD_OFFSET (field
)))
1554 actual_align
= (BITS_PER_UNIT
1555 * least_bit_hwi (tree_to_uhwi (DECL_FIELD_OFFSET (field
))));
1557 actual_align
= DECL_OFFSET_ALIGN (field
);
1558 /* ACTUAL_ALIGN is still the actual alignment *within the record* .
1559 store / extract bit field operations will check the alignment of the
1560 record against the mode of bit fields. */
1562 if (known_align
!= actual_align
)
1563 layout_decl (field
, actual_align
);
1565 if (rli
->prev_field
== NULL
&& DECL_BIT_FIELD_TYPE (field
))
1566 rli
->prev_field
= field
;
1568 /* Now add size of this field to the size of the record. If the size is
1569 not constant, treat the field as being a multiple of bytes and just
1570 adjust the offset, resetting the bit position. Otherwise, apportion the
1571 size amongst the bit position and offset. First handle the case of an
1572 unspecified size, which can happen when we have an invalid nested struct
1573 definition, such as struct j { struct j { int i; } }. The error message
1574 is printed in finish_struct. */
1575 if (DECL_SIZE (field
) == 0)
1577 else if (TREE_CODE (DECL_SIZE (field
)) != INTEGER_CST
1578 || TREE_OVERFLOW (DECL_SIZE (field
)))
1581 = size_binop (PLUS_EXPR
, rli
->offset
,
1582 fold_convert (sizetype
,
1583 size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
1584 bitsize_unit_node
)));
1586 = size_binop (PLUS_EXPR
, rli
->offset
, DECL_SIZE_UNIT (field
));
1587 rli
->bitpos
= bitsize_zero_node
;
1588 rli
->offset_align
= MIN (rli
->offset_align
, desired_align
);
1590 else if (targetm
.ms_bitfield_layout_p (rli
->t
))
1592 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
, DECL_SIZE (field
));
1594 /* If we ended a bitfield before the full length of the type then
1595 pad the struct out to the full length of the last type. */
1596 if ((DECL_CHAIN (field
) == NULL
1597 || TREE_CODE (DECL_CHAIN (field
)) != FIELD_DECL
)
1598 && DECL_BIT_FIELD_TYPE (field
)
1599 && !integer_zerop (DECL_SIZE (field
)))
1600 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
,
1601 bitsize_int (rli
->remaining_in_alignment
));
1603 normalize_rli (rli
);
1607 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
, DECL_SIZE (field
));
1608 normalize_rli (rli
);
1612 /* Assuming that all the fields have been laid out, this function uses
1613 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
1614 indicated by RLI. */
1617 finalize_record_size (record_layout_info rli
)
1619 tree unpadded_size
, unpadded_size_unit
;
1621 /* Now we want just byte and bit offsets, so set the offset alignment
1622 to be a byte and then normalize. */
1623 rli
->offset_align
= BITS_PER_UNIT
;
1624 normalize_rli (rli
);
1626 /* Determine the desired alignment. */
1627 #ifdef ROUND_TYPE_ALIGN
1628 SET_TYPE_ALIGN (rli
->t
, ROUND_TYPE_ALIGN (rli
->t
, TYPE_ALIGN (rli
->t
),
1629 rli
->record_align
));
1631 SET_TYPE_ALIGN (rli
->t
, MAX (TYPE_ALIGN (rli
->t
), rli
->record_align
));
1634 /* Compute the size so far. Be sure to allow for extra bits in the
1635 size in bytes. We have guaranteed above that it will be no more
1636 than a single byte. */
1637 unpadded_size
= rli_size_so_far (rli
);
1638 unpadded_size_unit
= rli_size_unit_so_far (rli
);
1639 if (! integer_zerop (rli
->bitpos
))
1641 = size_binop (PLUS_EXPR
, unpadded_size_unit
, size_one_node
);
1643 /* Round the size up to be a multiple of the required alignment. */
1644 TYPE_SIZE (rli
->t
) = round_up (unpadded_size
, TYPE_ALIGN (rli
->t
));
1645 TYPE_SIZE_UNIT (rli
->t
)
1646 = round_up (unpadded_size_unit
, TYPE_ALIGN_UNIT (rli
->t
));
1648 if (TREE_CONSTANT (unpadded_size
)
1649 && simple_cst_equal (unpadded_size
, TYPE_SIZE (rli
->t
)) == 0
1650 && input_location
!= BUILTINS_LOCATION
)
1651 warning (OPT_Wpadded
, "padding struct size to alignment boundary");
1653 if (warn_packed
&& TREE_CODE (rli
->t
) == RECORD_TYPE
1654 && TYPE_PACKED (rli
->t
) && ! rli
->packed_maybe_necessary
1655 && TREE_CONSTANT (unpadded_size
))
1659 #ifdef ROUND_TYPE_ALIGN
1661 = ROUND_TYPE_ALIGN (rli
->t
, TYPE_ALIGN (rli
->t
), rli
->unpacked_align
);
1663 rli
->unpacked_align
= MAX (TYPE_ALIGN (rli
->t
), rli
->unpacked_align
);
1666 unpacked_size
= round_up (TYPE_SIZE (rli
->t
), rli
->unpacked_align
);
1667 if (simple_cst_equal (unpacked_size
, TYPE_SIZE (rli
->t
)))
1669 if (TYPE_NAME (rli
->t
))
1673 if (TREE_CODE (TYPE_NAME (rli
->t
)) == IDENTIFIER_NODE
)
1674 name
= TYPE_NAME (rli
->t
);
1676 name
= DECL_NAME (TYPE_NAME (rli
->t
));
1678 if (STRICT_ALIGNMENT
)
1679 warning (OPT_Wpacked
, "packed attribute causes inefficient "
1680 "alignment for %qE", name
);
1682 warning (OPT_Wpacked
,
1683 "packed attribute is unnecessary for %qE", name
);
1687 if (STRICT_ALIGNMENT
)
1688 warning (OPT_Wpacked
,
1689 "packed attribute causes inefficient alignment");
1691 warning (OPT_Wpacked
, "packed attribute is unnecessary");
1697 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
1700 compute_record_mode (tree type
)
1703 machine_mode mode
= VOIDmode
;
1705 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
1706 However, if possible, we use a mode that fits in a register
1707 instead, in order to allow for better optimization down the
1709 SET_TYPE_MODE (type
, BLKmode
);
1711 if (! tree_fits_uhwi_p (TYPE_SIZE (type
)))
1714 /* A record which has any BLKmode members must itself be
1715 BLKmode; it can't go in a register. Unless the member is
