1 /* C-compiler utilities for types and variables storage layout
2 Copyright (C) 1987-2020 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);
398 return opt_scalar_int_mode ();
408 /* Find a mode that can be used for efficient bitwise operations on MODE,
412 bitwise_mode_for_mode (machine_mode mode
)
414 /* Quick exit if we already have a suitable mode. */
415 scalar_int_mode int_mode
;
416 if (is_a
<scalar_int_mode
> (mode
, &int_mode
)
417 && GET_MODE_BITSIZE (int_mode
) <= MAX_FIXED_MODE_SIZE
)
420 /* Reuse the sanity checks from int_mode_for_mode. */
421 gcc_checking_assert ((int_mode_for_mode (mode
), true));
423 poly_int64 bitsize
= GET_MODE_BITSIZE (mode
);
425 /* Try to replace complex modes with complex modes. In general we
426 expect both components to be processed independently, so we only
427 care whether there is a register for the inner mode. */
428 if (COMPLEX_MODE_P (mode
))
430 machine_mode trial
= mode
;
431 if ((GET_MODE_CLASS (trial
) == MODE_COMPLEX_INT
432 || mode_for_size (bitsize
, MODE_COMPLEX_INT
, false).exists (&trial
))
433 && have_regs_of_mode
[GET_MODE_INNER (trial
)])
437 /* Try to replace vector modes with vector modes. Also try using vector
438 modes if an integer mode would be too big. */
439 if (VECTOR_MODE_P (mode
)
440 || maybe_gt (bitsize
, MAX_FIXED_MODE_SIZE
))
442 machine_mode trial
= mode
;
443 if ((GET_MODE_CLASS (trial
) == MODE_VECTOR_INT
444 || mode_for_size (bitsize
, MODE_VECTOR_INT
, 0).exists (&trial
))
445 && have_regs_of_mode
[trial
]
446 && targetm
.vector_mode_supported_p (trial
))
450 /* Otherwise fall back on integers while honoring MAX_FIXED_MODE_SIZE. */
451 return mode_for_size (bitsize
, MODE_INT
, true);
454 /* Find a type that can be used for efficient bitwise operations on MODE.
455 Return null if no such mode exists. */
458 bitwise_type_for_mode (machine_mode mode
)
460 if (!bitwise_mode_for_mode (mode
).exists (&mode
))
463 unsigned int inner_size
= GET_MODE_UNIT_BITSIZE (mode
);
464 tree inner_type
= build_nonstandard_integer_type (inner_size
, true);
466 if (VECTOR_MODE_P (mode
))
467 return build_vector_type_for_mode (inner_type
, mode
);
469 if (COMPLEX_MODE_P (mode
))
470 return build_complex_type (inner_type
);
472 gcc_checking_assert (GET_MODE_INNER (mode
) == mode
);
476 /* Find a mode that is suitable for representing a vector with NUNITS
477 elements of mode INNERMODE, if one exists. The returned mode can be
478 either an integer mode or a vector mode. */
481 mode_for_vector (scalar_mode innermode
, poly_uint64 nunits
)
485 /* First, look for a supported vector type. */
486 if (SCALAR_FLOAT_MODE_P (innermode
))
487 mode
= MIN_MODE_VECTOR_FLOAT
;
488 else if (SCALAR_FRACT_MODE_P (innermode
))
489 mode
= MIN_MODE_VECTOR_FRACT
;
490 else if (SCALAR_UFRACT_MODE_P (innermode
))
491 mode
= MIN_MODE_VECTOR_UFRACT
;
492 else if (SCALAR_ACCUM_MODE_P (innermode
))
493 mode
= MIN_MODE_VECTOR_ACCUM
;
494 else if (SCALAR_UACCUM_MODE_P (innermode
))
495 mode
= MIN_MODE_VECTOR_UACCUM
;
497 mode
= MIN_MODE_VECTOR_INT
;
499 /* Do not check vector_mode_supported_p here. We'll do that
500 later in vector_type_mode. */
501 FOR_EACH_MODE_FROM (mode
, mode
)
502 if (known_eq (GET_MODE_NUNITS (mode
), nunits
)
503 && GET_MODE_INNER (mode
) == innermode
)
506 /* For integers, try mapping it to a same-sized scalar mode. */
507 if (GET_MODE_CLASS (innermode
) == MODE_INT
)
509 poly_uint64 nbits
= nunits
* GET_MODE_BITSIZE (innermode
);
510 if (int_mode_for_size (nbits
, 0).exists (&mode
)
511 && have_regs_of_mode
[mode
])
515 return opt_machine_mode ();
518 /* If a piece of code is using vector mode VECTOR_MODE and also wants
519 to operate on elements of mode ELEMENT_MODE, return the vector mode
520 it should use for those elements. If NUNITS is nonzero, ensure that
521 the mode has exactly NUNITS elements, otherwise pick whichever vector
522 size pairs the most naturally with VECTOR_MODE; this may mean choosing
523 a mode with a different size and/or number of elements, depending on
524 what the target prefers. Return an empty opt_machine_mode if there
525 is no supported vector mode with the required properties.
527 Unlike mode_for_vector. any returned mode is guaranteed to satisfy
528 both VECTOR_MODE_P and targetm.vector_mode_supported_p. */
531 related_vector_mode (machine_mode vector_mode
, scalar_mode element_mode
,
534 gcc_assert (VECTOR_MODE_P (vector_mode
));
535 return targetm
.vectorize
.related_mode (vector_mode
, element_mode
, nunits
);
538 /* If a piece of code is using vector mode VECTOR_MODE and also wants
539 to operate on integer vectors with the same element size and number
540 of elements, return the vector mode it should use. Return an empty
541 opt_machine_mode if there is no supported vector mode with the
544 Unlike mode_for_vector. any returned mode is guaranteed to satisfy
545 both VECTOR_MODE_P and targetm.vector_mode_supported_p. */
548 related_int_vector_mode (machine_mode vector_mode
)
550 gcc_assert (VECTOR_MODE_P (vector_mode
));
551 scalar_int_mode int_mode
;
552 if (int_mode_for_mode (GET_MODE_INNER (vector_mode
)).exists (&int_mode
))
553 return related_vector_mode (vector_mode
, int_mode
,
554 GET_MODE_NUNITS (vector_mode
));
555 return opt_machine_mode ();
558 /* Return the alignment of MODE. This will be bounded by 1 and
559 BIGGEST_ALIGNMENT. */
562 get_mode_alignment (machine_mode mode
)
564 return MIN (BIGGEST_ALIGNMENT
, MAX (1, mode_base_align
[mode
]*BITS_PER_UNIT
));
567 /* Return the natural mode of an array, given that it is SIZE bytes in
568 total and has elements of type ELEM_TYPE. */
571 mode_for_array (tree elem_type
, tree size
)
574 poly_uint64 int_size
, int_elem_size
;
575 unsigned HOST_WIDE_INT num_elems
;
578 /* One-element arrays get the component type's mode. */
579 elem_size
= TYPE_SIZE (elem_type
);
580 if (simple_cst_equal (size
, elem_size
))
581 return TYPE_MODE (elem_type
);
584 if (poly_int_tree_p (size
, &int_size
)
585 && poly_int_tree_p (elem_size
, &int_elem_size
)
586 && maybe_ne (int_elem_size
, 0U)
587 && constant_multiple_p (int_size
, int_elem_size
, &num_elems
))
589 machine_mode elem_mode
= TYPE_MODE (elem_type
);
591 if (targetm
.array_mode (elem_mode
, num_elems
).exists (&mode
))
593 if (targetm
.array_mode_supported_p (elem_mode
, num_elems
))
596 return mode_for_size_tree (size
, MODE_INT
, limit_p
).else_blk ();
599 /* Subroutine of layout_decl: Force alignment required for the data type.
600 But if the decl itself wants greater alignment, don't override that. */
603 do_type_align (tree type
, tree decl
)
605 if (TYPE_ALIGN (type
) > DECL_ALIGN (decl
))
607 SET_DECL_ALIGN (decl
, TYPE_ALIGN (type
));
608 if (TREE_CODE (decl
) == FIELD_DECL
)
609 DECL_USER_ALIGN (decl
) = TYPE_USER_ALIGN (type
);
611 if (TYPE_WARN_IF_NOT_ALIGN (type
) > DECL_WARN_IF_NOT_ALIGN (decl
))
612 SET_DECL_WARN_IF_NOT_ALIGN (decl
, TYPE_WARN_IF_NOT_ALIGN (type
));
615 /* Set the size, mode and alignment of a ..._DECL node.
616 TYPE_DECL does need this for C++.
617 Note that LABEL_DECL and CONST_DECL nodes do not need this,
618 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
619 Don't call layout_decl for them.
621 KNOWN_ALIGN is the amount of alignment we can assume this
622 decl has with no special effort. It is relevant only for FIELD_DECLs
623 and depends on the previous fields.
624 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
625 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
626 the record will be aligned to suit. */
629 layout_decl (tree decl
, unsigned int known_align
)
631 tree type
= TREE_TYPE (decl
);
632 enum tree_code code
= TREE_CODE (decl
);
634 location_t loc
= DECL_SOURCE_LOCATION (decl
);
636 if (code
== CONST_DECL
)
639 gcc_assert (code
== VAR_DECL
|| code
== PARM_DECL
|| code
== RESULT_DECL
640 || code
== TYPE_DECL
|| code
== FIELD_DECL
);
642 rtl
= DECL_RTL_IF_SET (decl
);
644 if (type
== error_mark_node
)
645 type
= void_type_node
;
647 /* Usually the size and mode come from the data type without change,
648 however, the front-end may set the explicit width of the field, so its
649 size may not be the same as the size of its type. This happens with
650 bitfields, of course (an `int' bitfield may be only 2 bits, say), but it
651 also happens with other fields. For example, the C++ front-end creates
652 zero-sized fields corresponding to empty base classes, and depends on
653 layout_type setting DECL_FIELD_BITPOS correctly for the field. Set the
654 size in bytes from the size in bits. If we have already set the mode,
655 don't set it again since we can be called twice for FIELD_DECLs. */
657 DECL_UNSIGNED (decl
) = TYPE_UNSIGNED (type
);
658 if (DECL_MODE (decl
) == VOIDmode
)
659 SET_DECL_MODE (decl
, TYPE_MODE (type
));
661 if (DECL_SIZE (decl
) == 0)
663 DECL_SIZE (decl
) = TYPE_SIZE (type
);
664 DECL_SIZE_UNIT (decl
) = TYPE_SIZE_UNIT (type
);
666 else if (DECL_SIZE_UNIT (decl
) == 0)
667 DECL_SIZE_UNIT (decl
)
668 = fold_convert_loc (loc
, sizetype
,
669 size_binop_loc (loc
, CEIL_DIV_EXPR
, DECL_SIZE (decl
),
672 if (code
!= FIELD_DECL
)
673 /* For non-fields, update the alignment from the type. */
674 do_type_align (type
, decl
);
676 /* For fields, it's a bit more complicated... */
678 bool old_user_align
= DECL_USER_ALIGN (decl
);
679 bool zero_bitfield
= false;
680 bool packed_p
= DECL_PACKED (decl
);
683 if (DECL_BIT_FIELD (decl
))
685 DECL_BIT_FIELD_TYPE (decl
) = type
;
687 /* A zero-length bit-field affects the alignment of the next
688 field. In essence such bit-fields are not influenced by
689 any packing due to #pragma pack or attribute packed. */
690 if (integer_zerop (DECL_SIZE (decl
))
691 && ! targetm
.ms_bitfield_layout_p (DECL_FIELD_CONTEXT (decl
)))
693 zero_bitfield
= true;
695 if (PCC_BITFIELD_TYPE_MATTERS
)
696 do_type_align (type
, decl
);
699 #ifdef EMPTY_FIELD_BOUNDARY
700 if (EMPTY_FIELD_BOUNDARY
> DECL_ALIGN (decl
))
702 SET_DECL_ALIGN (decl
, EMPTY_FIELD_BOUNDARY
);
703 DECL_USER_ALIGN (decl
) = 0;
709 /* See if we can use an ordinary integer mode for a bit-field.
