1 /* C-compiler utilities for types and variables storage layout
2 Copyright (C) 1987-2023 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 /* Only check the broader vector_mode_supported_any_target_p here.
503 We'll filter through target-specific availability and
504 vector_mode_supported_p later in vector_type_mode. */
505 FOR_EACH_MODE_FROM (mode
, mode
)
506 if (known_eq (GET_MODE_NUNITS (mode
), nunits
)
507 && GET_MODE_INNER (mode
) == innermode
508 && targetm
.vector_mode_supported_any_target_p (mode
))
511 /* For integers, try mapping it to a same-sized scalar mode. */
512 if (GET_MODE_CLASS (innermode
) == MODE_INT
)
514 poly_uint64 nbits
= nunits
* GET_MODE_BITSIZE (innermode
);
515 if (int_mode_for_size (nbits
, 0).exists (&mode
)
516 && have_regs_of_mode
[mode
])
520 return opt_machine_mode ();
523 /* If a piece of code is using vector mode VECTOR_MODE and also wants
524 to operate on elements of mode ELEMENT_MODE, return the vector mode
525 it should use for those elements. If NUNITS is nonzero, ensure that
526 the mode has exactly NUNITS elements, otherwise pick whichever vector
527 size pairs the most naturally with VECTOR_MODE; this may mean choosing
528 a mode with a different size and/or number of elements, depending on
529 what the target prefers. Return an empty opt_machine_mode if there
530 is no supported vector mode with the required properties.
532 Unlike mode_for_vector. any returned mode is guaranteed to satisfy
533 both VECTOR_MODE_P and targetm.vector_mode_supported_p. */
536 related_vector_mode (machine_mode vector_mode
, scalar_mode element_mode
,
539 gcc_assert (VECTOR_MODE_P (vector_mode
));
540 return targetm
.vectorize
.related_mode (vector_mode
, element_mode
, nunits
);
543 /* If a piece of code is using vector mode VECTOR_MODE and also wants
544 to operate on integer vectors with the same element size and number
545 of elements, return the vector mode it should use. Return an empty
546 opt_machine_mode if there is no supported vector mode with the
549 Unlike mode_for_vector. any returned mode is guaranteed to satisfy
550 both VECTOR_MODE_P and targetm.vector_mode_supported_p. */
553 related_int_vector_mode (machine_mode vector_mode
)
555 gcc_assert (VECTOR_MODE_P (vector_mode
));
556 scalar_int_mode int_mode
;
557 if (int_mode_for_mode (GET_MODE_INNER (vector_mode
)).exists (&int_mode
))
558 return related_vector_mode (vector_mode
, int_mode
,
559 GET_MODE_NUNITS (vector_mode
));
560 return opt_machine_mode ();
563 /* Return the alignment of MODE. This will be bounded by 1 and
564 BIGGEST_ALIGNMENT. */
567 get_mode_alignment (machine_mode mode
)
569 return MIN (BIGGEST_ALIGNMENT
, MAX (1, mode_base_align
[mode
]*BITS_PER_UNIT
));
572 /* Return the natural mode of an array, given that it is SIZE bytes in
573 total and has elements of type ELEM_TYPE. */
576 mode_for_array (tree elem_type
, tree size
)
579 poly_uint64 int_size
, int_elem_size
;
580 unsigned HOST_WIDE_INT num_elems
;
583 /* One-element arrays get the component type's mode. */
584 elem_size
= TYPE_SIZE (elem_type
);
585 if (simple_cst_equal (size
, elem_size
))
586 return TYPE_MODE (elem_type
);
589 if (poly_int_tree_p (size
, &int_size
)
590 && poly_int_tree_p (elem_size
, &int_elem_size
)
591 && maybe_ne (int_elem_size
, 0U)
592 && constant_multiple_p (int_size
, int_elem_size
, &num_elems
))
594 machine_mode elem_mode
= TYPE_MODE (elem_type
);
596 if (targetm
.array_mode (elem_mode
, num_elems
).exists (&mode
))
598 if (targetm
.array_mode_supported_p (elem_mode
, num_elems
))
601 return mode_for_size_tree (size
, MODE_INT
, limit_p
).else_blk ();
604 /* Subroutine of layout_decl: Force alignment required for the data type.
605 But if the decl itself wants greater alignment, don't override that. */
608 do_type_align (tree type
, tree decl
)
610 if (TYPE_ALIGN (type
) > DECL_ALIGN (decl
))
612 SET_DECL_ALIGN (decl
, TYPE_ALIGN (type
));
613 if (TREE_CODE (decl
) == FIELD_DECL
)
614 DECL_USER_ALIGN (decl
) = TYPE_USER_ALIGN (type
);
616 if (TYPE_WARN_IF_NOT_ALIGN (type
) > DECL_WARN_IF_NOT_ALIGN (decl
))
617 SET_DECL_WARN_IF_NOT_ALIGN (decl
, TYPE_WARN_IF_NOT_ALIGN (type
));
620 /* Set the size, mode and alignment of a ..._DECL node.
621 TYPE_DECL does need this for C++.
622 Note that LABEL_DECL and CONST_DECL nodes do not need this,
623 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
624 Don't call layout_decl for them.
626 KNOWN_ALIGN is the amount of alignment we can assume this
627 decl has with no special effort. It is relevant only for FIELD_DECLs
628 and depends on the previous fields.
629 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
630 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
631 the record will be aligned to suit. */
634 layout_decl (tree decl
, unsigned int known_align
)
636 tree type
= TREE_TYPE (decl
);
637 enum tree_code code
= TREE_CODE (decl
);
639 location_t loc
= DECL_SOURCE_LOCATION (decl
);
641 if (code
== CONST_DECL
)
644 gcc_assert (code
== VAR_DECL
|| code
== PARM_DECL
|| code
== RESULT_DECL
645 || code
== TYPE_DECL
|| code
== FIELD_DECL
);
647 rtl
= DECL_RTL_IF_SET (decl
);
649 if (type
== error_mark_node
)
650 type
= void_type_node
;
652 /* Usually the size and mode come from the data type without change,
653 however, the front-end may set the explicit width of the field, so its
654 size may not be the same as the size of its type. This happens with
655 bitfields, of course (an `int' bitfield may be only 2 bits, say), but it
656 also happens with other fields. For example, the C++ front-end creates
657 zero-sized fields corresponding to empty base classes, and depends on
658 layout_type setting DECL_FIELD_BITPOS correctly for the field. Set the
659 size in bytes from the size in bits. If we have already set the mode,
660 don't set it again since we can be called twice for FIELD_DECLs. */
662 DECL_UNSIGNED (decl
) = TYPE_UNSIGNED (type
);
663 if (DECL_MODE (decl
) == VOIDmode
)
664 SET_DECL_MODE (decl
, TYPE_MODE (type
));
666 if (DECL_SIZE (decl
) == 0)
668 DECL_SIZE (decl
) = TYPE_SIZE (type
);
669 DECL_SIZE_UNIT (decl
) = TYPE_SIZE_UNIT (type
);
671 else if (DECL_SIZE_UNIT (decl
) == 0)
672 DECL_SIZE_UNIT (decl
)
673 = fold_convert_loc (loc
, sizetype
,
674 size_binop_loc (loc
, CEIL_DIV_EXPR
, DECL_SIZE (decl
),
677 if (code
!= FIELD_DECL
)
678 /* For non-fields, update the alignment from the type. */
679 do_type_align (type
, decl
);
681 /* For fields, it's a bit more complicated... */
683 bool old_user_align
= DECL_USER_ALIGN (decl
);
684 bool zero_bitfield
= false;
685 bool packed_p
= DECL_PACKED (decl
);
688 if (DECL_BIT_FIELD (decl
))
690 DECL_BIT_FIELD_TYPE (decl
) = type
;
692 /* A zero-length bit-field affects the alignment of the next
693 field. In essence such bit-fields are not influenced by
694 any packing due to #pragma pack or attribute packed. */
695 if (integer_zerop (DECL_SIZE (decl
))
696 && ! targetm
.ms_bitfield_layout_p (DECL_FIELD_CONTEXT (decl
)))
698 zero_bitfield
= true;
700 if (PCC_BITFIELD_TYPE_MATTERS
)
701 do_type_align (type
, decl
);
704 #ifdef EMPTY_FIELD_BOUNDARY
705 if (EMPTY_FIELD_BOUNDARY
> DECL_ALIGN (decl
))
707 SET_DECL_ALIGN (decl
, EMPTY_FIELD_BOUNDARY
);
708 DECL_USER_ALIGN (decl
) = 0;
714 /* See if we can use an ordinary integer mode for a bit-field.
715 Conditions are: a fixed size that is correct for another mode,
716 occupying a complete byte or bytes on proper boundary. */
717 if (TYPE_SIZE (type
) != 0
718 && TREE_CODE (TYPE_SIZE (type
)) == INTEGER_CST
719 && GET_MODE_CLASS (TYPE_MODE (type
)) == MODE_INT
)
722 if (mode_for_size_tree (DECL_SIZE (decl
),
723 MODE_INT
, 1).exists (&xmode
))
725 unsigned int xalign
= GET_MODE_ALIGNMENT (xmode
);
726 if (!(xalign
> BITS_PER_UNIT
&& DECL_PACKED (decl
))
727 && (known_align
== 0 || known_align
>= xalign
))
729 SET_DECL_ALIGN (decl
, MAX (xalign
, DECL_ALIGN (decl
)));
730 SET_DECL_MODE (decl
, xmode
);
731 DECL_BIT_FIELD (decl
) = 0;
736 /* Turn off DECL_BIT_FIELD if we won't need it set. */
737 if (TYPE_MODE (type
) == BLKmode
&& DECL_MODE (decl
) == BLKmode
738 && known_align
>= TYPE_ALIGN (type
)
739 && DECL_ALIGN (decl
) >= TYPE_ALIGN (type
))
740 DECL_BIT_FIELD (decl
) = 0;
742 else if (packed_p
&& DECL_USER_ALIGN (decl
))
743 /* Don't touch DECL_ALIGN. For other packed fields, go ahead and
744 round up; we'll reduce it again below. We want packing to
745 supersede USER_ALIGN inherited from the type, but defer to
746 alignment explicitly specified on the field decl. */;
748 do_type_align (type
, decl
);
750 /* If the field is packed and not explicitly aligned, give it the
751 minimum alignment. Note that do_type_align may set
752 DECL_USER_ALIGN, so we need to check old_user_align instead. */
755 SET_DECL_ALIGN (decl
, MIN (DECL_ALIGN (decl
), BITS_PER_UNIT
));
757 if (! packed_p
&& ! DECL_USER_ALIGN (decl
))
759 /* Some targets (i.e. i386, VMS) limit struct field alignment
760 to a lower boundary than alignment of variables unless
761 it was overridden by attribute aligned. */
762 #ifdef BIGGEST_FIELD_ALIGNMENT
763 SET_DECL_ALIGN (decl
, MIN (DECL_ALIGN (decl
),
764 (unsigned) BIGGEST_FIELD_ALIGNMENT
));
766 #ifdef ADJUST_FIELD_ALIGN
767 SET_DECL_ALIGN (decl
, ADJUST_FIELD_ALIGN (decl
, TREE_TYPE (decl
),
773 mfa
= initial_max_fld_align
* BITS_PER_UNIT
;
775 mfa
= maximum_field_alignment
;
776 /* Should this be controlled by DECL_USER_ALIGN, too? */
778 SET_DECL_ALIGN (decl
, MIN (DECL_ALIGN (decl
), mfa
));
781 /* Evaluate nonconstant size only once, either now or as soon as safe. */
782 if (DECL_SIZE (decl
) != 0 && TREE_CODE (DECL_SIZE (decl
)) != INTEGER_CST
)
783 DECL_SIZE (decl
) = variable_size (DECL_SIZE (decl
));
784 if (DECL_SIZE_UNIT (decl
) != 0
785 && TREE_CODE (DECL_SIZE_UNIT (decl
)) != INTEGER_CST
)
786 DECL_SIZE_UNIT (decl
) = variable_size (DECL_SIZE_UNIT (decl
));
788 /* If requested, warn about definitions of large data objects. */
789 if ((code
== PARM_DECL
|| (code
== VAR_DECL
&& !DECL_NONLOCAL_FRAME (decl
)))
790 && !DECL_EXTERNAL (decl
))
792 tree size
= DECL_SIZE_UNIT (decl
);
794 if (size
!= 0 && TREE_CODE (size
) == INTEGER_CST
)
796 /* -Wlarger-than= argument of HOST_WIDE_INT_MAX is treated
797 as if PTRDIFF_MAX had been specified, with the value
798 being that on the target rather than the host. */
799 unsigned HOST_WIDE_INT max_size
= warn_larger_than_size
;
800 if (max_size
== HOST_WIDE_INT_MAX
)
801 max_size
= tree_to_shwi (TYPE_MAX_VALUE (ptrdiff_type_node
));
803 if (compare_tree_int (size
, max_size
) > 0)
804 warning (OPT_Wlarger_than_
, "size of %q+D %E bytes exceeds "
805 "maximum object size %wu",
806 decl
, size
, max_size
);
810 /* If the RTL was already set, update its mode and mem attributes. */
813 PUT_MODE (rtl
, DECL_MODE (decl
));
814 SET_DECL_RTL (decl
, 0);
816 set_mem_attributes (rtl
, decl
, 1);
817 SET_DECL_RTL (decl
, rtl
);
821 /* Given a VAR_DECL, PARM_DECL, RESULT_DECL, or FIELD_DECL, clears the
822 results of a previous call to layout_decl and calls it again. */
825 relayout_decl (tree decl
)
827 DECL_SIZE (decl
) = DECL_SIZE_UNIT (decl
) = 0;
828 SET_DECL_MODE (decl
, VOIDmode
);
829 if (!DECL_USER_ALIGN (decl
))
830 SET_DECL_ALIGN (decl
, 0);
831 if (DECL_RTL_SET_P (decl
))
832 SET_DECL_RTL (decl
, 0);
834 layout_decl (decl
, 0);
837 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
838 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
839 is to be passed to all other layout functions for this record. It is the
840 responsibility of the caller to call `free' for the storage returned.
