1 /* C-compiler utilities for types and variables storage layout
2 Copyright (C) 1987-2018 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"
46 /* Data type for the expressions representing sizes of data types.
47 It is the first integer type laid out. */
48 tree sizetype_tab
[(int) stk_type_kind_last
];
50 /* If nonzero, this is an upper limit on alignment of structure fields.
51 The value is measured in bits. */
52 unsigned int maximum_field_alignment
= TARGET_DEFAULT_PACK_STRUCT
* BITS_PER_UNIT
;
54 static tree
self_referential_size (tree
);
55 static void finalize_record_size (record_layout_info
);
56 static void finalize_type_size (tree
);
57 static void place_union_field (record_layout_info
, tree
);
58 static int excess_unit_span (HOST_WIDE_INT
, HOST_WIDE_INT
, HOST_WIDE_INT
,
60 extern void debug_rli (record_layout_info
);
62 /* Given a size SIZE that may not be a constant, return a SAVE_EXPR
63 to serve as the actual size-expression for a type or decl. */
66 variable_size (tree size
)
69 if (TREE_CONSTANT (size
))
72 /* If the size is self-referential, we can't make a SAVE_EXPR (see
73 save_expr for the rationale). But we can do something else. */
74 if (CONTAINS_PLACEHOLDER_P (size
))
75 return self_referential_size (size
);
77 /* If we are in the global binding level, we can't make a SAVE_EXPR
78 since it may end up being shared across functions, so it is up
79 to the front-end to deal with this case. */
80 if (lang_hooks
.decls
.global_bindings_p ())
83 return save_expr (size
);
86 /* An array of functions used for self-referential size computation. */
87 static GTY(()) vec
<tree
, va_gc
> *size_functions
;
89 /* Return true if T is a self-referential component reference. */
92 self_referential_component_ref_p (tree t
)
94 if (TREE_CODE (t
) != COMPONENT_REF
)
97 while (REFERENCE_CLASS_P (t
))
98 t
= TREE_OPERAND (t
, 0);
100 return (TREE_CODE (t
) == PLACEHOLDER_EXPR
);
103 /* Similar to copy_tree_r but do not copy component references involving
104 PLACEHOLDER_EXPRs. These nodes are spotted in find_placeholder_in_expr
105 and substituted in substitute_in_expr. */
108 copy_self_referential_tree_r (tree
*tp
, int *walk_subtrees
, void *data
)
110 enum tree_code code
= TREE_CODE (*tp
);
112 /* Stop at types, decls, constants like copy_tree_r. */
113 if (TREE_CODE_CLASS (code
) == tcc_type
114 || TREE_CODE_CLASS (code
) == tcc_declaration
115 || TREE_CODE_CLASS (code
) == tcc_constant
)
121 /* This is the pattern built in ada/make_aligning_type. */
122 else if (code
== ADDR_EXPR
123 && TREE_CODE (TREE_OPERAND (*tp
, 0)) == PLACEHOLDER_EXPR
)
129 /* Default case: the component reference. */
130 else if (self_referential_component_ref_p (*tp
))
136 /* We're not supposed to have them in self-referential size trees
137 because we wouldn't properly control when they are evaluated.
138 However, not creating superfluous SAVE_EXPRs requires accurate
139 tracking of readonly-ness all the way down to here, which we
140 cannot always guarantee in practice. So punt in this case. */
141 else if (code
== SAVE_EXPR
)
142 return error_mark_node
;
144 else if (code
== STATEMENT_LIST
)
147 return copy_tree_r (tp
, walk_subtrees
, data
);
150 /* Given a SIZE expression that is self-referential, return an equivalent
151 expression to serve as the actual size expression for a type. */
154 self_referential_size (tree size
)
156 static unsigned HOST_WIDE_INT fnno
= 0;
157 vec
<tree
> self_refs
= vNULL
;
158 tree param_type_list
= NULL
, param_decl_list
= NULL
;
159 tree t
, ref
, return_type
, fntype
, fnname
, fndecl
;
162 vec
<tree
, va_gc
> *args
= NULL
;
164 /* Do not factor out simple operations. */
165 t
= skip_simple_constant_arithmetic (size
);
166 if (TREE_CODE (t
) == CALL_EXPR
|| self_referential_component_ref_p (t
))
169 /* Collect the list of self-references in the expression. */
170 find_placeholder_in_expr (size
, &self_refs
);
171 gcc_assert (self_refs
.length () > 0);
173 /* Obtain a private copy of the expression. */
175 if (walk_tree (&t
, copy_self_referential_tree_r
, NULL
, NULL
) != NULL_TREE
)
179 /* Build the parameter and argument lists in parallel; also
180 substitute the former for the latter in the expression. */
181 vec_alloc (args
, self_refs
.length ());
182 FOR_EACH_VEC_ELT (self_refs
, i
, ref
)
184 tree subst
, param_name
, param_type
, param_decl
;
188 /* We shouldn't have true variables here. */
189 gcc_assert (TREE_READONLY (ref
));
192 /* This is the pattern built in ada/make_aligning_type. */
193 else if (TREE_CODE (ref
) == ADDR_EXPR
)
195 /* Default case: the component reference. */
197 subst
= TREE_OPERAND (ref
, 1);
199 sprintf (buf
, "p%d", i
);
200 param_name
= get_identifier (buf
);
201 param_type
= TREE_TYPE (ref
);
203 = build_decl (input_location
, PARM_DECL
, param_name
, param_type
);
204 DECL_ARG_TYPE (param_decl
) = param_type
;
205 DECL_ARTIFICIAL (param_decl
) = 1;
206 TREE_READONLY (param_decl
) = 1;
208 size
= substitute_in_expr (size
, subst
, param_decl
);
210 param_type_list
= tree_cons (NULL_TREE
, param_type
, param_type_list
);
211 param_decl_list
= chainon (param_decl
, param_decl_list
);
212 args
->quick_push (ref
);
215 self_refs
.release ();
217 /* Append 'void' to indicate that the number of parameters is fixed. */
218 param_type_list
= tree_cons (NULL_TREE
, void_type_node
, param_type_list
);
220 /* The 3 lists have been created in reverse order. */
221 param_type_list
= nreverse (param_type_list
);
222 param_decl_list
= nreverse (param_decl_list
);
224 /* Build the function type. */
225 return_type
= TREE_TYPE (size
);
226 fntype
= build_function_type (return_type
, param_type_list
);
228 /* Build the function declaration. */
229 sprintf (buf
, "SZ" HOST_WIDE_INT_PRINT_UNSIGNED
, fnno
++);
230 fnname
= get_file_function_name (buf
);
231 fndecl
= build_decl (input_location
, FUNCTION_DECL
, fnname
, fntype
);
232 for (t
= param_decl_list
; t
; t
= DECL_CHAIN (t
))
233 DECL_CONTEXT (t
) = fndecl
;
234 DECL_ARGUMENTS (fndecl
) = param_decl_list
;
236 = build_decl (input_location
, RESULT_DECL
, 0, return_type
);
237 DECL_CONTEXT (DECL_RESULT (fndecl
)) = fndecl
;
239 /* The function has been created by the compiler and we don't
240 want to emit debug info for it. */
241 DECL_ARTIFICIAL (fndecl
) = 1;
242 DECL_IGNORED_P (fndecl
) = 1;
244 /* It is supposed to be "const" and never throw. */
245 TREE_READONLY (fndecl
) = 1;
246 TREE_NOTHROW (fndecl
) = 1;
248 /* We want it to be inlined when this is deemed profitable, as
249 well as discarded if every call has been integrated. */
250 DECL_DECLARED_INLINE_P (fndecl
) = 1;
252 /* It is made up of a unique return statement. */
253 DECL_INITIAL (fndecl
) = make_node (BLOCK
);
254 BLOCK_SUPERCONTEXT (DECL_INITIAL (fndecl
)) = fndecl
;
255 t
= build2 (MODIFY_EXPR
, return_type
, DECL_RESULT (fndecl
), size
);
256 DECL_SAVED_TREE (fndecl
) = build1 (RETURN_EXPR
, void_type_node
, t
);
257 TREE_STATIC (fndecl
) = 1;
259 /* Put it onto the list of size functions. */
260 vec_safe_push (size_functions
, fndecl
);
262 /* Replace the original expression with a call to the size function. */
263 return build_call_expr_loc_vec (UNKNOWN_LOCATION
, fndecl
, args
);
266 /* Take, queue and compile all the size functions. It is essential that
267 the size functions be gimplified at the very end of the compilation
268 in order to guarantee transparent handling of self-referential sizes.
269 Otherwise the GENERIC inliner would not be able to inline them back
270 at each of their call sites, thus creating artificial non-constant
271 size expressions which would trigger nasty problems later on. */
274 finalize_size_functions (void)
279 for (i
= 0; size_functions
&& size_functions
->iterate (i
, &fndecl
); i
++)
281 allocate_struct_function (fndecl
, false);
283 dump_function (TDI_original
, fndecl
);
285 /* As these functions are used to describe the layout of variable-length
286 structures, debug info generation needs their implementation. */
287 debug_hooks
->size_function (fndecl
);
288 gimplify_function_tree (fndecl
);
289 cgraph_node::finalize_function (fndecl
, false);
292 vec_free (size_functions
);
295 /* Return a machine mode of class MCLASS with SIZE bits of precision,
296 if one exists. The mode may have padding bits as well the SIZE
297 value bits. If LIMIT is nonzero, disregard modes wider than
298 MAX_FIXED_MODE_SIZE. */
301 mode_for_size (poly_uint64 size
, enum mode_class mclass
, int limit
)
306 if (limit
&& maybe_gt (size
, (unsigned int) MAX_FIXED_MODE_SIZE
))
307 return opt_machine_mode ();
309 /* Get the first mode which has this size, in the specified class. */
310 FOR_EACH_MODE_IN_CLASS (mode
, mclass
)
311 if (known_eq (GET_MODE_PRECISION (mode
), size
))
314 if (mclass
== MODE_INT
|| mclass
== MODE_PARTIAL_INT
)
315 for (i
= 0; i
< NUM_INT_N_ENTS
; i
++)
316 if (known_eq (int_n_data
[i
].bitsize
, size
)
317 && int_n_enabled_p
[i
])
318 return int_n_data
[i
].m
;
320 return opt_machine_mode ();
323 /* Similar, except passed a tree node. */
326 mode_for_size_tree (const_tree size
, enum mode_class mclass
, int limit
)
328 unsigned HOST_WIDE_INT uhwi
;
331 if (!tree_fits_uhwi_p (size
))
332 return opt_machine_mode ();
333 uhwi
= tree_to_uhwi (size
);
336 return opt_machine_mode ();
337 return mode_for_size (ui
, mclass
, limit
);
340 /* Return the narrowest mode of class MCLASS that contains at least
341 SIZE bits. Abort if no such mode exists. */
344 smallest_mode_for_size (poly_uint64 size
, enum mode_class mclass
)
346 machine_mode mode
= VOIDmode
;
349 /* Get the first mode which has at least this size, in the
351 FOR_EACH_MODE_IN_CLASS (mode
, mclass
)
352 if (known_ge (GET_MODE_PRECISION (mode
), size
))
355 gcc_assert (mode
!= VOIDmode
);
357 if (mclass
== MODE_INT
|| mclass
== MODE_PARTIAL_INT
)
358 for (i
= 0; i
< NUM_INT_N_ENTS
; i
++)
359 if (known_ge (int_n_data
[i
].bitsize
, size
)
360 && known_lt (int_n_data
[i
].bitsize
, GET_MODE_PRECISION (mode
))
361 && int_n_enabled_p
[i
])
362 mode
= int_n_data
[i
].m
;
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
:
386 case MODE_VECTOR_BOOL
:
387 case MODE_VECTOR_INT
:
388 case MODE_VECTOR_FLOAT
:
389 case MODE_VECTOR_FRACT
:
390 case MODE_VECTOR_ACCUM
:
391 case MODE_VECTOR_UFRACT
:
392 case MODE_VECTOR_UACCUM
:
393 case MODE_POINTER_BOUNDS
:
394 return int_mode_for_size (GET_MODE_BITSIZE (mode
), 0);
398 return opt_scalar_int_mode ();
408 /* Find a mode that can be used for efficient bitwise operations on MODE,
412 bitwise_mode_for_mode (machine_mode mode
)
414 /* Quick exit if we already have a suitable 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 poly_int64 bitsize
= GET_MODE_BITSIZE (mode
);
425 /* Try to replace complex modes with complex modes. In general we
426 expect both components to be processed independently, so we only
427 care whether there is a register for the inner mode. */
428 if (COMPLEX_MODE_P (mode
))
430 machine_mode trial
= mode
;
431 if ((GET_MODE_CLASS (trial
) == MODE_COMPLEX_INT
432 || mode_for_size (bitsize
, MODE_COMPLEX_INT
, false).exists (&trial
))
433 && have_regs_of_mode
[GET_MODE_INNER (trial
)])
437 /* Try to replace vector modes with vector modes. Also try using vector
438 modes if an integer mode would be too big. */
439 if (VECTOR_MODE_P (mode
)
440 || maybe_gt (bitsize
, MAX_FIXED_MODE_SIZE
))
442 machine_mode trial
= mode
;
443 if ((GET_MODE_CLASS (trial
) == MODE_VECTOR_INT
444 || mode_for_size (bitsize
, MODE_VECTOR_INT
, 0).exists (&trial
))
445 && have_regs_of_mode
[trial
]
446 && targetm
.vector_mode_supported_p (trial
))
450 /* Otherwise fall back on integers while honoring MAX_FIXED_MODE_SIZE. */
451 return mode_for_size (bitsize
, MODE_INT
, true);
454 /* Find a type that can be used for efficient bitwise operations on MODE.
