1 /* C-compiler utilities for types and variables storage layout
2 Copyright (C) 1987-2015 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"
28 #include "double-int.h"
35 #include "fold-const.h"
36 #include "stor-layout.h"
37 #include "stringpool.h"
39 #include "print-tree.h"
43 #include "hard-reg-set.h"
46 #include "statistics.h"
48 #include "fixed-value.h"
49 #include "insn-config.h"
57 #include "diagnostic-core.h"
59 #include "langhooks.h"
64 #include "plugin-api.h"
67 #include "tree-inline.h"
68 #include "tree-dump.h"
71 /* Data type for the expressions representing sizes of data types.
72 It is the first integer type laid out. */
73 tree sizetype_tab
[(int) stk_type_kind_last
];
75 /* If nonzero, this is an upper limit on alignment of structure fields.
76 The value is measured in bits. */
77 unsigned int maximum_field_alignment
= TARGET_DEFAULT_PACK_STRUCT
* BITS_PER_UNIT
;
79 /* Nonzero if all REFERENCE_TYPEs are internal and hence should be allocated
80 in the address spaces' address_mode, not pointer_mode. Set only by
81 internal_reference_types called only by a front end. */
82 static int reference_types_internal
= 0;
84 static tree
self_referential_size (tree
);
85 static void finalize_record_size (record_layout_info
);
86 static void finalize_type_size (tree
);
87 static void place_union_field (record_layout_info
, tree
);
88 static int excess_unit_span (HOST_WIDE_INT
, HOST_WIDE_INT
, HOST_WIDE_INT
,
90 extern void debug_rli (record_layout_info
);
92 /* Show that REFERENCE_TYPES are internal and should use address_mode.
93 Called only by front end. */
96 internal_reference_types (void)
98 reference_types_internal
= 1;
101 /* Given a size SIZE that may not be a constant, return a SAVE_EXPR
102 to serve as the actual size-expression for a type or decl. */
105 variable_size (tree size
)
108 if (TREE_CONSTANT (size
))
111 /* If the size is self-referential, we can't make a SAVE_EXPR (see
112 save_expr for the rationale). But we can do something else. */
113 if (CONTAINS_PLACEHOLDER_P (size
))
114 return self_referential_size (size
);
116 /* If we are in the global binding level, we can't make a SAVE_EXPR
117 since it may end up being shared across functions, so it is up
118 to the front-end to deal with this case. */
119 if (lang_hooks
.decls
.global_bindings_p ())
122 return save_expr (size
);
125 /* An array of functions used for self-referential size computation. */
126 static GTY(()) vec
<tree
, va_gc
> *size_functions
;
128 /* Return true if T is a self-referential component reference. */
131 self_referential_component_ref_p (tree t
)
133 if (TREE_CODE (t
) != COMPONENT_REF
)
136 while (REFERENCE_CLASS_P (t
))
137 t
= TREE_OPERAND (t
, 0);
139 return (TREE_CODE (t
) == PLACEHOLDER_EXPR
);
142 /* Similar to copy_tree_r but do not copy component references involving
143 PLACEHOLDER_EXPRs. These nodes are spotted in find_placeholder_in_expr
144 and substituted in substitute_in_expr. */
147 copy_self_referential_tree_r (tree
*tp
, int *walk_subtrees
, void *data
)
149 enum tree_code code
= TREE_CODE (*tp
);
151 /* Stop at types, decls, constants like copy_tree_r. */
152 if (TREE_CODE_CLASS (code
) == tcc_type
153 || TREE_CODE_CLASS (code
) == tcc_declaration
154 || TREE_CODE_CLASS (code
) == tcc_constant
)
160 /* This is the pattern built in ada/make_aligning_type. */
161 else if (code
== ADDR_EXPR
162 && TREE_CODE (TREE_OPERAND (*tp
, 0)) == PLACEHOLDER_EXPR
)
168 /* Default case: the component reference. */
169 else if (self_referential_component_ref_p (*tp
))
175 /* We're not supposed to have them in self-referential size trees
176 because we wouldn't properly control when they are evaluated.
177 However, not creating superfluous SAVE_EXPRs requires accurate
178 tracking of readonly-ness all the way down to here, which we
179 cannot always guarantee in practice. So punt in this case. */
180 else if (code
== SAVE_EXPR
)
181 return error_mark_node
;
183 else if (code
== STATEMENT_LIST
)
186 return copy_tree_r (tp
, walk_subtrees
, data
);
189 /* Given a SIZE expression that is self-referential, return an equivalent
190 expression to serve as the actual size expression for a type. */
193 self_referential_size (tree size
)
195 static unsigned HOST_WIDE_INT fnno
= 0;
196 vec
<tree
> self_refs
= vNULL
;
197 tree param_type_list
= NULL
, param_decl_list
= NULL
;
198 tree t
, ref
, return_type
, fntype
, fnname
, fndecl
;
201 vec
<tree
, va_gc
> *args
= NULL
;
203 /* Do not factor out simple operations. */
204 t
= skip_simple_constant_arithmetic (size
);
205 if (TREE_CODE (t
) == CALL_EXPR
|| self_referential_component_ref_p (t
))
208 /* Collect the list of self-references in the expression. */
209 find_placeholder_in_expr (size
, &self_refs
);
210 gcc_assert (self_refs
.length () > 0);
212 /* Obtain a private copy of the expression. */
214 if (walk_tree (&t
, copy_self_referential_tree_r
, NULL
, NULL
) != NULL_TREE
)
218 /* Build the parameter and argument lists in parallel; also
219 substitute the former for the latter in the expression. */
220 vec_alloc (args
, self_refs
.length ());
221 FOR_EACH_VEC_ELT (self_refs
, i
, ref
)
223 tree subst
, param_name
, param_type
, param_decl
;
227 /* We shouldn't have true variables here. */
228 gcc_assert (TREE_READONLY (ref
));
231 /* This is the pattern built in ada/make_aligning_type. */
232 else if (TREE_CODE (ref
) == ADDR_EXPR
)
234 /* Default case: the component reference. */
236 subst
= TREE_OPERAND (ref
, 1);
238 sprintf (buf
, "p%d", i
);
239 param_name
= get_identifier (buf
);
240 param_type
= TREE_TYPE (ref
);
242 = build_decl (input_location
, PARM_DECL
, param_name
, param_type
);
243 DECL_ARG_TYPE (param_decl
) = param_type
;
244 DECL_ARTIFICIAL (param_decl
) = 1;
245 TREE_READONLY (param_decl
) = 1;
247 size
= substitute_in_expr (size
, subst
, param_decl
);
249 param_type_list
= tree_cons (NULL_TREE
, param_type
, param_type_list
);
250 param_decl_list
= chainon (param_decl
, param_decl_list
);
251 args
->quick_push (ref
);
254 self_refs
.release ();
256 /* Append 'void' to indicate that the number of parameters is fixed. */
257 param_type_list
= tree_cons (NULL_TREE
, void_type_node
, param_type_list
);
259 /* The 3 lists have been created in reverse order. */
260 param_type_list
= nreverse (param_type_list
);
261 param_decl_list
= nreverse (param_decl_list
);
263 /* Build the function type. */
264 return_type
= TREE_TYPE (size
);
265 fntype
= build_function_type (return_type
, param_type_list
);
267 /* Build the function declaration. */
268 sprintf (buf
, "SZ" HOST_WIDE_INT_PRINT_UNSIGNED
, fnno
++);
269 fnname
= get_file_function_name (buf
);
270 fndecl
= build_decl (input_location
, FUNCTION_DECL
, fnname
, fntype
);
271 for (t
= param_decl_list
; t
; t
= DECL_CHAIN (t
))
272 DECL_CONTEXT (t
) = fndecl
;
273 DECL_ARGUMENTS (fndecl
) = param_decl_list
;
275 = build_decl (input_location
, RESULT_DECL
, 0, return_type
);
276 DECL_CONTEXT (DECL_RESULT (fndecl
)) = fndecl
;
278 /* The function has been created by the compiler and we don't
279 want to emit debug info for it. */
280 DECL_ARTIFICIAL (fndecl
) = 1;
281 DECL_IGNORED_P (fndecl
) = 1;
283 /* It is supposed to be "const" and never throw. */
284 TREE_READONLY (fndecl
) = 1;
285 TREE_NOTHROW (fndecl
) = 1;
287 /* We want it to be inlined when this is deemed profitable, as
288 well as discarded if every call has been integrated. */
289 DECL_DECLARED_INLINE_P (fndecl
) = 1;
291 /* It is made up of a unique return statement. */
292 DECL_INITIAL (fndecl
) = make_node (BLOCK
);
293 BLOCK_SUPERCONTEXT (DECL_INITIAL (fndecl
)) = fndecl
;
294 t
= build2 (MODIFY_EXPR
, return_type
, DECL_RESULT (fndecl
), size
);
295 DECL_SAVED_TREE (fndecl
) = build1 (RETURN_EXPR
, void_type_node
, t
);
296 TREE_STATIC (fndecl
) = 1;
298 /* Put it onto the list of size functions. */
299 vec_safe_push (size_functions
, fndecl
);
301 /* Replace the original expression with a call to the size function. */
302 return build_call_expr_loc_vec (UNKNOWN_LOCATION
, fndecl
, args
);
305 /* Take, queue and compile all the size functions. It is essential that
306 the size functions be gimplified at the very end of the compilation
307 in order to guarantee transparent handling of self-referential sizes.
308 Otherwise the GENERIC inliner would not be able to inline them back
309 at each of their call sites, thus creating artificial non-constant
310 size expressions which would trigger nasty problems later on. */
313 finalize_size_functions (void)
318 for (i
= 0; size_functions
&& size_functions
->iterate (i
, &fndecl
); i
++)
320 allocate_struct_function (fndecl
, false);
322 dump_function (TDI_original
, fndecl
);
323 gimplify_function_tree (fndecl
);
324 dump_function (TDI_generic
, fndecl
);
325 cgraph_node::finalize_function (fndecl
, false);
328 vec_free (size_functions
);
331 /* Return the machine mode to use for a nonscalar of SIZE bits. The
332 mode must be in class MCLASS, and have exactly that many value bits;
333 it may have padding as well. If LIMIT is nonzero, modes of wider
334 than MAX_FIXED_MODE_SIZE will not be used. */
337 mode_for_size (unsigned int size
, enum mode_class mclass
, int limit
)
342 if (limit
&& size
> MAX_FIXED_MODE_SIZE
)
345 /* Get the first mode which has this size, in the specified class. */
346 for (mode
= GET_CLASS_NARROWEST_MODE (mclass
); mode
!= VOIDmode
;
347 mode
= GET_MODE_WIDER_MODE (mode
))
348 if (GET_MODE_PRECISION (mode
) == size
)
351 if (mclass
== MODE_INT
|| mclass
== MODE_PARTIAL_INT
)
352 for (i
= 0; i
< NUM_INT_N_ENTS
; i
++)
353 if (int_n_data
[i
].bitsize
== size
354 && int_n_enabled_p
[i
])
355 return int_n_data
[i
].m
;
360 /* Similar, except passed a tree node. */
363 mode_for_size_tree (const_tree size
, enum mode_class mclass
, int limit
)
365 unsigned HOST_WIDE_INT uhwi
;
368 if (!tree_fits_uhwi_p (size
))
370 uhwi
= tree_to_uhwi (size
);
374 return mode_for_size (ui
, mclass
, limit
);
377 /* Similar, but never return BLKmode; return the narrowest mode that
378 contains at least the requested number of value bits. */
381 smallest_mode_for_size (unsigned int size
, enum mode_class mclass
)
383 machine_mode mode
= VOIDmode
;
386 /* Get the first mode which has at least this size, in the
388 for (mode
= GET_CLASS_NARROWEST_MODE (mclass
); mode
!= VOIDmode
;
389 mode
= GET_MODE_WIDER_MODE (mode
))
390 if (GET_MODE_PRECISION (mode
) >= size
)
393 if (mclass
== MODE_INT
|| mclass
== MODE_PARTIAL_INT
)
394 for (i
= 0; i
< NUM_INT_N_ENTS
; i
++)
395 if (int_n_data
[i
].bitsize
>= size
396 && int_n_data
[i
].bitsize
< GET_MODE_PRECISION (mode
)
397 && int_n_enabled_p
[i
])
398 mode
= int_n_data
[i
].m
;
400 if (mode
== VOIDmode
)
406 /* Find an integer mode of the exact same size, or BLKmode on failure. */
409 int_mode_for_mode (machine_mode mode
)
411 switch (GET_MODE_CLASS (mode
))
414 case MODE_PARTIAL_INT
:
417 case MODE_COMPLEX_INT
:
418 case MODE_COMPLEX_FLOAT
:
420 case MODE_DECIMAL_FLOAT
:
421 case MODE_VECTOR_INT
:
422 case MODE_VECTOR_FLOAT
:
427 case MODE_VECTOR_FRACT
:
428 case MODE_VECTOR_ACCUM
:
429 case MODE_VECTOR_UFRACT
:
430 case MODE_VECTOR_UACCUM
:
431 case MODE_POINTER_BOUNDS
:
432 mode
= mode_for_size (GET_MODE_BITSIZE (mode
), MODE_INT
, 0);
439 /* ... fall through ... */
449 /* Find a mode that can be used for efficient bitwise operations on MODE.