710 Conditions are: a fixed size that is correct for another mode,
711 occupying a complete byte or bytes on proper boundary. */
712 if (TYPE_SIZE (type
) != 0
713 && TREE_CODE (TYPE_SIZE (type
)) == INTEGER_CST
714 && GET_MODE_CLASS (TYPE_MODE (type
)) == MODE_INT
)
717 if (mode_for_size_tree (DECL_SIZE (decl
),
718 MODE_INT
, 1).exists (&xmode
))
720 unsigned int xalign
= GET_MODE_ALIGNMENT (xmode
);
721 if (!(xalign
> BITS_PER_UNIT
&& DECL_PACKED (decl
))
722 && (known_align
== 0 || known_align
>= xalign
))
724 SET_DECL_ALIGN (decl
, MAX (xalign
, DECL_ALIGN (decl
)));
725 SET_DECL_MODE (decl
, xmode
);
726 DECL_BIT_FIELD (decl
) = 0;
731 /* Turn off DECL_BIT_FIELD if we won't need it set. */
732 if (TYPE_MODE (type
) == BLKmode
&& DECL_MODE (decl
) == BLKmode
733 && known_align
>= TYPE_ALIGN (type
)
734 && DECL_ALIGN (decl
) >= TYPE_ALIGN (type
))
735 DECL_BIT_FIELD (decl
) = 0;
737 else if (packed_p
&& DECL_USER_ALIGN (decl
))
738 /* Don't touch DECL_ALIGN. For other packed fields, go ahead and
739 round up; we'll reduce it again below. We want packing to
740 supersede USER_ALIGN inherited from the type, but defer to
741 alignment explicitly specified on the field decl. */;
743 do_type_align (type
, decl
);
745 /* If the field is packed and not explicitly aligned, give it the
746 minimum alignment. Note that do_type_align may set
747 DECL_USER_ALIGN, so we need to check old_user_align instead. */
750 SET_DECL_ALIGN (decl
, MIN (DECL_ALIGN (decl
), BITS_PER_UNIT
));
752 if (! packed_p
&& ! DECL_USER_ALIGN (decl
))
754 /* Some targets (i.e. i386, VMS) limit struct field alignment
755 to a lower boundary than alignment of variables unless
756 it was overridden by attribute aligned. */
757 #ifdef BIGGEST_FIELD_ALIGNMENT
758 SET_DECL_ALIGN (decl
, MIN (DECL_ALIGN (decl
),
759 (unsigned) BIGGEST_FIELD_ALIGNMENT
));
761 #ifdef ADJUST_FIELD_ALIGN
762 SET_DECL_ALIGN (decl
, ADJUST_FIELD_ALIGN (decl
, TREE_TYPE (decl
),
768 mfa
= initial_max_fld_align
* BITS_PER_UNIT
;
770 mfa
= maximum_field_alignment
;
771 /* Should this be controlled by DECL_USER_ALIGN, too? */
773 SET_DECL_ALIGN (decl
, MIN (DECL_ALIGN (decl
), mfa
));
776 /* Evaluate nonconstant size only once, either now or as soon as safe. */
777 if (DECL_SIZE (decl
) != 0 && TREE_CODE (DECL_SIZE (decl
)) != INTEGER_CST
)
778 DECL_SIZE (decl
) = variable_size (DECL_SIZE (decl
));
779 if (DECL_SIZE_UNIT (decl
) != 0
780 && TREE_CODE (DECL_SIZE_UNIT (decl
)) != INTEGER_CST
)
781 DECL_SIZE_UNIT (decl
) = variable_size (DECL_SIZE_UNIT (decl
));
783 /* If requested, warn about definitions of large data objects. */
784 if ((code
== PARM_DECL
|| (code
== VAR_DECL
&& !DECL_NONLOCAL_FRAME (decl
)))
785 && !DECL_EXTERNAL (decl
))
787 tree size
= DECL_SIZE_UNIT (decl
);
789 if (size
!= 0 && TREE_CODE (size
) == INTEGER_CST
)
791 /* -Wlarger-than= argument of HOST_WIDE_INT_MAX is treated
792 as if PTRDIFF_MAX had been specified, with the value
793 being that on the target rather than the host. */
794 unsigned HOST_WIDE_INT max_size
= warn_larger_than_size
;
795 if (max_size
== HOST_WIDE_INT_MAX
)
796 max_size
= tree_to_shwi (TYPE_MAX_VALUE (ptrdiff_type_node
));
798 if (compare_tree_int (size
, max_size
) > 0)
799 warning (OPT_Wlarger_than_
, "size of %q+D %E bytes exceeds "
800 "maximum object size %wu",
801 decl
, size
, max_size
);
805 /* If the RTL was already set, update its mode and mem attributes. */
808 PUT_MODE (rtl
, DECL_MODE (decl
));
809 SET_DECL_RTL (decl
, 0);
811 set_mem_attributes (rtl
, decl
, 1);
812 SET_DECL_RTL (decl
, rtl
);
816 /* Given a VAR_DECL, PARM_DECL, RESULT_DECL, or FIELD_DECL, clears the
817 results of a previous call to layout_decl and calls it again. */
820 relayout_decl (tree decl
)
822 DECL_SIZE (decl
) = DECL_SIZE_UNIT (decl
) = 0;
823 SET_DECL_MODE (decl
, VOIDmode
);
824 if (!DECL_USER_ALIGN (decl
))
825 SET_DECL_ALIGN (decl
, 0);
826 if (DECL_RTL_SET_P (decl
))
827 SET_DECL_RTL (decl
, 0);
829 layout_decl (decl
, 0);
832 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
833 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
834 is to be passed to all other layout functions for this record. It is the
835 responsibility of the caller to call `free' for the storage returned.
836 Note that garbage collection is not permitted until we finish laying
840 start_record_layout (tree t
)
842 record_layout_info rli
= XNEW (struct record_layout_info_s
);
846 /* If the type has a minimum specified alignment (via an attribute
847 declaration, for example) use it -- otherwise, start with a
848 one-byte alignment. */
849 rli
->record_align
= MAX (BITS_PER_UNIT
, TYPE_ALIGN (t
));
850 rli
->unpacked_align
= rli
->record_align
;
851 rli
->offset_align
= MAX (rli
->record_align
, BIGGEST_ALIGNMENT
);
853 #ifdef STRUCTURE_SIZE_BOUNDARY
854 /* Packed structures don't need to have minimum size. */
855 if (! TYPE_PACKED (t
))
859 /* #pragma pack overrides STRUCTURE_SIZE_BOUNDARY. */
860 tmp
= (unsigned) STRUCTURE_SIZE_BOUNDARY
;
861 if (maximum_field_alignment
!= 0)
862 tmp
= MIN (tmp
, maximum_field_alignment
);
863 rli
->record_align
= MAX (rli
->record_align
, tmp
);
867 rli
->offset
= size_zero_node
;
868 rli
->bitpos
= bitsize_zero_node
;
870 rli
->pending_statics
= 0;
871 rli
->packed_maybe_necessary
= 0;
872 rli
->remaining_in_alignment
= 0;
877 /* Fold sizetype value X to bitsizetype, given that X represents a type
881 bits_from_bytes (tree x
)
883 if (POLY_INT_CST_P (x
))
884 /* The runtime calculation isn't allowed to overflow sizetype;
885 increasing the runtime values must always increase the size
886 or offset of the object. This means that the object imposes
887 a maximum value on the runtime parameters, but we don't record
889 return build_poly_int_cst
891 poly_wide_int::from (poly_int_cst_value (x
),
892 TYPE_PRECISION (bitsizetype
),
893 TYPE_SIGN (TREE_TYPE (x
))));
894 x
= fold_convert (bitsizetype
, x
);
895 gcc_checking_assert (x
);
899 /* Return the combined bit position for the byte offset OFFSET and the
902 These functions operate on byte and bit positions present in FIELD_DECLs
903 and assume that these expressions result in no (intermediate) overflow.
904 This assumption is necessary to fold the expressions as much as possible,
905 so as to avoid creating artificially variable-sized types in languages
906 supporting variable-sized types like Ada. */
909 bit_from_pos (tree offset
, tree bitpos
)
911 return size_binop (PLUS_EXPR
, bitpos
,
912 size_binop (MULT_EXPR
, bits_from_bytes (offset
),
916 /* Return the combined truncated byte position for the byte offset OFFSET and
917 the bit position BITPOS. */
920 byte_from_pos (tree offset
, tree bitpos
)
923 if (TREE_CODE (bitpos
) == MULT_EXPR
924 && tree_int_cst_equal (TREE_OPERAND (bitpos
, 1), bitsize_unit_node
))
925 bytepos
= TREE_OPERAND (bitpos
, 0);
927 bytepos
= size_binop (TRUNC_DIV_EXPR
, bitpos
, bitsize_unit_node
);
928 return size_binop (PLUS_EXPR
, offset
, fold_convert (sizetype
, bytepos
));
931 /* Split the bit position POS into a byte offset *POFFSET and a bit
932 position *PBITPOS with the byte offset aligned to OFF_ALIGN bits. */
935 pos_from_bit (tree
*poffset
, tree
*pbitpos
, unsigned int off_align
,
938 tree toff_align
= bitsize_int (off_align
);
939 if (TREE_CODE (pos
) == MULT_EXPR
940 && tree_int_cst_equal (TREE_OPERAND (pos
, 1), toff_align
))
942 *poffset
= size_binop (MULT_EXPR
,
943 fold_convert (sizetype
, TREE_OPERAND (pos
, 0)),
944 size_int (off_align
/ BITS_PER_UNIT
));
945 *pbitpos
= bitsize_zero_node
;
949 *poffset
= size_binop (MULT_EXPR
,
950 fold_convert (sizetype
,
951 size_binop (FLOOR_DIV_EXPR
, pos
,
953 size_int (off_align
/ BITS_PER_UNIT
));
954 *pbitpos
= size_binop (FLOOR_MOD_EXPR
, pos
, toff_align
);
958 /* Given a pointer to bit and byte offsets and an offset alignment,
959 normalize the offsets so they are within the alignment. */
962 normalize_offset (tree
*poffset
, tree
*pbitpos
, unsigned int off_align
)
964 /* If the bit position is now larger than it should be, adjust it
966 if (compare_tree_int (*pbitpos
, off_align
) >= 0)
969 pos_from_bit (&offset
, &bitpos
, off_align
, *pbitpos
);
970 *poffset
= size_binop (PLUS_EXPR
, *poffset
, offset
);
975 /* Print debugging information about the information in RLI. */
978 debug_rli (record_layout_info rli
)
980 print_node_brief (stderr
, "type", rli
->t
, 0);
981 print_node_brief (stderr
, "\noffset", rli
->offset
, 0);
982 print_node_brief (stderr
, " bitpos", rli
->bitpos
, 0);
984 fprintf (stderr
, "\naligns: rec = %u, unpack = %u, off = %u\n",
985 rli
->record_align
, rli
->unpacked_align
,
988 /* The ms_struct code is the only that uses this. */
989 if (targetm
.ms_bitfield_layout_p (rli
->t
))
990 fprintf (stderr
, "remaining in alignment = %u\n", rli
->remaining_in_alignment
);
992 if (rli
->packed_maybe_necessary
)
993 fprintf (stderr
, "packed may be necessary\n");
995 if (!vec_safe_is_empty (rli
->pending_statics
))
997 fprintf (stderr
, "pending statics:\n");
998 debug (rli
->pending_statics
);
1002 /* Given an RLI with a possibly-incremented BITPOS, adjust OFFSET and
1003 BITPOS if necessary to keep BITPOS below OFFSET_ALIGN. */
1006 normalize_rli (record_layout_info rli
)
1008 normalize_offset (&rli
->offset
, &rli
->bitpos
, rli
->offset_align
);
1011 /* Returns the size in bytes allocated so far. */
1014 rli_size_unit_so_far (record_layout_info rli
)
1016 return byte_from_pos (rli
->offset
, rli
->bitpos
);
1019 /* Returns the size in bits allocated so far. */
1022 rli_size_so_far (record_layout_info rli
)
1024 return bit_from_pos (rli
->offset
, rli
->bitpos
);
1027 /* FIELD is about to be added to RLI->T. The alignment (in bits) of
1028 the next available location within the record is given by KNOWN_ALIGN.
1029 Update the variable alignment fields in RLI, and return the alignment
1030 to give the FIELD. */
1033 update_alignment_for_field (record_layout_info rli
, tree field
,
1034 unsigned int known_align
)
1036 /* The alignment required for FIELD. */
1037 unsigned int desired_align
;
1038 /* The type of this field. */
1039 tree type
= TREE_TYPE (field
);
1040 /* True if the field was explicitly aligned by the user. */
1044 /* Do not attempt to align an ERROR_MARK node */
1045 if (TREE_CODE (type
) == ERROR_MARK
)
1048 /* Lay out the field so we know what alignment it needs. */
1049 layout_decl (field
, known_align
);
1050 desired_align
= DECL_ALIGN (field
);
1051 user_align
= DECL_USER_ALIGN (field
);
1053 is_bitfield
= (type
!= error_mark_node
1054 && DECL_BIT_FIELD_TYPE (field
)
1055 && ! integer_zerop (TYPE_SIZE (type
)));
1057 /* Record must have at least as much alignment as any field.