841 Note that garbage collection is not permitted until we finish laying
845 start_record_layout (tree t
)
847 record_layout_info rli
= XNEW (struct record_layout_info_s
);
851 /* If the type has a minimum specified alignment (via an attribute
852 declaration, for example) use it -- otherwise, start with a
853 one-byte alignment. */
854 rli
->record_align
= MAX (BITS_PER_UNIT
, TYPE_ALIGN (t
));
855 rli
->unpacked_align
= rli
->record_align
;
856 rli
->offset_align
= MAX (rli
->record_align
, BIGGEST_ALIGNMENT
);
858 #ifdef STRUCTURE_SIZE_BOUNDARY
859 /* Packed structures don't need to have minimum size. */
860 if (! TYPE_PACKED (t
))
864 /* #pragma pack overrides STRUCTURE_SIZE_BOUNDARY. */
865 tmp
= (unsigned) STRUCTURE_SIZE_BOUNDARY
;
866 if (maximum_field_alignment
!= 0)
867 tmp
= MIN (tmp
, maximum_field_alignment
);
868 rli
->record_align
= MAX (rli
->record_align
, tmp
);
872 rli
->offset
= size_zero_node
;
873 rli
->bitpos
= bitsize_zero_node
;
875 rli
->pending_statics
= 0;
876 rli
->packed_maybe_necessary
= 0;
877 rli
->remaining_in_alignment
= 0;
882 /* Fold sizetype value X to bitsizetype, given that X represents a type
886 bits_from_bytes (tree x
)
888 if (POLY_INT_CST_P (x
))
889 /* The runtime calculation isn't allowed to overflow sizetype;
890 increasing the runtime values must always increase the size
891 or offset of the object. This means that the object imposes
892 a maximum value on the runtime parameters, but we don't record
894 return build_poly_int_cst
896 poly_wide_int::from (poly_int_cst_value (x
),
897 TYPE_PRECISION (bitsizetype
),
898 TYPE_SIGN (TREE_TYPE (x
))));
899 x
= fold_convert (bitsizetype
, x
);
900 gcc_checking_assert (x
);
904 /* Return the combined bit position for the byte offset OFFSET and the
907 These functions operate on byte and bit positions present in FIELD_DECLs
908 and assume that these expressions result in no (intermediate) overflow.
909 This assumption is necessary to fold the expressions as much as possible,
910 so as to avoid creating artificially variable-sized types in languages
911 supporting variable-sized types like Ada. */
914 bit_from_pos (tree offset
, tree bitpos
)
916 return size_binop (PLUS_EXPR
, bitpos
,
917 size_binop (MULT_EXPR
, bits_from_bytes (offset
),
921 /* Return the combined truncated byte position for the byte offset OFFSET and
922 the bit position BITPOS. */
925 byte_from_pos (tree offset
, tree bitpos
)
928 if (TREE_CODE (bitpos
) == MULT_EXPR
929 && tree_int_cst_equal (TREE_OPERAND (bitpos
, 1), bitsize_unit_node
))
930 bytepos
= TREE_OPERAND (bitpos
, 0);
932 bytepos
= size_binop (TRUNC_DIV_EXPR
, bitpos
, bitsize_unit_node
);
933 return size_binop (PLUS_EXPR
, offset
, fold_convert (sizetype
, bytepos
));
936 /* Split the bit position POS into a byte offset *POFFSET and a bit
937 position *PBITPOS with the byte offset aligned to OFF_ALIGN bits. */
940 pos_from_bit (tree
*poffset
, tree
*pbitpos
, unsigned int off_align
,
943 tree toff_align
= bitsize_int (off_align
);
944 if (TREE_CODE (pos
) == MULT_EXPR
945 && tree_int_cst_equal (TREE_OPERAND (pos
, 1), toff_align
))
947 *poffset
= size_binop (MULT_EXPR
,
948 fold_convert (sizetype
, TREE_OPERAND (pos
, 0)),
949 size_int (off_align
/ BITS_PER_UNIT
));
950 *pbitpos
= bitsize_zero_node
;
954 *poffset
= size_binop (MULT_EXPR
,
955 fold_convert (sizetype
,
956 size_binop (FLOOR_DIV_EXPR
, pos
,
958 size_int (off_align
/ BITS_PER_UNIT
));
959 *pbitpos
= size_binop (FLOOR_MOD_EXPR
, pos
, toff_align
);
963 /* Given a pointer to bit and byte offsets and an offset alignment,
964 normalize the offsets so they are within the alignment. */
967 normalize_offset (tree
*poffset
, tree
*pbitpos
, unsigned int off_align
)
969 /* If the bit position is now larger than it should be, adjust it
971 if (compare_tree_int (*pbitpos
, off_align
) >= 0)
974 pos_from_bit (&offset
, &bitpos
, off_align
, *pbitpos
);
975 *poffset
= size_binop (PLUS_EXPR
, *poffset
, offset
);
980 /* Print debugging information about the information in RLI. */
983 debug_rli (record_layout_info rli
)
985 print_node_brief (stderr
, "type", rli
->t
, 0);
986 print_node_brief (stderr
, "\noffset", rli
->offset
, 0);
987 print_node_brief (stderr
, " bitpos", rli
->bitpos
, 0);
989 fprintf (stderr
, "\naligns: rec = %u, unpack = %u, off = %u\n",
990 rli
->record_align
, rli
->unpacked_align
,
993 /* The ms_struct code is the only that uses this. */
994 if (targetm
.ms_bitfield_layout_p (rli
->t
))
995 fprintf (stderr
, "remaining in alignment = %u\n", rli
->remaining_in_alignment
);
997 if (rli
->packed_maybe_necessary
)
998 fprintf (stderr
, "packed may be necessary\n");
1000 if (!vec_safe_is_empty (rli
->pending_statics
))
1002 fprintf (stderr
, "pending statics:\n");
1003 debug (rli
->pending_statics
);
1007 /* Given an RLI with a possibly-incremented BITPOS, adjust OFFSET and
1008 BITPOS if necessary to keep BITPOS below OFFSET_ALIGN. */
1011 normalize_rli (record_layout_info rli
)
1013 normalize_offset (&rli
->offset
, &rli
->bitpos
, rli
->offset_align
);
1016 /* Returns the size in bytes allocated so far. */
1019 rli_size_unit_so_far (record_layout_info rli
)
1021 return byte_from_pos (rli
->offset
, rli
->bitpos
);
1024 /* Returns the size in bits allocated so far. */
1027 rli_size_so_far (record_layout_info rli
)
1029 return bit_from_pos (rli
->offset
, rli
->bitpos
);
1032 /* FIELD is about to be added to RLI->T. The alignment (in bits) of
1033 the next available location within the record is given by KNOWN_ALIGN.
1034 Update the variable alignment fields in RLI, and return the alignment
1035 to give the FIELD. */
1038 update_alignment_for_field (record_layout_info rli
, tree field
,
1039 unsigned int known_align
)
1041 /* The alignment required for FIELD. */
1042 unsigned int desired_align
;
1043 /* The type of this field. */
1044 tree type
= TREE_TYPE (field
);
1045 /* True if the field was explicitly aligned by the user. */
1049 /* Do not attempt to align an ERROR_MARK node */
1050 if (TREE_CODE (type
) == ERROR_MARK
)
1053 /* Lay out the field so we know what alignment it needs. */
1054 layout_decl (field
, known_align
);
1055 desired_align
= DECL_ALIGN (field
);
1056 user_align
= DECL_USER_ALIGN (field
);
1058 is_bitfield
= (type
!= error_mark_node
1059 && DECL_BIT_FIELD_TYPE (field
)
1060 && ! integer_zerop (TYPE_SIZE (type
)));
1062 /* Record must have at least as much alignment as any field.
1063 Otherwise, the alignment of the field within the record is
1065 if (targetm
.ms_bitfield_layout_p (rli
->t
))
1067 /* Here, the alignment of the underlying type of a bitfield can
1068 affect the alignment of a record; even a zero-sized field
1069 can do this. The alignment should be to the alignment of
1070 the type, except that for zero-size bitfields this only
1071 applies if there was an immediately prior, nonzero-size
1072 bitfield. (That's the way it is, experimentally.) */
1074 || ((DECL_SIZE (field
) == NULL_TREE
1075 || !integer_zerop (DECL_SIZE (field
)))
1076 ? !DECL_PACKED (field
)
1078 && DECL_BIT_FIELD_TYPE (rli
->prev_field
)
1079 && ! integer_zerop (DECL_SIZE (rli
->prev_field
)))))
1081 unsigned int type_align
= TYPE_ALIGN (type
);
1082 if (!is_bitfield
&& DECL_PACKED (field
))
1083 type_align
= desired_align
;
1085 type_align
= MAX (type_align
, desired_align
);
1086 if (maximum_field_alignment
!= 0)
1087 type_align
= MIN (type_align
, maximum_field_alignment
);
1088 rli
->record_align
= MAX (rli
->record_align
, type_align
);
1089 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
1092 else if (is_bitfield
&& PCC_BITFIELD_TYPE_MATTERS
)
1094 /* Named bit-fields cause the entire structure to have the
1095 alignment implied by their type. Some targets also apply the same
1096 rules to unnamed bitfields. */
1097 if (DECL_NAME (field
) != 0
1098 || targetm
.align_anon_bitfield ())
1100 unsigned int type_align
= TYPE_ALIGN (type
);
1102 #ifdef ADJUST_FIELD_ALIGN
1103 if (! TYPE_USER_ALIGN (type
))
1104 type_align
= ADJUST_FIELD_ALIGN (field
, type
, type_align
);
1107 /* Targets might chose to handle unnamed and hence possibly
1108 zero-width bitfield. Those are not influenced by #pragmas
1109 or packed attributes. */
1110 if (integer_zerop (DECL_SIZE (field
)))
1112 if (initial_max_fld_align
)
1113 type_align
= MIN (type_align
,
1114 initial_max_fld_align
* BITS_PER_UNIT
);
1116 else if (maximum_field_alignment
!= 0)
1117 type_align
= MIN (type_align
, maximum_field_alignment
);
1118 else if (DECL_PACKED (field
))
1119 type_align
= MIN (type_align
, BITS_PER_UNIT
);
1121 /* The alignment of the record is increased to the maximum
1122 of the current alignment, the alignment indicated on the
1123 field (i.e., the alignment specified by an __aligned__
1124 attribute), and the alignment indicated by the type of
1126 rli
->record_align
= MAX (rli
->record_align
, desired_align
);
1127 rli
->record_align
= MAX (rli
->record_align
, type_align
);
1130 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
1131 user_align
|= TYPE_USER_ALIGN (type
);
1136 rli
->record_align
= MAX (rli
->record_align
, desired_align
);
1137 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
1140 TYPE_USER_ALIGN (rli
->t
) |= user_align
;
1142 return desired_align
;
1145 /* Issue a warning if the record alignment, RECORD_ALIGN, is less than
1146 the field alignment of FIELD or FIELD isn't aligned. */
1149 handle_warn_if_not_align (tree field
, unsigned int record_align
)
1151 tree type
= TREE_TYPE (field
);
1153 if (type
== error_mark_node
)
1156 unsigned int warn_if_not_align
= 0;
1160 if (warn_if_not_aligned
)
1162 warn_if_not_align
= DECL_WARN_IF_NOT_ALIGN (field
);
1163 if (!warn_if_not_align
)
1164 warn_if_not_align
= TYPE_WARN_IF_NOT_ALIGN (type
);
1165 if (warn_if_not_align
)
1166 opt_w
= OPT_Wif_not_aligned
;
1169 if (!warn_if_not_align
1170 && warn_packed_not_aligned
1171 && lookup_attribute ("aligned", TYPE_ATTRIBUTES (type
)))
1173 warn_if_not_align
= TYPE_ALIGN (type
);
1174 opt_w
= OPT_Wpacked_not_aligned
;
1177 if (!warn_if_not_align
)
1180 tree context
= DECL_CONTEXT (field
