1 /* C-compiler utilities for types and variables storage layout
2 Copyright (C) 1987-2017 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
23 #include "coretypes.h"
30 #include "stringpool.h"
34 #include "diagnostic-core.h"
35 #include "fold-const.h"
36 #include "stor-layout.h"
38 #include "print-tree.h"
39 #include "langhooks.h"
40 #include "tree-inline.h"
45 /* Data type for the expressions representing sizes of data types.
46 It is the first integer type laid out. */
47 tree sizetype_tab
[(int) stk_type_kind_last
];
49 /* If nonzero, this is an upper limit on alignment of structure fields.
50 The value is measured in bits. */
51 unsigned int maximum_field_alignment
= TARGET_DEFAULT_PACK_STRUCT
* BITS_PER_UNIT
;
53 static tree
self_referential_size (tree
);
54 static void finalize_record_size (record_layout_info
);
55 static void finalize_type_size (tree
);
56 static void place_union_field (record_layout_info
, tree
);
57 static int excess_unit_span (HOST_WIDE_INT
, HOST_WIDE_INT
, HOST_WIDE_INT
,
59 extern void debug_rli (record_layout_info
);
61 /* Given a size SIZE that may not be a constant, return a SAVE_EXPR
62 to serve as the actual size-expression for a type or decl. */
65 variable_size (tree size
)
68 if (TREE_CONSTANT (size
))
71 /* If the size is self-referential, we can't make a SAVE_EXPR (see
72 save_expr for the rationale). But we can do something else. */
73 if (CONTAINS_PLACEHOLDER_P (size
))
74 return self_referential_size (size
);
76 /* If we are in the global binding level, we can't make a SAVE_EXPR
77 since it may end up being shared across functions, so it is up
78 to the front-end to deal with this case. */
79 if (lang_hooks
.decls
.global_bindings_p ())
82 return save_expr (size
);
85 /* An array of functions used for self-referential size computation. */
86 static GTY(()) vec
<tree
, va_gc
> *size_functions
;
88 /* Return true if T is a self-referential component reference. */
91 self_referential_component_ref_p (tree t
)
93 if (TREE_CODE (t
) != COMPONENT_REF
)
96 while (REFERENCE_CLASS_P (t
))
97 t
= TREE_OPERAND (t
, 0);
99 return (TREE_CODE (t
) == PLACEHOLDER_EXPR
);
102 /* Similar to copy_tree_r but do not copy component references involving
103 PLACEHOLDER_EXPRs. These nodes are spotted in find_placeholder_in_expr
104 and substituted in substitute_in_expr. */
107 copy_self_referential_tree_r (tree
*tp
, int *walk_subtrees
, void *data
)
109 enum tree_code code
= TREE_CODE (*tp
);
111 /* Stop at types, decls, constants like copy_tree_r. */
112 if (TREE_CODE_CLASS (code
) == tcc_type
113 || TREE_CODE_CLASS (code
) == tcc_declaration
114 || TREE_CODE_CLASS (code
) == tcc_constant
)
120 /* This is the pattern built in ada/make_aligning_type. */
121 else if (code
== ADDR_EXPR
122 && TREE_CODE (TREE_OPERAND (*tp
, 0)) == PLACEHOLDER_EXPR
)
128 /* Default case: the component reference. */
129 else if (self_referential_component_ref_p (*tp
))
135 /* We're not supposed to have them in self-referential size trees
136 because we wouldn't properly control when they are evaluated.
137 However, not creating superfluous SAVE_EXPRs requires accurate
138 tracking of readonly-ness all the way down to here, which we
139 cannot always guarantee in practice. So punt in this case. */
140 else if (code
== SAVE_EXPR
)
141 return error_mark_node
;
143 else if (code
== STATEMENT_LIST
)
146 return copy_tree_r (tp
, walk_subtrees
, data
);
149 /* Given a SIZE expression that is self-referential, return an equivalent
150 expression to serve as the actual size expression for a type. */
153 self_referential_size (tree size
)
155 static unsigned HOST_WIDE_INT fnno
= 0;
156 vec
<tree
> self_refs
= vNULL
;
157 tree param_type_list
= NULL
, param_decl_list
= NULL
;
158 tree t
, ref
, return_type
, fntype
, fnname
, fndecl
;
161 vec
<tree
, va_gc
> *args
= NULL
;
163 /* Do not factor out simple operations. */
164 t
= skip_simple_constant_arithmetic (size
);
165 if (TREE_CODE (t
) == CALL_EXPR
|| self_referential_component_ref_p (t
))
168 /* Collect the list of self-references in the expression. */
169 find_placeholder_in_expr (size
, &self_refs
);
170 gcc_assert (self_refs
.length () > 0);
172 /* Obtain a private copy of the expression. */
174 if (walk_tree (&t
, copy_self_referential_tree_r
, NULL
, NULL
) != NULL_TREE
)
178 /* Build the parameter and argument lists in parallel; also
179 substitute the former for the latter in the expression. */
180 vec_alloc (args
, self_refs
.length ());
181 FOR_EACH_VEC_ELT (self_refs
, i
, ref
)
183 tree subst
, param_name
, param_type
, param_decl
;
187 /* We shouldn't have true variables here. */
188 gcc_assert (TREE_READONLY (ref
));
191 /* This is the pattern built in ada/make_aligning_type. */
192 else if (TREE_CODE (ref
) == ADDR_EXPR
)
194 /* Default case: the component reference. */
196 subst
= TREE_OPERAND (ref
, 1);
198 sprintf (buf
, "p%d", i
);
199 param_name
= get_identifier (buf
);
200 param_type
= TREE_TYPE (ref
);
202 = build_decl (input_location
, PARM_DECL
, param_name
, param_type
);
203 DECL_ARG_TYPE (param_decl
) = param_type
;
204 DECL_ARTIFICIAL (param_decl
) = 1;
205 TREE_READONLY (param_decl
) = 1;
207 size
= substitute_in_expr (size
, subst
, param_decl
);
209 param_type_list
= tree_cons (NULL_TREE
, param_type
, param_type_list
);
210 param_decl_list
= chainon (param_decl
, param_decl_list
);
211 args
->quick_push (ref
);
214 self_refs
.release ();
216 /* Append 'void' to indicate that the number of parameters is fixed. */
217 param_type_list
= tree_cons (NULL_TREE
, void_type_node
, param_type_list
);
219 /* The 3 lists have been created in reverse order. */
220 param_type_list
= nreverse (param_type_list
);
221 param_decl_list
= nreverse (param_decl_list
);
223 /* Build the function type. */
224 return_type
= TREE_TYPE (size
);
225 fntype
= build_function_type (return_type
, param_type_list
);
227 /* Build the function declaration. */
228 sprintf (buf
, "SZ" HOST_WIDE_INT_PRINT_UNSIGNED
, fnno
++);
229 fnname
= get_file_function_name (buf
);
230 fndecl
= build_decl (input_location
, FUNCTION_DECL
, fnname
, fntype
);
231 for (t
= param_decl_list
; t
; t
= DECL_CHAIN (t
))
232 DECL_CONTEXT (t
) = fndecl
;
233 DECL_ARGUMENTS (fndecl
) = param_decl_list
;
235 = build_decl (input_location
, RESULT_DECL
, 0, return_type
);
236 DECL_CONTEXT (DECL_RESULT (fndecl
)) = fndecl
;
238 /* The function has been created by the compiler and we don't
239 want to emit debug info for it. */
240 DECL_ARTIFICIAL (fndecl
) = 1;
241 DECL_IGNORED_P (fndecl
) = 1;
243 /* It is supposed to be "const" and never throw. */
244 TREE_READONLY (fndecl
) = 1;
245 TREE_NOTHROW (fndecl
) = 1;
247 /* We want it to be inlined when this is deemed profitable, as
248 well as discarded if every call has been integrated. */
249 DECL_DECLARED_INLINE_P (fndecl
) = 1;
251 /* It is made up of a unique return statement. */
252 DECL_INITIAL (fndecl
) = make_node (BLOCK
);
253 BLOCK_SUPERCONTEXT (DECL_INITIAL (fndecl
)) = fndecl
;
254 t
= build2 (MODIFY_EXPR
, return_type
, DECL_RESULT (fndecl
), size
);
255 DECL_SAVED_TREE (fndecl
) = build1 (RETURN_EXPR
, void_type_node
, t
);
256 TREE_STATIC (fndecl
) = 1;
258 /* Put it onto the list of size functions. */
259 vec_safe_push (size_functions
, fndecl
);
261 /* Replace the original expression with a call to the size function. */
262 return build_call_expr_loc_vec (UNKNOWN_LOCATION
, fndecl
, args
);
265 /* Take, queue and compile all the size functions. It is essential that
266 the size functions be gimplified at the very end of the compilation
267 in order to guarantee transparent handling of self-referential sizes.
268 Otherwise the GENERIC inliner would not be able to inline them back
269 at each of their call sites, thus creating artificial non-constant
270 size expressions which would trigger nasty problems later on. */
273 finalize_size_functions (void)
278 for (i
= 0; size_functions
&& size_functions
->iterate (i
, &fndecl
); i
++)
280 allocate_struct_function (fndecl
, false);
282 dump_function (TDI_original
, fndecl
);
284 /* As these functions are used to describe the layout of variable-length
285 structures, debug info generation needs their implementation. */
286 debug_hooks
->size_function (fndecl
);
287 gimplify_function_tree (fndecl
);
288 cgraph_node::finalize_function (fndecl
, false);
291 vec_free (size_functions
);
294 /* Return the machine mode to use for a nonscalar of SIZE bits. The
295 mode must be in class MCLASS, and have exactly that many value bits;
296 it may have padding as well. If LIMIT is nonzero, modes of wider
297 than MAX_FIXED_MODE_SIZE will not be used. */
300 mode_for_size (unsigned int size
, enum mode_class mclass
, int limit
)
305 if (limit
&& size
> MAX_FIXED_MODE_SIZE
)
308 /* Get the first mode which has this size, in the specified class. */
309 FOR_EACH_MODE_IN_CLASS (mode
, mclass
)
310 if (GET_MODE_PRECISION (mode
) == size
)
313 if (mclass
== MODE_INT
|| mclass
== MODE_PARTIAL_INT
)
314 for (i
= 0; i
< NUM_INT_N_ENTS
; i
++)
315 if (int_n_data
[i
].bitsize
== size
316 && int_n_enabled_p
[i
])
317 return int_n_data
[i
].m
;
322 /* Similar, except passed a tree node. */
325 mode_for_size_tree (const_tree size
, enum mode_class mclass
, int limit
)
327 unsigned HOST_WIDE_INT uhwi
;
330 if (!tree_fits_uhwi_p (size
))
332 uhwi
= tree_to_uhwi (size
);
336 return mode_for_size (ui
, mclass
, limit
);
339 /* Similar, but never return BLKmode; return the narrowest mode that
340 contains at least the requested number of value bits. */
343 smallest_mode_for_size (unsigned int size
, enum mode_class mclass
)
345 machine_mode mode
= VOIDmode
;
348 /* Get the first mode which has at least this size, in the
350 FOR_EACH_MODE_IN_CLASS (mode
, mclass
)
351 if (GET_MODE_PRECISION (mode
) >= size
)
354 if (mclass
== MODE_INT
|| mclass
== MODE_PARTIAL_INT
)
355 for (i
= 0; i
< NUM_INT_N_ENTS
; i
++)
356 if (int_n_data
[i
].bitsize
>= size
357 && int_n_data
[i
].bitsize
< GET_MODE_PRECISION (mode
)
358 && int_n_enabled_p
[i
])
359 mode
= int_n_data
[i
].m
;
361 if (mode
== VOIDmode
)
367 /* Return an integer mode of exactly the same size as MODE, if one exists. */
370 int_mode_for_mode (machine_mode mode
)
372 switch (GET_MODE_CLASS (mode
))
375 case MODE_PARTIAL_INT
:
376 return as_a
<scalar_int_mode
> (mode
);
378 case MODE_COMPLEX_INT
:
379 case MODE_COMPLEX_FLOAT
:
381 case MODE_DECIMAL_FLOAT
:
382 case MODE_VECTOR_INT
:
383 case MODE_VECTOR_FLOAT
:
388 case MODE_VECTOR_FRACT
:
389 case MODE_VECTOR_ACCUM
:
390 case MODE_VECTOR_UFRACT
:
391 case MODE_VECTOR_UACCUM
:
392 case MODE_POINTER_BOUNDS
:
393 return int_mode_for_size (GET_MODE_BITSIZE (mode
), 0);
397 return opt_scalar_int_mode ();
407 /* Find a mode that can be used for efficient bitwise operations on MODE.
408 Return BLKmode if no such mode exists. */
411 bitwise_mode_for_mode (machine_mode mode
)
413 /* Quick exit if we already have a suitable mode. */
414 unsigned int bitsize
= GET_MODE_BITSIZE (mode
);
415 scalar_int_mode int_mode
;
416 if (is_a
<scalar_int_mode
> (mode
, &int_mode
)
417 && GET_MODE_BITSIZE (int_mode
) <= MAX_FIXED_MODE_SIZE
)
420 /* Reuse the sanity checks from int_mode_for_mode. */
421 gcc_checking_assert ((int_mode_for_mode (mode
), true));
423 /* Try to replace complex modes with complex modes. In general we
424 expect both components to be processed independently, so we only
425 care whether there is a register for the inner mode. */
426 if (COMPLEX_MODE_P (mode
))
428 machine_mode trial
= mode
;
429 if (GET_MODE_CLASS (mode
) != MODE_COMPLEX_INT
)
430 trial
= mode_for_size (bitsize
, MODE_COMPLEX_INT
, false);
432 && have_regs_of_mode
[GET_MODE_INNER (trial
)])
436 /* Try to replace vector modes with vector modes. Also try using vector
437 modes if an integer mode would be too big. */
438 if (VECTOR_MODE_P (mode
) || bitsize
> MAX_FIXED_MODE_SIZE
)
440 machine_mode trial
= mode
;
441 if (GET_MODE_CLASS (mode
) != MODE_VECTOR_INT
)
442 trial
= mode_for_size (bitsize
, MODE_VECTOR_INT
, 0);
444 && have_regs_of_mode
[trial
]
445 && targetm
.vector_mode_supported_p (trial
))
449 /* Otherwise fall back on integers while honoring MAX_FIXED_MODE_SIZE. */
450 return mode_for_size (bitsize
, MODE_INT
, true);
453 /* Find a type that can be used for efficient bitwise operations on MODE.
