1 /* C-compiler utilities for types and variables storage layout
2 Copyright (C) 1987-2018 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
23 #include "coretypes.h"
30 #include "stringpool.h"
34 #include "diagnostic-core.h"
35 #include "fold-const.h"
36 #include "stor-layout.h"
38 #include "print-tree.h"
39 #include "langhooks.h"
40 #include "tree-inline.h"
46 /* Data type for the expressions representing sizes of data types.
47 It is the first integer type laid out. */
48 tree sizetype_tab
[(int) stk_type_kind_last
];
50 /* If nonzero, this is an upper limit on alignment of structure fields.
51 The value is measured in bits. */
52 unsigned int maximum_field_alignment
= TARGET_DEFAULT_PACK_STRUCT
* BITS_PER_UNIT
;
54 static tree
self_referential_size (tree
);
55 static void finalize_record_size (record_layout_info
);
56 static void finalize_type_size (tree
);
57 static void place_union_field (record_layout_info
, tree
);
58 static int excess_unit_span (HOST_WIDE_INT
, HOST_WIDE_INT
, HOST_WIDE_INT
,
60 extern void debug_rli (record_layout_info
);
62 /* Given a size SIZE that may not be a constant, return a SAVE_EXPR
63 to serve as the actual size-expression for a type or decl. */
66 variable_size (tree size
)
69 if (TREE_CONSTANT (size
))
72 /* If the size is self-referential, we can't make a SAVE_EXPR (see
73 save_expr for the rationale). But we can do something else. */
74 if (CONTAINS_PLACEHOLDER_P (size
))
75 return self_referential_size (size
);
77 /* If we are in the global binding level, we can't make a SAVE_EXPR
78 since it may end up being shared across functions, so it is up
79 to the front-end to deal with this case. */
80 if (lang_hooks
.decls
.global_bindings_p ())
83 return save_expr (size
);
86 /* An array of functions used for self-referential size computation. */
87 static GTY(()) vec
<tree
, va_gc
> *size_functions
;
89 /* Return true if T is a self-referential component reference. */
92 self_referential_component_ref_p (tree t
)
94 if (TREE_CODE (t
) != COMPONENT_REF
)
97 while (REFERENCE_CLASS_P (t
))
98 t
= TREE_OPERAND (t
, 0);
100 return (TREE_CODE (t
) == PLACEHOLDER_EXPR
);
103 /* Similar to copy_tree_r but do not copy component references involving
104 PLACEHOLDER_EXPRs. These nodes are spotted in find_placeholder_in_expr
105 and substituted in substitute_in_expr. */
108 copy_self_referential_tree_r (tree
*tp
, int *walk_subtrees
, void *data
)
110 enum tree_code code
= TREE_CODE (*tp
);
112 /* Stop at types, decls, constants like copy_tree_r. */
113 if (TREE_CODE_CLASS (code
) == tcc_type
114 || TREE_CODE_CLASS (code
) == tcc_declaration
115 || TREE_CODE_CLASS (code
) == tcc_constant
)
121 /* This is the pattern built in ada/make_aligning_type. */
122 else if (code
== ADDR_EXPR
123 && TREE_CODE (TREE_OPERAND (*tp
, 0)) == PLACEHOLDER_EXPR
)
129 /* Default case: the component reference. */
130 else if (self_referential_component_ref_p (*tp
))
136 /* We're not supposed to have them in self-referential size trees
137 because we wouldn't properly control when they are evaluated.
138 However, not creating superfluous SAVE_EXPRs requires accurate
139 tracking of readonly-ness all the way down to here, which we
140 cannot always guarantee in practice. So punt in this case. */
141 else if (code
== SAVE_EXPR
)
142 return error_mark_node
;
144 else if (code
== STATEMENT_LIST
)
147 return copy_tree_r (tp
, walk_subtrees
, data
);
150 /* Given a SIZE expression that is self-referential, return an equivalent
151 expression to serve as the actual size expression for a type. */
154 self_referential_size (tree size
)
156 static unsigned HOST_WIDE_INT fnno
= 0;
157 vec
<tree
> self_refs
= vNULL
;
158 tree param_type_list
= NULL
, param_decl_list
= NULL
;
159 tree t
, ref
, return_type
, fntype
, fnname
, fndecl
;
162 vec
<tree
, va_gc
> *args
= NULL
;
164 /* Do not factor out simple operations. */
165 t
= skip_simple_constant_arithmetic (size
);
166 if (TREE_CODE (t
) == CALL_EXPR
|| self_referential_component_ref_p (t
))
169 /* Collect the list of self-references in the expression. */
170 find_placeholder_in_expr (size
, &self_refs
);
171 gcc_assert (self_refs
.length () > 0);
173 /* Obtain a private copy of the expression. */
175 if (walk_tree (&t
, copy_self_referential_tree_r
, NULL
, NULL
) != NULL_TREE
)
179 /* Build the parameter and argument lists in parallel; also
180 substitute the former for the latter in the expression. */
181 vec_alloc (args
, self_refs
.length ());
182 FOR_EACH_VEC_ELT (self_refs
, i
, ref
)
184 tree subst
, param_name
, param_type
, param_decl
;
188 /* We shouldn't have true variables here. */
189 gcc_assert (TREE_READONLY (ref
));
192 /* This is the pattern built in ada/make_aligning_type. */
193 else if (TREE_CODE (ref
) == ADDR_EXPR
)
195 /* Default case: the component reference. */
197 subst
= TREE_OPERAND (ref
, 1);
199 sprintf (buf
, "p%d", i
);
200 param_name
= get_identifier (buf
);
201 param_type
= TREE_TYPE (ref
);
203 = build_decl (input_location
, PARM_DECL
, param_name
, param_type
);
204 DECL_ARG_TYPE (param_decl
) = param_type
;
205 DECL_ARTIFICIAL (param_decl
) = 1;
206 TREE_READONLY (param_decl
) = 1;
208 size
= substitute_in_expr (size
, subst
, param_decl
);
210 param_type_list
= tree_cons (NULL_TREE
, param_type
, param_type_list
);
211 param_decl_list
= chainon (param_decl
, param_decl_list
);
212 args
->quick_push (ref
);
215 self_refs
.release ();
217 /* Append 'void' to indicate that the number of parameters is fixed. */
218 param_type_list
= tree_cons (NULL_TREE
, void_type_node
, param_type_list
);
220 /* The 3 lists have been created in reverse order. */
221 param_type_list
= nreverse (param_type_list
);
222 param_decl_list
= nreverse (param_decl_list
);
224 /* Build the function type. */
225 return_type
= TREE_TYPE (size
);
226 fntype
= build_function_type (return_type
, param_type_list
);
228 /* Build the function declaration. */
229 sprintf (buf
, "SZ" HOST_WIDE_INT_PRINT_UNSIGNED
, fnno
++);
230 fnname
= get_file_function_name (buf
);
231 fndecl
= build_decl (input_location
, FUNCTION_DECL
, fnname
, fntype
);
232 for (t
= param_decl_list
; t
; t
= DECL_CHAIN (t
))
233 DECL_CONTEXT (t
) = fndecl
;
234 DECL_ARGUMENTS (fndecl
) = param_decl_list
;
236 = build_decl (input_location
, RESULT_DECL
, 0, return_type
);
237 DECL_CONTEXT (DECL_RESULT (fndecl
)) = fndecl
;
239 /* The function has been created by the compiler and we don't
240 want to emit debug info for it. */
241 DECL_ARTIFICIAL (fndecl
) = 1;
242 DECL_IGNORED_P (fndecl
) = 1;
244 /* It is supposed to be "const" and never throw. */
245 TREE_READONLY (fndecl
) = 1;
246 TREE_NOTHROW (fndecl
) = 1;
248 /* We want it to be inlined when this is deemed profitable, as
249 well as discarded if every call has been integrated. */
250 DECL_DECLARED_INLINE_P (fndecl
) = 1;
252 /* It is made up of a unique return statement. */
253 DECL_INITIAL (fndecl
) = make_node (BLOCK
);
254 BLOCK_SUPERCONTEXT (DECL_INITIAL (fndecl
)) = fndecl
;
255 t
= build2 (MODIFY_EXPR
, return_type
, DECL_RESULT (fndecl
), size
);
256 DECL_SAVED_TREE (fndecl
) = build1 (RETURN_EXPR
, void_type_node
, t
);
257 TREE_STATIC (fndecl
) = 1;
259 /* Put it onto the list of size functions. */
260 vec_safe_push (size_functions
, fndecl
);
262 /* Replace the original expression with a call to the size function. */
263 return build_call_expr_loc_vec (UNKNOWN_LOCATION
, fndecl
, args
);
266 /* Take, queue and compile all the size functions. It is essential that
267 the size functions be gimplified at the very end of the compilation
268 in order to guarantee transparent handling of self-referential sizes.
269 Otherwise the GENERIC inliner would not be able to inline them back
270 at each of their call sites, thus creating artificial non-constant
271 size expressions which would trigger nasty problems later on. */
274 finalize_size_functions (void)
279 for (i
= 0; size_functions
&& size_functions
->iterate (i
, &fndecl
); i
++)
281 allocate_struct_function (fndecl
, false);
283 dump_function (TDI_original
, fndecl
);
285 /* As these functions are used to describe the layout of variable-length
286 structures, debug info generation needs their implementation. */
287 debug_hooks
->size_function (fndecl
);
288 gimplify_function_tree (fndecl
);
289 cgraph_node::finalize_function (fndecl
, false);
292 vec_free (size_functions
);
295 /* Return a machine mode of class MCLASS with SIZE bits of precision,
296 if one exists. The mode may have padding bits as well the SIZE
297 value bits. If LIMIT is nonzero, disregard modes wider than
298 MAX_FIXED_MODE_SIZE. */
301 mode_for_size (poly_uint64 size
, enum mode_class mclass
, int limit
)
306 if (limit
&& maybe_gt (size
, (unsigned int) MAX_FIXED_MODE_SIZE
))
307 return opt_machine_mode ();
309 /* Get the first mode which has this size, in the specified class. */
310 FOR_EACH_MODE_IN_CLASS (mode
, mclass
)
311 if (known_eq (GET_MODE_PRECISION (mode
), size
))
314 if (mclass
== MODE_INT
|| mclass
== MODE_PARTIAL_INT
)
315 for (i
= 0; i
< NUM_INT_N_ENTS
; i
++)
316 if (known_eq (int_n_data
[i
].bitsize
, size
)
317 && int_n_enabled_p
[i
])
318 return int_n_data
[i
].m
;
320 return opt_machine_mode ();
323 /* Similar, except passed a tree node. */
326 mode_for_size_tree (const_tree size
, enum mode_class mclass
, int limit
)
328 unsigned HOST_WIDE_INT uhwi
;
331 if (!tree_fits_uhwi_p (size
))
332 return opt_machine_mode ();
333 uhwi
= tree_to_uhwi (size
);
336 return opt_machine_mode ();
337 return mode_for_size (ui
, mclass
, limit
);
340 /* Return the narrowest mode of class MCLASS that contains at least
341 SIZE bits. Abort if no such mode exists. */
344 smallest_mode_for_size (poly_uint64 size
, enum mode_class mclass
)
346 machine_mode mode
= VOIDmode
;
349 /* Get the first mode which has at least this size, in the
351 FOR_EACH_MODE_IN_CLASS (mode
, mclass
)
352 if (known_ge (GET_MODE_PRECISION (mode
), size
))
355 gcc_assert (mode
!= VOIDmode
);
357 if (mclass
== MODE_INT
|| mclass
== MODE_PARTIAL_INT
)
358 for (i
= 0; i
< NUM_INT_N_ENTS
; i
++)
359 if (known_ge (int_n_data
[i
].bitsize
, size
)
360 && known_lt (int_n_data
[i
].bitsize
, GET_MODE_PRECISION (mode
))
361 && int_n_enabled_p
[i
])
362 mode
= int_n_data
[i
].m
;
367 /* Return an integer mode of exactly the same size as MODE, if one exists. */
370 int_mode_for_mode (machine_mode mode
)
372 switch (GET_MODE_CLASS (mode
))
375 case MODE_PARTIAL_INT
:
376 return as_a
<scalar_int_mode
> (mode
);
378 case MODE_COMPLEX_INT
:
379 case MODE_COMPLEX_FLOAT
:
381 case MODE_DECIMAL_FLOAT
:
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,
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 (trial
) == MODE_COMPLEX_INT
430 || mode_for_size (bitsize
, MODE_COMPLEX_INT
, false).exists (&trial
))
431 && have_regs_of_mode
[GET_MODE_INNER (trial
)])
435 /* Try to replace vector modes with vector modes. Also try using vector
436 modes if an integer mode would be too big. */
437 if (VECTOR_MODE_P (mode
) || bitsize
> MAX_FIXED_MODE_SIZE
)
439 machine_mode trial
= mode
;
440 if ((GET_MODE_CLASS (trial
) == MODE_VECTOR_INT
441 || mode_for_size (bitsize
, MODE_VECTOR_INT
, 0).exists (&trial
))
442 && have_regs_of_mode
[trial
]
443 && targetm
.vector_mode_supported_p (trial
))
447 /* Otherwise fall back on integers while honoring MAX_FIXED_MODE_SIZE. */
448 return mode_for_size (bitsize
, MODE_INT
, true);
451 /* Find a type that can be used for efficient bitwise operations on MODE.