1058 Otherwise, the alignment of the field within the record is
1060 if (targetm
.ms_bitfield_layout_p (rli
->t
))
1062 /* Here, the alignment of the underlying type of a bitfield can
1063 affect the alignment of a record; even a zero-sized field
1064 can do this. The alignment should be to the alignment of
1065 the type, except that for zero-size bitfields this only
1066 applies if there was an immediately prior, nonzero-size
1067 bitfield. (That's the way it is, experimentally.) */
1069 || ((DECL_SIZE (field
) == NULL_TREE
1070 || !integer_zerop (DECL_SIZE (field
)))
1071 ? !DECL_PACKED (field
)
1073 && DECL_BIT_FIELD_TYPE (rli
->prev_field
)
1074 && ! integer_zerop (DECL_SIZE (rli
->prev_field
)))))
1076 unsigned int type_align
= TYPE_ALIGN (type
);
1077 if (!is_bitfield
&& DECL_PACKED (field
))
1078 type_align
= desired_align
;
1080 type_align
= MAX (type_align
, desired_align
);
1081 if (maximum_field_alignment
!= 0)
1082 type_align
= MIN (type_align
, maximum_field_alignment
);
1083 rli
->record_align
= MAX (rli
->record_align
, type_align
);
1084 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
1087 else if (is_bitfield
&& PCC_BITFIELD_TYPE_MATTERS
)
1089 /* Named bit-fields cause the entire structure to have the
1090 alignment implied by their type. Some targets also apply the same
1091 rules to unnamed bitfields. */
1092 if (DECL_NAME (field
) != 0
1093 || targetm
.align_anon_bitfield ())
1095 unsigned int type_align
= TYPE_ALIGN (type
);
1097 #ifdef ADJUST_FIELD_ALIGN
1098 if (! TYPE_USER_ALIGN (type
))
1099 type_align
= ADJUST_FIELD_ALIGN (field
, type
, type_align
);
1102 /* Targets might chose to handle unnamed and hence possibly
1103 zero-width bitfield. Those are not influenced by #pragmas
1104 or packed attributes. */
1105 if (integer_zerop (DECL_SIZE (field
)))
1107 if (initial_max_fld_align
)
1108 type_align
= MIN (type_align
,
1109 initial_max_fld_align
* BITS_PER_UNIT
);
1111 else if (maximum_field_alignment
!= 0)
1112 type_align
= MIN (type_align
, maximum_field_alignment
);
1113 else if (DECL_PACKED (field
))
1114 type_align
= MIN (type_align
, BITS_PER_UNIT
);
1116 /* The alignment of the record is increased to the maximum
1117 of the current alignment, the alignment indicated on the
1118 field (i.e., the alignment specified by an __aligned__
1119 attribute), and the alignment indicated by the type of
1121 rli
->record_align
= MAX (rli
->record_align
, desired_align
);
1122 rli
->record_align
= MAX (rli
->record_align
, type_align
);
1125 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
1126 user_align
|= TYPE_USER_ALIGN (type
);
1131 rli
->record_align
= MAX (rli
->record_align
, desired_align
);
1132 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
1135 TYPE_USER_ALIGN (rli
->t
) |= user_align
;
1137 return desired_align
;
1140 /* Issue a warning if the record alignment, RECORD_ALIGN, is less than
1141 the field alignment of FIELD or FIELD isn't aligned. */
1144 handle_warn_if_not_align (tree field
, unsigned int record_align
)
1146 tree type
= TREE_TYPE (field
);
1148 if (type
== error_mark_node
)
1151 unsigned int warn_if_not_align
= 0;
1155 if (warn_if_not_aligned
)
1157 warn_if_not_align
= DECL_WARN_IF_NOT_ALIGN (field
);
1158 if (!warn_if_not_align
)
1159 warn_if_not_align
= TYPE_WARN_IF_NOT_ALIGN (type
);
1160 if (warn_if_not_align
)
1161 opt_w
= OPT_Wif_not_aligned
;
1164 if (!warn_if_not_align
1165 && warn_packed_not_aligned
1166 && lookup_attribute ("aligned", TYPE_ATTRIBUTES (type
)))
1168 warn_if_not_align
= TYPE_ALIGN (type
);
1169 opt_w
= OPT_Wpacked_not_aligned
;
1172 if (!warn_if_not_align
)
1175 tree context
= DECL_CONTEXT (field
);
1177 warn_if_not_align
/= BITS_PER_UNIT
;
1178 record_align
/= BITS_PER_UNIT
;
1179 if ((record_align
% warn_if_not_align
) != 0)
1180 warning (opt_w
, "alignment %u of %qT is less than %u",
1181 record_align
, context
, warn_if_not_align
);
1183 tree off
= byte_position (field
);
1184 if (!multiple_of_p (TREE_TYPE (off
), off
, size_int (warn_if_not_align
)))
1186 if (TREE_CODE (off
) == INTEGER_CST
)
1187 warning (opt_w
, "%q+D offset %E in %qT isn%'t aligned to %u",
1188 field
, off
, context
, warn_if_not_align
);
1190 warning (opt_w
, "%q+D offset %E in %qT may not be aligned to %u",
1191 field
, off
, context
, warn_if_not_align
);
1195 /* Called from place_field to handle unions. */
1198 place_union_field (record_layout_info rli
, tree field
)
1200 update_alignment_for_field (rli
, field
, /*known_align=*/0);
1202 DECL_FIELD_OFFSET (field
) = size_zero_node
;
1203 DECL_FIELD_BIT_OFFSET (field
) = bitsize_zero_node
;
1204 SET_DECL_OFFSET_ALIGN (field
, BIGGEST_ALIGNMENT
);
1205 handle_warn_if_not_align (field
, rli
->record_align
);
1207 /* If this is an ERROR_MARK return *after* having set the
1208 field at the start of the union. This helps when parsing
1210 if (TREE_CODE (TREE_TYPE (field
)) == ERROR_MARK
)
1213 if (AGGREGATE_TYPE_P (TREE_TYPE (field
))
1214 && TYPE_TYPELESS_STORAGE (TREE_TYPE (field
)))
1215 TYPE_TYPELESS_STORAGE (rli
->t
) = 1;
1217 /* We assume the union's size will be a multiple of a byte so we don't
1218 bother with BITPOS. */
1219 if (TREE_CODE (rli
->t
) == UNION_TYPE
)
1220 rli
->offset
= size_binop (MAX_EXPR
, rli
->offset
, DECL_SIZE_UNIT (field
));
1221 else if (TREE_CODE (rli
->t
) == QUAL_UNION_TYPE
)
1222 rli
->offset
= fold_build3 (COND_EXPR
, sizetype
, DECL_QUALIFIER (field
),
1223 DECL_SIZE_UNIT (field
), rli
->offset
);
1226 /* A bitfield of SIZE with a required access alignment of ALIGN is allocated
1227 at BYTE_OFFSET / BIT_OFFSET. Return nonzero if the field would span more
1228 units of alignment than the underlying TYPE. */
1230 excess_unit_span (HOST_WIDE_INT byte_offset
, HOST_WIDE_INT bit_offset
,
1231 HOST_WIDE_INT size
, HOST_WIDE_INT align
, tree type
)
1233 /* Note that the calculation of OFFSET might overflow; we calculate it so
1234 that we still get the right result as long as ALIGN is a power of two. */
1235 unsigned HOST_WIDE_INT offset
= byte_offset
* BITS_PER_UNIT
+ bit_offset
;
1237 offset
= offset
% align
;
1238 return ((offset
+ size
+ align
- 1) / align
1239 > tree_to_uhwi (TYPE_SIZE (type
)) / align
);
1242 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
1243 is a FIELD_DECL to be added after those fields already present in
1244 T. (FIELD is not actually added to the TYPE_FIELDS list here;
1245 callers that desire that behavior must manually perform that step.) */
1248 place_field (record_layout_info rli
, tree field
)
1250 /* The alignment required for FIELD. */
1251 unsigned int desired_align
;
1252 /* The alignment FIELD would have if we just dropped it into the
1253 record as it presently stands. */
1254 unsigned int known_align
;
1255 unsigned int actual_align
;
1256 /* The type of this field. */
1257 tree type
= TREE_TYPE (field
);
1259 gcc_assert (TREE_CODE (field
) != ERROR_MARK
);
1261 /* If FIELD is static, then treat it like a separate variable, not
1262 really like a structure field. If it is a FUNCTION_DECL, it's a
1263 method. In both cases, all we do is lay out the decl, and we do
1264 it *after* the record is laid out. */
1267 vec_safe_push (rli
->pending_statics
, field
);
1271 /* Enumerators and enum types which are local to this class need not
1272 be laid out. Likewise for initialized constant fields. */
1273 else if (TREE_CODE (field
) != FIELD_DECL
)
1276 /* Unions are laid out very differently than records, so split
1277 that code off to another function. */
1278 else if (TREE_CODE (rli
->t
) != RECORD_TYPE
)
1280 place_union_field (rli
, field
);
1284 else if (TREE_CODE (type
) == ERROR_MARK
)
1286 /* Place this field at the current allocation position, so we
1287 maintain monotonicity. */
1288 DECL_FIELD_OFFSET (field
) = rli
->offset
;
1289 DECL_FIELD_BIT_OFFSET (field
) = rli
->bitpos
;
1290 SET_DECL_OFFSET_ALIGN (field
, rli
->offset_align
);
1291 handle_warn_if_not_align (field
, rli
->record_align
);
1295 if (AGGREGATE_TYPE_P (type
)
1296 && TYPE_TYPELESS_STORAGE (type
))
1297 TYPE_TYPELESS_STORAGE (rli
->t
) = 1;
1299 /* Work out the known alignment so far. Note that A & (-A) is the
1300 value of the least-significant bit in A that is one. */
1301 if (! integer_zerop (rli
->bitpos
))
1302 known_align
= least_bit_hwi (tree_to_uhwi (rli
->bitpos
));
1303 else if (integer_zerop (rli
->offset
))
1305 else if (tree_fits_uhwi_p (rli
->offset
))
1306 known_align
= (BITS_PER_UNIT
1307 * least_bit_hwi (tree_to_uhwi (rli
->offset
)));
1309 known_align
= rli
->offset_align
;
1311 desired_align
= update_alignment_for_field (rli
, field
, known_align
);
1312 if (known_align
== 0)
1313 known_align
= MAX (BIGGEST_ALIGNMENT
, rli
->record_align
);
1315 if (warn_packed
&& DECL_PACKED (field
))
1317 if (known_align
>= TYPE_ALIGN (type
))
1319 if (TYPE_ALIGN (type
) > desired_align
)
1321 if (STRICT_ALIGNMENT
)
1322 warning (OPT_Wattributes
, "packed attribute causes "
1323 "inefficient alignment for %q+D", field
);
1324 /* Don't warn if DECL_PACKED was set by the type. */
1325 else if (!TYPE_PACKED (rli
->t
))
1326 warning (OPT_Wattributes
, "packed attribute is "
1327 "unnecessary for %q+D", field
);
1331 rli
->packed_maybe_necessary
= 1;
1334 /* Does this field automatically have alignment it needs by virtue
1335 of the fields that precede it and the record's own alignment? */
1336 if (known_align
< desired_align
1337 && (! targetm
.ms_bitfield_layout_p (rli
->t
)
1338 || rli
->prev_field
== NULL
))
1340 /* No, we need to skip space before this field.
1341 Bump the cumulative size to multiple of field alignment. */
1343 if (!targetm
.ms_bitfield_layout_p (rli
->t
)
1344 && DECL_SOURCE_LOCATION (field
) != BUILTINS_LOCATION
)
1345 warning (OPT_Wpadded
, "padding struct to align %q+D", field
);
1347 /* If the alignment is still within offset_align, just align
1348 the bit position. */
1349 if (desired_align
< rli
->offset_align
)
1350 rli
->bitpos
= round_up (rli
->bitpos
, desired_align
);
1353 /* First adjust OFFSET by the partial bits, then align. */
1355 = size_binop (PLUS_EXPR
, rli
->offset
,
1356 fold_convert (sizetype
,
1357 size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
1358 bitsize_unit_node
)));
1359 rli
->bitpos
= bitsize_zero_node
;
1361 rli
->offset
= round_up (rli
->offset
, desired_align
/ BITS_PER_UNIT
);
1364 if (! TREE_CONSTANT (rli
->offset
))
1365 rli
->offset_align
= desired_align
;
1368 /* Handle compatibility with PCC. Note that if the record has any
1369 variable-sized fields, we need not worry about compatibility. */
1370 if (PCC_BITFIELD_TYPE_MATTERS
1371 && ! targetm
.ms_bitfield_layout_p (rli
->t
)
1372 && TREE_CODE (field
) == FIELD_DECL
1373 && type
!= error_mark_node
1374 && DECL_BIT_FIELD (field
)
1375 && (! DECL_PACKED (field
)
1376 /* Enter for these packed fields only to issue a warning. */
1377 || TYPE_ALIGN (type
) <= BITS_PER_UNIT
)
1378 && maximum_field_alignment
== 0
1379 && ! integer_zerop (DECL_SIZE (field
))
1380 && tree_fits_uhwi_p (DECL_SIZE (field
))
1381 && tree_fits_uhwi_p (rli
->offset
)
1382 && tree_fits_uhwi_p (TYPE_SIZE (type
)))
1384 unsigned int type_align
= TYPE_ALIGN (type
);
1385 tree dsize
= DECL_SIZE (field
);
1386 HOST_WIDE_INT field_size
= tree_to_uhwi (dsize
);
1387 HOST_WIDE_INT offset
= tree_to_uhwi (rli
->offset
);
1388 HOST_WIDE_INT bit_offset
= tree_to_shwi (rli
->bitpos
);
1390 #ifdef ADJUST_FIELD_ALIGN
1391 if (! TYPE_USER_ALIGN (type
))
1392 type_align
= ADJUST_FIELD_ALIGN (field
, type
, type_align
);
1395 /* A bit field may not span more units of alignment of its type
1396 than its type itself. Advance to next boundary if necessary. */
1397 if (excess_unit_span (offset
, bit_offset
, field_size
, type_align
, type
))
1399 if (DECL_PACKED (field
))
1401 if (warn_packed_bitfield_compat
== 1)
1404 "offset of packed bit-field %qD has changed in GCC 4.4",
1408 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1411 if (! DECL_PACKED (field
))
1412 TYPE_USER_ALIGN (rli
->t
) |= TYPE_USER_ALIGN (type
);
1414 SET_TYPE_WARN_IF_NOT_ALIGN (rli
->t
,
1415 TYPE_WARN_IF_NOT_ALIGN (type
));
1418 #ifdef BITFIELD_NBYTES_LIMITED
1419 if (BITFIELD_NBYTES_LIMITED
1420 && ! targetm
.ms_bitfield_layout_p (rli
->t
)
1421 && TREE_CODE (field
) == FIELD_DECL
1422 && type
!= error_mark_node
1423 && DECL_BIT_FIELD_TYPE (field
)
1424 && ! DECL_PACKED (field
)
1425 && ! integer_zerop (DECL_SIZE (field
))
1426 && tree_fits_uhwi_p (DECL_SIZE (field
))
1427 && tree_fits_uhwi_p (rli
->offset
)
1428 && tree_fits_uhwi_p (TYPE_SIZE (type
)))
1430 unsigned int type_align
= TYPE_ALIGN (type
);
1431 tree dsize
= DECL_SIZE (field
);
1432 HOST_WIDE_INT field_size
= tree_to_uhwi (dsize
);
1433 HOST_WIDE_INT offset
= tree_to_uhwi (rli
->offset
);
1434 HOST_WIDE_INT bit_offset
= tree_to_shwi (rli
->bitpos
);
1436 #ifdef ADJUST_FIELD_ALIGN
1437 if (! TYPE_USER_ALIGN (type
))
1438 type_align
= ADJUST_FIELD_ALIGN (field
, type
, type_align
);
1441 if (maximum_field_alignment
!= 0)
1442 type_align
= MIN (type_align
, maximum_field_alignment
);
1443 /* ??? This test is opposite the test in the containing if
1444 statement, so this code is unreachable currently. */
1445 else if (DECL_PACKED (field
))
1446 type_align
= MIN (type_align
, BITS_PER_UNIT
);
1448 /* A bit field may not span the unit of alignment of its type.