);
1182 warn_if_not_align
/= BITS_PER_UNIT
;
1183 record_align
/= BITS_PER_UNIT
;
1184 if ((record_align
% warn_if_not_align
) != 0)
1185 warning (opt_w
, "alignment %u of %qT is less than %u",
1186 record_align
, context
, warn_if_not_align
);
1188 tree off
= byte_position (field
);
1189 if (!multiple_of_p (TREE_TYPE (off
), off
, size_int (warn_if_not_align
)))
1191 if (TREE_CODE (off
) == INTEGER_CST
)
1192 warning (opt_w
, "%q+D offset %E in %qT isn%'t aligned to %u",
1193 field
, off
, context
, warn_if_not_align
);
1195 warning (opt_w
, "%q+D offset %E in %qT may not be aligned to %u",
1196 field
, off
, context
, warn_if_not_align
);
1200 /* Called from place_field to handle unions. */
1203 place_union_field (record_layout_info rli
, tree field
)
1205 update_alignment_for_field (rli
, field
, /*known_align=*/0);
1207 DECL_FIELD_OFFSET (field
) = size_zero_node
;
1208 DECL_FIELD_BIT_OFFSET (field
) = bitsize_zero_node
;
1209 SET_DECL_OFFSET_ALIGN (field
, BIGGEST_ALIGNMENT
);
1210 handle_warn_if_not_align (field
, rli
->record_align
);
1212 /* If this is an ERROR_MARK return *after* having set the
1213 field at the start of the union. This helps when parsing
1215 if (TREE_CODE (TREE_TYPE (field
)) == ERROR_MARK
)
1218 if (AGGREGATE_TYPE_P (TREE_TYPE (field
))
1219 && TYPE_TYPELESS_STORAGE (TREE_TYPE (field
)))
1220 TYPE_TYPELESS_STORAGE (rli
->t
) = 1;
1222 /* We assume the union's size will be a multiple of a byte so we don't
1223 bother with BITPOS. */
1224 if (TREE_CODE (rli
->t
) == UNION_TYPE
)
1225 rli
->offset
= size_binop (MAX_EXPR
, rli
->offset
, DECL_SIZE_UNIT (field
));
1226 else if (TREE_CODE (rli
->t
) == QUAL_UNION_TYPE
)
1227 rli
->offset
= fold_build3 (COND_EXPR
, sizetype
, DECL_QUALIFIER (field
),
1228 DECL_SIZE_UNIT (field
), rli
->offset
);
1231 /* A bitfield of SIZE with a required access alignment of ALIGN is allocated
1232 at BYTE_OFFSET / BIT_OFFSET. Return nonzero if the field would span more
1233 units of alignment than the underlying TYPE. */
1235 excess_unit_span (HOST_WIDE_INT byte_offset
, HOST_WIDE_INT bit_offset
,
1236 HOST_WIDE_INT size
, HOST_WIDE_INT align
, tree type
)
1238 /* Note that the calculation of OFFSET might overflow; we calculate it so
1239 that we still get the right result as long as ALIGN is a power of two. */
1240 unsigned HOST_WIDE_INT offset
= byte_offset
* BITS_PER_UNIT
+ bit_offset
;
1242 offset
= offset
% align
;
1243 return ((offset
+ size
+ align
- 1) / align
1244 > tree_to_uhwi (TYPE_SIZE (type
)) / align
);
1247 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
1248 is a FIELD_DECL to be added after those fields already present in
1249 T. (FIELD is not actually added to the TYPE_FIELDS list here;
1250 callers that desire that behavior must manually perform that step.) */
1253 place_field (record_layout_info rli
, tree field
)
1255 /* The alignment required for FIELD. */
1256 unsigned int desired_align
;
1257 /* The alignment FIELD would have if we just dropped it into the
1258 record as it presently stands. */
1259 unsigned int known_align
;
1260 unsigned int actual_align
;
1261 /* The type of this field. */
1262 tree type
= TREE_TYPE (field
);
1264 gcc_assert (TREE_CODE (field
) != ERROR_MARK
);
1266 /* If FIELD is static, then treat it like a separate variable, not
1267 really like a structure field. If it is a FUNCTION_DECL, it's a
1268 method. In both cases, all we do is lay out the decl, and we do
1269 it *after* the record is laid out. */
1272 vec_safe_push (rli
->pending_statics
, field
);
1276 /* Enumerators and enum types which are local to this class need not
1277 be laid out. Likewise for initialized constant fields. */
1278 else if (TREE_CODE (field
) != FIELD_DECL
)
1281 /* Unions are laid out very differently than records, so split
1282 that code off to another function. */
1283 else if (TREE_CODE (rli
->t
) != RECORD_TYPE
)
1285 place_union_field (rli
, field
);
1289 else if (TREE_CODE (type
) == ERROR_MARK
)
1291 /* Place this field at the current allocation position, so we
1292 maintain monotonicity. */
1293 DECL_FIELD_OFFSET (field
) = rli
->offset
;
1294 DECL_FIELD_BIT_OFFSET (field
) = rli
->bitpos
;
1295 SET_DECL_OFFSET_ALIGN (field
, rli
->offset_align
);
1296 handle_warn_if_not_align (field
, rli
->record_align
);
1300 if (AGGREGATE_TYPE_P (type
)
1301 && TYPE_TYPELESS_STORAGE (type
))
1302 TYPE_TYPELESS_STORAGE (rli
->t
) = 1;
1304 /* Work out the known alignment so far. Note that A & (-A) is the
1305 value of the least-significant bit in A that is one. */
1306 if (! integer_zerop (rli
->bitpos
))
1307 known_align
= least_bit_hwi (tree_to_uhwi (rli
->bitpos
));
1308 else if (integer_zerop (rli
->offset
))
1310 else if (tree_fits_uhwi_p (rli
->offset
))
1311 known_align
= (BITS_PER_UNIT
1312 * least_bit_hwi (tree_to_uhwi (rli
->offset
)));
1314 known_align
= rli
->offset_align
;
1316 desired_align
= update_alignment_for_field (rli
, field
, known_align
);
1317 if (known_align
== 0)
1318 known_align
= MAX (BIGGEST_ALIGNMENT
, rli
->record_align
);
1320 if (warn_packed
&& DECL_PACKED (field
))
1322 if (known_align
>= TYPE_ALIGN (type
))
1324 if (TYPE_ALIGN (type
) > desired_align
)
1326 if (STRICT_ALIGNMENT
)
1327 warning (OPT_Wattributes
, "packed attribute causes "
1328 "inefficient alignment for %q+D", field
);
1329 /* Don't warn if DECL_PACKED was set by the type. */
1330 else if (!TYPE_PACKED (rli
->t
))
1331 warning (OPT_Wattributes
, "packed attribute is "
1332 "unnecessary for %q+D", field
);
1336 rli
->packed_maybe_necessary
= 1;
1339 /* Does this field automatically have alignment it needs by virtue
1340 of the fields that precede it and the record's own alignment? */
1341 if (known_align
< desired_align
1342 && (! targetm
.ms_bitfield_layout_p (rli
->t
)
1343 || rli
->prev_field
== NULL
))
1345 /* No, we need to skip space before this field.
1346 Bump the cumulative size to multiple of field alignment. */
1348 if (!targetm
.ms_bitfield_layout_p (rli
->t
)
1349 && DECL_SOURCE_LOCATION (field
) != BUILTINS_LOCATION
1350 && !TYPE_ARTIFICIAL (rli
->t
))
1351 warning (OPT_Wpadded
, "padding struct to align %q+D", field
);
1353 /* If the alignment is still within offset_align, just align
1354 the bit position. */
1355 if (desired_align
< rli
->offset_align
)
1356 rli
->bitpos
= round_up (rli
->bitpos
, desired_align
);
1359 /* First adjust OFFSET by the partial bits, then align. */
1361 = size_binop (PLUS_EXPR
, rli
->offset
,
1362 fold_convert (sizetype
,
1363 size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
1364 bitsize_unit_node
)));
1365 rli
->bitpos
= bitsize_zero_node
;
1367 rli
->offset
= round_up (rli
->offset
, desired_align
/ BITS_PER_UNIT
);
1370 if (! TREE_CONSTANT (rli
->offset
))
1371 rli
->offset_align
= desired_align
;
1374 /* Handle compatibility with PCC. Note that if the record has any
1375 variable-sized fields, we need not worry about compatibility. */
1376 if (PCC_BITFIELD_TYPE_MATTERS
1377 && ! targetm
.ms_bitfield_layout_p (rli
->t
)
1378 && TREE_CODE (field
) == FIELD_DECL
1379 && type
!= error_mark_node
1380 && DECL_BIT_FIELD (field
)
1381 && (! DECL_PACKED (field
)
1382 /* Enter for these packed fields only to issue a warning. */
1383 || TYPE_ALIGN (type
) <= BITS_PER_UNIT
)
1384 && maximum_field_alignment
== 0
1385 && ! integer_zerop (DECL_SIZE (field
))
1386 && tree_fits_uhwi_p (DECL_SIZE (field
))
1387 && tree_fits_uhwi_p (rli
->offset
)
1388 && tree_fits_uhwi_p (TYPE_SIZE (type
)))
1390 unsigned int type_align
= TYPE_ALIGN (type
);
1391 tree dsize
= DECL_SIZE (field
);
1392 HOST_WIDE_INT field_size
= tree_to_uhwi (dsize
);
1393 HOST_WIDE_INT offset
= tree_to_uhwi (rli
->offset
);
1394 HOST_WIDE_INT bit_offset
= tree_to_shwi (rli
->bitpos
);
1396 #ifdef ADJUST_FIELD_ALIGN
1397 if (! TYPE_USER_ALIGN (type
))
1398 type_align
= ADJUST_FIELD_ALIGN (field
, type
, type_align
);
1401 /* A bit field may not span more units of alignment of its type
1402 than its type itself. Advance to next boundary if necessary. */
1403 if (excess_unit_span (offset
, bit_offset
, field_size
, type_align
, type
))
1405 if (DECL_PACKED (field
))
1407 if (warn_packed_bitfield_compat
== 1)
1410 "offset of packed bit-field %qD has changed in GCC 4.4",
1414 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1417 if (! DECL_PACKED (field
))
1418 TYPE_USER_ALIGN (rli
->t
) |= TYPE_USER_ALIGN (type
);
1420 SET_TYPE_WARN_IF_NOT_ALIGN (rli
->t
,
1421 TYPE_WARN_IF_NOT_ALIGN (type
));
1424 #ifdef BITFIELD_NBYTES_LIMITED
1425 if (BITFIELD_NBYTES_LIMITED
1426 && ! targetm
.ms_bitfield_layout_p (rli
->t
)
1427 && TREE_CODE (field
) == FIELD_DECL
1428 && type
!= error_mark_node
1429 && DECL_BIT_FIELD_TYPE (field
)
1430 && ! DECL_PACKED (field
)
1431 && ! integer_zerop (DECL_SIZE (field
))
1432 && tree_fits_uhwi_p (DECL_SIZE (field
))
1433 && tree_fits_uhwi_p (rli
->offset
)
1434 && tree_fits_uhwi_p (TYPE_SIZE (type
)))
1436 unsigned int type_align
= TYPE_ALIGN (type
);
1437 tree dsize
= DECL_SIZE (field
);
1438 HOST_WIDE_INT field_size
= tree_to_uhwi (dsize
);
1439 HOST_WIDE_INT offset
= tree_to_uhwi (rli
->offset
);
1440 HOST_WIDE_INT bit_offset
= tree_to_shwi (rli
->bitpos
);
1442 #ifdef ADJUST_FIELD_ALIGN
1443 if (! TYPE_USER_ALIGN (type
))
1444 type_align
= ADJUST_FIELD_ALIGN (field
, type
, type_align
);
1447 if (maximum_field_alignment
!= 0)
1448 type_align
= MIN (type_align
, maximum_field_alignment
);
1449 /* ??? This test is opposite the test in the containing if
1450 statement, so this code is unreachable currently. */
1451 else if (DECL_PACKED (field
))
1452 type_align
= MIN (type_align
, BITS_PER_UNIT
);
1454 /* A bit field may not span the unit of alignment of its type.
1455 Advance to next boundary if necessary. */
1456 if (excess_unit_span (offset
, bit_offset
, field_size
, type_align
, type
))
1457 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1459 TYPE_USER_ALIGN (rli
->t
) |= TYPE_USER_ALIGN (type
);
1460 SET_TYPE_WARN_IF_NOT_ALIGN (rli
->t
,
1461 TYPE_WARN_IF_NOT_ALIGN (type
));
1465 /* See the docs for TARGET_MS_BITFIELD_LAYOUT_P for details.