452 Return null if no such mode exists. */
455 bitwise_type_for_mode (machine_mode mode
)
457 if (!bitwise_mode_for_mode (mode
).exists (&mode
))
460 unsigned int inner_size
= GET_MODE_UNIT_BITSIZE (mode
);
461 tree inner_type
= build_nonstandard_integer_type (inner_size
, true);
463 if (VECTOR_MODE_P (mode
))
464 return build_vector_type_for_mode (inner_type
, mode
);
466 if (COMPLEX_MODE_P (mode
))
467 return build_complex_type (inner_type
);
469 gcc_checking_assert (GET_MODE_INNER (mode
) == mode
);
473 /* Find a mode that is suitable for representing a vector with NUNITS
474 elements of mode INNERMODE, if one exists. The returned mode can be
475 either an integer mode or a vector mode. */
478 mode_for_vector (scalar_mode innermode
, poly_uint64 nunits
)
482 /* First, look for a supported vector type. */
483 if (SCALAR_FLOAT_MODE_P (innermode
))
484 mode
= MIN_MODE_VECTOR_FLOAT
;
485 else if (SCALAR_FRACT_MODE_P (innermode
))
486 mode
= MIN_MODE_VECTOR_FRACT
;
487 else if (SCALAR_UFRACT_MODE_P (innermode
))
488 mode
= MIN_MODE_VECTOR_UFRACT
;
489 else if (SCALAR_ACCUM_MODE_P (innermode
))
490 mode
= MIN_MODE_VECTOR_ACCUM
;
491 else if (SCALAR_UACCUM_MODE_P (innermode
))
492 mode
= MIN_MODE_VECTOR_UACCUM
;
494 mode
= MIN_MODE_VECTOR_INT
;
496 /* Do not check vector_mode_supported_p here. We'll do that
497 later in vector_type_mode. */
498 FOR_EACH_MODE_FROM (mode
, mode
)
499 if (known_eq (GET_MODE_NUNITS (mode
), nunits
)
500 && GET_MODE_INNER (mode
) == innermode
)
503 /* For integers, try mapping it to a same-sized scalar mode. */
504 if (GET_MODE_CLASS (innermode
) == MODE_INT
)
506 poly_uint64 nbits
= nunits
* GET_MODE_BITSIZE (innermode
);
507 if (int_mode_for_size (nbits
, 0).exists (&mode
)
508 && have_regs_of_mode
[mode
])
512 return opt_machine_mode ();
515 /* Return the mode for a vector that has NUNITS integer elements of
516 INT_BITS bits each, if such a mode exists. The mode can be either
517 an integer mode or a vector mode. */
520 mode_for_int_vector (unsigned int int_bits
, poly_uint64 nunits
)
522 scalar_int_mode int_mode
;
523 machine_mode vec_mode
;
524 if (int_mode_for_size (int_bits
, 0).exists (&int_mode
)
525 && mode_for_vector (int_mode
, nunits
).exists (&vec_mode
))
527 return opt_machine_mode ();
530 /* Return the alignment of MODE. This will be bounded by 1 and
531 BIGGEST_ALIGNMENT. */
534 get_mode_alignment (machine_mode mode
)
536 return MIN (BIGGEST_ALIGNMENT
, MAX (1, mode_base_align
[mode
]*BITS_PER_UNIT
));
539 /* Return the natural mode of an array, given that it is SIZE bytes in
540 total and has elements of type ELEM_TYPE. */
543 mode_for_array (tree elem_type
, tree size
)
546 unsigned HOST_WIDE_INT int_size
, int_elem_size
;
549 /* One-element arrays get the component type's mode. */
550 elem_size
= TYPE_SIZE (elem_type
);
551 if (simple_cst_equal (size
, elem_size
))
552 return TYPE_MODE (elem_type
);
555 if (tree_fits_uhwi_p (size
) && tree_fits_uhwi_p (elem_size
))
557 int_size
= tree_to_uhwi (size
);
558 int_elem_size
= tree_to_uhwi (elem_size
);
559 if (int_elem_size
> 0
560 && int_size
% int_elem_size
== 0
561 && targetm
.array_mode_supported_p (TYPE_MODE (elem_type
),
562 int_size
/ int_elem_size
))
565 return mode_for_size_tree (size
, MODE_INT
, limit_p
).else_blk ();
568 /* Subroutine of layout_decl: Force alignment required for the data type.
569 But if the decl itself wants greater alignment, don't override that. */
572 do_type_align (tree type
, tree decl
)
574 if (TYPE_ALIGN (type
) > DECL_ALIGN (decl
))
576 SET_DECL_ALIGN (decl
, TYPE_ALIGN (type
));
577 if (TREE_CODE (decl
) == FIELD_DECL
)
578 DECL_USER_ALIGN (decl
) = TYPE_USER_ALIGN (type
);
580 if (TYPE_WARN_IF_NOT_ALIGN (type
) > DECL_WARN_IF_NOT_ALIGN (decl
))
581 SET_DECL_WARN_IF_NOT_ALIGN (decl
, TYPE_WARN_IF_NOT_ALIGN (type
));
584 /* Set the size, mode and alignment of a ..._DECL node.
585 TYPE_DECL does need this for C++.
586 Note that LABEL_DECL and CONST_DECL nodes do not need this,
587 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
588 Don't call layout_decl for them.
590 KNOWN_ALIGN is the amount of alignment we can assume this
591 decl has with no special effort. It is relevant only for FIELD_DECLs
592 and depends on the previous fields.
593 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
594 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
595 the record will be aligned to suit. */
598 layout_decl (tree decl
, unsigned int known_align
)
600 tree type
= TREE_TYPE (decl
);
601 enum tree_code code
= TREE_CODE (decl
);
603 location_t loc
= DECL_SOURCE_LOCATION (decl
);
605 if (code
== CONST_DECL
)
608 gcc_assert (code
== VAR_DECL
|| code
== PARM_DECL
|| code
== RESULT_DECL
609 || code
== TYPE_DECL
|| code
== FIELD_DECL
);
611 rtl
= DECL_RTL_IF_SET (decl
);
613 if (type
== error_mark_node
)
614 type
= void_type_node
;
616 /* Usually the size and mode come from the data type without change,
617 however, the front-end may set the explicit width of the field, so its
618 size may not be the same as the size of its type. This happens with
619 bitfields, of course (an `int' bitfield may be only 2 bits, say), but it
620 also happens with other fields. For example, the C++ front-end creates
621 zero-sized fields corresponding to empty base classes, and depends on
622 layout_type setting DECL_FIELD_BITPOS correctly for the field. Set the
623 size in bytes from the size in bits. If we have already set the mode,
624 don't set it again since we can be called twice for FIELD_DECLs. */
626 DECL_UNSIGNED (decl
) = TYPE_UNSIGNED (type
);
627 if (DECL_MODE (decl
) == VOIDmode
)
628 SET_DECL_MODE (decl
, TYPE_MODE (type
));
630 if (DECL_SIZE (decl
) == 0)
632 DECL_SIZE (decl
) = TYPE_SIZE (type
);
633 DECL_SIZE_UNIT (decl
) = TYPE_SIZE_UNIT (type
);
635 else if (DECL_SIZE_UNIT (decl
) == 0)
636 DECL_SIZE_UNIT (decl
)
637 = fold_convert_loc (loc
, sizetype
,
638 size_binop_loc (loc
, CEIL_DIV_EXPR
, DECL_SIZE (decl
),
641 if (code
!= FIELD_DECL
)
642 /* For non-fields, update the alignment from the type. */
643 do_type_align (type
, decl
);
645 /* For fields, it's a bit more complicated... */
647 bool old_user_align
= DECL_USER_ALIGN (decl
);
648 bool zero_bitfield
= false;
649 bool packed_p
= DECL_PACKED (decl
);
652 if (DECL_BIT_FIELD (decl
))
654 DECL_BIT_FIELD_TYPE (decl
) = type
;
656 /* A zero-length bit-field affects the alignment of the next
657 field. In essence such bit-fields are not influenced by
658 any packing due to #pragma pack or attribute packed. */
659 if (integer_zerop (DECL_SIZE (decl
))
660 && ! targetm
.ms_bitfield_layout_p (DECL_FIELD_CONTEXT (decl
)))
662 zero_bitfield
= true;
664 if (PCC_BITFIELD_TYPE_MATTERS
)
665 do_type_align (type
, decl
);
668 #ifdef EMPTY_FIELD_BOUNDARY
669 if (EMPTY_FIELD_BOUNDARY
> DECL_ALIGN (decl
))
671 SET_DECL_ALIGN (decl
, EMPTY_FIELD_BOUNDARY
);
672 DECL_USER_ALIGN (decl
) = 0;
678 /* See if we can use an ordinary integer mode for a bit-field.
679 Conditions are: a fixed size that is correct for another mode,
680 occupying a complete byte or bytes on proper boundary. */
681 if (TYPE_SIZE (type
) != 0
682 && TREE_CODE (TYPE_SIZE (type
)) == INTEGER_CST
683 && GET_MODE_CLASS (TYPE_MODE (type
)) == MODE_INT
)
686 if (mode_for_size_tree (DECL_SIZE (decl
),
687 MODE_INT
, 1).exists (&xmode
))
689 unsigned int xalign
= GET_MODE_ALIGNMENT (xmode
);
690 if (!(xalign
> BITS_PER_UNIT
&& DECL_PACKED (decl
))
691 && (known_align
== 0 || known_align
>= xalign
))
693 SET_DECL_ALIGN (decl
, MAX (xalign
, DECL_ALIGN (decl
)));
694 SET_DECL_MODE (decl
, xmode
);
695 DECL_BIT_FIELD (decl
) = 0;
700 /* Turn off DECL_BIT_FIELD if we won't need it set. */
701 if (TYPE_MODE (type
) == BLKmode
&& DECL_MODE (decl
) == BLKmode
702 && known_align
>= TYPE_ALIGN (type
)
703 && DECL_ALIGN (decl
) >= TYPE_ALIGN (type
))
704 DECL_BIT_FIELD (decl
) = 0;
706 else if (packed_p
&& DECL_USER_ALIGN (decl
))
707 /* Don't touch DECL_ALIGN. For other packed fields, go ahead and
708 round up; we'll reduce it again below. We want packing to
709 supersede USER_ALIGN inherited from the type, but defer to
710 alignment explicitly specified on the field decl. */;
712 do_type_align (type
, decl
);
714 /* If the field is packed and not explicitly aligned, give it the
715 minimum alignment. Note that do_type_align may set
716 DECL_USER_ALIGN, so we need to check old_user_align instead. */
719 SET_DECL_ALIGN (decl
, MIN (DECL_ALIGN (decl
), BITS_PER_UNIT
));
721 if (! packed_p
&& ! DECL_USER_ALIGN (decl
))
723 /* Some targets (i.e. i386, VMS) limit struct field alignment
724 to a lower boundary than alignment of variables unless
725 it was overridden by attribute aligned. */
726 #ifdef BIGGEST_FIELD_ALIGNMENT
727 SET_DECL_ALIGN (decl
, MIN (DECL_ALIGN (decl
),
728 (unsigned) BIGGEST_FIELD_ALIGNMENT
));
730 #ifdef ADJUST_FIELD_ALIGN
731 SET_DECL_ALIGN (decl
, ADJUST_FIELD_ALIGN (decl
, TREE_TYPE (decl
),
737 mfa
= initial_max_fld_align
* BITS_PER_UNIT
;
739 mfa
= maximum_field_alignment
;
740 /* Should this be controlled by DECL_USER_ALIGN, too? */
742 SET_DECL_ALIGN (decl
, MIN (DECL_ALIGN (decl
), mfa
));
745 /* Evaluate nonconstant size only once, either now or as soon as safe. */
746 if (DECL_SIZE (decl
) != 0 && TREE_CODE (DECL_SIZE (decl
)) != INTEGER_CST
)
747 DECL_SIZE (decl
) = variable_size (DECL_SIZE (decl
));
748 if (DECL_SIZE_UNIT (decl
) != 0
749 && TREE_CODE (DECL_SIZE_UNIT (decl
)) != INTEGER_CST
)
750 DECL_SIZE_UNIT (decl
) = variable_size (DECL_SIZE_UNIT (decl
));
752 /* If requested, warn about definitions of large data objects. */
754 && (code
== VAR_DECL
|| code
== PARM_DECL
)
755 && ! DECL_EXTERNAL (decl
))
757 tree size
= DECL_SIZE_UNIT (decl
);
759 if (size
!= 0 && TREE_CODE (size
) == INTEGER_CST
760 && compare_tree_int (size
, larger_than_size
) > 0)
762 int size_as_int
= TREE_INT_CST_LOW (size
);
764 if (compare_tree_int (size
, size_as_int
) == 0)
765 warning (OPT_Wlarger_than_
, "size of %q+D is %d bytes", decl
, size_as_int
);
767 warning (OPT_Wlarger_than_
, "size of %q+D is larger than %wd bytes",
768 decl
, larger_than_size
);
772 /* If the RTL was already set, update its mode and mem attributes. */
775 PUT_MODE (rtl
, DECL_MODE (decl
));
776 SET_DECL_RTL (decl
, 0);
778 set_mem_attributes (rtl
, decl
, 1);
779 SET_DECL_RTL (decl
, rtl
);
783 /* Given a VAR_DECL, PARM_DECL, RESULT_DECL, or FIELD_DECL, clears the
784 results of a previous call to layout_decl and calls it again. */
787 relayout_decl (tree decl
)
789 DECL_SIZE (decl
) = DECL_SIZE_UNIT (decl
) = 0;
790 SET_DECL_MODE (decl
, VOIDmode
);
791 if (!DECL_USER_ALIGN (decl
))
792 SET_DECL_ALIGN (decl
, 0);
793 if (DECL_RTL_SET_P (decl
))
794 SET_DECL_RTL (decl
, 0);
796 layout_decl (decl
, 0);
799 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
800 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
801 is to be passed to all other layout functions for this record. It is the
802 responsibility of the caller to call `free' for the storage returned.