455 Return null if no such mode exists. */
458 bitwise_type_for_mode (machine_mode mode
)
460 if (!bitwise_mode_for_mode (mode
).exists (&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 NUNITS
477 elements of mode INNERMODE, if one exists. The returned mode can be
478 either an integer mode or a vector mode. */
481 mode_for_vector (scalar_mode innermode
, poly_uint64 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 (known_eq (GET_MODE_NUNITS (mode
), nunits
)
503 && GET_MODE_INNER (mode
) == innermode
)
506 /* For integers, try mapping it to a same-sized scalar mode. */
507 if (GET_MODE_CLASS (innermode
) == MODE_INT
)
509 poly_uint64 nbits
= nunits
* GET_MODE_BITSIZE (innermode
);
510 if (int_mode_for_size (nbits
, 0).exists (&mode
)
511 && have_regs_of_mode
[mode
])
515 return opt_machine_mode ();
518 /* Return the mode for a vector that has NUNITS integer elements of
519 INT_BITS bits each, if such a mode exists. The mode can be either
520 an integer mode or a vector mode. */
523 mode_for_int_vector (unsigned int int_bits
, poly_uint64 nunits
)
525 scalar_int_mode int_mode
;
526 machine_mode vec_mode
;
527 if (int_mode_for_size (int_bits
, 0).exists (&int_mode
)
528 && mode_for_vector (int_mode
, nunits
).exists (&vec_mode
))
530 return opt_machine_mode ();
533 /* Return the alignment of MODE. This will be bounded by 1 and
534 BIGGEST_ALIGNMENT. */
537 get_mode_alignment (machine_mode mode
)
539 return MIN (BIGGEST_ALIGNMENT
, MAX (1, mode_base_align
[mode
]*BITS_PER_UNIT
));
542 /* Return the natural mode of an array, given that it is SIZE bytes in
543 total and has elements of type ELEM_TYPE. */
546 mode_for_array (tree elem_type
, tree size
)
549 unsigned HOST_WIDE_INT int_size
, int_elem_size
;
552 /* One-element arrays get the component type's mode. */
553 elem_size
= TYPE_SIZE (elem_type
);
554 if (simple_cst_equal (size
, elem_size
))
555 return TYPE_MODE (elem_type
);
558 if (tree_fits_uhwi_p (size
) && tree_fits_uhwi_p (elem_size
))
560 int_size
= tree_to_uhwi (size
);
561 int_elem_size
= tree_to_uhwi (elem_size
);
562 if (int_elem_size
> 0
563 && int_size
% int_elem_size
== 0
564 && targetm
.array_mode_supported_p (TYPE_MODE (elem_type
),
565 int_size
/ int_elem_size
))
568 return mode_for_size_tree (size
, MODE_INT
, limit_p
).else_blk ();
571 /* Subroutine of layout_decl: Force alignment required for the data type.
572 But if the decl itself wants greater alignment, don't override that. */
575 do_type_align (tree type
, tree decl
)
577 if (TYPE_ALIGN (type
) > DECL_ALIGN (decl
))
579 SET_DECL_ALIGN (decl
, TYPE_ALIGN (type
));
580 if (TREE_CODE (decl
) == FIELD_DECL
)
581 DECL_USER_ALIGN (decl
) = TYPE_USER_ALIGN (type
);
583 if (TYPE_WARN_IF_NOT_ALIGN (type
) > DECL_WARN_IF_NOT_ALIGN (decl
))
584 SET_DECL_WARN_IF_NOT_ALIGN (decl
, TYPE_WARN_IF_NOT_ALIGN (type
));
587 /* Set the size, mode and alignment of a ..._DECL node.
588 TYPE_DECL does need this for C++.
589 Note that LABEL_DECL and CONST_DECL nodes do not need this,
590 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
591 Don't call layout_decl for them.
593 KNOWN_ALIGN is the amount of alignment we can assume this
594 decl has with no special effort. It is relevant only for FIELD_DECLs
595 and depends on the previous fields.
596 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
597 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
598 the record will be aligned to suit. */
601 layout_decl (tree decl
, unsigned int known_align
)
603 tree type
= TREE_TYPE (decl
);
604 enum tree_code code
= TREE_CODE (decl
);
606 location_t loc
= DECL_SOURCE_LOCATION (decl
);
608 if (code
== CONST_DECL
)
611 gcc_assert (code
== VAR_DECL
|| code
== PARM_DECL
|| code
== RESULT_DECL
612 || code
== TYPE_DECL
|| code
== FIELD_DECL
);
614 rtl
= DECL_RTL_IF_SET (decl
);
616 if (type
== error_mark_node
)
617 type
= void_type_node
;
619 /* Usually the size and mode come from the data type without change,
620 however, the front-end may set the explicit width of the field, so its
621 size may not be the same as the size of its type. This happens with
622 bitfields, of course (an `int' bitfield may be only 2 bits, say), but it
623 also happens with other fields. For example, the C++ front-end creates
624 zero-sized fields corresponding to empty base classes, and depends on
625 layout_type setting DECL_FIELD_BITPOS correctly for the field. Set the
626 size in bytes from the size in bits. If we have already set the mode,
627 don't set it again since we can be called twice for FIELD_DECLs. */
629 DECL_UNSIGNED (decl
) = TYPE_UNSIGNED (type
);
630 if (DECL_MODE (decl
) == VOIDmode
)
631 SET_DECL_MODE (decl
, TYPE_MODE (type
));
633 if (DECL_SIZE (decl
) == 0)
635 DECL_SIZE (decl
) = TYPE_SIZE (type
);
636 DECL_SIZE_UNIT (decl
) = TYPE_SIZE_UNIT (type
);
638 else if (DECL_SIZE_UNIT (decl
) == 0)
639 DECL_SIZE_UNIT (decl
)
640 = fold_convert_loc (loc
, sizetype
,
641 size_binop_loc (loc
, CEIL_DIV_EXPR
, DECL_SIZE (decl
),
644 if (code
!= FIELD_DECL
)
645 /* For non-fields, update the alignment from the type. */
646 do_type_align (type
, decl
);
648 /* For fields, it's a bit more complicated... */
650 bool old_user_align
= DECL_USER_ALIGN (decl
);
651 bool zero_bitfield
= false;
652 bool packed_p
= DECL_PACKED (decl
);
655 if (DECL_BIT_FIELD (decl
))
657 DECL_BIT_FIELD_TYPE (decl
) = type
;
659 /* A zero-length bit-field affects the alignment of the next
660 field. In essence such bit-fields are not influenced by
661 any packing due to #pragma pack or attribute packed. */
662 if (integer_zerop (DECL_SIZE (decl
))
663 && ! targetm
.ms_bitfield_layout_p (DECL_FIELD_CONTEXT (decl
)))
665 zero_bitfield
= true;
667 if (PCC_BITFIELD_TYPE_MATTERS
)
668 do_type_align (type
, decl
);
671 #ifdef EMPTY_FIELD_BOUNDARY
672 if (EMPTY_FIELD_BOUNDARY
> DECL_ALIGN (decl
))
674 SET_DECL_ALIGN (decl
, EMPTY_FIELD_BOUNDARY
);
675 DECL_USER_ALIGN (decl
) = 0;
681 /* See if we can use an ordinary integer mode for a bit-field.
682 Conditions are: a fixed size that is correct for another mode,
683 occupying a complete byte or bytes on proper boundary. */
684 if (TYPE_SIZE (type
) != 0
685 && TREE_CODE (TYPE_SIZE (type
)) == INTEGER_CST
686 && GET_MODE_CLASS (TYPE_MODE (type
)) == MODE_INT
)
689 if (mode_for_size_tree (DECL_SIZE (decl
),
690 MODE_INT
, 1).exists (&xmode
))
692 unsigned int xalign
= GET_MODE_ALIGNMENT (xmode
);
693 if (!(xalign
> BITS_PER_UNIT
&& DECL_PACKED (decl
))
694 && (known_align
== 0 || known_align
>= xalign
))
696 SET_DECL_ALIGN (decl
, MAX (xalign
, DECL_ALIGN (decl
)));
697 SET_DECL_MODE (decl
, xmode
);
698 DECL_BIT_FIELD (decl
) = 0;
703 /* Turn off DECL_BIT_FIELD if we won't need it set. */
704 if (TYPE_MODE (type
) == BLKmode
&& DECL_MODE (decl
) == BLKmode
705 && known_align
>= TYPE_ALIGN (type
)
706 && DECL_ALIGN (decl
) >= TYPE_ALIGN (type
))
707 DECL_BIT_FIELD (decl
) = 0;
709 else if (packed_p
&& DECL_USER_ALIGN (decl
))
710 /* Don't touch DECL_ALIGN. For other packed fields, go ahead and
711 round up; we'll reduce it again below. We want packing to
712 supersede USER_ALIGN inherited from the type, but defer to
713 alignment explicitly specified on the field decl. */;
715 do_type_align (type
, decl
);
717 /* If the field is packed and not explicitly aligned, give it the
718 minimum alignment. Note that do_type_align may set
719 DECL_USER_ALIGN, so we need to check old_user_align instead. */
722 SET_DECL_ALIGN (decl
, MIN (DECL_ALIGN (decl
), BITS_PER_UNIT
));
724 if (! packed_p
&& ! DECL_USER_ALIGN (decl
))
726 /* Some targets (i.e. i386, VMS) limit struct field alignment
727 to a lower boundary than alignment of variables unless
728 it was overridden by attribute aligned. */
729 #ifdef BIGGEST_FIELD_ALIGNMENT
730 SET_DECL_ALIGN (decl
, MIN (DECL_ALIGN (decl
),
731 (unsigned) BIGGEST_FIELD_ALIGNMENT
));
733 #ifdef ADJUST_FIELD_ALIGN
734 SET_DECL_ALIGN (decl
, ADJUST_FIELD_ALIGN (decl
, TREE_TYPE (decl
),
740 mfa
= initial_max_fld_align
* BITS_PER_UNIT
;
742 mfa
= maximum_field_alignment
;
743 /* Should this be controlled by DECL_USER_ALIGN, too? */
745 SET_DECL_ALIGN (decl
, MIN (DECL_ALIGN (decl
), mfa
));
748 /* Evaluate nonconstant size only once, either now or as soon as safe. */
749 if (DECL_SIZE (decl
) != 0 && TREE_CODE (DECL_SIZE (decl
)) != INTEGER_CST
)
750 DECL_SIZE (decl
) = variable_size (DECL_SIZE (decl
));
751 if (DECL_SIZE_UNIT (decl
) != 0
752 && TREE_CODE (DECL_SIZE_UNIT (decl
)) != INTEGER_CST
)
753 DECL_SIZE_UNIT (decl
) = variable_size (DECL_SIZE_UNIT (decl
));
755 /* If requested, warn about definitions of large data objects. */
757 && (code
== VAR_DECL
|| code
== PARM_DECL
)
758 && ! DECL_EXTERNAL (decl
))
760 tree size
= DECL_SIZE_UNIT (decl
);
762 if (size
!= 0 && TREE_CODE (size
) == INTEGER_CST
763 && compare_tree_int (size
, larger_than_size
) > 0)
765 int size_as_int
= TREE_INT_CST_LOW (size
);
767 if (compare_tree_int (size
, size_as_int
) == 0)
768 warning (OPT_Wlarger_than_
, "size of %q+D is %d bytes", decl
, size_as_int
);
770 warning (OPT_Wlarger_than_
, "size of %q+D is larger than %wd bytes",
771 decl
, larger_than_size
);
775 /* If the RTL was already set, update its mode and mem attributes. */
778 PUT_MODE (rtl
, DECL_MODE (decl
));
779 SET_DECL_RTL (decl
, 0);
781 set_mem_attributes (rtl
, decl
, 1);
782 SET_DECL_RTL (decl
, rtl
);
786 /* Given a VAR_DECL, PARM_DECL, RESULT_DECL, or FIELD_DECL, clears the
787 results of a previous call to layout_decl and calls it again. */
790 relayout_decl (tree decl
)
792 DECL_SIZE (decl
) = DECL_SIZE_UNIT (decl
) = 0;
793 SET_DECL_MODE (decl
, VOIDmode
);
794 if (!DECL_USER_ALIGN (decl
))
795 SET_DECL_ALIGN (decl
, 0);
796 if (DECL_RTL_SET_P (decl
))
797 SET_DECL_RTL (decl
, 0);
799 layout_decl (decl
, 0);
802 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
803 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
804 is to be passed to all other layout functions for this record. It is the
805 responsibility of the caller to call `free' for the storage returned.
806 Note that garbage collection is not permitted until we finish laying
810 start_record_layout (tree t
)
812 record_layout_info rli
= XNEW (struct record_layout_info_s
);
816 /* If the type has a minimum specified alignment (via an attribute
817 declaration, for example) use it -- otherwise, start with a
818 one-byte alignment. */
819 rli
->record_align
= MAX (BITS_PER_UNIT
, TYPE_ALIGN (t
));
820 rli
->unpacked_align
= rli
->record_align
;
821 rli
->offset_align
= MAX (rli
->record_align
, BIGGEST_ALIGNMENT
);
823 #ifdef STRUCTURE_SIZE_BOUNDARY
824 /* Packed structures don't need to have minimum size. */
825 if (! TYPE_PACKED (t
))
829 /* #pragma pack overrides STRUCTURE_SIZE_BOUNDARY. */
830 tmp
= (unsigned) STRUCTURE_SIZE_BOUNDARY
;
831 if (maximum_field_alignment
!= 0)
832 tmp
= MIN (tmp
, maximum_field_alignment
);
833 rli
->record_align
= MAX (rli
->record_align
, tmp
);
837 rli
->offset
= size_zero_node
;
838 rli
->bitpos
= bitsize_zero_node
;
840 rli
->pending_statics
= 0;
841 rli
->packed_maybe_necessary
= 0;
842 rli
->remaining_in_alignment
= 0;
847 /* Fold sizetype value X to bitsizetype, given that X represents a type
851 bits_from_bytes (tree x
)
853 if (POLY_INT_CST_P (x
))
854 /* The runtime calculation isn't allowed to overflow sizetype;
855 increasing the runtime values must always increase the size
856 or offset of the object. This means that the object imposes
857 a maximum value on the runtime parameters, but we don't record
859 return build_poly_int_cst
861 poly_wide_int::from (poly_int_cst_value (x
),
862 TYPE_PRECISION (bitsizetype
),
863 TYPE_SIGN (TREE_TYPE (x
))));
864 x
= fold_convert (bitsizetype
, x
);
865 gcc_checking_assert (x
);
869 /* Return the combined bit position for the byte offset OFFSET and the
872 These functions operate on byte and bit positions present in FIELD_DECLs
873 and assume that these expressions result in no (intermediate) overflow.
