1 /* C-compiler utilities for types and variables storage layout
2 Copyright (C) 1987-2021 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"
47 /* Data type for the expressions representing sizes of data types.
48 It is the first integer type laid out. */
49 tree sizetype_tab
[(int) stk_type_kind_last
];
51 /* If nonzero, this is an upper limit on alignment of structure fields.
52 The value is measured in bits. */
53 unsigned int maximum_field_alignment
= TARGET_DEFAULT_PACK_STRUCT
* BITS_PER_UNIT
;
55 static tree
self_referential_size (tree
);
56 static void finalize_record_size (record_layout_info
);
57 static void finalize_type_size (tree
);
58 static void place_union_field (record_layout_info
, tree
);
59 static int excess_unit_span (HOST_WIDE_INT
, HOST_WIDE_INT
, HOST_WIDE_INT
,
61 extern void debug_rli (record_layout_info
);
63 /* Given a size SIZE that may not be a constant, return a SAVE_EXPR
64 to serve as the actual size-expression for a type or decl. */
67 variable_size (tree size
)
70 if (TREE_CONSTANT (size
))
73 /* If the size is self-referential, we can't make a SAVE_EXPR (see
74 save_expr for the rationale). But we can do something else. */
75 if (CONTAINS_PLACEHOLDER_P (size
))
76 return self_referential_size (size
);
78 /* If we are in the global binding level, we can't make a SAVE_EXPR
79 since it may end up being shared across functions, so it is up
80 to the front-end to deal with this case. */
81 if (lang_hooks
.decls
.global_bindings_p ())
84 return save_expr (size
);
87 /* An array of functions used for self-referential size computation. */
88 static GTY(()) vec
<tree
, va_gc
> *size_functions
;
90 /* Return true if T is a self-referential component reference. */
93 self_referential_component_ref_p (tree t
)
95 if (TREE_CODE (t
) != COMPONENT_REF
)
98 while (REFERENCE_CLASS_P (t
))
99 t
= TREE_OPERAND (t
, 0);
101 return (TREE_CODE (t
) == PLACEHOLDER_EXPR
);
104 /* Similar to copy_tree_r but do not copy component references involving
105 PLACEHOLDER_EXPRs. These nodes are spotted in find_placeholder_in_expr
106 and substituted in substitute_in_expr. */
109 copy_self_referential_tree_r (tree
*tp
, int *walk_subtrees
, void *data
)
111 enum tree_code code
= TREE_CODE (*tp
);
113 /* Stop at types, decls, constants like copy_tree_r. */
114 if (TREE_CODE_CLASS (code
) == tcc_type
115 || TREE_CODE_CLASS (code
) == tcc_declaration
116 || TREE_CODE_CLASS (code
) == tcc_constant
)
122 /* This is the pattern built in ada/make_aligning_type. */
123 else if (code
== ADDR_EXPR
124 && TREE_CODE (TREE_OPERAND (*tp
, 0)) == PLACEHOLDER_EXPR
)
130 /* Default case: the component reference. */
131 else if (self_referential_component_ref_p (*tp
))
137 /* We're not supposed to have them in self-referential size trees
138 because we wouldn't properly control when they are evaluated.
139 However, not creating superfluous SAVE_EXPRs requires accurate
140 tracking of readonly-ness all the way down to here, which we
141 cannot always guarantee in practice. So punt in this case. */
142 else if (code
== SAVE_EXPR
)
143 return error_mark_node
;
145 else if (code
== STATEMENT_LIST
)
148 return copy_tree_r (tp
, walk_subtrees
, data
);
151 /* Given a SIZE expression that is self-referential, return an equivalent
152 expression to serve as the actual size expression for a type. */
155 self_referential_size (tree size
)
157 static unsigned HOST_WIDE_INT fnno
= 0;
158 vec
<tree
> self_refs
= vNULL
;
159 tree param_type_list
= NULL
, param_decl_list
= NULL
;
160 tree t
, ref
, return_type
, fntype
, fnname
, fndecl
;
163 vec
<tree
, va_gc
> *args
= NULL
;
165 /* Do not factor out simple operations. */
166 t
= skip_simple_constant_arithmetic (size
);
167 if (TREE_CODE (t
) == CALL_EXPR
|| self_referential_component_ref_p (t
))
170 /* Collect the list of self-references in the expression. */
171 find_placeholder_in_expr (size
, &self_refs
);
172 gcc_assert (self_refs
.length () > 0);
174 /* Obtain a private copy of the expression. */
176 if (walk_tree (&t
, copy_self_referential_tree_r
, NULL
, NULL
) != NULL_TREE
)
180 /* Build the parameter and argument lists in parallel; also
181 substitute the former for the latter in the expression. */
182 vec_alloc (args
, self_refs
.length ());
183 FOR_EACH_VEC_ELT (self_refs
, i
, ref
)
185 tree subst
, param_name
, param_type
, param_decl
;
189 /* We shouldn't have true variables here. */
190 gcc_assert (TREE_READONLY (ref
));
193 /* This is the pattern built in ada/make_aligning_type. */
194 else if (TREE_CODE (ref
) == ADDR_EXPR
)
196 /* Default case: the component reference. */
198 subst
= TREE_OPERAND (ref
, 1);
200 sprintf (buf
, "p%d", i
);
201 param_name
= get_identifier (buf
);
202 param_type
= TREE_TYPE (ref
);
204 = build_decl (input_location
, PARM_DECL
, param_name
, param_type
);
205 DECL_ARG_TYPE (param_decl
) = param_type
;
206 DECL_ARTIFICIAL (param_decl
) = 1;
207 TREE_READONLY (param_decl
) = 1;
209 size
= substitute_in_expr (size
, subst
, param_decl
);
211 param_type_list
= tree_cons (NULL_TREE
, param_type
, param_type_list
);
212 param_decl_list
= chainon (param_decl
, param_decl_list
);
213 args
->quick_push (ref
);
216 self_refs
.release ();
218 /* Append 'void' to indicate that the number of parameters is fixed. */
219 param_type_list
= tree_cons (NULL_TREE
, void_type_node
, param_type_list
);
221 /* The 3 lists have been created in reverse order. */
222 param_type_list
= nreverse (param_type_list
);
223 param_decl_list
= nreverse (param_decl_list
);
225 /* Build the function type. */
226 return_type
= TREE_TYPE (size
);
227 fntype
= build_function_type (return_type
, param_type_list
);
229 /* Build the function declaration. */
230 sprintf (buf
, "SZ" HOST_WIDE_INT_PRINT_UNSIGNED
, fnno
++);
231 fnname
= get_file_function_name (buf
);
232 fndecl
= build_decl (input_location
, FUNCTION_DECL
, fnname
, fntype
);
233 for (t
= param_decl_list
; t
; t
= DECL_CHAIN (t
))
234 DECL_CONTEXT (t
) = fndecl
;
235 DECL_ARGUMENTS (fndecl
) = param_decl_list
;
237 = build_decl (input_location
, RESULT_DECL
, 0, return_type
);
238 DECL_CONTEXT (DECL_RESULT (fndecl
)) = fndecl
;
240 /* The function has been created by the compiler and we don't
241 want to emit debug info for it. */
242 DECL_ARTIFICIAL (fndecl
) = 1;
243 DECL_IGNORED_P (fndecl
) = 1;
245 /* It is supposed to be "const" and never throw. */
246 TREE_READONLY (fndecl
) = 1;
247 TREE_NOTHROW (fndecl
) = 1;
249 /* We want it to be inlined when this is deemed profitable, as
250 well as discarded if every call has been integrated. */
251 DECL_DECLARED_INLINE_P (fndecl
) = 1;
253 /* It is made up of a unique return statement. */
254 DECL_INITIAL (fndecl
) = make_node (BLOCK
);
255 BLOCK_SUPERCONTEXT (DECL_INITIAL (fndecl
)) = fndecl
;
256 t
= build2 (MODIFY_EXPR
, return_type
, DECL_RESULT (fndecl
), size
);
257 DECL_SAVED_TREE (fndecl
) = build1 (RETURN_EXPR
, void_type_node
, t
);
258 TREE_STATIC (fndecl
) = 1;
260 /* Put it onto the list of size functions. */
261 vec_safe_push (size_functions
, fndecl
);
263 /* Replace the original expression with a call to the size function. */
264 return build_call_expr_loc_vec (UNKNOWN_LOCATION
, fndecl
, args
);
267 /* Take, queue and compile all the size functions. It is essential that
268 the size functions be gimplified at the very end of the compilation
269 in order to guarantee transparent handling of self-referential sizes.
270 Otherwise the GENERIC inliner would not be able to inline them back
271 at each of their call sites, thus creating artificial non-constant
272 size expressions which would trigger nasty problems later on. */
275 finalize_size_functions (void)
280 for (i
= 0; size_functions
&& size_functions
->iterate (i
, &fndecl
); i
++)
282 allocate_struct_function (fndecl
, false);
284 dump_function (TDI_original
, fndecl
);
286 /* As these functions are used to describe the layout of variable-length
287 structures, debug info generation needs their implementation. */
288 debug_hooks
->size_function (fndecl
);
289 gimplify_function_tree (fndecl
);
290 cgraph_node::finalize_function (fndecl
, false);
293 vec_free (size_functions
);
296 /* Return a machine mode of class MCLASS with SIZE bits of precision,
297 if one exists. The mode may have padding bits as well the SIZE
298 value bits. If LIMIT is nonzero, disregard modes wider than
299 MAX_FIXED_MODE_SIZE. */
302 mode_for_size (poly_uint64 size
, enum mode_class mclass
, int limit
)
307 if (limit
&& maybe_gt (size
, (unsigned int) MAX_FIXED_MODE_SIZE
))
308 return opt_machine_mode ();
310 /* Get the first mode which has this size, in the specified class. */
311 FOR_EACH_MODE_IN_CLASS (mode
, mclass
)
312 if (known_eq (GET_MODE_PRECISION (mode
), size
))
315 if (mclass
== MODE_INT
|| mclass
== MODE_PARTIAL_INT
)
316 for (i
= 0; i
< NUM_INT_N_ENTS
; i
++)
317 if (known_eq (int_n_data
[i
].bitsize
, size
)
318 && int_n_enabled_p
[i
])
319 return int_n_data
[i
].m
;
321 return opt_machine_mode ();
324 /* Similar, except passed a tree node. */
327 mode_for_size_tree (const_tree size
, enum mode_class mclass
, int limit
)
329 unsigned HOST_WIDE_INT uhwi
;
332 if (!tree_fits_uhwi_p (size
))
333 return opt_machine_mode ();
334 uhwi
= tree_to_uhwi (size
);
337 return opt_machine_mode ();
338 return mode_for_size (ui
, mclass
, limit
);
341 /* Return the narrowest mode of class MCLASS that contains at least
342 SIZE bits. Abort if no such mode exists. */
345 smallest_mode_for_size (poly_uint64 size
, enum mode_class mclass
)
347 machine_mode mode
= VOIDmode
;
350 /* Get the first mode which has at least this size, in the
352 FOR_EACH_MODE_IN_CLASS (mode
, mclass
)
353 if (known_ge (GET_MODE_PRECISION (mode
), size
))
356 gcc_assert (mode
!= VOIDmode
);
358 if (mclass
== MODE_INT
|| mclass
== MODE_PARTIAL_INT
)
359 for (i
= 0; i
< NUM_INT_N_ENTS
; i
++)
360 if (known_ge (int_n_data
[i
].bitsize
, size
)
361 && known_lt (int_n_data
[i
].bitsize
, GET_MODE_PRECISION (mode
))
362 && int_n_enabled_p
[i
])
363 mode
= int_n_data
[i
].m
;
368 /* Return an integer mode of exactly the same size as MODE, if one exists. */
371 int_mode_for_mode (machine_mode mode
)
373 switch (GET_MODE_CLASS (mode
))
376 case MODE_PARTIAL_INT
:
377 return as_a
<scalar_int_mode
> (mode
);
379 case MODE_COMPLEX_INT
:
380 case MODE_COMPLEX_FLOAT
:
382 case MODE_DECIMAL_FLOAT
:
387 case MODE_VECTOR_BOOL
:
388 case MODE_VECTOR_INT
:
389 case MODE_VECTOR_FLOAT
:
390 case MODE_VECTOR_FRACT
:
391 case MODE_VECTOR_ACCUM
:
392 case MODE_VECTOR_UFRACT
:
393 case MODE_VECTOR_UACCUM
:
394 return int_mode_for_size (GET_MODE_BITSIZE (mode
), 0);
397 return opt_scalar_int_mode ();
401 return opt_scalar_int_mode ();
411 /* Find a mode that can be used for efficient bitwise operations on MODE,
415 bitwise_mode_for_mode (machine_mode mode
)
417 /* Quick exit if we already have a suitable mode. */
418 scalar_int_mode int_mode
;
419 if (is_a
<scalar_int_mode
> (mode
, &int_mode
)
420 && GET_MODE_BITSIZE (int_mode
) <= MAX_FIXED_MODE_SIZE
)
423 /* Reuse the sanity checks from int_mode_for_mode. */
424 gcc_checking_assert ((int_mode_for_mode (mode
), true));
426 poly_int64 bitsize
= GET_MODE_BITSIZE (mode
);
428 /* Try to replace complex modes with complex modes. In general we
429 expect both components to be processed independently, so we only
430 care whether there is a register for the inner mode. */
431 if (COMPLEX_MODE_P (mode
))
433 machine_mode trial
= mode
;
434 if ((GET_MODE_CLASS (trial
) == MODE_COMPLEX_INT
435 || mode_for_size (bitsize
, MODE_COMPLEX_INT
, false).exists (&trial
))
436 && have_regs_of_mode
[GET_MODE_INNER (trial
)])
440 /* Try to replace vector modes with vector modes. Also try using vector
441 modes if an integer mode would be too big. */
442 if (VECTOR_MODE_P (mode
)
443 || maybe_gt (bitsize
, MAX_FIXED_MODE_SIZE
))
445 machine_mode trial
= mode
;
446 if ((GET_MODE_CLASS (trial
) == MODE_VECTOR_INT
447 || mode_for_size (bitsize
, MODE_VECTOR_INT
, 0).exists (&trial
))
448 && have_regs_of_mode
[trial
]
449 && targetm
.vector_mode_supported_p (trial
))
453 /* Otherwise fall back on integers while honoring MAX_FIXED_MODE_SIZE. */
454 return mode_for_size (bitsize
, MODE_INT
, true);
457 /* Find a type that can be used for efficient bitwise operations on MODE.
