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
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"
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;
52 /* ... and its original value in bytes, specified via -fpack-struct=<value>. */
53 unsigned int initial_max_fld_align = TARGET_DEFAULT_PACK_STRUCT;
55 /* Nonzero if all REFERENCE_TYPEs are internal and hence should be
56 allocated in Pmode, not ptr_mode. Set only by internal_reference_types
57 called only by a front end. */
58 static int reference_types_internal = 0;
60 static tree self_referential_size (tree);
61 static void finalize_record_size (record_layout_info);
62 static void finalize_type_size (tree);
63 static void place_union_field (record_layout_info, tree);
64 #if defined (PCC_BITFIELD_TYPE_MATTERS) || defined (BITFIELD_NBYTES_LIMITED)
65 static int excess_unit_span (HOST_WIDE_INT, HOST_WIDE_INT, HOST_WIDE_INT,
68 extern void debug_rli (record_layout_info);
70 /* SAVE_EXPRs for sizes of types and decls, waiting to be expanded. */
72 static GTY(()) tree pending_sizes;
74 /* Show that REFERENCE_TYPES are internal and should be Pmode. Called only
78 internal_reference_types (void)
80 reference_types_internal = 1;
83 /* Get a list of all the objects put on the pending sizes list. */
86 get_pending_sizes (void)
88 tree chain = pending_sizes;
94 /* Add EXPR to the pending sizes list. */
97 put_pending_size (tree expr)
99 /* Strip any simple arithmetic from EXPR to see if it has an underlying
101 expr = skip_simple_arithmetic (expr);
103 if (TREE_CODE (expr) == SAVE_EXPR)
104 pending_sizes = tree_cons (NULL_TREE, expr, pending_sizes);
107 /* Put a chain of objects into the pending sizes list, which must be
111 put_pending_sizes (tree chain)
113 gcc_assert (!pending_sizes);
114 pending_sizes = chain;
117 /* Given a size SIZE that may not be a constant, return a SAVE_EXPR
118 to serve as the actual size-expression for a type or decl. */
121 variable_size (tree size)
126 if (TREE_CONSTANT (size))
129 /* If the size is self-referential, we can't make a SAVE_EXPR (see
130 save_expr for the rationale). But we can do something else. */
131 if (CONTAINS_PLACEHOLDER_P (size))
132 return self_referential_size (size);
134 /* If the language-processor is to take responsibility for variable-sized
135 items (e.g., languages which have elaboration procedures like Ada),
136 just return SIZE unchanged. */
137 if (lang_hooks.decls.global_bindings_p () < 0)
140 size = save_expr (size);
142 /* If an array with a variable number of elements is declared, and
143 the elements require destruction, we will emit a cleanup for the
144 array. That cleanup is run both on normal exit from the block
145 and in the exception-handler for the block. Normally, when code
146 is used in both ordinary code and in an exception handler it is
147 `unsaved', i.e., all SAVE_EXPRs are recalculated. However, we do
148 not wish to do that here; the array-size is the same in both
150 save = skip_simple_arithmetic (size);
152 if (cfun && cfun->dont_save_pending_sizes_p)
153 /* The front-end doesn't want us to keep a list of the expressions
154 that determine sizes for variable size objects. Trust it. */
157 if (lang_hooks.decls.global_bindings_p ())
159 if (TREE_CONSTANT (size))
160 error ("type size can%'t be explicitly evaluated");
162 error ("variable-size type declared outside of any function");
164 return size_one_node;
167 put_pending_size (save);
172 /* An array of functions used for self-referential size computation. */
173 static GTY(()) VEC (tree, gc) *size_functions;
175 /* Similar to copy_tree_r but do not copy component references involving
176 PLACEHOLDER_EXPRs. These nodes are spotted in find_placeholder_in_expr
177 and substituted in substitute_in_expr. */
180 copy_self_referential_tree_r (tree *tp, int *walk_subtrees, void *data)
182 enum tree_code code = TREE_CODE (*tp);
184 /* Stop at types, decls, constants like copy_tree_r. */
185 if (TREE_CODE_CLASS (code) == tcc_type
186 || TREE_CODE_CLASS (code) == tcc_declaration
187 || TREE_CODE_CLASS (code) == tcc_constant)
193 /* This is the pattern built in ada/make_aligning_type. */
194 else if (code == ADDR_EXPR
195 && TREE_CODE (TREE_OPERAND (*tp, 0)) == PLACEHOLDER_EXPR)
201 /* Default case: the component reference. */
202 else if (code == COMPONENT_REF)
205 for (inner = TREE_OPERAND (*tp, 0);
206 REFERENCE_CLASS_P (inner);
207 inner = TREE_OPERAND (inner, 0))
210 if (TREE_CODE (inner) == PLACEHOLDER_EXPR)
217 /* We're not supposed to have them in self-referential size trees
218 because we wouldn't properly control when they are evaluated.
219 However, not creating superfluous SAVE_EXPRs requires accurate
220 tracking of readonly-ness all the way down to here, which we
221 cannot always guarantee in practice. So punt in this case. */
222 else if (code == SAVE_EXPR)
223 return error_mark_node;
225 return copy_tree_r (tp, walk_subtrees, data);
228 /* Given a SIZE expression that is self-referential, return an equivalent
229 expression to serve as the actual size expression for a type. */
232 self_referential_size (tree size)
234 static unsigned HOST_WIDE_INT fnno = 0;
235 VEC (tree, heap) *self_refs = NULL;
236 tree param_type_list = NULL, param_decl_list = NULL, arg_list = NULL;
237 tree t, ref, return_type, fntype, fnname, fndecl;
241 /* Do not factor out simple operations. */
242 t = skip_simple_arithmetic (size);
243 if (TREE_CODE (t) == CALL_EXPR)
246 /* Collect the list of self-references in the expression. */
247 find_placeholder_in_expr (size, &self_refs);
248 gcc_assert (VEC_length (tree, self_refs) > 0);
250 /* Obtain a private copy of the expression. */
252 if (walk_tree (&t, copy_self_referential_tree_r, NULL, NULL) != NULL_TREE)
256 /* Build the parameter and argument lists in parallel; also
257 substitute the former for the latter in the expression. */
258 for (i = 0; VEC_iterate (tree, self_refs, i, ref); i++)
260 tree subst, param_name, param_type, param_decl;
264 /* We shouldn't have true variables here. */
265 gcc_assert (TREE_READONLY (ref));
268 /* This is the pattern built in ada/make_aligning_type. */
269 else if (TREE_CODE (ref) == ADDR_EXPR)
271 /* Default case: the component reference. */
273 subst = TREE_OPERAND (ref, 1);
275 sprintf (buf, "p%d", i);
276 param_name = get_identifier (buf);
277 param_type = TREE_TYPE (ref);
279 = build_decl (input_location, PARM_DECL, param_name, param_type);
280 if (targetm.calls.promote_prototypes (NULL_TREE)
281 && INTEGRAL_TYPE_P (param_type)
282 && TYPE_PRECISION (param_type) < TYPE_PRECISION (integer_type_node))
283 DECL_ARG_TYPE (param_decl) = integer_type_node;
285 DECL_ARG_TYPE (param_decl) = param_type;
286 DECL_ARTIFICIAL (param_decl) = 1;
287 TREE_READONLY (param_decl) = 1;
289 size = substitute_in_expr (size, subst, param_decl);
291 param_type_list = tree_cons (NULL_TREE, param_type, param_type_list);
292 param_decl_list = chainon (param_decl, param_decl_list);
293 arg_list = tree_cons (NULL_TREE, ref, arg_list);
296 VEC_free (tree, heap, self_refs);
298 /* Append 'void' to indicate that the number of parameters is fixed. */
299 param_type_list = tree_cons (NULL_TREE, void_type_node, param_type_list);
301 /* The 3 lists have been created in reverse order. */
302 param_type_list = nreverse (param_type_list);
303 param_decl_list = nreverse (param_decl_list);
304 arg_list = nreverse (arg_list);
306 /* Build the function type. */
307 return_type = TREE_TYPE (size);
308 fntype = build_function_type (return_type, param_type_list);
310 /* Build the function declaration. */
311 sprintf (buf, "SZ"HOST_WIDE_INT_PRINT_UNSIGNED, fnno++);
312 fnname = get_file_function_name (buf);
313 fndecl = build_decl (input_location, FUNCTION_DECL, fnname, fntype);
314 for (t = param_decl_list; t; t = TREE_CHAIN (t))
315 DECL_CONTEXT (t) = fndecl;
316 DECL_ARGUMENTS (fndecl) = param_decl_list;
318 = build_decl (input_location, RESULT_DECL, 0, return_type);
319 DECL_CONTEXT (DECL_RESULT (fndecl)) = fndecl;
321 /* The function has been created by the compiler and we don't
322 want to emit debug info for it. */
323 DECL_ARTIFICIAL (fndecl) = 1;
324 DECL_IGNORED_P (fndecl) = 1;
326 /* It is supposed to be "const" and never throw. */
327 TREE_READONLY (fndecl) = 1;
328 TREE_NOTHROW (fndecl) = 1;
330 /* We want it to be inlined when this is deemed profitable, as
331 well as discarded if every call has been integrated. */
332 DECL_DECLARED_INLINE_P (fndecl) = 1;
334 /* It is made up of a unique return statement. */
335 DECL_INITIAL (fndecl) = make_node (BLOCK);
336 BLOCK_SUPERCONTEXT (DECL_INITIAL (fndecl)) = fndecl;
337 t = build2 (MODIFY_EXPR, return_type, DECL_RESULT (fndecl), size);
338 DECL_SAVED_TREE (fndecl) = build1 (RETURN_EXPR, void_type_node, t);
339 TREE_STATIC (fndecl) = 1;
341 /* Put it onto the list of size functions. */
342 VEC_safe_push (tree, gc, size_functions, fndecl);
344 /* Replace the original expression with a call to the size function. */
345 return build_function_call_expr (fndecl, arg_list);
348 /* Take, queue and compile all the size functions. It is essential that
349 the size functions be gimplified at the very end of the compilation
350 in order to guarantee transparent handling of self-referential sizes.