454 Return null if no such mode exists. */
457 bitwise_type_for_mode (machine_mode mode
)
459 mode
= bitwise_mode_for_mode (mode
);
463 unsigned int inner_size
= GET_MODE_UNIT_BITSIZE (mode
);
464 tree inner_type
= build_nonstandard_integer_type (inner_size
, true);
466 if (VECTOR_MODE_P (mode
))
467 return build_vector_type_for_mode (inner_type
, mode
);
469 if (COMPLEX_MODE_P (mode
))
470 return build_complex_type (inner_type
);
472 gcc_checking_assert (GET_MODE_INNER (mode
) == mode
);
476 /* Find a mode that is suitable for representing a vector with
477 NUNITS elements of mode INNERMODE. Returns BLKmode if there
478 is no suitable mode. */
481 mode_for_vector (machine_mode innermode
, unsigned nunits
)
485 /* First, look for a supported vector type. */
486 if (SCALAR_FLOAT_MODE_P (innermode
))
487 mode
= MIN_MODE_VECTOR_FLOAT
;
488 else if (SCALAR_FRACT_MODE_P (innermode
))
489 mode
= MIN_MODE_VECTOR_FRACT
;
490 else if (SCALAR_UFRACT_MODE_P (innermode
))
491 mode
= MIN_MODE_VECTOR_UFRACT
;
492 else if (SCALAR_ACCUM_MODE_P (innermode
))
493 mode
= MIN_MODE_VECTOR_ACCUM
;
494 else if (SCALAR_UACCUM_MODE_P (innermode
))
495 mode
= MIN_MODE_VECTOR_UACCUM
;
497 mode
= MIN_MODE_VECTOR_INT
;
499 /* Do not check vector_mode_supported_p here. We'll do that
500 later in vector_type_mode. */
501 FOR_EACH_MODE_FROM (mode
, mode
)
502 if (GET_MODE_NUNITS (mode
) == nunits
503 && GET_MODE_INNER (mode
) == innermode
)
506 /* For integers, try mapping it to a same-sized scalar mode. */
508 && GET_MODE_CLASS (innermode
) == MODE_INT
)
509 mode
= mode_for_size (nunits
* GET_MODE_BITSIZE (innermode
),
513 || (GET_MODE_CLASS (mode
) == MODE_INT
514 && !have_regs_of_mode
[mode
]))
520 /* Return the alignment of MODE. This will be bounded by 1 and
521 BIGGEST_ALIGNMENT. */
524 get_mode_alignment (machine_mode mode
)
526 return MIN (BIGGEST_ALIGNMENT
, MAX (1, mode_base_align
[mode
]*BITS_PER_UNIT
));
529 /* Return the natural mode of an array, given that it is SIZE bytes in
530 total and has elements of type ELEM_TYPE. */
533 mode_for_array (tree elem_type
, tree size
)
536 unsigned HOST_WIDE_INT int_size
, int_elem_size
;
539 /* One-element arrays get the component type's mode. */
540 elem_size
= TYPE_SIZE (elem_type
);
541 if (simple_cst_equal (size
, elem_size
))
542 return TYPE_MODE (elem_type
);
545 if (tree_fits_uhwi_p (size
) && tree_fits_uhwi_p (elem_size
))
547 int_size
= tree_to_uhwi (size
);
548 int_elem_size
= tree_to_uhwi (elem_size
);
549 if (int_elem_size
> 0
550 && int_size
% int_elem_size
== 0
551 && targetm
.array_mode_supported_p (TYPE_MODE (elem_type
),
552 int_size
/ int_elem_size
))
555 return mode_for_size_tree (size
, MODE_INT
, limit_p
);
558 /* Subroutine of layout_decl: Force alignment required for the data type.
559 But if the decl itself wants greater alignment, don't override that. */
562 do_type_align (tree type
, tree decl
)
564 if (TYPE_ALIGN (type
) > DECL_ALIGN (decl
))
566 SET_DECL_ALIGN (decl
, TYPE_ALIGN (type
));
567 if (TREE_CODE (decl
) == FIELD_DECL
)
568 DECL_USER_ALIGN (decl
) = TYPE_USER_ALIGN (type
);
570 if (TYPE_WARN_IF_NOT_ALIGN (type
) > DECL_WARN_IF_NOT_ALIGN (decl
))
571 SET_DECL_WARN_IF_NOT_ALIGN (decl
, TYPE_WARN_IF_NOT_ALIGN (type
));
574 /* Set the size, mode and alignment of a ..._DECL node.
575 TYPE_DECL does need this for C++.
576 Note that LABEL_DECL and CONST_DECL nodes do not need this,
577 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
578 Don't call layout_decl for them.
580 KNOWN_ALIGN is the amount of alignment we can assume this
581 decl has with no special effort. It is relevant only for FIELD_DECLs
582 and depends on the previous fields.
583 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
584 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
585 the record will be aligned to suit. */
588 layout_decl (tree decl
, unsigned int known_align
)
590 tree type
= TREE_TYPE (decl
);
591 enum tree_code code
= TREE_CODE (decl
);
593 location_t loc
= DECL_SOURCE_LOCATION (decl
);
595 if (code
== CONST_DECL
)
598 gcc_assert (code
== VAR_DECL
|| code
== PARM_DECL
|| code
== RESULT_DECL
599 || code
== TYPE_DECL
|| code
== FIELD_DECL
);
601 rtl
= DECL_RTL_IF_SET (decl
);
603 if (type
== error_mark_node
)
604 type
= void_type_node
;
606 /* Usually the size and mode come from the data type without change,
607 however, the front-end may set the explicit width of the field, so its
608 size may not be the same as the size of its type. This happens with
609 bitfields, of course (an `int' bitfield may be only 2 bits, say), but it
610 also happens with other fields. For example, the C++ front-end creates
611 zero-sized fields corresponding to empty base classes, and depends on
612 layout_type setting DECL_FIELD_BITPOS correctly for the field. Set the
613 size in bytes from the size in bits. If we have already set the mode,
614 don't set it again since we can be called twice for FIELD_DECLs. */
616 DECL_UNSIGNED (decl
) = TYPE_UNSIGNED (type
);
617 if (DECL_MODE (decl
) == VOIDmode
)
618 SET_DECL_MODE (decl
, TYPE_MODE (type
));
620 if (DECL_SIZE (decl
) == 0)
622 DECL_SIZE (decl
) = TYPE_SIZE (type
);
623 DECL_SIZE_UNIT (decl
) = TYPE_SIZE_UNIT (type
);
625 else if (DECL_SIZE_UNIT (decl
) == 0)
626 DECL_SIZE_UNIT (decl
)
627 = fold_convert_loc (loc
, sizetype
,
628 size_binop_loc (loc
, CEIL_DIV_EXPR
, DECL_SIZE (decl
),
631 if (code
!= FIELD_DECL
)
632 /* For non-fields, update the alignment from the type. */
633 do_type_align (type
, decl
);
635 /* For fields, it's a bit more complicated... */
637 bool old_user_align
= DECL_USER_ALIGN (decl
);
638 bool zero_bitfield
= false;
639 bool packed_p
= DECL_PACKED (decl
);
642 if (DECL_BIT_FIELD (decl
))
644 DECL_BIT_FIELD_TYPE (decl
) = type
;
646 /* A zero-length bit-field affects the alignment of the next
647 field. In essence such bit-fields are not influenced by
648 any packing due to #pragma pack or attribute packed. */
649 if (integer_zerop (DECL_SIZE (decl
))
650 && ! targetm
.ms_bitfield_layout_p (DECL_FIELD_CONTEXT (decl
)))
652 zero_bitfield
= true;
654 if (PCC_BITFIELD_TYPE_MATTERS
)
655 do_type_align (type
, decl
);
658 #ifdef EMPTY_FIELD_BOUNDARY
659 if (EMPTY_FIELD_BOUNDARY
> DECL_ALIGN (decl
))
661 SET_DECL_ALIGN (decl
, EMPTY_FIELD_BOUNDARY
);
662 DECL_USER_ALIGN (decl
) = 0;
668 /* See if we can use an ordinary integer mode for a bit-field.
669 Conditions are: a fixed size that is correct for another mode,
670 occupying a complete byte or bytes on proper boundary. */
671 if (TYPE_SIZE (type
) != 0
672 && TREE_CODE (TYPE_SIZE (type
)) == INTEGER_CST
673 && GET_MODE_CLASS (TYPE_MODE (type
)) == MODE_INT
)
676 = mode_for_size_tree (DECL_SIZE (decl
), MODE_INT
, 1);
677 unsigned int xalign
= GET_MODE_ALIGNMENT (xmode
);
680 && !(xalign
> BITS_PER_UNIT
&& DECL_PACKED (decl
))
681 && (known_align
== 0 || known_align
>= xalign
))
683 SET_DECL_ALIGN (decl
, MAX (xalign
, DECL_ALIGN (decl
)));
684 SET_DECL_MODE (decl
, xmode
);
685 DECL_BIT_FIELD (decl
) = 0;
689 /* Turn off DECL_BIT_FIELD if we won't need it set. */
690 if (TYPE_MODE (type
) == BLKmode
&& DECL_MODE (decl
) == BLKmode
691 && known_align
>= TYPE_ALIGN (type
)
692 && DECL_ALIGN (decl
) >= TYPE_ALIGN (type
))
693 DECL_BIT_FIELD (decl
) = 0;
695 else if (packed_p
&& DECL_USER_ALIGN (decl
))
696 /* Don't touch DECL_ALIGN. For other packed fields, go ahead and
697 round up; we'll reduce it again below. We want packing to
698 supersede USER_ALIGN inherited from the type, but defer to
699 alignment explicitly specified on the field decl. */;
701 do_type_align (type
, decl
);
703 /* If the field is packed and not explicitly aligned, give it the
704 minimum alignment. Note that do_type_align may set
705 DECL_USER_ALIGN, so we need to check old_user_align instead. */
708 SET_DECL_ALIGN (decl
, MIN (DECL_ALIGN (decl
), BITS_PER_UNIT
));
710 if (! packed_p
&& ! DECL_USER_ALIGN (decl
))
712 /* Some targets (i.e. i386, VMS) limit struct field alignment
713 to a lower boundary than alignment of variables unless
714 it was overridden by attribute aligned. */
715 #ifdef BIGGEST_FIELD_ALIGNMENT
716 SET_DECL_ALIGN (decl
, MIN (DECL_ALIGN (decl
),
717 (unsigned) BIGGEST_FIELD_ALIGNMENT
));
719 #ifdef ADJUST_FIELD_ALIGN
720 SET_DECL_ALIGN (decl
, ADJUST_FIELD_ALIGN (decl
, TREE_TYPE (decl
),
726 mfa
= initial_max_fld_align
* BITS_PER_UNIT
;
728 mfa
= maximum_field_alignment
;
729 /* Should this be controlled by DECL_USER_ALIGN, too? */
731 SET_DECL_ALIGN (decl
, MIN (DECL_ALIGN (decl
), mfa
));
734 /* Evaluate nonconstant size only once, either now or as soon as safe. */
735 if (DECL_SIZE (decl
) != 0 && TREE_CODE (DECL_SIZE (decl
)) != INTEGER_CST
)
736 DECL_SIZE (decl
) = variable_size (DECL_SIZE (decl
));
737 if (DECL_SIZE_UNIT (decl
) != 0
738 && TREE_CODE (DECL_SIZE_UNIT (decl
)) != INTEGER_CST
)
739 DECL_SIZE_UNIT (decl
) = variable_size (DECL_SIZE_UNIT (decl
));
741 /* If requested, warn about definitions of large data objects. */
743 && (code
== VAR_DECL
|| code
== PARM_DECL
)
744 && ! DECL_EXTERNAL (decl
))
746 tree size
= DECL_SIZE_UNIT (decl
);
748 if (size
!= 0 && TREE_CODE (size
) == INTEGER_CST
749 && compare_tree_int (size
, larger_than_size
) > 0)
751 int size_as_int
= TREE_INT_CST_LOW (size
);
753 if (compare_tree_int (size
, size_as_int
) == 0)
754 warning (OPT_Wlarger_than_
, "size of %q+D is %d bytes", decl
, size_as_int
);
756 warning (OPT_Wlarger_than_
, "size of %q+D is larger than %wd bytes",
757 decl
, larger_than_size
);
761 /* If the RTL was already set, update its mode and mem attributes. */
764 PUT_MODE (rtl
, DECL_MODE (decl
));
765 SET_DECL_RTL (decl
, 0);
767 set_mem_attributes (rtl
, decl
, 1);
768 SET_DECL_RTL (decl
, rtl
);
772 /* Given a VAR_DECL, PARM_DECL, RESULT_DECL, or FIELD_DECL, clears the
773 results of a previous call to layout_decl and calls it again. */
776 relayout_decl (tree decl
)
778 DECL_SIZE (decl
) = DECL_SIZE_UNIT (decl
) = 0;
779 SET_DECL_MODE (decl
, VOIDmode
);
780 if (!DECL_USER_ALIGN (decl
))
781 SET_DECL_ALIGN (decl
, 0);
782 if (DECL_RTL_SET_P (decl
))
783 SET_DECL_RTL (decl
, 0);
785 layout_decl (decl
, 0);
788 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
789 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
790 is to be passed to all other layout functions for this record. It is the
791 responsibility of the caller to call `free' for the storage returned.