874 This assumption is necessary to fold the expressions as much as possible,
875 so as to avoid creating artificially variable-sized types in languages
876 supporting variable-sized types like Ada. */
879 bit_from_pos (tree offset
, tree bitpos
)
881 return size_binop (PLUS_EXPR
, bitpos
,
882 size_binop (MULT_EXPR
, bits_from_bytes (offset
),
886 /* Return the combined truncated byte position for the byte offset OFFSET and
887 the bit position BITPOS. */
890 byte_from_pos (tree offset
, tree bitpos
)
893 if (TREE_CODE (bitpos
) == MULT_EXPR
894 && tree_int_cst_equal (TREE_OPERAND (bitpos
, 1), bitsize_unit_node
))
895 bytepos
= TREE_OPERAND (bitpos
, 0);
897 bytepos
= size_binop (TRUNC_DIV_EXPR
, bitpos
, bitsize_unit_node
);
898 return size_binop (PLUS_EXPR
, offset
, fold_convert (sizetype
, bytepos
));
901 /* Split the bit position POS into a byte offset *POFFSET and a bit
902 position *PBITPOS with the byte offset aligned to OFF_ALIGN bits. */
905 pos_from_bit (tree
*poffset
, tree
*pbitpos
, unsigned int off_align
,
908 tree toff_align
= bitsize_int (off_align
);
909 if (TREE_CODE (pos
) == MULT_EXPR
910 && tree_int_cst_equal (TREE_OPERAND (pos
, 1), toff_align
))
912 *poffset
= size_binop (MULT_EXPR
,
913 fold_convert (sizetype
, TREE_OPERAND (pos
, 0)),
914 size_int (off_align
/ BITS_PER_UNIT
));
915 *pbitpos
= bitsize_zero_node
;
919 *poffset
= size_binop (MULT_EXPR
,
920 fold_convert (sizetype
,
921 size_binop (FLOOR_DIV_EXPR
, pos
,
923 size_int (off_align
/ BITS_PER_UNIT
));
924 *pbitpos
= size_binop (FLOOR_MOD_EXPR
, pos
, toff_align
);
928 /* Given a pointer to bit and byte offsets and an offset alignment,
929 normalize the offsets so they are within the alignment. */
932 normalize_offset (tree
*poffset
, tree
*pbitpos
, unsigned int off_align
)
934 /* If the bit position is now larger than it should be, adjust it
936 if (compare_tree_int (*pbitpos
, off_align
) >= 0)
939 pos_from_bit (&offset
, &bitpos
, off_align
, *pbitpos
);
940 *poffset
= size_binop (PLUS_EXPR
, *poffset
, offset
);
945 /* Print debugging information about the information in RLI. */
948 debug_rli (record_layout_info rli
)
950 print_node_brief (stderr
, "type", rli
->t
, 0);
951 print_node_brief (stderr
, "\noffset", rli
->offset
, 0);
952 print_node_brief (stderr
, " bitpos", rli
->bitpos
, 0);
954 fprintf (stderr
, "\naligns: rec = %u, unpack = %u, off = %u\n",
955 rli
->record_align
, rli
->unpacked_align
,
958 /* The ms_struct code is the only that uses this. */
959 if (targetm
.ms_bitfield_layout_p (rli
->t
))
960 fprintf (stderr
, "remaining in alignment = %u\n", rli
->remaining_in_alignment
);
962 if (rli
->packed_maybe_necessary
)
963 fprintf (stderr
, "packed may be necessary\n");
965 if (!vec_safe_is_empty (rli
->pending_statics
))
967 fprintf (stderr
, "pending statics:\n");
968 debug (rli
->pending_statics
);
972 /* Given an RLI with a possibly-incremented BITPOS, adjust OFFSET and
973 BITPOS if necessary to keep BITPOS below OFFSET_ALIGN. */
976 normalize_rli (record_layout_info rli
)
978 normalize_offset (&rli
->offset
, &rli
->bitpos
, rli
->offset_align
);
981 /* Returns the size in bytes allocated so far. */
984 rli_size_unit_so_far (record_layout_info rli
)
986 return byte_from_pos (rli
->offset
, rli
->bitpos
);
989 /* Returns the size in bits allocated so far. */
992 rli_size_so_far (record_layout_info rli
)
994 return bit_from_pos (rli
->offset
, rli
->bitpos
);
997 /* FIELD is about to be added to RLI->T. The alignment (in bits) of
998 the next available location within the record is given by KNOWN_ALIGN.
999 Update the variable alignment fields in RLI, and return the alignment
1000 to give the FIELD. */
1003 update_alignment_for_field (record_layout_info rli
, tree field
,
1004 unsigned int known_align
)
1006 /* The alignment required for FIELD. */
1007 unsigned int desired_align
;
1008 /* The type of this field. */
1009 tree type
= TREE_TYPE (field
);
1010 /* True if the field was explicitly aligned by the user. */
1014 /* Do not attempt to align an ERROR_MARK node */
1015 if (TREE_CODE (type
) == ERROR_MARK
)
1018 /* Lay out the field so we know what alignment it needs. */
1019 layout_decl (field
, known_align
);
1020 desired_align
= DECL_ALIGN (field
);
1021 user_align
= DECL_USER_ALIGN (field
);
1023 is_bitfield
= (type
!= error_mark_node
1024 && DECL_BIT_FIELD_TYPE (field
)
1025 && ! integer_zerop (TYPE_SIZE (type
)));
1027 /* Record must have at least as much alignment as any field.
1028 Otherwise, the alignment of the field within the record is
1030 if (targetm
.ms_bitfield_layout_p (rli
->t
))
1032 /* Here, the alignment of the underlying type of a bitfield can
1033 affect the alignment of a record; even a zero-sized field
1034 can do this. The alignment should be to the alignment of
1035 the type, except that for zero-size bitfields this only
1036 applies if there was an immediately prior, nonzero-size
1037 bitfield. (That's the way it is, experimentally.) */
1038 if ((!is_bitfield
&& !DECL_PACKED (field
))
1039 || ((DECL_SIZE (field
) == NULL_TREE
1040 || !integer_zerop (DECL_SIZE (field
)))
1041 ? !DECL_PACKED (field
)
1043 && DECL_BIT_FIELD_TYPE (rli
->prev_field
)
1044 && ! integer_zerop (DECL_SIZE (rli
->prev_field
)))))
1046 unsigned int type_align
= TYPE_ALIGN (type
);
1047 type_align
= MAX (type_align
, desired_align
);
1048 if (maximum_field_alignment
!= 0)
1049 type_align
= MIN (type_align
, maximum_field_alignment
);
1050 rli
->record_align
= MAX (rli
->record_align
, type_align
);
1051 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
1054 else if (is_bitfield
&& PCC_BITFIELD_TYPE_MATTERS
)
1056 /* Named bit-fields cause the entire structure to have the
1057 alignment implied by their type. Some targets also apply the same
1058 rules to unnamed bitfields. */
1059 if (DECL_NAME (field
) != 0
1060 || targetm
.align_anon_bitfield ())
1062 unsigned int type_align
= TYPE_ALIGN (type
);
1064 #ifdef ADJUST_FIELD_ALIGN
1065 if (! TYPE_USER_ALIGN (type
))
1066 type_align
= ADJUST_FIELD_ALIGN (field
, type
, type_align
);
1069 /* Targets might chose to handle unnamed and hence possibly
1070 zero-width bitfield. Those are not influenced by #pragmas
1071 or packed attributes. */
1072 if (integer_zerop (DECL_SIZE (field
)))
1074 if (initial_max_fld_align
)
1075 type_align
= MIN (type_align
,
1076 initial_max_fld_align
* BITS_PER_UNIT
);
1078 else if (maximum_field_alignment
!= 0)
1079 type_align
= MIN (type_align
, maximum_field_alignment
);
1080 else if (DECL_PACKED (field
))
1081 type_align
= MIN (type_align
, BITS_PER_UNIT
);
1083 /* The alignment of the record is increased to the maximum
1084 of the current alignment, the alignment indicated on the
1085 field (i.e., the alignment specified by an __aligned__
1086 attribute), and the alignment indicated by the type of
1088 rli
->record_align
= MAX (rli
->record_align
, desired_align
);
1089 rli
->record_align
= MAX (rli
->record_align
, type_align
);
1092 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
1093 user_align
|= TYPE_USER_ALIGN (type
);
1098 rli
->record_align
= MAX (rli
->record_align
, desired_align
);
1099 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
1102 TYPE_USER_ALIGN (rli
->t
) |= user_align
;
1104 return desired_align
;
1107 /* Issue a warning if the record alignment, RECORD_ALIGN, is less than
1108 the field alignment of FIELD or FIELD isn't aligned. */
1111 handle_warn_if_not_align (tree field
, unsigned int record_align
)
1113 tree type
= TREE_TYPE (field
);
1115 if (type
== error_mark_node
)
1118 unsigned int warn_if_not_align
= 0;
1122 if (warn_if_not_aligned
)
1124 warn_if_not_align
= DECL_WARN_IF_NOT_ALIGN (field
);
1125 if (!warn_if_not_align
)
1126 warn_if_not_align
= TYPE_WARN_IF_NOT_ALIGN (type
);
1127 if (warn_if_not_align
)
1128 opt_w
= OPT_Wif_not_aligned
;
1131 if (!warn_if_not_align
1132 && warn_packed_not_aligned
1133 && lookup_attribute ("aligned", TYPE_ATTRIBUTES (type
)))
1135 warn_if_not_align
= TYPE_ALIGN (type
);
1136 opt_w
= OPT_Wpacked_not_aligned
;
1139 if (!warn_if_not_align
)
1142 tree context
= DECL_CONTEXT (field
);
1144 warn_if_not_align
/= BITS_PER_UNIT
;
1145 record_align
/= BITS_PER_UNIT
;
1146 if ((record_align
% warn_if_not_align
) != 0)
1147 warning (opt_w
, "alignment %u of %qT is less than %u",
1148 record_align
, context
, warn_if_not_align
);
1150 unsigned HOST_WIDE_INT off
1151 = (tree_to_uhwi (DECL_FIELD_OFFSET (field
))
1152 + tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field
)) / BITS_PER_UNIT
);
1153 if ((off
% warn_if_not_align
) != 0)
1154 warning (opt_w
, "%q+D offset %wu in %qT isn't aligned to %u",
1155 field
, off
, context
, warn_if_not_align
);
1158 /* Called from place_field to handle unions. */
1161 place_union_field (record_layout_info rli
, tree field
)
1163 update_alignment_for_field (rli
, field
, /*known_align=*/0);
1165 DECL_FIELD_OFFSET (field
) = size_zero_node
;
1166 DECL_FIELD_BIT_OFFSET (field
) = bitsize_zero_node
;
1167 SET_DECL_OFFSET_ALIGN (field
, BIGGEST_ALIGNMENT
);
1168 handle_warn_if_not_align (field
, rli
->record_align
);
1170 /* If this is an ERROR_MARK return *after* having set the
1171 field at the start of the union. This helps when parsing
1173 if (TREE_CODE (TREE_TYPE (field
)) == ERROR_MARK
)
1176 if (AGGREGATE_TYPE_P (TREE_TYPE (field
))
1177 && TYPE_TYPELESS_STORAGE (TREE_TYPE (field
)))
1178 TYPE_TYPELESS_STORAGE (rli
->t
) = 1;
1180 /* We assume the union's size will be a multiple of a byte so we don't
1181 bother with BITPOS. */
1182 if (TREE_CODE (rli
->t
) == UNION_TYPE
)
1183 rli
->offset
= size_binop (MAX_EXPR
, rli
->offset
, DECL_SIZE_UNIT (field
));
1184 else if (TREE_CODE (rli
->t
) == QUAL_UNION_TYPE
)
1185 rli
->offset
= fold_build3 (COND_EXPR
, sizetype
, DECL_QUALIFIER (field
),
1186 DECL_SIZE_UNIT (field
), rli
->offset
);
1189 /* A bitfield of SIZE with a required access alignment of ALIGN is allocated
1190 at BYTE_OFFSET / BIT_OFFSET. Return nonzero if the field would span more
1191 units of alignment than the underlying TYPE. */
1193 excess_unit_span (HOST_WIDE_INT byte_offset
, HOST_WIDE_INT bit_offset
,
1194 HOST_WIDE_INT size
, HOST_WIDE_INT align
, tree type
)
1196 /* Note that the calculation of OFFSET might overflow; we calculate it so
1197 that we still get the right result as long as ALIGN is a power of two. */
1198 unsigned HOST_WIDE_INT offset
= byte_offset
* BITS_PER_UNIT
+ bit_offset
;
1200 offset
= offset
% align
;
1201 return ((offset
+ size
+ align
- 1) / align
1202 > tree_to_uhwi (TYPE_SIZE (type
)) / align
);
1205 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
1206 is a FIELD_DECL to be added after those fields already present in
1207 T. (FIELD is not actually added to the TYPE_FIELDS list here;
1208 callers that desire that behavior must manually perform that step.) */
1211 place_field (record_layout_info rli
, tree field
)
1213 /* The alignment required for FIELD. */
1214 unsigned int desired_align
;
1215 /* The alignment FIELD would have if we just dropped it into the
1216 record as it presently stands. */
1217 unsigned int known_align
;
1218 unsigned int actual_align
;
1219 /* The type of this field. */
1220 tree type
= TREE_TYPE (field
);
1222 gcc_assert (TREE_CODE (field
) != ERROR_MARK
);
1224 /* If FIELD is static, then treat it like a separate variable, not
1225 really like a structure field. If it is a FUNCTION_DECL, it's a
1226 method. In both cases, all we do is lay out the decl, and we do
1227 it *after* the record is laid out. */
1230 vec_safe_push (rli
->pending_statics
, field
);
1234 /* Enumerators and enum types which are local to this class need not
1235 be laid out. Likewise for initialized constant fields. */
1236 else if (TREE_CODE (field
) != FIELD_DECL
)
1239 /* Unions are laid out very differently than records, so split
1240 that code off to another function. */
1241 else if (TREE_CODE (rli
->t
) != RECORD_TYPE
)
1243 place_union_field (rli
, field
);
1247 else if (TREE_CODE (type
) == ERROR_MARK
)
1249 /* Place this field at the current allocation position, so we
1250 maintain monotonicity. */
1251 DECL_FIELD_OFFSET (field
) = rli
->offset
;
1252 DECL_FIELD_BIT_OFFSET (field
) = rli
->bitpos
;
1253 SET_DECL_OFFSET_ALIGN (field
, rli
->offset_align
);
1254 handle_warn_if_not_align (field
, rli
->record_align
);
1258 if (AGGREGATE_TYPE_P (type
)
1259 && TYPE_TYPELESS_STORAGE (type
))
1260 TYPE_TYPELESS_STORAGE (rli
->t
) = 1;
1262 /* Work out the known alignment so far. Note that A & (-A) is the
1263 value of the least-significant bit in A that is one. */
1264 if (! integer_zerop (rli
->bitpos
))
1265 known_align
= least_bit_hwi (tree_to_uhwi (rli
->bitpos
));
1266 else if (integer_zerop (rli
->offset
))
1268 else if (tree_fits_uhwi_p (rli
->offset
))
1269 known_align
= (BITS_PER_UNIT
1270 * least_bit_hwi (tree_to_uhwi (rli
->offset
)));
1272 known_align
= rli
->offset_align
;
1274 desired_align
= update_alignment_for_field (rli
, field
, known_align
);
1275 if (known_align
== 0)
1276 known_align
= MAX (BIGGEST_ALIGNMENT
, rli
->record_align
);
1278 if (warn_packed
&& DECL_PACKED (field
))
1280 if (known_align
>= TYPE_ALIGN (type
))
1282 if (TYPE_ALIGN (type
) > desired_align
)
1284 if (STRICT_ALIGNMENT
)
1285 warning (OPT_Wattributes
, "packed attribute causes "
1286 "inefficient alignment for %q+D", field
);
1287 /* Don't warn if DECL_PACKED was set by the type. */
1288 else if (!TYPE_PACKED (rli
->t
))
1289 warning (OPT_Wattributes
, "packed attribute is "
1290 "unnecessary for %q+D", field
);
1294 rli
->packed_maybe_necessary
= 1;
1297 /* Does this field automatically have alignment it needs by virtue
1298 of the fields that precede it and the record's own alignment? */
1299 if (known_align
< desired_align
)
1301 /* No, we need to skip space before this field.