1449 Advance to next boundary if necessary. */
1450 if (excess_unit_span (offset
, bit_offset
, field_size
, type_align
, type
))
1451 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1453 TYPE_USER_ALIGN (rli
->t
) |= TYPE_USER_ALIGN (type
);
1454 SET_TYPE_WARN_IF_NOT_ALIGN (rli
->t
,
1455 TYPE_WARN_IF_NOT_ALIGN (type
));
1459 /* See the docs for TARGET_MS_BITFIELD_LAYOUT_P for details.
1461 When a bit field is inserted into a packed record, the whole
1462 size of the underlying type is used by one or more same-size
1463 adjacent bitfields. (That is, if its long:3, 32 bits is
1464 used in the record, and any additional adjacent long bitfields are
1465 packed into the same chunk of 32 bits. However, if the size
1466 changes, a new field of that size is allocated.) In an unpacked
1467 record, this is the same as using alignment, but not equivalent
1470 Note: for compatibility, we use the type size, not the type alignment
1471 to determine alignment, since that matches the documentation */
1473 if (targetm
.ms_bitfield_layout_p (rli
->t
))
1475 tree prev_saved
= rli
->prev_field
;
1476 tree prev_type
= prev_saved
? DECL_BIT_FIELD_TYPE (prev_saved
) : NULL
;
1478 /* This is a bitfield if it exists. */
1479 if (rli
->prev_field
)
1481 bool realign_p
= known_align
< desired_align
;
1483 /* If both are bitfields, nonzero, and the same size, this is
1484 the middle of a run. Zero declared size fields are special
1485 and handled as "end of run". (Note: it's nonzero declared
1486 size, but equal type sizes!) (Since we know that both
1487 the current and previous fields are bitfields by the
1488 time we check it, DECL_SIZE must be present for both.) */
1489 if (DECL_BIT_FIELD_TYPE (field
)
1490 && !integer_zerop (DECL_SIZE (field
))
1491 && !integer_zerop (DECL_SIZE (rli
->prev_field
))
1492 && tree_fits_shwi_p (DECL_SIZE (rli
->prev_field
))
1493 && tree_fits_uhwi_p (TYPE_SIZE (type
))
1494 && simple_cst_equal (TYPE_SIZE (type
), TYPE_SIZE (prev_type
)))
1496 /* We're in the middle of a run of equal type size fields; make
1497 sure we realign if we run out of bits. (Not decl size,
1499 HOST_WIDE_INT bitsize
= tree_to_uhwi (DECL_SIZE (field
));
1501 if (rli
->remaining_in_alignment
< bitsize
)
1503 HOST_WIDE_INT typesize
= tree_to_uhwi (TYPE_SIZE (type
));
1505 /* out of bits; bump up to next 'word'. */
1507 = size_binop (PLUS_EXPR
, rli
->bitpos
,
1508 bitsize_int (rli
->remaining_in_alignment
));
1509 rli
->prev_field
= field
;
1510 if (typesize
< bitsize
)
1511 rli
->remaining_in_alignment
= 0;
1513 rli
->remaining_in_alignment
= typesize
- bitsize
;
1517 rli
->remaining_in_alignment
-= bitsize
;
1523 /* End of a run: if leaving a run of bitfields of the same type
1524 size, we have to "use up" the rest of the bits of the type
1527 Compute the new position as the sum of the size for the prior
1528 type and where we first started working on that type.
1529 Note: since the beginning of the field was aligned then
1530 of course the end will be too. No round needed. */
1532 if (!integer_zerop (DECL_SIZE (rli
->prev_field
)))
1535 = size_binop (PLUS_EXPR
, rli
->bitpos
,
1536 bitsize_int (rli
->remaining_in_alignment
));
1539 /* We "use up" size zero fields; the code below should behave
1540 as if the prior field was not a bitfield. */
1543 /* Cause a new bitfield to be captured, either this time (if
1544 currently a bitfield) or next time we see one. */
1545 if (!DECL_BIT_FIELD_TYPE (field
)
1546 || integer_zerop (DECL_SIZE (field
)))
1547 rli
->prev_field
= NULL
;
1550 /* Does this field automatically have alignment it needs by virtue
1551 of the fields that precede it and the record's own alignment? */
1554 /* If the alignment is still within offset_align, just align
1555 the bit position. */
1556 if (desired_align
< rli
->offset_align
)
1557 rli
->bitpos
= round_up (rli
->bitpos
, desired_align
);
1560 /* First adjust OFFSET by the partial bits, then align. */
1561 tree d
= size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
1563 rli
->offset
= size_binop (PLUS_EXPR
, rli
->offset
,
1564 fold_convert (sizetype
, d
));
1565 rli
->bitpos
= bitsize_zero_node
;
1567 rli
->offset
= round_up (rli
->offset
,
1568 desired_align
/ BITS_PER_UNIT
);
1571 if (! TREE_CONSTANT (rli
->offset
))
1572 rli
->offset_align
= desired_align
;
1575 normalize_rli (rli
);
1578 /* If we're starting a new run of same type size bitfields
1579 (or a run of non-bitfields), set up the "first of the run"
1582 That is, if the current field is not a bitfield, or if there
1583 was a prior bitfield the type sizes differ, or if there wasn't
1584 a prior bitfield the size of the current field is nonzero.
1586 Note: we must be sure to test ONLY the type size if there was
1587 a prior bitfield and ONLY for the current field being zero if
1590 if (!DECL_BIT_FIELD_TYPE (field
)
1591 || (prev_saved
!= NULL
1592 ? !simple_cst_equal (TYPE_SIZE (type
), TYPE_SIZE (prev_type
))
1593 : !integer_zerop (DECL_SIZE (field
))))
1595 /* Never smaller than a byte for compatibility. */
1596 unsigned int type_align
= BITS_PER_UNIT
;
1598 /* (When not a bitfield), we could be seeing a flex array (with
1599 no DECL_SIZE). Since we won't be using remaining_in_alignment
1600 until we see a bitfield (and come by here again) we just skip
1602 if (DECL_SIZE (field
) != NULL
1603 && tree_fits_uhwi_p (TYPE_SIZE (TREE_TYPE (field
)))
1604 && tree_fits_uhwi_p (DECL_SIZE (field
)))
1606 unsigned HOST_WIDE_INT bitsize
1607 = tree_to_uhwi (DECL_SIZE (field
));
1608 unsigned HOST_WIDE_INT typesize
1609 = tree_to_uhwi (TYPE_SIZE (TREE_TYPE (field
)));
1611 if (typesize
< bitsize
)
1612 rli
->remaining_in_alignment
= 0;
1614 rli
->remaining_in_alignment
= typesize
- bitsize
;
1617 /* Now align (conventionally) for the new type. */
1618 if (! DECL_PACKED (field
))
1619 type_align
= TYPE_ALIGN (TREE_TYPE (field
));
1621 if (maximum_field_alignment
!= 0)
1622 type_align
= MIN (type_align
, maximum_field_alignment
);
1624 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1626 /* If we really aligned, don't allow subsequent bitfields
1628 rli
->prev_field
= NULL
;
1632 /* Offset so far becomes the position of this field after normalizing. */
1633 normalize_rli (rli
);
1634 DECL_FIELD_OFFSET (field
) = rli
->offset
;
1635 DECL_FIELD_BIT_OFFSET (field
) = rli
->bitpos
;
1636 SET_DECL_OFFSET_ALIGN (field
, rli
->offset_align
);
1637 handle_warn_if_not_align (field
, rli
->record_align
);
1639 /* Evaluate nonconstant offsets only once, either now or as soon as safe. */
1640 if (TREE_CODE (DECL_FIELD_OFFSET (field
)) != INTEGER_CST
)
1641 DECL_FIELD_OFFSET (field
) = variable_size (DECL_FIELD_OFFSET (field
));
1643 /* If this field ended up more aligned than we thought it would be (we
1644 approximate this by seeing if its position changed), lay out the field
1645 again; perhaps we can use an integral mode for it now. */
1646 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field
)))
1647 actual_align
= least_bit_hwi (tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field
)));
1648 else if (integer_zerop (DECL_FIELD_OFFSET (field
)))
1649 actual_align
= MAX (BIGGEST_ALIGNMENT
, rli
->record_align
);
1650 else if (tree_fits_uhwi_p (DECL_FIELD_OFFSET (field
)))
1651 actual_align
= (BITS_PER_UNIT
1652 * least_bit_hwi (tree_to_uhwi (DECL_FIELD_OFFSET (field
))));
1654 actual_align
= DECL_OFFSET_ALIGN (field
);
1655 /* ACTUAL_ALIGN is still the actual alignment *within the record* .