450 Return BLKmode if no such mode exists. */
453 bitwise_mode_for_mode (machine_mode mode
)
455 /* Quick exit if we already have a suitable mode. */
456 unsigned int bitsize
= GET_MODE_BITSIZE (mode
);
457 if (SCALAR_INT_MODE_P (mode
) && bitsize
<= MAX_FIXED_MODE_SIZE
)
460 /* Reuse the sanity checks from int_mode_for_mode. */
461 gcc_checking_assert ((int_mode_for_mode (mode
), true));
463 /* Try to replace complex modes with complex modes. In general we
464 expect both components to be processed independently, so we only
465 care whether there is a register for the inner mode. */
466 if (COMPLEX_MODE_P (mode
))
468 machine_mode trial
= mode
;
469 if (GET_MODE_CLASS (mode
) != MODE_COMPLEX_INT
)
470 trial
= mode_for_size (bitsize
, MODE_COMPLEX_INT
, false);
472 && have_regs_of_mode
[GET_MODE_INNER (trial
)])
476 /* Try to replace vector modes with vector modes. Also try using vector
477 modes if an integer mode would be too big. */
478 if (VECTOR_MODE_P (mode
) || bitsize
> MAX_FIXED_MODE_SIZE
)
480 machine_mode trial
= mode
;
481 if (GET_MODE_CLASS (mode
) != MODE_VECTOR_INT
)
482 trial
= mode_for_size (bitsize
, MODE_VECTOR_INT
, 0);
484 && have_regs_of_mode
[trial
]
485 && targetm
.vector_mode_supported_p (trial
))
489 /* Otherwise fall back on integers while honoring MAX_FIXED_MODE_SIZE. */
490 return mode_for_size (bitsize
, MODE_INT
, true);
493 /* Find a type that can be used for efficient bitwise operations on MODE.
494 Return null if no such mode exists. */
497 bitwise_type_for_mode (machine_mode mode
)
499 mode
= bitwise_mode_for_mode (mode
);
503 unsigned int inner_size
= GET_MODE_UNIT_BITSIZE (mode
);
504 tree inner_type
= build_nonstandard_integer_type (inner_size
, true);
506 if (VECTOR_MODE_P (mode
))
507 return build_vector_type_for_mode (inner_type
, mode
);
509 if (COMPLEX_MODE_P (mode
))
510 return build_complex_type (inner_type
);
512 gcc_checking_assert (GET_MODE_INNER (mode
) == VOIDmode
);
516 /* Find a mode that is suitable for representing a vector with
517 NUNITS elements of mode INNERMODE. Returns BLKmode if there
518 is no suitable mode. */
521 mode_for_vector (machine_mode innermode
, unsigned nunits
)
525 /* First, look for a supported vector type. */
526 if (SCALAR_FLOAT_MODE_P (innermode
))
527 mode
= MIN_MODE_VECTOR_FLOAT
;
528 else if (SCALAR_FRACT_MODE_P (innermode
))
529 mode
= MIN_MODE_VECTOR_FRACT
;
530 else if (SCALAR_UFRACT_MODE_P (innermode
))
531 mode
= MIN_MODE_VECTOR_UFRACT
;
532 else if (SCALAR_ACCUM_MODE_P (innermode
))
533 mode
= MIN_MODE_VECTOR_ACCUM
;
534 else if (SCALAR_UACCUM_MODE_P (innermode
))
535 mode
= MIN_MODE_VECTOR_UACCUM
;
537 mode
= MIN_MODE_VECTOR_INT
;
539 /* Do not check vector_mode_supported_p here. We'll do that
540 later in vector_type_mode. */
541 for (; mode
!= VOIDmode
; mode
= GET_MODE_WIDER_MODE (mode
))
542 if (GET_MODE_NUNITS (mode
) == nunits
543 && GET_MODE_INNER (mode
) == innermode
)
546 /* For integers, try mapping it to a same-sized scalar mode. */
548 && GET_MODE_CLASS (innermode
) == MODE_INT
)
549 mode
= mode_for_size (nunits
* GET_MODE_BITSIZE (innermode
),
553 || (GET_MODE_CLASS (mode
) == MODE_INT
554 && !have_regs_of_mode
[mode
]))
560 /* Return the alignment of MODE. This will be bounded by 1 and
561 BIGGEST_ALIGNMENT. */
564 get_mode_alignment (machine_mode mode
)
566 return MIN (BIGGEST_ALIGNMENT
, MAX (1, mode_base_align
[mode
]*BITS_PER_UNIT
));
569 /* Return the precision of the mode, or for a complex or vector mode the
570 precision of the mode of its elements. */
573 element_precision (machine_mode mode
)
575 if (COMPLEX_MODE_P (mode
) || VECTOR_MODE_P (mode
))
576 mode
= GET_MODE_INNER (mode
);
578 return GET_MODE_PRECISION (mode
);
581 /* Return the natural mode of an array, given that it is SIZE bytes in
582 total and has elements of type ELEM_TYPE. */
585 mode_for_array (tree elem_type
, tree size
)
588 unsigned HOST_WIDE_INT int_size
, int_elem_size
;
591 /* One-element arrays get the component type's mode. */
592 elem_size
= TYPE_SIZE (elem_type
);
593 if (simple_cst_equal (size
, elem_size
))
594 return TYPE_MODE (elem_type
);
597 if (tree_fits_uhwi_p (size
) && tree_fits_uhwi_p (elem_size
))
599 int_size
= tree_to_uhwi (size
);
600 int_elem_size
= tree_to_uhwi (elem_size
);
601 if (int_elem_size
> 0
602 && int_size
% int_elem_size
== 0
603 && targetm
.array_mode_supported_p (TYPE_MODE (elem_type
),
604 int_size
/ int_elem_size
))
607 return mode_for_size_tree (size
, MODE_INT
, limit_p
);
610 /* Subroutine of layout_decl: Force alignment required for the data type.
611 But if the decl itself wants greater alignment, don't override that. */
614 do_type_align (tree type
, tree decl
)
616 if (TYPE_ALIGN (type
) > DECL_ALIGN (decl
))
618 DECL_ALIGN (decl
) = TYPE_ALIGN (type
);
619 if (TREE_CODE (decl
) == FIELD_DECL
)
620 DECL_USER_ALIGN (decl
) = TYPE_USER_ALIGN (type
);
624 /* Set the size, mode and alignment of a ..._DECL node.
625 TYPE_DECL does need this for C++.
626 Note that LABEL_DECL and CONST_DECL nodes do not need this,
627 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
628 Don't call layout_decl for them.
630 KNOWN_ALIGN is the amount of alignment we can assume this
631 decl has with no special effort. It is relevant only for FIELD_DECLs
632 and depends on the previous fields.
633 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
634 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
635 the record will be aligned to suit. */
638 layout_decl (tree decl
, unsigned int known_align
)
640 tree type
= TREE_TYPE (decl
);
641 enum tree_code code
= TREE_CODE (decl
);
643 location_t loc
= DECL_SOURCE_LOCATION (decl
);
645 if (code
== CONST_DECL
)
648 gcc_assert (code
== VAR_DECL
|| code
== PARM_DECL
|| code
== RESULT_DECL
649 || code
== TYPE_DECL
||code
== FIELD_DECL
);
651 rtl
= DECL_RTL_IF_SET (decl
);
653 if (type
== error_mark_node
)
654 type
= void_type_node
;
656 /* Usually the size and mode come from the data type without change,
657 however, the front-end may set the explicit width of the field, so its
658 size may not be the same as the size of its type. This happens with
659 bitfields, of course (an `int' bitfield may be only 2 bits, say), but it
660 also happens with other fields. For example, the C++ front-end creates
661 zero-sized fields corresponding to empty base classes, and depends on
662 layout_type setting DECL_FIELD_BITPOS correctly for the field. Set the
663 size in bytes from the size in bits. If we have already set the mode,
664 don't set it again since we can be called twice for FIELD_DECLs. */
666 DECL_UNSIGNED (decl
) = TYPE_UNSIGNED (type
);
667 if (DECL_MODE (decl
) == VOIDmode
)
668 DECL_MODE (decl
) = TYPE_MODE (type
);
670 if (DECL_SIZE (decl
) == 0)
672 DECL_SIZE (decl
) = TYPE_SIZE (type
);
673 DECL_SIZE_UNIT (decl
) = TYPE_SIZE_UNIT (type
);
675 else if (DECL_SIZE_UNIT (decl
) == 0)
676 DECL_SIZE_UNIT (decl
)
677 = fold_convert_loc (loc
, sizetype
,
678 size_binop_loc (loc
, CEIL_DIV_EXPR
, DECL_SIZE (decl
),
681 if (code
!= FIELD_DECL
)
682 /* For non-fields, update the alignment from the type. */
683 do_type_align (type
, decl
);
685 /* For fields, it's a bit more complicated... */
687 bool old_user_align
= DECL_USER_ALIGN (decl
);
688 bool zero_bitfield
= false;
689 bool packed_p
= DECL_PACKED (decl
);
692 if (DECL_BIT_FIELD (decl
))
694 DECL_BIT_FIELD_TYPE (decl
) = type
;
696 /* A zero-length bit-field affects the alignment of the next
697 field. In essence such bit-fields are not influenced by
698 any packing due to #pragma pack or attribute packed. */
699 if (integer_zerop (DECL_SIZE (decl
))
700 && ! targetm
.ms_bitfield_layout_p (DECL_FIELD_CONTEXT (decl
)))
702 zero_bitfield
= true;
704 if (PCC_BITFIELD_TYPE_MATTERS
)
705 do_type_align (type
, decl
);
708 #ifdef EMPTY_FIELD_BOUNDARY
709 if (EMPTY_FIELD_BOUNDARY
> DECL_ALIGN (decl
))
711 DECL_ALIGN (decl
) = EMPTY_FIELD_BOUNDARY
;
712 DECL_USER_ALIGN (decl
) = 0;
718 /* See if we can use an ordinary integer mode for a bit-field.
719 Conditions are: a fixed size that is correct for another mode,
720 occupying a complete byte or bytes on proper boundary. */
721 if (TYPE_SIZE (type
) != 0
722 && TREE_CODE (TYPE_SIZE (type
)) == INTEGER_CST
723 && GET_MODE_CLASS (TYPE_MODE (type
)) == MODE_INT
)
726 = mode_for_size_tree (DECL_SIZE (decl
), MODE_INT
, 1);
727 unsigned int xalign
= GET_MODE_ALIGNMENT (xmode
);
730 && !(xalign
> BITS_PER_UNIT
&& DECL_PACKED (decl
))
731 && (known_align
== 0 || known_align
>= xalign
))
733 DECL_ALIGN (decl
) = MAX (xalign
, DECL_ALIGN (decl
));
734 DECL_MODE (decl
) = xmode
;
735 DECL_BIT_FIELD (decl
) = 0;
739 /* Turn off DECL_BIT_FIELD if we won't need it set. */
740 if (TYPE_MODE (type
) == BLKmode
&& DECL_MODE (decl
) == BLKmode
741 && known_align
>= TYPE_ALIGN (type
)
742 && DECL_ALIGN (decl
) >= TYPE_ALIGN (type
))
743 DECL_BIT_FIELD (decl
) = 0;
745 else if (packed_p
&& DECL_USER_ALIGN (decl
))
746 /* Don't touch DECL_ALIGN. For other packed fields, go ahead and
747 round up; we'll reduce it again below. We want packing to
748 supersede USER_ALIGN inherited from the type, but defer to
749 alignment explicitly specified on the field decl. */;
751 do_type_align (type
, decl
);
753 /* If the field is packed and not explicitly aligned, give it the
754 minimum alignment. Note that do_type_align may set
755 DECL_USER_ALIGN, so we need to check old_user_align instead. */
758 DECL_ALIGN (decl
) = MIN (DECL_ALIGN (decl
), BITS_PER_UNIT
);
760 if (! packed_p
&& ! DECL_USER_ALIGN (decl
))
762 /* Some targets (i.e. i386, VMS) limit struct field alignment
763 to a lower boundary than alignment of variables unless
764 it was overridden by attribute aligned. */
765 #ifdef BIGGEST_FIELD_ALIGNMENT
767 = MIN (DECL_ALIGN (decl
), (unsigned) BIGGEST_FIELD_ALIGNMENT
);
769 #ifdef ADJUST_FIELD_ALIGN
770 DECL_ALIGN (decl
) = ADJUST_FIELD_ALIGN (decl
, DECL_ALIGN (decl
));
775 mfa
= initial_max_fld_align
* BITS_PER_UNIT
;
777 mfa
= maximum_field_alignment
;
778 /* Should this be controlled by DECL_USER_ALIGN, too? */
780 DECL_ALIGN (decl
) = MIN (DECL_ALIGN (decl
), mfa
);
783 /* Evaluate nonconstant size only once, either now or as soon as safe. */
784 if (DECL_SIZE (decl
) != 0 && TREE_CODE (DECL_SIZE (decl
)) != INTEGER_CST
)
785 DECL_SIZE (decl
) = variable_size (DECL_SIZE (decl
));
786 if (DECL_SIZE_UNIT (decl
) != 0
787 && TREE_CODE (DECL_SIZE_UNIT (decl
)) != INTEGER_CST
)
788 DECL_SIZE_UNIT (decl
) = variable_size (DECL_SIZE_UNIT (decl
));
790 /* If requested, warn about definitions of large data objects. */
792 && (code
== VAR_DECL
|| code
== PARM_DECL
)
793 && ! DECL_EXTERNAL (decl
))
795 tree size
= DECL_SIZE_UNIT (decl
);
797 if (size
!= 0 && TREE_CODE (size
) == INTEGER_CST
798 && compare_tree_int (size
, larger_than_size
) > 0)
800 int size_as_int
= TREE_INT_CST_LOW (size
);
802 if (compare_tree_int (size
, size_as_int
) == 0)
803 warning (OPT_Wlarger_than_
, "size of %q+D is %d bytes", decl
, size_as_int
);
805 warning (OPT_Wlarger_than_
, "size of %q+D is larger than %wd bytes",
806 decl
, larger_than_size
);
810 /* If the RTL was already set, update its mode and mem attributes. */
813 PUT_MODE (rtl
, DECL_MODE (decl
));
814 SET_DECL_RTL (decl
, 0);
815 set_mem_attributes (rtl
, decl
, 1);
816 SET_DECL_RTL (decl
, rtl
);
820 /* Given a VAR_DECL, PARM_DECL or RESULT_DECL, clears the results of
821 a previous call to layout_decl and calls it again. */
824 relayout_decl (tree decl
)
826 DECL_SIZE (decl
) = DECL_SIZE_UNIT (decl
) = 0;
827 DECL_MODE (decl
) = VOIDmode
;
828 if (!DECL_USER_ALIGN (decl
))
829 DECL_ALIGN (decl
) = 0;
830 SET_DECL_RTL (decl
, 0);
832 layout_decl (decl
, 0);
835 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
836 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
837 is to be passed to all other layout functions for this record. It is the
838 responsibility of the caller to call `free' for the storage returned.