351 Otherwise the GENERIC inliner would not be able to inline them back
352 at each of their call sites, thus creating artificial non-constant
353 size expressions which would trigger nasty problems later on. */
356 finalize_size_functions (void)
361 for (i = 0; VEC_iterate(tree, size_functions, i, fndecl); i++)
363 dump_function (TDI_original, fndecl);
364 gimplify_function_tree (fndecl);
365 dump_function (TDI_generic, fndecl);
366 cgraph_finalize_function (fndecl, false);
369 VEC_free (tree, gc, size_functions);
372 #ifndef MAX_FIXED_MODE_SIZE
373 #define MAX_FIXED_MODE_SIZE GET_MODE_BITSIZE (DImode)
376 /* Return the machine mode to use for a nonscalar of SIZE bits. The
377 mode must be in class MCLASS, and have exactly that many value bits;
378 it may have padding as well. If LIMIT is nonzero, modes of wider
379 than MAX_FIXED_MODE_SIZE will not be used. */
382 mode_for_size (unsigned int size, enum mode_class mclass, int limit)
384 enum machine_mode mode;
386 if (limit && size > MAX_FIXED_MODE_SIZE)
389 /* Get the first mode which has this size, in the specified class. */
390 for (mode = GET_CLASS_NARROWEST_MODE (mclass); mode != VOIDmode;
391 mode = GET_MODE_WIDER_MODE (mode))
392 if (GET_MODE_PRECISION (mode) == size)
398 /* Similar, except passed a tree node. */
401 mode_for_size_tree (const_tree size, enum mode_class mclass, int limit)
403 unsigned HOST_WIDE_INT uhwi;
406 if (!host_integerp (size, 1))
408 uhwi = tree_low_cst (size, 1);
412 return mode_for_size (ui, mclass, limit);
415 /* Similar, but never return BLKmode; return the narrowest mode that
416 contains at least the requested number of value bits. */
419 smallest_mode_for_size (unsigned int size, enum mode_class mclass)
421 enum machine_mode mode;
423 /* Get the first mode which has at least this size, in the
425 for (mode = GET_CLASS_NARROWEST_MODE (mclass); mode != VOIDmode;
426 mode = GET_MODE_WIDER_MODE (mode))
427 if (GET_MODE_PRECISION (mode) >= size)
433 /* Find an integer mode of the exact same size, or BLKmode on failure. */
436 int_mode_for_mode (enum machine_mode mode)
438 switch (GET_MODE_CLASS (mode))
441 case MODE_PARTIAL_INT:
444 case MODE_COMPLEX_INT:
445 case MODE_COMPLEX_FLOAT:
447 case MODE_DECIMAL_FLOAT:
448 case MODE_VECTOR_INT:
449 case MODE_VECTOR_FLOAT:
454 case MODE_VECTOR_FRACT:
455 case MODE_VECTOR_ACCUM:
456 case MODE_VECTOR_UFRACT:
457 case MODE_VECTOR_UACCUM:
458 mode = mode_for_size (GET_MODE_BITSIZE (mode), MODE_INT, 0);
465 /* ... fall through ... */
475 /* Return the alignment of MODE. This will be bounded by 1 and
476 BIGGEST_ALIGNMENT. */
479 get_mode_alignment (enum machine_mode mode)
481 return MIN (BIGGEST_ALIGNMENT, MAX (1, mode_base_align[mode]*BITS_PER_UNIT));
485 /* Subroutine of layout_decl: Force alignment required for the data type.
486 But if the decl itself wants greater alignment, don't override that. */
489 do_type_align (tree type, tree decl)
491 if (TYPE_ALIGN (type) > DECL_ALIGN (decl))
493 DECL_ALIGN (decl) = TYPE_ALIGN (type);
494 if (TREE_CODE (decl) == FIELD_DECL)
495 DECL_USER_ALIGN (decl) = TYPE_USER_ALIGN (type);
499 /* Set the size, mode and alignment of a ..._DECL node.
500 TYPE_DECL does need this for C++.
501 Note that LABEL_DECL and CONST_DECL nodes do not need this,
502 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
503 Don't call layout_decl for them.
505 KNOWN_ALIGN is the amount of alignment we can assume this
506 decl has with no special effort. It is relevant only for FIELD_DECLs
507 and depends on the previous fields.
508 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
509 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
510 the record will be aligned to suit. */
513 layout_decl (tree decl, unsigned int known_align)
515 tree type = TREE_TYPE (decl);
516 enum tree_code code = TREE_CODE (decl);
519 if (code == CONST_DECL)
522 gcc_assert (code == VAR_DECL || code == PARM_DECL || code == RESULT_DECL
523 || code == TYPE_DECL ||code == FIELD_DECL);
525 rtl = DECL_RTL_IF_SET (decl);
527 if (type == error_mark_node)
528 type = void_type_node;
530 /* Usually the size and mode come from the data type without change,
531 however, the front-end may set the explicit width of the field, so its
532 size may not be the same as the size of its type. This happens with
533 bitfields, of course (an `int' bitfield may be only 2 bits, say), but it
534 also happens with other fields. For example, the C++ front-end creates
535 zero-sized fields corresponding to empty base classes, and depends on
536 layout_type setting DECL_FIELD_BITPOS correctly for the field. Set the
537 size in bytes from the size in bits. If we have already set the mode,
538 don't set it again since we can be called twice for FIELD_DECLs. */
540 DECL_UNSIGNED (decl) = TYPE_UNSIGNED (type);
541 if (DECL_MODE (decl) == VOIDmode)
542 DECL_MODE (decl) = TYPE_MODE (type);
544 if (DECL_SIZE (decl) == 0)
546 DECL_SIZE (decl) = TYPE_SIZE (type);
547 DECL_SIZE_UNIT (decl) = TYPE_SIZE_UNIT (type);
549 else if (DECL_SIZE_UNIT (decl) == 0)
550 DECL_SIZE_UNIT (decl)
551 = fold_convert (sizetype, size_binop (CEIL_DIV_EXPR, DECL_SIZE (decl),
554 if (code != FIELD_DECL)
555 /* For non-fields, update the alignment from the type. */
556 do_type_align (type, decl);
558 /* For fields, it's a bit more complicated... */
560 bool old_user_align = DECL_USER_ALIGN (decl);
561 bool zero_bitfield = false;
562 bool packed_p = DECL_PACKED (decl);
565 if (DECL_BIT_FIELD (decl))
567 DECL_BIT_FIELD_TYPE (decl) = type;
569 /* A zero-length bit-field affects the alignment of the next
570 field. In essence such bit-fields are not influenced by
571 any packing due to #pragma pack or attribute packed. */
572 if (integer_zerop (DECL_SIZE (decl))
573 && ! targetm.ms_bitfield_layout_p (DECL_FIELD_CONTEXT (decl)))
575 zero_bitfield = true;
577 #ifdef PCC_BITFIELD_TYPE_MATTERS
578 if (PCC_BITFIELD_TYPE_MATTERS)
579 do_type_align (type, decl);
583 #ifdef EMPTY_FIELD_BOUNDARY
584 if (EMPTY_FIELD_BOUNDARY > DECL_ALIGN (decl))
586 DECL_ALIGN (decl) = EMPTY_FIELD_BOUNDARY;
587 DECL_USER_ALIGN (decl) = 0;
593 /* See if we can use an ordinary integer mode for a bit-field.
594 Conditions are: a fixed size that is correct for another mode
595 and occupying a complete byte or bytes on proper boundary. */
596 if (TYPE_SIZE (type) != 0
597 && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
598 && GET_MODE_CLASS (TYPE_MODE (type)) == MODE_INT)
600 enum machine_mode xmode
601 = mode_for_size_tree (DECL_SIZE (decl), MODE_INT, 1);
602 unsigned int xalign = GET_MODE_ALIGNMENT (xmode);
605 && !(xalign > BITS_PER_UNIT && DECL_PACKED (decl))
606 && (known_align == 0 || known_align >= xalign))
608 DECL_ALIGN (decl) = MAX (xalign, DECL_ALIGN (decl));
609 DECL_MODE (decl) = xmode;
610 DECL_BIT_FIELD (decl) = 0;
614 /* Turn off DECL_BIT_FIELD if we won't need it set. */
615 if (TYPE_MODE (type) == BLKmode && DECL_MODE (decl) == BLKmode
616 && known_align >= TYPE_ALIGN (type)
617 && DECL_ALIGN (decl) >= TYPE_ALIGN (type))
618 DECL_BIT_FIELD (decl) = 0;
620 else if (packed_p && DECL_USER_ALIGN (decl))
621 /* Don't touch DECL_ALIGN. For other packed fields, go ahead and
622 round up; we'll reduce it again below. We want packing to
623 supersede USER_ALIGN inherited from the type, but defer to
624 alignment explicitly specified on the field decl. */;
626 do_type_align (type, decl);
628 /* If the field is packed and not explicitly aligned, give it the
629 minimum alignment. Note that do_type_align may set
630 DECL_USER_ALIGN, so we need to check old_user_align instead. */
633 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), BITS_PER_UNIT);
635 if (! packed_p && ! DECL_USER_ALIGN (decl))
637 /* Some targets (i.e. i386, VMS) limit struct field alignment
638 to a lower boundary than alignment of variables unless
639 it was overridden by attribute aligned. */
640 #ifdef BIGGEST_FIELD_ALIGNMENT
642 = MIN (DECL_ALIGN (decl), (unsigned) BIGGEST_FIELD_ALIGNMENT);
644 #ifdef ADJUST_FIELD_ALIGN
645 DECL_ALIGN (decl) = ADJUST_FIELD_ALIGN (decl, DECL_ALIGN (decl));
650 mfa = initial_max_fld_align * BITS_PER_UNIT;
652 mfa = maximum_field_alignment;
653 /* Should this be controlled by DECL_USER_ALIGN, too? */
655 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), mfa);
658 /* Evaluate nonconstant size only once, either now or as soon as safe. */
659 if (DECL_SIZE (decl) != 0 && TREE_CODE (DECL_SIZE (decl)) != INTEGER_CST)
660 DECL_SIZE (decl) = variable_size (DECL_SIZE (decl));
661 if (DECL_SIZE_UNIT (decl) != 0
662 && TREE_CODE (DECL_SIZE_UNIT (decl)) != INTEGER_CST)
663 DECL_SIZE_UNIT (decl) = variable_size (DECL_SIZE_UNIT (decl));
665 /* If requested, warn about definitions of large data objects. */
667 && (code == VAR_DECL || code == PARM_DECL)
668 && ! DECL_EXTERNAL (decl))
670 tree size = DECL_SIZE_UNIT (decl);
672 if (size != 0 && TREE_CODE (size) == INTEGER_CST
673 && compare_tree_int (size, larger_than_size) > 0)
675 int size_as_int = TREE_INT_CST_LOW (size);
677 if (compare_tree_int (size, size_as_int) == 0)
678 warning (OPT_Wlarger_than_eq, "size of %q+D is %d bytes", decl, size_as_int);
680 warning (OPT_Wlarger_than_eq, "size of %q+D is larger than %wd bytes",
681 decl, larger_than_size);
685 /* If the RTL was already set, update its mode and mem attributes. */
688 PUT_MODE (rtl, DECL_MODE (decl));
689 SET_DECL_RTL (decl, 0);
690 set_mem_attributes (rtl, decl, 1);
691 SET_DECL_RTL (decl, rtl);
695 /* Given a VAR_DECL, PARM_DECL or RESULT_DECL, clears the results of
696 a previous call to layout_decl and calls it again. */
699 relayout_decl (tree decl)
701 DECL_SIZE (decl) = DECL_SIZE_UNIT (decl) = 0;
702 DECL_MODE (decl) = VOIDmode;
703 if (!DECL_USER_ALIGN (decl))
704 DECL_ALIGN (decl) = 0;
705 SET_DECL_RTL (decl, 0);
707 layout_decl (decl, 0);
710 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
711 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
712 is to be passed to all other layout functions for this record. It is the
713 responsibility of the caller to call `free' for the storage returned.