792 Note that garbage collection is not permitted until we finish laying
796 start_record_layout (tree t
)
798 record_layout_info rli
= XNEW (struct record_layout_info_s
);
802 /* If the type has a minimum specified alignment (via an attribute
803 declaration, for example) use it -- otherwise, start with a
804 one-byte alignment. */
805 rli
->record_align
= MAX (BITS_PER_UNIT
, TYPE_ALIGN (t
));
806 rli
->unpacked_align
= rli
->record_align
;
807 rli
->offset_align
= MAX (rli
->record_align
, BIGGEST_ALIGNMENT
);
809 #ifdef STRUCTURE_SIZE_BOUNDARY
810 /* Packed structures don't need to have minimum size. */
811 if (! TYPE_PACKED (t
))
815 /* #pragma pack overrides STRUCTURE_SIZE_BOUNDARY. */
816 tmp
= (unsigned) STRUCTURE_SIZE_BOUNDARY
;
817 if (maximum_field_alignment
!= 0)
818 tmp
= MIN (tmp
, maximum_field_alignment
);
819 rli
->record_align
= MAX (rli
->record_align
, tmp
);
823 rli
->offset
= size_zero_node
;
824 rli
->bitpos
= bitsize_zero_node
;
826 rli
->pending_statics
= 0;
827 rli
->packed_maybe_necessary
= 0;
828 rli
->remaining_in_alignment
= 0;
833 /* Return the combined bit position for the byte offset OFFSET and the
836 These functions operate on byte and bit positions present in FIELD_DECLs
837 and assume that these expressions result in no (intermediate) overflow.
838 This assumption is necessary to fold the expressions as much as possible,
839 so as to avoid creating artificially variable-sized types in languages
840 supporting variable-sized types like Ada. */
843 bit_from_pos (tree offset
, tree bitpos
)
845 if (TREE_CODE (offset
) == PLUS_EXPR
)
846 offset
= size_binop (PLUS_EXPR
,
847 fold_convert (bitsizetype
, TREE_OPERAND (offset
, 0)),
848 fold_convert (bitsizetype
, TREE_OPERAND (offset
, 1)));
850 offset
= fold_convert (bitsizetype
, offset
);
851 return size_binop (PLUS_EXPR
, bitpos
,
852 size_binop (MULT_EXPR
, offset
, bitsize_unit_node
));
855 /* Return the combined truncated byte position for the byte offset OFFSET and
856 the bit position BITPOS. */
859 byte_from_pos (tree offset
, tree bitpos
)
862 if (TREE_CODE (bitpos
) == MULT_EXPR
863 && tree_int_cst_equal (TREE_OPERAND (bitpos
, 1), bitsize_unit_node
))
864 bytepos
= TREE_OPERAND (bitpos
, 0);
866 bytepos
= size_binop (TRUNC_DIV_EXPR
, bitpos
, bitsize_unit_node
);
867 return size_binop (PLUS_EXPR
, offset
, fold_convert (sizetype
, bytepos
));
870 /* Split the bit position POS into a byte offset *POFFSET and a bit
871 position *PBITPOS with the byte offset aligned to OFF_ALIGN bits. */
874 pos_from_bit (tree
*poffset
, tree
*pbitpos
, unsigned int off_align
,
877 tree toff_align
= bitsize_int (off_align
);
878 if (TREE_CODE (pos
) == MULT_EXPR
879 && tree_int_cst_equal (TREE_OPERAND (pos
, 1), toff_align
))
881 *poffset
= size_binop (MULT_EXPR
,
882 fold_convert (sizetype
, TREE_OPERAND (pos
, 0)),
883 size_int (off_align
/ BITS_PER_UNIT
));
884 *pbitpos
= bitsize_zero_node
;
888 *poffset
= size_binop (MULT_EXPR
,
889 fold_convert (sizetype
,
890 size_binop (FLOOR_DIV_EXPR
, pos
,
892 size_int (off_align
/ BITS_PER_UNIT
));
893 *pbitpos
= size_binop (FLOOR_MOD_EXPR
, pos
, toff_align
);
897 /* Given a pointer to bit and byte offsets and an offset alignment,
898 normalize the offsets so they are within the alignment. */
901 normalize_offset (tree
*poffset
, tree
*pbitpos
, unsigned int off_align
)
903 /* If the bit position is now larger than it should be, adjust it
905 if (compare_tree_int (*pbitpos
, off_align
) >= 0)
908 pos_from_bit (&offset
, &bitpos
, off_align
, *pbitpos
);
909 *poffset
= size_binop (PLUS_EXPR
, *poffset
, offset
);
914 /* Print debugging information about the information in RLI. */
917 debug_rli (record_layout_info rli
)
919 print_node_brief (stderr
, "type", rli
->t
, 0);
920 print_node_brief (stderr
, "\noffset", rli
->offset
, 0);
921 print_node_brief (stderr
, " bitpos", rli
->bitpos
, 0);
923 fprintf (stderr
, "\naligns: rec = %u, unpack = %u, off = %u\n",
924 rli
->record_align
, rli
->unpacked_align
,
927 /* The ms_struct code is the only that uses this. */
928 if (targetm
.ms_bitfield_layout_p (rli
->t
))
929 fprintf (stderr
, "remaining in alignment = %u\n", rli
->remaining_in_alignment
);
931 if (rli
->packed_maybe_necessary
)
932 fprintf (stderr
, "packed may be necessary\n");
934 if (!vec_safe_is_empty (rli
->pending_statics
))
936 fprintf (stderr
, "pending statics:\n");
937 debug_vec_tree (rli
->pending_statics
);
941 /* Given an RLI with a possibly-incremented BITPOS, adjust OFFSET and
942 BITPOS if necessary to keep BITPOS below OFFSET_ALIGN. */
945 normalize_rli (record_layout_info rli
)
947 normalize_offset (&rli
->offset
, &rli
->bitpos
, rli
->offset_align
);
950 /* Returns the size in bytes allocated so far. */
953 rli_size_unit_so_far (record_layout_info rli
)
955 return byte_from_pos (rli
->offset
, rli
->bitpos
);
958 /* Returns the size in bits allocated so far. */
961 rli_size_so_far (record_layout_info rli
)
963 return bit_from_pos (rli
->offset
, rli
->bitpos
);
966 /* FIELD is about to be added to RLI->T. The alignment (in bits) of
967 the next available location within the record is given by KNOWN_ALIGN.
968 Update the variable alignment fields in RLI, and return the alignment
969 to give the FIELD. */
972 update_alignment_for_field (record_layout_info rli
, tree field
,
973 unsigned int known_align
)
975 /* The alignment required for FIELD. */
976 unsigned int desired_align
;
977 /* The type of this field. */
978 tree type
= TREE_TYPE (field
);
979 /* True if the field was explicitly aligned by the user. */
983 /* Do not attempt to align an ERROR_MARK node */
984 if (TREE_CODE (type
) == ERROR_MARK
)
987 /* Lay out the field so we know what alignment it needs. */
988 layout_decl (field
, known_align
);
989 desired_align
= DECL_ALIGN (field
);
990 user_align
= DECL_USER_ALIGN (field
);
992 is_bitfield
= (type
!= error_mark_node
993 && DECL_BIT_FIELD_TYPE (field
)
994 && ! integer_zerop (TYPE_SIZE (type
)));
996 /* Record must have at least as much alignment as any field.
997 Otherwise, the alignment of the field within the record is
999 if (targetm
.ms_bitfield_layout_p (rli
->t
))
1001 /* Here, the alignment of the underlying type of a bitfield can
1002 affect the alignment of a record; even a zero-sized field
1003 can do this. The alignment should be to the alignment of
1004 the type, except that for zero-size bitfields this only
1005 applies if there was an immediately prior, nonzero-size
1006 bitfield. (That's the way it is, experimentally.) */
1007 if ((!is_bitfield
&& !DECL_PACKED (field
))
1008 || ((DECL_SIZE (field
) == NULL_TREE
1009 || !integer_zerop (DECL_SIZE (field
)))
1010 ? !DECL_PACKED (field
)
1012 && DECL_BIT_FIELD_TYPE (rli
->prev_field
)
1013 && ! integer_zerop (DECL_SIZE (rli
->prev_field
)))))
1015 unsigned int type_align
= TYPE_ALIGN (type
);
1016 type_align
= MAX (type_align
, desired_align
);
1017 if (maximum_field_alignment
!= 0)
1018 type_align
= MIN (type_align
, maximum_field_alignment
);
1019 rli
->record_align
= MAX (rli
->record_align
, type_align
);
1020 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
1023 else if (is_bitfield
&& PCC_BITFIELD_TYPE_MATTERS
)
1025 /* Named bit-fields cause the entire structure to have the
1026 alignment implied by their type. Some targets also apply the same
1027 rules to unnamed bitfields. */
1028 if (DECL_NAME (field
) != 0
1029 || targetm
.align_anon_bitfield ())
1031 unsigned int type_align
= TYPE_ALIGN (type
);
1033 #ifdef ADJUST_FIELD_ALIGN
1034 if (! TYPE_USER_ALIGN (type
))
1035 type_align
= ADJUST_FIELD_ALIGN (field
, type
, type_align
);
1038 /* Targets might chose to handle unnamed and hence possibly
1039 zero-width bitfield. Those are not influenced by #pragmas
1040 or packed attributes. */
1041 if (integer_zerop (DECL_SIZE (field
)))
1043 if (initial_max_fld_align
)
1044 type_align
= MIN (type_align
,
1045 initial_max_fld_align
* BITS_PER_UNIT
);
1047 else if (maximum_field_alignment
!= 0)
1048 type_align
= MIN (type_align
, maximum_field_alignment
);
1049 else if (DECL_PACKED (field
))
1050 type_align
= MIN (type_align
, BITS_PER_UNIT
);
1052 /* The alignment of the record is increased to the maximum
1053 of the current alignment, the alignment indicated on the
1054 field (i.e., the alignment specified by an __aligned__
1055 attribute), and the alignment indicated by the type of
1057 rli
->record_align
= MAX (rli
->record_align
, desired_align
);
1058 rli
->record_align
= MAX (rli
->record_align
, type_align
);
1061 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
1062 user_align
|= TYPE_USER_ALIGN (type
);
1067 rli
->record_align
= MAX (rli
->record_align
, desired_align
);
1068 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
1071 TYPE_USER_ALIGN (rli
->t
) |= user_align
;
1073 return desired_align
;
1076 /* Issue a warning if the record alignment, RECORD_ALIGN, is less than
1077 the field alignment of FIELD or FIELD isn't aligned. */
1080 handle_warn_if_not_align (tree field
, unsigned int record_align
)
1082 tree type
= TREE_TYPE (field
);
1084 if (type
== error_mark_node
)
1087 unsigned int warn_if_not_align
= 0;
1091 if (warn_if_not_aligned
)
1093 warn_if_not_align
= DECL_WARN_IF_NOT_ALIGN (field
);
1094 if (!warn_if_not_align
)
1095 warn_if_not_align
= TYPE_WARN_IF_NOT_ALIGN (type
);
1096 if (warn_if_not_align
)
1097 opt_w
= OPT_Wif_not_aligned
;
1100 if (!warn_if_not_align
1101 && warn_packed_not_aligned
1102 && TYPE_USER_ALIGN (type
))
1104 warn_if_not_align
= TYPE_ALIGN (type
);
1105 opt_w
= OPT_Wpacked_not_aligned
;
1108 if (!warn_if_not_align
)
1111 tree context
= DECL_CONTEXT (field
);
1113 warn_if_not_align
/= BITS_PER_UNIT
;
1114 record_align
/= BITS_PER_UNIT
;
1115 if ((record_align
% warn_if_not_align
) != 0)
1116 warning (opt_w
, "alignment %u of %qT is less than %u",
1117 record_align
, context
, warn_if_not_align
);
1119 unsigned HOST_WIDE_INT off
1120 = (tree_to_uhwi (DECL_FIELD_OFFSET (field
))
1121 + tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field
)) / BITS_PER_UNIT
);
1122 if ((off
% warn_if_not_align
) != 0)
1123 warning (opt_w
, "%q+D offset %wu in %qT isn't aligned to %u",
1124 field
, off
, context
, warn_if_not_align
);
1127 /* Called from place_field to handle unions. */
1130 place_union_field (record_layout_info rli
, tree field
)
1132 update_alignment_for_field (rli
, field
, /*known_align=*/0);
1134 DECL_FIELD_OFFSET (field
) = size_zero_node
;
1135 DECL_FIELD_BIT_OFFSET (field
) = bitsize_zero_node
;
1136 SET_DECL_OFFSET_ALIGN (field
, BIGGEST_ALIGNMENT
);
1137 handle_warn_if_not_align (field
, rli
->record_align
);
1139 /* If this is an ERROR_MARK return *after* having set the
1140 field at the start of the union. This helps when parsing
1142 if (TREE_CODE (TREE_TYPE (field
)) == ERROR_MARK
)
1145 if (AGGREGATE_TYPE_P (TREE_TYPE (field
))
1146 && TYPE_TYPELESS_STORAGE (TREE_TYPE (field
)))
1147 TYPE_TYPELESS_STORAGE (rli
->t
) = 1;
1149 /* We assume the union's size will be a multiple of a byte so we don't
1150 bother with BITPOS. */
1151 if (TREE_CODE (rli
->t
) == UNION_TYPE
)
1152 rli
->offset
= size_binop (MAX_EXPR
, rli
->offset
, DECL_SIZE_UNIT (field
));
1153 else if (TREE_CODE (rli
->t
) == QUAL_UNION_TYPE
)
1154 rli
->offset
= fold_build3 (COND_EXPR
, sizetype
, DECL_QUALIFIER (field
),
1155 DECL_SIZE_UNIT (field
), rli
->offset
);
1158 /* A bitfield of SIZE with a required access alignment of ALIGN is allocated
1159 at BYTE_OFFSET / BIT_OFFSET. Return nonzero if the field would span more
1160 units of alignment than the underlying TYPE. */
1162 excess_unit_span (HOST_WIDE_INT byte_offset
, HOST_WIDE_INT bit_offset
,
1163 HOST_WIDE_INT size
, HOST_WIDE_INT align
, tree type
)
1165 /* Note that the calculation of OFFSET might overflow; we calculate it so
1166 that we still get the right result as long as ALIGN is a power of two. */
1167 unsigned HOST_WIDE_INT offset
= byte_offset
* BITS_PER_UNIT
+ bit_offset
;
1169 offset
= offset
% align
;
1170 return ((offset
+ size
+ align
- 1) / align
1171 > tree_to_uhwi (TYPE_SIZE (type
)) / align
);
1174 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
1175 is a FIELD_DECL to be added after those fields already present in
1176 T. (FIELD is not actually added to the TYPE_FIELDS list here;
1177 callers that desire that behavior must manually perform that step.) */
1180 place_field (record_layout_info rli
, tree field
)
1182 /* The alignment required for FIELD. */
1183 unsigned int desired_align
;
1184 /* The alignment FIELD would have if we just dropped it into the
1185 record as it presently stands. */
1186 unsigned int known_align
;
1187 unsigned int actual_align
;
1188 /* The type of this field. */
1189 tree type
= TREE_TYPE (field
);
1191 gcc_assert (TREE_CODE (field
) != ERROR_MARK
);
1193 /* If FIELD is static, then treat it like a separate variable, not
1194 really like a structure field. If it is a FUNCTION_DECL, it's a
1195 method. In both cases, all we do is lay out the decl, and we do
1196 it *after* the record is laid out. */
1199 vec_safe_push (rli
->pending_statics
, field
);
1203 /* Enumerators and enum types which are local to this class need not
1204 be laid out. Likewise for initialized constant fields. */
1205 else if (TREE_CODE (field
) != FIELD_DECL
)
1208 /* Unions are laid out very differently than records, so split
1209 that code off to another function. */
1210 else if (TREE_CODE (rli
->t
) != RECORD_TYPE
)
1212 place_union_field (rli
, field
);
1216 else if (TREE_CODE (type
) == ERROR_MARK
)
1218 /* Place this field at the current allocation position, so we
1219 maintain monotonicity. */
1220 DECL_FIELD_OFFSET (field
) = rli
->offset
;
1221 DECL_FIELD_BIT_OFFSET (field
) = rli
->bitpos
;
1222 SET_DECL_OFFSET_ALIGN (field
, rli
->offset_align
);
1223 handle_warn_if_not_align (field
, rli
->record_align
);
1227 if (AGGREGATE_TYPE_P (type
)
1228 && TYPE_TYPELESS_STORAGE (type
))
1229 TYPE_TYPELESS_STORAGE (rli
->t
) = 1;
1231 /* Work out the known alignment so far. Note that A & (-A) is the
1232 value of the least-significant bit in A that is one. */
1233 if (! integer_zerop (rli
->bitpos
))
1234 known_align
= least_bit_hwi (tree_to_uhwi (rli
->bitpos
));
1235 else if (integer_zerop (rli
->offset
))
1237 else if (tree_fits_uhwi_p (rli
->offset
))
1238 known_align
= (BITS_PER_UNIT
1239 * least_bit_hwi (tree_to_uhwi (rli
->offset
)));
1241 known_align
= rli
->offset_align
;
1243 desired_align
= update_alignment_for_field (rli
, field
, known_align
);
1244 if (known_align
== 0)
1245 known_align
= MAX (BIGGEST_ALIGNMENT
, rli
->record_align
);
1247 if (warn_packed
&& DECL_PACKED (field
))
1249 if (known_align
>= TYPE_ALIGN (type
))
1251 if (TYPE_ALIGN (type
) > desired_align
)
1253 if (STRICT_ALIGNMENT
)
1254 warning (OPT_Wattributes
, "packed attribute causes "
1255 "inefficient alignment for %q+D", field
);
1256 /* Don't warn if DECL_PACKED was set by the type. */
1257 else if (!TYPE_PACKED (rli
->t
))
1258 warning (OPT_Wattributes
, "packed attribute is "
1259 "unnecessary for %q+D", field
);
1263 rli
->packed_maybe_necessary
= 1;
1266 /* Does this field automatically have alignment it needs by virtue
1267 of the fields that precede it and the record's own alignment? */
1268 if (known_align
< desired_align
)
1270 /* No, we need to skip space before this field.