1467 When a bit field is inserted into a packed record, the whole
1468 size of the underlying type is used by one or more same-size
1469 adjacent bitfields. (That is, if its long:3, 32 bits is
1470 used in the record, and any additional adjacent long bitfields are
1471 packed into the same chunk of 32 bits. However, if the size
1472 changes, a new field of that size is allocated.) In an unpacked
1473 record, this is the same as using alignment, but not equivalent
1476 Note: for compatibility, we use the type size, not the type alignment
1477 to determine alignment, since that matches the documentation */
1479 if (targetm
.ms_bitfield_layout_p (rli
->t
))
1481 tree prev_saved
= rli
->prev_field
;
1482 tree prev_type
= prev_saved
? DECL_BIT_FIELD_TYPE (prev_saved
) : NULL
;
1484 /* This is a bitfield if it exists. */
1485 if (rli
->prev_field
)
1487 bool realign_p
= known_align
< desired_align
;
1489 /* If both are bitfields, nonzero, and the same size, this is
1490 the middle of a run. Zero declared size fields are special
1491 and handled as "end of run". (Note: it's nonzero declared
1492 size, but equal type sizes!) (Since we know that both
1493 the current and previous fields are bitfields by the
1494 time we check it, DECL_SIZE must be present for both.) */
1495 if (DECL_BIT_FIELD_TYPE (field
)
1496 && !integer_zerop (DECL_SIZE (field
))
1497 && !integer_zerop (DECL_SIZE (rli
->prev_field
))
1498 && tree_fits_shwi_p (DECL_SIZE (rli
->prev_field
))
1499 && tree_fits_uhwi_p (TYPE_SIZE (type
))
1500 && simple_cst_equal (TYPE_SIZE (type
), TYPE_SIZE (prev_type
)))
1502 /* We're in the middle of a run of equal type size fields; make
1503 sure we realign if we run out of bits. (Not decl size,
1505 HOST_WIDE_INT bitsize
= tree_to_uhwi (DECL_SIZE (field
));
1507 if (rli
->remaining_in_alignment
< bitsize
)
1509 HOST_WIDE_INT typesize
= tree_to_uhwi (TYPE_SIZE (type
));
1511 /* out of bits; bump up to next 'word'. */
1513 = size_binop (PLUS_EXPR
, rli
->bitpos
,
1514 bitsize_int (rli
->remaining_in_alignment
));
1515 rli
->prev_field
= field
;
1516 if (typesize
< bitsize
)
1517 rli
->remaining_in_alignment
= 0;
1519 rli
->remaining_in_alignment
= typesize
- bitsize
;
1523 rli
->remaining_in_alignment
-= bitsize
;
1529 /* End of a run: if leaving a run of bitfields of the same type
1530 size, we have to "use up" the rest of the bits of the type
1533 Compute the new position as the sum of the size for the prior
1534 type and where we first started working on that type.
1535 Note: since the beginning of the field was aligned then
1536 of course the end will be too. No round needed. */
1538 if (!integer_zerop (DECL_SIZE (rli
->prev_field
)))
1541 = size_binop (PLUS_EXPR
, rli
->bitpos
,
1542 bitsize_int (rli
->remaining_in_alignment
));
1545 /* We "use up" size zero fields; the code below should behave
1546 as if the prior field was not a bitfield. */
1549 /* Cause a new bitfield to be captured, either this time (if
1550 currently a bitfield) or next time we see one. */
1551 if (!DECL_BIT_FIELD_TYPE (field
)
1552 || integer_zerop (DECL_SIZE (field
)))
1553 rli
->prev_field
= NULL
;
1556 /* Does this field automatically have alignment it needs by virtue
1557 of the fields that precede it and the record's own alignment? */
1560 /* If the alignment is still within offset_align, just align
1561 the bit position. */
1562 if (desired_align
< rli
->offset_align
)
1563 rli
->bitpos
= round_up (rli
->bitpos
, desired_align
);
1566 /* First adjust OFFSET by the partial bits, then align. */
1567 tree d
= size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
1569 rli
->offset
= size_binop (PLUS_EXPR
, rli
->offset
,
1570 fold_convert (sizetype
, d
));
1571 rli
->bitpos
= bitsize_zero_node
;
1573 rli
->offset
= round_up (rli
->offset
,
1574 desired_align
/ BITS_PER_UNIT
);
1577 if (! TREE_CONSTANT (rli
->offset
))
1578 rli
->offset_align
= desired_align
;
1581 normalize_rli (rli
);
1584 /* If we're starting a new run of same type size bitfields
1585 (or a run of non-bitfields), set up the "first of the run"
1588 That is, if the current field is not a bitfield, or if there
1589 was a prior bitfield the type sizes differ, or if there wasn't
1590 a prior bitfield the size of the current field is nonzero.
1592 Note: we must be sure to test ONLY the type size if there was
1593 a prior bitfield and ONLY for the current field being zero if
1596 if (!DECL_BIT_FIELD_TYPE (field
)
1597 || (prev_saved
!= NULL
1598 ? !simple_cst_equal (TYPE_SIZE (type
), TYPE_SIZE (prev_type
))
1599 : !integer_zerop (DECL_SIZE (field
))))
1601 /* Never smaller than a byte for compatibility. */
1602 unsigned int type_align
= BITS_PER_UNIT
;
1604 /* (When not a bitfield), we could be seeing a flex array (with
1605 no DECL_SIZE). Since we won't be using remaining_in_alignment
1606 until we see a bitfield (and come by here again) we just skip
1608 if (DECL_SIZE (field
) != NULL
1609 && tree_fits_uhwi_p (TYPE_SIZE (TREE_TYPE (field
)))
1610 && tree_fits_uhwi_p (DECL_SIZE (field
)))
1612 unsigned HOST_WIDE_INT bitsize
1613 = tree_to_uhwi (DECL_SIZE (field
));
1614 unsigned HOST_WIDE_INT typesize
1615 = tree_to_uhwi (TYPE_SIZE (TREE_TYPE (field
)));
1617 if (typesize
< bitsize
)
1618 rli
->remaining_in_alignment
= 0;
1620 rli
->remaining_in_alignment
= typesize
- bitsize
;
1623 /* Now align (conventionally) for the new type. */
1624 if (! DECL_PACKED (field
))
1625 type_align
= TYPE_ALIGN (TREE_TYPE (field
));
1627 if (maximum_field_alignment
!= 0)
1628 type_align
= MIN (type_align
, maximum_field_alignment
);
1630 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1632 /* If we really aligned, don't allow subsequent bitfields
1634 rli
->prev_field
= NULL
;
1638 /* Offset so far becomes the position of this field after normalizing. */
1639 normalize_rli (rli
);
1640 DECL_FIELD_OFFSET (field
) = rli
->offset
;
1641 DECL_FIELD_BIT_OFFSET (field
) = rli
->bitpos
;
1642 SET_DECL_OFFSET_ALIGN (field
, rli
->offset_align
);
1643 handle_warn_if_not_align (field
, rli
->record_align
);
1645 /* Evaluate nonconstant offsets only once, either now or as soon as safe. */
1646 if (TREE_CODE (DECL_FIELD_OFFSET (field
)) != INTEGER_CST
)
1647 DECL_FIELD_OFFSET (field
) = variable_size (DECL_FIELD_OFFSET (field
));
1649 /* If this field ended up more aligned than we thought it would be (we
1650 approximate this by seeing if its position changed), lay out the field
1651 again; perhaps we can use an integral mode for it now. */
1652 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field
)))
1653 actual_align
= least_bit_hwi (tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field
)));
1654 else if (integer_zerop (DECL_FIELD_OFFSET (field
)))
1655 actual_align
= MAX (BIGGEST_ALIGNMENT
, rli
->record_align
);
1656 else if (tree_fits_uhwi_p (DECL_FIELD_OFFSET (field
)))
1657 actual_align
= (BITS_PER_UNIT
1658 * least_bit_hwi (tree_to_uhwi (DECL_FIELD_OFFSET (field
))));
1660 actual_align
= DECL_OFFSET_ALIGN (field
);
1661 /* ACTUAL_ALIGN is still the actual alignment *within the record* .
1662 store / extract bit field operations will check the alignment of the
1663 record against the mode of bit fields. */
1665 if (known_align
!= actual_align
)
1666 layout_decl (field
, actual_align
);
1668 if (rli
->prev_field
== NULL
&& DECL_BIT_FIELD_TYPE (field
))
1669 rli
->prev_field
= field
;
1671 /* Now add size of this field to the size of the record. If the size is
1672 not constant, treat the field as being a multiple of bytes and just
1673 adjust the offset, resetting the bit position. Otherwise, apportion the
1674 size amongst the bit position and offset. First handle the case of an
1675 unspecified size, which can happen when we have an invalid nested struct
1676 definition, such as struct j { struct j { int i; } }. The error message
1677 is printed in finish_struct. */
1678 if (DECL_SIZE (field
) == 0)
1680 else if (TREE_CODE (DECL_SIZE (field
)) != INTEGER_CST
1681 || TREE_OVERFLOW (DECL_SIZE (field
)))
1684 = size_binop (PLUS_EXPR
, rli
->offset
,
1685 fold_convert (sizetype
,
1686 size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
1687 bitsize_unit_node
)));
1689 = size_binop (PLUS_EXPR
, rli
->offset
, DECL_SIZE_UNIT (field
));
1690 rli
->bitpos
= bitsize_zero_node
;
1691 rli
->offset_align
= MIN (rli
->offset_align
, desired_align
);
1693 if (!multiple_of_p (bitsizetype
, DECL_SIZE (field
),
1694 bitsize_int (rli
->offset_align
)))
1696 tree type
= strip_array_types (TREE_TYPE (field
));
1697 /* The above adjusts offset_align just based on the start of the
1698 field. The field might not have a size that is a multiple of
1699 that offset_align though. If the field is an array of fixed
1700 sized elements, assume there can be any multiple of those
1701 sizes. If it is a variable length aggregate or array of
1702 variable length aggregates, assume worst that the end is
1703 just BITS_PER_UNIT aligned. */
1704 if (TREE_CODE (TYPE_SIZE (type
)) == INTEGER_CST
)
1706 if (TREE_INT_CST_LOW (TYPE_SIZE (type
)))
1708 unsigned HOST_WIDE_INT sz
1709 = least_bit_hwi (TREE_INT_CST_LOW (TYPE_SIZE (type
)));
1710 rli
->offset_align
= MIN (rli
->offset_align
, sz
);
1714 rli
->offset_align
= MIN (rli
->offset_align
, BITS_PER_UNIT
);
1717 else if (targetm
.ms_bitfield_layout_p (rli
->t
))
1719 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
, DECL_SIZE (field
));
1721 /* If FIELD is the last field and doesn't end at the full length
1722 of the type then pad the struct out to the full length of the
1724 if (DECL_BIT_FIELD_TYPE (field
)
1725 && !integer_zerop (DECL_SIZE (field
)))
1727 /* We have to scan, because non-field DECLS are also here. */
1729 while ((probe
= DECL_CHAIN (probe
)))
1730 if (TREE_CODE (probe
) == FIELD_DECL
)
1733 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
,
1734 bitsize_int (rli
->remaining_in_alignment
));
1737 normalize_rli (rli
);
1741 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
, DECL_SIZE (field
));
1742 normalize_rli (rli
);
1746 /* Assuming that all the fields have been laid out, this function uses
1747 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
1748 indicated by RLI. */
1751 finalize_record_size (record_layout_info rli
)
1753 tree unpadded_size
, unpadded_size_unit
;
1755 /* Now we want just byte and bit offsets, so set the offset alignment
1756 to be a byte and then normalize. */
1757 rli
->offset_align
= BITS_PER_UNIT
;
1758 normalize_rli (rli
);
1760 /* Determine the desired alignment. */
1761 #ifdef ROUND_TYPE_ALIGN
1762 SET_TYPE_ALIGN (rli
->t
, ROUND_TYPE_ALIGN (rli
->t
, TYPE_ALIGN (rli
->t
),
1763 rli
->record_align
));
1765 SET_TYPE_ALIGN (rli
->t
, MAX (TYPE_ALIGN (rli
->t
), rli
->record_align
));
1768 /* Compute the size so far. Be sure to allow for extra bits in the
1769 size in bytes. We have guaranteed above that it will be no more
1770 than a single byte. */
1771 unpadded_size
= rli_size_so_far (rli
);
1772 unpadded_size_unit
= rli_size_unit_so_far (rli
);
1773 if (! integer_zerop (rli
->bitpos
))
1775 = size_binop (PLUS_EXPR
, unpadded_size_unit
, size_one_node
);
1777 /* Round the size up to be a multiple of the required alignment. */
1778 TYPE_SIZE (rli
->t
) = round_up (unpadded_size
, TYPE_ALIGN (rli
->t
));
1779 TYPE_SIZE_UNIT (rli
->t
)
1780 = round_up (unpadded_size_unit
, TYPE_ALIGN_UNIT (rli
->t
));
1782 if (TREE_CONSTANT (unpadded_size
)
1783 && simple_cst_equal (unpadded_size
, TYPE_SIZE (rli
->t
)) == 0
1784 && input_location
!= BUILTINS_LOCATION
1785 && !TYPE_ARTIFICIAL (rli
->t
))
1788 = size_binop (MINUS_EXPR
, TYPE_SIZE_UNIT (rli
->t
), unpadded_size_unit
);
1789 warning (OPT_Wpadded
,
1790 "padding struct size to alignment boundary with %E bytes", pad_size
);
1793 if (warn_packed
&& TREE_CODE (rli
->t
) == RECORD_TYPE
1794 && TYPE_PACKED (rli
->t
) && ! rli
->packed_maybe_necessary
1795 && TREE_CONSTANT (unpadded_size
))
1799 #ifdef ROUND_TYPE_ALIGN
1801 = ROUND_TYPE_ALIGN (rli
->t
, TYPE_ALIGN (rli
->t
), rli
->unpacked_align
);
1803 rli
->unpacked_align
= MAX (TYPE_ALIGN (rli
->t
), rli
->unpacked_align
);
1806 unpacked_size
= round_up (TYPE_SIZE (rli
->t
), rli
->unpacked_align
);
1807 if (simple_cst_equal (unpacked_size
, TYPE_SIZE (rli
->t
)))
1809 if (TYPE_NAME (rli
->t
))
1813 if (TREE_CODE (TYPE_NAME (rli
->t
)) == IDENTIFIER_NODE
)
1814 name
= TYPE_NAME (rli
->t
);
1816 name
= DECL_NAME (TYPE_NAME (rli
->t
));
1818 if (STRICT_ALIGNMENT
)
1819 warning (OPT_Wpacked
, "packed attribute causes inefficient "
1820 "alignment for %qE", name
);
1822 warning (OPT_Wpacked
,
1823 "packed attribute is unnecessary for %qE", name
);
1827 if (STRICT_ALIGNMENT
)
1828 warning (OPT_Wpacked
,
1829 "packed attribute causes inefficient alignment");
1831 warning (OPT_Wpacked
, "packed attribute is unnecessary");
1837 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
1840 compute_record_mode (tree type
)
1843 machine_mode mode
= VOIDmode
;
1845 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
1846 However, if possible, we use a mode that fits in a register
1847 instead, in order to allow for better optimization down the
1849 SET_TYPE_MODE (type
, BLKmode
);
1851 poly_uint64 type_size
;
1852 if (!poly_int_tree_p (TYPE_SIZE (type
), &type_size
))
1855 /* A record which has any BLKmode members must itself be
1856 BLKmode; it can't go in a register. Unless the member is
1857 BLKmode only because it isn't aligned. */
1858 for (field
= TYPE_FIELDS (type
); field
; field
= DECL_CHAIN (field
))
1860 if (TREE_CODE (field
) != FIELD_DECL
)
1863 poly_uint64 field_size
;
1864 if (TREE_CODE (TREE_TYPE (field
)) == ERROR_MARK
1865 || (TYPE_MODE (TREE_TYPE (field
)) == BLKmode
1866 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field
))
1867 && !(TYPE_SIZE (TREE_TYPE (field
)) != 0
1868 && integer_zerop (TYPE_SIZE (TREE_TYPE (field
)))))
1869 || !tree_fits_poly_uint64_p (bit_position (field
))
1870 || DECL_SIZE (field
) == 0
1871 || !poly_int_tree_p (DECL_SIZE (field
), &field_size
))
1874 /* If this field is the whole struct, remember its mode so
1875 that, say, we can put a double in a class into a DF
1876 register instead of forcing it to live in the stack. */
1877 if (known_eq (field_size
, type_size
)
1878 /* Partial int types (e.g. __int20) may have TYPE_SIZE equal to
1879 wider types (e.g. int32), despite precision being less. Ensure
1880 that the TYPE_MODE of the struct does not get set to the partial
1881 int mode if there is a wider type also in the struct. */
1882 && known_gt (GET_MODE_PRECISION (DECL_MODE (field
)),
1883 GET_MODE_PRECISION (mode
)))
1884 mode
= DECL_MODE (field
);
1886 /* With some targets, it is sub-optimal to access an aligned
1887 BLKmode structure as a scalar. */
1888 if (targetm
.member_type_forces_blk (field
, mode
))
1892 /* If we only have one real field; use its mode if that mode's size
1893 matches the type's size. This generally only applies to RECORD_TYPE.
