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 /* SAVE_EXPRs for sizes of types and decls, waiting to be expanded. */
70 static GTY(()) VEC(tree,gc) *pending_sizes;
72 /* Show that REFERENCE_TYPES are internal and should use address_mode.
73 Called only by front end. */
76 internal_reference_types (void)
78 reference_types_internal = 1;
81 /* Get a VEC of all the objects put on the pending sizes list. */
84 get_pending_sizes (void)
86 VEC(tree,gc) *chain = pending_sizes;
92 /* Add EXPR to the pending sizes list. */
95 put_pending_size (tree expr)
97 /* Strip any simple arithmetic from EXPR to see if it has an underlying
99 expr = skip_simple_arithmetic (expr);
101 if (TREE_CODE (expr) == SAVE_EXPR)
102 VEC_safe_push (tree, gc, pending_sizes, expr);
105 /* Put a chain of objects into the pending sizes list, which must be
109 put_pending_sizes (VEC(tree,gc) *chain)
111 gcc_assert (!pending_sizes);
112 pending_sizes = chain;
115 /* Given a size SIZE that may not be a constant, return a SAVE_EXPR
116 to serve as the actual size-expression for a type or decl. */
119 variable_size (tree size)
124 if (TREE_CONSTANT (size))
127 /* If the size is self-referential, we can't make a SAVE_EXPR (see
128 save_expr for the rationale). But we can do something else. */
129 if (CONTAINS_PLACEHOLDER_P (size))
130 return self_referential_size (size);
132 /* If the language-processor is to take responsibility for variable-sized
133 items (e.g., languages which have elaboration procedures like Ada),
134 just return SIZE unchanged. */
135 if (lang_hooks.decls.global_bindings_p () < 0)
138 size = save_expr (size);
140 /* If an array with a variable number of elements is declared, and
141 the elements require destruction, we will emit a cleanup for the
142 array. That cleanup is run both on normal exit from the block
143 and in the exception-handler for the block. Normally, when code
144 is used in both ordinary code and in an exception handler it is
145 `unsaved', i.e., all SAVE_EXPRs are recalculated. However, we do
146 not wish to do that here; the array-size is the same in both
148 save = skip_simple_arithmetic (size);
150 if (cfun && cfun->dont_save_pending_sizes_p)
151 /* The front-end doesn't want us to keep a list of the expressions
152 that determine sizes for variable size objects. Trust it. */
155 if (lang_hooks.decls.global_bindings_p ())
157 if (TREE_CONSTANT (size))
158 error ("type size can%'t be explicitly evaluated");
160 error ("variable-size type declared outside of any function");
162 return size_one_node;
165 put_pending_size (save);
170 /* An array of functions used for self-referential size computation. */
171 static GTY(()) VEC (tree, gc) *size_functions;
173 /* Look inside EXPR into simple arithmetic operations involving constants.
174 Return the outermost non-arithmetic or non-constant node. */
177 skip_simple_constant_arithmetic (tree expr)
181 if (UNARY_CLASS_P (expr))
182 expr = TREE_OPERAND (expr, 0);
183 else if (BINARY_CLASS_P (expr))
185 if (TREE_CONSTANT (TREE_OPERAND (expr, 1)))
186 expr = TREE_OPERAND (expr, 0);
187 else if (TREE_CONSTANT (TREE_OPERAND (expr, 0)))
188 expr = TREE_OPERAND (expr, 1);
199 /* Similar to copy_tree_r but do not copy component references involving
200 PLACEHOLDER_EXPRs. These nodes are spotted in find_placeholder_in_expr
201 and substituted in substitute_in_expr. */
204 copy_self_referential_tree_r (tree *tp, int *walk_subtrees, void *data)
206 enum tree_code code = TREE_CODE (*tp);
208 /* Stop at types, decls, constants like copy_tree_r. */
209 if (TREE_CODE_CLASS (code) == tcc_type
210 || TREE_CODE_CLASS (code) == tcc_declaration
211 || TREE_CODE_CLASS (code) == tcc_constant)
217 /* This is the pattern built in ada/make_aligning_type. */
218 else if (code == ADDR_EXPR
219 && TREE_CODE (TREE_OPERAND (*tp, 0)) == PLACEHOLDER_EXPR)
225 /* Default case: the component reference. */
226 else if (code == COMPONENT_REF)
229 for (inner = TREE_OPERAND (*tp, 0);
230 REFERENCE_CLASS_P (inner);
231 inner = TREE_OPERAND (inner, 0))
234 if (TREE_CODE (inner) == PLACEHOLDER_EXPR)
241 /* We're not supposed to have them in self-referential size trees
242 because we wouldn't properly control when they are evaluated.
243 However, not creating superfluous SAVE_EXPRs requires accurate
244 tracking of readonly-ness all the way down to here, which we
245 cannot always guarantee in practice. So punt in this case. */
246 else if (code == SAVE_EXPR)
247 return error_mark_node;
249 return copy_tree_r (tp, walk_subtrees, data);
252 /* Given a SIZE expression that is self-referential, return an equivalent
253 expression to serve as the actual size expression for a type. */
256 self_referential_size (tree size)
258 static unsigned HOST_WIDE_INT fnno = 0;
259 VEC (tree, heap) *self_refs = NULL;
260 tree param_type_list = NULL, param_decl_list = NULL;
261 tree t, ref, return_type, fntype, fnname, fndecl;
264 VEC(tree,gc) *args = NULL;
266 /* Do not factor out simple operations. */
267 t = skip_simple_constant_arithmetic (size);
268 if (TREE_CODE (t) == CALL_EXPR)
271 /* Collect the list of self-references in the expression. */
272 find_placeholder_in_expr (size, &self_refs);
273 gcc_assert (VEC_length (tree, self_refs) > 0);
275 /* Obtain a private copy of the expression. */
277 if (walk_tree (&t, copy_self_referential_tree_r, NULL, NULL) != NULL_TREE)
281 /* Build the parameter and argument lists in parallel; also
282 substitute the former for the latter in the expression. */
283 args = VEC_alloc (tree, gc, VEC_length (tree, self_refs));
284 FOR_EACH_VEC_ELT (tree, self_refs, i, ref)
286 tree subst, param_name, param_type, param_decl;
290 /* We shouldn't have true variables here. */
291 gcc_assert (TREE_READONLY (ref));
294 /* This is the pattern built in ada/make_aligning_type. */
295 else if (TREE_CODE (ref) == ADDR_EXPR)
297 /* Default case: the component reference. */
299 subst = TREE_OPERAND (ref, 1);
301 sprintf (buf, "p%d", i);
302 param_name = get_identifier (buf);
303 param_type = TREE_TYPE (ref);
305 = build_decl (input_location, PARM_DECL, param_name, param_type);
306 if (targetm.calls.promote_prototypes (NULL_TREE)
307 && INTEGRAL_TYPE_P (param_type)
308 && TYPE_PRECISION (param_type) < TYPE_PRECISION (integer_type_node))
309 DECL_ARG_TYPE (param_decl) = integer_type_node;
311 DECL_ARG_TYPE (param_decl) = param_type;
312 DECL_ARTIFICIAL (param_decl) = 1;
313 TREE_READONLY (param_decl) = 1;
315 size = substitute_in_expr (size, subst, param_decl);
317 param_type_list = tree_cons (NULL_TREE, param_type, param_type_list);
318 param_decl_list = chainon (param_decl, param_decl_list);
319 VEC_quick_push (tree, args, ref);
322 VEC_free (tree, heap, self_refs);
324 /* Append 'void' to indicate that the number of parameters is fixed. */
325 param_type_list = tree_cons (NULL_TREE, void_type_node, param_type_list);
327 /* The 3 lists have been created in reverse order. */
328 param_type_list = nreverse (param_type_list);
329 param_decl_list = nreverse (param_decl_list);
331 /* Build the function type. */
332 return_type = TREE_TYPE (size);
333 fntype = build_function_type (return_type, param_type_list);
335 /* Build the function declaration. */
336 sprintf (buf, "SZ"HOST_WIDE_INT_PRINT_UNSIGNED, fnno++);
337 fnname = get_file_function_name (buf);
338 fndecl = build_decl (input_location, FUNCTION_DECL, fnname, fntype);
339 for (t = param_decl_list; t; t = DECL_CHAIN (t))
340 DECL_CONTEXT (t) = fndecl;
341 DECL_ARGUMENTS (fndecl) = param_decl_list;
343 = build_decl (input_location, RESULT_DECL, 0, return_type);
344 DECL_CONTEXT (DECL_RESULT (fndecl)) = fndecl;
346 /* The function has been created by the compiler and we don't
347 want to emit debug info for it. */
348 DECL_ARTIFICIAL (fndecl) = 1;
349 DECL_IGNORED_P (fndecl) = 1;
351 /* It is supposed to be "const" and never throw. */
352 TREE_READONLY (fndecl) = 1;
353 TREE_NOTHROW (fndecl) = 1;
355 /* We want it to be inlined when this is deemed profitable, as
356 well as discarded if every call has been integrated. */
357 DECL_DECLARED_INLINE_P (fndecl) = 1;
359 /* It is made up of a unique return statement. */
360 DECL_INITIAL (fndecl) = make_node (BLOCK);
361 BLOCK_SUPERCONTEXT (DECL_INITIAL (fndecl)) = fndecl;
362 t = build2 (MODIFY_EXPR, return_type, DECL_RESULT (fndecl), size);
363 DECL_SAVED_TREE (fndecl) = build1 (RETURN_EXPR, void_type_node, t);
364 TREE_STATIC (fndecl) = 1;
366 /* Put it onto the list of size functions. */
367 VEC_safe_push (tree, gc, size_functions, fndecl);
369 /* Replace the original expression with a call to the size function. */
370 return build_call_expr_loc_vec (UNKNOWN_LOCATION, fndecl, args);
373 /* Take, queue and compile all the size functions. It is essential that
374 the size functions be gimplified at the very end of the compilation
375 in order to guarantee transparent handling of self-referential sizes.