714 Note that garbage collection is not permitted until we finish laying
718 start_record_layout (tree t)
720 record_layout_info rli = XNEW (struct record_layout_info_s);
724 /* If the type has a minimum specified alignment (via an attribute
725 declaration, for example) use it -- otherwise, start with a
726 one-byte alignment. */
727 rli->record_align = MAX (BITS_PER_UNIT, TYPE_ALIGN (t));
728 rli->unpacked_align = rli->record_align;
729 rli->offset_align = MAX (rli->record_align, BIGGEST_ALIGNMENT);
731 #ifdef STRUCTURE_SIZE_BOUNDARY
732 /* Packed structures don't need to have minimum size. */
733 if (! TYPE_PACKED (t))
737 /* #pragma pack overrides STRUCTURE_SIZE_BOUNDARY. */
738 tmp = (unsigned) STRUCTURE_SIZE_BOUNDARY;
739 if (maximum_field_alignment != 0)
740 tmp = MIN (tmp, maximum_field_alignment);
741 rli->record_align = MAX (rli->record_align, tmp);
745 rli->offset = size_zero_node;
746 rli->bitpos = bitsize_zero_node;
748 rli->pending_statics = 0;
749 rli->packed_maybe_necessary = 0;
750 rli->remaining_in_alignment = 0;
755 /* These four routines perform computations that convert between
756 the offset/bitpos forms and byte and bit offsets. */
759 bit_from_pos (tree offset, tree bitpos)
761 return size_binop (PLUS_EXPR, bitpos,
762 size_binop (MULT_EXPR,
763 fold_convert (bitsizetype, offset),
768 byte_from_pos (tree offset, tree bitpos)
770 return size_binop (PLUS_EXPR, offset,
771 fold_convert (sizetype,
772 size_binop (TRUNC_DIV_EXPR, bitpos,
773 bitsize_unit_node)));
777 pos_from_bit (tree *poffset, tree *pbitpos, unsigned int off_align,
780 *poffset = size_binop (MULT_EXPR,
781 fold_convert (sizetype,
782 size_binop (FLOOR_DIV_EXPR, pos,
783 bitsize_int (off_align))),
784 size_int (off_align / BITS_PER_UNIT));
785 *pbitpos = size_binop (FLOOR_MOD_EXPR, pos, bitsize_int (off_align));
788 /* Given a pointer to bit and byte offsets and an offset alignment,
789 normalize the offsets so they are within the alignment. */
792 normalize_offset (tree *poffset, tree *pbitpos, unsigned int off_align)
794 /* If the bit position is now larger than it should be, adjust it
796 if (compare_tree_int (*pbitpos, off_align) >= 0)
798 tree extra_aligns = size_binop (FLOOR_DIV_EXPR, *pbitpos,
799 bitsize_int (off_align));
802 = size_binop (PLUS_EXPR, *poffset,
803 size_binop (MULT_EXPR,
804 fold_convert (sizetype, extra_aligns),
805 size_int (off_align / BITS_PER_UNIT)));
808 = size_binop (FLOOR_MOD_EXPR, *pbitpos, bitsize_int (off_align));
812 /* Print debugging information about the information in RLI. */
815 debug_rli (record_layout_info rli)
817 print_node_brief (stderr, "type", rli->t, 0);
818 print_node_brief (stderr, "\noffset", rli->offset, 0);
819 print_node_brief (stderr, " bitpos", rli->bitpos, 0);
821 fprintf (stderr, "\naligns: rec = %u, unpack = %u, off = %u\n",
822 rli->record_align, rli->unpacked_align,
825 /* The ms_struct code is the only that uses this. */
826 if (targetm.ms_bitfield_layout_p (rli->t))
827 fprintf (stderr, "remaining in alignment = %u\n", rli->remaining_in_alignment);
829 if (rli->packed_maybe_necessary)
830 fprintf (stderr, "packed may be necessary\n");
832 if (rli->pending_statics)
834 fprintf (stderr, "pending statics:\n");
835 debug_tree (rli->pending_statics);
839 /* Given an RLI with a possibly-incremented BITPOS, adjust OFFSET and
840 BITPOS if necessary to keep BITPOS below OFFSET_ALIGN. */
843 normalize_rli (record_layout_info rli)
845 normalize_offset (&rli->offset, &rli->bitpos, rli->offset_align);
848 /* Returns the size in bytes allocated so far. */
851 rli_size_unit_so_far (record_layout_info rli)
853 return byte_from_pos (rli->offset, rli->bitpos);
856 /* Returns the size in bits allocated so far. */
859 rli_size_so_far (record_layout_info rli)
861 return bit_from_pos (rli->offset, rli->bitpos);
864 /* FIELD is about to be added to RLI->T. The alignment (in bits) of
865 the next available location within the record is given by KNOWN_ALIGN.
866 Update the variable alignment fields in RLI, and return the alignment
867 to give the FIELD. */
870 update_alignment_for_field (record_layout_info rli, tree field,
871 unsigned int known_align)
873 /* The alignment required for FIELD. */
874 unsigned int desired_align;
875 /* The type of this field. */
876 tree type = TREE_TYPE (field);
877 /* True if the field was explicitly aligned by the user. */
881 /* Do not attempt to align an ERROR_MARK node */
882 if (TREE_CODE (type) == ERROR_MARK)
885 /* Lay out the field so we know what alignment it needs. */
886 layout_decl (field, known_align);
887 desired_align = DECL_ALIGN (field);
888 user_align = DECL_USER_ALIGN (field);
890 is_bitfield = (type != error_mark_node
891 && DECL_BIT_FIELD_TYPE (field)
892 && ! integer_zerop (TYPE_SIZE (type)));
894 /* Record must have at least as much alignment as any field.
895 Otherwise, the alignment of the field within the record is
897 if (targetm.ms_bitfield_layout_p (rli->t))
899 /* Here, the alignment of the underlying type of a bitfield can
900 affect the alignment of a record; even a zero-sized field
901 can do this. The alignment should be to the alignment of
902 the type, except that for zero-size bitfields this only
903 applies if there was an immediately prior, nonzero-size
904 bitfield. (That's the way it is, experimentally.) */
905 if ((!is_bitfield && !DECL_PACKED (field))
906 || (!integer_zerop (DECL_SIZE (field))
907 ? !DECL_PACKED (field)
909 && DECL_BIT_FIELD_TYPE (rli->prev_field)
910 && ! integer_zerop (DECL_SIZE (rli->prev_field)))))
912 unsigned int type_align = TYPE_ALIGN (type);
913 type_align = MAX (type_align, desired_align);
914 if (maximum_field_alignment != 0)
915 type_align = MIN (type_align, maximum_field_alignment);
916 rli->record_align = MAX (rli->record_align, type_align);
917 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
920 #ifdef PCC_BITFIELD_TYPE_MATTERS
921 else if (is_bitfield && PCC_BITFIELD_TYPE_MATTERS)
923 /* Named bit-fields cause the entire structure to have the
924 alignment implied by their type. Some targets also apply the same
925 rules to unnamed bitfields. */
926 if (DECL_NAME (field) != 0
927 || targetm.align_anon_bitfield ())
929 unsigned int type_align = TYPE_ALIGN (type);
931 #ifdef ADJUST_FIELD_ALIGN
932 if (! TYPE_USER_ALIGN (type))
933 type_align = ADJUST_FIELD_ALIGN (field, type_align);
936 /* Targets might chose to handle unnamed and hence possibly
937 zero-width bitfield. Those are not influenced by #pragmas
938 or packed attributes. */
939 if (integer_zerop (DECL_SIZE (field)))
941 if (initial_max_fld_align)
942 type_align = MIN (type_align,
943 initial_max_fld_align * BITS_PER_UNIT);
945 else if (maximum_field_alignment != 0)
946 type_align = MIN (type_align, maximum_field_alignment);
947 else if (DECL_PACKED (field))
948 type_align = MIN (type_align, BITS_PER_UNIT);
950 /* The alignment of the record is increased to the maximum
951 of the current alignment, the alignment indicated on the
952 field (i.e., the alignment specified by an __aligned__
953 attribute), and the alignment indicated by the type of
955 rli->record_align = MAX (rli->record_align, desired_align);
956 rli->record_align = MAX (rli->record_align, type_align);
959 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
960 user_align |= TYPE_USER_ALIGN (type);
966 rli->record_align = MAX (rli->record_align, desired_align);
967 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
970 TYPE_USER_ALIGN (rli->t) |= user_align;
972 return desired_align;
975 /* Called from place_field to handle unions. */
978 place_union_field (record_layout_info rli, tree field)
980 update_alignment_for_field (rli, field, /*known_align=*/0);
982 DECL_FIELD_OFFSET (field) = size_zero_node;
983 DECL_FIELD_BIT_OFFSET (field) = bitsize_zero_node;
984 SET_DECL_OFFSET_ALIGN (field, BIGGEST_ALIGNMENT);
986 /* If this is an ERROR_MARK return *after* having set the
987 field at the start of the union. This helps when parsing
989 if (TREE_CODE (TREE_TYPE (field)) == ERROR_MARK)
992 /* We assume the union's size will be a multiple of a byte so we don't
993 bother with BITPOS. */
994 if (TREE_CODE (rli->t) == UNION_TYPE)
995 rli->offset = size_binop (MAX_EXPR, rli->offset, DECL_SIZE_UNIT (field));
996 else if (TREE_CODE (rli->t) == QUAL_UNION_TYPE)
997 rli->offset = fold_build3 (COND_EXPR, sizetype,
998 DECL_QUALIFIER (field),
999 DECL_SIZE_UNIT (field), rli->offset);
1002 #if defined (PCC_BITFIELD_TYPE_MATTERS) || defined (BITFIELD_NBYTES_LIMITED)
1003 /* A bitfield of SIZE with a required access alignment of ALIGN is allocated
1004 at BYTE_OFFSET / BIT_OFFSET. Return nonzero if the field would span more
1005 units of alignment than the underlying TYPE. */
1007 excess_unit_span (HOST_WIDE_INT byte_offset, HOST_WIDE_INT bit_offset,
1008 HOST_WIDE_INT size, HOST_WIDE_INT align, tree type)
1010 /* Note that the calculation of OFFSET might overflow; we calculate it so
1011 that we still get the right result as long as ALIGN is a power of two. */
1012 unsigned HOST_WIDE_INT offset = byte_offset * BITS_PER_UNIT + bit_offset;
1014 offset = offset % align;
1015 return ((offset + size + align - 1) / align
1016 > ((unsigned HOST_WIDE_INT) tree_low_cst (TYPE_SIZE (type), 1)
1021 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
1022 is a FIELD_DECL to be added after those fields already present in
1023 T. (FIELD is not actually added to the TYPE_FIELDS list here;
1024 callers that desire that behavior must manually perform that step.) */
1027 place_field (record_layout_info rli, tree field)
1029 /* The alignment required for FIELD. */
1030 unsigned int desired_align;
1031 /* The alignment FIELD would have if we just dropped it into the
1032 record as it presently stands. */
1033 unsigned int known_align;
1034 unsigned int actual_align;
1035 /* The type of this field. */
1036 tree type = TREE_TYPE (field);
1038 gcc_assert (TREE_CODE (field) != ERROR_MARK);
1040 /* If FIELD is static, then treat it like a separate variable, not
1041 really like a structure field. If it is a FUNCTION_DECL, it's a
1042 method. In both cases, all we do is lay out the decl, and we do
1043 it *after* the record is laid out. */
1044 if (TREE_CODE (field) == VAR_DECL)
1046 rli->pending_statics = tree_cons (NULL_TREE, field,
1047 rli->pending_statics);
1051 /* Enumerators and enum types which are local to this class need not
1052 be laid out. Likewise for initialized constant fields. */
1053 else if (TREE_CODE (field) != FIELD_DECL)
1056 /* Unions are laid out very differently than records, so split
1057 that code off to another function. */
1058 else if (TREE_CODE (rli->t) != RECORD_TYPE)
1060 place_union_field (rli, field);
1064 else if (TREE_CODE (type) == ERROR_MARK)
1066 /* Place this field at the current allocation position, so we
1067 maintain monotonicity. */
1068 DECL_FIELD_OFFSET (field) = rli->offset;
1069 DECL_FIELD_BIT_OFFSET (field) = rli->bitpos;
1070 SET_DECL_OFFSET_ALIGN (field, rli->offset_align);
1074 /* Work out the known alignment so far. Note that A & (-A) is the
1075 value of the least-significant bit in A that is one. */
1076 if (! integer_zerop (rli->bitpos))
1077 known_align = (tree_low_cst (rli->bitpos, 1)
1078 & - tree_low_cst (rli->bitpos, 1));
1079 else if (integer_zerop (rli->offset))
1081 else if (host_integerp (rli->offset, 1))
1082 known_align = (BITS_PER_UNIT
1083 * (tree_low_cst (rli->offset, 1)
1084 & - tree_low_cst (rli->offset, 1)));
1086 known_align = rli->offset_align;
1088 desired_align = update_alignment_for_field (rli, field, known_align);
1089 if (known_align == 0)
1090 known_align = MAX (BIGGEST_ALIGNMENT, rli->record_align);
1092 if (warn_packed && DECL_PACKED (field))
1094 if (known_align >= TYPE_ALIGN (type))
1096 if (TYPE_ALIGN (type) > desired_align)
1098 if (STRICT_ALIGNMENT)
1099 warning (OPT_Wattributes, "packed attribute causes "
1100 "inefficient alignment for %q+D", field);
1102 warning (OPT_Wattributes, "packed attribute is "
1103 "unnecessary for %q+D", field);
1107 rli->packed_maybe_necessary = 1;
1110 /* Does this field automatically have alignment it needs by virtue
1111 of the fields that precede it and the record's own alignment?