803 Note that garbage collection is not permitted until we finish laying
807 start_record_layout (tree t
)
809 record_layout_info rli
= XNEW (struct record_layout_info_s
);
813 /* If the type has a minimum specified alignment (via an attribute
814 declaration, for example) use it -- otherwise, start with a
815 one-byte alignment. */
816 rli
->record_align
= MAX (BITS_PER_UNIT
, TYPE_ALIGN (t
));
817 rli
->unpacked_align
= rli
->record_align
;
818 rli
->offset_align
= MAX (rli
->record_align
, BIGGEST_ALIGNMENT
);
820 #ifdef STRUCTURE_SIZE_BOUNDARY
821 /* Packed structures don't need to have minimum size. */
822 if (! TYPE_PACKED (t
))
826 /* #pragma pack overrides STRUCTURE_SIZE_BOUNDARY. */
827 tmp
= (unsigned) STRUCTURE_SIZE_BOUNDARY
;
828 if (maximum_field_alignment
!= 0)
829 tmp
= MIN (tmp
, maximum_field_alignment
);
830 rli
->record_align
= MAX (rli
->record_align
, tmp
);
834 rli
->offset
= size_zero_node
;
835 rli
->bitpos
= bitsize_zero_node
;
837 rli
->pending_statics
= 0;
838 rli
->packed_maybe_necessary
= 0;
839 rli
->remaining_in_alignment
= 0;
844 /* Fold sizetype value X to bitsizetype, given that X represents a type
848 bits_from_bytes (tree x
)
850 if (POLY_INT_CST_P (x
))
851 /* The runtime calculation isn't allowed to overflow sizetype;
852 increasing the runtime values must always increase the size
853 or offset of the object. This means that the object imposes
854 a maximum value on the runtime parameters, but we don't record
856 return build_poly_int_cst
858 poly_wide_int::from (poly_int_cst_value (x
),
859 TYPE_PRECISION (bitsizetype
),
860 TYPE_SIGN (TREE_TYPE (x
))));
861 x
= fold_convert (bitsizetype
, x
);
862 gcc_checking_assert (x
);
866 /* Return the combined bit position for the byte offset OFFSET and the
869 These functions operate on byte and bit positions present in FIELD_DECLs
870 and assume that these expressions result in no (intermediate) overflow.
871 This assumption is necessary to fold the expressions as much as possible,
872 so as to avoid creating artificially variable-sized types in languages
873 supporting variable-sized types like Ada. */
876 bit_from_pos (tree offset
, tree bitpos
)
878 return size_binop (PLUS_EXPR
, bitpos
,
879 size_binop (MULT_EXPR
, bits_from_bytes (offset
),
883 /* Return the combined truncated byte position for the byte offset OFFSET and
884 the bit position BITPOS. */
887 byte_from_pos (tree offset
, tree bitpos
)
890 if (TREE_CODE (bitpos
) == MULT_EXPR
891 && tree_int_cst_equal (TREE_OPERAND (bitpos
, 1), bitsize_unit_node
))
892 bytepos
= TREE_OPERAND (bitpos
, 0);
894 bytepos
= size_binop (TRUNC_DIV_EXPR
, bitpos
, bitsize_unit_node
);
895 return size_binop (PLUS_EXPR
, offset
, fold_convert (sizetype
, bytepos
));
898 /* Split the bit position POS into a byte offset *POFFSET and a bit
899 position *PBITPOS with the byte offset aligned to OFF_ALIGN bits. */
902 pos_from_bit (tree
*poffset
, tree
*pbitpos
, unsigned int off_align
,
905 tree toff_align
= bitsize_int (off_align
);
906 if (TREE_CODE (pos
) == MULT_EXPR
907 && tree_int_cst_equal (TREE_OPERAND (pos
, 1), toff_align
))
909 *poffset
= size_binop (MULT_EXPR
,
910 fold_convert (sizetype
, TREE_OPERAND (pos
, 0)),
911 size_int (off_align
/ BITS_PER_UNIT
));
912 *pbitpos
= bitsize_zero_node
;
916 *poffset
= size_binop (MULT_EXPR
,
917 fold_convert (sizetype
,
918 size_binop (FLOOR_DIV_EXPR
, pos
,
920 size_int (off_align
/ BITS_PER_UNIT
));
921 *pbitpos
= size_binop (FLOOR_MOD_EXPR
, pos
, toff_align
);
925 /* Given a pointer to bit and byte offsets and an offset alignment,
926 normalize the offsets so they are within the alignment. */
929 normalize_offset (tree
*poffset
, tree
*pbitpos
, unsigned int off_align
)
931 /* If the bit position is now larger than it should be, adjust it
933 if (compare_tree_int (*pbitpos
, off_align
) >= 0)
936 pos_from_bit (&offset
, &bitpos
, off_align
, *pbitpos
);
937 *poffset
= size_binop (PLUS_EXPR
, *poffset
, offset
);
942 /* Print debugging information about the information in RLI. */
945 debug_rli (record_layout_info rli
)
947 print_node_brief (stderr
, "type", rli
->t
, 0);
948 print_node_brief (stderr
, "\noffset", rli
->offset
, 0);
949 print_node_brief (stderr
, " bitpos", rli
->bitpos
, 0);
951 fprintf (stderr
, "\naligns: rec = %u, unpack = %u, off = %u\n",
952 rli
->record_align
, rli
->unpacked_align
,
955 /* The ms_struct code is the only that uses this. */
956 if (targetm
.ms_bitfield_layout_p (rli
->t
))
957 fprintf (stderr
, "remaining in alignment = %u\n", rli
->remaining_in_alignment
);
959 if (rli
->packed_maybe_necessary
)
960 fprintf (stderr
, "packed may be necessary\n");
962 if (!vec_safe_is_empty (rli
->pending_statics
))
964 fprintf (stderr
, "pending statics:\n");
965 debug (rli
->pending_statics
);
969 /* Given an RLI with a possibly-incremented BITPOS, adjust OFFSET and
970 BITPOS if necessary to keep BITPOS below OFFSET_ALIGN. */
973 normalize_rli (record_layout_info rli
)
975 normalize_offset (&rli
->offset
, &rli
->bitpos
, rli
->offset_align
);
978 /* Returns the size in bytes allocated so far. */
981 rli_size_unit_so_far (record_layout_info rli
)
983 return byte_from_pos (rli
->offset
, rli
->bitpos
);
986 /* Returns the size in bits allocated so far. */
989 rli_size_so_far (record_layout_info rli
)
991 return bit_from_pos (rli
->offset
, rli
->bitpos
);
994 /* FIELD is about to be added to RLI->T. The alignment (in bits) of
995 the next available location within the record is given by KNOWN_ALIGN.
996 Update the variable alignment fields in RLI, and return the alignment
997 to give the FIELD. */
1000 update_alignment_for_field (record_layout_info rli
, tree field
,
1001 unsigned int known_align
)
1003 /* The alignment required for FIELD. */
1004 unsigned int desired_align
;
1005 /* The type of this field. */
1006 tree type
= TREE_TYPE (field
);
1007 /* True if the field was explicitly aligned by the user. */
1011 /* Do not attempt to align an ERROR_MARK node */
1012 if (TREE_CODE (type
) == ERROR_MARK
)
1015 /* Lay out the field so we know what alignment it needs. */
1016 layout_decl (field
, known_align
);
1017 desired_align
= DECL_ALIGN (field
);
1018 user_align
= DECL_USER_ALIGN (field
);
1020 is_bitfield
= (type
!= error_mark_node
1021 && DECL_BIT_FIELD_TYPE (field
)
1022 && ! integer_zerop (TYPE_SIZE (type
)));
1024 /* Record must have at least as much alignment as any field.
1025 Otherwise, the alignment of the field within the record is
1027 if (targetm
.ms_bitfield_layout_p (rli
->t
))
1029 /* Here, the alignment of the underlying type of a bitfield can
1030 affect the alignment of a record; even a zero-sized field
1031 can do this. The alignment should be to the alignment of
1032 the type, except that for zero-size bitfields this only
1033 applies if there was an immediately prior, nonzero-size
1034 bitfield. (That's the way it is, experimentally.) */
1035 if ((!is_bitfield
&& !DECL_PACKED (field
))
1036 || ((DECL_SIZE (field
) == NULL_TREE
1037 || !integer_zerop (DECL_SIZE (field
)))
1038 ? !DECL_PACKED (field
)
1040 && DECL_BIT_FIELD_TYPE (rli
->prev_field
)
1041 && ! integer_zerop (DECL_SIZE (rli
->prev_field
)))))
1043 unsigned int type_align
= TYPE_ALIGN (type
);
1044 type_align
= MAX (type_align
, desired_align
);
1045 if (maximum_field_alignment
!= 0)
1046 type_align
= MIN (type_align
, maximum_field_alignment
);
1047 rli
->record_align
= MAX (rli
->record_align
, type_align
);
1048 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
1051 else if (is_bitfield
&& PCC_BITFIELD_TYPE_MATTERS
)
1053 /* Named bit-fields cause the entire structure to have the
1054 alignment implied by their type. Some targets also apply the same
1055 rules to unnamed bitfields. */
1056 if (DECL_NAME (field
) != 0
1057 || targetm
.align_anon_bitfield ())
1059 unsigned int type_align
= TYPE_ALIGN (type
);
1061 #ifdef ADJUST_FIELD_ALIGN
1062 if (! TYPE_USER_ALIGN (type
))
1063 type_align
= ADJUST_FIELD_ALIGN (field
, type
, type_align
);
1066 /* Targets might chose to handle unnamed and hence possibly
1067 zero-width bitfield. Those are not influenced by #pragmas
1068 or packed attributes. */
1069 if (integer_zerop (DECL_SIZE (field
)))
1071 if (initial_max_fld_align
)
1072 type_align
= MIN (type_align
,
1073 initial_max_fld_align
* BITS_PER_UNIT
);
1075 else if (maximum_field_alignment
!= 0)
1076 type_align
= MIN (type_align
, maximum_field_alignment
);
1077 else if (DECL_PACKED (field
))
1078 type_align
= MIN (type_align
, BITS_PER_UNIT
);
1080 /* The alignment of the record is increased to the maximum
1081 of the current alignment, the alignment indicated on the
1082 field (i.e., the alignment specified by an __aligned__
1083 attribute), and the alignment indicated by the type of
1085 rli
->record_align
= MAX (rli
->record_align
, desired_align
);
1086 rli
->record_align
= MAX (rli
->record_align
, type_align
);
1089 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
1090 user_align
|= TYPE_USER_ALIGN (type
);
1095 rli
->record_align
= MAX (rli
->record_align
, desired_align
);
1096 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
1099 TYPE_USER_ALIGN (rli
->t
) |= user_align
;
1101 return desired_align
;
1104 /* Issue a warning if the record alignment, RECORD_ALIGN, is less than
1105 the field alignment of FIELD or FIELD isn't aligned. */
1108 handle_warn_if_not_align (tree field
, unsigned int record_align
)
1110 tree type
= TREE_TYPE (field
);
1112 if (type
== error_mark_node
)
1115 unsigned int warn_if_not_align
= 0;
1119 if (warn_if_not_aligned
)
1121 warn_if_not_align
= DECL_WARN_IF_NOT_ALIGN (field
);
1122 if (!warn_if_not_align
)
1123 warn_if_not_align
= TYPE_WARN_IF_NOT_ALIGN (type
);
1124 if (warn_if_not_align
)
1125 opt_w
= OPT_Wif_not_aligned
;
1128 if (!warn_if_not_align
1129 && warn_packed_not_aligned
1130 && lookup_attribute ("aligned", TYPE_ATTRIBUTES (type
)))
1132 warn_if_not_align
= TYPE_ALIGN (type
);
1133 opt_w
= OPT_Wpacked_not_aligned
;
1136 if (!warn_if_not_align
)
1139 tree context
= DECL_CONTEXT (field
);
1141 warn_if_not_align
/= BITS_PER_UNIT
;
1142 record_align
/= BITS_PER_UNIT
;
1143 if ((record_align
% warn_if_not_align
) != 0)
1144 warning (opt_w
, "alignment %u of %qT is less than %u",
1145 record_align
, context
, warn_if_not_align
);
1147 unsigned HOST_WIDE_INT off
1148 = (tree_to_uhwi (DECL_FIELD_OFFSET (field
))
1149 + tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field
)) / BITS_PER_UNIT
);
1150 if ((off
% warn_if_not_align
) != 0)
1151 warning (opt_w
, "%q+D offset %wu in %qT isn't aligned to %u",
1152 field
, off
, context
, warn_if_not_align
);
1155 /* Called from place_field to handle unions. */
1158 place_union_field (record_layout_info rli
, tree field
)
1160 update_alignment_for_field (rli
, field
, /*known_align=*/0);
1162 DECL_FIELD_OFFSET (field
) = size_zero_node
;
1163 DECL_FIELD_BIT_OFFSET (field
) = bitsize_zero_node
;
1164 SET_DECL_OFFSET_ALIGN (field
, BIGGEST_ALIGNMENT
);
1165 handle_warn_if_not_align (field
, rli
->record_align
);
1167 /* If this is an ERROR_MARK return *after* having set the
1168 field at the start of the union. This helps when parsing
1170 if (TREE_CODE (TREE_TYPE (field
)) == ERROR_MARK
)
1173 if (AGGREGATE_TYPE_P (TREE_TYPE (field
))
1174 && TYPE_TYPELESS_STORAGE (TREE_TYPE (field
)))
1175 TYPE_TYPELESS_STORAGE (rli
->t
) = 1;
1177 /* We assume the union's size will be a multiple of a byte so we don't
1178 bother with BITPOS. */
1179 if (TREE_CODE (rli
->t
) == UNION_TYPE
)
1180 rli
->offset
= size_binop (MAX_EXPR
, rli
->offset
, DECL_SIZE_UNIT (field
));
1181 else if (TREE_CODE (rli
->t
) == QUAL_UNION_TYPE
)
1182 rli
->offset
= fold_build3 (COND_EXPR
, sizetype
, DECL_QUALIFIER (field
),
1183 DECL_SIZE_UNIT (field
), rli
->offset
);
1186 /* A bitfield of SIZE with a required access alignment of ALIGN is allocated
1187 at BYTE_OFFSET / BIT_OFFSET. Return nonzero if the field would span more
1188 units of alignment than the underlying TYPE. */
1190 excess_unit_span (HOST_WIDE_INT byte_offset
, HOST_WIDE_INT bit_offset
,
1191 HOST_WIDE_INT size
, HOST_WIDE_INT align
, tree type
)
1193 /* Note that the calculation of OFFSET might overflow; we calculate it so
1194 that we still get the right result as long as ALIGN is a power of two. */
1195 unsigned HOST_WIDE_INT offset
= byte_offset
* BITS_PER_UNIT
+ bit_offset
;
1197 offset
= offset
% align
;
1198 return ((offset
+ size
+ align
- 1) / align
1199 > tree_to_uhwi (TYPE_SIZE (type
)) / align
);
1202 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
1203 is a FIELD_DECL to be added after those fields already present in
1204 T. (FIELD is not actually added to the TYPE_FIELDS list here;
1205 callers that desire that behavior must manually perform that step.) */
1208 place_field (record_layout_info rli
, tree field
)
1210 /* The alignment required for FIELD. */
1211 unsigned int desired_align
;
1212 /* The alignment FIELD would have if we just dropped it into the
1213 record as it presently stands. */
1214 unsigned int known_align
;
1215 unsigned int actual_align
;
1216 /* The type of this field. */
1217 tree type
= TREE_TYPE (field
);
1219 gcc_assert (TREE_CODE (field
) != ERROR_MARK
);
1221 /* If FIELD is static, then treat it like a separate variable, not
1222 really like a structure field. If it is a FUNCTION_DECL, it's a
1223 method. In both cases, all we do is lay out the decl, and we do
1224 it *after* the record is laid out. */
1227 vec_safe_push (rli
->pending_statics
, field
);
1231 /* Enumerators and enum types which are local to this class need not
1232 be laid out. Likewise for initialized constant fields. */
1233 else if (TREE_CODE (field
) != FIELD_DECL
)
1236 /* Unions are laid out very differently than records, so split
1237 that code off to another function. */
1238 else if (TREE_CODE (rli
->t
) != RECORD_TYPE
)
1240 place_union_field (rli
, field
);
1244 else if (TREE_CODE (type
) == ERROR_MARK
)
1246 /* Place this field at the current allocation position, so we
1247 maintain monotonicity. */
1248 DECL_FIELD_OFFSET (field
) = rli
->offset
;
1249 DECL_FIELD_BIT_OFFSET (field
) = rli
->bitpos
;
1250 SET_DECL_OFFSET_ALIGN (field
, rli
->offset_align
);
1251 handle_warn_if_not_align (field
, rli
->record_align
);
1255 if (AGGREGATE_TYPE_P (type
)
1256 && TYPE_TYPELESS_STORAGE (type
))
1257 TYPE_TYPELESS_STORAGE (rli
->t
) = 1;
1259 /* Work out the known alignment so far. Note that A & (-A) is the
1260 value of the least-significant bit in A that is one. */
1261 if (! integer_zerop (rli
->bitpos
))
1262 known_align
= least_bit_hwi (tree_to_uhwi (rli
->bitpos
));
1263 else if (integer_zerop (rli
->offset
))
1265 else if (tree_fits_uhwi_p (rli
->offset
))
1266 known_align
= (BITS_PER_UNIT
1267 * least_bit_hwi (tree_to_uhwi (rli
->offset
)));
1269 known_align
= rli
->offset_align
;
1271 desired_align
= update_alignment_for_field (rli
, field
, known_align
);
1272 if (known_align
== 0)
1273 known_align
= MAX (BIGGEST_ALIGNMENT
, rli
->record_align
);
1275 if (warn_packed
&& DECL_PACKED (field
))
1277 if (known_align
>= TYPE_ALIGN (type
))
1279 if (TYPE_ALIGN (type
) > desired_align
)
1281 if (STRICT_ALIGNMENT
)
1282 warning (OPT_Wattributes
, "packed attribute causes "
1283 "inefficient alignment for %q+D", field
);
1284 /* Don't warn if DECL_PACKED was set by the type. */
1285 else if (!TYPE_PACKED (rli
->t
))
1286 warning (OPT_Wattributes
, "packed attribute is "
1287 "unnecessary for %q+D", field
);
1291 rli
->packed_maybe_necessary
= 1;
1294 /* Does this field automatically have alignment it needs by virtue
1295 of the fields that precede it and the record's own alignment? */
1296 if (known_align
< desired_align
)
1298 /* No, we need to skip space before this field.