1302 Bump the cumulative size to multiple of field alignment. */
1304 if (!targetm
.ms_bitfield_layout_p (rli
->t
)
1305 && DECL_SOURCE_LOCATION (field
) != BUILTINS_LOCATION
)
1306 warning (OPT_Wpadded
, "padding struct to align %q+D", field
);
1308 /* If the alignment is still within offset_align, just align
1309 the bit position. */
1310 if (desired_align
< rli
->offset_align
)
1311 rli
->bitpos
= round_up (rli
->bitpos
, desired_align
);
1314 /* First adjust OFFSET by the partial bits, then align. */
1316 = size_binop (PLUS_EXPR
, rli
->offset
,
1317 fold_convert (sizetype
,
1318 size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
1319 bitsize_unit_node
)));
1320 rli
->bitpos
= bitsize_zero_node
;
1322 rli
->offset
= round_up (rli
->offset
, desired_align
/ BITS_PER_UNIT
);
1325 if (! TREE_CONSTANT (rli
->offset
))
1326 rli
->offset_align
= desired_align
;
1327 if (targetm
.ms_bitfield_layout_p (rli
->t
))
1328 rli
->prev_field
= NULL
;
1331 /* Handle compatibility with PCC. Note that if the record has any
1332 variable-sized fields, we need not worry about compatibility. */
1333 if (PCC_BITFIELD_TYPE_MATTERS
1334 && ! targetm
.ms_bitfield_layout_p (rli
->t
)
1335 && TREE_CODE (field
) == FIELD_DECL
1336 && type
!= error_mark_node
1337 && DECL_BIT_FIELD (field
)
1338 && (! DECL_PACKED (field
)
1339 /* Enter for these packed fields only to issue a warning. */
1340 || TYPE_ALIGN (type
) <= BITS_PER_UNIT
)
1341 && maximum_field_alignment
== 0
1342 && ! integer_zerop (DECL_SIZE (field
))
1343 && tree_fits_uhwi_p (DECL_SIZE (field
))
1344 && tree_fits_uhwi_p (rli
->offset
)
1345 && tree_fits_uhwi_p (TYPE_SIZE (type
)))
1347 unsigned int type_align
= TYPE_ALIGN (type
);
1348 tree dsize
= DECL_SIZE (field
);
1349 HOST_WIDE_INT field_size
= tree_to_uhwi (dsize
);
1350 HOST_WIDE_INT offset
= tree_to_uhwi (rli
->offset
);
1351 HOST_WIDE_INT bit_offset
= tree_to_shwi (rli
->bitpos
);
1353 #ifdef ADJUST_FIELD_ALIGN
1354 if (! TYPE_USER_ALIGN (type
))
1355 type_align
= ADJUST_FIELD_ALIGN (field
, type
, type_align
);
1358 /* A bit field may not span more units of alignment of its type
1359 than its type itself. Advance to next boundary if necessary. */
1360 if (excess_unit_span (offset
, bit_offset
, field_size
, type_align
, type
))
1362 if (DECL_PACKED (field
))
1364 if (warn_packed_bitfield_compat
== 1)
1367 "offset of packed bit-field %qD has changed in GCC 4.4",
1371 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1374 if (! DECL_PACKED (field
))
1375 TYPE_USER_ALIGN (rli
->t
) |= TYPE_USER_ALIGN (type
);
1377 SET_TYPE_WARN_IF_NOT_ALIGN (rli
->t
,
1378 TYPE_WARN_IF_NOT_ALIGN (type
));
1381 #ifdef BITFIELD_NBYTES_LIMITED
1382 if (BITFIELD_NBYTES_LIMITED
1383 && ! targetm
.ms_bitfield_layout_p (rli
->t
)
1384 && TREE_CODE (field
) == FIELD_DECL
1385 && type
!= error_mark_node
1386 && DECL_BIT_FIELD_TYPE (field
)
1387 && ! DECL_PACKED (field
)
1388 && ! integer_zerop (DECL_SIZE (field
))
1389 && tree_fits_uhwi_p (DECL_SIZE (field
))
1390 && tree_fits_uhwi_p (rli
->offset
)
1391 && tree_fits_uhwi_p (TYPE_SIZE (type
)))
1393 unsigned int type_align
= TYPE_ALIGN (type
);
1394 tree dsize
= DECL_SIZE (field
);
1395 HOST_WIDE_INT field_size
= tree_to_uhwi (dsize
);
1396 HOST_WIDE_INT offset
= tree_to_uhwi (rli
->offset
);
1397 HOST_WIDE_INT bit_offset
= tree_to_shwi (rli
->bitpos
);
1399 #ifdef ADJUST_FIELD_ALIGN
1400 if (! TYPE_USER_ALIGN (type
))
1401 type_align
= ADJUST_FIELD_ALIGN (field
, type
, type_align
);
1404 if (maximum_field_alignment
!= 0)
1405 type_align
= MIN (type_align
, maximum_field_alignment
);
1406 /* ??? This test is opposite the test in the containing if
1407 statement, so this code is unreachable currently. */
1408 else if (DECL_PACKED (field
))
1409 type_align
= MIN (type_align
, BITS_PER_UNIT
);
1411 /* A bit field may not span the unit of alignment of its type.
1412 Advance to next boundary if necessary. */
1413 if (excess_unit_span (offset
, bit_offset
, field_size
, type_align
, type
))
1414 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1416 TYPE_USER_ALIGN (rli
->t
) |= TYPE_USER_ALIGN (type
);
1417 SET_TYPE_WARN_IF_NOT_ALIGN (rli
->t
,
1418 TYPE_WARN_IF_NOT_ALIGN (type
));
1422 /* See the docs for TARGET_MS_BITFIELD_LAYOUT_P for details.
1424 When a bit field is inserted into a packed record, the whole
1425 size of the underlying type is used by one or more same-size
1426 adjacent bitfields. (That is, if its long:3, 32 bits is
1427 used in the record, and any additional adjacent long bitfields are
1428 packed into the same chunk of 32 bits. However, if the size
1429 changes, a new field of that size is allocated.) In an unpacked
1430 record, this is the same as using alignment, but not equivalent
1433 Note: for compatibility, we use the type size, not the type alignment
1434 to determine alignment, since that matches the documentation */
1436 if (targetm
.ms_bitfield_layout_p (rli
->t
))
1438 tree prev_saved
= rli
->prev_field
;
1439 tree prev_type
= prev_saved
? DECL_BIT_FIELD_TYPE (prev_saved
) : NULL
;
1441 /* This is a bitfield if it exists. */
1442 if (rli
->prev_field
)
1444 /* If both are bitfields, nonzero, and the same size, this is
1445 the middle of a run. Zero declared size fields are special
1446 and handled as "end of run". (Note: it's nonzero declared
1447 size, but equal type sizes!) (Since we know that both
1448 the current and previous fields are bitfields by the
1449 time we check it, DECL_SIZE must be present for both.) */
1450 if (DECL_BIT_FIELD_TYPE (field
)
1451 && !integer_zerop (DECL_SIZE (field
))
1452 && !integer_zerop (DECL_SIZE (rli
->prev_field
))
1453 && tree_fits_shwi_p (DECL_SIZE (rli
->prev_field
))
1454 && tree_fits_uhwi_p (TYPE_SIZE (type
))
1455 && simple_cst_equal (TYPE_SIZE (type
), TYPE_SIZE (prev_type
)))
1457 /* We're in the middle of a run of equal type size fields; make
1458 sure we realign if we run out of bits. (Not decl size,
1460 HOST_WIDE_INT bitsize
= tree_to_uhwi (DECL_SIZE (field
));
1462 if (rli
->remaining_in_alignment
< bitsize
)
1464 HOST_WIDE_INT typesize
= tree_to_uhwi (TYPE_SIZE (type
));
1466 /* out of bits; bump up to next 'word'. */
1468 = size_binop (PLUS_EXPR
, rli
->bitpos
,
1469 bitsize_int (rli
->remaining_in_alignment
));
1470 rli
->prev_field
= field
;
1471 if (typesize
< bitsize
)
1472 rli
->remaining_in_alignment
= 0;
1474 rli
->remaining_in_alignment
= typesize
- bitsize
;
1477 rli
->remaining_in_alignment
-= bitsize
;
1481 /* End of a run: if leaving a run of bitfields of the same type
1482 size, we have to "use up" the rest of the bits of the type
1485 Compute the new position as the sum of the size for the prior
1486 type and where we first started working on that type.
1487 Note: since the beginning of the field was aligned then
1488 of course the end will be too. No round needed. */
1490 if (!integer_zerop (DECL_SIZE (rli
->prev_field
)))
1493 = size_binop (PLUS_EXPR
, rli
->bitpos
,
1494 bitsize_int (rli
->remaining_in_alignment
));
1497 /* We "use up" size zero fields; the code below should behave
1498 as if the prior field was not a bitfield. */
1501 /* Cause a new bitfield to be captured, either this time (if
1502 currently a bitfield) or next time we see one. */
1503 if (!DECL_BIT_FIELD_TYPE (field
)
1504 || integer_zerop (DECL_SIZE (field
)))
1505 rli
->prev_field
= NULL
;
1508 normalize_rli (rli
);
1511 /* If we're starting a new run of same type size bitfields
1512 (or a run of non-bitfields), set up the "first of the run"
1515 That is, if the current field is not a bitfield, or if there
1516 was a prior bitfield the type sizes differ, or if there wasn't
1517 a prior bitfield the size of the current field is nonzero.