1112 We already align ms_struct fields, so don't re-align them. */
1113 if (known_align < desired_align
1114 && !targetm.ms_bitfield_layout_p (rli->t))
1116 /* No, we need to skip space before this field.
1117 Bump the cumulative size to multiple of field alignment. */
1119 warning (OPT_Wpadded, "padding struct to align %q+D", field);
1121 /* If the alignment is still within offset_align, just align
1122 the bit position. */
1123 if (desired_align < rli->offset_align)
1124 rli->bitpos = round_up (rli->bitpos, desired_align);
1127 /* First adjust OFFSET by the partial bits, then align. */
1129 = size_binop (PLUS_EXPR, rli->offset,
1130 fold_convert (sizetype,
1131 size_binop (CEIL_DIV_EXPR, rli->bitpos,
1132 bitsize_unit_node)));
1133 rli->bitpos = bitsize_zero_node;
1135 rli->offset = round_up (rli->offset, desired_align / BITS_PER_UNIT);
1138 if (! TREE_CONSTANT (rli->offset))
1139 rli->offset_align = desired_align;
1143 /* Handle compatibility with PCC. Note that if the record has any
1144 variable-sized fields, we need not worry about compatibility. */
1145 #ifdef PCC_BITFIELD_TYPE_MATTERS
1146 if (PCC_BITFIELD_TYPE_MATTERS
1147 && ! targetm.ms_bitfield_layout_p (rli->t)
1148 && TREE_CODE (field) == FIELD_DECL
1149 && type != error_mark_node
1150 && DECL_BIT_FIELD (field)
1151 && (! DECL_PACKED (field)
1152 /* Enter for these packed fields only to issue a warning. */
1153 || TYPE_ALIGN (type) <= BITS_PER_UNIT)
1154 && maximum_field_alignment == 0
1155 && ! integer_zerop (DECL_SIZE (field))
1156 && host_integerp (DECL_SIZE (field), 1)
1157 && host_integerp (rli->offset, 1)
1158 && host_integerp (TYPE_SIZE (type), 1))
1160 unsigned int type_align = TYPE_ALIGN (type);
1161 tree dsize = DECL_SIZE (field);
1162 HOST_WIDE_INT field_size = tree_low_cst (dsize, 1);
1163 HOST_WIDE_INT offset = tree_low_cst (rli->offset, 0);
1164 HOST_WIDE_INT bit_offset = tree_low_cst (rli->bitpos, 0);
1166 #ifdef ADJUST_FIELD_ALIGN
1167 if (! TYPE_USER_ALIGN (type))
1168 type_align = ADJUST_FIELD_ALIGN (field, type_align);
1171 /* A bit field may not span more units of alignment of its type
1172 than its type itself. Advance to next boundary if necessary. */
1173 if (excess_unit_span (offset, bit_offset, field_size, type_align, type))
1175 if (DECL_PACKED (field))
1177 if (warn_packed_bitfield_compat == 1)
1180 "Offset of packed bit-field %qD has changed in GCC 4.4",
1184 rli->bitpos = round_up (rli->bitpos, type_align);
1187 if (! DECL_PACKED (field))
1188 TYPE_USER_ALIGN (rli->t) |= TYPE_USER_ALIGN (type);
1192 #ifdef BITFIELD_NBYTES_LIMITED
1193 if (BITFIELD_NBYTES_LIMITED
1194 && ! targetm.ms_bitfield_layout_p (rli->t)
1195 && TREE_CODE (field) == FIELD_DECL
1196 && type != error_mark_node
1197 && DECL_BIT_FIELD_TYPE (field)
1198 && ! DECL_PACKED (field)
1199 && ! integer_zerop (DECL_SIZE (field))
1200 && host_integerp (DECL_SIZE (field), 1)
1201 && host_integerp (rli->offset, 1)
1202 && host_integerp (TYPE_SIZE (type), 1))
1204 unsigned int type_align = TYPE_ALIGN (type);
1205 tree dsize = DECL_SIZE (field);
1206 HOST_WIDE_INT field_size = tree_low_cst (dsize, 1);
1207 HOST_WIDE_INT offset = tree_low_cst (rli->offset, 0);
1208 HOST_WIDE_INT bit_offset = tree_low_cst (rli->bitpos, 0);
1210 #ifdef ADJUST_FIELD_ALIGN
1211 if (! TYPE_USER_ALIGN (type))
1212 type_align = ADJUST_FIELD_ALIGN (field, type_align);
1215 if (maximum_field_alignment != 0)
1216 type_align = MIN (type_align, maximum_field_alignment);
1217 /* ??? This test is opposite the test in the containing if
1218 statement, so this code is unreachable currently. */
1219 else if (DECL_PACKED (field))
1220 type_align = MIN (type_align, BITS_PER_UNIT);
1222 /* A bit field may not span the unit of alignment of its type.
1223 Advance to next boundary if necessary. */
1224 if (excess_unit_span (offset, bit_offset, field_size, type_align, type))
1225 rli->bitpos = round_up (rli->bitpos, type_align);
1227 TYPE_USER_ALIGN (rli->t) |= TYPE_USER_ALIGN (type);
1231 /* See the docs for TARGET_MS_BITFIELD_LAYOUT_P for details.
1233 When a bit field is inserted into a packed record, the whole
1234 size of the underlying type is used by one or more same-size
1235 adjacent bitfields. (That is, if its long:3, 32 bits is
1236 used in the record, and any additional adjacent long bitfields are
1237 packed into the same chunk of 32 bits. However, if the size
1238 changes, a new field of that size is allocated.) In an unpacked
1239 record, this is the same as using alignment, but not equivalent
1242 Note: for compatibility, we use the type size, not the type alignment
1243 to determine alignment, since that matches the documentation */
1245 if (targetm.ms_bitfield_layout_p (rli->t))
1247 tree prev_saved = rli->prev_field;
1248 tree prev_type = prev_saved ? DECL_BIT_FIELD_TYPE (prev_saved) : NULL;
1250 /* This is a bitfield if it exists. */
1251 if (rli->prev_field)
1253 /* If both are bitfields, nonzero, and the same size, this is
1254 the middle of a run. Zero declared size fields are special
1255 and handled as "end of run". (Note: it's nonzero declared
1256 size, but equal type sizes!) (Since we know that both
1257 the current and previous fields are bitfields by the
1258 time we check it, DECL_SIZE must be present for both.) */
1259 if (DECL_BIT_FIELD_TYPE (field)
1260 && !integer_zerop (DECL_SIZE (field))
1261 && !integer_zerop (DECL_SIZE (rli->prev_field))
1262 && host_integerp (DECL_SIZE (rli->prev_field), 0)
1263 && host_integerp (TYPE_SIZE (type), 0)
1264 && simple_cst_equal (TYPE_SIZE (type), TYPE_SIZE (prev_type)))
1266 /* We're in the middle of a run of equal type size fields; make
1267 sure we realign if we run out of bits. (Not decl size,
1269 HOST_WIDE_INT bitsize = tree_low_cst (DECL_SIZE (field), 1);
1271 if (rli->remaining_in_alignment < bitsize)
1273 HOST_WIDE_INT typesize = tree_low_cst (TYPE_SIZE (type), 1);
1275 /* out of bits; bump up to next 'word'. */
1277 = size_binop (PLUS_EXPR, rli->bitpos,
1278 bitsize_int (rli->remaining_in_alignment));
1279 rli->prev_field = field;
1280 if (typesize < bitsize)
1281 rli->remaining_in_alignment = 0;
1283 rli->remaining_in_alignment = typesize - bitsize;
1286 rli->remaining_in_alignment -= bitsize;
1290 /* End of a run: if leaving a run of bitfields of the same type
1291 size, we have to "use up" the rest of the bits of the type
1294 Compute the new position as the sum of the size for the prior
1295 type and where we first started working on that type.
1296 Note: since the beginning of the field was aligned then
1297 of course the end will be too. No round needed. */
1299 if (!integer_zerop (DECL_SIZE (rli->prev_field)))
1302 = size_binop (PLUS_EXPR, rli->bitpos,
1303 bitsize_int (rli->remaining_in_alignment));
1306 /* We "use up" size zero fields; the code below should behave
1307 as if the prior field was not a bitfield. */
1310 /* Cause a new bitfield to be captured, either this time (if
1311 currently a bitfield) or next time we see one. */
1312 if (!DECL_BIT_FIELD_TYPE(field)
1313 || integer_zerop (DECL_SIZE (field)))
1314 rli->prev_field = NULL;
1317 normalize_rli (rli);
1320 /* If we're starting a new run of same size type bitfields
1321 (or a run of non-bitfields), set up the "first of the run"
1324 That is, if the current field is not a bitfield, or if there
1325 was a prior bitfield the type sizes differ, or if there wasn't
1326 a prior bitfield the size of the current field is nonzero.
