1 /* C-compiler utilities for types and variables storage layout
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1996, 1998,
3 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
4 Free Software Foundation, Inc.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
25 #include "coretypes.h"
34 #include "diagnostic-core.h"
37 #include "langhooks.h"
41 #include "tree-inline.h"
42 #include "tree-dump.h"
45 /* Data type for the expressions representing sizes of data types.
46 It is the first integer type laid out. */
47 tree sizetype_tab[(int) TYPE_KIND_LAST];
49 /* If nonzero, this is an upper limit on alignment of structure fields.
50 The value is measured in bits. */
51 unsigned int maximum_field_alignment = TARGET_DEFAULT_PACK_STRUCT * BITS_PER_UNIT;
53 /* Nonzero if all REFERENCE_TYPEs are internal and hence should be allocated
54 in the address spaces' address_mode, not pointer_mode. Set only by
55 internal_reference_types called only by a front end. */
56 static int reference_types_internal = 0;
58 static tree self_referential_size (tree);
59 static void finalize_record_size (record_layout_info);
60 static void finalize_type_size (tree);
61 static void place_union_field (record_layout_info, tree);
62 #if defined (PCC_BITFIELD_TYPE_MATTERS) || defined (BITFIELD_NBYTES_LIMITED)
63 static int excess_unit_span (HOST_WIDE_INT, HOST_WIDE_INT, HOST_WIDE_INT,
66 extern void debug_rli (record_layout_info);
68 /* Show that REFERENCE_TYPES are internal and should use address_mode.
69 Called only by front end. */
72 internal_reference_types (void)
74 reference_types_internal = 1;
77 /* Given a size SIZE that may not be a constant, return a SAVE_EXPR
78 to serve as the actual size-expression for a type or decl. */
81 variable_size (tree size)
84 if (TREE_CONSTANT (size))
87 /* If the size is self-referential, we can't make a SAVE_EXPR (see
88 save_expr for the rationale). But we can do something else. */
89 if (CONTAINS_PLACEHOLDER_P (size))
90 return self_referential_size (size);
92 /* If the language-processor is to take responsibility for variable-sized
93 items (e.g., languages which have elaboration procedures like Ada),
94 just return SIZE unchanged. */
95 if (lang_hooks.decls.global_bindings_p () < 0)
98 return save_expr (size);
101 /* An array of functions used for self-referential size computation. */
102 static GTY(()) VEC (tree, gc) *size_functions;
104 /* Look inside EXPR into simple arithmetic operations involving constants.
105 Return the outermost non-arithmetic or non-constant node. */
108 skip_simple_constant_arithmetic (tree expr)
112 if (UNARY_CLASS_P (expr))
113 expr = TREE_OPERAND (expr, 0);
114 else if (BINARY_CLASS_P (expr))
116 if (TREE_CONSTANT (TREE_OPERAND (expr, 1)))
117 expr = TREE_OPERAND (expr, 0);
118 else if (TREE_CONSTANT (TREE_OPERAND (expr, 0)))
119 expr = TREE_OPERAND (expr, 1);
130 /* Similar to copy_tree_r but do not copy component references involving
131 PLACEHOLDER_EXPRs. These nodes are spotted in find_placeholder_in_expr
132 and substituted in substitute_in_expr. */
135 copy_self_referential_tree_r (tree *tp, int *walk_subtrees, void *data)
137 enum tree_code code = TREE_CODE (*tp);
139 /* Stop at types, decls, constants like copy_tree_r. */
140 if (TREE_CODE_CLASS (code) == tcc_type
141 || TREE_CODE_CLASS (code) == tcc_declaration
142 || TREE_CODE_CLASS (code) == tcc_constant)
148 /* This is the pattern built in ada/make_aligning_type. */
149 else if (code == ADDR_EXPR
150 && TREE_CODE (TREE_OPERAND (*tp, 0)) == PLACEHOLDER_EXPR)
156 /* Default case: the component reference. */
157 else if (code == COMPONENT_REF)
160 for (inner = TREE_OPERAND (*tp, 0);
161 REFERENCE_CLASS_P (inner);
162 inner = TREE_OPERAND (inner, 0))
165 if (TREE_CODE (inner) == PLACEHOLDER_EXPR)
172 /* We're not supposed to have them in self-referential size trees
173 because we wouldn't properly control when they are evaluated.
174 However, not creating superfluous SAVE_EXPRs requires accurate
175 tracking of readonly-ness all the way down to here, which we
176 cannot always guarantee in practice. So punt in this case. */
177 else if (code == SAVE_EXPR)
178 return error_mark_node;
180 return copy_tree_r (tp, walk_subtrees, data);
183 /* Given a SIZE expression that is self-referential, return an equivalent
184 expression to serve as the actual size expression for a type. */
187 self_referential_size (tree size)
189 static unsigned HOST_WIDE_INT fnno = 0;
190 VEC (tree, heap) *self_refs = NULL;
191 tree param_type_list = NULL, param_decl_list = NULL;
192 tree t, ref, return_type, fntype, fnname, fndecl;
195 VEC(tree,gc) *args = NULL;
197 /* Do not factor out simple operations. */
198 t = skip_simple_constant_arithmetic (size);
199 if (TREE_CODE (t) == CALL_EXPR)
202 /* Collect the list of self-references in the expression. */
203 find_placeholder_in_expr (size, &self_refs);
204 gcc_assert (VEC_length (tree, self_refs) > 0);
206 /* Obtain a private copy of the expression. */
208 if (walk_tree (&t, copy_self_referential_tree_r, NULL, NULL) != NULL_TREE)
212 /* Build the parameter and argument lists in parallel; also
213 substitute the former for the latter in the expression. */
214 args = VEC_alloc (tree, gc, VEC_length (tree, self_refs));
215 FOR_EACH_VEC_ELT (tree, self_refs, i, ref)
217 tree subst, param_name, param_type, param_decl;
221 /* We shouldn't have true variables here. */
222 gcc_assert (TREE_READONLY (ref));
225 /* This is the pattern built in ada/make_aligning_type. */
226 else if (TREE_CODE (ref) == ADDR_EXPR)
228 /* Default case: the component reference. */
230 subst = TREE_OPERAND (ref, 1);
232 sprintf (buf, "p%d", i);
233 param_name = get_identifier (buf);
234 param_type = TREE_TYPE (ref);
236 = build_decl (input_location, PARM_DECL, param_name, param_type);
237 if (targetm.calls.promote_prototypes (NULL_TREE)
238 && INTEGRAL_TYPE_P (param_type)
239 && TYPE_PRECISION (param_type) < TYPE_PRECISION (integer_type_node))
240 DECL_ARG_TYPE (param_decl) = integer_type_node;
242 DECL_ARG_TYPE (param_decl) = param_type;
243 DECL_ARTIFICIAL (param_decl) = 1;
244 TREE_READONLY (param_decl) = 1;
246 size = substitute_in_expr (size, subst, param_decl);
248 param_type_list = tree_cons (NULL_TREE, param_type, param_type_list);
249 param_decl_list = chainon (param_decl, param_decl_list);
250 VEC_quick_push (tree, args, ref);
253 VEC_free (tree, heap, self_refs);
255 /* Append 'void' to indicate that the number of parameters is fixed. */
256 param_type_list = tree_cons (NULL_TREE, void_type_node, param_type_list);
258 /* The 3 lists have been created in reverse order. */
259 param_type_list = nreverse (param_type_list);
260 param_decl_list = nreverse (param_decl_list);
262 /* Build the function type. */
263 return_type = TREE_TYPE (size);
264 fntype = build_function_type (return_type, param_type_list);
266 /* Build the function declaration. */
267 sprintf (buf, "SZ"HOST_WIDE_INT_PRINT_UNSIGNED, fnno++);
268 fnname = get_file_function_name (buf);
269 fndecl = build_decl (input_location, FUNCTION_DECL, fnname, fntype);
270 for (t = param_decl_list; t; t = DECL_CHAIN (t))
271 DECL_CONTEXT (t) = fndecl;
272 DECL_ARGUMENTS (fndecl) = param_decl_list;
274 = build_decl (input_location, RESULT_DECL, 0, return_type);
275 DECL_CONTEXT (DECL_RESULT (fndecl)) = fndecl;
277 /* The function has been created by the compiler and we don't
278 want to emit debug info for it. */
279 DECL_ARTIFICIAL (fndecl) = 1;
280 DECL_IGNORED_P (fndecl) = 1;
282 /* It is supposed to be "const" and never throw. */
283 TREE_READONLY (fndecl) = 1;
284 TREE_NOTHROW (fndecl) = 1;
286 /* We want it to be inlined when this is deemed profitable, as
287 well as discarded if every call has been integrated. */
288 DECL_DECLARED_INLINE_P (fndecl) = 1;
290 /* It is made up of a unique return statement. */
291 DECL_INITIAL (fndecl) = make_node (BLOCK);
292 BLOCK_SUPERCONTEXT (DECL_INITIAL (fndecl)) = fndecl;
293 t = build2 (MODIFY_EXPR, return_type, DECL_RESULT (fndecl), size);
294 DECL_SAVED_TREE (fndecl) = build1 (RETURN_EXPR, void_type_node, t);
295 TREE_STATIC (fndecl) = 1;
297 /* Put it onto the list of size functions. */
298 VEC_safe_push (tree, gc, size_functions, fndecl);
300 /* Replace the original expression with a call to the size function. */
301 return build_call_expr_loc_vec (UNKNOWN_LOCATION, fndecl, args);
304 /* Take, queue and compile all the size functions. It is essential that
305 the size functions be gimplified at the very end of the compilation
306 in order to guarantee transparent handling of self-referential sizes.