1716 BLKmode only because it isn't aligned. */
1717 for (field
= TYPE_FIELDS (type
); field
; field
= DECL_CHAIN (field
))
1719 if (TREE_CODE (field
) != FIELD_DECL
)
1722 if (TREE_CODE (TREE_TYPE (field
)) == ERROR_MARK
1723 || (TYPE_MODE (TREE_TYPE (field
)) == BLKmode
1724 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field
))
1725 && !(TYPE_SIZE (TREE_TYPE (field
)) != 0
1726 && integer_zerop (TYPE_SIZE (TREE_TYPE (field
)))))
1727 || ! tree_fits_uhwi_p (bit_position (field
))
1728 || DECL_SIZE (field
) == 0
1729 || ! tree_fits_uhwi_p (DECL_SIZE (field
)))
1732 /* If this field is the whole struct, remember its mode so
1733 that, say, we can put a double in a class into a DF
1734 register instead of forcing it to live in the stack. */
1735 if (simple_cst_equal (TYPE_SIZE (type
), DECL_SIZE (field
)))
1736 mode
= DECL_MODE (field
);
1738 /* With some targets, it is sub-optimal to access an aligned
1739 BLKmode structure as a scalar. */
1740 if (targetm
.member_type_forces_blk (field
, mode
))
1744 /* If we only have one real field; use its mode if that mode's size
1745 matches the type's size. This only applies to RECORD_TYPE. This
1746 does not apply to unions. */
1747 if (TREE_CODE (type
) == RECORD_TYPE
&& mode
!= VOIDmode
1748 && tree_fits_uhwi_p (TYPE_SIZE (type
))
1749 && GET_MODE_BITSIZE (mode
) == tree_to_uhwi (TYPE_SIZE (type
)))
1750 SET_TYPE_MODE (type
, mode
);
1752 SET_TYPE_MODE (type
, mode_for_size_tree (TYPE_SIZE (type
), MODE_INT
, 1));
1754 /* If structure's known alignment is less than what the scalar
1755 mode would need, and it matters, then stick with BLKmode. */
1756 if (TYPE_MODE (type
) != BLKmode
1758 && ! (TYPE_ALIGN (type
) >= BIGGEST_ALIGNMENT
1759 || TYPE_ALIGN (type
) >= GET_MODE_ALIGNMENT (TYPE_MODE (type
))))
1761 /* If this is the only reason this type is BLKmode, then
1762 don't force containing types to be BLKmode. */
1763 TYPE_NO_FORCE_BLK (type
) = 1;
1764 SET_TYPE_MODE (type
, BLKmode
);
1768 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1772 finalize_type_size (tree type
)
1774 /* Normally, use the alignment corresponding to the mode chosen.
1775 However, where strict alignment is not required, avoid
1776 over-aligning structures, since most compilers do not do this
1778 if (TYPE_MODE (type
) != BLKmode
1779 && TYPE_MODE (type
) != VOIDmode
1780 && (STRICT_ALIGNMENT
|| !AGGREGATE_TYPE_P (type
)))
1782 unsigned mode_align
= GET_MODE_ALIGNMENT (TYPE_MODE (type
));
1784 /* Don't override a larger alignment requirement coming from a user
1785 alignment of one of the fields. */
1786 if (mode_align
>= TYPE_ALIGN (type
))
1788 SET_TYPE_ALIGN (type
, mode_align
);
1789 TYPE_USER_ALIGN (type
) = 0;
1793 /* Do machine-dependent extra alignment. */
1794 #ifdef ROUND_TYPE_ALIGN
1795 SET_TYPE_ALIGN (type
,
1796 ROUND_TYPE_ALIGN (type
, TYPE_ALIGN (type
), BITS_PER_UNIT
));
1799 /* If we failed to find a simple way to calculate the unit size
1800 of the type, find it by division. */
1801 if (TYPE_SIZE_UNIT (type
) == 0 && TYPE_SIZE (type
) != 0)
1802 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1803 result will fit in sizetype. We will get more efficient code using
1804 sizetype, so we force a conversion. */
1805 TYPE_SIZE_UNIT (type
)
1806 = fold_convert (sizetype
,
1807 size_binop (FLOOR_DIV_EXPR
, TYPE_SIZE (type
),
1808 bitsize_unit_node
));
1810 if (TYPE_SIZE (type
) != 0)
1812 TYPE_SIZE (type
) = round_up (TYPE_SIZE (type
), TYPE_ALIGN (type
));
1813 TYPE_SIZE_UNIT (type
)
1814 = round_up (TYPE_SIZE_UNIT (type
), TYPE_ALIGN_UNIT (type
));
1817 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1818 if (TYPE_SIZE (type
) != 0 && TREE_CODE (TYPE_SIZE (type
)) != INTEGER_CST
)
1819 TYPE_SIZE (type
) = variable_size (TYPE_SIZE (type
));
1820 if (TYPE_SIZE_UNIT (type
) != 0
1821 && TREE_CODE (TYPE_SIZE_UNIT (type
)) != INTEGER_CST
)
1822 TYPE_SIZE_UNIT (type
) = variable_size (TYPE_SIZE_UNIT (type
));
1824 /* Also layout any other variants of the type. */
1825 if (TYPE_NEXT_VARIANT (type
)
1826 || type
!= TYPE_MAIN_VARIANT (type
))
1829 /* Record layout info of this variant. */
1830 tree size
= TYPE_SIZE (type
);
1831 tree size_unit
= TYPE_SIZE_UNIT (type
);
1832 unsigned int align
= TYPE_ALIGN (type
);
1833 unsigned int precision
= TYPE_PRECISION (type
);
1834 unsigned int user_align
= TYPE_USER_ALIGN (type
);
1835 machine_mode mode
= TYPE_MODE (type
);
1837 /* Copy it into all variants. */
1838 for (variant
= TYPE_MAIN_VARIANT (type
);
1840 variant
= TYPE_NEXT_VARIANT (variant
))
1842 TYPE_SIZE (variant
) = size
;
1843 TYPE_SIZE_UNIT (variant
) = size_unit
;
1844 unsigned valign
= align
;
1845 if (TYPE_USER_ALIGN (variant
))
1846 valign
= MAX (valign
, TYPE_ALIGN (variant
));
1848 TYPE_USER_ALIGN (variant
) = user_align
;
1849 SET_TYPE_ALIGN (variant
, valign
);
1850 TYPE_PRECISION (variant
) = precision
;
1851 SET_TYPE_MODE (variant
, mode
);
1856 /* Return a new underlying object for a bitfield started with FIELD. */
1859 start_bitfield_representative (tree field
)
1861 tree repr
= make_node (FIELD_DECL
);
1862 DECL_FIELD_OFFSET (repr
) = DECL_FIELD_OFFSET (field
);
1863 /* Force the representative to begin at a BITS_PER_UNIT aligned
1864 boundary - C++ may use tail-padding of a base object to
1865 continue packing bits so the bitfield region does not start
1866 at bit zero (see g++.dg/abi/bitfield5.C for example).