1519 Note: we must be sure to test ONLY the type size if there was
1520 a prior bitfield and ONLY for the current field being zero if
1523 if (!DECL_BIT_FIELD_TYPE (field
)
1524 || (prev_saved
!= NULL
1525 ? !simple_cst_equal (TYPE_SIZE (type
), TYPE_SIZE (prev_type
))
1526 : !integer_zerop (DECL_SIZE (field
)) ))
1528 /* Never smaller than a byte for compatibility. */
1529 unsigned int type_align
= BITS_PER_UNIT
;
1531 /* (When not a bitfield), we could be seeing a flex array (with
1532 no DECL_SIZE). Since we won't be using remaining_in_alignment
1533 until we see a bitfield (and come by here again) we just skip
1535 if (DECL_SIZE (field
) != NULL
1536 && tree_fits_uhwi_p (TYPE_SIZE (TREE_TYPE (field
)))
1537 && tree_fits_uhwi_p (DECL_SIZE (field
)))
1539 unsigned HOST_WIDE_INT bitsize
1540 = tree_to_uhwi (DECL_SIZE (field
));
1541 unsigned HOST_WIDE_INT typesize
1542 = tree_to_uhwi (TYPE_SIZE (TREE_TYPE (field
)));
1544 if (typesize
< bitsize
)
1545 rli
->remaining_in_alignment
= 0;
1547 rli
->remaining_in_alignment
= typesize
- bitsize
;
1550 /* Now align (conventionally) for the new type. */
1551 type_align
= TYPE_ALIGN (TREE_TYPE (field
));
1553 if (maximum_field_alignment
!= 0)
1554 type_align
= MIN (type_align
, maximum_field_alignment
);
1556 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1558 /* If we really aligned, don't allow subsequent bitfields
1560 rli
->prev_field
= NULL
;
1564 /* Offset so far becomes the position of this field after normalizing. */
1565 normalize_rli (rli
);
1566 DECL_FIELD_OFFSET (field
) = rli
->offset
;
1567 DECL_FIELD_BIT_OFFSET (field
) = rli
->bitpos
;
1568 SET_DECL_OFFSET_ALIGN (field
, rli
->offset_align
);
1569 handle_warn_if_not_align (field
, rli
->record_align
);
1571 /* Evaluate nonconstant offsets only once, either now or as soon as safe. */
1572 if (TREE_CODE (DECL_FIELD_OFFSET (field
)) != INTEGER_CST
)
1573 DECL_FIELD_OFFSET (field
) = variable_size (DECL_FIELD_OFFSET (field
));
1575 /* If this field ended up more aligned than we thought it would be (we
1576 approximate this by seeing if its position changed), lay out the field
1577 again; perhaps we can use an integral mode for it now. */
1578 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field
)))
1579 actual_align
= least_bit_hwi (tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field
)));
1580 else if (integer_zerop (DECL_FIELD_OFFSET (field
)))
1581 actual_align
= MAX (BIGGEST_ALIGNMENT
, rli
->record_align
);
1582 else if (tree_fits_uhwi_p (DECL_FIELD_OFFSET (field
)))
1583 actual_align
= (BITS_PER_UNIT
1584 * least_bit_hwi (tree_to_uhwi (DECL_FIELD_OFFSET (field
))));
1586 actual_align
= DECL_OFFSET_ALIGN (field
);
1587 /* ACTUAL_ALIGN is still the actual alignment *within the record* .
1588 store / extract bit field operations will check the alignment of the
1589 record against the mode of bit fields. */
1591 if (known_align
!= actual_align
)
1592 layout_decl (field
, actual_align
);
1594 if (rli
->prev_field
== NULL
&& DECL_BIT_FIELD_TYPE (field
))
1595 rli
->prev_field
= field
;
1597 /* Now add size of this field to the size of the record. If the size is
1598 not constant, treat the field as being a multiple of bytes and just
1599 adjust the offset, resetting the bit position. Otherwise, apportion the
1600 size amongst the bit position and offset. First handle the case of an
1601 unspecified size, which can happen when we have an invalid nested struct
1602 definition, such as struct j { struct j { int i; } }. The error message
1603 is printed in finish_struct. */
1604 if (DECL_SIZE (field
) == 0)
1606 else if (TREE_CODE (DECL_SIZE (field
)) != INTEGER_CST
1607 || TREE_OVERFLOW (DECL_SIZE (field
)))
1610 = size_binop (PLUS_EXPR
, rli
->offset
,
1611 fold_convert (sizetype
,
1612 size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
1613 bitsize_unit_node
)));
1615 = size_binop (PLUS_EXPR
, rli
->offset
, DECL_SIZE_UNIT (field
));
1616 rli
->bitpos
= bitsize_zero_node
;
1617 rli
->offset_align
= MIN (rli
->offset_align
, desired_align
);
1619 else if (targetm
.ms_bitfield_layout_p (rli
->t
))
1621 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
, DECL_SIZE (field
));
1623 /* If we ended a bitfield before the full length of the type then
1624 pad the struct out to the full length of the last type. */
1625 if ((DECL_CHAIN (field
) == NULL
1626 || TREE_CODE (DECL_CHAIN (field
)) != FIELD_DECL
)
1627 && DECL_BIT_FIELD_TYPE (field
)
1628 && !integer_zerop (DECL_SIZE (field
)))
1629 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
,
1630 bitsize_int (rli
->remaining_in_alignment
));
1632 normalize_rli (rli
);
1636 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
, DECL_SIZE (field
));
1637 normalize_rli (rli
);
1641 /* Assuming that all the fields have been laid out, this function uses
1642 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
1643 indicated by RLI. */
1646 finalize_record_size (record_layout_info rli
)
1648 tree unpadded_size
, unpadded_size_unit
;
1650 /* Now we want just byte and bit offsets, so set the offset alignment
1651 to be a byte and then normalize. */
1652 rli
->offset_align
= BITS_PER_UNIT
;
1653 normalize_rli (rli
);
1655 /* Determine the desired alignment. */
1656 #ifdef ROUND_TYPE_ALIGN
1657 SET_TYPE_ALIGN (rli
->t
, ROUND_TYPE_ALIGN (rli
->t
, TYPE_ALIGN (rli
->t
),
1658 rli
->record_align
));
1660 SET_TYPE_ALIGN (rli
->t
, MAX (TYPE_ALIGN (rli
->t
), rli
->record_align
));
1663 /* Compute the size so far. Be sure to allow for extra bits in the
1664 size in bytes. We have guaranteed above that it will be no more
1665 than a single byte. */
1666 unpadded_size
= rli_size_so_far (rli
);
1667 unpadded_size_unit
= rli_size_unit_so_far (rli
);
1668 if (! integer_zerop (rli
->bitpos
))
1670 = size_binop (PLUS_EXPR
, unpadded_size_unit
, size_one_node
);
1672 /* Round the size up to be a multiple of the required alignment. */
1673 TYPE_SIZE (rli
->t
) = round_up (unpadded_size
, TYPE_ALIGN (rli
->t
));
1674 TYPE_SIZE_UNIT (rli
->t
)
1675 = round_up (unpadded_size_unit
, TYPE_ALIGN_UNIT (rli
->t
));
1677 if (TREE_CONSTANT (unpadded_size
)
1678 && simple_cst_equal (unpadded_size
, TYPE_SIZE (rli
->t
)) == 0
1679 && input_location
!= BUILTINS_LOCATION
)
1680 warning (OPT_Wpadded
, "padding struct size to alignment boundary");
1682 if (warn_packed
&& TREE_CODE (rli
->t
) == RECORD_TYPE
1683 && TYPE_PACKED (rli
->t
) && ! rli
->packed_maybe_necessary
1684 && TREE_CONSTANT (unpadded_size
))
1688 #ifdef ROUND_TYPE_ALIGN
1690 = ROUND_TYPE_ALIGN (rli
->t
, TYPE_ALIGN (rli
->t
), rli
->unpacked_align
);
1692 rli
->unpacked_align
= MAX (TYPE_ALIGN (rli
->t
), rli
->unpacked_align
);
1695 unpacked_size
= round_up (TYPE_SIZE (rli
->t
), rli
->unpacked_align
);
1696 if (simple_cst_equal (unpacked_size
, TYPE_SIZE (rli
->t
)))
1698 if (TYPE_NAME (rli
->t
))
1702 if (TREE_CODE (TYPE_NAME (rli
->t
)) == IDENTIFIER_NODE
)
1703 name
= TYPE_NAME (rli
->t
);
1705 name
= DECL_NAME (TYPE_NAME (rli
->t
));
1707 if (STRICT_ALIGNMENT
)
1708 warning (OPT_Wpacked
, "packed attribute causes inefficient "
1709 "alignment for %qE", name
);
1711 warning (OPT_Wpacked
,
1712 "packed attribute is unnecessary for %qE", name
);
1716 if (STRICT_ALIGNMENT
)
1717 warning (OPT_Wpacked
,
1718 "packed attribute causes inefficient alignment");
1720 warning (OPT_Wpacked
, "packed attribute is unnecessary");
1726 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
1729 compute_record_mode (tree type
)
1732 machine_mode mode
= VOIDmode
;
1734 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
1735 However, if possible, we use a mode that fits in a register
1736 instead, in order to allow for better optimization down the
1738 SET_TYPE_MODE (type
, BLKmode
);
1740 if (! tree_fits_uhwi_p (TYPE_SIZE (type
)))
1743 /* A record which has any BLKmode members must itself be
1744 BLKmode; it can't go in a register. Unless the member is
1745 BLKmode only because it isn't aligned. */
1746 for (field
= TYPE_FIELDS (type
); field
; field
= DECL_CHAIN (field
))
1748 if (TREE_CODE (field
) != FIELD_DECL
)
1751 if (TREE_CODE (TREE_TYPE (field
)) == ERROR_MARK
1752 || (TYPE_MODE (TREE_TYPE (field
)) == BLKmode
1753 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field
))
1754 && !(TYPE_SIZE (TREE_TYPE (field
)) != 0
1755 && integer_zerop (TYPE_SIZE (TREE_TYPE (field
)))))
1756 || ! tree_fits_uhwi_p (bit_position (field
))
1757 || DECL_SIZE (field
) == 0
1758 || ! tree_fits_uhwi_p (DECL_SIZE (field
)))
1761 /* If this field is the whole struct, remember its mode so
1762 that, say, we can put a double in a class into a DF
1763 register instead of forcing it to live in the stack. */
1764 if (simple_cst_equal (TYPE_SIZE (type
), DECL_SIZE (field
)))
1765 mode
= DECL_MODE (field
);
1767 /* With some targets, it is sub-optimal to access an aligned
1768 BLKmode structure as a scalar. */
1769 if (targetm
.member_type_forces_blk (field
, mode
))
1773 /* If we only have one real field; use its mode if that mode's size
1774 matches the type's size. This only applies to RECORD_TYPE. This
1775 does not apply to unions. */
1776 if (TREE_CODE (type
) == RECORD_TYPE
&& mode
!= VOIDmode
1777 && tree_fits_uhwi_p (TYPE_SIZE (type
))
1778 && known_eq (GET_MODE_BITSIZE (mode
), tree_to_uhwi (TYPE_SIZE (type
))))
1781 mode
= mode_for_size_tree (TYPE_SIZE (type
), MODE_INT
, 1).else_blk ();
1783 /* If structure's known alignment is less than what the scalar
1784 mode would need, and it matters, then stick with BLKmode. */
1787 && ! (TYPE_ALIGN (type
) >= BIGGEST_ALIGNMENT
1788 || TYPE_ALIGN (type
) >= GET_MODE_ALIGNMENT (mode
)))
1790 /* If this is the only reason this type is BLKmode, then
1791 don't force containing types to be BLKmode. */
1792 TYPE_NO_FORCE_BLK (type
) = 1;
1796 SET_TYPE_MODE (type
, mode
);
1799 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1803 finalize_type_size (tree type
)
1805 /* Normally, use the alignment corresponding to the mode chosen.
1806 However, where strict alignment is not required, avoid
1807 over-aligning structures, since most compilers do not do this
1809 if (TYPE_MODE (type
) != BLKmode
1810 && TYPE_MODE (type
) != VOIDmode
1811 && (STRICT_ALIGNMENT
|| !AGGREGATE_TYPE_P (type
)))
1813 unsigned mode_align
= GET_MODE_ALIGNMENT (TYPE_MODE (type
));
1815 /* Don't override a larger alignment requirement coming from a user
1816 alignment of one of the fields. */
1817 if (mode_align
>= TYPE_ALIGN (type
))
1819 SET_TYPE_ALIGN (type
, mode_align
);
1820 TYPE_USER_ALIGN (type
) = 0;
1824 /* Do machine-dependent extra alignment. */
1825 #ifdef ROUND_TYPE_ALIGN
1826 SET_TYPE_ALIGN (type
,
1827 ROUND_TYPE_ALIGN (type
, TYPE_ALIGN (type
), BITS_PER_UNIT
));
1830 /* If we failed to find a simple way to calculate the unit size
1831 of the type, find it by division. */
1832 if (TYPE_SIZE_UNIT (type
) == 0 && TYPE_SIZE (type
) != 0)
1833 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1834 result will fit in sizetype. We will get more efficient code using
1835 sizetype, so we force a conversion. */
1836 TYPE_SIZE_UNIT (type
)
1837 = fold_convert (sizetype
,
1838 size_binop (FLOOR_DIV_EXPR
, TYPE_SIZE (type
),
1839 bitsize_unit_node
));
1841 if (TYPE_SIZE (type
) != 0)
1843 TYPE_SIZE (type
) = round_up (TYPE_SIZE (type
), TYPE_ALIGN (type
));
1844 TYPE_SIZE_UNIT (type
)
1845 = round_up (TYPE_SIZE_UNIT (type
), TYPE_ALIGN_UNIT (type
));
1848 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1849 if (TYPE_SIZE (type
) != 0 && TREE_CODE (TYPE_SIZE (type
)) != INTEGER_CST
)
1850 TYPE_SIZE (type
) = variable_size (TYPE_SIZE (type
));
1851 if (TYPE_SIZE_UNIT (type
) != 0
1852 && TREE_CODE (TYPE_SIZE_UNIT (type
)) != INTEGER_CST
)
1853 TYPE_SIZE_UNIT (type
) = variable_size (TYPE_SIZE_UNIT (type
));
1855 /* Also layout any other variants of the type. */
1856 if (TYPE_NEXT_VARIANT (type
)
1857 || type
!= TYPE_MAIN_VARIANT (type
))
1860 /* Record layout info of this variant. */
1861 tree size
= TYPE_SIZE (type
);
1862 tree size_unit
= TYPE_SIZE_UNIT (type
);
1863 unsigned int align
= TYPE_ALIGN (type
);
1864 unsigned int precision
= TYPE_PRECISION (type
);
1865 unsigned int user_align
= TYPE_USER_ALIGN (type
);
1866 machine_mode mode
= TYPE_MODE (type
);
1868 /* Copy it into all variants. */
1869 for (variant
= TYPE_MAIN_VARIANT (type
);
1871 variant
= TYPE_NEXT_VARIANT (variant
))
1873 TYPE_SIZE (variant
) = size
;
1874 TYPE_SIZE_UNIT (variant
) = size_unit
;
1875 unsigned valign
= align
;
1876 if (TYPE_USER_ALIGN (variant
))
1877 valign
= MAX (valign
, TYPE_ALIGN (variant
));
1879 TYPE_USER_ALIGN (variant
) = user_align
;
1880 SET_TYPE_ALIGN (variant
, valign
);
1881 TYPE_PRECISION (variant
) = precision
;
1882 SET_TYPE_MODE (variant
, mode
);
1886 /* Handle empty records as per the x86-64 psABI. */
1887 TYPE_EMPTY_P (type
) = targetm
.calls
.empty_record_p (type
);
1890 /* Return a new underlying object for a bitfield started with FIELD. */
1893 start_bitfield_representative (tree field
)
1895 tree repr
= make_node (FIELD_DECL
);
1896 DECL_FIELD_OFFSET (repr
) = DECL_FIELD_OFFSET (field
);
1897 /* Force the representative to begin at a BITS_PER_UNIT aligned
1898 boundary - C++ may use tail-padding of a base object to
1899 continue packing bits so the bitfield region does not start
1900 at bit zero (see g++.dg/abi/bitfield5.C for example).