307 Otherwise the GENERIC inliner would not be able to inline them back
308 at each of their call sites, thus creating artificial non-constant
309 size expressions which would trigger nasty problems later on. */
312 finalize_size_functions (void)
317 for (i = 0; VEC_iterate(tree, size_functions, i, fndecl); i++)
319 dump_function (TDI_original, fndecl);
320 gimplify_function_tree (fndecl);
321 dump_function (TDI_generic, fndecl);
322 cgraph_finalize_function (fndecl, false);
325 VEC_free (tree, gc, size_functions);
328 /* Return the machine mode to use for a nonscalar of SIZE bits. The
329 mode must be in class MCLASS, and have exactly that many value bits;
330 it may have padding as well. If LIMIT is nonzero, modes of wider
331 than MAX_FIXED_MODE_SIZE will not be used. */
334 mode_for_size (unsigned int size, enum mode_class mclass, int limit)
336 enum machine_mode mode;
338 if (limit && size > MAX_FIXED_MODE_SIZE)
341 /* Get the first mode which has this size, in the specified class. */
342 for (mode = GET_CLASS_NARROWEST_MODE (mclass); mode != VOIDmode;
343 mode = GET_MODE_WIDER_MODE (mode))
344 if (GET_MODE_PRECISION (mode) == size)
350 /* Similar, except passed a tree node. */
353 mode_for_size_tree (const_tree size, enum mode_class mclass, int limit)
355 unsigned HOST_WIDE_INT uhwi;
358 if (!host_integerp (size, 1))
360 uhwi = tree_low_cst (size, 1);
364 return mode_for_size (ui, mclass, limit);
367 /* Similar, but never return BLKmode; return the narrowest mode that
368 contains at least the requested number of value bits. */
371 smallest_mode_for_size (unsigned int size, enum mode_class mclass)
373 enum machine_mode mode;
375 /* Get the first mode which has at least this size, in the
377 for (mode = GET_CLASS_NARROWEST_MODE (mclass); mode != VOIDmode;
378 mode = GET_MODE_WIDER_MODE (mode))
379 if (GET_MODE_PRECISION (mode) >= size)
385 /* Find an integer mode of the exact same size, or BLKmode on failure. */
388 int_mode_for_mode (enum machine_mode mode)
390 switch (GET_MODE_CLASS (mode))
393 case MODE_PARTIAL_INT:
396 case MODE_COMPLEX_INT:
397 case MODE_COMPLEX_FLOAT:
399 case MODE_DECIMAL_FLOAT:
400 case MODE_VECTOR_INT:
401 case MODE_VECTOR_FLOAT:
406 case MODE_VECTOR_FRACT:
407 case MODE_VECTOR_ACCUM:
408 case MODE_VECTOR_UFRACT:
409 case MODE_VECTOR_UACCUM:
410 mode = mode_for_size (GET_MODE_BITSIZE (mode), MODE_INT, 0);
417 /* ... fall through ... */
427 /* Find a mode that is suitable for representing a vector with
428 NUNITS elements of mode INNERMODE. Returns BLKmode if there
429 is no suitable mode. */
432 mode_for_vector (enum machine_mode innermode, unsigned nunits)
434 enum machine_mode mode;
436 /* First, look for a supported vector type. */
437 if (SCALAR_FLOAT_MODE_P (innermode))
438 mode = MIN_MODE_VECTOR_FLOAT;
439 else if (SCALAR_FRACT_MODE_P (innermode))
440 mode = MIN_MODE_VECTOR_FRACT;
441 else if (SCALAR_UFRACT_MODE_P (innermode))
442 mode = MIN_MODE_VECTOR_UFRACT;
443 else if (SCALAR_ACCUM_MODE_P (innermode))
444 mode = MIN_MODE_VECTOR_ACCUM;
445 else if (SCALAR_UACCUM_MODE_P (innermode))
446 mode = MIN_MODE_VECTOR_UACCUM;
448 mode = MIN_MODE_VECTOR_INT;
450 /* Do not check vector_mode_supported_p here. We'll do that
451 later in vector_type_mode. */
452 for (; mode != VOIDmode ; mode = GET_MODE_WIDER_MODE (mode))
453 if (GET_MODE_NUNITS (mode) == nunits
454 && GET_MODE_INNER (mode) == innermode)
457 /* For integers, try mapping it to a same-sized scalar mode. */
459 && GET_MODE_CLASS (innermode) == MODE_INT)
460 mode = mode_for_size (nunits * GET_MODE_BITSIZE (innermode),
464 || (GET_MODE_CLASS (mode) == MODE_INT
465 && !have_regs_of_mode[mode]))
471 /* Return the alignment of MODE. This will be bounded by 1 and
472 BIGGEST_ALIGNMENT. */
475 get_mode_alignment (enum machine_mode mode)
477 return MIN (BIGGEST_ALIGNMENT, MAX (1, mode_base_align[mode]*BITS_PER_UNIT));
480 /* Return the natural mode of an array, given that it is SIZE bytes in
481 total and has elements of type ELEM_TYPE. */
483 static enum machine_mode
484 mode_for_array (tree elem_type, tree size)
487 unsigned HOST_WIDE_INT int_size, int_elem_size;
490 /* One-element arrays get the component type's mode. */
491 elem_size = TYPE_SIZE (elem_type);
492 if (simple_cst_equal (size, elem_size))
493 return TYPE_MODE (elem_type);
496 if (host_integerp (size, 1) && host_integerp (elem_size, 1))
498 int_size = tree_low_cst (size, 1);
499 int_elem_size = tree_low_cst (elem_size, 1);
500 if (int_elem_size > 0
501 && int_size % int_elem_size == 0
502 && targetm.array_mode_supported_p (TYPE_MODE (elem_type),
503 int_size / int_elem_size))
506 return mode_for_size_tree (size, MODE_INT, limit_p);
509 /* Subroutine of layout_decl: Force alignment required for the data type.
510 But if the decl itself wants greater alignment, don't override that. */
513 do_type_align (tree type, tree decl)
515 if (TYPE_ALIGN (type) > DECL_ALIGN (decl))
517 DECL_ALIGN (decl) = TYPE_ALIGN (type);
518 if (TREE_CODE (decl) == FIELD_DECL)
519 DECL_USER_ALIGN (decl) = TYPE_USER_ALIGN (type);
523 /* Set the size, mode and alignment of a ..._DECL node.
524 TYPE_DECL does need this for C++.
525 Note that LABEL_DECL and CONST_DECL nodes do not need this,
526 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
527 Don't call layout_decl for them.
529 KNOWN_ALIGN is the amount of alignment we can assume this
530 decl has with no special effort. It is relevant only for FIELD_DECLs
531 and depends on the previous fields.
532 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
533 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
534 the record will be aligned to suit. */
537 layout_decl (tree decl, unsigned int known_align)
539 tree type = TREE_TYPE (decl);
540 enum tree_code code = TREE_CODE (decl);
542 location_t loc = DECL_SOURCE_LOCATION (decl);
544 if (code == CONST_DECL)
547 gcc_assert (code == VAR_DECL || code == PARM_DECL || code == RESULT_DECL
548 || code == TYPE_DECL ||code == FIELD_DECL);
550 rtl = DECL_RTL_IF_SET (decl);
552 if (type == error_mark_node)
553 type = void_type_node;
555 /* Usually the size and mode come from the data type without change,
556 however, the front-end may set the explicit width of the field, so its
557 size may not be the same as the size of its type. This happens with
558 bitfields, of course (an `int' bitfield may be only 2 bits, say), but it
559 also happens with other fields. For example, the C++ front-end creates
560 zero-sized fields corresponding to empty base classes, and depends on
561 layout_type setting DECL_FIELD_BITPOS correctly for the field. Set the
562 size in bytes from the size in bits. If we have already set the mode,
563 don't set it again since we can be called twice for FIELD_DECLs. */
565 DECL_UNSIGNED (decl) = TYPE_UNSIGNED (type);
566 if (DECL_MODE (decl) == VOIDmode)
567 DECL_MODE (decl) = TYPE_MODE (type);
569 if (DECL_SIZE (decl) == 0)
571 DECL_SIZE (decl) = TYPE_SIZE (type);
572 DECL_SIZE_UNIT (decl) = TYPE_SIZE_UNIT (type);
574 else if (DECL_SIZE_UNIT (decl) == 0)
575 DECL_SIZE_UNIT (decl)
576 = fold_convert_loc (loc, sizetype,
577 size_binop_loc (loc, CEIL_DIV_EXPR, DECL_SIZE (decl),
580 if (code != FIELD_DECL)
581 /* For non-fields, update the alignment from the type. */
582 do_type_align (type, decl);
584 /* For fields, it's a bit more complicated... */
586 bool old_user_align = DECL_USER_ALIGN (decl);
587 bool zero_bitfield = false;
588 bool packed_p = DECL_PACKED (decl);
591 if (DECL_BIT_FIELD (decl))
593 DECL_BIT_FIELD_TYPE (decl) = type;
595 /* A zero-length bit-field affects the alignment of the next
596 field. In essence such bit-fields are not influenced by
597 any packing due to #pragma pack or attribute packed. */
598 if (integer_zerop (DECL_SIZE (decl))
599 && ! targetm.ms_bitfield_layout_p (DECL_FIELD_CONTEXT (decl)))
601 zero_bitfield = true;
603 #ifdef PCC_BITFIELD_TYPE_MATTERS
604 if (PCC_BITFIELD_TYPE_MATTERS)
605 do_type_align (type, decl);
609 #ifdef EMPTY_FIELD_BOUNDARY
610 if (EMPTY_FIELD_BOUNDARY > DECL_ALIGN (decl))
612 DECL_ALIGN (decl) = EMPTY_FIELD_BOUNDARY;
613 DECL_USER_ALIGN (decl) = 0;
619 /* See if we can use an ordinary integer mode for a bit-field.
620 Conditions are: a fixed size that is correct for another mode,
621 occupying a complete byte or bytes on proper boundary,
622 and not volatile or not -fstrict-volatile-bitfields. */
623 if (TYPE_SIZE (type) != 0
624 && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
625 && GET_MODE_CLASS (TYPE_MODE (type)) == MODE_INT
626 && !(TREE_THIS_VOLATILE (decl)
627 && flag_strict_volatile_bitfields > 0))
629 enum machine_mode xmode
630 = mode_for_size_tree (DECL_SIZE (decl), MODE_INT, 1);
631 unsigned int xalign = GET_MODE_ALIGNMENT (xmode);
634 && !(xalign > BITS_PER_UNIT && DECL_PACKED (decl))
635 && (known_align == 0 || known_align >= xalign))
637 DECL_ALIGN (decl) = MAX (xalign, DECL_ALIGN (decl));
638 DECL_MODE (decl) = xmode;
639 DECL_BIT_FIELD (decl) = 0;
643 /* Turn off DECL_BIT_FIELD if we won't need it set. */
644 if (TYPE_MODE (type) == BLKmode && DECL_MODE (decl) == BLKmode
645 && known_align >= TYPE_ALIGN (type)
646 && DECL_ALIGN (decl) >= TYPE_ALIGN (type))
647 DECL_BIT_FIELD (decl) = 0;
649 else if (packed_p && DECL_USER_ALIGN (decl))
650 /* Don't touch DECL_ALIGN. For other packed fields, go ahead and
651 round up; we'll reduce it again below. We want packing to
652 supersede USER_ALIGN inherited from the type, but defer to
653 alignment explicitly specified on the field decl. */;
655 do_type_align (type, decl);
657 /* If the field is packed and not explicitly aligned, give it the
658 minimum alignment. Note that do_type_align may set
659 DECL_USER_ALIGN, so we need to check old_user_align instead. */
662 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), BITS_PER_UNIT);
664 if (! packed_p && ! DECL_USER_ALIGN (decl))
666 /* Some targets (i.e. i386, VMS) limit struct field alignment
667 to a lower boundary than alignment of variables unless
668 it was overridden by attribute aligned. */
669 #ifdef BIGGEST_FIELD_ALIGNMENT
671 = MIN (DECL_ALIGN (decl), (unsigned) BIGGEST_FIELD_ALIGNMENT);
673 #ifdef ADJUST_FIELD_ALIGN
674 DECL_ALIGN (decl) = ADJUST_FIELD_ALIGN (decl, DECL_ALIGN (decl));
679 mfa = initial_max_fld_align * BITS_PER_UNIT;
681 mfa = maximum_field_alignment;
682 /* Should this be controlled by DECL_USER_ALIGN, too? */
684 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), mfa);
687 /* Evaluate nonconstant size only once, either now or as soon as safe. */
688 if (DECL_SIZE (decl) != 0 && TREE_CODE (DECL_SIZE (decl)) != INTEGER_CST)
689 DECL_SIZE (decl) = variable_size (DECL_SIZE (decl));
690 if (DECL_SIZE_UNIT (decl) != 0
691 && TREE_CODE (DECL_SIZE_UNIT (decl)) != INTEGER_CST)
692 DECL_SIZE_UNIT (decl) = variable_size (DECL_SIZE_UNIT (decl));
694 /* If requested, warn about definitions of large data objects. */
696 && (code == VAR_DECL || code == PARM_DECL)
697 && ! DECL_EXTERNAL (decl))
699 tree size = DECL_SIZE_UNIT (decl);
701 if (size != 0 && TREE_CODE (size) == INTEGER_CST
702 && compare_tree_int (size, larger_than_size) > 0)
704 int size_as_int = TREE_INT_CST_LOW (size);
706 if (compare_tree_int (size, size_as_int) == 0)
707 warning (OPT_Wlarger_than_, "size of %q+D is %d bytes", decl, size_as_int);
709 warning (OPT_Wlarger_than_, "size of %q+D is larger than %wd bytes",
710 decl, larger_than_size);
714 /* If the RTL was already set, update its mode and mem attributes. */
717 PUT_MODE (rtl, DECL_MODE (decl));
718 SET_DECL_RTL (decl, 0);
719 set_mem_attributes (rtl, decl, 1);
720 SET_DECL_RTL (decl, rtl);
724 /* Given a VAR_DECL, PARM_DECL or RESULT_DECL, clears the results of
725 a previous call to layout_decl and calls it again. */
728 relayout_decl (tree decl)
730 DECL_SIZE (decl) = DECL_SIZE_UNIT (decl) = 0;
731 DECL_MODE (decl) = VOIDmode;
732 if (!DECL_USER_ALIGN (decl))
733 DECL_ALIGN (decl) = 0;
734 SET_DECL_RTL (decl, 0);
736 layout_decl (decl, 0);
739 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
740 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
741 is to be passed to all other layout functions for this record. It is the
742 responsibility of the caller to call `free' for the storage returned.