1867 Unallocated bits may happen for other reasons as well,
1868 for example Ada which allows explicit bit-granular structure layout. */
1869 DECL_FIELD_BIT_OFFSET (repr
)
1870 = size_binop (BIT_AND_EXPR
,
1871 DECL_FIELD_BIT_OFFSET (field
),
1872 bitsize_int (~(BITS_PER_UNIT
- 1)));
1873 SET_DECL_OFFSET_ALIGN (repr
, DECL_OFFSET_ALIGN (field
));
1874 DECL_SIZE (repr
) = DECL_SIZE (field
);
1875 DECL_SIZE_UNIT (repr
) = DECL_SIZE_UNIT (field
);
1876 DECL_PACKED (repr
) = DECL_PACKED (field
);
1877 DECL_CONTEXT (repr
) = DECL_CONTEXT (field
);
1878 /* There are no indirect accesses to this field. If we introduce
1879 some then they have to use the record alias set. This makes
1880 sure to properly conflict with [indirect] accesses to addressable
1881 fields of the bitfield group. */
1882 DECL_NONADDRESSABLE_P (repr
) = 1;
1886 /* Finish up a bitfield group that was started by creating the underlying
1887 object REPR with the last field in the bitfield group FIELD. */
1890 finish_bitfield_representative (tree repr
, tree field
)
1892 unsigned HOST_WIDE_INT bitsize
, maxbitsize
;
1895 size
= size_diffop (DECL_FIELD_OFFSET (field
),
1896 DECL_FIELD_OFFSET (repr
));
1897 while (TREE_CODE (size
) == COMPOUND_EXPR
)
1898 size
= TREE_OPERAND (size
, 1);
1899 gcc_assert (tree_fits_uhwi_p (size
));
1900 bitsize
= (tree_to_uhwi (size
) * BITS_PER_UNIT
1901 + tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field
))
1902 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr
))
1903 + tree_to_uhwi (DECL_SIZE (field
)));
1905 /* Round up bitsize to multiples of BITS_PER_UNIT. */
1906 bitsize
= (bitsize
+ BITS_PER_UNIT
- 1) & ~(BITS_PER_UNIT
- 1);
1908 /* Now nothing tells us how to pad out bitsize ... */
1909 nextf
= DECL_CHAIN (field
);
1910 while (nextf
&& TREE_CODE (nextf
) != FIELD_DECL
)
1911 nextf
= DECL_CHAIN (nextf
);
1915 /* If there was an error, the field may be not laid out
1916 correctly. Don't bother to do anything. */
1917 if (TREE_TYPE (nextf
) == error_mark_node
)
1919 maxsize
= size_diffop (DECL_FIELD_OFFSET (nextf
),
1920 DECL_FIELD_OFFSET (repr
));
1921 if (tree_fits_uhwi_p (maxsize
))
1923 maxbitsize
= (tree_to_uhwi (maxsize
) * BITS_PER_UNIT
1924 + tree_to_uhwi (DECL_FIELD_BIT_OFFSET (nextf
))
1925 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr
)));
1926 /* If the group ends within a bitfield nextf does not need to be
1927 aligned to BITS_PER_UNIT. Thus round up. */
1928 maxbitsize
= (maxbitsize
+ BITS_PER_UNIT
- 1) & ~(BITS_PER_UNIT
- 1);
1931 maxbitsize
= bitsize
;
1935 /* Note that if the C++ FE sets up tail-padding to be re-used it
1936 creates a as-base variant of the type with TYPE_SIZE adjusted
1937 accordingly. So it is safe to include tail-padding here. */
1938 tree aggsize
= lang_hooks
.types
.unit_size_without_reusable_padding
1939 (DECL_CONTEXT (field
));
1940 tree maxsize
= size_diffop (aggsize
, DECL_FIELD_OFFSET (repr
));
1941 /* We cannot generally rely on maxsize to fold to an integer constant,
1942 so use bitsize as fallback for this case. */
1943 if (tree_fits_uhwi_p (maxsize
))
1944 maxbitsize
= (tree_to_uhwi (maxsize
) * BITS_PER_UNIT
1945 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr
)));
1947 maxbitsize
= bitsize
;
1950 /* Only if we don't artificially break up the representative in
1951 the middle of a large bitfield with different possibly
1952 overlapping representatives. And all representatives start
1954 gcc_assert (maxbitsize
% BITS_PER_UNIT
== 0);
1956 /* Find the smallest nice mode to use. */
1957 opt_scalar_int_mode mode_iter
;
1958 FOR_EACH_MODE_IN_CLASS (mode_iter
, MODE_INT
)
1959 if (GET_MODE_BITSIZE (mode_iter
.require ()) >= bitsize
)
1962 scalar_int_mode mode
;
1963 if (!mode_iter
.exists (&mode
)
1964 || GET_MODE_BITSIZE (mode
) > maxbitsize
1965 || GET_MODE_BITSIZE (mode
) > MAX_FIXED_MODE_SIZE
)
1967 /* We really want a BLKmode representative only as a last resort,
1968 considering the member b in
1969 struct { int a : 7; int b : 17; int c; } __attribute__((packed));
1970 Otherwise we simply want to split the representative up
1971 allowing for overlaps within the bitfield region as required for
1972 struct { int a : 7; int b : 7;
1973 int c : 10; int d; } __attribute__((packed));
1974 [0, 15] HImode for a and b, [8, 23] HImode for c. */
1975 DECL_SIZE (repr
) = bitsize_int (bitsize
);
1976 DECL_SIZE_UNIT (repr
) = size_int (bitsize
/ BITS_PER_UNIT
);
1977 SET_DECL_MODE (repr
, BLKmode
);
1978 TREE_TYPE (repr
) = build_array_type_nelts (unsigned_char_type_node
,
1979 bitsize
/ BITS_PER_UNIT
);
1983 unsigned HOST_WIDE_INT modesize
= GET_MODE_BITSIZE (mode
);
1984 DECL_SIZE (repr
) = bitsize_int (modesize
);
1985 DECL_SIZE_UNIT (repr
) = size_int (modesize
/ BITS_PER_UNIT
);
1986 SET_DECL_MODE (repr
, mode
);
1987 TREE_TYPE (repr
) = lang_hooks
.types
.type_for_mode (mode
, 1);
1990 /* Remember whether the bitfield group is at the end of the
1991 structure or not. */
1992 DECL_CHAIN (repr
) = nextf
;
1995 /* Compute and set FIELD_DECLs for the underlying objects we should
1996 use for bitfield access for the structure T. */
1999 finish_bitfield_layout (tree t
)
2002 tree repr
= NULL_TREE
;
2004 /* Unions would be special, for the ease of type-punning optimizations
2005 we could use the underlying type as hint for the representative
2006 if the bitfield would fit and the representative would not exceed
2007 the union in size. */
2008 if (TREE_CODE (t
) != RECORD_TYPE
)
2011 for (prev
= NULL_TREE
, field
= TYPE_FIELDS (t
);
2012 field
; field
= DECL_CHAIN (field
))
2014 if (TREE_CODE (field
) != FIELD_DECL
)
2017 /* In the C++ memory model, consecutive bit fields in a structure are
2018 considered one memory location and updating a memory location
2019 may not store into adjacent memory locations. */
2021 && DECL_BIT_FIELD_TYPE (field
))
2023 /* Start new representative. */
2024 repr
= start_bitfield_representative (field
);
2027 && ! DECL_BIT_FIELD_TYPE (field
))
2029 /* Finish off new representative. */
2030 finish_bitfield_representative (repr
, prev
);
2033 else if (DECL_BIT_FIELD_TYPE (field
))
2035 gcc_assert (repr
!= NULL_TREE
);
2037 /* Zero-size bitfields finish off a representative and
2038 do not have a representative themselves. This is
2039 required by the C++ memory model. */
2040 if (integer_zerop (DECL_SIZE (field
)))
2042 finish_bitfield_representative (repr
, prev
);
2046 /* We assume that either DECL_FIELD_OFFSET of the representative
2047 and each bitfield member is a constant or they are equal.