1271 Bump the cumulative size to multiple of field alignment. */
1273 if (!targetm
.ms_bitfield_layout_p (rli
->t
)
1274 && DECL_SOURCE_LOCATION (field
) != BUILTINS_LOCATION
)
1275 warning (OPT_Wpadded
, "padding struct to align %q+D", field
);
1277 /* If the alignment is still within offset_align, just align
1278 the bit position. */
1279 if (desired_align
< rli
->offset_align
)
1280 rli
->bitpos
= round_up (rli
->bitpos
, desired_align
);
1283 /* First adjust OFFSET by the partial bits, then align. */
1285 = size_binop (PLUS_EXPR
, rli
->offset
,
1286 fold_convert (sizetype
,
1287 size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
1288 bitsize_unit_node
)));
1289 rli
->bitpos
= bitsize_zero_node
;
1291 rli
->offset
= round_up (rli
->offset
, desired_align
/ BITS_PER_UNIT
);
1294 if (! TREE_CONSTANT (rli
->offset
))
1295 rli
->offset_align
= desired_align
;
1296 if (targetm
.ms_bitfield_layout_p (rli
->t
))
1297 rli
->prev_field
= NULL
;
1300 /* Handle compatibility with PCC. Note that if the record has any
1301 variable-sized fields, we need not worry about compatibility. */
1302 if (PCC_BITFIELD_TYPE_MATTERS
1303 && ! targetm
.ms_bitfield_layout_p (rli
->t
)
1304 && TREE_CODE (field
) == FIELD_DECL
1305 && type
!= error_mark_node
1306 && DECL_BIT_FIELD (field
)
1307 && (! DECL_PACKED (field
)
1308 /* Enter for these packed fields only to issue a warning. */
1309 || TYPE_ALIGN (type
) <= BITS_PER_UNIT
)
1310 && maximum_field_alignment
== 0
1311 && ! integer_zerop (DECL_SIZE (field
))
1312 && tree_fits_uhwi_p (DECL_SIZE (field
))
1313 && tree_fits_uhwi_p (rli
->offset
)
1314 && tree_fits_uhwi_p (TYPE_SIZE (type
)))
1316 unsigned int type_align
= TYPE_ALIGN (type
);
1317 tree dsize
= DECL_SIZE (field
);
1318 HOST_WIDE_INT field_size
= tree_to_uhwi (dsize
);
1319 HOST_WIDE_INT offset
= tree_to_uhwi (rli
->offset
);
1320 HOST_WIDE_INT bit_offset
= tree_to_shwi (rli
->bitpos
);
1322 #ifdef ADJUST_FIELD_ALIGN
1323 if (! TYPE_USER_ALIGN (type
))
1324 type_align
= ADJUST_FIELD_ALIGN (field
, type
, type_align
);
1327 /* A bit field may not span more units of alignment of its type
1328 than its type itself. Advance to next boundary if necessary. */
1329 if (excess_unit_span (offset
, bit_offset
, field_size
, type_align
, type
))
1331 if (DECL_PACKED (field
))
1333 if (warn_packed_bitfield_compat
== 1)
1336 "offset of packed bit-field %qD has changed in GCC 4.4",
1340 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1343 if (! DECL_PACKED (field
))
1344 TYPE_USER_ALIGN (rli
->t
) |= TYPE_USER_ALIGN (type
);
1346 SET_TYPE_WARN_IF_NOT_ALIGN (rli
->t
,
1347 TYPE_WARN_IF_NOT_ALIGN (type
));
1350 #ifdef BITFIELD_NBYTES_LIMITED
1351 if (BITFIELD_NBYTES_LIMITED
1352 && ! targetm
.ms_bitfield_layout_p (rli
->t
)
1353 && TREE_CODE (field
) == FIELD_DECL
1354 && type
!= error_mark_node
1355 && DECL_BIT_FIELD_TYPE (field
)
1356 && ! DECL_PACKED (field
)
1357 && ! integer_zerop (DECL_SIZE (field
))
1358 && tree_fits_uhwi_p (DECL_SIZE (field
))
1359 && tree_fits_uhwi_p (rli
->offset
)
1360 && tree_fits_uhwi_p (TYPE_SIZE (type
)))
1362 unsigned int type_align
= TYPE_ALIGN (type
);
1363 tree dsize
= DECL_SIZE (field
);
1364 HOST_WIDE_INT field_size
= tree_to_uhwi (dsize
);
1365 HOST_WIDE_INT offset
= tree_to_uhwi (rli
->offset
);
1366 HOST_WIDE_INT bit_offset
= tree_to_shwi (rli
->bitpos
);
1368 #ifdef ADJUST_FIELD_ALIGN
1369 if (! TYPE_USER_ALIGN (type
))
1370 type_align
= ADJUST_FIELD_ALIGN (field
, type
, type_align
);
1373 if (maximum_field_alignment
!= 0)
1374 type_align
= MIN (type_align
, maximum_field_alignment
);
1375 /* ??? This test is opposite the test in the containing if
1376 statement, so this code is unreachable currently. */
1377 else if (DECL_PACKED (field
))
1378 type_align
= MIN (type_align
, BITS_PER_UNIT
);
1380 /* A bit field may not span the unit of alignment of its type.
1381 Advance to next boundary if necessary. */
1382 if (excess_unit_span (offset
, bit_offset
, field_size
, type_align
, type
))
1383 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1385 TYPE_USER_ALIGN (rli
->t
) |= TYPE_USER_ALIGN (type
);
1386 SET_TYPE_WARN_IF_NOT_ALIGN (rli
->t
,
1387 TYPE_WARN_IF_NOT_ALIGN (type
));
1391 /* See the docs for TARGET_MS_BITFIELD_LAYOUT_P for details.
1393 When a bit field is inserted into a packed record, the whole
1394 size of the underlying type is used by one or more same-size
1395 adjacent bitfields. (That is, if its long:3, 32 bits is
1396 used in the record, and any additional adjacent long bitfields are
1397 packed into the same chunk of 32 bits. However, if the size
1398 changes, a new field of that size is allocated.) In an unpacked
1399 record, this is the same as using alignment, but not equivalent
1402 Note: for compatibility, we use the type size, not the type alignment
1403 to determine alignment, since that matches the documentation */
1405 if (targetm
.ms_bitfield_layout_p (rli
->t
))
1407 tree prev_saved
= rli
->prev_field
;
1408 tree prev_type
= prev_saved
? DECL_BIT_FIELD_TYPE (prev_saved
) : NULL
;
1410 /* This is a bitfield if it exists. */
1411 if (rli
->prev_field
)
1413 /* If both are bitfields, nonzero, and the same size, this is
1414 the middle of a run. Zero declared size fields are special
1415 and handled as "end of run". (Note: it's nonzero declared
1416 size, but equal type sizes!) (Since we know that both
1417 the current and previous fields are bitfields by the
1418 time we check it, DECL_SIZE must be present for both.) */
1419 if (DECL_BIT_FIELD_TYPE (field
)
1420 && !integer_zerop (DECL_SIZE (field
))
1421 && !integer_zerop (DECL_SIZE (rli
->prev_field
))
1422 && tree_fits_shwi_p (DECL_SIZE (rli
->prev_field
))
1423 && tree_fits_uhwi_p (TYPE_SIZE (type
))
1424 && simple_cst_equal (TYPE_SIZE (type
), TYPE_SIZE (prev_type
)))
1426 /* We're in the middle of a run of equal type size fields; make
1427 sure we realign if we run out of bits. (Not decl size,
1429 HOST_WIDE_INT bitsize
= tree_to_uhwi (DECL_SIZE (field
));
1431 if (rli
->remaining_in_alignment
< bitsize
)
1433 HOST_WIDE_INT typesize
= tree_to_uhwi (TYPE_SIZE (type
));
1435 /* out of bits; bump up to next 'word'. */
1437 = size_binop (PLUS_EXPR
, rli
->bitpos
,
1438 bitsize_int (rli
->remaining_in_alignment
));
1439 rli
->prev_field
= field
;
1440 if (typesize
< bitsize
)
1441 rli
->remaining_in_alignment
= 0;
1443 rli
->remaining_in_alignment
= typesize
- bitsize
;
1446 rli
->remaining_in_alignment
-= bitsize
;
1450 /* End of a run: if leaving a run of bitfields of the same type
1451 size, we have to "use up" the rest of the bits of the type
1454 Compute the new position as the sum of the size for the prior
1455 type and where we first started working on that type.
1456 Note: since the beginning of the field was aligned then
1457 of course the end will be too. No round needed. */
1459 if (!integer_zerop (DECL_SIZE (rli
->prev_field
)))
1462 = size_binop (PLUS_EXPR
, rli
->bitpos
,
1463 bitsize_int (rli
->remaining_in_alignment
));
1466 /* We "use up" size zero fields; the code below should behave
1467 as if the prior field was not a bitfield. */
1470 /* Cause a new bitfield to be captured, either this time (if
1471 currently a bitfield) or next time we see one. */
1472 if (!DECL_BIT_FIELD_TYPE (field
)
1473 || integer_zerop (DECL_SIZE (field
)))
1474 rli
->prev_field
= NULL
;
1477 normalize_rli (rli
);
1480 /* If we're starting a new run of same type size bitfields
1481 (or a run of non-bitfields), set up the "first of the run"
1484 That is, if the current field is not a bitfield, or if there
1485 was a prior bitfield the type sizes differ, or if there wasn't
1486 a prior bitfield the size of the current field is nonzero.