1299 Bump the cumulative size to multiple of field alignment. */
1301 if (!targetm
.ms_bitfield_layout_p (rli
->t
)
1302 && DECL_SOURCE_LOCATION (field
) != BUILTINS_LOCATION
)
1303 warning (OPT_Wpadded
, "padding struct to align %q+D", field
);
1305 /* If the alignment is still within offset_align, just align
1306 the bit position. */
1307 if (desired_align
< rli
->offset_align
)
1308 rli
->bitpos
= round_up (rli
->bitpos
, desired_align
);
1311 /* First adjust OFFSET by the partial bits, then align. */
1313 = size_binop (PLUS_EXPR
, rli
->offset
,
1314 fold_convert (sizetype
,
1315 size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
1316 bitsize_unit_node
)));
1317 rli
->bitpos
= bitsize_zero_node
;
1319 rli
->offset
= round_up (rli
->offset
, desired_align
/ BITS_PER_UNIT
);
1322 if (! TREE_CONSTANT (rli
->offset
))
1323 rli
->offset_align
= desired_align
;
1324 if (targetm
.ms_bitfield_layout_p (rli
->t
))
1325 rli
->prev_field
= NULL
;
1328 /* Handle compatibility with PCC. Note that if the record has any
1329 variable-sized fields, we need not worry about compatibility. */
1330 if (PCC_BITFIELD_TYPE_MATTERS
1331 && ! targetm
.ms_bitfield_layout_p (rli
->t
)
1332 && TREE_CODE (field
) == FIELD_DECL
1333 && type
!= error_mark_node
1334 && DECL_BIT_FIELD (field
)
1335 && (! DECL_PACKED (field
)
1336 /* Enter for these packed fields only to issue a warning. */
1337 || TYPE_ALIGN (type
) <= BITS_PER_UNIT
)
1338 && maximum_field_alignment
== 0
1339 && ! integer_zerop (DECL_SIZE (field
))
1340 && tree_fits_uhwi_p (DECL_SIZE (field
))
1341 && tree_fits_uhwi_p (rli
->offset
)
1342 && tree_fits_uhwi_p (TYPE_SIZE (type
)))
1344 unsigned int type_align
= TYPE_ALIGN (type
);
1345 tree dsize
= DECL_SIZE (field
);
1346 HOST_WIDE_INT field_size
= tree_to_uhwi (dsize
);
1347 HOST_WIDE_INT offset
= tree_to_uhwi (rli
->offset
);
1348 HOST_WIDE_INT bit_offset
= tree_to_shwi (rli
->bitpos
);
1350 #ifdef ADJUST_FIELD_ALIGN
1351 if (! TYPE_USER_ALIGN (type
))
1352 type_align
= ADJUST_FIELD_ALIGN (field
, type
, type_align
);
1355 /* A bit field may not span more units of alignment of its type
1356 than its type itself. Advance to next boundary if necessary. */
1357 if (excess_unit_span (offset
, bit_offset
, field_size
, type_align
, type
))
1359 if (DECL_PACKED (field
))
1361 if (warn_packed_bitfield_compat
== 1)
1364 "offset of packed bit-field %qD has changed in GCC 4.4",
1368 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1371 if (! DECL_PACKED (field
))
1372 TYPE_USER_ALIGN (rli
->t
) |= TYPE_USER_ALIGN (type
);
1374 SET_TYPE_WARN_IF_NOT_ALIGN (rli
->t
,
1375 TYPE_WARN_IF_NOT_ALIGN (type
));
1378 #ifdef BITFIELD_NBYTES_LIMITED
1379 if (BITFIELD_NBYTES_LIMITED
1380 && ! targetm
.ms_bitfield_layout_p (rli
->t
)
1381 && TREE_CODE (field
) == FIELD_DECL
1382 && type
!= error_mark_node
1383 && DECL_BIT_FIELD_TYPE (field
)
1384 && ! DECL_PACKED (field
)
1385 && ! integer_zerop (DECL_SIZE (field
))
1386 && tree_fits_uhwi_p (DECL_SIZE (field
))
1387 && tree_fits_uhwi_p (rli
->offset
)
1388 && tree_fits_uhwi_p (TYPE_SIZE (type
)))
1390 unsigned int type_align
= TYPE_ALIGN (type
);
1391 tree dsize
= DECL_SIZE (field
);
1392 HOST_WIDE_INT field_size
= tree_to_uhwi (dsize
);
1393 HOST_WIDE_INT offset
= tree_to_uhwi (rli
->offset
);
1394 HOST_WIDE_INT bit_offset
= tree_to_shwi (rli
->bitpos
);
1396 #ifdef ADJUST_FIELD_ALIGN
1397 if (! TYPE_USER_ALIGN (type
))
1398 type_align
= ADJUST_FIELD_ALIGN (field
, type
, type_align
);
1401 if (maximum_field_alignment
!= 0)
1402 type_align
= MIN (type_align
, maximum_field_alignment
);
1403 /* ??? This test is opposite the test in the containing if
1404 statement, so this code is unreachable currently. */
1405 else if (DECL_PACKED (field
))
1406 type_align
= MIN (type_align
, BITS_PER_UNIT
);
1408 /* A bit field may not span the unit of alignment of its type.
1409 Advance to next boundary if necessary. */
1410 if (excess_unit_span (offset
, bit_offset
, field_size
, type_align
, type
))
1411 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1413 TYPE_USER_ALIGN (rli
->t
) |= TYPE_USER_ALIGN (type
);
1414 SET_TYPE_WARN_IF_NOT_ALIGN (rli
->t
,
1415 TYPE_WARN_IF_NOT_ALIGN (type
));
1419 /* See the docs for TARGET_MS_BITFIELD_LAYOUT_P for details.
1421 When a bit field is inserted into a packed record, the whole
1422 size of the underlying type is used by one or more same-size
1423 adjacent bitfields. (That is, if its long:3, 32 bits is
1424 used in the record, and any additional adjacent long bitfields are
1425 packed into the same chunk of 32 bits. However, if the size
1426 changes, a new field of that size is allocated.) In an unpacked
1427 record, this is the same as using alignment, but not equivalent
1430 Note: for compatibility, we use the type size, not the type alignment
1431 to determine alignment, since that matches the documentation */
1433 if (targetm
.ms_bitfield_layout_p (rli
->t
))
1435 tree prev_saved
= rli
->prev_field
;
1436 tree prev_type
= prev_saved
? DECL_BIT_FIELD_TYPE (prev_saved
) : NULL
;
1438 /* This is a bitfield if it exists. */
1439 if (rli
->prev_field
)
1441 /* If both are bitfields, nonzero, and the same size, this is
1442 the middle of a run. Zero declared size fields are special
1443 and handled as "end of run". (Note: it's nonzero declared
1444 size, but equal type sizes!) (Since we know that both
1445 the current and previous fields are bitfields by the
1446 time we check it, DECL_SIZE must be present for both.) */
1447 if (DECL_BIT_FIELD_TYPE (field
)
1448 && !integer_zerop (DECL_SIZE (field
))
1449 && !integer_zerop (DECL_SIZE (rli
->prev_field
))
1450 && tree_fits_shwi_p (DECL_SIZE (rli
->prev_field
))
1451 && tree_fits_uhwi_p (TYPE_SIZE (type
))
1452 && simple_cst_equal (TYPE_SIZE (type
), TYPE_SIZE (prev_type
)))
1454 /* We're in the middle of a run of equal type size fields; make
1455 sure we realign if we run out of bits. (Not decl size,
1457 HOST_WIDE_INT bitsize
= tree_to_uhwi (DECL_SIZE (field
));
1459 if (rli
->remaining_in_alignment
< bitsize
)
1461 HOST_WIDE_INT typesize
= tree_to_uhwi (TYPE_SIZE (type
));
1463 /* out of bits; bump up to next 'word'. */
1465 = size_binop (PLUS_EXPR
, rli
->bitpos
,
1466 bitsize_int (rli
->remaining_in_alignment
));
1467 rli
->prev_field
= field
;
1468 if (typesize
< bitsize
)
1469 rli
->remaining_in_alignment
= 0;
1471 rli
->remaining_in_alignment
= typesize
- bitsize
;
1474 rli
->remaining_in_alignment
-= bitsize
;
1478 /* End of a run: if leaving a run of bitfields of the same type
1479 size, we have to "use up" the rest of the bits of the type
1482 Compute the new position as the sum of the size for the prior
1483 type and where we first started working on that type.
1484 Note: since the beginning of the field was aligned then
1485 of course the end will be too. No round needed. */
1487 if (!integer_zerop (DECL_SIZE (rli
->prev_field
)))
1490 = size_binop (PLUS_EXPR
, rli
->bitpos
,
1491 bitsize_int (rli
->remaining_in_alignment
));
1494 /* We "use up" size zero fields; the code below should behave
1495 as if the prior field was not a bitfield. */
1498 /* Cause a new bitfield to be captured, either this time (if
1499 currently a bitfield) or next time we see one. */
1500 if (!DECL_BIT_FIELD_TYPE (field
)
1501 || integer_zerop (DECL_SIZE (field
)))
1502 rli
->prev_field
= NULL
;
1505 normalize_rli (rli
);
1508 /* If we're starting a new run of same type size bitfields
1509 (or a run of non-bitfields), set up the "first of the run"
1512 That is, if the current field is not a bitfield, or if there
1513 was a prior bitfield the type sizes differ, or if there wasn't
1514 a prior bitfield the size of the current field is nonzero.