839 Note that garbage collection is not permitted until we finish laying
843 start_record_layout (tree t
)
845 record_layout_info rli
= XNEW (struct record_layout_info_s
);
849 /* If the type has a minimum specified alignment (via an attribute
850 declaration, for example) use it -- otherwise, start with a
851 one-byte alignment. */
852 rli
->record_align
= MAX (BITS_PER_UNIT
, TYPE_ALIGN (t
));
853 rli
->unpacked_align
= rli
->record_align
;
854 rli
->offset_align
= MAX (rli
->record_align
, BIGGEST_ALIGNMENT
);
856 #ifdef STRUCTURE_SIZE_BOUNDARY
857 /* Packed structures don't need to have minimum size. */
858 if (! TYPE_PACKED (t
))
862 /* #pragma pack overrides STRUCTURE_SIZE_BOUNDARY. */
863 tmp
= (unsigned) STRUCTURE_SIZE_BOUNDARY
;
864 if (maximum_field_alignment
!= 0)
865 tmp
= MIN (tmp
, maximum_field_alignment
);
866 rli
->record_align
= MAX (rli
->record_align
, tmp
);
870 rli
->offset
= size_zero_node
;
871 rli
->bitpos
= bitsize_zero_node
;
873 rli
->pending_statics
= 0;
874 rli
->packed_maybe_necessary
= 0;
875 rli
->remaining_in_alignment
= 0;
880 /* Return the combined bit position for the byte offset OFFSET and the
883 These functions operate on byte and bit positions present in FIELD_DECLs
884 and assume that these expressions result in no (intermediate) overflow.
885 This assumption is necessary to fold the expressions as much as possible,
886 so as to avoid creating artificially variable-sized types in languages
887 supporting variable-sized types like Ada. */
890 bit_from_pos (tree offset
, tree bitpos
)
892 if (TREE_CODE (offset
) == PLUS_EXPR
)
893 offset
= size_binop (PLUS_EXPR
,
894 fold_convert (bitsizetype
, TREE_OPERAND (offset
, 0)),
895 fold_convert (bitsizetype
, TREE_OPERAND (offset
, 1)));
897 offset
= fold_convert (bitsizetype
, offset
);
898 return size_binop (PLUS_EXPR
, bitpos
,
899 size_binop (MULT_EXPR
, offset
, bitsize_unit_node
));
902 /* Return the combined truncated byte position for the byte offset OFFSET and
903 the bit position BITPOS. */
906 byte_from_pos (tree offset
, tree bitpos
)
909 if (TREE_CODE (bitpos
) == MULT_EXPR
910 && tree_int_cst_equal (TREE_OPERAND (bitpos
, 1), bitsize_unit_node
))
911 bytepos
= TREE_OPERAND (bitpos
, 0);
913 bytepos
= size_binop (TRUNC_DIV_EXPR
, bitpos
, bitsize_unit_node
);
914 return size_binop (PLUS_EXPR
, offset
, fold_convert (sizetype
, bytepos
));
917 /* Split the bit position POS into a byte offset *POFFSET and a bit
918 position *PBITPOS with the byte offset aligned to OFF_ALIGN bits. */
921 pos_from_bit (tree
*poffset
, tree
*pbitpos
, unsigned int off_align
,
924 tree toff_align
= bitsize_int (off_align
);
925 if (TREE_CODE (pos
) == MULT_EXPR
926 && tree_int_cst_equal (TREE_OPERAND (pos
, 1), toff_align
))
928 *poffset
= size_binop (MULT_EXPR
,
929 fold_convert (sizetype
, TREE_OPERAND (pos
, 0)),
930 size_int (off_align
/ BITS_PER_UNIT
));
931 *pbitpos
= bitsize_zero_node
;
935 *poffset
= size_binop (MULT_EXPR
,
936 fold_convert (sizetype
,
937 size_binop (FLOOR_DIV_EXPR
, pos
,
939 size_int (off_align
/ BITS_PER_UNIT
));
940 *pbitpos
= size_binop (FLOOR_MOD_EXPR
, pos
, toff_align
);
944 /* Given a pointer to bit and byte offsets and an offset alignment,
945 normalize the offsets so they are within the alignment. */
948 normalize_offset (tree
*poffset
, tree
*pbitpos
, unsigned int off_align
)
950 /* If the bit position is now larger than it should be, adjust it
952 if (compare_tree_int (*pbitpos
, off_align
) >= 0)
955 pos_from_bit (&offset
, &bitpos
, off_align
, *pbitpos
);
956 *poffset
= size_binop (PLUS_EXPR
, *poffset
, offset
);
961 /* Print debugging information about the information in RLI. */
964 debug_rli (record_layout_info rli
)
966 print_node_brief (stderr
, "type", rli
->t
, 0);
967 print_node_brief (stderr
, "\noffset", rli
->offset
, 0);
968 print_node_brief (stderr
, " bitpos", rli
->bitpos
, 0);
970 fprintf (stderr
, "\naligns: rec = %u, unpack = %u, off = %u\n",
971 rli
->record_align
, rli
->unpacked_align
,
974 /* The ms_struct code is the only that uses this. */
975 if (targetm
.ms_bitfield_layout_p (rli
->t
))
976 fprintf (stderr
, "remaining in alignment = %u\n", rli
->remaining_in_alignment
);
978 if (rli
->packed_maybe_necessary
)
979 fprintf (stderr
, "packed may be necessary\n");
981 if (!vec_safe_is_empty (rli
->pending_statics
))
983 fprintf (stderr
, "pending statics:\n");
984 debug_vec_tree (rli
->pending_statics
);
988 /* Given an RLI with a possibly-incremented BITPOS, adjust OFFSET and
989 BITPOS if necessary to keep BITPOS below OFFSET_ALIGN. */
992 normalize_rli (record_layout_info rli
)
994 normalize_offset (&rli
->offset
, &rli
->bitpos
, rli
->offset_align
);
997 /* Returns the size in bytes allocated so far. */
1000 rli_size_unit_so_far (record_layout_info rli
)
1002 return byte_from_pos (rli
->offset
, rli
->bitpos
);
1005 /* Returns the size in bits allocated so far. */
1008 rli_size_so_far (record_layout_info rli
)
1010 return bit_from_pos (rli
->offset
, rli
->bitpos
);
1013 /* FIELD is about to be added to RLI->T. The alignment (in bits) of
1014 the next available location within the record is given by KNOWN_ALIGN.
1015 Update the variable alignment fields in RLI, and return the alignment
1016 to give the FIELD. */
1019 update_alignment_for_field (record_layout_info rli
, tree field
,
1020 unsigned int known_align
)
1022 /* The alignment required for FIELD. */
1023 unsigned int desired_align
;
1024 /* The type of this field. */
1025 tree type
= TREE_TYPE (field
);
1026 /* True if the field was explicitly aligned by the user. */
1030 /* Do not attempt to align an ERROR_MARK node */
1031 if (TREE_CODE (type
) == ERROR_MARK
)
1034 /* Lay out the field so we know what alignment it needs. */
1035 layout_decl (field
, known_align
);
1036 desired_align
= DECL_ALIGN (field
);
1037 user_align
= DECL_USER_ALIGN (field
);
1039 is_bitfield
= (type
!= error_mark_node
1040 && DECL_BIT_FIELD_TYPE (field
)
1041 && ! integer_zerop (TYPE_SIZE (type
)));
1043 /* Record must have at least as much alignment as any field.
1044 Otherwise, the alignment of the field within the record is
1046 if (targetm
.ms_bitfield_layout_p (rli
->t
))
1048 /* Here, the alignment of the underlying type of a bitfield can
1049 affect the alignment of a record; even a zero-sized field
1050 can do this. The alignment should be to the alignment of
1051 the type, except that for zero-size bitfields this only
1052 applies if there was an immediately prior, nonzero-size
1053 bitfield. (That's the way it is, experimentally.) */
1054 if ((!is_bitfield
&& !DECL_PACKED (field
))
1055 || ((DECL_SIZE (field
) == NULL_TREE
1056 || !integer_zerop (DECL_SIZE (field
)))
1057 ? !DECL_PACKED (field
)
1059 && DECL_BIT_FIELD_TYPE (rli
->prev_field
)
1060 && ! integer_zerop (DECL_SIZE (rli
->prev_field
)))))
1062 unsigned int type_align
= TYPE_ALIGN (type
);
1063 type_align
= MAX (type_align
, desired_align
);
1064 if (maximum_field_alignment
!= 0)
1065 type_align
= MIN (type_align
, maximum_field_alignment
);
1066 rli
->record_align
= MAX (rli
->record_align
, type_align
);
1067 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
1070 else if (is_bitfield
&& PCC_BITFIELD_TYPE_MATTERS
)
1072 /* Named bit-fields cause the entire structure to have the
1073 alignment implied by their type. Some targets also apply the same
1074 rules to unnamed bitfields. */
1075 if (DECL_NAME (field
) != 0
1076 || targetm
.align_anon_bitfield ())
1078 unsigned int type_align
= TYPE_ALIGN (type
);
1080 #ifdef ADJUST_FIELD_ALIGN
1081 if (! TYPE_USER_ALIGN (type
))
1082 type_align
= ADJUST_FIELD_ALIGN (field
, type_align
);
1085 /* Targets might chose to handle unnamed and hence possibly
1086 zero-width bitfield. Those are not influenced by #pragmas
1087 or packed attributes. */
1088 if (integer_zerop (DECL_SIZE (field
)))
1090 if (initial_max_fld_align
)
1091 type_align
= MIN (type_align
,
1092 initial_max_fld_align
* BITS_PER_UNIT
);
1094 else if (maximum_field_alignment
!= 0)
1095 type_align
= MIN (type_align
, maximum_field_alignment
);
1096 else if (DECL_PACKED (field
))
1097 type_align
= MIN (type_align
, BITS_PER_UNIT
);
1099 /* The alignment of the record is increased to the maximum
1100 of the current alignment, the alignment indicated on the
1101 field (i.e., the alignment specified by an __aligned__
1102 attribute), and the alignment indicated by the type of
1104 rli
->record_align
= MAX (rli
->record_align
, desired_align
);
1105 rli
->record_align
= MAX (rli
->record_align
, type_align
);
1108 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
1109 user_align
|= TYPE_USER_ALIGN (type
);
1114 rli
->record_align
= MAX (rli
->record_align
, desired_align
);
1115 rli
->unpacked_align
= MAX (rli
->unpacked_align
, TYPE_ALIGN (type
));
1118 TYPE_USER_ALIGN (rli
->t
) |= user_align
;
1120 return desired_align
;
1123 /* Called from place_field to handle unions. */
1126 place_union_field (record_layout_info rli
, tree field
)
1128 update_alignment_for_field (rli
, field
, /*known_align=*/0);
1130 DECL_FIELD_OFFSET (field
) = size_zero_node
;
1131 DECL_FIELD_BIT_OFFSET (field
) = bitsize_zero_node
;
1132 SET_DECL_OFFSET_ALIGN (field
, BIGGEST_ALIGNMENT
);
1134 /* If this is an ERROR_MARK return *after* having set the
1135 field at the start of the union. This helps when parsing
1137 if (TREE_CODE (TREE_TYPE (field
)) == ERROR_MARK
)
1140 /* We assume the union's size will be a multiple of a byte so we don't
1141 bother with BITPOS. */
1142 if (TREE_CODE (rli
->t
) == UNION_TYPE
)
1143 rli
->offset
= size_binop (MAX_EXPR
, rli
->offset
, DECL_SIZE_UNIT (field
));
1144 else if (TREE_CODE (rli
->t
) == QUAL_UNION_TYPE
)
1145 rli
->offset
= fold_build3 (COND_EXPR
, sizetype
, DECL_QUALIFIER (field
),
1146 DECL_SIZE_UNIT (field
), rli
->offset
);
1149 /* A bitfield of SIZE with a required access alignment of ALIGN is allocated
1150 at BYTE_OFFSET / BIT_OFFSET. Return nonzero if the field would span more
1151 units of alignment than the underlying TYPE. */
1153 excess_unit_span (HOST_WIDE_INT byte_offset
, HOST_WIDE_INT bit_offset
,
1154 HOST_WIDE_INT size
, HOST_WIDE_INT align
, tree type
)
1156 /* Note that the calculation of OFFSET might overflow; we calculate it so
1157 that we still get the right result as long as ALIGN is a power of two. */
1158 unsigned HOST_WIDE_INT offset
= byte_offset
* BITS_PER_UNIT
+ bit_offset
;
1160 offset
= offset
% align
;
1161 return ((offset
+ size
+ align
- 1) / align
1162 > tree_to_uhwi (TYPE_SIZE (type
)) / align
);
1165 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
1166 is a FIELD_DECL to be added after those fields already present in
1167 T. (FIELD is not actually added to the TYPE_FIELDS list here;
1168 callers that desire that behavior must manually perform that step.) */
1171 place_field (record_layout_info rli
, tree field
)
1173 /* The alignment required for FIELD. */
1174 unsigned int desired_align
;
1175 /* The alignment FIELD would have if we just dropped it into the
1176 record as it presently stands. */
1177 unsigned int known_align
;
1178 unsigned int actual_align
;
1179 /* The type of this field. */
1180 tree type
= TREE_TYPE (field
);
1182 gcc_assert (TREE_CODE (field
) != ERROR_MARK
);
1184 /* If FIELD is static, then treat it like a separate variable, not
1185 really like a structure field. If it is a FUNCTION_DECL, it's a
1186 method. In both cases, all we do is lay out the decl, and we do
1187 it *after* the record is laid out. */
1188 if (TREE_CODE (field
) == VAR_DECL
)
1190 vec_safe_push (rli
->pending_statics
, field
);
1194 /* Enumerators and enum types which are local to this class need not
1195 be laid out. Likewise for initialized constant fields. */
1196 else if (TREE_CODE (field
) != FIELD_DECL
)
1199 /* Unions are laid out very differently than records, so split
1200 that code off to another function. */
1201 else if (TREE_CODE (rli
->t
) != RECORD_TYPE
)
1203 place_union_field (rli
, field
);
1207 else if (TREE_CODE (type
) == ERROR_MARK
)
1209 /* Place this field at the current allocation position, so we
1210 maintain monotonicity. */
1211 DECL_FIELD_OFFSET (field
) = rli
->offset
;
1212 DECL_FIELD_BIT_OFFSET (field
) = rli
->bitpos
;
1213 SET_DECL_OFFSET_ALIGN (field
, rli
->offset_align
);
1217 /* Work out the known alignment so far. Note that A & (-A) is the
1218 value of the least-significant bit in A that is one. */
1219 if (! integer_zerop (rli
->bitpos
))
1220 known_align
= (tree_to_uhwi (rli
->bitpos
)
1221 & - tree_to_uhwi (rli
->bitpos
));
1222 else if (integer_zerop (rli
->offset
))
1224 else if (tree_fits_uhwi_p (rli
->offset
))
1225 known_align
= (BITS_PER_UNIT
1226 * (tree_to_uhwi (rli
->offset
)
1227 & - tree_to_uhwi (rli
->offset
)));
1229 known_align
= rli
->offset_align
;
1231 desired_align
= update_alignment_for_field (rli
, field
, known_align
);
1232 if (known_align
== 0)
1233 known_align
= MAX (BIGGEST_ALIGNMENT
, rli
->record_align
);
1235 if (warn_packed
&& DECL_PACKED (field
))
1237 if (known_align
>= TYPE_ALIGN (type
))
1239 if (TYPE_ALIGN (type
) > desired_align
)
1241 if (STRICT_ALIGNMENT
)
1242 warning (OPT_Wattributes
, "packed attribute causes "
1243 "inefficient alignment for %q+D", field
);
1244 /* Don't warn if DECL_PACKED was set by the type. */
1245 else if (!TYPE_PACKED (rli
->t
))
1246 warning (OPT_Wattributes
, "packed attribute is "
1247 "unnecessary for %q+D", field
);
1251 rli
->packed_maybe_necessary
= 1;
1254 /* Does this field automatically have alignment it needs by virtue
1255 of the fields that precede it and the record's own alignment? */
1256 if (known_align
< desired_align
)
1258 /* No, we need to skip space before this field.