743 Note that garbage collection is not permitted until we finish laying
747 start_record_layout (tree t)
749 record_layout_info rli = XNEW (struct record_layout_info_s);
753 /* If the type has a minimum specified alignment (via an attribute
754 declaration, for example) use it -- otherwise, start with a
755 one-byte alignment. */
756 rli->record_align = MAX (BITS_PER_UNIT, TYPE_ALIGN (t));
757 rli->unpacked_align = rli->record_align;
758 rli->offset_align = MAX (rli->record_align, BIGGEST_ALIGNMENT);
760 #ifdef STRUCTURE_SIZE_BOUNDARY
761 /* Packed structures don't need to have minimum size. */
762 if (! TYPE_PACKED (t))
766 /* #pragma pack overrides STRUCTURE_SIZE_BOUNDARY. */
767 tmp = (unsigned) STRUCTURE_SIZE_BOUNDARY;
768 if (maximum_field_alignment != 0)
769 tmp = MIN (tmp, maximum_field_alignment);
770 rli->record_align = MAX (rli->record_align, tmp);
774 rli->offset = size_zero_node;
775 rli->bitpos = bitsize_zero_node;
777 rli->pending_statics = NULL;
778 rli->packed_maybe_necessary = 0;
779 rli->remaining_in_alignment = 0;
784 /* These four routines perform computations that convert between
785 the offset/bitpos forms and byte and bit offsets. */
788 bit_from_pos (tree offset, tree bitpos)
790 return size_binop (PLUS_EXPR, bitpos,
791 size_binop (MULT_EXPR,
792 fold_convert (bitsizetype, offset),
797 byte_from_pos (tree offset, tree bitpos)
799 return size_binop (PLUS_EXPR, offset,
800 fold_convert (sizetype,
801 size_binop (TRUNC_DIV_EXPR, bitpos,
802 bitsize_unit_node)));
806 pos_from_bit (tree *poffset, tree *pbitpos, unsigned int off_align,
809 *poffset = size_binop (MULT_EXPR,
810 fold_convert (sizetype,
811 size_binop (FLOOR_DIV_EXPR, pos,
812 bitsize_int (off_align))),
813 size_int (off_align / BITS_PER_UNIT));
814 *pbitpos = size_binop (FLOOR_MOD_EXPR, pos, bitsize_int (off_align));
817 /* Given a pointer to bit and byte offsets and an offset alignment,
818 normalize the offsets so they are within the alignment. */
821 normalize_offset (tree *poffset, tree *pbitpos, unsigned int off_align)
823 /* If the bit position is now larger than it should be, adjust it
825 if (compare_tree_int (*pbitpos, off_align) >= 0)
827 tree extra_aligns = size_binop (FLOOR_DIV_EXPR, *pbitpos,
828 bitsize_int (off_align));
831 = size_binop (PLUS_EXPR, *poffset,
832 size_binop (MULT_EXPR,
833 fold_convert (sizetype, extra_aligns),
834 size_int (off_align / BITS_PER_UNIT)));
837 = size_binop (FLOOR_MOD_EXPR, *pbitpos, bitsize_int (off_align));
841 /* Print debugging information about the information in RLI. */
844 debug_rli (record_layout_info rli)
846 print_node_brief (stderr, "type", rli->t, 0);
847 print_node_brief (stderr, "\noffset", rli->offset, 0);
848 print_node_brief (stderr, " bitpos", rli->bitpos, 0);
850 fprintf (stderr, "\naligns: rec = %u, unpack = %u, off = %u\n",
851 rli->record_align, rli->unpacked_align,
854 /* The ms_struct code is the only that uses this. */
855 if (targetm.ms_bitfield_layout_p (rli->t))
856 fprintf (stderr, "remaining in alignment = %u\n", rli->remaining_in_alignment);
858 if (rli->packed_maybe_necessary)
859 fprintf (stderr, "packed may be necessary\n");
861 if (!VEC_empty (tree, rli->pending_statics))
863 fprintf (stderr, "pending statics:\n");
864 debug_vec_tree (rli->pending_statics);
868 /* Given an RLI with a possibly-incremented BITPOS, adjust OFFSET and
869 BITPOS if necessary to keep BITPOS below OFFSET_ALIGN. */
872 normalize_rli (record_layout_info rli)
874 normalize_offset (&rli->offset, &rli->bitpos, rli->offset_align);
877 /* Returns the size in bytes allocated so far. */
880 rli_size_unit_so_far (record_layout_info rli)
882 return byte_from_pos (rli->offset, rli->bitpos);
885 /* Returns the size in bits allocated so far. */
888 rli_size_so_far (record_layout_info rli)
890 return bit_from_pos (rli->offset, rli->bitpos);
893 /* FIELD is about to be added to RLI->T. The alignment (in bits) of
894 the next available location within the record is given by KNOWN_ALIGN.
895 Update the variable alignment fields in RLI, and return the alignment
896 to give the FIELD. */
899 update_alignment_for_field (record_layout_info rli, tree field,
900 unsigned int known_align)
902 /* The alignment required for FIELD. */
903 unsigned int desired_align;
904 /* The type of this field. */
905 tree type = TREE_TYPE (field);
906 /* True if the field was explicitly aligned by the user. */
910 /* Do not attempt to align an ERROR_MARK node */
911 if (TREE_CODE (type) == ERROR_MARK)
914 /* Lay out the field so we know what alignment it needs. */
915 layout_decl (field, known_align);
916 desired_align = DECL_ALIGN (field);
917 user_align = DECL_USER_ALIGN (field);
919 is_bitfield = (type != error_mark_node
920 && DECL_BIT_FIELD_TYPE (field)
921 && ! integer_zerop (TYPE_SIZE (type)));
923 /* Record must have at least as much alignment as any field.