2048 This is because we need to be able to compute the bit-offset
2049 of each field relative to the representative in get_bit_range
2050 during RTL expansion.
2051 If these constraints are not met, simply force a new
2052 representative to be generated. That will at most
2053 generate worse code but still maintain correctness with
2054 respect to the C++ memory model. */
2055 else if (!((tree_fits_uhwi_p (DECL_FIELD_OFFSET (repr
))
2056 && tree_fits_uhwi_p (DECL_FIELD_OFFSET (field
)))
2057 || operand_equal_p (DECL_FIELD_OFFSET (repr
),
2058 DECL_FIELD_OFFSET (field
), 0)))
2060 finish_bitfield_representative (repr
, prev
);
2061 repr
= start_bitfield_representative (field
);
2068 DECL_BIT_FIELD_REPRESENTATIVE (field
) = repr
;
2074 finish_bitfield_representative (repr
, prev
);
2077 /* Do all of the work required to layout the type indicated by RLI,
2078 once the fields have been laid out. This function will call `free'
2079 for RLI, unless FREE_P is false. Passing a value other than false
2080 for FREE_P is bad practice; this option only exists to support the
2084 finish_record_layout (record_layout_info rli
, int free_p
)
2088 /* Compute the final size. */
2089 finalize_record_size (rli
);
2091 /* Compute the TYPE_MODE for the record. */
2092 compute_record_mode (rli
->t
);
2094 /* Perform any last tweaks to the TYPE_SIZE, etc. */
2095 finalize_type_size (rli
->t
);
2097 /* Compute bitfield representatives. */
2098 finish_bitfield_layout (rli
->t
);
2100 /* Propagate TYPE_PACKED and TYPE_REVERSE_STORAGE_ORDER to variants.
2101 With C++ templates, it is too early to do this when the attribute
2103 for (variant
= TYPE_NEXT_VARIANT (rli
->t
); variant
;
2104 variant
= TYPE_NEXT_VARIANT (variant
))
2106 TYPE_PACKED (variant
) = TYPE_PACKED (rli
->t
);
2107 TYPE_REVERSE_STORAGE_ORDER (variant
)
2108 = TYPE_REVERSE_STORAGE_ORDER (rli
->t
);
2111 /* Lay out any static members. This is done now because their type
2112 may use the record's type. */
2113 while (!vec_safe_is_empty (rli
->pending_statics
))
2114 layout_decl (rli
->pending_statics
->pop (), 0);
2119 vec_free (rli
->pending_statics
);
2125 /* Finish processing a builtin RECORD_TYPE type TYPE. It's name is
2126 NAME, its fields are chained in reverse on FIELDS.
2128 If ALIGN_TYPE is non-null, it is given the same alignment as
2132 finish_builtin_struct (tree type
, const char *name
, tree fields
,
2137 for (tail
= NULL_TREE
; fields
; tail
= fields
, fields
= next
)
2139 DECL_FIELD_CONTEXT (fields
) = type
;
2140 next
= DECL_CHAIN (fields
);
2141 DECL_CHAIN (fields
) = tail
;
2143 TYPE_FIELDS (type
) = tail
;
2147 SET_TYPE_ALIGN (type
, TYPE_ALIGN (align_type
));
2148 TYPE_USER_ALIGN (type
) = TYPE_USER_ALIGN (align_type
);
2149 SET_TYPE_WARN_IF_NOT_ALIGN (type
,
2150 TYPE_WARN_IF_NOT_ALIGN (align_type
));
2154 #if 0 /* not yet, should get fixed properly later */
2155 TYPE_NAME (type
) = make_type_decl (get_identifier (name
), type
);
2157 TYPE_NAME (type
) = build_decl (BUILTINS_LOCATION
,
2158 TYPE_DECL
, get_identifier (name
), type
);
2160 TYPE_STUB_DECL (type
) = TYPE_NAME (type
);
2161 layout_decl (TYPE_NAME (type
), 0);
2164 /* Calculate the mode, size, and alignment for TYPE.
2165 For an array type, calculate the element separation as well.
2166 Record TYPE on the chain of permanent or temporary types
2167 so that dbxout will find out about it.
2169 TYPE_SIZE of a type is nonzero if the type has been laid out already.
2170 layout_type does nothing on such a type.
2172 If the type is incomplete, its TYPE_SIZE remains zero. */
2175 layout_type (tree type
)
2179 if (type
== error_mark_node
)
2182 /* We don't want finalize_type_size to copy an alignment attribute to
2183 variants that don't have it. */
2184 type
= TYPE_MAIN_VARIANT (type
);
2186 /* Do nothing if type has been laid out before. */
2187 if (TYPE_SIZE (type
))
2190 switch (TREE_CODE (type
))
2193 /* This kind of type is the responsibility
2194 of the language-specific code. */
2201 scalar_int_mode mode
2202 = smallest_int_mode_for_size (TYPE_PRECISION (type
));
2203 SET_TYPE_MODE (type
, mode
);
2204 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2205 /* Don't set TYPE_PRECISION here, as it may be set by a bitfield. */
2206 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2212 /* Allow the caller to choose the type mode, which is how decimal
2213 floats are distinguished from binary ones. */
2214 if (TYPE_MODE (type
) == VOIDmode
)
2216 (type
, float_mode_for_size (TYPE_PRECISION (type
)).require ());
2217 scalar_float_mode mode
= as_a
<scalar_float_mode
> (TYPE_MODE (type
));
2218 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2219 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2223 case FIXED_POINT_TYPE
:
2225 /* TYPE_MODE (type) has been set already. */
2226 scalar_mode mode
= SCALAR_TYPE_MODE (type
);
2227 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2228 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2233 TYPE_UNSIGNED (type
) = TYPE_UNSIGNED (TREE_TYPE (type
));
2234 SET_TYPE_MODE (type
,
2235 GET_MODE_COMPLEX_MODE (TYPE_MODE (TREE_TYPE (type
))));
2237 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
2238 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
2243 int nunits
= TYPE_VECTOR_SUBPARTS (type
);
2244 tree innertype
= TREE_TYPE (type
);
2246 gcc_assert (!(nunits
& (nunits
- 1)));
2248 /* Find an appropriate mode for the vector type. */
2249 if (TYPE_MODE (type
) == VOIDmode
)
2250 SET_TYPE_MODE (type
,
2251 mode_for_vector (SCALAR_TYPE_MODE (innertype
),
2254 TYPE_SATURATING (type
) = TYPE_SATURATING (TREE_TYPE (type
));
2255 TYPE_UNSIGNED (type
) = TYPE_UNSIGNED (TREE_TYPE (type
));
2256 /* Several boolean vector elements may fit in a single unit. */
2257 if (VECTOR_BOOLEAN_TYPE_P (type
)
2258 && type
->type_common
.mode
!= BLKmode
)
2259 TYPE_SIZE_UNIT (type
)
2260 = size_int (GET_MODE_SIZE (type
->type_common
.mode
));
2262 TYPE_SIZE_UNIT (type
) = int_const_binop (MULT_EXPR
,
2263 TYPE_SIZE_UNIT (innertype
),
2265 TYPE_SIZE (type
) = int_const_binop (MULT_EXPR
,
2266 TYPE_SIZE (innertype
),
2267 bitsize_int (nunits
));
2269 /* For vector types, we do not default to the mode's alignment.