1259 Bump the cumulative size to multiple of field alignment. */
1261 if (!targetm
.ms_bitfield_layout_p (rli
->t
)
1262 && DECL_SOURCE_LOCATION (field
) != BUILTINS_LOCATION
)
1263 warning (OPT_Wpadded
, "padding struct to align %q+D", field
);
1265 /* If the alignment is still within offset_align, just align
1266 the bit position. */
1267 if (desired_align
< rli
->offset_align
)
1268 rli
->bitpos
= round_up (rli
->bitpos
, desired_align
);
1271 /* First adjust OFFSET by the partial bits, then align. */
1273 = size_binop (PLUS_EXPR
, rli
->offset
,
1274 fold_convert (sizetype
,
1275 size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
1276 bitsize_unit_node
)));
1277 rli
->bitpos
= bitsize_zero_node
;
1279 rli
->offset
= round_up (rli
->offset
, desired_align
/ BITS_PER_UNIT
);
1282 if (! TREE_CONSTANT (rli
->offset
))
1283 rli
->offset_align
= desired_align
;
1284 if (targetm
.ms_bitfield_layout_p (rli
->t
))
1285 rli
->prev_field
= NULL
;
1288 /* Handle compatibility with PCC. Note that if the record has any
1289 variable-sized fields, we need not worry about compatibility. */
1290 if (PCC_BITFIELD_TYPE_MATTERS
1291 && ! targetm
.ms_bitfield_layout_p (rli
->t
)
1292 && TREE_CODE (field
) == FIELD_DECL
1293 && type
!= error_mark_node
1294 && DECL_BIT_FIELD (field
)
1295 && (! DECL_PACKED (field
)
1296 /* Enter for these packed fields only to issue a warning. */
1297 || TYPE_ALIGN (type
) <= BITS_PER_UNIT
)
1298 && maximum_field_alignment
== 0
1299 && ! integer_zerop (DECL_SIZE (field
))
1300 && tree_fits_uhwi_p (DECL_SIZE (field
))
1301 && tree_fits_uhwi_p (rli
->offset
)
1302 && tree_fits_uhwi_p (TYPE_SIZE (type
)))
1304 unsigned int type_align
= TYPE_ALIGN (type
);
1305 tree dsize
= DECL_SIZE (field
);
1306 HOST_WIDE_INT field_size
= tree_to_uhwi (dsize
);
1307 HOST_WIDE_INT offset
= tree_to_uhwi (rli
->offset
);
1308 HOST_WIDE_INT bit_offset
= tree_to_shwi (rli
->bitpos
);
1310 #ifdef ADJUST_FIELD_ALIGN
1311 if (! TYPE_USER_ALIGN (type
))
1312 type_align
= ADJUST_FIELD_ALIGN (field
, type_align
);
1315 /* A bit field may not span more units of alignment of its type
1316 than its type itself. Advance to next boundary if necessary. */
1317 if (excess_unit_span (offset
, bit_offset
, field_size
, type_align
, type
))
1319 if (DECL_PACKED (field
))
1321 if (warn_packed_bitfield_compat
== 1)
1324 "offset of packed bit-field %qD has changed in GCC 4.4",
1328 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1331 if (! DECL_PACKED (field
))
1332 TYPE_USER_ALIGN (rli
->t
) |= TYPE_USER_ALIGN (type
);
1335 #ifdef BITFIELD_NBYTES_LIMITED
1336 if (BITFIELD_NBYTES_LIMITED
1337 && ! targetm
.ms_bitfield_layout_p (rli
->t
)
1338 && TREE_CODE (field
) == FIELD_DECL
1339 && type
!= error_mark_node
1340 && DECL_BIT_FIELD_TYPE (field
)
1341 && ! DECL_PACKED (field
)
1342 && ! integer_zerop (DECL_SIZE (field
))
1343 && tree_fits_uhwi_p (DECL_SIZE (field
))
1344 && tree_fits_uhwi_p (rli
->offset
)
1345 && tree_fits_uhwi_p (TYPE_SIZE (type
)))
1347 unsigned int type_align
= TYPE_ALIGN (type
);
1348 tree dsize
= DECL_SIZE (field
);
1349 HOST_WIDE_INT field_size
= tree_to_uhwi (dsize
);
1350 HOST_WIDE_INT offset
= tree_to_uhwi (rli
->offset
);
1351 HOST_WIDE_INT bit_offset
= tree_to_shwi (rli
->bitpos
);
1353 #ifdef ADJUST_FIELD_ALIGN
1354 if (! TYPE_USER_ALIGN (type
))
1355 type_align
= ADJUST_FIELD_ALIGN (field
, type_align
);
1358 if (maximum_field_alignment
!= 0)
1359 type_align
= MIN (type_align
, maximum_field_alignment
);
1360 /* ??? This test is opposite the test in the containing if
1361 statement, so this code is unreachable currently. */
1362 else if (DECL_PACKED (field
))
1363 type_align
= MIN (type_align
, BITS_PER_UNIT
);
1365 /* A bit field may not span the unit of alignment of its type.
1366 Advance to next boundary if necessary. */
1367 if (excess_unit_span (offset
, bit_offset
, field_size
, type_align
, type
))
1368 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1370 TYPE_USER_ALIGN (rli
->t
) |= TYPE_USER_ALIGN (type
);
1374 /* See the docs for TARGET_MS_BITFIELD_LAYOUT_P for details.
1376 When a bit field is inserted into a packed record, the whole
1377 size of the underlying type is used by one or more same-size
1378 adjacent bitfields. (That is, if its long:3, 32 bits is
1379 used in the record, and any additional adjacent long bitfields are
1380 packed into the same chunk of 32 bits. However, if the size
1381 changes, a new field of that size is allocated.) In an unpacked
1382 record, this is the same as using alignment, but not equivalent
1385 Note: for compatibility, we use the type size, not the type alignment
1386 to determine alignment, since that matches the documentation */
1388 if (targetm
.ms_bitfield_layout_p (rli
->t
))
1390 tree prev_saved
= rli
->prev_field
;
1391 tree prev_type
= prev_saved
? DECL_BIT_FIELD_TYPE (prev_saved
) : NULL
;
1393 /* This is a bitfield if it exists. */
1394 if (rli
->prev_field
)
1396 /* If both are bitfields, nonzero, and the same size, this is
1397 the middle of a run. Zero declared size fields are special
1398 and handled as "end of run". (Note: it's nonzero declared
1399 size, but equal type sizes!) (Since we know that both
1400 the current and previous fields are bitfields by the
1401 time we check it, DECL_SIZE must be present for both.) */
1402 if (DECL_BIT_FIELD_TYPE (field
)
1403 && !integer_zerop (DECL_SIZE (field
))
1404 && !integer_zerop (DECL_SIZE (rli
->prev_field
))
1405 && tree_fits_shwi_p (DECL_SIZE (rli
->prev_field
))
1406 && tree_fits_uhwi_p (TYPE_SIZE (type
))
1407 && simple_cst_equal (TYPE_SIZE (type
), TYPE_SIZE (prev_type
)))
1409 /* We're in the middle of a run of equal type size fields; make
1410 sure we realign if we run out of bits. (Not decl size,
1412 HOST_WIDE_INT bitsize
= tree_to_uhwi (DECL_SIZE (field
));
1414 if (rli
->remaining_in_alignment
< bitsize
)
1416 HOST_WIDE_INT typesize
= tree_to_uhwi (TYPE_SIZE (type
));
1418 /* out of bits; bump up to next 'word'. */
1420 = size_binop (PLUS_EXPR
, rli
->bitpos
,
1421 bitsize_int (rli
->remaining_in_alignment
));
1422 rli
->prev_field
= field
;
1423 if (typesize
< bitsize
)
1424 rli
->remaining_in_alignment
= 0;
1426 rli
->remaining_in_alignment
= typesize
- bitsize
;
1429 rli
->remaining_in_alignment
-= bitsize
;
1433 /* End of a run: if leaving a run of bitfields of the same type
1434 size, we have to "use up" the rest of the bits of the type
1437 Compute the new position as the sum of the size for the prior
1438 type and where we first started working on that type.
1439 Note: since the beginning of the field was aligned then
1440 of course the end will be too. No round needed. */
1442 if (!integer_zerop (DECL_SIZE (rli
->prev_field
)))
1445 = size_binop (PLUS_EXPR
, rli
->bitpos
,
1446 bitsize_int (rli
->remaining_in_alignment
));
1449 /* We "use up" size zero fields; the code below should behave
1450 as if the prior field was not a bitfield. */
1453 /* Cause a new bitfield to be captured, either this time (if
1454 currently a bitfield) or next time we see one. */
1455 if (!DECL_BIT_FIELD_TYPE (field
)
1456 || integer_zerop (DECL_SIZE (field
)))
1457 rli
->prev_field
= NULL
;
1460 normalize_rli (rli
);
1463 /* If we're starting a new run of same type size bitfields
1464 (or a run of non-bitfields), set up the "first of the run"
1467 That is, if the current field is not a bitfield, or if there
1468 was a prior bitfield the type sizes differ, or if there wasn't
1469 a prior bitfield the size of the current field is nonzero.
1471 Note: we must be sure to test ONLY the type size if there was
1472 a prior bitfield and ONLY for the current field being zero if
1475 if (!DECL_BIT_FIELD_TYPE (field
)
1476 || (prev_saved
!= NULL
1477 ? !simple_cst_equal (TYPE_SIZE (type
), TYPE_SIZE (prev_type
))
1478 : !integer_zerop (DECL_SIZE (field
)) ))
1480 /* Never smaller than a byte for compatibility. */
1481 unsigned int type_align
= BITS_PER_UNIT
;
1483 /* (When not a bitfield), we could be seeing a flex array (with
1484 no DECL_SIZE). Since we won't be using remaining_in_alignment
1485 until we see a bitfield (and come by here again) we just skip
1487 if (DECL_SIZE (field
) != NULL
1488 && tree_fits_uhwi_p (TYPE_SIZE (TREE_TYPE (field
)))
1489 && tree_fits_uhwi_p (DECL_SIZE (field
)))
1491 unsigned HOST_WIDE_INT bitsize
1492 = tree_to_uhwi (DECL_SIZE (field
));
1493 unsigned HOST_WIDE_INT typesize
1494 = tree_to_uhwi (TYPE_SIZE (TREE_TYPE (field
)));
1496 if (typesize
< bitsize
)
1497 rli
->remaining_in_alignment
= 0;
1499 rli
->remaining_in_alignment
= typesize
- bitsize
;
1502 /* Now align (conventionally) for the new type. */
1503 type_align
= TYPE_ALIGN (TREE_TYPE (field
));
1505 if (maximum_field_alignment
!= 0)
1506 type_align
= MIN (type_align
, maximum_field_alignment
);
1508 rli
->bitpos
= round_up (rli
->bitpos
, type_align
);
1510 /* If we really aligned, don't allow subsequent bitfields
1512 rli
->prev_field
= NULL
;
1516 /* Offset so far becomes the position of this field after normalizing. */
1517 normalize_rli (rli
);
1518 DECL_FIELD_OFFSET (field
) = rli
->offset
;
1519 DECL_FIELD_BIT_OFFSET (field
) = rli
->bitpos
;
1520 SET_DECL_OFFSET_ALIGN (field
, rli
->offset_align
);
1522 /* Evaluate nonconstant offsets only once, either now or as soon as safe. */
1523 if (TREE_CODE (DECL_FIELD_OFFSET (field
)) != INTEGER_CST
)
1524 DECL_FIELD_OFFSET (field
) = variable_size (DECL_FIELD_OFFSET (field
));
1526 /* If this field ended up more aligned than we thought it would be (we
1527 approximate this by seeing if its position changed), lay out the field
1528 again; perhaps we can use an integral mode for it now. */
1529 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field
)))
1530 actual_align
= (tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field
))
1531 & - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field
)));
1532 else if (integer_zerop (DECL_FIELD_OFFSET (field
)))
1533 actual_align
= MAX (BIGGEST_ALIGNMENT
, rli
->record_align
);
1534 else if (tree_fits_uhwi_p (DECL_FIELD_OFFSET (field
)))
1535 actual_align
= (BITS_PER_UNIT
1536 * (tree_to_uhwi (DECL_FIELD_OFFSET (field
))
1537 & - tree_to_uhwi (DECL_FIELD_OFFSET (field
))));
1539 actual_align
= DECL_OFFSET_ALIGN (field
);
1540 /* ACTUAL_ALIGN is still the actual alignment *within the record* .