1516 Note: we must be sure to test ONLY the type size if there was
1517 a prior bitfield and ONLY for the current field being zero if
1520 if (!DECL_BIT_FIELD_TYPE (field
)
1521 || (prev_saved
!= NULL
1522 ? !simple_cst_equal (TYPE_SIZE (type
), TYPE_SIZE (prev_type
))
1523 : !integer_zerop (DECL_SIZE (field
)) ))
1525 /* Never smaller than a byte for compatibility. */
1526 unsigned int type_align
= BITS_PER_UNIT
;
1528 /* (When not a bitfield), we could be seeing a flex array (with
1529 no DECL_SIZE). Since we won't be using remaining_in_alignment
1530 until we see a bitfield (and come by here again) we just skip
1532 if (DECL_SIZE (field
) != NULL
1533 && tree_fits_uhwi_p (TYPE_SIZE (TREE_TYPE (field
)))
1534 && tree_fits_uhwi_p (DECL_SIZE (field
)))
1536 unsigned HOST_WIDE_INT bitsize
1537 = tree_to_uhwi (DECL_SIZE (field
));
1538 unsigned HOST_WIDE_INT typesize
1539 = tree_to_uhwi (TYPE_SIZE (TREE_TYPE (field
)));
1541 if (typesize
< bitsize
)
1542 rli
->remaining_in_alignment
= 0;
1544 rli
->remaining_in_alignment
= typesize
- bitsize
;
1547 /* Now align (conventionally) for the new type. */
1548 type_align
= TYPE_ALIGN (TREE_TYPE (field
));
1550 if (maximum_field_alignment
!= 0)
1551 type_align
= MIN (type_align
, maximum_field_alignment
);
1553 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1555 /* If we really aligned, don't allow subsequent bitfields
1557 rli
->prev_field
= NULL
;
1561 /* Offset so far becomes the position of this field after normalizing. */
1562 normalize_rli (rli
);
1563 DECL_FIELD_OFFSET (field
) = rli
->offset
;
1564 DECL_FIELD_BIT_OFFSET (field
) = rli
->bitpos
;
1565 SET_DECL_OFFSET_ALIGN (field
, rli
->offset_align
);
1566 handle_warn_if_not_align (field
, rli
->record_align
);
1568 /* Evaluate nonconstant offsets only once, either now or as soon as safe. */
1569 if (TREE_CODE (DECL_FIELD_OFFSET (field
)) != INTEGER_CST
)
1570 DECL_FIELD_OFFSET (field
) = variable_size (DECL_FIELD_OFFSET (field
));
1572 /* If this field ended up more aligned than we thought it would be (we
1573 approximate this by seeing if its position changed), lay out the field
1574 again; perhaps we can use an integral mode for it now. */
1575 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field
)))
1576 actual_align
= least_bit_hwi (tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field
)));
1577 else if (integer_zerop (DECL_FIELD_OFFSET (field
)))
1578 actual_align
= MAX (BIGGEST_ALIGNMENT
, rli
->record_align
);
1579 else if (tree_fits_uhwi_p (DECL_FIELD_OFFSET (field
)))
1580 actual_align
= (BITS_PER_UNIT
1581 * least_bit_hwi (tree_to_uhwi (DECL_FIELD_OFFSET (field
))));
1583 actual_align
= DECL_OFFSET_ALIGN (field
);
1584 /* ACTUAL_ALIGN is still the actual alignment *within the record* .
1585 store / extract bit field operations will check the alignment of the
1586 record against the mode of bit fields. */
1588 if (known_align
!= actual_align
)
1589 layout_decl (field
, actual_align
);
1591 if (rli
->prev_field
== NULL
&& DECL_BIT_FIELD_TYPE (field
))
1592 rli
->prev_field
= field
;
1594 /* Now add size of this field to the size of the record. If the size is
1595 not constant, treat the field as being a multiple of bytes and just
1596 adjust the offset, resetting the bit position. Otherwise, apportion the
1597 size amongst the bit position and offset. First handle the case of an
1598 unspecified size, which can happen when we have an invalid nested struct
1599 definition, such as struct j { struct j { int i; } }. The error message
1600 is printed in finish_struct. */
1601 if (DECL_SIZE (field
) == 0)
1603 else if (TREE_CODE (DECL_SIZE (field
)) != INTEGER_CST
1604 || TREE_OVERFLOW (DECL_SIZE (field
)))
1607 = size_binop (PLUS_EXPR
, rli
->offset
,
1608 fold_convert (sizetype
,
1609 size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
1610 bitsize_unit_node
)));
1612 = size_binop (PLUS_EXPR
, rli
->offset
, DECL_SIZE_UNIT (field
));
1613 rli
->bitpos
= bitsize_zero_node
;
1614 rli
->offset_align
= MIN (rli
->offset_align
, desired_align
);
1616 else if (targetm
.ms_bitfield_layout_p (rli
->t
))
1618 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
, DECL_SIZE (field
));
1620 /* If we ended a bitfield before the full length of the type then
1621 pad the struct out to the full length of the last type. */
1622 if ((DECL_CHAIN (field
) == NULL
1623 || TREE_CODE (DECL_CHAIN (field
)) != FIELD_DECL
)
1624 && DECL_BIT_FIELD_TYPE (field
)
1625 && !integer_zerop (DECL_SIZE (field
)))
1626 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
,
1627 bitsize_int (rli
->remaining_in_alignment
));
1629 normalize_rli (rli
);
1633 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
, DECL_SIZE (field
));
1634 normalize_rli (rli
);
1638 /* Assuming that all the fields have been laid out, this function uses
1639 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
1640 indicated by RLI. */
1643 finalize_record_size (record_layout_info rli
)
1645 tree unpadded_size
, unpadded_size_unit
;
1647 /* Now we want just byte and bit offsets, so set the offset alignment
1648 to be a byte and then normalize. */
1649 rli
->offset_align
= BITS_PER_UNIT
;
1650 normalize_rli (rli
);
1652 /* Determine the desired alignment. */
1653 #ifdef ROUND_TYPE_ALIGN
1654 SET_TYPE_ALIGN (rli
->t
, ROUND_TYPE_ALIGN (rli
->t
, TYPE_ALIGN (rli
->t
),
1655 rli
->record_align
));
1657 SET_TYPE_ALIGN (rli
->t
, MAX (TYPE_ALIGN (rli
->t
), rli
->record_align
));
1660 /* Compute the size so far. Be sure to allow for extra bits in the
1661 size in bytes. We have guaranteed above that it will be no more
1662 than a single byte. */
1663 unpadded_size
= rli_size_so_far (rli
);
1664 unpadded_size_unit
= rli_size_unit_so_far (rli
);
1665 if (! integer_zerop (rli
->bitpos
))
1667 = size_binop (PLUS_EXPR
, unpadded_size_unit
, size_one_node
);
1669 /* Round the size up to be a multiple of the required alignment. */
1670 TYPE_SIZE (rli
->t
) = round_up (unpadded_size
, TYPE_ALIGN (rli
->t
));
1671 TYPE_SIZE_UNIT (rli
->t
)
1672 = round_up (unpadded_size_unit
, TYPE_ALIGN_UNIT (rli
->t
));
1674 if (TREE_CONSTANT (unpadded_size
)
1675 && simple_cst_equal (unpadded_size
, TYPE_SIZE (rli
->t
)) == 0
1676 && input_location
!= BUILTINS_LOCATION
)
1677 warning (OPT_Wpadded
, "padding struct size to alignment boundary");
1679 if (warn_packed
&& TREE_CODE (rli
->t
) == RECORD_TYPE
1680 && TYPE_PACKED (rli
->t
) && ! rli
->packed_maybe_necessary
1681 && TREE_CONSTANT (unpadded_size
))
1685 #ifdef ROUND_TYPE_ALIGN
1687 = ROUND_TYPE_ALIGN (rli
->t
, TYPE_ALIGN (rli
->t
), rli
->unpacked_align
);
1689 rli
->unpacked_align
= MAX (TYPE_ALIGN (rli
->t
), rli
->unpacked_align
);
1692 unpacked_size
= round_up (TYPE_SIZE (rli
->t
), rli
->unpacked_align
);
1693 if (simple_cst_equal (unpacked_size
, TYPE_SIZE (rli
->t
)))
1695 if (TYPE_NAME (rli
->t
))
1699 if (TREE_CODE (TYPE_NAME (rli
->t
)) == IDENTIFIER_NODE
)
1700 name
= TYPE_NAME (rli
->t
);
1702 name
= DECL_NAME (TYPE_NAME (rli
->t
));
1704 if (STRICT_ALIGNMENT
)
1705 warning (OPT_Wpacked
, "packed attribute causes inefficient "
1706 "alignment for %qE", name
);
1708 warning (OPT_Wpacked
,
1709 "packed attribute is unnecessary for %qE", name
);
1713 if (STRICT_ALIGNMENT
)
1714 warning (OPT_Wpacked
,
1715 "packed attribute causes inefficient alignment");
1717 warning (OPT_Wpacked
, "packed attribute is unnecessary");
1723 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
1726 compute_record_mode (tree type
)
1729 machine_mode mode
= VOIDmode
;
1731 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
1732 However, if possible, we use a mode that fits in a register
1733 instead, in order to allow for better optimization down the
1735 SET_TYPE_MODE (type
, BLKmode
);
1737 if (! tree_fits_uhwi_p (TYPE_SIZE (type
)))
1740 /* A record which has any BLKmode members must itself be
1741 BLKmode; it can't go in a register. Unless the member is
1742 BLKmode only because it isn't aligned. */
1743 for (field
= TYPE_FIELDS (type
); field
; field
= DECL_CHAIN (field
))
1745 if (TREE_CODE (field
) != FIELD_DECL
)
1748 if (TREE_CODE (TREE_TYPE (field
)) == ERROR_MARK
1749 || (TYPE_MODE (TREE_TYPE (field
)) == BLKmode
1750 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field
))
1751 && !(TYPE_SIZE (TREE_TYPE (field
)) != 0
1752 && integer_zerop (TYPE_SIZE (TREE_TYPE (field
)))))
1753 || ! tree_fits_uhwi_p (bit_position (field
))
1754 || DECL_SIZE (field
) == 0
1755 || ! tree_fits_uhwi_p (DECL_SIZE (field
)))
1758 /* If this field is the whole struct, remember its mode so
1759 that, say, we can put a double in a class into a DF
1760 register instead of forcing it to live in the stack. */
1761 if (simple_cst_equal (TYPE_SIZE (type
), DECL_SIZE (field
)))
1762 mode
= DECL_MODE (field
);
1764 /* With some targets, it is sub-optimal to access an aligned
1765 BLKmode structure as a scalar. */
1766 if (targetm
.member_type_forces_blk (field
, mode
))
1770 /* If we only have one real field; use its mode if that mode's size
1771 matches the type's size. This only applies to RECORD_TYPE. This
1772 does not apply to unions. */
1773 if (TREE_CODE (type
) == RECORD_TYPE
&& mode
!= VOIDmode
1774 && tree_fits_uhwi_p (TYPE_SIZE (type
))
1775 && GET_MODE_BITSIZE (mode
) == tree_to_uhwi (TYPE_SIZE (type
)))
1778 mode
= mode_for_size_tree (TYPE_SIZE (type
), MODE_INT
, 1).else_blk ();
1780 /* If structure's known alignment is less than what the scalar
1781 mode would need, and it matters, then stick with BLKmode. */
1784 && ! (TYPE_ALIGN (type
) >= BIGGEST_ALIGNMENT
1785 || TYPE_ALIGN (type
) >= GET_MODE_ALIGNMENT (mode
)))
1787 /* If this is the only reason this type is BLKmode, then
1788 don't force containing types to be BLKmode. */
1789 TYPE_NO_FORCE_BLK (type
) = 1;
1793 SET_TYPE_MODE (type
, mode
);
1796 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1800 finalize_type_size (tree type
)
1802 /* Normally, use the alignment corresponding to the mode chosen.
1803 However, where strict alignment is not required, avoid
1804 over-aligning structures, since most compilers do not do this
1806 if (TYPE_MODE (type
) != BLKmode
1807 && TYPE_MODE (type
) != VOIDmode
1808 && (STRICT_ALIGNMENT
|| !AGGREGATE_TYPE_P (type
)))
1810 unsigned mode_align
= GET_MODE_ALIGNMENT (TYPE_MODE (type
));
1812 /* Don't override a larger alignment requirement coming from a user
1813 alignment of one of the fields. */
1814 if (mode_align
>= TYPE_ALIGN (type
))
1816 SET_TYPE_ALIGN (type
, mode_align
);
1817 TYPE_USER_ALIGN (type
) = 0;
1821 /* Do machine-dependent extra alignment. */
1822 #ifdef ROUND_TYPE_ALIGN
1823 SET_TYPE_ALIGN (type
,
1824 ROUND_TYPE_ALIGN (type
, TYPE_ALIGN (type
), BITS_PER_UNIT
));
1827 /* If we failed to find a simple way to calculate the unit size
1828 of the type, find it by division. */
1829 if (TYPE_SIZE_UNIT (type
) == 0 && TYPE_SIZE (type
) != 0)
1830 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1831 result will fit in sizetype. We will get more efficient code using
1832 sizetype, so we force a conversion. */
1833 TYPE_SIZE_UNIT (type
)
1834 = fold_convert (sizetype
,
1835 size_binop (FLOOR_DIV_EXPR
, TYPE_SIZE (type
),
1836 bitsize_unit_node
));
1838 if (TYPE_SIZE (type
) != 0)
1840 TYPE_SIZE (type
) = round_up (TYPE_SIZE (type
), TYPE_ALIGN (type
));
1841 TYPE_SIZE_UNIT (type
)
1842 = round_up (TYPE_SIZE_UNIT (type
), TYPE_ALIGN_UNIT (type
));
1845 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1846 if (TYPE_SIZE (type
) != 0 && TREE_CODE (TYPE_SIZE (type
)) != INTEGER_CST
)
1847 TYPE_SIZE (type
) = variable_size (TYPE_SIZE (type
));
1848 if (TYPE_SIZE_UNIT (type
) != 0
1849 && TREE_CODE (TYPE_SIZE_UNIT (type
)) != INTEGER_CST
)
1850 TYPE_SIZE_UNIT (type
) = variable_size (TYPE_SIZE_UNIT (type
));
1852 /* Also layout any other variants of the type. */
1853 if (TYPE_NEXT_VARIANT (type
)
1854 || type
!= TYPE_MAIN_VARIANT (type
))
1857 /* Record layout info of this variant. */
1858 tree size
= TYPE_SIZE (type
);
1859 tree size_unit
= TYPE_SIZE_UNIT (type
);
1860 unsigned int align
= TYPE_ALIGN (type
);
1861 unsigned int precision
= TYPE_PRECISION (type
);
1862 unsigned int user_align
= TYPE_USER_ALIGN (type
);
1863 machine_mode mode
= TYPE_MODE (type
);
1865 /* Copy it into all variants. */
1866 for (variant
= TYPE_MAIN_VARIANT (type
);
1868 variant
= TYPE_NEXT_VARIANT (variant
))
1870 TYPE_SIZE (variant
) = size
;
1871 TYPE_SIZE_UNIT (variant
) = size_unit
;
1872 unsigned valign
= align
;
1873 if (TYPE_USER_ALIGN (variant
))
1874 valign
= MAX (valign
, TYPE_ALIGN (variant
));
1876 TYPE_USER_ALIGN (variant
) = user_align
;
1877 SET_TYPE_ALIGN (variant
, valign
);
1878 TYPE_PRECISION (variant
) = precision
;
1879 SET_TYPE_MODE (variant
, mode
);
1883 /* Handle empty records as per the x86-64 psABI. */
1884 TYPE_EMPTY_P (type
) = targetm
.calls
.empty_record_p (type
);
1887 /* Return a new underlying object for a bitfield started with FIELD. */
1890 start_bitfield_representative (tree field
)
1892 tree repr
= make_node (FIELD_DECL
);
1893 DECL_FIELD_OFFSET (repr
) = DECL_FIELD_OFFSET (field
);
1894 /* Force the representative to begin at a BITS_PER_UNIT aligned
1895 boundary - C++ may use tail-padding of a base object to
1896 continue packing bits so the bitfield region does not start
1897 at bit zero (see g++.dg/abi/bitfield5.C for example).