376 Otherwise the GENERIC inliner would not be able to inline them back
377 at each of their call sites, thus creating artificial non-constant
378 size expressions which would trigger nasty problems later on. */
381 finalize_size_functions (void)
386 for (i = 0; VEC_iterate(tree, size_functions, i, fndecl); i++)
388 dump_function (TDI_original, fndecl);
389 gimplify_function_tree (fndecl);
390 dump_function (TDI_generic, fndecl);
391 cgraph_finalize_function (fndecl, false);
394 VEC_free (tree, gc, size_functions);
397 /* Return the machine mode to use for a nonscalar of SIZE bits. The
398 mode must be in class MCLASS, and have exactly that many value bits;
399 it may have padding as well. If LIMIT is nonzero, modes of wider
400 than MAX_FIXED_MODE_SIZE will not be used. */
403 mode_for_size (unsigned int size, enum mode_class mclass, int limit)
405 enum machine_mode mode;
407 if (limit && size > MAX_FIXED_MODE_SIZE)
410 /* Get the first mode which has this size, in the specified class. */
411 for (mode = GET_CLASS_NARROWEST_MODE (mclass); mode != VOIDmode;
412 mode = GET_MODE_WIDER_MODE (mode))
413 if (GET_MODE_PRECISION (mode) == size)
419 /* Similar, except passed a tree node. */
422 mode_for_size_tree (const_tree size, enum mode_class mclass, int limit)
424 unsigned HOST_WIDE_INT uhwi;
427 if (!host_integerp (size, 1))
429 uhwi = tree_low_cst (size, 1);
433 return mode_for_size (ui, mclass, limit);
436 /* Similar, but never return BLKmode; return the narrowest mode that
437 contains at least the requested number of value bits. */
440 smallest_mode_for_size (unsigned int size, enum mode_class mclass)
442 enum machine_mode mode;
444 /* Get the first mode which has at least this size, in the
446 for (mode = GET_CLASS_NARROWEST_MODE (mclass); mode != VOIDmode;
447 mode = GET_MODE_WIDER_MODE (mode))
448 if (GET_MODE_PRECISION (mode) >= size)
454 /* Find an integer mode of the exact same size, or BLKmode on failure. */
457 int_mode_for_mode (enum machine_mode mode)
459 switch (GET_MODE_CLASS (mode))
462 case MODE_PARTIAL_INT:
465 case MODE_COMPLEX_INT:
466 case MODE_COMPLEX_FLOAT:
468 case MODE_DECIMAL_FLOAT:
469 case MODE_VECTOR_INT:
470 case MODE_VECTOR_FLOAT:
475 case MODE_VECTOR_FRACT:
476 case MODE_VECTOR_ACCUM:
477 case MODE_VECTOR_UFRACT:
478 case MODE_VECTOR_UACCUM:
479 mode = mode_for_size (GET_MODE_BITSIZE (mode), MODE_INT, 0);
486 /* ... fall through ... */
496 /* Find a mode that is suitable for representing a vector with
497 NUNITS elements of mode INNERMODE. Returns BLKmode if there
498 is no suitable mode. */
501 mode_for_vector (enum machine_mode innermode, unsigned nunits)
503 enum machine_mode mode;
505 /* First, look for a supported vector type. */
506 if (SCALAR_FLOAT_MODE_P (innermode))
507 mode = MIN_MODE_VECTOR_FLOAT;
508 else if (SCALAR_FRACT_MODE_P (innermode))
509 mode = MIN_MODE_VECTOR_FRACT;
510 else if (SCALAR_UFRACT_MODE_P (innermode))
511 mode = MIN_MODE_VECTOR_UFRACT;
512 else if (SCALAR_ACCUM_MODE_P (innermode))
513 mode = MIN_MODE_VECTOR_ACCUM;
514 else if (SCALAR_UACCUM_MODE_P (innermode))
515 mode = MIN_MODE_VECTOR_UACCUM;
517 mode = MIN_MODE_VECTOR_INT;
519 /* Do not check vector_mode_supported_p here. We'll do that
520 later in vector_type_mode. */
521 for (; mode != VOIDmode ; mode = GET_MODE_WIDER_MODE (mode))
522 if (GET_MODE_NUNITS (mode) == nunits
523 && GET_MODE_INNER (mode) == innermode)
526 /* For integers, try mapping it to a same-sized scalar mode. */
528 && GET_MODE_CLASS (innermode) == MODE_INT)
529 mode = mode_for_size (nunits * GET_MODE_BITSIZE (innermode),
533 || (GET_MODE_CLASS (mode) == MODE_INT
534 && !have_regs_of_mode[mode]))
540 /* Return the alignment of MODE. This will be bounded by 1 and
541 BIGGEST_ALIGNMENT. */
544 get_mode_alignment (enum machine_mode mode)
546 return MIN (BIGGEST_ALIGNMENT, MAX (1, mode_base_align[mode]*BITS_PER_UNIT));
550 /* Subroutine of layout_decl: Force alignment required for the data type.
551 But if the decl itself wants greater alignment, don't override that. */
554 do_type_align (tree type, tree decl)
556 if (TYPE_ALIGN (type) > DECL_ALIGN (decl))
558 DECL_ALIGN (decl) = TYPE_ALIGN (type);
559 if (TREE_CODE (decl) == FIELD_DECL)
560 DECL_USER_ALIGN (decl) = TYPE_USER_ALIGN (type);
564 /* Set the size, mode and alignment of a ..._DECL node.
565 TYPE_DECL does need this for C++.
566 Note that LABEL_DECL and CONST_DECL nodes do not need this,
567 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
568 Don't call layout_decl for them.
570 KNOWN_ALIGN is the amount of alignment we can assume this
571 decl has with no special effort. It is relevant only for FIELD_DECLs
572 and depends on the previous fields.
573 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
574 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
575 the record will be aligned to suit. */
578 layout_decl (tree decl, unsigned int known_align)
580 tree type = TREE_TYPE (decl);
581 enum tree_code code = TREE_CODE (decl);
583 location_t loc = DECL_SOURCE_LOCATION (decl);
585 if (code == CONST_DECL)
588 gcc_assert (code == VAR_DECL || code == PARM_DECL || code == RESULT_DECL
589 || code == TYPE_DECL ||code == FIELD_DECL);
591 rtl = DECL_RTL_IF_SET (decl);
593 if (type == error_mark_node)
594 type = void_type_node;
596 /* Usually the size and mode come from the data type without change,
597 however, the front-end may set the explicit width of the field, so its
598 size may not be the same as the size of its type. This happens with
599 bitfields, of course (an `int' bitfield may be only 2 bits, say), but it
600 also happens with other fields. For example, the C++ front-end creates
601 zero-sized fields corresponding to empty base classes, and depends on
602 layout_type setting DECL_FIELD_BITPOS correctly for the field. Set the
603 size in bytes from the size in bits. If we have already set the mode,
604 don't set it again since we can be called twice for FIELD_DECLs. */
606 DECL_UNSIGNED (decl) = TYPE_UNSIGNED (type);
607 if (DECL_MODE (decl) == VOIDmode)
608 DECL_MODE (decl) = TYPE_MODE (type);
610 if (DECL_SIZE (decl) == 0)
612 DECL_SIZE (decl) = TYPE_SIZE (type);
613 DECL_SIZE_UNIT (decl) = TYPE_SIZE_UNIT (type);
615 else if (DECL_SIZE_UNIT (decl) == 0)
616 DECL_SIZE_UNIT (decl)
617 = fold_convert_loc (loc, sizetype,
618 size_binop_loc (loc, CEIL_DIV_EXPR, DECL_SIZE (decl),
621 if (code != FIELD_DECL)
622 /* For non-fields, update the alignment from the type. */
623 do_type_align (type, decl);
625 /* For fields, it's a bit more complicated... */
627 bool old_user_align = DECL_USER_ALIGN (decl);
628 bool zero_bitfield = false;
629 bool packed_p = DECL_PACKED (decl);
632 if (DECL_BIT_FIELD (decl))
634 DECL_BIT_FIELD_TYPE (decl) = type;
636 /* A zero-length bit-field affects the alignment of the next
637 field. In essence such bit-fields are not influenced by
638 any packing due to #pragma pack or attribute packed. */
639 if (integer_zerop (DECL_SIZE (decl))
640 && ! targetm.ms_bitfield_layout_p (DECL_FIELD_CONTEXT (decl)))
642 zero_bitfield = true;
644 #ifdef PCC_BITFIELD_TYPE_MATTERS
645 if (PCC_BITFIELD_TYPE_MATTERS)
646 do_type_align (type, decl);
650 #ifdef EMPTY_FIELD_BOUNDARY
651 if (EMPTY_FIELD_BOUNDARY > DECL_ALIGN (decl))
653 DECL_ALIGN (decl) = EMPTY_FIELD_BOUNDARY;
654 DECL_USER_ALIGN (decl) = 0;
660 /* See if we can use an ordinary integer mode for a bit-field.
661 Conditions are: a fixed size that is correct for another mode,
662 occupying a complete byte or bytes on proper boundary,
663 and not -fstrict-volatile-bitfields. If the latter is set,
664 we unfortunately can't check TREE_THIS_VOLATILE, as a cast
665 may make a volatile object later. */
666 if (TYPE_SIZE (type) != 0
667 && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
668 && GET_MODE_CLASS (TYPE_MODE (type)) == MODE_INT
669 && flag_strict_volatile_bitfields <= 0)
671 enum machine_mode xmode
672 = mode_for_size_tree (DECL_SIZE (decl), MODE_INT, 1);
673 unsigned int xalign = GET_MODE_ALIGNMENT (xmode);
676 && !(xalign > BITS_PER_UNIT && DECL_PACKED (decl))
677 && (known_align == 0 || known_align >= xalign))
679 DECL_ALIGN (decl) = MAX (xalign, DECL_ALIGN (decl));
680 DECL_MODE (decl) = xmode;
681 DECL_BIT_FIELD (decl) = 0;
685 /* Turn off DECL_BIT_FIELD if we won't need it set. */
686 if (TYPE_MODE (type) == BLKmode && DECL_MODE (decl) == BLKmode
687 && known_align >= TYPE_ALIGN (type)
688 && DECL_ALIGN (decl) >= TYPE_ALIGN (type))
689 DECL_BIT_FIELD (decl) = 0;
691 else if (packed_p && DECL_USER_ALIGN (decl))
692 /* Don't touch DECL_ALIGN. For other packed fields, go ahead and
693 round up; we'll reduce it again below. We want packing to
694 supersede USER_ALIGN inherited from the type, but defer to
695 alignment explicitly specified on the field decl. */;
697 do_type_align (type, decl);
699 /* If the field is packed and not explicitly aligned, give it the
700 minimum alignment. Note that do_type_align may set
701 DECL_USER_ALIGN, so we need to check old_user_align instead. */
704 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), BITS_PER_UNIT);
706 if (! packed_p && ! DECL_USER_ALIGN (decl))
708 /* Some targets (i.e. i386, VMS) limit struct field alignment
709 to a lower boundary than alignment of variables unless
710 it was overridden by attribute aligned. */
711 #ifdef BIGGEST_FIELD_ALIGNMENT
713 = MIN (DECL_ALIGN (decl), (unsigned) BIGGEST_FIELD_ALIGNMENT);
715 #ifdef ADJUST_FIELD_ALIGN
716 DECL_ALIGN (decl) = ADJUST_FIELD_ALIGN (decl, DECL_ALIGN (decl));
721 mfa = initial_max_fld_align * BITS_PER_UNIT;
723 mfa = maximum_field_alignment;
724 /* Should this be controlled by DECL_USER_ALIGN, too? */
726 DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), mfa);
729 /* Evaluate nonconstant size only once, either now or as soon as safe. */
730 if (DECL_SIZE (decl) != 0 && TREE_CODE (DECL_SIZE (decl)) != INTEGER_CST)
731 DECL_SIZE (decl) = variable_size (DECL_SIZE (decl));
732 if (DECL_SIZE_UNIT (decl) != 0
733 && TREE_CODE (DECL_SIZE_UNIT (decl)) != INTEGER_CST)
734 DECL_SIZE_UNIT (decl) = variable_size (DECL_SIZE_UNIT (decl));
736 /* If requested, warn about definitions of large data objects. */
738 && (code == VAR_DECL || code == PARM_DECL)
739 && ! DECL_EXTERNAL (decl))
741 tree size = DECL_SIZE_UNIT (decl);
743 if (size != 0 && TREE_CODE (size) == INTEGER_CST
744 && compare_tree_int (size, larger_than_size) > 0)
746 int size_as_int = TREE_INT_CST_LOW (size);
748 if (compare_tree_int (size, size_as_int) == 0)
749 warning (OPT_Wlarger_than_, "size of %q+D is %d bytes", decl, size_as_int);
751 warning (OPT_Wlarger_than_, "size of %q+D is larger than %wd bytes",
752 decl, larger_than_size);
756 /* If the RTL was already set, update its mode and mem attributes. */
759 PUT_MODE (rtl, DECL_MODE (decl));
760 SET_DECL_RTL (decl, 0);
761 set_mem_attributes (rtl, decl, 1);
762 SET_DECL_RTL (decl, rtl);
766 /* Given a VAR_DECL, PARM_DECL or RESULT_DECL, clears the results of
767 a previous call to layout_decl and calls it again. */
770 relayout_decl (tree decl)
772 DECL_SIZE (decl) = DECL_SIZE_UNIT (decl) = 0;
773 DECL_MODE (decl) = VOIDmode;
774 if (!DECL_USER_ALIGN (decl))
775 DECL_ALIGN (decl) = 0;
776 SET_DECL_RTL (decl, 0);
778 layout_decl (decl, 0);
781 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
782 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
783 is to be passed to all other layout functions for this record. It is the
784 responsibility of the caller to call `free' for the storage returned.