1541 store / extract bit field operations will check the alignment of the
1542 record against the mode of bit fields. */
1544 if (known_align
!= actual_align
)
1545 layout_decl (field
, actual_align
);
1547 if (rli
->prev_field
== NULL
&& DECL_BIT_FIELD_TYPE (field
))
1548 rli
->prev_field
= field
;
1550 /* Now add size of this field to the size of the record. If the size is
1551 not constant, treat the field as being a multiple of bytes and just
1552 adjust the offset, resetting the bit position. Otherwise, apportion the
1553 size amongst the bit position and offset. First handle the case of an
1554 unspecified size, which can happen when we have an invalid nested struct
1555 definition, such as struct j { struct j { int i; } }. The error message
1556 is printed in finish_struct. */
1557 if (DECL_SIZE (field
) == 0)
1559 else if (TREE_CODE (DECL_SIZE (field
)) != INTEGER_CST
1560 || TREE_OVERFLOW (DECL_SIZE (field
)))
1563 = size_binop (PLUS_EXPR
, rli
->offset
,
1564 fold_convert (sizetype
,
1565 size_binop (CEIL_DIV_EXPR
, rli
->bitpos
,
1566 bitsize_unit_node
)));
1568 = size_binop (PLUS_EXPR
, rli
->offset
, DECL_SIZE_UNIT (field
));
1569 rli
->bitpos
= bitsize_zero_node
;
1570 rli
->offset_align
= MIN (rli
->offset_align
, desired_align
);
1572 else if (targetm
.ms_bitfield_layout_p (rli
->t
))
1574 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
, DECL_SIZE (field
));
1576 /* If we ended a bitfield before the full length of the type then
1577 pad the struct out to the full length of the last type. */
1578 if ((DECL_CHAIN (field
) == NULL
1579 || TREE_CODE (DECL_CHAIN (field
)) != FIELD_DECL
)
1580 && DECL_BIT_FIELD_TYPE (field
)
1581 && !integer_zerop (DECL_SIZE (field
)))
1582 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
,
1583 bitsize_int (rli
->remaining_in_alignment
));
1585 normalize_rli (rli
);
1589 rli
->bitpos
= size_binop (PLUS_EXPR
, rli
->bitpos
, DECL_SIZE (field
));
1590 normalize_rli (rli
);
1594 /* Assuming that all the fields have been laid out, this function uses
1595 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
1596 indicated by RLI. */
1599 finalize_record_size (record_layout_info rli
)
1601 tree unpadded_size
, unpadded_size_unit
;
1603 /* Now we want just byte and bit offsets, so set the offset alignment
1604 to be a byte and then normalize. */
1605 rli
->offset_align
= BITS_PER_UNIT
;
1606 normalize_rli (rli
);
1608 /* Determine the desired alignment. */
1609 #ifdef ROUND_TYPE_ALIGN
1610 TYPE_ALIGN (rli
->t
) = ROUND_TYPE_ALIGN (rli
->t
, TYPE_ALIGN (rli
->t
),
1613 TYPE_ALIGN (rli
->t
) = MAX (TYPE_ALIGN (rli
->t
), rli
->record_align
);
1616 /* Compute the size so far. Be sure to allow for extra bits in the
1617 size in bytes. We have guaranteed above that it will be no more
1618 than a single byte. */
1619 unpadded_size
= rli_size_so_far (rli
);
1620 unpadded_size_unit
= rli_size_unit_so_far (rli
);
1621 if (! integer_zerop (rli
->bitpos
))
1623 = size_binop (PLUS_EXPR
, unpadded_size_unit
, size_one_node
);
1625 /* Round the size up to be a multiple of the required alignment. */
1626 TYPE_SIZE (rli
->t
) = round_up (unpadded_size
, TYPE_ALIGN (rli
->t
));
1627 TYPE_SIZE_UNIT (rli
->t
)
1628 = round_up (unpadded_size_unit
, TYPE_ALIGN_UNIT (rli
->t
));
1630 if (TREE_CONSTANT (unpadded_size
)
1631 && simple_cst_equal (unpadded_size
, TYPE_SIZE (rli
->t
)) == 0
1632 && input_location
!= BUILTINS_LOCATION
)
1633 warning (OPT_Wpadded
, "padding struct size to alignment boundary");
1635 if (warn_packed
&& TREE_CODE (rli
->t
) == RECORD_TYPE
1636 && TYPE_PACKED (rli
->t
) && ! rli
->packed_maybe_necessary
1637 && TREE_CONSTANT (unpadded_size
))
1641 #ifdef ROUND_TYPE_ALIGN
1643 = ROUND_TYPE_ALIGN (rli
->t
, TYPE_ALIGN (rli
->t
), rli
->unpacked_align
);
1645 rli
->unpacked_align
= MAX (TYPE_ALIGN (rli
->t
), rli
->unpacked_align
);
1648 unpacked_size
= round_up (TYPE_SIZE (rli
->t
), rli
->unpacked_align
);
1649 if (simple_cst_equal (unpacked_size
, TYPE_SIZE (rli
->t
)))
1651 if (TYPE_NAME (rli
->t
))
1655 if (TREE_CODE (TYPE_NAME (rli
->t
)) == IDENTIFIER_NODE
)
1656 name
= TYPE_NAME (rli
->t
);
1658 name
= DECL_NAME (TYPE_NAME (rli
->t
));
1660 if (STRICT_ALIGNMENT
)
1661 warning (OPT_Wpacked
, "packed attribute causes inefficient "
1662 "alignment for %qE", name
);
1664 warning (OPT_Wpacked
,
1665 "packed attribute is unnecessary for %qE", name
);
1669 if (STRICT_ALIGNMENT
)
1670 warning (OPT_Wpacked
,
1671 "packed attribute causes inefficient alignment");
1673 warning (OPT_Wpacked
, "packed attribute is unnecessary");
1679 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
1682 compute_record_mode (tree type
)
1685 machine_mode mode
= VOIDmode
;
1687 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
1688 However, if possible, we use a mode that fits in a register
1689 instead, in order to allow for better optimization down the
1691 SET_TYPE_MODE (type
, BLKmode
);
1693 if (! tree_fits_uhwi_p (TYPE_SIZE (type
)))
1696 /* A record which has any BLKmode members must itself be
1697 BLKmode; it can't go in a register. Unless the member is
1698 BLKmode only because it isn't aligned. */
1699 for (field
= TYPE_FIELDS (type
); field
; field
= DECL_CHAIN (field
))
1701 if (TREE_CODE (field
) != FIELD_DECL
)
1704 if (TREE_CODE (TREE_TYPE (field
)) == ERROR_MARK
1705 || (TYPE_MODE (TREE_TYPE (field
)) == BLKmode
1706 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field
))
1707 && !(TYPE_SIZE (TREE_TYPE (field
)) != 0
1708 && integer_zerop (TYPE_SIZE (TREE_TYPE (field
)))))
1709 || ! tree_fits_uhwi_p (bit_position (field
))
1710 || DECL_SIZE (field
) == 0
1711 || ! tree_fits_uhwi_p (DECL_SIZE (field
)))
1714 /* If this field is the whole struct, remember its mode so
1715 that, say, we can put a double in a class into a DF
1716 register instead of forcing it to live in the stack. */
1717 if (simple_cst_equal (TYPE_SIZE (type
), DECL_SIZE (field
)))
1718 mode
= DECL_MODE (field
);
1720 /* With some targets, it is sub-optimal to access an aligned
1721 BLKmode structure as a scalar. */
1722 if (targetm
.member_type_forces_blk (field
, mode
))
1726 /* If we only have one real field; use its mode if that mode's size
1727 matches the type's size. This only applies to RECORD_TYPE. This
1728 does not apply to unions. */
1729 if (TREE_CODE (type
) == RECORD_TYPE
&& mode
!= VOIDmode
1730 && tree_fits_uhwi_p (TYPE_SIZE (type
))
1731 && GET_MODE_BITSIZE (mode
) == tree_to_uhwi (TYPE_SIZE (type
)))
1732 SET_TYPE_MODE (type
, mode
);
1734 SET_TYPE_MODE (type
, mode_for_size_tree (TYPE_SIZE (type
), MODE_INT
, 1));
1736 /* If structure's known alignment is less than what the scalar
1737 mode would need, and it matters, then stick with BLKmode. */
1738 if (TYPE_MODE (type
) != BLKmode
1740 && ! (TYPE_ALIGN (type
) >= BIGGEST_ALIGNMENT
1741 || TYPE_ALIGN (type
) >= GET_MODE_ALIGNMENT (TYPE_MODE (type
))))
1743 /* If this is the only reason this type is BLKmode, then
1744 don't force containing types to be BLKmode. */
1745 TYPE_NO_FORCE_BLK (type
) = 1;
1746 SET_TYPE_MODE (type
, BLKmode
);
1750 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1754 finalize_type_size (tree type
)
1756 /* Normally, use the alignment corresponding to the mode chosen.
1757 However, where strict alignment is not required, avoid
1758 over-aligning structures, since most compilers do not do this
1760 if (TYPE_MODE (type
) != BLKmode
1761 && TYPE_MODE (type
) != VOIDmode
1762 && (STRICT_ALIGNMENT
|| !AGGREGATE_TYPE_P (type
)))
1764 unsigned mode_align
= GET_MODE_ALIGNMENT (TYPE_MODE (type
));
1766 /* Don't override a larger alignment requirement coming from a user
1767 alignment of one of the fields. */
1768 if (mode_align
>= TYPE_ALIGN (type
))
1770 TYPE_ALIGN (type
) = mode_align
;
1771 TYPE_USER_ALIGN (type
) = 0;
1775 /* Do machine-dependent extra alignment. */
1776 #ifdef ROUND_TYPE_ALIGN
1778 = ROUND_TYPE_ALIGN (type
, TYPE_ALIGN (type
), BITS_PER_UNIT
);
1781 /* If we failed to find a simple way to calculate the unit size
1782 of the type, find it by division. */
1783 if (TYPE_SIZE_UNIT (type
) == 0 && TYPE_SIZE (type
) != 0)
1784 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1785 result will fit in sizetype. We will get more efficient code using
1786 sizetype, so we force a conversion. */
1787 TYPE_SIZE_UNIT (type
)
1788 = fold_convert (sizetype
,
1789 size_binop (FLOOR_DIV_EXPR
, TYPE_SIZE (type
),
1790 bitsize_unit_node
));
1792 if (TYPE_SIZE (type
) != 0)
1794 TYPE_SIZE (type
) = round_up (TYPE_SIZE (type
), TYPE_ALIGN (type
));
1795 TYPE_SIZE_UNIT (type
)
1796 = round_up (TYPE_SIZE_UNIT (type
), TYPE_ALIGN_UNIT (type
));
1799 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1800 if (TYPE_SIZE (type
) != 0 && TREE_CODE (TYPE_SIZE (type
)) != INTEGER_CST
)
1801 TYPE_SIZE (type
) = variable_size (TYPE_SIZE (type
));
1802 if (TYPE_SIZE_UNIT (type
) != 0
1803 && TREE_CODE (TYPE_SIZE_UNIT (type
)) != INTEGER_CST
)
1804 TYPE_SIZE_UNIT (type
) = variable_size (TYPE_SIZE_UNIT (type
));
1806 /* Also layout any other variants of the type. */
1807 if (TYPE_NEXT_VARIANT (type
)
1808 || type
!= TYPE_MAIN_VARIANT (type
))
1811 /* Record layout info of this variant. */
1812 tree size
= TYPE_SIZE (type
);
1813 tree size_unit
= TYPE_SIZE_UNIT (type
);
1814 unsigned int align
= TYPE_ALIGN (type
);
1815 unsigned int precision
= TYPE_PRECISION (type
);
1816 unsigned int user_align
= TYPE_USER_ALIGN (type
);
1817 machine_mode mode
= TYPE_MODE (type
);
1819 /* Copy it into all variants. */
1820 for (variant
= TYPE_MAIN_VARIANT (type
);
1822 variant
= TYPE_NEXT_VARIANT (variant
))
1824 TYPE_SIZE (variant
) = size
;
1825 TYPE_SIZE_UNIT (variant
) = size_unit
;
1826 unsigned valign
= align
;
1827 if (TYPE_USER_ALIGN (variant
))
1828 valign
= MAX (valign
, TYPE_ALIGN (variant
));
1830 TYPE_USER_ALIGN (variant
) = user_align
;
1831 TYPE_ALIGN (variant
) = valign
;
1832 TYPE_PRECISION (variant
) = precision
;
1833 SET_TYPE_MODE (variant
, mode
);
1838 /* Return a new underlying object for a bitfield started with FIELD. */
1841 start_bitfield_representative (tree field
)
1843 tree repr
= make_node (FIELD_DECL
);
1844 DECL_FIELD_OFFSET (repr
) = DECL_FIELD_OFFSET (field
);
1845 /* Force the representative to begin at a BITS_PER_UNIT aligned
1846 boundary - C++ may use tail-padding of a base object to
1847 continue packing bits so the bitfield region does not start
1848 at bit zero (see g++.dg/abi/bitfield5.C for example).