924 Otherwise, the alignment of the field within the record is
926 if (targetm.ms_bitfield_layout_p (rli->t))
928 /* Here, the alignment of the underlying type of a bitfield can
929 affect the alignment of a record; even a zero-sized field
930 can do this. The alignment should be to the alignment of
931 the type, except that for zero-size bitfields this only
932 applies if there was an immediately prior, nonzero-size
933 bitfield. (That's the way it is, experimentally.) */
934 if ((!is_bitfield && !DECL_PACKED (field))
935 || (!integer_zerop (DECL_SIZE (field))
936 ? !DECL_PACKED (field)
938 && DECL_BIT_FIELD_TYPE (rli->prev_field)
939 && ! integer_zerop (DECL_SIZE (rli->prev_field)))))
941 unsigned int type_align = TYPE_ALIGN (type);
942 type_align = MAX (type_align, desired_align);
943 if (maximum_field_alignment != 0)
944 type_align = MIN (type_align, maximum_field_alignment);
945 rli->record_align = MAX (rli->record_align, type_align);
946 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
949 #ifdef PCC_BITFIELD_TYPE_MATTERS
950 else if (is_bitfield && PCC_BITFIELD_TYPE_MATTERS)
952 /* Named bit-fields cause the entire structure to have the
953 alignment implied by their type. Some targets also apply the same
954 rules to unnamed bitfields. */
955 if (DECL_NAME (field) != 0
956 || targetm.align_anon_bitfield ())
958 unsigned int type_align = TYPE_ALIGN (type);
960 #ifdef ADJUST_FIELD_ALIGN
961 if (! TYPE_USER_ALIGN (type))
962 type_align = ADJUST_FIELD_ALIGN (field, type_align);
965 /* Targets might chose to handle unnamed and hence possibly
966 zero-width bitfield. Those are not influenced by #pragmas
967 or packed attributes. */
968 if (integer_zerop (DECL_SIZE (field)))
970 if (initial_max_fld_align)
971 type_align = MIN (type_align,
972 initial_max_fld_align * BITS_PER_UNIT);
974 else if (maximum_field_alignment != 0)
975 type_align = MIN (type_align, maximum_field_alignment);
976 else if (DECL_PACKED (field))
977 type_align = MIN (type_align, BITS_PER_UNIT);
979 /* The alignment of the record is increased to the maximum
980 of the current alignment, the alignment indicated on the
981 field (i.e., the alignment specified by an __aligned__
982 attribute), and the alignment indicated by the type of
984 rli->record_align = MAX (rli->record_align, desired_align);
985 rli->record_align = MAX (rli->record_align, type_align);
988 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
989 user_align |= TYPE_USER_ALIGN (type);
995 rli->record_align = MAX (rli->record_align, desired_align);
996 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
999 TYPE_USER_ALIGN (rli->t) |= user_align;
1001 return desired_align;
1004 /* Called from place_field to handle unions. */
1007 place_union_field (record_layout_info rli, tree field)
1009 update_alignment_for_field (rli, field, /*known_align=*/0);
1011 DECL_FIELD_OFFSET (field) = size_zero_node;
1012 DECL_FIELD_BIT_OFFSET (field) = bitsize_zero_node;
1013 SET_DECL_OFFSET_ALIGN (field, BIGGEST_ALIGNMENT);
1015 /* If this is an ERROR_MARK return *after* having set the
1016 field at the start of the union. This helps when parsing
1018 if (TREE_CODE (TREE_TYPE (field)) == ERROR_MARK)
1021 /* We assume the union's size will be a multiple of a byte so we don't
1022 bother with BITPOS. */
1023 if (TREE_CODE (rli->t) == UNION_TYPE)
1024 rli->offset = size_binop (MAX_EXPR, rli->offset, DECL_SIZE_UNIT (field));
1025 else if (TREE_CODE (rli->t) == QUAL_UNION_TYPE)
1026 rli->offset = fold_build3 (COND_EXPR, sizetype, DECL_QUALIFIER (field),
1027 DECL_SIZE_UNIT (field), rli->offset);
1030 #if defined (PCC_BITFIELD_TYPE_MATTERS) || defined (BITFIELD_NBYTES_LIMITED)
1031 /* A bitfield of SIZE with a required access alignment of ALIGN is allocated
1032 at BYTE_OFFSET / BIT_OFFSET. Return nonzero if the field would span more
1033 units of alignment than the underlying TYPE. */
1035 excess_unit_span (HOST_WIDE_INT byte_offset, HOST_WIDE_INT bit_offset,
1036 HOST_WIDE_INT size, HOST_WIDE_INT align, tree type)
1038 /* Note that the calculation of OFFSET might overflow; we calculate it so
1039 that we still get the right result as long as ALIGN is a power of two. */
1040 unsigned HOST_WIDE_INT offset = byte_offset * BITS_PER_UNIT + bit_offset;
1042 offset = offset % align;
1043 return ((offset + size + align - 1) / align
1044 > ((unsigned HOST_WIDE_INT) tree_low_cst (TYPE_SIZE (type), 1)
1049 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
1050 is a FIELD_DECL to be added after those fields already present in
1051 T. (FIELD is not actually added to the TYPE_FIELDS list here;
1052 callers that desire that behavior must manually perform that step.) */
1055 place_field (record_layout_info rli, tree field)
1057 /* The alignment required for FIELD. */
1058 unsigned int desired_align;
1059 /* The alignment FIELD would have if we just dropped it into the
1060 record as it presently stands. */
1061 unsigned int known_align;
1062 unsigned int actual_align;
1063 /* The type of this field. */
1064 tree type = TREE_TYPE (field);
1066 gcc_assert (TREE_CODE (field) != ERROR_MARK);
1068 /* If FIELD is static, then treat it like a separate variable, not
1069 really like a structure field. If it is a FUNCTION_DECL, it's a
1070 method. In both cases, all we do is lay out the decl, and we do
1071 it *after* the record is laid out. */
1072 if (TREE_CODE (field) == VAR_DECL)
1074 VEC_safe_push (tree, gc, rli->pending_statics, field);
1078 /* Enumerators and enum types which are local to this class need not
1079 be laid out. Likewise for initialized constant fields. */
1080 else if (TREE_CODE (field) != FIELD_DECL)
1083 /* Unions are laid out very differently than records, so split
1084 that code off to another function. */
1085 else if (TREE_CODE (rli->t) != RECORD_TYPE)
1087 place_union_field (rli, field);
1091 else if (TREE_CODE (type) == ERROR_MARK)
1093 /* Place this field at the current allocation position, so we
1094 maintain monotonicity. */
1095 DECL_FIELD_OFFSET (field) = rli->offset;
1096 DECL_FIELD_BIT_OFFSET (field) = rli->bitpos;
1097 SET_DECL_OFFSET_ALIGN (field, rli->offset_align);
1101 /* Work out the known alignment so far. Note that A & (-A) is the
1102 value of the least-significant bit in A that is one. */
1103 if (! integer_zerop (rli->bitpos))
1104 known_align = (tree_low_cst (rli->bitpos, 1)
1105 & - tree_low_cst (rli->bitpos, 1));
1106 else if (integer_zerop (rli->offset))
1108 else if (host_integerp (rli->offset, 1))
1109 known_align = (BITS_PER_UNIT
1110 * (tree_low_cst (rli->offset, 1)
1111 & - tree_low_cst (rli->offset, 1)));
1113 known_align = rli->offset_align;
1115 desired_align = update_alignment_for_field (rli, field, known_align);
1116 if (known_align == 0)
1117 known_align = MAX (BIGGEST_ALIGNMENT, rli->record_align);
1119 if (warn_packed && DECL_PACKED (field))
1121 if (known_align >= TYPE_ALIGN (type))
1123 if (TYPE_ALIGN (type) > desired_align)
1125 if (STRICT_ALIGNMENT)
1126 warning (OPT_Wattributes, "packed attribute causes "
1127 "inefficient alignment for %q+D", field);
1128 /* Don't warn if DECL_PACKED was set by the type. */
1129 else if (!TYPE_PACKED (rli->t))
1130 warning (OPT_Wattributes, "packed attribute is "
1131 "unnecessary for %q+D", field);
1135 rli->packed_maybe_necessary = 1;
1138 /* Does this field automatically have alignment it needs by virtue
1139 of the fields that precede it and the record's own alignment?
1140 We already align ms_struct fields, so don't re-align them. */
1141 if (known_align < desired_align
1142 && !targetm.ms_bitfield_layout_p (rli->t))
1144 /* No, we need to skip space before this field.
1145 Bump the cumulative size to multiple of field alignment. */
1147 if (DECL_SOURCE_LOCATION (field) != BUILTINS_LOCATION)
1148 warning (OPT_Wpadded, "padding struct to align %q+D", field);
1150 /* If the alignment is still within offset_align, just align
1151 the bit position. */
1152 if (desired_align < rli->offset_align)
1153 rli->bitpos = round_up (rli->bitpos, desired_align);
1156 /* First adjust OFFSET by the partial bits, then align. */
1158 = size_binop (PLUS_EXPR, rli->offset,
1159 fold_convert (sizetype,
1160 size_binop (CEIL_DIV_EXPR, rli->bitpos,
1161 bitsize_unit_node)));
1162 rli->bitpos = bitsize_zero_node;
1164 rli->offset = round_up (rli->offset, desired_align / BITS_PER_UNIT);
1167 if (! TREE_CONSTANT (rli->offset))
1168 rli->offset_align = desired_align;
1172 /* Handle compatibility with PCC. Note that if the record has any
1173 variable-sized fields, we need not worry about compatibility. */
1174 #ifdef PCC_BITFIELD_TYPE_MATTERS
1175 if (PCC_BITFIELD_TYPE_MATTERS
1176 && ! targetm.ms_bitfield_layout_p (rli->t)
1177 && TREE_CODE (field) == FIELD_DECL
1178 && type != error_mark_node
1179 && DECL_BIT_FIELD (field)
1180 && (! DECL_PACKED (field)
1181 /* Enter for these packed fields only to issue a warning. */
1182 || TYPE_ALIGN (type) <= BITS_PER_UNIT)
1183 && maximum_field_alignment == 0
1184 && ! integer_zerop (DECL_SIZE (field))
1185 && host_integerp (DECL_SIZE (field), 1)
1186 && host_integerp (rli->offset, 1)
1187 && host_integerp (TYPE_SIZE (type), 1))
1189 unsigned int type_align = TYPE_ALIGN (type);
1190 tree dsize = DECL_SIZE (field);
1191 HOST_WIDE_INT field_size = tree_low_cst (dsize, 1);
1192 HOST_WIDE_INT offset = tree_low_cst (rli->offset, 0);
1193 HOST_WIDE_INT bit_offset = tree_low_cst (rli->bitpos, 0);
1195 #ifdef ADJUST_FIELD_ALIGN
1196 if (! TYPE_USER_ALIGN (type))
1197 type_align = ADJUST_FIELD_ALIGN (field, type_align);
1200 /* A bit field may not span more units of alignment of its type
1201 than its type itself. Advance to next boundary if necessary. */
1202 if (excess_unit_span (offset, bit_offset, field_size, type_align, type))
1204 if (DECL_PACKED (field))
1206 if (warn_packed_bitfield_compat == 1)
1209 "offset of packed bit-field %qD has changed in GCC 4.4",
1213 rli->bitpos = round_up (rli->bitpos, type_align);
1216 if (! DECL_PACKED (field))
1217 TYPE_USER_ALIGN (rli->t) |= TYPE_USER_ALIGN (type);
1221 #ifdef BITFIELD_NBYTES_LIMITED
1222 if (BITFIELD_NBYTES_LIMITED
1223 && ! targetm.ms_bitfield_layout_p (rli->t)
1224 && TREE_CODE (field) == FIELD_DECL
1225 && type != error_mark_node
1226 && DECL_BIT_FIELD_TYPE (field)
1227 && ! DECL_PACKED (field)
1228 && ! integer_zerop (DECL_SIZE (field))
1229 && host_integerp (DECL_SIZE (field), 1)
1230 && host_integerp (rli->offset, 1)
1231 && host_integerp (TYPE_SIZE (type), 1))
1233 unsigned int type_align = TYPE_ALIGN (type);
1234 tree dsize = DECL_SIZE (field);
1235 HOST_WIDE_INT field_size = tree_low_cst (dsize, 1);
1236 HOST_WIDE_INT offset = tree_low_cst (rli->offset, 0);
1237 HOST_WIDE_INT bit_offset = tree_low_cst (rli->bitpos, 0);
1239 #ifdef ADJUST_FIELD_ALIGN
1240 if (! TYPE_USER_ALIGN (type))
1241 type_align = ADJUST_FIELD_ALIGN (field, type_align);
1244 if (maximum_field_alignment != 0)
1245 type_align = MIN (type_align, maximum_field_alignment);
1246 /* ??? This test is opposite the test in the containing if
1247 statement, so this code is unreachable currently. */
1248 else if (DECL_PACKED (field))
1249 type_align = MIN (type_align, BITS_PER_UNIT);
1251 /* A bit field may not span the unit of alignment of its type.
1252 Advance to next boundary if necessary. */
1253 if (excess_unit_span (offset, bit_offset, field_size, type_align, type))
1254 rli->bitpos = round_up (rli->bitpos, type_align);
1256 TYPE_USER_ALIGN (rli->t) |= TYPE_USER_ALIGN (type);
1260 /* See the docs for TARGET_MS_BITFIELD_LAYOUT_P for details.