785 Note that garbage collection is not permitted until we finish laying
789 start_record_layout (tree t)
791 record_layout_info rli = XNEW (struct record_layout_info_s);
795 /* If the type has a minimum specified alignment (via an attribute
796 declaration, for example) use it -- otherwise, start with a
797 one-byte alignment. */
798 rli->record_align = MAX (BITS_PER_UNIT, TYPE_ALIGN (t));
799 rli->unpacked_align = rli->record_align;
800 rli->offset_align = MAX (rli->record_align, BIGGEST_ALIGNMENT);
802 #ifdef STRUCTURE_SIZE_BOUNDARY
803 /* Packed structures don't need to have minimum size. */
804 if (! TYPE_PACKED (t))
808 /* #pragma pack overrides STRUCTURE_SIZE_BOUNDARY. */
809 tmp = (unsigned) STRUCTURE_SIZE_BOUNDARY;
810 if (maximum_field_alignment != 0)
811 tmp = MIN (tmp, maximum_field_alignment);
812 rli->record_align = MAX (rli->record_align, tmp);
816 rli->offset = size_zero_node;
817 rli->bitpos = bitsize_zero_node;
819 rli->pending_statics = NULL;
820 rli->packed_maybe_necessary = 0;
821 rli->remaining_in_alignment = 0;
826 /* These four routines perform computations that convert between
827 the offset/bitpos forms and byte and bit offsets. */
830 bit_from_pos (tree offset, tree bitpos)
832 return size_binop (PLUS_EXPR, bitpos,
833 size_binop (MULT_EXPR,
834 fold_convert (bitsizetype, offset),
839 byte_from_pos (tree offset, tree bitpos)
841 return size_binop (PLUS_EXPR, offset,
842 fold_convert (sizetype,
843 size_binop (TRUNC_DIV_EXPR, bitpos,
844 bitsize_unit_node)));
848 pos_from_bit (tree *poffset, tree *pbitpos, unsigned int off_align,
851 *poffset = size_binop (MULT_EXPR,
852 fold_convert (sizetype,
853 size_binop (FLOOR_DIV_EXPR, pos,
854 bitsize_int (off_align))),
855 size_int (off_align / BITS_PER_UNIT));
856 *pbitpos = size_binop (FLOOR_MOD_EXPR, pos, bitsize_int (off_align));
859 /* Given a pointer to bit and byte offsets and an offset alignment,
860 normalize the offsets so they are within the alignment. */
863 normalize_offset (tree *poffset, tree *pbitpos, unsigned int off_align)
865 /* If the bit position is now larger than it should be, adjust it
867 if (compare_tree_int (*pbitpos, off_align) >= 0)
869 tree extra_aligns = size_binop (FLOOR_DIV_EXPR, *pbitpos,
870 bitsize_int (off_align));
873 = size_binop (PLUS_EXPR, *poffset,
874 size_binop (MULT_EXPR,
875 fold_convert (sizetype, extra_aligns),
876 size_int (off_align / BITS_PER_UNIT)));
879 = size_binop (FLOOR_MOD_EXPR, *pbitpos, bitsize_int (off_align));
883 /* Print debugging information about the information in RLI. */
886 debug_rli (record_layout_info rli)
888 print_node_brief (stderr, "type", rli->t, 0);
889 print_node_brief (stderr, "\noffset", rli->offset, 0);
890 print_node_brief (stderr, " bitpos", rli->bitpos, 0);
892 fprintf (stderr, "\naligns: rec = %u, unpack = %u, off = %u\n",
893 rli->record_align, rli->unpacked_align,
896 /* The ms_struct code is the only that uses this. */
897 if (targetm.ms_bitfield_layout_p (rli->t))
898 fprintf (stderr, "remaining in alignment = %u\n", rli->remaining_in_alignment);
900 if (rli->packed_maybe_necessary)
901 fprintf (stderr, "packed may be necessary\n");
903 if (!VEC_empty (tree, rli->pending_statics))
905 fprintf (stderr, "pending statics:\n");
906 debug_vec_tree (rli->pending_statics);
910 /* Given an RLI with a possibly-incremented BITPOS, adjust OFFSET and
911 BITPOS if necessary to keep BITPOS below OFFSET_ALIGN. */
914 normalize_rli (record_layout_info rli)
916 normalize_offset (&rli->offset, &rli->bitpos, rli->offset_align);
919 /* Returns the size in bytes allocated so far. */
922 rli_size_unit_so_far (record_layout_info rli)
924 return byte_from_pos (rli->offset, rli->bitpos);
927 /* Returns the size in bits allocated so far. */
930 rli_size_so_far (record_layout_info rli)
932 return bit_from_pos (rli->offset, rli->bitpos);
935 /* FIELD is about to be added to RLI->T. The alignment (in bits) of
936 the next available location within the record is given by KNOWN_ALIGN.
937 Update the variable alignment fields in RLI, and return the alignment
938 to give the FIELD. */
941 update_alignment_for_field (record_layout_info rli, tree field,
942 unsigned int known_align)
944 /* The alignment required for FIELD. */
945 unsigned int desired_align;
946 /* The type of this field. */
947 tree type = TREE_TYPE (field);
948 /* True if the field was explicitly aligned by the user. */
952 /* Do not attempt to align an ERROR_MARK node */
953 if (TREE_CODE (type) == ERROR_MARK)
956 /* Lay out the field so we know what alignment it needs. */
957 layout_decl (field, known_align);
958 desired_align = DECL_ALIGN (field);
959 user_align = DECL_USER_ALIGN (field);
961 is_bitfield = (type != error_mark_node
962 && DECL_BIT_FIELD_TYPE (field)
963 && ! integer_zerop (TYPE_SIZE (type)));
965 /* Record must have at least as much alignment as any field.
966 Otherwise, the alignment of the field within the record is
968 if (targetm.ms_bitfield_layout_p (rli->t))
970 /* Here, the alignment of the underlying type of a bitfield can
971 affect the alignment of a record; even a zero-sized field
972 can do this. The alignment should be to the alignment of
973 the type, except that for zero-size bitfields this only
974 applies if there was an immediately prior, nonzero-size
975 bitfield. (That's the way it is, experimentally.) */
976 if ((!is_bitfield && !DECL_PACKED (field))
977 || (!integer_zerop (DECL_SIZE (field))
978 ? !DECL_PACKED (field)
980 && DECL_BIT_FIELD_TYPE (rli->prev_field)
981 && ! integer_zerop (DECL_SIZE (rli->prev_field)))))
983 unsigned int type_align = TYPE_ALIGN (type);
984 type_align = MAX (type_align, desired_align);
985 if (maximum_field_alignment != 0)
986 type_align = MIN (type_align, maximum_field_alignment);
987 rli->record_align = MAX (rli->record_align, type_align);
988 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
991 #ifdef PCC_BITFIELD_TYPE_MATTERS
992 else if (is_bitfield && PCC_BITFIELD_TYPE_MATTERS)
994 /* Named bit-fields cause the entire structure to have the
995 alignment implied by their type. Some targets also apply the same
996 rules to unnamed bitfields. */
997 if (DECL_NAME (field) != 0
998 || targetm.align_anon_bitfield ())
1000 unsigned int type_align = TYPE_ALIGN (type);
1002 #ifdef ADJUST_FIELD_ALIGN
1003 if (! TYPE_USER_ALIGN (type))
1004 type_align = ADJUST_FIELD_ALIGN (field, type_align);
1007 /* Targets might chose to handle unnamed and hence possibly
1008 zero-width bitfield. Those are not influenced by #pragmas
1009 or packed attributes. */
1010 if (integer_zerop (DECL_SIZE (field)))
1012 if (initial_max_fld_align)
1013 type_align = MIN (type_align,
1014 initial_max_fld_align * BITS_PER_UNIT);
1016 else if (maximum_field_alignment != 0)
1017 type_align = MIN (type_align, maximum_field_alignment);
1018 else if (DECL_PACKED (field))
1019 type_align = MIN (type_align, BITS_PER_UNIT);
1021 /* The alignment of the record is increased to the maximum
1022 of the current alignment, the alignment indicated on the
1023 field (i.e., the alignment specified by an __aligned__
1024 attribute), and the alignment indicated by the type of
1026 rli->record_align = MAX (rli->record_align, desired_align);
1027 rli->record_align = MAX (rli->record_align, type_align);
1030 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
1031 user_align |= TYPE_USER_ALIGN (type);
1037 rli->record_align = MAX (rli->record_align, desired_align);
1038 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
1041 TYPE_USER_ALIGN (rli->t) |= user_align;
1043 return desired_align;
1046 /* Called from place_field to handle unions. */
1049 place_union_field (record_layout_info rli, tree field)
1051 update_alignment_for_field (rli, field, /*known_align=*/0);
1053 DECL_FIELD_OFFSET (field) = size_zero_node;
1054 DECL_FIELD_BIT_OFFSET (field) = bitsize_zero_node;
1055 SET_DECL_OFFSET_ALIGN (field, BIGGEST_ALIGNMENT);
1057 /* If this is an ERROR_MARK return *after* having set the
1058 field at the start of the union. This helps when parsing
1060 if (TREE_CODE (TREE_TYPE (field)) == ERROR_MARK)
1063 /* We assume the union's size will be a multiple of a byte so we don't
1064 bother with BITPOS. */
1065 if (TREE_CODE (rli->t) == UNION_TYPE)
1066 rli->offset = size_binop (MAX_EXPR, rli->offset, DECL_SIZE_UNIT (field));
1067 else if (TREE_CODE (rli->t) == QUAL_UNION_TYPE)
1068 rli->offset = fold_build3 (COND_EXPR, sizetype, DECL_QUALIFIER (field),
1069 DECL_SIZE_UNIT (field), rli->offset);
1072 #if defined (PCC_BITFIELD_TYPE_MATTERS) || defined (BITFIELD_NBYTES_LIMITED)
1073 /* A bitfield of SIZE with a required access alignment of ALIGN is allocated
1074 at BYTE_OFFSET / BIT_OFFSET. Return nonzero if the field would span more
1075 units of alignment than the underlying TYPE. */
1077 excess_unit_span (HOST_WIDE_INT byte_offset, HOST_WIDE_INT bit_offset,
1078 HOST_WIDE_INT size, HOST_WIDE_INT align, tree type)
1080 /* Note that the calculation of OFFSET might overflow; we calculate it so
1081 that we still get the right result as long as ALIGN is a power of two. */
1082 unsigned HOST_WIDE_INT offset = byte_offset * BITS_PER_UNIT + bit_offset;
1084 offset = offset % align;
1085 return ((offset + size + align - 1) / align
1086 > ((unsigned HOST_WIDE_INT) tree_low_cst (TYPE_SIZE (type), 1)
1091 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
1092 is a FIELD_DECL to be added after those fields already present in