1894 For UNION_TYPE, if the widest field is MODE_INT then use that mode.
1895 If the widest field is MODE_PARTIAL_INT, and the union will be passed
1896 by reference, then use that mode. */
1897 if ((TREE_CODE (type
) == RECORD_TYPE
1898 || (TREE_CODE (type
) == UNION_TYPE
1899 && (GET_MODE_CLASS (mode
) == MODE_INT
1900 || (GET_MODE_CLASS (mode
) == MODE_PARTIAL_INT
1901 && (targetm
.calls
.pass_by_reference
1902 (pack_cumulative_args (0),
1903 function_arg_info (type
, mode
, /*named=*/false)))))))
1905 && known_eq (GET_MODE_BITSIZE (mode
), type_size
))
1908 mode
= mode_for_size_tree (TYPE_SIZE (type
), MODE_INT
, 1).else_blk ();
1910 /* If structure's known alignment is less than what the scalar
1911 mode would need, and it matters, then stick with BLKmode. */
1914 && ! (TYPE_ALIGN (type
) >= BIGGEST_ALIGNMENT
1915 || TYPE_ALIGN (type
) >= GET_MODE_ALIGNMENT (mode
)))
1917 /* If this is the only reason this type is BLKmode, then
1918 don't force containing types to be BLKmode. */
1919 TYPE_NO_FORCE_BLK (type
) = 1;
1923 SET_TYPE_MODE (type
, mode
);
1926 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1930 finalize_type_size (tree type
)
1932 /* Normally, use the alignment corresponding to the mode chosen.
1933 However, where strict alignment is not required, avoid
1934 over-aligning structures, since most compilers do not do this
1936 bool tua_cleared_p
= false;
1937 if (TYPE_MODE (type
) != BLKmode
1938 && TYPE_MODE (type
) != VOIDmode
1939 && (STRICT_ALIGNMENT
|| !AGGREGATE_TYPE_P (type
)))
1941 unsigned mode_align
= GET_MODE_ALIGNMENT (TYPE_MODE (type
));
1943 /* Don't override a larger alignment requirement coming from a user
1944 alignment of one of the fields. */
1945 if (mode_align
>= TYPE_ALIGN (type
))
1947 SET_TYPE_ALIGN (type
, mode_align
);
1948 /* Remember that we're about to reset this flag. */
1949 tua_cleared_p
= TYPE_USER_ALIGN (type
);
1950 TYPE_USER_ALIGN (type
) = false;
1954 /* Do machine-dependent extra alignment. */
1955 #ifdef ROUND_TYPE_ALIGN
1956 SET_TYPE_ALIGN (type
,
1957 ROUND_TYPE_ALIGN (type
, TYPE_ALIGN (type
), BITS_PER_UNIT
));
1960 /* If we failed to find a simple way to calculate the unit size
1961 of the type, find it by division. */
1962 if (TYPE_SIZE_UNIT (type
) == 0 && TYPE_SIZE (type
) != 0)
1963 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1964 result will fit in sizetype. We will get more efficient code using
1965 sizetype, so we force a conversion. */
1966 TYPE_SIZE_UNIT (type
)
1967 = fold_convert (sizetype
,
1968 size_binop (FLOOR_DIV_EXPR
, TYPE_SIZE (type
),
1969 bitsize_unit_node
));
1971 if (TYPE_SIZE (type
) != 0)
1973 TYPE_SIZE (type
) = round_up (TYPE_SIZE (type
), TYPE_ALIGN (type
));
1974 TYPE_SIZE_UNIT (type
)
1975 = round_up (TYPE_SIZE_UNIT (type
), TYPE_ALIGN_UNIT (type
));
1978 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1979 if (TYPE_SIZE (type
) != 0 && TREE_CODE (TYPE_SIZE (type
)) != INTEGER_CST
)
1980 TYPE_SIZE (type
) = variable_size (TYPE_SIZE (type
));
1981 if (TYPE_SIZE_UNIT (type
) != 0
1982 && TREE_CODE (TYPE_SIZE_UNIT (type
)) != INTEGER_CST
)
1983 TYPE_SIZE_UNIT (type
) = variable_size (TYPE_SIZE_UNIT (type
));
1985 /* Handle empty records as per the x86-64 psABI. */
1986 TYPE_EMPTY_P (type
) = targetm
.calls
.empty_record_p (type
);
1988 /* Also layout any other variants of the type. */
1989 if (TYPE_NEXT_VARIANT (type
)
1990 || type
!= TYPE_MAIN_VARIANT (type
))
1993 /* Record layout info of this variant. */
1994 tree size
= TYPE_SIZE (type
);
1995 tree size_unit
= TYPE_SIZE_UNIT (type
);
1996 unsigned int align
= TYPE_ALIGN (type
);
1997 unsigned int precision
= TYPE_PRECISION (type
);
1998 unsigned int user_align
= TYPE_USER_ALIGN (type
);
1999 machine_mode mode
= TYPE_MODE (type
);
2000 bool empty_p
= TYPE_EMPTY_P (type
);
2001 bool typeless
= AGGREGATE_TYPE_P (type
) && TYPE_TYPELESS_STORAGE (type
);
2003 /* Copy it into all variants. */
2004 for (variant
= TYPE_MAIN_VARIANT (type
);
2005 variant
!= NULL_TREE
;
2006 variant
= TYPE_NEXT_VARIANT (variant
))
2008 TYPE_SIZE (variant
) = size
;
2009 TYPE_SIZE_UNIT (variant
) = size_unit
;
2010 unsigned valign
= align
;
2011 if (TYPE_USER_ALIGN (variant
))
2013 valign
= MAX (valign
, TYPE_ALIGN (variant
));
2014 /* If we reset TYPE_USER_ALIGN on the main variant, we might
2015 need to reset it on the variants too. TYPE_MODE will be set
2016 to MODE in this variant, so we can use that. */
2017 if (tua_cleared_p
&& GET_MODE_ALIGNMENT (mode
) >= valign
)
2018 TYPE_USER_ALIGN (variant
) = false;
2021 TYPE_USER_ALIGN (variant
) = user_align
;
2022 SET_TYPE_ALIGN (variant
, valign
);
2023 TYPE_PRECISION (variant
) = precision
;
2024 SET_TYPE_MODE (variant
, mode
);
2025 TYPE_EMPTY_P (variant
) = empty_p
;
2026 if (AGGREGATE_TYPE_P (variant
))
2027 TYPE_TYPELESS_STORAGE (variant
) = typeless
;
2032 /* Return a new underlying object for a bitfield started with FIELD. */
2035 start_bitfield_representative (tree field
)
2037 tree repr
= make_node (FIELD_DECL
);
2038 DECL_FIELD_OFFSET (repr
) = DECL_FIELD_OFFSET (field
);
2039 /* Force the representative to begin at a BITS_PER_UNIT aligned
2040 boundary - C++ may use tail-padding of a base object to
2041 continue packing bits so the bitfield region does not start
2042 at bit zero (see g++.dg/abi/bitfield5.C for example).