1898 Unallocated bits may happen for other reasons as well,
1899 for example Ada which allows explicit bit-granular structure layout. */
1900 DECL_FIELD_BIT_OFFSET (repr
)
1901 = size_binop (BIT_AND_EXPR
,
1902 DECL_FIELD_BIT_OFFSET (field
),
1903 bitsize_int (~(BITS_PER_UNIT
- 1)));
1904 SET_DECL_OFFSET_ALIGN (repr
, DECL_OFFSET_ALIGN (field
));
1905 DECL_SIZE (repr
) = DECL_SIZE (field
);
1906 DECL_SIZE_UNIT (repr
) = DECL_SIZE_UNIT (field
);
1907 DECL_PACKED (repr
) = DECL_PACKED (field
);
1908 DECL_CONTEXT (repr
) = DECL_CONTEXT (field
);
1909 /* There are no indirect accesses to this field. If we introduce
1910 some then they have to use the record alias set. This makes
1911 sure to properly conflict with [indirect] accesses to addressable
1912 fields of the bitfield group. */
1913 DECL_NONADDRESSABLE_P (repr
) = 1;
1917 /* Finish up a bitfield group that was started by creating the underlying
1918 object REPR with the last field in the bitfield group FIELD. */
1921 finish_bitfield_representative (tree repr
, tree field
)
1923 unsigned HOST_WIDE_INT bitsize
, maxbitsize
;
1926 size
= size_diffop (DECL_FIELD_OFFSET (field
),
1927 DECL_FIELD_OFFSET (repr
));
1928 while (TREE_CODE (size
) == COMPOUND_EXPR
)
1929 size
= TREE_OPERAND (size
, 1);
1930 gcc_assert (tree_fits_uhwi_p (size
));
1931 bitsize
= (tree_to_uhwi (size
) * BITS_PER_UNIT
1932 + tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field
))
1933 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr
))
1934 + tree_to_uhwi (DECL_SIZE (field
)));
1936 /* Round up bitsize to multiples of BITS_PER_UNIT. */
1937 bitsize
= (bitsize
+ BITS_PER_UNIT
- 1) & ~(BITS_PER_UNIT
- 1);
1939 /* Now nothing tells us how to pad out bitsize ... */
1940 nextf
= DECL_CHAIN (field
);
1941 while (nextf
&& TREE_CODE (nextf
) != FIELD_DECL
)
1942 nextf
= DECL_CHAIN (nextf
);
1946 /* If there was an error, the field may be not laid out
1947 correctly. Don't bother to do anything. */
1948 if (TREE_TYPE (nextf
) == error_mark_node
)
1950 maxsize
= size_diffop (DECL_FIELD_OFFSET (nextf
),
1951 DECL_FIELD_OFFSET (repr
));
1952 if (tree_fits_uhwi_p (maxsize
))
1954 maxbitsize
= (tree_to_uhwi (maxsize
) * BITS_PER_UNIT
1955 + tree_to_uhwi (DECL_FIELD_BIT_OFFSET (nextf
))
1956 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr
)));
1957 /* If the group ends within a bitfield nextf does not need to be
1958 aligned to BITS_PER_UNIT. Thus round up. */
1959 maxbitsize
= (maxbitsize
+ BITS_PER_UNIT
- 1) & ~(BITS_PER_UNIT
- 1);
1962 maxbitsize
= bitsize
;
1966 /* Note that if the C++ FE sets up tail-padding to be re-used it
1967 creates a as-base variant of the type with TYPE_SIZE adjusted
1968 accordingly. So it is safe to include tail-padding here. */
1969 tree aggsize
= lang_hooks
.types
.unit_size_without_reusable_padding
1970 (DECL_CONTEXT (field
));
1971 tree maxsize
= size_diffop (aggsize
, DECL_FIELD_OFFSET (repr
));
1972 /* We cannot generally rely on maxsize to fold to an integer constant,
1973 so use bitsize as fallback for this case. */
1974 if (tree_fits_uhwi_p (maxsize
))
1975 maxbitsize
= (tree_to_uhwi (maxsize
) * BITS_PER_UNIT
1976 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr
)));
1978 maxbitsize
= bitsize
;
1981 /* Only if we don't artificially break up the representative in
1982 the middle of a large bitfield with different possibly
1983 overlapping representatives. And all representatives start
1985 gcc_assert (maxbitsize
% BITS_PER_UNIT
== 0);
1987 /* Find the smallest nice mode to use. */
1988 opt_scalar_int_mode mode_iter
;
1989 FOR_EACH_MODE_IN_CLASS (mode_iter
, MODE_INT
)
1990 if (GET_MODE_BITSIZE (mode_iter
.require ()) >= bitsize
)
1993 scalar_int_mode mode
;
1994 if (!mode_iter
.exists (&mode
)
1995 || GET_MODE_BITSIZE (mode
) > maxbitsize
1996 || GET_MODE_BITSIZE (mode
) > MAX_FIXED_MODE_SIZE
)
1998 /* We really want a BLKmode representative only as a last resort,
1999 considering the member b in
2000 struct { int a : 7; int b : 17; int c; } __attribute__((packed));
2001 Otherwise we simply want to split the representative up
2002 allowing for overlaps within the bitfield region as required for
2003 struct { int a : 7; int b : 7;
2004 int c : 10; int d; } __attribute__((packed));
2005 [0, 15] HImode for a and b, [8, 23] HImode for c. */
2006 DECL_SIZE (repr
) = bitsize_int (bitsize
);
2007 DECL_SIZE_UNIT (repr
) = size_int (bitsize
/ BITS_PER_UNIT
);
2008 SET_DECL_MODE (repr
, BLKmode
);
2009 TREE_TYPE (repr
) = build_array_type_nelts (unsigned_char_type_node
,
2010 bitsize
/ BITS_PER_UNIT
);
2014 unsigned HOST_WIDE_INT modesize
= GET_MODE_BITSIZE (mode
);
2015 DECL_SIZE (repr
) = bitsize_int (modesize
);
2016 DECL_SIZE_UNIT (repr
) = size_int (modesize
/ BITS_PER_UNIT
);
2017 SET_DECL_MODE (repr
, mode
);
2018 TREE_TYPE (repr
) = lang_hooks
.types
.type_for_mode (mode
, 1);
2021 /* Remember whether the bitfield group is at the end of the
2022 structure or not. */
2023 DECL_CHAIN (repr
) = nextf
;
2026 /* Compute and set FIELD_DECLs for the underlying objects we should
2027 use for bitfield access for the structure T. */
2030 finish_bitfield_layout (tree t
)
2033 tree repr
= NULL_TREE
;
2035 /* Unions would be special, for the ease of type-punning optimizations
2036 we could use the underlying type as hint for the representative
2037 if the bitfield would fit and the representative would not exceed
2038 the union in size. */
2039 if (TREE_CODE (t
) != RECORD_TYPE
)
2042 for (prev
= NULL_TREE
, field
= TYPE_FIELDS (t
);
2043 field
; field
= DECL_CHAIN (field
))
2045 if (TREE_CODE (field
) != FIELD_DECL
)
2048 /* In the C++ memory model, consecutive bit fields in a structure are
2049 considered one memory location and updating a memory location
2050 may not store into adjacent memory locations. */
2052 && DECL_BIT_FIELD_TYPE (field
))
2054 /* Start new representative. */
2055 repr
= start_bitfield_representative (field
);
2058 && ! DECL_BIT_FIELD_TYPE (field
))
2060 /* Finish off new representative. */
2061 finish_bitfield_representative (repr
, prev
);
2064 else if (DECL_BIT_FIELD_TYPE (field
))
2066 gcc_assert (repr
!= NULL_TREE
);
2068 /* Zero-size bitfields finish off a representative and
2069 do not have a representative themselves. This is
2070 required by the C++ memory model. */
2071 if (integer_zerop (DECL_SIZE (field
)))
2073 finish_bitfield_representative (repr
, prev
);
2077 /* We assume that either DECL_FIELD_OFFSET of the representative
2078 and each bitfield member is a constant or they are equal.
2079 This is because we need to be able to compute the bit-offset
2080 of each field relative to the representative in get_bit_range
2081 during RTL expansion.
2082 If these constraints are not met, simply force a new
2083 representative to be generated. That will at most
2084 generate worse code but still maintain correctness with
2085 respect to the C++ memory model. */
2086 else if (!((tree_fits_uhwi_p (DECL_FIELD_OFFSET (repr
))
2087 && tree_fits_uhwi_p (DECL_FIELD_OFFSET (field
)))
2088 || operand_equal_p (DECL_FIELD_OFFSET (repr
),
2089 DECL_FIELD_OFFSET (field
), 0)))
2091 finish_bitfield_representative (repr
, prev
);
2092 repr
= start_bitfield_representative (field
);
2099 DECL_BIT_FIELD_REPRESENTATIVE (field
) = repr
;
2105 finish_bitfield_representative (repr
, prev
);
2108 /* Do all of the work required to layout the type indicated by RLI,
2109 once the fields have been laid out. This function will call `free'
2110 for RLI, unless FREE_P is false. Passing a value other than false
2111 for FREE_P is bad practice; this option only exists to support the
2115 finish_record_layout (record_layout_info rli
, int free_p
)
2119 /* Compute the final size. */
2120 finalize_record_size (rli
);
2122 /* Compute the TYPE_MODE for the record. */
2123 compute_record_mode (rli
->t
);
2125 /* Perform any last tweaks to the TYPE_SIZE, etc. */
2126 finalize_type_size (rli
->t
);
2128 /* Compute bitfield representatives. */
2129 finish_bitfield_layout (rli
->t
);
2131 /* Propagate TYPE_PACKED and TYPE_REVERSE_STORAGE_ORDER to variants.
2132 With C++ templates, it is too early to do this when the attribute
2134 for (variant
= TYPE_NEXT_VARIANT (rli
->t
); variant
;
2135 variant
= TYPE_NEXT_VARIANT (variant
))
2137 TYPE_PACKED (variant
) = TYPE_PACKED (rli
->t
);
2138 TYPE_REVERSE_STORAGE_ORDER (variant
)
2139 = TYPE_REVERSE_STORAGE_ORDER (rli
->t
);
2142 /* Lay out any static members. This is done now because their type
2143 may use the record's type. */
2144 while (!vec_safe_is_empty (rli
->pending_statics
))
2145 layout_decl (rli
->pending_statics
->pop (), 0);
2150 vec_free (rli
->pending_statics
);
2156 /* Finish processing a builtin RECORD_TYPE type TYPE. It's name is
2157 NAME, its fields are chained in reverse on FIELDS.
2159 If ALIGN_TYPE is non-null, it is given the same alignment as
2163 finish_builtin_struct (tree type
, const char *name
, tree fields
,
2168 for (tail
= NULL_TREE
; fields
; tail
= fields
, fields
= next
)
2170 DECL_FIELD_CONTEXT (fields
) = type
;
2171 next
= DECL_CHAIN (fields
);
2172 DECL_CHAIN (fields
) = tail
;
2174 TYPE_FIELDS (type
) = tail
;
2178 SET_TYPE_ALIGN (type
, TYPE_ALIGN (align_type
));
2179 TYPE_USER_ALIGN (type
) = TYPE_USER_ALIGN (align_type
);
2180 SET_TYPE_WARN_IF_NOT_ALIGN (type
,
2181 TYPE_WARN_IF_NOT_ALIGN (align_type
));
2185 #if 0 /* not yet, should get fixed properly later */
2186 TYPE_NAME (type
) = make_type_decl (get_identifier (name
), type
);
2188 TYPE_NAME (type
) = build_decl (BUILTINS_LOCATION
,
2189 TYPE_DECL
, get_identifier (name
), type
);
2191 TYPE_STUB_DECL (type
) = TYPE_NAME (type
);
2192 layout_decl (TYPE_NAME (type
), 0);
2195 /* Calculate the mode, size, and alignment for TYPE.
2196 For an array type, calculate the element separation as well.
2197 Record TYPE on the chain of permanent or temporary types
2198 so that dbxout will find out about it.
2200 TYPE_SIZE of a type is nonzero if the type has been laid out already.
2201 layout_type does nothing on such a type.