1488 Note: we must be sure to test ONLY the type size if there was
1489 a prior bitfield and ONLY for the current field being zero if
1492 if (!DECL_BIT_FIELD_TYPE (field
)
1493 || (prev_saved
!= NULL
1494 ? !simple_cst_equal (TYPE_SIZE (type
), TYPE_SIZE (prev_type
))
1495 : !integer_zerop (DECL_SIZE (field
)) ))
1497 /* Never smaller than a byte for compatibility. */
1498 unsigned int type_align
= BITS_PER_UNIT
;
1500 /* (When not a bitfield), we could be seeing a flex array (with
1501 no DECL_SIZE). Since we won't be using remaining_in_alignment
1502 until we see a bitfield (and come by here again) we just skip
1504 if (DECL_SIZE (field
) != NULL
1505 && tree_fits_uhwi_p (TYPE_SIZE (TREE_TYPE (field
)))
1506 && tree_fits_uhwi_p (DECL_SIZE (field
)))
1508 unsigned HOST_WIDE_INT bitsize
1509 = tree_to_uhwi (DECL_SIZE (field
));
1510 unsigned HOST_WIDE_INT typesize
1511 = tree_to_uhwi (TYPE_SIZE (TREE_TYPE (field
)));
1513 if (typesize
< bitsize
)
1514 rli
->remaining_in_alignment
= 0;
1516 rli
->remaining_in_alignment
= typesize
- bitsize
;
1519 /* Now align (conventionally) for the new type. */
1520 type_align
= TYPE_ALIGN (TREE_TYPE (field
));
1522 if (maximum_field_alignment
!= 0)
1523 type_align
= MIN (type_align
, maximum_field_alignment
);
1525 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1527 /* If we really aligned, don't allow subsequent bitfields
1529 rli
->prev_field
= NULL
;
1533 /* Offset so far becomes the position of this field after normalizing. */
1534 normalize_rli (rli
);
1535 DECL_FIELD_OFFSET (field
) = rli
->offset
;
1536 DECL_FIELD_BIT_OFFSET (field
) = rli
->bitpos
;
1537 SET_DECL_OFFSET_ALIGN (field
, rli
->offset_align
);
1538 handle_warn_if_not_align (field
, rli
->record_align
);
1540 /* Evaluate nonconstant offsets only once, either now or as soon as safe. */
1541 if (TREE_CODE (DECL_FIELD_OFFSET (field
)) != INTEGER_CST
)
1542 DECL_FIELD_OFFSET (field
) = variable_size (DECL_FIELD_OFFSET (field
));
1544 /* If this field ended up more aligned than we thought it would be (we
1545 approximate this by seeing if its position changed), lay out the field
1546 again; perhaps we can use an integral mode for it now. */
1547 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field
)))
1548 actual_align
= least_bit_hwi (tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field
)));
1549 else if (integer_zerop (DECL_FIELD_OFFSET (field
)))
1550 actual_align
= MAX (BIGGEST_ALIGNMENT
, rli
->record_align
);
1551 else if (tree_fits_uhwi_p (DECL_FIELD_OFFSET (field
)))
1552 actual_align
= (BITS_PER_UNIT
1553 * least_bit_hwi (tree_to_uhwi (DECL_FIELD_OFFSET (field
))));
1555 actual_align
= DECL_OFFSET_ALIGN (field
);
1556 /* ACTUAL_ALIGN is still the actual alignment *within the record* .
1557 store / extract bit field operations will check the alignment of the
1558 record against the mode of bit fields. */
1560 if (known_align
!= actual_align
)
1561 layout_decl (field
, actual_align
);
1563 if (rli
->prev_field
== NULL
&& DECL_BIT_FIELD_TYPE (field
))
1564 rli
->prev_field
= field
;
1566 /* Now add size of this field to the size of the record. If the size is
1567 not constant, treat the field as being a multiple of bytes and just
1568 adjust the offset, resetting the bit position. Otherwise, apportion the
1569 size amongst the bit position and offset. First handle the case of an
1570 unspecified size, which can happen when we have an invalid nested struct
1571 definition, such as struct j { struct j { int i; } }. The error message
1572 is printed in finish_struct. */
1573 if (DECL_SIZE (field
) == 0)
1575 else if (TREE_CODE (DECL_SIZE (field
)) != INTEGER_CST
1576 || TREE_OVERFLOW (DECL_SIZE (field
)))
1579 = size_binop (PLUS_EXPR
, rli
->offset
,
1580 fold_convert (sizetype
,
1581 size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
1582 bitsize_unit_node
)));
1584 = size_binop (PLUS_EXPR
, rli
->offset
, DECL_SIZE_UNIT (field
));
1585 rli
->bitpos
= bitsize_zero_node
;
1586 rli
->offset_align
= MIN (rli
->offset_align
, desired_align
);
1588 else if (targetm
.ms_bitfield_layout_p (rli
->t
))
1590 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
, DECL_SIZE (field
));
1592 /* If we ended a bitfield before the full length of the type then
1593 pad the struct out to the full length of the last type. */
1594 if ((DECL_CHAIN (field
) == NULL
1595 || TREE_CODE (DECL_CHAIN (field
)) != FIELD_DECL
)
1596 && DECL_BIT_FIELD_TYPE (field
)
1597 && !integer_zerop (DECL_SIZE (field
)))
1598 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
,
1599 bitsize_int (rli
->remaining_in_alignment
));
1601 normalize_rli (rli
);
1605 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
, DECL_SIZE (field
));
1606 normalize_rli (rli
);
1610 /* Assuming that all the fields have been laid out, this function uses
1611 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
1612 indicated by RLI. */
1615 finalize_record_size (record_layout_info rli
)
1617 tree unpadded_size
, unpadded_size_unit
;
1619 /* Now we want just byte and bit offsets, so set the offset alignment
1620 to be a byte and then normalize. */
1621 rli
->offset_align
= BITS_PER_UNIT
;
1622 normalize_rli (rli
);
1624 /* Determine the desired alignment. */
1625 #ifdef ROUND_TYPE_ALIGN
1626 SET_TYPE_ALIGN (rli
->t
, ROUND_TYPE_ALIGN (rli
->t
, TYPE_ALIGN (rli
->t
),
1627 rli
->record_align
));
1629 SET_TYPE_ALIGN (rli
->t
, MAX (TYPE_ALIGN (rli
->t
), rli
->record_align
));
1632 /* Compute the size so far. Be sure to allow for extra bits in the
1633 size in bytes. We have guaranteed above that it will be no more
1634 than a single byte. */
1635 unpadded_size
= rli_size_so_far (rli
);
1636 unpadded_size_unit
= rli_size_unit_so_far (rli
);
1637 if (! integer_zerop (rli
->bitpos
))
1639 = size_binop (PLUS_EXPR
, unpadded_size_unit
, size_one_node
);
1641 /* Round the size up to be a multiple of the required alignment. */
1642 TYPE_SIZE (rli
->t
) = round_up (unpadded_size
, TYPE_ALIGN (rli
->t
));
1643 TYPE_SIZE_UNIT (rli
->t
)
1644 = round_up (unpadded_size_unit
, TYPE_ALIGN_UNIT (rli
->t
));
1646 if (TREE_CONSTANT (unpadded_size
)
1647 && simple_cst_equal (unpadded_size
, TYPE_SIZE (rli
->t
)) == 0
1648 && input_location
!= BUILTINS_LOCATION
)
1649 warning (OPT_Wpadded
, "padding struct size to alignment boundary");
1651 if (warn_packed
&& TREE_CODE (rli
->t
) == RECORD_TYPE
1652 && TYPE_PACKED (rli
->t
) && ! rli
->packed_maybe_necessary
1653 && TREE_CONSTANT (unpadded_size
))
1657 #ifdef ROUND_TYPE_ALIGN
1659 = ROUND_TYPE_ALIGN (rli
->t
, TYPE_ALIGN (rli
->t
), rli
->unpacked_align
);
1661 rli
->unpacked_align
= MAX (TYPE_ALIGN (rli
->t
), rli
->unpacked_align
);
1664 unpacked_size
= round_up (TYPE_SIZE (rli
->t
), rli
->unpacked_align
);
1665 if (simple_cst_equal (unpacked_size
, TYPE_SIZE (rli
->t
)))
1667 if (TYPE_NAME (rli
->t
))
1671 if (TREE_CODE (TYPE_NAME (rli
->t
)) == IDENTIFIER_NODE
)
1672 name
= TYPE_NAME (rli
->t
);
1674 name
= DECL_NAME (TYPE_NAME (rli
->t
));
1676 if (STRICT_ALIGNMENT
)
1677 warning (OPT_Wpacked
, "packed attribute causes inefficient "
1678 "alignment for %qE", name
);
1680 warning (OPT_Wpacked
,
1681 "packed attribute is unnecessary for %qE", name
);
1685 if (STRICT_ALIGNMENT
)
1686 warning (OPT_Wpacked
,
1687 "packed attribute causes inefficient alignment");
1689 warning (OPT_Wpacked
, "packed attribute is unnecessary");
1695 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
1698 compute_record_mode (tree type
)
1701 machine_mode mode
= VOIDmode
;
1703 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
1704 However, if possible, we use a mode that fits in a register
1705 instead, in order to allow for better optimization down the
1707 SET_TYPE_MODE (type
, BLKmode
);
1709 if (! tree_fits_uhwi_p (TYPE_SIZE (type
)))
1712 /* A record which has any BLKmode members must itself be
1713 BLKmode; it can't go in a register. Unless the member is
1714 BLKmode only because it isn't aligned. */
1715 for (field
= TYPE_FIELDS (type
); field
; field
= DECL_CHAIN (field
))
1717 if (TREE_CODE (field
) != FIELD_DECL
)
1720 if (TREE_CODE (TREE_TYPE (field
)) == ERROR_MARK
1721 || (TYPE_MODE (TREE_TYPE (field
)) == BLKmode
1722 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field
))
1723 && !(TYPE_SIZE (TREE_TYPE (field
)) != 0
1724 && integer_zerop (TYPE_SIZE (TREE_TYPE (field
)))))
1725 || ! tree_fits_uhwi_p (bit_position (field
))
1726 || DECL_SIZE (field
) == 0
1727 || ! tree_fits_uhwi_p (DECL_SIZE (field
)))
1730 /* If this field is the whole struct, remember its mode so
1731 that, say, we can put a double in a class into a DF
1732 register instead of forcing it to live in the stack. */
1733 if (simple_cst_equal (TYPE_SIZE (type
), DECL_SIZE (field
)))
1734 mode
= DECL_MODE (field
);
1736 /* With some targets, it is sub-optimal to access an aligned
1737 BLKmode structure as a scalar. */
1738 if (targetm
.member_type_forces_blk (field
, mode
))
1742 /* If we only have one real field; use its mode if that mode's size
1743 matches the type's size. This only applies to RECORD_TYPE. This
1744 does not apply to unions. */
1745 if (TREE_CODE (type
) == RECORD_TYPE
&& mode
!= VOIDmode
1746 && tree_fits_uhwi_p (TYPE_SIZE (type
))
1747 && GET_MODE_BITSIZE (mode
) == tree_to_uhwi (TYPE_SIZE (type
)))
1748 SET_TYPE_MODE (type
, mode
);
1750 SET_TYPE_MODE (type
, mode_for_size_tree (TYPE_SIZE (type
), MODE_INT
, 1));
1752 /* If structure's known alignment is less than what the scalar
1753 mode would need, and it matters, then stick with BLKmode. */
1754 if (TYPE_MODE (type
) != BLKmode
1756 && ! (TYPE_ALIGN (type
) >= BIGGEST_ALIGNMENT
1757 || TYPE_ALIGN (type
) >= GET_MODE_ALIGNMENT (TYPE_MODE (type
))))
1759 /* If this is the only reason this type is BLKmode, then
1760 don't force containing types to be BLKmode. */
1761 TYPE_NO_FORCE_BLK (type
) = 1;
1762 SET_TYPE_MODE (type
, BLKmode
);
1766 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1770 finalize_type_size (tree type
)
1772 /* Normally, use the alignment corresponding to the mode chosen.
1773 However, where strict alignment is not required, avoid
1774 over-aligning structures, since most compilers do not do this
1776 if (TYPE_MODE (type
) != BLKmode
1777 && TYPE_MODE (type
) != VOIDmode
1778 && (STRICT_ALIGNMENT
|| !AGGREGATE_TYPE_P (type
)))
1780 unsigned mode_align
= GET_MODE_ALIGNMENT (TYPE_MODE (type
));
1782 /* Don't override a larger alignment requirement coming from a user
1783 alignment of one of the fields. */
1784 if (mode_align
>= TYPE_ALIGN (type
))
1786 SET_TYPE_ALIGN (type
, mode_align
);
1787 TYPE_USER_ALIGN (type
) = 0;
1791 /* Do machine-dependent extra alignment. */
1792 #ifdef ROUND_TYPE_ALIGN
1793 SET_TYPE_ALIGN (type
,
1794 ROUND_TYPE_ALIGN (type
, TYPE_ALIGN (type
), BITS_PER_UNIT
));
1797 /* If we failed to find a simple way to calculate the unit size
1798 of the type, find it by division. */
1799 if (TYPE_SIZE_UNIT (type
) == 0 && TYPE_SIZE (type
) != 0)
1800 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1801 result will fit in sizetype. We will get more efficient code using
1802 sizetype, so we force a conversion. */
1803 TYPE_SIZE_UNIT (type
)
1804 = fold_convert (sizetype
,
1805 size_binop (FLOOR_DIV_EXPR
, TYPE_SIZE (type
),
1806 bitsize_unit_node
));
1808 if (TYPE_SIZE (type
) != 0)
1810 TYPE_SIZE (type
) = round_up (TYPE_SIZE (type
), TYPE_ALIGN (type
));
1811 TYPE_SIZE_UNIT (type
)
1812 = round_up (TYPE_SIZE_UNIT (type
), TYPE_ALIGN_UNIT (type
));
1815 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1816 if (TYPE_SIZE (type
) != 0 && TREE_CODE (TYPE_SIZE (type
)) != INTEGER_CST
)
1817 TYPE_SIZE (type
) = variable_size (TYPE_SIZE (type
));
1818 if (TYPE_SIZE_UNIT (type
) != 0
1819 && TREE_CODE (TYPE_SIZE_UNIT (type
)) != INTEGER_CST
)
1820 TYPE_SIZE_UNIT (type
) = variable_size (TYPE_SIZE_UNIT (type
));
1822 /* Also layout any other variants of the type. */
1823 if (TYPE_NEXT_VARIANT (type
)
1824 || type
!= TYPE_MAIN_VARIANT (type
))
1827 /* Record layout info of this variant. */
1828 tree size
= TYPE_SIZE (type
);
1829 tree size_unit
= TYPE_SIZE_UNIT (type
);
1830 unsigned int align
= TYPE_ALIGN (type
);
1831 unsigned int precision
= TYPE_PRECISION (type
);
1832 unsigned int user_align
= TYPE_USER_ALIGN (type
);
1833 machine_mode mode
= TYPE_MODE (type
);
1835 /* Copy it into all variants. */
1836 for (variant
= TYPE_MAIN_VARIANT (type
);
1838 variant
= TYPE_NEXT_VARIANT (variant
))
1840 TYPE_SIZE (variant
) = size
;
1841 TYPE_SIZE_UNIT (variant
) = size_unit
;
1842 unsigned valign
= align
;
1843 if (TYPE_USER_ALIGN (variant
))
1844 valign
= MAX (valign
, TYPE_ALIGN (variant
));
1846 TYPE_USER_ALIGN (variant
) = user_align
;
1847 SET_TYPE_ALIGN (variant
, valign
);
1848 TYPE_PRECISION (variant
) = precision
;
1849 SET_TYPE_MODE (variant
, mode
);
1854 /* Return a new underlying object for a bitfield started with FIELD. */
1857 start_bitfield_representative (tree field
)
1859 tree repr
= make_node (FIELD_DECL
);
1860 DECL_FIELD_OFFSET (repr
) = DECL_FIELD_OFFSET (field
);
1861 /* Force the representative to begin at a BITS_PER_UNIT aligned
1862 boundary - C++ may use tail-padding of a base object to
1863 continue packing bits so the bitfield region does not start
1864 at bit zero (see g++.dg/abi/bitfield5.C for example).