1849 Unallocated bits may happen for other reasons as well,
1850 for example Ada which allows explicit bit-granular structure layout. */
1851 DECL_FIELD_BIT_OFFSET (repr
)
1852 = size_binop (BIT_AND_EXPR
,
1853 DECL_FIELD_BIT_OFFSET (field
),
1854 bitsize_int (~(BITS_PER_UNIT
- 1)));
1855 SET_DECL_OFFSET_ALIGN (repr
, DECL_OFFSET_ALIGN (field
));
1856 DECL_SIZE (repr
) = DECL_SIZE (field
);
1857 DECL_SIZE_UNIT (repr
) = DECL_SIZE_UNIT (field
);
1858 DECL_PACKED (repr
) = DECL_PACKED (field
);
1859 DECL_CONTEXT (repr
) = DECL_CONTEXT (field
);
1863 /* Finish up a bitfield group that was started by creating the underlying
1864 object REPR with the last field in the bitfield group FIELD. */
1867 finish_bitfield_representative (tree repr
, tree field
)
1869 unsigned HOST_WIDE_INT bitsize
, maxbitsize
;
1873 size
= size_diffop (DECL_FIELD_OFFSET (field
),
1874 DECL_FIELD_OFFSET (repr
));
1875 while (TREE_CODE (size
) == COMPOUND_EXPR
)
1876 size
= TREE_OPERAND (size
, 1);
1877 gcc_assert (tree_fits_uhwi_p (size
));
1878 bitsize
= (tree_to_uhwi (size
) * BITS_PER_UNIT
1879 + tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field
))
1880 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr
))
1881 + tree_to_uhwi (DECL_SIZE (field
)));
1883 /* Round up bitsize to multiples of BITS_PER_UNIT. */
1884 bitsize
= (bitsize
+ BITS_PER_UNIT
- 1) & ~(BITS_PER_UNIT
- 1);
1886 /* Now nothing tells us how to pad out bitsize ... */
1887 nextf
= DECL_CHAIN (field
);
1888 while (nextf
&& TREE_CODE (nextf
) != FIELD_DECL
)
1889 nextf
= DECL_CHAIN (nextf
);
1893 /* If there was an error, the field may be not laid out
1894 correctly. Don't bother to do anything. */
1895 if (TREE_TYPE (nextf
) == error_mark_node
)
1897 maxsize
= size_diffop (DECL_FIELD_OFFSET (nextf
),
1898 DECL_FIELD_OFFSET (repr
));
1899 if (tree_fits_uhwi_p (maxsize
))
1901 maxbitsize
= (tree_to_uhwi (maxsize
) * BITS_PER_UNIT
1902 + tree_to_uhwi (DECL_FIELD_BIT_OFFSET (nextf
))
1903 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr
)));
1904 /* If the group ends within a bitfield nextf does not need to be
1905 aligned to BITS_PER_UNIT. Thus round up. */
1906 maxbitsize
= (maxbitsize
+ BITS_PER_UNIT
- 1) & ~(BITS_PER_UNIT
- 1);
1909 maxbitsize
= bitsize
;
1913 /* ??? If you consider that tail-padding of this struct might be
1914 re-used when deriving from it we cannot really do the following
1915 and thus need to set maxsize to bitsize? Also we cannot
1916 generally rely on maxsize to fold to an integer constant, so
1917 use bitsize as fallback for this case. */
1918 tree maxsize
= size_diffop (TYPE_SIZE_UNIT (DECL_CONTEXT (field
)),
1919 DECL_FIELD_OFFSET (repr
));
1920 if (tree_fits_uhwi_p (maxsize
))
1921 maxbitsize
= (tree_to_uhwi (maxsize
) * BITS_PER_UNIT
1922 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr
)));
1924 maxbitsize
= bitsize
;
1927 /* Only if we don't artificially break up the representative in
1928 the middle of a large bitfield with different possibly
1929 overlapping representatives. And all representatives start
1931 gcc_assert (maxbitsize
% BITS_PER_UNIT
== 0);
1933 /* Find the smallest nice mode to use. */
1934 for (mode
= GET_CLASS_NARROWEST_MODE (MODE_INT
); mode
!= VOIDmode
;
1935 mode
= GET_MODE_WIDER_MODE (mode
))
1936 if (GET_MODE_BITSIZE (mode
) >= bitsize
)
1938 if (mode
!= VOIDmode
1939 && (GET_MODE_BITSIZE (mode
) > maxbitsize
1940 || GET_MODE_BITSIZE (mode
) > MAX_FIXED_MODE_SIZE
))
1943 if (mode
== VOIDmode
)
1945 /* We really want a BLKmode representative only as a last resort,
1946 considering the member b in
1947 struct { int a : 7; int b : 17; int c; } __attribute__((packed));
1948 Otherwise we simply want to split the representative up
1949 allowing for overlaps within the bitfield region as required for
1950 struct { int a : 7; int b : 7;
1951 int c : 10; int d; } __attribute__((packed));
1952 [0, 15] HImode for a and b, [8, 23] HImode for c. */
1953 DECL_SIZE (repr
) = bitsize_int (bitsize
);
1954 DECL_SIZE_UNIT (repr
) = size_int (bitsize
/ BITS_PER_UNIT
);
1955 DECL_MODE (repr
) = BLKmode
;
1956 TREE_TYPE (repr
) = build_array_type_nelts (unsigned_char_type_node
,
1957 bitsize
/ BITS_PER_UNIT
);
1961 unsigned HOST_WIDE_INT modesize
= GET_MODE_BITSIZE (mode
);
1962 DECL_SIZE (repr
) = bitsize_int (modesize
);
1963 DECL_SIZE_UNIT (repr
) = size_int (modesize
/ BITS_PER_UNIT
);
1964 DECL_MODE (repr
) = mode
;
1965 TREE_TYPE (repr
) = lang_hooks
.types
.type_for_mode (mode
, 1);
1968 /* Remember whether the bitfield group is at the end of the
1969 structure or not. */
1970 DECL_CHAIN (repr
) = nextf
;
1973 /* Compute and set FIELD_DECLs for the underlying objects we should
1974 use for bitfield access for the structure T. */
1977 finish_bitfield_layout (tree t
)
1980 tree repr
= NULL_TREE
;
1982 /* Unions would be special, for the ease of type-punning optimizations
1983 we could use the underlying type as hint for the representative
1984 if the bitfield would fit and the representative would not exceed
1985 the union in size. */
1986 if (TREE_CODE (t
) != RECORD_TYPE
)
1989 for (prev
= NULL_TREE
, field
= TYPE_FIELDS (t
);
1990 field
; field
= DECL_CHAIN (field
))
1992 if (TREE_CODE (field
) != FIELD_DECL
)
1995 /* In the C++ memory model, consecutive bit fields in a structure are
1996 considered one memory location and updating a memory location
1997 may not store into adjacent memory locations. */
1999 && DECL_BIT_FIELD_TYPE (field
))
2001 /* Start new representative. */
2002 repr
= start_bitfield_representative (field
);
2005 && ! DECL_BIT_FIELD_TYPE (field
))
2007 /* Finish off new representative. */
2008 finish_bitfield_representative (repr
, prev
);
2011 else if (DECL_BIT_FIELD_TYPE (field
))
2013 gcc_assert (repr
!= NULL_TREE
);
2015 /* Zero-size bitfields finish off a representative and
2016 do not have a representative themselves. This is
2017 required by the C++ memory model. */
2018 if (integer_zerop (DECL_SIZE (field
)))
2020 finish_bitfield_representative (repr
, prev
);
2024 /* We assume that either DECL_FIELD_OFFSET of the representative
2025 and each bitfield member is a constant or they are equal.
2026 This is because we need to be able to compute the bit-offset
2027 of each field relative to the representative in get_bit_range
2028 during RTL expansion.
2029 If these constraints are not met, simply force a new
2030 representative to be generated. That will at most
2031 generate worse code but still maintain correctness with
2032 respect to the C++ memory model. */
2033 else if (!((tree_fits_uhwi_p (DECL_FIELD_OFFSET (repr
))
2034 && tree_fits_uhwi_p (DECL_FIELD_OFFSET (field
)))
2035 || operand_equal_p (DECL_FIELD_OFFSET (repr
),
2036 DECL_FIELD_OFFSET (field
), 0)))
2038 finish_bitfield_representative (repr
, prev
);
2039 repr
= start_bitfield_representative (field
);
2046 DECL_BIT_FIELD_REPRESENTATIVE (field
) = repr
;
2052 finish_bitfield_representative (repr
, prev
);
2055 /* Do all of the work required to layout the type indicated by RLI,
2056 once the fields have been laid out. This function will call `free'
2057 for RLI, unless FREE_P is false. Passing a value other than false
2058 for FREE_P is bad practice; this option only exists to support the
2062 finish_record_layout (record_layout_info rli
, int free_p
)
2066 /* Compute the final size. */
2067 finalize_record_size (rli
);
2069 /* Compute the TYPE_MODE for the record. */
2070 compute_record_mode (rli
->t
);
2072 /* Perform any last tweaks to the TYPE_SIZE, etc. */
2073 finalize_type_size (rli
->t
);
2075 /* Compute bitfield representatives. */
2076 finish_bitfield_layout (rli
->t
);
2078 /* Propagate TYPE_PACKED to variants. With C++ templates,
2079 handle_packed_attribute is too early to do this. */
2080 for (variant
= TYPE_NEXT_VARIANT (rli
->t
); variant
;
2081 variant
= TYPE_NEXT_VARIANT (variant
))
2082 TYPE_PACKED (variant
) = TYPE_PACKED (rli
->t
);
2084 /* Lay out any static members. This is done now because their type
2085 may use the record's type. */
2086 while (!vec_safe_is_empty (rli
->pending_statics
))
2087 layout_decl (rli
->pending_statics
->pop (), 0);
2092 vec_free (rli
->pending_statics
);
2098 /* Finish processing a builtin RECORD_TYPE type TYPE. It's name is
2099 NAME, its fields are chained in reverse on FIELDS.
2101 If ALIGN_TYPE is non-null, it is given the same alignment as
2105 finish_builtin_struct (tree type
, const char *name
, tree fields
,
2110 for (tail
= NULL_TREE
; fields
; tail
= fields
, fields
= next
)
2112 DECL_FIELD_CONTEXT (fields
) = type
;
2113 next
= DECL_CHAIN (fields
);
2114 DECL_CHAIN (fields
) = tail
;
2116 TYPE_FIELDS (type
) = tail
;
2120 TYPE_ALIGN (type
) = TYPE_ALIGN (align_type
);
2121 TYPE_USER_ALIGN (type
) = TYPE_USER_ALIGN (align_type
);
2125 #if 0 /* not yet, should get fixed properly later */
2126 TYPE_NAME (type
) = make_type_decl (get_identifier (name
), type
);
2128 TYPE_NAME (type
) = build_decl (BUILTINS_LOCATION
,
2129 TYPE_DECL
, get_identifier (name
), type
);
2131 TYPE_STUB_DECL (type
) = TYPE_NAME (type
);
2132 layout_decl (TYPE_NAME (type
), 0);
2135 /* Calculate the mode, size, and alignment for TYPE.
2136 For an array type, calculate the element separation as well.
2137 Record TYPE on the chain of permanent or temporary types
2138 so that dbxout will find out about it.
2140 TYPE_SIZE of a type is nonzero if the type has been laid out already.
2141 layout_type does nothing on such a type.
2143 If the type is incomplete, its TYPE_SIZE remains zero. */
2146 layout_type (tree type
)
2150 if (type
== error_mark_node
)
2153 /* We don't want finalize_type_size to copy an alignment attribute to
2154 variants that don't have it. */
2155 type
= TYPE_MAIN_VARIANT (type
);
2157 /* Do nothing if type has been laid out before. */
2158 if (TYPE_SIZE (type
))
2161 switch (TREE_CODE (type
))
2164 /* This kind of type is the responsibility
2165 of the language-specific code. */
2171 SET_TYPE_MODE (type
,
2172 smallest_mode_for_size (TYPE_PRECISION (type
), MODE_INT
));
2173 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
2174 /* Don't set TYPE_PRECISION here, as it may be set by a bitfield. */
2175 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
2179 SET_TYPE_MODE (type
,
2180 mode_for_size (TYPE_PRECISION (type
), MODE_FLOAT
, 0));
2181 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
2182 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
2185 case FIXED_POINT_TYPE
:
2186 /* TYPE_MODE (type) has been set already. */
2187 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
2188 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
2192 TYPE_UNSIGNED (type
) = TYPE_UNSIGNED (TREE_TYPE (type
));
2193 SET_TYPE_MODE (type
,
2194 mode_for_size (2 * TYPE_PRECISION (TREE_TYPE (type
)),
2195 (TREE_CODE (TREE_TYPE (type
)) == REAL_TYPE
2196 ? MODE_COMPLEX_FLOAT
: MODE_COMPLEX_INT
),
2198 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
2199 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
2204 int nunits
= TYPE_VECTOR_SUBPARTS (type
);
2205 tree innertype
= TREE_TYPE (type
);
2207 gcc_assert (!(nunits
& (nunits
- 1)));
2209 /* Find an appropriate mode for the vector type. */
2210 if (TYPE_MODE (type
) == VOIDmode
)
2211 SET_TYPE_MODE (type
,
2212 mode_for_vector (TYPE_MODE (innertype
), nunits
));
2214 TYPE_SATURATING (type
) = TYPE_SATURATING (TREE_TYPE (type
));
2215 TYPE_UNSIGNED (type
) = TYPE_UNSIGNED (TREE_TYPE (type
));
2216 TYPE_SIZE_UNIT (type
) = int_const_binop (MULT_EXPR
,
2217 TYPE_SIZE_UNIT (innertype
),
2219 TYPE_SIZE (type
) = int_const_binop (MULT_EXPR
, TYPE_SIZE (innertype
),
2220 bitsize_int (nunits
));
2222 /* For vector types, we do not default to the mode's alignment.