458 Return null if no such mode exists. */
461 bitwise_type_for_mode (machine_mode mode
)
463 if (!bitwise_mode_for_mode (mode
).exists (&mode
))
466 unsigned int inner_size
= GET_MODE_UNIT_BITSIZE (mode
);
467 tree inner_type
= build_nonstandard_integer_type (inner_size
, true);
469 if (VECTOR_MODE_P (mode
))
470 return build_vector_type_for_mode (inner_type
, mode
);
472 if (COMPLEX_MODE_P (mode
))
473 return build_complex_type (inner_type
);
475 gcc_checking_assert (GET_MODE_INNER (mode
) == mode
);
479 /* Find a mode that is suitable for representing a vector with NUNITS
480 elements of mode INNERMODE, if one exists. The returned mode can be
481 either an integer mode or a vector mode. */
484 mode_for_vector (scalar_mode innermode
, poly_uint64 nunits
)
488 /* First, look for a supported vector type. */
489 if (SCALAR_FLOAT_MODE_P (innermode
))
490 mode
= MIN_MODE_VECTOR_FLOAT
;
491 else if (SCALAR_FRACT_MODE_P (innermode
))
492 mode
= MIN_MODE_VECTOR_FRACT
;
493 else if (SCALAR_UFRACT_MODE_P (innermode
))
494 mode
= MIN_MODE_VECTOR_UFRACT
;
495 else if (SCALAR_ACCUM_MODE_P (innermode
))
496 mode
= MIN_MODE_VECTOR_ACCUM
;
497 else if (SCALAR_UACCUM_MODE_P (innermode
))
498 mode
= MIN_MODE_VECTOR_UACCUM
;
500 mode
= MIN_MODE_VECTOR_INT
;
502 /* Do not check vector_mode_supported_p here. We'll do that
503 later in vector_type_mode. */
504 FOR_EACH_MODE_FROM (mode
, mode
)
505 if (known_eq (GET_MODE_NUNITS (mode
), nunits
)
506 && GET_MODE_INNER (mode
) == innermode
)
509 /* For integers, try mapping it to a same-sized scalar mode. */
510 if (GET_MODE_CLASS (innermode
) == MODE_INT
)
512 poly_uint64 nbits
= nunits
* GET_MODE_BITSIZE (innermode
);
513 if (int_mode_for_size (nbits
, 0).exists (&mode
)
514 && have_regs_of_mode
[mode
])
518 return opt_machine_mode ();
521 /* If a piece of code is using vector mode VECTOR_MODE and also wants
522 to operate on elements of mode ELEMENT_MODE, return the vector mode
523 it should use for those elements. If NUNITS is nonzero, ensure that
524 the mode has exactly NUNITS elements, otherwise pick whichever vector
525 size pairs the most naturally with VECTOR_MODE; this may mean choosing
526 a mode with a different size and/or number of elements, depending on
527 what the target prefers. Return an empty opt_machine_mode if there
528 is no supported vector mode with the required properties.
530 Unlike mode_for_vector. any returned mode is guaranteed to satisfy
531 both VECTOR_MODE_P and targetm.vector_mode_supported_p. */
534 related_vector_mode (machine_mode vector_mode
, scalar_mode element_mode
,
537 gcc_assert (VECTOR_MODE_P (vector_mode
));
538 return targetm
.vectorize
.related_mode (vector_mode
, element_mode
, nunits
);
541 /* If a piece of code is using vector mode VECTOR_MODE and also wants
542 to operate on integer vectors with the same element size and number
543 of elements, return the vector mode it should use. Return an empty
544 opt_machine_mode if there is no supported vector mode with the
547 Unlike mode_for_vector. any returned mode is guaranteed to satisfy
548 both VECTOR_MODE_P and targetm.vector_mode_supported_p. */
551 related_int_vector_mode (machine_mode vector_mode
)
553 gcc_assert (VECTOR_MODE_P (vector_mode
));
554 scalar_int_mode int_mode
;
555 if (int_mode_for_mode (GET_MODE_INNER (vector_mode
)).exists (&int_mode
))
556 return related_vector_mode (vector_mode
, int_mode
,
557 GET_MODE_NUNITS (vector_mode
));
558 return opt_machine_mode ();
561 /* Return the alignment of MODE. This will be bounded by 1 and
562 BIGGEST_ALIGNMENT. */
565 get_mode_alignment (machine_mode mode
)
567 return MIN (BIGGEST_ALIGNMENT
, MAX (1, mode_base_align
[mode
]*BITS_PER_UNIT
));
570 /* Return the natural mode of an array, given that it is SIZE bytes in
571 total and has elements of type ELEM_TYPE. */
574 mode_for_array (tree elem_type
, tree size
)
577 poly_uint64 int_size
, int_elem_size
;
578 unsigned HOST_WIDE_INT num_elems
;
581 /* One-element arrays get the component type's mode. */
582 elem_size
= TYPE_SIZE (elem_type
);
583 if (simple_cst_equal (size
, elem_size
))
584 return TYPE_MODE (elem_type
);
587 if (poly_int_tree_p (size
, &int_size
)
588 && poly_int_tree_p (elem_size
, &int_elem_size
)
589 && maybe_ne (int_elem_size
, 0U)
590 && constant_multiple_p (int_size
, int_elem_size
, &num_elems
))
592 machine_mode elem_mode
= TYPE_MODE (elem_type
);
594 if (targetm
.array_mode (elem_mode
, num_elems
).exists (&mode
))
596 if (targetm
.array_mode_supported_p (elem_mode
, num_elems
))
599 return mode_for_size_tree (size
, MODE_INT
, limit_p
).else_blk ();
602 /* Subroutine of layout_decl: Force alignment required for the data type.
603 But if the decl itself wants greater alignment, don't override that. */
606 do_type_align (tree type
, tree decl
)
608 if (TYPE_ALIGN (type
) > DECL_ALIGN (decl
))
610 SET_DECL_ALIGN (decl
, TYPE_ALIGN (type
));
611 if (TREE_CODE (decl
) == FIELD_DECL
)
612 DECL_USER_ALIGN (decl
) = TYPE_USER_ALIGN (type
);
614 if (TYPE_WARN_IF_NOT_ALIGN (type
) > DECL_WARN_IF_NOT_ALIGN (decl
))
615 SET_DECL_WARN_IF_NOT_ALIGN (decl
, TYPE_WARN_IF_NOT_ALIGN (type
));
618 /* Set the size, mode and alignment of a ..._DECL node.
619 TYPE_DECL does need this for C++.
620 Note that LABEL_DECL and CONST_DECL nodes do not need this,
621 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
622 Don't call layout_decl for them.
624 KNOWN_ALIGN is the amount of alignment we can assume this
625 decl has with no special effort. It is relevant only for FIELD_DECLs
626 and depends on the previous fields.
627 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
628 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
629 the record will be aligned to suit. */
632 layout_decl (tree decl
, unsigned int known_align
)
634 tree type
= TREE_TYPE (decl
);
635 enum tree_code code
= TREE_CODE (decl
);
637 location_t loc
= DECL_SOURCE_LOCATION (decl
);
639 if (code
== CONST_DECL
)
642 gcc_assert (code
== VAR_DECL
|| code
== PARM_DECL
|| code
== RESULT_DECL
643 || code
== TYPE_DECL
|| code
== FIELD_DECL
);
645 rtl
= DECL_RTL_IF_SET (decl
);
647 if (type
== error_mark_node
)
648 type
= void_type_node
;
650 /* Usually the size and mode come from the data type without change,
651 however, the front-end may set the explicit width of the field, so its
652 size may not be the same as the size of its type. This happens with
653 bitfields, of course (an `int' bitfield may be only 2 bits, say), but it
654 also happens with other fields. For example, the C++ front-end creates
655 zero-sized fields corresponding to empty base classes, and depends on
656 layout_type setting DECL_FIELD_BITPOS correctly for the field. Set the
657 size in bytes from the size in bits. If we have already set the mode,
658 don't set it again since we can be called twice for FIELD_DECLs. */
660 DECL_UNSIGNED (decl
) = TYPE_UNSIGNED (type
);
661 if (DECL_MODE (decl
) == VOIDmode
)
662 SET_DECL_MODE (decl
, TYPE_MODE (type
));
664 if (DECL_SIZE (decl
) == 0)
666 DECL_SIZE (decl
) = TYPE_SIZE (type
);
667 DECL_SIZE_UNIT (decl
) = TYPE_SIZE_UNIT (type
);
669 else if (DECL_SIZE_UNIT (decl
) == 0)
670 DECL_SIZE_UNIT (decl
)
671 = fold_convert_loc (loc
, sizetype
,
672 size_binop_loc (loc
, CEIL_DIV_EXPR
, DECL_SIZE (decl
),
675 if (code
!= FIELD_DECL
)
676 /* For non-fields, update the alignment from the type. */
677 do_type_align (type
, decl
);
679 /* For fields, it's a bit more complicated... */
681 bool old_user_align
= DECL_USER_ALIGN (decl
);
682 bool zero_bitfield
= false;
683 bool packed_p
= DECL_PACKED (decl
);
686 if (DECL_BIT_FIELD (decl
))
688 DECL_BIT_FIELD_TYPE (decl
) = type
;
690 /* A zero-length bit-field affects the alignment of the next
691 field. In essence such bit-fields are not influenced by
692 any packing due to #pragma pack or attribute packed. */
693 if (integer_zerop (DECL_SIZE (decl
))
694 && ! targetm
.ms_bitfield_layout_p (DECL_FIELD_CONTEXT (decl
)))
696 zero_bitfield
= true;
698 if (PCC_BITFIELD_TYPE_MATTERS
)
699 do_type_align (type
, decl
);
702 #ifdef EMPTY_FIELD_BOUNDARY
703 if (EMPTY_FIELD_BOUNDARY
> DECL_ALIGN (decl
))
705 SET_DECL_ALIGN (decl
, EMPTY_FIELD_BOUNDARY
);
706 DECL_USER_ALIGN (decl
) = 0;
712 /* See if we can use an ordinary integer mode for a bit-field.
713 Conditions are: a fixed size that is correct for another mode,
714 occupying a complete byte or bytes on proper boundary. */
715 if (TYPE_SIZE (type
) != 0
716 && TREE_CODE (TYPE_SIZE (type
)) == INTEGER_CST
717 && GET_MODE_CLASS (TYPE_MODE (type
)) == MODE_INT
)
720 if (mode_for_size_tree (DECL_SIZE (decl
),
721 MODE_INT
, 1).exists (&xmode
))
723 unsigned int xalign
= GET_MODE_ALIGNMENT (xmode
);
724 if (!(xalign
> BITS_PER_UNIT
&& DECL_PACKED (decl
))
725 && (known_align
== 0 || known_align
>= xalign
))
727 SET_DECL_ALIGN (decl
, MAX (xalign
, DECL_ALIGN (decl
)));
728 SET_DECL_MODE (decl
, xmode
);
729 DECL_BIT_FIELD (decl
) = 0;
734 /* Turn off DECL_BIT_FIELD if we won't need it set. */
735 if (TYPE_MODE (type
) == BLKmode
&& DECL_MODE (decl
) == BLKmode
736 && known_align
>= TYPE_ALIGN (type
)
737 && DECL_ALIGN (decl
) >= TYPE_ALIGN (type
))
738 DECL_BIT_FIELD (decl
) = 0;
740 else if (packed_p
&& DECL_USER_ALIGN (decl
))
741 /* Don't touch DECL_ALIGN. For other packed fields, go ahead and
742 round up; we'll reduce it again below. We want packing to
743 supersede USER_ALIGN inherited from the type, but defer to
744 alignment explicitly specified on the field decl. */;
746 do_type_align (type
, decl
);
748 /* If the field is packed and not explicitly aligned, give it the
749 minimum alignment. Note that do_type_align may set
750 DECL_USER_ALIGN, so we need to check old_user_align instead. */
753 SET_DECL_ALIGN (decl
, MIN (DECL_ALIGN (decl
), BITS_PER_UNIT
));
755 if (! packed_p
&& ! DECL_USER_ALIGN (decl
))
757 /* Some targets (i.e. i386, VMS) limit struct field alignment
758 to a lower boundary than alignment of variables unless
759 it was overridden by attribute aligned. */
760 #ifdef BIGGEST_FIELD_ALIGNMENT
761 SET_DECL_ALIGN (decl
, MIN (DECL_ALIGN (decl
),
762 (unsigned) BIGGEST_FIELD_ALIGNMENT
));
764 #ifdef ADJUST_FIELD_ALIGN
765 SET_DECL_ALIGN (decl
, ADJUST_FIELD_ALIGN (decl
, TREE_TYPE (decl
),
771 mfa
= initial_max_fld_align
* BITS_PER_UNIT
;
773 mfa
= maximum_field_alignment
;
774 /* Should this be controlled by DECL_USER_ALIGN, too? */
776 SET_DECL_ALIGN (decl
, MIN (DECL_ALIGN (decl
), mfa
));
779 /* Evaluate nonconstant size only once, either now or as soon as safe. */
780 if (DECL_SIZE (decl
) != 0 && TREE_CODE (DECL_SIZE (decl
)) != INTEGER_CST
)
781 DECL_SIZE (decl
) = variable_size (DECL_SIZE (decl
));
782 if (DECL_SIZE_UNIT (decl
) != 0
783 && TREE_CODE (DECL_SIZE_UNIT (decl
)) != INTEGER_CST
)
784 DECL_SIZE_UNIT (decl
) = variable_size (DECL_SIZE_UNIT (decl
));
786 /* If requested, warn about definitions of large data objects. */
787 if ((code
== PARM_DECL
|| (code
== VAR_DECL
&& !DECL_NONLOCAL_FRAME (decl
)))
788 && !DECL_EXTERNAL (decl
))
790 tree size
= DECL_SIZE_UNIT (decl
);
792 if (size
!= 0 && TREE_CODE (size
) == INTEGER_CST
)
794 /* -Wlarger-than= argument of HOST_WIDE_INT_MAX is treated
795 as if PTRDIFF_MAX had been specified, with the value
796 being that on the target rather than the host. */
797 unsigned HOST_WIDE_INT max_size
= warn_larger_than_size
;
798 if (max_size
== HOST_WIDE_INT_MAX
)
799 max_size
= tree_to_shwi (TYPE_MAX_VALUE (ptrdiff_type_node
));
801 if (compare_tree_int (size
, max_size
) > 0)
802 warning (OPT_Wlarger_than_
, "size of %q+D %E bytes exceeds "
803 "maximum object size %wu",
804 decl
, size
, max_size
);
808 /* If the RTL was already set, update its mode and mem attributes. */
811 PUT_MODE (rtl
, DECL_MODE (decl
));
812 SET_DECL_RTL (decl
, 0);
814 set_mem_attributes (rtl
, decl
, 1);
815 SET_DECL_RTL (decl
, rtl
);
819 /* Given a VAR_DECL, PARM_DECL, RESULT_DECL, or FIELD_DECL, clears the
820 results of a previous call to layout_decl and calls it again. */
823 relayout_decl (tree decl
)
825 DECL_SIZE (decl
) = DECL_SIZE_UNIT (decl
) = 0;
826 SET_DECL_MODE (decl
, VOIDmode
);
827 if (!DECL_USER_ALIGN (decl
))
828 SET_DECL_ALIGN (decl
, 0);
829 if (DECL_RTL_SET_P (decl
))
830 SET_DECL_RTL (decl
, 0);
832 layout_decl (decl
, 0);
835 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
836 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
837 is to be passed to all other layout functions for this record. It is the
838 responsibility of the caller to call `free' for the storage returned.