1656 store / extract bit field operations will check the alignment of the
1657 record against the mode of bit fields. */
1659 if (known_align
!= actual_align
)
1660 layout_decl (field
, actual_align
);
1662 if (rli
->prev_field
== NULL
&& DECL_BIT_FIELD_TYPE (field
))
1663 rli
->prev_field
= field
;
1665 /* Now add size of this field to the size of the record. If the size is
1666 not constant, treat the field as being a multiple of bytes and just
1667 adjust the offset, resetting the bit position. Otherwise, apportion the
1668 size amongst the bit position and offset. First handle the case of an
1669 unspecified size, which can happen when we have an invalid nested struct
1670 definition, such as struct j { struct j { int i; } }. The error message
1671 is printed in finish_struct. */
1672 if (DECL_SIZE (field
) == 0)
1674 else if (TREE_CODE (DECL_SIZE (field
)) != INTEGER_CST
1675 || TREE_OVERFLOW (DECL_SIZE (field
)))
1678 = size_binop (PLUS_EXPR
, rli
->offset
,
1679 fold_convert (sizetype
,
1680 size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
1681 bitsize_unit_node
)));
1683 = size_binop (PLUS_EXPR
, rli
->offset
, DECL_SIZE_UNIT (field
));
1684 rli
->bitpos
= bitsize_zero_node
;
1685 rli
->offset_align
= MIN (rli
->offset_align
, desired_align
);
1687 if (!multiple_of_p (bitsizetype
, DECL_SIZE (field
),
1688 bitsize_int (rli
->offset_align
)))
1690 tree type
= strip_array_types (TREE_TYPE (field
));
1691 /* The above adjusts offset_align just based on the start of the
1692 field. The field might not have a size that is a multiple of
1693 that offset_align though. If the field is an array of fixed
1694 sized elements, assume there can be any multiple of those
1695 sizes. If it is a variable length aggregate or array of
1696 variable length aggregates, assume worst that the end is
1697 just BITS_PER_UNIT aligned. */
1698 if (TREE_CODE (TYPE_SIZE (type
)) == INTEGER_CST
)
1700 if (TREE_INT_CST_LOW (TYPE_SIZE (type
)))
1702 unsigned HOST_WIDE_INT sz
1703 = least_bit_hwi (TREE_INT_CST_LOW (TYPE_SIZE (type
)));
1704 rli
->offset_align
= MIN (rli
->offset_align
, sz
);
1708 rli
->offset_align
= MIN (rli
->offset_align
, BITS_PER_UNIT
);
1711 else if (targetm
.ms_bitfield_layout_p (rli
->t
))
1713 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
, DECL_SIZE (field
));
1715 /* If FIELD is the last field and doesn't end at the full length
1716 of the type then pad the struct out to the full length of the
1718 if (DECL_BIT_FIELD_TYPE (field
)
1719 && !integer_zerop (DECL_SIZE (field
)))
1721 /* We have to scan, because non-field DECLS are also here. */
1723 while ((probe
= DECL_CHAIN (probe
)))
1724 if (TREE_CODE (probe
) == FIELD_DECL
)
1727 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
,
1728 bitsize_int (rli
->remaining_in_alignment
));
1731 normalize_rli (rli
);
1735 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
, DECL_SIZE (field
));
1736 normalize_rli (rli
);
1740 /* Assuming that all the fields have been laid out, this function uses
1741 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
1742 indicated by RLI. */
1745 finalize_record_size (record_layout_info rli
)
1747 tree unpadded_size
, unpadded_size_unit
;
1749 /* Now we want just byte and bit offsets, so set the offset alignment
1750 to be a byte and then normalize. */
1751 rli
->offset_align
= BITS_PER_UNIT
;
1752 normalize_rli (rli
);
1754 /* Determine the desired alignment. */
1755 #ifdef ROUND_TYPE_ALIGN
1756 SET_TYPE_ALIGN (rli
->t
, ROUND_TYPE_ALIGN (rli
->t
, TYPE_ALIGN (rli
->t
),
1757 rli
->record_align
));
1759 SET_TYPE_ALIGN (rli
->t
, MAX (TYPE_ALIGN (rli
->t
), rli
->record_align
));
1762 /* Compute the size so far. Be sure to allow for extra bits in the
1763 size in bytes. We have guaranteed above that it will be no more
1764 than a single byte. */
1765 unpadded_size
= rli_size_so_far (rli
);
1766 unpadded_size_unit
= rli_size_unit_so_far (rli
);
1767 if (! integer_zerop (rli
->bitpos
))
1769 = size_binop (PLUS_EXPR
, unpadded_size_unit
, size_one_node
);
1771 /* Round the size up to be a multiple of the required alignment. */
1772 TYPE_SIZE (rli
->t
) = round_up (unpadded_size
, TYPE_ALIGN (rli
->t
));
1773 TYPE_SIZE_UNIT (rli
->t
)
1774 = round_up (unpadded_size_unit
, TYPE_ALIGN_UNIT (rli
->t
));
1776 if (TREE_CONSTANT (unpadded_size
)
1777 && simple_cst_equal (unpadded_size
, TYPE_SIZE (rli
->t
)) == 0
1778 && input_location
!= BUILTINS_LOCATION
)
1779 warning (OPT_Wpadded
, "padding struct size to alignment boundary");
1781 if (warn_packed
&& TREE_CODE (rli
->t
) == RECORD_TYPE
1782 && TYPE_PACKED (rli
->t
) && ! rli
->packed_maybe_necessary
1783 && TREE_CONSTANT (unpadded_size
))
1787 #ifdef ROUND_TYPE_ALIGN
1789 = ROUND_TYPE_ALIGN (rli
->t
, TYPE_ALIGN (rli
->t
), rli
->unpacked_align
);
1791 rli
->unpacked_align
= MAX (TYPE_ALIGN (rli
->t
), rli
->unpacked_align
);
1794 unpacked_size
= round_up (TYPE_SIZE (rli
->t
), rli
->unpacked_align
);
1795 if (simple_cst_equal (unpacked_size
, TYPE_SIZE (rli
->t
)))
1797 if (TYPE_NAME (rli
->t
))
1801 if (TREE_CODE (TYPE_NAME (rli
->t
)) == IDENTIFIER_NODE
)
1802 name
= TYPE_NAME (rli
->t
);
1804 name
= DECL_NAME (TYPE_NAME (rli
->t
));
1806 if (STRICT_ALIGNMENT
)
1807 warning (OPT_Wpacked
, "packed attribute causes inefficient "
1808 "alignment for %qE", name
);
1810 warning (OPT_Wpacked
,
1811 "packed attribute is unnecessary for %qE", name
);
1815 if (STRICT_ALIGNMENT
)
1816 warning (OPT_Wpacked
,
1817 "packed attribute causes inefficient alignment");
1819 warning (OPT_Wpacked
, "packed attribute is unnecessary");
1825 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
1828 compute_record_mode (tree type
)
1831 machine_mode mode
= VOIDmode
;
1833 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
1834 However, if possible, we use a mode that fits in a register
1835 instead, in order to allow for better optimization down the
1837 SET_TYPE_MODE (type
, BLKmode
);
1839 poly_uint64 type_size
;
1840 if (!poly_int_tree_p (TYPE_SIZE (type
), &type_size
))
1843 /* A record which has any BLKmode members must itself be
1844 BLKmode; it can't go in a register. Unless the member is
1845 BLKmode only because it isn't aligned. */
1846 for (field
= TYPE_FIELDS (type
); field
; field
= DECL_CHAIN (field
))
1848 if (TREE_CODE (field
) != FIELD_DECL
)
1851 poly_uint64 field_size
;
1852 if (TREE_CODE (TREE_TYPE (field
)) == ERROR_MARK
1853 || (TYPE_MODE (TREE_TYPE (field
)) == BLKmode
1854 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field
))
1855 && !(TYPE_SIZE (TREE_TYPE (field
)) != 0
1856 && integer_zerop (TYPE_SIZE (TREE_TYPE (field
)))))
1857 || !tree_fits_poly_uint64_p (bit_position (field
))
1858 || DECL_SIZE (field
) == 0
1859 || !poly_int_tree_p (DECL_SIZE (field
), &field_size
))
1862 /* If this field is the whole struct, remember its mode so
1863 that, say, we can put a double in a class into a DF
1864 register instead of forcing it to live in the stack. */
1865 if (known_eq (field_size
, type_size
)
1866 /* Partial int types (e.g. __int20) may have TYPE_SIZE equal to
1867 wider types (e.g. int32), despite precision being less. Ensure
1868 that the TYPE_MODE of the struct does not get set to the partial
1869 int mode if there is a wider type also in the struct. */
1870 && known_gt (GET_MODE_PRECISION (DECL_MODE (field
)),
1871 GET_MODE_PRECISION (mode
)))
1872 mode
= DECL_MODE (field
);
1874 /* With some targets, it is sub-optimal to access an aligned
1875 BLKmode structure as a scalar. */
1876 if (targetm
.member_type_forces_blk (field
, mode
))
1880 /* If we only have one real field; use its mode if that mode's size
1881 matches the type's size. This generally only applies to RECORD_TYPE.
1882 For UNION_TYPE, if the widest field is MODE_INT then use that mode.
1883 If the widest field is MODE_PARTIAL_INT, and the union will be passed
1884 by reference, then use that mode. */
1885 if ((TREE_CODE (type
) == RECORD_TYPE
1886 || (TREE_CODE (type
) == UNION_TYPE
1887 && (GET_MODE_CLASS (mode
) == MODE_INT
1888 || (GET_MODE_CLASS (mode
) == MODE_PARTIAL_INT
1889 && (targetm
.calls
.pass_by_reference
1890 (pack_cumulative_args (0),
1891 function_arg_info (type
, mode
, /*named=*/false)))))))
1893 && known_eq (GET_MODE_BITSIZE (mode
), type_size
))
1896 mode
= mode_for_size_tree (TYPE_SIZE (type
), MODE_INT
, 1).else_blk ();
1898 /* If structure's known alignment is less than what the scalar
1899 mode would need, and it matters, then stick with BLKmode. */
1902 && ! (TYPE_ALIGN (type
) >= BIGGEST_ALIGNMENT
1903 || TYPE_ALIGN (type
) >= GET_MODE_ALIGNMENT (mode
)))
1905 /* If this is the only reason this type is BLKmode, then
1906 don't force containing types to be BLKmode. */
1907 TYPE_NO_FORCE_BLK (type
) = 1;
1911 SET_TYPE_MODE (type
, mode
);
1914 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1918 finalize_type_size (tree type
)
1920 /* Normally, use the alignment corresponding to the mode chosen.
1921 However, where strict alignment is not required, avoid
1922 over-aligning structures, since most compilers do not do this
1924 if (TYPE_MODE (type
) != BLKmode
1925 && TYPE_MODE (type
) != VOIDmode
1926 && (STRICT_ALIGNMENT
|| !AGGREGATE_TYPE_P (type
)))
1928 unsigned mode_align
= GET_MODE_ALIGNMENT (TYPE_MODE (type
));
1930 /* Don't override a larger alignment requirement coming from a user
1931 alignment of one of the fields. */
1932 if (mode_align
>= TYPE_ALIGN (type
))
1934 SET_TYPE_ALIGN (type
, mode_align
);
1935 TYPE_USER_ALIGN (type
) = 0;
1939 /* Do machine-dependent extra alignment. */
1940 #ifdef ROUND_TYPE_ALIGN
1941 SET_TYPE_ALIGN (type
,
1942 ROUND_TYPE_ALIGN (type
, TYPE_ALIGN (type
), BITS_PER_UNIT
));
1945 /* If we failed to find a simple way to calculate the unit size
1946 of the type, find it by division. */
1947 if (TYPE_SIZE_UNIT (type
) == 0 && TYPE_SIZE (type
) != 0)
1948 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1949 result will fit in sizetype. We will get more efficient code using
1950 sizetype, so we force a conversion. */
1951 TYPE_SIZE_UNIT (type
)
1952 = fold_convert (sizetype
,
1953 size_binop (FLOOR_DIV_EXPR
, TYPE_SIZE (type
),
1954 bitsize_unit_node
));
1956 if (TYPE_SIZE (type
) != 0)
1958 TYPE_SIZE (type
) = round_up (TYPE_SIZE (type
), TYPE_ALIGN (type
));
1959 TYPE_SIZE_UNIT (type
)
1960 = round_up (TYPE_SIZE_UNIT (type
), TYPE_ALIGN_UNIT (type
));
1963 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1964 if (TYPE_SIZE (type
) != 0 && TREE_CODE (TYPE_SIZE (type
)) != INTEGER_CST
)
1965 TYPE_SIZE (type
) = variable_size (TYPE_SIZE (type
));
1966 if (TYPE_SIZE_UNIT (type
) != 0
1967 && TREE_CODE (TYPE_SIZE_UNIT (type
)) != INTEGER_CST
)
1968 TYPE_SIZE_UNIT (type
) = variable_size (TYPE_SIZE_UNIT (type
));
1970 /* Handle empty records as per the x86-64 psABI. */
1971 TYPE_EMPTY_P (type
) = targetm
.calls
.empty_record_p (type
);
1973 /* Also layout any other variants of the type. */
1974 if (TYPE_NEXT_VARIANT (type
)
1975 || type
!= TYPE_MAIN_VARIANT (type
))
1978 /* Record layout info of this variant. */
1979 tree size
= TYPE_SIZE (type
);
1980 tree size_unit
= TYPE_SIZE_UNIT (type
);
1981 unsigned int align
= TYPE_ALIGN (type
);
1982 unsigned int precision
= TYPE_PRECISION (type
);
1983 unsigned int user_align
= TYPE_USER_ALIGN (type
);
1984 machine_mode mode
= TYPE_MODE (type
);
1985 bool empty_p
= TYPE_EMPTY_P (type
);
1987 /* Copy it into all variants. */
1988 for (variant
= TYPE_MAIN_VARIANT (type
);
1990 variant
= TYPE_NEXT_VARIANT (variant
))
1992 TYPE_SIZE (variant
) = size
;
1993 TYPE_SIZE_UNIT (variant
) = size_unit
;
1994 unsigned valign
= align
;
1995 if (TYPE_USER_ALIGN (variant
))
1996 valign
= MAX (valign
, TYPE_ALIGN (variant
));
1998 TYPE_USER_ALIGN (variant
) = user_align
;
1999 SET_TYPE_ALIGN (variant
, valign
);
2000 TYPE_PRECISION (variant
) = precision
;
2001 SET_TYPE_MODE (variant
, mode
);
2002 TYPE_EMPTY_P (variant
) = empty_p
;
2007 /* Return a new underlying object for a bitfield started with FIELD. */
2010 start_bitfield_representative (tree field
)
2012 tree repr
= make_node (FIELD_DECL
);
2013 DECL_FIELD_OFFSET (repr
) = DECL_FIELD_OFFSET (field
);
2014 /* Force the representative to begin at a BITS_PER_UNIT aligned
2015 boundary - C++ may use tail-padding of a base object to
2016 continue packing bits so the bitfield region does not start
2017 at bit zero (see g++.dg/abi/bitfield5.C for example).