1093 T. (FIELD is not actually added to the TYPE_FIELDS list here;
1094 callers that desire that behavior must manually perform that step.) */
1097 place_field (record_layout_info rli, tree field)
1099 /* The alignment required for FIELD. */
1100 unsigned int desired_align;
1101 /* The alignment FIELD would have if we just dropped it into the
1102 record as it presently stands. */
1103 unsigned int known_align;
1104 unsigned int actual_align;
1105 /* The type of this field. */
1106 tree type = TREE_TYPE (field);
1108 gcc_assert (TREE_CODE (field) != ERROR_MARK);
1110 /* If FIELD is static, then treat it like a separate variable, not
1111 really like a structure field. If it is a FUNCTION_DECL, it's a
1112 method. In both cases, all we do is lay out the decl, and we do
1113 it *after* the record is laid out. */
1114 if (TREE_CODE (field) == VAR_DECL)
1116 VEC_safe_push (tree, gc, rli->pending_statics, field);
1120 /* Enumerators and enum types which are local to this class need not
1121 be laid out. Likewise for initialized constant fields. */
1122 else if (TREE_CODE (field) != FIELD_DECL)
1125 /* Unions are laid out very differently than records, so split
1126 that code off to another function. */
1127 else if (TREE_CODE (rli->t) != RECORD_TYPE)
1129 place_union_field (rli, field);
1133 else if (TREE_CODE (type) == ERROR_MARK)
1135 /* Place this field at the current allocation position, so we
1136 maintain monotonicity. */
1137 DECL_FIELD_OFFSET (field) = rli->offset;
1138 DECL_FIELD_BIT_OFFSET (field) = rli->bitpos;
1139 SET_DECL_OFFSET_ALIGN (field, rli->offset_align);
1143 /* Work out the known alignment so far. Note that A & (-A) is the
1144 value of the least-significant bit in A that is one. */
1145 if (! integer_zerop (rli->bitpos))
1146 known_align = (tree_low_cst (rli->bitpos, 1)
1147 & - tree_low_cst (rli->bitpos, 1));
1148 else if (integer_zerop (rli->offset))
1150 else if (host_integerp (rli->offset, 1))
1151 known_align = (BITS_PER_UNIT
1152 * (tree_low_cst (rli->offset, 1)
1153 & - tree_low_cst (rli->offset, 1)));
1155 known_align = rli->offset_align;
1157 desired_align = update_alignment_for_field (rli, field, known_align);
1158 if (known_align == 0)
1159 known_align = MAX (BIGGEST_ALIGNMENT, rli->record_align);
1161 if (warn_packed && DECL_PACKED (field))
1163 if (known_align >= TYPE_ALIGN (type))
1165 if (TYPE_ALIGN (type) > desired_align)
1167 if (STRICT_ALIGNMENT)
1168 warning (OPT_Wattributes, "packed attribute causes "
1169 "inefficient alignment for %q+D", field);
1170 /* Don't warn if DECL_PACKED was set by the type. */
1171 else if (!TYPE_PACKED (rli->t))
1172 warning (OPT_Wattributes, "packed attribute is "
1173 "unnecessary for %q+D", field);
1177 rli->packed_maybe_necessary = 1;
1180 /* Does this field automatically have alignment it needs by virtue
1181 of the fields that precede it and the record's own alignment? */
1182 if (known_align < desired_align)
1184 /* No, we need to skip space before this field.
1185 Bump the cumulative size to multiple of field alignment. */
1187 if (!targetm.ms_bitfield_layout_p (rli->t)
1188 && DECL_SOURCE_LOCATION (field) != BUILTINS_LOCATION)
1189 warning (OPT_Wpadded, "padding struct to align %q+D", field);
1191 /* If the alignment is still within offset_align, just align
1192 the bit position. */
1193 if (desired_align < rli->offset_align)
1194 rli->bitpos = round_up (rli->bitpos, desired_align);
1197 /* First adjust OFFSET by the partial bits, then align. */
1199 = size_binop (PLUS_EXPR, rli->offset,
1200 fold_convert (sizetype,
1201 size_binop (CEIL_DIV_EXPR, rli->bitpos,
1202 bitsize_unit_node)));
1203 rli->bitpos = bitsize_zero_node;
1205 rli->offset = round_up (rli->offset, desired_align / BITS_PER_UNIT);
1208 if (! TREE_CONSTANT (rli->offset))
1209 rli->offset_align = desired_align;
1210 if (targetm.ms_bitfield_layout_p (rli->t))
1211 rli->prev_field = NULL;
1214 /* Handle compatibility with PCC. Note that if the record has any
1215 variable-sized fields, we need not worry about compatibility. */
1216 #ifdef PCC_BITFIELD_TYPE_MATTERS
1217 if (PCC_BITFIELD_TYPE_MATTERS
1218 && ! targetm.ms_bitfield_layout_p (rli->t)
1219 && TREE_CODE (field) == FIELD_DECL
1220 && type != error_mark_node
1221 && DECL_BIT_FIELD (field)
1222 && (! DECL_PACKED (field)
1223 /* Enter for these packed fields only to issue a warning. */
1224 || TYPE_ALIGN (type) <= BITS_PER_UNIT)
1225 && maximum_field_alignment == 0
1226 && ! integer_zerop (DECL_SIZE (field))
1227 && host_integerp (DECL_SIZE (field), 1)
1228 && host_integerp (rli->offset, 1)
1229 && host_integerp (TYPE_SIZE (type), 1))
1231 unsigned int type_align = TYPE_ALIGN (type);
1232 tree dsize = DECL_SIZE (field);
1233 HOST_WIDE_INT field_size = tree_low_cst (dsize, 1);
1234 HOST_WIDE_INT offset = tree_low_cst (rli->offset, 0);
1235 HOST_WIDE_INT bit_offset = tree_low_cst (rli->bitpos, 0);
1237 #ifdef ADJUST_FIELD_ALIGN
1238 if (! TYPE_USER_ALIGN (type))
1239 type_align = ADJUST_FIELD_ALIGN (field, type_align);
1242 /* A bit field may not span more units of alignment of its type
1243 than its type itself. Advance to next boundary if necessary. */
1244 if (excess_unit_span (offset, bit_offset, field_size, type_align, type))
1246 if (DECL_PACKED (field))
1248 if (warn_packed_bitfield_compat == 1)
1251 "offset of packed bit-field %qD has changed in GCC 4.4",
1255 rli->bitpos = round_up (rli->bitpos, type_align);
1258 if (! DECL_PACKED (field))
1259 TYPE_USER_ALIGN (rli->t) |= TYPE_USER_ALIGN (type);
1263 #ifdef BITFIELD_NBYTES_LIMITED
1264 if (BITFIELD_NBYTES_LIMITED
1265 && ! targetm.ms_bitfield_layout_p (rli->t)
1266 && TREE_CODE (field) == FIELD_DECL
1267 && type != error_mark_node
1268 && DECL_BIT_FIELD_TYPE (field)
1269 && ! DECL_PACKED (field)
1270 && ! integer_zerop (DECL_SIZE (field))
1271 && host_integerp (DECL_SIZE (field), 1)
1272 && host_integerp (rli->offset, 1)
1273 && host_integerp (TYPE_SIZE (type), 1))
1275 unsigned int type_align = TYPE_ALIGN (type);
1276 tree dsize = DECL_SIZE (field);
1277 HOST_WIDE_INT field_size = tree_low_cst (dsize, 1);
1278 HOST_WIDE_INT offset = tree_low_cst (rli->offset, 0);
1279 HOST_WIDE_INT bit_offset = tree_low_cst (rli->bitpos, 0);
1281 #ifdef ADJUST_FIELD_ALIGN
1282 if (! TYPE_USER_ALIGN (type))
1283 type_align = ADJUST_FIELD_ALIGN (field, type_align);
1286 if (maximum_field_alignment != 0)
1287 type_align = MIN (type_align, maximum_field_alignment);
1288 /* ??? This test is opposite the test in the containing if
1289 statement, so this code is unreachable currently. */
1290 else if (DECL_PACKED (field))
1291 type_align = MIN (type_align, BITS_PER_UNIT);
1293 /* A bit field may not span the unit of alignment of its type.
1294 Advance to next boundary if necessary. */
1295 if (excess_unit_span (offset, bit_offset, field_size, type_align, type))
1296 rli->bitpos = round_up (rli->bitpos, type_align);
1298 TYPE_USER_ALIGN (rli->t) |= TYPE_USER_ALIGN (type);
1302 /* See the docs for TARGET_MS_BITFIELD_LAYOUT_P for details.
1304 When a bit field is inserted into a packed record, the whole
1305 size of the underlying type is used by one or more same-size
1306 adjacent bitfields. (That is, if its long:3, 32 bits is
1307 used in the record, and any additional adjacent long bitfields are
1308 packed into the same chunk of 32 bits. However, if the size
1309 changes, a new field of that size is allocated.) In an unpacked
1310 record, this is the same as using alignment, but not equivalent
1313 Note: for compatibility, we use the type size, not the type alignment
1314 to determine alignment, since that matches the documentation */
1316 if (targetm.ms_bitfield_layout_p (rli->t))
1318 tree prev_saved = rli->prev_field;
1319 tree prev_type = prev_saved ? DECL_BIT_FIELD_TYPE (prev_saved) : NULL;
1321 /* This is a bitfield if it exists. */
1322 if (rli->prev_field)
1324 /* If both are bitfields, nonzero, and the same size, this is
1325 the middle of a run. Zero declared size fields are special
1326 and handled as "end of run". (Note: it's nonzero declared
1327 size, but equal type sizes!) (Since we know that both
1328 the current and previous fields are bitfields by the
1329 time we check it, DECL_SIZE must be present for both.) */
1330 if (DECL_BIT_FIELD_TYPE (field)
1331 && !integer_zerop (DECL_SIZE (field))
1332 && !integer_zerop (DECL_SIZE (rli->prev_field))
1333 && host_integerp (DECL_SIZE (rli->prev_field), 0)
1334 && host_integerp (TYPE_SIZE (type), 0)
1335 && simple_cst_equal (TYPE_SIZE (type), TYPE_SIZE (prev_type)))
1337 /* We're in the middle of a run of equal type size fields; make
1338 sure we realign if we run out of bits. (Not decl size,
1340 HOST_WIDE_INT bitsize = tree_low_cst (DECL_SIZE (field), 1);
1342 if (rli->remaining_in_alignment < bitsize)
1344 HOST_WIDE_INT typesize = tree_low_cst (TYPE_SIZE (type), 1);
1346 /* out of bits; bump up to next 'word'. */
1348 = size_binop (PLUS_EXPR, rli->bitpos,
1349 bitsize_int (rli->remaining_in_alignment));
1350 rli->prev_field = field;
1351 if (typesize < bitsize)
1352 rli->remaining_in_alignment = 0;
1354 rli->remaining_in_alignment = typesize - bitsize;
1357 rli->remaining_in_alignment -= bitsize;
1361 /* End of a run: if leaving a run of bitfields of the same type
1362 size, we have to "use up" the rest of the bits of the type
1365 Compute the new position as the sum of the size for the prior
1366 type and where we first started working on that type.