2203 If the type is incomplete, its TYPE_SIZE remains zero. */
2206 layout_type (tree type
)
2210 if (type
== error_mark_node
)
2213 /* We don't want finalize_type_size to copy an alignment attribute to
2214 variants that don't have it. */
2215 type
= TYPE_MAIN_VARIANT (type
);
2217 /* Do nothing if type has been laid out before. */
2218 if (TYPE_SIZE (type
))
2221 switch (TREE_CODE (type
))
2224 /* This kind of type is the responsibility
2225 of the language-specific code. */
2232 scalar_int_mode mode
2233 = smallest_int_mode_for_size (TYPE_PRECISION (type
));
2234 SET_TYPE_MODE (type
, mode
);
2235 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2236 /* Don't set TYPE_PRECISION here, as it may be set by a bitfield. */
2237 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2243 /* Allow the caller to choose the type mode, which is how decimal
2244 floats are distinguished from binary ones. */
2245 if (TYPE_MODE (type
) == VOIDmode
)
2247 (type
, float_mode_for_size (TYPE_PRECISION (type
)).require ());
2248 scalar_float_mode mode
= as_a
<scalar_float_mode
> (TYPE_MODE (type
));
2249 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2250 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2254 case FIXED_POINT_TYPE
:
2256 /* TYPE_MODE (type) has been set already. */
2257 scalar_mode mode
= SCALAR_TYPE_MODE (type
);
2258 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2259 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2264 TYPE_UNSIGNED (type
) = TYPE_UNSIGNED (TREE_TYPE (type
));
2265 SET_TYPE_MODE (type
,
2266 GET_MODE_COMPLEX_MODE (TYPE_MODE (TREE_TYPE (type
))));
2268 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
2269 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
2274 int nunits
= TYPE_VECTOR_SUBPARTS (type
);
2275 tree innertype
= TREE_TYPE (type
);
2277 gcc_assert (!(nunits
& (nunits
- 1)));
2279 /* Find an appropriate mode for the vector type. */
2280 if (TYPE_MODE (type
) == VOIDmode
)
2281 SET_TYPE_MODE (type
,
2282 mode_for_vector (SCALAR_TYPE_MODE (innertype
),
2283 nunits
).else_blk ());
2285 TYPE_SATURATING (type
) = TYPE_SATURATING (TREE_TYPE (type
));
2286 TYPE_UNSIGNED (type
) = TYPE_UNSIGNED (TREE_TYPE (type
));
2287 /* Several boolean vector elements may fit in a single unit. */
2288 if (VECTOR_BOOLEAN_TYPE_P (type
)
2289 && type
->type_common
.mode
!= BLKmode
)
2290 TYPE_SIZE_UNIT (type
)
2291 = size_int (GET_MODE_SIZE (type
->type_common
.mode
));
2293 TYPE_SIZE_UNIT (type
) = int_const_binop (MULT_EXPR
,
2294 TYPE_SIZE_UNIT (innertype
),
2296 TYPE_SIZE (type
) = int_const_binop
2298 bits_from_bytes (TYPE_SIZE_UNIT (type
)),
2299 bitsize_int (BITS_PER_UNIT
));
2301 /* For vector types, we do not default to the mode's alignment.
2302 Instead, query a target hook, defaulting to natural alignment.
2303 This prevents ABI changes depending on whether or not native
2304 vector modes are supported. */
2305 SET_TYPE_ALIGN (type
, targetm
.vector_alignment (type
));
2307 /* However, if the underlying mode requires a bigger alignment than
2308 what the target hook provides, we cannot use the mode. For now,
2309 simply reject that case. */
2310 gcc_assert (TYPE_ALIGN (type
)
2311 >= GET_MODE_ALIGNMENT (TYPE_MODE (type
)));
2316 /* This is an incomplete type and so doesn't have a size. */
2317 SET_TYPE_ALIGN (type
, 1);
2318 TYPE_USER_ALIGN (type
) = 0;
2319 SET_TYPE_MODE (type
, VOIDmode
);
2322 case POINTER_BOUNDS_TYPE
:
2323 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
2324 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
2328 TYPE_SIZE (type
) = bitsize_int (POINTER_SIZE
);
2329 TYPE_SIZE_UNIT (type
) = size_int (POINTER_SIZE_UNITS
);
2330 /* A pointer might be MODE_PARTIAL_INT, but ptrdiff_t must be
2331 integral, which may be an __intN. */
2332 SET_TYPE_MODE (type
, int_mode_for_size (POINTER_SIZE
, 0).require ());
2333 TYPE_PRECISION (type
) = POINTER_SIZE
;
2338 /* It's hard to see what the mode and size of a function ought to
2339 be, but we do know the alignment is FUNCTION_BOUNDARY, so
2340 make it consistent with that. */
2341 SET_TYPE_MODE (type
,
2342 int_mode_for_size (FUNCTION_BOUNDARY
, 0).else_blk ());
2343 TYPE_SIZE (type
) = bitsize_int (FUNCTION_BOUNDARY
);
2344 TYPE_SIZE_UNIT (type
) = size_int (FUNCTION_BOUNDARY
/ BITS_PER_UNIT
);
2348 case REFERENCE_TYPE
:
2350 scalar_int_mode mode
= SCALAR_INT_TYPE_MODE (type
);
2351 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2352 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2353 TYPE_UNSIGNED (type
) = 1;
2354 TYPE_PRECISION (type
) = GET_MODE_PRECISION (mode
);
2360 tree index
= TYPE_DOMAIN (type
);
2361 tree element
= TREE_TYPE (type
);
2363 /* We need to know both bounds in order to compute the size. */
2364 if (index
&& TYPE_MAX_VALUE (index
) && TYPE_MIN_VALUE (index
)
2365 && TYPE_SIZE (element
))
2367 tree ub
= TYPE_MAX_VALUE (index
);
2368 tree lb
= TYPE_MIN_VALUE (index
);
2369 tree element_size
= TYPE_SIZE (element
);
2372 /* Make sure that an array of zero-sized element is zero-sized
2373 regardless of its extent. */
2374 if (integer_zerop (element_size
))
2375 length
= size_zero_node
;
2377 /* The computation should happen in the original signedness so
2378 that (possible) negative values are handled appropriately
2379 when determining overflow. */
2382 /* ??? When it is obvious that the range is signed
2383 represent it using ssizetype. */
2384 if (TREE_CODE (lb
) == INTEGER_CST
2385 && TREE_CODE (ub
) == INTEGER_CST
2386 && TYPE_UNSIGNED (TREE_TYPE (lb
))
2387 && tree_int_cst_lt (ub
, lb
))
2389 lb
= wide_int_to_tree (ssizetype
,
2390 offset_int::from (wi::to_wide (lb
),
2392 ub
= wide_int_to_tree (ssizetype
,
2393 offset_int::from (wi::to_wide (ub
),
2397 = fold_convert (sizetype
,
2398 size_binop (PLUS_EXPR
,
2399 build_int_cst (TREE_TYPE (lb
), 1),
2400 size_binop (MINUS_EXPR
, ub
, lb
)));
2403 /* ??? We have no way to distinguish a null-sized array from an
2404 array spanning the whole sizetype range, so we arbitrarily
2405 decide that [0, -1] is the only valid representation. */
2406 if (integer_zerop (length
)
2407 && TREE_OVERFLOW (length
)
2408 && integer_zerop (lb
))
2409 length
= size_zero_node
;
2411 TYPE_SIZE (type
) = size_binop (MULT_EXPR
, element_size
,
2412 bits_from_bytes (length
));
2414 /* If we know the size of the element, calculate the total size
2415 directly, rather than do some division thing below. This
2416 optimization helps Fortran assumed-size arrays (where the
2417 size of the array is determined at runtime) substantially. */
2418 if (TYPE_SIZE_UNIT (element
))
2419 TYPE_SIZE_UNIT (type
)
2420 = size_binop (MULT_EXPR
, TYPE_SIZE_UNIT (element
), length
);
2423 /* Now round the alignment and size,
2424 using machine-dependent criteria if any. */
2426 unsigned align
= TYPE_ALIGN (element
);
2427 if (TYPE_USER_ALIGN (type
))
2428 align
= MAX (align
, TYPE_ALIGN (type
));
2430 TYPE_USER_ALIGN (type
) = TYPE_USER_ALIGN (element
);
2431 if (!TYPE_WARN_IF_NOT_ALIGN (type
))
2432 SET_TYPE_WARN_IF_NOT_ALIGN (type
,
2433 TYPE_WARN_IF_NOT_ALIGN (element
));
2434 #ifdef ROUND_TYPE_ALIGN
2435 align
= ROUND_TYPE_ALIGN (type
, align
, BITS_PER_UNIT
);
2437 align
= MAX (align
, BITS_PER_UNIT
);
2439 SET_TYPE_ALIGN (type
, align
);
2440 SET_TYPE_MODE (type
, BLKmode
);
2441 if (TYPE_SIZE (type
) != 0
2442 && ! targetm
.member_type_forces_blk (type
, VOIDmode
)
2443 /* BLKmode elements force BLKmode aggregate;
2444 else extract/store fields may lose. */
2445 && (TYPE_MODE (TREE_TYPE (type
)) != BLKmode
2446 || TYPE_NO_FORCE_BLK (TREE_TYPE (type
))))
2448 SET_TYPE_MODE (type
, mode_for_array (TREE_TYPE (type
),
2450 if (TYPE_MODE (type
) != BLKmode
2451 && STRICT_ALIGNMENT
&& TYPE_ALIGN (type
) < BIGGEST_ALIGNMENT
2452 && TYPE_ALIGN (type
) < GET_MODE_ALIGNMENT (TYPE_MODE (type
)))
2454 TYPE_NO_FORCE_BLK (type
) = 1;
2455 SET_TYPE_MODE (type
, BLKmode
);
2458 if (AGGREGATE_TYPE_P (element
))
2459 TYPE_TYPELESS_STORAGE (type
) = TYPE_TYPELESS_STORAGE (element
);
2460 /* When the element size is constant, check that it is at least as
2461 large as the element alignment. */
2462 if (TYPE_SIZE_UNIT (element
)
2463 && TREE_CODE (TYPE_SIZE_UNIT (element
)) == INTEGER_CST
2464 /* If TYPE_SIZE_UNIT overflowed, then it is certainly larger than
2466 && !TREE_OVERFLOW (TYPE_SIZE_UNIT (element
))
2467 && !integer_zerop (TYPE_SIZE_UNIT (element
))
2468 && compare_tree_int (TYPE_SIZE_UNIT (element
),
2469 TYPE_ALIGN_UNIT (element
)) < 0)
2470 error ("alignment of array elements is greater than element size");
2476 case QUAL_UNION_TYPE
:
2479 record_layout_info rli
;
2481 /* Initialize the layout information. */
2482 rli
= start_record_layout (type
);
2484 /* If this is a QUAL_UNION_TYPE, we want to process the fields
2485 in the reverse order in building the COND_EXPR that denotes
2486 its size. We reverse them again later. */
2487 if (TREE_CODE (type
) == QUAL_UNION_TYPE
)
2488 TYPE_FIELDS (type
) = nreverse (TYPE_FIELDS (type
));
2490 /* Place all the fields. */
2491 for (field
= TYPE_FIELDS (type
); field
; field
= DECL_CHAIN (field
))
2492 place_field (rli
, field
);
2494 if (TREE_CODE (type
) == QUAL_UNION_TYPE
)
2495 TYPE_FIELDS (type
) = nreverse (TYPE_FIELDS (type
));
2497 /* Finish laying out the record. */
2498 finish_record_layout (rli
, /*free_p=*/true);
2506 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
2507 records and unions, finish_record_layout already called this
2509 if (!RECORD_OR_UNION_TYPE_P (type
))
2510 finalize_type_size (type
);
2512 /* We should never see alias sets on incomplete aggregates. And we
2513 should not call layout_type on not incomplete aggregates. */
2514 if (AGGREGATE_TYPE_P (type
))
2515 gcc_assert (!TYPE_ALIAS_SET_KNOWN_P (type
));
2518 /* Return the least alignment required for type TYPE. */
2521 min_align_of_type (tree type
)
2523 unsigned int align
= TYPE_ALIGN (type
);
2524 if (!TYPE_USER_ALIGN (type
))
2526 align
= MIN (align
, BIGGEST_ALIGNMENT
);
2527 #ifdef BIGGEST_FIELD_ALIGNMENT
2528 align
= MIN (align
, BIGGEST_FIELD_ALIGNMENT
);
2530 unsigned int field_align
= align
;
2531 #ifdef ADJUST_FIELD_ALIGN
2532 field_align
= ADJUST_FIELD_ALIGN (NULL_TREE
, type
, field_align
);
2534 align
= MIN (align
, field_align
);
2536 return align
/ BITS_PER_UNIT
;
2539 /* Create and return a type for signed integers of PRECISION bits. */
2542 make_signed_type (int precision
)
2544 tree type
= make_node (INTEGER_TYPE
);
2546 TYPE_PRECISION (type
) = precision
;
2548 fixup_signed_type (type
);
2552 /* Create and return a type for unsigned integers of PRECISION bits. */
2555 make_unsigned_type (int precision
)
2557 tree type
= make_node (INTEGER_TYPE
);
2559 TYPE_PRECISION (type
) = precision
;
2561 fixup_unsigned_type (type
);
2565 /* Create and return a type for fract of PRECISION bits, UNSIGNEDP,
2569 make_fract_type (int precision
, int unsignedp
, int satp
)
2571 tree type
= make_node (FIXED_POINT_TYPE
);
2573 TYPE_PRECISION (type
) = precision
;
2576 TYPE_SATURATING (type
) = 1;
2578 /* Lay out the type: set its alignment, size, etc. */
2579 TYPE_UNSIGNED (type
) = unsignedp
;
2580 enum mode_class mclass
= unsignedp
? MODE_UFRACT
: MODE_FRACT
;
2581 SET_TYPE_MODE (type
, mode_for_size (precision
, mclass
, 0).require ());
2587 /* Create and return a type for accum of PRECISION bits, UNSIGNEDP,
2591 make_accum_type (int precision
, int unsignedp
, int satp
)
2593 tree type
= make_node (FIXED_POINT_TYPE
);
2595 TYPE_PRECISION (type
) = precision
;
2598 TYPE_SATURATING (type
) = 1;
2600 /* Lay out the type: set its alignment, size, etc. */
2601 TYPE_UNSIGNED (type
) = unsignedp
;
2602 enum mode_class mclass
= unsignedp
? MODE_UACCUM
: MODE_ACCUM
;
2603 SET_TYPE_MODE (type
, mode_for_size (precision
, mclass
, 0).require ());
2609 /* Initialize sizetypes so layout_type can use them. */
2612 initialize_sizetypes (void)