1328 Note: we must be sure to test ONLY the type size if there was
1329 a prior bitfield and ONLY for the current field being zero if
1332 if (!DECL_BIT_FIELD_TYPE (field)
1333 || (prev_saved != NULL
1334 ? !simple_cst_equal (TYPE_SIZE (type), TYPE_SIZE (prev_type))
1335 : !integer_zerop (DECL_SIZE (field)) ))
1337 /* Never smaller than a byte for compatibility. */
1338 unsigned int type_align = BITS_PER_UNIT;
1340 /* (When not a bitfield), we could be seeing a flex array (with
1341 no DECL_SIZE). Since we won't be using remaining_in_alignment
1342 until we see a bitfield (and come by here again) we just skip
1344 if (DECL_SIZE (field) != NULL
1345 && host_integerp (TYPE_SIZE (TREE_TYPE (field)), 0)
1346 && host_integerp (DECL_SIZE (field), 0))
1348 HOST_WIDE_INT bitsize = tree_low_cst (DECL_SIZE (field), 1);
1349 HOST_WIDE_INT typesize
1350 = tree_low_cst (TYPE_SIZE (TREE_TYPE (field)), 1);
1352 if (typesize < bitsize)
1353 rli->remaining_in_alignment = 0;
1355 rli->remaining_in_alignment = typesize - bitsize;
1358 /* Now align (conventionally) for the new type. */
1359 type_align = TYPE_ALIGN (TREE_TYPE (field));
1361 if (maximum_field_alignment != 0)
1362 type_align = MIN (type_align, maximum_field_alignment);
1364 rli->bitpos = round_up (rli->bitpos, type_align);
1366 /* If we really aligned, don't allow subsequent bitfields
1368 rli->prev_field = NULL;
1372 /* Offset so far becomes the position of this field after normalizing. */
1373 normalize_rli (rli);
1374 DECL_FIELD_OFFSET (field) = rli->offset;
1375 DECL_FIELD_BIT_OFFSET (field) = rli->bitpos;
1376 SET_DECL_OFFSET_ALIGN (field, rli->offset_align);
1378 /* If this field ended up more aligned than we thought it would be (we
1379 approximate this by seeing if its position changed), lay out the field
1380 again; perhaps we can use an integral mode for it now. */
1381 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field)))
1382 actual_align = (tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1)
1383 & - tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1));
1384 else if (integer_zerop (DECL_FIELD_OFFSET (field)))
1385 actual_align = MAX (BIGGEST_ALIGNMENT, rli->record_align);
1386 else if (host_integerp (DECL_FIELD_OFFSET (field), 1))
1387 actual_align = (BITS_PER_UNIT
1388 * (tree_low_cst (DECL_FIELD_OFFSET (field), 1)
1389 & - tree_low_cst (DECL_FIELD_OFFSET (field), 1)));
1391 actual_align = DECL_OFFSET_ALIGN (field);
1392 /* ACTUAL_ALIGN is still the actual alignment *within the record* .
1393 store / extract bit field operations will check the alignment of the
1394 record against the mode of bit fields. */
1396 if (known_align != actual_align)
1397 layout_decl (field, actual_align);
1399 if (rli->prev_field == NULL && DECL_BIT_FIELD_TYPE (field))
1400 rli->prev_field = field;
1402 /* Now add size of this field to the size of the record. If the size is
1403 not constant, treat the field as being a multiple of bytes and just
1404 adjust the offset, resetting the bit position. Otherwise, apportion the
1405 size amongst the bit position and offset. First handle the case of an
1406 unspecified size, which can happen when we have an invalid nested struct
1407 definition, such as struct j { struct j { int i; } }. The error message
1408 is printed in finish_struct. */
1409 if (DECL_SIZE (field) == 0)
1411 else if (TREE_CODE (DECL_SIZE (field)) != INTEGER_CST
1412 || TREE_OVERFLOW (DECL_SIZE (field)))
1415 = size_binop (PLUS_EXPR, rli->offset,
1416 fold_convert (sizetype,
1417 size_binop (CEIL_DIV_EXPR, rli->bitpos,
1418 bitsize_unit_node)));
1420 = size_binop (PLUS_EXPR, rli->offset, DECL_SIZE_UNIT (field));
1421 rli->bitpos = bitsize_zero_node;
1422 rli->offset_align = MIN (rli->offset_align, desired_align);
1424 else if (targetm.ms_bitfield_layout_p (rli->t))
1426 rli->bitpos = size_binop (PLUS_EXPR, rli->bitpos, DECL_SIZE (field));
1428 /* If we ended a bitfield before the full length of the type then
1429 pad the struct out to the full length of the last type. */
1430 if ((TREE_CHAIN (field) == NULL
1431 || TREE_CODE (TREE_CHAIN (field)) != FIELD_DECL)
1432 && DECL_BIT_FIELD_TYPE (field)
1433 && !integer_zerop (DECL_SIZE (field)))
1434 rli->bitpos = size_binop (PLUS_EXPR, rli->bitpos,
1435 bitsize_int (rli->remaining_in_alignment));
1437 normalize_rli (rli);
1441 rli->bitpos = size_binop (PLUS_EXPR, rli->bitpos, DECL_SIZE (field));
1442 normalize_rli (rli);
1446 /* Assuming that all the fields have been laid out, this function uses
1447 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
1448 indicated by RLI. */
1451 finalize_record_size (record_layout_info rli)
1453 tree unpadded_size, unpadded_size_unit;
1455 /* Now we want just byte and bit offsets, so set the offset alignment
1456 to be a byte and then normalize. */
1457 rli->offset_align = BITS_PER_UNIT;
1458 normalize_rli (rli);
1460 /* Determine the desired alignment. */
1461 #ifdef ROUND_TYPE_ALIGN
1462 TYPE_ALIGN (rli->t) = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t),
1465 TYPE_ALIGN (rli->t) = MAX (TYPE_ALIGN (rli->t), rli->record_align);
1468 /* Compute the size so far. Be sure to allow for extra bits in the
1469 size in bytes. We have guaranteed above that it will be no more
1470 than a single byte. */
1471 unpadded_size = rli_size_so_far (rli);
1472 unpadded_size_unit = rli_size_unit_so_far (rli);
1473 if (! integer_zerop (rli->bitpos))
1475 = size_binop (PLUS_EXPR, unpadded_size_unit, size_one_node);
1477 /* Round the size up to be a multiple of the required alignment. */
1478 TYPE_SIZE (rli->t) = round_up (unpadded_size, TYPE_ALIGN (rli->t));
1479 TYPE_SIZE_UNIT (rli->t)
1480 = round_up (unpadded_size_unit, TYPE_ALIGN_UNIT (rli->t));
1482 if (TREE_CONSTANT (unpadded_size)
1483 && simple_cst_equal (unpadded_size, TYPE_SIZE (rli->t)) == 0)
1484 warning (OPT_Wpadded, "padding struct size to alignment boundary");
1486 if (warn_packed && TREE_CODE (rli->t) == RECORD_TYPE
1487 && TYPE_PACKED (rli->t) && ! rli->packed_maybe_necessary
1488 && TREE_CONSTANT (unpadded_size))
1492 #ifdef ROUND_TYPE_ALIGN
1494 = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t), rli->unpacked_align);
1496 rli->unpacked_align = MAX (TYPE_ALIGN (rli->t), rli->unpacked_align);
1499 unpacked_size = round_up (TYPE_SIZE (rli->t), rli->unpacked_align);
1500 if (simple_cst_equal (unpacked_size, TYPE_SIZE (rli->t)))
1502 TYPE_PACKED (rli->t) = 0;
1504 if (TYPE_NAME (rli->t))
1508 if (TREE_CODE (TYPE_NAME (rli->t)) == IDENTIFIER_NODE)
1509 name = TYPE_NAME (rli->t);
1511 name = DECL_NAME (TYPE_NAME (rli->t));
1513 if (STRICT_ALIGNMENT)
1514 warning (OPT_Wpacked, "packed attribute causes inefficient "
1515 "alignment for %qE", name);
1517 warning (OPT_Wpacked,
1518 "packed attribute is unnecessary for %qE", name);
1522 if (STRICT_ALIGNMENT)
1523 warning (OPT_Wpacked,
1524 "packed attribute causes inefficient alignment");
1526 warning (OPT_Wpacked, "packed attribute is unnecessary");
1532 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
1535 compute_record_mode (tree type)
1538 enum machine_mode mode = VOIDmode;
1540 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
1541 However, if possible, we use a mode that fits in a register
1542 instead, in order to allow for better optimization down the
1544 SET_TYPE_MODE (type, BLKmode);
1546 if (! host_integerp (TYPE_SIZE (type), 1))
1549 /* A record which has any BLKmode members must itself be
1550 BLKmode; it can't go in a register. Unless the member is
1551 BLKmode only because it isn't aligned. */
1552 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1554 if (TREE_CODE (field) != FIELD_DECL)
1557 if (TREE_CODE (TREE_TYPE (field)) == ERROR_MARK
1558 || (TYPE_MODE (TREE_TYPE (field)) == BLKmode
1559 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field))
1560 && !(TYPE_SIZE (TREE_TYPE (field)) != 0
1561 && integer_zerop (TYPE_SIZE (TREE_TYPE (field)))))
1562 || ! host_integerp (bit_position (field), 1)
1563 || DECL_SIZE (field) == 0
1564 || ! host_integerp (DECL_SIZE (field), 1))
1567 /* If this field is the whole struct, remember its mode so
1568 that, say, we can put a double in a class into a DF
1569 register instead of forcing it to live in the stack. */
1570 if (simple_cst_equal (TYPE_SIZE (type), DECL_SIZE (field)))
1571 mode = DECL_MODE (field);
1573 #ifdef MEMBER_TYPE_FORCES_BLK
1574 /* With some targets, eg. c4x, it is sub-optimal
1575 to access an aligned BLKmode structure as a scalar. */
1577 if (MEMBER_TYPE_FORCES_BLK (field, mode))
1579 #endif /* MEMBER_TYPE_FORCES_BLK */
1582 /* If we only have one real field; use its mode if that mode's size
1583 matches the type's size. This only applies to RECORD_TYPE. This
1584 does not apply to unions. */
1585 if (TREE_CODE (type) == RECORD_TYPE && mode != VOIDmode
1586 && host_integerp (TYPE_SIZE (type), 1)
1587 && GET_MODE_BITSIZE (mode) == TREE_INT_CST_LOW (TYPE_SIZE (type)))
1588 SET_TYPE_MODE (type, mode);
1590 SET_TYPE_MODE (type, mode_for_size_tree (TYPE_SIZE (type), MODE_INT, 1));
1592 /* If structure's known alignment is less than what the scalar
1593 mode would need, and it matters, then stick with BLKmode. */
1594 if (TYPE_MODE (type) != BLKmode
1596 && ! (TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT
1597 || TYPE_ALIGN (type) >= GET_MODE_ALIGNMENT (TYPE_MODE (type))))
1599 /* If this is the only reason this type is BLKmode, then
1600 don't force containing types to be BLKmode. */
1601 TYPE_NO_FORCE_BLK (type) = 1;
1602 SET_TYPE_MODE (type, BLKmode);
1606 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1610 finalize_type_size (tree type)
1612 /* Normally, use the alignment corresponding to the mode chosen.