2223 Instead, query a target hook, defaulting to natural alignment.
2224 This prevents ABI changes depending on whether or not native
2225 vector modes are supported. */
2226 TYPE_ALIGN (type
) = targetm
.vector_alignment (type
);
2228 /* However, if the underlying mode requires a bigger alignment than
2229 what the target hook provides, we cannot use the mode. For now,
2230 simply reject that case. */
2231 gcc_assert (TYPE_ALIGN (type
)
2232 >= GET_MODE_ALIGNMENT (TYPE_MODE (type
)));
2237 /* This is an incomplete type and so doesn't have a size. */
2238 TYPE_ALIGN (type
) = 1;
2239 TYPE_USER_ALIGN (type
) = 0;
2240 SET_TYPE_MODE (type
, VOIDmode
);
2243 case POINTER_BOUNDS_TYPE
:
2244 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type
)));
2245 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (TYPE_MODE (type
)));
2249 TYPE_SIZE (type
) = bitsize_int (POINTER_SIZE
);
2250 TYPE_SIZE_UNIT (type
) = size_int (POINTER_SIZE_UNITS
);
2251 /* A pointer might be MODE_PARTIAL_INT, but ptrdiff_t must be
2252 integral, which may be an __intN. */
2253 SET_TYPE_MODE (type
, mode_for_size (POINTER_SIZE
, MODE_INT
, 0));
2254 TYPE_PRECISION (type
) = POINTER_SIZE
;
2259 /* It's hard to see what the mode and size of a function ought to
2260 be, but we do know the alignment is FUNCTION_BOUNDARY, so
2261 make it consistent with that. */
2262 SET_TYPE_MODE (type
, mode_for_size (FUNCTION_BOUNDARY
, MODE_INT
, 0));
2263 TYPE_SIZE (type
) = bitsize_int (FUNCTION_BOUNDARY
);
2264 TYPE_SIZE_UNIT (type
) = size_int (FUNCTION_BOUNDARY
/ BITS_PER_UNIT
);
2268 case REFERENCE_TYPE
:
2270 machine_mode mode
= TYPE_MODE (type
);
2271 if (TREE_CODE (type
) == REFERENCE_TYPE
&& reference_types_internal
)
2273 addr_space_t as
= TYPE_ADDR_SPACE (TREE_TYPE (type
));
2274 mode
= targetm
.addr_space
.address_mode (as
);
2277 TYPE_SIZE (type
) = bitsize_int (GET_MODE_BITSIZE (mode
));
2278 TYPE_SIZE_UNIT (type
) = size_int (GET_MODE_SIZE (mode
));
2279 TYPE_UNSIGNED (type
) = 1;
2280 TYPE_PRECISION (type
) = GET_MODE_PRECISION (mode
);
2286 tree index
= TYPE_DOMAIN (type
);
2287 tree element
= TREE_TYPE (type
);
2289 build_pointer_type (element
);
2291 /* We need to know both bounds in order to compute the size. */
2292 if (index
&& TYPE_MAX_VALUE (index
) && TYPE_MIN_VALUE (index
)
2293 && TYPE_SIZE (element
))
2295 tree ub
= TYPE_MAX_VALUE (index
);
2296 tree lb
= TYPE_MIN_VALUE (index
);
2297 tree element_size
= TYPE_SIZE (element
);
2300 /* Make sure that an array of zero-sized element is zero-sized
2301 regardless of its extent. */
2302 if (integer_zerop (element_size
))
2303 length
= size_zero_node
;
2305 /* The computation should happen in the original signedness so
2306 that (possible) negative values are handled appropriately
2307 when determining overflow. */
2310 /* ??? When it is obvious that the range is signed
2311 represent it using ssizetype. */
2312 if (TREE_CODE (lb
) == INTEGER_CST
2313 && TREE_CODE (ub
) == INTEGER_CST
2314 && TYPE_UNSIGNED (TREE_TYPE (lb
))
2315 && tree_int_cst_lt (ub
, lb
))
2317 lb
= wide_int_to_tree (ssizetype
,
2318 offset_int::from (lb
, SIGNED
));
2319 ub
= wide_int_to_tree (ssizetype
,
2320 offset_int::from (ub
, SIGNED
));
2323 = fold_convert (sizetype
,
2324 size_binop (PLUS_EXPR
,
2325 build_int_cst (TREE_TYPE (lb
), 1),
2326 size_binop (MINUS_EXPR
, ub
, lb
)));
2329 /* ??? We have no way to distinguish a null-sized array from an
2330 array spanning the whole sizetype range, so we arbitrarily
2331 decide that [0, -1] is the only valid representation. */
2332 if (integer_zerop (length
)
2333 && TREE_OVERFLOW (length
)
2334 && integer_zerop (lb
))
2335 length
= size_zero_node
;
2337 TYPE_SIZE (type
) = size_binop (MULT_EXPR
, element_size
,
2338 fold_convert (bitsizetype
,
2341 /* If we know the size of the element, calculate the total size
2342 directly, rather than do some division thing below. This
2343 optimization helps Fortran assumed-size arrays (where the
2344 size of the array is determined at runtime) substantially. */
2345 if (TYPE_SIZE_UNIT (element
))
2346 TYPE_SIZE_UNIT (type
)
2347 = size_binop (MULT_EXPR
, TYPE_SIZE_UNIT (element
), length
);
2350 /* Now round the alignment and size,
2351 using machine-dependent criteria if any. */
2353 unsigned align
= TYPE_ALIGN (element
);
2354 if (TYPE_USER_ALIGN (type
))
2355 align
= MAX (align
, TYPE_ALIGN (type
));
2357 TYPE_USER_ALIGN (type
) = TYPE_USER_ALIGN (element
);
2358 #ifdef ROUND_TYPE_ALIGN
2359 align
= ROUND_TYPE_ALIGN (type
, align
, BITS_PER_UNIT
);
2361 align
= MAX (align
, BITS_PER_UNIT
);
2363 TYPE_ALIGN (type
) = align
;
2364 SET_TYPE_MODE (type
, BLKmode
);
2365 if (TYPE_SIZE (type
) != 0
2366 && ! targetm
.member_type_forces_blk (type
, VOIDmode
)
2367 /* BLKmode elements force BLKmode aggregate;
2368 else extract/store fields may lose. */
2369 && (TYPE_MODE (TREE_TYPE (type
)) != BLKmode
2370 || TYPE_NO_FORCE_BLK (TREE_TYPE (type
))))
2372 SET_TYPE_MODE (type
, mode_for_array (TREE_TYPE (type
),
2374 if (TYPE_MODE (type
) != BLKmode
2375 && STRICT_ALIGNMENT
&& TYPE_ALIGN (type
) < BIGGEST_ALIGNMENT
2376 && TYPE_ALIGN (type
) < GET_MODE_ALIGNMENT (TYPE_MODE (type
)))
2378 TYPE_NO_FORCE_BLK (type
) = 1;
2379 SET_TYPE_MODE (type
, BLKmode
);
2382 /* When the element size is constant, check that it is at least as
2383 large as the element alignment. */
2384 if (TYPE_SIZE_UNIT (element
)
2385 && TREE_CODE (TYPE_SIZE_UNIT (element
)) == INTEGER_CST
2386 /* If TYPE_SIZE_UNIT overflowed, then it is certainly larger than
2388 && !TREE_OVERFLOW (TYPE_SIZE_UNIT (element
))
2389 && !integer_zerop (TYPE_SIZE_UNIT (element
))
2390 && compare_tree_int (TYPE_SIZE_UNIT (element
),
2391 TYPE_ALIGN_UNIT (element
)) < 0)
2392 error ("alignment of array elements is greater than element size");
2398 case QUAL_UNION_TYPE
:
2401 record_layout_info rli
;
2403 /* Initialize the layout information. */
2404 rli
= start_record_layout (type
);
2406 /* If this is a QUAL_UNION_TYPE, we want to process the fields
2407 in the reverse order in building the COND_EXPR that denotes
2408 its size. We reverse them again later. */
2409 if (TREE_CODE (type
) == QUAL_UNION_TYPE
)
2410 TYPE_FIELDS (type
) = nreverse (TYPE_FIELDS (type
));
2412 /* Place all the fields. */
2413 for (field
= TYPE_FIELDS (type
); field
; field
= DECL_CHAIN (field
))
2414 place_field (rli
, field
);
2416 if (TREE_CODE (type
) == QUAL_UNION_TYPE
)
2417 TYPE_FIELDS (type
) = nreverse (TYPE_FIELDS (type
));
2419 /* Finish laying out the record. */
2420 finish_record_layout (rli
, /*free_p=*/true);
2428 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
2429 records and unions, finish_record_layout already called this
2431 if (!RECORD_OR_UNION_TYPE_P (type
))
2432 finalize_type_size (type
);
2434 /* We should never see alias sets on incomplete aggregates. And we
2435 should not call layout_type on not incomplete aggregates. */
2436 if (AGGREGATE_TYPE_P (type
))
2437 gcc_assert (!TYPE_ALIAS_SET_KNOWN_P (type
));
2440 /* Return the least alignment required for type TYPE. */
2443 min_align_of_type (tree type
)
2445 unsigned int align
= TYPE_ALIGN (type
);
2446 if (!TYPE_USER_ALIGN (type
))
2448 align
= MIN (align
, BIGGEST_ALIGNMENT
);
2449 #ifdef BIGGEST_FIELD_ALIGNMENT
2450 align
= MIN (align
, BIGGEST_FIELD_ALIGNMENT
);
2452 unsigned int field_align
= align
;
2453 #ifdef ADJUST_FIELD_ALIGN
2454 tree field
= build_decl (UNKNOWN_LOCATION
, FIELD_DECL
, NULL_TREE
, type
);
2455 field_align
= ADJUST_FIELD_ALIGN (field
, field_align
);
2458 align
= MIN (align
, field_align
);
2460 return align
/ BITS_PER_UNIT
;
2463 /* Vector types need to re-check the target flags each time we report
2464 the machine mode. We need to do this because attribute target can
2465 change the result of vector_mode_supported_p and have_regs_of_mode
2466 on a per-function basis. Thus the TYPE_MODE of a VECTOR_TYPE can
2467 change on a per-function basis. */
2468 /* ??? Possibly a better solution is to run through all the types
2469 referenced by a function and re-compute the TYPE_MODE once, rather
2470 than make the TYPE_MODE macro call a function. */
2473 vector_type_mode (const_tree t
)
2477 gcc_assert (TREE_CODE (t
) == VECTOR_TYPE
);
2479 mode
= t
->type_common
.mode
;
2480 if (VECTOR_MODE_P (mode
)
2481 && (!targetm
.vector_mode_supported_p (mode
)
2482 || !have_regs_of_mode
[mode
]))
2484 machine_mode innermode
= TREE_TYPE (t
)->type_common
.mode
;
2486 /* For integers, try mapping it to a same-sized scalar mode. */
2487 if (GET_MODE_CLASS (innermode
) == MODE_INT
)
2489 mode
= mode_for_size (TYPE_VECTOR_SUBPARTS (t
)
2490 * GET_MODE_BITSIZE (innermode
), MODE_INT
, 0);
2492 if (mode
!= VOIDmode
&& have_regs_of_mode
[mode
])
2502 /* Create and return a type for signed integers of PRECISION bits. */
2505 make_signed_type (int precision
)
2507 tree type
= make_node (INTEGER_TYPE
);
2509 TYPE_PRECISION (type
) = precision
;
2511 fixup_signed_type (type
);
2515 /* Create and return a type for unsigned integers of PRECISION bits. */
2518 make_unsigned_type (int precision
)
2520 tree type
= make_node (INTEGER_TYPE
);
2522 TYPE_PRECISION (type
) = precision
;
2524 fixup_unsigned_type (type
);
2528 /* Create and return a type for fract of PRECISION bits, UNSIGNEDP,
2532 make_fract_type (int precision
, int unsignedp
, int satp
)
2534 tree type
= make_node (FIXED_POINT_TYPE
);
2536 TYPE_PRECISION (type
) = precision
;
2539 TYPE_SATURATING (type
) = 1;
2541 /* Lay out the type: set its alignment, size, etc. */
2544 TYPE_UNSIGNED (type
) = 1;
2545 SET_TYPE_MODE (type
, mode_for_size (precision
, MODE_UFRACT
, 0));
2548 SET_TYPE_MODE (type
, mode_for_size (precision
, MODE_FRACT
, 0));
2554 /* Create and return a type for accum of PRECISION bits, UNSIGNEDP,
2558 make_accum_type (int precision
, int unsignedp
, int satp
)
2560 tree type
= make_node (FIXED_POINT_TYPE
);
2562 TYPE_PRECISION (type
) = precision
;
2565 TYPE_SATURATING (type
) = 1;
2567 /* Lay out the type: set its alignment, size, etc. */
2570 TYPE_UNSIGNED (type
) = 1;
2571 SET_TYPE_MODE (type
, mode_for_size (precision
, MODE_UACCUM
, 0));
2574 SET_TYPE_MODE (type
, mode_for_size (precision
, MODE_ACCUM
, 0));
2580 /* Initialize sizetypes so layout_type can use them. */
2583 initialize_sizetypes (void)
2585 int precision
, bprecision
;
2587 /* Get sizetypes precision from the SIZE_TYPE target macro. */
2588 if (strcmp (SIZETYPE
, "unsigned int") == 0)
2589 precision
= INT_TYPE_SIZE
;
2590 else if (strcmp (SIZETYPE
, "long unsigned int") == 0)
2591 precision
= LONG_TYPE_SIZE
;
2592 else if (strcmp (SIZETYPE
, "long long unsigned int") == 0)
2593 precision
= LONG_LONG_TYPE_SIZE
;
2594 else if (strcmp (SIZETYPE
, "short unsigned int") == 0)
2595 precision
= SHORT_TYPE_SIZE
;
2601 for (i
= 0; i
< NUM_INT_N_ENTS
; i
++)
2602 if (int_n_enabled_p
[i
])
2605 sprintf (name
, "__int%d unsigned", int_n_data
[i
].bitsize
);
2607 if (strcmp (name
, SIZETYPE
) == 0)
2609 precision
= int_n_data
[i
].bitsize
;
2612 if (precision
== -1)
2617 = MIN (precision