2043 Unallocated bits may happen for other reasons as well,
2044 for example Ada which allows explicit bit-granular structure layout. */
2045 DECL_FIELD_BIT_OFFSET (repr
)
2046 = size_binop (BIT_AND_EXPR
,
2047 DECL_FIELD_BIT_OFFSET (field
),
2048 bitsize_int (~(BITS_PER_UNIT
- 1)));
2049 SET_DECL_OFFSET_ALIGN (repr
, DECL_OFFSET_ALIGN (field
));
2050 DECL_SIZE (repr
) = DECL_SIZE (field
);
2051 DECL_SIZE_UNIT (repr
) = DECL_SIZE_UNIT (field
);
2052 DECL_PACKED (repr
) = DECL_PACKED (field
);
2053 DECL_CONTEXT (repr
) = DECL_CONTEXT (field
);
2054 /* There are no indirect accesses to this field. If we introduce
2055 some then they have to use the record alias set. This makes
2056 sure to properly conflict with [indirect] accesses to addressable
2057 fields of the bitfield group. */
2058 DECL_NONADDRESSABLE_P (repr
) = 1;
2062 /* Finish up a bitfield group that was started by creating the underlying
2063 object REPR with the last field in the bitfield group FIELD. */
2066 finish_bitfield_representative (tree repr
, tree field
)
2068 unsigned HOST_WIDE_INT bitsize
, maxbitsize
;
2071 size
= size_diffop (DECL_FIELD_OFFSET (field
),
2072 DECL_FIELD_OFFSET (repr
));
2073 while (TREE_CODE (size
) == COMPOUND_EXPR
)
2074 size
= TREE_OPERAND (size
, 1);
2075 gcc_assert (tree_fits_uhwi_p (size
));
2076 bitsize
= (tree_to_uhwi (size
) * BITS_PER_UNIT
2077 + tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field
))
2078 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr
))
2079 + tree_to_uhwi (DECL_SIZE (field
)));
2081 /* Round up bitsize to multiples of BITS_PER_UNIT. */
2082 bitsize
= (bitsize
+ BITS_PER_UNIT
- 1) & ~(BITS_PER_UNIT
- 1);
2084 /* Now nothing tells us how to pad out bitsize ... */
2085 if (TREE_CODE (DECL_CONTEXT (field
)) == RECORD_TYPE
)
2087 nextf
= DECL_CHAIN (field
);
2088 while (nextf
&& TREE_CODE (nextf
) != FIELD_DECL
)
2089 nextf
= DECL_CHAIN (nextf
);
2096 /* If there was an error, the field may be not laid out
2097 correctly. Don't bother to do anything. */
2098 if (TREE_TYPE (nextf
) == error_mark_node
)
2100 TREE_TYPE (repr
) = error_mark_node
;
2103 maxsize
= size_diffop (DECL_FIELD_OFFSET (nextf
),
2104 DECL_FIELD_OFFSET (repr
));
2105 if (tree_fits_uhwi_p (maxsize
))
2107 maxbitsize
= (tree_to_uhwi (maxsize
) * BITS_PER_UNIT
2108 + tree_to_uhwi (DECL_FIELD_BIT_OFFSET (nextf
))
2109 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr
)));
2110 /* If the group ends within a bitfield nextf does not need to be
2111 aligned to BITS_PER_UNIT. Thus round up. */
2112 maxbitsize
= (maxbitsize
+ BITS_PER_UNIT
- 1) & ~(BITS_PER_UNIT
- 1);
2115 maxbitsize
= bitsize
;
2119 /* Note that if the C++ FE sets up tail-padding to be re-used it
2120 creates a as-base variant of the type with TYPE_SIZE adjusted
2121 accordingly. So it is safe to include tail-padding here. */
2122 tree aggsize
= lang_hooks
.types
.unit_size_without_reusable_padding
2123 (DECL_CONTEXT (field
));
2124 tree maxsize
= size_diffop (aggsize
, DECL_FIELD_OFFSET (repr
));
2125 /* We cannot generally rely on maxsize to fold to an integer constant,
2126 so use bitsize as fallback for this case. */
2127 if (tree_fits_uhwi_p (maxsize
))
2128 maxbitsize
= (tree_to_uhwi (maxsize
) * BITS_PER_UNIT
2129 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr
)));
2131 maxbitsize
= bitsize
;
2134 /* Only if we don't artificially break up the representative in
2135 the middle of a large bitfield with different possibly
2136 overlapping representatives. And all representatives start
2138 gcc_assert (maxbitsize
% BITS_PER_UNIT
== 0);
2140 /* Find the smallest nice mode to use. */
2141 opt_scalar_int_mode mode_iter
;
2142 FOR_EACH_MODE_IN_CLASS (mode_iter
, MODE_INT
)
2143 if (GET_MODE_BITSIZE (mode_iter
.require ()) >= bitsize
)
2146 scalar_int_mode mode
;
2147 if (!mode_iter
.exists (&mode
)
2148 || GET_MODE_BITSIZE (mode
) > maxbitsize
2149 || GET_MODE_BITSIZE (mode
) > MAX_FIXED_MODE_SIZE
)
2151 /* We really want a BLKmode representative only as a last resort,
2152 considering the member b in
2153 struct { int a : 7; int b : 17; int c; } __attribute__((packed));
2154 Otherwise we simply want to split the representative up
2155 allowing for overlaps within the bitfield region as required for
2156 struct { int a : 7; int b : 7;
2157 int c : 10; int d; } __attribute__((packed));
2158 [0, 15] HImode for a and b, [8, 23] HImode for c. */
2159 DECL_SIZE (repr
) = bitsize_int (bitsize
);
2160 DECL_SIZE_UNIT (repr
) = size_int (bitsize
/ BITS_PER_UNIT
);
2161 SET_DECL_MODE (repr
, BLKmode
);
2162 TREE_TYPE (repr
) = build_array_type_nelts (unsigned_char_type_node
,
2163 bitsize
/ BITS_PER_UNIT
);
2167 unsigned HOST_WIDE_INT modesize
= GET_MODE_BITSIZE (mode
);
2168 DECL_SIZE (repr
) = bitsize_int (modesize
);
2169 DECL_SIZE_UNIT (repr
) = size_int (modesize
/ BITS_PER_UNIT
);
2170 SET_DECL_MODE (repr
, mode
);
2171 TREE_TYPE (repr
) = lang_hooks
.types
.type_for_mode (mode
, 1);
2174 /* Remember whether the bitfield group is at the end of the
2175 structure or not. */
2176 DECL_CHAIN (repr
) = nextf
;
2179 /* Compute and set FIELD_DECLs for the underlying objects we should
2180 use for bitfield access for the structure T. */
2183 finish_bitfield_layout (tree t
)
2186 tree repr
= NULL_TREE
;
2188 if (TREE_CODE (t
) == QUAL_UNION_TYPE
)
2191 for (prev
= NULL_TREE
, field
= TYPE_FIELDS (t
);
2192 field
; field
= DECL_CHAIN (field
))
2194 if (TREE_CODE (field
) != FIELD_DECL
)
2197 /* In the C++ memory model, consecutive bit fields in a structure are
2198 considered one memory location and updating a memory location
2199 may not store into adjacent memory locations. */
2201 && DECL_BIT_FIELD_TYPE (field
))
2203 /* Start new representative. */
2204 repr
= start_bitfield_representative (field
);
2207 && ! DECL_BIT_FIELD_TYPE (field
))
2209 /* Finish off new representative. */
2210 finish_bitfield_representative (repr
, prev
);
2213 else if (DECL_BIT_FIELD_TYPE (field
))
2215 gcc_assert (repr
!= NULL_TREE
);
2217 /* Zero-size bitfields finish off a representative and
2218 do not have a representative themselves. This is
2219 required by the C++ memory model. */
2220 if (integer_zerop (DECL_SIZE (field
)))
2222 finish_bitfield_representative (repr
, prev
);
2226 /* We assume that either DECL_FIELD_OFFSET of the representative
2227 and each bitfield member is a constant or they are equal.
2228 This is because we need to be able to compute the bit-offset
2229 of each field relative to the representative in get_bit_range
2230 during RTL expansion.
2231 If these constraints are not met, simply force a new
2232 representative to be generated. That will at most
2233 generate worse code but still maintain correctness with
2234 respect to the C++ memory model. */
2235 else if (!((tree_fits_uhwi_p (DECL_FIELD_OFFSET (repr
))
2236 && tree_fits_uhwi_p (DECL_FIELD_OFFSET (field
)))
2237 || operand_equal_p (DECL_FIELD_OFFSET (repr
),
2238 DECL_FIELD_OFFSET (field
), 0)))
2240 finish_bitfield_representative (repr
, prev
);
2241 repr
= start_bitfield_representative (field
);
2248 DECL_BIT_FIELD_REPRESENTATIVE (field
) = repr
;
2250 if (TREE_CODE (t
) == RECORD_TYPE
)
2254 finish_bitfield_representative (repr
, field
);
2260 finish_bitfield_representative (repr
, prev
);
2263 /* Do all of the work required to layout the type indicated by RLI,
2264 once the fields have been laid out. This function will call `free'
2265 for RLI, unless FREE_P is false. Passing a value other than false
2266 for FREE_P is bad practice; this option only exists to support the
2270 finish_record_layout (record_layout_info rli
, int free_p
)
2274 /* Compute the final size. */
2275 finalize_record_size (rli
);
2277 /* Compute the TYPE_MODE for the record. */
2278 compute_record_mode (rli
->t
);
2280 /* Perform any last tweaks to the TYPE_SIZE, etc. */
2281 finalize_type_size (rli
->t
);
2283 /* Compute bitfield representatives. */
2284 finish_bitfield_layout (rli
->t
);
2286 /* Propagate TYPE_PACKED and TYPE_REVERSE_STORAGE_ORDER to variants.
2287 With C++ templates, it is too early to do this when the attribute
2289 for (variant
= TYPE_NEXT_VARIANT (rli
->t
); variant
;
2290 variant
= TYPE_NEXT_VARIANT (variant
))
2292 TYPE_PACKED (variant
) = TYPE_PACKED (rli
->t
);
2293 TYPE_REVERSE_STORAGE_ORDER (variant
)
2294 = TYPE_REVERSE_STORAGE_ORDER (rli
->t
);
2297 /* Lay out any static members. This is done now because their type
2298 may use the record's type. */
2299 while (!vec_safe_is_empty (rli
->pending_statics
))
2300 layout_decl (rli
->pending_statics
->pop (), 0);
2305 vec_free (rli
->pending_statics
);
2311 /* Finish processing a builtin RECORD_TYPE type TYPE. It's name is
2312 NAME, its fields are chained in reverse on FIELDS.
2314 If ALIGN_TYPE is non-null, it is given the same alignment as
2318 finish_builtin_struct (tree type
, const char *name
, tree fields
,
2323 for (tail
= NULL_TREE
; fields
; tail
= fields
, fields
= next
)
2325 DECL_FIELD_CONTEXT (fields
) = type
;
2326 next
= DECL_CHAIN (fields
);
2327 DECL_CHAIN (fields
) = tail
;
2329 TYPE_FIELDS (type
) = tail
;
2333 SET_TYPE_ALIGN (type
, TYPE_ALIGN (align_type
));
2334 TYPE_USER_ALIGN (type
) = TYPE_USER_ALIGN (align_type
);
2335 SET_TYPE_WARN_IF_NOT_ALIGN (type
,
2336 TYPE_WARN_IF_NOT_ALIGN (align_type
));
2340 #if 0 /* not yet, should get fixed properly later */
2341 TYPE_NAME (type
) = make_type_decl (get_identifier (name
), type
);
2343 TYPE_NAME (type
) = build_decl (BUILTINS_LOCATION
,
2344 TYPE_DECL
, get_identifier (name
), type
);
2346 TYPE_STUB_DECL (type
) = TYPE_NAME (type
);
2347 layout_decl (TYPE_NAME (type
), 0);
2350 /* Calculate the mode, size, and alignment for TYPE.
2351 For an array type, calculate the element separation as well.
2352 Record TYPE on the chain of permanent or temporary types
2353 so that dbxout will find out about it.
2355 TYPE_SIZE of a type is nonzero if the type has been laid out already.
2356 layout_type does nothing on such a type.
2358 If the type is incomplete, its TYPE_SIZE remains zero. */
2361 layout_type (tree type
)
2365 if (type
== error_mark_node
)
2368 /* We don't want finalize_type_size to copy an alignment attribute to
2369 variants that don't have it. */
2370 type
= TYPE_MAIN_VARIANT (type
);
2372 /* Do nothing if type has been laid out before. */
2373 if (TYPE_SIZE (type
))
2376 switch (TREE_CODE (type
))
2379 /* This kind of type is the responsibility
2380 of the language-specific code. */
2387 scalar_int_mode mode
2388 = smallest_int_mode_for_size (TYPE_PRECISION (type
));
2389 SET_TYPE_MODE (type
, mode
);
2390 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2391 /* Don't set TYPE_PRECISION here, as it may be set by a bitfield. */
2392 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2398 /* Allow the caller to choose the type mode, which is how decimal
2399 floats are distinguished from binary ones. */
2400 if (TYPE_MODE (type
) == VOIDmode
)
2402 (type
, float_mode_for_size (TYPE_PRECISION (type
)).require ());
2403 scalar_float_mode mode
= as_a
<scalar_float_mode
> (TYPE_MODE (type
));
2404 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2405 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2409 case FIXED_POINT_TYPE
:
2411 /* TYPE_MODE (type) has been set already. */
2412 scalar_mode mode
= SCALAR_TYPE_MODE (type
);
2413 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2414 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2419 TYPE_UNSIGNED (type
) = TYPE_UNSIGNED (TREE_TYPE (type
));
2420 SET_TYPE_MODE (type
,
2421 GET_MODE_COMPLEX_MODE (TYPE_MODE (TREE_TYPE (type
))));
2423 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
2424 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
2429 poly_uint64 nunits
= TYPE_VECTOR_SUBPARTS (type
);
2430 tree innertype
= TREE_TYPE (type
);
2432 /* Find an appropriate mode for the vector type. */
2433 if (TYPE_MODE (type
) == VOIDmode
)
2434 SET_TYPE_MODE (type
,
2435 mode_for_vector (SCALAR_TYPE_MODE (innertype
),
2436 nunits
).else_blk ());
2438 TYPE_SATURATING (type
) = TYPE_SATURATING (TREE_TYPE (type
));
2439 TYPE_UNSIGNED (type
) = TYPE_UNSIGNED (TREE_TYPE (type
));
2440 /* Several boolean vector elements may fit in a single unit. */
2441 if (VECTOR_BOOLEAN_TYPE_P (type
)
2442 && type
->type_common
.mode
!= BLKmode
)
2443 TYPE_SIZE_UNIT (type
)
2444 = size_int (GET_MODE_SIZE (type
->type_common
.mode
));
2446 TYPE_SIZE_UNIT (type
) = int_const_binop (MULT_EXPR
,
2447 TYPE_SIZE_UNIT (innertype
),
2449 TYPE_SIZE (type
) = int_const_binop
2451 bits_from_bytes (TYPE_SIZE_UNIT (type
)),
2452 bitsize_int (BITS_PER_UNIT
));
2454 /* For vector types, we do not default to the mode's alignment.