1613 However, where strict alignment is not required, avoid
1614 over-aligning structures, since most compilers do not do this
1617 if (TYPE_MODE (type) != BLKmode && TYPE_MODE (type) != VOIDmode
1618 && (STRICT_ALIGNMENT
1619 || (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE
1620 && TREE_CODE (type) != QUAL_UNION_TYPE
1621 && TREE_CODE (type) != ARRAY_TYPE)))
1623 unsigned mode_align = GET_MODE_ALIGNMENT (TYPE_MODE (type));
1625 /* Don't override a larger alignment requirement coming from a user
1626 alignment of one of the fields. */
1627 if (mode_align >= TYPE_ALIGN (type))
1629 TYPE_ALIGN (type) = mode_align;
1630 TYPE_USER_ALIGN (type) = 0;
1634 /* Do machine-dependent extra alignment. */
1635 #ifdef ROUND_TYPE_ALIGN
1637 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (type), BITS_PER_UNIT);
1640 /* If we failed to find a simple way to calculate the unit size
1641 of the type, find it by division. */
1642 if (TYPE_SIZE_UNIT (type) == 0 && TYPE_SIZE (type) != 0)
1643 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1644 result will fit in sizetype. We will get more efficient code using
1645 sizetype, so we force a conversion. */
1646 TYPE_SIZE_UNIT (type)
1647 = fold_convert (sizetype,
1648 size_binop (FLOOR_DIV_EXPR, TYPE_SIZE (type),
1649 bitsize_unit_node));
1651 if (TYPE_SIZE (type) != 0)
1653 TYPE_SIZE (type) = round_up (TYPE_SIZE (type), TYPE_ALIGN (type));
1654 TYPE_SIZE_UNIT (type) = round_up (TYPE_SIZE_UNIT (type),
1655 TYPE_ALIGN_UNIT (type));
1658 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1659 if (TYPE_SIZE (type) != 0 && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
1660 TYPE_SIZE (type) = variable_size (TYPE_SIZE (type));
1661 if (TYPE_SIZE_UNIT (type) != 0
1662 && TREE_CODE (TYPE_SIZE_UNIT (type)) != INTEGER_CST)
1663 TYPE_SIZE_UNIT (type) = variable_size (TYPE_SIZE_UNIT (type));
1665 /* Also layout any other variants of the type. */
1666 if (TYPE_NEXT_VARIANT (type)
1667 || type != TYPE_MAIN_VARIANT (type))
1670 /* Record layout info of this variant. */
1671 tree size = TYPE_SIZE (type);
1672 tree size_unit = TYPE_SIZE_UNIT (type);
1673 unsigned int align = TYPE_ALIGN (type);
1674 unsigned int user_align = TYPE_USER_ALIGN (type);
1675 enum machine_mode mode = TYPE_MODE (type);
1677 /* Copy it into all variants. */
1678 for (variant = TYPE_MAIN_VARIANT (type);
1680 variant = TYPE_NEXT_VARIANT (variant))
1682 TYPE_SIZE (variant) = size;
1683 TYPE_SIZE_UNIT (variant) = size_unit;
1684 TYPE_ALIGN (variant) = align;
1685 TYPE_USER_ALIGN (variant) = user_align;
1686 SET_TYPE_MODE (variant, mode);
1691 /* Do all of the work required to layout the type indicated by RLI,
1692 once the fields have been laid out. This function will call `free'
1693 for RLI, unless FREE_P is false. Passing a value other than false
1694 for FREE_P is bad practice; this option only exists to support the
1698 finish_record_layout (record_layout_info rli, int free_p)
1702 /* Compute the final size. */
1703 finalize_record_size (rli);
1705 /* Compute the TYPE_MODE for the record. */
1706 compute_record_mode (rli->t);
1708 /* Perform any last tweaks to the TYPE_SIZE, etc. */
1709 finalize_type_size (rli->t);
1711 /* Propagate TYPE_PACKED to variants. With C++ templates,
1712 handle_packed_attribute is too early to do this. */
1713 for (variant = TYPE_NEXT_VARIANT (rli->t); variant;
1714 variant = TYPE_NEXT_VARIANT (variant))
1715 TYPE_PACKED (variant) = TYPE_PACKED (rli->t);
1717 /* Lay out any static members. This is done now because their type
1718 may use the record's type. */
1719 while (rli->pending_statics)
1721 layout_decl (TREE_VALUE (rli->pending_statics), 0);
1722 rli->pending_statics = TREE_CHAIN (rli->pending_statics);
1731 /* Finish processing a builtin RECORD_TYPE type TYPE. It's name is
1732 NAME, its fields are chained in reverse on FIELDS.
1734 If ALIGN_TYPE is non-null, it is given the same alignment as
1738 finish_builtin_struct (tree type, const char *name, tree fields,
1743 for (tail = NULL_TREE; fields; tail = fields, fields = next)
1745 DECL_FIELD_CONTEXT (fields) = type;
1746 next = TREE_CHAIN (fields);
1747 TREE_CHAIN (fields) = tail;
1749 TYPE_FIELDS (type) = tail;
1753 TYPE_ALIGN (type) = TYPE_ALIGN (align_type);
1754 TYPE_USER_ALIGN (type) = TYPE_USER_ALIGN (align_type);
1758 #if 0 /* not yet, should get fixed properly later */
1759 TYPE_NAME (type) = make_type_decl (get_identifier (name), type);
1761 TYPE_NAME (type) = build_decl (BUILTINS_LOCATION,
1762 TYPE_DECL, get_identifier (name), type);
1764 TYPE_STUB_DECL (type) = TYPE_NAME (type);
1765 layout_decl (TYPE_NAME (type), 0);
1768 /* Calculate the mode, size, and alignment for TYPE.
1769 For an array type, calculate the element separation as well.
1770 Record TYPE on the chain of permanent or temporary types
1771 so that dbxout will find out about it.
1773 TYPE_SIZE of a type is nonzero if the type has been laid out already.
1774 layout_type does nothing on such a type.
1776 If the type is incomplete, its TYPE_SIZE remains zero. */
1779 layout_type (tree type)
1783 if (type == error_mark_node)
1786 /* Do nothing if type has been laid out before. */
1787 if (TYPE_SIZE (type))
1790 switch (TREE_CODE (type))
1793 /* This kind of type is the responsibility
1794 of the language-specific code. */
1797 case BOOLEAN_TYPE: /* Used for Java, Pascal, and Chill. */
1798 if (TYPE_PRECISION (type) == 0)
1799 TYPE_PRECISION (type) = 1; /* default to one byte/boolean. */
1801 /* ... fall through ... */
1805 if (TREE_CODE (TYPE_MIN_VALUE (type)) == INTEGER_CST
1806 && tree_int_cst_sgn (TYPE_MIN_VALUE (type)) >= 0)
1807 TYPE_UNSIGNED (type) = 1;
1809 SET_TYPE_MODE (type,
1810 smallest_mode_for_size (TYPE_PRECISION (type), MODE_INT));
1811 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1812 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1816 SET_TYPE_MODE (type,
1817 mode_for_size (TYPE_PRECISION (type), MODE_FLOAT, 0));
1818 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1819 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1822 case FIXED_POINT_TYPE:
1823 /* TYPE_MODE (type) has been set already. */
1824 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1825 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1829 TYPE_UNSIGNED (type) = TYPE_UNSIGNED (TREE_TYPE (type));
1830 SET_TYPE_MODE (type,
1831 mode_for_size (2 * TYPE_PRECISION (TREE_TYPE (type)),
1832 (TREE_CODE (TREE_TYPE (type)) == REAL_TYPE
1833 ? MODE_COMPLEX_FLOAT : MODE_COMPLEX_INT),
1835 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1836 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1841 int nunits = TYPE_VECTOR_SUBPARTS (type);
1842 tree innertype = TREE_TYPE (type);
1844 gcc_assert (!(nunits & (nunits - 1)));
1846 /* Find an appropriate mode for the vector type. */
1847 if (TYPE_MODE (type) == VOIDmode)
1849 enum machine_mode innermode = TYPE_MODE (innertype);
1850 enum machine_mode mode;
1852 /* First, look for a supported vector type. */
1853 if (SCALAR_FLOAT_MODE_P (innermode))
1854 mode = MIN_MODE_VECTOR_FLOAT;
1855 else if (SCALAR_FRACT_MODE_P (innermode))
1856 mode = MIN_MODE_VECTOR_FRACT;
1857 else if (SCALAR_UFRACT_MODE_P (innermode))
1858 mode = MIN_MODE_VECTOR_UFRACT;
1859 else if (SCALAR_ACCUM_MODE_P (innermode))
1860 mode = MIN_MODE_VECTOR_ACCUM;
1861 else if (SCALAR_UACCUM_MODE_P (innermode))
1862 mode = MIN_MODE_VECTOR_UACCUM;
1864 mode = MIN_MODE_VECTOR_INT;
1866 /* Do not check vector_mode_supported_p here. We'll do that
1867 later in vector_type_mode. */
1868 for (; mode != VOIDmode ; mode = GET_MODE_WIDER_MODE (mode))
1869 if (GET_MODE_NUNITS (mode) == nunits
1870 && GET_MODE_INNER (mode) == innermode)
1873 /* For integers, try mapping it to a same-sized scalar mode. */
1874 if (mode == VOIDmode
1875 && GET_MODE_CLASS (innermode) == MODE_INT)
1876 mode = mode_for_size (nunits * GET_MODE_BITSIZE (innermode),
1879 if (mode == VOIDmode ||
1880 (GET_MODE_CLASS (mode) == MODE_INT
1881 && !have_regs_of_mode[mode]))
1882 SET_TYPE_MODE (type, BLKmode);
1884 SET_TYPE_MODE (type, mode);
1887 TYPE_SATURATING (type) = TYPE_SATURATING (TREE_TYPE (type));
1888 TYPE_UNSIGNED (type) = TYPE_UNSIGNED (TREE_TYPE (type));
1889 TYPE_SIZE_UNIT (type) = int_const_binop (MULT_EXPR,
1890 TYPE_SIZE_UNIT (innertype),
1891 size_int (nunits), 0);
1892 TYPE_SIZE (type) = int_const_binop (MULT_EXPR, TYPE_SIZE (innertype),
1893 bitsize_int (nunits), 0);
1895 /* Always naturally align vectors. This prevents ABI changes
1896 depending on whether or not native vector modes are supported. */
1897 TYPE_ALIGN (type) = tree_low_cst (TYPE_SIZE (type), 0);
1902 /* This is an incomplete type and so doesn't have a size. */
1903 TYPE_ALIGN (type) = 1;
1904 TYPE_USER_ALIGN (type) = 0;
1905 SET_TYPE_MODE (type, VOIDmode);
1909 TYPE_SIZE (type) = bitsize_int (POINTER_SIZE);
1910 TYPE_SIZE_UNIT (type) = size_int (POINTER_SIZE / BITS_PER_UNIT);
1911 /* A pointer might be MODE_PARTIAL_INT,
1912 but ptrdiff_t must be integral. */
1913 SET_TYPE_MODE (type, mode_for_size (POINTER_SIZE, MODE_INT, 0));
1918 /* It's hard to see what the mode and size of a function ought to
1919 be, but we do know the alignment is FUNCTION_BOUNDARY, so
1920 make it consistent with that. */
1921 SET_TYPE_MODE (type, mode_for_size (FUNCTION_BOUNDARY, MODE_INT, 0));
1922 TYPE_SIZE (type) = bitsize_int (FUNCTION_BOUNDARY);
1923 TYPE_SIZE_UNIT (type) = size_int (FUNCTION_BOUNDARY / BITS_PER_UNIT);
1927 case REFERENCE_TYPE:
1929 enum machine_mode mode = ((TREE_CODE (type) == REFERENCE_TYPE
1930 && reference_types_internal)
1931 ? Pmode : TYPE_MODE (type));
1933 int nbits = GET_MODE_BITSIZE (mode);
1935 TYPE_SIZE (type) = bitsize_int (nbits);
1936 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (mode));
1937 TYPE_UNSIGNED (type) = 1;
1938 TYPE_PRECISION (type) = nbits;
1944 tree index = TYPE_DOMAIN (type);
1945 tree element = TREE_TYPE (type);
1947 build_pointer_type (element);
1949 /* We need to know both bounds in order to compute the size. */
1950 if (index && TYPE_MAX_VALUE (index) && TYPE_MIN_VALUE (index)
1951 && TYPE_SIZE (element))
1953 tree ub = TYPE_MAX_VALUE (index);
1954 tree lb = TYPE_MIN_VALUE (index);
1958 /* The initial subtraction should happen in the original type so
1959 that (possible) negative values are handled appropriately. */
1960 length = size_binop (PLUS_EXPR, size_one_node,
1961 fold_convert (sizetype,
1962 fold_build2 (MINUS_EXPR,
1966 /* Special handling for arrays of bits (for Chill). */
1967 element_size = TYPE_SIZE (element);
1968 if (TYPE_PACKED (type) && INTEGRAL_TYPE_P (element)
1969 && (integer_zerop (TYPE_MAX_VALUE (element))
1970 || integer_onep (TYPE_MAX_VALUE (element)))
1971 && host_integerp (TYPE_MIN_VALUE (element), 1))
1973 HOST_WIDE_INT maxvalue
1974 = tree_low_cst (TYPE_MAX_VALUE (element), 1);
1975 HOST_WIDE_INT minvalue
1976 = tree_low_cst (TYPE_MIN_VALUE (element), 1);
1978 if (maxvalue - minvalue == 1
1979 && (maxvalue == 1 || maxvalue == 0))
1980 element_size = integer_one_node;
1983 /* If neither bound is a constant and sizetype is signed, make
1984 sure the size is never negative. We should really do this
1985 if *either* bound is non-constant, but this is the best
1986 compromise between C and Ada. */
1987 if (!TYPE_UNSIGNED (sizetype)
1988 && TREE_CODE (TYPE_MIN_VALUE (index)) != INTEGER_CST
1989 && TREE_CODE (TYPE_MAX_VALUE (index)) != INTEGER_CST)
1990 length = size_binop (MAX_EXPR, length, size_zero_node);
1992 TYPE_SIZE (type) = size_binop (MULT_EXPR, element_size,
1993 fold_convert (bitsizetype,
1996 /* If we know the size of the element, calculate the total
1997 size directly, rather than do some division thing below.