2270 Instead, query a target hook, defaulting to natural alignment.
2271 This prevents ABI changes depending on whether or not native
2272 vector modes are supported. */
2273 SET_TYPE_ALIGN (type
, targetm
.vector_alignment (type
));
2275 /* However, if the underlying mode requires a bigger alignment than
2276 what the target hook provides, we cannot use the mode. For now,
2277 simply reject that case. */
2278 gcc_assert (TYPE_ALIGN (type
)
2279 >= GET_MODE_ALIGNMENT (TYPE_MODE (type
)));
2284 /* This is an incomplete type and so doesn't have a size. */
2285 SET_TYPE_ALIGN (type
, 1);
2286 TYPE_USER_ALIGN (type
) = 0;
2287 SET_TYPE_MODE (type
, VOIDmode
);
2290 case POINTER_BOUNDS_TYPE
:
2291 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
2292 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
2296 TYPE_SIZE (type
) = bitsize_int (POINTER_SIZE
);
2297 TYPE_SIZE_UNIT (type
) = size_int (POINTER_SIZE_UNITS
);
2298 /* A pointer might be MODE_PARTIAL_INT, but ptrdiff_t must be
2299 integral, which may be an __intN. */
2300 SET_TYPE_MODE (type
, int_mode_for_size (POINTER_SIZE
, 0).require ());
2301 TYPE_PRECISION (type
) = POINTER_SIZE
;
2306 /* It's hard to see what the mode and size of a function ought to
2307 be, but we do know the alignment is FUNCTION_BOUNDARY, so
2308 make it consistent with that. */
2309 SET_TYPE_MODE (type
,
2310 int_mode_for_size (FUNCTION_BOUNDARY
, 0).else_blk ());
2311 TYPE_SIZE (type
) = bitsize_int (FUNCTION_BOUNDARY
);
2312 TYPE_SIZE_UNIT (type
) = size_int (FUNCTION_BOUNDARY
/ BITS_PER_UNIT
);
2316 case REFERENCE_TYPE
:
2318 scalar_int_mode mode
= SCALAR_INT_TYPE_MODE (type
);
2319 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2320 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2321 TYPE_UNSIGNED (type
) = 1;
2322 TYPE_PRECISION (type
) = GET_MODE_PRECISION (mode
);
2328 tree index
= TYPE_DOMAIN (type
);
2329 tree element
= TREE_TYPE (type
);
2331 /* We need to know both bounds in order to compute the size. */
2332 if (index
&& TYPE_MAX_VALUE (index
) && TYPE_MIN_VALUE (index
)
2333 && TYPE_SIZE (element
))
2335 tree ub
= TYPE_MAX_VALUE (index
);
2336 tree lb
= TYPE_MIN_VALUE (index
);
2337 tree element_size
= TYPE_SIZE (element
);
2340 /* Make sure that an array of zero-sized element is zero-sized
2341 regardless of its extent. */
2342 if (integer_zerop (element_size
))
2343 length
= size_zero_node
;
2345 /* The computation should happen in the original signedness so
2346 that (possible) negative values are handled appropriately
2347 when determining overflow. */
2350 /* ??? When it is obvious that the range is signed
2351 represent it using ssizetype. */
2352 if (TREE_CODE (lb
) == INTEGER_CST
2353 && TREE_CODE (ub
) == INTEGER_CST
2354 && TYPE_UNSIGNED (TREE_TYPE (lb
))
2355 && tree_int_cst_lt (ub
, lb
))
2357 lb
= wide_int_to_tree (ssizetype
,
2358 offset_int::from (lb
, SIGNED
));
2359 ub
= wide_int_to_tree (ssizetype
,
2360 offset_int::from (ub
, SIGNED
));
2363 = fold_convert (sizetype
,
2364 size_binop (PLUS_EXPR
,
2365 build_int_cst (TREE_TYPE (lb
), 1),
2366 size_binop (MINUS_EXPR
, ub
, lb
)));
2369 /* ??? We have no way to distinguish a null-sized array from an
2370 array spanning the whole sizetype range, so we arbitrarily
2371 decide that [0, -1] is the only valid representation. */
2372 if (integer_zerop (length
)
2373 && TREE_OVERFLOW (length
)
2374 && integer_zerop (lb
))
2375 length
= size_zero_node
;
2377 TYPE_SIZE (type
) = size_binop (MULT_EXPR
, element_size
,
2378 fold_convert (bitsizetype
,
2381 /* If we know the size of the element, calculate the total size
2382 directly, rather than do some division thing below. This
2383 optimization helps Fortran assumed-size arrays (where the
2384 size of the array is determined at runtime) substantially. */
2385 if (TYPE_SIZE_UNIT (element
))
2386 TYPE_SIZE_UNIT (type
)
2387 = size_binop (MULT_EXPR
, TYPE_SIZE_UNIT (element
), length
);
2390 /* Now round the alignment and size,
2391 using machine-dependent criteria if any. */
2393 unsigned align
= TYPE_ALIGN (element
);
2394 if (TYPE_USER_ALIGN (type
))
2395 align
= MAX (align
, TYPE_ALIGN (type
));
2397 TYPE_USER_ALIGN (type
) = TYPE_USER_ALIGN (element
);
2398 if (!TYPE_WARN_IF_NOT_ALIGN (type
))
2399 SET_TYPE_WARN_IF_NOT_ALIGN (type
,
2400 TYPE_WARN_IF_NOT_ALIGN (element
));
2401 #ifdef ROUND_TYPE_ALIGN
2402 align
= ROUND_TYPE_ALIGN (type
, align
, BITS_PER_UNIT
);
2404 align
= MAX (align
, BITS_PER_UNIT
);
2406 SET_TYPE_ALIGN (type
, align
);
2407 SET_TYPE_MODE (type
, BLKmode
);
2408 if (TYPE_SIZE (type
) != 0