2614 int precision
, bprecision
;
2616 /* Get sizetypes precision from the SIZE_TYPE target macro. */
2617 if (strcmp (SIZETYPE
, "unsigned int") == 0)
2618 precision
= INT_TYPE_SIZE
;
2619 else if (strcmp (SIZETYPE
, "long unsigned int") == 0)
2620 precision
= LONG_TYPE_SIZE
;
2621 else if (strcmp (SIZETYPE
, "long long unsigned int") == 0)
2622 precision
= LONG_LONG_TYPE_SIZE
;
2623 else if (strcmp (SIZETYPE
, "short unsigned int") == 0)
2624 precision
= SHORT_TYPE_SIZE
;
2630 for (i
= 0; i
< NUM_INT_N_ENTS
; i
++)
2631 if (int_n_enabled_p
[i
])
2634 sprintf (name
, "__int%d unsigned", int_n_data
[i
].bitsize
);
2636 if (strcmp (name
, SIZETYPE
) == 0)
2638 precision
= int_n_data
[i
].bitsize
;
2641 if (precision
== -1)
2646 = MIN (precision
+ LOG2_BITS_PER_UNIT
+ 1, MAX_FIXED_MODE_SIZE
);
2647 bprecision
= GET_MODE_PRECISION (smallest_int_mode_for_size (bprecision
));
2648 if (bprecision
> HOST_BITS_PER_DOUBLE_INT
)
2649 bprecision
= HOST_BITS_PER_DOUBLE_INT
;
2651 /* Create stubs for sizetype and bitsizetype so we can create constants. */
2652 sizetype
= make_node (INTEGER_TYPE
);
2653 TYPE_NAME (sizetype
) = get_identifier ("sizetype");
2654 TYPE_PRECISION (sizetype
) = precision
;
2655 TYPE_UNSIGNED (sizetype
) = 1;
2656 bitsizetype
= make_node (INTEGER_TYPE
);
2657 TYPE_NAME (bitsizetype
) = get_identifier ("bitsizetype");
2658 TYPE_PRECISION (bitsizetype
) = bprecision
;
2659 TYPE_UNSIGNED (bitsizetype
) = 1;
2661 /* Now layout both types manually. */
2662 scalar_int_mode mode
= smallest_int_mode_for_size (precision
);
2663 SET_TYPE_MODE (sizetype
, mode
);
2664 SET_TYPE_ALIGN (sizetype
, GET_MODE_ALIGNMENT (TYPE_MODE (sizetype
)));
2665 TYPE_SIZE (sizetype
) = bitsize_int (precision
);
2666 TYPE_SIZE_UNIT (sizetype
) = size_int (GET_MODE_SIZE (mode
));
2667 set_min_and_max_values_for_integral_type (sizetype
, precision
, UNSIGNED
);
2669 mode
= smallest_int_mode_for_size (bprecision
);
2670 SET_TYPE_MODE (bitsizetype
, mode
);
2671 SET_TYPE_ALIGN (bitsizetype
, GET_MODE_ALIGNMENT (TYPE_MODE (bitsizetype
)));
2672 TYPE_SIZE (bitsizetype
) = bitsize_int (bprecision
);
2673 TYPE_SIZE_UNIT (bitsizetype
) = size_int (GET_MODE_SIZE (mode
));
2674 set_min_and_max_values_for_integral_type (bitsizetype
, bprecision
, UNSIGNED
);
2676 /* Create the signed variants of *sizetype. */
2677 ssizetype
= make_signed_type (TYPE_PRECISION (sizetype
));
2678 TYPE_NAME (ssizetype
) = get_identifier ("ssizetype");
2679 sbitsizetype
= make_signed_type (TYPE_PRECISION (bitsizetype
));
2680 TYPE_NAME (sbitsizetype
) = get_identifier ("sbitsizetype");
2683 /* TYPE is an integral type, i.e., an INTEGRAL_TYPE, ENUMERAL_TYPE
2684 or BOOLEAN_TYPE. Set TYPE_MIN_VALUE and TYPE_MAX_VALUE
2685 for TYPE, based on the PRECISION and whether or not the TYPE
2686 IS_UNSIGNED. PRECISION need not correspond to a width supported
2687 natively by the hardware; for example, on a machine with 8-bit,
2688 16-bit, and 32-bit register modes, PRECISION might be 7, 23, or
2692 set_min_and_max_values_for_integral_type (tree type
,
2696 /* For bitfields with zero width we end up creating integer types
2697 with zero precision. Don't assign any minimum/maximum values
2698 to those types, they don't have any valid value. */
2702 TYPE_MIN_VALUE (type
)
2703 = wide_int_to_tree (type
, wi::min_value (precision
, sgn
));
2704 TYPE_MAX_VALUE (type
)
2705 = wide_int_to_tree (type
, wi::max_value (precision
, sgn
));
2708 /* Set the extreme values of TYPE based on its precision in bits,
2709 then lay it out. Used when make_signed_type won't do
2710 because the tree code is not INTEGER_TYPE. */
2713 fixup_signed_type (tree type
)
2715 int precision
= TYPE_PRECISION (type
);
2717 set_min_and_max_values_for_integral_type (type
, precision
, SIGNED
);
2719 /* Lay out the type: set its alignment, size, etc. */
2723 /* Set the extreme values of TYPE based on its precision in bits,
2724 then lay it out. This is used both in `make_unsigned_type'
2725 and for enumeral types. */
2728 fixup_unsigned_type (tree type
)
2730 int precision
= TYPE_PRECISION (type
);
2732 TYPE_UNSIGNED (type
) = 1;
2734 set_min_and_max_values_for_integral_type (type
, precision
, UNSIGNED
);
2736 /* Lay out the type: set its alignment, size, etc. */
2740 /* Construct an iterator for a bitfield that spans BITSIZE bits,
2743 BITREGION_START is the bit position of the first bit in this
2744 sequence of bit fields. BITREGION_END is the last bit in this
2745 sequence. If these two fields are non-zero, we should restrict the
2746 memory access to that range. Otherwise, we are allowed to touch
2747 any adjacent non bit-fields.
2749 ALIGN is the alignment of the underlying object in bits.
2750 VOLATILEP says whether the bitfield is volatile. */
2752 bit_field_mode_iterator
2753 ::bit_field_mode_iterator (HOST_WIDE_INT bitsize
, HOST_WIDE_INT bitpos
,
2754 poly_int64 bitregion_start
,
2755 poly_int64 bitregion_end
,
2756 unsigned int align
, bool volatilep
)
2757 : m_mode (NARROWEST_INT_MODE
), m_bitsize (bitsize
),
2758 m_bitpos (bitpos
), m_bitregion_start (bitregion_start
),
2759 m_bitregion_end (bitregion_end
), m_align (align
),
2760 m_volatilep (volatilep
), m_count (0)
2762 if (known_eq (m_bitregion_end
, 0))
2764 /* We can assume that any aligned chunk of ALIGN bits that overlaps
2765 the bitfield is mapped and won't trap, provided that ALIGN isn't
2766 too large. The cap is the biggest required alignment for data,
2767 or at least the word size. And force one such chunk at least. */
2768 unsigned HOST_WIDE_INT units
2769 = MIN (align
, MAX (BIGGEST_ALIGNMENT
, BITS_PER_WORD
));
2772 HOST_WIDE_INT end
= bitpos
+ bitsize
+ units
- 1;
2773 m_bitregion_end
= end
- end
% units
- 1;
2777 /* Calls to this function return successively larger modes that can be used
2778 to represent the bitfield. Return true if another bitfield mode is
2779 available, storing it in *OUT_MODE if so. */
2782 bit_field_mode_iterator::next_mode (scalar_int_mode
*out_mode
)
2784 scalar_int_mode mode
;
2785 for (; m_mode
.exists (&mode
); m_mode
= GET_MODE_WIDER_MODE (mode
))
2787 unsigned int unit
= GET_MODE_BITSIZE (mode
);
2789 /* Skip modes that don't have full precision. */
2790 if (unit
!= GET_MODE_PRECISION (mode
))
2793 /* Stop if the mode is too wide to handle efficiently. */
2794 if (unit
> MAX_FIXED_MODE_SIZE
)
2797 /* Don't deliver more than one multiword mode; the smallest one
2799 if (m_count
> 0 && unit
> BITS_PER_WORD
)
2802 /* Skip modes that are too small. */
2803 unsigned HOST_WIDE_INT substart
= (unsigned HOST_WIDE_INT
) m_bitpos
% unit
;
2804 unsigned HOST_WIDE_INT subend
= substart
+ m_bitsize
;
2808 /* Stop if the mode goes outside the bitregion. */
2809 HOST_WIDE_INT start
= m_bitpos
- substart
;
2810 if (maybe_ne (m_bitregion_start
, 0)
2811 && maybe_lt (start
, m_bitregion_start
))
2813 HOST_WIDE_INT end
= start
+ unit
;
2814 if (maybe_gt (end
, m_bitregion_end
+ 1))
2817 /* Stop if the mode requires too much alignment. */
2818 if (GET_MODE_ALIGNMENT (mode
) > m_align
2819 && targetm
.slow_unaligned_access (mode
, m_align
))
2823 m_mode
= GET_MODE_WIDER_MODE (mode
);
2830 /* Return true if smaller modes are generally preferred for this kind
2834 bit_field_mode_iterator::prefer_smaller_modes ()
2837 ? targetm
.narrow_volatile_bitfield ()
2838 : !SLOW_BYTE_ACCESS
);
2841 /* Find the best machine mode to use when referencing a bit field of length
2842 BITSIZE bits starting at BITPOS.
2844 BITREGION_START is the bit position of the first bit in this
2845 sequence of bit fields. BITREGION_END is the last bit in this
2846 sequence. If these two fields are non-zero, we should restrict the
2847 memory access to that range. Otherwise, we are allowed to touch
2848 any adjacent non bit-fields.
2850 The chosen mode must have no more than LARGEST_MODE_BITSIZE bits.
2851 INT_MAX is a suitable value for LARGEST_MODE_BITSIZE if the caller
2852 doesn't want to apply a specific limit.
2854 If no mode meets all these conditions, we return VOIDmode.
2856 The underlying object is known to be aligned to a boundary of ALIGN bits.
2858 If VOLATILEP is false and SLOW_BYTE_ACCESS is false, we return the
2859 smallest mode meeting these conditions.
2861 If VOLATILEP is false and SLOW_BYTE_ACCESS is true, we return the
2862 largest mode (but a mode no wider than UNITS_PER_WORD) that meets
2865 If VOLATILEP is true the narrow_volatile_bitfields target hook is used to
2866 decide which of the above modes should be used. */
2869 get_best_mode (int bitsize
, int bitpos
,
2870 poly_uint64 bitregion_start
, poly_uint64 bitregion_end
,
2872 unsigned HOST_WIDE_INT largest_mode_bitsize
, bool volatilep
,
2873 scalar_int_mode
*best_mode
)
2875 bit_field_mode_iterator
iter (bitsize
, bitpos
, bitregion_start
,
2876 bitregion_end
, align
, volatilep
);
2877 scalar_int_mode mode
;
2879 while (iter
.next_mode (&mode
)
2880 /* ??? For historical reasons, reject modes that would normally
2881 receive greater alignment, even if unaligned accesses are
2882 acceptable. This has both advantages and disadvantages.
2883 Removing this check means that something like:
2885 struct s { unsigned int x; unsigned int y; };
2886 int f (struct s *s) { return s->x == 0 && s->y == 0; }
2888 can be implemented using a single load and compare on
2889 64-bit machines that have no alignment restrictions.
2890 For example, on powerpc64-linux-gnu, we would generate:
2912 However, accessing more than one field can make life harder
2913 for the gimple optimizers. For example, gcc.dg/vect/bb-slp-5.c
2914 has a series of unsigned short copies followed by a series of
2915 unsigned short comparisons. With this check, both the copies
2916 and comparisons remain 16-bit accesses and FRE is able
2917 to eliminate the latter. Without the check, the comparisons
2918 can be done using 2 64-bit operations, which FRE isn't able
2919 to handle in the same way.
2921 Either way, it would probably be worth disabling this check
2922 during expand. One particular example where removing the
2923 check would help is the get_best_mode call in store_bit_field.
2924 If we are given a memory bitregion of 128 bits that is aligned
2925 to a 64-bit boundary, and the bitfield we want to modify is
2926 in the second half of the bitregion, this check causes
2927 store_bitfield to turn the memory into a 64-bit reference
2928 to the _first_ half of the region. We later use
2929 adjust_bitfield_address to get a reference to the correct half,
2930 but doing so looks to adjust_bitfield_address as though we are
2931 moving past the end of the original object, so it drops the
2932 associated MEM_EXPR and MEM_OFFSET. Removing the check
2933 causes store_bit_field to keep a 128-bit memory reference,
2934 so that the final bitfield reference still has a MEM_EXPR
2936 && GET_MODE_ALIGNMENT (mode
) <= align
2937 && GET_MODE_BITSIZE (mode
) <= largest_mode_bitsize
)
2941 if (iter
.prefer_smaller_modes ())
2948 /* Gets minimal and maximal values for MODE (signed or unsigned depending on
2949 SIGN). The returned constants are made to be usable in TARGET_MODE. */
2952 get_mode_bounds (scalar_int_mode mode
, int sign
,
2953 scalar_int_mode target_mode
,
2954 rtx
*mmin
, rtx
*mmax
)
2956 unsigned size
= GET_MODE_PRECISION (mode
);
2957 unsigned HOST_WIDE_INT min_val
, max_val
;
2959 gcc_assert (size
<= HOST_BITS_PER_WIDE_INT
);
2961 /* Special case BImode, which has values 0 and STORE_FLAG_VALUE. */
2964 if (STORE_FLAG_VALUE
< 0)
2966 min_val
= STORE_FLAG_VALUE
;
2972 max_val
= STORE_FLAG_VALUE
;
2977 min_val
= -(HOST_WIDE_INT_1U
<< (size
- 1));
2978 max_val
= (HOST_WIDE_INT_1U
<< (size
- 1)) - 1;
2983 max_val
= (HOST_WIDE_INT_1U
<< (size
- 1) << 1) - 1;
2986 *mmin
= gen_int_mode (min_val
, target_mode
);
2987 *mmax
= gen_int_mode (max_val
, target_mode
);
2990 #include "gt-stor-layout.h"