1865 Unallocated bits may happen for other reasons as well,
1866 for example Ada which allows explicit bit-granular structure layout. */
1867 DECL_FIELD_BIT_OFFSET (repr
)
1868 = size_binop (BIT_AND_EXPR
,
1869 DECL_FIELD_BIT_OFFSET (field
),
1870 bitsize_int (~(BITS_PER_UNIT
- 1)));
1871 SET_DECL_OFFSET_ALIGN (repr
, DECL_OFFSET_ALIGN (field
));
1872 DECL_SIZE (repr
) = DECL_SIZE (field
);
1873 DECL_SIZE_UNIT (repr
) = DECL_SIZE_UNIT (field
);
1874 DECL_PACKED (repr
) = DECL_PACKED (field
);
1875 DECL_CONTEXT (repr
) = DECL_CONTEXT (field
);
1876 /* There are no indirect accesses to this field. If we introduce
1877 some then they have to use the record alias set. This makes
1878 sure to properly conflict with [indirect] accesses to addressable
1879 fields of the bitfield group. */
1880 DECL_NONADDRESSABLE_P (repr
) = 1;
1884 /* Finish up a bitfield group that was started by creating the underlying
1885 object REPR with the last field in the bitfield group FIELD. */
1888 finish_bitfield_representative (tree repr
, tree field
)
1890 unsigned HOST_WIDE_INT bitsize
, maxbitsize
;
1894 size
= size_diffop (DECL_FIELD_OFFSET (field
),
1895 DECL_FIELD_OFFSET (repr
));
1896 while (TREE_CODE (size
) == COMPOUND_EXPR
)
1897 size
= TREE_OPERAND (size
, 1);
1898 gcc_assert (tree_fits_uhwi_p (size
));
1899 bitsize
= (tree_to_uhwi (size
) * BITS_PER_UNIT
1900 + tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field
))
1901 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr
))
1902 + tree_to_uhwi (DECL_SIZE (field
)));
1904 /* Round up bitsize to multiples of BITS_PER_UNIT. */
1905 bitsize
= (bitsize
+ BITS_PER_UNIT
- 1) & ~(BITS_PER_UNIT
- 1);
1907 /* Now nothing tells us how to pad out bitsize ... */
1908 nextf
= DECL_CHAIN (field
);
1909 while (nextf
&& TREE_CODE (nextf
) != FIELD_DECL
)
1910 nextf
= DECL_CHAIN (nextf
);
1914 /* If there was an error, the field may be not laid out
1915 correctly. Don't bother to do anything. */
1916 if (TREE_TYPE (nextf
) == error_mark_node
)
1918 maxsize
= size_diffop (DECL_FIELD_OFFSET (nextf
),
1919 DECL_FIELD_OFFSET (repr
));
1920 if (tree_fits_uhwi_p (maxsize
))
1922 maxbitsize
= (tree_to_uhwi (maxsize
) * BITS_PER_UNIT
1923 + tree_to_uhwi (DECL_FIELD_BIT_OFFSET (nextf
))
1924 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr
)));
1925 /* If the group ends within a bitfield nextf does not need to be
1926 aligned to BITS_PER_UNIT. Thus round up. */
1927 maxbitsize
= (maxbitsize
+ BITS_PER_UNIT
- 1) & ~(BITS_PER_UNIT
- 1);
1930 maxbitsize
= bitsize
;
1934 /* Note that if the C++ FE sets up tail-padding to be re-used it
1935 creates a as-base variant of the type with TYPE_SIZE adjusted
1936 accordingly. So it is safe to include tail-padding here. */
1937 tree aggsize
= lang_hooks
.types
.unit_size_without_reusable_padding
1938 (DECL_CONTEXT (field
));
1939 tree maxsize
= size_diffop (aggsize
, DECL_FIELD_OFFSET (repr
));
1940 /* We cannot generally rely on maxsize to fold to an integer constant,
1941 so use bitsize as fallback for this case. */
1942 if (tree_fits_uhwi_p (maxsize
))
1943 maxbitsize
= (tree_to_uhwi (maxsize
) * BITS_PER_UNIT
1944 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr
)));
1946 maxbitsize
= bitsize
;
1949 /* Only if we don't artificially break up the representative in
1950 the middle of a large bitfield with different possibly
1951 overlapping representatives. And all representatives start
1953 gcc_assert (maxbitsize
% BITS_PER_UNIT
== 0);
1955 /* Find the smallest nice mode to use. */
1956 FOR_EACH_MODE_IN_CLASS (mode
, MODE_INT
)
1957 if (GET_MODE_BITSIZE (mode
) >= bitsize
)
1959 if (mode
!= VOIDmode
1960 && (GET_MODE_BITSIZE (mode
) > maxbitsize
1961 || GET_MODE_BITSIZE (mode
) > MAX_FIXED_MODE_SIZE
))
1964 if (mode
== VOIDmode
)
1966 /* We really want a BLKmode representative only as a last resort,
1967 considering the member b in
1968 struct { int a : 7; int b : 17; int c; } __attribute__((packed));
1969 Otherwise we simply want to split the representative up
1970 allowing for overlaps within the bitfield region as required for
1971 struct { int a : 7; int b : 7;
1972 int c : 10; int d; } __attribute__((packed));
1973 [0, 15] HImode for a and b, [8, 23] HImode for c. */
1974 DECL_SIZE (repr
) = bitsize_int (bitsize
);
1975 DECL_SIZE_UNIT (repr
) = size_int (bitsize
/ BITS_PER_UNIT
);
1976 SET_DECL_MODE (repr
, BLKmode
);
1977 TREE_TYPE (repr
) = build_array_type_nelts (unsigned_char_type_node
,
1978 bitsize
/ BITS_PER_UNIT
);
1982 unsigned HOST_WIDE_INT modesize
= GET_MODE_BITSIZE (mode
);
1983 DECL_SIZE (repr
) = bitsize_int (modesize
);
1984 DECL_SIZE_UNIT (repr
) = size_int (modesize
/ BITS_PER_UNIT
);
1985 SET_DECL_MODE (repr
, mode
);
1986 TREE_TYPE (repr
) = lang_hooks
.types
.type_for_mode (mode
, 1);
1989 /* Remember whether the bitfield group is at the end of the
1990 structure or not. */
1991 DECL_CHAIN (repr
) = nextf
;
1994 /* Compute and set FIELD_DECLs for the underlying objects we should
1995 use for bitfield access for the structure T. */
1998 finish_bitfield_layout (tree t
)
2001 tree repr
= NULL_TREE
;
2003 /* Unions would be special, for the ease of type-punning optimizations
2004 we could use the underlying type as hint for the representative
2005 if the bitfield would fit and the representative would not exceed
2006 the union in size. */
2007 if (TREE_CODE (t
) != RECORD_TYPE
)
2010 for (prev
= NULL_TREE
, field
= TYPE_FIELDS (t
);
2011 field
; field
= DECL_CHAIN (field
))
2013 if (TREE_CODE (field
) != FIELD_DECL
)
2016 /* In the C++ memory model, consecutive bit fields in a structure are
2017 considered one memory location and updating a memory location
2018 may not store into adjacent memory locations. */
2020 && DECL_BIT_FIELD_TYPE (field
))
2022 /* Start new representative. */
2023 repr
= start_bitfield_representative (field
);
2026 && ! DECL_BIT_FIELD_TYPE (field
))
2028 /* Finish off new representative. */
2029 finish_bitfield_representative (repr
, prev
);
2032 else if (DECL_BIT_FIELD_TYPE (field
))
2034 gcc_assert (repr
!= NULL_TREE
);
2036 /* Zero-size bitfields finish off a representative and
2037 do not have a representative themselves. This is
2038 required by the C++ memory model. */
2039 if (integer_zerop (DECL_SIZE (field
)))
2041 finish_bitfield_representative (repr
, prev
);
2045 /* We assume that either DECL_FIELD_OFFSET of the representative
2046 and each bitfield member is a constant or they are equal.
2047 This is because we need to be able to compute the bit-offset
2048 of each field relative to the representative in get_bit_range
2049 during RTL expansion.
2050 If these constraints are not met, simply force a new
2051 representative to be generated. That will at most
2052 generate worse code but still maintain correctness with
2053 respect to the C++ memory model. */
2054 else if (!((tree_fits_uhwi_p (DECL_FIELD_OFFSET (repr
))
2055 && tree_fits_uhwi_p (DECL_FIELD_OFFSET (field
)))
2056 || operand_equal_p (DECL_FIELD_OFFSET (repr
),
2057 DECL_FIELD_OFFSET (field
), 0)))
2059 finish_bitfield_representative (repr
, prev
);
2060 repr
= start_bitfield_representative (field
);
2067 DECL_BIT_FIELD_REPRESENTATIVE (field
) = repr
;
2073 finish_bitfield_representative (repr
, prev
);
2076 /* Do all of the work required to layout the type indicated by RLI,
2077 once the fields have been laid out. This function will call `free'
2078 for RLI, unless FREE_P is false. Passing a value other than false
2079 for FREE_P is bad practice; this option only exists to support the
2083 finish_record_layout (record_layout_info rli
, int free_p
)
2087 /* Compute the final size. */
2088 finalize_record_size (rli
);
2090 /* Compute the TYPE_MODE for the record. */
2091 compute_record_mode (rli
->t
);
2093 /* Perform any last tweaks to the TYPE_SIZE, etc. */
2094 finalize_type_size (rli
->t
);
2096 /* Compute bitfield representatives. */
2097 finish_bitfield_layout (rli
->t
);
2099 /* Propagate TYPE_PACKED and TYPE_REVERSE_STORAGE_ORDER to variants.
2100 With C++ templates, it is too early to do this when the attribute
2102 for (variant
= TYPE_NEXT_VARIANT (rli
->t
); variant
;
2103 variant
= TYPE_NEXT_VARIANT (variant
))
2105 TYPE_PACKED (variant
) = TYPE_PACKED (rli
->t
);
2106 TYPE_REVERSE_STORAGE_ORDER (variant
)
2107 = TYPE_REVERSE_STORAGE_ORDER (rli
->t
);
2110 /* Lay out any static members. This is done now because their type
2111 may use the record's type. */
2112 while (!vec_safe_is_empty (rli
->pending_statics
))
2113 layout_decl (rli
->pending_statics
->pop (), 0);
2118 vec_free (rli
->pending_statics
);
2124 /* Finish processing a builtin RECORD_TYPE type TYPE. It's name is
2125 NAME, its fields are chained in reverse on FIELDS.
2127 If ALIGN_TYPE is non-null, it is given the same alignment as
2131 finish_builtin_struct (tree type
, const char *name
, tree fields
,
2136 for (tail
= NULL_TREE
; fields
; tail
= fields
, fields
= next
)
2138 DECL_FIELD_CONTEXT (fields
) = type
;
2139 next
= DECL_CHAIN (fields
);
2140 DECL_CHAIN (fields
) = tail
;
2142 TYPE_FIELDS (type
) = tail
;
2146 SET_TYPE_ALIGN (type
, TYPE_ALIGN (align_type
));
2147 TYPE_USER_ALIGN (type
) = TYPE_USER_ALIGN (align_type
);
2148 SET_TYPE_WARN_IF_NOT_ALIGN (type
,
2149 TYPE_WARN_IF_NOT_ALIGN (align_type
));
2153 #if 0 /* not yet, should get fixed properly later */
2154 TYPE_NAME (type
) = make_type_decl (get_identifier (name
), type
);
2156 TYPE_NAME (type
) = build_decl (BUILTINS_LOCATION
,
2157 TYPE_DECL
, get_identifier (name
), type
);
2159 TYPE_STUB_DECL (type
) = TYPE_NAME (type
);
2160 layout_decl (TYPE_NAME (type
), 0);
2163 /* Calculate the mode, size, and alignment for TYPE.
2164 For an array type, calculate the element separation as well.
2165 Record TYPE on the chain of permanent or temporary types
2166 so that dbxout will find out about it.
2168 TYPE_SIZE of a type is nonzero if the type has been laid out already.
2169 layout_type does nothing on such a type.