2409 && ! targetm
.member_type_forces_blk (type
, VOIDmode
)
2410 /* BLKmode elements force BLKmode aggregate;
2411 else extract/store fields may lose. */
2412 && (TYPE_MODE (TREE_TYPE (type
)) != BLKmode
2413 || TYPE_NO_FORCE_BLK (TREE_TYPE (type
))))
2415 SET_TYPE_MODE (type
, mode_for_array (TREE_TYPE (type
),
2417 if (TYPE_MODE (type
) != BLKmode
2418 && STRICT_ALIGNMENT
&& TYPE_ALIGN (type
) < BIGGEST_ALIGNMENT
2419 && TYPE_ALIGN (type
) < GET_MODE_ALIGNMENT (TYPE_MODE (type
)))
2421 TYPE_NO_FORCE_BLK (type
) = 1;
2422 SET_TYPE_MODE (type
, BLKmode
);
2425 if (AGGREGATE_TYPE_P (element
))
2426 TYPE_TYPELESS_STORAGE (type
) = TYPE_TYPELESS_STORAGE (element
);
2427 /* When the element size is constant, check that it is at least as
2428 large as the element alignment. */
2429 if (TYPE_SIZE_UNIT (element
)
2430 && TREE_CODE (TYPE_SIZE_UNIT (element
)) == INTEGER_CST
2431 /* If TYPE_SIZE_UNIT overflowed, then it is certainly larger than
2433 && !TREE_OVERFLOW (TYPE_SIZE_UNIT (element
))
2434 && !integer_zerop (TYPE_SIZE_UNIT (element
))
2435 && compare_tree_int (TYPE_SIZE_UNIT (element
),
2436 TYPE_ALIGN_UNIT (element
)) < 0)
2437 error ("alignment of array elements is greater than element size");
2443 case QUAL_UNION_TYPE
:
2446 record_layout_info rli
;
2448 /* Initialize the layout information. */
2449 rli
= start_record_layout (type
);
2451 /* If this is a QUAL_UNION_TYPE, we want to process the fields
2452 in the reverse order in building the COND_EXPR that denotes
2453 its size. We reverse them again later. */
2454 if (TREE_CODE (type
) == QUAL_UNION_TYPE
)
2455 TYPE_FIELDS (type
) = nreverse (TYPE_FIELDS (type
));
2457 /* Place all the fields. */
2458 for (field
= TYPE_FIELDS (type
); field
; field
= DECL_CHAIN (field
))
2459 place_field (rli
, field
);
2461 if (TREE_CODE (type
) == QUAL_UNION_TYPE
)
2462 TYPE_FIELDS (type
) = nreverse (TYPE_FIELDS (type
));
2464 /* Finish laying out the record. */
2465 finish_record_layout (rli
, /*free_p=*/true);
2473 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
2474 records and unions, finish_record_layout already called this
2476 if (!RECORD_OR_UNION_TYPE_P (type
))
2477 finalize_type_size (type
);
2479 /* We should never see alias sets on incomplete aggregates. And we
2480 should not call layout_type on not incomplete aggregates. */
2481 if (AGGREGATE_TYPE_P (type
))
2482 gcc_assert (!TYPE_ALIAS_SET_KNOWN_P (type
));
2485 /* Return the least alignment required for type TYPE. */
2488 min_align_of_type (tree type
)
2490 unsigned int align
= TYPE_ALIGN (type
);
2491 if (!TYPE_USER_ALIGN (type
))
2493 align
= MIN (align
, BIGGEST_ALIGNMENT
);
2494 #ifdef BIGGEST_FIELD_ALIGNMENT
2495 align
= MIN (align
, BIGGEST_FIELD_ALIGNMENT
);
2497 unsigned int field_align
= align
;
2498 #ifdef ADJUST_FIELD_ALIGN
2499 field_align
= ADJUST_FIELD_ALIGN (NULL_TREE
, type
, field_align
);
2501 align
= MIN (align
, field_align
);
2503 return align
/ BITS_PER_UNIT
;
2506 /* Create and return a type for signed integers of PRECISION bits. */
2509 make_signed_type (int precision
)
2511 tree type
= make_node (INTEGER_TYPE
);
2513 TYPE_PRECISION (type
) = precision
;
2515 fixup_signed_type (type
);
2519 /* Create and return a type for unsigned integers of PRECISION bits. */
2522 make_unsigned_type (int precision
)
2524 tree type
= make_node (INTEGER_TYPE
);
2526 TYPE_PRECISION (type
) = precision
;
2528 fixup_unsigned_type (type
);
2532 /* Create and return a type for fract of PRECISION bits, UNSIGNEDP,
2536 make_fract_type (int precision
, int unsignedp
, int satp
)
2538 tree type
= make_node (FIXED_POINT_TYPE
);
2540 TYPE_PRECISION (type
) = precision
;
2543 TYPE_SATURATING (type
) = 1;
2545 /* Lay out the type: set its alignment, size, etc. */
2548 TYPE_UNSIGNED (type
) = 1;
2549 SET_TYPE_MODE (type
, mode_for_size (precision
, MODE_UFRACT
, 0));
2552 SET_TYPE_MODE (type
, mode_for_size (precision
, MODE_FRACT
, 0));
2558 /* Create and return a type for accum of PRECISION bits, UNSIGNEDP,
2562 make_accum_type (int precision
, int unsignedp
, int satp
)
2564 tree type
= make_node (FIXED_POINT_TYPE
);
2566 TYPE_PRECISION (type
) = precision
;
2569 TYPE_SATURATING (type
) = 1;
2571 /* Lay out the type: set its alignment, size, etc. */
2574 TYPE_UNSIGNED (type
) = 1;
2575 SET_TYPE_MODE (type
, mode_for_size (precision
, MODE_UACCUM
, 0));
2578 SET_TYPE_MODE (type
, mode_for_size (precision
, MODE_ACCUM
, 0));
2584 /* Initialize sizetypes so layout_type can use them. */
2587 initialize_sizetypes (void)
2589 int precision
, bprecision
;