1367 Note: since the beginning of the field was aligned then
1368 of course the end will be too. No round needed. */
1370 if (!integer_zerop (DECL_SIZE (rli->prev_field)))
1373 = size_binop (PLUS_EXPR, rli->bitpos,
1374 bitsize_int (rli->remaining_in_alignment));
1377 /* We "use up" size zero fields; the code below should behave
1378 as if the prior field was not a bitfield. */
1381 /* Cause a new bitfield to be captured, either this time (if
1382 currently a bitfield) or next time we see one. */
1383 if (!DECL_BIT_FIELD_TYPE(field)
1384 || integer_zerop (DECL_SIZE (field)))
1385 rli->prev_field = NULL;
1388 normalize_rli (rli);
1391 /* If we're starting a new run of same size type bitfields
1392 (or a run of non-bitfields), set up the "first of the run"
1395 That is, if the current field is not a bitfield, or if there
1396 was a prior bitfield the type sizes differ, or if there wasn't
1397 a prior bitfield the size of the current field is nonzero.
1399 Note: we must be sure to test ONLY the type size if there was
1400 a prior bitfield and ONLY for the current field being zero if
1403 if (!DECL_BIT_FIELD_TYPE (field)
1404 || (prev_saved != NULL
1405 ? !simple_cst_equal (TYPE_SIZE (type), TYPE_SIZE (prev_type))
1406 : !integer_zerop (DECL_SIZE (field)) ))
1408 /* Never smaller than a byte for compatibility. */
1409 unsigned int type_align = BITS_PER_UNIT;
1411 /* (When not a bitfield), we could be seeing a flex array (with
1412 no DECL_SIZE). Since we won't be using remaining_in_alignment
1413 until we see a bitfield (and come by here again) we just skip
1415 if (DECL_SIZE (field) != NULL
1416 && host_integerp (TYPE_SIZE (TREE_TYPE (field)), 1)
1417 && host_integerp (DECL_SIZE (field), 1))
1419 unsigned HOST_WIDE_INT bitsize
1420 = tree_low_cst (DECL_SIZE (field), 1);
1421 unsigned HOST_WIDE_INT typesize
1422 = tree_low_cst (TYPE_SIZE (TREE_TYPE (field)), 1);
1424 if (typesize < bitsize)
1425 rli->remaining_in_alignment = 0;
1427 rli->remaining_in_alignment = typesize - bitsize;
1430 /* Now align (conventionally) for the new type. */
1431 type_align = TYPE_ALIGN (TREE_TYPE (field));
1433 if (maximum_field_alignment != 0)
1434 type_align = MIN (type_align, maximum_field_alignment);
1436 rli->bitpos = round_up (rli->bitpos, type_align);
1438 /* If we really aligned, don't allow subsequent bitfields
1440 rli->prev_field = NULL;
1444 /* Offset so far becomes the position of this field after normalizing. */
1445 normalize_rli (rli);
1446 DECL_FIELD_OFFSET (field) = rli->offset;
1447 DECL_FIELD_BIT_OFFSET (field) = rli->bitpos;
1448 SET_DECL_OFFSET_ALIGN (field, rli->offset_align);
1450 /* If this field ended up more aligned than we thought it would be (we
1451 approximate this by seeing if its position changed), lay out the field
1452 again; perhaps we can use an integral mode for it now. */
1453 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field)))
1454 actual_align = (tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1)
1455 & - tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1));
1456 else if (integer_zerop (DECL_FIELD_OFFSET (field)))
1457 actual_align = MAX (BIGGEST_ALIGNMENT, rli->record_align);
1458 else if (host_integerp (DECL_FIELD_OFFSET (field), 1))
1459 actual_align = (BITS_PER_UNIT
1460 * (tree_low_cst (DECL_FIELD_OFFSET (field), 1)
1461 & - tree_low_cst (DECL_FIELD_OFFSET (field), 1)));
1463 actual_align = DECL_OFFSET_ALIGN (field);
1464 /* ACTUAL_ALIGN is still the actual alignment *within the record* .
1465 store / extract bit field operations will check the alignment of the
1466 record against the mode of bit fields. */
1468 if (known_align != actual_align)
1469 layout_decl (field, actual_align);
1471 if (rli->prev_field == NULL && DECL_BIT_FIELD_TYPE (field))
1472 rli->prev_field = field;
1474 /* Now add size of this field to the size of the record. If the size is
1475 not constant, treat the field as being a multiple of bytes and just
1476 adjust the offset, resetting the bit position. Otherwise, apportion the
1477 size amongst the bit position and offset. First handle the case of an
1478 unspecified size, which can happen when we have an invalid nested struct
1479 definition, such as struct j { struct j { int i; } }. The error message
1480 is printed in finish_struct. */
1481 if (DECL_SIZE (field) == 0)
1483 else if (TREE_CODE (DECL_SIZE (field)) != INTEGER_CST
1484 || TREE_OVERFLOW (DECL_SIZE (field)))
1487 = size_binop (PLUS_EXPR, rli->offset,
1488 fold_convert (sizetype,
1489 size_binop (CEIL_DIV_EXPR, rli->bitpos,
1490 bitsize_unit_node)));
1492 = size_binop (PLUS_EXPR, rli->offset, DECL_SIZE_UNIT (field));
1493 rli->bitpos = bitsize_zero_node;
1494 rli->offset_align = MIN (rli->offset_align, desired_align);
1496 else if (targetm.ms_bitfield_layout_p (rli->t))
1498 rli->bitpos = size_binop (PLUS_EXPR, rli->bitpos, DECL_SIZE (field));
1500 /* If we ended a bitfield before the full length of the type then
1501 pad the struct out to the full length of the last type. */
1502 if ((DECL_CHAIN (field) == NULL
1503 || TREE_CODE (DECL_CHAIN (field)) != FIELD_DECL)
1504 && DECL_BIT_FIELD_TYPE (field)
1505 && !integer_zerop (DECL_SIZE (field)))
1506 rli->bitpos = size_binop (PLUS_EXPR, rli->bitpos,
1507 bitsize_int (rli->remaining_in_alignment));
1509 normalize_rli (rli);
1513 rli->bitpos = size_binop (PLUS_EXPR, rli->bitpos, DECL_SIZE (field));
1514 normalize_rli (rli);
1518 /* Assuming that all the fields have been laid out, this function uses
1519 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
1520 indicated by RLI. */
1523 finalize_record_size (record_layout_info rli)
1525 tree unpadded_size, unpadded_size_unit;
1527 /* Now we want just byte and bit offsets, so set the offset alignment
1528 to be a byte and then normalize. */
1529 rli->offset_align = BITS_PER_UNIT;
1530 normalize_rli (rli);
1532 /* Determine the desired alignment. */
1533 #ifdef ROUND_TYPE_ALIGN
1534 TYPE_ALIGN (rli->t) = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t),
1537 TYPE_ALIGN (rli->t) = MAX (TYPE_ALIGN (rli->t), rli->record_align);
1540 /* Compute the size so far. Be sure to allow for extra bits in the
1541 size in bytes. We have guaranteed above that it will be no more
1542 than a single byte. */
1543 unpadded_size = rli_size_so_far (rli);
1544 unpadded_size_unit = rli_size_unit_so_far (rli);
1545 if (! integer_zerop (rli->bitpos))
1547 = size_binop (PLUS_EXPR, unpadded_size_unit, size_one_node);
1549 /* Round the size up to be a multiple of the required alignment. */
1550 TYPE_SIZE (rli->t) = round_up (unpadded_size, TYPE_ALIGN (rli->t));
1551 TYPE_SIZE_UNIT (rli->t)
1552 = round_up (unpadded_size_unit, TYPE_ALIGN_UNIT (rli->t));
1554 if (TREE_CONSTANT (unpadded_size)
1555 && simple_cst_equal (unpadded_size, TYPE_SIZE (rli->t)) == 0
1556 && input_location != BUILTINS_LOCATION)
1557 warning (OPT_Wpadded, "padding struct size to alignment boundary");
1559 if (warn_packed && TREE_CODE (rli->t) == RECORD_TYPE
1560 && TYPE_PACKED (rli->t) && ! rli->packed_maybe_necessary
1561 && TREE_CONSTANT (unpadded_size))
1565 #ifdef ROUND_TYPE_ALIGN
1567 = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t), rli->unpacked_align);
1569 rli->unpacked_align = MAX (TYPE_ALIGN (rli->t), rli->unpacked_align);
1572 unpacked_size = round_up (TYPE_SIZE (rli->t), rli->unpacked_align);
1573 if (simple_cst_equal (unpacked_size, TYPE_SIZE (rli->t)))
1575 if (TYPE_NAME (rli->t))
1579 if (TREE_CODE (TYPE_NAME (rli->t)) == IDENTIFIER_NODE)
1580 name = TYPE_NAME (rli->t);
1582 name = DECL_NAME (TYPE_NAME (rli->t));
1584 if (STRICT_ALIGNMENT)
1585 warning (OPT_Wpacked, "packed attribute causes inefficient "
1586 "alignment for %qE", name);
1588 warning (OPT_Wpacked,
1589 "packed attribute is unnecessary for %qE", name);
1593 if (STRICT_ALIGNMENT)
1594 warning (OPT_Wpacked,
1595 "packed attribute causes inefficient alignment");
1597 warning (OPT_Wpacked, "packed attribute is unnecessary");
1603 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
1606 compute_record_mode (tree type)
1609 enum machine_mode mode = VOIDmode;
1611 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
1612 However, if possible, we use a mode that fits in a register
1613 instead, in order to allow for better optimization down the
1615 SET_TYPE_MODE (type, BLKmode);
1617 if (! host_integerp (TYPE_SIZE (type), 1))
1620 /* A record which has any BLKmode members must itself be
1621 BLKmode; it can't go in a register. Unless the member is
1622 BLKmode only because it isn't aligned. */
1623 for (field = TYPE_FIELDS (type); field; field = DECL_CHAIN (field))
1625 if (TREE_CODE (field) != FIELD_DECL)
1628 if (TREE_CODE (TREE_TYPE (field)) == ERROR_MARK
1629 || (TYPE_MODE (TREE_TYPE (field)) == BLKmode
1630 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field))
1631 && !(TYPE_SIZE (TREE_TYPE (field)) != 0
1632 && integer_zerop (TYPE_SIZE (TREE_TYPE (field)))))
1633 || ! host_integerp (bit_position (field), 1)
1634 || DECL_SIZE (field) == 0
1635 || ! host_integerp (DECL_SIZE (field), 1))
1638 /* If this field is the whole struct, remember its mode so
1639 that, say, we can put a double in a class into a DF
1640 register instead of forcing it to live in the stack. */
1641 if (simple_cst_equal (TYPE_SIZE (type), DECL_SIZE (field)))
1642 mode = DECL_MODE (field);
1644 #ifdef MEMBER_TYPE_FORCES_BLK
1645 /* With some targets, eg. c4x, it is sub-optimal
1646 to access an aligned BLKmode structure as a scalar. */
1648 if (MEMBER_TYPE_FORCES_BLK (field, mode))
1650 #endif /* MEMBER_TYPE_FORCES_BLK */
1653 /* If we only have one real field; use its mode if that mode's size
1654 matches the type's size. This only applies to RECORD_TYPE. This
1655 does not apply to unions. */
1656 if (TREE_CODE (type) == RECORD_TYPE && mode != VOIDmode
1657 && host_integerp (TYPE_SIZE (type), 1)
1658 && GET_MODE_BITSIZE (mode) == TREE_INT_CST_LOW (TYPE_SIZE (type)))
1659 SET_TYPE_MODE (type, mode);
1661 SET_TYPE_MODE (type, mode_for_size_tree (TYPE_SIZE (type), MODE_INT, 1));
1663 /* If structure's known alignment is less than what the scalar
1664 mode would need, and it matters, then stick with BLKmode. */
1665 if (TYPE_MODE (type) != BLKmode
1667 && ! (TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT
1668 || TYPE_ALIGN (type) >= GET_MODE_ALIGNMENT (TYPE_MODE (type))))
1670 /* If this is the only reason this type is BLKmode, then
1671 don't force containing types to be BLKmode. */
1672 TYPE_NO_FORCE_BLK (type) = 1;
1673 SET_TYPE_MODE (type, BLKmode);
1677 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1681 finalize_type_size (tree type)
1683 /* Normally, use the alignment corresponding to the mode chosen.