1262 When a bit field is inserted into a packed record, the whole
1263 size of the underlying type is used by one or more same-size
1264 adjacent bitfields. (That is, if its long:3, 32 bits is
1265 used in the record, and any additional adjacent long bitfields are
1266 packed into the same chunk of 32 bits. However, if the size
1267 changes, a new field of that size is allocated.) In an unpacked
1268 record, this is the same as using alignment, but not equivalent
1271 Note: for compatibility, we use the type size, not the type alignment
1272 to determine alignment, since that matches the documentation */
1274 if (targetm.ms_bitfield_layout_p (rli->t))
1276 tree prev_saved = rli->prev_field;
1277 tree prev_type = prev_saved ? DECL_BIT_FIELD_TYPE (prev_saved) : NULL;
1279 /* This is a bitfield if it exists. */
1280 if (rli->prev_field)
1282 /* If both are bitfields, nonzero, and the same size, this is
1283 the middle of a run. Zero declared size fields are special
1284 and handled as "end of run". (Note: it's nonzero declared
1285 size, but equal type sizes!) (Since we know that both
1286 the current and previous fields are bitfields by the
1287 time we check it, DECL_SIZE must be present for both.) */
1288 if (DECL_BIT_FIELD_TYPE (field)
1289 && !integer_zerop (DECL_SIZE (field))
1290 && !integer_zerop (DECL_SIZE (rli->prev_field))
1291 && host_integerp (DECL_SIZE (rli->prev_field), 0)
1292 && host_integerp (TYPE_SIZE (type), 0)
1293 && simple_cst_equal (TYPE_SIZE (type), TYPE_SIZE (prev_type)))
1295 /* We're in the middle of a run of equal type size fields; make
1296 sure we realign if we run out of bits. (Not decl size,
1298 HOST_WIDE_INT bitsize = tree_low_cst (DECL_SIZE (field), 1);
1300 if (rli->remaining_in_alignment < bitsize)
1302 HOST_WIDE_INT typesize = tree_low_cst (TYPE_SIZE (type), 1);
1304 /* out of bits; bump up to next 'word'. */
1306 = size_binop (PLUS_EXPR, rli->bitpos,
1307 bitsize_int (rli->remaining_in_alignment));
1308 rli->prev_field = field;
1309 if (typesize < bitsize)
1310 rli->remaining_in_alignment = 0;
1312 rli->remaining_in_alignment = typesize - bitsize;
1315 rli->remaining_in_alignment -= bitsize;
1319 /* End of a run: if leaving a run of bitfields of the same type
1320 size, we have to "use up" the rest of the bits of the type
1323 Compute the new position as the sum of the size for the prior
1324 type and where we first started working on that type.
1325 Note: since the beginning of the field was aligned then
1326 of course the end will be too. No round needed. */
1328 if (!integer_zerop (DECL_SIZE (rli->prev_field)))
1331 = size_binop (PLUS_EXPR, rli->bitpos,
1332 bitsize_int (rli->remaining_in_alignment));
1335 /* We "use up" size zero fields; the code below should behave
1336 as if the prior field was not a bitfield. */
1339 /* Cause a new bitfield to be captured, either this time (if
1340 currently a bitfield) or next time we see one. */
1341 if (!DECL_BIT_FIELD_TYPE(field)
1342 || integer_zerop (DECL_SIZE (field)))
1343 rli->prev_field = NULL;
1346 normalize_rli (rli);
1349 /* If we're starting a new run of same size type bitfields
1350 (or a run of non-bitfields), set up the "first of the run"
1353 That is, if the current field is not a bitfield, or if there
1354 was a prior bitfield the type sizes differ, or if there wasn't
1355 a prior bitfield the size of the current field is nonzero.
1357 Note: we must be sure to test ONLY the type size if there was
1358 a prior bitfield and ONLY for the current field being zero if
1361 if (!DECL_BIT_FIELD_TYPE (field)
1362 || (prev_saved != NULL
1363 ? !simple_cst_equal (TYPE_SIZE (type), TYPE_SIZE (prev_type))
1364 : !integer_zerop (DECL_SIZE (field)) ))
1366 /* Never smaller than a byte for compatibility. */
1367 unsigned int type_align = BITS_PER_UNIT;
1369 /* (When not a bitfield), we could be seeing a flex array (with
1370 no DECL_SIZE). Since we won't be using remaining_in_alignment
1371 until we see a bitfield (and come by here again) we just skip
1373 if (DECL_SIZE (field) != NULL
1374 && host_integerp (TYPE_SIZE (TREE_TYPE (field)), 1)
1375 && host_integerp (DECL_SIZE (field), 1))
1377 unsigned HOST_WIDE_INT bitsize
1378 = tree_low_cst (DECL_SIZE (field), 1);
1379 unsigned HOST_WIDE_INT typesize
1380 = tree_low_cst (TYPE_SIZE (TREE_TYPE (field)), 1);
1382 if (typesize < bitsize)
1383 rli->remaining_in_alignment = 0;
1385 rli->remaining_in_alignment = typesize - bitsize;
1388 /* Now align (conventionally) for the new type. */
1389 type_align = TYPE_ALIGN (TREE_TYPE (field));
1391 if (maximum_field_alignment != 0)
1392 type_align = MIN (type_align, maximum_field_alignment);
1394 rli->bitpos = round_up (rli->bitpos, type_align);
1396 /* If we really aligned, don't allow subsequent bitfields
1398 rli->prev_field = NULL;
1402 /* Offset so far becomes the position of this field after normalizing. */
1403 normalize_rli (rli);
1404 DECL_FIELD_OFFSET (field) = rli->offset;
1405 DECL_FIELD_BIT_OFFSET (field) = rli->bitpos;
1406 SET_DECL_OFFSET_ALIGN (field, rli->offset_align);
1408 /* If this field ended up more aligned than we thought it would be (we
1409 approximate this by seeing if its position changed), lay out the field
1410 again; perhaps we can use an integral mode for it now. */
1411 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field)))
1412 actual_align = (tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1)
1413 & - tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1));
1414 else if (integer_zerop (DECL_FIELD_OFFSET (field)))
1415 actual_align = MAX (BIGGEST_ALIGNMENT, rli->record_align);
1416 else if (host_integerp (DECL_FIELD_OFFSET (field), 1))
1417 actual_align = (BITS_PER_UNIT
1418 * (tree_low_cst (DECL_FIELD_OFFSET (field), 1)
1419 & - tree_low_cst (DECL_FIELD_OFFSET (field), 1)));
1421 actual_align = DECL_OFFSET_ALIGN (field);
1422 /* ACTUAL_ALIGN is still the actual alignment *within the record* .
1423 store / extract bit field operations will check the alignment of the
1424 record against the mode of bit fields. */
1426 if (known_align != actual_align)
1427 layout_decl (field, actual_align);
1429 if (rli->prev_field == NULL && DECL_BIT_FIELD_TYPE (field))
1430 rli->prev_field = field;
1432 /* Now add size of this field to the size of the record. If the size is
1433 not constant, treat the field as being a multiple of bytes and just
1434 adjust the offset, resetting the bit position. Otherwise, apportion the
1435 size amongst the bit position and offset. First handle the case of an
1436 unspecified size, which can happen when we have an invalid nested struct
1437 definition, such as struct j { struct j { int i; } }. The error message
1438 is printed in finish_struct. */
1439 if (DECL_SIZE (field) == 0)
1441 else if (TREE_CODE (DECL_SIZE (field)) != INTEGER_CST
1442 || TREE_OVERFLOW (DECL_SIZE (field)))
1445 = size_binop (PLUS_EXPR, rli->offset,
1446 fold_convert (sizetype,
1447 size_binop (CEIL_DIV_EXPR, rli->bitpos,
1448 bitsize_unit_node)));
1450 = size_binop (PLUS_EXPR, rli->offset, DECL_SIZE_UNIT (field));
1451 rli->bitpos = bitsize_zero_node;
1452 rli->offset_align = MIN (rli->offset_align, desired_align);
1454 else if (targetm.ms_bitfield_layout_p (rli->t))
1456 rli->bitpos = size_binop (PLUS_EXPR, rli->bitpos, DECL_SIZE (field));
1458 /* If we ended a bitfield before the full length of the type then
1459 pad the struct out to the full length of the last type. */
1460 if ((DECL_CHAIN (field) == NULL
1461 || TREE_CODE (DECL_CHAIN (field)) != FIELD_DECL)
1462 && DECL_BIT_FIELD_TYPE (field)
1463 && !integer_zerop (DECL_SIZE (field)))
1464 rli->bitpos = size_binop (PLUS_EXPR, rli->bitpos,
1465 bitsize_int (rli->remaining_in_alignment));
1467 normalize_rli (rli);
1471 rli->bitpos = size_binop (PLUS_EXPR, rli->bitpos, DECL_SIZE (field));
1472 normalize_rli (rli);
1476 /* Assuming that all the fields have been laid out, this function uses
1477 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
1478 indicated by RLI. */
1481 finalize_record_size (record_layout_info rli)
1483 tree unpadded_size, unpadded_size_unit;
1485 /* Now we want just byte and bit offsets, so set the offset alignment
1486 to be a byte and then normalize. */
1487 rli->offset_align = BITS_PER_UNIT;
1488 normalize_rli (rli);
1490 /* Determine the desired alignment. */
1491 #ifdef ROUND_TYPE_ALIGN
1492 TYPE_ALIGN (rli->t) = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t),
1495 TYPE_ALIGN (rli->t) = MAX (TYPE_ALIGN (rli->t), rli->record_align);
1498 /* Compute the size so far. Be sure to allow for extra bits in the
1499 size in bytes. We have guaranteed above that it will be no more
1500 than a single byte. */
1501 unpadded_size = rli_size_so_far (rli);
1502 unpadded_size_unit = rli_size_unit_so_far (rli);
1503 if (! integer_zerop (rli->bitpos))
1505 = size_binop (PLUS_EXPR, unpadded_size_unit, size_one_node);
1507 /* Round the size up to be a multiple of the required alignment. */
1508 TYPE_SIZE (rli->t) = round_up (unpadded_size, TYPE_ALIGN (rli->t));
1509 TYPE_SIZE_UNIT (rli->t)
1510 = round_up (unpadded_size_unit, TYPE_ALIGN_UNIT (rli->t));
1512 if (TREE_CONSTANT (unpadded_size)
1513 && simple_cst_equal (unpadded_size, TYPE_SIZE (rli->t)) == 0
1514 && input_location != BUILTINS_LOCATION)
1515 warning (OPT_Wpadded, "padding struct size to alignment boundary");
1517 if (warn_packed && TREE_CODE (rli->t) == RECORD_TYPE
1518 && TYPE_PACKED (rli->t) && ! rli->packed_maybe_necessary
1519 && TREE_CONSTANT (unpadded_size))
1523 #ifdef ROUND_TYPE_ALIGN
1525 = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t), rli->unpacked_align);
1527 rli->unpacked_align = MAX (TYPE_ALIGN (rli->t), rli->unpacked_align);
1530 unpacked_size = round_up (TYPE_SIZE (rli->t), rli->unpacked_align);
1531 if (simple_cst_equal (unpacked_size, TYPE_SIZE (rli->t)))
1533 if (TYPE_NAME (rli->t))
1537 if (TREE_CODE (TYPE_NAME (rli->t)) == IDENTIFIER_NODE)
1538 name = TYPE_NAME (rli->t);
1540 name = DECL_NAME (TYPE_NAME (rli->t));
1542 if (STRICT_ALIGNMENT)
1543 warning (OPT_Wpacked, "packed attribute causes inefficient "
1544 "alignment for %qE", name);
1546 warning (OPT_Wpacked,
1547 "packed attribute is unnecessary for %qE", name);
1551 if (STRICT_ALIGNMENT)
1552 warning (OPT_Wpacked,
1553 "packed attribute causes inefficient alignment");
1555 warning (OPT_Wpacked, "packed attribute is unnecessary");
1561 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
1564 compute_record_mode (tree type)
1567 enum machine_mode mode = VOIDmode;
1569 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
1570 However, if possible, we use a mode that fits in a register
1571 instead, in order to allow for better optimization down the
1573 SET_TYPE_MODE (type, BLKmode);
1575 if (! host_integerp (TYPE_SIZE (type), 1))
1578 /* A record which has any BLKmode members must itself be
1579 BLKmode; it can't go in a register. Unless the member is
1580 BLKmode only because it isn't aligned. */
1581 for (field = TYPE_FIELDS (type); field; field = DECL_CHAIN (field))
1583 if (TREE_CODE (field) != FIELD_DECL)
1586 if (TREE_CODE (TREE_TYPE (field)) == ERROR_MARK
1587 || (TYPE_MODE (TREE_TYPE (field)) == BLKmode
1588 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field))
1589 && !(TYPE_SIZE (TREE_TYPE (field)) != 0
1590 && integer_zerop (TYPE_SIZE (TREE_TYPE (field)))))
1591 || ! host_integerp (bit_position (field), 1)
1592 || DECL_SIZE (field) == 0
1593 || ! host_integerp (DECL_SIZE (field), 1))
1596 /* If this field is the whole struct, remember its mode so
1597 that, say, we can put a double in a class into a DF
1598 register instead of forcing it to live in the stack. */
1599 if (simple_cst_equal (TYPE_SIZE (type), DECL_SIZE (field)))
1600 mode = DECL_MODE (field);
1602 #ifdef MEMBER_TYPE_FORCES_BLK
1603 /* With some targets, eg. c4x, it is sub-optimal
1604 to access an aligned BLKmode structure as a scalar. */
1606 if (MEMBER_TYPE_FORCES_BLK (field, mode))
1608 #endif /* MEMBER_TYPE_FORCES_BLK */
1611 /* If we only have one real field; use its mode if that mode's size
1612 matches the type's size. This only applies to RECORD_TYPE. This
1613 does not apply to unions. */
1614 if (TREE_CODE (type) == RECORD_TYPE && mode != VOIDmode
1615 && host_integerp (TYPE_SIZE (type), 1)
1616 && GET_MODE_BITSIZE (mode) == TREE_INT_CST_LOW (TYPE_SIZE (type)))
1617 SET_TYPE_MODE (type, mode);
1619 SET_TYPE_MODE (type, mode_for_size_tree (TYPE_SIZE (type), MODE_INT, 1));
1621 /* If structure's known alignment is less than what the scalar
1622 mode would need, and it matters, then stick with BLKmode. */
1623 if (TYPE_MODE (type) != BLKmode
1625 && ! (TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT
1626 || TYPE_ALIGN (type) >= GET_MODE_ALIGNMENT (TYPE_MODE (type))))
1628 /* If this is the only reason this type is BLKmode, then
1629 don't force containing types to be BLKmode. */
1630 TYPE_NO_FORCE_BLK (type) = 1;
1631 SET_TYPE_MODE (type, BLKmode);
1635 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1639 finalize_type_size (tree type)
1641 /* Normally, use the alignment corresponding to the mode chosen.