839 Note that garbage collection is not permitted until we finish laying
843 start_record_layout (tree t
)
845 record_layout_info rli
= XNEW (struct record_layout_info_s
);
849 /* If the type has a minimum specified alignment (via an attribute
850 declaration, for example) use it -- otherwise, start with a
851 one-byte alignment. */
852 rli
->record_align
= MAX (BITS_PER_UNIT
, TYPE_ALIGN (t
));
853 rli
->unpacked_align
= rli
->record_align
;
854 rli
->offset_align
= MAX (rli
->record_align
, BIGGEST_ALIGNMENT
);
856 #ifdef STRUCTURE_SIZE_BOUNDARY
857 /* Packed structures don't need to have minimum size. */
858 if (! TYPE_PACKED (t
))
862 /* #pragma pack overrides STRUCTURE_SIZE_BOUNDARY. */
863 tmp
= (unsigned) STRUCTURE_SIZE_BOUNDARY
;
864 if (maximum_field_alignment
!= 0)
865 tmp
= MIN (tmp
, maximum_field_alignment
);
866 rli
->record_align
= MAX (rli
->record_align
, tmp
);
870 rli
->offset
= size_zero_node
;
871 rli
->bitpos
= bitsize_zero_node
;
873 rli
->pending_statics
= 0;
874 rli
->packed_maybe_necessary
= 0;
875 rli
->remaining_in_alignment
= 0;
880 /* Fold sizetype value X to bitsizetype, given that X represents a type
884 bits_from_bytes (tree x
)
886 if (POLY_INT_CST_P (x
))
887 /* The runtime calculation isn't allowed to overflow sizetype;
888 increasing the runtime values must always increase the size
889 or offset of the object. This means that the object imposes
890 a maximum value on the runtime parameters, but we don't record
892 return build_poly_int_cst
894 poly_wide_int::from (poly_int_cst_value (x
),
895 TYPE_PRECISION (bitsizetype
),
896 TYPE_SIGN (TREE_TYPE (x
))));
897 x
= fold_convert (bitsizetype
, x
);
898 gcc_checking_assert (x
);
902 /* Return the combined bit position for the byte offset OFFSET and the
905 These functions operate on byte and bit positions present in FIELD_DECLs
906 and assume that these expressions result in no (intermediate) overflow.
907 This assumption is necessary to fold the expressions as much as possible,
908 so as to avoid creating artificially variable-sized types in languages
909 supporting variable-sized types like Ada. */
912 bit_from_pos (tree offset
, tree bitpos
)
914 return size_binop (PLUS_EXPR
, bitpos
,
915 size_binop (MULT_EXPR
, bits_from_bytes (offset
),
919 /* Return the combined truncated byte position for the byte offset OFFSET and
920 the bit position BITPOS. */
923 byte_from_pos (tree offset
, tree bitpos
)
926 if (TREE_CODE (bitpos
) == MULT_EXPR
927 && tree_int_cst_equal (TREE_OPERAND (bitpos
, 1), bitsize_unit_node
))
928 bytepos
= TREE_OPERAND (bitpos
, 0);
930 bytepos
= size_binop (TRUNC_DIV_EXPR
, bitpos
, bitsize_unit_node
);
931 return size_binop (PLUS_EXPR
, offset
, fold_convert (sizetype
, bytepos
));
934 /* Split the bit position POS into a byte offset *POFFSET and a bit
935 position *PBITPOS with the byte offset aligned to OFF_ALIGN bits. */
938 pos_from_bit (tree
*poffset
, tree
*pbitpos
, unsigned int off_align
,
941 tree toff_align
= bitsize_int (off_align
);
942 if (TREE_CODE (pos
) == MULT_EXPR
943 && tree_int_cst_equal (TREE_OPERAND (pos
, 1), toff_align
))
945 *poffset
= size_binop (MULT_EXPR
,
946 fold_convert (sizetype
, TREE_OPERAND (pos
, 0)),
947 size_int (off_align
/ BITS_PER_UNIT
));
948 *pbitpos
= bitsize_zero_node
;
952 *poffset
= size_binop (MULT_EXPR
,
953 fold_convert (sizetype
,
954 size_binop (FLOOR_DIV_EXPR
, pos
,
956 size_int (off_align
/ BITS_PER_UNIT
));
957 *pbitpos
= size_binop (FLOOR_MOD_EXPR
, pos
, toff_align
);
961 /* Given a pointer to bit and byte offsets and an offset alignment,
962 normalize the offsets so they are within the alignment. */
965 normalize_offset (tree
*poffset
, tree
*pbitpos
, unsigned int off_align
)
967 /* If the bit position is now larger than it should be, adjust it
969 if (compare_tree_int (*pbitpos
, off_align
) >= 0)
972 pos_from_bit (&offset
, &bitpos
, off_align
, *pbitpos
);
973 *poffset
= size_binop (PLUS_EXPR
, *poffset
, offset
);
978 /* Print debugging information about the information in RLI. */
981 debug_rli (record_layout_info rli
)
983 print_node_brief (stderr
, "type", rli
->t
, 0);
984 print_node_brief (stderr
, "\noffset", rli
->offset
, 0);
985 print_node_brief (stderr
, " bitpos", rli
->bitpos
, 0);
987 fprintf (stderr
, "\naligns: rec = %u, unpack = %u, off = %u\n",
988 rli
->record_align
, rli
->unpacked_align
,
991 /* The ms_struct code is the only that uses this. */
992 if (targetm
.ms_bitfield_layout_p (rli
->t
))
993 fprintf (stderr
, "remaining in alignment = %u\n", rli
->remaining_in_alignment
);
995 if (rli
->packed_maybe_necessary
)
996 fprintf (stderr
, "packed may be necessary\n");
998 if (!vec_safe_is_empty (rli
->pending_statics
))
1000 fprintf (stderr
, "pending statics:\n");
1001 debug (rli
->pending_statics
);
1005 /* Given an RLI with a possibly-incremented BITPOS, adjust OFFSET and
1006 BITPOS if necessary to keep BITPOS below OFFSET_ALIGN. */
1009 normalize_rli (record_layout_info rli
)
1011 normalize_offset (&rli
->offset
, &rli
->bitpos
, rli
->offset_align
);
1014 /* Returns the size in bytes allocated so far. */
1017 rli_size_unit_so_far (record_layout_info rli
)
1019 return byte_from_pos (rli
->offset
, rli
->bitpos
);
1022 /* Returns the size in bits allocated so far. */
1025 rli_size_so_far (record_layout_info rli
)
1027 return bit_from_pos (rli
->offset
, rli
->bitpos
);
1030 /* FIELD is about to be added to RLI->T. The alignment (in bits) of
1031 the next available location within the record is given by KNOWN_ALIGN.
1032 Update the variable alignment fields in RLI, and return the alignment
1033 to give the FIELD. */
1036 update_alignment_for_field (record_layout_info rli
, tree field
,
1037 unsigned int known_align
)
1039 /* The alignment required for FIELD. */
1040 unsigned int desired_align
;
1041 /* The type of this field. */
1042 tree type
= TREE_TYPE (field
);
1043 /* True if the field was explicitly aligned by the user. */
1047 /* Do not attempt to align an ERROR_MARK node */
1048 if (TREE_CODE (type
) == ERROR_MARK
)
1051 /* Lay out the field so we know what alignment it needs. */
1052 layout_decl (field
, known_align
);
1053 desired_align
= DECL_ALIGN (field
);
1054 user_align
= DECL_USER_ALIGN (field
);
1056 is_bitfield
= (type
!= error_mark_node
1057 && DECL_BIT_FIELD_TYPE (field
)
1058 && ! integer_zerop (TYPE_SIZE (type
)));
1060 /* Record must have at least as much alignment as any field.
1061 Otherwise, the alignment of the field within the record is
1063 if (targetm
.ms_bitfield_layout_p (rli
->t
))
1065 /* Here, the alignment of the underlying type of a bitfield can
1066 affect the alignment of a record; even a zero-sized field
1067 can do this. The alignment should be to the alignment of
1068 the type, except that for zero-size bitfields this only
1069 applies if there was an immediately prior, nonzero-size
1070 bitfield. (That's the way it is, experimentally.) */
1072 || ((DECL_SIZE (field
) == NULL_TREE
1073 || !integer_zerop (DECL_SIZE (field
)))
1074 ? !DECL_PACKED (field
)
1076 && DECL_BIT_FIELD_TYPE (rli
->prev_field
)
1077 && ! integer_zerop (DECL_SIZE (rli
->prev_field
)))))
1079 unsigned int type_align
= TYPE_ALIGN (type
);
1080 if (!is_bitfield
&& DECL_PACKED (field
))
1081 type_align
= desired_align
;
1083 type_align
= MAX (type_align
, desired_align
);
1084 if (maximum_field_alignment
!= 0)
1085 type_align
= MIN (type_align
, maximum_field_alignment
);
1086 rli
->record_align
= MAX (rli
->record_align
, type_align
);
1087 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
1090 else if (is_bitfield
&& PCC_BITFIELD_TYPE_MATTERS
)
1092 /* Named bit-fields cause the entire structure to have the
1093 alignment implied by their type. Some targets also apply the same
1094 rules to unnamed bitfields. */
1095 if (DECL_NAME (field
) != 0
1096 || targetm
.align_anon_bitfield ())
1098 unsigned int type_align
= TYPE_ALIGN (type
);
1100 #ifdef ADJUST_FIELD_ALIGN
1101 if (! TYPE_USER_ALIGN (type
))
1102 type_align
= ADJUST_FIELD_ALIGN (field
, type
, type_align
);
1105 /* Targets might chose to handle unnamed and hence possibly
1106 zero-width bitfield. Those are not influenced by #pragmas
1107 or packed attributes. */
1108 if (integer_zerop (DECL_SIZE (field
)))
1110 if (initial_max_fld_align
)
1111 type_align
= MIN (type_align
,
1112 initial_max_fld_align
* BITS_PER_UNIT
);
1114 else if (maximum_field_alignment
!= 0)
1115 type_align
= MIN (type_align
, maximum_field_alignment
);
1116 else if (DECL_PACKED (field
))
1117 type_align
= MIN (type_align
, BITS_PER_UNIT
);
1119 /* The alignment of the record is increased to the maximum
1120 of the current alignment, the alignment indicated on the
1121 field (i.e., the alignment specified by an __aligned__
1122 attribute), and the alignment indicated by the type of
1124 rli
->record_align
= MAX (rli
->record_align
, desired_align
);
1125 rli
->record_align
= MAX (rli
->record_align
, type_align
);
1128 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
1129 user_align
|= TYPE_USER_ALIGN (type
);
1134 rli
->record_align
= MAX (rli
->record_align
, desired_align
);
1135 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
1138 TYPE_USER_ALIGN (rli
->t
) |= user_align
;
1140 return desired_align
;
1143 /* Issue a warning if the record alignment, RECORD_ALIGN, is less than
1144 the field alignment of FIELD or FIELD isn't aligned. */
1147 handle_warn_if_not_align (tree field
, unsigned int record_align
)
1149 tree type
= TREE_TYPE (field
);
1151 if (type
== error_mark_node
)
1154 unsigned int warn_if_not_align
= 0;
1158 if (warn_if_not_aligned
)
1160 warn_if_not_align
= DECL_WARN_IF_NOT_ALIGN (field
);
1161 if (!warn_if_not_align
)
1162 warn_if_not_align
= TYPE_WARN_IF_NOT_ALIGN (type
);
1163 if (warn_if_not_align
)
1164 opt_w
= OPT_Wif_not_aligned
;
1167 if (!warn_if_not_align
1168 && warn_packed_not_aligned
1169 && lookup_attribute ("aligned", TYPE_ATTRIBUTES (type
)))
1171 warn_if_not_align
= TYPE_ALIGN (type
);
1172 opt_w
= OPT_Wpacked_not_aligned
;
1175 if (!warn_if_not_align
)
1178 tree context
= DECL_CONTEXT (field
);
1180 warn_if_not_align
/= BITS_PER_UNIT
;
1181 record_align
/= BITS_PER_UNIT
;
1182 if ((record_align
% warn_if_not_align
) != 0)
1183 warning (opt_w
, "alignment %u of %qT is less than %u",
1184 record_align
, context
, warn_if_not_align
);
1186 tree off
= byte_position (field
);
1187 if (!multiple_of_p (TREE_TYPE (off
), off
, size_int (warn_if_not_align
)))
1189 if (TREE_CODE (off
) == INTEGER_CST
)
1190 warning (opt_w
, "%q+D offset %E in %qT isn%'t aligned to %u",
1191 field
, off
, context
, warn_if_not_align
);
1193 warning (opt_w
, "%q+D offset %E in %qT may not be aligned to %u",
1194 field
, off
, context
, warn_if_not_align
);
1198 /* Called from place_field to handle unions. */
1201 place_union_field (record_layout_info rli
, tree field
)
1203 update_alignment_for_field (rli
, field
, /*known_align=*/0);
1205 DECL_FIELD_OFFSET (field
) = size_zero_node
;
1206 DECL_FIELD_BIT_OFFSET (field
) = bitsize_zero_node
;
1207 SET_DECL_OFFSET_ALIGN (field
, BIGGEST_ALIGNMENT
);
1208 handle_warn_if_not_align (field
, rli
->record_align
);
1210 /* If this is an ERROR_MARK return *after* having set the
1211 field at the start of the union. This helps when parsing
1213 if (TREE_CODE (TREE_TYPE (field
)) == ERROR_MARK
)
1216 if (AGGREGATE_TYPE_P (TREE_TYPE (field
))
1217 && TYPE_TYPELESS_STORAGE (TREE_TYPE (field
)))
1218 TYPE_TYPELESS_STORAGE (rli
->t
) = 1;
1220 /* We assume the union's size will be a multiple of a byte so we don't
1221 bother with BITPOS. */
1222 if (TREE_CODE (rli
->t
) == UNION_TYPE
)
1223 rli
->offset
= size_binop (MAX_EXPR
, rli
->offset
, DECL_SIZE_UNIT (field
));
1224 else if (TREE_CODE (rli
->t
) == QUAL_UNION_TYPE
)
1225 rli
->offset
= fold_build3 (COND_EXPR
, sizetype
, DECL_QUALIFIER (field
),
1226 DECL_SIZE_UNIT (field
), rli
->offset
);
1229 /* A bitfield of SIZE with a required access alignment of ALIGN is allocated
1230 at BYTE_OFFSET / BIT_OFFSET. Return nonzero if the field would span more
1231 units of alignment than the underlying TYPE. */
1233 excess_unit_span (HOST_WIDE_INT byte_offset
, HOST_WIDE_INT bit_offset
,
1234 HOST_WIDE_INT size
, HOST_WIDE_INT align
, tree type
)
1236 /* Note that the calculation of OFFSET might overflow; we calculate it so
1237 that we still get the right result as long as ALIGN is a power of two. */
1238 unsigned HOST_WIDE_INT offset
= byte_offset
* BITS_PER_UNIT
+ bit_offset
;
1240 offset
= offset
% align
;
1241 return ((offset
+ size
+ align
- 1) / align
1242 > tree_to_uhwi (TYPE_SIZE (type
)) / align
);
1245 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
1246 is a FIELD_DECL to be added after those fields already present in
1247 T. (FIELD is not actually added to the TYPE_FIELDS list here;
1248 callers that desire that behavior must manually perform that step.) */
1251 place_field (record_layout_info rli
, tree field
)
1253 /* The alignment required for FIELD. */
1254 unsigned int desired_align
;
1255 /* The alignment FIELD would have if we just dropped it into the
1256 record as it presently stands. */
1257 unsigned int known_align
;
1258 unsigned int actual_align
;
1259 /* The type of this field. */
1260 tree type
= TREE_TYPE (field
);
1262 gcc_assert (TREE_CODE (field
) != ERROR_MARK
);
1264 /* If FIELD is static, then treat it like a separate variable, not
1265 really like a structure field. If it is a FUNCTION_DECL, it's a
1266 method. In both cases, all we do is lay out the decl, and we do
1267 it *after* the record is laid out. */
1270 vec_safe_push (rli
->pending_statics
, field
);
1274 /* Enumerators and enum types which are local to this class need not
1275 be laid out. Likewise for initialized constant fields. */
1276 else if (TREE_CODE (field
) != FIELD_DECL
)
1279 /* Unions are laid out very differently than records, so split
1280 that code off to another function. */
1281 else if (TREE_CODE (rli
->t
) != RECORD_TYPE
)
1283 place_union_field (rli
, field
);
1287 else if (TREE_CODE (type
) == ERROR_MARK
)
1289 /* Place this field at the current allocation position, so we
1290 maintain monotonicity. */
1291 DECL_FIELD_OFFSET (field
) = rli
->offset
;
1292 DECL_FIELD_BIT_OFFSET (field
) = rli
->bitpos
;
1293 SET_DECL_OFFSET_ALIGN (field
, rli
->offset_align
);
1294 handle_warn_if_not_align (field
, rli
->record_align
);
1298 if (AGGREGATE_TYPE_P (type
)
1299 && TYPE_TYPELESS_STORAGE (type
))
1300 TYPE_TYPELESS_STORAGE (rli
->t
) = 1;
1302 /* Work out the known alignment so far. Note that A & (-A) is the
1303 value of the least-significant bit in A that is one. */
1304 if (! integer_zerop (rli
->bitpos
))
1305 known_align
= least_bit_hwi (tree_to_uhwi (rli
->bitpos
));
1306 else if (integer_zerop (rli
->offset
))
1308 else if (tree_fits_uhwi_p (rli
->offset
))
1309 known_align
= (BITS_PER_UNIT
1310 * least_bit_hwi (tree_to_uhwi (rli
->offset
)));
1312 known_align
= rli
->offset_align
;
1314 desired_align
= update_alignment_for_field (rli
, field
, known_align
);
1315 if (known_align
== 0)
1316 known_align
= MAX (BIGGEST_ALIGNMENT
, rli
->record_align
);
1318 if (warn_packed
&& DECL_PACKED (field
))
1320 if (known_align
>= TYPE_ALIGN (type
))
1322 if (TYPE_ALIGN (type
) > desired_align
)
1324 if (STRICT_ALIGNMENT
)
1325 warning (OPT_Wattributes
, "packed attribute causes "
1326 "inefficient alignment for %q+D", field
);
1327 /* Don't warn if DECL_PACKED was set by the type. */
1328 else if (!TYPE_PACKED (rli
->t
))
1329 warning (OPT_Wattributes
, "packed attribute is "
1330 "unnecessary for %q+D", field
);
1334 rli
->packed_maybe_necessary
= 1;
1337 /* Does this field automatically have alignment it needs by virtue
1338 of the fields that precede it and the record's own alignment? */
1339 if (known_align
< desired_align
1340 && (! targetm
.ms_bitfield_layout_p (rli
->t
)
1341 || rli
->prev_field
== NULL
))
1343 /* No, we need to skip space before this field.