2455 Instead, query a target hook, defaulting to natural alignment.
2456 This prevents ABI changes depending on whether or not native
2457 vector modes are supported. */
2458 SET_TYPE_ALIGN (type
, targetm
.vector_alignment (type
));
2460 /* However, if the underlying mode requires a bigger alignment than
2461 what the target hook provides, we cannot use the mode. For now,
2462 simply reject that case. */
2463 gcc_assert (TYPE_ALIGN (type
)
2464 >= GET_MODE_ALIGNMENT (TYPE_MODE (type
)));
2469 /* This is an incomplete type and so doesn't have a size. */
2470 SET_TYPE_ALIGN (type
, 1);
2471 TYPE_USER_ALIGN (type
) = 0;
2472 SET_TYPE_MODE (type
, VOIDmode
);
2476 TYPE_SIZE (type
) = bitsize_int (POINTER_SIZE
);
2477 TYPE_SIZE_UNIT (type
) = size_int (POINTER_SIZE_UNITS
);
2478 /* A pointer might be MODE_PARTIAL_INT, but ptrdiff_t must be
2479 integral, which may be an __intN. */
2480 SET_TYPE_MODE (type
, int_mode_for_size (POINTER_SIZE
, 0).require ());
2481 TYPE_PRECISION (type
) = POINTER_SIZE
;
2486 /* It's hard to see what the mode and size of a function ought to
2487 be, but we do know the alignment is FUNCTION_BOUNDARY, so
2488 make it consistent with that. */
2489 SET_TYPE_MODE (type
,
2490 int_mode_for_size (FUNCTION_BOUNDARY
, 0).else_blk ());
2491 TYPE_SIZE (type
) = bitsize_int (FUNCTION_BOUNDARY
);
2492 TYPE_SIZE_UNIT (type
) = size_int (FUNCTION_BOUNDARY
/ BITS_PER_UNIT
);
2496 case REFERENCE_TYPE
:
2498 scalar_int_mode mode
= SCALAR_INT_TYPE_MODE (type
);
2499 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2500 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2501 TYPE_UNSIGNED (type
) = 1;
2502 TYPE_PRECISION (type
) = GET_MODE_PRECISION (mode
);
2508 tree index
= TYPE_DOMAIN (type
);
2509 tree element
= TREE_TYPE (type
);
2511 /* We need to know both bounds in order to compute the size. */
2512 if (index
&& TYPE_MAX_VALUE (index
) && TYPE_MIN_VALUE (index
)
2513 && TYPE_SIZE (element
))
2515 tree ub
= TYPE_MAX_VALUE (index
);
2516 tree lb
= TYPE_MIN_VALUE (index
);
2517 tree element_size
= TYPE_SIZE (element
);
2520 /* Make sure that an array of zero-sized element is zero-sized
2521 regardless of its extent. */
2522 if (integer_zerop (element_size
))
2523 length
= size_zero_node
;
2525 /* The computation should happen in the original signedness so
2526 that (possible) negative values are handled appropriately
2527 when determining overflow. */
2530 /* ??? When it is obvious that the range is signed
2531 represent it using ssizetype. */
2532 if (TREE_CODE (lb
) == INTEGER_CST
2533 && TREE_CODE (ub
) == INTEGER_CST
2534 && TYPE_UNSIGNED (TREE_TYPE (lb
))
2535 && tree_int_cst_lt (ub
, lb
))
2537 lb
= wide_int_to_tree (ssizetype
,
2538 offset_int::from (wi::to_wide (lb
),
2540 ub
= wide_int_to_tree (ssizetype
,
2541 offset_int::from (wi::to_wide (ub
),
2545 = fold_convert (sizetype
,
2546 size_binop (PLUS_EXPR
,
2547 build_int_cst (TREE_TYPE (lb
), 1),
2548 size_binop (MINUS_EXPR
, ub
, lb
)));
2551 /* ??? We have no way to distinguish a null-sized array from an
2552 array spanning the whole sizetype range, so we arbitrarily
2553 decide that [0, -1] is the only valid representation. */
2554 if (integer_zerop (length
)
2555 && TREE_OVERFLOW (length
)
2556 && integer_zerop (lb
))
2557 length
= size_zero_node
;
2559 TYPE_SIZE (type
) = size_binop (MULT_EXPR
, element_size
,
2560 bits_from_bytes (length
));
2562 /* If we know the size of the element, calculate the total size
2563 directly, rather than do some division thing below. This
2564 optimization helps Fortran assumed-size arrays (where the
2565 size of the array is determined at runtime) substantially. */
2566 if (TYPE_SIZE_UNIT (element
))
2567 TYPE_SIZE_UNIT (type
)
2568 = size_binop (MULT_EXPR
, TYPE_SIZE_UNIT (element
), length
);
2571 /* Now round the alignment and size,
2572 using machine-dependent criteria if any. */
2574 unsigned align
= TYPE_ALIGN (element
);
2575 if (TYPE_USER_ALIGN (type
))
2576 align
= MAX (align
, TYPE_ALIGN (type
));
2578 TYPE_USER_ALIGN (type
) = TYPE_USER_ALIGN (element
);
2579 if (!TYPE_WARN_IF_NOT_ALIGN (type
))
2580 SET_TYPE_WARN_IF_NOT_ALIGN (type
,
2581 TYPE_WARN_IF_NOT_ALIGN (element
));
2582 #ifdef ROUND_TYPE_ALIGN
2583 align
= ROUND_TYPE_ALIGN (type
, align
, BITS_PER_UNIT
);
2585 align
= MAX (align
, BITS_PER_UNIT
);
2587 SET_TYPE_ALIGN (type
, align
);
2588 SET_TYPE_MODE (type
, BLKmode
);
2589 if (TYPE_SIZE (type
) != 0
2590 && ! targetm
.member_type_forces_blk (type
, VOIDmode
)
2591 /* BLKmode elements force BLKmode aggregate;
2592 else extract/store fields may lose. */
2593 && (TYPE_MODE (TREE_TYPE (type
)) != BLKmode
2594 || TYPE_NO_FORCE_BLK (TREE_TYPE (type
))))
2596 SET_TYPE_MODE (type
, mode_for_array (TREE_TYPE (type
),
2598 if (TYPE_MODE (type
) != BLKmode
2599 && STRICT_ALIGNMENT
&& TYPE_ALIGN (type
) < BIGGEST_ALIGNMENT
2600 && TYPE_ALIGN (type
) < GET_MODE_ALIGNMENT (TYPE_MODE (type
)))
2602 TYPE_NO_FORCE_BLK (type
) = 1;
2603 SET_TYPE_MODE (type
, BLKmode
);
2606 if (AGGREGATE_TYPE_P (element
))
2607 TYPE_TYPELESS_STORAGE (type
) = TYPE_TYPELESS_STORAGE (element
);
2608 /* When the element size is constant, check that it is at least as
2609 large as the element alignment. */
2610 if (TYPE_SIZE_UNIT (element
)
2611 && TREE_CODE (TYPE_SIZE_UNIT (element
)) == INTEGER_CST
2612 /* If TYPE_SIZE_UNIT overflowed, then it is certainly larger than
2614 && !TREE_OVERFLOW (TYPE_SIZE_UNIT (element
))
2615 && !integer_zerop (TYPE_SIZE_UNIT (element
)))
2617 if (compare_tree_int (TYPE_SIZE_UNIT (element
),
2618 TYPE_ALIGN_UNIT (element
)) < 0)
2619 error ("alignment of array elements is greater than "
2621 else if (TYPE_ALIGN_UNIT (element
) > 1
2622 && (wi::zext (wi::to_wide (TYPE_SIZE_UNIT (element
)),
2623 ffs_hwi (TYPE_ALIGN_UNIT (element
)) - 1)
2625 error ("size of array element is not a multiple of its "
2633 case QUAL_UNION_TYPE
:
2636 record_layout_info rli
;
2638 /* Initialize the layout information. */
2639 rli
= start_record_layout (type
);
2641 /* If this is a QUAL_UNION_TYPE, we want to process the fields
2642 in the reverse order in building the COND_EXPR that denotes
2643 its size. We reverse them again later. */
2644 if (TREE_CODE (type
) == QUAL_UNION_TYPE
)
2645 TYPE_FIELDS (type
) = nreverse (TYPE_FIELDS (type
));
2647 /* Place all the fields. */
2648 for (field
= TYPE_FIELDS (type
); field
; field
= DECL_CHAIN (field
))
2649 place_field (rli
, field
);
2651 if (TREE_CODE (type
) == QUAL_UNION_TYPE
)
2652 TYPE_FIELDS (type
) = nreverse (TYPE_FIELDS (type
));
2654 /* Finish laying out the record. */
2655 finish_record_layout (rli
, /*free_p=*/true);
2663 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
2664 records and unions, finish_record_layout already called this
2666 if (!RECORD_OR_UNION_TYPE_P (type
))
2667 finalize_type_size (type
);
2669 /* We should never see alias sets on incomplete aggregates. And we
2670 should not call layout_type on not incomplete aggregates. */
2671 if (AGGREGATE_TYPE_P (type
))
2672 gcc_assert (!TYPE_ALIAS_SET_KNOWN_P (type
));
2675 /* Return the least alignment required for type TYPE. */
2678 min_align_of_type (tree type
)
2680 unsigned int align
= TYPE_ALIGN (type
);
2681 if (!TYPE_USER_ALIGN (type
))
2683 align
= MIN (align
, BIGGEST_ALIGNMENT
);
2684 #ifdef BIGGEST_FIELD_ALIGNMENT
2685 align
= MIN (align
, BIGGEST_FIELD_ALIGNMENT
);
2687 unsigned int field_align
= align
;
2688 #ifdef ADJUST_FIELD_ALIGN
2689 field_align
= ADJUST_FIELD_ALIGN (NULL_TREE
, type
, field_align
);
2691 align
= MIN (align
, field_align
);
2693 return align
/ BITS_PER_UNIT
;
2696 /* Create and return a type for signed integers of PRECISION bits. */
2699 make_signed_type (int precision
)
2701 tree type
= make_node (INTEGER_TYPE
);
2703 TYPE_PRECISION (type
) = precision
;
2705 fixup_signed_type (type
);
2709 /* Create and return a type for unsigned integers of PRECISION bits. */
2712 make_unsigned_type (int precision
)
2714 tree type
= make_node (INTEGER_TYPE
);
2716 TYPE_PRECISION (type
) = precision
;
2718 fixup_unsigned_type (type
);
2722 /* Create and return a type for fract of PRECISION bits, UNSIGNEDP,
2726 make_fract_type (int precision
, int unsignedp
, int satp
)
2728 tree type
= make_node (FIXED_POINT_TYPE
);
2730 TYPE_PRECISION (type
) = precision
;
2733 TYPE_SATURATING (type
) = 1;
2735 /* Lay out the type: set its alignment, size, etc. */
2736 TYPE_UNSIGNED (type
) = unsignedp
;
2737 enum mode_class mclass
= unsignedp
? MODE_UFRACT
: MODE_FRACT
;
2738 SET_TYPE_MODE (type
, mode_for_size (precision
, mclass
, 0).require ());
2744 /* Create and return a type for accum of PRECISION bits, UNSIGNEDP,
2748 make_accum_type (int precision
, int unsignedp
, int satp
)
2750 tree type
= make_node (FIXED_POINT_TYPE
);
2752 TYPE_PRECISION (type
) = precision
;
2755 TYPE_SATURATING (type
) = 1;
2757 /* Lay out the type: set its alignment, size, etc. */
2758 TYPE_UNSIGNED (type
) = unsignedp
;
2759 enum mode_class mclass
= unsignedp
? MODE_UACCUM
: MODE_ACCUM
;
2760 SET_TYPE_MODE (type
, mode_for_size (precision
, mclass
, 0).require ());
2766 /* Initialize sizetypes so layout_type can use them. */
2769 initialize_sizetypes (void)
2771 int precision
, bprecision
;
2773 /* Get sizetypes precision from the SIZE_TYPE target macro. */
2774 if (strcmp (SIZETYPE
, "unsigned int") == 0)
2775 precision
= INT_TYPE_SIZE
;
2776 else if (strcmp (SIZETYPE
, "long unsigned int") == 0)
2777 precision
= LONG_TYPE_SIZE
;
2778 else if (strcmp (SIZETYPE
, "long long unsigned int") == 0)
2779 precision
= LONG_LONG_TYPE_SIZE
;
2780 else if (strcmp (SIZETYPE
, "short unsigned int") == 0)
2781 precision
= SHORT_TYPE_SIZE
;
2787 for (i
= 0; i
< NUM_INT_N_ENTS
; i
++)
2788 if (int_n_enabled_p
[i
])
2790 char name
[50], altname
[50];
2791 sprintf (name
, "__int%d unsigned", int_n_data
[i
].bitsize
);
2792 sprintf (altname
, "__int%d__ unsigned", int_n_data
[i
].bitsize
);
2794 if (strcmp (name
, SIZETYPE
) == 0
2795 || strcmp (altname
, SIZETYPE
) == 0)
2797 precision
= int_n_data
[i
].bitsize
;
2800 if (precision
== -1)
2805 = MIN (precision
+ LOG2_BITS_PER_UNIT
+ 1, MAX_FIXED_MODE_SIZE
);
2806 bprecision
= GET_MODE_PRECISION (smallest_int_mode_for_size (bprecision
));
2807 if (bprecision
> HOST_BITS_PER_DOUBLE_INT
)
2808 bprecision
= HOST_BITS_PER_DOUBLE_INT
;
2810 /* Create stubs for sizetype and bitsizetype so we can create constants. */
2811 sizetype
= make_node (INTEGER_TYPE
);
2812 TYPE_NAME (sizetype
) = get_identifier ("sizetype");
2813 TYPE_PRECISION (sizetype
) = precision
;
2814 TYPE_UNSIGNED (sizetype
) = 1;
2815 bitsizetype
= make_node (INTEGER_TYPE