1642 However, where strict alignment is not required, avoid
1643 over-aligning structures, since most compilers do not do this
1646 if (TYPE_MODE (type) != BLKmode && TYPE_MODE (type) != VOIDmode
1647 && (STRICT_ALIGNMENT
1648 || (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE
1649 && TREE_CODE (type) != QUAL_UNION_TYPE
1650 && TREE_CODE (type) != ARRAY_TYPE)))
1652 unsigned mode_align = GET_MODE_ALIGNMENT (TYPE_MODE (type));
1654 /* Don't override a larger alignment requirement coming from a user
1655 alignment of one of the fields. */
1656 if (mode_align >= TYPE_ALIGN (type))
1658 TYPE_ALIGN (type) = mode_align;
1659 TYPE_USER_ALIGN (type) = 0;
1663 /* Do machine-dependent extra alignment. */
1664 #ifdef ROUND_TYPE_ALIGN
1666 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (type), BITS_PER_UNIT);
1669 /* If we failed to find a simple way to calculate the unit size
1670 of the type, find it by division. */
1671 if (TYPE_SIZE_UNIT (type) == 0 && TYPE_SIZE (type) != 0)
1672 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1673 result will fit in sizetype. We will get more efficient code using
1674 sizetype, so we force a conversion. */
1675 TYPE_SIZE_UNIT (type)
1676 = fold_convert (sizetype,
1677 size_binop (FLOOR_DIV_EXPR, TYPE_SIZE (type),
1678 bitsize_unit_node));
1680 if (TYPE_SIZE (type) != 0)
1682 TYPE_SIZE (type) = round_up (TYPE_SIZE (type), TYPE_ALIGN (type));
1683 TYPE_SIZE_UNIT (type)
1684 = round_up (TYPE_SIZE_UNIT (type), TYPE_ALIGN_UNIT (type));
1687 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1688 if (TYPE_SIZE (type) != 0 && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
1689 TYPE_SIZE (type) = variable_size (TYPE_SIZE (type));
1690 if (TYPE_SIZE_UNIT (type) != 0
1691 && TREE_CODE (TYPE_SIZE_UNIT (type)) != INTEGER_CST)
1692 TYPE_SIZE_UNIT (type) = variable_size (TYPE_SIZE_UNIT (type));
1694 /* Also layout any other variants of the type. */
1695 if (TYPE_NEXT_VARIANT (type)
1696 || type != TYPE_MAIN_VARIANT (type))
1699 /* Record layout info of this variant. */
1700 tree size = TYPE_SIZE (type);
1701 tree size_unit = TYPE_SIZE_UNIT (type);
1702 unsigned int align = TYPE_ALIGN (type);
1703 unsigned int user_align = TYPE_USER_ALIGN (type);
1704 enum machine_mode mode = TYPE_MODE (type);
1706 /* Copy it into all variants. */
1707 for (variant = TYPE_MAIN_VARIANT (type);
1709 variant = TYPE_NEXT_VARIANT (variant))
1711 TYPE_SIZE (variant) = size;
1712 TYPE_SIZE_UNIT (variant) = size_unit;
1713 TYPE_ALIGN (variant) = align;
1714 TYPE_USER_ALIGN (variant) = user_align;
1715 SET_TYPE_MODE (variant, mode);
1720 /* Do all of the work required to layout the type indicated by RLI,
1721 once the fields have been laid out. This function will call `free'
1722 for RLI, unless FREE_P is false. Passing a value other than false
1723 for FREE_P is bad practice; this option only exists to support the
1727 finish_record_layout (record_layout_info rli, int free_p)
1731 /* Compute the final size. */
1732 finalize_record_size (rli);
1734 /* Compute the TYPE_MODE for the record. */
1735 compute_record_mode (rli->t);
1737 /* Perform any last tweaks to the TYPE_SIZE, etc. */
1738 finalize_type_size (rli->t);
1740 /* Propagate TYPE_PACKED to variants. With C++ templates,
1741 handle_packed_attribute is too early to do this. */
1742 for (variant = TYPE_NEXT_VARIANT (rli->t); variant;
1743 variant = TYPE_NEXT_VARIANT (variant))
1744 TYPE_PACKED (variant) = TYPE_PACKED (rli->t);
1746 /* Lay out any static members. This is done now because their type
1747 may use the record's type. */
1748 while (!VEC_empty (tree, rli->pending_statics))
1749 layout_decl (VEC_pop (tree, rli->pending_statics), 0);
1754 VEC_free (tree, gc, rli->pending_statics);
1760 /* Finish processing a builtin RECORD_TYPE type TYPE. It's name is
1761 NAME, its fields are chained in reverse on FIELDS.
1763 If ALIGN_TYPE is non-null, it is given the same alignment as
1767 finish_builtin_struct (tree type, const char *name, tree fields,
1772 for (tail = NULL_TREE; fields; tail = fields, fields = next)
1774 DECL_FIELD_CONTEXT (fields) = type;
1775 next = DECL_CHAIN (fields);
1776 DECL_CHAIN (fields) = tail;
1778 TYPE_FIELDS (type) = tail;
1782 TYPE_ALIGN (type) = TYPE_ALIGN (align_type);
1783 TYPE_USER_ALIGN (type) = TYPE_USER_ALIGN (align_type);
1787 #if 0 /* not yet, should get fixed properly later */
1788 TYPE_NAME (type) = make_type_decl (get_identifier (name), type);
1790 TYPE_NAME (type) = build_decl (BUILTINS_LOCATION,
1791 TYPE_DECL, get_identifier (name), type);
1793 TYPE_STUB_DECL (type) = TYPE_NAME (type);
1794 layout_decl (TYPE_NAME (type), 0);
1797 /* Calculate the mode, size, and alignment for TYPE.
1798 For an array type, calculate the element separation as well.
1799 Record TYPE on the chain of permanent or temporary types
1800 so that dbxout will find out about it.
1802 TYPE_SIZE of a type is nonzero if the type has been laid out already.
1803 layout_type does nothing on such a type.