1684 However, where strict alignment is not required, avoid
1685 over-aligning structures, since most compilers do not do this
1688 if (TYPE_MODE (type) != BLKmode && TYPE_MODE (type) != VOIDmode
1689 && (STRICT_ALIGNMENT
1690 || (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE
1691 && TREE_CODE (type) != QUAL_UNION_TYPE
1692 && TREE_CODE (type) != ARRAY_TYPE)))
1694 unsigned mode_align = GET_MODE_ALIGNMENT (TYPE_MODE (type));
1696 /* Don't override a larger alignment requirement coming from a user
1697 alignment of one of the fields. */
1698 if (mode_align >= TYPE_ALIGN (type))
1700 TYPE_ALIGN (type) = mode_align;
1701 TYPE_USER_ALIGN (type) = 0;
1705 /* Do machine-dependent extra alignment. */
1706 #ifdef ROUND_TYPE_ALIGN
1708 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (type), BITS_PER_UNIT);
1711 /* If we failed to find a simple way to calculate the unit size
1712 of the type, find it by division. */
1713 if (TYPE_SIZE_UNIT (type) == 0 && TYPE_SIZE (type) != 0)
1714 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1715 result will fit in sizetype. We will get more efficient code using
1716 sizetype, so we force a conversion. */
1717 TYPE_SIZE_UNIT (type)
1718 = fold_convert (sizetype,
1719 size_binop (FLOOR_DIV_EXPR, TYPE_SIZE (type),
1720 bitsize_unit_node));
1722 if (TYPE_SIZE (type) != 0)
1724 TYPE_SIZE (type) = round_up (TYPE_SIZE (type), TYPE_ALIGN (type));
1725 TYPE_SIZE_UNIT (type)
1726 = round_up (TYPE_SIZE_UNIT (type), TYPE_ALIGN_UNIT (type));
1729 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1730 if (TYPE_SIZE (type) != 0 && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
1731 TYPE_SIZE (type) = variable_size (TYPE_SIZE (type));
1732 if (TYPE_SIZE_UNIT (type) != 0
1733 && TREE_CODE (TYPE_SIZE_UNIT (type)) != INTEGER_CST)
1734 TYPE_SIZE_UNIT (type) = variable_size (TYPE_SIZE_UNIT (type));
1736 /* Also layout any other variants of the type. */
1737 if (TYPE_NEXT_VARIANT (type)
1738 || type != TYPE_MAIN_VARIANT (type))
1741 /* Record layout info of this variant. */
1742 tree size = TYPE_SIZE (type);
1743 tree size_unit = TYPE_SIZE_UNIT (type);
1744 unsigned int align = TYPE_ALIGN (type);
1745 unsigned int user_align = TYPE_USER_ALIGN (type);
1746 enum machine_mode mode = TYPE_MODE (type);
1748 /* Copy it into all variants. */
1749 for (variant = TYPE_MAIN_VARIANT (type);
1751 variant = TYPE_NEXT_VARIANT (variant))
1753 TYPE_SIZE (variant) = size;
1754 TYPE_SIZE_UNIT (variant) = size_unit;
1755 TYPE_ALIGN (variant) = align;
1756 TYPE_USER_ALIGN (variant) = user_align;
1757 SET_TYPE_MODE (variant, mode);
1762 /* Do all of the work required to layout the type indicated by RLI,
1763 once the fields have been laid out. This function will call `free'
1764 for RLI, unless FREE_P is false. Passing a value other than false
1765 for FREE_P is bad practice; this option only exists to support the
1769 finish_record_layout (record_layout_info rli, int free_p)
1773 /* Compute the final size. */
1774 finalize_record_size (rli);
1776 /* Compute the TYPE_MODE for the record. */
1777 compute_record_mode (rli->t);
1779 /* Perform any last tweaks to the TYPE_SIZE, etc. */
1780 finalize_type_size (rli->t);
1782 /* Propagate TYPE_PACKED to variants. With C++ templates,
1783 handle_packed_attribute is too early to do this. */
1784 for (variant = TYPE_NEXT_VARIANT (rli->t); variant;
1785 variant = TYPE_NEXT_VARIANT (variant))
1786 TYPE_PACKED (variant) = TYPE_PACKED (rli->t);
1788 /* Lay out any static members. This is done now because their type
1789 may use the record's type. */
1790 while (!VEC_empty (tree, rli->pending_statics))
1791 layout_decl (VEC_pop (tree, rli->pending_statics), 0);
1796 VEC_free (tree, gc, rli->pending_statics);
1802 /* Finish processing a builtin RECORD_TYPE type TYPE. It's name is
1803 NAME, its fields are chained in reverse on FIELDS.
1805 If ALIGN_TYPE is non-null, it is given the same alignment as
1809 finish_builtin_struct (tree type, const char *name, tree fields,
1814 for (tail = NULL_TREE; fields; tail = fields, fields = next)
1816 DECL_FIELD_CONTEXT (fields) = type;
1817 next = DECL_CHAIN (fields);
1818 DECL_CHAIN (fields) = tail;
1820 TYPE_FIELDS (type) = tail;
1824 TYPE_ALIGN (type) = TYPE_ALIGN (align_type);
1825 TYPE_USER_ALIGN (type) = TYPE_USER_ALIGN (align_type);
1829 #if 0 /* not yet, should get fixed properly later */
1830 TYPE_NAME (type) = make_type_decl (get_identifier (name), type);
1832 TYPE_NAME (type) = build_decl (BUILTINS_LOCATION,
1833 TYPE_DECL, get_identifier (name), type);
1835 TYPE_STUB_DECL (type) = TYPE_NAME (type);
1836 layout_decl (TYPE_NAME (type), 0);
1839 /* Calculate the mode, size, and alignment for TYPE.
1840 For an array type, calculate the element separation as well.
1841 Record TYPE on the chain of permanent or temporary types
1842 so that dbxout will find out about it.
1844 TYPE_SIZE of a type is nonzero if the type has been laid out already.
1845 layout_type does nothing on such a type.
1847 If the type is incomplete, its TYPE_SIZE remains zero. */
1850 layout_type (tree type)
1854 if (type == error_mark_node)
1857 /* Do nothing if type has been laid out before. */
1858 if (TYPE_SIZE (type))
1861 switch (TREE_CODE (type))
1864 /* This kind of type is the responsibility
1865 of the language-specific code. */
1868 case BOOLEAN_TYPE: /* Used for Java, Pascal, and Chill. */
1869 if (TYPE_PRECISION (type) == 0)
1870 TYPE_PRECISION (type) = 1; /* default to one byte/boolean. */
1872 /* ... fall through ... */
1876 if (TREE_CODE (TYPE_MIN_VALUE (type)) == INTEGER_CST
1877 && tree_int_cst_sgn (TYPE_MIN_VALUE (type)) >= 0)
1878 TYPE_UNSIGNED (type) = 1;
1880 SET_TYPE_MODE (type,
1881 smallest_mode_for_size (TYPE_PRECISION (type), MODE_INT));
1882 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1883 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1887 SET_TYPE_MODE (type,
1888 mode_for_size (TYPE_PRECISION (type), MODE_FLOAT, 0));
1889 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1890 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1893 case FIXED_POINT_TYPE:
1894 /* TYPE_MODE (type) has been set already. */
1895 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1896 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1900 TYPE_UNSIGNED (type) = TYPE_UNSIGNED (TREE_TYPE (type));
1901 SET_TYPE_MODE (type,
1902 mode_for_size (2 * TYPE_PRECISION (TREE_TYPE (type)),
1903 (TREE_CODE (TREE_TYPE (type)) == REAL_TYPE
1904 ? MODE_COMPLEX_FLOAT : MODE_COMPLEX_INT),
1906 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
1907 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
1912 int nunits = TYPE_VECTOR_SUBPARTS (type);
1913 tree innertype = TREE_TYPE (type);
1915 gcc_assert (!(nunits & (nunits - 1)));
1917 /* Find an appropriate mode for the vector type. */
1918 if (TYPE_MODE (type) == VOIDmode)
1919 SET_TYPE_MODE (type,
1920 mode_for_vector (TYPE_MODE (innertype), nunits));
1922 TYPE_SATURATING (type) = TYPE_SATURATING (TREE_TYPE (type));
1923 TYPE_UNSIGNED (type) = TYPE_UNSIGNED (TREE_TYPE (type));
1924 TYPE_SIZE_UNIT (type) = int_const_binop (MULT_EXPR,
1925 TYPE_SIZE_UNIT (innertype),
1926 size_int (nunits), 0);
1927 TYPE_SIZE (type) = int_const_binop (MULT_EXPR, TYPE_SIZE (innertype),
1928 bitsize_int (nunits), 0);
1930 /* For vector types, we do not default to the mode's alignment.