2171 If the type is incomplete, its TYPE_SIZE remains zero. */
2174 layout_type (tree type
)
2178 if (type
== error_mark_node
)
2181 /* We don't want finalize_type_size to copy an alignment attribute to
2182 variants that don't have it. */
2183 type
= TYPE_MAIN_VARIANT (type
);
2185 /* Do nothing if type has been laid out before. */
2186 if (TYPE_SIZE (type
))
2189 switch (TREE_CODE (type
))
2192 /* This kind of type is the responsibility
2193 of the language-specific code. */
2200 scalar_int_mode mode
2201 = smallest_int_mode_for_size (TYPE_PRECISION (type
));
2202 SET_TYPE_MODE (type
, mode
);
2203 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2204 /* Don't set TYPE_PRECISION here, as it may be set by a bitfield. */
2205 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2211 /* Allow the caller to choose the type mode, which is how decimal
2212 floats are distinguished from binary ones. */
2213 if (TYPE_MODE (type
) == VOIDmode
)
2215 (type
, float_mode_for_size (TYPE_PRECISION (type
)).require ());
2216 scalar_float_mode mode
= as_a
<scalar_float_mode
> (TYPE_MODE (type
));
2217 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2218 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2222 case FIXED_POINT_TYPE
:
2223 /* TYPE_MODE (type) has been set already. */
2224 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
2225 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
2229 TYPE_UNSIGNED (type
) = TYPE_UNSIGNED (TREE_TYPE (type
));
2230 SET_TYPE_MODE (type
,
2231 GET_MODE_COMPLEX_MODE (TYPE_MODE (TREE_TYPE (type
))));
2233 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
2234 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
2239 int nunits
= TYPE_VECTOR_SUBPARTS (type
);
2240 tree innertype
= TREE_TYPE (type
);
2242 gcc_assert (!(nunits
& (nunits
- 1)));
2244 /* Find an appropriate mode for the vector type. */
2245 if (TYPE_MODE (type
) == VOIDmode
)
2246 SET_TYPE_MODE (type
,
2247 mode_for_vector (TYPE_MODE (innertype
), nunits
));
2249 TYPE_SATURATING (type
) = TYPE_SATURATING (TREE_TYPE (type
));
2250 TYPE_UNSIGNED (type
) = TYPE_UNSIGNED (TREE_TYPE (type
));
2251 /* Several boolean vector elements may fit in a single unit. */
2252 if (VECTOR_BOOLEAN_TYPE_P (type
)
2253 && type
->type_common
.mode
!= BLKmode
)
2254 TYPE_SIZE_UNIT (type
)
2255 = size_int (GET_MODE_SIZE (type
->type_common
.mode
));
2257 TYPE_SIZE_UNIT (type
) = int_const_binop (MULT_EXPR
,
2258 TYPE_SIZE_UNIT (innertype
),
2260 TYPE_SIZE (type
) = int_const_binop (MULT_EXPR
,
2261 TYPE_SIZE (innertype
),
2262 bitsize_int (nunits
));
2264 /* For vector types, we do not default to the mode's alignment.
2265 Instead, query a target hook, defaulting to natural alignment.
2266 This prevents ABI changes depending on whether or not native
2267 vector modes are supported. */
2268 SET_TYPE_ALIGN (type
, targetm
.vector_alignment (type
));
2270 /* However, if the underlying mode requires a bigger alignment than
2271 what the target hook provides, we cannot use the mode. For now,
2272 simply reject that case. */
2273 gcc_assert (TYPE_ALIGN (type
)
2274 >= GET_MODE_ALIGNMENT (TYPE_MODE (type
)));
2279 /* This is an incomplete type and so doesn't have a size. */
2280 SET_TYPE_ALIGN (type
, 1);
2281 TYPE_USER_ALIGN (type
) = 0;
2282 SET_TYPE_MODE (type
, VOIDmode
);
2285 case POINTER_BOUNDS_TYPE
:
2286 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
2287 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
2291 TYPE_SIZE (type
) = bitsize_int (POINTER_SIZE
);
2292 TYPE_SIZE_UNIT (type
) = size_int (POINTER_SIZE_UNITS
);
2293 /* A pointer might be MODE_PARTIAL_INT, but ptrdiff_t must be
2294 integral, which may be an __intN. */
2295 SET_TYPE_MODE (type
, mode_for_size (POINTER_SIZE
, MODE_INT
, 0));
2296 TYPE_PRECISION (type
) = POINTER_SIZE
;
2301 /* It's hard to see what the mode and size of a function ought to
2302 be, but we do know the alignment is FUNCTION_BOUNDARY, so
2303 make it consistent with that. */
2304 SET_TYPE_MODE (type
, mode_for_size (FUNCTION_BOUNDARY
, MODE_INT
, 0));
2305 TYPE_SIZE (type
) = bitsize_int (FUNCTION_BOUNDARY
);
2306 TYPE_SIZE_UNIT (type
) = size_int (FUNCTION_BOUNDARY
/ BITS_PER_UNIT
);
2310 case REFERENCE_TYPE
:
2312 machine_mode mode
= TYPE_MODE (type
);
2313 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2314 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2315 TYPE_UNSIGNED (type
) = 1;
2316 TYPE_PRECISION (type
) = GET_MODE_PRECISION (mode
);
2322 tree index
= TYPE_DOMAIN (type
);
2323 tree element
= TREE_TYPE (type
);
2325 /* We need to know both bounds in order to compute the size. */
2326 if (index
&& TYPE_MAX_VALUE (index
) && TYPE_MIN_VALUE (index
)
2327 && TYPE_SIZE (element
))
2329 tree ub
= TYPE_MAX_VALUE (index
);
2330 tree lb
= TYPE_MIN_VALUE (index
);
2331 tree element_size
= TYPE_SIZE (element
);
2334 /* Make sure that an array of zero-sized element is zero-sized
2335 regardless of its extent. */
2336 if (integer_zerop (element_size
))
2337 length
= size_zero_node
;
2339 /* The computation should happen in the original signedness so
2340 that (possible) negative values are handled appropriately
2341 when determining overflow. */
2344 /* ??? When it is obvious that the range is signed
2345 represent it using ssizetype. */
2346 if (TREE_CODE (lb
) == INTEGER_CST
2347 && TREE_CODE (ub
) == INTEGER_CST
2348 && TYPE_UNSIGNED (TREE_TYPE (lb
))
2349 && tree_int_cst_lt (ub
, lb
))
2351 lb
= wide_int_to_tree (ssizetype
,
2352 offset_int::from (lb
, SIGNED
));
2353 ub
= wide_int_to_tree (ssizetype
,
2354 offset_int::from (ub
, SIGNED
));
2357 = fold_convert (sizetype
,
2358 size_binop (PLUS_EXPR
,
2359 build_int_cst (TREE_TYPE (lb
), 1),
2360 size_binop (MINUS_EXPR
, ub
, lb
)));
2363 /* ??? We have no way to distinguish a null-sized array from an
2364 array spanning the whole sizetype range, so we arbitrarily
2365 decide that [0, -1] is the only valid representation. */
2366 if (integer_zerop (length
)
2367 && TREE_OVERFLOW (length
)
2368 && integer_zerop (lb
))
2369 length
= size_zero_node
;
2371 TYPE_SIZE (type
) = size_binop (MULT_EXPR
, element_size
,
2372 fold_convert (bitsizetype
,
2375 /* If we know the size of the element, calculate the total size
2376 directly, rather than do some division thing below. This
2377 optimization helps Fortran assumed-size arrays (where the
2378 size of the array is determined at runtime) substantially. */
2379 if (TYPE_SIZE_UNIT (element
))
2380 TYPE_SIZE_UNIT (type
)
2381 = size_binop (MULT_EXPR
, TYPE_SIZE_UNIT (element
), length
);
2384 /* Now round the alignment and size,
2385 using machine-dependent criteria if any. */
2387 unsigned align
= TYPE_ALIGN (element
);
2388 if (TYPE_USER_ALIGN (type
))
2389 align
= MAX (align
, TYPE_ALIGN (type
));
2391 TYPE_USER_ALIGN (type
) = TYPE_USER_ALIGN (element
);
2392 if (!TYPE_WARN_IF_NOT_ALIGN (type
))
2393 SET_TYPE_WARN_IF_NOT_ALIGN (type
,
2394 TYPE_WARN_IF_NOT_ALIGN (element
));
2395 #ifdef ROUND_TYPE_ALIGN
2396 align
= ROUND_TYPE_ALIGN (type
, align
, BITS_PER_UNIT
);
2398 align
= MAX (align
, BITS_PER_UNIT
);
2400 SET_TYPE_ALIGN (type
, align
);
2401 SET_TYPE_MODE (type
, BLKmode
);
2402 if (TYPE_SIZE (type
) != 0
2403 && ! targetm
.member_type_forces_blk (type
, VOIDmode
)
2404 /* BLKmode elements force BLKmode aggregate;
2405 else extract/store fields may lose. */
2406 && (TYPE_MODE (TREE_TYPE (type
)) != BLKmode
2407 || TYPE_NO_FORCE_BLK (TREE_TYPE (type
))))
2409 SET_TYPE_MODE (type
, mode_for_array (TREE_TYPE (type
),
2411 if (TYPE_MODE (type
) != BLKmode
2412 && STRICT_ALIGNMENT
&& TYPE_ALIGN (type
) < BIGGEST_ALIGNMENT
2413 && TYPE_ALIGN (type
) < GET_MODE_ALIGNMENT (TYPE_MODE (type
)))
2415 TYPE_NO_FORCE_BLK (type
) = 1;
2416 SET_TYPE_MODE (type
, BLKmode
);
2419 if (AGGREGATE_TYPE_P (element
))
2420 TYPE_TYPELESS_STORAGE (type
) = TYPE_TYPELESS_STORAGE (element
);
2421 /* When the element size is constant, check that it is at least as
2422 large as the element alignment. */
2423 if (TYPE_SIZE_UNIT (element
)
2424 && TREE_CODE (TYPE_SIZE_UNIT (element
)) == INTEGER_CST
2425 /* If TYPE_SIZE_UNIT overflowed, then it is certainly larger than
2427 && !TREE_OVERFLOW (TYPE_SIZE_UNIT (element
))
2428 && !integer_zerop (TYPE_SIZE_UNIT (element
))
2429 && compare_tree_int (TYPE_SIZE_UNIT (element
),
2430 TYPE_ALIGN_UNIT (element
)) < 0)
2431 error ("alignment of array elements is greater than element size");
2437 case QUAL_UNION_TYPE
:
2440 record_layout_info rli
;
2442 /* Initialize the layout information. */
2443 rli
= start_record_layout (type
);
2445 /* If this is a QUAL_UNION_TYPE, we want to process the fields
2446 in the reverse order in building the COND_EXPR that denotes
2447 its size. We reverse them again later. */
2448 if (TREE_CODE (type
) == QUAL_UNION_TYPE
)
2449 TYPE_FIELDS (type
) = nreverse (TYPE_FIELDS (type
));
2451 /* Place all the fields. */
2452 for (field
= TYPE_FIELDS (type
); field
; field
= DECL_CHAIN (field
))
2453 place_field (rli
, field
);
2455 if (TREE_CODE (type
) == QUAL_UNION_TYPE
)
2456 TYPE_FIELDS (type
) = nreverse (TYPE_FIELDS (type
));
2458 /* Finish laying out the record. */
2459 finish_record_layout (rli
, /*free_p=*/true);
2467 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
2468 records and unions, finish_record_layout already called this
2470 if (!RECORD_OR_UNION_TYPE_P (type
))
2471 finalize_type_size (type
);
2473 /* We should never see alias sets on incomplete aggregates. And we
2474 should not call layout_type on not incomplete aggregates. */
2475 if (AGGREGATE_TYPE_P (type
))
2476 gcc_assert (!TYPE_ALIAS_SET_KNOWN_P (type
));
2479 /* Return the least alignment required for type TYPE. */
2482 min_align_of_type (tree type
)
2484 unsigned int align
= TYPE_ALIGN (type
);
2485 if (!TYPE_USER_ALIGN (type
))
2487 align
= MIN (align
, BIGGEST_ALIGNMENT
);
2488 #ifdef BIGGEST_FIELD_ALIGNMENT
2489 align
= MIN (align
, BIGGEST_FIELD_ALIGNMENT
);
2491 unsigned int field_align
= align
;
2492 #ifdef ADJUST_FIELD_ALIGN
2493 field_align
= ADJUST_FIELD_ALIGN (NULL_TREE
, type
, field_align
);
2495 align
= MIN (align
, field_align
);
2497 return align
/ BITS_PER_UNIT
;
2500 /* Create and return a type for signed integers of PRECISION bits. */
2503 make_signed_type (int precision
)
2505 tree type
= make_node (INTEGER_TYPE
);
2507 TYPE_PRECISION (type
) = precision
;
2509 fixup_signed_type (type
);
2513 /* Create and return a type for unsigned integers of PRECISION bits. */
2516 make_unsigned_type (int precision
)
2518 tree type
= make_node (INTEGER_TYPE
);
2520 TYPE_PRECISION (type
) = precision
;
2522 fixup_unsigned_type (type
);
2526 /* Create and return a type for fract of PRECISION bits, UNSIGNEDP,
2530 make_fract_type (int precision
, int unsignedp
, int satp
)
2532 tree type
= make_node (FIXED_POINT_TYPE
);
2534 TYPE_PRECISION (type
) = precision
;
2537 TYPE_SATURATING (type
) = 1;
2539 /* Lay out the type: set its alignment, size, etc. */
2542 TYPE_UNSIGNED (type
) = 1;
2543 SET_TYPE_MODE (type
, mode_for_size (precision
, MODE_UFRACT
, 0));
2546 SET_TYPE_MODE (type
, mode_for_size (precision
, MODE_FRACT
, 0));
2552 /* Create and return a type for accum of PRECISION bits, UNSIGNEDP,
2556 make_accum_type (int precision
, int unsignedp
, int satp
)
2558 tree type
= make_node (FIXED_POINT_TYPE
);
2560 TYPE_PRECISION (type
) = precision
;
2563 TYPE_SATURATING (type
) = 1;
2565 /* Lay out the type: set its alignment, size, etc. */
2568 TYPE_UNSIGNED (type
) = 1;
2569 SET_TYPE_MODE (type
, mode_for_size (precision
, MODE_UACCUM
, 0));
2572 SET_TYPE_MODE (type
, mode_for_size (precision
, MODE_ACCUM
, 0));
2578 /* Initialize sizetypes so layout_type can use them. */
2581 initialize_sizetypes (void)
2583 int precision