1805 If the type is incomplete, its TYPE_SIZE remains zero. */
1808 layout_type (tree type)
1812 if (type == error_mark_node)
1815 /* Do nothing if type has been laid out before. */
1816 if (TYPE_SIZE (type))
1819 switch (TREE_CODE (type))
1822 /* This kind of type is the responsibility
1823 of the language-specific code. */
1826 case BOOLEAN_TYPE: /* Used for Java, Pascal, and Chill. */
1827 if (TYPE_PRECISION (type) == 0)
1828 TYPE_PRECISION (type) = 1; /* default to one byte/boolean. */
1830 /* ... fall through ... */
1834 if (TREE_CODE (TYPE_MIN_VALUE (type)) == INTEGER_CST
1835 && tree_int_cst_sgn (TYPE_MIN_VALUE (type)) >= 0)
1836 TYPE_UNSIGNED (type) = 1;
1838 SET_TYPE_MODE (type,
1839 smallest_mode_for_size (TYPE_PRECISION (type), MODE_INT));
1840 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1841 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1845 SET_TYPE_MODE (type,
1846 mode_for_size (TYPE_PRECISION (type), MODE_FLOAT, 0));
1847 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1848 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1851 case FIXED_POINT_TYPE:
1852 /* TYPE_MODE (type) has been set already. */
1853 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1854 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1858 TYPE_UNSIGNED (type) = TYPE_UNSIGNED (TREE_TYPE (type));
1859 SET_TYPE_MODE (type,
1860 mode_for_size (2 * TYPE_PRECISION (TREE_TYPE (type)),
1861 (TREE_CODE (TREE_TYPE (type)) == REAL_TYPE
1862 ? MODE_COMPLEX_FLOAT : MODE_COMPLEX_INT),
1864 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1865 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1870 int nunits = TYPE_VECTOR_SUBPARTS (type);
1871 tree innertype = TREE_TYPE (type);
1873 gcc_assert (!(nunits & (nunits - 1)));
1875 /* Find an appropriate mode for the vector type. */
1876 if (TYPE_MODE (type) == VOIDmode)
1877 SET_TYPE_MODE (type,
1878 mode_for_vector (TYPE_MODE (innertype), nunits));
1880 TYPE_SATURATING (type) = TYPE_SATURATING (TREE_TYPE (type));
1881 TYPE_UNSIGNED (type) = TYPE_UNSIGNED (TREE_TYPE (type));
1882 TYPE_SIZE_UNIT (type) = int_const_binop (MULT_EXPR,
1883 TYPE_SIZE_UNIT (innertype),
1885 TYPE_SIZE (type) = int_const_binop (MULT_EXPR, TYPE_SIZE (innertype),
1886 bitsize_int (nunits));
1888 /* Always naturally align vectors. This prevents ABI changes
1889 depending on whether or not native vector modes are supported. */
1890 TYPE_ALIGN (type) = tree_low_cst (TYPE_SIZE (type), 0);
1895 /* This is an incomplete type and so doesn't have a size. */
1896 TYPE_ALIGN (type) = 1;
1897 TYPE_USER_ALIGN (type) = 0;
1898 SET_TYPE_MODE (type, VOIDmode);
1902 TYPE_SIZE (type) = bitsize_int (POINTER_SIZE);
1903 TYPE_SIZE_UNIT (type) = size_int (POINTER_SIZE / BITS_PER_UNIT);
1904 /* A pointer might be MODE_PARTIAL_INT,
1905 but ptrdiff_t must be integral. */
1906 SET_TYPE_MODE (type, mode_for_size (POINTER_SIZE, MODE_INT, 0));
1907 TYPE_PRECISION (type) = POINTER_SIZE;
1912 /* It's hard to see what the mode and size of a function ought to
1913 be, but we do know the alignment is FUNCTION_BOUNDARY, so
1914 make it consistent with that. */
1915 SET_TYPE_MODE (type, mode_for_size (FUNCTION_BOUNDARY, MODE_INT, 0));
1916 TYPE_SIZE (type) = bitsize_int (FUNCTION_BOUNDARY);
1917 TYPE_SIZE_UNIT (type) = size_int (FUNCTION_BOUNDARY / BITS_PER_UNIT);
1921 case REFERENCE_TYPE:
1923 enum machine_mode mode = TYPE_MODE (type);
1924 if (TREE_CODE (type) == REFERENCE_TYPE && reference_types_internal)
1926 addr_space_t as = TYPE_ADDR_SPACE (TREE_TYPE (type));
1927 mode = targetm.addr_space.address_mode (as);
1930 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (mode));
1931 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (mode));
1932 TYPE_UNSIGNED (type) = 1;
1933 TYPE_PRECISION (type) = GET_MODE_BITSIZE (mode);
1939 tree index = TYPE_DOMAIN (type);
1940 tree element = TREE_TYPE (type);
1942 build_pointer_type (element);
1944 /* We need to know both bounds in order to compute the size. */
1945 if (index && TYPE_MAX_VALUE (index) && TYPE_MIN_VALUE (index)
1946 && TYPE_SIZE (element))
1948 tree ub = TYPE_MAX_VALUE (index);
1949 tree lb = TYPE_MIN_VALUE (index);
1950 tree element_size = TYPE_SIZE (element);
1953 /* Make sure that an array of zero-sized element is zero-sized
1954 regardless of its extent. */
1955 if (integer_zerop (element_size))
1956 length = size_zero_node;
1958 /* The computation should happen in the original type so
1959 that (possible) negative values are handled appropriately. */
1962 = fold_convert (sizetype,
1963 fold_build2 (PLUS_EXPR, TREE_TYPE (lb),
1964 build_int_cst (TREE_TYPE (lb), 1),
1965 fold_build2 (MINUS_EXPR,
1969 TYPE_SIZE (type) = size_binop (MULT_EXPR, element_size,
1970 fold_convert (bitsizetype,
1973 /* If we know the size of the element, calculate the total size
1974 directly, rather than do some division thing below. This
1975 optimization helps Fortran assumed-size arrays (where the
1976 size of the array is determined at runtime) substantially. */
1977 if (TYPE_SIZE_UNIT (element))
1978 TYPE_SIZE_UNIT (type)
1979 = size_binop (MULT_EXPR, TYPE_SIZE_UNIT (element), length);
1982 /* Now round the alignment and size,
1983 using machine-dependent criteria if any. */
1985 #ifdef ROUND_TYPE_ALIGN
1987 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (element), BITS_PER_UNIT);
1989 TYPE_ALIGN (type) = MAX (TYPE_ALIGN (element), BITS_PER_UNIT);
1991 TYPE_USER_ALIGN (type) = TYPE_USER_ALIGN (element);
1992 SET_TYPE_MODE (type, BLKmode);
1993 if (TYPE_SIZE (type) != 0
1994 #ifdef MEMBER_TYPE_FORCES_BLK
1995 && ! MEMBER_TYPE_FORCES_BLK (type, VOIDmode)
1997 /* BLKmode elements force BLKmode aggregate;
1998 else extract/store fields may lose. */
1999 && (TYPE_MODE (TREE_TYPE (type)) != BLKmode
2000 || TYPE_NO_FORCE_BLK (TREE_TYPE (type))))
2002 SET_TYPE_MODE (type, mode_for_array (TREE_TYPE (type),
2004 if (TYPE_MODE (type) != BLKmode
2005 && STRICT_ALIGNMENT && TYPE_ALIGN (type) < BIGGEST_ALIGNMENT
2006 && TYPE_ALIGN (type) < GET_MODE_ALIGNMENT (TYPE_MODE (type)))
2008 TYPE_NO_FORCE_BLK (type) = 1;
2009 SET_TYPE_MODE (type, BLKmode);
2012 /* When the element size is constant, check that it is at least as
2013 large as the element alignment. */
2014 if (TYPE_SIZE_UNIT (element)
2015 && TREE_CODE (TYPE_SIZE_UNIT (element)) == INTEGER_CST
2016 /* If TYPE_SIZE_UNIT overflowed, then it is certainly larger than
2018 && !TREE_OVERFLOW (TYPE_SIZE_UNIT (element))
2019 && !integer_zerop (TYPE_SIZE_UNIT (element))
2020 && compare_tree_int (TYPE_SIZE_UNIT (element),
2021 TYPE_ALIGN_UNIT (element)) < 0)
2022 error ("alignment of array elements is greater than element size");
2028 case QUAL_UNION_TYPE:
2031 record_layout_info rli;
2033 /* Initialize the layout information. */
2034 rli = start_record_layout (type);
2036 /* If this is a QUAL_UNION_TYPE, we want to process the fields
2037 in the reverse order in building the COND_EXPR that denotes
2038 its size. We reverse them again later. */
2039 if (TREE_CODE (type) == QUAL_UNION_TYPE)
2040 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
2042 /* Place all the fields. */
2043 for (field = TYPE_FIELDS (type); field; field = DECL_CHAIN (field))
2044 place_field (rli, field);
2046 if (TREE_CODE (type) == QUAL_UNION_TYPE)
2047 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
2049 /* Finish laying out the record. */
2050 finish_record_layout (rli, /*free_p=*/true);
2058 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
2059 records and unions, finish_record_layout already called this
2061 if (TREE_CODE (type) != RECORD_TYPE
2062 && TREE_CODE (type) != UNION_TYPE
2063 && TREE_CODE (type) != QUAL_UNION_TYPE)
2064 finalize_type_size (type);
2066 /* We should never see alias sets on incomplete aggregates. And we
2067 should not call layout_type on not incomplete aggregates. */
2068 if (AGGREGATE_TYPE_P (type))
2069 gcc_assert (!TYPE_ALIAS_SET_KNOWN_P (type));
2072 /* Vector types need to re-check the target flags each time we report
2073 the machine mode. We need to do this because attribute target can
2074 change the result of vector_mode_supported_p and have_regs_of_mode
2075 on a per-function basis. Thus the TYPE_MODE of a VECTOR_TYPE can
2076 change on a per-function basis. */
2077 /* ??? Possibly a better solution is to run through all the types
2078 referenced by a function and re-compute the TYPE_MODE once, rather
2079 than make the TYPE_MODE macro call a function. */
2082 vector_type_mode (const_tree t)
2084 enum machine_mode mode;
2086 gcc_assert (TREE_CODE (t) == VECTOR_TYPE);
2088 mode = t->type.mode;
2089 if (VECTOR_MODE_P (mode)
2090 && (!targetm.vector_mode_supported_p (mode)
2091 || !have_regs_of_mode[mode]))
2093 enum machine_mode innermode = TREE_TYPE (t)->type.mode;
2095 /* For integers, try mapping it to a same-sized scalar mode. */
2096 if (GET_MODE_CLASS (innermode) == MODE_INT)
2098 mode = mode_for_size (TYPE_VECTOR_SUBPARTS (t)
2099 * GET_MODE_BITSIZE (innermode), MODE_INT, 0);
2101 if (mode != VOIDmode && have_regs_of_mode[mode])
2111 /* Create and return a type for signed integers of PRECISION bits. */
2114 make_signed_type (int precision)
2116 tree type = make_node (INTEGER_TYPE);
2118 TYPE_PRECISION (type) = precision;
2120 fixup_signed_type (type);
2124 /* Create and return a type for unsigned integers of PRECISION bits. */
2127 make_unsigned_type (int precision)
2129 tree type = make_node (INTEGER_TYPE);
2131 TYPE_PRECISION (type) = precision;
2133 fixup_unsigned_type (type);
2137 /* Create and return a type for fract of PRECISION bits, UNSIGNEDP,
2141 make_fract_type (int precision, int unsignedp, int satp)
2143 tree type = make_node (FIXED_POINT_TYPE);
2145 TYPE_PRECISION (type) = precision;
2148 TYPE_SATURATING (type) = 1;
2150 /* Lay out the type: set its alignment, size, etc. */
2153 TYPE_UNSIGNED (type) = 1;
2154 SET_TYPE_MODE (type, mode_for_size (precision, MODE_UFRACT, 0));
2157 SET_TYPE_MODE (type, mode_for_size (precision, MODE_FRACT, 0));
2163 /* Create and return a type for accum of PRECISION bits, UNSIGNEDP,
2167 make_accum_type (int precision, int unsignedp, int satp)
2169 tree type = make_node (FIXED_POINT_TYPE);
2171 TYPE_PRECISION (type) = precision;
2174 TYPE_SATURATING (type) = 1;
2176 /* Lay out the type: set its alignment, size, etc. */
2179 TYPE_UNSIGNED (type) = 1;
2180 SET_TYPE_MODE (type, mode_for_size (precision, MODE_UACCUM, 0));
2183 SET_TYPE_MODE (type, mode_for_size (precision, MODE_ACCUM, 0));
2189 /* Initialize sizetype and bitsizetype to a reasonable and temporary
2190 value to enable integer types to be created. */
2193 initialize_sizetypes (void)
2195 tree t = make_node (INTEGER_TYPE);
2196 int precision = GET_MODE_BITSIZE (SImode);
2198 SET_TYPE_MODE (t, SImode);
2199 TYPE_ALIGN (t) = GET_MODE_ALIGNMENT (SImode);
2200 TYPE_IS_SIZETYPE (t) = 1;
2201 TYPE_UNSIGNED (t) = 1;
2202 TYPE_SIZE (t) = build_int_cst (t, precision);
2203 TYPE_SIZE_UNIT (t) = build_int_cst (t, GET_MODE_SIZE (SImode));
2204 TYPE_PRECISION (t) = precision;
2206 set_min_and_max_values_for_integral_type (t, precision,
2207 /*is_unsigned=*/true);
2210 bitsizetype = build_distinct_type_copy (t);
2213 /* Make sizetype a version of TYPE, and initialize *sizetype accordingly.