1931 Instead, query a target hook, defaulting to natural alignment.
1932 This prevents ABI changes depending on whether or not native
1933 vector modes are supported. */
1934 TYPE_ALIGN (type) = targetm.vector_alignment (type);
1936 /* However, if the underlying mode requires a bigger alignment than
1937 what the target hook provides, we cannot use the mode. For now,
1938 simply reject that case. */
1939 gcc_assert (TYPE_ALIGN (type)
1940 >= GET_MODE_ALIGNMENT (TYPE_MODE (type)));
1945 /* This is an incomplete type and so doesn't have a size. */
1946 TYPE_ALIGN (type) = 1;
1947 TYPE_USER_ALIGN (type) = 0;
1948 SET_TYPE_MODE (type, VOIDmode);
1952 TYPE_SIZE (type) = bitsize_int (POINTER_SIZE);
1953 TYPE_SIZE_UNIT (type) = size_int (POINTER_SIZE / BITS_PER_UNIT);
1954 /* A pointer might be MODE_PARTIAL_INT,
1955 but ptrdiff_t must be integral. */
1956 SET_TYPE_MODE (type, mode_for_size (POINTER_SIZE, MODE_INT, 0));
1957 TYPE_PRECISION (type) = POINTER_SIZE;
1962 /* It's hard to see what the mode and size of a function ought to
1963 be, but we do know the alignment is FUNCTION_BOUNDARY, so
1964 make it consistent with that. */
1965 SET_TYPE_MODE (type, mode_for_size (FUNCTION_BOUNDARY, MODE_INT, 0));
1966 TYPE_SIZE (type) = bitsize_int (FUNCTION_BOUNDARY);
1967 TYPE_SIZE_UNIT (type) = size_int (FUNCTION_BOUNDARY / BITS_PER_UNIT);
1971 case REFERENCE_TYPE:
1973 enum machine_mode mode = TYPE_MODE (type);
1974 if (TREE_CODE (type) == REFERENCE_TYPE && reference_types_internal)
1976 addr_space_t as = TYPE_ADDR_SPACE (TREE_TYPE (type));
1977 mode = targetm.addr_space.address_mode (as);
1980 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (mode));
1981 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (mode));
1982 TYPE_UNSIGNED (type) = 1;
1983 TYPE_PRECISION (type) = GET_MODE_BITSIZE (mode);
1989 tree index = TYPE_DOMAIN (type);
1990 tree element = TREE_TYPE (type);
1992 build_pointer_type (element);
1994 /* We need to know both bounds in order to compute the size. */
1995 if (index && TYPE_MAX_VALUE (index) && TYPE_MIN_VALUE (index)
1996 && TYPE_SIZE (element))
1998 tree ub = TYPE_MAX_VALUE (index);
1999 tree lb = TYPE_MIN_VALUE (index);
2000 tree element_size = TYPE_SIZE (element);
2003 /* Make sure that an array of zero-sized element is zero-sized
2004 regardless of its extent. */
2005 if (integer_zerop (element_size))
2006 length = size_zero_node;
2008 /* The initial subtraction should happen in the original type so
2009 that (possible) negative values are handled appropriately. */
2012 = size_binop (PLUS_EXPR, size_one_node,
2013 fold_convert (sizetype,
2014 fold_build2 (MINUS_EXPR,
2018 TYPE_SIZE (type) = size_binop (MULT_EXPR, element_size,
2019 fold_convert (bitsizetype,
2022 /* If we know the size of the element, calculate the total size
2023 directly, rather than do some division thing below. This
2024 optimization helps Fortran assumed-size arrays (where the
2025 size of the array is determined at runtime) substantially. */
2026 if (TYPE_SIZE_UNIT (element))
2027 TYPE_SIZE_UNIT (type)
2028 = size_binop (MULT_EXPR, TYPE_SIZE_UNIT (element), length);
2031 /* Now round the alignment and size,
2032 using machine-dependent criteria if any. */
2034 #ifdef ROUND_TYPE_ALIGN
2036 = ROUND_TYPE_ALIGN (type, TYPE_ALIGN (element), BITS_PER_UNIT);
2038 TYPE_ALIGN (type) = MAX (TYPE_ALIGN (element), BITS_PER_UNIT);
2040 TYPE_USER_ALIGN (type) = TYPE_USER_ALIGN (element);
2041 SET_TYPE_MODE (type, BLKmode);
2042 if (TYPE_SIZE (type) != 0
2043 #ifdef MEMBER_TYPE_FORCES_BLK
2044 && ! MEMBER_TYPE_FORCES_BLK (type, VOIDmode)
2046 /* BLKmode elements force BLKmode aggregate;
2047 else extract/store fields may lose. */
2048 && (TYPE_MODE (TREE_TYPE (type)) != BLKmode
2049 || TYPE_NO_FORCE_BLK (TREE_TYPE (type))))
2051 /* One-element arrays get the component type's mode. */
2052 if (simple_cst_equal (TYPE_SIZE (type),
2053 TYPE_SIZE (TREE_TYPE (type))))
2054 SET_TYPE_MODE (type, TYPE_MODE (TREE_TYPE (type)));
2056 SET_TYPE_MODE (type, mode_for_size_tree (TYPE_SIZE (type),
2059 if (TYPE_MODE (type) != BLKmode
2060 && STRICT_ALIGNMENT && TYPE_ALIGN (type) < BIGGEST_ALIGNMENT
2061 && TYPE_ALIGN (type) < GET_MODE_ALIGNMENT (TYPE_MODE (type)))
2063 TYPE_NO_FORCE_BLK (type) = 1;
2064 SET_TYPE_MODE (type, BLKmode);
2067 /* When the element size is constant, check that it is at least as
2068 large as the element alignment. */
2069 if (TYPE_SIZE_UNIT (element)
2070 && TREE_CODE (TYPE_SIZE_UNIT (element)) == INTEGER_CST
2071 /* If TYPE_SIZE_UNIT overflowed, then it is certainly larger than
2073 && !TREE_OVERFLOW (TYPE_SIZE_UNIT (element))
2074 && !integer_zerop (TYPE_SIZE_UNIT (element))
2075 && compare_tree_int (TYPE_SIZE_UNIT (element),
2076 TYPE_ALIGN_UNIT (element)) < 0)
2077 error ("alignment of array elements is greater than element size");
2083 case QUAL_UNION_TYPE:
2086 record_layout_info rli;
2088 /* Initialize the layout information. */
2089 rli = start_record_layout (type);
2091 /* If this is a QUAL_UNION_TYPE, we want to process the fields
2092 in the reverse order in building the COND_EXPR that denotes
2093 its size. We reverse them again later. */
2094 if (TREE_CODE (type) == QUAL_UNION_TYPE)
2095 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
2097 /* Place all the fields. */
2098 for (field = TYPE_FIELDS (type); field; field = DECL_CHAIN (field))
2099 place_field (rli, field);
2101 if (TREE_CODE (type) == QUAL_UNION_TYPE)
2102 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
2104 /* Finish laying out the record. */
2105 finish_record_layout (rli, /*free_p=*/true);
2113 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
2114 records and unions, finish_record_layout already called this
2116 if (TREE_CODE (type) != RECORD_TYPE
2117 && TREE_CODE (type) != UNION_TYPE
2118 && TREE_CODE (type) != QUAL_UNION_TYPE)
2119 finalize_type_size (type);
2121 /* We should never see alias sets on incomplete aggregates. And we
2122 should not call layout_type on not incomplete aggregates. */
2123 if (AGGREGATE_TYPE_P (type))
2124 gcc_assert (!TYPE_ALIAS_SET_KNOWN_P (type));
2127 /* Vector types need to re-check the target flags each time we report
2128 the machine mode. We need to do this because attribute target can
2129 change the result of vector_mode_supported_p and have_regs_of_mode
2130 on a per-function basis. Thus the TYPE_MODE of a VECTOR_TYPE can
2131 change on a per-function basis. */
2132 /* ??? Possibly a better solution is to run through all the types
2133 referenced by a function and re-compute the TYPE_MODE once, rather
2134 than make the TYPE_MODE macro call a function. */
2137 vector_type_mode (const_tree t)
2139 enum machine_mode mode;
2141 gcc_assert (TREE_CODE (t) == VECTOR_TYPE);
2143 mode = t->type.mode;
2144 if (VECTOR_MODE_P (mode)
2145 && (!targetm.vector_mode_supported_p (mode)
2146 || !have_regs_of_mode[mode]))
2148 enum machine_mode innermode = TREE_TYPE (t)->type.mode;
2150 /* For integers, try mapping it to a same-sized scalar mode. */
2151 if (GET_MODE_CLASS (innermode) == MODE_INT)
2153 mode = mode_for_size (TYPE_VECTOR_SUBPARTS (t)
2154 * GET_MODE_BITSIZE (innermode), MODE_INT, 0);
2156 if (mode != VOIDmode && have_regs_of_mode[mode])
2166 /* Create and return a type for signed integers of PRECISION bits. */
2169 make_signed_type (int precision)
2171 tree type = make_node (INTEGER_TYPE);
2173 TYPE_PRECISION (type) = precision;
2175 fixup_signed_type (type);
2179 /* Create and return a type for unsigned integers of PRECISION bits. */
2182 make_unsigned_type (int precision)
2184 tree type = make_node (INTEGER_TYPE);
2186 TYPE_PRECISION (type) = precision;
2188 fixup_unsigned_type (type);
2192 /* Create and return a type for fract of PRECISION bits, UNSIGNEDP,
2196 make_fract_type (int precision, int unsignedp, int satp)
2198 tree type = make_node (FIXED_POINT_TYPE);
2200 TYPE_PRECISION (type) = precision;
2203 TYPE_SATURATING (type) = 1;
2205 /* Lay out the type: set its alignment, size, etc. */
2208 TYPE_UNSIGNED (type) = 1;
2209 SET_TYPE_MODE (type, mode_for_size (precision, MODE_UFRACT, 0));
2212 SET_TYPE_MODE (type, mode_for_size (precision, MODE_FRACT, 0));
2218 /* Create and return a type for accum of PRECISION bits, UNSIGNEDP,
2222 make_accum_type (int precision, int unsignedp, int satp)
2224 tree type = make_node (FIXED_POINT_TYPE);
2226 TYPE_PRECISION (type) = precision;
2229 TYPE_SATURATING (type) = 1;
2231 /* Lay out the type: set its alignment, size, etc. */
2234 TYPE_UNSIGNED (type) = 1;
2235 SET_TYPE_MODE (type, mode_for_size (precision, MODE_UACCUM, 0));
2238 SET_TYPE_MODE (type, mode_for_size (precision, MODE_ACCUM, 0));
2244 /* Initialize sizetype and bitsizetype to a reasonable and temporary
2245 value to enable integer types to be created. */
2248 initialize_sizetypes (void)
2250 tree t = make_node (INTEGER_TYPE);
2251 int precision = GET_MODE_BITSIZE (SImode);
2253 SET_TYPE_MODE (t, SImode);
2254 TYPE_ALIGN (t) = GET_MODE_ALIGNMENT (SImode);
2255 TYPE_IS_SIZETYPE (t) = 1;
2256 TYPE_UNSIGNED (t) = 1;
2257 TYPE_SIZE (t) = build_int_cst (t, precision);
2258 TYPE_SIZE_UNIT (t) = build_int_cst (t, GET_MODE_SIZE (SImode));
2259 TYPE_PRECISION (t) = precision;
2261 set_min_and_max_values_for_integral_type (t, precision, true);
2264 bitsizetype = build_distinct_type_copy (t);
2267 /* Make sizetype a version of TYPE, and initialize *sizetype accordingly.