2018 Unallocated bits may happen for other reasons as well,
2019 for example Ada which allows explicit bit-granular structure layout. */
2020 DECL_FIELD_BIT_OFFSET (repr
)
2021 = size_binop (BIT_AND_EXPR
,
2022 DECL_FIELD_BIT_OFFSET (field
),
2023 bitsize_int (~(BITS_PER_UNIT
- 1)));
2024 SET_DECL_OFFSET_ALIGN (repr
, DECL_OFFSET_ALIGN (field
));
2025 DECL_SIZE (repr
) = DECL_SIZE (field
);
2026 DECL_SIZE_UNIT (repr
) = DECL_SIZE_UNIT (field
);
2027 DECL_PACKED (repr
) = DECL_PACKED (field
);
2028 DECL_CONTEXT (repr
) = DECL_CONTEXT (field
);
2029 /* There are no indirect accesses to this field. If we introduce
2030 some then they have to use the record alias set. This makes
2031 sure to properly conflict with [indirect] accesses to addressable
2032 fields of the bitfield group. */
2033 DECL_NONADDRESSABLE_P (repr
) = 1;
2037 /* Finish up a bitfield group that was started by creating the underlying
2038 object REPR with the last field in the bitfield group FIELD. */
2041 finish_bitfield_representative (tree repr
, tree field
)
2043 unsigned HOST_WIDE_INT bitsize
, maxbitsize
;
2046 size
= size_diffop (DECL_FIELD_OFFSET (field
),
2047 DECL_FIELD_OFFSET (repr
));
2048 while (TREE_CODE (size
) == COMPOUND_EXPR
)
2049 size
= TREE_OPERAND (size
, 1);
2050 gcc_assert (tree_fits_uhwi_p (size
));
2051 bitsize
= (tree_to_uhwi (size
) * BITS_PER_UNIT
2052 + tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field
))
2053 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr
))
2054 + tree_to_uhwi (DECL_SIZE (field
)));
2056 /* Round up bitsize to multiples of BITS_PER_UNIT. */
2057 bitsize
= (bitsize
+ BITS_PER_UNIT
- 1) & ~(BITS_PER_UNIT
- 1);
2059 /* Now nothing tells us how to pad out bitsize ... */
2060 nextf
= DECL_CHAIN (field
);
2061 while (nextf
&& TREE_CODE (nextf
) != FIELD_DECL
)
2062 nextf
= DECL_CHAIN (nextf
);
2066 /* If there was an error, the field may be not laid out
2067 correctly. Don't bother to do anything. */
2068 if (TREE_TYPE (nextf
) == error_mark_node
)
2070 maxsize
= size_diffop (DECL_FIELD_OFFSET (nextf
),
2071 DECL_FIELD_OFFSET (repr
));
2072 if (tree_fits_uhwi_p (maxsize
))
2074 maxbitsize
= (tree_to_uhwi (maxsize
) * BITS_PER_UNIT
2075 + tree_to_uhwi (DECL_FIELD_BIT_OFFSET (nextf
))
2076 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr
)));
2077 /* If the group ends within a bitfield nextf does not need to be
2078 aligned to BITS_PER_UNIT. Thus round up. */
2079 maxbitsize
= (maxbitsize
+ BITS_PER_UNIT
- 1) & ~(BITS_PER_UNIT
- 1);
2082 maxbitsize
= bitsize
;
2086 /* Note that if the C++ FE sets up tail-padding to be re-used it
2087 creates a as-base variant of the type with TYPE_SIZE adjusted
2088 accordingly. So it is safe to include tail-padding here. */
2089 tree aggsize
= lang_hooks
.types
.unit_size_without_reusable_padding
2090 (DECL_CONTEXT (field
));
2091 tree maxsize
= size_diffop (aggsize
, DECL_FIELD_OFFSET (repr
));
2092 /* We cannot generally rely on maxsize to fold to an integer constant,
2093 so use bitsize as fallback for this case. */
2094 if (tree_fits_uhwi_p (maxsize
))
2095 maxbitsize
= (tree_to_uhwi (maxsize
) * BITS_PER_UNIT
2096 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr
)));
2098 maxbitsize
= bitsize
;
2101 /* Only if we don't artificially break up the representative in
2102 the middle of a large bitfield with different possibly
2103 overlapping representatives. And all representatives start
2105 gcc_assert (maxbitsize
% BITS_PER_UNIT
== 0);
2107 /* Find the smallest nice mode to use. */
2108 opt_scalar_int_mode mode_iter
;
2109 FOR_EACH_MODE_IN_CLASS (mode_iter
, MODE_INT
)
2110 if (GET_MODE_BITSIZE (mode_iter
.require ()) >= bitsize
)
2113 scalar_int_mode mode
;
2114 if (!mode_iter
.exists (&mode
)
2115 || GET_MODE_BITSIZE (mode
) > maxbitsize
2116 || GET_MODE_BITSIZE (mode
) > MAX_FIXED_MODE_SIZE
)
2118 /* We really want a BLKmode representative only as a last resort,
2119 considering the member b in
2120 struct { int a : 7; int b : 17; int c; } __attribute__((packed));
2121 Otherwise we simply want to split the representative up
2122 allowing for overlaps within the bitfield region as required for
2123 struct { int a : 7; int b : 7;
2124 int c : 10; int d; } __attribute__((packed));
2125 [0, 15] HImode for a and b, [8, 23] HImode for c. */
2126 DECL_SIZE (repr
) = bitsize_int (bitsize
);
2127 DECL_SIZE_UNIT (repr
) = size_int (bitsize
/ BITS_PER_UNIT
);
2128 SET_DECL_MODE (repr
, BLKmode
);
2129 TREE_TYPE (repr
) = build_array_type_nelts (unsigned_char_type_node
,
2130 bitsize
/ BITS_PER_UNIT
);
2134 unsigned HOST_WIDE_INT modesize
= GET_MODE_BITSIZE (mode
);
2135 DECL_SIZE (repr
) = bitsize_int (modesize
);
2136 DECL_SIZE_UNIT (repr
) = size_int (modesize
/ BITS_PER_UNIT
);
2137 SET_DECL_MODE (repr
, mode
);
2138 TREE_TYPE (repr
) = lang_hooks
.types
.type_for_mode (mode
, 1);
2141 /* Remember whether the bitfield group is at the end of the
2142 structure or not. */
2143 DECL_CHAIN (repr
) = nextf
;
2146 /* Compute and set FIELD_DECLs for the underlying objects we should
2147 use for bitfield access for the structure T. */
2150 finish_bitfield_layout (tree t
)
2153 tree repr
= NULL_TREE
;
2155 /* Unions would be special, for the ease of type-punning optimizations
2156 we could use the underlying type as hint for the representative
2157 if the bitfield would fit and the representative would not exceed
2158 the union in size. */
2159 if (TREE_CODE (t
) != RECORD_TYPE
)
2162 for (prev
= NULL_TREE
, field
= TYPE_FIELDS (t
);
2163 field
; field
= DECL_CHAIN (field
))
2165 if (TREE_CODE (field
) != FIELD_DECL
)
2168 /* In the C++ memory model, consecutive bit fields in a structure are
2169 considered one memory location and updating a memory location
2170 may not store into adjacent memory locations. */
2172 && DECL_BIT_FIELD_TYPE (field
))
2174 /* Start new representative. */
2175 repr
= start_bitfield_representative (field
);
2178 && ! DECL_BIT_FIELD_TYPE (field
))
2180 /* Finish off new representative. */
2181 finish_bitfield_representative (repr
, prev
);
2184 else if (DECL_BIT_FIELD_TYPE (field
))
2186 gcc_assert (repr
!= NULL_TREE
);
2188 /* Zero-size bitfields finish off a representative and
2189 do not have a representative themselves. This is
2190 required by the C++ memory model. */
2191 if (integer_zerop (DECL_SIZE (field
)))
2193 finish_bitfield_representative (repr
, prev
);
2197 /* We assume that either DECL_FIELD_OFFSET of the representative
2198 and each bitfield member is a constant or they are equal.
2199 This is because we need to be able to compute the bit-offset
2200 of each field relative to the representative in get_bit_range
2201 during RTL expansion.
2202 If these constraints are not met, simply force a new
2203 representative to be generated. That will at most
2204 generate worse code but still maintain correctness with
2205 respect to the C++ memory model. */
2206 else if (!((tree_fits_uhwi_p (DECL_FIELD_OFFSET (repr
))
2207 && tree_fits_uhwi_p (DECL_FIELD_OFFSET (field
)))
2208 || operand_equal_p (DECL_FIELD_OFFSET (repr
),
2209 DECL_FIELD_OFFSET (field
), 0)))
2211 finish_bitfield_representative (repr
, prev
);
2212 repr
= start_bitfield_representative (field
);
2219 DECL_BIT_FIELD_REPRESENTATIVE (field
) = repr
;
2225 finish_bitfield_representative (repr
, prev
);
2228 /* Do all of the work required to layout the type indicated by RLI,
2229 once the fields have been laid out. This function will call `free'
2230 for RLI, unless FREE_P is false. Passing a value other than false
2231 for FREE_P is bad practice; this option only exists to support the
2235 finish_record_layout (record_layout_info rli
, int free_p
)
2239 /* Compute the final size. */
2240 finalize_record_size (rli
);
2242 /* Compute the TYPE_MODE for the record. */
2243 compute_record_mode (rli
->t
);
2245 /* Perform any last tweaks to the TYPE_SIZE, etc. */
2246 finalize_type_size (rli
->t
);
2248 /* Compute bitfield representatives. */
2249 finish_bitfield_layout (rli
->t
);
2251 /* Propagate TYPE_PACKED and TYPE_REVERSE_STORAGE_ORDER to variants.
2252 With C++ templates, it is too early to do this when the attribute
2254 for (variant
= TYPE_NEXT_VARIANT (rli
->t
); variant
;
2255 variant
= TYPE_NEXT_VARIANT (variant
))
2257 TYPE_PACKED (variant
) = TYPE_PACKED (rli
->t
);
2258 TYPE_REVERSE_STORAGE_ORDER (variant
)
2259 = TYPE_REVERSE_STORAGE_ORDER (rli
->t
);
2262 /* Lay out any static members. This is done now because their type
2263 may use the record's type. */
2264 while (!vec_safe_is_empty (rli
->pending_statics
))
2265 layout_decl (rli
->pending_statics
->pop (), 0);
2270 vec_free (rli
->pending_statics
);
2276 /* Finish processing a builtin RECORD_TYPE type TYPE. It's name is
2277 NAME, its fields are chained in reverse on FIELDS.
2279 If ALIGN_TYPE is non-null, it is given the same alignment as
2283 finish_builtin_struct (tree type
, const char *name
, tree fields
,
2288 for (tail
= NULL_TREE
; fields
; tail
= fields
, fields
= next
)
2290 DECL_FIELD_CONTEXT (fields
) = type
;
2291 next
= DECL_CHAIN (fields
);
2292 DECL_CHAIN (fields
) = tail
;
2294 TYPE_FIELDS (type
) = tail
;
2298 SET_TYPE_ALIGN (type
, TYPE_ALIGN (align_type
));
2299 TYPE_USER_ALIGN (type
) = TYPE_USER_ALIGN (align_type
);
2300 SET_TYPE_WARN_IF_NOT_ALIGN (type
,
2301 TYPE_WARN_IF_NOT_ALIGN (align_type
));
2305 #if 0 /* not yet, should get fixed properly later */
2306 TYPE_NAME (type
) = make_type_decl (get_identifier (name
), type
);
2308 TYPE_NAME (type
) = build_decl (BUILTINS_LOCATION
,
2309 TYPE_DECL
, get_identifier (name
), type
);
2311 TYPE_STUB_DECL (type
) = TYPE_NAME (type
);
2312 layout_decl (TYPE_NAME (type
), 0);
2315 /* Calculate the mode, size, and alignment for TYPE.
2316 For an array type, calculate the element separation as well.
2317 Record TYPE on the chain of permanent or temporary types
2318 so that dbxout will find out about it.
2320 TYPE_SIZE of a type is nonzero if the type has been laid out already.
2321 layout_type does nothing on such a type.
2323 If the type is incomplete, its TYPE_SIZE remains zero. */
2326 layout_type (tree type
)
2330 if (type
== error_mark_node
)
2333 /* We don't want finalize_type_size to copy an alignment attribute to
2334 variants that don't have it. */
2335 type
= TYPE_MAIN_VARIANT (type
);
2337 /* Do nothing if type has been laid out before. */
2338 if (TYPE_SIZE (type
))
2341 switch (TREE_CODE (type
))
2344 /* This kind of type is the responsibility
2345 of the language-specific code. */
2352 scalar_int_mode mode
2353 = smallest_int_mode_for_size (TYPE_PRECISION (type
));
2354 SET_TYPE_MODE (type
, mode
);
2355 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2356 /* Don't set TYPE_PRECISION here, as it may be set by a bitfield. */
2357 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2363 /* Allow the caller to choose the type mode, which is how decimal
2364 floats are distinguished from binary ones. */
2365 if (TYPE_MODE (type
) == VOIDmode
)
2367 (type
, float_mode_for_size (TYPE_PRECISION (type
)).require ());
2368 scalar_float_mode mode
= as_a
<scalar_float_mode
> (TYPE_MODE (type
));
2369 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2370 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2374 case FIXED_POINT_TYPE
:
2376 /* TYPE_MODE (type) has been set already. */
2377 scalar_mode mode
= SCALAR_TYPE_MODE (type
);
2378 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2379 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2384 TYPE_UNSIGNED (type
) = TYPE_UNSIGNED (TREE_TYPE (type
));
2385 SET_TYPE_MODE (type
,
2386 GET_MODE_COMPLEX_MODE (TYPE_MODE (TREE_TYPE (type
))));
2388 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
2389 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
2394 poly_uint64 nunits
= TYPE_VECTOR_SUBPARTS (type
);
2395 tree innertype
= TREE_TYPE (type
);
2397 /* Find an appropriate mode for the vector type. */
2398 if (TYPE_MODE (type
) == VOIDmode
)
2399 SET_TYPE_MODE (type
,
2400 mode_for_vector (SCALAR_TYPE_MODE (innertype
),
2401 nunits
).else_blk ());
2403 TYPE_SATURATING (type
) = TYPE_SATURATING (TREE_TYPE (type
));
2404 TYPE_UNSIGNED (type
) = TYPE_UNSIGNED (TREE_TYPE (type
));
2405 /* Several boolean vector elements may fit in a single unit. */
2406 if (VECTOR_BOOLEAN_TYPE_P (type
)
2407 && type
->type_common
.mode
!= BLKmode
)
2408 TYPE_SIZE_UNIT (type
)
2409 = size_int (GET_MODE_SIZE (type
->type_common
.mode
));
2411 TYPE_SIZE_UNIT (type
) = int_const_binop (MULT_EXPR
,
2412 TYPE_SIZE_UNIT (innertype
),
2414 TYPE_SIZE (type
) = int_const_binop
2416 bits_from_bytes (TYPE_SIZE_UNIT (type
)),
2417 bitsize_int (BITS_PER_UNIT
));
2419 /* For vector types, we do not default to the mode's alignment.