2214 We do this by overwriting the stub sizetype and bitsizetype nodes created
2215 by initialize_sizetypes. This makes sure that (a) anything stubby about
2216 them no longer exists and (b) any INTEGER_CSTs created with such a type,
2220 set_sizetype (tree type)
2223 int oprecision = TYPE_PRECISION (type);
2224 /* The *bitsizetype types use a precision that avoids overflows when
2225 calculating signed sizes / offsets in bits. However, when
2226 cross-compiling from a 32 bit to a 64 bit host, we are limited to 64 bit
2229 = MIN (oprecision + BITS_PER_UNIT_LOG + 1, MAX_FIXED_MODE_SIZE);
2231 = GET_MODE_PRECISION (smallest_mode_for_size (precision, MODE_INT));
2232 if (precision > HOST_BITS_PER_WIDE_INT * 2)
2233 precision = HOST_BITS_PER_WIDE_INT * 2;
2235 /* sizetype must be an unsigned type. */
2236 gcc_assert (TYPE_UNSIGNED (type));
2238 t = build_distinct_type_copy (type);
2239 /* We want to use sizetype's cache, as we will be replacing that type. */
2240 TYPE_CACHED_VALUES (t) = TYPE_CACHED_VALUES (sizetype);
2241 TYPE_CACHED_VALUES_P (t) = TYPE_CACHED_VALUES_P (sizetype);
2242 TYPE_UID (t) = TYPE_UID (sizetype);
2243 TYPE_IS_SIZETYPE (t) = 1;
2245 /* Replace our original stub sizetype. */
2246 memcpy (sizetype, t, tree_size (sizetype));
2247 TYPE_MAIN_VARIANT (sizetype) = sizetype;
2248 TYPE_CANONICAL (sizetype) = sizetype;
2250 /* sizetype is unsigned but we need to fix TYPE_MAX_VALUE so that it is
2251 sign-extended in a way consistent with force_fit_type. */
2252 max = TYPE_MAX_VALUE (sizetype);
2253 TYPE_MAX_VALUE (sizetype)
2254 = double_int_to_tree (sizetype, tree_to_double_int (max));
2256 t = make_node (INTEGER_TYPE);
2257 TYPE_NAME (t) = get_identifier ("bit_size_type");
2258 /* We want to use bitsizetype's cache, as we will be replacing that type. */
2259 TYPE_CACHED_VALUES (t) = TYPE_CACHED_VALUES (bitsizetype);
2260 TYPE_CACHED_VALUES_P (t) = TYPE_CACHED_VALUES_P (bitsizetype);
2261 TYPE_PRECISION (t) = precision;
2262 TYPE_UID (t) = TYPE_UID (bitsizetype);
2263 TYPE_IS_SIZETYPE (t) = 1;
2265 /* Replace our original stub bitsizetype. */
2266 memcpy (bitsizetype, t, tree_size (bitsizetype));
2267 TYPE_MAIN_VARIANT (bitsizetype) = bitsizetype;
2268 TYPE_CANONICAL (bitsizetype) = bitsizetype;
2270 fixup_unsigned_type (bitsizetype);
2272 /* Create the signed variants of *sizetype. */
2273 ssizetype = make_signed_type (oprecision);
2274 TYPE_IS_SIZETYPE (ssizetype) = 1;
2275 sbitsizetype = make_signed_type (precision);
2276 TYPE_IS_SIZETYPE (sbitsizetype) = 1;
2279 /* TYPE is an integral type, i.e., an INTEGRAL_TYPE, ENUMERAL_TYPE
2280 or BOOLEAN_TYPE. Set TYPE_MIN_VALUE and TYPE_MAX_VALUE
2281 for TYPE, based on the PRECISION and whether or not the TYPE
2282 IS_UNSIGNED. PRECISION need not correspond to a width supported
2283 natively by the hardware; for example, on a machine with 8-bit,
2284 16-bit, and 32-bit register modes, PRECISION might be 7, 23, or
2288 set_min_and_max_values_for_integral_type (tree type,
2297 min_value = build_int_cst (type, 0);
2299 = build_int_cst_wide (type, precision - HOST_BITS_PER_WIDE_INT >= 0
2301 : ((HOST_WIDE_INT) 1 << precision) - 1,
2302 precision - HOST_BITS_PER_WIDE_INT > 0
2303 ? ((unsigned HOST_WIDE_INT) ~0
2304 >> (HOST_BITS_PER_WIDE_INT
2305 - (precision - HOST_BITS_PER_WIDE_INT)))
2311 = build_int_cst_wide (type,
2312 (precision - HOST_BITS_PER_WIDE_INT > 0
2314 : (HOST_WIDE_INT) (-1) << (precision - 1)),
2315 (((HOST_WIDE_INT) (-1)
2316 << (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
2317 ? precision - HOST_BITS_PER_WIDE_INT - 1
2320 = build_int_cst_wide (type,
2321 (precision - HOST_BITS_PER_WIDE_INT > 0
2323 : ((HOST_WIDE_INT) 1 << (precision - 1)) - 1),
2324 (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
2325 ? (((HOST_WIDE_INT) 1
2326 << (precision - HOST_BITS_PER_WIDE_INT - 1))) - 1
2330 TYPE_MIN_VALUE (type) = min_value;
2331 TYPE_MAX_VALUE (type) = max_value;
2334 /* Set the extreme values of TYPE based on its precision in bits,
2335 then lay it out. Used when make_signed_type won't do
2336 because the tree code is not INTEGER_TYPE.
2337 E.g. for Pascal, when the -fsigned-char option is given. */
2340 fixup_signed_type (tree type)
2342 int precision = TYPE_PRECISION (type);
2344 /* We can not represent properly constants greater then
2345 2 * HOST_BITS_PER_WIDE_INT, still we need the types
2346 as they are used by i386 vector extensions and friends. */
2347 if (precision > HOST_BITS_PER_WIDE_INT * 2)
2348 precision = HOST_BITS_PER_WIDE_INT * 2;
2350 set_min_and_max_values_for_integral_type (type, precision,
2351 /*is_unsigned=*/false);
2353 /* Lay out the type: set its alignment, size, etc. */
2357 /* Set the extreme values of TYPE based on its precision in bits,
2358 then lay it out. This is used both in `make_unsigned_type'
2359 and for enumeral types. */
2362 fixup_unsigned_type (tree type)
2364 int precision = TYPE_PRECISION (type);
2366 /* We can not represent properly constants greater then
2367 2 * HOST_BITS_PER_WIDE_INT, still we need the types
2368 as they are used by i386 vector extensions and friends. */
2369 if (precision > HOST_BITS_PER_WIDE_INT * 2)
2370 precision = HOST_BITS_PER_WIDE_INT * 2;
2372 TYPE_UNSIGNED (type) = 1;
2374 set_min_and_max_values_for_integral_type (type, precision,
2375 /*is_unsigned=*/true);
2377 /* Lay out the type: set its alignment, size, etc. */
2381 /* Find the best machine mode to use when referencing a bit field of length
2382 BITSIZE bits starting at BITPOS.
2384 The underlying object is known to be aligned to a boundary of ALIGN bits.
2385 If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
2386 larger than LARGEST_MODE (usually SImode).
2388 If no mode meets all these conditions, we return VOIDmode.
2390 If VOLATILEP is false and SLOW_BYTE_ACCESS is false, we return the
2391 smallest mode meeting these conditions.
2393 If VOLATILEP is false and SLOW_BYTE_ACCESS is true, we return the
2394 largest mode (but a mode no wider than UNITS_PER_WORD) that meets
2397 If VOLATILEP is true the narrow_volatile_bitfields target hook is used to
2398 decide which of the above modes should be used. */
2401 get_best_mode (int bitsize, int bitpos, unsigned int align,
2402 enum machine_mode largest_mode, int volatilep)
2404 enum machine_mode mode;
2405 unsigned int unit = 0;
2407 /* Find the narrowest integer mode that contains the bit field. */
2408 for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
2409 mode = GET_MODE_WIDER_MODE (mode))
2411 unit = GET_MODE_BITSIZE (mode);
2412 if ((bitpos % unit) + bitsize <= unit)
2416 if (mode == VOIDmode
2417 /* It is tempting to omit the following line
2418 if STRICT_ALIGNMENT is true.
2419 But that is incorrect, since if the bitfield uses part of 3 bytes
2420 and we use a 4-byte mode, we could get a spurious segv
2421 if the extra 4th byte is past the end of memory.
2422 (Though at least one Unix compiler ignores this problem:
2423 that on the Sequent 386 machine. */
2424 || MIN (unit, BIGGEST_ALIGNMENT) > align
2425 || (largest_mode != VOIDmode && unit > GET_MODE_BITSIZE (largest_mode)))
2428 if ((SLOW_BYTE_ACCESS && ! volatilep)
2429 || (volatilep && !targetm.narrow_volatile_bitfield ()))
2431 enum machine_mode wide_mode = VOIDmode, tmode;
2433 for (tmode = GET_CLASS_NARROWEST_MODE (MODE_INT); tmode != VOIDmode;
2434 tmode = GET_MODE_WIDER_MODE (tmode))
2436 unit = GET_MODE_BITSIZE (tmode);
2437 if (bitpos / unit == (bitpos + bitsize - 1) / unit
2438 && unit <= BITS_PER_WORD
2439 && unit <= MIN (align, BIGGEST_ALIGNMENT)
2440 && (largest_mode == VOIDmode
2441 || unit <= GET_MODE_BITSIZE (largest_mode)))
2445 if (wide_mode != VOIDmode)
2452 /* Gets minimal and maximal values for MODE (signed or unsigned depending on
2453 SIGN). The returned constants are made to be usable in TARGET_MODE. */
2456 get_mode_bounds (enum machine_mode mode, int sign,
2457 enum machine_mode target_mode,
2458 rtx *mmin, rtx *mmax)
2460 unsigned size = GET_MODE_BITSIZE (mode);
2461 unsigned HOST_WIDE_INT min_val, max_val;
2463 gcc_assert (size <= HOST_BITS_PER_WIDE_INT);
2467 min_val = -((unsigned HOST_WIDE_INT) 1 << (size - 1));
2468 max_val = ((unsigned HOST_WIDE_INT) 1 << (size - 1)) - 1;
2473 max_val = ((unsigned HOST_WIDE_INT) 1 << (size - 1) << 1) - 1;
2476 *mmin = gen_int_mode (min_val, target_mode);
2477 *mmax = gen_int_mode (max_val, target_mode);
2480 #include "gt-stor-layout.h"