1998 This optimization helps Fortran assumed-size arrays
1999 (where the size of the array is determined at runtime)
2001 Note that we can't do this in the case where the size of
2002 the elements is one bit since TYPE_SIZE_UNIT cannot be
2003 set correctly in that case. */
2004 if (TYPE_SIZE_UNIT (element) != 0 && ! integer_onep (element_size))
2005 TYPE_SIZE_UNIT (type)
2006 = size_binop (MULT_EXPR, TYPE_SIZE_UNIT (element), length);
2009 /* Now round the alignment and size,
2010 using machine-dependent criteria if any. */
2012 #ifdef ROUND_TYPE_ALIGN
2014 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (element), BITS_PER_UNIT);
2016 TYPE_ALIGN (type) = MAX (TYPE_ALIGN (element), BITS_PER_UNIT);
2018 if (!TYPE_SIZE (element))
2019 /* We don't know the size of the underlying element type, so
2020 our alignment calculations will be wrong, forcing us to
2021 fall back on structural equality. */
2022 SET_TYPE_STRUCTURAL_EQUALITY (type);
2023 TYPE_USER_ALIGN (type) = TYPE_USER_ALIGN (element);
2024 SET_TYPE_MODE (type, BLKmode);
2025 if (TYPE_SIZE (type) != 0
2026 #ifdef MEMBER_TYPE_FORCES_BLK
2027 && ! MEMBER_TYPE_FORCES_BLK (type, VOIDmode)
2029 /* BLKmode elements force BLKmode aggregate;
2030 else extract/store fields may lose. */
2031 && (TYPE_MODE (TREE_TYPE (type)) != BLKmode
2032 || TYPE_NO_FORCE_BLK (TREE_TYPE (type))))
2034 /* One-element arrays get the component type's mode. */
2035 if (simple_cst_equal (TYPE_SIZE (type),
2036 TYPE_SIZE (TREE_TYPE (type))))
2037 SET_TYPE_MODE (type, TYPE_MODE (TREE_TYPE (type)));
2039 SET_TYPE_MODE (type, mode_for_size_tree (TYPE_SIZE (type),
2042 if (TYPE_MODE (type) != BLKmode
2043 && STRICT_ALIGNMENT && TYPE_ALIGN (type) < BIGGEST_ALIGNMENT
2044 && TYPE_ALIGN (type) < GET_MODE_ALIGNMENT (TYPE_MODE (type)))
2046 TYPE_NO_FORCE_BLK (type) = 1;
2047 SET_TYPE_MODE (type, BLKmode);
2050 /* When the element size is constant, check that it is at least as
2051 large as the element alignment. */
2052 if (TYPE_SIZE_UNIT (element)
2053 && TREE_CODE (TYPE_SIZE_UNIT (element)) == INTEGER_CST
2054 /* If TYPE_SIZE_UNIT overflowed, then it is certainly larger than
2056 && !TREE_OVERFLOW (TYPE_SIZE_UNIT (element))
2057 && !integer_zerop (TYPE_SIZE_UNIT (element))
2058 && compare_tree_int (TYPE_SIZE_UNIT (element),
2059 TYPE_ALIGN_UNIT (element)) < 0)
2060 error ("alignment of array elements is greater than element size");
2066 case QUAL_UNION_TYPE:
2069 record_layout_info rli;
2071 /* Initialize the layout information. */
2072 rli = start_record_layout (type);
2074 /* If this is a QUAL_UNION_TYPE, we want to process the fields
2075 in the reverse order in building the COND_EXPR that denotes
2076 its size. We reverse them again later. */
2077 if (TREE_CODE (type) == QUAL_UNION_TYPE)
2078 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
2080 /* Place all the fields. */
2081 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
2082 place_field (rli, field);
2084 if (TREE_CODE (type) == QUAL_UNION_TYPE)
2085 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
2087 /* Finish laying out the record. */
2088 finish_record_layout (rli, /*free_p=*/true);
2096 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
2097 records and unions, finish_record_layout already called this
2099 if (TREE_CODE (type) != RECORD_TYPE
2100 && TREE_CODE (type) != UNION_TYPE
2101 && TREE_CODE (type) != QUAL_UNION_TYPE)
2102 finalize_type_size (type);
2104 /* We should never see alias sets on incomplete aggregates. And we
2105 should not call layout_type on not incomplete aggregates. */
2106 if (AGGREGATE_TYPE_P (type))
2107 gcc_assert (!TYPE_ALIAS_SET_KNOWN_P (type));
2110 /* Vector types need to re-check the target flags each time we report
2111 the machine mode. We need to do this because attribute target can
2112 change the result of vector_mode_supported_p and have_regs_of_mode
2113 on a per-function basis. Thus the TYPE_MODE of a VECTOR_TYPE can
2114 change on a per-function basis. */
2115 /* ??? Possibly a better solution is to run through all the types
2116 referenced by a function and re-compute the TYPE_MODE once, rather
2117 than make the TYPE_MODE macro call a function. */
2120 vector_type_mode (const_tree t)
2122 enum machine_mode mode;
2124 gcc_assert (TREE_CODE (t) == VECTOR_TYPE);
2126 mode = t->type.mode;
2127 if (VECTOR_MODE_P (mode)
2128 && (!targetm.vector_mode_supported_p (mode)
2129 || !have_regs_of_mode[mode]))
2131 enum machine_mode innermode = TREE_TYPE (t)->type.mode;
2133 /* For integers, try mapping it to a same-sized scalar mode. */
2134 if (GET_MODE_CLASS (innermode) == MODE_INT)
2136 mode = mode_for_size (TYPE_VECTOR_SUBPARTS (t)
2137 * GET_MODE_BITSIZE (innermode), MODE_INT, 0);
2139 if (mode != VOIDmode && have_regs_of_mode[mode])
2149 /* Create and return a type for signed integers of PRECISION bits. */
2152 make_signed_type (int precision)
2154 tree type = make_node (INTEGER_TYPE);
2156 TYPE_PRECISION (type) = precision;
2158 fixup_signed_type (type);
2162 /* Create and return a type for unsigned integers of PRECISION bits. */
2165 make_unsigned_type (int precision)
2167 tree type = make_node (INTEGER_TYPE);
2169 TYPE_PRECISION (type) = precision;
2171 fixup_unsigned_type (type);
2175 /* Create and return a type for fract of PRECISION bits, UNSIGNEDP,
2179 make_fract_type (int precision, int unsignedp, int satp)
2181 tree type = make_node (FIXED_POINT_TYPE);
2183 TYPE_PRECISION (type) = precision;
2186 TYPE_SATURATING (type) = 1;
2188 /* Lay out the type: set its alignment, size, etc. */
2191 TYPE_UNSIGNED (type) = 1;
2192 SET_TYPE_MODE (type, mode_for_size (precision, MODE_UFRACT, 0));
2195 SET_TYPE_MODE (type, mode_for_size (precision, MODE_FRACT, 0));
2201 /* Create and return a type for accum of PRECISION bits, UNSIGNEDP,
2205 make_accum_type (int precision, int unsignedp, int satp)
2207 tree type = make_node (FIXED_POINT_TYPE);
2209 TYPE_PRECISION (type) = precision;
2212 TYPE_SATURATING (type) = 1;
2214 /* Lay out the type: set its alignment, size, etc. */
2217 TYPE_UNSIGNED (type) = 1;
2218 SET_TYPE_MODE (type, mode_for_size (precision, MODE_UACCUM, 0));
2221 SET_TYPE_MODE (type, mode_for_size (precision, MODE_ACCUM, 0));
2227 /* Initialize sizetype and bitsizetype to a reasonable and temporary
2228 value to enable integer types to be created. */
2231 initialize_sizetypes (bool signed_p)
2233 tree t = make_node (INTEGER_TYPE);
2234 int precision = GET_MODE_BITSIZE (SImode);
2236 SET_TYPE_MODE (t, SImode);
2237 TYPE_ALIGN (t) = GET_MODE_ALIGNMENT (SImode);
2238 TYPE_USER_ALIGN (t) = 0;
2239 TYPE_IS_SIZETYPE (t) = 1;
2240 TYPE_UNSIGNED (t) = !signed_p;
2241 TYPE_SIZE (t) = build_int_cst (t, precision);
2242 TYPE_SIZE_UNIT (t) = build_int_cst (t, GET_MODE_SIZE (SImode));
2243 TYPE_PRECISION (t) = precision;
2245 /* Set TYPE_MIN_VALUE and TYPE_MAX_VALUE. */
2246 set_min_and_max_values_for_integral_type (t, precision, !signed_p);
2249 bitsizetype = build_distinct_type_copy (t);
2252 /* Make sizetype a version of TYPE, and initialize *sizetype
2253 accordingly. We do this by overwriting the stub sizetype and
2254 bitsizetype nodes created by initialize_sizetypes. This makes sure
2255 that (a) anything stubby about them no longer exists, (b) any
2256 INTEGER_CSTs created with such a type, remain valid. */
2259 set_sizetype (tree type)
2262 int oprecision = TYPE_PRECISION (type);
2263 /* The *bitsizetype types use a precision that avoids overflows when
2264 calculating signed sizes / offsets in bits. However, when
2265 cross-compiling from a 32 bit to a 64 bit host, we are limited to 64 bit
2268 = MIN (oprecision + BITS_PER_UNIT_LOG + 1, MAX_FIXED_MODE_SIZE);
2270 = GET_MODE_PRECISION (smallest_mode_for_size (precision, MODE_INT));
2271 if (precision > HOST_BITS_PER_WIDE_INT * 2)
2272 precision = HOST_BITS_PER_WIDE_INT * 2;
2274 gcc_assert (TYPE_UNSIGNED (type) == TYPE_UNSIGNED (sizetype));
2276 t = build_distinct_type_copy (type);