1901 Unallocated bits may happen for other reasons as well,
1902 for example Ada which allows explicit bit-granular structure layout. */
1903 DECL_FIELD_BIT_OFFSET (repr
)
1904 = size_binop (BIT_AND_EXPR
,
1905 DECL_FIELD_BIT_OFFSET (field
),
1906 bitsize_int (~(BITS_PER_UNIT
- 1)));
1907 SET_DECL_OFFSET_ALIGN (repr
, DECL_OFFSET_ALIGN (field
));
1908 DECL_SIZE (repr
) = DECL_SIZE (field
);
1909 DECL_SIZE_UNIT (repr
) = DECL_SIZE_UNIT (field
);
1910 DECL_PACKED (repr
) = DECL_PACKED (field
);
1911 DECL_CONTEXT (repr
) = DECL_CONTEXT (field
);
1912 /* There are no indirect accesses to this field. If we introduce
1913 some then they have to use the record alias set. This makes
1914 sure to properly conflict with [indirect] accesses to addressable
1915 fields of the bitfield group. */
1916 DECL_NONADDRESSABLE_P (repr
) = 1;
1920 /* Finish up a bitfield group that was started by creating the underlying
1921 object REPR with the last field in the bitfield group FIELD. */
1924 finish_bitfield_representative (tree repr
, tree field
)
1926 unsigned HOST_WIDE_INT bitsize
, maxbitsize
;
1929 size
= size_diffop (DECL_FIELD_OFFSET (field
),
1930 DECL_FIELD_OFFSET (repr
));
1931 while (TREE_CODE (size
) == COMPOUND_EXPR
)
1932 size
= TREE_OPERAND (size
, 1);
1933 gcc_assert (tree_fits_uhwi_p (size
));
1934 bitsize
= (tree_to_uhwi (size
) * BITS_PER_UNIT
1935 + tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field
))
1936 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr
))
1937 + tree_to_uhwi (DECL_SIZE (field
)));
1939 /* Round up bitsize to multiples of BITS_PER_UNIT. */
1940 bitsize
= (bitsize
+ BITS_PER_UNIT
- 1) & ~(BITS_PER_UNIT
- 1);
1942 /* Now nothing tells us how to pad out bitsize ... */
1943 nextf
= DECL_CHAIN (field
);
1944 while (nextf
&& TREE_CODE (nextf
) != FIELD_DECL
)
1945 nextf
= DECL_CHAIN (nextf
);
1949 /* If there was an error, the field may be not laid out
1950 correctly. Don't bother to do anything. */
1951 if (TREE_TYPE (nextf
) == error_mark_node
)
1953 maxsize
= size_diffop (DECL_FIELD_OFFSET (nextf
),
1954 DECL_FIELD_OFFSET (repr
));
1955 if (tree_fits_uhwi_p (maxsize
))
1957 maxbitsize
= (tree_to_uhwi (maxsize
) * BITS_PER_UNIT
1958 + tree_to_uhwi (DECL_FIELD_BIT_OFFSET (nextf
))
1959 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr
)));
1960 /* If the group ends within a bitfield nextf does not need to be
1961 aligned to BITS_PER_UNIT. Thus round up. */
1962 maxbitsize
= (maxbitsize
+ BITS_PER_UNIT
- 1) & ~(BITS_PER_UNIT
- 1);
1965 maxbitsize
= bitsize
;
1969 /* Note that if the C++ FE sets up tail-padding to be re-used it
1970 creates a as-base variant of the type with TYPE_SIZE adjusted
1971 accordingly. So it is safe to include tail-padding here. */
1972 tree aggsize
= lang_hooks
.types
.unit_size_without_reusable_padding
1973 (DECL_CONTEXT (field
));
1974 tree maxsize
= size_diffop (aggsize
, DECL_FIELD_OFFSET (repr
));
1975 /* We cannot generally rely on maxsize to fold to an integer constant,
1976 so use bitsize as fallback for this case. */
1977 if (tree_fits_uhwi_p (maxsize
))
1978 maxbitsize
= (tree_to_uhwi (maxsize
) * BITS_PER_UNIT
1979 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr
)));
1981 maxbitsize
= bitsize
;
1984 /* Only if we don't artificially break up the representative in
1985 the middle of a large bitfield with different possibly
1986 overlapping representatives. And all representatives start
1988 gcc_assert (maxbitsize
% BITS_PER_UNIT
== 0);
1990 /* Find the smallest nice mode to use. */
1991 opt_scalar_int_mode mode_iter
;
1992 FOR_EACH_MODE_IN_CLASS (mode_iter
, MODE_INT
)
1993 if (GET_MODE_BITSIZE (mode_iter
.require ()) >= bitsize
)
1996 scalar_int_mode mode
;
1997 if (!mode_iter
.exists (&mode
)
1998 || GET_MODE_BITSIZE (mode
) > maxbitsize
1999 || GET_MODE_BITSIZE (mode
) > MAX_FIXED_MODE_SIZE
)
2001 /* We really want a BLKmode representative only as a last resort,
2002 considering the member b in
2003 struct { int a : 7; int b : 17; int c; } __attribute__((packed));
2004 Otherwise we simply want to split the representative up
2005 allowing for overlaps within the bitfield region as required for
2006 struct { int a : 7; int b : 7;
2007 int c : 10; int d; } __attribute__((packed));
2008 [0, 15] HImode for a and b, [8, 23] HImode for c. */
2009 DECL_SIZE (repr
) = bitsize_int (bitsize
);
2010 DECL_SIZE_UNIT (repr
) = size_int (bitsize
/ BITS_PER_UNIT
);
2011 SET_DECL_MODE (repr
, BLKmode
);
2012 TREE_TYPE (repr
) = build_array_type_nelts (unsigned_char_type_node
,
2013 bitsize
/ BITS_PER_UNIT
);
2017 unsigned HOST_WIDE_INT modesize
= GET_MODE_BITSIZE (mode
);
2018 DECL_SIZE (repr
) = bitsize_int (modesize
);
2019 DECL_SIZE_UNIT (repr
) = size_int (modesize
/ BITS_PER_UNIT
);
2020 SET_DECL_MODE (repr
, mode
);
2021 TREE_TYPE (repr
) = lang_hooks
.types
.type_for_mode (mode
, 1);
2024 /* Remember whether the bitfield group is at the end of the
2025 structure or not. */
2026 DECL_CHAIN (repr
) = nextf
;
2029 /* Compute and set FIELD_DECLs for the underlying objects we should
2030 use for bitfield access for the structure T. */
2033 finish_bitfield_layout (tree t
)
2036 tree repr
= NULL_TREE
;
2038 /* Unions would be special, for the ease of type-punning optimizations
2039 we could use the underlying type as hint for the representative
2040 if the bitfield would fit and the representative would not exceed
2041 the union in size. */
2042 if (TREE_CODE (t
) != RECORD_TYPE
)
2045 for (prev
= NULL_TREE
, field
= TYPE_FIELDS (t
);
2046 field
; field
= DECL_CHAIN (field
))
2048 if (TREE_CODE (field
) != FIELD_DECL
)
2051 /* In the C++ memory model, consecutive bit fields in a structure are
2052 considered one memory location and updating a memory location
2053 may not store into adjacent memory locations. */
2055 && DECL_BIT_FIELD_TYPE (field
))
2057 /* Start new representative. */
2058 repr
= start_bitfield_representative (field
);
2061 && ! DECL_BIT_FIELD_TYPE (field
))
2063 /* Finish off new representative. */
2064 finish_bitfield_representative (repr
, prev
);
2067 else if (DECL_BIT_FIELD_TYPE (field
))
2069 gcc_assert (repr
!= NULL_TREE
);
2071 /* Zero-size bitfields finish off a representative and
2072 do not have a representative themselves. This is
2073 required by the C++ memory model. */
2074 if (integer_zerop (DECL_SIZE (field
)))
2076 finish_bitfield_representative (repr
, prev
);
2080 /* We assume that either DECL_FIELD_OFFSET of the representative
2081 and each bitfield member is a constant or they are equal.
2082 This is because we need to be able to compute the bit-offset
2083 of each field relative to the representative in get_bit_range
2084 during RTL expansion.
2085 If these constraints are not met, simply force a new
2086 representative to be generated. That will at most
2087 generate worse code but still maintain correctness with
2088 respect to the C++ memory model. */
2089 else if (!((tree_fits_uhwi_p (DECL_FIELD_OFFSET (repr
))
2090 && tree_fits_uhwi_p (DECL_FIELD_OFFSET (field
)))
2091 || operand_equal_p (DECL_FIELD_OFFSET (repr
),
2092 DECL_FIELD_OFFSET (field
), 0)))
2094 finish_bitfield_representative (repr
, prev
);
2095 repr
= start_bitfield_representative (field
);
2102 DECL_BIT_FIELD_REPRESENTATIVE (field
) = repr
;
2108 finish_bitfield_representative (repr
, prev
);
2111 /* Do all of the work required to layout the type indicated by RLI,
2112 once the fields have been laid out. This function will call `free'
2113 for RLI, unless FREE_P is false. Passing a value other than false
2114 for FREE_P is bad practice; this option only exists to support the
2118 finish_record_layout (record_layout_info rli
, int free_p
)
2122 /* Compute the final size. */
2123 finalize_record_size (rli
);
2125 /* Compute the TYPE_MODE for the record. */
2126 compute_record_mode (rli
->t
);
2128 /* Perform any last tweaks to the TYPE_SIZE, etc. */
2129 finalize_type_size (rli
->t
);
2131 /* Compute bitfield representatives. */
2132 finish_bitfield_layout (rli
->t
);
2134 /* Propagate TYPE_PACKED and TYPE_REVERSE_STORAGE_ORDER to variants.
2135 With C++ templates, it is too early to do this when the attribute
2137 for (variant
= TYPE_NEXT_VARIANT (rli
->t
); variant
;
2138 variant
= TYPE_NEXT_VARIANT (variant
))
2140 TYPE_PACKED (variant
) = TYPE_PACKED (rli
->t
);
2141 TYPE_REVERSE_STORAGE_ORDER (variant
)
2142 = TYPE_REVERSE_STORAGE_ORDER (rli
->t
);
2145 /* Lay out any static members. This is done now because their type
2146 may use the record's type. */
2147 while (!vec_safe_is_empty (rli
->pending_statics
))
2148 layout_decl (rli
->pending_statics
->pop (), 0);
2153 vec_free (rli
->pending_statics
);
2159 /* Finish processing a builtin RECORD_TYPE type TYPE. It's name is
2160 NAME, its fields are chained in reverse on FIELDS.
2162 If ALIGN_TYPE is non-null, it is given the same alignment as
2166 finish_builtin_struct (tree type
, const char *name
, tree fields
,
2171 for (tail
= NULL_TREE
; fields
; tail
= fields
, fields
= next
)
2173 DECL_FIELD_CONTEXT (fields
) = type
;
2174 next
= DECL_CHAIN (fields
);
2175 DECL_CHAIN (fields
) = tail
;
2177 TYPE_FIELDS (type
) = tail
;
2181 SET_TYPE_ALIGN (type
, TYPE_ALIGN (align_type
));
2182 TYPE_USER_ALIGN (type
) = TYPE_USER_ALIGN (align_type
);
2183 SET_TYPE_WARN_IF_NOT_ALIGN (type
,
2184 TYPE_WARN_IF_NOT_ALIGN (align_type
));
2188 #if 0 /* not yet, should get fixed properly later */
2189 TYPE_NAME (type
) = make_type_decl (get_identifier (name
), type
);
2191 TYPE_NAME (type
) = build_decl (BUILTINS_LOCATION
,
2192 TYPE_DECL
, get_identifier (name
), type
);
2194 TYPE_STUB_DECL (type
) = TYPE_NAME (type
);
2195 layout_decl (TYPE_NAME (type
), 0);
2198 /* Calculate the mode, size, and alignment for TYPE.
2199 For an array type, calculate the element separation as well.
2200 Record TYPE on the chain of permanent or temporary types
2201 so that dbxout will find out about it.
2203 TYPE_SIZE of a type is nonzero if the type has been laid out already.
2204 layout_type does nothing on such a type.