1344 Bump the cumulative size to multiple of field alignment. */
1346 if (!targetm
.ms_bitfield_layout_p (rli
->t
)
1347 && DECL_SOURCE_LOCATION (field
) != BUILTINS_LOCATION
1348 && !TYPE_ARTIFICIAL (rli
->t
))
1349 warning (OPT_Wpadded
, "padding struct to align %q+D", field
);
1351 /* If the alignment is still within offset_align, just align
1352 the bit position. */
1353 if (desired_align
< rli
->offset_align
)
1354 rli
->bitpos
= round_up (rli
->bitpos
, desired_align
);
1357 /* First adjust OFFSET by the partial bits, then align. */
1359 = size_binop (PLUS_EXPR
, rli
->offset
,
1360 fold_convert (sizetype
,
1361 size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
1362 bitsize_unit_node
)));
1363 rli
->bitpos
= bitsize_zero_node
;
1365 rli
->offset
= round_up (rli
->offset
, desired_align
/ BITS_PER_UNIT
);
1368 if (! TREE_CONSTANT (rli
->offset
))
1369 rli
->offset_align
= desired_align
;
1372 /* Handle compatibility with PCC. Note that if the record has any
1373 variable-sized fields, we need not worry about compatibility. */
1374 if (PCC_BITFIELD_TYPE_MATTERS
1375 && ! targetm
.ms_bitfield_layout_p (rli
->t
)
1376 && TREE_CODE (field
) == FIELD_DECL
1377 && type
!= error_mark_node
1378 && DECL_BIT_FIELD (field
)
1379 && (! DECL_PACKED (field
)
1380 /* Enter for these packed fields only to issue a warning. */
1381 || TYPE_ALIGN (type
) <= BITS_PER_UNIT
)
1382 && maximum_field_alignment
== 0
1383 && ! integer_zerop (DECL_SIZE (field
))
1384 && tree_fits_uhwi_p (DECL_SIZE (field
))
1385 && tree_fits_uhwi_p (rli
->offset
)
1386 && tree_fits_uhwi_p (TYPE_SIZE (type
)))
1388 unsigned int type_align
= TYPE_ALIGN (type
);
1389 tree dsize
= DECL_SIZE (field
);
1390 HOST_WIDE_INT field_size
= tree_to_uhwi (dsize
);
1391 HOST_WIDE_INT offset
= tree_to_uhwi (rli
->offset
);
1392 HOST_WIDE_INT bit_offset
= tree_to_shwi (rli
->bitpos
);
1394 #ifdef ADJUST_FIELD_ALIGN
1395 if (! TYPE_USER_ALIGN (type
))
1396 type_align
= ADJUST_FIELD_ALIGN (field
, type
, type_align
);
1399 /* A bit field may not span more units of alignment of its type
1400 than its type itself. Advance to next boundary if necessary. */
1401 if (excess_unit_span (offset
, bit_offset
, field_size
, type_align
, type
))
1403 if (DECL_PACKED (field
))
1405 if (warn_packed_bitfield_compat
== 1)
1408 "offset of packed bit-field %qD has changed in GCC 4.4",
1412 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1415 if (! DECL_PACKED (field
))
1416 TYPE_USER_ALIGN (rli
->t
) |= TYPE_USER_ALIGN (type
);
1418 SET_TYPE_WARN_IF_NOT_ALIGN (rli
->t
,
1419 TYPE_WARN_IF_NOT_ALIGN (type
));
1422 #ifdef BITFIELD_NBYTES_LIMITED
1423 if (BITFIELD_NBYTES_LIMITED
1424 && ! targetm
.ms_bitfield_layout_p (rli
->t
)
1425 && TREE_CODE (field
) == FIELD_DECL
1426 && type
!= error_mark_node
1427 && DECL_BIT_FIELD_TYPE (field
)
1428 && ! DECL_PACKED (field
)
1429 && ! integer_zerop (DECL_SIZE (field
))
1430 && tree_fits_uhwi_p (DECL_SIZE (field
))
1431 && tree_fits_uhwi_p (rli
->offset
)
1432 && tree_fits_uhwi_p (TYPE_SIZE (type
)))
1434 unsigned int type_align
= TYPE_ALIGN (type
);
1435 tree dsize
= DECL_SIZE (field
);
1436 HOST_WIDE_INT field_size
= tree_to_uhwi (dsize
);
1437 HOST_WIDE_INT offset
= tree_to_uhwi (rli
->offset
);
1438 HOST_WIDE_INT bit_offset
= tree_to_shwi (rli
->bitpos
);
1440 #ifdef ADJUST_FIELD_ALIGN
1441 if (! TYPE_USER_ALIGN (type
))
1442 type_align
= ADJUST_FIELD_ALIGN (field
, type
, type_align
);
1445 if (maximum_field_alignment
!= 0)
1446 type_align
= MIN (type_align
, maximum_field_alignment
);
1447 /* ??? This test is opposite the test in the containing if
1448 statement, so this code is unreachable currently. */
1449 else if (DECL_PACKED (field
))
1450 type_align
= MIN (type_align
, BITS_PER_UNIT
);
1452 /* A bit field may not span the unit of alignment of its type.
1453 Advance to next boundary if necessary. */
1454 if (excess_unit_span (offset
, bit_offset
, field_size
, type_align
, type
))
1455 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1457 TYPE_USER_ALIGN (rli
->t
) |= TYPE_USER_ALIGN (type
);
1458 SET_TYPE_WARN_IF_NOT_ALIGN (rli
->t
,
1459 TYPE_WARN_IF_NOT_ALIGN (type
));
1463 /* See the docs for TARGET_MS_BITFIELD_LAYOUT_P for details.
1465 When a bit field is inserted into a packed record, the whole
1466 size of the underlying type is used by one or more same-size
1467 adjacent bitfields. (That is, if its long:3, 32 bits is
1468 used in the record, and any additional adjacent long bitfields are
1469 packed into the same chunk of 32 bits. However, if the size
1470 changes, a new field of that size is allocated.) In an unpacked
1471 record, this is the same as using alignment, but not equivalent
1474 Note: for compatibility, we use the type size, not the type alignment
1475 to determine alignment, since that matches the documentation */
1477 if (targetm
.ms_bitfield_layout_p (rli
->t
))
1479 tree prev_saved
= rli
->prev_field
;
1480 tree prev_type
= prev_saved
? DECL_BIT_FIELD_TYPE (prev_saved
) : NULL
;
1482 /* This is a bitfield if it exists. */
1483 if (rli
->prev_field
)
1485 bool realign_p
= known_align
< desired_align
;
1487 /* If both are bitfields, nonzero, and the same size, this is
1488 the middle of a run. Zero declared size fields are special
1489 and handled as "end of run". (Note: it's nonzero declared
1490 size, but equal type sizes!) (Since we know that both
1491 the current and previous fields are bitfields by the
1492 time we check it, DECL_SIZE must be present for both.) */
1493 if (DECL_BIT_FIELD_TYPE (field
)
1494 && !integer_zerop (DECL_SIZE (field
))
1495 && !integer_zerop (DECL_SIZE (rli
->prev_field
))
1496 && tree_fits_shwi_p (DECL_SIZE (rli
->prev_field
))
1497 && tree_fits_uhwi_p (TYPE_SIZE (type
))
1498 && simple_cst_equal (TYPE_SIZE (type
), TYPE_SIZE (prev_type
)))
1500 /* We're in the middle of a run of equal type size fields; make
1501 sure we realign if we run out of bits. (Not decl size,
1503 HOST_WIDE_INT bitsize
= tree_to_uhwi (DECL_SIZE (field
));
1505 if (rli
->remaining_in_alignment
< bitsize
)
1507 HOST_WIDE_INT typesize
= tree_to_uhwi (TYPE_SIZE (type
));
1509 /* out of bits; bump up to next 'word'. */
1511 = size_binop (PLUS_EXPR
, rli
->bitpos
,
1512 bitsize_int (rli
->remaining_in_alignment
));
1513 rli
->prev_field
= field
;
1514 if (typesize
< bitsize
)
1515 rli
->remaining_in_alignment
= 0;
1517 rli
->remaining_in_alignment
= typesize
- bitsize
;
1521 rli
->remaining_in_alignment
-= bitsize
;
1527 /* End of a run: if leaving a run of bitfields of the same type
1528 size, we have to "use up" the rest of the bits of the type
1531 Compute the new position as the sum of the size for the prior
1532 type and where we first started working on that type.
1533 Note: since the beginning of the field was aligned then
1534 of course the end will be too. No round needed. */
1536 if (!integer_zerop (DECL_SIZE (rli
->prev_field
)))
1539 = size_binop (PLUS_EXPR
, rli
->bitpos
,
1540 bitsize_int (rli
->remaining_in_alignment
));
1543 /* We "use up" size zero fields; the code below should behave
1544 as if the prior field was not a bitfield. */
1547 /* Cause a new bitfield to be captured, either this time (if
1548 currently a bitfield) or next time we see one. */
1549 if (!DECL_BIT_FIELD_TYPE (field
)
1550 || integer_zerop (DECL_SIZE (field
)))
1551 rli
->prev_field
= NULL
;
1554 /* Does this field automatically have alignment it needs by virtue
1555 of the fields that precede it and the record's own alignment? */
1558 /* If the alignment is still within offset_align, just align
1559 the bit position. */
1560 if (desired_align
< rli
->offset_align
)
1561 rli
->bitpos
= round_up (rli
->bitpos
, desired_align
);
1564 /* First adjust OFFSET by the partial bits, then align. */
1565 tree d
= size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
1567 rli
->offset
= size_binop (PLUS_EXPR
, rli
->offset
,
1568 fold_convert (sizetype
, d
));
1569 rli
->bitpos
= bitsize_zero_node
;
1571 rli
->offset
= round_up (rli
->offset
,
1572 desired_align
/ BITS_PER_UNIT
);
1575 if (! TREE_CONSTANT (rli
->offset
))
1576 rli
->offset_align
= desired_align
;
1579 normalize_rli (rli
);
1582 /* If we're starting a new run of same type size bitfields
1583 (or a run of non-bitfields), set up the "first of the run"
1586 That is, if the current field is not a bitfield, or if there
1587 was a prior bitfield the type sizes differ, or if there wasn't
1588 a prior bitfield the size of the current field is nonzero.