, bprecision
;
2585 /* Get sizetypes precision from the SIZE_TYPE target macro. */
2586 if (strcmp (SIZETYPE
, "unsigned int") == 0)
2587 precision
= INT_TYPE_SIZE
;
2588 else if (strcmp (SIZETYPE
, "long unsigned int") == 0)
2589 precision
= LONG_TYPE_SIZE
;
2590 else if (strcmp (SIZETYPE
, "long long unsigned int") == 0)
2591 precision
= LONG_LONG_TYPE_SIZE
;
2592 else if (strcmp (SIZETYPE
, "short unsigned int") == 0)
2593 precision
= SHORT_TYPE_SIZE
;
2599 for (i
= 0; i
< NUM_INT_N_ENTS
; i
++)
2600 if (int_n_enabled_p
[i
])
2603 sprintf (name
, "__int%d unsigned", int_n_data
[i
].bitsize
);
2605 if (strcmp (name
, SIZETYPE
) == 0)
2607 precision
= int_n_data
[i
].bitsize
;
2610 if (precision
== -1)
2615 = MIN (precision
+ LOG2_BITS_PER_UNIT
+ 1, MAX_FIXED_MODE_SIZE
);
2616 bprecision
= GET_MODE_PRECISION (smallest_int_mode_for_size (bprecision
));
2617 if (bprecision
> HOST_BITS_PER_DOUBLE_INT
)
2618 bprecision
= HOST_BITS_PER_DOUBLE_INT
;
2620 /* Create stubs for sizetype and bitsizetype so we can create constants. */
2621 sizetype
= make_node (INTEGER_TYPE
);
2622 TYPE_NAME (sizetype
) = get_identifier ("sizetype");
2623 TYPE_PRECISION (sizetype
) = precision
;
2624 TYPE_UNSIGNED (sizetype
) = 1;
2625 bitsizetype
= make_node (INTEGER_TYPE
);
2626 TYPE_NAME (bitsizetype
) = get_identifier ("bitsizetype");
2627 TYPE_PRECISION (bitsizetype
) = bprecision
;
2628 TYPE_UNSIGNED (bitsizetype
) = 1;
2630 /* Now layout both types manually. */
2631 scalar_int_mode mode
= smallest_int_mode_for_size (precision
);
2632 SET_TYPE_MODE (sizetype
, mode
);
2633 SET_TYPE_ALIGN (sizetype
, GET_MODE_ALIGNMENT (TYPE_MODE (sizetype
)));
2634 TYPE_SIZE (sizetype
) = bitsize_int (precision
);
2635 TYPE_SIZE_UNIT (sizetype
) = size_int (GET_MODE_SIZE (mode
));
2636 set_min_and_max_values_for_integral_type (sizetype
, precision
, UNSIGNED
);
2638 mode
= smallest_int_mode_for_size (bprecision
);
2639 SET_TYPE_MODE (bitsizetype
, mode
);
2640 SET_TYPE_ALIGN (bitsizetype
, GET_MODE_ALIGNMENT (TYPE_MODE (bitsizetype
)));
2641 TYPE_SIZE (bitsizetype
) = bitsize_int (bprecision
);
2642 TYPE_SIZE_UNIT (bitsizetype
) = size_int (GET_MODE_SIZE (mode
));
2643 set_min_and_max_values_for_integral_type (bitsizetype
, bprecision
, UNSIGNED
);
2645 /* Create the signed variants of *sizetype. */
2646 ssizetype
= make_signed_type (TYPE_PRECISION (sizetype
));
2647 TYPE_NAME (ssizetype
) = get_identifier ("ssizetype");
2648 sbitsizetype
= make_signed_type (TYPE_PRECISION (bitsizetype
));
2649 TYPE_NAME (sbitsizetype
) = get_identifier ("sbitsizetype");
2652 /* TYPE is an integral type, i.e., an INTEGRAL_TYPE, ENUMERAL_TYPE
2653 or BOOLEAN_TYPE. Set TYPE_MIN_VALUE and TYPE_MAX_VALUE
2654 for TYPE, based on the PRECISION and whether or not the TYPE
2655 IS_UNSIGNED. PRECISION need not correspond to a width supported
2656 natively by the hardware; for example, on a machine with 8-bit,
2657 16-bit, and 32-bit register modes, PRECISION might be 7, 23, or
2661 set_min_and_max_values_for_integral_type (tree type
,
2665 /* For bitfields with zero width we end up creating integer types
2666 with zero precision. Don't assign any minimum/maximum values
2667 to those types, they don't have any valid value. */
2671 TYPE_MIN_VALUE (type
)
2672 = wide_int_to_tree (type
, wi::min_value (precision
, sgn
));
2673 TYPE_MAX_VALUE (type
)
2674 = wide_int_to_tree (type
, wi::max_value (precision
, sgn
));
2677 /* Set the extreme values of TYPE based on its precision in bits,
2678 then lay it out. Used when make_signed_type won't do
2679 because the tree code is not INTEGER_TYPE. */
2682 fixup_signed_type (tree type
)
2684 int precision
= TYPE_PRECISION (type
);
2686 set_min_and_max_values_for_integral_type (type
, precision
, SIGNED
);
2688 /* Lay out the type: set its alignment, size, etc. */
2692 /* Set the extreme values of TYPE based on its precision in bits,
2693 then lay it out. This is used both in `make_unsigned_type'
2694 and for enumeral types. */
2697 fixup_unsigned_type (tree type
)
2699 int precision
= TYPE_PRECISION (type
);
2701 TYPE_UNSIGNED (type
) = 1;
2703 set_min_and_max_values_for_integral_type (type
, precision
, UNSIGNED
);
2705 /* Lay out the type: set its alignment, size, etc. */
2709 /* Construct an iterator for a bitfield that spans BITSIZE bits,
2712 BITREGION_START is the bit position of the first bit in this
2713 sequence of bit fields. BITREGION_END is the last bit in this
2714 sequence. If these two fields are non-zero, we should restrict the
2715 memory access to that range. Otherwise, we are allowed to touch
2716 any adjacent non bit-fields.
2718 ALIGN is the alignment of the underlying object in bits.
2719 VOLATILEP says whether the bitfield is volatile. */
2721 bit_field_mode_iterator
2722 ::bit_field_mode_iterator (HOST_WIDE_INT bitsize
, HOST_WIDE_INT bitpos
,
2723 HOST_WIDE_INT bitregion_start
,
2724 HOST_WIDE_INT bitregion_end
,
2725 unsigned int align
, bool volatilep
)
2726 : m_mode (GET_CLASS_NARROWEST_MODE (MODE_INT
)), m_bitsize (bitsize
),
2727 m_bitpos (bitpos
), m_bitregion_start (bitregion_start
),
2728 m_bitregion_end (bitregion_end
), m_align (align
),
2729 m_volatilep (volatilep
), m_count (0)
2731 if (!m_bitregion_end
)
2733 /* We can assume that any aligned chunk of ALIGN bits that overlaps
2734 the bitfield is mapped and won't trap, provided that ALIGN isn't
2735 too large. The cap is the biggest required alignment for data,
2736 or at least the word size. And force one such chunk at least. */
2737 unsigned HOST_WIDE_INT units
2738 = MIN (align
, MAX (BIGGEST_ALIGNMENT
, BITS_PER_WORD
));
2741 m_bitregion_end
= bitpos
+ bitsize
+ units
- 1;
2742 m_bitregion_end
-= m_bitregion_end
% units
+ 1;
2746 /* Calls to this function return successively larger modes that can be used
2747 to represent the bitfield. Return true if another bitfield mode is
2748 available, storing it in *OUT_MODE if so. */
2751 bit_field_mode_iterator::next_mode (machine_mode
*out_mode
)
2753 for (; m_mode
!= VOIDmode
;
2754 m_mode
= GET_MODE_WIDER_MODE (m_mode
).else_void ())
2756 unsigned int unit
= GET_MODE_BITSIZE (m_mode
);
2758 /* Skip modes that don't have full precision. */
2759 if (unit
!= GET_MODE_PRECISION (m_mode
))
2762 /* Stop if the mode is too wide to handle efficiently. */
2763 if (unit
> MAX_FIXED_MODE_SIZE
)
2766 /* Don't deliver more than one multiword mode; the smallest one
2768 if (m_count
> 0 && unit
> BITS_PER_WORD
)
2771 /* Skip modes that are too small. */
2772 unsigned HOST_WIDE_INT substart
= (unsigned HOST_WIDE_INT
) m_bitpos
% unit
;
2773 unsigned HOST_WIDE_INT subend
= substart
+ m_bitsize
;
2777 /* Stop if the mode goes outside the bitregion. */
2778 HOST_WIDE_INT start
= m_bitpos
- substart
;
2779 if (m_bitregion_start
&& start
< m_bitregion_start
)
2781 HOST_WIDE_INT end
= start
+ unit
;
2782 if (end
> m_bitregion_end
+ 1)
2785 /* Stop if the mode requires too much alignment. */
2786 if (GET_MODE_ALIGNMENT (m_mode
) > m_align
2787 && SLOW_UNALIGNED_ACCESS (m_mode
, m_align
))
2791 m_mode
= GET_MODE_WIDER_MODE (m_mode
).else_void ();
2798 /* Return true if smaller modes are generally preferred for this kind
2802 bit_field_mode_iterator::prefer_smaller_modes ()
2805 ? targetm
.narrow_volatile_bitfield ()
2806 : !SLOW_BYTE_ACCESS
);
2809 /* Find the best machine mode to use when referencing a bit field of length
2810 BITSIZE bits starting at BITPOS.
2812 BITREGION_START is the bit position of the first bit in this
2813 sequence of bit fields. BITREGION_END is the last bit in this
2814 sequence. If these two fields are non-zero, we should restrict the
2815 memory access to that range. Otherwise, we are allowed to touch
2816 any adjacent non bit-fields.
2818 The underlying object is known to be aligned to a boundary of ALIGN bits.
2819 If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
2820 larger than LARGEST_MODE (usually SImode).
2822 If no mode meets all these conditions, we return VOIDmode.
2824 If VOLATILEP is false and SLOW_BYTE_ACCESS is false, we return the
2825 smallest mode meeting these conditions.
2827 If VOLATILEP is false and SLOW_BYTE_ACCESS is true, we return the
2828 largest mode (but a mode no wider than UNITS_PER_WORD) that meets
2831 If VOLATILEP is true the narrow_volatile_bitfields target hook is used to
2832 decide which of the above modes should be used. */
2835 get_best_mode (int bitsize
, int bitpos
,
2836 unsigned HOST_WIDE_INT bitregion_start
,
2837 unsigned HOST_WIDE_INT bitregion_end
,
2839 machine_mode largest_mode
, bool volatilep
)
2841 bit_field_mode_iterator
iter (bitsize
, bitpos
, bitregion_start
,
2842 bitregion_end
, align
, volatilep
);
2843 machine_mode widest_mode
= VOIDmode
;
2845 while (iter
.next_mode (&mode
)
2846 /* ??? For historical reasons, reject modes that would normally
2847 receive greater alignment, even if unaligned accesses are
2848 acceptable. This has both advantages and disadvantages.
2849 Removing this check means that something like:
2851 struct s { unsigned int x; unsigned int y; };
2852 int f (struct s *s) { return s->x == 0 && s->y == 0; }
2854 can be implemented using a single load and compare on
2855 64-bit machines that have no alignment restrictions.
2856 For example, on powerpc64-linux-gnu, we would generate:
2878 However, accessing more than one field can make life harder
2879 for the gimple optimizers. For example, gcc.dg/vect/bb-slp-5.c
2880 has a series of unsigned short copies followed by a series of
2881 unsigned short comparisons. With this check, both the copies
2882 and comparisons remain 16-bit accesses and FRE is able
2883 to eliminate the latter. Without the check, the comparisons
2884 can be done using 2 64-bit operations, which FRE isn't able
2885 to handle in the same way.
2887 Either way, it would probably be worth disabling this check
2888 during expand. One particular example where removing the
2889 check would help is the get_best_mode call in store_bit_field.
2890 If we are given a memory bitregion of 128 bits that is aligned
2891 to a 64-bit boundary, and the bitfield we want to modify is
2892 in the second half of the bitregion, this check causes
2893 store_bitfield to turn the memory into a 64-bit reference
2894 to the _first_ half of the region. We later use
2895 adjust_bitfield_address to get a reference to the correct half,
2896 but doing so looks to adjust_bitfield_address as though we are
2897 moving past the end of the original object, so it drops the
2898 associated MEM_EXPR and MEM_OFFSET. Removing the check
2899 causes store_bit_field to keep a 128-bit memory reference,
2900 so that the final bitfield reference still has a MEM_EXPR
2902 && GET_MODE_ALIGNMENT (mode
) <= align
2903 && (largest_mode
== VOIDmode
2904 || GET_MODE_SIZE (mode
) <= GET_MODE_SIZE (largest_mode
)))
2907 if (iter
.prefer_smaller_modes ())
2913 /* Gets minimal and maximal values for MODE (signed or unsigned depending on
2914 SIGN). The returned constants are made to be usable in TARGET_MODE. */
2917 get_mode_bounds (machine_mode mode
, int sign
,
2918 machine_mode target_mode
,
2919 rtx
*mmin
, rtx
*mmax
)
2921 unsigned size
= GET_MODE_PRECISION (mode
);
2922 unsigned HOST_WIDE_INT min_val
, max_val
;
2924 gcc_assert (size
<= HOST_BITS_PER_WIDE_INT
);
2926 /* Special case BImode, which has values 0 and STORE_FLAG_VALUE. */
2929 if (STORE_FLAG_VALUE
< 0)
2931 min_val
= STORE_FLAG_VALUE
;
2937 max_val
= STORE_FLAG_VALUE
;
2942 min_val
= -(HOST_WIDE_INT_1U
<< (size
- 1));
2943 max_val
= (HOST_WIDE_INT_1U
<< (size
- 1)) - 1;
2948 max_val
= (HOST_WIDE_INT_1U
<< (size
- 1) << 1) - 1;
2951 *mmin
= gen_int_mode (min_val
, target_mode
);
2952 *mmax
= gen_int_mode (max_val
, target_mode
);
2955 #include "gt-stor-layout.h"