2206 If the type is incomplete, its TYPE_SIZE remains zero. */
2209 layout_type (tree type
)
2213 if (type
== error_mark_node
)
2216 /* We don't want finalize_type_size to copy an alignment attribute to
2217 variants that don't have it. */
2218 type
= TYPE_MAIN_VARIANT (type
);
2220 /* Do nothing if type has been laid out before. */
2221 if (TYPE_SIZE (type
))
2224 switch (TREE_CODE (type
))
2227 /* This kind of type is the responsibility
2228 of the language-specific code. */
2235 scalar_int_mode mode
2236 = smallest_int_mode_for_size (TYPE_PRECISION (type
));
2237 SET_TYPE_MODE (type
, mode
);
2238 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2239 /* Don't set TYPE_PRECISION here, as it may be set by a bitfield. */
2240 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2246 /* Allow the caller to choose the type mode, which is how decimal
2247 floats are distinguished from binary ones. */
2248 if (TYPE_MODE (type
) == VOIDmode
)
2250 (type
, float_mode_for_size (TYPE_PRECISION (type
)).require ());
2251 scalar_float_mode mode
= as_a
<scalar_float_mode
> (TYPE_MODE (type
));
2252 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2253 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2257 case FIXED_POINT_TYPE
:
2259 /* TYPE_MODE (type) has been set already. */
2260 scalar_mode mode
= SCALAR_TYPE_MODE (type
);
2261 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2262 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2267 TYPE_UNSIGNED (type
) = TYPE_UNSIGNED (TREE_TYPE (type
));
2268 SET_TYPE_MODE (type
,
2269 GET_MODE_COMPLEX_MODE (TYPE_MODE (TREE_TYPE (type
))));
2271 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
2272 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
2277 poly_uint64 nunits
= TYPE_VECTOR_SUBPARTS (type
);
2278 tree innertype
= TREE_TYPE (type
);
2280 /* Find an appropriate mode for the vector type. */
2281 if (TYPE_MODE (type
) == VOIDmode
)
2282 SET_TYPE_MODE (type
,
2283 mode_for_vector (SCALAR_TYPE_MODE (innertype
),
2284 nunits
).else_blk ());
2286 TYPE_SATURATING (type
) = TYPE_SATURATING (TREE_TYPE (type
));
2287 TYPE_UNSIGNED (type
) = TYPE_UNSIGNED (TREE_TYPE (type
));
2288 /* Several boolean vector elements may fit in a single unit. */
2289 if (VECTOR_BOOLEAN_TYPE_P (type
)
2290 && type
->type_common
.mode
!= BLKmode
)
2291 TYPE_SIZE_UNIT (type
)
2292 = size_int (GET_MODE_SIZE (type
->type_common
.mode
));
2294 TYPE_SIZE_UNIT (type
) = int_const_binop (MULT_EXPR
,
2295 TYPE_SIZE_UNIT (innertype
),
2297 TYPE_SIZE (type
) = int_const_binop
2299 bits_from_bytes (TYPE_SIZE_UNIT (type
)),
2300 bitsize_int (BITS_PER_UNIT
));
2302 /* For vector types, we do not default to the mode's alignment.
2303 Instead, query a target hook, defaulting to natural alignment.
2304 This prevents ABI changes depending on whether or not native
2305 vector modes are supported. */
2306 SET_TYPE_ALIGN (type
, targetm
.vector_alignment (type
));
2308 /* However, if the underlying mode requires a bigger alignment than
2309 what the target hook provides, we cannot use the mode. For now,
2310 simply reject that case. */
2311 gcc_assert (TYPE_ALIGN (type
)
2312 >= GET_MODE_ALIGNMENT (TYPE_MODE (type
)));
2317 /* This is an incomplete type and so doesn't have a size. */
2318 SET_TYPE_ALIGN (type
, 1);
2319 TYPE_USER_ALIGN (type
) = 0;
2320 SET_TYPE_MODE (type
, VOIDmode
);
2323 case POINTER_BOUNDS_TYPE
:
2324 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
2325 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
2329 TYPE_SIZE (type
) = bitsize_int (POINTER_SIZE
);
2330 TYPE_SIZE_UNIT (type
) = size_int (POINTER_SIZE_UNITS
);
2331 /* A pointer might be MODE_PARTIAL_INT, but ptrdiff_t must be
2332 integral, which may be an __intN. */
2333 SET_TYPE_MODE (type
, int_mode_for_size (POINTER_SIZE
, 0).require ());
2334 TYPE_PRECISION (type
) = POINTER_SIZE
;
2339 /* It's hard to see what the mode and size of a function ought to
2340 be, but we do know the alignment is FUNCTION_BOUNDARY, so
2341 make it consistent with that. */
2342 SET_TYPE_MODE (type
,
2343 int_mode_for_size (FUNCTION_BOUNDARY
, 0).else_blk ());
2344 TYPE_SIZE (type
) = bitsize_int (FUNCTION_BOUNDARY
);
2345 TYPE_SIZE_UNIT (type
) = size_int (FUNCTION_BOUNDARY
/ BITS_PER_UNIT
);
2349 case REFERENCE_TYPE
:
2351 scalar_int_mode mode
= SCALAR_INT_TYPE_MODE (type
);
2352 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2353 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2354 TYPE_UNSIGNED (type
) = 1;
2355 TYPE_PRECISION (type
) = GET_MODE_PRECISION (mode
);
2361 tree index
= TYPE_DOMAIN (type
);
2362 tree element
= TREE_TYPE (type
);
2364 /* We need to know both bounds in order to compute the size. */
2365 if (index
&& TYPE_MAX_VALUE (index
) && TYPE_MIN_VALUE (index
)
2366 && TYPE_SIZE (element
))
2368 tree ub
= TYPE_MAX_VALUE (index
);
2369 tree lb
= TYPE_MIN_VALUE (index
);
2370 tree element_size
= TYPE_SIZE (element
);
2373 /* Make sure that an array of zero-sized element is zero-sized
2374 regardless of its extent. */
2375 if (integer_zerop (element_size
))
2376 length
= size_zero_node
;
2378 /* The computation should happen in the original signedness so
2379 that (possible) negative values are handled appropriately
2380 when determining overflow. */
2383 /* ??? When it is obvious that the range is signed
2384 represent it using ssizetype. */
2385 if (TREE_CODE (lb
) == INTEGER_CST
2386 && TREE_CODE (ub
) == INTEGER_CST
2387 && TYPE_UNSIGNED (TREE_TYPE (lb
))
2388 && tree_int_cst_lt (ub
, lb
))
2390 lb
= wide_int_to_tree (ssizetype
,
2391 offset_int::from (wi::to_wide (lb
),
2393 ub
= wide_int_to_tree (ssizetype
,
2394 offset_int::from (wi::to_wide (ub
),
2398 = fold_convert (sizetype
,
2399 size_binop (PLUS_EXPR
,
2400 build_int_cst (TREE_TYPE (lb
), 1),
2401 size_binop (MINUS_EXPR
, ub
, lb
)));
2404 /* ??? We have no way to distinguish a null-sized array from an
2405 array spanning the whole sizetype range, so we arbitrarily
2406 decide that [0, -1] is the only valid representation. */
2407 if (integer_zerop (length
)
2408 && TREE_OVERFLOW (length
)
2409 && integer_zerop (lb
))
2410 length
= size_zero_node
;
2412 TYPE_SIZE (type
) = size_binop (MULT_EXPR
, element_size
,
2413 bits_from_bytes (length
));
2415 /* If we know the size of the element, calculate the total size
2416 directly, rather than do some division thing below. This
2417 optimization helps Fortran assumed-size arrays (where the
2418 size of the array is determined at runtime) substantially. */
2419 if (TYPE_SIZE_UNIT (element
))
2420 TYPE_SIZE_UNIT (type
)
2421 = size_binop (MULT_EXPR
, TYPE_SIZE_UNIT (element
), length
);
2424 /* Now round the alignment and size,
2425 using machine-dependent criteria if any. */
2427 unsigned align
= TYPE_ALIGN (element
);
2428 if (TYPE_USER_ALIGN (type
))
2429 align
= MAX (align
, TYPE_ALIGN (type
));
2431 TYPE_USER_ALIGN (type
) = TYPE_USER_ALIGN (element
);
2432 if (!TYPE_WARN_IF_NOT_ALIGN (type
))
2433 SET_TYPE_WARN_IF_NOT_ALIGN (type
,
2434 TYPE_WARN_IF_NOT_ALIGN (element
));
2435 #ifdef ROUND_TYPE_ALIGN
2436 align
= ROUND_TYPE_ALIGN (type
, align
, BITS_PER_UNIT
);
2438 align
= MAX (align
, BITS_PER_UNIT
);
2440 SET_TYPE_ALIGN (type
, align
);
2441 SET_TYPE_MODE (type
, BLKmode
);
2442 if (TYPE_SIZE (type
) != 0
2443 && ! targetm
.member_type_forces_blk (type
, VOIDmode
)
2444 /* BLKmode elements force BLKmode aggregate;
2445 else extract/store fields may lose. */
2446 && (TYPE_MODE (TREE_TYPE (type
)) != BLKmode
2447 || TYPE_NO_FORCE_BLK (TREE_TYPE (type
))))
2449 SET_TYPE_MODE (type
, mode_for_array (TREE_TYPE (type
),
2451 if (TYPE_MODE (type
) != BLKmode
2452 && STRICT_ALIGNMENT
&& TYPE_ALIGN (type
) < BIGGEST_ALIGNMENT
2453 && TYPE_ALIGN (type
) < GET_MODE_ALIGNMENT (TYPE_MODE (type
)))
2455 TYPE_NO_FORCE_BLK (type
) = 1;
2456 SET_TYPE_MODE (type
, BLKmode
);
2459 if (AGGREGATE_TYPE_P (element
))
2460 TYPE_TYPELESS_STORAGE (type
) = TYPE_TYPELESS_STORAGE (element
);
2461 /* When the element size is constant, check that it is at least as
2462 large as the element alignment. */
2463 if (TYPE_SIZE_UNIT (element
)
2464 && TREE_CODE (TYPE_SIZE_UNIT (element
)) == INTEGER_CST
2465 /* If TYPE_SIZE_UNIT overflowed, then it is certainly larger than
2467 && !TREE_OVERFLOW (TYPE_SIZE_UNIT (element
))
2468 && !integer_zerop (TYPE_SIZE_UNIT (element
))
2469 && compare_tree_int (TYPE_SIZE_UNIT (element
),
2470 TYPE_ALIGN_UNIT (element
)) < 0)
2471 error ("alignment of array elements is greater than element size");
2477 case QUAL_UNION_TYPE
:
2480 record_layout_info rli
;
2482 /* Initialize the layout information. */
2483 rli
= start_record_layout (type
);
2485 /* If this is a QUAL_UNION_TYPE, we want to process the fields
2486 in the reverse order in building the COND_EXPR that denotes
2487 its size. We reverse them again later. */
2488 if (TREE_CODE (type
) == QUAL_UNION_TYPE
)
2489 TYPE_FIELDS (type
) = nreverse (TYPE_FIELDS (type
));
2491 /* Place all the fields. */
2492 for (field
= TYPE_FIELDS (type
); field
; field
= DECL_CHAIN (field
))
2493 place_field (rli
, field
);
2495 if (TREE_CODE (type
) == QUAL_UNION_TYPE
)
2496 TYPE_FIELDS (type
) = nreverse (TYPE_FIELDS (type
));
2498 /* Finish laying out the record. */
2499 finish_record_layout (rli
, /*free_p=*/true);
2507 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
2508 records and unions, finish_record_layout already called this
2510 if (!RECORD_OR_UNION_TYPE_P (type
))
2511 finalize_type_size (type
);
2513 /* We should never see alias sets on incomplete aggregates. And we
2514 should not call layout_type on not incomplete aggregates. */
2515 if (AGGREGATE_TYPE_P (type
))
2516 gcc_assert (!TYPE_ALIAS_SET_KNOWN_P (type
));
2519 /* Return the least alignment required for type TYPE. */
2522 min_align_of_type (tree type
)
2524 unsigned int align
= TYPE_ALIGN (type
);
2525 if (!TYPE_USER_ALIGN (type
))
2527 align
= MIN (align
, BIGGEST_ALIGNMENT
);
2528 #ifdef BIGGEST_FIELD_ALIGNMENT
2529 align
= MIN (align
, BIGGEST_FIELD_ALIGNMENT
);
2531 unsigned int field_align
= align
;
2532 #ifdef ADJUST_FIELD_ALIGN
2533 field_align
= ADJUST_FIELD_ALIGN (NULL_TREE
, type
, field_align
);
2535 align
= MIN (align
, field_align
);
2537 return align
/ BITS_PER_UNIT
;
2540 /* Create and return a type for signed integers of PRECISION bits. */
2543 make_signed_type (int precision
)
2545 tree type
= make_node (INTEGER_TYPE
);
2547 TYPE_PRECISION (type
) = precision
;
2549 fixup_signed_type (type
);
2553 /* Create and return a type for unsigned integers of PRECISION bits. */
2556 make_unsigned_type (int precision
)
2558 tree type
= make_node (INTEGER_TYPE
);
2560 TYPE_PRECISION (type
) = precision
;
2562 fixup_unsigned_type (type
);
2566 /* Create and return a type for fract of PRECISION bits, UNSIGNEDP,
2570 make_fract_type (int precision
, int unsignedp
, int satp
)
2572 tree type
= make_node (FIXED_POINT_TYPE
);
2574 TYPE_PRECISION (type
) = precision
;
2577 TYPE_SATURATING (type
) = 1;
2579 /* Lay out the type: set its alignment, size, etc. */
2580 TYPE_UNSIGNED (type
) = unsignedp
;
2581 enum mode_class mclass
= unsignedp
? MODE_UFRACT
: MODE_FRACT
;
2582 SET_TYPE_MODE (type
, mode_for_size (precision
, mclass
, 0).require ());
2588 /* Create and return a type for accum of PRECISION bits, UNSIGNEDP,
2592 make_accum_type (int precision
, int unsignedp
, int satp
)
2594 tree type
= make_node (FIXED_POINT_TYPE
);
2596 TYPE_PRECISION (type
) = precision
;
2599 TYPE_SATURATING (type
) = 1;
2601 /* Lay out the type: set its alignment, size, etc. */
2602 TYPE_UNSIGNED (type
) = unsignedp
;
2603 enum mode_class mclass
= unsignedp
? MODE_UACCUM
: MODE_ACCUM
;
2604 SET_TYPE_MODE (type
, mode_for_size (precision
, mclass
, 0).require ());
2610 /* Initialize sizetypes so layout_type can use them. */
2613 initialize_sizetypes (void)