);
2816 TYPE_NAME (bitsizetype
) = get_identifier ("bitsizetype");
2817 TYPE_PRECISION (bitsizetype
) = bprecision
;
2818 TYPE_UNSIGNED (bitsizetype
) = 1;
2820 /* Now layout both types manually. */
2821 scalar_int_mode mode
= smallest_int_mode_for_size (precision
);
2822 SET_TYPE_MODE (sizetype
, mode
);
2823 SET_TYPE_ALIGN (sizetype
, GET_MODE_ALIGNMENT (TYPE_MODE (sizetype
)));
2824 TYPE_SIZE (sizetype
) = bitsize_int (precision
);
2825 TYPE_SIZE_UNIT (sizetype
) = size_int (GET_MODE_SIZE (mode
));
2826 set_min_and_max_values_for_integral_type (sizetype
, precision
, UNSIGNED
);
2828 mode
= smallest_int_mode_for_size (bprecision
);
2829 SET_TYPE_MODE (bitsizetype
, mode
);
2830 SET_TYPE_ALIGN (bitsizetype
, GET_MODE_ALIGNMENT (TYPE_MODE (bitsizetype
)));
2831 TYPE_SIZE (bitsizetype
) = bitsize_int (bprecision
);
2832 TYPE_SIZE_UNIT (bitsizetype
) = size_int (GET_MODE_SIZE (mode
));
2833 set_min_and_max_values_for_integral_type (bitsizetype
, bprecision
, UNSIGNED
);
2835 /* Create the signed variants of *sizetype. */
2836 ssizetype
= make_signed_type (TYPE_PRECISION (sizetype
));
2837 TYPE_NAME (ssizetype
) = get_identifier ("ssizetype");
2838 sbitsizetype
= make_signed_type (TYPE_PRECISION (bitsizetype
));
2839 TYPE_NAME (sbitsizetype
) = get_identifier ("sbitsizetype");
2842 /* TYPE is an integral type, i.e., an INTEGRAL_TYPE, ENUMERAL_TYPE
2843 or BOOLEAN_TYPE. Set TYPE_MIN_VALUE and TYPE_MAX_VALUE
2844 for TYPE, based on the PRECISION and whether or not the TYPE
2845 IS_UNSIGNED. PRECISION need not correspond to a width supported
2846 natively by the hardware; for example, on a machine with 8-bit,
2847 16-bit, and 32-bit register modes, PRECISION might be 7, 23, or
2851 set_min_and_max_values_for_integral_type (tree type
,
2855 /* For bitfields with zero width we end up creating integer types
2856 with zero precision. Don't assign any minimum/maximum values
2857 to those types, they don't have any valid value. */
2861 gcc_assert (precision
<= WIDE_INT_MAX_PRECISION
);
2863 TYPE_MIN_VALUE (type
)
2864 = wide_int_to_tree (type
, wi::min_value (precision
, sgn
));
2865 TYPE_MAX_VALUE (type
)
2866 = wide_int_to_tree (type
, wi::max_value (precision
, sgn
));
2869 /* Set the extreme values of TYPE based on its precision in bits,
2870 then lay it out. Used when make_signed_type won't do
2871 because the tree code is not INTEGER_TYPE. */
2874 fixup_signed_type (tree type
)
2876 int precision
= TYPE_PRECISION (type
);
2878 set_min_and_max_values_for_integral_type (type
, precision
, SIGNED
);
2880 /* Lay out the type: set its alignment, size, etc. */
2884 /* Set the extreme values of TYPE based on its precision in bits,
2885 then lay it out. This is used both in `make_unsigned_type'
2886 and for enumeral types. */
2889 fixup_unsigned_type (tree type
)
2891 int precision
= TYPE_PRECISION (type
);
2893 TYPE_UNSIGNED (type
) = 1;
2895 set_min_and_max_values_for_integral_type (type
, precision
, UNSIGNED
);
2897 /* Lay out the type: set its alignment, size, etc. */
2901 /* Construct an iterator for a bitfield that spans BITSIZE bits,
2904 BITREGION_START is the bit position of the first bit in this
2905 sequence of bit fields. BITREGION_END is the last bit in this
2906 sequence. If these two fields are non-zero, we should restrict the
2907 memory access to that range. Otherwise, we are allowed to touch
2908 any adjacent non bit-fields.
2910 ALIGN is the alignment of the underlying object in bits.
2911 VOLATILEP says whether the bitfield is volatile. */
2913 bit_field_mode_iterator
2914 ::bit_field_mode_iterator (HOST_WIDE_INT bitsize
, HOST_WIDE_INT bitpos
,
2915 poly_int64 bitregion_start
,
2916 poly_int64 bitregion_end
,
2917 unsigned int align
, bool volatilep
)
2918 : m_mode (NARROWEST_INT_MODE
), m_bitsize (bitsize
),
2919 m_bitpos (bitpos
), m_bitregion_start (bitregion_start
),
2920 m_bitregion_end (bitregion_end
), m_align (align
),
2921 m_volatilep (volatilep
), m_count (0)
2923 if (known_eq (m_bitregion_end
, 0))
2925 /* We can assume that any aligned chunk of ALIGN bits that overlaps
2926 the bitfield is mapped and won't trap, provided that ALIGN isn't
2927 too large. The cap is the biggest required alignment for data,
2928 or at least the word size. And force one such chunk at least. */
2929 unsigned HOST_WIDE_INT units
2930 = MIN (align
, MAX (BIGGEST_ALIGNMENT
, BITS_PER_WORD
));
2933 HOST_WIDE_INT end
= bitpos
+ bitsize
+ units
- 1;
2934 m_bitregion_end
= end
- end
% units
- 1;
2938 /* Calls to this function return successively larger modes that can be used
2939 to represent the bitfield. Return true if another bitfield mode is
2940 available, storing it in *OUT_MODE if so. */
2943 bit_field_mode_iterator::next_mode (scalar_int_mode
*out_mode
)
2945 scalar_int_mode mode
;
2946 for (; m_mode
.exists (&mode
); m_mode
= GET_MODE_WIDER_MODE (mode
))
2948 unsigned int unit
= GET_MODE_BITSIZE (mode
);
2950 /* Skip modes that don't have full precision. */
2951 if (unit
!= GET_MODE_PRECISION (mode
))
2954 /* Stop if the mode is too wide to handle efficiently. */
2955 if (unit
> MAX_FIXED_MODE_SIZE
)
2958 /* Don't deliver more than one multiword mode; the smallest one
2960 if (m_count
> 0 && unit
> BITS_PER_WORD
)
2963 /* Skip modes that are too small. */
2964 unsigned HOST_WIDE_INT substart
= (unsigned HOST_WIDE_INT
) m_bitpos
% unit
;
2965 unsigned HOST_WIDE_INT subend
= substart
+ m_bitsize
;
2969 /* Stop if the mode goes outside the bitregion. */
2970 HOST_WIDE_INT start
= m_bitpos
- substart
;
2971 if (maybe_ne (m_bitregion_start
, 0)
2972 && maybe_lt (start
, m_bitregion_start
))
2974 HOST_WIDE_INT end
= start
+ unit
;
2975 if (maybe_gt (end
, m_bitregion_end
+ 1))
2978 /* Stop if the mode requires too much alignment. */
2979 if (GET_MODE_ALIGNMENT (mode
) > m_align
2980 && targetm
.slow_unaligned_access (mode
, m_align
))
2984 m_mode
= GET_MODE_WIDER_MODE (mode
);
2991 /* Return true if smaller modes are generally preferred for this kind
2995 bit_field_mode_iterator::prefer_smaller_modes ()
2998 ? targetm
.narrow_volatile_bitfield ()
2999 : !SLOW_BYTE_ACCESS
);
3002 /* Find the best machine mode to use when referencing a bit field of length
3003 BITSIZE bits starting at BITPOS.
3005 BITREGION_START is the bit position of the first bit in this
3006 sequence of bit fields. BITREGION_END is the last bit in this
3007 sequence. If these two fields are non-zero, we should restrict the
3008 memory access to that range. Otherwise, we are allowed to touch
3009 any adjacent non bit-fields.
3011 The chosen mode must have no more than LARGEST_MODE_BITSIZE bits.
3012 INT_MAX is a suitable value for LARGEST_MODE_BITSIZE if the caller
3013 doesn't want to apply a specific limit.
3015 If no mode meets all these conditions, we return VOIDmode.
3017 The underlying object is known to be aligned to a boundary of ALIGN bits.
3019 If VOLATILEP is false and SLOW_BYTE_ACCESS is false, we return the
3020 smallest mode meeting these conditions.
3022 If VOLATILEP is false and SLOW_BYTE_ACCESS is true, we return the
3023 largest mode (but a mode no wider than UNITS_PER_WORD) that meets
3026 If VOLATILEP is true the narrow_volatile_bitfields target hook is used to
3027 decide which of the above modes should be used. */
3030 get_best_mode (int bitsize
, int bitpos
,
3031 poly_uint64 bitregion_start
, poly_uint64 bitregion_end
,
3033 unsigned HOST_WIDE_INT largest_mode_bitsize
, bool volatilep
,
3034 scalar_int_mode
*best_mode
)
3036 bit_field_mode_iterator
iter (bitsize
, bitpos
, bitregion_start
,
3037 bitregion_end
, align
, volatilep
);
3038 scalar_int_mode mode
;
3040 while (iter
.next_mode (&mode
)
3041 /* ??? For historical reasons, reject modes that would normally
3042 receive greater alignment, even if unaligned accesses are
3043 acceptable. This has both advantages and disadvantages.
3044 Removing this check means that something like:
3046 struct s { unsigned int x; unsigned int y; };
3047 int f (struct s *s) { return s->x == 0 && s->y == 0; }
3049 can be implemented using a single load and compare on
3050 64-bit machines that have no alignment restrictions.
3051 For example, on powerpc64-linux-gnu, we would generate:
3073 However, accessing more than one field can make life harder
3074 for the gimple optimizers. For example, gcc.dg/vect/bb-slp-5.c
3075 has a series of unsigned short copies followed by a series of
3076 unsigned short comparisons. With this check, both the copies
3077 and comparisons remain 16-bit accesses and FRE is able
3078 to eliminate the latter. Without the check, the comparisons
3079 can be done using 2 64-bit operations, which FRE isn't able
3080 to handle in the same way.
3082 Either way, it would probably be worth disabling this check
3083 during expand. One particular example where removing the
3084 check would help is the get_best_mode call in store_bit_field.
3085 If we are given a memory bitregion of 128 bits that is aligned
3086 to a 64-bit boundary, and the bitfield we want to modify is
3087 in the second half of the bitregion, this check causes
3088 store_bitfield to turn the memory into a 64-bit reference
3089 to the _first_ half of the region. We later use
3090 adjust_bitfield_address to get a reference to the correct half,
3091 but doing so looks to adjust_bitfield_address as though we are
3092 moving past the end of the original object, so it drops the
3093 associated MEM_EXPR and MEM_OFFSET. Removing the check
3094 causes store_bit_field to keep a 128-bit memory reference,
3095 so that the final bitfield reference still has a MEM_EXPR
3097 && GET_MODE_ALIGNMENT (mode
) <= align
3098 && GET_MODE_BITSIZE (mode
) <= largest_mode_bitsize
)
3102 if (iter
.prefer_smaller_modes ())
3109 /* Gets minimal and maximal values for MODE (signed or unsigned depending on
3110 SIGN). The returned constants are made to be usable in TARGET_MODE. */
3113 get_mode_bounds (scalar_int_mode mode
, int sign
,
3114 scalar_int_mode target_mode
,
3115 rtx
*mmin
, rtx
*mmax
)
3117 unsigned size
= GET_MODE_PRECISION (mode
);
3118 unsigned HOST_WIDE_INT min_val
, max_val
;
3120 gcc_assert (size
<= HOST_BITS_PER_WIDE_INT
);
3122 /* Special case BImode, which has values 0 and STORE_FLAG_VALUE. */
3125 if (STORE_FLAG_VALUE
< 0)
3127 min_val
= STORE_FLAG_VALUE
;
3133 max_val
= STORE_FLAG_VALUE
;
3138 min_val
= -(HOST_WIDE_INT_1U
<< (size
- 1));
3139 max_val
= (HOST_WIDE_INT_1U
<< (size
- 1)) - 1;
3144 max_val
= (HOST_WIDE_INT_1U
<< (size
- 1) << 1) - 1;
3147 *mmin
= gen_int_mode (min_val
, target_mode
);
3148 *mmax
= gen_int_mode (max_val
, target_mode
);
3151 #include "gt-stor-layout.h"