2277 /* We do want to use sizetype's cache, as we will be replacing that
2279 TYPE_CACHED_VALUES (t) = TYPE_CACHED_VALUES (sizetype);
2280 TYPE_CACHED_VALUES_P (t) = TYPE_CACHED_VALUES_P (sizetype);
2281 TREE_TYPE (TYPE_CACHED_VALUES (t)) = type;
2282 TYPE_UID (t) = TYPE_UID (sizetype);
2283 TYPE_IS_SIZETYPE (t) = 1;
2285 /* Replace our original stub sizetype. */
2286 memcpy (sizetype, t, tree_size (sizetype));
2287 TYPE_MAIN_VARIANT (sizetype) = sizetype;
2288 TYPE_CANONICAL (sizetype) = sizetype;
2290 t = make_node (INTEGER_TYPE);
2291 TYPE_NAME (t) = get_identifier ("bit_size_type");
2292 /* We do want to use bitsizetype's cache, as we will be replacing that
2294 TYPE_CACHED_VALUES (t) = TYPE_CACHED_VALUES (bitsizetype);
2295 TYPE_CACHED_VALUES_P (t) = TYPE_CACHED_VALUES_P (bitsizetype);
2296 TYPE_PRECISION (t) = precision;
2297 TYPE_UID (t) = TYPE_UID (bitsizetype);
2298 TYPE_IS_SIZETYPE (t) = 1;
2300 /* Replace our original stub bitsizetype. */
2301 memcpy (bitsizetype, t, tree_size (bitsizetype));
2302 TYPE_MAIN_VARIANT (bitsizetype) = bitsizetype;
2303 TYPE_CANONICAL (bitsizetype) = bitsizetype;
2305 if (TYPE_UNSIGNED (type))
2307 fixup_unsigned_type (bitsizetype);
2308 ssizetype = build_distinct_type_copy (make_signed_type (oprecision));
2309 TYPE_IS_SIZETYPE (ssizetype) = 1;
2310 sbitsizetype = build_distinct_type_copy (make_signed_type (precision));
2311 TYPE_IS_SIZETYPE (sbitsizetype) = 1;
2315 fixup_signed_type (bitsizetype);
2316 ssizetype = sizetype;
2317 sbitsizetype = bitsizetype;
2320 /* If SIZETYPE is unsigned, we need to fix TYPE_MAX_VALUE so that
2321 it is sign extended in a way consistent with force_fit_type. */
2322 if (TYPE_UNSIGNED (type))
2324 tree orig_max, new_max;
2326 orig_max = TYPE_MAX_VALUE (sizetype);
2328 /* Build a new node with the same values, but a different type.
2329 Sign extend it to ensure consistency. */
2330 new_max = build_int_cst_wide_type (sizetype,
2331 TREE_INT_CST_LOW (orig_max),
2332 TREE_INT_CST_HIGH (orig_max));
2333 TYPE_MAX_VALUE (sizetype) = new_max;
2337 /* TYPE is an integral type, i.e., an INTEGRAL_TYPE, ENUMERAL_TYPE
2338 or BOOLEAN_TYPE. Set TYPE_MIN_VALUE and TYPE_MAX_VALUE
2339 for TYPE, based on the PRECISION and whether or not the TYPE
2340 IS_UNSIGNED. PRECISION need not correspond to a width supported
2341 natively by the hardware; for example, on a machine with 8-bit,
2342 16-bit, and 32-bit register modes, PRECISION might be 7, 23, or
2346 set_min_and_max_values_for_integral_type (tree type,
2355 min_value = build_int_cst (type, 0);
2357 = build_int_cst_wide (type, precision - HOST_BITS_PER_WIDE_INT >= 0
2359 : ((HOST_WIDE_INT) 1 << precision) - 1,
2360 precision - HOST_BITS_PER_WIDE_INT > 0
2361 ? ((unsigned HOST_WIDE_INT) ~0
2362 >> (HOST_BITS_PER_WIDE_INT
2363 - (precision - HOST_BITS_PER_WIDE_INT)))
2369 = build_int_cst_wide (type,
2370 (precision - HOST_BITS_PER_WIDE_INT > 0
2372 : (HOST_WIDE_INT) (-1) << (precision - 1)),
2373 (((HOST_WIDE_INT) (-1)
2374 << (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
2375 ? precision - HOST_BITS_PER_WIDE_INT - 1
2378 = build_int_cst_wide (type,
2379 (precision - HOST_BITS_PER_WIDE_INT > 0
2381 : ((HOST_WIDE_INT) 1 << (precision - 1)) - 1),
2382 (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
2383 ? (((HOST_WIDE_INT) 1
2384 << (precision - HOST_BITS_PER_WIDE_INT - 1))) - 1
2388 TYPE_MIN_VALUE (type) = min_value;
2389 TYPE_MAX_VALUE (type) = max_value;
2392 /* Set the extreme values of TYPE based on its precision in bits,
2393 then lay it out. Used when make_signed_type won't do
2394 because the tree code is not INTEGER_TYPE.
2395 E.g. for Pascal, when the -fsigned-char option is given. */
2398 fixup_signed_type (tree type)
2400 int precision = TYPE_PRECISION (type);
2402 /* We can not represent properly constants greater then
2403 2 * HOST_BITS_PER_WIDE_INT, still we need the types
2404 as they are used by i386 vector extensions and friends. */
2405 if (precision > HOST_BITS_PER_WIDE_INT * 2)
2406 precision = HOST_BITS_PER_WIDE_INT * 2;
2408 set_min_and_max_values_for_integral_type (type, precision,
2409 /*is_unsigned=*/false);
2411 /* Lay out the type: set its alignment, size, etc. */
2415 /* Set the extreme values of TYPE based on its precision in bits,
2416 then lay it out. This is used both in `make_unsigned_type'
2417 and for enumeral types. */
2420 fixup_unsigned_type (tree type)
2422 int precision = TYPE_PRECISION (type);
2424 /* We can not represent properly constants greater then
2425 2 * HOST_BITS_PER_WIDE_INT, still we need the types
2426 as they are used by i386 vector extensions and friends. */
2427 if (precision > HOST_BITS_PER_WIDE_INT * 2)
2428 precision = HOST_BITS_PER_WIDE_INT * 2;
2430 TYPE_UNSIGNED (type) = 1;
2432 set_min_and_max_values_for_integral_type (type, precision,
2433 /*is_unsigned=*/true);
2435 /* Lay out the type: set its alignment, size, etc. */
2439 /* Find the best machine mode to use when referencing a bit field of length
2440 BITSIZE bits starting at BITPOS.
2442 The underlying object is known to be aligned to a boundary of ALIGN bits.
2443 If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
2444 larger than LARGEST_MODE (usually SImode).
2446 If no mode meets all these conditions, we return VOIDmode.
2448 If VOLATILEP is false and SLOW_BYTE_ACCESS is false, we return the
2449 smallest mode meeting these conditions.
2451 If VOLATILEP is false and SLOW_BYTE_ACCESS is true, we return the
2452 largest mode (but a mode no wider than UNITS_PER_WORD) that meets
2455 If VOLATILEP is true the narrow_volatile_bitfields target hook is used to
2456 decide which of the above modes should be used. */
2459 get_best_mode (int bitsize, int bitpos, unsigned int align,
2460 enum machine_mode largest_mode, int volatilep)
2462 enum machine_mode mode;
2463 unsigned int unit = 0;
2465 /* Find the narrowest integer mode that contains the bit field. */
2466 for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
2467 mode = GET_MODE_WIDER_MODE (mode))
2469 unit = GET_MODE_BITSIZE (mode);
2470 if ((bitpos % unit) + bitsize <= unit)
2474 if (mode == VOIDmode
2475 /* It is tempting to omit the following line
2476 if STRICT_ALIGNMENT is true.
2477 But that is incorrect, since if the bitfield uses part of 3 bytes
2478 and we use a 4-byte mode, we could get a spurious segv
2479 if the extra 4th byte is past the end of memory.
2480 (Though at least one Unix compiler ignores this problem:
2481 that on the Sequent 386 machine. */
2482 || MIN (unit, BIGGEST_ALIGNMENT) > align
2483 || (largest_mode != VOIDmode && unit > GET_MODE_BITSIZE (largest_mode)))
2486 if ((SLOW_BYTE_ACCESS && ! volatilep)
2487 || (volatilep && !targetm.narrow_volatile_bitfield ()))
2489 enum machine_mode wide_mode = VOIDmode, tmode;
2491 for (tmode = GET_CLASS_NARROWEST_MODE (MODE_INT); tmode != VOIDmode;
2492 tmode = GET_MODE_WIDER_MODE (tmode))
2494 unit = GET_MODE_BITSIZE (tmode);
2495 if (bitpos / unit == (bitpos + bitsize - 1) / unit
2496 && unit <= BITS_PER_WORD
2497 && unit <= MIN (align, BIGGEST_ALIGNMENT)
2498 && (largest_mode == VOIDmode
2499 || unit <= GET_MODE_BITSIZE (largest_mode)))
2503 if (wide_mode != VOIDmode)
2510 /* Gets minimal and maximal values for MODE (signed or unsigned depending on
2511 SIGN). The returned constants are made to be usable in TARGET_MODE. */
2514 get_mode_bounds (enum machine_mode mode, int sign,
2515 enum machine_mode target_mode,
2516 rtx *mmin, rtx *mmax)
2518 unsigned size = GET_MODE_BITSIZE (mode);
2519 unsigned HOST_WIDE_INT min_val, max_val;
2521 gcc_assert (size <= HOST_BITS_PER_WIDE_INT);
2525 min_val = -((unsigned HOST_WIDE_INT) 1 << (size - 1));
2526 max_val = ((unsigned HOST_WIDE_INT) 1 << (size - 1)) - 1;
2531 max_val = ((unsigned HOST_WIDE_INT) 1 << (size - 1) << 1) - 1;
2534 *mmin = gen_int_mode (min_val, target_mode);
2535 *mmax = gen_int_mode (max_val, target_mode);
2538 #include "gt-stor-layout.h"