2268 We do this by overwriting the stub sizetype and bitsizetype nodes created
2269 by initialize_sizetypes. This makes sure that (a) anything stubby about
2270 them no longer exists and (b) any INTEGER_CSTs created with such a type,
2274 set_sizetype (tree type)
2277 int oprecision = TYPE_PRECISION (type);
2278 /* The *bitsizetype types use a precision that avoids overflows when
2279 calculating signed sizes / offsets in bits. However, when
2280 cross-compiling from a 32 bit to a 64 bit host, we are limited to 64 bit
2283 = MIN (oprecision + BITS_PER_UNIT_LOG + 1, MAX_FIXED_MODE_SIZE);
2285 = GET_MODE_PRECISION (smallest_mode_for_size (precision, MODE_INT));
2286 if (precision > HOST_BITS_PER_WIDE_INT * 2)
2287 precision = HOST_BITS_PER_WIDE_INT * 2;
2289 /* sizetype must be an unsigned type. */
2290 gcc_assert (TYPE_UNSIGNED (type));
2292 t = build_distinct_type_copy (type);
2293 /* We want to use sizetype's cache, as we will be replacing that type. */
2294 TYPE_CACHED_VALUES (t) = TYPE_CACHED_VALUES (sizetype);
2295 TYPE_CACHED_VALUES_P (t) = TYPE_CACHED_VALUES_P (sizetype);
2296 TREE_TYPE (TYPE_CACHED_VALUES (t)) = type;
2297 TYPE_UID (t) = TYPE_UID (sizetype);
2298 TYPE_IS_SIZETYPE (t) = 1;
2300 /* Replace our original stub sizetype. */
2301 memcpy (sizetype, t, tree_size (sizetype));
2302 TYPE_MAIN_VARIANT (sizetype) = sizetype;
2303 TYPE_CANONICAL (sizetype) = sizetype;
2305 /* sizetype is unsigned but we need to fix TYPE_MAX_VALUE so that it is
2306 sign-extended in a way consistent with force_fit_type. */
2307 max = TYPE_MAX_VALUE (sizetype);
2308 TYPE_MAX_VALUE (sizetype)
2309 = double_int_to_tree (sizetype, tree_to_double_int (max));
2311 t = make_node (INTEGER_TYPE);
2312 TYPE_NAME (t) = get_identifier ("bit_size_type");
2313 /* We want to use bitsizetype's cache, as we will be replacing that type. */
2314 TYPE_CACHED_VALUES (t) = TYPE_CACHED_VALUES (bitsizetype);
2315 TYPE_CACHED_VALUES_P (t) = TYPE_CACHED_VALUES_P (bitsizetype);
2316 TYPE_PRECISION (t) = precision;
2317 TYPE_UID (t) = TYPE_UID (bitsizetype);
2318 TYPE_IS_SIZETYPE (t) = 1;
2320 /* Replace our original stub bitsizetype. */
2321 memcpy (bitsizetype, t, tree_size (bitsizetype));
2322 TYPE_MAIN_VARIANT (bitsizetype) = bitsizetype;
2323 TYPE_CANONICAL (bitsizetype) = bitsizetype;
2325 fixup_unsigned_type (bitsizetype);
2327 /* Create the signed variants of *sizetype. */
2328 ssizetype = make_signed_type (oprecision);
2329 TYPE_IS_SIZETYPE (ssizetype) = 1;
2330 sbitsizetype = make_signed_type (precision);
2331 TYPE_IS_SIZETYPE (sbitsizetype) = 1;
2334 /* TYPE is an integral type, i.e., an INTEGRAL_TYPE, ENUMERAL_TYPE
2335 or BOOLEAN_TYPE. Set TYPE_MIN_VALUE and TYPE_MAX_VALUE
2336 for TYPE, based on the PRECISION and whether or not the TYPE
2337 IS_UNSIGNED. PRECISION need not correspond to a width supported
2338 natively by the hardware; for example, on a machine with 8-bit,
2339 16-bit, and 32-bit register modes, PRECISION might be 7, 23, or
2343 set_min_and_max_values_for_integral_type (tree type,
2352 min_value = build_int_cst (type, 0);
2354 = build_int_cst_wide (type, precision - HOST_BITS_PER_WIDE_INT >= 0
2356 : ((HOST_WIDE_INT) 1 << precision) - 1,
2357 precision - HOST_BITS_PER_WIDE_INT > 0
2358 ? ((unsigned HOST_WIDE_INT) ~0
2359 >> (HOST_BITS_PER_WIDE_INT
2360 - (precision - HOST_BITS_PER_WIDE_INT)))
2366 = build_int_cst_wide (type,
2367 (precision - HOST_BITS_PER_WIDE_INT > 0
2369 : (HOST_WIDE_INT) (-1) << (precision - 1)),
2370 (((HOST_WIDE_INT) (-1)
2371 << (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
2372 ? precision - HOST_BITS_PER_WIDE_INT - 1
2375 = build_int_cst_wide (type,
2376 (precision - HOST_BITS_PER_WIDE_INT > 0
2378 : ((HOST_WIDE_INT) 1 << (precision - 1)) - 1),
2379 (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
2380 ? (((HOST_WIDE_INT) 1
2381 << (precision - HOST_BITS_PER_WIDE_INT - 1))) - 1
2385 TYPE_MIN_VALUE (type) = min_value;
2386 TYPE_MAX_VALUE (type) = max_value;
2389 /* Set the extreme values of TYPE based on its precision in bits,
2390 then lay it out. Used when make_signed_type won't do
2391 because the tree code is not INTEGER_TYPE.
2392 E.g. for Pascal, when the -fsigned-char option is given. */
2395 fixup_signed_type (tree type)
2397 int precision = TYPE_PRECISION (type);
2399 /* We can not represent properly constants greater then
2400 2 * HOST_BITS_PER_WIDE_INT, still we need the types
2401 as they are used by i386 vector extensions and friends. */
2402 if (precision > HOST_BITS_PER_WIDE_INT * 2)
2403 precision = HOST_BITS_PER_WIDE_INT * 2;
2405 set_min_and_max_values_for_integral_type (type, precision,
2406 /*is_unsigned=*/false);
2408 /* Lay out the type: set its alignment, size, etc. */
2412 /* Set the extreme values of TYPE based on its precision in bits,
2413 then lay it out. This is used both in `make_unsigned_type'
2414 and for enumeral types. */
2417 fixup_unsigned_type (tree type)
2419 int precision = TYPE_PRECISION (type);
2421 /* We can not represent properly constants greater then
2422 2 * HOST_BITS_PER_WIDE_INT, still we need the types
2423 as they are used by i386 vector extensions and friends. */
2424 if (precision > HOST_BITS_PER_WIDE_INT * 2)
2425 precision = HOST_BITS_PER_WIDE_INT * 2;
2427 TYPE_UNSIGNED (type) = 1;
2429 set_min_and_max_values_for_integral_type (type, precision,
2430 /*is_unsigned=*/true);
2432 /* Lay out the type: set its alignment, size, etc. */
2436 /* Find the best machine mode to use when referencing a bit field of length
2437 BITSIZE bits starting at BITPOS.
2439 The underlying object is known to be aligned to a boundary of ALIGN bits.
2440 If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
2441 larger than LARGEST_MODE (usually SImode).
2443 If no mode meets all these conditions, we return VOIDmode.
2445 If VOLATILEP is false and SLOW_BYTE_ACCESS is false, we return the
2446 smallest mode meeting these conditions.
2448 If VOLATILEP is false and SLOW_BYTE_ACCESS is true, we return the
2449 largest mode (but a mode no wider than UNITS_PER_WORD) that meets
2452 If VOLATILEP is true the narrow_volatile_bitfields target hook is used to
2453 decide which of the above modes should be used. */
2456 get_best_mode (int bitsize, int bitpos, unsigned int align,
2457 enum machine_mode largest_mode, int volatilep)
2459 enum machine_mode mode;
2460 unsigned int unit = 0;
2462 /* Find the narrowest integer mode that contains the bit field. */
2463 for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
2464 mode = GET_MODE_WIDER_MODE (mode))
2466 unit = GET_MODE_BITSIZE (mode);
2467 if ((bitpos % unit) + bitsize <= unit)
2471 if (mode == VOIDmode
2472 /* It is tempting to omit the following line
2473 if STRICT_ALIGNMENT is true.
2474 But that is incorrect, since if the bitfield uses part of 3 bytes
2475 and we use a 4-byte mode, we could get a spurious segv
2476 if the extra 4th byte is past the end of memory.
2477 (Though at least one Unix compiler ignores this problem:
2478 that on the Sequent 386 machine. */
2479 || MIN (unit, BIGGEST_ALIGNMENT) > align
2480 || (largest_mode != VOIDmode && unit > GET_MODE_BITSIZE (largest_mode)))
2483 if ((SLOW_BYTE_ACCESS && ! volatilep)
2484 || (volatilep && !targetm.narrow_volatile_bitfield ()))
2486 enum machine_mode wide_mode = VOIDmode, tmode;
2488 for (tmode = GET_CLASS_NARROWEST_MODE (MODE_INT); tmode != VOIDmode;
2489 tmode = GET_MODE_WIDER_MODE (tmode))
2491 unit = GET_MODE_BITSIZE (tmode);
2492 if (bitpos / unit == (bitpos + bitsize - 1) / unit
2493 && unit <= BITS_PER_WORD
2494 && unit <= MIN (align, BIGGEST_ALIGNMENT)
2495 && (largest_mode == VOIDmode
2496 || unit <= GET_MODE_BITSIZE (largest_mode)))
2500 if (wide_mode != VOIDmode)
2507 /* Gets minimal and maximal values for MODE (signed or unsigned depending on
2508 SIGN). The returned constants are made to be usable in TARGET_MODE. */
2511 get_mode_bounds (enum machine_mode mode, int sign,
2512 enum machine_mode target_mode,
2513 rtx *mmin, rtx *mmax)
2515 unsigned size = GET_MODE_BITSIZE (mode);
2516 unsigned HOST_WIDE_INT min_val, max_val;
2518 gcc_assert (size <= HOST_BITS_PER_WIDE_INT);
2522 min_val = -((unsigned HOST_WIDE_INT) 1 << (size - 1));
2523 max_val = ((unsigned HOST_WIDE_INT) 1 << (size - 1)) - 1;
2528 max_val = ((unsigned HOST_WIDE_INT) 1 << (size - 1) << 1) - 1;
2531 *mmin = gen_int_mode (min_val, target_mode);
2532 *mmax = gen_int_mode (max_val, target_mode);
2535 #include "gt-stor-layout.h"