+ BITS_PER_UNIT_LOG
+ 1, MAX_FIXED_MODE_SIZE
);
2619 = GET_MODE_PRECISION (smallest_mode_for_size (bprecision
, MODE_INT
));
2620 if (bprecision
> HOST_BITS_PER_DOUBLE_INT
)
2621 bprecision
= HOST_BITS_PER_DOUBLE_INT
;
2623 /* Create stubs for sizetype and bitsizetype so we can create constants. */
2624 sizetype
= make_node (INTEGER_TYPE
);
2625 TYPE_NAME (sizetype
) = get_identifier ("sizetype");
2626 TYPE_PRECISION (sizetype
) = precision
;
2627 TYPE_UNSIGNED (sizetype
) = 1;
2628 bitsizetype
= make_node (INTEGER_TYPE
);
2629 TYPE_NAME (bitsizetype
) = get_identifier ("bitsizetype");
2630 TYPE_PRECISION (bitsizetype
) = bprecision
;
2631 TYPE_UNSIGNED (bitsizetype
) = 1;
2633 /* Now layout both types manually. */
2634 SET_TYPE_MODE (sizetype
, smallest_mode_for_size (precision
, MODE_INT
));
2635 TYPE_ALIGN (sizetype
) = GET_MODE_ALIGNMENT (TYPE_MODE (sizetype
));
2636 TYPE_SIZE (sizetype
) = bitsize_int (precision
);
2637 TYPE_SIZE_UNIT (sizetype
) = size_int (GET_MODE_SIZE (TYPE_MODE (sizetype
)));
2638 set_min_and_max_values_for_integral_type (sizetype
, precision
, UNSIGNED
);
2640 SET_TYPE_MODE (bitsizetype
, smallest_mode_for_size (bprecision
, MODE_INT
));
2641 TYPE_ALIGN (bitsizetype
) = GET_MODE_ALIGNMENT (TYPE_MODE (bitsizetype
));
2642 TYPE_SIZE (bitsizetype
) = bitsize_int (bprecision
);
2643 TYPE_SIZE_UNIT (bitsizetype
)
2644 = size_int (GET_MODE_SIZE (TYPE_MODE (bitsizetype
)));
2645 set_min_and_max_values_for_integral_type (bitsizetype
, bprecision
, UNSIGNED
);
2647 /* Create the signed variants of *sizetype. */
2648 ssizetype
= make_signed_type (TYPE_PRECISION (sizetype
));
2649 TYPE_NAME (ssizetype
) = get_identifier ("ssizetype");
2650 sbitsizetype
= make_signed_type (TYPE_PRECISION (bitsizetype
));
2651 TYPE_NAME (sbitsizetype
) = get_identifier ("sbitsizetype");
2654 /* TYPE is an integral type, i.e., an INTEGRAL_TYPE, ENUMERAL_TYPE
2655 or BOOLEAN_TYPE. Set TYPE_MIN_VALUE and TYPE_MAX_VALUE
2656 for TYPE, based on the PRECISION and whether or not the TYPE
2657 IS_UNSIGNED. PRECISION need not correspond to a width supported
2658 natively by the hardware; for example, on a machine with 8-bit,
2659 16-bit, and 32-bit register modes, PRECISION might be 7, 23, or
2663 set_min_and_max_values_for_integral_type (tree type
,
2667 /* For bitfields with zero width we end up creating integer types
2668 with zero precision. Don't assign any minimum/maximum values
2669 to those types, they don't have any valid value. */
2673 TYPE_MIN_VALUE (type
)
2674 = wide_int_to_tree (type
, wi::min_value (precision
, sgn
));
2675 TYPE_MAX_VALUE (type
)
2676 = wide_int_to_tree (type
, wi::max_value (precision
, sgn
));
2679 /* Set the extreme values of TYPE based on its precision in bits,
2680 then lay it out. Used when make_signed_type won't do
2681 because the tree code is not INTEGER_TYPE.
2682 E.g. for Pascal, when the -fsigned-char option is given. */
2685 fixup_signed_type (tree type
)
2687 int precision
= TYPE_PRECISION (type
);
2689 set_min_and_max_values_for_integral_type (type
, precision
, SIGNED
);
2691 /* Lay out the type: set its alignment, size, etc. */
2695 /* Set the extreme values of TYPE based on its precision in bits,
2696 then lay it out. This is used both in `make_unsigned_type'
2697 and for enumeral types. */
2700 fixup_unsigned_type (tree type
)
2702 int precision
= TYPE_PRECISION (type
);
2704 TYPE_UNSIGNED (type
) = 1;
2706 set_min_and_max_values_for_integral_type (type
, precision
, UNSIGNED
);
2708 /* Lay out the type: set its alignment, size, etc. */
2712 /* Construct an iterator for a bitfield that spans BITSIZE bits,
2715 BITREGION_START is the bit position of the first bit in this
2716 sequence of bit fields. BITREGION_END is the last bit in this
2717 sequence. If these two fields are non-zero, we should restrict the
2718 memory access to that range. Otherwise, we are allowed to touch
2719 any adjacent non bit-fields.
2721 ALIGN is the alignment of the underlying object in bits.
2722 VOLATILEP says whether the bitfield is volatile. */
2724 bit_field_mode_iterator
2725 ::bit_field_mode_iterator (HOST_WIDE_INT bitsize
, HOST_WIDE_INT bitpos
,
2726 HOST_WIDE_INT bitregion_start
,
2727 HOST_WIDE_INT bitregion_end
,
2728 unsigned int align
, bool volatilep
)
2729 : m_mode (GET_CLASS_NARROWEST_MODE (MODE_INT
)), m_bitsize (bitsize
),
2730 m_bitpos (bitpos
), m_bitregion_start (bitregion_start
),
2731 m_bitregion_end (bitregion_end
), m_align (align
),
2732 m_volatilep (volatilep
), m_count (0)
2734 if (!m_bitregion_end
)
2736 /* We can assume that any aligned chunk of ALIGN bits that overlaps
2737 the bitfield is mapped and won't trap, provided that ALIGN isn't
2738 too large. The cap is the biggest required alignment for data,
2739 or at least the word size. And force one such chunk at least. */
2740 unsigned HOST_WIDE_INT units
2741 = MIN (align
, MAX (BIGGEST_ALIGNMENT
, BITS_PER_WORD
));
2744 m_bitregion_end
= bitpos
+ bitsize
+ units
- 1;
2745 m_bitregion_end
-= m_bitregion_end
% units
+ 1;
2749 /* Calls to this function return successively larger modes that can be used
2750 to represent the bitfield. Return true if another bitfield mode is
2751 available, storing it in *OUT_MODE if so. */
2754 bit_field_mode_iterator::next_mode (machine_mode
*out_mode
)
2756 for (; m_mode
!= VOIDmode
; m_mode
= GET_MODE_WIDER_MODE (m_mode
))
2758 unsigned int unit
= GET_MODE_BITSIZE (m_mode
);
2760 /* Skip modes that don't have full precision. */
2761 if (unit
!= GET_MODE_PRECISION (m_mode
))
2764 /* Stop if the mode is too wide to handle efficiently. */
2765 if (unit
> MAX_FIXED_MODE_SIZE
)
2768 /* Don't deliver more than one multiword mode; the smallest one
2770 if (m_count
> 0 && unit
> BITS_PER_WORD
)
2773 /* Skip modes that are too small. */
2774 unsigned HOST_WIDE_INT substart
= (unsigned HOST_WIDE_INT
) m_bitpos
% unit
;
2775 unsigned HOST_WIDE_INT subend
= substart
+ m_bitsize
;
2779 /* Stop if the mode goes outside the bitregion. */
2780 HOST_WIDE_INT start
= m_bitpos
- substart
;
2781 if (m_bitregion_start
&& start
< m_bitregion_start
)
2783 HOST_WIDE_INT end
= start
+ unit
;
2784 if (end
> m_bitregion_end
+ 1)
2787 /* Stop if the mode requires too much alignment. */
2788 if (GET_MODE_ALIGNMENT (m_mode
) > m_align
2789 && SLOW_UNALIGNED_ACCESS (m_mode
, m_align
))
2793 m_mode
= GET_MODE_WIDER_MODE (m_mode
);
2800 /* Return true if smaller modes are generally preferred for this kind
2804 bit_field_mode_iterator::prefer_smaller_modes ()
2807 ? targetm
.narrow_volatile_bitfield ()
2808 : !SLOW_BYTE_ACCESS
);
2811 /* Find the best machine mode to use when referencing a bit field of length
2812 BITSIZE bits starting at BITPOS.
2814 BITREGION_START is the bit position of the first bit in this
2815 sequence of bit fields. BITREGION_END is the last bit in this
2816 sequence. If these two fields are non-zero, we should restrict the
2817 memory access to that range. Otherwise, we are allowed to touch
2818 any adjacent non bit-fields.
2820 The underlying object is known to be aligned to a boundary of ALIGN bits.
2821 If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
2822 larger than LARGEST_MODE (usually SImode).
2824 If no mode meets all these conditions, we return VOIDmode.
2826 If VOLATILEP is false and SLOW_BYTE_ACCESS is false, we return the
2827 smallest mode meeting these conditions.
2829 If VOLATILEP is false and SLOW_BYTE_ACCESS is true, we return the
2830 largest mode (but a mode no wider than UNITS_PER_WORD) that meets
2833 If VOLATILEP is true the narrow_volatile_bitfields target hook is used to
2834 decide which of the above modes should be used. */
2837 get_best_mode (int bitsize
, int bitpos
,
2838 unsigned HOST_WIDE_INT bitregion_start
,
2839 unsigned HOST_WIDE_INT bitregion_end
,
2841 machine_mode largest_mode
, bool volatilep
)
2843 bit_field_mode_iterator
iter (bitsize
, bitpos
, bitregion_start
,
2844 bitregion_end
, align
, volatilep
);
2845 machine_mode widest_mode
= VOIDmode
;
2847 while (iter
.next_mode (&mode
)
2848 /* ??? For historical reasons, reject modes that would normally
2849 receive greater alignment, even if unaligned accesses are
2850 acceptable. This has both advantages and disadvantages.
2851 Removing this check means that something like:
2853 struct s { unsigned int x; unsigned int y; };
2854 int f (struct s *s) { return s->x == 0 && s->y == 0; }
2856 can be implemented using a single load and compare on
2857 64-bit machines that have no alignment restrictions.
2858 For example, on powerpc64-linux-gnu, we would generate:
2880 However, accessing more than one field can make life harder
2881 for the gimple optimizers. For example, gcc.dg/vect/bb-slp-5.c
2882 has a series of unsigned short copies followed by a series of
2883 unsigned short comparisons. With this check, both the copies
2884 and comparisons remain 16-bit accesses and FRE is able
2885 to eliminate the latter. Without the check, the comparisons
2886 can be done using 2 64-bit operations, which FRE isn't able
2887 to handle in the same way.
2889 Either way, it would probably be worth disabling this check
2890 during expand. One particular example where removing the
2891 check would help is the get_best_mode call in store_bit_field.
2892 If we are given a memory bitregion of 128 bits that is aligned
2893 to a 64-bit boundary, and the bitfield we want to modify is
2894 in the second half of the bitregion, this check causes
2895 store_bitfield to turn the memory into a 64-bit reference
2896 to the _first_ half of the region. We later use
2897 adjust_bitfield_address to get a reference to the correct half,
2898 but doing so looks to adjust_bitfield_address as though we are
2899 moving past the end of the original object, so it drops the
2900 associated MEM_EXPR and MEM_OFFSET. Removing the check
2901 causes store_bit_field to keep a 128-bit memory reference,
2902 so that the final bitfield reference still has a MEM_EXPR
2904 && GET_MODE_ALIGNMENT (mode
) <= align
2905 && (largest_mode
== VOIDmode
2906 || GET_MODE_SIZE (mode
) <= GET_MODE_SIZE (largest_mode
)))
2909 if (iter
.prefer_smaller_modes ())
2915 /* Gets minimal and maximal values for MODE (signed or unsigned depending on
2916 SIGN). The returned constants are made to be usable in TARGET_MODE. */
2919 get_mode_bounds (machine_mode mode
, int sign
,
2920 machine_mode target_mode
,
2921 rtx
*mmin
, rtx
*mmax
)
2923 unsigned size
= GET_MODE_PRECISION (mode
);
2924 unsigned HOST_WIDE_INT min_val
, max_val
;
2926 gcc_assert (size
<= HOST_BITS_PER_WIDE_INT
);
2928 /* Special case BImode, which has values 0 and STORE_FLAG_VALUE. */
2931 if (STORE_FLAG_VALUE
< 0)
2933 min_val
= STORE_FLAG_VALUE
;
2939 max_val
= STORE_FLAG_VALUE
;
2944 min_val
= -((unsigned HOST_WIDE_INT
) 1 << (size
- 1));
2945 max_val
= ((unsigned HOST_WIDE_INT
) 1 << (size
- 1)) - 1;
2950 max_val
= ((unsigned HOST_WIDE_INT
) 1 << (size
- 1) << 1) - 1;
2953 *mmin
= gen_int_mode (min_val
, target_mode
);
2954 *mmax
= gen_int_mode (max_val
, target_mode
);
2957 #include "gt-stor-layout.h"