1590 Note: we must be sure to test ONLY the type size if there was
1591 a prior bitfield and ONLY for the current field being zero if
1594 if (!DECL_BIT_FIELD_TYPE (field
)
1595 || (prev_saved
!= NULL
1596 ? !simple_cst_equal (TYPE_SIZE (type
), TYPE_SIZE (prev_type
))
1597 : !integer_zerop (DECL_SIZE (field
))))
1599 /* Never smaller than a byte for compatibility. */
1600 unsigned int type_align
= BITS_PER_UNIT
;
1602 /* (When not a bitfield), we could be seeing a flex array (with
1603 no DECL_SIZE). Since we won't be using remaining_in_alignment
1604 until we see a bitfield (and come by here again) we just skip
1606 if (DECL_SIZE (field
) != NULL
1607 && tree_fits_uhwi_p (TYPE_SIZE (TREE_TYPE (field
)))
1608 && tree_fits_uhwi_p (DECL_SIZE (field
)))
1610 unsigned HOST_WIDE_INT bitsize
1611 = tree_to_uhwi (DECL_SIZE (field
));
1612 unsigned HOST_WIDE_INT typesize
1613 = tree_to_uhwi (TYPE_SIZE (TREE_TYPE (field
)));
1615 if (typesize
< bitsize
)
1616 rli
->remaining_in_alignment
= 0;
1618 rli
->remaining_in_alignment
= typesize
- bitsize
;
1621 /* Now align (conventionally) for the new type. */
1622 if (! DECL_PACKED (field
))
1623 type_align
= TYPE_ALIGN (TREE_TYPE (field
));
1625 if (maximum_field_alignment
!= 0)
1626 type_align
= MIN (type_align
, maximum_field_alignment
);
1628 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1630 /* If we really aligned, don't allow subsequent bitfields
1632 rli
->prev_field
= NULL
;
1636 /* Offset so far becomes the position of this field after normalizing. */
1637 normalize_rli (rli
);
1638 DECL_FIELD_OFFSET (field
) = rli
->offset
;
1639 DECL_FIELD_BIT_OFFSET (field
) = rli
->bitpos
;
1640 SET_DECL_OFFSET_ALIGN (field
, rli
->offset_align
);
1641 handle_warn_if_not_align (field
, rli
->record_align
);
1643 /* Evaluate nonconstant offsets only once, either now or as soon as safe. */
1644 if (TREE_CODE (DECL_FIELD_OFFSET (field
)) != INTEGER_CST
)
1645 DECL_FIELD_OFFSET (field
) = variable_size (DECL_FIELD_OFFSET (field
));
1647 /* If this field ended up more aligned than we thought it would be (we
1648 approximate this by seeing if its position changed), lay out the field
1649 again; perhaps we can use an integral mode for it now. */
1650 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field
)))
1651 actual_align
= least_bit_hwi (tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field
)));
1652 else if (integer_zerop (DECL_FIELD_OFFSET (field
)))
1653 actual_align
= MAX (BIGGEST_ALIGNMENT
, rli
->record_align
);
1654 else if (tree_fits_uhwi_p (DECL_FIELD_OFFSET (field
)))
1655 actual_align
= (BITS_PER_UNIT
1656 * least_bit_hwi (tree_to_uhwi (DECL_FIELD_OFFSET (field
))));
1658 actual_align
= DECL_OFFSET_ALIGN (field
);
1659 /* ACTUAL_ALIGN is still the actual alignment *within the record* .
1660 store / extract bit field operations will check the alignment of the
1661 record against the mode of bit fields. */
1663 if (known_align
!= actual_align
)
1664 layout_decl (field
, actual_align
);
1666 if (rli
->prev_field
== NULL
&& DECL_BIT_FIELD_TYPE (field
))
1667 rli
->prev_field
= field
;
1669 /* Now add size of this field to the size of the record. If the size is
1670 not constant, treat the field as being a multiple of bytes and just
1671 adjust the offset, resetting the bit position. Otherwise, apportion the
1672 size amongst the bit position and offset. First handle the case of an
1673 unspecified size, which can happen when we have an invalid nested struct
1674 definition, such as struct j { struct j { int i; } }. The error message
1675 is printed in finish_struct. */
1676 if (DECL_SIZE (field
) == 0)
1678 else if (TREE_CODE (DECL_SIZE (field
)) != INTEGER_CST
1679 || TREE_OVERFLOW (DECL_SIZE (field
)))
1682 = size_binop (PLUS_EXPR
, rli
->offset
,
1683 fold_convert (sizetype
,
1684 size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
1685 bitsize_unit_node
)));
1687 = size_binop (PLUS_EXPR
, rli
->offset
, DECL_SIZE_UNIT (field
));
1688 rli
->bitpos
= bitsize_zero_node
;
1689 rli
->offset_align
= MIN (rli
->offset_align
, desired_align
);
1691 if (!multiple_of_p (bitsizetype
, DECL_SIZE (field
),
1692 bitsize_int (rli
->offset_align
)))
1694 tree type
= strip_array_types (TREE_TYPE (field
));
1695 /* The above adjusts offset_align just based on the start of the
1696 field. The field might not have a size that is a multiple of
1697 that offset_align though. If the field is an array of fixed
1698 sized elements, assume there can be any multiple of those
1699 sizes. If it is a variable length aggregate or array of
1700 variable length aggregates, assume worst that the end is
1701 just BITS_PER_UNIT aligned. */
1702 if (TREE_CODE (TYPE_SIZE (type
)) == INTEGER_CST
)
1704 if (TREE_INT_CST_LOW (TYPE_SIZE (type
)))
1706 unsigned HOST_WIDE_INT sz
1707 = least_bit_hwi (TREE_INT_CST_LOW (TYPE_SIZE (type
)));
1708 rli
->offset_align
= MIN (rli
->offset_align
, sz
);
1712 rli
->offset_align
= MIN (rli
->offset_align
, BITS_PER_UNIT
);
1715 else if (targetm
.ms_bitfield_layout_p (rli
->t
))
1717 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
, DECL_SIZE (field
));
1719 /* If FIELD is the last field and doesn't end at the full length
1720 of the type then pad the struct out to the full length of the
1722 if (DECL_BIT_FIELD_TYPE (field
)
1723 && !integer_zerop (DECL_SIZE (field
)))
1725 /* We have to scan, because non-field DECLS are also here. */
1727 while ((probe
= DECL_CHAIN (probe
)))
1728 if (TREE_CODE (probe
) == FIELD_DECL
)
1731 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
,
1732 bitsize_int (rli
->remaining_in_alignment
));
1735 normalize_rli (rli
);
1739 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
, DECL_SIZE (field
));
1740 normalize_rli (rli
);
1744 /* Assuming that all the fields have been laid out, this function uses
1745 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
1746 indicated by RLI. */
1749 finalize_record_size (record_layout_info rli
)
1751 tree unpadded_size
, unpadded_size_unit
;
1753 /* Now we want just byte and bit offsets, so set the offset alignment
1754 to be a byte and then normalize. */
1755 rli
->offset_align
= BITS_PER_UNIT
;
1756 normalize_rli (rli
);
1758 /* Determine the desired alignment. */
1759 #ifdef ROUND_TYPE_ALIGN
1760 SET_TYPE_ALIGN (rli
->t
, ROUND_TYPE_ALIGN (rli
->t
, TYPE_ALIGN (rli
->t
),
1761 rli
->record_align
));
1763 SET_TYPE_ALIGN (rli
->t
, MAX (TYPE_ALIGN (rli
->t
), rli
->record_align
));
1766 /* Compute the size so far. Be sure to allow for extra bits in the
1767 size in bytes. We have guaranteed above that it will be no more
1768 than a single byte. */
1769 unpadded_size
= rli_size_so_far (rli
);
1770 unpadded_size_unit
= rli_size_unit_so_far (rli
);
1771 if (! integer_zerop (rli
->bitpos
))
1773 = size_binop (PLUS_EXPR
, unpadded_size_unit
, size_one_node
);
1775 /* Round the size up to be a multiple of the required alignment. */
1776 TYPE_SIZE (rli
->t
) = round_up (unpadded_size
, TYPE_ALIGN (rli
->t
));
1777 TYPE_SIZE_UNIT (rli
->t
)
1778 = round_up (unpadded_size_unit
, TYPE_ALIGN_UNIT (rli
->t
));
1780 if (TREE_CONSTANT (unpadded_size
)
1781 && simple_cst_equal (unpadded_size
, TYPE_SIZE (rli
->t
)) == 0
1782 && input_location
!= BUILTINS_LOCATION
1783 && !TYPE_ARTIFICIAL (rli
->t
))
1784 warning (OPT_Wpadded
, "padding struct size to alignment boundary");
1786 if (warn_packed
&& TREE_CODE (rli
->t
) == RECORD_TYPE
1787 && TYPE_PACKED (rli
->t
) && ! rli
->packed_maybe_necessary
1788 && TREE_CONSTANT (unpadded_size
))
1792 #ifdef ROUND_TYPE_ALIGN
1794 = ROUND_TYPE_ALIGN (rli
->t
, TYPE_ALIGN (rli
->t
), rli
->unpacked_align
);
1796 rli
->unpacked_align
= MAX (TYPE_ALIGN (rli
->t
), rli
->unpacked_align
);
1799 unpacked_size
= round_up (TYPE_SIZE (rli
->t
), rli
->unpacked_align
);
1800 if (simple_cst_equal (unpacked_size
, TYPE_SIZE (rli
->t
)))
1802 if (TYPE_NAME (rli
->t
))
1806 if (TREE_CODE (TYPE_NAME (rli
->t
)) == IDENTIFIER_NODE
)
1807 name
= TYPE_NAME (rli
->t
);
1809 name
= DECL_NAME (TYPE_NAME (rli
->t
));
1811 if (STRICT_ALIGNMENT
)
1812 warning (OPT_Wpacked
, "packed attribute causes inefficient "
1813 "alignment for %qE", name
);
1815 warning (OPT_Wpacked
,
1816 "packed attribute is unnecessary for %qE", name
);
1820 if (STRICT_ALIGNMENT
)
1821 warning (OPT_Wpacked
,
1822 "packed attribute causes inefficient alignment");
1824 warning (OPT_Wpacked
, "packed attribute is unnecessary");
1830 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
1833 compute_record_mode (tree type
)
1836 machine_mode mode
= VOIDmode
;
1838 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
1839 However, if possible, we use a mode that fits in a register
1840 instead, in order to allow for better optimization down the
1842 SET_TYPE_MODE (type
, BLKmode
);
1844 poly_uint64 type_size
;
1845 if (!poly_int_tree_p (TYPE_SIZE (type
), &type_size
))
1848 /* A record which has any BLKmode members must itself be
1849 BLKmode; it can't go in a register. Unless the member is
1850 BLKmode only because it isn't aligned. */
1851 for (field
= TYPE_FIELDS (type
); field
; field
= DECL_CHAIN (field
))
1853 if (TREE_CODE (field
) != FIELD_DECL
)
1856 poly_uint64 field_size
;
1857 if (TREE_CODE (TREE_TYPE (field
)) == ERROR_MARK
1858 || (TYPE_MODE (TREE_TYPE (field
)) == BLKmode
1859 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field
))
1860 && !(TYPE_SIZE (TREE_TYPE (field
)) != 0
1861 && integer_zerop (TYPE_SIZE (TREE_TYPE (field
)))))
1862 || !tree_fits_poly_uint64_p (bit_position (field
))
1863 || DECL_SIZE (field
) == 0
1864 || !poly_int_tree_p (DECL_SIZE (field
), &field_size
))
1867 /* If this field is the whole struct, remember its mode so
1868 that, say, we can put a double in a class into a DF
1869 register instead of forcing it to live in the stack. */
1870 if (known_eq (field_size
, type_size
)
1871 /* Partial int types (e.g. __int20) may have TYPE_SIZE equal to
1872 wider types (e.g. int32), despite precision being less. Ensure
1873 that the TYPE_MODE of the struct does not get set to the partial
1874 int mode if there is a wider type also in the struct. */
1875 && known_gt (GET_MODE_PRECISION (DECL_MODE (field
)),
1876 GET_MODE_PRECISION (mode
)))
1877 mode
= DECL_MODE (field
);
1879 /* With some targets, it is sub-optimal to access an aligned
1880 BLKmode structure as a scalar. */
1881 if (targetm
.member_type_forces_blk (field
, mode
))
1885 /* If we only have one real field; use its mode if that mode's size
1886 matches the type's size. This generally only applies to RECORD_TYPE.
1887 For UNION_TYPE, if the widest field is MODE_INT then use that mode.
1888 If the widest field is MODE_PARTIAL_INT, and the union will be passed
1889 by reference, then use that mode. */
1890 if ((TREE_CODE (type
) == RECORD_TYPE
1891 || (TREE_CODE (type
) == UNION_TYPE
1892 && (GET_MODE_CLASS (mode
) == MODE_INT
1893 || (GET_MODE_CLASS (mode
) == MODE_PARTIAL_INT
1894 && (targetm
.calls
.pass_by_reference
1895 (pack_cumulative_args (0),
1896 function_arg_info (type
, mode
, /*named=*/false)))))))
1898 && known_eq (GET_MODE_BITSIZE (mode
), type_size
))
1901 mode
= mode_for_size_tree (TYPE_SIZE (type
), MODE_INT
, 1).else_blk ();
1903 /* If structure's known alignment is less than what the scalar
1904 mode would need, and it matters, then stick with BLKmode. */
1907 && ! (TYPE_ALIGN (type
) >= BIGGEST_ALIGNMENT
1908 || TYPE_ALIGN (type
) >= GET_MODE_ALIGNMENT (mode
)))
1910 /* If this is the only reason this type is BLKmode, then
1911 don't force containing types to be BLKmode. */
1912 TYPE_NO_FORCE_BLK (type
) = 1;
1916 SET_TYPE_MODE (type
, mode
);
1919 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1923 finalize_type_size (tree type
)
1925 /* Normally, use the alignment corresponding to the mode chosen.