2420 Instead, query a target hook, defaulting to natural alignment.
2421 This prevents ABI changes depending on whether or not native
2422 vector modes are supported. */
2423 SET_TYPE_ALIGN (type
, targetm
.vector_alignment (type
));
2425 /* However, if the underlying mode requires a bigger alignment than
2426 what the target hook provides, we cannot use the mode. For now,
2427 simply reject that case. */
2428 gcc_assert (TYPE_ALIGN (type
)
2429 >= GET_MODE_ALIGNMENT (TYPE_MODE (type
)));
2434 /* This is an incomplete type and so doesn't have a size. */
2435 SET_TYPE_ALIGN (type
, 1);
2436 TYPE_USER_ALIGN (type
) = 0;
2437 SET_TYPE_MODE (type
, VOIDmode
);
2441 TYPE_SIZE (type
) = bitsize_int (POINTER_SIZE
);
2442 TYPE_SIZE_UNIT (type
) = size_int (POINTER_SIZE_UNITS
);
2443 /* A pointer might be MODE_PARTIAL_INT, but ptrdiff_t must be
2444 integral, which may be an __intN. */
2445 SET_TYPE_MODE (type
, int_mode_for_size (POINTER_SIZE
, 0).require ());
2446 TYPE_PRECISION (type
) = POINTER_SIZE
;
2451 /* It's hard to see what the mode and size of a function ought to
2452 be, but we do know the alignment is FUNCTION_BOUNDARY, so
2453 make it consistent with that. */
2454 SET_TYPE_MODE (type
,
2455 int_mode_for_size (FUNCTION_BOUNDARY
, 0).else_blk ());
2456 TYPE_SIZE (type
) = bitsize_int (FUNCTION_BOUNDARY
);
2457 TYPE_SIZE_UNIT (type
) = size_int (FUNCTION_BOUNDARY
/ BITS_PER_UNIT
);
2461 case REFERENCE_TYPE
:
2463 scalar_int_mode mode
= SCALAR_INT_TYPE_MODE (type
);
2464 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2465 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2466 TYPE_UNSIGNED (type
) = 1;
2467 TYPE_PRECISION (type
) = GET_MODE_PRECISION (mode
);
2473 tree index
= TYPE_DOMAIN (type
);
2474 tree element
= TREE_TYPE (type
);
2476 /* We need to know both bounds in order to compute the size. */
2477 if (index
&& TYPE_MAX_VALUE (index
) && TYPE_MIN_VALUE (index
)
2478 && TYPE_SIZE (element
))
2480 tree ub
= TYPE_MAX_VALUE (index
);
2481 tree lb
= TYPE_MIN_VALUE (index
);
2482 tree element_size
= TYPE_SIZE (element
);
2485 /* Make sure that an array of zero-sized element is zero-sized
2486 regardless of its extent. */
2487 if (integer_zerop (element_size
))
2488 length
= size_zero_node
;
2490 /* The computation should happen in the original signedness so
2491 that (possible) negative values are handled appropriately
2492 when determining overflow. */
2495 /* ??? When it is obvious that the range is signed
2496 represent it using ssizetype. */
2497 if (TREE_CODE (lb
) == INTEGER_CST
2498 && TREE_CODE (ub
) == INTEGER_CST
2499 && TYPE_UNSIGNED (TREE_TYPE (lb
))
2500 && tree_int_cst_lt (ub
, lb
))
2502 lb
= wide_int_to_tree (ssizetype
,
2503 offset_int::from (wi::to_wide (lb
),
2505 ub
= wide_int_to_tree (ssizetype
,
2506 offset_int::from (wi::to_wide (ub
),
2510 = fold_convert (sizetype
,
2511 size_binop (PLUS_EXPR
,
2512 build_int_cst (TREE_TYPE (lb
), 1),
2513 size_binop (MINUS_EXPR
, ub
, lb
)));
2516 /* ??? We have no way to distinguish a null-sized array from an
2517 array spanning the whole sizetype range, so we arbitrarily
2518 decide that [0, -1] is the only valid representation. */
2519 if (integer_zerop (length
)
2520 && TREE_OVERFLOW (length
)
2521 && integer_zerop (lb
))
2522 length
= size_zero_node
;
2524 TYPE_SIZE (type
) = size_binop (MULT_EXPR
, element_size
,
2525 bits_from_bytes (length
));
2527 /* If we know the size of the element, calculate the total size
2528 directly, rather than do some division thing below. This
2529 optimization helps Fortran assumed-size arrays (where the
2530 size of the array is determined at runtime) substantially. */
2531 if (TYPE_SIZE_UNIT (element
))
2532 TYPE_SIZE_UNIT (type
)
2533 = size_binop (MULT_EXPR
, TYPE_SIZE_UNIT (element
), length
);
2536 /* Now round the alignment and size,
2537 using machine-dependent criteria if any. */
2539 unsigned align
= TYPE_ALIGN (element
);
2540 if (TYPE_USER_ALIGN (type
))
2541 align
= MAX (align
, TYPE_ALIGN (type
));
2543 TYPE_USER_ALIGN (type
) = TYPE_USER_ALIGN (element
);
2544 if (!TYPE_WARN_IF_NOT_ALIGN (type
))
2545 SET_TYPE_WARN_IF_NOT_ALIGN (type
,
2546 TYPE_WARN_IF_NOT_ALIGN (element
));
2547 #ifdef ROUND_TYPE_ALIGN
2548 align
= ROUND_TYPE_ALIGN (type
, align
, BITS_PER_UNIT
);
2550 align
= MAX (align
, BITS_PER_UNIT
);
2552 SET_TYPE_ALIGN (type
, align
);
2553 SET_TYPE_MODE (type
, BLKmode
);
2554 if (TYPE_SIZE (type
) != 0
2555 && ! targetm
.member_type_forces_blk (type
, VOIDmode
)
2556 /* BLKmode elements force BLKmode aggregate;
2557 else extract/store fields may lose. */
2558 && (TYPE_MODE (TREE_TYPE (type
)) != BLKmode
2559 || TYPE_NO_FORCE_BLK (TREE_TYPE (type
))))
2561 SET_TYPE_MODE (type
, mode_for_array (TREE_TYPE (type
),
2563 if (TYPE_MODE (type
) != BLKmode
2564 && STRICT_ALIGNMENT
&& TYPE_ALIGN (type
) < BIGGEST_ALIGNMENT
2565 && TYPE_ALIGN (type
) < GET_MODE_ALIGNMENT (TYPE_MODE (type
)))
2567 TYPE_NO_FORCE_BLK (type
) = 1;
2568 SET_TYPE_MODE (type
, BLKmode
);
2571 if (AGGREGATE_TYPE_P (element
))
2572 TYPE_TYPELESS_STORAGE (type
) = TYPE_TYPELESS_STORAGE (element
);
2573 /* When the element size is constant, check that it is at least as
2574 large as the element alignment. */
2575 if (TYPE_SIZE_UNIT (element
)
2576 && TREE_CODE (TYPE_SIZE_UNIT (element
)) == INTEGER_CST
2577 /* If TYPE_SIZE_UNIT overflowed, then it is certainly larger than
2579 && !TREE_OVERFLOW (TYPE_SIZE_UNIT (element
))
2580 && !integer_zerop (TYPE_SIZE_UNIT (element
))
2581 && compare_tree_int (TYPE_SIZE_UNIT (element
),
2582 TYPE_ALIGN_UNIT (element
)) < 0)
2583 error ("alignment of array elements is greater than element size");
2589 case QUAL_UNION_TYPE
:
2592 record_layout_info rli
;
2594 /* Initialize the layout information. */
2595 rli
= start_record_layout (type
);
2597 /* If this is a QUAL_UNION_TYPE, we want to process the fields
2598 in the reverse order in building the COND_EXPR that denotes
2599 its size. We reverse them again later. */
2600 if (TREE_CODE (type
) == QUAL_UNION_TYPE
)
2601 TYPE_FIELDS (type
) = nreverse (TYPE_FIELDS (type
));
2603 /* Place all the fields. */
2604 for (field
= TYPE_FIELDS (type
); field
; field
= DECL_CHAIN (field
))
2605 place_field (rli
, field
);
2607 if (TREE_CODE (type
) == QUAL_UNION_TYPE
)
2608 TYPE_FIELDS (type
) = nreverse (TYPE_FIELDS (type
));
2610 /* Finish laying out the record. */
2611 finish_record_layout (rli
, /*free_p=*/true);
2619 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
2620 records and unions, finish_record_layout already called this
2622 if (!RECORD_OR_UNION_TYPE_P (type
))
2623 finalize_type_size (type
);
2625 /* We should never see alias sets on incomplete aggregates. And we
2626 should not call layout_type on not incomplete aggregates. */
2627 if (AGGREGATE_TYPE_P (type
))
2628 gcc_assert (!TYPE_ALIAS_SET_KNOWN_P (type
));
2631 /* Return the least alignment required for type TYPE. */
2634 min_align_of_type (tree type
)
2636 unsigned int align
= TYPE_ALIGN (type
);
2637 if (!TYPE_USER_ALIGN (type
))
2639 align
= MIN (align
, BIGGEST_ALIGNMENT
);
2640 #ifdef BIGGEST_FIELD_ALIGNMENT
2641 align
= MIN (align
, BIGGEST_FIELD_ALIGNMENT
);
2643 unsigned int field_align
= align
;
2644 #ifdef ADJUST_FIELD_ALIGN
2645 field_align
= ADJUST_FIELD_ALIGN (NULL_TREE
, type
, field_align
);
2647 align
= MIN (align
, field_align
);
2649 return align
/ BITS_PER_UNIT
;
2652 /* Create and return a type for signed integers of PRECISION bits. */
2655 make_signed_type (int precision
)
2657 tree type
= make_node (INTEGER_TYPE
);
2659 TYPE_PRECISION (type
) = precision
;
2661 fixup_signed_type (type
);
2665 /* Create and return a type for unsigned integers of PRECISION bits. */
2668 make_unsigned_type (int precision
)
2670 tree type
= make_node (INTEGER_TYPE
);
2672 TYPE_PRECISION (type
) = precision
;
2674 fixup_unsigned_type (type
);
2678 /* Create and return a type for fract of PRECISION bits, UNSIGNEDP,
2682 make_fract_type (int precision
, int unsignedp
, int satp
)
2684 tree type
= make_node (FIXED_POINT_TYPE
);
2686 TYPE_PRECISION (type
) = precision
;
2689 TYPE_SATURATING (type
) = 1;
2691 /* Lay out the type: set its alignment, size, etc. */
2692 TYPE_UNSIGNED (type
) = unsignedp
;
2693 enum mode_class mclass
= unsignedp
? MODE_UFRACT
: MODE_FRACT
;
2694 SET_TYPE_MODE (type
, mode_for_size (precision
, mclass
, 0).require ());
2700 /* Create and return a type for accum of PRECISION bits, UNSIGNEDP,
2704 make_accum_type (int precision
, int unsignedp
, int satp
)
2706 tree type
= make_node (FIXED_POINT_TYPE
);
2708 TYPE_PRECISION (type
) = precision
;
2711 TYPE_SATURATING (type
) = 1;
2713 /* Lay out the type: set its alignment, size, etc. */
2714 TYPE_UNSIGNED (type
) = unsignedp
;
2715 enum mode_class mclass
= unsignedp
? MODE_UACCUM
: MODE_ACCUM
;
2716 SET_TYPE_MODE (type
, mode_for_size (precision
, mclass
, 0).require ());
2722 /* Initialize sizetypes so layout_type can use them. */
2725 initialize_sizetypes (void)
2727 int precision
, bprecision
;
2729 /* Get sizetypes precision from the SIZE_TYPE target macro. */
2730 if (strcmp (SIZETYPE
, "unsigned int") == 0)
2731 precision
= INT_TYPE_SIZE
;
2732 else if (strcmp (SIZETYPE
, "long unsigned int") == 0)
2733 precision
= LONG_TYPE_SIZE
;
2734 else if (strcmp (SIZETYPE
, "long long unsigned int") == 0)
2735 precision
= LONG_LONG_TYPE_SIZE
;
2736 else if (strcmp (SIZETYPE
, "short unsigned int") == 0)
2737 precision
= SHORT_TYPE_SIZE
;
2743 for (i
= 0; i
< NUM_INT_N_ENTS
; i
++)
2744 if (int_n_enabled_p
[i
])
2746 char name
[50], altname
[50];
2747 sprintf (name
, "__int%d unsigned", int_n_data
[i
].bitsize
);
2748 sprintf (altname
, "__int%d__ unsigned", int_n_data
[i
].bitsize
);
2750 if (strcmp (name
, SIZETYPE
) == 0
2751 || strcmp (altname
, SIZETYPE
) == 0)
2753 precision
= int_n_data
[i
].bitsize
;
2756 if (precision
== -1)
2761 = MIN (precision
+ LOG2_BITS_PER_UNIT
+ 1, MAX_FIXED_MODE_SIZE
);
2762 bprecision
= GET_MODE_PRECISION (smallest_int_mode_for_size (bprecision
));
2763 if (bprecision
> HOST_BITS_PER_DOUBLE_INT
)
2764 bprecision
= HOST_BITS_PER_DOUBLE_INT
;
2766 /* Create stubs for sizetype and bitsizetype so we can create constants. */
2767 sizetype
= make_node (INTEGER_TYPE
);
2768 TYPE_NAME (sizetype
) = get_identifier ("sizetype");
2769 TYPE_PRECISION (sizetype
) = precision
;
2770 TYPE_UNSIGNED (sizetype
) = 1;
2771 bitsizetype
= make_node (INTEGER_TYPE
);
2772 TYPE_NAME (bitsizetype
) = get_identifier ("bitsizetype");