2591 /* Get sizetypes precision from the SIZE_TYPE target macro. */
2592 if (strcmp (SIZETYPE
, "unsigned int") == 0)
2593 precision
= INT_TYPE_SIZE
;
2594 else if (strcmp (SIZETYPE
, "long unsigned int") == 0)
2595 precision
= LONG_TYPE_SIZE
;
2596 else if (strcmp (SIZETYPE
, "long long unsigned int") == 0)
2597 precision
= LONG_LONG_TYPE_SIZE
;
2598 else if (strcmp (SIZETYPE
, "short unsigned int") == 0)
2599 precision
= SHORT_TYPE_SIZE
;
2605 for (i
= 0; i
< NUM_INT_N_ENTS
; i
++)
2606 if (int_n_enabled_p
[i
])
2609 sprintf (name
, "__int%d unsigned", int_n_data
[i
].bitsize
);
2611 if (strcmp (name
, SIZETYPE
) == 0)
2613 precision
= int_n_data
[i
].bitsize
;
2616 if (precision
== -1)
2621 = MIN (precision
+ LOG2_BITS_PER_UNIT
+ 1, MAX_FIXED_MODE_SIZE
);
2622 bprecision
= GET_MODE_PRECISION (smallest_int_mode_for_size (bprecision
));
2623 if (bprecision
> HOST_BITS_PER_DOUBLE_INT
)
2624 bprecision
= HOST_BITS_PER_DOUBLE_INT
;
2626 /* Create stubs for sizetype and bitsizetype so we can create constants. */
2627 sizetype
= make_node (INTEGER_TYPE
);
2628 TYPE_NAME (sizetype
) = get_identifier ("sizetype");
2629 TYPE_PRECISION (sizetype
) = precision
;
2630 TYPE_UNSIGNED (sizetype
) = 1;
2631 bitsizetype
= make_node (INTEGER_TYPE
);
2632 TYPE_NAME (bitsizetype
) = get_identifier ("bitsizetype");
2633 TYPE_PRECISION (bitsizetype
) = bprecision
;
2634 TYPE_UNSIGNED (bitsizetype
) = 1;
2636 /* Now layout both types manually. */
2637 scalar_int_mode mode
= smallest_int_mode_for_size (precision
);
2638 SET_TYPE_MODE (sizetype
, mode
);
2639 SET_TYPE_ALIGN (sizetype
, GET_MODE_ALIGNMENT (TYPE_MODE (sizetype
)));
2640 TYPE_SIZE (sizetype
) = bitsize_int (precision
);
2641 TYPE_SIZE_UNIT (sizetype
) = size_int (GET_MODE_SIZE (mode
));
2642 set_min_and_max_values_for_integral_type (sizetype
, precision
, UNSIGNED
);
2644 mode
= smallest_int_mode_for_size (bprecision
);
2645 SET_TYPE_MODE (bitsizetype
, mode
);
2646 SET_TYPE_ALIGN (bitsizetype
, GET_MODE_ALIGNMENT (TYPE_MODE (bitsizetype
)));
2647 TYPE_SIZE (bitsizetype
) = bitsize_int (bprecision
);
2648 TYPE_SIZE_UNIT (bitsizetype
) = size_int (GET_MODE_SIZE (mode
));
2649 set_min_and_max_values_for_integral_type (bitsizetype
, bprecision
, UNSIGNED
);
2651 /* Create the signed variants of *sizetype. */
2652 ssizetype
= make_signed_type (TYPE_PRECISION (sizetype
));
2653 TYPE_NAME (ssizetype
) = get_identifier ("ssizetype");
2654 sbitsizetype
= make_signed_type (TYPE_PRECISION (bitsizetype
));
2655 TYPE_NAME (sbitsizetype
) = get_identifier ("sbitsizetype");
2658 /* TYPE is an integral type, i.e., an INTEGRAL_TYPE, ENUMERAL_TYPE
2659 or BOOLEAN_TYPE. Set TYPE_MIN_VALUE and TYPE_MAX_VALUE
2660 for TYPE, based on the PRECISION and whether or not the TYPE
2661 IS_UNSIGNED. PRECISION need not correspond to a width supported
2662 natively by the hardware; for example, on a machine with 8-bit,
2663 16-bit, and 32-bit register modes, PRECISION might be 7, 23, or
2667 set_min_and_max_values_for_integral_type (tree type
,
2671 /* For bitfields with zero width we end up creating integer types
2672 with zero precision. Don't assign any minimum/maximum values
2673 to those types, they don't have any valid value. */
2677 TYPE_MIN_VALUE (type
)
2678 = wide_int_to_tree (type
, wi::min_value (precision
, sgn
));
2679 TYPE_MAX_VALUE (type
)
2680 = wide_int_to_tree (type
, wi::max_value (precision
, sgn
));
2683 /* Set the extreme values of TYPE based on its precision in bits,
2684 then lay it out. Used when make_signed_type won't do
2685 because the tree code is not INTEGER_TYPE. */
2688 fixup_signed_type (tree type
)
2690 int precision
= TYPE_PRECISION (type
);
2692 set_min_and_max_values_for_integral_type (type
, precision
, SIGNED
);
2694 /* Lay out the type: set its alignment, size, etc. */
2698 /* Set the extreme values of TYPE based on its precision in bits,
2699 then lay it out. This is used both in `make_unsigned_type'
2700 and for enumeral types. */
2703 fixup_unsigned_type (tree type
)
2705 int precision
= TYPE_PRECISION (type
);
2707 TYPE_UNSIGNED (type
) = 1;
2709 set_min_and_max_values_for_integral_type (type
, precision
, UNSIGNED
);
2711 /* Lay out the type: set its alignment, size, etc. */
2715 /* Construct an iterator for a bitfield that spans BITSIZE bits,
2718 BITREGION_START is the bit position of the first bit in this
2719 sequence of bit fields. BITREGION_END is the last bit in this
2720 sequence. If these two fields are non-zero, we should restrict the
2721 memory access to that range. Otherwise, we are allowed to touch
2722 any adjacent non bit-fields.