1926 However, where strict alignment is not required, avoid
1927 over-aligning structures, since most compilers do not do this
1929 if (TYPE_MODE (type
) != BLKmode
1930 && TYPE_MODE (type
) != VOIDmode
1931 && (STRICT_ALIGNMENT
|| !AGGREGATE_TYPE_P (type
)))
1933 unsigned mode_align
= GET_MODE_ALIGNMENT (TYPE_MODE (type
));
1935 /* Don't override a larger alignment requirement coming from a user
1936 alignment of one of the fields. */
1937 if (mode_align
>= TYPE_ALIGN (type
))
1939 SET_TYPE_ALIGN (type
, mode_align
);
1940 TYPE_USER_ALIGN (type
) = 0;
1944 /* Do machine-dependent extra alignment. */
1945 #ifdef ROUND_TYPE_ALIGN
1946 SET_TYPE_ALIGN (type
,
1947 ROUND_TYPE_ALIGN (type
, TYPE_ALIGN (type
), BITS_PER_UNIT
));
1950 /* If we failed to find a simple way to calculate the unit size
1951 of the type, find it by division. */
1952 if (TYPE_SIZE_UNIT (type
) == 0 && TYPE_SIZE (type
) != 0)
1953 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1954 result will fit in sizetype. We will get more efficient code using
1955 sizetype, so we force a conversion. */
1956 TYPE_SIZE_UNIT (type
)
1957 = fold_convert (sizetype
,
1958 size_binop (FLOOR_DIV_EXPR
, TYPE_SIZE (type
),
1959 bitsize_unit_node
));
1961 if (TYPE_SIZE (type
) != 0)
1963 TYPE_SIZE (type
) = round_up (TYPE_SIZE (type
), TYPE_ALIGN (type
));
1964 TYPE_SIZE_UNIT (type
)
1965 = round_up (TYPE_SIZE_UNIT (type
), TYPE_ALIGN_UNIT (type
));
1968 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1969 if (TYPE_SIZE (type
) != 0 && TREE_CODE (TYPE_SIZE (type
)) != INTEGER_CST
)
1970 TYPE_SIZE (type
) = variable_size (TYPE_SIZE (type
));
1971 if (TYPE_SIZE_UNIT (type
) != 0
1972 && TREE_CODE (TYPE_SIZE_UNIT (type
)) != INTEGER_CST
)
1973 TYPE_SIZE_UNIT (type
) = variable_size (TYPE_SIZE_UNIT (type
));
1975 /* Handle empty records as per the x86-64 psABI. */
1976 TYPE_EMPTY_P (type
) = targetm
.calls
.empty_record_p (type
);
1978 /* Also layout any other variants of the type. */
1979 if (TYPE_NEXT_VARIANT (type
)
1980 || type
!= TYPE_MAIN_VARIANT (type
))
1983 /* Record layout info of this variant. */
1984 tree size
= TYPE_SIZE (type
);
1985 tree size_unit
= TYPE_SIZE_UNIT (type
);
1986 unsigned int align
= TYPE_ALIGN (type
);
1987 unsigned int precision
= TYPE_PRECISION (type
);
1988 unsigned int user_align
= TYPE_USER_ALIGN (type
);
1989 machine_mode mode
= TYPE_MODE (type
);
1990 bool empty_p
= TYPE_EMPTY_P (type
);
1992 /* Copy it into all variants. */
1993 for (variant
= TYPE_MAIN_VARIANT (type
);
1995 variant
= TYPE_NEXT_VARIANT (variant
))
1997 TYPE_SIZE (variant
) = size
;
1998 TYPE_SIZE_UNIT (variant
) = size_unit
;
1999 unsigned valign
= align
;
2000 if (TYPE_USER_ALIGN (variant
))
2001 valign
= MAX (valign
, TYPE_ALIGN (variant
));
2003 TYPE_USER_ALIGN (variant
) = user_align
;
2004 SET_TYPE_ALIGN (variant
, valign
);
2005 TYPE_PRECISION (variant
) = precision
;
2006 SET_TYPE_MODE (variant
, mode
);
2007 TYPE_EMPTY_P (variant
) = empty_p
;
2012 /* Return a new underlying object for a bitfield started with FIELD. */
2015 start_bitfield_representative (tree field
)
2017 tree repr
= make_node (FIELD_DECL
);
2018 DECL_FIELD_OFFSET (repr
) = DECL_FIELD_OFFSET (field
);
2019 /* Force the representative to begin at a BITS_PER_UNIT aligned
2020 boundary - C++ may use tail-padding of a base object to
2021 continue packing bits so the bitfield region does not start
2022 at bit zero (see g++.dg/abi/bitfield5.C for example).
2023 Unallocated bits may happen for other reasons as well,
2024 for example Ada which allows explicit bit-granular structure layout. */
2025 DECL_FIELD_BIT_OFFSET (repr
)
2026 = size_binop (BIT_AND_EXPR
,
2027 DECL_FIELD_BIT_OFFSET (field
),
2028 bitsize_int (~(BITS_PER_UNIT
- 1)));
2029 SET_DECL_OFFSET_ALIGN (repr
, DECL_OFFSET_ALIGN (field
));
2030 DECL_SIZE (repr
) = DECL_SIZE (field
);
2031 DECL_SIZE_UNIT (repr
) = DECL_SIZE_UNIT (field
);
2032 DECL_PACKED (repr
) = DECL_PACKED (field
);
2033 DECL_CONTEXT (repr
) = DECL_CONTEXT (field
);
2034 /* There are no indirect accesses to this field. If we introduce
2035 some then they have to use the record alias set. This makes
2036 sure to properly conflict with [indirect] accesses to addressable
2037 fields of the bitfield group. */
2038 DECL_NONADDRESSABLE_P (repr
) = 1;
2042 /* Finish up a bitfield group that was started by creating the underlying
2043 object REPR with the last field in the bitfield group FIELD. */
2046 finish_bitfield_representative (tree repr
, tree field
)
2048 unsigned HOST_WIDE_INT bitsize
, maxbitsize
;
2051 size
= size_diffop (DECL_FIELD_OFFSET (field
),
2052 DECL_FIELD_OFFSET (repr
));
2053 while (TREE_CODE (size
) == COMPOUND_EXPR
)
2054 size
= TREE_OPERAND (size
, 1);
2055 gcc_assert (tree_fits_uhwi_p (size
));
2056 bitsize
= (tree_to_uhwi (size
) * BITS_PER_UNIT
2057 + tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field
))
2058 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr
))
2059 + tree_to_uhwi (DECL_SIZE (field
)));
2061 /* Round up bitsize to multiples of BITS_PER_UNIT. */
2062 bitsize
= (bitsize
+ BITS_PER_UNIT
- 1) & ~(BITS_PER_UNIT
- 1);
2064 /* Now nothing tells us how to pad out bitsize ... */
2065 nextf
= DECL_CHAIN (field
);
2066 while (nextf
&& TREE_CODE (nextf
) != FIELD_DECL
)
2067 nextf
= DECL_CHAIN (nextf
);
2071 /* If there was an error, the field may be not laid out
2072 correctly. Don't bother to do anything. */
2073 if (TREE_TYPE (nextf
) == error_mark_node
)
2075 maxsize
= size_diffop (DECL_FIELD_OFFSET (nextf
),
2076 DECL_FIELD_OFFSET (repr
));
2077 if (tree_fits_uhwi_p (maxsize
))
2079 maxbitsize
= (tree_to_uhwi (maxsize
) * BITS_PER_UNIT
2080 + tree_to_uhwi (DECL_FIELD_BIT_OFFSET (nextf
))
2081 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr
)));
2082 /* If the group ends within a bitfield nextf does not need to be
2083 aligned to BITS_PER_UNIT. Thus round up. */
2084 maxbitsize
= (maxbitsize
+ BITS_PER_UNIT
- 1) & ~(BITS_PER_UNIT
- 1);
2087 maxbitsize
= bitsize
;
2091 /* Note that if the C++ FE sets up tail-padding to be re-used it
2092 creates a as-base variant of the type with TYPE_SIZE adjusted
2093 accordingly. So it is safe to include tail-padding here. */
2094 tree aggsize
= lang_hooks
.types
.unit_size_without_reusable_padding
2095 (DECL_CONTEXT (field
));
2096 tree maxsize
= size_diffop (aggsize
, DECL_FIELD_OFFSET (repr
));
2097 /* We cannot generally rely on maxsize to fold to an integer constant,
2098 so use bitsize as fallback for this case. */
2099 if (tree_fits_uhwi_p (maxsize
))
2100 maxbitsize
= (tree_to_uhwi (maxsize
) * BITS_PER_UNIT
2101 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr
)));
2103 maxbitsize
= bitsize
;
2106 /* Only if we don't artificially break up the representative in
2107 the middle of a large bitfield with different possibly
2108 overlapping representatives. And all representatives start
2110 gcc_assert (maxbitsize
% BITS_PER_UNIT
== 0);
2112 /* Find the smallest nice mode to use. */
2113 opt_scalar_int_mode mode_iter
;
2114 FOR_EACH_MODE_IN_CLASS (mode_iter
, MODE_INT
)
2115 if (GET_MODE_BITSIZE (mode_iter
.require ()) >= bitsize
)
2118 scalar_int_mode mode
;
2119 if (!mode_iter
.exists (&mode
)
2120 || GET_MODE_BITSIZE (mode
) > maxbitsize
2121 || GET_MODE_BITSIZE (mode
) > MAX_FIXED_MODE_SIZE
)
2123 /* We really want a BLKmode representative only as a last resort,
2124 considering the member b in
2125 struct { int a : 7; int b : 17; int c; } __attribute__((packed));
2126 Otherwise we simply want to split the representative up
2127 allowing for overlaps within the bitfield region as required for
2128 struct { int a : 7; int b : 7;
2129 int c : 10; int d; } __attribute__((packed));
2130 [0, 15] HImode for a and b, [8, 23] HImode for c. */
2131 DECL_SIZE (repr
) = bitsize_int (bitsize
);
2132 DECL_SIZE_UNIT (repr
) = size_int (bitsize
/ BITS_PER_UNIT
);
2133 SET_DECL_MODE (repr
, BLKmode
);
2134 TREE_TYPE (repr
) = build_array_type_nelts (unsigned_char_type_node
,
2135 bitsize
/ BITS_PER_UNIT
);
2139 unsigned HOST_WIDE_INT modesize
= GET_MODE_BITSIZE (mode
);
2140 DECL_SIZE (repr
) = bitsize_int (modesize
);
2141 DECL_SIZE_UNIT (repr
) = size_int (modesize
/ BITS_PER_UNIT
);
2142 SET_DECL_MODE (repr
, mode
);
2143 TREE_TYPE (repr
) = lang_hooks
.types
.type_for_mode (mode
, 1);
2146 /* Remember whether the bitfield group is at the end of the
2147 structure or not. */
2148 DECL_CHAIN (repr
) = nextf
;
2151 /* Compute and set FIELD_DECLs for the underlying objects we should
2152 use for bitfield access for the structure T. */
2155 finish_bitfield_layout (tree t
)
2158 tree repr
= NULL_TREE
;
2160 /* Unions would be special, for the ease of type-punning optimizations
2161 we could use the underlying type as hint for the representative
2162 if the bitfield would fit and the representative would not exceed
2163 the union in size. */
2164 if (TREE_CODE (t
) != RECORD_TYPE
)
2167 for (prev
= NULL_TREE
, field
= TYPE_FIELDS (t
);
2168 field
; field
= DECL_CHAIN (field
))
2170 if (TREE_CODE (field
) != FIELD_DECL
)
2173 /* In the C++ memory model, consecutive bit fields in a structure are
2174 considered one memory location and updating a memory location
2175 may not store into adjacent memory locations. */
2177 && DECL_BIT_FIELD_TYPE (field
))
2179 /* Start new representative. */
2180 repr
= start_bitfield_representative (field
);
2183 && ! DECL_BIT_FIELD_TYPE (field
))
2185 /* Finish off new representative. */
2186 finish_bitfield_representative (repr
, prev
);
2189 else if (DECL_BIT_FIELD_TYPE (field
))
2191 gcc_assert (repr
!= NULL_TREE
);
2193 /* Zero-size bitfields finish off a representative and
2194 do not have a representative themselves. This is
2195 required by the C++ memory model. */
2196 if (integer_zerop (DECL_SIZE (field
)))
2198 finish_bitfield_representative (repr
, prev
);
2202 /* We assume that either DECL_FIELD_OFFSET of the representative
2203 and each bitfield member is a constant or they are equal.
2204 This is because we need to be able to compute the bit-offset
2205 of each field relative to the representative in get_bit_range
2206 during RTL expansion.
2207 If these constraints are not met, simply force a new
2208 representative to be generated. That will at most
2209 generate worse code but still maintain correctness with
2210 respect to the C++ memory model. */
2211 else if (!((tree_fits_uhwi_p (DECL_FIELD_OFFSET (repr
))
2212 && tree_fits_uhwi_p (DECL_FIELD_OFFSET (field
)))
2213 || operand_equal_p (DECL_FIELD_OFFSET (repr
),
2214 DECL_FIELD_OFFSET (field
), 0)))
2216 finish_bitfield_representative (repr
, prev
);
2217 repr
= start_bitfield_representative (field
);
2224 DECL_BIT_FIELD_REPRESENTATIVE (field
) = repr
;
2230 finish_bitfield_representative (repr
, prev
);
2233 /* Do all of the work required to layout the type indicated by RLI,
2234 once the fields have been laid out. This function will call `free'
2235 for RLI, unless FREE_P is false. Passing a value other than false
2236 for FREE_P is bad practice; this option only exists to support the
2240 finish_record_layout (record_layout_info rli
, int free_p
)
2244 /* Compute the final size. */
2245 finalize_record_size (rli
);
2247 /* Compute the TYPE_MODE for the record. */
2248 compute_record_mode (rli
->t
);
2250 /* Perform any last tweaks to the TYPE_SIZE, etc. */
2251 finalize_type_size (rli
->t
);
2253 /* Compute bitfield representatives. */
2254 finish_bitfield_layout (rli
->t
);
2256 /* Propagate TYPE_PACKED and TYPE_REVERSE_STORAGE_ORDER to variants.
2257 With C++ templates, it is too early to do this when the attribute
2259 for (variant
= TYPE_NEXT_VARIANT (rli
->t
); variant
;
2260 variant
= TYPE_NEXT_VARIANT (variant
))
2262 TYPE_PACKED (variant
) = TYPE_PACKED (rli
->t
);
2263 TYPE_REVERSE_STORAGE_ORDER (variant
)
2264 = TYPE_REVERSE_STORAGE_ORDER (rli
->t
);
2267 /* Lay out any static members. This is done now because their type
2268 may use the record's type. */
2269 while (!vec_safe_is_empty (rli
->pending_statics
))
2270 layout_decl (rli
->pending_statics
->pop (), 0);
2275 vec_free (rli
->pending_statics
);
2281 /* Finish processing a builtin RECORD_TYPE type TYPE. It's name is
2282 NAME, its fields are chained in reverse on FIELDS.
2284 If ALIGN_TYPE is non-null, it is given the same alignment as
2288 finish_builtin_struct (tree type
, const char *name
, tree fields
,
2293 for (tail
= NULL_TREE
; fields
; tail
= fields
, fields
= next
)
2295 DECL_FIELD_CONTEXT (fields
) = type
;
2296 next
= DECL_CHAIN (fields
);
2297 DECL_CHAIN (fields
) = tail
;
2299 TYPE_FIELDS (type
) = tail
;
2303 SET_TYPE_ALIGN (type
, TYPE_ALIGN (align_type
));
2304 TYPE_USER_ALIGN (type
) = TYPE_USER_ALIGN (align_type
);
2305 SET_TYPE_WARN_IF_NOT_ALIGN (type
,
2306 TYPE_WARN_IF_NOT_ALIGN (align_type
));
2310 #if 0 /* not yet, should get fixed properly later */
2311 TYPE_NAME (type
) = make_type_decl (get_identifier (name
), type
);
2313 TYPE_NAME (type
) = build_decl (BUILTINS_LOCATION
,
2314 TYPE_DECL
, get_identifier (name
), type
);
2316 TYPE_STUB_DECL (type
) = TYPE_NAME (type
);
2317 layout_decl (TYPE_NAME (type
), 0);
2320 /* Calculate the mode, size, and alignment for TYPE.