2773 TYPE_PRECISION (bitsizetype
) = bprecision
;
2774 TYPE_UNSIGNED (bitsizetype
) = 1;
2776 /* Now layout both types manually. */
2777 scalar_int_mode mode
= smallest_int_mode_for_size (precision
);
2778 SET_TYPE_MODE (sizetype
, mode
);
2779 SET_TYPE_ALIGN (sizetype
, GET_MODE_ALIGNMENT (TYPE_MODE (sizetype
)));
2780 TYPE_SIZE (sizetype
) = bitsize_int (precision
);
2781 TYPE_SIZE_UNIT (sizetype
) = size_int (GET_MODE_SIZE (mode
));
2782 set_min_and_max_values_for_integral_type (sizetype
, precision
, UNSIGNED
);
2784 mode
= smallest_int_mode_for_size (bprecision
);
2785 SET_TYPE_MODE (bitsizetype
, mode
);
2786 SET_TYPE_ALIGN (bitsizetype
, GET_MODE_ALIGNMENT (TYPE_MODE (bitsizetype
)));
2787 TYPE_SIZE (bitsizetype
) = bitsize_int (bprecision
);
2788 TYPE_SIZE_UNIT (bitsizetype
) = size_int (GET_MODE_SIZE (mode
));
2789 set_min_and_max_values_for_integral_type (bitsizetype
, bprecision
, UNSIGNED
);
2791 /* Create the signed variants of *sizetype. */
2792 ssizetype
= make_signed_type (TYPE_PRECISION (sizetype
));
2793 TYPE_NAME (ssizetype
) = get_identifier ("ssizetype");
2794 sbitsizetype
= make_signed_type (TYPE_PRECISION (bitsizetype
));
2795 TYPE_NAME (sbitsizetype
) = get_identifier ("sbitsizetype");
2798 /* TYPE is an integral type, i.e., an INTEGRAL_TYPE, ENUMERAL_TYPE
2799 or BOOLEAN_TYPE. Set TYPE_MIN_VALUE and TYPE_MAX_VALUE
2800 for TYPE, based on the PRECISION and whether or not the TYPE
2801 IS_UNSIGNED. PRECISION need not correspond to a width supported
2802 natively by the hardware; for example, on a machine with 8-bit,
2803 16-bit, and 32-bit register modes, PRECISION might be 7, 23, or
2807 set_min_and_max_values_for_integral_type (tree type
,
2811 /* For bitfields with zero width we end up creating integer types
2812 with zero precision. Don't assign any minimum/maximum values
2813 to those types, they don't have any valid value. */
2817 TYPE_MIN_VALUE (type
)
2818 = wide_int_to_tree (type
, wi::min_value (precision
, sgn
));
2819 TYPE_MAX_VALUE (type
)
2820 = wide_int_to_tree (type
, wi::max_value (precision
, sgn
));
2823 /* Set the extreme values of TYPE based on its precision in bits,
2824 then lay it out. Used when make_signed_type won't do
2825 because the tree code is not INTEGER_TYPE. */
2828 fixup_signed_type (tree type
)
2830 int precision
= TYPE_PRECISION (type
);
2832 set_min_and_max_values_for_integral_type (type
, precision
, SIGNED
);
2834 /* Lay out the type: set its alignment, size, etc. */
2838 /* Set the extreme values of TYPE based on its precision in bits,
2839 then lay it out. This is used both in `make_unsigned_type'
2840 and for enumeral types. */
2843 fixup_unsigned_type (tree type
)
2845 int precision
= TYPE_PRECISION (type
);
2847 TYPE_UNSIGNED (type
) = 1;
2849 set_min_and_max_values_for_integral_type (type
, precision
, UNSIGNED
);
2851 /* Lay out the type: set its alignment, size, etc. */
2855 /* Construct an iterator for a bitfield that spans BITSIZE bits,
2858 BITREGION_START is the bit position of the first bit in this
2859 sequence of bit fields. BITREGION_END is the last bit in this
2860 sequence. If these two fields are non-zero, we should restrict the
2861 memory access to that range. Otherwise, we are allowed to touch
2862 any adjacent non bit-fields.
2864 ALIGN is the alignment of the underlying object in bits.
2865 VOLATILEP says whether the bitfield is volatile. */
2867 bit_field_mode_iterator
2868 ::bit_field_mode_iterator (HOST_WIDE_INT bitsize
, HOST_WIDE_INT bitpos
,
2869 poly_int64 bitregion_start
,
2870 poly_int64 bitregion_end
,
2871 unsigned int align
, bool volatilep
)
2872 : m_mode (NARROWEST_INT_MODE
), m_bitsize (bitsize
),
2873 m_bitpos (bitpos
), m_bitregion_start (bitregion_start
),
2874 m_bitregion_end (bitregion_end
), m_align (align
),
2875 m_volatilep (volatilep
), m_count (0)
2877 if (known_eq (m_bitregion_end
, 0))
2879 /* We can assume that any aligned chunk of ALIGN bits that overlaps
2880 the bitfield is mapped and won't trap, provided that ALIGN isn't
2881 too large. The cap is the biggest required alignment for data,
2882 or at least the word size. And force one such chunk at least. */
2883 unsigned HOST_WIDE_INT units
2884 = MIN (align
, MAX (BIGGEST_ALIGNMENT
, BITS_PER_WORD
));
2887 HOST_WIDE_INT end
= bitpos
+ bitsize
+ units
- 1;
2888 m_bitregion_end
= end
- end
% units
- 1;
2892 /* Calls to this function return successively larger modes that can be used
2893 to represent the bitfield. Return true if another bitfield mode is
2894 available, storing it in *OUT_MODE if so. */
2897 bit_field_mode_iterator::next_mode (scalar_int_mode
*out_mode
)
2899 scalar_int_mode mode
;
2900 for (; m_mode
.exists (&mode
); m_mode
= GET_MODE_WIDER_MODE (mode
))
2902 unsigned int unit
= GET_MODE_BITSIZE (mode
);
2904 /* Skip modes that don't have full precision. */
2905 if (unit
!= GET_MODE_PRECISION (mode
))
2908 /* Stop if the mode is too wide to handle efficiently. */
2909 if (unit
> MAX_FIXED_MODE_SIZE
)
2912 /* Don't deliver more than one multiword mode; the smallest one
2914 if (m_count
> 0 && unit
> BITS_PER_WORD
)
2917 /* Skip modes that are too small. */
2918 unsigned HOST_WIDE_INT substart
= (unsigned HOST_WIDE_INT
) m_bitpos
% unit
;
2919 unsigned HOST_WIDE_INT subend
= substart
+ m_bitsize
;
2923 /* Stop if the mode goes outside the bitregion. */
2924 HOST_WIDE_INT start
= m_bitpos
- substart
;
2925 if (maybe_ne (m_bitregion_start
, 0)
2926 && maybe_lt (start
, m_bitregion_start
))
2928 HOST_WIDE_INT end
= start
+ unit
;
2929 if (maybe_gt (end
, m_bitregion_end
+ 1))
2932 /* Stop if the mode requires too much alignment. */
2933 if (GET_MODE_ALIGNMENT (mode
) > m_align
2934 && targetm
.slow_unaligned_access (mode
, m_align
))
2938 m_mode
= GET_MODE_WIDER_MODE (mode
);
2945 /* Return true if smaller modes are generally preferred for this kind
2949 bit_field_mode_iterator::prefer_smaller_modes ()
2952 ? targetm
.narrow_volatile_bitfield ()
2953 : !SLOW_BYTE_ACCESS
);
2956 /* Find the best machine mode to use when referencing a bit field of length
2957 BITSIZE bits starting at BITPOS.
2959 BITREGION_START is the bit position of the first bit in this
2960 sequence of bit fields. BITREGION_END is the last bit in this
2961 sequence. If these two fields are non-zero, we should restrict the
2962 memory access to that range. Otherwise, we are allowed to touch
2963 any adjacent non bit-fields.
2965 The chosen mode must have no more than LARGEST_MODE_BITSIZE bits.
2966 INT_MAX is a suitable value for LARGEST_MODE_BITSIZE if the caller
2967 doesn't want to apply a specific limit.
2969 If no mode meets all these conditions, we return VOIDmode.
2971 The underlying object is known to be aligned to a boundary of ALIGN bits.
2973 If VOLATILEP is false and SLOW_BYTE_ACCESS is false, we return the
2974 smallest mode meeting these conditions.
2976 If VOLATILEP is false and SLOW_BYTE_ACCESS is true, we return the
2977 largest mode (but a mode no wider than UNITS_PER_WORD) that meets
2980 If VOLATILEP is true the narrow_volatile_bitfields target hook is used to
2981 decide which of the above modes should be used. */
2984 get_best_mode (int bitsize
, int bitpos
,
2985 poly_uint64 bitregion_start
, poly_uint64 bitregion_end
,
2987 unsigned HOST_WIDE_INT largest_mode_bitsize
, bool volatilep
,
2988 scalar_int_mode
*best_mode
)
2990 bit_field_mode_iterator
iter (bitsize
, bitpos
, bitregion_start
,
2991 bitregion_end
, align
, volatilep
);
2992 scalar_int_mode mode
;
2994 while (iter
.next_mode (&mode
)
2995 /* ??? For historical reasons, reject modes that would normally
2996 receive greater alignment, even if unaligned accesses are
2997 acceptable. This has both advantages and disadvantages.
2998 Removing this check means that something like:
3000 struct s { unsigned int x; unsigned int y; };
3001 int f (struct s *s) { return s->x == 0 && s->y == 0; }
3003 can be implemented using a single load and compare on
3004 64-bit machines that have no alignment restrictions.
3005 For example, on powerpc64-linux-gnu, we would generate:
3027 However, accessing more than one field can make life harder
3028 for the gimple optimizers. For example, gcc.dg/vect/bb-slp-5.c
3029 has a series of unsigned short copies followed by a series of
3030 unsigned short comparisons. With this check, both the copies
3031 and comparisons remain 16-bit accesses and FRE is able
3032 to eliminate the latter. Without the check, the comparisons
3033 can be done using 2 64-bit operations, which FRE isn't able
3034 to handle in the same way.
3036 Either way, it would probably be worth disabling this check
3037 during expand. One particular example where removing the
3038 check would help is the get_best_mode call in store_bit_field.
3039 If we are given a memory bitregion of 128 bits that is aligned
3040 to a 64-bit boundary, and the bitfield we want to modify is
3041 in the second half of the bitregion, this check causes
3042 store_bitfield to turn the memory into a 64-bit reference
3043 to the _first_ half of the region. We later use
3044 adjust_bitfield_address to get a reference to the correct half,
3045 but doing so looks to adjust_bitfield_address as though we are
3046 moving past the end of the original object, so it drops the
3047 associated MEM_EXPR and MEM_OFFSET. Removing the check
3048 causes store_bit_field to keep a 128-bit memory reference,
3049 so that the final bitfield reference still has a MEM_EXPR
3051 && GET_MODE_ALIGNMENT (mode
) <= align
3052 && GET_MODE_BITSIZE (mode
) <= largest_mode_bitsize
)
3056 if (iter
.prefer_smaller_modes ())
3063 /* Gets minimal and maximal values for MODE (signed or unsigned depending on
3064 SIGN). The returned constants are made to be usable in TARGET_MODE. */
3067 get_mode_bounds (scalar_int_mode mode
, int sign
,
3068 scalar_int_mode target_mode
,
3069 rtx
*mmin
, rtx
*mmax
)
3071 unsigned size
= GET_MODE_PRECISION (mode
);
3072 unsigned HOST_WIDE_INT min_val
, max_val
;
3074 gcc_assert (size
<= HOST_BITS_PER_WIDE_INT
);
3076 /* Special case BImode, which has values 0 and STORE_FLAG_VALUE. */
3079 if (STORE_FLAG_VALUE
< 0)
3081 min_val
= STORE_FLAG_VALUE
;
3087 max_val
= STORE_FLAG_VALUE
;
3092 min_val
= -(HOST_WIDE_INT_1U
<< (size
- 1));
3093 max_val
= (HOST_WIDE_INT_1U
<< (size
- 1)) - 1;
3098 max_val
= (HOST_WIDE_INT_1U
<< (size
- 1) << 1) - 1;
3101 *mmin
= gen_int_mode (min_val
, target_mode
);
3102 *mmax
= gen_int_mode (max_val
, target_mode
);
3105 #include "gt-stor-layout.h"