2724 ALIGN is the alignment of the underlying object in bits.
2725 VOLATILEP says whether the bitfield is volatile. */
2727 bit_field_mode_iterator
2728 ::bit_field_mode_iterator (HOST_WIDE_INT bitsize
, HOST_WIDE_INT bitpos
,
2729 HOST_WIDE_INT bitregion_start
,
2730 HOST_WIDE_INT bitregion_end
,
2731 unsigned int align
, bool volatilep
)
2732 : m_mode (NARROWEST_INT_MODE
), m_bitsize (bitsize
),
2733 m_bitpos (bitpos
), m_bitregion_start (bitregion_start
),
2734 m_bitregion_end (bitregion_end
), m_align (align
),
2735 m_volatilep (volatilep
), m_count (0)
2737 if (!m_bitregion_end
)
2739 /* We can assume that any aligned chunk of ALIGN bits that overlaps
2740 the bitfield is mapped and won't trap, provided that ALIGN isn't
2741 too large. The cap is the biggest required alignment for data,
2742 or at least the word size. And force one such chunk at least. */
2743 unsigned HOST_WIDE_INT units
2744 = MIN (align
, MAX (BIGGEST_ALIGNMENT
, BITS_PER_WORD
));
2747 m_bitregion_end
= bitpos
+ bitsize
+ units
- 1;
2748 m_bitregion_end
-= m_bitregion_end
% units
+ 1;
2752 /* Calls to this function return successively larger modes that can be used
2753 to represent the bitfield. Return true if another bitfield mode is
2754 available, storing it in *OUT_MODE if so. */
2757 bit_field_mode_iterator::next_mode (scalar_int_mode
*out_mode
)
2759 scalar_int_mode mode
;
2760 for (; m_mode
.exists (&mode
); m_mode
= GET_MODE_WIDER_MODE (mode
))
2762 unsigned int unit
= GET_MODE_BITSIZE (mode
);
2764 /* Skip modes that don't have full precision. */
2765 if (unit
!= GET_MODE_PRECISION (mode
))
2768 /* Stop if the mode is too wide to handle efficiently. */
2769 if (unit
> MAX_FIXED_MODE_SIZE
)
2772 /* Don't deliver more than one multiword mode; the smallest one
2774 if (m_count
> 0 && unit
> BITS_PER_WORD
)
2777 /* Skip modes that are too small. */
2778 unsigned HOST_WIDE_INT substart
= (unsigned HOST_WIDE_INT
) m_bitpos
% unit
;
2779 unsigned HOST_WIDE_INT subend
= substart
+ m_bitsize
;
2783 /* Stop if the mode goes outside the bitregion. */
2784 HOST_WIDE_INT start
= m_bitpos
- substart
;
2785 if (m_bitregion_start
&& start
< m_bitregion_start
)
2787 HOST_WIDE_INT end
= start
+ unit
;
2788 if (end
> m_bitregion_end
+ 1)
2791 /* Stop if the mode requires too much alignment. */
2792 if (GET_MODE_ALIGNMENT (mode
) > m_align
2793 && SLOW_UNALIGNED_ACCESS (mode
, m_align
))
2797 m_mode
= GET_MODE_WIDER_MODE (mode
);
2804 /* Return true if smaller modes are generally preferred for this kind
2808 bit_field_mode_iterator::prefer_smaller_modes ()
2811 ? targetm
.narrow_volatile_bitfield ()
2812 : !SLOW_BYTE_ACCESS
);
2815 /* Find the best machine mode to use when referencing a bit field of length
2816 BITSIZE bits starting at BITPOS.
2818 BITREGION_START is the bit position of the first bit in this
2819 sequence of bit fields. BITREGION_END is the last bit in this
2820 sequence. If these two fields are non-zero, we should restrict the
2821 memory access to that range. Otherwise, we are allowed to touch
2822 any adjacent non bit-fields.
2824 The chosen mode must have no more than LARGEST_MODE_BITSIZE bits.
2825 INT_MAX is a suitable value for LARGEST_MODE_BITSIZE if the caller
2826 doesn't want to apply a specific limit.
2828 If no mode meets all these conditions, we return VOIDmode.
2830 The underlying object is known to be aligned to a boundary of ALIGN bits.
2832 If VOLATILEP is false and SLOW_BYTE_ACCESS is false, we return the
2833 smallest mode meeting these conditions.
2835 If VOLATILEP is false and SLOW_BYTE_ACCESS is true, we return the
2836 largest mode (but a mode no wider than UNITS_PER_WORD) that meets
2839 If VOLATILEP is true the narrow_volatile_bitfields target hook is used to
2840 decide which of the above modes should be used. */
2843 get_best_mode (int bitsize
, int bitpos
,
2844 unsigned HOST_WIDE_INT bitregion_start
,
2845 unsigned HOST_WIDE_INT bitregion_end
,
2847 unsigned HOST_WIDE_INT largest_mode_bitsize
, bool volatilep
,
2848 scalar_int_mode
*best_mode
)
2850 bit_field_mode_iterator
iter (bitsize
, bitpos
, bitregion_start
,
2851 bitregion_end
, align
, volatilep
);
2852 scalar_int_mode mode
;
2854 while (iter
.next_mode (&mode
)
2855 /* ??? For historical reasons, reject modes that would normally
2856 receive greater alignment, even if unaligned accesses are
2857 acceptable. This has both advantages and disadvantages.
2858 Removing this check means that something like:
2860 struct s { unsigned int x; unsigned int y; };
2861 int f (struct s *s) { return s->x == 0 && s->y == 0; }
2863 can be implemented using a single load and compare on
2864 64-bit machines that have no alignment restrictions.
2865 For example, on powerpc64-linux-gnu, we would generate:
2887 However, accessing more than one field can make life harder
2888 for the gimple optimizers. For example, gcc.dg/vect/bb-slp-5.c
2889 has a series of unsigned short copies followed by a series of
2890 unsigned short comparisons. With this check, both the copies
2891 and comparisons remain 16-bit accesses and FRE is able
2892 to eliminate the latter. Without the check, the comparisons
2893 can be done using 2 64-bit operations, which FRE isn't able
2894 to handle in the same way.
2896 Either way, it would probably be worth disabling this check
2897 during expand. One particular example where removing the
2898 check would help is the get_best_mode call in store_bit_field.
2899 If we are given a memory bitregion of 128 bits that is aligned
2900 to a 64-bit boundary, and the bitfield we want to modify is
2901 in the second half of the bitregion, this check causes
2902 store_bitfield to turn the memory into a 64-bit reference
2903 to the _first_ half of the region. We later use
2904 adjust_bitfield_address to get a reference to the correct half,
2905 but doing so looks to adjust_bitfield_address as though we are
2906 moving past the end of the original object, so it drops the
2907 associated MEM_EXPR and MEM_OFFSET. Removing the check
2908 causes store_bit_field to keep a 128-bit memory reference,
2909 so that the final bitfield reference still has a MEM_EXPR
2911 && GET_MODE_ALIGNMENT (mode
) <= align
2912 && GET_MODE_BITSIZE (mode
) <= largest_mode_bitsize
)
2916 if (iter
.prefer_smaller_modes ())
2923 /* Gets minimal and maximal values for MODE (signed or unsigned depending on
2924 SIGN). The returned constants are made to be usable in TARGET_MODE. */
2927 get_mode_bounds (scalar_int_mode mode
, int sign
,
2928 scalar_int_mode target_mode
,
2929 rtx
*mmin
, rtx
*mmax
)
2931 unsigned size
= GET_MODE_PRECISION (mode
);
2932 unsigned HOST_WIDE_INT min_val
, max_val
;
2934 gcc_assert (size
<= HOST_BITS_PER_WIDE_INT
);
2936 /* Special case BImode, which has values 0 and STORE_FLAG_VALUE. */
2939 if (STORE_FLAG_VALUE
< 0)
2941 min_val
= STORE_FLAG_VALUE
;
2947 max_val
= STORE_FLAG_VALUE
;
2952 min_val
= -(HOST_WIDE_INT_1U
<< (size
- 1));
2953 max_val
= (HOST_WIDE_INT_1U
<< (size
- 1)) - 1;
2958 max_val
= (HOST_WIDE_INT_1U
<< (size
- 1) << 1) - 1;
2961 *mmin
= gen_int_mode (min_val
, target_mode
);
2962 *mmax
= gen_int_mode (max_val
, target_mode
);
2965 #include "gt-stor-layout.h"