2321 For an array type, calculate the element separation as well.
2322 Record TYPE on the chain of permanent or temporary types
2323 so that dbxout will find out about it.
2325 TYPE_SIZE of a type is nonzero if the type has been laid out already.
2326 layout_type does nothing on such a type.
2328 If the type is incomplete, its TYPE_SIZE remains zero. */
2331 layout_type (tree type
)
2335 if (type
== error_mark_node
)
2338 /* We don't want finalize_type_size to copy an alignment attribute to
2339 variants that don't have it. */
2340 type
= TYPE_MAIN_VARIANT (type
);
2342 /* Do nothing if type has been laid out before. */
2343 if (TYPE_SIZE (type
))
2346 switch (TREE_CODE (type
))
2349 /* This kind of type is the responsibility
2350 of the language-specific code. */
2357 scalar_int_mode mode
2358 = smallest_int_mode_for_size (TYPE_PRECISION (type
));
2359 SET_TYPE_MODE (type
, mode
);
2360 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2361 /* Don't set TYPE_PRECISION here, as it may be set by a bitfield. */
2362 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2368 /* Allow the caller to choose the type mode, which is how decimal
2369 floats are distinguished from binary ones. */
2370 if (TYPE_MODE (type
) == VOIDmode
)
2372 (type
, float_mode_for_size (TYPE_PRECISION (type
)).require ());
2373 scalar_float_mode mode
= as_a
<scalar_float_mode
> (TYPE_MODE (type
));
2374 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2375 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2379 case FIXED_POINT_TYPE
:
2381 /* TYPE_MODE (type) has been set already. */
2382 scalar_mode mode
= SCALAR_TYPE_MODE (type
);
2383 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2384 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2389 TYPE_UNSIGNED (type
) = TYPE_UNSIGNED (TREE_TYPE (type
));
2390 SET_TYPE_MODE (type
,
2391 GET_MODE_COMPLEX_MODE (TYPE_MODE (TREE_TYPE (type
))));
2393 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
2394 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
2399 poly_uint64 nunits
= TYPE_VECTOR_SUBPARTS (type
);
2400 tree innertype
= TREE_TYPE (type
);
2402 /* Find an appropriate mode for the vector type. */
2403 if (TYPE_MODE (type
) == VOIDmode
)
2404 SET_TYPE_MODE (type
,
2405 mode_for_vector (SCALAR_TYPE_MODE (innertype
),
2406 nunits
).else_blk ());
2408 TYPE_SATURATING (type
) = TYPE_SATURATING (TREE_TYPE (type
));
2409 TYPE_UNSIGNED (type
) = TYPE_UNSIGNED (TREE_TYPE (type
));
2410 /* Several boolean vector elements may fit in a single unit. */
2411 if (VECTOR_BOOLEAN_TYPE_P (type
)
2412 && type
->type_common
.mode
!= BLKmode
)
2413 TYPE_SIZE_UNIT (type
)
2414 = size_int (GET_MODE_SIZE (type
->type_common
.mode
));
2416 TYPE_SIZE_UNIT (type
) = int_const_binop (MULT_EXPR
,
2417 TYPE_SIZE_UNIT (innertype
),
2419 TYPE_SIZE (type
) = int_const_binop
2421 bits_from_bytes (TYPE_SIZE_UNIT (type
)),
2422 bitsize_int (BITS_PER_UNIT
));
2424 /* For vector types, we do not default to the mode's alignment.
2425 Instead, query a target hook, defaulting to natural alignment.
2426 This prevents ABI changes depending on whether or not native
2427 vector modes are supported. */
2428 SET_TYPE_ALIGN (type
, targetm
.vector_alignment (type
));
2430 /* However, if the underlying mode requires a bigger alignment than
2431 what the target hook provides, we cannot use the mode. For now,
2432 simply reject that case. */
2433 gcc_assert (TYPE_ALIGN (type
)
2434 >= GET_MODE_ALIGNMENT (TYPE_MODE (type
)));
2439 /* This is an incomplete type and so doesn't have a size. */
2440 SET_TYPE_ALIGN (type
, 1);
2441 TYPE_USER_ALIGN (type
) = 0;
2442 SET_TYPE_MODE (type
, VOIDmode
);
2446 TYPE_SIZE (type
) = bitsize_int (POINTER_SIZE
);
2447 TYPE_SIZE_UNIT (type
) = size_int (POINTER_SIZE_UNITS
);
2448 /* A pointer might be MODE_PARTIAL_INT, but ptrdiff_t must be
2449 integral, which may be an __intN. */
2450 SET_TYPE_MODE (type
, int_mode_for_size (POINTER_SIZE
, 0).require ());
2451 TYPE_PRECISION (type
) = POINTER_SIZE
;
2456 /* It's hard to see what the mode and size of a function ought to
2457 be, but we do know the alignment is FUNCTION_BOUNDARY, so
2458 make it consistent with that. */
2459 SET_TYPE_MODE (type
,
2460 int_mode_for_size (FUNCTION_BOUNDARY
, 0).else_blk ());
2461 TYPE_SIZE (type
) = bitsize_int (FUNCTION_BOUNDARY
);
2462 TYPE_SIZE_UNIT (type
) = size_int (FUNCTION_BOUNDARY
/ BITS_PER_UNIT
);
2466 case REFERENCE_TYPE
:
2468 scalar_int_mode mode
= SCALAR_INT_TYPE_MODE (type
);
2469 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2470 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2471 TYPE_UNSIGNED (type
) = 1;
2472 TYPE_PRECISION (type
) = GET_MODE_PRECISION (mode
);
2478 tree index
= TYPE_DOMAIN (type
);
2479 tree element
= TREE_TYPE (type
);
2481 /* We need to know both bounds in order to compute the size. */
2482 if (index
&& TYPE_MAX_VALUE (index
) && TYPE_MIN_VALUE (index
)
2483 && TYPE_SIZE (element
))
2485 tree ub
= TYPE_MAX_VALUE (index
);
2486 tree lb
= TYPE_MIN_VALUE (index
);
2487 tree element_size
= TYPE_SIZE (element
);
2490 /* Make sure that an array of zero-sized element is zero-sized
2491 regardless of its extent. */
2492 if (integer_zerop (element_size
))
2493 length
= size_zero_node
;
2495 /* The computation should happen in the original signedness so
2496 that (possible) negative values are handled appropriately
2497 when determining overflow. */
2500 /* ??? When it is obvious that the range is signed
2501 represent it using ssizetype. */
2502 if (TREE_CODE (lb
) == INTEGER_CST
2503 && TREE_CODE (ub
) == INTEGER_CST
2504 && TYPE_UNSIGNED (TREE_TYPE (lb
))
2505 && tree_int_cst_lt (ub
, lb
))
2507 lb
= wide_int_to_tree (ssizetype
,
2508 offset_int::from (wi::to_wide (lb
),
2510 ub
= wide_int_to_tree (ssizetype
,
2511 offset_int::from (wi::to_wide (ub
),
2515 = fold_convert (sizetype
,
2516 size_binop (PLUS_EXPR
,
2517 build_int_cst (TREE_TYPE (lb
), 1),
2518 size_binop (MINUS_EXPR
, ub
, lb
)));
2521 /* ??? We have no way to distinguish a null-sized array from an
2522 array spanning the whole sizetype range, so we arbitrarily
2523 decide that [0, -1] is the only valid representation. */
2524 if (integer_zerop (length
)
2525 && TREE_OVERFLOW (length
)
2526 && integer_zerop (lb
))
2527 length
= size_zero_node
;
2529 TYPE_SIZE (type
) = size_binop (MULT_EXPR
, element_size
,
2530 bits_from_bytes (length
));
2532 /* If we know the size of the element, calculate the total size
2533 directly, rather than do some division thing below. This
2534 optimization helps Fortran assumed-size arrays (where the
2535 size of the array is determined at runtime) substantially. */
2536 if (TYPE_SIZE_UNIT (element
))
2537 TYPE_SIZE_UNIT (type
)
2538 = size_binop (MULT_EXPR
, TYPE_SIZE_UNIT (element
), length
);
2541 /* Now round the alignment and size,
2542 using machine-dependent criteria if any. */
2544 unsigned align
= TYPE_ALIGN (element
);
2545 if (TYPE_USER_ALIGN (type
))
2546 align
= MAX (align
, TYPE_ALIGN (type
));
2548 TYPE_USER_ALIGN (type
) = TYPE_USER_ALIGN (element
);
2549 if (!TYPE_WARN_IF_NOT_ALIGN (type
))
2550 SET_TYPE_WARN_IF_NOT_ALIGN (type
,
2551 TYPE_WARN_IF_NOT_ALIGN (element
));
2552 #ifdef ROUND_TYPE_ALIGN
2553 align
= ROUND_TYPE_ALIGN (type
, align
, BITS_PER_UNIT
);
2555 align
= MAX (align
, BITS_PER_UNIT
);
2557 SET_TYPE_ALIGN (type
, align
);
2558 SET_TYPE_MODE (type
, BLKmode
);
2559 if (TYPE_SIZE (type
) != 0
2560 && ! targetm
.member_type_forces_blk (type
, VOIDmode
)
2561 /* BLKmode elements force BLKmode aggregate;
2562 else extract/store fields may lose. */
2563 && (TYPE_MODE (TREE_TYPE (type
)) != BLKmode
2564 || TYPE_NO_FORCE_BLK (TREE_TYPE (type
))))
2566 SET_TYPE_MODE (type
, mode_for_array (TREE_TYPE (type
),
2568 if (TYPE_MODE (type
) != BLKmode
2569 && STRICT_ALIGNMENT
&& TYPE_ALIGN (type
) < BIGGEST_ALIGNMENT
2570 && TYPE_ALIGN (type
) < GET_MODE_ALIGNMENT (TYPE_MODE (type
)))
2572 TYPE_NO_FORCE_BLK (type
) = 1;
2573 SET_TYPE_MODE (type
, BLKmode
);
2576 if (AGGREGATE_TYPE_P (element
))
2577 TYPE_TYPELESS_STORAGE (type
) = TYPE_TYPELESS_STORAGE (element
);
2578 /* When the element size is constant, check that it is at least as
2579 large as the element alignment. */
2580 if (TYPE_SIZE_UNIT (element
)
2581 && TREE_CODE (TYPE_SIZE_UNIT (element
)) == INTEGER_CST
2582 /* If TYPE_SIZE_UNIT overflowed, then it is certainly larger than
2584 && !TREE_OVERFLOW (TYPE_SIZE_UNIT (element
))
2585 && !integer_zerop (TYPE_SIZE_UNIT (element
)))
2587 if (compare_tree_int (TYPE_SIZE_UNIT (element
),
2588 TYPE_ALIGN_UNIT (element
)) < 0)
2589 error ("alignment of array elements is greater than "
2591 else if (TYPE_ALIGN_UNIT (element
) > 1
2592 && (wi::zext (wi::to_wide (TYPE_SIZE_UNIT (element
)),
2593 ffs_hwi (TYPE_ALIGN_UNIT (element
)) - 1)
2595 error ("size of array element is not a multiple of its "
2603 case QUAL_UNION_TYPE
:
2606 record_layout_info rli
;
2608 /* Initialize the layout information. */
2609 rli
= start_record_layout (type
);
2611 /* If this is a QUAL_UNION_TYPE, we want to process the fields
2612 in the reverse order in building the COND_EXPR that denotes
2613 its size. We reverse them again later. */
2614 if (TREE_CODE (type
) == QUAL_UNION_TYPE
)
2615 TYPE_FIELDS (type
) = nreverse (TYPE_FIELDS (type
));
2617 /* Place all the fields. */
2618 for (field
= TYPE_FIELDS (type
); field
; field
= DECL_CHAIN (field
))
2619 place_field (rli
, field
);
2621 if (TREE_CODE (type
) == QUAL_UNION_TYPE
)
2622 TYPE_FIELDS (type
) = nreverse (TYPE_FIELDS (type
));
2624 /* Finish laying out the record. */
2625 finish_record_layout (rli
, /*free_p=*/true);
2633 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
2634 records and unions, finish_record_layout already called this
2636 if (!RECORD_OR_UNION_TYPE_P (type
))
2637 finalize_type_size (type
);
2639 /* We should never see alias sets on incomplete aggregates. And we
2640 should not call layout_type on not incomplete aggregates. */
2641 if (AGGREGATE_TYPE_P (type
))
2642 gcc_assert (!TYPE_ALIAS_SET_KNOWN_P (type
));
2645 /* Return the least alignment required for type TYPE. */
2648 min_align_of_type (tree type
)
2650 unsigned int align
= TYPE_ALIGN (type
);
2651 if (!TYPE_USER_ALIGN (type
))
2653 align
= MIN (align
, BIGGEST_ALIGNMENT
);
2654 #ifdef BIGGEST_FIELD_ALIGNMENT
2655 align
= MIN (align
, BIGGEST_FIELD_ALIGNMENT
);
2657 unsigned int field_align
= align
;
2658 #ifdef ADJUST_FIELD_ALIGN
2659 field_align
= ADJUST_FIELD_ALIGN (NULL_TREE
, type
, field_align
);
2661 align
= MIN (align
, field_align
);
2663 return align
/ BITS_PER_UNIT
;
2666 /* Create and return a type for signed integers of PRECISION bits. */
2669 make_signed_type (int precision
)
2671 tree type
= make_node (INTEGER_TYPE
);
2673 TYPE_PRECISION (type
) = precision
;
2675 fixup_signed_type (type
);
2679 /* Create and return a type for unsigned integers of PRECISION bits. */
2682 make_unsigned_type (int precision
)
2684 tree type
= make_node (INTEGER_TYPE
);
2686 TYPE_PRECISION (type
) = precision
;
2688 fixup_unsigned_type (type
);
2692 /* Create and return a type for fract of PRECISION bits, UNSIGNEDP,
2696 make_fract_type (int precision
, int unsignedp
, int satp
)
2698 tree type
= make_node (FIXED_POINT_TYPE
);
2700 TYPE_PRECISION (type
) = precision
;
2703 TYPE_SATURATING (type
) = 1;
2705 /* Lay out the type: set its alignment, size, etc. */
2706 TYPE_UNSIGNED (type
) = unsignedp
;
2707 enum mode_class mclass
= unsignedp
? MODE_UFRACT
: MODE_FRACT
;
2708 SET_TYPE_MODE (type
, mode_for_size (precision
, mclass
, 0).require ());
2714 /* Create and return a type for accum of PRECISION bits, UNSIGNEDP,
2718 make_accum_type (int precision
, int unsignedp
, int satp
)
2720 tree type
= make_node (FIXED_POINT_TYPE
);
2722 TYPE_PRECISION (type
) = precision
;
2725 TYPE_SATURATING (type
) = 1;
2727 /* Lay out the type: set its alignment, size, etc. */
2728 TYPE_UNSIGNED (type
) = unsignedp
;
2729 enum mode_class mclass
= unsignedp
? MODE_UACCUM
: MODE_ACCUM
;
2730 SET_TYPE_MODE (type
, mode_for_size (precision
, mclass
, 0).require ());