2615 int precision
, bprecision
;
2617 /* Get sizetypes precision from the SIZE_TYPE target macro. */
2618 if (strcmp (SIZETYPE
, "unsigned int") == 0)
2619 precision
= INT_TYPE_SIZE
;
2620 else if (strcmp (SIZETYPE
, "long unsigned int") == 0)
2621 precision
= LONG_TYPE_SIZE
;
2622 else if (strcmp (SIZETYPE
, "long long unsigned int") == 0)
2623 precision
= LONG_LONG_TYPE_SIZE
;
2624 else if (strcmp (SIZETYPE
, "short unsigned int") == 0)
2625 precision
= SHORT_TYPE_SIZE
;
2631 for (i
= 0; i
< NUM_INT_N_ENTS
; i
++)
2632 if (int_n_enabled_p
[i
])
2635 sprintf (name
, "__int%d unsigned", int_n_data
[i
].bitsize
);
2637 if (strcmp (name
, SIZETYPE
) == 0)
2639 precision
= int_n_data
[i
].bitsize
;
2642 if (precision
== -1)
2647 = MIN (precision
+ LOG2_BITS_PER_UNIT
+ 1, MAX_FIXED_MODE_SIZE
);
2648 bprecision
= GET_MODE_PRECISION (smallest_int_mode_for_size (bprecision
));
2649 if (bprecision
> HOST_BITS_PER_DOUBLE_INT
)
2650 bprecision
= HOST_BITS_PER_DOUBLE_INT
;
2652 /* Create stubs for sizetype and bitsizetype so we can create constants. */
2653 sizetype
= make_node (INTEGER_TYPE
);
2654 TYPE_NAME (sizetype
) = get_identifier ("sizetype");
2655 TYPE_PRECISION (sizetype
) = precision
;
2656 TYPE_UNSIGNED (sizetype
) = 1;
2657 bitsizetype
= make_node (INTEGER_TYPE
);
2658 TYPE_NAME (bitsizetype
) = get_identifier ("bitsizetype");
2659 TYPE_PRECISION (bitsizetype
) = bprecision
;
2660 TYPE_UNSIGNED (bitsizetype
) = 1;
2662 /* Now layout both types manually. */
2663 scalar_int_mode mode
= smallest_int_mode_for_size (precision
);
2664 SET_TYPE_MODE (sizetype
, mode
);
2665 SET_TYPE_ALIGN (sizetype
, GET_MODE_ALIGNMENT (TYPE_MODE (sizetype
)));
2666 TYPE_SIZE (sizetype
) = bitsize_int (precision
);
2667 TYPE_SIZE_UNIT (sizetype
) = size_int (GET_MODE_SIZE (mode
));
2668 set_min_and_max_values_for_integral_type (sizetype
, precision
, UNSIGNED
);
2670 mode
= smallest_int_mode_for_size (bprecision
);
2671 SET_TYPE_MODE (bitsizetype
, mode
);
2672 SET_TYPE_ALIGN (bitsizetype
, GET_MODE_ALIGNMENT (TYPE_MODE (bitsizetype
)));
2673 TYPE_SIZE (bitsizetype
) = bitsize_int (bprecision
);
2674 TYPE_SIZE_UNIT (bitsizetype
) = size_int (GET_MODE_SIZE (mode
));
2675 set_min_and_max_values_for_integral_type (bitsizetype
, bprecision
, UNSIGNED
);
2677 /* Create the signed variants of *sizetype. */
2678 ssizetype
= make_signed_type (TYPE_PRECISION (sizetype
));
2679 TYPE_NAME (ssizetype
) = get_identifier ("ssizetype");
2680 sbitsizetype
= make_signed_type (TYPE_PRECISION (bitsizetype
));
2681 TYPE_NAME (sbitsizetype
) = get_identifier ("sbitsizetype");
2684 /* TYPE is an integral type, i.e., an INTEGRAL_TYPE, ENUMERAL_TYPE
2685 or BOOLEAN_TYPE. Set TYPE_MIN_VALUE and TYPE_MAX_VALUE
2686 for TYPE, based on the PRECISION and whether or not the TYPE
2687 IS_UNSIGNED. PRECISION need not correspond to a width supported
2688 natively by the hardware; for example, on a machine with 8-bit,
2689 16-bit, and 32-bit register modes, PRECISION might be 7, 23, or
2693 set_min_and_max_values_for_integral_type (tree type
,
2697 /* For bitfields with zero width we end up creating integer types
2698 with zero precision. Don't assign any minimum/maximum values
2699 to those types, they don't have any valid value. */
2703 TYPE_MIN_VALUE (type
)
2704 = wide_int_to_tree (type
, wi::min_value (precision
, sgn
));
2705 TYPE_MAX_VALUE (type
)
2706 = wide_int_to_tree (type
, wi::max_value (precision
, sgn
));
2709 /* Set the extreme values of TYPE based on its precision in bits,
2710 then lay it out. Used when make_signed_type won't do
2711 because the tree code is not INTEGER_TYPE. */
2714 fixup_signed_type (tree type
)
2716 int precision
= TYPE_PRECISION (type
);
2718 set_min_and_max_values_for_integral_type (type
, precision
, SIGNED
);
2720 /* Lay out the type: set its alignment, size, etc. */
2724 /* Set the extreme values of TYPE based on its precision in bits,
2725 then lay it out. This is used both in `make_unsigned_type'
2726 and for enumeral types. */
2729 fixup_unsigned_type (tree type
)
2731 int precision
= TYPE_PRECISION (type
);
2733 TYPE_UNSIGNED (type
) = 1;
2735 set_min_and_max_values_for_integral_type (type
, precision
, UNSIGNED
);
2737 /* Lay out the type: set its alignment, size, etc. */
2741 /* Construct an iterator for a bitfield that spans BITSIZE bits,
2744 BITREGION_START is the bit position of the first bit in this
2745 sequence of bit fields. BITREGION_END is the last bit in this
2746 sequence. If these two fields are non-zero, we should restrict the
2747 memory access to that range. Otherwise, we are allowed to touch
2748 any adjacent non bit-fields.
2750 ALIGN is the alignment of the underlying object in bits.
2751 VOLATILEP says whether the bitfield is volatile. */
2753 bit_field_mode_iterator
2754 ::bit_field_mode_iterator (HOST_WIDE_INT bitsize
, HOST_WIDE_INT bitpos
,
2755 poly_int64 bitregion_start
,
2756 poly_int64 bitregion_end
,
2757 unsigned int align
, bool volatilep
)
2758 : m_mode (NARROWEST_INT_MODE
), m_bitsize (bitsize
),
2759 m_bitpos (bitpos
), m_bitregion_start (bitregion_start
),
2760 m_bitregion_end (bitregion_end
), m_align (align
),
2761 m_volatilep (volatilep
), m_count (0)
2763 if (known_eq (m_bitregion_end
, 0))
2765 /* We can assume that any aligned chunk of ALIGN bits that overlaps
2766 the bitfield is mapped and won't trap, provided that ALIGN isn't
2767 too large. The cap is the biggest required alignment for data,
2768 or at least the word size. And force one such chunk at least. */
2769 unsigned HOST_WIDE_INT units
2770 = MIN (align
, MAX (BIGGEST_ALIGNMENT
, BITS_PER_WORD
));
2773 HOST_WIDE_INT end
= bitpos
+ bitsize
+ units
- 1;
2774 m_bitregion_end
= end
- end
% units
- 1;
2778 /* Calls to this function return successively larger modes that can be used
2779 to represent the bitfield. Return true if another bitfield mode is
2780 available, storing it in *OUT_MODE if so. */
2783 bit_field_mode_iterator::next_mode (scalar_int_mode
*out_mode
)
2785 scalar_int_mode mode
;
2786 for (; m_mode
.exists (&mode
); m_mode
= GET_MODE_WIDER_MODE (mode
))
2788 unsigned int unit
= GET_MODE_BITSIZE (mode
);
2790 /* Skip modes that don't have full precision. */
2791 if (unit
!= GET_MODE_PRECISION (mode
))
2794 /* Stop if the mode is too wide to handle efficiently. */
2795 if (unit
> MAX_FIXED_MODE_SIZE
)
2798 /* Don't deliver more than one multiword mode; the smallest one
2800 if (m_count
> 0 && unit
> BITS_PER_WORD
)
2803 /* Skip modes that are too small. */
2804 unsigned HOST_WIDE_INT substart
= (unsigned HOST_WIDE_INT
) m_bitpos
% unit
;
2805 unsigned HOST_WIDE_INT subend
= substart
+ m_bitsize
;
2809 /* Stop if the mode goes outside the bitregion. */
2810 HOST_WIDE_INT start
= m_bitpos
- substart
;
2811 if (maybe_ne (m_bitregion_start
, 0)
2812 && maybe_lt (start
, m_bitregion_start
))
2814 HOST_WIDE_INT end
= start
+ unit
;
2815 if (maybe_gt (end
, m_bitregion_end
+ 1))
2818 /* Stop if the mode requires too much alignment. */
2819 if (GET_MODE_ALIGNMENT (mode
) > m_align
2820 && targetm
.slow_unaligned_access (mode
, m_align
))
2824 m_mode
= GET_MODE_WIDER_MODE (mode
);
2831 /* Return true if smaller modes are generally preferred for this kind
2835 bit_field_mode_iterator::prefer_smaller_modes ()
2838 ? targetm
.narrow_volatile_bitfield ()
2839 : !SLOW_BYTE_ACCESS
);
2842 /* Find the best machine mode to use when referencing a bit field of length
2843 BITSIZE bits starting at BITPOS.
2845 BITREGION_START is the bit position of the first bit in this
2846 sequence of bit fields. BITREGION_END is the last bit in this
2847 sequence. If these two fields are non-zero, we should restrict the
2848 memory access to that range. Otherwise, we are allowed to touch
2849 any adjacent non bit-fields.
2851 The chosen mode must have no more than LARGEST_MODE_BITSIZE bits.
2852 INT_MAX is a suitable value for LARGEST_MODE_BITSIZE if the caller
2853 doesn't want to apply a specific limit.
2855 If no mode meets all these conditions, we return VOIDmode.
2857 The underlying object is known to be aligned to a boundary of ALIGN bits.
2859 If VOLATILEP is false and SLOW_BYTE_ACCESS is false, we return the
2860 smallest mode meeting these conditions.
2862 If VOLATILEP is false and SLOW_BYTE_ACCESS is true, we return the
2863 largest mode (but a mode no wider than UNITS_PER_WORD) that meets
2866 If VOLATILEP is true the narrow_volatile_bitfields target hook is used to
2867 decide which of the above modes should be used. */
2870 get_best_mode (int bitsize
, int bitpos
,
2871 poly_uint64 bitregion_start
, poly_uint64 bitregion_end
,
2873 unsigned HOST_WIDE_INT largest_mode_bitsize
, bool volatilep
,
2874 scalar_int_mode
*best_mode
)
2876 bit_field_mode_iterator
iter (bitsize
, bitpos
, bitregion_start
,
2877 bitregion_end
, align
, volatilep
);
2878 scalar_int_mode mode
;
2880 while (iter
.next_mode (&mode
)
2881 /* ??? For historical reasons, reject modes that would normally
2882 receive greater alignment, even if unaligned accesses are
2883 acceptable. This has both advantages and disadvantages.
2884 Removing this check means that something like:
2886 struct s { unsigned int x; unsigned int y; };
2887 int f (struct s *s) { return s->x == 0 && s->y == 0; }
2889 can be implemented using a single load and compare on
2890 64-bit machines that have no alignment restrictions.
2891 For example, on powerpc64-linux-gnu, we would generate:
2913 However, accessing more than one field can make life harder
2914 for the gimple optimizers. For example, gcc.dg/vect/bb-slp-5.c
2915 has a series of unsigned short copies followed by a series of
2916 unsigned short comparisons. With this check, both the copies
2917 and comparisons remain 16-bit accesses and FRE is able
2918 to eliminate the latter. Without the check, the comparisons
2919 can be done using 2 64-bit operations, which FRE isn't able
2920 to handle in the same way.
2922 Either way, it would probably be worth disabling this check
2923 during expand. One particular example where removing the
2924 check would help is the get_best_mode call in store_bit_field.
2925 If we are given a memory bitregion of 128 bits that is aligned
2926 to a 64-bit boundary, and the bitfield we want to modify is
2927 in the second half of the bitregion, this check causes
2928 store_bitfield to turn the memory into a 64-bit reference
2929 to the _first_ half of the region. We later use
2930 adjust_bitfield_address to get a reference to the correct half,
2931 but doing so looks to adjust_bitfield_address as though we are
2932 moving past the end of the original object, so it drops the
2933 associated MEM_EXPR and MEM_OFFSET. Removing the check
2934 causes store_bit_field to keep a 128-bit memory reference,
2935 so that the final bitfield reference still has a MEM_EXPR
2937 && GET_MODE_ALIGNMENT (mode
) <= align
2938 && GET_MODE_BITSIZE (mode
) <= largest_mode_bitsize
)
2942 if (iter
.prefer_smaller_modes ())
2949 /* Gets minimal and maximal values for MODE (signed or unsigned depending on
2950 SIGN). The returned constants are made to be usable in TARGET_MODE. */
2953 get_mode_bounds (scalar_int_mode mode
, int sign
,
2954 scalar_int_mode target_mode
,
2955 rtx
*mmin
, rtx
*mmax
)
2957 unsigned size
= GET_MODE_PRECISION (mode
);
2958 unsigned HOST_WIDE_INT min_val
, max_val
;
2960 gcc_assert (size
<= HOST_BITS_PER_WIDE_INT
);
2962 /* Special case BImode, which has values 0 and STORE_FLAG_VALUE. */
2965 if (STORE_FLAG_VALUE
< 0)
2967 min_val
= STORE_FLAG_VALUE
;
2973 max_val
= STORE_FLAG_VALUE
;
2978 min_val
= -(HOST_WIDE_INT_1U
<< (size
- 1));
2979 max_val
= (HOST_WIDE_INT_1U
<< (size
- 1)) - 1;
2984 max_val
= (HOST_WIDE_INT_1U
<< (size
- 1) << 1) - 1;
2987 *mmin
= gen_int_mode (min_val
, target_mode
);
2988 *mmax
= gen_int_mode (max_val
, target_mode
);
2991 #include "gt-stor-layout.h"