2736 /* Initialize sizetypes so layout_type can use them. */
2739 initialize_sizetypes (void)
2741 int precision
, bprecision
;
2743 /* Get sizetypes precision from the SIZE_TYPE target macro. */
2744 if (strcmp (SIZETYPE
, "unsigned int") == 0)
2745 precision
= INT_TYPE_SIZE
;
2746 else if (strcmp (SIZETYPE
, "long unsigned int") == 0)
2747 precision
= LONG_TYPE_SIZE
;
2748 else if (strcmp (SIZETYPE
, "long long unsigned int") == 0)
2749 precision
= LONG_LONG_TYPE_SIZE
;
2750 else if (strcmp (SIZETYPE
, "short unsigned int") == 0)
2751 precision
= SHORT_TYPE_SIZE
;
2757 for (i
= 0; i
< NUM_INT_N_ENTS
; i
++)
2758 if (int_n_enabled_p
[i
])
2760 char name
[50], altname
[50];
2761 sprintf (name
, "__int%d unsigned", int_n_data
[i
].bitsize
);
2762 sprintf (altname
, "__int%d__ unsigned", int_n_data
[i
].bitsize
);
2764 if (strcmp (name
, SIZETYPE
) == 0
2765 || strcmp (altname
, SIZETYPE
) == 0)
2767 precision
= int_n_data
[i
].bitsize
;
2770 if (precision
== -1)
2775 = MIN (precision
+ LOG2_BITS_PER_UNIT
+ 1, MAX_FIXED_MODE_SIZE
);
2776 bprecision
= GET_MODE_PRECISION (smallest_int_mode_for_size (bprecision
));
2777 if (bprecision
> HOST_BITS_PER_DOUBLE_INT
)
2778 bprecision
= HOST_BITS_PER_DOUBLE_INT
;
2780 /* Create stubs for sizetype and bitsizetype so we can create constants. */
2781 sizetype
= make_node (INTEGER_TYPE
);
2782 TYPE_NAME (sizetype
) = get_identifier ("sizetype");
2783 TYPE_PRECISION (sizetype
) = precision
;
2784 TYPE_UNSIGNED (sizetype
) = 1;
2785 bitsizetype
= make_node (INTEGER_TYPE
);
2786 TYPE_NAME (bitsizetype
) = get_identifier ("bitsizetype");
2787 TYPE_PRECISION (bitsizetype
) = bprecision
;
2788 TYPE_UNSIGNED (bitsizetype
) = 1;
2790 /* Now layout both types manually. */
2791 scalar_int_mode mode
= smallest_int_mode_for_size (precision
);
2792 SET_TYPE_MODE (sizetype
, mode
);
2793 SET_TYPE_ALIGN (sizetype
, GET_MODE_ALIGNMENT (TYPE_MODE (sizetype
)));
2794 TYPE_SIZE (sizetype
) = bitsize_int (precision
);
2795 TYPE_SIZE_UNIT (sizetype
) = size_int (GET_MODE_SIZE (mode
));
2796 set_min_and_max_values_for_integral_type (sizetype
, precision
, UNSIGNED
);
2798 mode
= smallest_int_mode_for_size (bprecision
);
2799 SET_TYPE_MODE (bitsizetype
, mode
);
2800 SET_TYPE_ALIGN (bitsizetype
, GET_MODE_ALIGNMENT (TYPE_MODE (bitsizetype
)));
2801 TYPE_SIZE (bitsizetype
) = bitsize_int (bprecision
);
2802 TYPE_SIZE_UNIT (bitsizetype
) = size_int (GET_MODE_SIZE (mode
));
2803 set_min_and_max_values_for_integral_type (bitsizetype
, bprecision
, UNSIGNED
);
2805 /* Create the signed variants of *sizetype. */
2806 ssizetype
= make_signed_type (TYPE_PRECISION (sizetype
));
2807 TYPE_NAME (ssizetype
) = get_identifier ("ssizetype");
2808 sbitsizetype
= make_signed_type (TYPE_PRECISION (bitsizetype
));
2809 TYPE_NAME (sbitsizetype
) = get_identifier ("sbitsizetype");
2812 /* TYPE is an integral type, i.e., an INTEGRAL_TYPE, ENUMERAL_TYPE
2813 or BOOLEAN_TYPE. Set TYPE_MIN_VALUE and TYPE_MAX_VALUE
2814 for TYPE, based on the PRECISION and whether or not the TYPE
2815 IS_UNSIGNED. PRECISION need not correspond to a width supported
2816 natively by the hardware; for example, on a machine with 8-bit,
2817 16-bit, and 32-bit register modes, PRECISION might be 7, 23, or
2821 set_min_and_max_values_for_integral_type (tree type
,
2825 /* For bitfields with zero width we end up creating integer types
2826 with zero precision. Don't assign any minimum/maximum values
2827 to those types, they don't have any valid value. */
2831 TYPE_MIN_VALUE (type
)
2832 = wide_int_to_tree (type
, wi::min_value (precision
, sgn
));
2833 TYPE_MAX_VALUE (type
)
2834 = wide_int_to_tree (type
, wi::max_value (precision
, sgn
));
2837 /* Set the extreme values of TYPE based on its precision in bits,
2838 then lay it out. Used when make_signed_type won't do
2839 because the tree code is not INTEGER_TYPE. */
2842 fixup_signed_type (tree type
)
2844 int precision
= TYPE_PRECISION (type
);
2846 set_min_and_max_values_for_integral_type (type
, precision
, SIGNED
);
2848 /* Lay out the type: set its alignment, size, etc. */
2852 /* Set the extreme values of TYPE based on its precision in bits,
2853 then lay it out. This is used both in `make_unsigned_type'
2854 and for enumeral types. */
2857 fixup_unsigned_type (tree type
)
2859 int precision
= TYPE_PRECISION (type
);
2861 TYPE_UNSIGNED (type
) = 1;
2863 set_min_and_max_values_for_integral_type (type
, precision
, UNSIGNED
);
2865 /* Lay out the type: set its alignment, size, etc. */
2869 /* Construct an iterator for a bitfield that spans BITSIZE bits,
2872 BITREGION_START is the bit position of the first bit in this
2873 sequence of bit fields. BITREGION_END is the last bit in this
2874 sequence. If these two fields are non-zero, we should restrict the
2875 memory access to that range. Otherwise, we are allowed to touch
2876 any adjacent non bit-fields.
2878 ALIGN is the alignment of the underlying object in bits.
2879 VOLATILEP says whether the bitfield is volatile. */
2881 bit_field_mode_iterator
2882 ::bit_field_mode_iterator (HOST_WIDE_INT bitsize
, HOST_WIDE_INT bitpos
,
2883 poly_int64 bitregion_start
,
2884 poly_int64 bitregion_end
,
2885 unsigned int align
, bool volatilep
)
2886 : m_mode (NARROWEST_INT_MODE
), m_bitsize (bitsize
),
2887 m_bitpos (bitpos
), m_bitregion_start (bitregion_start
),
2888 m_bitregion_end (bitregion_end
), m_align (align
),
2889 m_volatilep (volatilep
), m_count (0)
2891 if (known_eq (m_bitregion_end
, 0))
2893 /* We can assume that any aligned chunk of ALIGN bits that overlaps
2894 the bitfield is mapped and won't trap, provided that ALIGN isn't
2895 too large. The cap is the biggest required alignment for data,
2896 or at least the word size. And force one such chunk at least. */
2897 unsigned HOST_WIDE_INT units
2898 = MIN (align
, MAX (BIGGEST_ALIGNMENT
, BITS_PER_WORD
));
2901 HOST_WIDE_INT end
= bitpos
+ bitsize
+ units
- 1;
2902 m_bitregion_end
= end
- end
% units
- 1;
2906 /* Calls to this function return successively larger modes that can be used
2907 to represent the bitfield. Return true if another bitfield mode is
2908 available, storing it in *OUT_MODE if so. */
2911 bit_field_mode_iterator::next_mode (scalar_int_mode
*out_mode
)
2913 scalar_int_mode mode
;
2914 for (; m_mode
.exists (&mode
); m_mode
= GET_MODE_WIDER_MODE (mode
))
2916 unsigned int unit
= GET_MODE_BITSIZE (mode
);
2918 /* Skip modes that don't have full precision. */
2919 if (unit
!= GET_MODE_PRECISION (mode
))
2922 /* Stop if the mode is too wide to handle efficiently. */
2923 if (unit
> MAX_FIXED_MODE_SIZE
)
2926 /* Don't deliver more than one multiword mode; the smallest one
2928 if (m_count
> 0 && unit
> BITS_PER_WORD
)
2931 /* Skip modes that are too small. */
2932 unsigned HOST_WIDE_INT substart
= (unsigned HOST_WIDE_INT
) m_bitpos
% unit
;
2933 unsigned HOST_WIDE_INT subend
= substart
+ m_bitsize
;
2937 /* Stop if the mode goes outside the bitregion. */
2938 HOST_WIDE_INT start
= m_bitpos
- substart
;
2939 if (maybe_ne (m_bitregion_start
, 0)
2940 && maybe_lt (start
, m_bitregion_start
))
2942 HOST_WIDE_INT end
= start
+ unit
;
2943 if (maybe_gt (end
, m_bitregion_end
+ 1))
2946 /* Stop if the mode requires too much alignment. */
2947 if (GET_MODE_ALIGNMENT (mode
) > m_align
2948 && targetm
.slow_unaligned_access (mode
, m_align
))
2952 m_mode
= GET_MODE_WIDER_MODE (mode
);
2959 /* Return true if smaller modes are generally preferred for this kind
2963 bit_field_mode_iterator::prefer_smaller_modes ()
2966 ? targetm
.narrow_volatile_bitfield ()
2967 : !SLOW_BYTE_ACCESS
);
2970 /* Find the best machine mode to use when referencing a bit field of length
2971 BITSIZE bits starting at BITPOS.
2973 BITREGION_START is the bit position of the first bit in this
2974 sequence of bit fields. BITREGION_END is the last bit in this
2975 sequence. If these two fields are non-zero, we should restrict the
2976 memory access to that range. Otherwise, we are allowed to touch
2977 any adjacent non bit-fields.
2979 The chosen mode must have no more than LARGEST_MODE_BITSIZE bits.
2980 INT_MAX is a suitable value for LARGEST_MODE_BITSIZE if the caller
2981 doesn't want to apply a specific limit.
2983 If no mode meets all these conditions, we return VOIDmode.
2985 The underlying object is known to be aligned to a boundary of ALIGN bits.
2987 If VOLATILEP is false and SLOW_BYTE_ACCESS is false, we return the
2988 smallest mode meeting these conditions.
2990 If VOLATILEP is false and SLOW_BYTE_ACCESS is true, we return the
2991 largest mode (but a mode no wider than UNITS_PER_WORD) that meets
2994 If VOLATILEP is true the narrow_volatile_bitfields target hook is used to
2995 decide which of the above modes should be used. */
2998 get_best_mode (int bitsize
, int bitpos
,
2999 poly_uint64 bitregion_start
, poly_uint64 bitregion_end
,
3001 unsigned HOST_WIDE_INT largest_mode_bitsize
, bool volatilep
,
3002 scalar_int_mode
*best_mode
)
3004 bit_field_mode_iterator
iter (bitsize
, bitpos
, bitregion_start
,
3005 bitregion_end
, align
, volatilep
);
3006 scalar_int_mode mode
;
3008 while (iter
.next_mode (&mode
)
3009 /* ??? For historical reasons, reject modes that would normally
3010 receive greater alignment, even if unaligned accesses are
3011 acceptable. This has both advantages and disadvantages.
3012 Removing this check means that something like:
3014 struct s { unsigned int x; unsigned int y; };
3015 int f (struct s *s) { return s->x == 0 && s->y == 0; }
3017 can be implemented using a single load and compare on
3018 64-bit machines that have no alignment restrictions.
3019 For example, on powerpc64-linux-gnu, we would generate:
3041 However, accessing more than one field can make life harder
3042 for the gimple optimizers. For example, gcc.dg/vect/bb-slp-5.c
3043 has a series of unsigned short copies followed by a series of
3044 unsigned short comparisons. With this check, both the copies
3045 and comparisons remain 16-bit accesses and FRE is able
3046 to eliminate the latter. Without the check, the comparisons
3047 can be done using 2 64-bit operations, which FRE isn't able
3048 to handle in the same way.
3050 Either way, it would probably be worth disabling this check
3051 during expand. One particular example where removing the
3052 check would help is the get_best_mode call in store_bit_field.
3053 If we are given a memory bitregion of 128 bits that is aligned
3054 to a 64-bit boundary, and the bitfield we want to modify is
3055 in the second half of the bitregion, this check causes
3056 store_bitfield to turn the memory into a 64-bit reference
3057 to the _first_ half of the region. We later use
3058 adjust_bitfield_address to get a reference to the correct half,
3059 but doing so looks to adjust_bitfield_address as though we are
3060 moving past the end of the original object, so it drops the
3061 associated MEM_EXPR and MEM_OFFSET. Removing the check
3062 causes store_bit_field to keep a 128-bit memory reference,
3063 so that the final bitfield reference still has a MEM_EXPR
3065 && GET_MODE_ALIGNMENT (mode
) <= align
3066 && GET_MODE_BITSIZE (mode
) <= largest_mode_bitsize
)
3070 if (iter
.prefer_smaller_modes ())
3077 /* Gets minimal and maximal values for MODE (signed or unsigned depending on
3078 SIGN). The returned constants are made to be usable in TARGET_MODE. */
3081 get_mode_bounds (scalar_int_mode mode
, int sign
,
3082 scalar_int_mode target_mode
,
3083 rtx
*mmin
, rtx
*mmax
)
3085 unsigned size
= GET_MODE_PRECISION (mode
);
3086 unsigned HOST_WIDE_INT min_val
, max_val
;
3088 gcc_assert (size
<= HOST_BITS_PER_WIDE_INT
);
3090 /* Special case BImode, which has values 0 and STORE_FLAG_VALUE. */
3093 if (STORE_FLAG_VALUE
< 0)
3095 min_val
= STORE_FLAG_VALUE
;
3101 max_val
= STORE_FLAG_VALUE
;
3106 min_val
= -(HOST_WIDE_INT_1U
<< (size
- 1));
3107 max_val
= (HOST_WIDE_INT_1U
<< (size
- 1)) - 1;
3112 max_val
= (HOST_WIDE_INT_1U
<< (size
- 1) << 1) - 1;
3115 *mmin
= gen_int_mode (min_val
, target_mode
);
3116 *mmax
= gen_int_mode (max_val
, target_mode
);
3119 #include "gt-stor-layout.h"